tag:theconversation.com,2011:/id/topics/radiation-damage-11803/articlesRadiation damage – The Conversation2019-06-21T14:27:31Ztag:theconversation.com,2011:article/1191842019-06-21T14:27:31Z2019-06-21T14:27:31ZWhy plants don’t die from cancer<figure><img src="https://images.theconversation.com/files/280726/original/file-20190621-61747-1s3g4p6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An abandoned hotel building in Pripyat, a few miles from Chernobyl.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/inside-hotel-abandoned-pripyat-city-chernobyl-728433472?src=LRikqvrql7m5t-QFSdnLSg-1-6&studio=1">Fotokon/Shutterstock</a></span></figcaption></figure><p>Chernobyl has become a byword for catastrophe. The 1986 nuclear disaster, recently brought back into the public eye by the hugely popular <a href="https://www.youtube.com/watch?v=s9APLXM9Ei8">TV show</a> of the same name, <a href="https://www.who.int/ionizing_radiation/chernobyl/backgrounder/en/">caused thousands of cancers</a>, turned a once populous area into a ghost city, and resulted in the setting up of an exclusion zone 2600km² in size.</p>
<p>But Chernobyl’s exclusion zone isn’t devoid of life. <a href="https://www.theguardian.com/environment/2015/oct/05/wildlife-thriving-around-chernobyl-nuclear-plant-despite-radiation">Wolves, boars</a> and <a href="https://www.weforum.org/agenda/2019/05/what-s-going-on-in-chernobyl-today/">bears</a> have returned to the lush forests surrounding the old nuclear plant. And when it comes to vegetation, all but the most <a href="https://www.ceh.ac.uk/news-and-media/blogs/understanding-ecological-impact-major-fire-chernobyl-red-forest">vulnerable and exposed plant life</a> never died in the first place, and even in the most radioactive areas of the zone, vegetation was recovering <a href="https://www-pub.iaea.org/MTCD/Publications/PDF/Pub1001_web.pdf">within three years</a>.</p>
<p>Humans and other mammals and birds would have been killed <a href="http://www.unscear.org/docs/publications/1996/UNSCEAR_1996_Report.pdf">many times over</a> by the radiation that plants in the most contaminated areas received. So why is plant life so resilient to radiation and nuclear disaster?</p>
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<p>To answer this question, we first need to understand how radiation from nuclear reactors affects living cells. Chernobyl’s radioactive material is “unstable” because it is constantly firing out high energy particles and waves that <a href="https://www.frontiersin.org/articles/10.3389/fpls.2018.00847/full">smash cellular structures</a> or produce reactive chemicals which attack the cells’ machinery.</p>
<p>Most parts of the cell are replaceable if damaged, but DNA is a crucial exception. At higher radiation doses, DNA becomes garbled and cells die quickly. Lower doses can cause subtler damage in the form of <a href="https://www.sciencedirect.com/science/article/pii/S0160412007002474?via%3Dihub">mutations</a> altering the way that the cell functions – for example, causing it to become cancerous, multiply uncontrollably, and spread to other parts of the body.</p>
<p>In animals this is often fatal, because their cells and systems are highly specialised and inflexible. Think of animal biology as an intricate machine in which each cell and organ has a place and purpose, and <a href="https://science.sciencemag.org/content/360/6396/1391">all parts must work and cooperate for the individual to survive</a>. A human cannot manage without a brain, heart or lungs.</p>
<p>Plants, however, develop in a much more flexible and organic way. Because they can’t move, they have no choice but to adapt to the circumstances in which they find themselves. Rather than having a defined structure as an animal does, plants <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-3040.2009.01929.x">make it up</a> as they go along. Whether they grow deeper roots or a taller stem <a href="https://academic.oup.com/aob/article/92/1/1/177536">depends on</a> the balance of chemical signals from other parts of the plant and the “<a href="https://theconversation.com/how-trees-communicate-via-a-wood-wide-web-65368">wood wide web</a>”, as well as light, temperature, water and nutrient conditions.</p>
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<img alt="" src="https://images.theconversation.com/files/280731/original/file-20190621-61756-7oh2sx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/280731/original/file-20190621-61756-7oh2sx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/280731/original/file-20190621-61756-7oh2sx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/280731/original/file-20190621-61756-7oh2sx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/280731/original/file-20190621-61756-7oh2sx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/280731/original/file-20190621-61756-7oh2sx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/280731/original/file-20190621-61756-7oh2sx.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">Trees have reclaimed the area surrounding the old nuclear power station.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/abandoned-pripyat-city-nuclear-power-station-1097280545?src=LRikqvrql7m5t-QFSdnLSg-1-63&studio=1">Fotokon/Shutterstock</a></span>
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<p>Critically, unlike animal cells, almost all plant cells are able to create new cells of whatever type the plant needs. This is why a gardener can grow new plants from cuttings, with roots sprouting from what was once a stem or leaf.</p>
<p>All of this means that plants can replace dead cells or tissues <a href="https://www.sciencedirect.com/science/article/pii/S136952661630070X?via%3Dihub">much more easily</a> than animals, whether the damage is due to being attacked by an animal or to radiation.</p>
<p>And while radiation and other types of DNA damage can cause tumours in plants, mutated cells are generally not able to spread from one part of the plant to another as cancers do, thanks to the <a href="https://www.ncbi.nlm.nih.gov/books/NBK26928/">rigid, interconnecting walls</a> surrounding plant cells. Nor are <a href="https://www.nature.com/articles/380481a0.pdf">such tumours fatal</a> in the vast majority of cases, because the plant can find ways to work around the malfunctioning tissue.</p>
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<img alt="" src="https://images.theconversation.com/files/280724/original/file-20190621-61771-1mf6wtk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/280724/original/file-20190621-61771-1mf6wtk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/280724/original/file-20190621-61771-1mf6wtk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/280724/original/file-20190621-61771-1mf6wtk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/280724/original/file-20190621-61771-1mf6wtk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/280724/original/file-20190621-61771-1mf6wtk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/280724/original/file-20190621-61771-1mf6wtk.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">The rigid and interconnecting walls of plant cells make them resistant to cancer.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cell-structure-hydrilla-view-leaf-surface-714995158?src=-LjnPq3qpAFcLtnCXGMfSw-1-0&studio=1">Rattiya Thongdumhyu/Shutterstock</a></span>
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<p>Interestingly, in addition to this innate resilience to radiation, some plants in the Chernobyl exclusion zone seem to be using extra mechanisms to <a href="http://www.plantphysiol.org/content/135/1/357">protect</a> their DNA, changing its chemistry to make it <a href="https://www.sciencedirect.com/science/article/pii/S0027510703001039?via%3Dihub">more resistant to damage</a>, and turning on systems to <a href="https://www.sciencedirect.com/science/article/pii/S1568786416302440?via%3Dihub">repair</a> it if this doesn’t work. Levels of natural radiation on the Earth’s surface were <a href="https://www.frontiersin.org/articles/10.3389/fpls.2018.00847/full">much higher</a> in the distant past when early plants were evolving, so plants in the exclusion zone may be drawing upon adaptations dating back to this time in order to survive.</p>
<h2>A new lease of life</h2>
<p>Life is now thriving around Chernobyl. Populations of many plant and animal species are actually <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(15)00988-4?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982215009884%3Fshowall%3Dtrue">greater</a> than they were before the disaster.</p>
<p>Given the tragic loss and shortening of human lives associated with Chernobyl, this <a href="https://interestingengineering.com/the-plants-and-animals-of-the-chernobyl-exclusion-zone">resurgence of nature</a> may surprise you. Radiation does have <a href="http://cricket.biol.sc.edu/chernobyl/papers/Mousseau-et-al-TREES-2013.pdf">demonstrably harmful</a> effects on <a href="https://www.smithsonianmag.com/science-nature/forests-around-chernobyl-arent-decaying-properly-180950075/">plant life</a>, and may shorten the lives of individual plants and animals. But if life-sustaining resources are in abundant enough supply and burdens are not fatal, then life will flourish. </p>
<p>Crucially, the burden brought by radiation at Chernobyl is less severe than the benefits reaped from humans leaving the area. Now essentially one of Europe’s largest nature preserves, the ecosystem supports more life than before, even if each individual cycle of that life lasts a little less. </p>
<p>In a way, the Chernobyl disaster reveals the true extent of our environmental impact on the planet. Harmful as it was, the nuclear accident was far less destructive to the local ecosystem than we were. In driving ourselves away from the area, we have created space for nature to return.</p><img src="https://counter.theconversation.com/content/119184/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stuart Thompson has received funding from MAFF and the Nuffield Foundation and has consulted to the University of Copenhagen.</span></em></p>Most plant life survived the nuclear disaster at Chernobyl - and they have a lack of legs to thank for it.Stuart Thompson, Senior Lecturer in Plant Biochemistry, University of WestminsterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/818032017-09-15T10:21:37Z2017-09-15T10:21:37ZSeeds in space – how well can they survive harsh, non-Earth conditions?<figure><img src="https://images.theconversation.com/files/185909/original/file-20170913-18075-165yqah.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Spend many months attached to the ISS and see how well you grow.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/station/research/experiments/1674.html">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Will we someday colonize space? Will our children visit other planets? To achieve goals like these, we’ll need to crack one crucial challenge: how to feed ourselves for long periods away from Earth.</p>
<p>A <a href="http://www.mars-one.com/faq/mission-to-mars/how-long-does-it-take-to-travel-to-mars">trip to Mars would take months</a>, and exploring the depths of the galaxy would take even longer. Provision of nutritious food for travelers is a significant obstacle. While stockpiling food is an option, storing enough to last many months strains weight and space limitations in spacecraft – and missions could easily outlast food shelf life. Growing food in space will be essential.</p>
<p>Essential – and not necessarily easy. The conditions in the vacuum of space are quite harsh compared to Earth. Seeds in space must be able to withstand large doses of ultraviolet and cosmic radiation, low pressure and microgravity. </p>
<p>Believe it or not, the first space travelers were seeds. In 1946, <a href="https://www.nasa.gov/pdf/449089main_White_Sands_Missile_Range_Fact_Sheet.pdf">NASA launched a V-2 rocket carrying maize</a> seeds to observe how they’d be affected by radiation. Since then, the scientific community has learned <a href="https://doi.org/10.1079/SSR200193">a great deal</a> about the effects of the space environment on seed <a href="https://doi.org/10.1016/j.asr.2011.05.017">germination</a>, <a href="https://doi.org/10.1016/0273-1177(86)90076-1">metabolism</a>, <a href="https://doi.org/10.1016/j.asr.2005.06.043">genetics</a>, <a href="http://journal.ashspublications.org/content/130/6/848.short">biochemistry</a> and even <a href="https://doi.org/10.1016/S0273-1177(03)00250-3">seed</a> <a href="https://doi.org/10.1016/j.actaastro.2006.09.009">production</a>. </p>
<p>Astrobiologists David Tepfer and Sydney Leach recently investigated <a href="https://doi.org/10.1089/ast.2015.1457">how seeds would do back on Earth</a> after spending extended periods on the International Space Station. The experiments they conducted on the <a href="https://www.nasa.gov/mission_pages/station/research/experiments/696.html">EXPOSE</a> <a href="https://www.nasa.gov/mission_pages/station/research/experiments/211.html">missions</a> were much longer than many other ISS seed experiments, and placed the seeds on the outside of the station, in the dead of space, rather than inside. The goal was to understand not only the effects of long-term radiation exposure, but a bit about the molecular mechanisms of those effects.</p>
<h2>Seeds have some defenses</h2>
<p>Seeds possess a couple of remarkable traits that Tepfer and Leach hypothesized would give these “model space travelers” a fighting chance.</p>
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<a href="https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=575&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=575&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=575&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=722&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=722&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=722&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">Seeds protect their important insides with a strong external seed coat.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Dycotyledon_seed_diagram-en.svg">LadyofHats</a></span>
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<p>First, they contain multiple copies of important genes – what scientists call redundancy. Genetic redundancy is common in flowering plants, especially food products such as <a href="https://www.sciencedaily.com/releases/2014/09/140930090636.htm">seedless watermelon and strawberries</a>. If one genetic copy is damaged, there’s still another available to do the job.</p>
<p>Secondly, seed coats contain chemicals called flavonoids that act as sunscreens, protecting the seed’s DNA from damage by ultraviolet (UV) light. On Earth, our planet’s atmosphere filters out some harmful UV light before it can reach us. But in space, there is no protective atmosphere.</p>
<p>Would these special features be enough to let the seeds survive or even thrive? To find out, Tepfer and Leach conducted a series of experiments – both outside the International Space Station and back on Earth – with tobacco, <em>Arabidopsis</em> (a flowering plant commonly used in research) and morning glory seeds. </p>
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<a href="https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=440&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=440&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=440&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=553&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=553&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=553&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">The EXPOSE-R experiment attached to the exterior of the International Space Station.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/station/expeditions/expedition26/russian_eva27.html">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>Bombarded with energy</h2>
