tag:theconversation.com,2011:/id/topics/cadmium-14298/articlesCadmium – The Conversation2022-09-27T13:11:58Ztag:theconversation.com,2011:article/1911522022-09-27T13:11:58Z2022-09-27T13:11:58ZNigeria’s sacred Osun River supports millions of people - but pollution is making it unsafe<figure><img src="https://images.theconversation.com/files/486262/original/file-20220923-9077-t1qt1j.jpg?ixlib=rb-1.1.0&rect=16%2C5%2C3578%2C2382&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Osun River has become turbid and unsafe for consumption - threatening its cultural and biodiversity significance. Photo by: Stefan Heunis/AFP via Getty Images.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/woman-throws-a-sacrificial-chicken-into-the-sacred-river-news-photo/1018606984?adppopup=true">from www,gettyimages.com</a></span></figcaption></figure><p><em>Pollution has become a worrying threat to Nigeria’s Osun River. The river supports millions of people who rely on the water for agriculture as well as industries. It is also an integral part of Nigeria’s treasured Osun-Osogbo sacred grove, a UNESCO world heritage site. Emmanuel O. Akindele unpacks what’s causing the pollution, what harm it’s causing and what must change to preserve the river’s biodiversity.</em> </p>
<h2>How important is the Osun River to Nigeria?</h2>
<p>The Osun River is one of the major rivers in southern Nigeria, <a href="https://link.springer.com/article/10.1007/s11356-020-08763-8">draining into the Gulf of Guinea</a>. The river takes its source from Ekiti State. But it’s culturally linked to the ancient city of <a href="https://core.ac.uk/download/pdf/236410037.pdf">Osogbo</a>. A stretch of the river that flows by a sacred grove in the ancient town of Osogbo has been designated a <a href="https://whc.unesco.org/en/list/1118/">UNESCO World Heritage Site</a> due to its <a href="https://whc.unesco.org/en/list/1118">cultural</a> significance. It is one of two such designated sites in <a href="https://whc.unesco.org/en/statesparties/ng">Nigeria</a>. </p>
<p>The river provides a wide range of cultural ecosystem services such as <a href="https://afribary.com/works/assessment-of-the-ecotourism-potentials-of-osun-osogbo-world-heritage-site-osun-state-nigeria">natural scenes</a> for eco-tourists and the site for filming Nollywood movies. A large number of foreign tourists <a href="https://www.academia.edu/52361771/HARNESSING_CULTURAL_HERITAGE_FOR_TOURISM_DEVELOPMENT_IN_NIGERIA_A_STUDY_OF_THE_OSUN_OSOGBO_SACRED_GROVE_AND_FESTIVAL">visit</a> the river each year. The visits are either to pay homage to the river goddess (Osun) or to join others in celebrating the <a href="https://www.vanguardngr.com/2022/08/2022-osun-festival-begins-with-spiritual-cleansing-of-roads/">annual Osun festival</a>. </p>
<p>The river also has enormous environmental value given its rich <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/aje.12482">biodiversity</a>. It supports <a href="https://www.tandfonline.com/doi/abs/10.1080/21658005.2017.1357290?journalCode=tzec20">plankton</a>, <a href="https://www.scielo.sa.cr/scielo.php?script=sci_arttext&pid=S0034-77442007000200034">snakes</a> and <a href="https://www.frim.gov.my/v1/JTFSOnline/jtfs/v26n1/5-15.pdf">endangered plants</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A flowing river bordered by dense forest." src="https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Osun River is one of the last remnants of primary high forest in southern Nigeria - UNESCO World Heritage Site. But pollution is threatening the river.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/osun-river-osun-osogbo-sacred-grove-osogbo-osun-royalty-free-image/1141985549?adppopup=true">from www.gettyimages.com</a></span>
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<p>Along its whole course, the Osun River also plays a <a href="https://www.tandfonline.com/doi/pdf/10.1080/16583655.2019.1567899">critical part</a> in supporting the livelihoods of people. In many areas of Osogbo and Osun State, it provides irrigation for nearby farmlands. A significant number of abattoirs are also situated close to the river bank along several stretches of its course. </p>
<p>The Osun River flows through other human settlements in southwest Nigeria as well as the historic city of Osogbo.</p>
<h2>What are the main sources of the pollution?</h2>
<p>Plastic pollution is the main one. My research has shown that some <a href="https://theconversation.com/nigerian-river-snails-carry-more-microplastics-than-rhine-snails-126622">aquatic snails</a> and <a href="https://theconversation.com/why-microplastics-found-in-nigerias-freshwaters-raise-a-red-flag-147432">insects</a> of the river carry microplastic pollutants. Plastic pollution is a common phenomenon in many inland waters of Nigeria. </p>
<p>Heavy metals also pollute the river. Heavy metals like gold, mercury and cadmium <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4144270/">occur naturally</a> in the Earth’s crust. But they can also be introduced through domestic and industrial wastes, or atmospheric sources. Heavy metals can be <a href="https://www.sciencedirect.com/science/article/pii/S2405844020315346">amplified</a> by human activities like waste deposition or mining. Mining loosens heavy metals buried in the earth, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5129257/">adding more of them</a> to water. </p>
<p>Artisanal gold mining within the catchments of the Osun River, especially around the Ijesha land area of Osun State, have further worsened the ecological condition of the river and made the water <a href="https://www.premiumtimesng.com/news/top-news/548204-osun-osogbo-festival-govt-warns-devotees-tourists-against-drinking-from-river.html">unsafe</a> for human use. </p>
<p>The impact of illegal gold mining on the river cannot be over-emphasised. First, the impacts have been felt on the river’s water quality, which has deteriorated. This has grave implications for its <a href="http://medcraveonline.com/BIJ/water-pollution-and-aquatic-biodiversity.html">biological diversity</a>.</p>
<p>Aside from the introduction of toxicants, the river, which was once <a href="https://www.tandfonline.com/doi/abs/10.1080/21658005.2017.1357290?journalCode=tzec20">transparent</a> enough for photosynthetic production, is now very turbid (cloudy) with a characteristic gold colour. At extremely low water transparency, a river’s phytoplankton primary production could be <a href="https://openprairie.sdstate.edu/cgi/viewcontent.cgi?article=1046&context=oak-lake_research-pubs">threatened</a>, and by implication, its secondary (fish) production could also be threatened. It can also cause fish to die by <a href="https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/255660.pdf">blocking</a> their gills and destroying their reproductive sites. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/KMmMsKIVuTk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Osun river pollution. Credit: UrbanAlert,</span></figcaption>
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<p>Another source of pollution is human-generated <a href="https://www.voanews.com/a/nigeria-s-osun-river-sacred-revered-and-increasingly-toxic/6708178.html">waste</a> that lands up in the river. This is due to <a href="https://theconversation.com/nigerias-plastic-pollution-is-harming-the-environment-steps-to-combat-it-are-overdue-177839">poor waste management practice</a> – a feature common in many urban areas in Nigeria. </p>
<h2>What are the solutions?</h2>
<p>The government must first halt all mining near the river until environmental audits have been conducted, placing urgent human welfare ahead of short-term economic gains. Although the river has already suffered significant harm, it is still possible to halt mining operations so that toxicant concentrations do not keep rising and the river can recuperate from the stress of pollution. </p>
<p>Through natural processes, rivers and streams have the ability to <a href="https://www.sciencedirect.com/science/article/pii/S187802961101022X?via%3Dihub">purify</a> themselves. However, in the instance of the Osun River, this can only happen after the various sources of pollution are stopped. </p>
<p>If further gold mining operations are suggested following an environmental audit of the Osun River, it will be crucial to reroute effluents from all natural waters in the basin. A special reservoir can be constructed in a location far away from where people live and make their living.</p>
