tag:theconversation.com,2011:/ca-fr/topics/sunscreen-212/articlesSunscreen – La Conversation2024-01-08T12:09:28Ztag:theconversation.com,2011:article/2196402024-01-08T12:09:28Z2024-01-08T12:09:28ZSunscreen: why wearing it even in winter could be a good idea<figure><img src="https://images.theconversation.com/files/567833/original/file-20240104-27-a4kzki.jpg?ixlib=rb-1.1.0&rect=11%2C0%2C3854%2C2590&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Sun's radiation can still damage our skin even in winter.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woman-using-sunscreen-257081962">Stanislav Nikolov/ Shutterstock</a></span></figcaption></figure><p>Sunscreen has taken centre stage in many skincare routines, especially among those hoping to prevent visible signs of ageing. But while it makes sense to wear sunscreen every day in the summer when the sun’s rays are most powerful, many may wonder whether there’s any benefit of wearing sunscreen daily in the winter months.</p>
<p>The sun’s radiation can reach us during all times of the year. This means that in both summer and winter, we are exposed to infrared radiation, as well as UVA and UVB rays.</p>
<p>UVB is mainly responsible for sunburn and DNA damage – and can also <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3709783/">cause skin cancers</a> as a result of long-term exposure. UVA radiation does contribute to these processes somewhat, but it’s less effective at doing so. UVA can penetrate deeper into the skin, however, which can damage the collagen – a key part of the skin that keeps it firm and elastic. This can cause the <a href="https://pubmed.ncbi.nlm.nih.gov/25234829/">skin to age faster</a>, leading to wrinkles, fine lines and changes in pigmentation.</p>
<p>The amount of UVA and UVB radiation that reaches the Earth’s surface changes across the seasons. This is due to the angle of the Sun in the sky, as well as other factors such as latitude and time of day.</p>
<p>For example, let’s compare how <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/php.12422">UVA and UVB radiation varies</a> at solar noon in London, UK and Kuala Lampur, Malaysia (which is near the equator).</p>
<p>In latitudes closer to the equator (such as in Kuala Lampur), the amount of UVA and UVB radiation throughout the year remains fairly consistent. But in higher latitudes, such as London, there’s almost no UVB radiation throughout the winter months – whereas there’s still some UVA radiation.</p>
<p>Not only that, but people living further from the equator may tend to spend less time exposed to the Sun in winter due to the colder temperatures and variable weather. And when they do go outside, they may cover their skin up – usually leaving only their face exposed to the Sun for much shorter periods of time.</p>
<p>But UVA radiation can still penetrate through clouds and windows. While our exposure to these rays is probably minimal, skin damage from UV exposure is <a href="https://www.sciencedirect.com/science/article/pii/S0079610706000162">accumulated over decades</a>, so anything that can be done to reduce exposure (and damage) over time may be beneficial. This is also true of UVB exposure – although it is less relevant in winter months at higher latitudes.</p>
<p>This may be where daily sunscreen use during the winter is still of benefit. Sunscreens are formulated to reduce exposure to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6978633/">both UVB and UVA rays</a> – although they are usually more effective at reducing exposure to UVB radiation. They have been designed in this way to prevent the most damaging effects of the Sun, such as sunburn and DNA damage. The impact of exposure to UVA radiation has only been considered more recently.</p>
<p>Numerous studies have shown regular sunscreen use over many years is effective at <a href="https://onlinelibrary.wiley.com/doi/10.1111/phpp.12109">preventing skin damage</a>, photoaging and skin cancers. The most robust trials suggest daily sunscreen use is most effective, but this will be dependent on the factors discussed above.</p>
<h2>The effects of altitude and snow</h2>
<p>One place where winter sunscreen use is especially important is when skiing or snowboarding – or when you’re otherwise going to be outside for extended periods of time, at higher altitudes on snow-covered mountains.</p>
<p>Both altitude and snow can increase the doses of <a href="https://www.who.int/news-room/questions-and-answers/item/radiation-ultraviolet-(uv)">UVA and UVB radiation</a> a person receives. Snow can reflect up to 80% of UV radiation emitted by the Sun – effectively almost doubling the doses received. Also, for every 1,000-foot increase in altitude, there’s a 10% increase in UV exposure. This is why it’s essential to protect the skin and eyes by wearing sunscreen, protective clothing and sunglasses that block both types of UV ray. This is also true when spending time in snowy environments, such as when hiking or skating.</p>
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<img alt="A man and a woman snowshoe through a snowy field on a sunny day." src="https://images.theconversation.com/files/567835/original/file-20240104-19-ml8ihz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567835/original/file-20240104-19-ml8ihz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567835/original/file-20240104-19-ml8ihz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567835/original/file-20240104-19-ml8ihz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567835/original/file-20240104-19-ml8ihz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567835/original/file-20240104-19-ml8ihz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567835/original/file-20240104-19-ml8ihz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Snow reflects UV radiation.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/snowshoe-walkers-running-powder-snow-beautiful-1279921384">Lukas Gojda/ Shutterstock</a></span>
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<p>Sunscreens are generally regarded as safe and tend to have few adverse effects, so you don’t need to worry too much about wearing one throughout the year. However, there are some points to consider, especially if you have skin conditions. For example, sunscreen can <a href="https://www.byrdie.com/does-sunscreen-cause-acne-or-help-it-7546147">exacerbate acne</a> and cause <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7759112/">irritation and allergic reactions</a> – although these are rare.</p>
<p>There are also emerging concerns from regulatory agencies about the <a href="https://jamanetwork.com/journals/jama/fullarticle/2759002">absorption of UV filters into the body</a>. However, the consequences of such absorption and the potential affects on health are not well defined and require more research.</p>
<p>Still, the benefits of sunscreen have been widely demonstrated – as has their safety. So if you want to prevent premature signs of ageing, it’s important to use sunscreen at all times you may be exposed to the Sun – especially in the summer months. While the benefits of wearing sunscreen in winter are less well defined, there’s probably no harm in wearing one if you want to.</p>
<p>If you decide to use sunscreen in winter, use ones that have broad spectrum five-star UVA protection. For day-to-day use, high SPF sunscreens are unlikely to provide a large benefit, particularly if spending only short periods outside. However, if skiing, a <a href="https://www.jaad.org/article/S0190-9622(17)31086-1/fulltext">high-SPF sunscreen</a> with five-star UVA protection would be beneficial.</p><img src="https://counter.theconversation.com/content/219640/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karl Lawrence has previously received funding from the sunscreen industry and hold patents related to sunscreen ingredients.</span></em></p>Regular sunscreen use over many years is shown to be effective at preventing skin damage, photoaging and skin cancers.Karl Lawrence, Research fellow, King's College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2160782023-12-27T20:26:50Z2023-12-27T20:26:50ZThinking of a(nother) tattoo this summer? What you need to know about sunburn, sweating and fading<p>More of us have tattoos than ever before. About <a href="https://mccrindle.com.au/article/tattoos-on-the-rise-among-aussies/">25% of Australians</a> are inked. </p>
<p>A tattoo can be a large investment in time, money and pain.</p>
<p>So how do you take care of your tattooed skin? Here’s what you need to know about sunburn, sweating and fading.</p>
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<strong>
Read more:
<a href="https://theconversation.com/tattoos-have-a-long-history-going-back-to-the-ancient-world-and-also-to-colonialism-165584">Tattoos have a long history going back to the ancient world – and also to colonialism</a>
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<h2>What’s a tattoo, dermatologically speaking?</h2>
<p>Tattoo inks are deposited in the <a href="https://dermnetnz.org/topics/the-structure-of-normal-skin">layer of skin</a> called the dermis. This layer contains sweat and oil glands, a blood supply, immune cells, collagen to support the skin’s structures, and fibroblasts, which produce collagen.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/563548/original/file-20231205-29-8elmtu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Cross-section of human skin showing epidermis and dermis" src="https://images.theconversation.com/files/563548/original/file-20231205-29-8elmtu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/563548/original/file-20231205-29-8elmtu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563548/original/file-20231205-29-8elmtu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563548/original/file-20231205-29-8elmtu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563548/original/file-20231205-29-8elmtu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563548/original/file-20231205-29-8elmtu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563548/original/file-20231205-29-8elmtu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Tattoo inks are inserted into the dermis.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/normal-skin-layers-crosssection-human-structure-2339540305">zonn hong/Shutterstock</a></span>
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<p>Fibroblasts <a href="https://www.sciencedirect.com/science/article/pii/S1470204511703400?via%3Dihub#bib74">take up</a> the ink particles, as do immune cells in the dermal tissue known as <a href="https://onlinelibrary.wiley.com/doi/10.1111/cup.12023">macrophages</a>. The ink particles also stick inside bundles of collagen.</p>
<p>Between these three mechanisms, the dermis holds tattoo inks so well they can be seen even on the 5,300-year-old <a href="https://www.sciencedirect.com/science/article/pii/S1296207415000023#bib0200">ice mummy Ötzi</a>. </p>
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<p>
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Read more:
<a href="https://theconversation.com/what-otzi-the-prehistoric-iceman-can-teach-us-about-the-use-of-tattoos-in-ceremonial-healing-or-religious-rites-168058">What Ötzi the prehistoric iceman can teach us about the use of tattoos in ceremonial healing or religious rites</a>
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<h2>Can I get a tattoo if I’m sunburnt?</h2>
<p>No, and many tattoo artists will not do it. During sunburn, your skin calls in extra immune cells and fluid to kill off and break down cells that have too much UV damage. </p>
<p>This <a href="https://link.springer.com/article/10.1007/s40257-017-0326-5">inflammation</a> can affect the tattoo ink deposits. You might not get the look you were after, with too much ink removed by your immune cells or swelling distorting the lines.</p>
<p>It’s much better to be proactive about sun protection before a tattoo, or at least be patient and reschedule when your skin has healed.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/i-cant-get-sunburnt-through-glass-shade-or-in-water-right-5-common-sunburn-myths-busted-150640">I can't get sunburnt through glass, shade or in water, right? 5 common sunburn myths busted</a>
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</em>
</p>
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<h2>How soon after my new tattoo can I go into the sun?</h2>
<p>There’s not much research on how soon you can expose your new tattoo to the sun. However, <a href="https://karger.com/drm/article/doi/10.1159/000533489/861717/An-Analysis-of-the-Content-and-Recommendations-of">most tattooists</a> advise you to avoid sun exposure while the tattoo heals, generally about three weeks.</p>
<p>This seems sensible, as your fresh tattoo is a type of wound.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/563560/original/file-20231205-25-bjthp5.jpg?ixlib=rb-1.1.0&rect=0%2C11%2C1920%2C1267&q=45&auto=format&w=1000&fit=clip"><img alt="Woman with sleeve tattoo heading to ocean, yoga mat under arm" src="https://images.theconversation.com/files/563560/original/file-20231205-25-bjthp5.jpg?ixlib=rb-1.1.0&rect=0%2C11%2C1920%2C1267&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/563560/original/file-20231205-25-bjthp5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563560/original/file-20231205-25-bjthp5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563560/original/file-20231205-25-bjthp5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563560/original/file-20231205-25-bjthp5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563560/original/file-20231205-25-bjthp5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563560/original/file-20231205-25-bjthp5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wait about three weeks before heading out into the sun with your new tattoo.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/crop-tattooed-woman-with-yoga-mat-against-river-4793296/">Anete Lusina/Pexels</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>Because the skin is damaged by inserting a needle, it’s not too surprising that the most common short-term complication is local inflammation with swelling, redness and discomfort at the tattoo site. There is an influx of immune cells to deal with the damage, much like a sunburn.</p>
<p>So, in one way, you should treat your new tattoo like sunburn and <a href="https://www.aad.org/public/everyday-care/injured-skin/burns/treat-sunburn">avoid sun exposure</a> while it heals. </p>
<p>But you shouldn’t use <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7442309/">sunscreen</a> on the tattoo in that time. That’s because sunscreen can <a href="https://www.futuremedicine.com/doi/10.2217/nnm.12.196?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed">enter the dermis</a> through the puncture wounds and cause more irritation. Cover your new tattoo with loose clothing instead.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/do-beach-cabanas-actually-protect-you-from-the-sun-199102">Do beach cabanas actually protect you from the sun?</a>
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</em>
</p>
<hr>
<h2>What happens if my tattoo gets sunburnt?</h2>
<p><a href="https://onlinelibrary.wiley.com/doi/10.1111/jdv.12093">Sunlight-induced reactions</a> to both new and existing tattoos are common. There’s usually swelling, itching or stinging on the tattoo site that can start immediately or develop over the course of a day. We’re not really sure why this happens.</p>
<p>Most of the time, these reactions are unpleasant but don’t require medical treatment, much like sunburn. </p>
<p>There is also a small amount of evidence that sunburn on a tattoo temporarily suppresses the skin’s immune system, allowing an <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1468-3083.2004.01121.x">infection</a> to become established.</p>
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<p>
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<strong>
Read more:
<a href="https://theconversation.com/common-skin-rashes-and-what-to-do-about-them-91518">Common skin rashes and what to do about them</a>
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<h2>Do tattoos increase my risk of skin cancer?</h2>
<p>Some <a href="https://www.sciencedirect.com/science/article/pii/S1470204511703400?via%3Dihub#bib4">ink components</a>, such as mercury or carbon black, are suspected cancer-causing agents when used in other applications. However, there’s <a href="https://www.sciencedirect.com/science/article/pii/S1470204511703400?via%3Dihub">no evidence</a> skin cancers are more likely in tattooed skin.</p>
<p>Tattoos make newly-developed skin cancers <a href="https://onlinelibrary.wiley.com/doi/10.1111/ajd.12219">more difficult to detect</a>. Besides making the lesion more difficult to spot in the first place, the colours of the tattoo interfere with your doctor’s assessment of the colours in the lesion, which can be an important sign of cancer.</p>
<p>So it’s a good idea to get familiar with the moles and freckles on a patch of skin before you’re inked, and check them yourself once a month for changes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/563561/original/file-20231205-15-fbd5ki.jpg?ixlib=rb-1.1.0&rect=2%2C2%2C995%2C663&q=45&auto=format&w=1000&fit=clip"><img alt="Man with tattoos spraying sunscreen on arms" src="https://images.theconversation.com/files/563561/original/file-20231205-15-fbd5ki.jpg?ixlib=rb-1.1.0&rect=2%2C2%2C995%2C663&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/563561/original/file-20231205-15-fbd5ki.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563561/original/file-20231205-15-fbd5ki.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563561/original/file-20231205-15-fbd5ki.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563561/original/file-20231205-15-fbd5ki.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563561/original/file-20231205-15-fbd5ki.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563561/original/file-20231205-15-fbd5ki.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Don’t use sunscreen on new tattoos but after about three weeks, go for it.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/tattooed-man-applying-sunscreen-cream-on-2338700035">Pixel-Shot/Shutterstock</a></span>
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<p>Red tattoos seem to be more prone to large but benign (non-cancerous) skin tumours called <a href="https://dermnetnz.org/topics/keratoacanthoma">keratoacanthomas</a>. These appear within a few months of tattooing, and often grow rapidly but then heal by themselves.</p>
<p>However, they can be difficult to distinguish from <a href="https://karger.com/drm/article/237/2/309/115107/Keratoacanthomas-and-Squamous-Cell-Carcinomas-on">squamous cell carcinomas</a> (a type of skin cancer). They can also damage underlying structures, such as nerves and muscles. So they often need to be removed anyway.</p>
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<p>
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<strong>
Read more:
<a href="https://theconversation.com/health-check-do-i-need-a-skin-cancer-check-48096">Health Check: do I need a skin cancer check?</a>
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</em>
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<h2>Can sunlight fade my tattoo?</h2>
<p>As tattoos age, they can fade a bit as some of the loose ink particles filter deeper into the dermis. Sun exposure can also degrade ink particles.</p>
<p>There’s limited research on this in human skin. After all, most people don’t want to fade their tattoos for science. So most of what we know is from research <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1600-0625.2009.00925.x">in mice</a>.</p>
<p>However, modern tattoo inks give you a strong colour. So in practice, you might not notice any fading for years.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/friday-essay-power-perils-and-rites-of-passage-the-history-of-the-female-tattoo-72725">Friday essay: power, perils and rites of passage – the history of the female tattoo</a>
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<h2>Does tattooed skin sweat differently to un-inked skin?</h2>
<p>This is an important question, because sweating is a major way our body avoids overheating in the summer. If you’ve got a full sleeve or your whole back is your canvas, that’s a significant amount of skin.</p>
<p>Since tattooing punctures the skin repeatedly, <a href="https://journals.physiology.org/doi/full/10.1152/japplphysiol.00427.2019?rfr_dat=cr_pub++0pubmed&url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org">sweat glands</a> in the dermis may be damaged.</p>
<p>But the research on tattoos’ impact on sweating is mixed and depends on what you are doing at the time.</p>
<p>In <a href="https://journals.physiology.org/doi/full/10.1152/japplphysiol.00427.2019?rfr_dat=cr_pub++0pubmed&url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org">one study</a>, researchers used a heatable suit to increase study participants’ internal body temperature by 1°C. Tattooed areas produced about 15% less sweat. It’s not clear if this is enough to increase the risk of heat stress.</p>
<p>However, when other researchers looked at sweating <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9463223/">induced by exercise</a> there was no effect in the volume of sweat between tattooed and un-tattooed skin.</p>
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<strong>
Read more:
<a href="https://theconversation.com/how-tattoos-became-fashionable-in-victorian-england-122487">How tattoos became fashionable in Victorian England</a>
</strong>
</em>
</p>
<hr>
<h2>Longer-term risks</h2>
<p>When performed under the clean conditions of a licenced tattoo parlour, tattooing is relatively safe. </p>
<p>But long term, some people develop <a href="https://link.springer.com/article/10.1007/s40257-017-0326-5">allergic reactions</a> to certain colours due to the different compounds in each, most commonly red dyes. This can cause lumps, scales, scarring or other visible changes.</p>
<p>So, what’s the most common long-term side effect of tattoos? Tattoo regret and wanting to have them <a href="https://link.springer.com/article/10.1007/s12016-016-8532-0">removed</a>.</p><img src="https://counter.theconversation.com/content/216078/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katie Lee receives funding from the National Health and Medical Research Council. </span></em></p><p class="fine-print"><em><span>Erin McMeniman does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A tattoo can be a large investment in time, money and pain. Here’s how to look after yours this summer.Katie Lee, PhD Candidate, The University of QueenslandErin McMeniman, Senior Lecturer Princess Alexandra Hospital Southside Clinical Unit and Casual Research Assistant, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2158932023-12-24T20:53:47Z2023-12-24T20:53:47ZA short history of sunscreen, from basting like a chook to preventing skin cancer<p>Australians have used commercial creams, lotions or gels to manage our skin’s sun exposure for nearly a century. </p>
<p>But why we do it, the preparations themselves, and whether they work, has changed over time.</p>
<p>In this short history of sunscreen in Australia, we look at how we’ve slathered, slopped and spritzed our skin for sometimes surprising reasons.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/4-myths-about-sunscreen-and-why-theyre-wrong-125879">4½ myths about sunscreen and why they're wrong</a>
</strong>
</em>
</p>
<hr>
<h2>At first, suncreams helped you ‘tan with ease’</h2>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/562563/original/file-20231129-23-98jddw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Advertisement for Hamilton's Sunburn Vanishing Cream" src="https://images.theconversation.com/files/562563/original/file-20231129-23-98jddw.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/562563/original/file-20231129-23-98jddw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1129&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562563/original/file-20231129-23-98jddw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1129&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562563/original/file-20231129-23-98jddw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1129&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562563/original/file-20231129-23-98jddw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1418&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562563/original/file-20231129-23-98jddw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1418&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562563/original/file-20231129-23-98jddw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1418&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This early sunscreen claimed you could ‘tan with ease’.</span>
<span class="attribution"><a class="source" href="https://trove.nla.gov.au/newspaper/page/11041390?searchTerm=Hamilton%20sun%20vanishing%20cream">Trove/NLA</a></span>
</figcaption>
</figure>
<p>Sunscreens have been available in Australia since the 30s. Chemist <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10120514/">Milton Blake</a> made one of the first.</p>
<p>He used a kerosene heater to cook batches of “sunburn vanishing cream”, scented with French perfume. </p>
<p>His backyard business became H.A. Milton (Hamilton) Laboratories, which still <a href="https://www.hamiltonsunandskin.com.au/history-of-hamilton">makes sunscreens today</a>. </p>
<p>Hamilton’s first cream <a href="https://trove.nla.gov.au/newspaper/article/128464119?searchTerm=Hamilton%20sun%20vanishing%20cream">claimed</a> you could “
Sunbathe in Comfort and TAN with ease”. According to modern standards, it would have had an SPF (or sun protection factor) of 2.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-how-does-sunscreen-work-what-is-spf-and-can-i-still-tan-with-it-on-88869">Explainer: how does sunscreen work, what is SPF and can I still tan with it on?</a>
</strong>
</em>
</p>
<hr>
<h2>The mirage of ‘safe tanning’</h2>
<p>A tan was considered a “<a href="https://trove.nla.gov.au/newspaper/article/21611069?searchTerm=sunburn%20lotion">modern complexion</a>” and for most of the 20th century, you might put something on your skin to help gain one. That’s when “safe tanning” (without burning) was thought possible.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/562843/original/file-20231130-27-l79asi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Coppertone advertisement showing tanned woman in bikini" src="https://images.theconversation.com/files/562843/original/file-20231130-27-l79asi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/562843/original/file-20231130-27-l79asi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=862&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562843/original/file-20231130-27-l79asi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=862&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562843/original/file-20231130-27-l79asi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=862&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562843/original/file-20231130-27-l79asi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1083&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562843/original/file-20231130-27-l79asi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1083&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562843/original/file-20231130-27-l79asi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1083&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This 1967 Coppertone advertisement urged you to ‘tan, not burn’.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/91591049@N00/15224409766/in/photolist-pck5By-nY3gWR-86iQ6o">SenseiAlan/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Sunburn was known to be caused by the <a href="https://www.cancercouncil.com.au/cancer-prevention/sun-protection/understanding-uv-radiation/what-is-uv-radiation/">UVB component</a> of ultraviolet (UV) light. UVA, however, was thought not to be involved in burning; it was just thought to darken the skin pigment melanin. So, medical authorities advised that by using a sunscreen that filtered out UVB, you could “safely tan” without burning.</p>
<p>But that was wrong.</p>
<p>From the 70s, medical research suggested UVA <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/exd.12388">penetrated damagingly deep</a> into the skin, causing ageing effects such as sunspots and wrinkles. And both <a href="https://www.cancercouncil.com.au/cancer-prevention/sun-protection/understanding-uv-radiation/what-is-uv-radiation/">UVA and UVB</a> could cause skin cancer.</p>
<p>Sunscreens from the 80s sought to be “<a href="https://theconversation.com/how-to-pick-the-right-sunscreen-when-youre-blinded-by-choice-125881">broad spectrum</a>” – they filtered both UVB and UVA.</p>
<p>Researchers consequently recommended sunscreens for <a href="https://www.sbs.com.au/language/english/en/article/skin-cancer-in-australia-what-are-the-risks-and-how-to-protect-yourself/sa022ydq1">all skin tones</a>, including for preventing sun damage in people with <a href="https://www.skincancer.org/skin-cancer-information/skin-cancer-skin-of-color/">dark skin</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sun-damage-and-cancer-how-uv-radiation-affects-our-skin-34538">Sun damage and cancer: how UV radiation affects our skin</a>
</strong>
</em>
</p>
<hr>
<h2>Delaying burning … or encouraging it?</h2>
<p>Up to the 80s, sun preparations ranged from something that claimed to delay burning, to preparations that actively encouraged it to get that desirable tan – think, baby oil or coconut oil. Sun-worshippers even raided the kitchen cabinet, slicking olive oil on their skin.</p>
<p>One manufacturer’s “sun lotion” might effectively filter UVB; another’s merely basted you like a roast chicken.</p>
<p>Since labelling laws before the 80s didn’t require manufacturers to list the ingredients, it was often hard for consumers to tell which was which.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-should-i-add-sunscreen-to-my-skincare-routine-now-its-getting-hotter-213453">How should I add sunscreen to my skincare routine now it's getting hotter?</a>
</strong>
</em>
</p>
<hr>
<h2>At last, SPF arrives to guide consumers</h2>
<p>In the 70s, two Queensland researchers, Gordon Groves and Don Robertson, developed tests for sunscreens – sometimes experimenting on students or colleagues. They printed their ranking <a href="https://trove.nla.gov.au/newspaper/article/116399802?searchTerm=guide%20to%20sunburn%20protection">in the newspaper</a>, which the public could use to choose a product. </p>
<p>An Australian sunscreen manufacturer then asked the federal health department to regulate the industry. The company wanted standard definitions to market their products, backed up by consistent lab testing methods.</p>
<p><a href="https://store.standards.org.au/product/as-2604-1986">In 1986</a>, after years of consultation with manufacturers, researchers and consumers, Australian Standard AS2604 gave a specified a testing method, based on the Queensland researchers’ work. We also had a way of expressing how well sunscreens worked – the <a href="https://theconversation.com/explainer-how-does-sunscreen-work-what-is-spf-and-can-i-still-tan-with-it-on-88869">sun protection factor or SPF</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/562856/original/file-20231130-17-70ggq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Sunscreen products with various SPF labels" src="https://images.theconversation.com/files/562856/original/file-20231130-17-70ggq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/562856/original/file-20231130-17-70ggq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=257&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562856/original/file-20231130-17-70ggq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=257&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562856/original/file-20231130-17-70ggq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=257&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562856/original/file-20231130-17-70ggq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=323&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562856/original/file-20231130-17-70ggq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=323&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562856/original/file-20231130-17-70ggq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=323&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Consumers could pick their product based on the sun protection factor or SPF.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/set-sunscreen-products-on-turquoise-background-2291735329">Shutterstock</a></span>
</figcaption>
</figure>
<p>This is the ratio of how long it takes a fair-skinned person to burn using the product compared with how long it takes to burn without it. So a cream that protects the skin sufficiently so it takes 40 minutes to burn instead of 20 minutes has an SPF of 2.</p>
<p>Manufacturers liked SPF because businesses that invested in clever chemistry could distinguish themselves in marketing. Consumers liked SPF because it was easy to understand – the higher the number, the better the protection.</p>
<p>Australians, encouraged from 1981 by the <a href="https://www.youtube.com/watch?v=b7nocIenCYg%22">Slip! Slop! Slap!</a> nationwide skin cancer campaign, could now “slop” on a sunscreen knowing the degree of protection it offered.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-pick-the-right-sunscreen-when-youre-blinded-by-choice-125881">How to pick the right sunscreen when you're blinded by choice</a>
</strong>
</em>
</p>
<hr>
<h2>How about skin cancer?</h2>
<p>It wasn’t until 1999 that research proved that using sunscreen prevents skin cancer. Again, we have Queensland to thank, specifically the residents of Nambour. They took part in a <a href="https://pubmed.ncbi.nlm.nih.gov/10475183/">trial</a> for nearly five years, carried out by a research team led by Adele Green of the Queensland Institute of Medical Research. Using sunscreen daily over that time reduced rates of squamous cell carcinoma (a common form of skin cancer) by about 60%.</p>
<p>Follow-up <a href="https://pubmed.ncbi.nlm.nih.gov/21135266/">studies</a> in 2011 and 2013 showed regular sunscreen use almost halved the rate of melanoma and <a href="https://pubmed.ncbi.nlm.nih.gov/23732711/">slowed skin ageing</a>. But there was no impact on rates of <a href="https://www.cancer.org.au/cancer-information/types-of-cancer/non-melanoma-skin-cancer">basal cell carcinoma</a>, another common skin cancer. </p>
<p>By then, researchers had shown sunscreen stopped sunburn, and stopping sunburn would prevent at least some types of skin cancer.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1729258841827635600"}"></div></p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/theres-a-serious-ethical-problem-with-some-sunscreen-testing-methods-and-youre-probably-not-aware-of-it-195359">There's a serious ethical problem with some sunscreen testing methods – and you're probably not aware of it</a>
</strong>
</em>
</p>
<hr>
<h2>What’s in sunscreen today?</h2>
<p>An effective sunscreen uses one or more active ingredients in a cream, lotion or gel. The <a href="https://theconversation.com/explainer-how-does-sunscreen-work-what-is-spf-and-can-i-still-tan-with-it-on-88869">active ingredient</a> either works:</p>
<ul>
<li><p>“chemically” by absorbing UV and converting it to heat. Examples include PABA (para-aminobenzoic acid) and benzyl salicylate, or</p></li>
<li><p>“physically” by blocking the UV, such as zinc oxide or titanium dioxide. </p></li>
</ul>
<p>Physical blockers at first had limited cosmetic appeal because they were opaque pastes. (Think cricketers with zinc smeared on their noses.) </p>
<p>With microfine particle technology from the 90s, sunscreen manufacturers could then use a combination of chemical absorbers and physical blockers to achieve high degrees of sun protection in a cosmetically acceptable formulation.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/research-check-should-we-be-worried-that-the-chemicals-from-sunscreen-can-get-into-our-blood-116738">Research Check: should we be worried that the chemicals from sunscreen can get into our blood?</a>