<p>Their EXPOSE-E experiment flew to the International Space Station (ISS) in 2008 and lasted 558 days – so just under two years.</p>
<p>They stored the seeds in a single layer on the outside of the ISS behind a special kind of glass that let in ultraviolet radiation only at wavelengths between 110 and 400 nanometers. DNA readily absorbs UV radiation in this wavelength range. A second, identical set of seeds was on the ISS, but shielded completely from UV radiation. The purpose of this experimental design was to observe the effects of UV radiation separately from other types of radiation <a href="https://www.space.com/32644-cosmic-rays.html">like cosmic rays</a> that are everywhere in space.</p>
<p>Tepfer and Leach chose tobacco and <em>Arabidopsis</em> seeds for EXPOSE-E because both have a redundant genome and therefore good odds for survival. They also included a genetically engineered variety of tobacco with an antibiotic resistance gene added; the plan was to later test this gene in bacteria and determine if there was any damage. In addition to normal <em>Arapidopsis</em>, they sent up two genetically modified strains of the plant that contained low and absent UV-protective chemicals in their seed coat. They also sent purified DNA and purified flavonoids. This gave the researchers a wide range of scenarios by which to understand the effects of space on the seeds.</p>
<p>A second ISS mission called EXPOSE-R included only the three types of <em>Arabidopsis</em> seeds. These received a little over double the dose of ultraviolet light because of the longer experiment time, 682 days. Lastly, researchers performed a ground experiment back in the lab that exposed <em>Arabidopsis</em>, tobacco and morning glory seeds to very high doses of UV light for only a month.</p>
<p>After all these various exposure conditions, it was time to see how well the seeds could grow.</p>
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<a href="https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=515&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 Expose-R experiment was equipped with three trays containing a variety of biological samples – including seeds.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/station/multimedia/exp18_eva2.html">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>What would researchers reap?</h2>
<p><a href="https://doi.org/10.1089/ast.2015.1457">When the seeds returned to Earth</a>, the researchers measured their germination rates – that is, how quickly the root emerged from the seed coat.</p>
<p>The seeds that had been shielded in the lab did the best, with more than 90 percent of them germinating. Next came the seeds that had been exposed to UV radiation for one month in the laboratory, with better than 80 percent germinating. </p>
<p>For the space-traveling seeds, more than 60 percent of the shielded seeds germinated. A mere 3 percent of space UV-exposed seeds did.</p>
<p>The 11 <em>Arabidopsis</em> plants that did grow from both the wild type and genetically engineered seeds did not survive once planted in soil. Tobacco plants, however, showed reduced growth but that growth rate recovered in subsequent generations. Tobacco has a much heartier seed coat and a more redundant genome, which may explain its apparent survival advantage.</p>
<p>When the researchers plugged the antibiotic resistance gene into bacteria, they found it was still functional after its trip to space. That finding suggests it’s not genetic damage that’s making these seeds less viable. Tepfer and Leach attributed the reduced germination rate to damage to other molecules in the seed besides DNA – such as proteins. A redundant genome or built-in DNA repair mechanisms weren’t going to overcome that damage, further explaining why the <em>Arabidopsis</em> plants didn’t survive transplanting.</p>
<p>In the ground experiments, the researchers found that radiation damage is dose-dependent – the more radiation the seeds received, the worse their germination rate.</p>
<p>These discoveries could inform future directions for research in space agriculture. Scientists may consider genetically engineering seeds to have added protection for the cellular machinery critical for protein synthesis, such as ribosomes. Future research will also need to explore further how seeds stored in space germinate in microgravity, rather than on Earth.</p>
<p>As researchers add to the knowledge of how space affects plants and their seeds, we can continue to make the strides necessary toward producing food in space. It will be a crucial step toward sustainable colonies that can survive beyond the comfortable confines of Earth’s biosphere.</p><img src="https://counter.theconversation.com/content/81803/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gina Riggio is affiliated with Blue Marble Space.</span></em></p>If you want to live on Mars, you’re going to need to grow food. Seeds are naturally equipped to handle challenging Earth environments, but how well can they survive what they’ll encounter off-planet?Gina Misra, Ph.D. Student in Cell and Molecular Biology, University of ArkansasLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/579422016-04-25T13:49:12Z2016-04-25T13:49:12ZForget Fukushima: Chernobyl still holds record as worst nuclear accident for public health<p>The 1986 Chernobyl and 2011 Fukushima nuclear power plant accidents both share the notorious distinction of attaining the highest accident rating on the International Atomic Energy Agency (IAEA) <a href="http://www-ns.iaea.org/tech-areas/emergency/ines.asp">scale of nuclear accidents</a>. No other reactor incident has ever received this Level 7 “major accident” designation in the history of nuclear power. Chernobyl and Fukushima earned it because both involved core meltdowns that released significant amounts of radioactivity to their surroundings.</p>
<p>Both of these accidents involved evacuation of hundreds of thousands of residents. Both still have people waiting to return to their homes. And both left a legacy of large-scale radioactive contamination of the environment that will persist for years to come, despite ongoing cleanup efforts.</p>
<p>So the tendency is to think of these accidents as similar events that happened in different countries, 25 years apart.</p>
<p>But the IAEA scale isn’t designed to measure public health impact. In terms of health ramifications, these two nuclear accidents were not even in the same league. While <a href="http://www.who.int/ionizing_radiation/a_e/fukushima/faqs-fukushima/en/">Fukushima</a> involved radioactivity exposures to hundred of thousands of people, <a href="http://www.who.int/mediacentre/news/releases/2005/pr38/en/index1.html">Chernobyl</a> exposed hundreds of millions. And millions of those received substantially more exposure than the people of Fukushima.</p>
<p>On the occasion of the 30th anniversary of the April 26, 1986 Chernobyl accident in Ukraine, we do well to reflect on the health burden it caused – and compare it with what we expect to see from Japan’s Fukushima nuclear accident. As I report in my book “<a href="http://press.princeton.edu/titles/10691.html">Strange Glow: The Story of Radiation</a>,” from a public health standpoint, there’s really no comparison between the two events. </p>
<h2>Higher doses of radiation, more health harm</h2>
<p>Chernobyl was by far the worst reactor accident of all time. A total of 127 reactor workers, firemen and emergency personnel on site sustained radiation doses sufficient to cause radiation sickness (over 1,000 mSv); some received doses high enough to be lethal (over 5,000 mSv). Over the subsequent six months, <a href="http://pegasusbooks.com/books/atomic-accidents-9781605984926-hardcover">54 died from their radiation exposure</a>. And it’s been estimated that 22 of the 110,645 cleanup workers may have <a href="https://www.ucsf.edu/news/2012/11/13087/chernobyl-cleanup-workers-had-significantly-increased-risk-leukemia">contracted fatal leukemias</a> over the next 25 years.</p>
<p>In contrast, at Fukushima, there were no radiation doses high enough to produce radiation sickness, even among the reactor core workers. Two Fukushima workers who had leaky respirators received effective doses of <a href="http://pegasusbooks.com/books/atomic-accidents-9781605984926-hardcover">590 mSv and 640 mSv</a>. That’s above the Japanese occupational limit for conducting lifesaving rescue work (250 mSv), but still below the threshold for radiation sickness (1,000 mSv). Due to their exposure, the two workers’ lifetime cancer risks will <a href="http://press.princeton.edu/titles/10691.html">increase about 3 percent</a> (from the 25 percent background cancer risk rate to about 28 percent), but they are unlikely to experience other health consequences.</p>
<p>Beyond just the plant workers, over 572 million people among 40 different countries got at least some exposure to Chernobyl radioactivity. (Neither the United States nor Japan was among the exposed countries.) It took two decades to fully assess the cancer consequences to these people. Finally, in 2006, an international team of scientists completed a comprehensive <a href="http://dx.doi.org/10.1002/ijc.22037">analysis of the dose and health data</a> and reported on the cancer deaths that could be attributed to Chernobyl radioactivity.</p>
<p>Their detailed analysis included countrywide estimates of individual radiation doses in all 40 exposed countries, and regionwide estimates for the most highly contaminated regions of the most highly contaminated countries (Belarus, Russian Federation and Ukraine).</p>
<p>Using statistical models, the scientists predicted a total of 22,800 radiation-induced cancers, excluding thyroid cancers, among this group of 572 million people. Thyroid cancer warranted separate special scrutiny, as we will discuss presently; this hormonally important gland is uniquely affected by a specific radioactive isotope, iodine-131.</p>
<p>So that’s 22,800 non-thyroid cancers in addition to the approximately 194 million cancer cases that would normally be expected in a population of that size, even in the absence of a Chernobyl accident. The increase from 194,000,000 to 194,022,800 is a 0.01 percent rise in the overall cancer rate. That’s too small to have any measurable impact on the cancer incidence rates for any national cancer registries, so these predicted values will likely remain theoretical.</p>
<h2>Chernobyl’s iodine-131 thyroid effects far worse</h2>
<p>Unfortunately, at Chernobyl, the one type of cancer that could have easily been prevented was not. The population surrounding Chernobyl was not warned that iodine-131 – a radioactive fission product that can enter the food chain – had contaminated milk and other locally produced agricultural products. Consequently, people ate iodine-131-contaminated food, resulting in thyroid cancers.</p>
<p>For the local population, iodine-131 exposure was a worst-case scenario because they were already <a href="http://www.who.int/ionizing_radiation/chernobyl/backgrounder/en/">suffering from an iodine-deficient diet</a>; their <a href="http://www.thyroid.org/iodine-deficiency/">iodine-starved thyroids</a> sucked up any iodine that became available. This extremely unfortunate situation would not have happened in countries such as the United States or Japan, where diets are richer in iodine.</p>
<p>Thyroid cancer is rare, with a low background incidence compared to other cancers. So excess thyroid cancers due to iodine-131 can be more readily spotted in cancer registries. And this, in fact, has been the case for Chernobyl. Beginning five years after the accident, an increase in the rate of thyroid cancers started and continued rising over the following decades. Scientists estimate that there will ultimately be about <a href="http://dx.doi.org/10.1002/ijc.22037">16,000 excess thyroid cancers</a> produced as a result of iodine-131 exposure from Chernobyl.</p>
<p>At Fukushima, in contrast, there was much less iodine-131 exposure. The affected population was smaller, local people were advised to avoid local dairy products due to possible contamination and they did not have iodine-deficient diets.</p>
<p>Consequently, typical radiation doses to the thyroid were low. Iodine-131 uptake into the thyroids of exposed people was measured and the <a href="http://dx.doi.org/10.1038/srep00507">doses were estimated to average</a> just 4.2 mSv for children and 3.5 mSv for adults – levels comparable to annual background radiation doses of approximately 3.0 mSv per year.</p>
<p>Contrast this to Chernobyl, where a significant proportion of the local population received thyroid doses in excess of 200 mSv – 50 times more – well high enough to see appreciable amounts of excess thyroid cancer. So at Fukushima, where iodine-131 doses approached background levels, we wouldn’t expect thyroid cancer to present the problem that it did at Chernobyl. </p>
<p>Nevertheless, there has already been one report that <a href="http://mainichi.jp/english/articles/20160307/p2a/00m/0na/022000c">claims there is an increase</a> in thyroid cancer among Fukushima residents at just four years post-accident. That’s earlier than would be expected based on the <a href="http://dx.doi.org/10.1038/sj.bjc.6601860">Chernobyl experience</a>. And the study’s design has been criticized as flawed for a number of scientific reasons, including the <a href="http://www.sciencemag.org/news/2016/03/mystery-cancers-are-cropping-children-aftermath-fukushima">comparison methods used</a>. Thus, this report of excess thyroid cancers must be considered suspect <a href="http://dx.doi.org/10.1093/jjco/hyv191">until better data arrive</a>.</p>
<h2>Chernobyl has no comparison</h2>
<p>In short, Chernobyl is by far the worst nuclear power plant accident of all time. It was a totally human-made event – <a href="http://pegasusbooks.com/books/atomic-accidents-9781605984926-hardcover">a “safety” test gone terribly awry</a> – made worse by incompetent workers who did all the wrong things when attempting to avert a meltdown.</p>
<p>Fukushima in contrast, was an unfortunate natural disaster – caused by a tsunami that flooded reactor basements – and the workers acted responsibly to mitigate the damage despite loss of electrical power.</p>
<p>April 26, 1986 was the darkest day in the history of nuclear power. Thirty years later, there is no rival that comes even close to Chernobyl in terms of public health consequences; certainly not Fukushima. We must be vigilant to ensure nothing like Chernobyl ever happens again. We don’t want to be “celebrating” any more anniversaries like this one.</p><img src="https://counter.theconversation.com/content/57942/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Timothy J. Jorgensen does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The meltdown at the Chernobyl Nuclear Power Plant in 1986 exposed 572 million people to radiation. No other nuclear accident holds a candle to that level of public health impact.Timothy J. Jorgensen, Director of the Health Physics and Radiation Protection Graduate Program and Associate Professor of Radiation Medicine, Georgetown UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/570302016-04-25T13:49:07Z2016-04-25T13:49:07ZAt Chernobyl and Fukushima, radioactivity has seriously harmed wildlife<figure><img src="https://images.theconversation.com/files/118604/original/image-20160413-25397-867nu9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">White storks on road near Chernobyl, Ukraine. Many parts of the Chernobyl region have low radioactivity levels and serve as refuges for plants and animals.