<p>A polluted and unsafe environment for plants and animals is a reliable indicator of a similarly unsafe environment for people.</p><img src="https://counter.theconversation.com/content/191152/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emmanuel O. Akindele receives funding from the British Ecological Society. </span></em></p>The ability of the Osun River to support biodiversity is being threatened by pollution and can only be rescued if the contamination ends.Emmanuel O. Akindele, Senior Lecturer, Obafemi Awolowo UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1658662021-11-12T13:36:08Z2021-11-12T13:36:08ZNeurotoxins in the environment are damaging human brain health – and more frequent fires and floods may make the problem worse<figure><img src="https://images.theconversation.com/files/428985/original/file-20211028-23-ey0fbd.jpg?ixlib=rb-1.1.0&rect=242%2C177%2C3352%2C2204&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Wildfire smoke contains a mixture of toxic pollutants that can be harmful to both the lungs and the brain. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/california-wildfires-royalty-free-image/1281624333?adppopup=true">Bloomberg Creative/ Bloomberg Creative Photos via Getty Images</a></span></figcaption></figure><p>In the summer of 2021, a toxic, smoky haze stemming from <a href="https://www.nbcnews.com/western-wildfires">Western wildfires</a> wafted across large parts of the United States, while hurricanes wrought extensive flooding in the southern and eastern U.S. Air quality websites such as <a href="https://www.airnow.gov">AirNow</a> warned of <a href="https://www.npr.org/2021/07/21/1018865569/the-western-wildfires-are-affecting-people-3-000-miles-away">hazardous conditions</a> on the U.S. East Coast from Western forest fires 3,000 miles away, with recommendations to stay indoors. </p>
<p>Journalists reported the immediate impact of lives lost and homes and property destroyed, but more insidious dangers escaped notice. Few people realize that these <a href="https://www.npr.org/2021/09/11/1035241392/climate-change-disasters-mental-health-anxiety-eco-grief">climate change-fueled</a> <a href="https://www.washingtonpost.com/world/interactive/2021/cop26-extreme-weather-climate-change-action/">disasters</a> – both fires and <a href="https://doi.org/10.1080/10807030903051309">floods</a> – could <a href="https://doi.org/10.1080/10962247.2017.1401017">adversely affect human health</a> in longer-term ways. </p>
<p>I’m a <a href="https://scholar.google.com/scholar?as_ylo=2017&q=Arnold+Eiser&hl=en&as_sdt=0,39">scientist-author</a> who studies the links between environmental factors and the development of neurological disorders, which is the <a href="https://rowman.com/ISBN/9781538158074/Preserving-Brain-Health-in-a-Toxic-Age-New-Insights-from-Neuroscience-Integrative-Medicine-and-Public-Health">subject of my recent book</a>. My <a href="https://doi.org/10.1016/j.brainres.2017.06.032">research on this topic</a> adds to a growing body of evidence that <a href="https://www.nytimes.com/2019/07/15/climate/flooding-chemicals-health-research.html">more frequent environmental disasters</a> may be raising <a href="https://doi.org/10.1007/s11356-015-4913-9">human exposure to neurotoxins</a>.</p>
<h2>Neurotoxic smoke</h2>
<p>Many scientists have identified links between <a href="https://doi.org/10.1016/j.bj.2018.06.001">air pollution</a> in various forms, including from <a href="https://theconversation.com/breathing-wildfire-smoke-can-affect-the-brain-and-sperm-as-well-as-the-lungs-166548">forest fire smoke</a>, and an increased risk and prevalence of adverse health effects, including brain disorders. </p>
<p>Wildfire smoke is a mixture of <a href="https://health.ny.gov/environmental/outdoors/air/smoke_from_fire">countless noxious chemical compounds</a>. Fires burning <a href="https://www.theguardian.com/world/2021/aug/09/fires-rage-around-the-world-where-are-the-worst-blazes%20and%20Australia">across the warming planet</a> – from California to Greece and Australia – are adding dangerous particulate matter to the atmosphere that includes <a href="https://doi.org/10.5772/intechopen.97204">neurotoxic heavy metals</a> such as mercury, lead, cadmium and manganese nanoparticles. <a href="https://theconversation.com/whats-in-wildfire-smoke-a-toxicologist-explains-the-health-risks-and-which-masks-can-help-164597">These toxins</a> are an added environmental burden on top of the pollutants emitted by factories, power plants, trucks, automobiles and other sources. </p>
<p>The greatest potential for health problems comes from minuscule particles, smaller than 2.5 microns – or PM 2.5 (for context, the width of a human hair is typically 50 to 70 microns). This is, in part, because <a href="https://doi.org/10.1164/rccm.201903-0635LE">tiny particles are easily inhaled</a>; from the lungs, they enter the bloodstream and circulate widely throughout the body. <a href="https://doi.org/10.3389/fphys.2020.00155">In the brain</a> they may inflame the microglial cells, the brain’s defensive cells, causing harm to neurons instead of protecting them. Studies show that these extremely tiny particles may damage neurons or brain cells by <a href="https://doi.org/10.1016/j.tins.2009.05.009">promoting inflammation</a>. Brain inflammation can lead to conditions <a href="https://doi.org/10.3233/JAD-180631">like dementia</a> and <a href="https://doi.org/10.1097/JOM.0000000000000451">Parkinson’s disease</a>, a movement disorder in adults.</p>
<p>In addition, <a href="https://doi.org/10.1001/jamapediatrics.2018.3101">prenatal</a> and <a href="https://doi.org/10.1097/EDE.0000000000001109">early-life exposure</a> to air pollution has been linked to an increased risk of autism spectrum disorder in children. Research suggests that <a href="https://doi.org/10.1001/jamanetworkopen.2021.7508">air pollution exposure</a> during these critical periods, particularly in the third trimester of pregnancy and the first few months of life, <a href="https://doi.org/10.1515/tnsci-2016-0005">may impair normal neural development</a>. </p>
<h2>Waterborne neurotoxins</h2>
<p>As part of my book research, I investigated potential links between environmental neurotoxins and related health effects in Finland. Seeking unique environmental factors that might underlie the disproportionately high rates of fatal dementia that occurred in Finland in the past decade, I found that <a href="https://doi.org/10.1016/j.brainres.2017.06.032">water pollution</a> – exacerbated by flooding, use of fertilizer and higher water temperatures – may be affecting brain health. </p>
<p>As I reviewed the environmental concerns in Finland, the widespread presence of <a href="https://www.usgs.gov/centers/kswsc/science/cyanobacterial-blue-green-algal-blooms-tastes-odors-and-toxins-0?qt-science_center_objects=0#qt-science_center_objects">blue-green algae in waterways</a> stood out to me. Though it’s commonly called algae, blue-green algae is actually a type of bacteria called cyanobacteria. These toxic microorganisms thrive and proliferate in warm waterways when excessive nutrients, particularly phosphorus from fertilizer runoff, pour into fresh and brackish water. It produces <a href="https://www.epa.gov/cyanohabs/health-effects-cyanotoxins">cyanotoxins</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Blue-green algae bloom on surface of lake with trees in the distance." src="https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=372&fit=crop&dpr=1 600w, https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=372&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=372&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=468&fit=crop&dpr=1 754w, https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=468&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/428983/original/file-20211028-23-lejb0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=468&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">Harmful blooms of blue-green algae on lakes and ponds can be toxic to humans and dogs alike.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/sefton-park-lake-in-liverpool-which-has-been-closed-off-news-photo/1228294229?adppopup=true">Peter Byrne/PA Images via Getty Images</a></span>
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<p>One of these cyanotoxins, β-methylamino-L-alanine, or BMAA, is linked to <a href="https://doi.org/10.3389/fnagi.2020.00026">neurodegenerative disorders</a> including amyotrophic lateral sclerosis, or ALS, Parkinson’s disease and Alzheimer’s disease.