</strong>
</em>
</p>
<hr>
<h2>Where now?</h2>
<p>Australians have embraced sunscreen, but they still don’t apply enough <a href="https://www.cancervic.org.au/get-support/stories/australians-dont-apply-enough-sunscreen.html">or</a> reapply often enough.</p>
<p>Although some people are concerned sunscreen will block the skin’s ability to <a href="https://theconversation.com/should-i-be-getting-my-vitamin-d-levels-checked-211268">make vitamin D</a> this is unlikely. That’s because even SPF50 sunscreen doesn’t filter out all UVB.</p>
<p>There’s also concern about the active ingredients in sunscreen <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9652235/">getting into the environment</a> and whether their <a href="https://www.fda.gov/drugs/news-events-human-drugs/spotlight-cder-science-new-fda-study-shines-light-sunscreen-absorption">absorption by our bodies</a> is a problem.</p>
<p>Sunscreens have evolved from something that at best offered mild protection to effective, easy-to-use products that stave off the harmful effects of UV. They’ve evolved from something only people with fair skin used to a product for anyone.</p>
<p>Remember, slopping on sunscreen is just one part of sun protection. Don’t forget to also slip (protective clothing), slap (hat), seek (shade) and slide (sunglasses).</p><img src="https://counter.theconversation.com/content/215893/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laura Dawes does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Early products focused on tanning. Others roasted you like a chicken. Which of these claims can you remember?Laura Dawes, Research Fellow in Medico-Legal History, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2170972023-12-19T19:01:49Z2023-12-19T19:01:49ZWhat’s the difference between physical and chemical sunscreens? And which one should you choose?<figure><img src="https://images.theconversation.com/files/561796/original/file-20231127-29-cr1fq0.jpg?ixlib=rb-1.1.0&rect=42%2C21%2C7092%2C4557&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/attractive-woman-healthy-skin-applying-sunscreen-288608612">Shutterstock</a></span></figcaption></figure><p>Sun exposure can <a href="https://www.researchgate.net/publication/353329938_The_role_of_bacterial_cellulose_loaded_with_plant_phenolics_in_prevention_of_UV-induced_skin_damage">accelerate ageing</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/33640513/">cause</a> skin burns, erythema (a skin reaction), skin cancer, melasmas (or sun spots) and other forms of hyperpigmentation – all triggered by <a href="https://pubmed.ncbi.nlm.nih.gov/29874551/">solar ultraviolet radiation</a>. </p>
<p>Approximately 80% of skin cancer cases in people engaged in outdoor activities are <a href="https://pubmed.ncbi.nlm.nih.gov/33197435/">preventable</a> by decreasing sun exposure. This can be done in lots of ways including wearing <a href="https://pubmed.ncbi.nlm.nih.gov/31978412/">protective clothing or sunscreens</a>.</p>
<p>But not all sunscreens work in the same way. You might have heard of “physical” and “chemical” sunscreens. What’s the difference and which one is right for you?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-should-i-add-sunscreen-to-my-skincare-routine-now-its-getting-hotter-213453">How should I add sunscreen to my skincare routine now it's getting hotter?</a>
</strong>
</em>
</p>
<hr>
<h2>How sunscreens are classified</h2>
<p>Sunscreens are <a href="https://pubmed.ncbi.nlm.nih.gov/33571844/">grouped</a> by their use of active <a href="https://pubmed.ncbi.nlm.nih.gov/35215026/">inorganic and organic ultraviolet (UV) filters</a>. Chemical sunscreens use organic filters such as <a href="https://www.science.org.au/curious/people-medicine/deciphering-label-your-sunscreen-bottle">cinnamates</a> (chemically related to cinnamon oil) and benzophenones. Physical sunscreens (sometimes called mineral sunscreens) use inorganic filters such as <a href="https://www.science.org.au/curious/people-medicine/deciphering-label-your-sunscreen-bottle">titanium and zinc oxide</a>.</p>
<p>These filters <a href="https://pubmed.ncbi.nlm.nih.gov/32335182/">prevent the effects of UV radiation</a> on the skin. </p>
<p>Organic UV filters are known as chemical filters because the molecules in them change to stop UV radiation reaching the skin. Inorganic UV filters are known as physical filters, because they work through physical means, such as <a href="https://pubmed.ncbi.nlm.nih.gov/35215026/">blocking, scattering and reflection</a> of UV radiation to prevent skin damage.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-how-does-sunscreen-work-what-is-spf-and-can-i-still-tan-with-it-on-88869">Explainer: how does sunscreen work, what is SPF and can I still tan with it on?</a>
</strong>
</em>
</p>
<hr>
<h2>Nano versus micro</h2>
<p>The effectiveness of the filters in physical sunscreen depends on factors including the size of the particle, how it’s mixed into the cream or lotion, the amount used and the <a href="https://www.ncbi.nlm.nih.gov/books/NBK592413/#:%7E:text=The%20index%20of%20refraction%20(n,the%20speed%20of%20light%20c.)">refraction index</a> (the speed light travels through a substance) of each filter. </p>
<p>When the particle size in physical sunscreens is large, it causes the light to be scattered and reflected more. That means physical <a href="https://www.researchgate.net/publication/363005590_Sunscreen_testing_A_critical_perspective_and_future_roadmap">sunscreens can be more obvious</a> on the skin, which can reduce their cosmetic appeal. </p>
<p>Nanoparticulate forms of physical sunscreens (with tiny particles smaller than 100 nanometers) can improve the cosmetic appearance of creams on the skin and UV protection, because the particles in this size range absorb more radiation than they reflect. These are sometimes labelled as “invisible” zinc or mineral formulations and are <a href="https://www.racgp.org.au/afp/2016/june/the-safety-of-nanoparticles-in-sunscreens-an-updat#ref-3">considered safe</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/561798/original/file-20231127-29-xpm7i4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man puts zinc cream across nose" src="https://images.theconversation.com/files/561798/original/file-20231127-29-xpm7i4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/561798/original/file-20231127-29-xpm7i4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/561798/original/file-20231127-29-xpm7i4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/561798/original/file-20231127-29-xpm7i4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/561798/original/file-20231127-29-xpm7i4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/561798/original/file-20231127-29-xpm7i4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/561798/original/file-20231127-29-xpm7i4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Physical sunscreens may be more obvious on the skin.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/surfer-putting-face-sunscreen-lotion-before-1779554906">Shutterstock</a></span>
</figcaption>
</figure>
<h2>So how do chemical sunscreens work?</h2>
<p>Chemical UV filters work by absorbing high-energy UV rays. This leads to the filter molecules interacting with sunlight and changing chemically. </p>
<p>When molecules return to their ground (or lower energy) state, they <a href="https://pubmed.ncbi.nlm.nih.gov/33640513/">release energy</a> as heat, distributed all over the skin. This may lead to uncomfortable reactions for people with skin sensitivity.</p>
<p>Generally, UV filters are meant to stay on the epidermis (the first skin layer) surface to protect it from UV radiation. When they enter into the dermis (the connective tissue layer) and bloodstream, this can lead to skin sensitivity and <a href="https://pubmed.ncbi.nlm.nih.gov/33571844/">increase the risk of toxicity</a>. The <a href="https://www.sciencedirect.com/science/article/pii/S0169409X20300077">safety profile</a> of chemical UV filters may depend on whether their small molecular size allows them to penetrate the skin. </p>
<p>Chemical sunscreens, compared to physical ones, cause more adverse reactions in the skin because of chemical changes in their molecules. In addition, some chemical filters, such as <a href="https://www.sciencedirect.com/topics/chemistry/dibenzoylmethane">dibenzoylmethane</a> tend to break down after UV exposure. These degraded products can no longer protect the skin against UV and, if they penetrate the skin, can <a href="https://pubmed.ncbi.nlm.nih.gov/32084432/">cause cell damage</a>.</p>
<p>Due to their stability – that is, how well they retain product integrity and effectiveness when exposed to sunlight – physical sunscreens may be <a href="https://pubmed.ncbi.nlm.nih.gov/21292345/">more suitable</a> for children and people with skin allergies.</p>
<p>Although sunscreen filter ingredients can rarely cause true allergic dermatitis, patients with photodermatoses (where the skin reacts to light) and eczema have <a href="https://pubmed.ncbi.nlm.nih.gov/21292345/">higher risk</a> and should take care and seek advice. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/theres-a-serious-ethical-problem-with-some-sunscreen-testing-methods-and-youre-probably-not-aware-of-it-195359">There's a serious ethical problem with some sunscreen testing methods – and you're probably not aware of it</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/561800/original/file-20231127-19-l879ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="woman compares sunscreen labels in pharmacy" src="https://images.theconversation.com/files/561800/original/file-20231127-19-l879ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/561800/original/file-20231127-19-l879ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/561800/original/file-20231127-19-l879ck.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/561800/original/file-20231127-19-l879ck.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/561800/original/file-20231127-19-l879ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/561800/original/file-20231127-19-l879ck.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/561800/original/file-20231127-19-l879ck.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">With lots of sunscreens on offer, it can be hard to decide which type is right for you.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/taking-sunscreen-lotion-shelves-pharmacy-store-1073742833">Shutterstock</a></span>
</figcaption>
</figure>
<h2>What to look for</h2>
<p>The best way to check if you’ll have a reaction to a physical or chemical sunscreen is to <a href="https://www.medicalnewstoday.com/articles/patch-test-skincare">patch test</a> it on a small area of skin. </p>
<p>And the <a href="https://www.racgp.org.au/afp/2016/june/the-safety-of-nanoparticles-in-sunscreens-an-updat#ref-3">best sunscreen to choose</a> is one that provides broad-spectrum protection, is water and sweat-resistant, has a high sun protection factor (SPF), is easy to apply and has a low allergy risk.</p>
<p>Health authorities recommend sunscreen to prevent sun damage and cancer. Chemical sunscreens have the potential to penetrate the skin and may cause irritation for some people. Physical sunscreens are considered safe and effective and nanoparticulate formulations can increase their appeal and ease of use.</p><img src="https://counter.theconversation.com/content/217097/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Yousuf Mohammed receives funding from U.S FDA grants. This article reflects the views of the author and should not be construed to represent views or policies.</span></em></p><p class="fine-print"><em><span>Khanh Phan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Not all sunscreens work the same way and some might irritate people with sensitive skin.Yousuf Mohammed, Dermatology researcher, The University of QueenslandKhanh Phan, Postdoctoral research associate, Frazer Institute, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2134532023-10-11T03:12:00Z2023-10-11T03:12:00ZHow should I add sunscreen to my skincare routine now it’s getting hotter?<figure><img src="https://images.theconversation.com/files/551609/original/file-20231003-17-n2lo07.jpg?ixlib=rb-1.1.0&rect=14%2C110%2C4905%2C3164&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/xOEmZX6YSu8">Annie Spratt/Unsplash</a></span></figcaption></figure><p>Sun exposure is the number one cause of skin cancer – including the most deadly form, melanoma. High levels of sun exposure cause <a href="https://europepmc.org/article/MED/26437734#id580549">an estimated 7,200 melanomas in Australia each year</a>. </p>
<p>Too much sun exposure can also lead to premature ageing, resulting in wrinkles, fine lines and age spots. </p>
<p>Can a tweak to your skincare routine help prevent this?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sunscreen-heres-why-its-an-anti-ageing-skincare-essential-187322">Sunscreen: here’s why it’s an anti-ageing skincare essential</a>
</strong>
</em>
</p>
<hr>
<h2>When should I start wearing sunscreen?</h2>
<p>In Australia, we are advised to <a href="https://pubmed.ncbi.nlm.nih.gov/30681231/">wear sunscreen</a> on days when the ultraviolet (UV) index reaches three or higher. That’s year-round for much of Australia. The weather forecast or the Cancer Council’s free <a href="https://www.sunsmart.com.au/resources/sunsmart-app">SunSmart app</a> are easy ways to check the UV Index.</p>
<p>Besides “primary sunscreens”, which are dedicated sun-protection products, a sun protection factor (SPF) is also found in many beauty products, such as foundations, powders and moisturisers. These are called “secondary sunscreens” because they have a primary purpose other than sun protection. </p>
<p>Primary sunscreens are regulated by the <a href="https://www.tga.gov.au/news/news/about-sunscreens#_Sun_protection_factor">Therapeutic Goods Administration</a> and the SPF must be determined by testing on human skin. SPF measures how quickly skin burns with and without the sunscreen under intense UV light. If the skin takes ten seconds to burn with no sunscreen, and 300 seconds to burn with the sunscreen, the SPF is 30 (300 divided by 10).</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1617699959146688514"}"></div></p>
<h2>Is the SPF in makeup or moisturisers enough to protect me the whole day?</h2>
<p>Simple answer? No. SPF 30 mixed into foundation is not going to be as effective as a primary SPF 30 sunscreen. </p>
<p>Also, when people use a moisturiser or makeup that includes SPF, they generally don’t do the three key steps that make sunscreens effective: </p>
<ol>
<li>putting a thick enough amount on</li>
<li>covering all sun exposed areas</li>
<li>reapplying regularly when outdoors for a sustained amount of time.</li>
</ol>
<p>One <a href="https://pubmed.ncbi.nlm.nih.gov/37632801/">study</a> had 39 participants apply their usual SPF makeup/moisturisers and photographed them with UV photography in the morning, then again in the afternoon, without reapplying during the day. The UV photography allowed the researchers to visualise how much protection these products were still providing. </p>
<p>They found participants missed some facial areas with the initial application and the SPF products provided less coverage by the afternoon.</p>
<figure class="align-right ">
<img alt="Woman applies makeup" src="https://images.theconversation.com/files/551610/original/file-20231003-27-zqq5eo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/551610/original/file-20231003-27-zqq5eo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551610/original/file-20231003-27-zqq5eo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551610/original/file-20231003-27-zqq5eo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551610/original/file-20231003-27-zqq5eo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551610/original/file-20231003-27-zqq5eo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551610/original/file-20231003-27-zqq5eo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Consider how much you’re using.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/woman-in-black-blazer-and-white-shirt-4612152/">Pexels/Cottonbro Studio</a></span>
</figcaption>
</figure>
<p>Another consideration is the product type. Liquid foundation may be applied more thickly than powder makeup, which is generally lightly applied. </p>
<p>The <a href="https://www.tga.gov.au/products/medicines/sunscreens">Therapeutic Goods Administration</a> tests primary sunscreens so they’re effective when applied at 2mg per 2 square centimetres of skin.</p>
<p>For the face, ears and neck, this is about one teaspoon (5mL) – are you applying that much powder?</p>
<p>It’s unlikely people will cake on their moisturiser thickly and reapply during the day, so these products aren’t effective sun protection if outdoors for a sustained amount of time when used alone.</p>
<h2>If skin products with SPF aren’t giving me better protection, should I stop using them?</h2>
<p>These products can still serve a protective purpose, as <a href="https://onlinelibrary.wiley.com/doi/10.1111/srt.13010">some research</a> suggests layering sunscreen and makeup products may help to cover areas that were missed during a single application. </p>
<p>When layering, SPF factors are not additive. If wearing an SPF 30 sunscreen and makeup with SPF 15, that doesn’t equal SPF 45. You will be getting the protection from the highest product (in this scenario, it’s the SPF 30). </p>
<p>A good metaphor is SPF in makeup is like “icing on the cake”. Use it as an add-on and if areas were missed with the initial sunscreen application, then there is another chance to cover all areas with the SPF makeup.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-how-does-sunscreen-work-what-is-spf-and-can-i-still-tan-with-it-on-88869">Explainer: how does sunscreen work, what is SPF and can I still tan with it on?</a>
</strong>
</em>
</p>
<hr>
<h2>Should I apply sunscreen before or after makeup?</h2>
<p>It depends on whether you’re using a chemical or physical sunscreen. Chemical sunscreens need to absorb into the skin to block and absorb the sun’s rays, whereas physical sunscreens sit on the surface of the skin and act as a shield. </p>
<p>When the main ingredient is zinc oxide or titanium dioxide, it’s a physical sunscreen – think the classic zinc sticks you used to apply to your nose and lips at the beach. Physical sunscreens are recommended for people with sensitive skin and although they used to be pretty thick and sticky, newer versions feel more like chemical sunscreens. </p>
<p>For maximum sun protection when using chemical sunscreens, apply sunscreen first, followed by moisturiser, then makeup. Give the sunscreen a few minutes to dry and sink into the skin before starting to put on other products. Chemical sunscreen should be applied 20 minutes before going outdoors.</p>
<figure class="align-center ">
<img alt="Man puts sunscreen on his face" src="https://images.theconversation.com/files/551611/original/file-20231003-25-4yrdir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551611/original/file-20231003-25-4yrdir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551611/original/file-20231003-25-4yrdir.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551611/original/file-20231003-25-4yrdir.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551611/original/file-20231003-25-4yrdir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551611/original/file-20231003-25-4yrdir.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551611/original/file-20231003-25-4yrdir.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Give chemical sunscreen a few minutes to dry before applying moisturiser.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/man-putting-on-cream-on-his-face-7433339/">Pexels/August de Richelieu</a></span>
</figcaption>
</figure>
<p>When using a physical sunscreen, first apply moisturisers, followed by sunscreen, and then makeup.</p>
<p>When reapplying sunscreen, it’s recommended to wash off makeup and start fresh, but this isn’t going to be practical for many people, so gently patting sunscreen over makeup is another option. Physical sunscreens will be most effective for reapplication over makeup.</p>
<h2>What type of sunscreen should I use?</h2>
<p>The best sunscreen is the one you actually like to apply. Protecting your skin on a daily basis (and not just for trips to the beach!) is a must in Australia’s high UV climate, and should be done with a primary sunscreen.</p>
<p>Look for sunscreens that have the label “broad spectrum”, which means it covers for UVA and UVB, and has at least SPF30. </p>
<p>Then experiment with features like matte finish, milk texture or fragrance-free to find a sunscreen you like.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-pick-the-right-sunscreen-when-youre-blinded-by-choice-125881">How to pick the right sunscreen when you're blinded by choice</a>
</strong>
</em>
</p>
<hr>
<p>No sunscreen provides 100% protection so you should also use other sun protection such as protective clothing, hats, sunglasses, using shade and avoiding the sun during peak UV hours.</p>
<p>Skin care and makeup products with SPF is better than nothing, but don’t rely solely on your morning makeup for sun protection the entire day.</p><img src="https://counter.theconversation.com/content/213453/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Monika Janda receives funding from National Health and Medical Research Council, Medical Research Future Fund and Australian Cancer Research Foundation. </span></em></p><p class="fine-print"><em><span>Katie Lee receives funding from the National Health and Medical Research Council. </span></em></p><p class="fine-print"><em><span>Caitlin Horsham does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Does SPF in makeup and moisturisers provide effective sun protection?Monika Janda, Professor in Behavioural Science, The University of QueenslandCaitlin Horsham, Research Manager, The University of QueenslandKatie Lee, PhD Candidate, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2093712023-08-11T12:38:49Z2023-08-11T12:38:49ZSkin cancer screening guidelines can seem confusing – three skin cancer researchers explain when to consider getting checked<figure><img src="https://images.theconversation.com/files/539388/original/file-20230725-17-v7y631.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C5454%2C3714&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A history of sunburns may put people at greater risk of developing skin cancer.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/young-womans-back-being-examined-at-a-royalty-free-image/166130792?phrase=skin+cancer+screening&adppopup=true">dnberty/iStock via Getty Images Plus</a></span></figcaption></figure><p><em>Protecting oneself from the summer sun and its damaging ultraviolet rays is often not straightforward. And public health messaging around when and how to be screened for skin cancer has become somewhat confusing.</em></p>
<p><em>In April 2023, the U.S. Preventive Services Task Force, an independent national panel of science experts, provided <a href="https://doi.org/10.1001/jama.2023.4342">updated recommendations on skin cancer</a> screening following a <a href="https://doi.org/10.1001/jama.2023.3262">systematic review of existing research</a>. The task force concluded that the evidence does not support annual widespread skin screening of adolescents and adults, but that catching cancers at the earliest stages reduces the risk of death from skin cancer.</em> </p>
<p><em>At first glance, these statements appear conflicting. So The Conversation asked dermatology experts <a href="https://som.cuanschutz.edu/Profiles/Faculty/Profile/7842">Enrique Torchia</a>, <a href="https://som.cuanschutz.edu/Profiles/Faculty/Profile/20820">Tamara Terzian</a> and <a href="https://coloradosph.cuanschutz.edu/resources/directory/directory-profile/Box-Neil-UCD4553">Neil Box</a> to help unravel the task force recommendations, what they mean for the public and how people can minimize their skin cancer risk.</em></p>
<h2>How common is skin cancer in the US?</h2>
<p>Skin cancer affects about 6 million Americans yearly, according to the Centers for Disease Control and Prevention. This number is <a href="https://www.cancer.org/research/cancer-facts-statistics/all-cancer-facts-figures/2023-cancer-facts-figures.html">more than all other types of cancers combined</a>. </p>
<p><a href="https://medschool.cuanschutz.edu/colorado-cancer-center/for-patients-families/cancers-we-treat/skin-cancer">Basal cell carcinoma and squamous cell carcinoma</a> – collectively known as keratinocyte cancers – account for more than <a href="https://doi.org/10.1016/j.jaad.2021.03.109">97% of skin cancer cases</a>, but invasive melanomas cause the most deaths. Keratinocyte cancers arise from basal cells and the more differentiated squamous cells in the epidermis – the top layer of skin – whereas melanoma comes from melanocytes found at the junction of the epidermis and the dermis, or middle layer. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542208/original/file-20230810-21547-6nm4f8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram showing human skin layers." src="https://images.theconversation.com/files/542208/original/file-20230810-21547-6nm4f8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542208/original/file-20230810-21547-6nm4f8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542208/original/file-20230810-21547-6nm4f8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542208/original/file-20230810-21547-6nm4f8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542208/original/file-20230810-21547-6nm4f8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542208/original/file-20230810-21547-6nm4f8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542208/original/file-20230810-21547-6nm4f8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The majority of skin cancers arise from cells within the epidermis, or top layer, of the skin.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/human-skin-layers-royalty-free-illustration/1149397551?phrase=dermis+layers&adppopup=true">About time/ iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Unlike normal cells, skin cancer cells grow without constraints, acquiring the ability to invade down into the dermis.</p>
<p>Invasive melanomas are classified by stages 1 through 4. The higher the number, the more invasive the tumor is into the dermis and to other organs of the body in <a href="https://www.cancer.gov/publications/dictionaries/cancer-terms/def/metastasis">a process called metastasis</a>. </p>
<h2>What are the main causes of skin cancer?</h2>
<p>Overexposure to ultraviolet rays causes the majority of skin cancers. Both light- and dark-skinned people <a href="https://www.aad.org/media/stats-skin-cancer">can get skin cancer</a>, but light-skinned individuals have a greater risk. Those with light skin, light or red hair, or with numerous moles, are more susceptible to skin damage and severe burns by ultraviolet rays. Darker-skinned individuals produce more of the <a href="https://my.clevelandclinic.org/health/body/22615-melanin">protective pigment called melanin</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542237/original/file-20230810-23008-qfmzoe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Cartoon of a young female on the left before sunburn and on the right with a sunburned face, with sunrays hitting an illustration of the skin layers in the middle." src="https://images.theconversation.com/files/542237/original/file-20230810-23008-qfmzoe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542237/original/file-20230810-23008-qfmzoe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542237/original/file-20230810-23008-qfmzoe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542237/original/file-20230810-23008-qfmzoe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542237/original/file-20230810-23008-qfmzoe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542237/original/file-20230810-23008-qfmzoe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542237/original/file-20230810-23008-qfmzoe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Overexposure to UV light damages skin, causing sunburns and stimulating melanocytes to make melanin, the protective pigment that darkens skin during tanning. Sunscreen can protect skin from UV damage.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/care-before-after-image-royalty-free-illustration/609443652">chombosan/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Tanning serves as the body’s protective response to skin damage from ultraviolet rays, stimulating melanocytes to <a href="https://doi.org/10.1111/exd.14260">produce melanin</a>. People who use tanning beds are at a higher risk of skin damage and skin cancers. This is why the American Academy of Dermatology and others <a href="https://www.aad.org/media/stats-indoor-tanning">recommend avoiding tanning beds</a>. Outdoor workers or those who spend time outdoors recreationally, especially at higher elevation, are exposed to more ultraviolet light. </p>
<p>A history of sunburns also puts people at greater risk of developing skin cancer. Because the damage from ultraviolet, or UV, exposure is cumulative, skin cancer is <a href="https://www.skincancer.org/skin-cancer-information/skin-cancer-facts/">more prevalent in people over 55 years old</a>. </p>
<p>Survivors of skin cancers are also <a href="https://doi.org/10.1111/jdv.12887">more likely to get another cancer</a> in their lifetime. Moreover, those who had a squamous cell carcinoma may be at <a href="https://doi.org/10.1007/s00403-017-1724-5">higher risk of dying from noncancer causes</a>. The reasons for these observations are not well understood but may be linked to inflammation or altered immunity, or both, in skin cancer survivors.</p>
<h2>What is the debate behind screening?</h2>
<p>The ongoing debate revolves around whether more screening reduces the death toll from melanoma. </p>
<p>Since the early 1990s, the incidence of melanoma has risen dramatically in the U.S. This increase may be due in part to more emphasis on early detection. <a href="https://doi.org/10.1056/NEJMsb2019760">More melanomas have been found</a>, particularly those identified at the earliest stage, also known as <a href="https://www.aimatmelanoma.org/stages-of-melanoma/">stage 0</a> or melanoma <em>in situ</em>. </p>
<p>Despite this, the rate of death per capita from melanoma has remained unchanged over the last 40 years. Researchers have <a href="https://doi.org/10.1056/NEJMsb2019760">attributed this fact to overdiagnosis</a>, in which suspicious lesions are diagnosed as early melanomas, even though they may not actually be melanomas or progress to be invasive melanomas, which have <a href="https://www.cancer.org/cancer/types/melanoma-skin-cancer/detection-diagnosis-staging/survival-rates-for-melanoma-skin-cancer-by-stage.html">the worst prognosis</a>. </p>
<p>This observation suggests that widespread screening may result in unnecessary surgical biopsies and increased psychological stress associated with a cancer diagnosis. </p>
<p>However, a recent study published after the task force recommendations showed that patients with melanoma <em>in situ</em> had a slight risk of death from melanoma, but <a href="https://doi.org/10.1001/jamadermatol.2023.1494">lived longer than the average person</a>. The authors speculated that the diagnosis of early stage melanoma resulted in a greater awareness of the patient’s overall health, leading to more health-conscious behavior. So, there may be additional benefits to screening the public. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/UnCUcFJJDSA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Regular self-exams help you catch skin cancer early, when it’s most treatable.</span></figcaption>
</figure>
<h2>What did the task force base its new recommendations on?</h2>
<p>The task force reviewed current and past data on the major types of skin cancers. The expert panel relied in part on the results of a large public <a href="https://doi.org/10.1016/j.jaad.2010.11.016">skin cancer screening program</a> in Germany. This program initially examined 20-year-olds from a single state and subsequently <a href="http://dx.doi.org/10.1136/bmjopen-2015-008158">expanded the program nationwide</a> to include people over 35. However, death rates from melanoma were unchanged compared to areas where skin exams were not offered. </p>
<p>The results of the German screening program did not provide strong confidence that annual widespread public screening of adults would reduce skin cancer deaths compared with current practices. However, the task force did conclude, based on numerous studies involving millions of patients, that detecting melanoma at early stages when tumors are less invasive <a href="https://doi.org/10.1001/jama.2023.3262">improved patient survival</a>. </p>
<h2>When should you get a skin exam?</h2>
<p>The American Academy of Dermatology, the <a href="https://www.skincancer.org/early-detection/self-exams/">Skin Cancer Foundation</a> and the <a href="https://www.cdc.gov/cancer/skin/basic_info/screening.htm">CDC recommend</a> <a href="https://www.aad.org/news/aad-statement-uspstf-cancer-screeening">monthly self-checks</a>. This requires familiarity with your skin or that of your family members. Luckily, there are many online guides on detecting suspicious skin lesions. </p>
<p>Whenever you have a concern about a spot on your skin, seek medical advice. Annual or more frequent exams are also <a href="https://www.aad.org/dw/dw-insights-and-inquiries/2019-archive/november/dwii-11-13-19-the-naked-truth-about-total-body-skin-examination-a-lesson-from-goldilocks-and-the-three-bears">recommended for high-risk groups</a>. This includes those who are older or susceptible to getting skin cancers, skin cancer survivors and immunocompromised people like organ transplant recipients. </p>
<p>Between 8% to 30% of the U.S. population <a href="https://doi.org/10.1016/j.jaad.2008.03.013">gets an annual skin exam</a>, but the numbers are imprecise because screening rates have not been well studied. Access to screening may also be challenging for some people. In response, nonprofits like the <a href="https://www.aad.org/public/public-health/skin-cancer-screenings/find-a-screening">American Academy of Dermatology</a>, <a href="https://www.skincancer.org/early-detection/destination-healthy-skin/">the Skin Cancer Foundation</a> and <a href="https://www.thesunbus.org/">The Sun Bus</a> provide resources for free exams. However, these opportunities are often few and far between. </p>
<p>Based on internal unpublished data from The Sun Bus, our mobile clinic operating in the central and southern U.S., a significant number of individuals seeking free exams were primarily motivated by concerns about a skin lesion and the cost of visiting a dermatologist.</p>
<p><iframe id="X7MiE" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/X7MiE/8/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Our data suggests that screening programs attract individuals who are proactive and health-conscious.</p>
<h2>How can you minimize the risk of skin cancer?</h2>
<p>Strategies that limit UV exposure will <a href="https://www.cdc.gov/cancer/skin/basic_info/sun-safety.htm">reduce skin cancer risk</a>. This includes avoiding sunburns by: </p>
<ul>
<li>Finding shade</li>
<li>Covering exposed skin</li>
<li>Using a hat and sunglasses</li>
<li>Using and reapplying sunscreen routinely</li>
</ul>
<p>A broad-spectrum sunscreen and lip balm with a Sun Protection Factor (SPF) of at least 30 when applied correctly will <a href="https://www.aad.org/public/everyday-care/sun-protection/shade-clothing-sunscreen/how-to-select-sunscreen">block 97% of ultraviolet rays</a>. Apply these products 15-20 minutes before heading out into the sun and reapply every two hours. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/L7dH-I2qLU8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Don’t wait until you’re in the sun to apply sunscreen.</span></figcaption>