</span> <span class="attribution"><span class="source">Tim Mousseau</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The largest nuclear disaster in history occurred over 30 years ago at the Chernobyl Nuclear Power Plant in what was then the Soviet Union. The meltdown, explosions and nuclear fire that burned for 10 days injected enormous quantities of radioactivity into the atmosphere and contaminated vast areas of Europe and Eurasia. The International Atomic Energy Agency <a href="http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/28/058/28058918.pdf">estimates</a> that Chernobyl released 400 times more radioactivity into the atmosphere than the bomb dropped on Hiroshima in 1945. </p>
<p>Radioactive cesium from Chernobyl can still be detected in some food products today. And in parts of central, eastern and northern Europe many <a href="http://www.telegraph.co.uk/news/worldnews/europe/germany/11068298/Radioactive-wild-boar-roaming-the-forests-of-Germany.html">animals</a>, plants and mushrooms still contain so much radioactivity that they are unsafe for human consumption. </p>
<p>The first atomic bomb exploded at Alamogordo, New Mexico more than 70 years ago. Since then, more than 2,000 atomic bombs have been tested, <a href="https://www.ctbto.org/nuclear-testing/the-effects-of-nuclear-testing/general-overview-of-theeffects-of-nuclear-testing/">injecting radioactive materials into the atmosphere</a>. And over <a href="http://onlinelibrary.wiley.com/doi/10.1111/risa.12587/full">200 small and large accidents</a> have occurred at nuclear facilities. But experts and advocacy groups are still <a href="http://www.ianfairlie.org/wp-content/uploads/2016/03/chernobyl-report-version-1.1.pdf">fiercely debating</a> the health and environmental consequences of radioactivity.</p>
<p>However, in the past decade population biologists have made considerable progress in documenting how radioactivity affects plants, animals and microbes. <a href="http://cricket.biol.sc.edu/chernobyl/Chernobyl_Research_Initiative/Management_Team.html">My colleagues and I</a> have analyzed these impacts at <a href="http://dx.doi.org/doi:10.1093/jhered/esu040">Chernobyl, Fukushima</a>
and <a href="http://dx.doi.org/10.1111/j.1469-185X.2012.00249.x">naturally radioactive regions</a> of the planet. </p>
<p>Our studies provide new fundamental insights about consequences of chronic, multigenerational exposure to low-dose ionizing radiation. Most importantly, we have found that individual organisms are injured by radiation in a variety of ways. The cumulative effects of these injuries result in lower population sizes and reduced biodiversity in high-radiation areas.</p>
<h2>Broad impacts at Chernobyl</h2>
<p>Radiation exposure has caused <a href="http://dx.doi.org/10.1038/srep08363">genetic damage</a>
and increased mutation rates in many organisms in the Chernobyl region. So far, we have found <a href="http://dx.doi.org/10.1016/j.tree.2016.01.005">little convincing evidence</a> that many organisms there are evolving to become more resistant to radiation. </p>
<p>Organisms’ evolutionary history may play a large role in determining how vulnerable they are to radiation. In our studies, species that have <a href="http://dx.doi.org/10.1111/j.1420-9101.2010.02074.x">historically</a> shown high mutation rates, such as the barn swallow (<em>Hirundo rustica</em>), the icterine warbler (<em>Hippolais icterina</em>) and the Eurasian blackcap (<em>Sylvia atricapilla</em>), are among the most likely to show <a href="http://dx.doi.org/10.1111/j.1420-9101.2010.02074.x">population declines</a> in Chernobyl. Our hypothesis is that species differ in their ability to repair DNA, and this affects both DNA substitution rates and susceptibility to radiation from Chernobyl. </p>
<p>Much like human survivors of the Hiroshima and Nagasaki atomic bombs, <a href="http://dx.doi.org/10.1371/journal.pone.0066939">birds</a> and <a href="http://dx.doi.org/%2010.1038/srep19974">mammals</a>
at Chernobyl have cataracts in their eyes and <a href="http://dx.doi.org/10.1371/journal.pone.0016862">smaller brains</a>. These are direct consequences of exposure to ionizing radiation in air, water and food. Like some cancer patients undergoing radiation therapy, many of the birds have <a href="http://dx.doi.org/10.1098/rsbl.2013.0530">malformed sperm</a>. In the most radioactive areas, up to 40 percent of male birds are <a href="http://dx.doi.org/10.1371/journal.pone.0100296">completely sterile</a>, with no sperm or just a few dead sperm in their reproductive tracts during the breeding season. </p>
<p><a href="http://dx.doi.org/10.1016/j.mrgentox.2013.04.019">Tumors</a>,
presumably cancerous, are obvious on some birds in high-radiation areas. So are developmental abnormalities in some <a href="http://www.bbc.com/news/science-environment-23619870">plants</a> and <a href="http://www.smithsonianmag.com/arts-culture/chernobyls-bugs-art-and-science-life-after-nuclear-fallout-180951231/?no-ist">insects</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/119690/original/image-20160421-27001-ghokic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119690/original/image-20160421-27001-ghokic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=391&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119690/original/image-20160421-27001-ghokic.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=391&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119690/original/image-20160421-27001-ghokic.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=391&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119690/original/image-20160421-27001-ghokic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=491&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119690/original/image-20160421-27001-ghokic.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=491&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119690/original/image-20160421-27001-ghokic.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=491&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Chernobyl reactor No. 4 building, encased in steel and concrete to limit radioactive contamination.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/iaea_imagebank/8134337381/in/photolist-doNB7e-dMnMSs-dMnMVd-9dHxb8-dMhewR-4mzugs-9dHE5k-dMnNuC-4mzt2Y-9dLDow-9dGGdR-9dKY23-4mvmR8-9y1Fzm-dMnNdA-9dGS1Z-9xXHvk-9dL2Ro-dMhejZ-9y1Fjo-dMnNxS-dMnN5E-9dGHPz-dMnN6y-dMheMF-dMnNE9-dMheR2-4mvpW4-9xXKuv-9xXHJt-dMnNfm-9xXM16-9Ae2Vq-9y1Hjb-9xXHXz-9xXJrx-4mvoTn-9y1Jys-9y1Gvf-dMnMTC-9xXNDM-9AdGxs-9xXLfv-dMhekM-dMnNiy-9y1K1y-4mviQz-9xXHSi-9xXJQt-9dKPjW">Vadim Mouchkin, IAEA/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Given overwhelming evidence of genetic damage and injury to individuals, it is not surprising that populations of many organisms in highly contaminated areas have shrunk. In Chernobyl, <a href="http://dx.doi.org/10.1016/j.ecolind.2010.06.013">all major groups of animals</a> that we surveyed were less abundant in more radioactive areas. This includes <a href="http://dx.doi.org/10.1016/j.biocon.2011.08.009">birds</a>, <a href="http://dx.doi.org/10.1098/rsbl.2008.0778">butterflies, dragonflies, bees, grasshoppers, spiders</a> and large and small <a href="http://dx.doi.org/10.1016/j.ecolind.2012.10.025">mammals</a>. </p>
<p>Not every species shows the same pattern of decline. Many species, including wolves, show no effects of radiation on their population density. A few species of birds appear to be more abundant in more radioactive areas. In both cases, higher numbers may reflect the fact that there are fewer competitors or predators for these species in highly radioactive areas. </p>
<p>Moreover, vast areas of the Chernobyl Exclusion Zone are not presently heavily contaminated, and appear to provide a refuge for many species. <a href="http://dx.doi.org/10.1016/j.cub.2015.08.017">One report published in 2015</a> described game animals such as wild boar and elk as thriving in the Chernobyl ecosystem. But nearly all documented consequences of radiation in Chernobyl and Fukushima have found that individual organisms exposed to radiation <a href="http://dx.doi.org/10.1093/jhered/esu040">suffer serious harm</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/119333/original/image-20160419-13901-1xt15gz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119333/original/image-20160419-13901-1xt15gz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119333/original/image-20160419-13901-1xt15gz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119333/original/image-20160419-13901-1xt15gz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119333/original/image-20160419-13901-1xt15gz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=519&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119333/original/image-20160419-13901-1xt15gz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=519&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119333/original/image-20160419-13901-1xt15gz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=519&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Map of the Chernobyl region of Ukraine. Note the highly heterogeneous deposition patterns of radioactivity in the region. Areas of low radioactivity provide refuges for wildlife in the region.</span>
<span class="attribution"><span class="source">Shestopalov, V.M., 1996. Atlas of Chernobyl exclusion zone. Kiev: Ukrainian Academy of Science.</span></span>
</figcaption>
</figure>
<p>There may be exceptions. For example, substances called antioxidants can defend against the damage to DNA, proteins and lipids caused by ionizing radiation. The <a href="http://dx.doi.org/10.1016/j.scitotenv.2016.01.027">levels of antioxidants</a> that individuals have available in their bodies may play an important role in reducing the damage caused by radiation. There is evidence that <a href="http://dx.doi.org/10.1111/1365-2435.12283">some birds</a> may have adapted to radiation by changing the way they use antioxidants in their bodies. </p>
<h2>Parallels at Fukushima</h2>
<p>We tested the validity of our Chernobyl studies by repeating them in Fukushima, Japan. The 2011 power loss and core meltdown at three nuclear reactors there released <a href="http://dx.doi.org/10.1093/jrr/rrv074">about one-tenth as much radioactive material</a> as the Chernobyl disaster.</p>
<p>Overall, we have found similar patterns of declines in abundance and <a href="http://dx.doi.org/10.1007/s10336-015-1197-2">diversity</a> of birds, although <a href="http://dx.doi.org/10.1007/s10336-015-1173-x">some species</a> are more sensitive to radiation than others. We have also found declines in some insects, such as <a href="http://dx.doi.org/10.1016/j.ecolind.2012.06.001">butterflies</a>, which may reflect the accumulation of <a href="http://dx.doi.org/10.1093/jhered/esu013">harmful mutations</a> over multiple generations. </p>
<p>Our studies at Fukushima have benefited from more sophisticated analyses of <a href="http://dx.doi.org/10.1038/srep16594">radiation doses</a> received by animals. In one paper, we teamed up with radioecologists to reconstruct the doses received by about 7,000 birds. The parallels we have found between Chernobyl and Fukushima provide strong evidence that radiation is the underlying cause of the effects we have observed in both locations.</p>
<p>Some members of the radiation regulatory community have been slow to acknowledge how nuclear accidents have harmed wildlife. For example, the U.N.-sponsored Chernobyl Forum instigated the notion that the accident has had a <a href="https://www.iaea.org/sites/default/files/chernobyl.pdf">positive impact on living organisms</a> in the exclusion zone because of the lack of human activities. A <a href="http://www.unscear.org/docs/reports/2013/13-85418_Report_2013_Annex_A.pdf">2013 report</a> of the United Nations Scientific Committee on the Effects of Atomic Radiation predicts minimal consequences for the biota animal and plant life of the Fukushima region. </p>