In particular I was struck by scientists’ finding high levels of BMAA in <a href="https://doi.org/10.1073/pnas.0914417107">mollusks and fish found in the Baltic Sea</a>, which could potentially play a role in Finland’s high incidence of dementia, as fish is heavily consumed there.</p>
<p>Blue-green algae is found in <a href="https://www.cdc.gov/habs/index.html">rivers, lakes and seas</a>. Its presence is a widespread problem for humans, dogs and wildlife in the U.S. and Canada, as well as around the globe. In 2020, <a href="https://www.bbc.com/news/world-africa-54234396">more than 300 elephants in Botswana died</a> after drinking from water sources contaminated by the cyanobacteria that cause these algal blooms. Blue-green algae is so widely present in Finland that scientists there have developed <a href="https://www.utu.fi/en/news/news/novel-testing-device-will-reveal-whether-water-contains-toxic-blue-green-algae">a quick test to determine whether it is present or not.</a></p>
<h2>Mold neurotoxins</h2>
<p>In Finland, warm, humid air creates the perfect conditions for mold to grow, and water-damaged buildings are particularly susceptible. Some species emit mycotoxins, or mold toxins. Long-term exposure to mycotoxins, even at low levels, can present <a href="https://doi.org/10.1080/00039896.2003.11879142">serious health hazards</a> for both people and animals. </p>
<p>Mold spores are tiny, making them easy to inhale or ingest. Inside the body they can trigger an immune response, leading to chronic inflammation. Ultimately, exposure to these spores may cause <a href="https://doi.org/10.1016/j.shaw.2020.01.003">cognitive impairment</a>, including memory loss, irritability, numbness, tremors and other symptoms. Such a situation is likely to develop after a region has experienced the flooding of residences or workplaces in the weeks after they have been damaged.</p>
<p>Mold toxins, particularly <a href="https://doi.org/10.1002/mnfr.200600137">ochratoxin A</a>, can trigger inflammation that may harm neurons and brain function. It has been <a href="https://doi.org/10.1016/j.jns.2006.06.006">specifically implicated</a> in Parkinson’s disease. </p>
<h2>Reducing risk and a way forward</h2>
<p>Education, greater awareness of environmental health concerns and public action are the best ways to minimize risks from environmental neurotoxins.</p>
<p>By learning to recognize blue-green algae, people may avoid swimming or boating near it and avoid letting their pets near it too. Consumers can advocate for greater environmental monitoring of food and water sources. Exercise that involves sweating can <a href="https://doi.org/10.1155/2017/3676089">help eliminate neurotoxic substances</a>. But before you exercise outdoors, it is prudent to check air quality on an app or website like <a href="https://www.airnow.gov/">AirNow</a>, a partnership of federal, state, local and tribal agencies.</p>
<p>If environmental policies aren’t put into place to mitigate the health risks posed by environmental neurotoxins, <a href="https://doi.org/10.4172/2161-0460.1000249">research suggests</a> that we may continue to experience increases in a variety of neurodegenerative disorders as the toxins rise. Many of these conditions are labeled idiopathic, or lacking a known cause. The neurotoxic connection is rarely considered, and environmental health hazards are <a href="https://doi.org/10.1186/s12909-020-02458-x">often overlooked in American health care</a>. This is in large part because environmental health is rarely taught in medical education, which can lead to a lack of awareness about potential diagnoses related to an environmental illness.</p>
<p>The U.S. Environmental Protection Agency is currently <a href="https://www.epa.gov/system/files/documents/2021-10/draft-policy-assessment-for-the-reconsideration-of-the-pm-naaqs_october-2021_0.pdf">reevaluating</a> air quality standards for particulate matter. A new EPA <a href="https://www.epa.gov/system/files/documents/2021-09/_epaoig_20210929-21-e-0264.pdf">inspector general report</a> calls for a strategic plan to control harmful algal blooms. Ohio, a leading state for public policy initiatives aimed at neurotoxic algal blooms, <a href="https://grist.org/politics/toxic-algae-blooms-are-multiplying-the-government-has-no-plan-to-help">now regulates</a> cyanotoxins in drinking water and advises farmers against adding fertilizer when the ground is saturated or when rain is in the forecast. </p>
<p>Since <a href="https://doi.org/10.1038/s41586-019-1468-9">climate change may be a driver for rising neurotoxins</a>, cutting greenhouse gas emissions and ensuring better environmental stewardship are essential to human health. Achieving this will require strong international and domestic efforts and a wide range of interventions by governments around the world. But all of these efforts must begin with a deeper and more widespread understanding of the profound nature of this problem – which should be a universal, nonpartisan concern. </p>
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<p class="fine-print"><em><span>Arnold R. Eiser 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>Pollution from more frequent floods and wildfires – exacerbated by the warming climate – is threatening human health and poses particular risks to the brain.Arnold R. Eiser, Emeritus Professor of Medicine, Drexel UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1665372021-09-10T12:28:29Z2021-09-10T12:28:29Z9/11 survivors’ exposure to toxic dust and the chronic health conditions that followed offer lessons that are still too often unheeded<figure><img src="https://images.theconversation.com/files/420128/original/file-20210908-22-728gm5.jpg?ixlib=rb-1.1.0&rect=0%2C125%2C2775%2C1859&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Toxic dust hung in the air around ground zero for more than three months following the 9/11 terrorist attacks.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/an-unidentified-new-york-city-firefighter-walks-away-from-news-photo/1372804?adppopup=true">Anthony Correia/Getty Images</a></span></figcaption></figure><p>The 9/11 terrorist attack on the World Trade Center in New York resulted in the loss of <a href="https://www.cnn.com/2013/07/27/us/september-11-anniversary-fast-facts/index.html">2,753 people in the Twin Towers and surrounding area</a>. After the attack, more than 100,000 responders and recovery workers from every U.S. state – along with <a href="https://www.cdc.gov/wtc/history.html">some 400,000 residents</a> and other workers around ground zero – were exposed to a <a href="https://abcnews.go.com/Health/september-11-toxic-world-trade-center-dust-cloud/story?id=14466933">toxic cloud of dust</a> that fell as a ghostly, thick layer of ash and then hung in the air for more than three months. </p>
<p>The World Trade Center dust plume, or <a href="https://doi.org/10.3109/10408444.2015.1044601">WTC dust</a>, consisted of a dangerous mixture of cement dust and particles, asbestos and a class of chemicals called <a href="https://www.epa.gov/international-cooperation/persistent-organic-pollutants-global-issue-global-response">persistent organic pollutants</a>. These include <a href="https://www.epa.gov/dioxin/learn-about-dioxin">cancer-causing dioxins</a> and <a href="https://www.cdc.gov/biomonitoring/PAHs_FactSheet.html">polyaromatic hydrocarbons, or PAHs</a>, which are byproducts of fuel combustion. </p>
<p>The dust also contained heavy metals that are known <a href="https://www.who.int/news-room/fact-sheets/detail/lead-poisoning-and-health">to be poisonous to the human body and brain</a>, such as lead – used in the manufacturing of flexible electrical cables – and mercury, which is found in float valves, switches and fluorescent lamps. The dust also contained cadmium, a carcinogen <a href="https://doi.org/10.1007/s10534-010-9328-y">toxic to the kidneys</a> that is used in the manufacturing of electric batteries and pigments for paints.</p>
<figure class="align-center ">
<img alt="Smoke pours from the Twin Towers of the World Trade Center in New York City on September 11, 2001." src="https://images.theconversation.com/files/420341/original/file-20210909-27-p4t2aq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/420341/original/file-20210909-27-p4t2aq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/420341/original/file-20210909-27-p4t2aq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/420341/original/file-20210909-27-p4t2aq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/420341/original/file-20210909-27-p4t2aq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=526&fit=crop&dpr=1 754w, https://images.theconversation.com/files/420341/original/file-20210909-27-p4t2aq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=526&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/420341/original/file-20210909-27-p4t2aq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=526&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">One of the haunting images from 9/11: Smoke pours from the twin towers of the World Trade Center in New York after they were hit by two hijacked airliners.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/smoke-pours-from-the-twin-towers-of-the-world-trade-center-news-photo/1339505?adppopup=true">Robert Giroux via Getty Images</a></span>