</figure>
<p>UV light is most intense between the hours of 10 a.m. to 4 p.m. It is a good idea to pay attention to the UV index – a forecast by zip code that <a href="https://www.epa.gov/sunsafety/uv-index-1">projects risk of UV exposure</a> on a scale of 0 to 11. A UV index below 2 is the safest, whereas 11 represents extreme danger. </p>
<p>Ideally, clothing should be rated with an Ultraviolet Protection Factor (UPF) of 50. Wearing regular long-sleeved clothing and pants will also <a href="https://www.skincancer.org/skin-cancer-prevention/sun-protection/sun-protective-clothing/">provide some protection</a>. </p>
<p>These measures can keep your skin healthy into your golden years by reducing skin aging and cancer caused by ultraviolet light.</p><img src="https://counter.theconversation.com/content/209371/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Enrique Torchia received funding from American Cancer Society and Dermatology Foundation. </span></em></p><p class="fine-print"><em><span>Neil Box receives funding from the National Institutes of Health and the American Skin Association. He is affiliated with Caris Life Sciences and the Colorado Melanoma Foundation. </span></em></p><p class="fine-print"><em><span>Tamara Terzian received funding from National Institutes of Health, Dermatology Foundation, Skin Cancer Foundation, American Skin Association, American Cancer Society, Cancer League of Colorado, and Colorado Clinical Translational Sciences Institute. She is affiliated with the Colorado Melanoma Foundation and the University of Colorado. </span></em></p>Widespread screening for skin cancer may not be necessary, but it is important to understand the risks behind UV overexposure and to get checked early if you have concerns.Enrique Torchia, Assistant Research Professor of Dermatology, University of Colorado Anschutz Medical CampusNeil Box, Associate Clinical Professor of Dermatology and Epidemiology, University of Colorado Anschutz Medical CampusTamara Terzian, Assistant Professor of Dermatology, University of Colorado Anschutz Medical CampusLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1965562023-01-24T00:53:09Z2023-01-24T00:53:09ZHow long does it take for skin to repair after sun exposure?<figure><img src="https://images.theconversation.com/files/505788/original/file-20230123-7984-c8rkw3.jpg?ixlib=rb-1.1.0&rect=35%2C61%2C5815%2C3832&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/jDR6xx0Sxqc">Patrick Robert Doyle/Unsplash</a></span></figcaption></figure><p>It’s impossible to avoid the Aussie sun entirely, but Australians are well aware of the dangers of too much exposure. Some <a href="https://www.cancer.org.au/cancer-information/causes-and-prevention/sun-safety/campaigns-and-events/slip-slop-slap-seek-slide">40 years</a> of Slip Slop Slap (and more recently added, Seek and Slide) campaigns have reinforced this, not to mention the unpleasant experience of a sunburn most of us have encountered at some point.</p>
<p>Skin <em>does</em> repair itself, but how long does that take? If you hit the beach for half an hour, then retreat to the shade for a while, then go back out, will the damage have gone back to baseline? Or are you accumulating it? </p>
<p>Like most things, it’s complicated. </p>
<h2>How does the sun damage your skin?</h2>
<p>Spending a day in the sun can cause <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3709783/">100,000 DNA defects</a> in each exposed skin cell. DNA is the genetic information your body needs to build and run itself. There’s a copy in each of your cells, except for red blood cells and the layer of dead cells at the very surface of the skin.</p>
<p>Your cells have a very effective DNA repair process, called nucleotide excision repair, for this kind of damage. But some damage still slips through the cracks.</p>
<p>When your skin’s DNA monitoring system decides there is just too much damage to be effectively repaired, it tells the cells to self-destruct and calls in the immune system to finish them off. This causes the symptoms of sunburn: redness, pain, and sometimes blistering. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-happens-to-your-skin-when-you-get-sunburnt-53865">Explainer: what happens to your skin when you get sunburnt?</a>
</strong>
</em>
</p>
<hr>
<p>However, you don’t have to get sunburnt to start accumulating damage. A tan is your skin reacting to DNA damage by increasing the amount of melanin, which alters the skin’s colour, to mitigate future UV exposure. Though this only gives you the same protection as a <a href="https://pubmed.ncbi.nlm.nih.gov/24891049/">2-4 SPF sunscreen</a>. </p>
<p>UV radiation in Australia is so high, particularly during summer, that you can <a href="https://pubmed.ncbi.nlm.nih.gov/16584368/">start accumulating damage</a> in the time it takes to hang out the washing or walk to the bus stop. </p>
<p>Even so, the amount of DNA damage is proportional to the amount of UV exposure, so longer exposures or exposures at high-UV times of day cause much more damage.</p>
<figure class="align-center ">
<img alt="Woman hangs washing on the line" src="https://images.theconversation.com/files/505783/original/file-20230123-38684-2xo56m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505783/original/file-20230123-38684-2xo56m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505783/original/file-20230123-38684-2xo56m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505783/original/file-20230123-38684-2xo56m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505783/original/file-20230123-38684-2xo56m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505783/original/file-20230123-38684-2xo56m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505783/original/file-20230123-38684-2xo56m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In the time it takes to hang the washing out, the sun can damage your skin.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/middle-aged-charming-woman-hanging-washed-1542691622">Shutterstock</a></span>
</figcaption>
</figure>
<h2>Remind me, what is UV radiation?</h2>
<p>There are <a href="https://pubmed.ncbi.nlm.nih.gov/24891049/">two types</a> of UV radiation that damage skin – UVB mostly affects the upper layer, causing sunburn and skin cancer, and UVA mostly damages the lower layer, causing premature ageing. </p>
<p>These act in two different ways to damage skin, but due its cancer-causing properties, UVB is the better studied. </p>
<p>Light particles (UVB photons) <a href="https://theconversation.com/explainer-what-happens-to-your-skin-when-you-get-sunburnt-53865">discharge energy</a> when they hit DNA. This causes bases on one DNA strand to connect to each other, instead of their corresponding bases on the other strand. </p>
<figure class="align-center ">
<img alt="Two DNA helices, showing the structure before and after a UV photon has discharged energy into one." src="https://images.theconversation.com/files/503007/original/file-20230104-22-uwylca.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/503007/original/file-20230104-22-uwylca.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=463&fit=crop&dpr=1 600w, https://images.theconversation.com/files/503007/original/file-20230104-22-uwylca.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=463&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/503007/original/file-20230104-22-uwylca.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=463&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/503007/original/file-20230104-22-uwylca.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=582&fit=crop&dpr=1 754w, https://images.theconversation.com/files/503007/original/file-20230104-22-uwylca.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=582&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/503007/original/file-20230104-22-uwylca.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=582&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">‘Before’ shows a normal DNA helix. ‘After’ shows how excess energy from light causes the bases on DNA strands to link up incorrectly.</span>
<span class="attribution"><span class="source">NASA/David Herring</span></span>
</figcaption>
</figure>
<p>This distorts the DNA helix, so it doesn’t copy correctly when it’s time for the cells to divide. </p>
<p>And it causes permanent mutations that are replicated whenever the daughter cells multiply, setting the stage for skin cancers. </p>
<p>Even an exposure of <a href="https://www.sciencedirect.com/science/article/pii/S0022202X15333169?via%3Dihub">half the amount of UV</a> needed to cause a sunburn is enough to start generating these DNA defects. </p>
<h2>How long does the damage take to repair?</h2>
<p>Once they’re formed, the half-life of DNA defects is <a href="https://onlinelibrary.wiley.com/doi/10.1111/phpp.12298">20-30 hours</a>, depending on the efficiency of your own DNA-repair machinery. That means it takes 20-30 hours for your cells to repair even half the damage. </p>
<p>In one study that took samples at 24 and 72 hours after exposure, <a href="https://pubmed.ncbi.nlm.nih.gov/12437454/">almost 25%</a> of the damage detected at the 24-hour mark was still present at 72 hours.</p>
<p>So if you’re already on your way to a sunburn, no, stepping away from the sun for 20 minutes to get an ice cream is not going to cut it. Your skin will eliminate most of the damage over a few days. But some may be missed or not found before the cell replicates.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-treat-sunburn-pain-according-to-skin-experts-150070">How to treat sunburn pain, according to skin experts</a>
</strong>
</em>
</p>
<hr>
<p>You’re better off minimising damage in the first place by planning to hit the beach early, spending the middle part of the day reading your new murder mystery in the shade, and perhaps returning to the sands from mid-afternoon. </p>
<p>Alternatively, you could extend your time in the sun by covering up extensively with a long-sleeved rashie, thick leggings, hat and frequently reapplied sunscreen on anything not covered up – and don’t forget your feet!</p>
<h2>Get into the habit of wearing sunscreen every day</h2>
<p>The good news is 30+ SPF sunscreen can <a href="https://www.sciencedirect.com/science/article/pii/S0022202X15333169?pes=vor">steeply reduce</a> and sometimes <a href="https://pubmed.ncbi.nlm.nih.gov/28165636/">completely block</a> damage. </p>
<p>To <a href="https://www.safeinthesunshine.org.au/sunprotection">protect your skin</a>, apply sunscreen as part of your morning routine on any day when the UV index is forecast to be <a href="https://pubmed.ncbi.nlm.nih.gov/30681231/">3 or higher</a>. This will prevent an accumulation of damage from brief exposures like hanging out washing or walking in from the carpark. </p>
<figure class="align-center ">
<img alt="Woman applies sunscreen in the morning" src="https://images.theconversation.com/files/505791/original/file-20230123-59990-byyoc7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505791/original/file-20230123-59990-byyoc7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505791/original/file-20230123-59990-byyoc7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505791/original/file-20230123-59990-byyoc7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505791/original/file-20230123-59990-byyoc7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505791/original/file-20230123-59990-byyoc7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505791/original/file-20230123-59990-byyoc7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Apply sunscreen as part of your daily routine.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/mirror-reflection-of-a-woman-applying-face-cream-4960087/">Pexels/Karolina Grabowska</a></span>
</figcaption>
</figure>
<p>Most weather forecasts will tell you what UV to expect but in Perth, Brisbane and Darwin it’s over 3 all year around. </p>
<p>If you’re going to be outside for a prolonged time, add sun protective clothing, a hat and sunglasses, reapply your sunscreen at least every two hours, and stay in the shade where possible. </p>
<p>If you do get sunburnt, the best thing you can do for yourself is <a href="https://theconversation.com/how-to-treat-sunburn-pain-according-to-skin-experts-150070">stay out of the sun</a> for a few days until the redness goes away. This lets your body deal with the damage as efficiently as possible without piling more on.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/4-myths-about-sunscreen-and-why-theyre-wrong-125879">4½ myths about sunscreen and why they're wrong</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/196556/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katie Lee receives funding from the NHMRC. </span></em></p><p class="fine-print"><em><span>H. Peter Soyer is a shareholder of MoleMap NZ Limited and e-derm consult GmbH and undertakes regular teledermatological reporting for both companies. He is a Medical Consultant for Canfield Scientific Inc and Blaze Bioscience Inc..</span></em></p>Spending too long in the sun can damage your DNA. But what about if you retreat back to the shade? How long does it take to get back to normal?Katie Lee, PhD Candidate, The University of QueenslandH. Peter Soyer, Professor of Dermatology, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1953592022-12-01T19:03:01Z2022-12-01T19:03:01ZThere’s a serious ethical problem with some sunscreen testing methods – and you’re probably not aware of it<figure><img src="https://images.theconversation.com/files/497862/original/file-20221129-16-3u2uwt.jpg?ixlib=rb-1.1.0&rect=43%2C92%2C3919%2C2469&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">frantic00/Shutterstock</span></span></figcaption></figure><p>As summer approaches, we need to start remembering to slip on sun-protective clothing, slop on sunscreen, slap on a hat, seek shade where possible, and slide on sunglasses.</p>
<p>When it comes to sunscreen, we all know we need to wear it to protect against the harmful effects of ultraviolet (UV) radiation, which can cause skin cancer.</p>
<p>But what about the sun protection factor, known as the SPF rating, we see on our sunscreen bottles? It indicates the level of protection – but is it always what it says it is, and how is it actually tested?</p>
<h2>Risking human health for SPF testing</h2>
<p>While there have been some cases of <a href="https://www.tga.gov.au/news/news/sunscreen-testing-ama-laboratories-condition-listing">sunscreens not matching up to their SPF claims</a>, this is the exception and not the norm.</p>
<p>In Australia, we can be comfortable knowing these products are tightly regulated to ensure they are safe and meet their claimed SPF rating, according to current SPF testing methods.</p>
<p>However, problems arise when it comes to <em>how</em> sunscreens are tested for their SPF rating. Most people would not be aware that the SPF value on their sunscreen bottles is determined by testing on humans.</p>
<p>Ultimately, this means we are risking people’s health to test how effective our sunscreens are – and we urgently need to change this.</p>
<h2>How is sunscreen SPF tested?</h2>
<p>Once a sunscreen formulation has been developed by a manufacturer it needs to go through testing to ensure it only contains approved ingredients, and ultimately, that it does what it says it does.</p>
<p>All sunscreen products available in Australia are <a href="https://www.tga.gov.au/news/news/about-sunscreens">tested according to the Australian Standard to determine the SPF</a>. This is great and provides assurance of safety and quality for the consumer – but the problem is with how this testing is done.</p>
<p>Currently, testing sunscreens on humans is the approved international standard to rate the UV protection level of a sunscreen. This testing involves volunteers wearing strictly defined amounts of sunscreen and being exposed to artificial solar <a href="https://www.arpansa.gov.au/understanding-radiation/what-is-radiation/non-ionising-radiation/ultraviolet-radiation">UV radiation</a>. </p>
<p>Performance is measured by determining the time it takes for erythema or redness to occur. <a href="https://www.cancer.org.au/about-us/policy-and-advocacy/prevention-policy/national-cancer-prevention-policy/skin-cancer-statistics-and-issues/sunburn">This is, basically, sunburn</a>; based on this, an SPF rating is assigned.</p>
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<h2>Why is human testing of SPF a problem?</h2>
<p>If sunscreens only contain approved ingredients we know are safe, is it really a problem they are tested on humans?</p>
<p>Sadly, yes. Human testing involves exposing people to harmful UV radiation, which we know can cause skin and eye damage, <a href="https://www.arpansa.gov.au/understanding-radiation/radiation-sources/more-radiation-sources/sun-exposure">as well as being the leading cause of skin cancer</a>. This alone is <a href="https://www.phrp.com.au/wp-content/uploads/2022/03/PHRP3212205.pdf">unethical and unjustifiable</a>.</p>
<p>There are also other issues associated with testing sunscreen on humans. For example, the <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/phpp.12095">use of erythema to determine sunscreen effectiveness is highly subjective</a>, and may differ from one person to another, even for those with the same <a href="https://www.arpansa.gov.au/sites/default/files/legacy/pubs/RadiationProtection/FitzpatrickSkinType.pdf">skin type</a>. This makes the reliability of such testing methods questionable.</p>
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Read more:
<a href="https://theconversation.com/human-skin-stood-up-better-to-the-sun-before-there-were-sunscreens-and-parasols-an-anthropologist-explains-why-187559">Human skin stood up better to the sun before there were sunscreens and parasols – an anthropologist explains why</a>
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<p>Further, testing is only done on a small number of people (a minimum of <a href="https://www.tga.gov.au/sites/default/files/australian-regulatory-guidelines-for-sunscreens.pdf">ten people is required in Australia</a>). This is great for exposing as few people as possible to harmful UV radiation to determine a product’s SPF rating – but not so great when it comes to inclusiveness.</p>
<p>Testing such a small number of people is not representative. It does not include all skin types and leads to real <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ics.12333">challenges in achieving reproducible results</a> across different laboratories testing the same product.</p>
<p>The testing itself is also very expensive. This adds to the already high cost of buying sunscreens, and potentially limits manufacturers from developing new and better products.</p>
<p>These, along with many other issues, highlight the urgency for non-human (in vitro) testing methods of a sunscreen’s effectiveness to be developed.</p>
<h2>Human-free SPF testing technology is in development</h2>
<p>While efforts have been made to develop non-human testing methods, <a href="https://www.sciencedirect.com/science/article/pii/S0165993622002072">there remain several challenges</a>. <a href="https://www.karger.com/Article/Abstract/292777">These include</a> the materials used to simulate human skin (also known as substrates), difficulties in applying the sunscreen to these substrates, reproducibility of results, and ensuring that results are the same as what we see with human testing.</p>
<p>However, scientists at <a href="https://www.rmit.edu.au">RMIT University</a>, with support from the Australian Radiation Protection and Nuclear Safety Agency (<a href="https://www.arpansa.gov.au">ARPANSA</a>) and the <a href="https://www.cancervic.org.au">Cancer Council Victoria</a>, are <a href="https://www.sciencedirect.com/science/article/pii/S0165993622002072">working on a solution to this problem</a>.</p>
<p>So far, they have developed a prototype sensor that <a href="https://www.nature.com/articles/s41467-018-06273-3">changes colour when exposed to UV radiation</a>. This <a href="https://www.nature.com/articles/s41467-018-06273-3/figures/5">sensor</a> could be customised for human-free sunscreen testing, for example.</p>
<p>Reliable in vitro testing methods will mean in the future, sunscreen manufacturers would be able to quickly make and test new and better sunscreens, without being limited by the time and cost constraints involved with human testing.</p>
<p>So the next time you buy a bottle of sunscreen, look to purchase the highest-rated sunscreen of SPF 50+ – and know that work is underway on getting that rating classified in a more ethical way.</p>
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<strong>
Read more:
<a href="https://theconversation.com/are-bananas-really-radioactive-an-expert-clears-up-common-misunderstandings-about-radiation-193211">Are bananas really 'radioactive'? An expert clears up common misunderstandings about radiation</a>
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<p class="fine-print"><em><span>Sarah Loughran receives funding from The National Health and Medical Research Council of Australia (NHMRC). She is the Director of Radiation Research and Advice at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). She is is also currently a member of the Scientific Expert Group at the International Commission on Non-Ionizing Radiation Protection (ICNIRP).</span></em></p><p class="fine-print"><em><span>Sylvia Urban receives funding from the Australian Research Council (ARC). She is a Professor in Chemistry and together with other colleagues in the School of Science, RMIT University, she is funded by the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) on this project. She is also a Fellow of the Royal Australian Chemical Institute (FRACI), a member of the American Society of Chemistry (ACS) and a Senior Fellow of the Higher Education Academy (SFHEA).</span></em></p>Sunscreen is one of the most important ways to protect yourself from skin cancer – but to be reliable, it has to be tested on brave volunteers.Sarah Loughran, Director Radiation Research and Advice (ARPANSA), and Adjunct Associate Professor (UOW), University of WollongongSylvia Urban, Professor in Chemistry, School of Science (Applied Chemistry & Environmental Science), RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1875592022-09-06T12:37:31Z2022-09-06T12:37:31ZHuman skin stood up better to the sun before there were sunscreens and parasols – an anthropologist explains why<figure><img src="https://images.theconversation.com/files/480836/original/file-20220824-4026-m7s9pf.jpg?ixlib=rb-1.1.0&rect=663%2C34%2C5087%2C3794&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The sun’s rays often feel good on your skin, but can cause serious damage.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-of-woman-against-sky-during-sunset-royalty-free-image/1340270649">Maksim Chernyshev/EyeEm via Getty Images</a></span></figcaption></figure><p>Human beings have a conflicted relationship with the sun. People love sunshine, but then get hot. Sweat gets in your eyes. Then there are all the protective rituals: the sunscreen, the hats, the sunglasses. If you stay out too long or haven’t taken sufficient precautions, your skin lets us you know with an angry sunburn. First the heat, then the pain, then the remorse.</p>
<p>Were people always this obsessed with what the sun would do to their bodies? <a href="https://scholar.google.com/citations?user=NIAvKr8AAAAJ&hl=en&oi=ao">As a biological anthropologist</a> who has studied primates’ adaptations to the environment, I can tell you the short answer is “no,” and they didn’t need to be. For eons, skin stood up to the sun.</p>
<h2>Skin, between you and the world</h2>
<p>Human beings evolved under the sun. Sunlight was a constant in people’s lives, warming and guiding them through the days and seasons. <em>Homo sapiens</em> spent the bulk of our prehistory and history outside, mostly naked. Skin was the primary interface between our ancestors’ bodies and the world.</p>
<p>Human skin was adapted to whatever conditions it found itself in. People took shelter, when they could find it, in caves and rock shelters, and got pretty good at making portable shelters from wood, animal skins and other gathered materials. At night, they huddled together and probably covered themselves with fur “blankets.” But during the active daylight hours, people were outdoors and their mostly bare skin was what they had.</p>
<p>During a person’s lifetime, <a href="https://medlineplus.gov/ency/anatomyvideos/000125.htm">skin responds to routine exposure to the sun</a> in many ways. The surface layer of the skin – the epidermis – <a href="https://newsinhealth.nih.gov/2014/07/sun-skin">becomes thicker by adding more layers of cells</a>. For most people, the skin becomes gradually darker as specialized cells kick into action to produce a <a href="https://my.clevelandclinic.org/health/body/22615-melanin">protective pigment called eumelanin</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="cross-sectional diagram of skin's layers with sunlight hitting the surface and showing increased production of melanin" src="https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Exposure to the sun’s rays triggers production of more protective eumelanin, which also darkens the skin’s appearance.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/tanning-process-skin-human-anatomy-royalty-free-illustration/645165034">ttsz/iStock via Getty Images Plus</a></span>
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<p>This remarkable molecule absorbs most visible light, causing it to look very dark brown, almost black. Eumelanin also absorbs damaging ultraviolet radiation. Depending on their genetics, people produce different amounts of eumelanin. Some have a lot and are able to produce a lot more when their skin is exposed to sun; others have less to start out with and produce less when their skin is exposed.</p>
<p><a href="https://scholar.google.com/citations?user=NIAvKr8AAAAJ&hl=en&oi=ao">My research on</a> <a href="https://doi.org/10.1111/pcmr.12976">the evolution of human skin pigmentation</a> has shown that the skin color of people in prehistory was tuned to local environmental conditions, primarily to local levels of ultraviolet light. People who lived under strong UV light – like you’d find near the equator – year in and year out had darkly pigmented and highly tannable skin capable of making a lot of eumelanin. People who lived under weaker and more seasonal UV levels – like you’d find in much of northern Europe and northern Asia – had lighter skin that had only limited abilities to produce protective pigment.</p>
<p>With only their feet to carry them, our distant ancestors didn’t move around much during their lives. Their skin adapted to subtle, seasonal changes in sunlight and UV conditions by producing more eumelanin and becoming darker in the summer and then losing some pigment in the fall and winter when the sun wasn’t so strong. Even for people with lightly pigmented skin, painful sunburns would have been exceedingly rare because there was never a sudden shock of strong sun exposure. Rather, as the sun strengthened during spring, the top layer of their skin would have gotten <a href="https://doi.org/10.1007/978-3-540-89656-2_60">gradually thicker over weeks and months of sun exposure</a>.</p>
<p>This is not to say that the skin would have been undamaged by today’s standards: Dermatologists would be appalled by the leathery and wrinkled appearance of the sun-exposed skin of our ancestors. Skin color, like the levels of sun itself, changed with the seasons and skin quickly showed its age. This is still the case for people who live traditional, mostly outdoor, lives in many parts of the world.</p>
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<a href="https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a squatting old man with weathered skin" src="https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Chronic unprotected sun exposure can damage skin, with effects that look like those on this farmer in India.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:2020_Indian_farmers%27_protest_-_old_man_sitting.jpg">Randeep Maddoke/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>There is no preserved skin from thousands of years ago for scientists to study, but we can infer from the effects of sun exposure on modern people that the damage was similar. <a href="https://doi.org/10.1111/j.1365-2133.2009.09565.x">Chronic sun exposure</a> <a href="https://doi.org/10.1016/S1011-1344(01)00198-1">can lead to skin cancer</a>, but rarely of the variety – <a href="https://doi.org/10.1016/j.bjps.2006.05.008">melanoma</a> – that would cause death during reproductive age.</p>
<h2>Indoor living changed skin</h2>
<p>Until around 10,000 years ago – a drop in the bucket of evolutionary history – human beings made their living by <a href="https://www.history.com/topics/pre-history/hunter-gatherers">gathering foods, hunting and fishing</a>. Humanity’s relationship with the sun and sunlight changed a lot after people started to settle down and live in permanent settlements. <a href="https://www.smithsonianmag.com/history/the-seeds-of-civilization-78015429/">Farming and food storage</a> were associated with the development of immovable buildings. By around 6000 B.C. many people throughout the world were spending more time in walled settlements, and more time indoors.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="line drawing of royal bearded man followed by two smaller men with parasol and fly whisk" src="https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1019&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1019&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1019&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1281&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1281&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1281&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Persian King Darius the Great, who lived more than 2,500 years ago, is portrayed being shielded from the sun.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/king-darius-the-great-followed-by-his-royalty-free-illustration/1367186124">Luisa Vallon Fumi/iStock via Getty Images Plus</a></span>
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<p>While most people still spent most of their time outside, some stayed indoors if they could. Many of them <a href="https://www.folkwear.com/blogs/news/historyoftheparasol">started protecting themselves from the sun</a> when they did go out. By at least 3000 B.C., a whole industry of sun protection grew up to create gear of all sorts – parasols, umbrellas, hats, tents and clothing – that would protect people from the discomfort and inevitable darkening of the skin associated with lengthy sun exposure. While some of these were originally reserved for nobility – like the parasols and umbrellas of ancient Egypt and China – these luxury items <a href="https://doi.org/10.1007/s11199-017-0785-4">began to be made</a> and <a href="https://doi.org/10.1080/17532523.2016.1281875">used more widely</a>.</p>
<p>In some places, people even developed <a href="https://doi.org/10.1371/journal.pone.0136090">protective pastes made out of minerals</a> and plant residues – <a href="https://doi.org/10.1111/jocd.14004">early versions of modern sunscreens</a> – to protect their exposed skin. Some, like the <a href="https://www.scmp.com/lifestyle/fashion-beauty/article/3100999/all-natural-sunscreen-and-beauty-product-thanaka-paste-has">thanaka paste used by people in Myanmar</a>, still persists today.</p>
<p>An important consequence of these practices in traditional agricultural societies was that people who spent most of their time indoors considered themselves privileged, and their lighter skin announced their status. A “farmer’s tan” was not glamorous: <a href="https://www.ucpress.edu/book/9780520283862/living-color">Sun-darkened skin was a penalty associated with hard outdoor work</a>, not the <a href="https://doi.org/10.2105/AJPH.2008.144352">badge of a leisurely vacation</a>. From Great Britain to China, Japan and India, suntanned skin became associated with a life of toil.</p>
<p>As people have moved around more and faster over longer distances in recent centuries, and spend more time indoors, their skin hasn’t caught up with their locations and lifestyles. Your levels of eumelanin probably aren’t perfectly adapted to the sun conditions where you live and so aren’t able to protect you the same way they might have your ancient ancestors.</p>
<p>Even if you’re naturally darkly pigmented or capable of tanning, everyone is susceptible to <a href="https://doi.org/10.1001/jamadermatol.2017.4201">damage caused by episodes of sun exposure</a>, especially after long breaks spent completely out of the sun. The “vacation effect” of sudden strong UV exposure is really bad because a sunburn signals damage to the skin that is never completely repaired. It’s like a bad debt that presents itself as prematurely aged or precancerous skin many years later. There is no healthy tan – a tan doesn’t protect you from further sun damage, it’s the sign of damage itself.</p>
<p>People may love the sun, but we’re not our ancestors. Humanity’s relationship with the sun has changed, and this means changing your behavior to save your skin.</p><img src="https://counter.theconversation.com/content/187559/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nina G. Jablonski consults for L'Oreal and has received funding from the National Science Foundation, The Leakey Foundation, The Wenner-Gren Foundation, The Robert Wood Johnson Foundation, and The Rockefeller Foundation.</span></em></p>Our ancient ancestors didn’t have clothes or houses – but that constant exposure to the sun helped their skin protect itself from the worst sun damage.Nina G. Jablonski, Evan Pugh University Professor of Anthropology, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1886302022-08-19T20:47:15Z2022-08-19T20:47:15ZContaminants of emerging concern, found in sunscreens and plastics, end up in the St. Lawrence River<figure><img src="https://images.theconversation.com/files/478808/original/file-20220811-17796-y4twb4.jpg?ixlib=rb-1.1.0&rect=12%2C6%2C3977%2C3011&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">UV absorbents and industrial antioxidants can reach aquatic environments through the degradation of plastics, or via wastewater treatment plant effluents.</span> <span class="attribution"><span class="source">(Environment and Climate Change Canada)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Ultraviolet (UV) absorbents and industrial antioxidants are contaminants attracting growing interest as they are found in a wide range of products that are used daily. These products include sunscreens, anti-aging creams and shampoos, and materials such as plastics and textiles, both domestic or industrial. Primarily, their use is to protect our skin and other <a href="https://www.degruyter.com/document/doi/10.1515/psr-2016-0130/html">consumer goods from the sun’s UV radiation or from naturally occurring oxidizing agents</a> in the air.</p>
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À lire aussi :
<a href="https://theconversation.com/les-retardateurs-de-flamme-un-veritable-danger-pour-la-faune-182714">Les retardateurs de flamme, un véritable danger pour la faune</a>
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<p>Given their high versatility, there are several entry points for these contaminants into aquatic environments. Commonly targeted sources are municipal wastewater treatment plants’ effluents, since they collect water from routine domestic and industrial uses.</p>
<p>To improve the current knowledge of the Québec situation, I studied the evolution of these contaminants in the St. Lawrence River near Montréal during my master’s degree. With my colleagues, we present here the <a href="https://pubs.acs.org/doi/10.1021/acs.est.1c07932">conclusions of this study</a>. </p>
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<img alt="" src="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>This article is part of our series, <a href="https://theconversation.com/ca-fr/topics/fleuve-saint-laurent-116908">The St. Lawrence River: In depth</a>.