<p>Unfortunately these official assessments were largely based on predictions from theoretical models, not on direct empirical observations of the plants and animals living in these regions. Based on our research, and that of others, it is now known that animals living under the full range of stresses in nature are <a href="http://dx.doi.org/10.1016/j.jenvrad.2012.01.013">far more sensitive</a> to the effects of radiation than previously believed. Although field studies sometimes lack the controlled settings needed for precise scientific experimentation, they make up for this with a more realistic description of natural processes.</p>
<p>Our emphasis on documenting radiation effects under “natural” conditions using wild organisms has provided many discoveries that will help us to prepare for the <a href="http://dx.doi.org/10.1016/j.erss.2015.12.026">next nuclear accident</a> or act of <a href="http://www.nuclearterror.org/index.html">nuclear terrorism</a>. This information is absolutely needed if we are to protect the environment not just for man, but also for the living organisms and ecosystem services that sustain all life on this planet. </p>
<p>There are currently more than 400 nuclear reactors in operation around the world, with 65 new ones under construction and another 165 on order or planned. All operating nuclear power plants are generating large quantities of nuclear waste that will need to be stored for thousands of years to come. Given this, and the probability of future accidents or nuclear terrorism, it is important that scientists learn as much as possible about the effects of these contaminants in the environment, both for remediation of the effects of future incidents and for evidenced-based risk assessment and energy policy development.</p><img src="https://counter.theconversation.com/content/57030/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Timothy A. Mousseau receives funding from the Samuel Freeman Charitable Trust. Previous funding includes: The National Science Foundation, the National Geographic Society, the National Institutes of Health. </span></em></p>How do we measure long-term impacts of nuclear accidents? Studies at Chernobyl and Fukushima show that radiation has harmed animals, birds and insects and reduced biodiversity at both sites.Timothy A. Mousseau, Professor of Biological Sciences, University of South CarolinaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/535142016-01-21T11:50:23Z2016-01-21T11:50:23ZLitvinenko poisoning: polonium explained<figure><img src="https://images.theconversation.com/files/108864/original/image-20160121-9754-u1yg2t.jpg?ixlib=rb-1.1.0&rect=53%2C0%2C951%2C640&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Polonium is found naturally in uranium ore</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/radioactiverosca/6862869951/in/photolist-bss18Z-74EqwM-7X1Ctf-2vVkpu-8cojGg-BRguip-BNXQpL-BhKABH-ankEnr-8crVfL-8cs5CU-ano7ky-atboEb-ati1uT-atboq5-at8LCr-atbpaN-6A9vPB-6vprqz-47snbL-7Xfo1h-dwnaWo-8gK8FW-8JA7k7-DqF9E-qpkBr9-bx8d9i-bXbo54-ankp9t-Bgbxok-atkxnq-atkwqy-qrBHpr-athPhc-atkrt3-atkua3-athLq4-atkBHs-atbpVs-cuhvHf-ceMcPq-atbpHy-at8M7n-atbqn9-DqFnW-DqFjp-DqFfd-DqF4Z-DqF6C-DqF3K">Rui Costa/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>The murder of former Russian spy Alexander Litvinenko was one of the most high-profile assassinations of the decade. It particularly captured the public imagination because Litvinenko was <a href="http://www.telegraph.co.uk/news/uknews/law-and-order/11371940/Alexander-Litvinenko-was-poisoned-twice-with-polonium-210-inquiry-hears.html">killed using polonium-210</a>, a rare but deadly substance that was thought to have been slipped into Litvinenko’s tea. Now a UK public inquiry has <a href="http://www.theguardian.com/world/2016/jan/21/alexander-litvinenko-was-probably-murdered-on-personal-orders-of-putin">issued its findings</a> on the case. But what is polonium?</p>
<h2>Rare and radioactive</h2>
<p>Polonium is a radioactive element that occurs naturally in tiny amounts (which are harmless to us). It was <a href="http://www.nobelprize.org/nobel_prizes/themes/physics/curie/">discovered in 1898</a> by Marie Curie, during her research on pitchblende, an ore of uranium. It has the chemical symbol “Po” and Curie named it after Poland, her native country. If you look at a periodic table, you’ll find polonium at the bottom of the group headed by oxygen and sulfur.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/108865/original/image-20160121-9754-1h72kx6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/108865/original/image-20160121-9754-1h72kx6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=763&fit=crop&dpr=1 600w, https://images.theconversation.com/files/108865/original/image-20160121-9754-1h72kx6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=763&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/108865/original/image-20160121-9754-1h72kx6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=763&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/108865/original/image-20160121-9754-1h72kx6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=959&fit=crop&dpr=1 754w, https://images.theconversation.com/files/108865/original/image-20160121-9754-1h72kx6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=959&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/108865/original/image-20160121-9754-1h72kx6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=959&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Marie Curie.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/Category:Marie_Curie#/media/File:Marie_Curie_(Nobel-Chem).jpg">Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>There are around 30 different isotopes of polonium ranging in atomic mass from 194 to 218, only differing from each other in their neutron number. The important one is polonium-210, which happens to be the one discovered by Curie.</p>
<p>Uranium atoms slowly decay into other atoms, eventually ending up as lead but with polonium as one stop on the way. Because of this radioactive decay, polonium atoms are continually being formed and decomposed so the element does not naturally accumulate in any significant amount.</p>
<p>Although polonium-210 was first isolated from uranium ores, today it can be artificially made by bombarding atoms of the metal bismuth with neutrons. According to <a href="http://www.theguardian.com/world/2015/mar/11/substance-used-to-poison-litvinenko-could-only-have-come-from-russia-inquiry">an expert who testified</a> to the Litvinenko enquiry, only one place in the world had a polonium “production line” – a closed nuclear facility in Sarov, just under 500 miles south-east of Moscow – and the sample used in the murder was highly likely to have come from here.</p>
<h2>Highly toxic</h2>
<p>Polonium is one of the <a href="http://www.medicalnewstoday.com/articles/58088.php">most toxic substances</a> known. According to some sources, it is up to a <a href="https://books.google.co.uk/books?id=j-Xu07p3cKwC&pg=PA332&lpg=PA332&dq=polonium+trillion+times+toxic&source=bl&ots=luQYfE41Kl&sig=fXHD19Rt_O9qaHFJA4-XZn8s0A0&hl=en&sa=X&ved=0ahUKEwj38v3M1LrKAhUBnBQKHQPpA-8Q6AEIIzAB#v=onepage&q=polonium%20trillion%20times%20toxictrillion&f=false">trillion times</a> more toxic than hydrogen cyanide. It is radioactive because it emits alpha particles (helium ions). Because these are easily absorbed by other materials, even by a few thin sheets of paper or by a few centimetres of air, polonium has to be inside your body to damage you.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/108867/original/image-20160121-9766-bc4z6r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/108867/original/image-20160121-9766-bc4z6r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/108867/original/image-20160121-9766-bc4z6r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/108867/original/image-20160121-9766-bc4z6r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/108867/original/image-20160121-9766-bc4z6r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/108867/original/image-20160121-9766-bc4z6r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/108867/original/image-20160121-9766-bc4z6r.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">Polonium can be produced from bismuth.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/play4smee/3605159933/in/photolist-hotYTE-uoAsXs-vk8xa-uKWEd-fyjRFb-fyjRCq-fyjRyq-fyjRuu-zLpkH-zoEx8-tYALv-eiWpPC-eiWpN3-eiWpMY-eiQFrX-eiQFrR-ek23do-ek23cd-z7vCj-cqUg2f-Cz27p-9fC6DH-7HSSUu-5cViiR-47thP5-9iDk6f-kydBF6-ceLMJ5-ejVZ3z-4dD29X-ceLMYQ-ceLM1b-hucaBo-6uDAoL-6uzorT-6uDAa3-hUDyjb-fFd2P7-7vZHsp-fFdLHb-dbrK4B-rym5wk-fFdMAy-fEVrr2-4vPx1v-fFd1aG-8JPat2-bmMReq-xZdQj-zmkuJa">play4smee/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>It’s this radiation that has made minuscule traces of polonium useful in anti-static brushes, which are used to remove static charge from sensitive equipment. The fact that its alpha particles are so easily absorbed also make it hard to detect by radiation detectors such as Geiger counters, so polonium is probably easier to smuggle than some other lethal agents.</p>
<p>If polonium is known to have entered the body very recently, there is a <a href="http://www.tandfonline.com/doi/abs/10.1080/15563650902956431?journalCode=ictx20&">chance of removing it</a> by gastric aspiration (sucking out the stomach contents) or lavage (washing the stomach out with water). Chelating chemical agents, the sort that are used to treat heavy metal poisoning, can also remove polonium from the body if administered very quickly. But once it gets into the blood, it is likely to cause acute radiation syndrome and you will die of <a href="http://www.news-medical.net/news/2007/03/06/22431.aspx">multiple organ failure</a>.</p>
<h2>Effect on the body</h2>
<p>The alpha radiation breaks apart the chemical bonds in living cells, damages DNA and creates lots of very reactive free radical ions that can do further damage. <a href="http://iopscience.iop.org/article/10.1088/0952-4746/27/1/001/pdf">One specific result</a> is a reduction in your white blood cell count which, apart from anything else, can make you more susceptible to infection and requires blood and platelet transfusions.</p>
<p>The liver, kidneys, spleen and bone marrow are particular targets and are massively damaged by the alpha-radiation. The rapid damage to the gastrointestinal tract causes nausea and vomiting. Bone marrow failure can result in days. One other target is hair follicles, which is why Litvinenko lost his hair <a href="https://www.clintox.org/documents/WMDSIG/AACT-WMD-Death_Polonium.pdf">before he died</a>. </p>
<p>Alexander Litvinenko is not the first casualty of polonium. In 1956, Marie Curie’s scientist daughter <a href="http://www.rsc.org/diversity/175-faces/all-faces/irene-joliot-curie">Irène Joliot-Curie</a> died of leukaemia that she is believed to have contracted through exposure to polonium years before. There <a href="https://theconversation.com/what-we-could-learn-from-yasser-arafats-exhumation-11030">have also been claims</a> that Palestinian leader Yasser Arafat may have been exposed to it in a similar way to which Litvinenko was.</p><img src="https://counter.theconversation.com/content/53514/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon Cotton 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>Polonium’s chemical properties made it the ideal secret weapon for the assassins of Alexander Litvinenko.Simon Cotton, Senior Lecturer in Chemistry, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/486002015-10-05T16:59:33Z2015-10-05T16:59:33ZWolves, boar and other wildlife defy contamination to make a comeback at Chernobyl<figure><img src="https://images.theconversation.com/files/97256/original/image-20151005-28783-1uicy6k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Valeriy Yurko</span></span></figcaption></figure><p>The <a href="http://www.world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Chernobyl-Accident/">accident at the Chernobyl Nuclear Power Plant</a> in 1986 had a devastating impact on the local population and forced 116,000 people to permanently leave their homes. But now researchers have discovered that, while the people may not have returned, the contaminated area of Belarus <a href="http://dx.doi.org/10.1016/j.cub.2015.08.017">is teeming with wild animals</a>, including elk, wild boar, deer and wolves. Perhaps surprisingly, many of these numbers seem to be on the rise and some of them are higher than in uncontaminated areas.</p>