</figcaption>
</figure>
<p><a href="http://www.idph.state.il.us/envhealth/factsheets/polychlorinatedbiphenyls.htm#:%7E:text=Polychlorinated%20biphenyls%20(PCBs)%20are%20a,equipment%20like%20capacitors%20and%20transformers.">Polychlorinated biphenyls</a>, human-made chemicals used in electrical transformers, were also part of the toxic stew. PCBs are <a href="https://www.epa.gov/pcbs/learn-about-polychlorinated-biphenyls-pcbs#healtheffects">known to be carcinogenic</a>, toxic to the nervous system and disruptive to the reproductive system. But they became even more harmful when incinerated at high heat from the jets’ fuel combustion and then carried by very fine particles. </p>
<p><a href="https://doi.org/10.3109/10408444.2015.1044601">WTC dust</a> was made up of both “large” particulate matter and very small, fine and ultrafine ones. These particularly small particles are known to be <a href="https://doi.org/10.1038/s41598-018-35398-0">highly toxic</a>, especially to the nervous system since they can travel directly through the <a href="https://doi.org/10.1016/j.neuro.2011.12.001">nasal cavity to the brain</a>. </p>
<p>Many first responders and others who were directly exposed to the dust developed a <a href="https://doi.org/10.3109/10408444.2015.1044601">severe and persistent cough</a> that lasted for a month, on average. They were treated at Mount Sinai Hospital and received care at the Clinic of Occupational Medicine, a well-known center for work-related diseases.</p>
<p>I am a physician specializing in occupational medicine who began working directly with 9/11 survivors in my role as director of the <a href="https://www.cdc.gov/wtc/">WTC Health Program</a> <a href="https://icahn.mssm.edu/about/departments/environmental-public-health/research/wtc-data-center">Data Center</a> at Mount Sinai beginning in 2012. That program collects data, as well as monitors and oversees the public health of WTC rescue and recovery workers. After eight years in that role, I <a href="https://stempel.fiu.edu/faculty/roberto-lucchini/">moved to Florida International University</a> in Miami, where I am planning to continue working with 9/11 responders who are moving to Florida as they reach retirement age.</p>
<figure class="align-center ">
<img alt="In lower Manhattan near Ground Zero, people run away as the North Tower of the World Trade Center collapses." src="https://images.theconversation.com/files/420343/original/file-20210909-23-1bc9fnj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/420343/original/file-20210909-23-1bc9fnj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/420343/original/file-20210909-23-1bc9fnj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/420343/original/file-20210909-23-1bc9fnj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/420343/original/file-20210909-23-1bc9fnj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/420343/original/file-20210909-23-1bc9fnj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/420343/original/file-20210909-23-1bc9fnj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Remembering 9/11: As the north tower of the World Trade Center collapses, a cloud of toxic gas chases terrified residents and tourists.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/people-run-away-as-the-north-tower-of-world-trade-center-news-photo/1339533?adppopup=true">Jose Jimenez/Primera Hora via Getty Images</a></span>
</figcaption>
</figure>
<h2>From acute to chronic conditions</h2>
<p>After the initial “acute” health problems that 9/11 responders faced, they soon began experiencing a wave of chronic diseases that <a href="https://doi.org/10.3390/ijerph18126383">continue to affect them</a> 20 years later. The persistent cough gave way to <a href="https://doi.org/10.1001/dmp.2011.58">respiratory diseases</a> such as asthma, chronic obstructive pulmonary disease (COPD) and upper airway diseases such as <a href="https://doi.org/10.1136/oemed-2015-103094">chronic rhinosinusitis</a>, laryngitis and nasopharyngitis. </p>
<p>The litany of respiratory diseases also put many of them at risk for <a href="https://doi.org/10.1038/ajg.2011.357">gastroesophageal reflux disease</a> (GERD), which occurs at a <a href="https://doi.org/10.1097/JOM.0b013e3181845f9b">higher rate in WTC survivors</a> than in the general population. This condition occurs when stomach acids reenter the esophagus, or food pipe, that connects the stomach to the throat. As a consequence of either the airway or the digestive disorders, many of these survivors also <a href="https://doi.org/10.1097/JOM.0b013e3182305282">struggle with sleep apnea</a>, which requires additional treatments.</p>
<p>Further compounding the tragedy, about eight years after the attacks, <a href="https://doi.org/10.1093/jncics/pkz090">cancers began to turn up</a> in 9/11 survivors. These include tumors of the blood and lymphoid tissues such as lymphoma, myeloma and leukemia, which are well known to <a href="https://doi.org/10.1186/1745-6673-8-14">affect workers exposed to carcinogens</a> in the workplace. But survivors also suffer from other cancers, including breast, head and neck, prostate, lung and thyroid cancers. </p>
<p>Some have also developed mesothelioma, an aggressive form of cancer related to <a href="http://dx.doi.org/10.1136/thoraxjnl-2013-204161">exposure to asbestos</a>. <a href="https://www.9news.com.au/9stories/september-11-death-toll-from-terror-attack-could-rise-by-millions-due-to-toxic-asbestos-dust/8bc90677-0032-42a2-82f9-4b9baad753d9">Asbestos</a> was used in the early construction of the north tower until public advocacy and broader awareness of its health dangers <a href="https://www.mesothelioma.com/states/new-york/world-trade-center/">brought its use to a halt</a>.</p>
<p>And the psychological trauma that 9/11 survivors experienced has left many suffering from persistent mental health challenges. One <a href="https://doi.org/10.1007/s10488-019-00998-z">study</a> published in 2020 found that of more than 16,000 WTC responders for whom data was collected, nearly half reported a need for mental health care, and 20% of those who were directly affected developed <a href="https://doi.org/10.1016/j.dadm.2016.08.001">post-traumatic stress disorder</a>. </p>
<p>Many have told me that the contact they had with parts of human bodies or with the deadly scene and the tragic days afterward left a permanent mark on their lives. They are unable to forget the images, and many of them suffer from mood disorders as well as <a href="https://doi.org/10.1186/s12940-019-0449-7">cognitive impairments and other behavioral issues</a>, including substance use disorder. </p>
<figure class="align-center ">
<img alt="On 9/11, shortly after the terrorist attack in New York City, a distraught survivor sits outside the World Trade Center." src="https://images.theconversation.com/files/420347/original/file-20210909-23-do7s5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/420347/original/file-20210909-23-do7s5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/420347/original/file-20210909-23-do7s5e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/420347/original/file-20210909-23-do7s5e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/420347/original/file-20210909-23-do7s5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/420347/original/file-20210909-23-do7s5e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/420347/original/file-20210909-23-do7s5e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Remembering 9/11: A distraught survivor sits outside the World Trade Center after the terrorist attack.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/survivor-sits-outside-the-world-trade-center-after-two-news-photo/50833029?adppopup=true">Jose Jimenez/Primera Hora via Getty Images</a></span>
</figcaption>
</figure>
<h2>An aging generation of survivors</h2>
<p>Now, 20 years on, these survivors face a new challenge as they age and move toward retirement – a <a href="https://doi.org/10.3386/w12123">difficult life transition</a> that can sometimes lead to mental health decline. Prior to retirement, the daily drumbeat of work activity and a steady schedule often helps keep the mind busy. But retirement can sometimes leave a void – one that for 9/11 survivors is too often filled with unwanted memories of the noises, smells, fear and despair of that terrible day and the days that followed. Many survivors have told me they do not want to return to Manhattan and certainly not to the WTC. </p>