Don’t miss new articles on this mythical river of remarkable beauty. Our experts look at its fauna, flora and history, and the issues it faces. This series is brought to you by <a href="https://theconversation.com/ca-fr">La Conversation</a>.</em></p>
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<h2>From showers and garbage cans … to fish in the St. Lawrence River</h2>
<p>As people shower, rinse water containing residues of sunscreens, shampoo and other personal care products, goes to wastewater treatment plants. Similarly, swimming in more touristy areas can lead to direct contamination of waterways. </p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S030438941730763X">Another source is plastic pollution</a>, which enters the aquatic environment through direct dumping, for example when people leave debris on beaches. Indirect plastic discharge also occurs through their presence in the effluents of domestic wastewater treatment plants. As plastics degrade, for example through exposure to sunlight, salinity or the prolonged contact with waves, the compounds they contain (such as UV absorbents and industrial antioxidants) can migrate to the environment. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/478319/original/file-20220809-18-w9mttj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="filet dans un lac" src="https://images.theconversation.com/files/478319/original/file-20220809-18-w9mttj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478319/original/file-20220809-18-w9mttj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478319/original/file-20220809-18-w9mttj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478319/original/file-20220809-18-w9mttj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478319/original/file-20220809-18-w9mttj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478319/original/file-20220809-18-w9mttj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478319/original/file-20220809-18-w9mttj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Once found in aquatic environments, UV absorbents and industrial antioxidants can harm the animals that live there. (Environment and Climate Change Canada). Provided by the author.</span>
<span class="attribution"><span class="source">(Environnement et Changement climatique Canada)</span>, <span class="license">Fourni par l'auteur</span></span>
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<p>As soon as they enter the environment, these contaminants can disperse into sediments, water, and even among aquatic organisms, thereby harming biodiversity and ecosystem health. Indeed, some of these compounds are suspected of causing harmful effects, including <a href="https://pubs.acs.org/doi/10.1021/acs.est.7b05057">disrupting the hormonal system in exposed aquatic organisms</a> and <a href="https://link.springer.com/article/10.1007/s00244-015-0227-7">promoting coral bleaching</a>.</p>
<p>However, it is important to gain a better understanding of their distribution and evolution in aquatic environments in order to assess the current risk to species exposed to these contaminants. </p>
<h2>Contaminants in the river</h2>
<p>To better understand the fate of pollutants of interest in the St. Lawrence ecosystem, several types of samples were studied from upstream and downstream of the Montréal wastewater treatment centre. We collected water, suspended matter (which are insoluble particles visible in the water), sediment and tissues from two fish species, northern pike and lake sturgeon.</p>
<p>The analysis results found several contaminants, confirming their presence in the St. Lawrence ecosystem. In addition, affinity for suspended matter was observed, with higher concentrations for some contaminants, indicating the importance of improving our understanding of the risks associated with ingesting suspended matter. Indeed, the latter can be an important route of accumulation for organisms.</p>
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<a href="https://images.theconversation.com/files/477479/original/file-20220803-25-fruewv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="schéma présentant la présence de contaminants émergents dans le Fleuve" src="https://images.theconversation.com/files/477479/original/file-20220803-25-fruewv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477479/original/file-20220803-25-fruewv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=436&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477479/original/file-20220803-25-fruewv.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=436&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477479/original/file-20220803-25-fruewv.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=436&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477479/original/file-20220803-25-fruewv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=548&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477479/original/file-20220803-25-fruewv.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=548&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477479/original/file-20220803-25-fruewv.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=548&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">UV absorbents and industrial antioxidants can find several pathways to aquatic environments through the degradation of plastics, wastewater or landfills. (Abigaëlle Dalpé-Castilloux), Provided by the author.</span>
<span class="attribution"><span class="source">(Abigaëlle Dalpé-Castilloux)</span>, <span class="license">Fourni par l'auteur</span></span>
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<p>In comparing the dominant contaminants in the two fish studied, we observed a major difference between lake sturgeon and northern pike. This discrepancy can be caused by different factors, such as dietary differences between the two organisms. <a href="https://www.dfo-mpo.gc.ca/species-especes/profiles-profils/northernpike-grandbrochet-eng.html">Northern pike</a> is an opportunistic carnivore that feeds on what is easily available. Its main diet consists of yellow perch, suckers, sunfish and others.</p>
<p>In comparison, <a href="https://naturecanada.ca/news/sp-spot-lake-sturgeon/">lake sturgeon</a> is a bottom predator that feeds on small organisms such as larvae, crayfish and small molluscs. This difference in lifestyles leads to a difference in the way the organisms are exposed to pollution and therefore the extent of contamination by certain pollutants. For example, if a contaminant has a greater affinity for sediment, organisms living near the bottom may be more affected by it.</p>
<h2>Some contaminants are of greater concern than others</h2>
<p>The results also show that BHT, an industrial antioxidant, and its breakdown product, BHTQ, were the only compounds found in the brain of northern pike. The effects of these contaminants on the nervous system of aquatic organisms are not well known at this time. An earlier study, however, demonstrated that BHT can accumulate in the rat brain and can lead to an increase <a href="https://www.sciencedirect.com/science/article/abs/pii/0300483X80901213?via%3Dihub">in the number of dead cells</a>. To our knowledge, this is the first finding of these toxic compounds in the St. Lawrence.</p>
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<a href="https://images.theconversation.com/files/478324/original/file-20220809-24-hxw36w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="2 personnes déploient un filet dans l'eau" src="https://images.theconversation.com/files/478324/original/file-20220809-24-hxw36w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478324/original/file-20220809-24-hxw36w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478324/original/file-20220809-24-hxw36w.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478324/original/file-20220809-24-hxw36w.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478324/original/file-20220809-24-hxw36w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478324/original/file-20220809-24-hxw36w.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478324/original/file-20220809-24-hxw36w.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Contaminant concentrations were measured in northern pike and lake sturgeon in the St. Lawrence River. (Environment and Climate Change Canada). Provided by the author.</span>
<span class="attribution"><span class="source">(Environnement et Changement climatique Canada)</span>, <span class="license">Fourni par l'auteur</span></span>
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</figure>
<p>Found mainly in plastics and paints, UV328 is a molecule of international interest <a href="http://www.pops.int/TheConvention/ThePOPs/ChemicalsProposedforListing/tabid/2510/Default.aspx">monitored by the Stockholm Convention</a> for its damaging effects on the liver and its potential for hormonal disruption. Its presence has been detected primarily in lake sturgeon, water, suspended matter and sediments of the river. </p>
<h2>More gaps to be filled</h2>
<p>The study highlighted the presence of contaminants of interest in the St. Lawrence River and identified UV328 and BHT as being of greater concern. On the other hand, there is still insufficient knowledge to understand the impact of these contaminants on the various organisms living in the St. Lawrence, particularly in terms of the effects of long-term exposures. </p>
<p>Moreover, it is important to remember that aquatic organisms are subject to a mixture of several pollutants and that it is therefore essential to have a better understanding of the consequences of their interactions on the health of organisms.</p><img src="https://counter.theconversation.com/content/188630/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Zhe Lu received funding from the Natural Sciences and Engineering Research Council of Canada, Environment and Climate Change Canada and UQAR-ISMER for this project.</span></em></p><p class="fine-print"><em><span>Abigaëlle Dalpé-Castilloux received funding from FRQNT and Regroupement des écotoxicologues du Québec.</span></em></p><p class="fine-print"><em><span>Magali Houde received funding from Environment and Climate Change Canada.</span></em></p>UV absorbents and industrial antioxidants are used in many household goods to protect them from UV radiation. They can have an adverse impact on ecosystems.Zhe Lu, Professor, Université du Québec à Rimouski (UQAR)Abigaëlle Dalpé-Castilloux, M Sc océanographie (laboratoire d'écotoxicologie marine, chimie analytique environnementale), Université du Québec à Rimouski (UQAR)Magali Houde, Chercheuse scientifique, Université du Québec à Montréal (UQAM)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1883442022-08-09T15:03:58Z2022-08-09T15:03:58ZDo chemicals in sunscreens threaten aquatic life? A new report says a thorough assessment is ‘urgently needed,’ while also calling sunscreens essential protection against skin cancer<figure><img src="https://images.theconversation.com/files/478144/original/file-20220808-4922-ds99rt.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3794%2C2514&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sunscreens for sale at a Walgreens drug store.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/shelves-of-suntan-lotion-for-sale-in-walgreens-news-photo/665553846">Jeff Greenberg/Universal Images Group via Getty Images</a></span></figcaption></figure><p><em>Studies have shown that the same active ingredients in sunscreens that protect people from cancer-causing ultraviolet rays can be toxic to a range of species in oceans, rivers and lakes. With both of these risks in mind, a <a href="https://nap.nationalacademies.org/catalog/26381/review-of-fate-exposure-and-effects-of-sunscreens-in-aquatic-environments-and-implications-for-sunscreen-usage-and-human-health">new report</a> from the National Academies of Sciences, Engineering and Medicine finds an urgent need for more information about whether these chemicals threaten aquatic life on a broad scale.</em> </p>
<p><em>The report calls on the U.S. Environmental Protection Agency to conduct a detailed review called an <a href="https://www.epa.gov/risk/ecological-risk-assessment">environmental risk assessment</a> of the likelihood that exposure to one or more of these chemicals, called <a href="https://ntp.niehs.nih.gov/whatwestudy/topics/uvfilters/index.html">UV filters</a>, may harm organisms in saltwater and freshwater ecosystems. The study recommends focusing on two types of settings – coral reefs in shallow waters near shore, and slow-moving freshwater bodies like ponds and marshes – that are heavily used for recreation and/or exposed to wastewater or urban runoff.</em> </p>
<p><em>The study recognizes that sunscreen with a Sun Protection Factor (SPF) of 30 or higher is an effective defense against sunburn and skin cancer, and that making it harder to buy broad-spectrum sunscreen that people will actually use could harm public health. Accordingly, it calls for research examining how changes in sunscreen usage could affect human health. Two members of the study committee explain how their group balanced these concerns.</em></p>
<h2>Many species are exposed to many stresses</h2>
<p><strong>Robert Richmond, Research Professor and Director, Kewalo Marine Laboratory, University of Hawaii at Manoa</strong></p>
<p>Studies to date have provided compelling laboratory evidence that some UV filters can have toxic effects on aquatic species, including <a href="http://dx.doi.org/10.1126/science.abo4627">corals</a>, <a href="http://dx.doi.org/10.1126/science.abn2600">anemones</a> and <a href="https://doi.org/10.1021/acs.est.8b02418">zebrafish</a>, that are exposed to the chemicals. These findings have raised concerns about sunscreens’ <a href="https://doi.org/10.1016/j.envpol.2020.115894">larger-scale impacts on biological communities and ecosystems</a>.</p>
<p>But outcomes in the environment will differ depending on what compounds, ecosystems and local environmental conditions are involved. That’s especially true for coral reefs. The committee highlighted reefs because they are <a href="https://coast.noaa.gov/states/fast-facts/coral-reefs.html">ecologically, economically and culturally valuable</a>, and attract large numbers of tourists who use sunscreens. </p>
<p>Coral reefs are <a href="https://doi.org/10.1016/j.oneear.2021.08.016">declining worldwide</a> due to multiple human-induced disturbances. Some of these disturbances are global, such as <a href="https://oceanservice.noaa.gov/facts/coralreef-climate.html">ocean warming and acidification driven by climate change</a>. Other stressors, such as coastal water quality, are more local. </p>
<p>Studying the effects of chemicals on corals and coral reefs is challenging because they are both complex systems. Reef-building corals are a combination of an animal, single-celled algae and rich populations of bacteria living and working together. Coral reefs are made up of thousands of interacting organisms. </p>
<p>Importantly, many stress responses in corals occur without causing outright death, but impair their health, growth, resilience and even ability to reproduce. Scientists need to know more about these responses to guide effective management responses and interventions.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dozens of parrotfish swim over a reef of res, white and yellow corals." src="https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Healthy coral reefs like this one in American Samoa support such diverse communities of fish and other organisms that they often are called the rainforests of the sea.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1016/j.oneear.2021.08.016">Kevin Lino, NOAA/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>After in-depth reviews of the existing data, our study committee recommended that the U.S. Environmental Protection Agency should undertake an ecological risk assessment of the 17 UV filters used in sunscreens sold in the U.S. Such a study would include a comparison of toxicity findings to relevant concentrations and exposure conditions. </p>
<p>For example, what happens to organisms exposed to these chemicals occasionally versus those exposed regularly, in calm bays or along open, wave-swept coasts? How do UV filters differ in whether they break down in water, or accumulate in sediments or the tissues of living organisms? </p>
<p>In our view, an ecological risk assessment would provide EPA and others the basis for sound and effective policy development. The sooner this happens and the results are applied to the regulatory process, the better for everyone who is affected, including future generations.</p>
<h2>The challenge of understanding long-term effects on humans and the environment</h2>
<p><strong>Karen Glanz, George A. Weiss University Professor and Director, UPenn Prevention Research Center, University of Pennsylvania</strong></p>
<p>The question of whether UV filters pose harm to the environment while helping to reduce skin damage and prevent skin cancer is a conundrum. It seemingly pits human and environmental health against each other head-to-head and asks policymakers, medical experts and the public to choose between them. </p>
<p>Humans need sunlight to live, but overexposure to the sun’s damaging rays – ultraviolet radiation – causes sunburn and wrinkles and is a risk factor for the development of skin cancers, including the most deadly type, <a href="https://www.cancer.org/cancer/melanoma-skin-cancer/about/what-is-melanoma.html">melanoma</a>. Routine use of <a href="https://www.aad.org/public/diseases/skin-cancer/prevent/how">broad-spectrum sunscreen with SPF 30+</a> when outdoors has been found to prevent skin damage and skin cancer. But sunscreens are most effective as part of a <a href="https://www.cdc.gov/cancer/skin/basic_info/sun-safety.htm">set of behaviors</a> that also includes wearing hats and cover-up clothing and seeking shade. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"616291967698386944"}"></div></p>
<p>Most people in the U.S. don’t practice these behaviors frequently or thoroughly enough. So it’s important to weigh very carefully the potential effects of restricting the choice of available sunscreens. </p>
<p>Some jurisdictions already restrict the sale of certain sunscreens because concerned advocates believe doing so will be good for the environment. In the U.S., they include <a href="https://www.cntraveler.com/story/these-destinations-are-banning-certain-sunscreens">Hawaii, the U.S Virgin Islands and the city of Key West, Florida</a>. Our report doesn’t draw a definitive conclusion about whether these measures are scientifically justified or effective. Rather, it emphasizes analyzing whether and how they may affect human health as well as the
environment.</p>
<p>The study draws attention to the challenge of understanding risks from UV filters to aquatic environments under various conditions, and in the context of overarching environmental stressors such as rising sea temperatures. It’s important to understand that for both environmental and human health issues, laboratory studies don’t always match what happens in the environment. </p>
<p>Studies of model systems such as bacteria and yeast, and organisms such as fish embryos and insect larvae, can yield findings that do not hold up in studies of humans. For both the environment and humans, it may not be possible or ethical to conduct true experiments that test the long-term effects of chemicals in UV filters. </p>
<p>Members of our committee wrestled to interpret the available evidence, and also with the gaps in that evidence. Ultimately we concluded that the science is not settled, but that there is much to build on to advance understanding of this issue. Our conclusions are not a win/lose outcome for either the environment or humans. Rather, they point to a need to think both broadly and strategically for the benefit of people and the planet.</p><img src="https://counter.theconversation.com/content/188344/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Richmond receives funding from the National Science Foundation, the National Oceanic and Atmospheric Administration, the U.S. Fish and Wildlife Service, the Pew Environmental Group, the National Fish and Wildlife Foundation, the H.W. Hoover Foundation and the Hawaii Division of Aquatic Resources.
He has been a Pew Fellow in Marine Conservation, and an Aldo Leopold Fellow in Environmental Leadership, and has served on the Board of Directors of the Palau International Coral Reef Center and as Science Advisor to the All Islands Committee of the US Coral Reef Task Force. He was a member of a previous study committee organized by the National Academies, on Interventions to Increase the Resilience of Coral Reefs.
</span></em></p><p class="fine-print"><em><span>Karen Glanz conducts research cancer prevention and control, theories of health behavior, and social and health policy. She has conducted descriptive, observational, methodological, intervention, and dissemination research in skin cancer prevention since 1993. She has worked on analyses of national surveys of UV exposure and sun protection; developed, analyzed and validated measures and methods of skin cancer prevention research; and led evidence reviews for skin cancer prevention. Her research has been funded by the U.S. Centers for Disease Control and Prevention, the National Institutes of Health, and the Skin Cancer Foundation. Dr. Glanz served on the US Task Force on Community Preventive Services for 10 years and co-led reviews of the effectiveness of skin cancer prevention programs. She is an elected member of the National Academy of Medicine. </span></em></p>Rising concern about possible environmental damage from the active ingredients in sunscreens could have ripple effects on public health if it causes people to use less of them.Robert Richmond, Professor of Biology and Director, Kewalo Marine Laboratory, University of HawaiiKaren Glanz, George A. Weiss University Professor and Director, UPenn Prevention Research Center, University of PennsylvaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1873222022-08-08T15:46:59Z2022-08-08T15:46:59ZSunscreen: here’s why it’s an anti-ageing skincare essential<figure><img src="https://images.theconversation.com/files/478083/original/file-20220808-2624-dua4s0.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C5694%2C3782&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sunscreens can help reduce the amount of damaging radiation our skin gets.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/attractive-young-black-african-woman-model-2052802880">Ground Picture/ Shutterstock</a></span></figcaption></figure><p>Every month there seems to be a trendy new product to add to your skincare collection. Lately, a commonplace product that many people already use has taken the top spot, with everyone from dermatologists to influencers swearing by it as the number one way to stay looking youthful through the years: sunscreen. </p>
<p>It’s no wonder. It’s thought that solar exposure – also known as “photoageing” – causes up to <a href="https://pubmed.ncbi.nlm.nih.gov/24101874/">80% of skin ageing</a>. So if you’re someone who’s worried about fine lines, wrinkles and uneven pigmentation, limiting the amount of solar radiation you get is one of the most important things you can do.</p>
<p>There are thought to be a number of different triggers for photoageing. Most research has linked it to the expression of a group of proteins called matrix metalloproteinases (MMPs). These proteins are enzymes that break down elastins and collagens in the skin’s deeper layer (called the dermis). Elastins and collagens are responsible for the skin’s structure, strength and stretchiness.</p>
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<figure class="align-right ">
<img alt="Quarter life, a series by The Conversation" src="https://images.theconversation.com/files/451343/original/file-20220310-13-1bj6csd.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/451343/original/file-20220310-13-1bj6csd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451343/original/file-20220310-13-1bj6csd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451343/original/file-20220310-13-1bj6csd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451343/original/file-20220310-13-1bj6csd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451343/original/file-20220310-13-1bj6csd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451343/original/file-20220310-13-1bj6csd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><strong><a href="https://theconversation.com/uk/topics/quarter-life-117947?utm_source=TCUK&utm_medium=linkback&utm_campaign=UK+YP2022&utm_content=InArticleTop">This article is part of Quarter Life</a></strong>, a series about issues affecting those of us in our twenties and thirties. From the challenges of beginning a career and taking care of our mental health, to the excitement of starting a family, adopting a pet or just making friends as an adult. The articles in this series explore the questions and bring answers as we navigate this turbulent period of life.</em></p>
<p><em>You may be interested in:</em></p>
<p><em><a href="https://theconversation.com/do-these-three-popular-anti-ageing-skincare-ingredients-work-heres-what-the-evidence-says-182200?utm_source=TCUK&utm_medium=linkback&utm_campaign=UK+YP2022&utm_content=InArticleTop">Do these three popular anti-ageing skincare ingredients work? Here’s what the evidence says</a></em></p>
<p><em><a href="https://theconversation.com/why-you-should-travel-solo-this-summer-184000?utm_source=TCUK&utm_medium=linkback&utm_campaign=UK+YP2022&utm_content=InArticleTop">Why you should travel solo this summer</a></em></p>
<p><em><a href="https://theconversation.com/should-i-still-go-on-holiday-if-i-have-covid-186185?utm_source=TCUK&utm_medium=linkback&utm_campaign=UK+YP2022&utm_content=InArticleTop">Should I still go on holiday if I have COVID?</a></em></p>
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<p>Expression of these MMP proteins has been linked to both <a href="https://europepmc.org/article/med/18459971">DNA damage</a> in skin cells and the <a href="https://pubmed.ncbi.nlm.nih.gov/19116368/">production</a> of <a href="https://link.springer.com/article/10.1007/BF02505041">reactive oxygen species</a>. Reactive oxygen species are highly reactive chemicals formed from oxygen that can damage other cellular components, such as DNA and proteins. </p>
<p>Both of these factors are caused by too much sun exposure. Over time, this damage accumulates to cause characteristic signs of ageing. This may explains why one study even showed people who tended to avoid the sun had <a href="https://pubmed.ncbi.nlm.nih.gov/24101874/">significantly fewer signs of ageing</a> compared to people who enjoyed spending time in the sun. </p>
<p>But it isn’t always possible to avoid the sun – which is where sunscreens help. These products contain ingredients (such as zinc oxide) which absorb or reflect UV radiation and dissipate it safely before it can damage our skin cells. This also reduces the cumulative dose of radiation received by the skin.</p>
<p>Studies have shown that sunscreens can prevent many signs of photoageing by tackling the triggers, with <a href="https://pubmed.ncbi.nlm.nih.gov/16520862/">numerous studies</a> showing they can prevent the expression of MMPs. A study that compared the effects of <a href="https://pubmed.ncbi.nlm.nih.gov/7490363/">using sunscreen versus a placebo</a> on skin ageing, found that people in the placebo group had higher levels of solar elastosis (a sign of photoageing which causes a loss of elasticity) after two years.</p>
<p><a href="https://pubmed.ncbi.nlm.nih.gov/23732711/">An Australian study</a> compared levels of photoageing in groups assigned to daily sunscreen use versus discretionary sunscreen use. In the daily sunscreen use group, there was no detectable increase in skin ageing over the four-and-a-half year study period compared to the discretionary sunscreen group. <a href="https://pubmed.ncbi.nlm.nih.gov/27749441/">Another study</a> has also shown daily sunscreen use for a year may reverse visible signs of ageing when assessed by a dermatologist.</p>
<h2>Choosing the right product</h2>
<p>While there is plenty of evidence that sunscreens can prevent photoageing, many only block the UV (ultraviolet) range of the solar spectrum. In the case of photoageing, exposure to <a href="https://pubmed.ncbi.nlm.nih.gov/34585779/">visible radiation</a> (particularly <a href="https://www.nature.com/articles/s41598-018-30738-6">blue light</a>) and <a href="https://pubmed.ncbi.nlm.nih.gov/19675547/">infrared</a> have all been shown to contribute to photoageing. Basically, this means that sunscreens can’t protect against photoageing entirely, but can reduce it significantly.</p>
<figure class="align-center ">
<img alt="A young woman stands in the aisle of a store, holding two bottles of sunscreen in each hand. There is a row of shelves beside her filled with sunscreen bottles." src="https://images.theconversation.com/files/478084/original/file-20220808-2583-9n9kdk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478084/original/file-20220808-2583-9n9kdk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=394&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478084/original/file-20220808-2583-9n9kdk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=394&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478084/original/file-20220808-2583-9n9kdk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=394&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478084/original/file-20220808-2583-9n9kdk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=495&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478084/original/file-20220808-2583-9n9kdk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=495&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478084/original/file-20220808-2583-9n9kdk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=495&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">There’s plenty of products to choose from nowadays.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/smiling-woman-choosing-bottles-sun-protection-1312068065">BearFotos/ Shutterstock</a></span>
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<p>Some <a href="https://www.sciencedirect.com/science/article/pii/S1011134421002517">newer solar filters</a> used in sunscreens have been developed which can block some blue light. Other ingredients sometimes added to sunscreens (<a href="https://pubmed.ncbi.nlm.nih.gov/30071261/">such as antioxidants</a>) have also been shown to prevent the production of MMPs and reduce <a href="https://pubmed.ncbi.nlm.nih.gov/34789788/">reactive oxygen species</a> – which will likely help in the fight against photoageing beyond the UV spectrum, too. Antioxidants may also protect against factors such as <a href="https://pubmed.ncbi.nlm.nih.gov/31927691/#:%7E:text=Recent%20findings%3A%20Traffic%2Drelated%20air,effects%20on%20premature%20skin%20aging.">pollution</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/17951030/">smoking</a>, which are both linked to faster ageing.</p>
<p>Photoageing is a cumulative process that occurs over time. Doing anything you can to <a href="https://www.britishskinfoundation.org.uk/how-to-stay-safe-in-the-sun">limit exposure</a> will slow this process – such as covering up with clothing when you go outside. But choosing the right kind of sunscreen may also help somewhat.</p>
<p>The best product to use comes down largely to personal preference. But in general, the higher the SPF, the greater protection you’ll have against photoageing. You should also try to find a sunscreen with five-star UVA protection on the label, which will help protect against the broadest range of UV radiation.</p>
<p>Be sure to regularly use sunscreen or SPF-containing products from spring to autumn. If you’re going to be getting a lot of sun (such as on a beach holiday) it’s best to use a higher SPF product and reapply regularly. Although some people recommend wearing sunscreen even in winter, this is unlikely to be of much benefit to people living in the UK, as UV radiation is lowest this time of year. But if you go on a skiing holiday or live somewhere with lots of snow, sunscreen will still be beneficial as snow reflects solar radiation. </p>
<p>All the evidence suggests that by far the most effective way to prevent photoageing is with the use of sunscreens, as these prevent damage from happening in the first place. Now with more choice than ever and formulations always being improved, it’s just a matter of finding what product works best for you. </p>
<p>But a final word of warning: slathering on sunscreen before sitting out tanning won’t be enough to protect you completely – and this goes beyond photoageing. Too much sun exposure can carry other risks – such as sunburn and skin cancer – which is something to bear in mind during the summer months.</p>