<p>The abandoned area around the nuclear power plant, known as the Chernobyl exclusion zone, includes about 4750 square kilometres of land in both Ukraine and Belarus. The <a href="https://wiki.ceh.ac.uk/download/attachments/212762954/points%20Cs137%20new.jpg?api=v2">contamination in the exclusion zone is patchy</a>, as the distribution of <a href="https://theconversation.com/explainer-the-difference-between-radiation-and-radioactivity-20014">radioactive isotopes</a> on the ground was influenced by the weather conditions at the time of the accident and the days following it. The radiation levels have reduced over the nearly 30 years since the accident, but in many parts of the zone they are too high for people to return. </p>
<p>The accident offered a unique opportunity to study the impacts on wildlife in the area – but hitherto researchers have failed to fully exploit it. The new study is important, as it is to our knowledge the first paper published in an international scientific journal on long-term changes in the population of mammals in the exclusion zone.</p>
<h2>Shedding light on a confusing debate</h2>
<p>Given the lack of rigorous studies, the debate about wildlife at the site has so far been divergent. This is true both of the <a href="http://onlinelibrary.wiley.com/doi/10.1002/ieam.238/pdf">scientific literature</a> and the mainstream media, with articles such as <a href="http://news.bbc.co.uk/1/hi/world/europe/4923342.stm">“Wildlife defies Chernobyl radiation”</a> and <a href="http://news.bbc.co.uk/1/hi/sci/tech/6946210.stm">“Chernobyl ‘not a wildlife haven’”</a> published shortly after one another.</p>
<p>Some of the research on the effect of radiation on wildlife populations, such as a study investigating <a href="http://rsbl.royalsocietypublishing.org/content/5/3/356">insects and spiders</a>, has reported significant, negative effects at relatively low levels – comparable with <a href="http://www.sciencedirect.com/science/article/pii/S0265931X08000489">natural background dose rates</a> in many countries. If these findings are correct, they have significant implications for the current radiation protection system for both humans and the environment. </p>
<p>However, very few of the studies conducted in the exclusion zone have considered medium or large mammal species. So even though <a href="http://www-pub.iaea.org/mtcd/publications/pdf/pub1239_web.pdf">some evaluations</a> in the past have suggested that the area has become a wildlife sanctuary, such observations have, rightly, been criticised as <a href="rsbl.royalsocietypublishing.org/content/4/1/65">being largely anecdotal</a>.</p>
<p>The new study in Belarus used two methods to estimate the number of animals: helicopter surveys conducted in the winter months between 1987 and 1996 when animals were counted directly, and ground surveys to record tracks of mammals in snow in the winter months of 2008-2010. The results were compared to data from similar studies conducted in a number of uncontaminated nature reserves in Belarus. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/97298/original/image-20151005-28744-58zu3n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/97298/original/image-20151005-28744-58zu3n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/97298/original/image-20151005-28744-58zu3n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/97298/original/image-20151005-28744-58zu3n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/97298/original/image-20151005-28744-58zu3n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/97298/original/image-20151005-28744-58zu3n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/97298/original/image-20151005-28744-58zu3n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Elk populations are increasing in Chernobyl.</span>
<span class="attribution"><span class="source">http://www.ceh.ac.uk/tree</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The team found that the number of elk, roe deer, red deer and wild boar within the Belarussian part of the exclusion zone are similar to those in four uncontaminated nature reserves. Of these, the number of elk and roe deer has increased consistently since 1987, with roe deer numbers increasing by about 10 times by 1996. The wild boar population dropped in 1993-94 but this was traced to a disease outbreak. They also found that the density of wolves is more than seven times higher in the zone than in other comparable areas, which is likely to be, at least in part, down to the fact that nobody is hunting them. </p>
<p>The researchers also looked at how many animals there were for different levels of radiation and found no relationship between ground contamination density (contamination in the exclusion zone has been relatively well mapped) and animal population.</p>
<p>The results contradict a previous study, also based on tracks in snow, which estimated that the number of animals <a href="http://www.bbc.co.uk/news/science-environment-10819027">is decreasing</a> in the area. However, this study failed to appropriately estimate the doses the animals received. The actual dose an animal receives depends not only on the amount of external radiation they receive, but also on the amount of radioactive material that the animals ingest by eating and drinking in the area. The new study has attempted to make more accurate assessments of radiation exposure.</p>
<h2>Is Chernobyl safe?</h2>
<p>While the study has shed much-needed light on wildlife in the area, further research is needed to verify the result and help us understand why this effect is seen. </p>
<p>For example, the finding goes against what may be expected to be seen: that ionising radiation is hazardous to living organisms. The results may even be taken to imply that raised radiation levels may have a beneficial effect on wildlife. However, it is important to keep in mind that as humans have left the zone, there is no agriculture, forestry or hunting to threaten wildlife. So radiation is most likely not good for animals, but removing humans definitely is. </p>
<p>There are likely to be negative effects of radiation in the exclusion zone. But currently we cannot clearly see this over the effects of humans leaving the area. For instance, the health or lifespan of the animals maybe affected and research is required to evaluate this. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/97254/original/image-20151005-28783-y7prf3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/97254/original/image-20151005-28783-y7prf3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/97254/original/image-20151005-28783-y7prf3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/97254/original/image-20151005-28783-y7prf3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/97254/original/image-20151005-28783-y7prf3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/97254/original/image-20151005-28783-y7prf3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/97254/original/image-20151005-28783-y7prf3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Chernobyl wolves caught on our camera.</span>
<span class="attribution"><span class="source">http://www.ceh.ac.uk/tree</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Advances in photographic and acoustic recording techniques means we are now able to estimate the number of animals by observing them directly rather than looking at their tracks. We have embarked on a <a href="http://www.bbc.co.uk/news/science-environment-32452085">project using motion-activated cameras</a> and sound recorders to investigate wildlife in different areas of the exclusion zone. Hopefully, this will provide more definitive conclusions on the relationship between dose rate and animal abundance. </p>
<p>Although our study continues, initial indications are that the apparent abundance of wildlife changes during the year, as do the species observed. Consequently, we could expect slightly different results from our five-year long research study to those found by others who have only surveyed in winter.</p>
<p>Nevertheless, the <a href="http://dx.doi.org/10.1016/j.cub.2015.08.017">study just reported</a> is currently the best evaluation we have. It is important, as it could help us understand the potential long-term environmental impact of the <a href="https://theconversation.com/is-fukushima-the-new-normal-for-nuclear-reactors-17391">2011 accident</a> at the Fukushima nuclear power plant in Japan. But perhaps the biggest lesson we can learn from the Chernobyl accident with respect to Fukushima is to ensure that rigorous and co-ordinated research programmes are conducted in Japan to help understand the effects of radiation on the natural environment.</p><img src="https://counter.theconversation.com/content/48600/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span> </span></em></p><p class="fine-print"><em><span>Nick Beresford and Mike Wood are funded through the NERC TREE project (<a href="http://www.ceh.ac.uk/TREE">www.ceh.ac.uk/TREE</a>), which has also funded some of the co-authors of the paper published by Deryabina and colleagues in Current Biology. However, Nick Beresford and Mike Wood had no prior knowledge of the Deryabina study.</span></em></p>Elk, deer and wolves are becoming increasingly common in Chernobyl.Mike Wood, Senior Lecturer in Environmental Management, University of SalfordNick Beresford, Radioecologist, UK Centre for Ecology & HydrologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/455642015-08-10T10:12:24Z2015-08-10T10:12:24ZWhat if it happened again? What we need to do to prepare for a nuclear event<figure><img src="https://images.theconversation.com/files/91077/original/image-20150806-5256-cbdnk1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Atomic cloud over Hiroshima.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Atomic_cloud_over_Hiroshima_(from_Matsuyama).jpg">By 509th Operations Group via Wikimedia Commons</a></span></figcaption></figure><p>Almost two years on from the 70th anniversary of the bombings of Hiroshima and Nagasaki, it might seem like the threat from nuclear weapons has receded. But it hasn’t; the threat is actually increasing steadily. This is difficult to face for many people, and this denial also means that we are not very well-prepared for nuclear and radiological events.</p>
<p>I’ve been studying the effects of nuclear events – from detonations to accidents – for over 30 years. I’ve been involved in research, teaching and humanitarian efforts in multiple expeditions to Chernobyl- and Fukushima-contaminated areas. Now I am involved in the proposal for the formation of the Nuclear Global Health Workforce.</p>
<p>Such a group could bring together nuclear and non-nuclear technical and health professionals for education and training, and help to meet the preparedness, coordination, collaboration and staffing requirements necessary to respond to a large-scale nuclear crisis.</p>
<p>Any nuclear weapon exchange or major nuclear plant meltdown will immediately lead to a global public health emergency. The Ebola outbreak taught the world that we should have resources in place to handle a major health emergency before it happens. </p>
<p>What would a Nuclear Global Health Workforce need to be prepared to manage? For that we can look back at the legacy of the atomic bombings of Hiroshima and Nagasaki, as well as the nuclear accidents like Chernobyl and Fukushima.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/91076/original/image-20150806-5263-pc5aav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91076/original/image-20150806-5263-pc5aav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91076/original/image-20150806-5263-pc5aav.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91076/original/image-20150806-5263-pc5aav.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91076/original/image-20150806-5263-pc5aav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91076/original/image-20150806-5263-pc5aav.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91076/original/image-20150806-5263-pc5aav.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=492&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Hiroshima Prefecture Industrial Promotion Hall after the blast.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/65847118@N06/6018958296/">Maarten Heerlien/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>What happens when a nuclear device is detonated over a city?</h2>