<p>Aging can also bring with it forgetfulness and other cognitive challenges. But studies show that these natural processes are <a href="https://doi.org/10.1186/s12940-019-0449-7">accelerated and more severe</a> in 9/11 survivors, similar to the experience of veterans from war zones. This is a concerning trend, but all the more so because a growing body of research, including <a href="https://doi.org/10.21203/rs.3.rs-846359/v1">our own preliminary study</a>, is finding links between <a href="https://doi.org/10.1192/bjp.bp.105.014779">cognitive impairment in 9/11 responders and dementia</a>. A recent <a href="https://www.washingtonpost.com/magazine/2021/08/30/911-first-responders-dementia/">Washington Post piece detailed</a> how 9/11 survivors are experiencing these dementia-like conditions in their 50s – far earlier than is typical. </p>
<p>The COVID-19 pandemic, too, has taken a toll on those who have already suffered from 9/11. People with <a href="https://doi.org/10.1016/j.eclinm.2020.100515">preexisting conditions</a> have been at far higher risk during the pandemic. Not surprisingly, a recent study found a <a href="https://doi.org/10.1371/journal.pone.0254713">higher incidence of COVID-19</a> in WTC responders from January through August 2020.</p>
<h2>Honoring the 9/11 survivors</h2>
<p>The health risks posed by direct exposure to the acrid dust was underestimated at the time, and poorly understood. Appropriate personal protective equipment, such as P100 half-face respirators, was not available at that time. </p>
<p>But now, over 20 years on, we know much more about the risks – and we have much greater access to protective equipment that can keep responders and recovery workers safe following disasters. Yet, too often, I see that we have not learned and applied these lessons. </p>
<p>For instance, in the immediate aftermath of the <a href="https://www.nytimes.com/live/2021/07/06/us/miami-building-collapse-updates">condominium collapse</a> near Miami Beach last June, it took days before P100 half-face respirators were fully available and made mandatory for the responders. Other examples around the world are even worse: One year after the <a href="https://www.npr.org/2021/08/04/1024275186/a-year-after-the-beirut-explosion-victims-families-continue-to-push-for-justice">Beirut explosion</a> in August 2020, very little action had been taken to investigate and manage the physical and <a href="https://timep.org/commentary/analysis/the-beirut-explosions-impact-on-mental-health/">mental health consequences </a> among responders and the impacted community.</p>
<p>Applying the lessons learned from 9/11 is a critically important way to honor the victims and the brave men and women who took part in the desperate rescue and recovery efforts back on those terrible days.</p><img src="https://counter.theconversation.com/content/166537/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roberto Lucchini receives funding from CDC/NIOSH to study the cognitive impacts associated to the WTC exposure to neurotoxins and to intense psychological trauma. </span></em></p>Those directly exposed to toxic dust and trauma on and after 9/11 carry with them a generation of chronic health conditions, which are placing them at higher risk during the pandemic and as they age.Roberto Lucchini, Professor of Occupational and Environmental Health Sciences, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1455422020-09-23T05:55:08Z2020-09-23T05:55:08ZOur toxic legacy: bushfires release decades of pollutants absorbed by forests<figure><img src="https://images.theconversation.com/files/359468/original/file-20200923-16-1phr8ww.jpg?ixlib=rb-1.1.0&rect=125%2C33%2C5434%2C3667&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>We know forests absorb carbon dioxide, but, like a sponge, they also soak up years of pollutants from human activity. When bushfires strike, these pollutants are re-released into the air with smoke and ash. </p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0269749120360887">Our new research</a> examined air samples from four major bushfires near Sydney between 1984 and 2004. We found traces of potentially toxic metals sourced from the city’s air — lead, cadmium and manganese — among the fine particles of soil and burnt vegetation in bushfire smoke.</p>
<p>These trace metals were associated with leaded petrol — which hasn’t been used since 2002 — and industrial emissions, which include past metal processing, fossil fuel burning, refineries, transport and power generation. </p>
<p>This means bushfires, such as the those that devastated Australia last summer, can remobilise pollutants we’ve long phased out. The health and other effects may not be fully understood or realised for decades.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/356507/original/file-20200904-14-ya8k73.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An infographic showing how forests soak up pollutants and then release them in fires." src="https://images.theconversation.com/files/356507/original/file-20200904-14-ya8k73.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/356507/original/file-20200904-14-ya8k73.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=321&fit=crop&dpr=1 600w, https://images.theconversation.com/files/356507/original/file-20200904-14-ya8k73.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=321&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/356507/original/file-20200904-14-ya8k73.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=321&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/356507/original/file-20200904-14-ya8k73.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=403&fit=crop&dpr=1 754w, https://images.theconversation.com/files/356507/original/file-20200904-14-ya8k73.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=403&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/356507/original/file-20200904-14-ya8k73.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=403&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How bushfires can resurrect pollutants years after they were emitted. Pb is lead, Cd is cadmium, Mn is manganese, and TSP is ‘total suspended particulates’</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Analysing air samples</h2>
<p>We chose four major bushfires — which occurred in 1984, 1987, 2001-2002 and 2004 — because of their known impact on air quality across Sydney. The New South Wales government collected air samples every sixth day on filters over that period and archived them, which meant we could study them years later.</p>
<p>We analysed these air samples during the bushfire periods and compared them to the months either side of each event.</p>
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Read more:
<a href="https://theconversation.com/california-is-on-fire-from-across-the-pacific-australians-watch-on-and-buckle-up-145170">California is on fire. From across the Pacific, Australians watch on and buckle up</a>
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<p>As expected, air pollution levels were higher during bushfires periods, in terms of total suspended particles and fine particles (“PM10”, which are particles 10 microns or less in size). </p>
<p>Using statistical analyses, we separated the source components of the particles: those from natural soils and those originating from human-sourced pollutants. We found the concentration of the human-sourced pollutant component — containing lead and cadmium — doubled during bushfire periods. </p>
<p>Pollution of the air with cadmium is associated with mining, refining, burning fossil fuels, and even from household wastes. But the source of lead pollution has a more complicated story. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/356509/original/file-20200904-24-1yx31ou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/356509/original/file-20200904-24-1yx31ou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=607&fit=crop&dpr=1 600w, https://images.theconversation.com/files/356509/original/file-20200904-24-1yx31ou.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=607&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/356509/original/file-20200904-24-1yx31ou.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=607&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/356509/original/file-20200904-24-1yx31ou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=763&fit=crop&dpr=1 754w, https://images.theconversation.com/files/356509/original/file-20200904-24-1yx31ou.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=763&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/356509/original/file-20200904-24-1yx31ou.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=763&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Average levels of metals and particles in Sydney’s air before, during and after bushfires.</span>
</figcaption>
</figure>