<p><iframe src="https://action.bridged.media/?id=62f190752e78b514b03fffc1&embed=true" width="100%" height="400px" style="border:none; overflow: hidden;"></p></iframe></p><img src="https://counter.theconversation.com/content/187322/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karl Lawrence has previously received funding from the sunscreen industry.</span></em></p>It’s thought that up to 80% of skin ageing is the result of sun exposure.Karl Lawrence, Post Doctoral Researcher, Photobiology, King's College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1876682022-08-02T12:58:13Z2022-08-02T12:58:13ZHot and getting hotter – 5 essential reads on high temps and human bodies<figure><img src="https://images.theconversation.com/files/476758/original/file-20220729-13732-9ef431.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5419%2C3585&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The way heat and humidity affect people depends on factors like the weather that's typical where they are.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/boy-pouring-water-over-head-outdoors-royalty-free-image/56323439">Hans Huber/Westend61 via Getty Images</a></span></figcaption></figure><p>Launching the <a href="https://cpo.noaa.gov/Interagency-Programs/NIHHIS/About-NIHHIS#:%7E:text=NIHHIS%20is%20an%20integrated%20system,capacity%2C%20communication%2C%20and%20societal%20understanding">National Integrated Heat Health Information System (NIHHIS)</a> and the <a href="https://www.heat.gov/">heat.gov</a> site on July 26, 2022, the Biden administration cited heat waves and the warming climate as serious health threats. As the new initiative promises a “science informed response” to hotter conditions, five stories from The Conversation’s archive explain what researchers know about heat and health.</p>
<h2>1. It’s the humidity</h2>
<p><a href="https://theconversation.com/how-dangerous-heat-waves-can-kill-121727">Heat waves can be deadly</a> in a variety of ways, wrote <a href="https://scholar.google.com/citations?user=fNSdMfEAAAAJ&hl=en&oi=ao">William Calvin</a>, who teaches physiology and neuroscience at the University of Washington.</p>
<p>“Heat waves can kill via the dehydration caused by heavy sweating; the altered sodium and potassium concentrations in the blood confuse both heart and nerve cells, and so breathing or heartbeat may suddenly stop,” he wrote.</p>
<p>Calvin explained that human bodies have not evolved to handle extreme heat with humidity. “Normally, sweat evaporates off your skin and you cool down. But with high humidity, the air is already saturated with water vapor, and so evaporative cooling stops. However, you keep sweating anyway, threatening dehydration.”</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-dangerous-heat-waves-can-kill-121727">How dangerous heat waves can kill</a>
</strong>
</em>
</p>
<hr>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/476609/original/file-20220728-25-30dl7d.jpg?ixlib=rb-1.1.0&rect=0%2C29%2C4946%2C3578&q=45&auto=format&w=1000&fit=clip"><img alt="Photo shows roughly half of a furrowed, fair-skinned forehead with dark hair at the temple and many drops of sweat on the skin." src="https://images.theconversation.com/files/476609/original/file-20220728-25-30dl7d.jpg?ixlib=rb-1.1.0&rect=0%2C29%2C4946%2C3578&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/476609/original/file-20220728-25-30dl7d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476609/original/file-20220728-25-30dl7d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476609/original/file-20220728-25-30dl7d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476609/original/file-20220728-25-30dl7d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=550&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476609/original/file-20220728-25-30dl7d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=550&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476609/original/file-20220728-25-30dl7d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=550&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sweating is one way the body stays cool. In heat stroke, sweating stops, leaving the body in danger of fatally overheating.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-of-mans-wrinkled-forehead-royalty-free-image/200390293-001">Veronique Beranger/The Image Bank via Getty Images</a></span>
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<h2>2. Lower tolerance for higher temps</h2>
<p>“That combination of temperature and humidity whereby the person’s core temperature starts to rise is called the ‘critical environmental limit,’” wrote a group of Penn State University scholars researching the health effects of heat: <a href="https://scholar.google.com/citations?hl=en&user=zsXN72cAAAAJ">W. Larry Kenney</a>, <a href="https://scholar.google.com/citations?hl=en&user=xuBw4jQAAAAJ">Daniel Vecellio</a>, <a href="https://scholar.google.com/citations?hl=en&user=KIiHyBgAAAAJ">Rachel Cottle</a> and <a href="https://scholar.google.com/citations?hl=en&user=h05wc-kAAAAJ">S. Tony Wolf</a>.</p>
<p>In a rare lab test of the human body’s heat tolerance, the researchers found that the <a href="https://theconversation.com/how-hot-is-too-hot-for-the-human-body-our-lab-found-heat-humidity-gets-dangerous-faster-than-many-people-realize-185593">limit is lower than previously thought</a>. When the air temperature is around 100 degrees Fahrenheit (38 Celsius), people can begin to feel ill effects at just 60% humidity – a higher temperature and lower humidity than researchers determined in 2010.</p>
<p>“Above those limits, core temperature rises continuously and risk of heat-related illnesses with prolonged exposures is increased,” they wrote. “The results of these tests show an even greater cause for concern.”</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-hot-is-too-hot-for-the-human-body-our-lab-found-heat-humidity-gets-dangerous-faster-than-many-people-realize-185593">How hot is too hot for the human body? Our lab found heat + humidity gets dangerous faster than many people realize</a>
</strong>
</em>
</p>
<hr>
<h2>3. Age matters</h2>
<p>Extremely hot whether is particularly dangerous for those over 70, according to family physician <a href="https://scholar.google.com/citations?user=6YGkTgMAAAAJ&hl=en&oi=ao">Dr. Gabriel Neal</a>, who teaches at the Texas A&M Health Science Center College of Medicine. </p>
<p>In his article on <a href="https://theconversation.com/heat-stroke-a-doctor-offers-tips-to-stay-safe-as-temperatures-soar-120626">avoiding heat stroke</a>, Neal described factors making older adults vulnerable to heat-related illnesses. </p>
<p>“As people age, our bodies’ ability to cool declines, and the elderly often take medication that further impairs this ability,” Neal wrote. “In addition, the elderly may not be aware of the dangerous heat wave and may not have working air conditioning in their home, nor have anyone to check on them.” </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/heat-stroke-a-doctor-offers-tips-to-stay-safe-as-temperatures-soar-120626">Heat stroke: A doctor offers tips to stay safe as temperatures soar</a>
</strong>
</em>
</p>
<hr>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/476604/original/file-20220728-26986-kw8qzx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Four clear glasses of water with ice floating in them sitting on a wooden surface" src="https://images.theconversation.com/files/476604/original/file-20220728-26986-kw8qzx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/476604/original/file-20220728-26986-kw8qzx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476604/original/file-20220728-26986-kw8qzx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476604/original/file-20220728-26986-kw8qzx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476604/original/file-20220728-26986-kw8qzx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476604/original/file-20220728-26986-kw8qzx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476604/original/file-20220728-26986-kw8qzx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hydration is key to staying well in the heat.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/drinking-glasses-on-wooden-table-royalty-free-image/558302225">Nawarit Rittiyotee/ EyeEm via Getty Images</a></span>
</figcaption>
</figure>
<h2>4. Wet or dry, hot is hot</h2>
<p><a href="https://theconversation.com/knowing-how-heat-and-humidity-affect-your-body-can-help-you-stay-safe-during-heat-waves-163700">It’s the heat and the humidity</a>, wrote Mississippi State University exercise physiologist <a href="https://theconversation.com/profiles/johneric-w-smith-644514">JohnEric Smith</a>.</p>
<p>“Hot desert climates are stressful due to extreme temperatures, while humid subtropical climates are stressful because the body has trouble removing heat when sweat doesn’t evaporate readily,” he wrote.</p>
<p>Smith added that how heat and humidity affect people depends on factors like the weather that’s typical where they are, and the cooling systems in local homes and buildings.</p>
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<strong>
Read more:
<a href="https://theconversation.com/knowing-how-heat-and-humidity-affect-your-body-can-help-you-stay-safe-during-heat-waves-163700">Knowing how heat and humidity affect your body can help you stay safe during heat waves</a>
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</em>
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<h2>5. Warming up food</h2>
<p>Tufts University epidemiologist <a href="https://scholar.google.com/citations?hl=en&user=TeQarhcAAAAJ">Elena Naumova</a> warns that keeping food safe to eat is becoming <a href="https://theconversation.com/climate-change-is-putting-food-safety-at-risk-more-often-a%5B%E2%80%A6%5D-picnics-and-parties-blackouts-are-a-growing-problem-185685">more challenging in a warming climate</a>.
“That’s because warm, wet weather conditions stimulate bacterial growth,” she wrote.</p>
<p>Naumova named several climate-related factors in spreading foodborne illnesses. “One growing problem is that heat waves, wildfires and severe storms are increasingly triggering power outages, which in turn affect food storage and food handling practices in stores, production and distribution sites and homes,” she wrote.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-is-putting-food-safety-at-risk-more-often-and-not-just-at-picnics-and-parties-blackouts-are-a-growing-problem-185685">Climate change is putting food safety at risk more often, and not just at picnics and parties – blackouts are a growing problem</a>
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<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archives.</em></p><img src="https://counter.theconversation.com/content/187668/count.gif" alt="The Conversation" width="1" height="1" />
After the announcement of President Biden’s heat initiative, The Conversation revisits stories on high summer temperatures and human health.Leah Samuel, Health + Equity EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1865392022-07-20T12:21:28Z2022-07-20T12:21:28ZIt’s a myth that sunscreen prevents melanoma in people of color – a dermatologist explains<p>Melanoma is a potentially deadly form of skin cancer that effects people of every racial and ethnic group. The risk factor most closely linked to developing melanoma is exposure to ultraviolet, or UV, rays from the sun. In fact, sunburns have been associated with <a href="https://doi.org/10.1016/j.ejca.2004.10.016">doubling one’s risk of melanoma</a>. </p>
<p>Sunscreen can block UV rays and therefore reduce the risk of sunburns, which ultimately may reduce the risk of developing melanoma. Thus, the promotion of sunscreen as an effective melanoma prevention strategy is a <a href="https://doi.org/10.1111/ijd.12606">reasonable public health message</a>. </p>
<p>But while this may be true for light-skinned people, such as <a href="https://doi.org/10.1200/JCO.2010.28.7078">individuals of European descent</a>, this is not the case for darker-skinned people, such as individuals of African or Asian descent.</p>
<p>The public health messages <a href="https://doi.org/10.1016/j.jaad.2013.11.038">promoted by many clinicians</a> and <a href="https://www.skincancer.org/prevention/skin-cancer-and-skin-of-color">public health groups</a> regarding sunscreen recommendations for dark-skinned people is not supported by the available evidence. <a href="https://www.npr.org/sections/codeswitch/2018/07/05/559883985/will-your-melanin-protect-you-from-the-sun">Media messaging</a> exacerbates the problem with <a href="https://www.usatoday.com/story/life/health-wellness/2022/06/14/dermatologists-poc-sunscreen/7609507001/">headline</a> after <a href="https://news.yahoo.com/black-does-crack-expert-approved-201834873.html">headline</a> warning that Black people <a href="https://www.bbc.com/news/health-62155509">can also develop melanoma</a> and that Black people are not immune. </p>
<p>To be sure, they can get melanoma, but the risk is very low. In the same way, <a href="https://seer.cancer.gov/statistics-network/explorer/application.html?site=55&data_type=1&graph_type=2&compareBy=sex&chk_sex_3=3&chk_sex_2=2&rate_type=1&race=1&age_range=1&stage=101&advopt_precision=1&advopt_show_ci=on&advopt_display=1">men can develop breast cancer</a>, however, we do not promote mammography as a strategy to fight breast cancer in men.</p>
<p>This message is important to me <a href="https://dellmed.utexas.edu/directory/ade-adamson">as a Black board-certified dermatologist and health services researcher</a> at Dell Medical School at the University of Texas at Austin, where I am director of the pigmented lesion clinic. In this capacity I take care of patients at high risk for melanoma.</p>
<h2>Melanoma in Black people is not associated with UV exposure</h2>
<p>In the U.S., melanoma is <a href="https://seer.cancer.gov/statistics-network/explorer/application.html?site=53&data_type=1&graph_type=2&compareBy=race&chk_race_9=9&chk_race_8=8&rate_type=2&sex=1&age_range=1&stage=101&advopt_precision=1&advopt_show_ci=on&hdn_view=1&advopt_display=1">30 times more common</a> among white people than Black people. </p>
<p>In Black people, melanoma usually develops in parts of the body that are not exposed to the sun, such as the palms of the hands and soles of the feet. These cancers are called “acral melanomas,” and sunscreen will do nothing to reduce the risk of these cancers.</p>
<p>When was the last time you had a sunburn on the palms or soles? Even among white people, <a href="https://doi.org/10.1111/j.1365-2133.2006.07368.x">there is no relationship</a> between sun exposure and the risk of acral melanomas. Famously, <a href="http://dx.doi.org/10.1111/pcmr.12279">Bob Marley died from an acral melanoma</a> on his big toe, but sunscreen would not have helped. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/P7ORgp8007U?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The rare form of skin cancer that killed Bob Marley is thought to be caused by an injury or trauma.</span></figcaption>
</figure>
<p>Last year my research group <a href="https://doi.org/10.1001/jamadermatol.2020.4616">conducted a systematic review</a> in which we analyzed all of the published medical literature related to UV exposure and melanoma in people of color. This includes those of African, Asian, Pacific Islander, Indigenous and Hispanic descent. Of the 13 studies that met our criteria for inclusion, 11 showed no association between UV exposure and melanoma. </p>
<p>Among the two studies that showed an association, one study showed a positive <a href="https://doi.org/10.1001/archderm.140.7.819">association between melanoma and UV exposure in Black men</a>. But that same study also examined UV exposure and melanoma in other groups, including Black women, white men and women and Hispanic men and women. In these other groups the researchers found no association between UV exposure and melanoma. This is a surprising result, given that white people are the group in which the association between UV exposure and melanoma has been consistently demonstrated, calling into question the validity of the study results. </p>
<p>The other study showing an association between UV and melanoma <a href="https://doi.org/10.3892/or.2011.1164">was among Hispanic men in Chile</a> based on latitude within the country. A major caveat to this study is that the city with the highest number of melanomas is also home to a large population of Chileans of Croatian descent, who would not be considered people of color.</p>
<p>Unfortunately, none of these studies measured melanin concentrations of individuals, so it is not possible to know whether theoretically lighter-skinned people of color may be at risk for UV-associated melanoma. However, even in light-skinned East Asian individuals, there is no evidence that UV exposure is linked to melanoma.</p>
<p>The bottom line is that the link between UV exposure and melanoma in people of color has been studied many times over and has yielded little to no evidence of a connection.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/274103/original/file-20190513-183089-143tn1g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/274103/original/file-20190513-183089-143tn1g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/274103/original/file-20190513-183089-143tn1g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/274103/original/file-20190513-183089-143tn1g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/274103/original/file-20190513-183089-143tn1g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/274103/original/file-20190513-183089-143tn1g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/274103/original/file-20190513-183089-143tn1g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Darker skin provides more protection from damage by the ultraviolet rays of the sun.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/happy-african-american-family-father-son-116979724?src=8lZJLe5GKU-Gie1opBfdOA-1-17">Spotmatik/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Racial disparities in melanoma outcomes are not related to UV exposure</h2>
<p>Many dermatologists often point out that Black patients tend to show up to the doctor <a href="https://doi.org/10.1016/j.jaad.2016.06.006">with later-stage melanoma</a>, which is true. However, this is an issue of access and awareness and has nothing to do with sunscreen application or protection from the sun. Black people should be aware of growths on their skin and seek medical attention if they have any changing, bleeding, painful or otherwise concerning spots, particularly on the hands and feet. </p>
<p>However, the notion that regular application of daily sunscreen will reduce an already extremely rare occurrence is nonsensical. </p>
<p>UV radiation does affect dark skin and can cause DNA damage; however, the damage <a href="https://doi.org/10.1096/fj.02-0865fje">is seven to eight times lower</a> than the damage done to white skin, given the natural sun-protective effect of increased melanin in darker skin. </p>
<p>To be clear, using regular sunscreen may help with reducing other effects of the sun’s rays such as sunburns, wrinkling, photoaging and freckling, which are all positive. But for the average Black person, sunscreen is unlikely to reduce their low risk of melanoma any further.</p>
<p>If sunscreen were important in the prevention of melanoma in dark-skinned patients, then why have we never heard of an epidemic of melanoma in sub-Saharan Africa, a region with intense sun, a lot of Black people and little sunscreen? </p>
<p>In certain subpopulations of Black people, such as those with disorders causing sun sensitivity, or patients with albinism – a condition in which people produce little or no melanin – or those with suppressed immune systems, sunscreen use may reduce risk of melanoma. But if you don’t fall into one of these categories, any meaningful risk reduction from the application of sunscreen is unlikely.</p>
<h2>One-size-fits-all public health messaging misses the mark</h2>
<p>Many dermatology and skin cancer-focused organizations – a few of which I belong to – promote the public health message of sunscreen use to reduce melanoma risk among Black patients. However, this message is not supported by evidence. There exists no study that demonstrates sunscreen reduces skin cancer risk in Black people. Period.</p>
<p>This issue of regular sunscreen use in Black people was made even more pressing after the release of two recent studies on <a href="https://doi.org/10.1001/jamadermatol.2022.0263">sunscreen absorption</a> in the <a href="https://doi.org/10.1001/jama.2019.20747">Journal of the American Medical Association</a>. This study showed that significant amounts of certain chemical sunscreen ingredients can get in the blood when used at <a href="https://twitter.com/AdeAdamson/status/1125522416837517312">maximal conditions</a>, with unknown impacts on human health. </p>
<p>To me, the most shocking part of the studies were that most of the participants were Black, the group least likely to derive any meaningful associated health benefits from sunscreen, while being exposed to potentially harmful levels of chemicals.</p>
<p>As dermatologists and public health advocates, we can improve how we educate patients and the public about melanoma prevention without promoting public health messages that are <a href="https://www.instagram.com/tv/BxPUuGUFR6X/?utm_source=ig_share_sheet&igshid=1jqzljkns187e">grounded in fear</a> and lack evidence. Black people should be informed that they are at risk of developing melanoma, but that <a href="https://doi.org/10.1001/jamadermatol.2021.2215">risk is low</a>.</p>
<p>Any dark-skinned person who develops a new, changing or symptomatic mole should see a doctor, particularly if the mole is on the palms or soles. We don’t know what the risk factors are for melanoma in Black or dark-skinned people, but they certainly are not UV rays. </p>
<p><em>This is an updated version of a piece that was <a href="https://theconversation.com/sunscreen-wouldnt-have-saved-bob-marley-from-melanoma-and-it-wont-help-other-dark-skinned-people-116979?notice=Article+has+been+updated">published on May 14, 2019</a>.</em></p><img src="https://counter.theconversation.com/content/186539/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adewole S. Adamson receives grant funding for his research from the American Cancer Society, Dermatology Foundation, and Robert Wood Johnson Foundation.</span></em></p>While sunscreen has the potential to reduce skin cancer for light-skinned people, it has never been shown to do the same for Black people. Yet that distinction is lacking in public health messaging.Adewole S. Adamson, Assistant Professor of Internal Medicine (Division of Dermatology), The University of Texas at AustinLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1850742022-06-20T09:37:18Z2022-06-20T09:37:18ZBlue light: what we do and don’t know about the damage it causes our skin<figure><img src="https://images.theconversation.com/files/469485/original/file-20220617-25-ma9rqf.jpg?ixlib=rb-1.1.0&rect=44%2C44%2C5946%2C3943&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Is blue light harmful?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/disappointed-sad-woman-holding-mobile-phone-1129353881">Shutterstock</a></span></figcaption></figure><p>Take a wander down the skincare aisle of any health and beauty retailer and you’ll be met with a bewildering array of creams and sprays, promising to protect you from various threats to your skin.</p>
<p>You might have noticed skincare companies claiming their products can protect you from the effects of blue light. If you hadn’t thought about blue light before, you’d be forgiven for worrying about whether you should be concerned. </p>
<p>First you need to understand what blue light is. </p>
<p>Visible light accounts for 50% of the sunlight spectrum and, as the name suggests, it’s the only part of light that can be detected by the human eye. The blue band of this visible spectrum has a particularly high energy level.</p>
<p>The longer the wavelength, the less energy it transmits. Blue light has very short, high energy waves.</p>
<p>Blue light is all around you. The sun emits blue light. So do fluorescent and incandescent light bulbs, mobile phones, computer screens and flat screen televisions. </p>
<h2>What are the risks?</h2>
<p>There is mounting evidence that blue light can have a harmful effect on the skin and eyes and disrupt the circadian rhythm (your internal clock). Typically, studies investigating the impact of sun radiation on the skin have focused on ultraviolet radiation, particularly UVB, which is responsible for sunburn. The most frequently reported effect of blue light exposure is a <a href="https://pubmed.ncbi.nlm.nih.gov/26977040/">significant increase in reactive oxygen species (ROS)</a>, highly reactive chemicals formed from oxygen. Too much ROS can <a href="https://pubmed.ncbi.nlm.nih.gov/15797866/">damage your DNA</a> and <a href="https://aacrjournals.org/mcr/article/14/7/612/89680/Oxidative-Stress-Induced-Protein-Damage-Inhibits">key enzymes such as those responsible for DNA repair</a>, increasing your risk of cancer. </p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S1011134421002517">Our research</a> showed blue light can induce pigmentation (tanning) across skin types. While many people consider a deep tan a desirable trait, it is a marker of skin damage and ROS. Others researchers found skin tans from visible light (which includes blue light) had <a href="https://www.sciencedirect.com/science/article/pii/S0022202X15349307">darker pigmentation that lasted longer</a> compared to ultraviolet radiation exposure. Our studies also showed blue light can <a href="https://www.nature.com/articles/s41598-018-30738-6">activate genes associated with inflammation and photoageing</a> (skin damge). Several studies have proved typical sunscreens do not prevent <a href="https://www.sciencedirect.com/science/article/pii/S1011134421002517">blue</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/26977040/">visible</a> light damage. </p>
<p>While blue light appears to be less potent than ultraviolet radiation, this may be accounted for by the relatively larger amounts of blue light that reach the Earth. UVR accounts for around 5% of solar radiation in the UK at midday in the summer. Blue light makes up around <a href="https://onlinelibrary.wiley.com/doi/10.1111/php.12422">three times more at 15%</a>.</p>
<p><a href="https://onlinelibrary.wiley.com/doi/10.1111/jocd.13837">There are some beneficial effects</a> of blue light. It has been used to treat skin conditions including <a href="https://www.karger.com/Article/FullText/448000">eczema</a>, it is widely used in <a href="https://journals.lww.com/jdnaonline/Fulltext/2015/05000/Current_Evidence_and_Applications_of_Photodynamic.4.aspx">photodynamic therapy</a>, which is used to treat a range of skins conditions, from acne to cancer, and it boosts <a href="https://pubmed.ncbi.nlm.nih.gov/22081819/">wound healing</a>. But the harmful effects of blue light are likely to outweigh the positives for healthy people.</p>
<figure class="align-center ">
<img alt="Man in bed looks at laptop" src="https://images.theconversation.com/files/469486/original/file-20220617-17-pypzma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469486/original/file-20220617-17-pypzma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469486/original/file-20220617-17-pypzma.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469486/original/file-20220617-17-pypzma.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469486/original/file-20220617-17-pypzma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469486/original/file-20220617-17-pypzma.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469486/original/file-20220617-17-pypzma.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We are all exposed to more blue light than ever before.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-home-front-laptop-watching-movies-1662226270">Shutterstock</a></span>
</figcaption>
</figure>
<p>Blue light can damage the skin but it’s less clear which sources of blue light are harmful to humans. The blue light from screens is responsible for a fraction of the blue light doses we get. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6280109/pdf/JBPE-8-447.pdf">Research</a> has shown screens from devices can increase ROS production. However, a <a href="https://www.beiersdorf.com/newsroom/press-releases/all-press-releases/2021/05/04-cell-phone-screens-do-not-damage-skin#:%7E:text=Artificial%20blue%20light%20has%20negligible,knowledge%20and%20of%20scientific%20studies.">study</a> by German skincare manufacturer Biersdorf found that an entire week’s worth exposure to blue light from a screen at a distance of 30cm is equivalent to just one minute of midday summer sun in Hamburg, Germany. <a href="https://www.sciencedirect.com/science/article/pii/S0190962219333249?via%3Dihub">Another study</a> found blue light from screens were 100 - 1,000 times less intense than blue light from the sun. It also failed to trigger melasma, which causes patches of skin discolouration, in patients who have the condition. It’s true we are spending more time in front of screens than ever before but while screens may cause some damage, it’s insignificant compared with sun exposure. </p>
<h2>Blue light skincare</h2>
<p>The cosmetics industry has started developing a wide range of skincare products that brands claim prevent blue light damage. However, there is <a href="https://onlinelibrary.wiley.com/doi/10.1111/jocd.13854">no regulated or standardised test</a> to assess a product’s ability to prevent blue light damage. Companies do carry out scientific tests on these products. But they can use any number of assessments in their work. This is very different from the regulations around sunscreen that claim to contain <a href="https://www.iso.org/standard/72250.html">Sun protection factor (SPF).</a>. SPF testing is closely regulated by the International Organization for Standardization (ISO). All products that claim to contain an SPF undergo an identical testing regime.</p>
<p>The lack of regulation for blue light claims makes it impossible for consumers to make informed choices about the level of protection offered and differences between products. This lack of regulation is unlikely to be dangerous for consumers, but the benefit from the products may be limited. Given the evidence around blue light emitted by screens, it’s worth applying scepticism to any claims that a product is needed to prevent damage from your computer screen or phone.</p>
<p>Traditional photoprotection products (such as sunscreens) don’t typically protect you from blue light damage. It’s encouraging the skincare industry is trying to address this need. But it is crucial that governments take the next step in the process and develop industry-wide, standardised testing. In the meantime, it is important to remember to limit any exposure to the sun. The use of sunscreens (or any product containing an SPF rating) have been proven to prevent skin cancer and photoageing, and products advertising blue light protection may give an additional benefit.</p><img src="https://counter.theconversation.com/content/185074/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karl Lawrence has previously received funding from the sunscreen industry.</span></em></p>What you need to know about blue light protection lotions.Karl Lawrence, Post Doctoral Researcher, Photobiology, King's College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1835522022-05-30T11:19:05Z2022-05-30T11:19:05ZSunscreen: new natural antioxidant ingredient could boost protection – and other things you should know<figure><img src="https://images.theconversation.com/files/465268/original/file-20220525-14-psubxv.jpg?ixlib=rb-1.1.0&rect=9%2C19%2C6400%2C4247&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sun creams and lotions contain ingredients that refract the sun's rays or make the sun's radiation less harmful.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-brunette-woman-applying-suntan-solar-1928684624">ThirtyPlus/ Shutterstock</a></span></figcaption></figure><p>Summer is around the corner, so it’s time to get out the sun cream. While most sun creams do a pretty good job of protecting against harmful damage caused by the sun’s ultraviolet (UV) rays, our <a href="https://www.mdpi.com/2076-3921/11/3/471">recent study suggests</a> they could be made even better. We found that adding a particular class of antioxidant (a type of molecule thought to help prevent or slow cell damage) to sun creams could help provide more powerful protection against damage from one type of UV radiation than existing ingredients.</p>
<p>The sun emits three types of ultraviolet radiation: UVC, UVB and UVA. Each of these is harmful, but the most harmful are UVC and UVB. Thankfully, the <a href="https://pubmed.ncbi.nlm.nih.gov/28038885/">ozone layer</a> stops many of the harmful rays reaching the Earth’s surface. Many, but not all. Around 95% of the UV rays that reach the Earth’s surface are UVA, but around 5% are the more harmful UVB rays. </p>
<p>Both UVA and UVB are <a href="https://pubmed.ncbi.nlm.nih.gov/34698038/">dangerous types of radiation</a>. UVB directly damages the DNA in your skin cells, while UVA causes indirect damage by generating harmful “free radicals”. These are molecules that can damage the skin cells’ fat, protein and DNA. Over time, the cumulative effects of sun damage can lead to irreversible harm to the skin and may increase the risk of developing skin cancer. </p>
<p>Everyone is at risk of sun damage, regardless of skin type. While people with light skin are more vulnerable to UVB, all skin types appear to be equally sensitive to UVA rays. So people with darker skin can still <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8252523/">experience sun damage</a>, especially from UVA rays. </p>
<p>When most of us go out in the sun, we tend to use sun creams to protect our skin from these harmful rays. Most of these contain either physical sun blockers (such as <a href="https://onlinelibrary.wiley.com/doi/10.1111/phpp.12439">titanium dioxide</a> or zinc oxide) or chemical filters, which most of us know better as <a href="https://pubmed.ncbi.nlm.nih.gov/20354639/">sunscreen</a>.</p>
<p>Physical sun blockers act by scattering or refracting the sun’s rays, while the chemicals in sunscreens <a href="https://link.springer.com/article/10.1007/s43630-021-00013-1">absorb the sun’s UV radiation</a> then convert it into a <a href="https://pubs.rsc.org/en/content/chapter/9781849734882-00245/978-1-84973-488-2">less damaging form</a> that won’t harm skin cells. </p>