<p>Approximately 135,000 and 64,000 people died, respectively, in Hiroshima and Nagasaki. The <a href="http://www.atomicarchive.com/Docs/MED/med_chp10.shtml">great majority</a> of deaths happened in the first days after the bombings, mainly from thermal burns, severe physical injuries and radiation. </p>
<p>Over 90% of the doctors in nurses in Hiroshima were killed and injured, and therefore unable to assist in the response. This was largely due to the concentration of medical personnel and facilities in inner urban areas. This exact concentration exists today in the majority of American cities, and is a chilling reminder of the difficulty in <a href="http://dx.doi.org/10.1017/dmp.2013.103">medically responding</a> to nuclear events. </p>
<p>What if a nuclear device were detonated in an urban area today? I explored this issue in a 2007 study modeling a nuclear weapon attack on <a href="http://dx.doi.org/10.1186/1476-072X-6-5">four American cities</a>. As in Hiroshima and Nagasaki, the majority of deaths would happen soon after the detonation, and the local health care response capability would be largely eradicated. </p>
<p>Models <a href="http://dx.doi.org/10.1097/DMP.0b013e318159a9e3">show</a> that such an event in an urban area in particular will not only destroy the existing public health protections but will, most likely, make it <a href="http://www.ncbi.nlm.nih.gov/books/NBK215195/?report=reader">extremely difficult</a> to respond, recover and rehabilitate them. </p>
<p>With medical facilities decimated after a detonation, treating the injured will be a tremendous challenge. We would need predicted casualty distributions and locations to figure out how to best allocate what resources and personnel remain. </p>
<p>Very few medical personnel today have the skills or knowledge to treat the kind and the quantity of injuries a nuclear blast can cause. Health care workers would have little to no familiarity with the treatment of radiation victims. Thermal burns would require enormous resources to treat even a single patient, and a large number of patients with these injuries will overwhelm any existing medical system. There would also be a massive number of laceration injuries from the breakage of virtually all glass in a wide area. </p>
<p>Currently, it has not been worked out how medical systems in affected areas are supposed to cope with the overwhelming numbers of patients from an urban nuclear detonation. This makes it that much more important to have an effort like the Nuclear Global Health Workforce to work to address and help nations prepare for these overwhelming events.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/91080/original/image-20150806-5268-1pwsmh4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91080/original/image-20150806-5268-1pwsmh4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=481&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91080/original/image-20150806-5268-1pwsmh4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=481&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91080/original/image-20150806-5268-1pwsmh4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=481&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91080/original/image-20150806-5268-1pwsmh4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=604&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91080/original/image-20150806-5268-1pwsmh4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=604&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91080/original/image-20150806-5268-1pwsmh4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=604&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Officials in protective gear check for signs of radiation on children who are from the evacuation area near the Fukushima Daini nuclear plant in Koriyama in this March 13 2011 photo.</span>
<span class="attribution"><span class="source">Reuters/Kim Kyung-Hoon/Files</span></span>
</figcaption>
</figure>
<h2>Getting people out of the blast and radiation contamination zones</h2>
<p>A major nuclear event would leave large swaths of territory uninhabitable for decades, with catastrophic impacts on humans, the economy and the environment. </p>
<p>Decisions to evacuate at-risk populations must be made within hours, but plans for and criteria to evacuate are lacking. And the scale of these evacuations and potential resettlement is tremendous.</p>
<p>For instance, within a few weeks after the Chernobyl accident, more than <a href="http://www.world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Appendices/Chernobyl-Accident---Appendix-2--Health-Impacts/">116,000 people were evacuated</a> from the most contaminated areas of Ukraine and Belarus. Another 220,000 people were relocated in subsequent years. But thousands continue to live in areas classified by Ukrainian and Belarussian authorities as strictly controlled zones, where chronic radioactive cesium contamination remains a problem. </p>
<p>The day after the Fukushima earthquake and tsunami, over <a href="http://www.washingtonpost.com/wp-dyn/content/article/2011/03/11/AR2011031103673.html">200,000 people were evacuated</a> from <a href="http://fukushimaontheglobe.com/the-earthquake-and-the-nuclear-accident/evacuation-orders-and-restricted-areas">areas within 20 kilometers (12 miles) the nuclear plant</a> because of the fear of the potential for radiation exposure.</p>
<p>On Day 3, people living in the 20-30 kilometer (12-18 mile) zone around the plant were asked <a href="http://www.iddri.org/Publications/Collections/Analyses/STUDY0513_RH_DEVAST%20report.pdf">to remain indoors</a>, and eventually advised to self-evacuate. </p>
<p>The evacuation process was plagued by misinformation, inadequate and confusing orders and delays in releasing information. There was also trouble evacuating everyone from the affected areas. Elderly and infirm residents were left in areas near the plant, and hospitalized patients were not always taken where they needed to go. All of these troubles lead to a loss of public trust in the government. </p>
<p>Chernobyl and Fukushima were both reactor meltdowns. A high-yield nuclear weapon – that is, a large device with a very large blast and radiation capability – would bring patient and evacuation numbers to incomprehensible levels. </p>
<p>However, the current Department of Homeland Security most-anticipated scenario for a nuclear attack in the US is for smaller nuclear weapons – 10 kilotons – about the size of the weapons used to attack Hiroshima and Nagasaki.</p>
<p>And new evidence has altered previous dire predictions in relatively low-yield nuclear blasts such as Hiroshima and Nagasaki. Current US nuclear war response protocols do not rely as much on large-scale evacuations from nearby areas. </p>
<p>For instance, in a <a href="http://www.epa.gov/radiation/docs/er/planning-guidance-for-response-to-nuclear-detonation-2-edition-final.pdf">hypothetical low-yield (10 kiloton) nuclear bomb</a> over Washington DC, only limited evacuations are planned. Despite projections of <a href="http://www.washingtonpost.com/wp-dyn/content/article/2008/04/15/AR2008041502969.html">100,000 fatalities</a> and about 150,000 casualties, the casualty-producing radiation plume would actually be expected to be confined to a relatively small area. People upwind would not need to take any action, and most of those downwind, in areas receiving relatively small radiation levels (from the point of view of being sufficient to cause radiation-related health issues), would need to seek only “moderate shelter.”</p>
<p>A Nuclear Global Health Workforce could start to lay out plans for how to rapidly respond to such an attack and project whether and what sort of evacuation plans would be needed. </p>
<h2>The long-term effects of radiation exposure</h2>
<p>The Radiation Effects Research Foundation (RERF), which was established to study the effects of radiation on survivors of the Hiroshima and Nagasaki, has been tracking the health effects of radiation for decades. </p>
<p>According to RERF, about <a href="http://www.rerf.jp/general/qa_e/qa2.html">1,900 excess cancer deaths</a> can be attributed to the atomic bombs, with about 200 cases of leukemia and 1,700 solid cancers. Japan has constructed very detailed cancer screenings after Hiroshima, Nagasaki and Fukushima; Chernobyl research has also been extensive, but not to the extent as in ongoing in Japan. </p>
<p>But the data on many potential health effects from radiation exposure, such as birth defects, arere less conclusive. </p>
<p>While it has been shown that intense medical X-ray exposure has accidentally produced birth defects in humans, there is considerable debate about whether there were <a href="http://www.rerf.jp/radefx/genetics_e/birthdef.html">birth defects</a> in the descendants of Hiroshima and Nagasaki atomic bomb survivors. </p>
<p>For example, one study found more than a doubling of brain malformations in some children from Hiroshima and Nagasaki, while other respected long-term investigations have concluded there are no statistically significant increases in birth defects resulting in atomic bomb survivors. </p>
<p>Looking at data from Chernobyl, where the release of airborne radiation was 100 times as much as Hiroshima and Nagasaki combined, there is a similar lack of definitive data for radiation-induced birth defects.</p>
<p>A wide-ranging <a href="http://www.epa.gov/radiation/docs/er/planning-guidance-for-response-to-nuclear-detonation-2-edition-final.pdf">WHO study</a> concluded that there were no differences in rates of mental retardation and emotional problems in Chernobyl radiation-exposed children compared to children in control groups. </p>
<p>A <a href="http://onlinelibrary.wiley.com/doi/10.1111/1469-7610.00613/abstract">Harvard review</a> on Chernobyl concluded that there was no substantive proof regarding radiation-induced effects on embryos or fetuses from the accident. Another <a href="http://aje.oxfordjournals.org/content/160/5/453.full">study looked at the congenital abnormality registers</a> for 16 European regions that received fallout from Chernobyl, and concluded that the widespread fear in the population about the possible effects of radiation exposure on the unborn fetus was not justified. </p>
<p>Indeed, the <a href="http://dx.doi.org/10.1001/dmp.2012.72">most definitive Chernobyl health impact</a> in terms of numbers was the dramatic increase of elective abortions near and at significant distances from the accident site. This was due to “nuclear phobia,”, lack of information and inadequate official guidance. Not having been informed about the actual lack of risk, there was understandable anxiety regarding the possible effects of radiation on the fetus, and a panic among expectant mothers about giving birth to a child with a birth defect. </p>
<p>A Nuclear Global Health Workforce could help health care practitioners, policymakers, administrators and others understand myths and realities of radiation. In the critical time just after a nuclear crisis, this would help officials make evidence-based policy decisions and help people understand the actual risks they face.</p>
<h2>What’s the risk of another Hiroshima or Nagasaki?</h2>
<p>Today, the risk for a nuclear exchange – and its devastating impact on medicine and public health worldwide – has only escalated. Nuclear weapons are spreading to more nations, and international relations are increasingly volatile. The developing technological sophistication among terrorist groups and the growing global availability and distribution of radioactive materials are also especially worrying. </p>
<p>Despite the gloomy prospects of health outcomes of any large scale nuclear event common in the minds of many, it is our mutually shared moral and ethical obligation to respond.</p><img src="https://counter.theconversation.com/content/45564/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cham Dallas has received U.S. federal funding for emergency response research and training from the Assistant Secretary for Preparedness and Response and the USDA, the Georgia State Department of Public Health, and the Georgia Emergency Management Agency.