<h2>A story written in lead</h2>
<p>Isotopes are variants of an element, such as lead. Different lead “<a href="https://theconversation.com/explainer-what-is-an-isotope-10688">isotopes</a>” have different atomic masses. </p>
<p>Our study measured lead <a href="https://theconversation.com/explainer-what-is-an-isotope-10688">isotopes</a> in the air samples to “fingerprint” the pollution sources. </p>
<p>The data show that the source of the lead ranges from natural origins derived from the weathering of rocks to those from leaded petrol emissions. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-an-isotope-10688">Explainer: what is an isotope?</a>
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<p>Leaded petrol started being phased out <a href="https://www.racq.com.au/cars-and-driving/cars/owning-and-maintaining-a-car/facts-about-fuels/unleaded-petrol-and-pre-1986-cars#:%7E:text=Many%20vehicles%20built%20before%201986,withdrawn%20from%20the%20Australian%20market.">in 1985</a> due to environmental and health concerns, and hasn’t been used in vehicles since 2002. Much smaller amounts are still used in AVGAS — the fuel used to power small piston aircraft engines. </p>
<p>As a result, lead levels in Sydney’s air decreased dramatically from 1984 to 2004. At the same time, the lead isotopes in the air changed. </p>
<p>The lead used in NSW <a href="https://www.sciencedirect.com/science/article/abs/pii/S0883292717301300">petrol</a> predominantly came from the mines at Broken Hill. Broken Hill lead has a very different isotopic signature to the lead found in Sydney’s main bedrock, Hawkesbury Sandstone. This corresponds to previous research showing ash from <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969717311440?via%3Dihub">Sydney trees</a> contained Broken Hill lead. </p>
<p>In 1994, lead in Sydney’s air was closer to the Broken Hill lead signature. By 2004, the lead isotopes in air resembled natural Sydney rocks. But during bushfires in 2001-2002 and 2004, the lead that was released started to look more like Broken Hill lead again. </p>
<p>This shows that the forests had absorbed leaded petrol emissions over the 70 years it was used and stored them. When the forests went up in flames, the lead was remobilised along with smoke and other bushfire particles.</p>
<h2>What does that mean for our health?</h2>
<p>Breathing in bushfire smoke is a serious <a href="https://www.mja.com.au/journal/2020/213/6/unprecedented-smoke-related-health-burden-associated-2019-20-bushfires-eastern">health risk</a>. Bushfire smoke resulted in more than 400 excess deaths during the devastating 2019-2020 bushfires.</p>
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<a href="https://images.theconversation.com/files/359469/original/file-20200923-14-6o0h4v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A huge plume of smoke coming from a forest" src="https://images.theconversation.com/files/359469/original/file-20200923-14-6o0h4v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/359469/original/file-20200923-14-6o0h4v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/359469/original/file-20200923-14-6o0h4v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/359469/original/file-20200923-14-6o0h4v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/359469/original/file-20200923-14-6o0h4v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/359469/original/file-20200923-14-6o0h4v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/359469/original/file-20200923-14-6o0h4v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The concentrations of toxic metals aren’t high enough to be a health risk.</span>
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<p>Recently, the focus of air quality and health research has shifted to very fine particles: “PM2.5”. These are particles 2.5 microns or smaller that can penetrate deep into our lungs. During the Black Summer bushfires of 2019-2020, PM2.5 levels reached <a href="https://www.ansto.gov.au/news/fine-particle-pollution-peaks-during-bushfires">85 micrograms per cubic metre of air over 24-hours</a>, more than three times the Australian air quality criteria of 25 micrograms per cubic metre.</p>
<p>While our study shows that potentially toxic metals were more elevated in the atmosphere during bushfires, the concentrations were not likely to be a health risk. The main risk is from the total concentration of fine particles in the air, rather than what they are made of.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/to-reduce-disasters-we-must-cut-greenhouse-emissions-so-why-isnt-the-bushfire-royal-commission-talking-about-this-145323">To reduce disasters, we must cut greenhouse emissions. So why isn't the bushfire royal commission talking about this?</a>
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<p>The concentrations of the trace metals measured during the four major bushfires in our study were below <a href="https://www.epa.nsw.gov.au/your-environment/air/industrial-emissions/modelling-assessing-air-emissions/approved-methods-modelling-assessing-air-pollutants">Australian</a> and <a href="http://www.euro.who.int/__data/assets/pdf_file/0019/331660/Evolution-air-quality.pdf">World Health Organisation</a> criteria. The period of increased exposure was also very limited, further reducing risk. </p>
<p>Nevertheless, it’s important to minimise exposure to all chemical contaminants. This is because many, such as lead, have no safe lower exposure limit and the effects are often proportionately greater at the first and <a href="https://doi.org/10.1371/journal.pbio.2003066">lowest exposure levels</a>.</p>
<h2>A lingering legacy</h2>
<p>It’s not just Australian forests that have a lingering toxic legacy. In Ukraine and Belarus, <a href="https://doi.org/10.1016/j.scitotenv.2019.133954">radioactive materials</a> from Chernobyl have been released during bushfires. </p>
<p>And as global knowledge of the <a href="https://www.epa.gov/international-cooperation/persistent-organic-pollutants-global-issue-global-response">damaging effects</a> of pesticides grew, we stopped using them. Yet we <a href="https://www.thearcticinstitute.org/persistent-organic-pollutants-pops-in-the-arctic/">still find them</a> far from civilisation in the frozen Arctic, waiting to be released when the ice melts.</p>
<p>Metals such as lead, copper, manganese and uranium continue to be mined and processed in Australia. The most significant <a href="https://search.informit.com.au/documentSummary;dn=459442988919303;res=IELENG">environmental and health impacts</a> are felt by the immediately surrounding communities, <a href="https://www.youtube.com/watch?v=zEgLPiFKVm8">particularly children</a>, as <a href="https://www.sciencedirect.com/science/article/pii/S0160412018308869">contaminants in the air deposit</a> on surfaces and are later ingested. </p>
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<p>Globally, the <a href="https://apps.who.int/iris/bitstream/handle/10665/259447/9789241512855-eng.pdf;jsessionid=DE707557C9481D70B0254A6C19800F1A?sequence=1">recycling of lead batteries</a> continues to contaminate communities and environments, particularly those in <a href="https://annalsofglobalhealth.org/articles/abstract/10.1016/j.aogh.2016.10.015/">low to middle income countries</a>. </p>
<p>Yes, our modern lifestyles <a href="http://www.austmine.com.au/News/category/articles-editorials/the-top-10-metals-and-minerals-powering-your-mobile-phone">depend on</a> these metals and other toxic chemicals. So, we must mine, use and dispose of them with great care, because once in the environment, they <a href="https://www.euro.who.int/__data/assets/pdf_file/0007/78649/E91044.pdf">do not</a> go away.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-bushfires-and-rain-turned-our-waterways-into-cake-mix-and-what-we-can-do-about-it-144504">How bushfires and rain turned our waterways into 'cake mix', and what we can do about it</a>
</strong>
</em>
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<img src="https://counter.theconversation.com/content/145542/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cynthia Faye Isley receives funding from Macquarie University and an Australian Government Citizen Science Grant, CSG55984 to MP Taylor ‘Citizen insights to the composition and risks of household dust’ (the DustSafe project).</span></em></p><p class="fine-print"><em><span>Mark Patrick Taylor receives funding from the Australian Research Council and the Australian Government via its Citizen Science Grants, number: CSG55984 ‘Citizen insights to the composition and risks of household dust’ (the DustSafe project). He is also affiliated with the Broken Hill Lead Reference Group, LEAD Group Inc. (Australia) and NSW EPA’s Broken Hill Environmental Lead Program. The research, sample collection and analysis was supported in part by a Macquarie University Outside Studies Program to MP Taylor.