<p>In recent years, some sun creams have also begun adding antioxidants, such as vitamins C and E, to neutralise free radicals and protect against UVA radiation. They’re added to act as a second line of defence in case the sun blockers or sunscreens the product contains fail.</p>
<p>But while this sounds promising, many studies have shown that these antioxidants only have a very <a href="https://pubmed.ncbi.nlm.nih.gov/20406189/">modest protective effect</a> when added to sun creams. This is because UVA radiation has a dual damaging effect on skin cells by generating both free radicals and free reactive iron. </p>
<p>Free reactive iron is a <a href="https://www.jidonline.org/article/S0022-202X(15)30990-8/fulltext">dangerous form of iron</a> – different from the nutrient iron that is necessary for the body’s function – that can generate a type of very harmful free radical with even more damaging power towards skin cells. Vitamins C and E haven’t been shown to be effective against free iron. </p>
<p>However, our recent research in human skin cells showed a particular <a href="https://www.mdpi.com/2076-3921/11/3/471">class of antioxidants</a> found in fruit and bark has a dual protective effect against damage from UVA rays. Our study showed that this type of antioxidant was able to both neutralise free radicals and trap free reactive iron, which both build up in the skin when <a href="https://www.pnas.org/doi/full/10.1073/pnas.96.12.6751">exposed to UVA radiation</a>. So adding these antioxidants to sun creams could provide a more effective second line of defence. </p>
<figure class="align-center ">
<img alt="Woman squirts sun cream into the palm of her hard." src="https://images.theconversation.com/files/465269/original/file-20220525-26-mn5nfv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/465269/original/file-20220525-26-mn5nfv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/465269/original/file-20220525-26-mn5nfv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/465269/original/file-20220525-26-mn5nfv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/465269/original/file-20220525-26-mn5nfv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/465269/original/file-20220525-26-mn5nfv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/465269/original/file-20220525-26-mn5nfv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Adding this ingredient could improve sun protection.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-woman-applying-sunscreen-on-her-1129453247">kitzcorner/ Shutterstock</a></span>
</figcaption>
</figure>
<p>The next step in our research will be to understand how we can improve the shelf life of these antioxidants so they remain active for a long time in sun creams. It will also be important for researchers to test whether these antioxidants offer the same level of protection when tested on humans. </p>
<p>This isn’t to say that current sun creams on the market don’t still provide important protection from some of the harm caused by the sun – they certainly do, so be sure to stock up on them.</p>
<h2>How to protect yourself</h2>
<p>To get the <a href="https://www.ouh.nhs.uk/patient-guide/leaflets/files/121203skinandsun.pdf">best protection</a> from the sun, it’s best to avoid going out in the sun between 11am and 3pm. However, if being out in the sun is unavoidable –- because of your occupation, for example – then you need to cover as much of your skin as possible and stay in the shade if you can.</p>
<p>Also, be sure to use the right amount of sun cream, which is 2mg of sun cream per centimetre square of skin. This is equivalent to <a href="https://www.nhs.uk/live-well/seasonal-health/sunscreen-and-sun-safety/">two tablespoons of sun cream altogether</a> for the face and body while wearing a swimming costume. But most people often use about <a href="https://www.cochranelibrary.com/es/central/doi/10.1002/central/CN-00327473/full">a quarter of this amount or even less</a> when they apply their sun cream, meaning they might be missing out on its protective effect. </p>
<p>It’s also important to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8252523/">choose the right SPF</a> (sun protection factor). For very light skin, use products with a high SPF (SPF 50 or higher) that has a five-star UVA protection factor (UVA-PF), which will be listed on the bottle. </p>
<p>For darker skin, SPF 30 and above with a five-star UVA-PF is recommended. For any SPF values of 30 or more, look for a UVA logo on the bottle that has a circle around it. This means that the product meets the EU standard and has protection against both UVA and UVB rays.</p><img src="https://counter.theconversation.com/content/183552/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr. Charareh Pourzand consults for ASEA LLC. The consultancy work delivered by Dr. Pourzand is facilitated by Consultancy Services in Research and Innovation Services (RIS) at the University of Bath. She has received funding from ASEA LLC, British Skin Foundation and BBSRC to conduct some of the work cited in this article. </span></em></p>Different sun creams work in different ways and protect against different ultra violet rays.Charareh Pourzand, Reader, Department of Pharmacy & Pharmacology, University of BathLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1823112022-05-05T18:01:15Z2022-05-05T18:01:15ZCorals and sea anemones turn sunscreen into toxins – understanding how could help save coral reefs<figure><img src="https://images.theconversation.com/files/461387/original/file-20220504-16-dvzlw6.jpg?ixlib=rb-1.1.0&rect=172%2C181%2C4820%2C3423&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Many places have banned sunscreens with certain chemicals in an attempt to help protect coral reefs.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/egypt-red-sea-hurghada-teenage-girl-snorkeling-at-royalty-free-image/932631960?adppopup=true">Westend61 via Getty Images</a></span></figcaption></figure><p>Sunscreen bottles are frequently labeled as “reef-friendly” and “coral-safe.” These claims generally mean that the lotions replaced oxybenzone – a chemical that can harm corals – with something else. But are these other chemicals really safer for reefs than oxybenzone?</p>
<p>This question led <a href="https://mitchlab.sites.stanford.edu/djordje-vuckovic">us</a>, two <a href="https://scholar.google.com/citations?hl=en&user=RQcNZ6QAAAAJ">environmental chemists</a>, to team up with <a href="https://med.stanford.edu/pringlelab/people/john-pringle.html">biologists</a> who study <a href="https://med.stanford.edu/pringlelab.html">sea anemones as a model for corals</a>. Our goal was to uncover how sunscreen harms reefs so that we could better understand which components in sunscreens are really “coral-safe.” </p>
<p>In <a href="https://www.science.org/doi/10.1126/science.abo4627">our new study</a>, published in Science, we found that when corals and sea anemones absorb oxybenzone, <a href="https://doi.org/10.1126/science.abn2600">their cells turn it into phototoxins</a>, molecules that are harmless in the dark but become toxic under sunlight.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dead coral reef." src="https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Reefs around the world – like the Great Barrier Reef seen here – are bleaching and dying because of stressors like increased water temperatures, and sunscreens may be exacerbating the issues.</span>
<span class="attribution"><span class="source">Amanda Tinoco</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Protecting people, harming reefs</h2>
<p>Sunlight is made of many different wavelengths of light. Longer wavelengths – like visible light – are typically harmless. But light at shorter wavelengths – like ultraviolet light – can pass through the surface of skin and damage DNA and cells. Sunscreens, including oxybenzone, work by absorbing most of the UV light and converting it into heat.</p>
<p>Coral reefs around the world have suffered in recent decades from <a href="https://oceanservice.noaa.gov/facts/coralreef-climate.html">warming oceans and other stressors</a>. Some scientists thought that sunscreens coming off of swimmers or from wastewater discharges could also be harming corals. They conducted lab experiments that showed that oxybenzone concentrations as low as 0.14 mg per liter of seawater can <a href="https://doi.org/10.1007/s00244-015-0227-7">kill 50% of coral larvae in less than 24 hours</a>. While most field samples typically have lower sunscreen concentrations, one popular snorkeling reef in the U.S. Virgin Islands <a href="https://doi.org/10.1007/s00244-015-0227-7">had up to 1.4 mg oxybenzone per liter of seawater</a> – more than 10 times the lethal dose for coral larvae. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chemical diagram of oxybenzone." src="https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=403&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=403&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=403&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Oxybenzone is a common ingredient in many sunscreens.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Oxybenzone.svg#/media/File:Oxybenzone.svg">Fvasconcellos via WikimediaCommons</a></span>
</figcaption>
</figure>
<p>Likely inspired by this research and a number of <a href="https://dx.doi.org/10.1289%2Fehp.10966">other studies</a> <a href="https://doi.org/10.1080/10934529.2011.602936">showing damage</a> to <a href="https://doi.org/10.1016/j.aquatox.2008.08.018">marine life</a>, Hawaii’s legislators <a href="https://www.washingtonpost.com/news/energy-environment/wp/2018/05/02/hawaii-might-be-about-to-ban-your-favorite-sunscreen-to-protect-its-coral-reefs/">voted</a> in 2018 to ban oxybenzone and another ingredient in sunscreens. Soon after, lawmakers in other places with coral reefs, like the <a href="https://psmag.com/news/the-us-virgin-islands-bans-potentially-dangerous-sunscreen-chemicals">Virgin Islands</a>, <a href="https://www.nytimes.com/2018/11/02/world/asia/palau-sunscreen-ban-coral.html">Palau</a> and <a href="https://www.visitaruba.com/news/general/aruba-officially-bans-plastics-and-oxybenzone/">Aruba</a>, implemented their own bans.</p>
<p>There is still an <a href="https://theconversation.com/theres-insufficient-evidence-your-sunscreen-harms-coral-reefs-109567">open debate</a> whether the concentrations of oxybenzone in the environment are high enough to damage reefs. But everyone agrees that these chemicals can cause harm under certain conditions, so understanding their mechanism is important. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A number of small test tubes with little sea anemones growing inside of them." src="https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">By putting sea anemones into test tubes with oxybenzone and controlling what kinds of light they were exposed to, we could see whether the sunscreen was reacting to light.</span>
<span class="attribution"><span class="source">Djordje Vuckovic</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Sunscreen or toxin</h2>
<p>While laboratory evidence had shown that sunscreen can harm corals, very little research had been done to understand how. Some studies suggested that oxybenzone <a href="https://doi.org/10.1016/j.envint.2014.05.015">mimics hormones</a>, disrupting reproduction and development. But another theory that our team found particularly intriguing was the possibility that the sunscreen behaved as a <a href="https://doi.org/10.1007/s00244-015-0227-7">light-activated toxin in corals</a>. </p>
<p>To test this, we used the sea anemones our colleagues breed as a model for corals. Sea anemones and corals are closely related and share a lot of biological processes, including a symbiotic relationship with algae that live within them. It is <a href="https://doi.org/10.1016/j.tree.2008.03.004">extremely difficult to perform experiments with corals under lab conditions</a>, so anemones are typically much better for lab-based studies like ours.</p>
<p>We put 21 anemones in test tubes full of seawater under a lightbulb that emits the full spectrum of sunlight. We covered five of the anemones with a box made of acrylic that blocks the exact wavelengths of UV light that oxybenzone normally absorbs and interacts with. Then we exposed all the anemones to 2 mg of oxybenzone per liter of seawater.</p>
<p>The anemones under the acrylic box were our “dark” samples and the ones outside of it our control “light” samples. Anemones, like corals, have a translucent surface, so if oxybenzone were acting as a phototoxin, the UV rays hitting the light group would trigger a chemical reaction and kill the animals – while the dark group would survive.</p>
<p>We ran the experiment for 21 days. On Day Six, the first anemone in the light group died. By Day 17, <a href="https://doi.org/10.1126/science.abn2600">all of them had died</a>. By comparison, none of the five anemones in the dark group died during the entire three weeks. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A close-up of a blue coral." src="https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Corals – like the mushroom coral seen here – and sea anemones absorb oxybenzone and metabolize it, but in doing so, they turn it into a toxin.</span>
<span class="attribution"><span class="source">Christian Renicke</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Metabolism converts oxybenzone to phototoxins</h2>
<p>We were surprised that a sunscreen was behaving as a phototoxin inside the anemones. We ran a chemical experiment on oxybenzone and confirmed that, on its own, it behaves as a sunscreen and not as a phototoxin. It’s only when the chemical was absorbed by anemones that it became dangerous under light. </p>
<p>Any time an organism absorbs a foreign substance, its cells try to get rid of the substance using various metabolic processes. Our experiments suggested that one of these processes was turning oxybenzone into a phototoxin.</p>
<p>To test this, we analyzed the chemicals that formed inside anemones after we exposed them to oxybenzone. We learned that our anemones had replaced part of oxybenzone’s chemical structure – a specific hydrogen atom on an alcohol group – with a sugar. Replacing hydrogen atoms on alcohol groups with sugars is something that <a href="https://passel2.unl.edu/view/lesson/2aee31ac6c74/7#:%7E:text=Phase%20II%20-%20Introduction,-Phase%20II%20reactions&text=reactions%20are%20anabolic%20processes%20which,solubility%20and%20usually%20reduced%20mobility.">plants</a> and <a href="https://doi.org/10.1007/1-4020-4142-X_3">animals</a> commonly do to make chemicals less toxic and more water soluble so they are easier to excrete.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chemical chart showing two different molecular structures." src="https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=155&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=155&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=155&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=195&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=195&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=195&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">When cells try to process oxybenzone, they replace part of an alcohol group (highlighted in red on the left) with a sugar (in red on the right) and in doing so turn the sunscreen into a phototoxin.</span>
<span class="attribution"><span class="source">Djordje Vuckovic</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>But when you remove this alcohol group from oxybenzone, oxybenzone ceases to function as a sunscreen. Instead, it holds on to the energy it absorbs from UV light and kicks off a series of <a href="https://doi.org/10.1111/php.12716">rapid chemical reactions</a> that <a href="https://doi.org/10.1021/acsomega.9b03244">damage cells</a>. Rather than turning the sunscreen into a harmless, easy-to-excrete molecule, the anemones <a href="https://doi.org/10.1126/science.abn2600">convert oxybenzone into a potent, sunlight-activated toxin</a>.</p>
<p>When we ran similar experiments with mushroom corals, we found something surprising. Even though <a href="https://doi.org/10.1016/j.tree.2008.03.004">corals are much more vulnerable to stressors than sea anemones</a>, they did not die from oxybenzone and light exposure during our entire eight-day experiment. The coral made the same phototoxins from oxybenzone, but all of the toxins were stored in the symbiotic algae living in the coral. The algae seemed to absorb the phototoxic byproducts and, in doing so, likely protected their coral hosts. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two rows of photos of sea anemones, with the top row showing a slower death." src="https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=128&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=128&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=128&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=161&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=161&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=161&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This photo series shows how darker-colored anemones on top with algae in them lived longer than the lighter-colored anemones on the bottom that did not have algae living in them.</span>
<span class="attribution"><span class="source">Djordje Vuckovic and Christian Renicke</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We suspect that the corals would have died from the phototoxins if they did not have their algae. It is not possible to keep corals without algae alive in the lab, so we did some experiments on anemones without algae instead. These anemones died about two times faster and had almost three times as many phototoxins in their cells compared than the same anemones with algae.</p>
<h2>Coral bleaching, ‘reef-safe’ sunscreens and human safety</h2>
<p>We believe there are a few important takeaways from our effort to better understand how oxybenzone harms corals. </p>
<p>First, <a href="https://doi.org/10.1126/science.aan8048">coral bleaching events</a> – in which the corals expel their algal symbionts because of high seawater temperatures or other stressors – likely leave corals particularly vulnerable to the toxic effects of sunscreens. </p>
<p>Second, it’s possible that oxybenzone could also be dangerous to other species. In our study, we found that human cells can also turn oxybenzone into a potential phototoxin. If this happens inside the body, where no light can reach, it’s not an issue. But if this occurs in the skin, where light can create toxins, it could be a problem. Previous studies have suggested that oxybenzone <a href="https://doi.org/10.1097/PSN.0000000000000244">could pose health risks to people</a>, and some researchers have recently <a href="https://doi.org/10.1016/j.jaad.2021.12.011">called for more research into its safety</a>.</p>
<p>Finally, the chemicals used in many alternative “reef-safe” sunscreens contain the same alcohol group as oxybenzone – so could potentially also be converted to phototoxins.</p>
<p>We hope that, taken together, our results will lead to safer sunscreens and help inform efforts to protect reefs. </p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://memberservices.theconversation.com/newsletters/?nl=science&source=inline-science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/182311/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Djordje Vuckovic has spoken with Soliome, a company involved in the production of novel sunscreen components. He received funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Bill Mitch has spoken with Soliome, a company involved in the production of novel sunscreen components. He receives funding from the U.S. National Science Foundation and the Stanford Woods Institute of the Environment.</span></em></p>Researchers have long suspected that an ingredient in sunscreen called oxybenzone was harming corals, but no one knew how. A new study shows how corals turn oxybenzone into a sunlight-activated toxin.Djordje Vuckovic, PhD candidate in Civil and Environmental Engineering, Stanford UniversityBill Mitch, Professor of Civil and Environmental Engineering, Stanford UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1799382022-03-27T19:12:25Z2022-03-27T19:12:25ZNo, sunscreen chemicals are not bleaching the Great Barrier Reef<figure><img src="https://images.theconversation.com/files/454291/original/file-20220325-21-5eoulu.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C5200%2C3448&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Getty Images</span></span></figcaption></figure><p>For the sixth time in the last 25 years, the Great Barrier Reef <a href="https://www.gbrmpa.gov.au/the-reef/reef-health">is bleaching</a>. During bleaching events, people are quick to point the finger at different causes, including <a href="https://owlcation.com/stem/Coral-Bleaching-and-Oxybenzone-Choose-Your-Sunscreen-Carefully">sunscreen</a>.</p>
<p>Why sunscreen? Some active ingredients can wash off snorkelers and into the reef, contaminating the area. So could this be the cause of the Barrier Reef’s bleaching? </p>
<p>In a word, no. I reviewed the evidence for sunscreen as a risk to coral in my <a href="https://www.publish.csiro.au/CH/CH21236">new research</a>, and found that while chemicals in sunscreen pose a risk to corals under laboratory conditions, they are only found at very low levels in real world environments. </p>
<p>That means when coral bleaching does occur, it is more likely to be due to the marine heatwaves and increased water temperatures that have come with climate change, as well as land-based run-off. </p>
<h2>Why have we been concerned over the environmental impact of sunscreens?</h2>
<p>After we apply sunscreen, the active ingredients can leach from our skin into the water. When we shower after swimming, soaps and detergents can further strip the these sunscreen chemicals off and send them into our waste water systems. They pass through treatment facilities, which cannot effectively remove them, and end up in rivers and oceans. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="hands putting on sunscreen" src="https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sunscreen isn’t the cause of the coral bleaching.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>It’s no surprise, then, that sunscreen contamination has been detected in freshwater and seas across the globe, from <a href="https://pubmed.ncbi.nlm.nih.gov/15996716/">Switzerland</a> to <a href="https://link.springer.com/article/10.1007/s11356-015-5174-3">Brazil</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/27235899/">Hong Kong</a>. Contamination is highest in the summer months, consistent with when people are more likely to go swimming, and peaks in the hours after people have finished swimming. </p>
<p>Four years ago, the Pacific island nation of Palau made world headlines by announcing plans to <a href="https://www.theguardian.com/world/2018/nov/02/pacific-island-to-introduce-world-first-reef-toxic-sunscreen-ban">ban all sunscreens</a> that contain specific synthetic active ingredients due to concern over the risk they posed to corals. <a href="https://www.cntraveler.com/story/these-destinations-are-banning-certain-sunscreens">Similar bans</a> have been announced by Hawaii, as well a number of other popular tourist areas in the Americas and Caribbean. </p>
<p>These bans are based on independent scientific studies and <a href="https://coralreefpalau.org/wp-content/uploads/2017/10/CRRF-UNESCO-Sunscreen-in-Jellyfish-Lake-no.2732.pdf">commissioned reports</a> which have found contamination from specific active ingredients in sunscreen in the water at beaches, rivers and lakes.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/theres-insufficient-evidence-your-sunscreen-harms-coral-reefs-109567">There's insufficient evidence your sunscreen harms coral reefs</a>
</strong>
</em>
</p>
<hr>
<p>Notably, the nations and regions which have banned these active ingredients, like Bonaire and Mexico, have local economies heavily reliant on summer tourism. For these areas, coral bleaching is not only an environmental catastrophe but an economic loss as well, if tourists choose to go elsewhere.</p>
<h2>How do we know sunscreen isn’t the issue?</h2>
<p>So if contamination concerns over these active ingredients are warranted, how can we be sure they’re not the cause of the bleaching in the Great Barrier Reef? </p>
<p>Put simply, the concentrations of the chemicals are too low to cause the bleaching. </p>
<p>The synthetic ingredients used in most products are highly <a href="https://www.corrosionpedia.com/definition/653/hydrophobic#:%7E:text=Hydrophobic%20is%20a%20property%20of,Oils%20and%20fats%20are%20hydrophobic.">hydrophobic</a> and <a href="https://www.greenfacts.org/glossary/jkl/lipophilic.htm">lipophilic</a>. That means they shun water and love fats, making them hard to dissolve in water. They’d much prefer to stay in the skin until they break down.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/research-check-should-we-be-worried-that-the-chemicals-from-sunscreen-can-get-into-our-blood-116738">Research Check: should we be worried that the chemicals from sunscreen can get into our blood?</a>
</strong>
</em>
</p>
<hr>
<p>Because of this, the levels found in the environment are very low. How low? Think nanograms per litre (a nanogram is 0.000000001 grams) or micrograms per litre (a microgram is 0.00001 grams). Significantly higher levels are found only in waste water treatment sludge and some sediments, not in the water itself.</p>
<p>So how do we reconcile this with studies showing sunscreen can damage corals? Under laboratory conditions, many active ingredients in sunscreen have been found to damage corals as well as <a href="https://pubmed.ncbi.nlm.nih.gov/22828885/">mussels</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/17889917/#:%7E:text=BP%2D2%20was%20accumulated%20in,and%20female%20fish%20were%20observed.">fish</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/24359924/">small crustaceans</a>, and plant-like organisms such as <a href="https://www.sciencedirect.com/science/article/abs/pii/S0269749111006713">algae and phytoplankton</a>.</p>
<p>The key phrase above is “under laboratory conditions”. While these studies would suggest sunscreens are a real threat to reefs, it’s important to know the context. </p>
<p>Studies like these are usually conducted under artificial conditions which can’t account for natural processes. They usually don’t account for the breakdown of the chemicals by sunlight or dilution through water flow and tides. These tests also use sunscreen concentrations up to thousands of times higher – milligrams per litre – compared to real world contamination levels found in collected samples.</p>
<p>In short, laboratory-only studies are not giving us a reliable indication of what happens to these chemicals in real world conditions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Sea wave seen side on" src="https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Laboratory studies don’t tend to account for dilution in seas or rivers.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>If it’s not sunscreen, what is it?</h2>
<p>The greatest threats to the reef are climate change, coastal development, land-based run-off like pesticides, herbicides, and other pollutants, and direct human use like illegal fishing, according to a <a href="https://www.gbrmpa.gov.au/our-work/outlook-report-2019">2019 outlook report</a> issued by the reef’s managing body. </p>
<p>Reefs get their striking colours from single-celled organisms called <a href="https://oceanservice.noaa.gov/education/tutorial_corals/coral02_zooxanthellae.html">zooxanthellae</a> which grow and live inside corals. Importantly, these organisms only grow under very specific conditions, including narrow bands of temperature and light levels. When conditions go outside the zooxanthellaes’ preferred zone, they die and the coral turns white. </p>
<p>As a result, the likeliest cause of this bleaching is <a href="https://www.gbrmpa.gov.au/our-work/threats-to-the-reef/climate-change">climate change</a>, which has increased ocean temperatures and acidity and resulted in more flooding, storms, and cyclones which block light and stir up the ocean floor. </p>
<p>So do you need to worry about the impact of your sunscreen on the environment? No. Sunscreen should remain a key part of our sun protection strategy, as a way to protect skin from UV damage, prevention skin cancers, and slow the visible signs of ageing. Our coral reefs face much bigger issues than sunscreen.</p><img src="https://counter.theconversation.com/content/179938/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Associate Professor Wheate in the past has received funding from the ACT Cancer Council, Tenovus Scotland, Medical Research Scotland, Scottish Crucible, and the Scottish Universities Life Sciences Alliance. He is Fellow of the Royal Australian Chemical Institute. Nial is the Science Director of Canngea Pty Ltd, chief scientific officer of Vairea Skincare LLC, a Board Director of the Australian Medicinal Cannabis Association, and a Standards Australia panel member for sunscreen agents.</span></em></p>Laboratory studies suggest sunscreen chemicals are dangerous to coral reefs. But in real world conditions, that’s not true. Bleaching must have another cause.Nial Wheate, Associate Professor of the Sydney Pharmacy School, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1691552021-12-26T20:27:14Z2021-12-26T20:27:14ZSlip, slop, slurp! The surprising science of sunscreen, sand and ice cream<figure><img src="https://images.theconversation.com/files/435198/original/file-20211202-25-12jv98a.jpg?ixlib=rb-1.1.0&rect=20%2C8%2C1976%2C1320&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Ahh, summer at the beach! The sun on your face, sand between your toes, an ice cream in your hand. </p>
<p>For scientists young and old, a trip to the beach is also a perfect opportunity to explore the peculiar properties of some fascinating fluids. </p>
<h2>Through thick and thin</h2>
<p>Take sunscreen. When you first squeeze sunscreen from the bottle, it spreads easily over your skin, providing an even protective layer against the Sun’s rays. But once on your skin, sunscreen gains a thicker consistency – it has higher <em>viscosity</em> – preventing it from dripping off. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-how-does-sunscreen-work-what-is-spf-and-can-i-still-tan-with-it-on-88869">Explainer: how does sunscreen work, what is SPF and can I still tan with it on?</a>
</strong>
</em>
</p>
<hr>
<p>Viscosity is the ability of a fluid to keep its shape when a force is applied. Sunscreen is what’s called a <em>shear-thinning fluid</em>, which means rubbing it makes its viscosity decrease so it flows more freely.</p>
<p>This effect typically occurs in fluids containing chain-like molecules called polymers. At rest, the polymers are tangled up in an irregular pattern; but when they are pushed around, they rearrange themselves into layers that slide past each other more easily. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/435199/original/file-20211202-23-klmz1g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/435199/original/file-20211202-23-klmz1g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/435199/original/file-20211202-23-klmz1g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/435199/original/file-20211202-23-klmz1g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/435199/original/file-20211202-23-klmz1g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/435199/original/file-20211202-23-klmz1g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/435199/original/file-20211202-23-klmz1g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sunscreen is a ‘shear-thinning fluid’, which means it flows more easily under pressure.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Shear-thinning fluids are quite common. Ketchup is a classic example: it has high viscosity at rest, making it stick to the sides of the bottle until you shake it so its viscosity decreases and it flows out the nozzle. </p>
<p>When the ketchup lands on your plate, its viscosity increases again so it forms a satisfying dollop. (If this is starting to make your mouth water, you’ll be interested to know that saliva is also a shear-thinning fluid.)</p>
<h2>Footprints in the sand</h2>
<p>The opposite of a shear-thinning fluid is a <em>shear-thickening fluid</em>, a material whose viscosity increases with applied force. </p>
<p>A familiar example is very wet sand: if you pick up a handful, it will flow between your fingers like grainy custard. When you squeeze it, however, the sand becomes firm and, counter-intuitively, appears dry. </p>
<p>This behaviour, called the <em>wet-sand effect</em>, occurs because the compressive force of your hand pushes apart tiny grains of sand, creating space that lets water drain away from the surface. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/435201/original/file-20211202-19-wox09w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/435201/original/file-20211202-19-wox09w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=551&fit=crop&dpr=1 600w, https://images.theconversation.com/files/435201/original/file-20211202-19-wox09w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=551&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/435201/original/file-20211202-19-wox09w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=551&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/435201/original/file-20211202-19-wox09w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=692&fit=crop&dpr=1 754w, https://images.theconversation.com/files/435201/original/file-20211202-19-wox09w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=692&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/435201/original/file-20211202-19-wox09w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=692&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Wet sand is a ‘shear-thickening fluid’: under pressure (like from a footstep) it becomes firmer and less runny.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>The same effect allows you to run on wet sand, producing firm and dry patches where your feet land. But if you stand still and gently wiggle your toes, the wet sand reverts to a liquid state, allowing your feet to sink in – and make a pleasing slurp when you pull them out. </p>