Cham Dallas has worked with U.S. legislators, including U.S. Senators Max Cleland (D, Georgia), Joseph Liebermann (D, Connecticut), and Sam Nunn (D, Georgia), and U.S. Congressmen Paul Broun (R, Georgia) and Jody Hice (R, Georgia), </span></em></p>Any nuclear weapon exchange or major nuclear plant meltdown will immediately lead to a global public health emergency. What can we learn from past events to help prepare?Cham Dallas, Professor and Director, Institute for Disaster Management, University of GeorgiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/410692015-07-16T10:15:41Z2015-07-16T10:15:41ZRadiation in the postwar American mind: from wonder to worry<figure><img src="https://images.theconversation.com/files/88423/original/image-20150714-21719-9oc0uv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Blowing up the desert – and people's minds: the first atom bomb test in 1945. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/ctbto/4926598556/">US Government</a></span></figcaption></figure><p>More than seventy five years ago at a remote site in New Mexico, the first test of a nuclear bomb was detonated, producing a <a href="http://www.pbs.org/wgbh/americanexperience/features/primary-resources/truman-bombtest/">massive explosion</a>. The test, which presaged the atomic bombs dropped on Nagasaki and Hiroshima, Japan in August 1945, forever changed the course of world affairs. Subsequent nuclear explosions, and the radioactive fallout they produced, quickly gave rise to worries over the dangers of radiation.</p>
<p>But what does “radiation” mean? And how have attitudes toward radiation changed over time? </p>
<p>The <a href="https://orise.orau.gov/reacts/guide/define.htm">technical definition</a> aside, for most Americans today, it means something like this: energies, often man-made, usually undetectable, that have <a href="http://press.uchicago.edu/ucp/books/book/chicago/R/bo19804483.html">strange effects</a> on living things. We connect the abstract, physical concept with a personal, biological one. We take special notice when we are exposed to those energies, even briefly. </p>
<h2>The early days: a glowing reception</h2>
<p>In that sense, the age of radiation began in 1895 with the discovery of X-rays. In the <a href="http://www.palgrave.com/page/detail/the-first-atomic-age-matthew-lavine/?K=9781137307217">half-century that followed</a>, Americans indulged in <a href="http://www.neatorama.com/2013/11/18/The-Strange-Fate-of-Eben-Byers/">optimistic fantasies</a> about the miracles these energies could perform for better health. But they also quickly learned to <a href="http://www.smithsonianmag.com/ist/?next=/history/clarence-dally-the-man-who-gave-thomas-edison-x-ray-vision-123713565/">fear</a> them. On balance, the anxieties have had greater staying power. </p>
<p>Such reactions came from the many direct, personal experiences Americans had with irradiation in an era when radium and X-ray machines were icons of scientific modernity in the early 20th century. They were hailed as the wonders of the age, presented simultaneously as poisons and cure-alls, perpetual motion machines and planet-busting explosives. Radioactive substances (or plausible fakes thereof) were added to dozens of <a href="http://io9.com/seriously-scary-radioactive-consumer-products-from-the-498044380">everyday consumer products</a>, including toothpaste and lipstick, to enhance them with the mysterious energies of the atom. X-rays were tools of portraiture at the <a href="http://www.uh.edu/engines/epi1494.htm">beauty salon</a> (for hair removal) as well as the hospital. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/88424/original/image-20150714-21701-1kb30w1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/88424/original/image-20150714-21701-1kb30w1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/88424/original/image-20150714-21701-1kb30w1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=601&fit=crop&dpr=1 600w, https://images.theconversation.com/files/88424/original/image-20150714-21701-1kb30w1.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=601&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/88424/original/image-20150714-21701-1kb30w1.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=601&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/88424/original/image-20150714-21701-1kb30w1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=755&fit=crop&dpr=1 754w, https://images.theconversation.com/files/88424/original/image-20150714-21701-1kb30w1.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=755&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/88424/original/image-20150714-21701-1kb30w1.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=755&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Health and beauty products were often advertised as containing radioactive elements like radium or thorium. Fortunately for consumers, these claims were rarely true.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Quackery_involving_radioactive_substances#/media/File:Tho-Radia-IMG_1228.JPG">Rama</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>After Hiroshima and Nagasaki, radioactive substances and irradiating machines came directly under the control of a specific few entities: the government, medical authorities and the scientific community. Tangible experiences of radiation became <a href="http://jhmas.oxfordjournals.org/content/67/4/587.full">muted</a> and rarer for Americans, and gee-whiz speculations about atomic energies in popular literature gave way to soberer considerations of the new nuclear reality. American feelings about radiation became more guarded and more related to their anxieties about the broader world than to their personal experiences. Radiation, always inscrutable, became a tabula rasa.</p>
<p>Physicists <a href="http://uncpress.unc.edu/browse/book_detail?title_id=446">emerged from the war</a> with a <a href="http://blog.nuclearsecrecy.com/wp-content/uploads/2012/06/1945-08-12-NYT-Baby-play-with-nice-ball.jpg">fearsome</a> and controversial reputation. Some scientists <a href="https://www.youtube.com/watch?v=CfBLXLz4wQ8">campaigned</a> against further development of nuclear weapons. Many more took Department of Defense funding to do exactly that. </p>
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<figcaption><span class="caption">President Eisenhower announces the Atoms for Peace program in 1953.</span></figcaption>
</figure>
<p>Publicly, the government downplayed weapons research while promoting peaceful <a href="http://newbooksinscitechsoc.com/2014/01/07/angela-n-h-creager-life-atomic-a-history-of-radioisotopes-in-science-and-medicine-university-of-chicago-press-2013/">medical applications</a> of new isotopes. The 1953 “Atoms for Peace” media campaign envisioned international cooperation on energy research. Jobs and comfort came from American uranium, the message went. Obsession with the destructive capacity of atomic energy was the province of the Communist bloc.</p>
<p>The atomic peace dividend was real: nuclear power plants built beginning in 1957 became a <a href="http://www.world-nuclear.org/info/Country-Profiles/Countries-T-Z/USA--Nuclear-Power/">substantial</a> part of the nation’s electrical production. Before the first commercial plant had been built, the chairman of the Atomic Energy Commission gleefully predicted a world in which electricity was “<a href="http://www.thisdayinquotes.com/2009/09/too-cheap-to-meter-nuclear-quote-debate.html">too cheap to meter</a>.”</p>
<h2>Fallout becomes a major fear</h2>
<p>But enthusiasm faded as nuclear plants became a reality. The public did not universally trust the <a href="http://www.nrc.gov/about-nrc/history.html#aec">regulators</a> and corporations that oversaw such plants, nor the engineers and scientists behind them. In March of 1979, two reactors melted down: one at Three Mile Island in Pennsylvania, and one in a <a href="http://www.people.com/people/archive/article/0,,20073417,00.html">movie</a>, The China Syndrome. The fact that the real accident was eventually contained without casualties did little to dispel the anxieties given voice by the movie: that nuclear energies were fundamentally beyond the control of fallible and corruptible people. No further plants were approved until 2012.</p>
<p>Radiation anxiety was heightened by the realization that it was becoming harder to avoid. Civilian scientists, refusing to trust “oracles speaking ‘ex cathedra’ from the Atomic Energy Commission,” conducted nationwide tests of <a href="http://www.stlmag.com/How-to-Stop-a-Nuclear-Bomb-The-St-Louis-Baby-Tooth-Survey-50-Years-Later/">baby teeth</a> beginning in 1959. They found clear evidence that fallout from nuclear tests was accumulating in children’s bodies. By 1963, atmospheric tests had been banned, but the sense that radiation was a form of pollution endemic to the new “atomic age” had taken root. Even natural sources of radiation seemed newly threatening. <a href="http://oldweb.northampton.ac.uk/aps/env/wastes/radon_hotline/radonstory.htm">Radon gas</a>, a selling point for early 20th-century health spas, was discovered in the 1980s to be accumulating in dangerous quantities in some residential basements. </p>
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<figcaption><span class="caption">A terrifying vision of nuclear war: The Day After from 1983.</span></figcaption>
</figure>
<p>It was this threat of omnipresent and involuntary irradiation that gave nuclear weapons their real horror. One might survive the initial blast, but the irradiated landscape that awaited the survivors was subtle and menacing. Richard Rhodes credits the grim 1983 TV movie <a href="http://www.pajiba.com/film_reviews/the-day-after-review-the-most-depressing-movie-of-all-time.php">The Day After</a> with Ronald Reagan’s energetic engagement in disarmament talks. </p>
<p>He was hardly the only person so affected. Books and movies that imagined the world after a nuclear war stressed the physical agonies of radiation sickness. But they also reinforced the association between radiation and mutation: fictional post-nuclear landscapes featured radioactive distortions of both <a href="https://www.youtube.com/watch?v=v4URRp39XOo">the body</a> and the <a href="http://the-toast.net/2013/08/08/slightly-less-beloved-classics-a-canticle-for-leibowitz/">social order</a>. Radiation had always been associated with change, but in an era when nuclear energies posed an existential threat to the world, it was harder to believe that such change would be for the better.</p>
<p>If “radiation” is bound up with Americans’ opinions of the people who wield it, then perhaps the most troubling thing about it is how flimsy and circumstantial their monopoly over it is. There is no longer a “secret of the bomb”; only diplomacy or threats prevent states from acquiring nuclear weapons. Even far simpler devices of mass irradiation – so-called “dirty bombs” – alarm people because of anxiety left over from more than a century of encounters with radiant energy. Cold War-style nuclear anxieties have persisted because we fully trust neither the energies nor the human systems in which they are embedded.</p>
<p><em>This article was updated with a new anniversary year.</em></p><img src="https://counter.theconversation.com/content/41069/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matt Lavine does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The first atom bomb test seventy years ago today marks the start of a change in Americans’ thinking about radiation. On balance, our nuclear anxieties endure today.Matt Lavine, Assistant Professor of History, Mississippi State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/411092015-05-01T18:00:04Z2015-05-01T18:00:04ZSpace travel may be bad for your brain – here’s why<figure><img src="https://images.theconversation.com/files/80083/original/image-20150501-23852-21mvkj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">I really hope this is the right flag</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/gsfc/8252445373/in/photolist-dzeWuV-bBhSJ4-aYusBg-bua5yn-5QtvYE-bumJb-8AnaWX-6dpL4R-o8yPqN-dDQRtX-nJ7s22-dxxRGT-8Cxjuc-6GA6QM-6ocMQM-4ob2SU-pA6owv-4ob2PQ-76paMX-a1HPxu-83MCom-fNvtDr-5G7u4h-7iS6vm-h9btUp-aXqRiD-fv9af7-dLtGYV-nYWYdT-73ZpGY-cuYoEC-9X9mpb-nXaARx-nX3Pp9-LkL8i-6F3xFG-tjmcE-m2SWHp-6jP2Lf-kyjDFX-dHWR7Y-62sH7R-atSbYi-3MiXpn-fN9vvF-fuTS74-bpixTw-5XCsM6-nEFbfq-nEFaBG">NASA/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>There is bad news for those planning to go to Mars in the near future: a study in mice has suggested that radiation in space could <a href="http://advances.sciencemag.org/content/1/4/e1400256">cause cognitive decline</a> in astronauts. However, we know from past research that mental, social and physical <a href="http://www.tcd.ie/Neuroscience/neil/">exercise can boost cognitive functions</a>. With planned Mars missions moving ever closer, it might be be worth exploring activity as a way to counter radiation damage.</p>
<p>There are many hurdles to overcome to get to Mars. The obvious one, of course, is the amount of time it takes – about <a href="http://www.nasa.gov/offices/marsplanning/faqs/">eight months</a>. But for those brave enough to attempt such a journey, this may well be acceptable. What could be harder to accept, however, are the harmful <a href="http://helios.gsfc.nasa.gov/qa_cr.html#em">galactic cosmic rays</a> you’d be subjected to, <a href="http://www.sciencemag.org/content/339/6121/807.full">produced by supernovae</a> far away from Earth. This is a form of radiation that we already know damages the body and increases the risk of cancer. </p>
<h2>Mouse maze</h2>
<p>Worse still, a new report suggests that this type of radiation also damages the brain. In this report, scientists exposed mice to charged particles at the NASA Space Radiation Laboratory. Six week later, they tested the memory abilities of these animals. Unfortunately for those eager to go to Mars, the news was not good.</p>
<p>The scientists used two tests of memory. The first is perhaps the simplest test available for mice: novel object recognition. Mice spontaneously explore new objects placed in their environment, but eventually get used to the objects and spend less time near them. </p>
<p>The task exploited this tendency by first presenting the animals with two identical objects, such as small statues. After the mice had spent some time exploring these, the researchers replaced one of the statues with a different object, for example, a salt shaker. If the mice had remembered exploring the statue, they would show a spontaneous preference for the salt shaker.</p>
<p>But after receiving a dose of radiation, the mice showed significantly less preference for a new object compared to mice who had not been irradiated. Indeed, depending on the type of charged particles that the mice were exposed to, in some instances they had next to no preference for the new object. This indicates that they did not remember the object they explored first.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/80076/original/image-20150501-23887-1kk3f7j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/80076/original/image-20150501-23887-1kk3f7j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=317&fit=crop&dpr=1 600w, https://images.theconversation.com/files/80076/original/image-20150501-23887-1kk3f7j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=317&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/80076/original/image-20150501-23887-1kk3f7j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=317&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/80076/original/image-20150501-23887-1kk3f7j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=398&fit=crop&dpr=1 754w, https://images.theconversation.com/files/80076/original/image-20150501-23887-1kk3f7j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=398&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/80076/original/image-20150501-23887-1kk3f7j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=398&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Can I get directions, please?</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/dullhunk/7095792663/in/photolist-bP2MWP-ri8UrL-mDs5p-mDACW-GuPj-mDtbR-mDsyY-S1iy-bELyzb-dZVM8G-7aTgge-8AQsJW-mDqnf-mDqU8-mDqdT-mDru7-5h17SJ-2odxw3-9M2QU4-dYdrBT-9LDaw1-6tQKDa-5zMk7j-nf6Giw-nHWjuW-bmMhUz-bmMhei-bmMhxz-dMheqg-dMhe4e-m8Qn-823XLT">Duncan Hull/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The researchers also did a second test placing one object in one location and a different object in another, within the same environment. The experimenter then moved one of the objects to a new location, while the other remained in the same place. Ordinarily, the mice would have spent more time exploring the displaced object compared to the object that had not moved. </p>