</span></em></p>Leaded petrol hasn’t been used since 2002, but new research found traces of it end up back in the air after bushfires.Cynthia Faye Barlow, Postdoctoral Research Fellow in Environmental Science, Macquarie UniversityMark Patrick Taylor, Professor of Environmental Science, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1311552020-02-07T03:16:08Z2020-02-07T03:16:08ZChocolate contains cadmium that can increase cancer risk<figure><img src="https://images.theconversation.com/files/313664/original/file-20200205-149802-1gai64i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The amount of cadmium content in cocoa beans depends on the location and soil conditions where the chocolate plant is grown and type of chocolate plant itself.</span> <span class="attribution"><span class="source">iravgustin/Shutterstock</span></span></figcaption></figure><p>Children and adults all over the world love chocolate, either enjoying it by eating chocolate bars or sipping warm cocoa drinks. </p>
<p>But behind its delicious taste, cacao contains cadmium, a chemical substance <a href="https://www.who.int/water_sanitation_health/dwq/chemicals/cadmium.pdf">harmful to kidneys</a>. It also increases the <a href="https://www.who.int/water_sanitation_health/dwq/chemicals/cadmium.pdf">risk of cancer</a>. </p>
<p>If we compare it to other harmful heavy metals like <a href="https://www.who.int/news-room/fact-sheets/detail/arsenic">arsenic</a>, cadmium may not seem to be that bad. But, exposure to cadmium for a long time, even in small amounts, can be dangerous as it accumulates in the body. Our body needs <a href="https://www.sciencedirect.com/science/article/pii/S0041008X09001690">ten to thirty years to digest cadmium</a>.</p>
<p>This is why the European Commission last year decreased the safety threshold of the amount of cadmium in processed chocolate in the region. The <a href="https://ec.europa.eu/food/sites/food/files/safety/docs/cs_contaminants_catalogue_cadmium_chocolate_en.pdf">cadmium threshold</a> is between 0.1 and 0.8 milligrams per kilogram of chocolate, depending on the type of chocolate.</p>
<p>Dark chocolate, for instance, has a lower ceiling than milk chocolate. All chocolate imported to Europe have to comply with the limit. </p>
<p>Europe’s decision was <a href="https://www.chemistryworld.com/news/why-cadmium-is-a-problem-for-chocoholics/3009994.article">based on research that showed</a> even though cadmium exposure in adult non-smokers in the region is still below WHO’s upper limit, exposure through food in children reaches twice the safe limit.</p>
<p>Meanwhile in Indonesia, the maximum limit on cadmium is <a href="http://sertifikasibbia.com/upload/logam_berat.pdf">0.5 milligram per kilogram of chocolate and cacao product</a>. The amount is roughly the same as the new European regulation for processed chocolate with over 30% cacao. </p>
<h2>Cadmium levels</h2>
<p>Chocolate is not the only food that contains cadmium. But because chocolate is often consumed by people of all ages, including children, its amount of cadmium must be regulated. This chemical is often associated with <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3248365/">bone density problems</a>. </p>
<p>Cadmium levels in processed chocolate on the market vary depending on the production process and the producers. </p>
<p>Generally, the cadmium rate in processed chocolate is minimal because of the mixing of raw chocolate with milk, sugar and syrup during production. The chocolate level in a product is between 10% (for milk chocolate) and 70-100% (for dark chocolate). However, if you eat too much chocolate for a long time, the cadmium amount in your body will increase.</p>
<p>A 2010 study on cadmium levels in chocolate powder from various countries showed chocolate powder from Venezuela <a href="https://www.tandfonline.com/doi/abs/10.1080/0265203031000077888">was up to 1.8 milligrams per kilogram of powder</a>. It’s higher than the European Commission standard. </p>
<p>Meanwhile, several studies on cadmium in processed chocolate in <a href="https://pubs.acs.org/doi/abs/10.1021/jf5026604">Brazil</a>, the <a href="https://www.tandfonline.com/doi/full/10.1080/19393210.2017.1420700">United States</a> and <a href="https://www.sciencedirect.com/science/article/pii/S0889157504000900">India</a> concluded the level of cadmium was under the safety limit. </p>
<p>Even in chocolate containing 100% chocolate, some processing has been carried out. Mixing cocoa beans from several sources, for example, can reduce the levels of cadmium in processed chocolate. The amount of cadmium content in cacao beans <a href="https://ec.europa.eu/food/sites/food/files/safety/docs/cs_contaminants_catalogue_cadmium_chocolate_en.pdf">depends on the location and soil conditions where the chocolate plant is grown</a>, as well as on the type of the chocolate plant itself.</p>
<p>WHO only has a limit on the amount of cadmium for dried cacao beans – <a href="https://www.berkeleywellness.com/healthy-eating/food-safety/article/there-cadmium-your-cocoa">0.3 milligrams per kg</a>. The maximum level of cadmium that can be tolerated by the human body, according to WHO, is <a href="https://iopscience.iop.org/article/10.1088/1755-1315/259/1/012005/pdf">0.025 milligrams per kg of body mass</a>. This is equivalent to 1.25 milligrams of cadmium for a person with a body weight of 50 kilograms per month.</p>
<p>By the WHO’s standard, it is potentially dangerous for a person who weighs 50 kilograms to consume more than 12.5 kilograms of 30% cocoa processed chocolate, that is under the European Commission’s ceiling, in a month; or to consume 2.5 kilograms of processed chocolate according to Indonesia’s ceiling.</p>
<h2>Cadmium exposure</h2>
<p>Exposure to excessive cadmium through food has <a href="https://www.who.int/water_sanitation_health/dwq/chemicals/cadmium.pdf">a significant effect on kidney health</a>, disrupting <a href="https://mcb.berkeley.edu/courses/mcb135e/kidneyprocess.html">reabsorption (such as the reabsorption of protein salt the body still needs)</a> <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5596182/">in the kidney’s</a> filtering unit.</p>
<p>Apart from food, cadmium exposure through <a href="https://www.who.int/water_sanitation_health/dwq/chemicals/cadmium.pdf">air is known to increase cancer risk</a>, causing <a href="https://occup-med.biomedcentral.com/articles/10.1186/1745-6673-1-22">shortness of breath, lung irritation and mucous membrane damage</a>. Cadmium exposure through the air in daily life, for example, occurs <a href="https://err.ersjournals.com/content/27/147/170122.short">through cigarette smoke</a>.</p>