<h2>Newton on the beach</h2>
<p>Simpler fluids, such as water, have a more or less constant viscosity. These are called <em>Newtonian fluids</em>, after Isaac Newton, who first wrote down the mathematical law to describe them in his famous 1687 book Principia. </p>
<p>To understand viscosity, imagine drinking water through a straw. When you suck, you create lower pressure at the top of the straw than the bottom, drawing water upwards.</p>
<p>The fluid near the walls of the straw experiences friction, so it flows more slowly than fluid near the centre. Newton reasoned the fluid separates into thin layers that slide over each other with a relative speed that depends on the applied force. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/kitchen-science-the-many-wonders-of-humble-flour-59310">Kitchen Science: the many wonders of humble flour</a>
</strong>
</em>
</p>
<hr>
<p>The viscosity measures the amount of friction between these different layers. The greater the viscosity (think of a milkshake), the more force you must apply to suck the fluid up the straw. </p>
<p>Newton’s law of viscosity, as it is known, is a mathematical ideal. No real fluid behaves exactly this way, but common fluids like water, alcohol, and vegetable oil come pretty close. </p>
<p>By contrast, <em>non-Newtonian fluids</em> — including shear-thinning and shear-thickening fluids — do not obey Newton’s law of viscosity: their viscosity changes depending on how much force is applied to them. </p>
<h2>The scoop on ice cream</h2>
<p>Time for some ice cream. Ice cream is a frozen mixture of cream, milk, sugar, and flavourings, but it is the unique behaviour of cream that is responsible for the dribbly joy of really good ice cream. </p>
<p>Cream is peculiar stuff. It is the fat-enriched portion of milk, separated from its watery base. </p>
<p>The resulting <em>emulsion</em> of fat globules and a small amount of liquid gives cream its silkiness. When cream is whisked, the applied force breaks the membranes of the fat globules, which glom together around trapped air, producing a suspension of bubbles and cream: whipped cream. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/435202/original/file-20211202-15-7eey1l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/435202/original/file-20211202-15-7eey1l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/435202/original/file-20211202-15-7eey1l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/435202/original/file-20211202-15-7eey1l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/435202/original/file-20211202-15-7eey1l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/435202/original/file-20211202-15-7eey1l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/435202/original/file-20211202-15-7eey1l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The light, silky texture of ice cream is all due to tiny air bubbles trapped inside little globules of cream.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Whipped cream is a type of non-Newtonian fluid called a <em>Bingham plastic</em>: at rest, it is semi-solid, forming stiff peaks that are perfect for spooning onto strawberries or scones. But under sufficient force, it can flow like a liquid: through the nozzle of a can of instant whipped cream, for example. </p>
<p>As anyone who has made whipped cream by hand knows, the key ingredient is <em>time</em>. The transformation from liquid to semi-solid is caused by applying force over a period of time.</p>
<p>Air bubbles trapped in the cream give ice cream its pillowy softness. In fact, air can make up to 50% of the total volume of ice cream, which explains why it is less dense than water – and why you can use it to make an ice cream float. </p>
<h2>Fantastic fluids</h2>
<p>Non-Newtonian fluids are found in all sorts of useful substances from biofuels to body armour to blood plasma, and there is still much about them to discover. As Isaac Newton said: </p>
<blockquote>
<p>To myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.</p>
</blockquote>
<p>What better way to spend a summer day? </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-story-of-a-wave-from-wind-blown-ripples-to-breaking-on-the-beach-128458">The story of a wave: from wind-blown ripples to breaking on the beach</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/169155/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shane Keating does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A trip to the beach is a perfect opportunity to explore the peculiar properties of some fascinating fluids.Shane Keating, Senior Lecturer in Mathematics and Oceanography, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1705592021-12-22T21:05:18Z2021-12-22T21:05:18ZDrugs and the sun – your daily medications could put you at greater risk of sunburn<figure><img src="https://images.theconversation.com/files/432801/original/file-20211119-19-1nls6j1.jpg?ixlib=rb-1.1.0&rect=16%2C24%2C5447%2C3506&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>With summer holidays underway, it’s time to think about the sun and your skin. Australia has the <a href="https://www.wcrf.org/dietandcancer/skin-cancer-statistics/">highest rate of skin cancer</a> in the world, so we need to be doing more to protect ourselves from the damaging effects of ultraviolet radiation.</p>
<p>Unfortunately, some medicines can increase your risk of sunburn, because they either enhance UV absorption in your skin or cause you to have a light-activated reaction. </p>
<p>It’s important not to skim over the information provided with your medication, to speak to your pharmacist for on-the-spot advice and to take extra precautions if required.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/i-cant-get-sunburnt-through-glass-shade-or-in-water-right-5-common-sunburn-myths-busted-150640">I can't get sunburnt through glass, shade or in water, right? 5 common sunburn myths busted</a>
</strong>
</em>
</p>
<hr>
<h2>What happens to your skin</h2>
<p>There are two main ways that medications can increase your risk of sunburn; a <a href="https://www.skincancer.org/risk-factors/photosensitivity/">phototoxic reaction and a photoallergic reaction</a>. </p>
<p>A phototoxic reaction is the most common way for a medication to cause an increase in sun sensitivity. This is where the drug molecule is able to absorb UV light, and then releases it back into the skin. Once the oral medication has been absorbed into the blood stream, or after the topical medication is applied to the skin, a phototoxic reaction can occur anytime within minutes or hours of sun exposure. Typically, only the skin that is exposed to the sun will react.</p>
<p>The second, less common mechanism, is via a photoallergic reaction. This can occur with certain medications that are applied directly to the skin, or that are taken by mouth and then circulated to the skin. </p>
<p>After exposure to the sun, a drug can undergo structural changes. Once these structural changes happen, small proteins in our body can bind to the drug, resulting in our immune system recognising it as a foreign substance. Then antibodies are produced to fight it. </p>
<p>The resulting reaction in many cases resembles eczema or a red rash. This type of reaction can take anywhere between one to three days to occur, and will only occur on the parts of the body that are exposed to the sun.</p>
<p>Importantly, both phototoxic and photoallergic reactions are damage to the skin from UV exposure that can increase the risk of later developing skin cancer.</p>
<p>There are also some types of medicines that can cause heat sensitivity and increase your risk of dehydration. This can occur if a medicine has effects that increase urination, prevent sweating, or reduce blood flow to the skin. Examples of these medications include diuretics, some types of antihistamines and stimulant medications for ADHD.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/432800/original/file-20211119-23-1vn7n38.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Pharmacist with medications." src="https://images.theconversation.com/files/432800/original/file-20211119-23-1vn7n38.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/432800/original/file-20211119-23-1vn7n38.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=377&fit=crop&dpr=1 600w, https://images.theconversation.com/files/432800/original/file-20211119-23-1vn7n38.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=377&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/432800/original/file-20211119-23-1vn7n38.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=377&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/432800/original/file-20211119-23-1vn7n38.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=474&fit=crop&dpr=1 754w, https://images.theconversation.com/files/432800/original/file-20211119-23-1vn7n38.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=474&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/432800/original/file-20211119-23-1vn7n38.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=474&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Your local pharmacist can give you advice on medications and sun sensitivity.</span>
<span class="attribution"><a class="source" href="https://image.shutterstock.com/image-photo/pharmacist-holding-medicine-box-capsule-260nw-704036482.jpg">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/common-skin-rashes-and-what-to-do-about-them-91518">Common skin rashes and what to do about them</a>
</strong>
</em>
</p>
<hr>
<h2>Which medicines can affect your skin?</h2>
<p>There are many medicines that can affect your skin and make you more sensitive to the sun, so it’s important to know which ones to look out for. </p>
<p>The first are the antibiotics. Tetracycline-based drugs are particularly known to cause sensitivity. An example is the drug <a href="https://www.nps.org.au/medicine-finder/apo-doxycycline-tablets">doxycycline</a> which is used to treat infections, acne, and as a malaria prophylactic (or prevention) for those who are going to a tropical location (lots of sun). </p>
<p>Other antibiotics known to cause sun sensitivity are <a href="https://www.nps.org.au/australian-prescriber/articles/fluoroquinolone-antibiotics-and-adverse-events">fluoroquinolones</a>, like ciprofloxacin, and <a href="https://www.nps.org.au/medicine-finder/bactrim-ds-tablets">sulfamethoxazole</a>, which treat a broad range of illnesses such as urinary tract infections, pneumonia or gastroenteritis.</p>
<p>The antifungals griseofulvin and voriconazole are known to cause sun sensitivity. You may be taking these medicines for skin or <a href="https://www.healthline.com/health/fungal-nail-infection">nail fungal infections</a>.</p>
<p>For people who suffer from skin conditions such as acne, psoriasis, or eczema, the oral retinoid medications including acitretin and isotretinoin and the topical cream pimecrolimus will leave you sensitive to the sun.</p>
<p>Non-steroidal anti-inflammatory drugs, like diclofenac, can leave you sun sensitive, especially if applied on the skin, so you need to be sure you adequately protect those areas. The same applies for some opioid-based pain patches, <a href="https://www.nps.org.au/radar/articles/fentanyl-patches-durogesic-for-chronic-pain">like fentanyl</a>. When you remove the patch, the skin underneath will be sensitive to the sun.</p>
<p><a href="https://www.nps.org.au/australian-prescriber/articles/amiodarone">Amiodarone</a> is a drug used to treat irregular heart beats and <a href="https://www.nps.org.au/medicine-finder/azathioprine-an-tablets">azathioprine</a> is an immuno suppressing drug used for people who have inflammatory immune conditions or organ transplants. Both are known to cause sun sensitivity.</p>
<p>Finally, a large number of drugs used in <a href="https://blog.uvahealth.com/2019/07/21/chemo-and-sun-sensitivity-how-to-protect-your-skin/">cancer chemotherapy will sensitise your skin</a>. These include: 5-fluorouracil, 5-aminolevulinic acid, vemurafenib, imatinib, mercaptopurine, and methotrexate.</p>
<p>It is important to note that not all people who use one of these medicines will have a sun sensitivity reaction – but extra precautions should be taken. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/432799/original/file-20211119-13-1ezdr9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Woman wearing hat putting on sunscreen" src="https://images.theconversation.com/files/432799/original/file-20211119-13-1ezdr9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/432799/original/file-20211119-13-1ezdr9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=369&fit=crop&dpr=1 600w, https://images.theconversation.com/files/432799/original/file-20211119-13-1ezdr9g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=369&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/432799/original/file-20211119-13-1ezdr9g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=369&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/432799/original/file-20211119-13-1ezdr9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=463&fit=crop&dpr=1 754w, https://images.theconversation.com/files/432799/original/file-20211119-13-1ezdr9g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=463&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/432799/original/file-20211119-13-1ezdr9g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=463&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It is much better to be sun safe than sun sorry.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-woman-bottle-sunblock-outside-on-680463682">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-does-australia-have-so-much-skin-cancer-hint-its-not-because-of-an-ozone-hole-91850">Why does Australia have so much skin cancer? (Hint: it's not because of an ozone hole)</a>
</strong>
</em>
</p>
<hr>
<h2>Protect your skin</h2>
<p>If you are taking a medicine that can make you more sensitive to the sun then always ensure you are <a href="https://www.sunsmart.com.au/">sunsmart</a>.</p>
<p>Remember the five S advice from the <a href="https://www.cancer.org.au/cancer-information/causes-and-prevention/sun-safety/be-sunsmart">Cancer Council</a>: </p>
<ul>
<li>slip on suitable clothing</li>
<li>slop on sunscreen that is rated SPF30 or higher to exposed skin, especially on your face and arms</li>
<li>slap on a hat</li>
<li>seek shade when you can</li>
<li>slide on sunglasses.</li>
</ul>
<p>And if you are concerned a medicine you are taking may be putting you at more risk of sunburn, <a href="https://www.choosingwisely.org.au/resources/consumers-and-carers/5questions">speak to your pharmacist</a>. They can confirm if your medicine does increase your risk of sunburn and discuss options. This could include having your doctor issue a prescription for a different drug. </p>
<p>Never just stop taking a medicine because you are concerned about the risk of sun damage or any other side effects; always discuss it first with your health care provider. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/burnt-is-out-skinscreen-is-in-how-sunscreen-got-a-beauty-makeover-131292">Burnt is out, 'skinscreen' is in. How sunscreen got a beauty makeover</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/170559/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Associate Professor Wheate in the past has received funding from the ACT Cancer Council, Tenovus Scotland, Medical Research Scotland, Scottish Crucible, and the Scottish Universities Life Sciences Alliance. He is Fellow of the Royal Australian Chemical Institute and a member of the Australasian Pharmaceutical Science Association. Nial is science director of the medicinal cannabis company Canngea Pty Ltd, a board member of the Australian Medicinal Cannabis Association, and a Standards Australia committee member for sunscreen agents.</span></em></p><p class="fine-print"><em><span>Elise Schubert is a registered pharmacist at Royal North Shore Hospital, and a PhD Candidate receiving scholarship from the University of Sydney and Canngea Pty Ltd.</span></em></p><p class="fine-print"><em><span>Lisa Kouladjian O'Donnell is a registered consultant pharmacist (independent) and a research fellow in geriatric pharmacotherapy from The University of Sydney. </span></em></p>In Summer, you may need to be extra sun smart if you’re swallowing certain medications or putting them on your skin.Nial Wheate, Associate Professor of the Sydney Pharmacy School, University of SydneyElise Schubert, Pharmacist and PhD Candidate, University of SydneyLisa Kouladjian O'Donnell, Research Fellow in Geriatric Pharmacotherapy, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1506402021-01-03T18:56:54Z2021-01-03T18:56:54ZI can’t get sunburnt through glass, shade or in water, right? 5 common sunburn myths busted<figure><img src="https://images.theconversation.com/files/374149/original/file-20201210-15-a2nj7x.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3376&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Despite decades of public health campaigns, skin cancer remains a major threat to health in Australia, with more cases diagnosed each year <a href="https://www.aihw.gov.au/reports/cancer/skin-cancer-in-australia/">than all other cancers combined</a>.</p>
<p>Skin cancer rates remain high and sunburn is all too common in Australia.</p>
<p>Our research looks at how best to inform people about the hazards of ultraviolet (UV) radiation, including by evaluating and testing <a href="https://www.coolandcovered.com.au/">shade</a>, as well as the development of wearable UV indicators including <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7378694/">stickers</a> and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7531871/">wristbands</a>. While this technology can help to improve people’s sun protection habits, we continue to come up against some common myths about sunburn.</p>
<p>As we’re in the middle of summer, it seems a good time to debunk some of these. </p>
<h2>Myth 1: “You can’t get burnt in the shade”</h2>
<p>Effective shade can provide protection from the Sun’s UV rays, but we can still get burnt in the shade.</p>
<p>Shade materials with holes or gaps can allow penetration by UV radiation.</p>
<p>The same rule applies for <a href="https://www.sciencedirect.com/science/article/abs/pii/S0143622819301006">tree shade</a>, with denser foliage and wider canopies providing better protection than trees with sparse <a href="https://www.sciencedirect.com/science/article/pii/S2215016119301888">foliage</a> and dappled sunlight.</p>
<p>Similarly, solid roof structures with wide overhangs and little sky view <a href="https://www.sciencedirect.com/science/article/abs/pii/S0360132318306280">provide greater UV radiation protection</a> than smaller structures.</p>
<p>Reflected UV radiation is another factor that means you’re not always safe in the shade. The Sun’s rays reflect from light-coloured surfaces and can bounce back under shade.</p>
<p><a href="https://www.arpansa.gov.au/understanding-radiation/what-is-radiation/non-ionising-radiation/ultraviolet-radiation">Light surfaces</a>, such as concrete, light-coloured paint or metallic surfaces, reflect more than dark ones. Sand can reflect as much as <a href="https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Solar-And-Ultraviolet-Radiation-1992">25% of UV radiation</a>. This means if you’re sitting under a beach umbrella, UV radiation can still damage your skin, even though you feel like you’re covered in the shade.</p>
<figure class="align-center ">
<img alt="Woman sitting at the beach under an umbrella" src="https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sand reflects up to 25% of UV radiation.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Myth 2: “You’re safe from the sun when in water”</h2>
<p>Up to 40% of total UV radiation hits the body even half a metre below the surface of the water, <a href="https://www.sunsmart.com.au/advice-for/sports-groups/top-sunsmart-tips-for-your-sport/swimming#:%7E:text=With%20outdoor%20swimming%20taking%20place,good%20sun%20protection%20is%20essential.">according to SunSmart</a>.</p>
<p>Ordinarily, you would have to dive at least <a href="https://www.int-res.com/abstracts/meps/v144/p109-118/">2.5m inshore and 4.5m in offshore coastal waters</a> to avoid harmful UV radiation. This is because offshore waters tend to be clearer, so UV can penetrate further, whereas inshore waters tend to have sediment and nutrients that can cause a rapid decline in UV.</p>
<p>When swimming, you may not notice when your skin is burning due to the cooling effect of water. Reflective surfaces around water environments can also amplify UV, such as concrete or other hard surfaces around a swimming pool. </p>
<p>The importance of adequate sun protection when participating in water-based activities is highlighted by the rate of sunburn in Queenslanders, with <a href="https://www.health.qld.gov.au/research-reports/reports/public-health/cho-report/current/full">45% of children sunburnt</a> in the previous 12 months and 69% of these sunburns acquired during a water-based activity.</p>
<h2>Myth 3: “Exercise makes my skin red hot, not the sun”</h2>
<p>You might often hear people say, when they return from exercise, that they’re red only because they’ve been running. While this does occur, redness from exercise usually dissipates quickly — so if you’re still red in the 24 hours after exercise, it’s sunburn.</p>
<p>When you exercise, your body temperature increases and your body’s natural mechanism is to cool down by carrying blood towards the skin’s surface, causing one to sweat and cool off.</p>
<p>Sweat washes sunscreen away and towelling down wipes off sunscreen.</p>
<p><a href="https://www.cancer.org.au/cancer-information/causes-and-prevention/sun-safety/about-sunscreen/spf50-sunscreen">Regular reapplication</a> of a water-resistant sunscreen is vital. Work-out tan lines are signs of skin damage. Each time our skin gets damaged we greatly increase our risk for skin cancer.</p>
<figure class="align-center ">
<img alt="Person sweating in the sun" src="https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sweat can wash sunscreen away. If you don’t reapply regularly, you risk skin damage.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Myth 4: “That’s not sunburn, it’s windburn”</h2>
<p>Windburn can make your skin red, but in Australia, windburn is pretty rare. It’s more likely to occur in instances like skiing, by very windy, cold and dry conditions, with dense mountain clouds and minimal or no sunlight. In Australia, it’s much more likely to be sunburn.</p>
<p>What’s more, high winds can actually increase the likelihood of getting sunburn. Wind dries out and weakens the outer layer of skin. Wind force can make these dead skin cells fall off.</p>
<p>When you apply sunscreen, it coats this outer layer of skin. As wind brushes these skin cells away your sunscreen goes with it, leaving unprotected skin to be burnt by the sun.</p>
<p>Using sun-protective clothing and reapplying sunscreen are the best ways to avoid skin damage when it’s windy.</p>
<h2>Myth 5: “You can’t get burnt in the car through a window”</h2>
<p>Often, glass used in car side windows is untinted. It reduces UV radiation but doesn’t completely block transmission.</p>
<p>This means you can still get skin damage if you spend a long time in the car next to an untinted side window. Tinted windows can help reduce the amount of UV that hits your skin, and the rule of thumb is that the darker the tint, <a href="https://www.wfaanz.org.au/regulations-automotive/">the more it protects</a> — it’s worth noting, though, that legally you can’t tint your whole front window in Australia, which is obviously the biggest window in the car.</p>
<p>More commonly, however, <a href="https://pubmed.ncbi.nlm.nih.gov/20226568/">people are sunburnt in cars</a> when they have the side windows down and are exposed to a short period of high levels of UV radiation.</p>
<figure class="align-center ">
<img alt="A person driving a car with their arm out the window" src="https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">It is possible to get sunburnt with the windows up in a car. But it’s more common to get burnt when you’ve wound down the windows.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Simple solutions are the five sun-safe measures — slip, slop, slap, seek, slide:</p>
<ul>
<li><p>slip on a long-sleeved shirt. If you’re in water, this might include a rashie or wetsuit.</p></li>
<li><p>slop on an SPF 30 or higher sunscreen, and reapply at least every two hours, or sooner after swimming or sweating</p></li>
<li><p>slap on a broad-brimmed hat</p></li>
<li><p>seek shade</p></li>
<li><p>slide on sunnies.</p></li>
</ul><img src="https://counter.theconversation.com/content/150640/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elke Hacker receives funding from the Queensland Government Advance Queensland fund. She undertakes contract research projects receiving funding from Cancer Council Victoria, Suncayr Ptd Ltd and SunFly Brands Inc. She'd also like to acknowledge Naomi Stekelenburg from QUT, who contributed to this article.</span></em></p><p class="fine-print"><em><span>Louise Baldwin receives project funding from Cancer Institute NSW and has previously received funding under the Advancing Queensland Age Friendly Community Grant scheme.</span></em></p>UV radiation can reflect off surfaces like sand or concrete, meaning shade doesn’t always prevent sunburn.Elke Hacker, Research Fellow, Queensland University of TechnologyLouise Baldwin, Senior Research Fellow, School of Public Health and Social Work, Faculty of Health, Queensland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1312922020-02-24T02:02:52Z2020-02-24T02:02:52ZBurnt is out, ‘skinscreen’ is in. How sunscreen got a beauty makeover<figure><img src="https://images.theconversation.com/files/316396/original/file-20200220-92507-5v3zf0.png?ixlib=rb-1.1.0&rect=12%2C7%2C1171%2C1063&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.instagram.com/calltimeonmelanoma/">Instagram/#Calltimeonmelanoma</a></span></figcaption></figure><p>Under Australia’s harsh sun, we’ve long slapped on sunscreen to protect ourselves from skin damage and cancer. </p>
<p>Now the product, once known for protecting skin against harmful UV rays, is becoming part of beauty routines. Sunscreen products are described as <a href="https://www.instagram.com/p/B8xsloAFPbi/">rich</a>, <a href="https://www.mecca.com.au/mecca-cosmetica/to-save-face-spf50-superscreen-75g/I-020875.html">luxe</a> or <a href="https://www.sephora.com.au/products/fresh-sugar-lip-treatment-sunscreen-spf-15/v/icon">nourishing</a>. </p>
<p>When did the cultural perception of sunscreen as a health imperative shift towards a lifestyle “must have”? And will this new pitch work to keep us sun safe? </p>
<h2>Campaigns of old</h2>
<p>Sun safety promotions work to combat dangerous tanning behaviour. </p>
<p>The iconic <a href="https://www.sunsmart.com.au/tools/videos/past-tv-campaigns/slip-slop-slap-original-sunsmart-campaign.html">Slip, Slop, Slap campaign</a> paved the way for how we see sun protection today. In the 1980s, it was instrumental in educating Australians about sun exposure and skin cancer.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/b7nocIenCYg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Sid the Seagull in full flight.</span></figcaption>
</figure>
<p>The campaign’s mascot, Sid the Seagull, sang and danced on our screens, encouraging us to slip on a shirt, slop on sunscreen and slap on a hat. </p>
<p>The slogan was extended to <a href="https://www.sunsmart.com.au/tools/videos/current-tv-campaigns/slip-slop-slap-seek-slide-sid-seagull.html">Slip, Slop, Slap, Seek, Slide</a> in 2007, adding two more tips to preventing sun damage: seeking shade and sliding on sunglasses. </p>
<p>These campaigns aimed to refocus Australians’ attitudes to sun protection as a necessity, despite our traditionally sun-drenched lifestyle. </p>
<p>In the 1990s, advertisements shifted their tone from catchy jingles to sexual appeals. The <a href="https://www.sunsmart.com.au/tools/videos/past-tv-campaigns/leave-your-hat-on1.html">Leave Your Hat On</a> campaign took inspiration from a striptease scene in the film <a href="https://www.imdb.com/title/tt0091635/">9/12 Weeks</a>, reversing it with a couple putting on sunscreen, clothes, hats and sunglasses. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/O0EaQEa2Xo8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Take it all off – no wait, put it back on again!</span></figcaption>
</figure>
<p>The campaign targeted young men, as they were most at risk of developing skin cancer. However, the messages of these advertisements did not stick in the minds of Australians. The <a href="https://www.researchgate.net/publication/310537900_Australian_young_adults'_tanning_behaviour_The_role_of_ideal_skin_tone_and_sociocultural_norms">cultural norm of tanning</a> remained steadfast.</p>
<h2>Education through fear</h2>
<p>When sex didn’t work to implement sun safety practices, campaigns used scare tactics instead. In the summer of 2003, skin cancer was branded as <a href="https://www.youtube.com/watch?v=xrenZCKMgjc&feature=youtu.be">killer body art</a> and the effects of sunburn, even if only mild, were portrayed as creating a <a href="https://www.youtube.com/watch?v=witly6zMCVw&feature=youtu.be">timebomb</a> under the skin. </p>
<p>These “<a href="https://link.springer.com/chapter/10.1007/978-3-319-45596-9_17">slice of death narratives</a>” – where the advertisement’s focus is on the negative consequences of poor decisions – highlighted the potentially fatal results of sun exposure. In 2007, <a href="https://www.sunsmart.com.au/tools/videos/past-tv-campaigns/clare-oliver-no-tan-is-worth-dying-for.html">Clare Oliver</a>, battling end-stage melanoma, shared her story to highlight the dangers of solariums and the cultural ideal of tanning. </p>
<p>The true story of <a href="https://www.youtube.com/watch?v=X1P1po6bH3w&feature=youtu.be">Wes Bonny</a>, told by the relatives of a 26-year-old man who died from melanoma in 2010, spoke volumes about skin cancer affecting an everyday “Aussie guy”. </p>
<p>In 2016, Melbourne mother <a href="https://www.sunsmart.com.au/about/media-campaigns/current-campaigns/belindas-story">Belinda</a> shared her story before her death from melanoma. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/tocIb3ITHhM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Melbourne mother Belinda urged others to learn from her story.</span></figcaption>
</figure>
<p>The campaigns were created to increase people’s vigilance with sun protection, and sunscreen became a product critical to protecting one’s health.</p>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/25794474">Evidently</a>, these messages were effective. Research showed <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4732951/">lower sunburn rates</a> across the population, and sun protective behaviours improved. </p>
<p>Moreover, research into the investment into such campaigns <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147665">found</a> every A$1 invested brought a return of A$3.85 by lowering treatment costs and increasing productivity. The campaigns reduced the rates of illness and death and the economic burden of skin cancer. </p>
<h2>A new beauty product?</h2>
<p>As consumer demand bloomed, the perception and branding of sun protection products changed. </p>
<p>The Australian sunscreen market is expected to tip <a href="https://www.cosmeticsbusiness.com/news/article_page/Asia_Pacific_Australia_Sun_Care_Market_Report_2017/128516">A$159.3 million this year</a>. By marketing sunscreen as a key step in a daily skincare routine, brands are repositioning sunscreen as a beauty essential. </p>
<p>The new buzzword “<a href="https://www.whyhellobeauty.com.au/2019/06/20/sunscreen-or-skinscreen/">skinscreen</a>” has been coined for products that combine skincare and sunscreen. To persuade women to add skinscreens in their beauty regimes, products are marketed with appealing fragrances and textures, and are encouraged to be worn under makeup. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/B8vZytqgMTp","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Beauty influencers on social media have jumped on-board the skinscreen craze. It is now marketed to highlight its anti-ageing <a href="https://annals.org/aim/article-abstract/1691733/sunscreen-prevention-skin-aging-randomized-trial">benefits</a>: preventing age spots, fine lines and wrinkles. </p>
<p>There are pros and cons to luxe skinscreen messaging. It may encourage frequent sunscreen application, but it also suggests women’s beauty and youth are inextricably linked and women’s value lies chiefly in their appearance. </p>
<p>Despite sunscreen’s new home in the beauty aisle, health messaging has not completely disappeared. The social media initiative <a href="https://www.calltimeonmelanoma.com.au/">Call Time on Melanoma</a> aims to spread awareness about skin cancers and protecting skin from harmful rays. </p>