<p>This indicates that it had learnt the location of each of the two objects. Again, following radiation, the mice did poorly. For several of the doses of charged particles, the animals showed essentially no preference for the displaced object. In short, they either failed to learn the association between the object and the location in which it was initially placed, or they were unable to remember it.</p>
<h2>Staying fit</h2>
<p>So what was the underlying reason for these results? The scientists conducting this work next looked in detail at the neurons – the brain’s functional units – of the mice. In specific regions of the brain, the dendrites – the part of the neurones receiving inputs from other neurons – were less branched. In addition, the specific portions of the neurons where communication takes place, the dendritic spines, were also reduced following exposure to radiation. Mice with the largest loss of spines had the worst memory.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/80086/original/image-20150501-23877-tzwgpo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/80086/original/image-20150501-23877-tzwgpo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=596&fit=crop&dpr=1 600w, https://images.theconversation.com/files/80086/original/image-20150501-23877-tzwgpo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=596&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/80086/original/image-20150501-23877-tzwgpo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=596&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/80086/original/image-20150501-23877-tzwgpo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=749&fit=crop&dpr=1 754w, https://images.theconversation.com/files/80086/original/image-20150501-23877-tzwgpo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=749&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/80086/original/image-20150501-23877-tzwgpo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=749&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Neuron in the brain.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/mikeblogs/3101400087/in/photolist-5J4uci-2zBis-8GG8Yt-9VgKqC-tPh5-4JcJ4G-5zWSMf-dKgNM-Fwxoc-9UwZJ-dnf1dp-9UwZT-9UwZX-9S317-9S32U-9S31f-CM7nW-pyzvv4-bunSTi-6PKTHD-8dvG3G-9S31D-dKCa5-6emXHD-4uyVRP-djq9Ei-62wJCo-cMss2-qpwwZ2-ptXi1d-qVzNcB-5wojQK-bunSPz-5wrz1p-t1cg-haFiqp-bmtp4E-bpKjeG-pMhQdT-51VHbo-mQiJBL-gEVDf-48gtz-haDVrh-7fqz8Y-gUTyhC-h4Dfx2-bViwxs-bx1iPV">Mike Seyfang/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Of course we already knew that <a href="http://www.sciencedirect.com/science/article/pii/S0896627314003900">radiation is bad for you</a> and that cell death is related to memory problems. While the research may have implications for astronauts, it is most likely not as simple as humans getting their neurons fried on the way to Mars and inevitably ending up demented. We now know that the brain is plastic and that the relation between brain damage and memory loss is complex. </p>
<p>So while the loss of connections between neurones likely contributes to the cognitive deficits in dementia, the rate at which this occurs may depend on what you do with your brain, how active you are and what experiences you seek. Current dementia research, for example, indicates that activity is protective. It seems that any activity – be it mental, physical, or social – to an extent protects the brain from succumbing to the worst ravages of dementia. In particular, learning and meeting new people are effective. </p>
<p>Ultimately, memory is based on synaptic plasticity, which is the ability of synapses to strengthen or weaken over time. By introducing extra activity which encourages such plasticity it may be possible to counter radiation damage to the synapses. What would be really useful is research that looks at the consequence of radiation in mice that are staying active and training their memory. If activity does indeed counteract the effects of radiation we could perhaps safely travel to Mars anyway – as long as we play chess and go on Skype dates on the way there.</p><img src="https://counter.theconversation.com/content/41109/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Magdalena Ietswaart receives funding from NIHR. However her views are her own and do not represent thos of NIHR.</span></em></p><p class="fine-print"><em><span>Paul Dudchenko receives funding from BBSRC. However his views are his own and do not represent those of the BBSRC.</span></em></p>Radiation in space could lead to cognitive decline.Magdalena Ietswaart, Academic in Psychology, University of StirlingPaul Dudchenko, Reader in Psychology, University of StirlingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/279032014-08-06T05:06:53Z2014-08-06T05:06:53ZExplainer: how hostile is space?<figure><img src="https://images.theconversation.com/files/55789/original/wgrv8vqd-1407236292.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Not ideal to make music videos.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasamarshall/5512309055">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Space may seem calm, but it is a more hostile environment than that on Earth. Invisible radiation is a big problem for space enthusiasts and scientific instruments. Substituting electronic devices to do human tasks reduces risk, but it doesn’t eliminate all risk. </p>
<p>Every active device in space is dealing with such risks right now – be it <a href="https://theconversation.com/topics/rosetta">Rosetta the comet chaser</a> or the satellite responsible for streaming live sports. These cause many problem for designers of space instruments, on which millions of taxpayer’s money is spent and which are out there to collect important information and provide vital services.</p>
<p>Beyond the risk of <a href="https://theconversation.com/cleaning-up-space-debris-with-sailing-satellites-20384">colliding with other objects in space</a>, there are four main dangers for such electronic devices: the empty vacuum, extreme temperature variability, small meteorite impacts and radiation damage. </p>
<p>The temperature variation in space can be enormous. If an astronaut’s back is facing the sun and the front is not, the temperature difference can be as much as 275°F. The vacuum in space increases the temperature too, as heat cannot escape into the surrounding air as it does on Earth. The vacuum can also free trapped pollutants such as water vapour, and deposit this water on cool parts of the spacecraft where it can cause problems such as shorting electronics. But both sensitivity to vacuum and temperature change are relatively easy to deal with, and can also be monitored with simple sensors on board the device. </p>
<p>Small meteorite impacts are hard to predict but remain rare. What causes the most damage is the the constant flux of radiation in the form of high energy particles. These particles cause permanent damage to electronics, which causes them to become unreliable over time and eventually fail.</p>
<p>There are three main radiation sources in space. The first source consists of galactic particles, originating within the Milky Way, along with extra-galactic particles, originating beyond the Milky Way. These can be very high energy, for example the “<a href="https://www.fourmilab.ch/documents/OhMyGodParticle/">Oh-My-God particle</a>”, which was a proton that had the energy equivalent to “a brick falling on your toe”. The second source consists of solar particles, forming the solar wind, which are expelled by the sun and are lower energy but much more numerous. The third source consists of trapped particles, which form invisible belts around planets with a strong enough magnetic field, such as that of the Earth. These last two sources fluctuate with solar activity, which follows <a href="https://theconversation.com/solar-storms-could-lead-to-a-global-techno-meltdown-16678">an 11-year cycle</a>.</p>
<p>The effects of the most energetic particles are classified as “single event effects” (SEEs). These involve particles which are capable of causing the dreaded “<a href="http://www.maximumpc.com/article/features/blue_screen_death_survival_guide_every_error_explained">blue screen of death</a>”. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/55782/original/66b564yq-1407232487.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/55782/original/66b564yq-1407232487.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/55782/original/66b564yq-1407232487.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/55782/original/66b564yq-1407232487.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/55782/original/66b564yq-1407232487.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/55782/original/66b564yq-1407232487.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/55782/original/66b564yq-1407232487.png?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">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Windows_9X_BSOD.png">Akhristov</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The damages can alter values stored in the memory and processors of digital devices, which can make them stop functioning at the most basic level. One way to deal with such damage is to use many memory cells to hold the same value, and compare values constantly to ensure that information only changes when an update is made to all memory cells at the same time.</p>
<p>The gradual accumulation of damage from high-energy particles on Charge-Coupled Devices (CCDs) (also found in digital cameras) are of more serious concern to scientists. The accuracy of the measurements needed to perform science is so great that any slight damage to these cameras can alter the data received from them. </p>
<p>You can see effects of this damage in a lot of the videos by astronaut Chris Hadfield on board the International Space Station. In full screen and streaming at highest quality, you will find white spots in the darker areas of the picture. These are caused by radiation damage to the sensor, which allows signal to be created by the temperature of the device, rather than the meaningful light particles which form the image. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/xICkLB3vAeU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Although shielding the components can give some effective prevention of radiation damaging the electronics, camera sensors always need an open path in order to take images. Shielding can also create secondary radiation when a damaging particle hits the shield, setting another particle loose.</p>
<p>Sometimes the entire spacecraft design can cause unexpected radiation effects. For example the <a href="http://chandra.harvard.edu/">Chandra X-Ray Observatory</a> launched in 2002 had a design that allowed protons and ions to be focused onto the CCD sensors through grazing from the telescope mirrors. Worse still, these protons were of the precise energy needed to stop inside the charge carrying region of the device, depositing the majority of their energy there, and increasing the damage during transit through the Earth’s radiation belts.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/55557/original/4vvhxgn8-1407006603.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/55557/original/4vvhxgn8-1407006603.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=635&fit=crop&dpr=1 600w, https://images.theconversation.com/files/55557/original/4vvhxgn8-1407006603.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=635&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/55557/original/4vvhxgn8-1407006603.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=635&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/55557/original/4vvhxgn8-1407006603.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=797&fit=crop&dpr=1 754w, https://images.theconversation.com/files/55557/original/4vvhxgn8-1407006603.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=797&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/55557/original/4vvhxgn8-1407006603.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=797&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Image smearing caused by CTI in a Hubble Space Telescope image shown as the raw image (left) and after image correction has been applied (right). Hubble’s radiation mitigation strategy was unique, send up astronauts to replace the sensors.</span>
<span class="attribution"><a class="source" href="http://arxiv.org/pdf/1009.4335v1.pdf">R Massey</a></span>
</figcaption>
</figure>
<p>Although we can heat the sensors in orbit to heal the damage, it is never completely repaired. New methods to deal with the damage are finally coming up with workable solutions. One involves a new type of sensor that captures images using the holes left behind by electrons to capture the image, instead of the electrons themselves. Another involves better processing of the images to counter the damage caused by radiation.</p>
<p>Understanding such damage is becoming more important as scientists need even more sensitive cameras to go in space. For example European Space Agency’s (ESA) Euclid mission is trying to measure the presence of dark matter by detecting the slight change in the shape of galaxies. </p>
<p>Thanks to Albert Einstein’s work, we know that light passing by heavy objects is bent ever so slightly. Dark matter is proposed to make up nearly quarter of all mass in the universe, so to find its presence, the Euclid mission will measure the bending caused by such matter to the light received from galaxies. The bending is so small that if radiation damage is not understood and dealt with, the damage could mask the effects Euclid is looking for. </p>
<p>Just like the Euclid mission, JUICE, another ESA mission due to launch 15 years from now, will spend seven years travelling to Jupiter, resulting in already heavily damaged sensors before science is even able to start. What makes matters worse is that Jupiter has trapped radiation belts of high energy electrons, creating an extremely harsh environment to perform science in. As we continue to develop deeper understanding of effects in sensors, we can extend the useful lifetime of space missions and perform more accurate science.</p>
<hr>
<p><em>Next, read this: <a href="https://theconversation.com/cleaning-up-space-debris-with-sailing-satellites-20384">Cleaning up space debris with sailing satellites</a></em></p><img src="https://counter.theconversation.com/content/27903/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ben Dryer receives funding from e2v technologies plc., who manufacture scientific CCDs. </span></em></p>Space may seem calm, but it is a more hostile environment than that on Earth. Invisible radiation is a big problem for space enthusiasts and scientific instruments. Substituting electronic devices to do…Ben Dryer, Postdoctoral Researcher in Electronic Imaging, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.