<p>With more than 21,000 Instagram followers, the account encourages people to wear sunscreen everyday, get regular skin checks and debunks myths about sunscreen. The initiative builds awareness by sharing the story of Natalie Fornasier, a woman who was diagnosed with stage III melanoma at age 20. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/314671/original/file-20200211-146704-1f5t6tp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/314671/original/file-20200211-146704-1f5t6tp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/314671/original/file-20200211-146704-1f5t6tp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/314671/original/file-20200211-146704-1f5t6tp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/314671/original/file-20200211-146704-1f5t6tp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/314671/original/file-20200211-146704-1f5t6tp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/314671/original/file-20200211-146704-1f5t6tp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/314671/original/file-20200211-146704-1f5t6tp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Not just for the beach. Sunscreen is now being pitched as part of a beauty routine.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/smiling-woman-hat-applying-sunscreen-on-1401651737">www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>Skincare brand La Roche-Posay was an <a href="https://www.laroche-posay.com.au/article/la-roche-posay-the-official-sunscreen-partner-of-australian-open-2019/a36405.aspx">official sunscreen partner</a> for the 2020 Australian Open. They offered a UV Experience to educate tennis fans about sunscreen protection and ran a campaign to raise awareness of the daily UV index.</p>
<p>Although important questions should be asked about the re-branding of sunscreen creating additional appearance-based pressures and “beauty work” for women, sunscreen appears to be more popular than ever. Sunsmart campaigns may have laid the health messaging groundwork, but today’s skincare brands continue to build awareness. This is a welcome step towards keeping Australians sun safe.</p><img src="https://counter.theconversation.com/content/131292/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lauren Gurrieri does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sunscreens’ change in branding from health essential to beauty product could help us slop on more cream - but it also creates more ‘beauty work’ for women.Lauren Gurrieri, Senior Lecturer in Marketing, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1288982020-01-16T14:00:02Z2020-01-16T14:00:02ZWhy you need more Vitamin D in the winter<figure><img src="https://images.theconversation.com/files/308468/original/file-20200103-11904-v09oed.jpg?ixlib=rb-1.1.0&rect=13%2C0%2C4448%2C3064&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Vitamin D is sometimes called the sunshine vitamin. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/vitamin-d-keeps-you-healthy-while-1148457554">FotoHelin/Shutterstock.com</a></span></figcaption></figure><p>Winter is upon us and so is the risk of vitamin D deficiency and infections. Vitamin D, which is made in our skin following sunlight exposure and also found in <a href="https://health.gov/dietaryguidelines/2015/guidelines/appendix-12/">oily fish (mackerel, tuna and sardines), mushrooms and fortified dairy and nondairy substitutes</a>, is essential for good health. Humans need vitamin D to <a href="https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#h7">keep healthy and to fight infections</a>. The irony is that in winter, when people need vitamin D the most, most of us are not getting enough. So how much should we take? Should we take supplements? How do we get more? And, who needs it most?</p>
<p><a href="https://vbs.psu.edu/research/labs/cantorna">I am a medical microbiologist and immunologist</a> who studies the functions of vitamin D in immune cells. My laboratory has been interested in figuring out why the immune system has vitamin D receptors that determine which cells can use vitamin D. In the immune system, vitamin D acts to improve your ability to <a href="https://doi.org/10.1016/j.tem.2019.04.005">fight infections</a> and to <a href="https://doi.org/10.1080/10409238.2019.1611734">reduce inflammation</a>.</p>
<h2>Where to get your vitamin D</h2>
<p>Vitamin D is called the sunshine vitamin since it is made in the skin after exposure to sun. The same UVB rays that cause a sunburn also make vitamin D. Sunscreen, darker skin pigmentation, clothing and reduced daylight in winter diminish the skin’s ability to make vitamin D. The people who experience the biggest seasonal swings in vitamin D levels are fair-skinned individuals <a href="https://doi.org/10.3390/nu10040457">living in the northern regions</a> of the U.S. and at <a href="https://doi.org/10.3945/an.117.015578">higher latitudes around the globe</a> where there is very little daylight in winter. </p>
<p>But those most at risk for low vitamin D levels are people of color and people living at higher latitudes. Dark-skinned individuals are more likely than fair-skinned individuals to be low for vitamin D year-round because the darker skin blocks the UVB rays from producing vitamin D. However, even in dark skinned individuals, vitamin D is lowest in the winter. </p>
<p>In the winter, in addition to high vitamin D food, adults should take additional vitamin D from foods and/or supplements to <a href="https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#en1">get at least 600 IU per day of vitamin D.</a> People who have dark skin or avoid sunshine should eat more vitamin D year-round. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/309314/original/file-20200109-80111-jn47z5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/309314/original/file-20200109-80111-jn47z5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=501&fit=crop&dpr=1 600w, https://images.theconversation.com/files/309314/original/file-20200109-80111-jn47z5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=501&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/309314/original/file-20200109-80111-jn47z5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=501&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/309314/original/file-20200109-80111-jn47z5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=630&fit=crop&dpr=1 754w, https://images.theconversation.com/files/309314/original/file-20200109-80111-jn47z5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=630&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/309314/original/file-20200109-80111-jn47z5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=630&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Food rich in vitamin D.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/vitamin-d-containing-foods-376614841">photka/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Vitamin D is important for bones and your microbes</h2>
<p>Originally, doctors thought that vitamin D was only important for bone health. This was because the vitamin D deficiency caused bone diseases like <a href="http://doi.org/10.1172/JCI29449">rickets in children and osteoporosis in adults.</a>. However, in the 1980s scientists discovered that <a href="https://www.jci.org/articles/view/111557">immune cells</a> <a href="https://science.sciencemag.org/content/224/4656/1438">had receptors for vitamin D</a>. </p>
<p>My group’s research has shown that vitamin D plays an important role in <a href="https://doi.org/10.1080/10409238.2019.1611734">maintaining health in the gastrointestinal tract</a>. <a href="https://iai.asm.org/content/84/11/3094">Higher levels of vitamin D</a> reduce <a href="https://doi.org/10.1016/j.tem.2019.04.005">susceptibility to inflammatory bowel disease</a> and <a href="http://doi.org/10.1038/ajg.2016.53">Crohn’s disease</a>, <a href="https://doi.org/10.3389/fimmu.2019.00001">gut</a> and <a href="http://doi.org/10.1128/IAI.00679-16">lung infections</a> in animals and people. </p>
<p>My colleagues and I have discovered that one of the ways vitamin D functions is by keeping the microbes in the gut healthy and happy. Vitamin D <a href="https://doi.org/10.1177/1535370214523890">increases the number and diversity of microbes</a> living in the gut, which together reduce inflammation throughout the body. </p>
<p>Low vitamin D levels are <a href="https://doi.org/10.1038/nrgastro.2015.34">associated with inflammatory bowel disease</a> in humans. Researchers have found that <a href="https://doi.org/10.1007%2Fs00535-017-1313-6">inflammatory bowel disease patients in Japan</a> have more symptoms in winter than during other seasons. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/309317/original/file-20200109-80122-1r4bify.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/309317/original/file-20200109-80122-1r4bify.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/309317/original/file-20200109-80122-1r4bify.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/309317/original/file-20200109-80122-1r4bify.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/309317/original/file-20200109-80122-1r4bify.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/309317/original/file-20200109-80122-1r4bify.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/309317/original/file-20200109-80122-1r4bify.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/309317/original/file-20200109-80122-1r4bify.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">People with darker skin are most likely to have low vitamin D levels year-round.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/pile-hands-isolated-on-white-caucasian-8316760">Lucian Coman/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Why is vitamin D more important in winter?</h2>
<p>In the winter, humans are exposed to more infections and spend less time outside. Exactly how much vitamin D healthy adults should have is debated. Some authorities recommend from <a href="https://www.nature.com/articles/nrendo.2017.31">200 IU per day to 2,000 IU per day</a>. In the U.S., the <a href="https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/">Institutes of Medicine</a> recommends 600-800 IU per day for adults, while the <a href="https://doi.org/10.1210/jcem.96.12.zeg3908">Endocrine Society states that optimal vitamin D status</a> may require 1500-2,000 IU per day. In the winter, people have a reduced ability to make vitamin D when they go outside, so amounts of at least 600 IU per day of vitamin D from food or supplements would help maintain vitamin D status at summer levels. </p>
<p>But, just like many things, <a href="https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/">too much vitamin D can be harmful</a>. Vitamin D toxicity does not result from too much sun or food. Because of the risk of skin cancer, dermatologists and other health professionals do not recommend unprotected sun exposure to boost your vitamin D. Instead they suggest supplements. But vitamin D toxicity can occur if an individual takes too many.</p>
<p>The experts that set the national intakes of vitamin D for the U.S. recommend that adult individuals take <a href="https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/">no more than 4,000 IU per day of vitamin D</a> to avoid toxic side effects. Vitamin D helps you absorb calcium from your diet, but when vitamin D is too high, calcium levels in the blood go up and that can lead to kidney disease. </p>
<p>By consuming more vitamin D during the winter your gut microbes will be healthier and you’ll be more resistant to infection and inflammation year-round. </p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/128898/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Margherita T. Cantorna receives funding from the National Institutes of Health.</span></em></p>Vitamin D is essential for good health and particularly for fighting infections and keeping the microbes in the human gut healthy. But in winter it can be difficult to get enough.Margherita T. Cantorna, Distinguished Professor of Molecular Immunology, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1258792020-01-05T18:52:43Z2020-01-05T18:52:43Z4½ myths about sunscreen and why they’re wrong<figure><img src="https://images.theconversation.com/files/306275/original/file-20191211-95149-63unt5.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C1000%2C553&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ouch! Here's the evidence to bust some myths about sunscreen. Now, there's no excuse to look like a rock lobster this summer.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-woman-back-sunburn-yellow-bikini-1536500750">from www.shutterstock.com</a></span></figcaption></figure><p>Many Australians are <a href="https://www.cancer.org.au/news/media-releases/almost-half-of-australians-confused-about-sunscreen.html">reluctant to use sunscreen</a>, even though it’s an important element in preventing the skin cancers that affect about <a href="https://onlinelibrary.wiley.com/doi/epdf/10.5694/j.1326-5377.2006.tb00086.x">two in three of us</a> at some time in our lives. </p>
<p>The Cancer Council <a href="https://www.cancer.org.au/news/media-releases/almost-half-of-australians-confused-about-sunscreen.html">says</a> myths about sunscreens contribute to this reluctance.</p>
<p>Here are 4½ sunscreen myths and what the evidence really says. Confused about the ½? Well, it’s a myth most of the time, but sometimes it’s true.</p>
<h2>Myth #1. It’s bad for my bones</h2>
<p>Many Australians are concerned using sunscreen might lead to <a href="https://www.ncbi.nlm.nih.gov/pubmed/17641980">vitamin D deficiency</a>. The idea is that sunscreen would block the UV light the skin needs to make vitamin D, critical for bone health.</p>
<p>However, you need <a href="https://www.sciencedirect.com/science/article/pii/S0190962205045962?via%3Dihub">far less UV than you think</a> to make the vitamin D you need: only one-third of the UV that causes a sunburn, and less than you need to tan.</p>
<p>Tests on humans going about their daily business generally show <a href="https://www.ncbi.nlm.nih.gov/pubmed/30945275">no vitamin D differences</a> between people who use sunscreen and those who don’t.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mondays-medical-myth-were-not-getting-enough-sun-10205">Monday's medical myth: we’re not getting enough sun</a>
</strong>
</em>
</p>
<hr>
<h2>Myth #2. Its ingredients are toxic</h2>
<p>If you google “toxic sunscreen”, you get more than <a href="https://www.google.com/search?client=firefox-b-d&q=toxic+sunscreen">eight million results</a>. So people are clearly worried if it’s safe. </p>
<p>However, there’s little evidence of harm compared to the large benefits of sunscreens, which are <a href="https://www.tga.gov.au/sunscreens">highly regulated in Australia</a>.</p>
<p>There <a href="https://www.ncbi.nlm.nih.gov/pubmed/15191542?dopt=Abstract">is evidence</a> large amounts of some sunscreen components can act as <a href="https://www.niehs.nih.gov/health/topics/agents/endocrine/index.cfm">hormone disruptors</a>. But the amounts needed far outstrip the amount sunscreen users are actually exposed to.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/306461/original/file-20191211-95130-9p1fuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/306461/original/file-20191211-95130-9p1fuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306461/original/file-20191211-95130-9p1fuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306461/original/file-20191211-95130-9p1fuh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306461/original/file-20191211-95130-9p1fuh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306461/original/file-20191211-95130-9p1fuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306461/original/file-20191211-95130-9p1fuh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306461/original/file-20191211-95130-9p1fuh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some ingredients can act as hormone disruptors. But the amounts needed far outstrip the amount sunscreen users are actually exposed to.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/closeup-young-caucasian-man-wearing-tshirt-583526149?src=fc3ba272-c03d-4f51-bdbc-1c8d3365b8a8-1-44&studio=1">from www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>Some people have also been alarmed by the US Food and Drug Administration (FDA) <a href="https://www.fda.gov/drugs/news-events-human-drugs/spotlight-cder-science-new-fda-study-shines-light-sunscreen-absorption">announcing further testing</a> of the sunscreen ingredients avobenzone, oxybenzone, octocrylene and ecamsule. This was after a <a href="https://jamanetwork.com/journals/jama/fullarticle/2733085">study</a> showed their concentrations could reach over 0.5 nanograms/mL in the blood.</p>
<p>This experiment involved people thickly applying sunscreen to parts of the body not covered by a swimsuit, four times a day for four days in a row. In other words, this is the maximum amount you might apply on a beach holiday, and considerably more than you would wear on a day-to-day basis (unless you work in your budgie smugglers). </p>
<p>However, there’s no evidence these concentrations are harmful and the further testing is just a precaution.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/research-check-should-we-be-worried-that-the-chemicals-from-sunscreen-can-get-into-our-blood-116738">Research Check: should we be worried that the chemicals from sunscreen can get into our blood?</a>
</strong>
</em>
</p>
<hr>
<p>The FDA recommends people <a href="https://www.fda.gov/drugs/news-events-human-drugs/spotlight-cder-science-new-fda-study-shines-light-sunscreen-absorption">continue using sunscreen</a>. If you still feel uneasy, you can stick to zinc oxide and titanium dioxide sunscreens, which the FDA says are “<a href="https://www.federalregister.gov/documents/2019/02/26/2019-03019/sunscreen-drug-products-for-over-the-counter-human-use">generally recognised as safe and effective</a>”. </p>
<p><strong>How about nanoparticles?</strong></p>
<p>That leads us to another common concern: nano-sized zinc oxide or titanium dioxide in sunscreens. <a href="https://www.tga.gov.au/community-qa/sunscreens-information-consumers">Nanoparticle forms</a> of these UV filters are designed to make them invisible on the skin while still keeping UV rays out. </p>
<p><a href="https://www.tga.gov.au/literature-review-safety-titanium-dioxide-and-zinc-oxide-nanoparticles-sunscreens">Human studies</a> show they either do not penetrate or minimally penetrate the stratum corneum. This is the upper-most layer of the skin, where the cells are already dead and tightly packed together to protect the living cells below. This suggests absorption and movement through the body, hence toxicity, is highly unlikely.</p>
<h2>Myth #3. It’s pointless. I already have skin cancer in my family</h2>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3835091/">Genetics and family history</a> do play a role in many melanomas in Australia. For instance, mutations in genes such as CDKN2A substantially increase a person’s <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6368081/">melanoma risk</a>. </p>
<p>However, sun exposure increases melanoma risk on top of any existing genetic risk. So whatever your baseline risk, everyone can take steps to lower the additional risks that come with sun exposure.</p>
<h2>Myth #4. I’m already middle-aged. It’s too late</h2>
<p>It’s true that sunburns in childhood seem to have a disproportionate effect on the risk of <a href="https://www.ncbi.nlm.nih.gov/pubmed/11227927">melanomas</a> and <a href="https://www.ncbi.nlm.nih.gov/pubmed/11684447">basal cell carcinomas</a>. But <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/bjd.15324">squamous cell carcinomas</a> are more affected by sun exposure over the years.</p>
<p>Ongoing sunscreen use also reduces the number new actinic keratoses, a pre-cancerous skin lesion, and reduces the number of existing keratoses <a href="https://www.nejm.org/doi/10.1056/NEJM199310143291602?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dwww.ncbi.nlm.nih.gov">in Australians over 40 years old</a>. </p>
<p>Regular sunscreen use also puts the brakes on <a href="https://www.sciencedirect.com/science/article/pii/S0190962216308805?via%3Dihub">skin ageing</a>, helping to reduce skin thinness, easy bruising and poor healing that older skin can be prone to. And of course, getting burnt feels terrible at any age.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-happens-to-your-skin-when-you-get-sunburnt-53865">Explainer: what happens to your skin when you get sunburnt?</a>
</strong>
</em>
</p>
<hr>
<h2>Myth #4½. I’m allergic to sunscreen</h2>
<p>This one’s only half a myth. Many people <a href="https://journals.lww.com/dermatitis/fulltext/2010/07000/True_Photoallergy_to_Sunscreens_Is_Rare_Despite.1.aspx#R4-1">say they have</a> an allergic reaction to sunscreen but only about <a href="https://www.sciencedirect.com/science/article/pii/S0140673698121682?via%3Dihub">3%</a> really do.</p>
<p>Often, people are just sunburned. They <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/hpja.301">thought they were well-protected</a> but simply stayed out in the sun too long, or didn’t reapply sunscreen often enough. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/BWGpUWoDmF0","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Your sunscreen might also be <a href="https://www.tga.gov.au/book/export/html/5307">out of date</a>. Sunscreen eventually breaks down and loses its effectiveness, faster if you store it somewhere very hot, like a car.</p>
<p>Alternatively, you may have <a href="https://www.dermnetnz.org/topics/polymorphic-light-eruption/">polymorphic light eruption</a>, a condition where UV light alters a skin compound, resulting in a rash. This can be itchy or burning, small pink or red bumps, flat, dry red patches, blisters, or even itchy patches with no visible signs.</p>
<p>Fortunately, this condition often occurs only on the first exposure during spring or early summer. Keep out of the sun for a few days and the rash should settle by itself.</p>
<p>If none of those causes fit the bill, you may indeed have <a href="https://www.dermnetnz.org/topics/sunscreen-allergy/">an allergy</a> to some component of your sunscreen (<a href="https://www.dermnetnz.org/topics/allergic-contact-dermatitis/">allergic contact dermatitis</a>), which a dermatologist can confirm.</p><img src="https://counter.theconversation.com/content/125879/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Prof Monika Janda receives funding from the NHMRC, MRFF, Harry LLoyd Foundation; Cancer Australia, Digital Health Agency.</span></em></p><p class="fine-print"><em><span>Katie Lee does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Do you know people who cling to myths about sunscreen? Here’s the evidence to convince them they’re wrong.Katie Lee, Research assistant, The University of QueenslandMonika Janda, Professor in Behavioural Science, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1258812019-12-25T21:47:09Z2019-12-25T21:47:09ZHow to pick the right sunscreen when you’re blinded by choice<figure><img src="https://images.theconversation.com/files/306504/original/file-20191212-85404-mfdgo7.jpg?ixlib=rb-1.1.0&rect=5%2C1%2C992%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">We're spoilt for choice when it comes to sunscreen in Australia. So how do you choose the right one?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/blurred-image-rows-hair-care-skin-788928742">from www.shutterstock.com</a></span></figcaption></figure><p>There’s an enormous variety of sunscreens to choose from. <a href="https://www.woolworths.com.au/shop/search/products?searchTerm=sunscreen">Major</a> <a href="https://shop.coles.com.au/a/a-national/everything/search/sunscreen">supermarkets</a> each sell more than 60 options. And one large <a href="https://www.chemistwarehouse.com.au/search?searchtext=sunscreen&searchmode=allwords">pharmacy chain</a> sells more than 100.</p>
<p>So how do you choose sunscreen that’s right for you?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/inducing-choice-paralysis-how-retailers-bury-customers-in-an-avalanche-of-options-116078">Inducing choice paralysis: how retailers bury customers in an avalanche of options</a>
</strong>
</em>
</p>
<hr>
<h2>The big 4 must haves</h2>
<p>Sunscreens need to tick these <a href="https://wiki.cancer.org.au/policy/Fact_sheet_-_Sunscreen">four major boxes</a>:</p>
<ol>
<li><p><strong>The sun protection factor, or SPF, should be at least 30, preferably 50.</strong> SPF describes how much UV gets to the skin. SPF50 allows just 1/50th (2%) of the UV to reach the skin</p></li>
<li><p><strong>Go for broad spectrum protection</strong>, which filters the <a href="https://link.springer.com/article/10.1007%2Fs40257-017-0290-0">full UV light spectrum</a>. UVB rays (290-320nm wavelengths) are responsible for most sunburn and DNA damage, but UVA rays (320-400nm) also cause DNA damage and accelerate skin ageing</p></li>
<li><p><strong>Aim for water resistant formulations</strong>, which <a href="https://www.dermcoll.edu.au/wp-content/uploads/ACD-Position-Statement-Sunscreen-March-2017-updated.pdf">stay on longer</a> in sweaty conditions, and when exercising or swimming. But no sunscreen is completely waterproof </p></li>
<li><p><strong>Make sure the sunscreen is approved in Australia</strong>. Approval from the Therapeutic Goods Administration (TGA) is the final must-have. All sunscreens for sale in Australia must meet the <a href="https://www.tga.gov.au/book/3-regulatory-categories-sunscreens">TGA’s requirements</a> and will carry an AUST number on the packaging. They can only contain ingredients from an approved list that have been tested for safety and efficacy. And the SPF, water resistance and broad spectrum action must be established by <a href="https://www.tga.gov.au/book/4-labelling-and-advertising">testing on human skin</a>. Sunscreens bought overseas don’t necessarily have these safeguards, so proceed with caution.</p></li>
</ol>
<p>Once you’ve ticked off the big four, you can limit your options by how the sunscreen is delivered, its ingredients, and other factors.</p>
<h2>Pump pack, roll-on or spray?</h2>
<p>The sunscreen delivery system is more important than you might think. Sunscreen works best when you <a href="https://www.tga.gov.au/community-qa/sunscreens-information-consumers">use lots</a> — a teaspoon for each limb, a teaspoon each for your front and back, and a teaspoon for your face and neck. </p>
<p>This is easiest to achieve with pump packs or squeeze tubes. People apply far less sunscreen when they use a <a href="https://jamanetwork.com/journals/jamadermatology/fullarticle/1149913">roll-on</a>. Spray-on sunscreen is <a href="https://www.cancer.org.au/news/blog/prevention/cancer-council-and-sunscreens-what-you-need-to-know-this-summer.html">even worse</a>; the TGA recommends you apply <a href="https://www.tga.gov.au/behind-news/be-sun-smart-wear-sunscreen">one-third of a whole can</a> for proper coverage. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/dJcLUCyn38o?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How to use sunscreen (Cancer Council)</span></figcaption>
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<h2>Look and feel, sensitive skin and kids</h2>
<p>Now we get down to the finer choices in sunscreen, and they depend on your personal concerns and preferences. Here are a few common choices.</p>
<p><strong>How to avoiding looking greasy</strong></p>
<p>Greasiness is the most off-putting thing about sunscreen for <a href="https://www.ncbi.nlm.nih.gov/pubmed/28449221">many</a> <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ajd.12636">Australians</a>. </p>
<p>But there are non-greasy formulations, often marketed as “dry-touch” or “matte finish”. These can be comparatively expensive, but worth it if greasiness is your main barrier to using sunscreen. </p>
<p>Your skin may still look shiny immediately after applying it. But it should return to a matte finish within 10-20 minutes as the sunscreen settles into the epidermis, the outer layer of the skin. </p>
<p><strong>How about sunscreen for sensitive or acne-prone skin?</strong></p>
<p><a href="https://www.dermnetnz.org/topics/sensitive-skin/">Sensitive skin</a> is irritated by a wide variety of cosmetics, lotions and fragrances. So, you can use ones marketed as kids’ sunscreen because these tend to be fragrance-free. </p>
<p>You can also choose sunscreens with ingredients such as <a href="https://www.tga.gov.au/literature-review-safety-titanium-dioxide-and-zinc-oxide-nanoparticles-sunscreens">zinc oxide or titanium dioxide</a>, which <a href="https://www.dermcoll.edu.au/atoz/sun-protection-sunscreens/">partially reflect and also absorb</a> UV rays.</p>
<p>Those so-called physical blockers are <a href="https://www.sciencedirect.com/science/article/abs/pii/S0887233311001585?via%3Dihub">very unlikely</a> to cause allergic or irritant rashes. But they appear white on the skin, unless you chose an option with nano-sized particles, which are invisible to the eye.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/306488/original/file-20191212-85397-i1352o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/306488/original/file-20191212-85397-i1352o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306488/original/file-20191212-85397-i1352o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306488/original/file-20191212-85397-i1352o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306488/original/file-20191212-85397-i1352o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306488/original/file-20191212-85397-i1352o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306488/original/file-20191212-85397-i1352o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306488/original/file-20191212-85397-i1352o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Sunscreens containing zinc oxide or titanium oxide are unlikely to inflame sensitive skin.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cheerful-freckled-girl-113065540">from www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>If your skin is prone to acne, <a href="https://www.dermcoll.edu.au/wp-content/uploads/ACD-Position-Statement-Sunscreen-March-2017-updated.pdf">good options</a> are lotions or gels, rather than creams, and products marked oil-free or non-comedogenic.</p>
<p>Sensitive and acne-prone skin is often limited to the face and neck, so it can be cheaper to have a specialist sunscreen for those parts and a cheaper one for the rest of your body.</p>
<p><a href="https://www.dermnetnz.org/topics/sunscreen-allergy/">Sunscreen allergies</a> are rarer but do affect up to <a href="https://www.sciencedirect.com/science/article/pii/S0140673698121682?via%3Dihub">3% of people</a>. They’re generally caused by a single sunscreen component, usually preservatives or fragrances. A dermatologist can patch test individual ingredients, which you can then avoid by checking labels. </p>
<p><strong>What’s the best sunscreen for my kids?</strong></p>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/26101815">Parents worry</a> about the effects of both UV exposure and chemical exposure. And of course, small children can be pretty anti-sunscreen.</p>
<p>All Australian sunscreen chemicals are approved by the TGA and are <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/1753-6405.12873">recommended for daily use</a>, even on kids. Plus, many kids’ sunscreens are made with sensitive skin in mind, because skin sensitivity is <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1468-2494.2012.00754.x">more common in young children</a>. If your child doesn’t have <a href="https://dermnetnz.org/topics/sensitive-skin/">sensitive skin</a> (skin that reacts with itching or burning sensations to a wide range of body care products), adult sunscreens are fine too.</p>
<p>However, <a href="https://www.dermcoll.edu.au/wp-content/uploads/ACD-Position-Statement-Sunscreen-March-2017-updated.pdf">babies under six months old</a> need a physical blocker sunscreen.</p>
<h2>What not to do</h2>
<p>The <a href="https://iheard.com.au/question/i-heard-of-a-recipe-for-natural-homemade-sunscreen-do-these-work/">Cancer Council</a> and the <a href="https://www.tga.gov.au/blogs/tga-topics/everything-you-ever-wanted-know-about-sunscreens-were-afraid-ask">TGA</a> strongly recommend against homemade sunscreens. </p>
<p>Natural oils and other ingredients promoted in recipes found online generally have <a href="https://www.medicalnewstoday.com/articles/325217.php#1">a low SPF</a>. And, as they have not been tested for causing irritation, can react unpredictably with the skin.</p>
<p><a href="https://www.tga.gov.au/book/2-therapeutic-sunscreen-or-cosmetic-sunscreen">Cosmetics that contain sunscreen</a>, such as lipstick or foundation with an SPF rating, are not regulated as tightly as regular sunscreens in Australia. </p>
<p>Cosmetics with an SPF 30 or higher can have good protection <a href="https://wiki.cancer.org.au/policy/Fact_sheet_-_Sunscreen">when you first apply them</a>. But like regular sunscreens, they need to be reapplied throughout the day. That’s not something we usually do, unless you’re going for the caked-on look. </p>
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Read more:
<a href="https://theconversation.com/explainer-what-happens-to-your-skin-when-you-get-sunburnt-53865">Explainer: what happens to your skin when you get sunburnt?</a>
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<img src="https://counter.theconversation.com/content/125881/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Spray, pump or roll-on? Matte, fragrance-free, oil-free? No wonder we’re confused when it comes to buying sunscreen.Katie Lee, Research assistant, The University of QueenslandErin McMeniman, Senior Lecturer Princess Alexandra Hospital Southside Clinical Unit and Casual Research Assistant, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.