<p>In the 1960s, Japan experienced cadmium contamination in its water. <a href="https://link.springer.com/article/10.1007/BF00381306">A study of a decades-long strange illness</a> in residents in Toyama Prefecture reveals “itai-itai” disease, caused by heavy metal pollution, especially cadmium, from mines in the upper reaches of the Jinzu River. <a href="https://www.who.int/water_sanitation_health/dwq/chemicals/cadmium.pdf">Itai-itai disease is marked</a> by bone softening, bone loss and kidney damage.</p>
<p>People with this disease complain of pain in the spine and joints due to reduced bone density associated with the toxic effects of cadmium. However, keep in mind this is an extreme case caused by chronically large amounts of cadmium poisoning.</p>
<h2>Why does food contain cadmium</h2>
<p>Plants can absorb and accumulate cadmium from water in the soil.</p>
<p>Chocolate plants can absorb cadmium through its roots and store it in chocolate leaves and seeds. This absorption can be influenced by <a href="https://ief.ee.ethz.ch/content/main/en/news-and-events/eth-news/news/2016/11/cadmium-cocoa-beans-and-chocolate.html">soil acidity and the amount of cadmium available in the soil</a>.</p>
<p>Therefore, geographical location can affect the cadmium content in plants. Volcanic soils, for instance, can contain higher amounts of cadmium. Environmental pollution and excessive use of fertilisers containing cadmium are also <a href="http://ejournal.forda-mof.org/ejournal-litbang/index.php/JKLH/article/view/4911/4371">factors affecting cadmium levels in the soil</a>.</p>
<p>In the case of itai-itai disease in Japan, cadmium in wastewater from mines flows and pollutes water sources used for irrigation by residents. Water pollution also pollutes aquatic ecosystems such as rivers and seas.</p>
<p>In addition to preventive action, remediation is <a href="https://publikasiilmiah.ums.ac.id/xmlui/bitstream/handle/11617/9326/fix%20prosiding%20SNPBS%202017%20Final%20Akhir%20fix%20deal%2023%20AGUSTUS_p188-p198.pdf?sequence=1&isAllowed=y">one of the solutions to reduce levels of cadmium in the environment</a>.</p>
<h2>Reducing cadmium exposing</h2>
<p>The easiest way to reduce the risk of cadmium exposure in everyday life is to avoid materials that have the potential to contain large amounts of it.</p>
<p>For example, you should limit consumption of chocolate, <a href="https://www.republika.co.id/berita/nasional/daerah/18/02/27/p4t1m9335-rentetan-kejadian-keracunan-penyu-di-mentawai">shellfish taken from contaminated waters</a> and <a href="https://www.popsci.com/heavy-metals-baby-food/">plants harvested from contaminated soil</a>. You should stop smoking and keep away from secondhand smoke exposure to avoid cadmium through the air.</p>
<p>Environmental pollution causes a high amount of cadmium in various foods. Therefore, the most appropriate way to reduce cadmium exposure is to protect the environment from the potential for cadmium pollution.</p>
<p>Disposing of NiCd (nickel-cadmium) batteries properly, using fertilisers that contain cadmium at appropriate levels, and monitoring the content of cadmium in the environment around waste disposal are some examples of preventive measures that can reduce exposure to cadmium in the community.</p><img src="https://counter.theconversation.com/content/131155/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mila Sari tidak bekerja, menjadi konsultan, memiliki saham, atau menerima dana dari perusahaan atau organisasi mana pun yang akan mengambil untung dari artikel ini, dan telah mengungkapkan bahwa ia tidak memiliki afiliasi selain yang telah disebut di atas.</span></em></p>Chocolate plants can absorb cadmium through their roots and store it in chocolate leaves and seeds. Cadmium levels in processed chocolate depending on the production process and the producers.Mila Sari, PhD Researcher in Chemistry, University of HullLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/958492018-06-13T23:12:22Z2018-06-13T23:12:22ZToxic leftovers from Giant Mine found in snowshoe hares<figure><img src="https://images.theconversation.com/files/221847/original/file-20180605-119847-bo5590.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Snowshoe hares near the now closed Giant Mine outside of Yellowknife, N.W.T show signs of arsenic contamination.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/denalinps/6990916044">(Denali NPS/flickr)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Even though it was closed decades ago, the Giant Mine on the outskirts of Yellowknife has left a long environmental legacy. </p>
<p>The gold extraction process, which required roasting ores at extremely high temperatures, created a toxic byproduct called arsenic trioxide. For about 55 years (1948-2004), arsenic and other toxic elements were released into the environment, causing <a href="http://www.rcinet.ca/eye-on-the-arctic/2016/08/24/arsenic-contamination-persists-in-yellowknife-lake-a-decade-after-gold-mine-shut-study/">widespread contamination of the terrestrial and aquatic ecosystems around Yellowknife</a>. </p>
<p>About <a href="http://www.cbc.ca/news/canada/north/giant-mine-arsenic-process-1.4418862">237,000 tonnes of arsenic trioxide dust is buried</a> underground, and <a href="http://www.cbc.ca/news/canada/north/dots-lakes-arsenic-nwt-yellowknife-water-1.4230597">several nearby lakes show arsenic contamination</a>. </p>
<p>Elevated arsenic levels have also been reported in soil, vegetation and fish around Yellowknife, but we knew little about how it has affected the health of the small mammals that live in the area. </p>
<p>Many of these fur-bearing animals are still being trapped for their pelts and for food, so knowing their arsenic levels is also important for human health.</p>
<h2>Weak bones</h2>
<p>Small mammals can serve as sentinels for environmental contamination. Snowshoe hares (<em>Lepus americanus</em>) live in a relatively small area and eat soil, so they are likely to accumulate higher levels of arsenic and other trace metals from the environment. </p>
<p>Exposure to elevated levels of arsenic can cause damage to the liver and other organs. And cadmium, a toxic metal and another byproduct of the gold extraction process, can replace calcium in the bones, leading to bone deformities and weakness. </p>
<p>In humans, chronic arsenic exposure (usually from water) can lead to <a href="https://www.epa.gov/sites/production/files/2014-03/documents/human_health_effects_from_chronic_arsenic_poisoning_3v.pdf">changes in skin colour, skin growths and cancers of the skin, lung and internal organs</a>.</p>
<p>When we measured arsenic and cadmium levels in hares living within two kilometres of the Giant Mine and compared them to hares living about 20 kilometres away from Yellowknife, the results were striking. </p>
<p>The arsenic levels in the guts of snowshoe hares living near the Giant Mine were <a href="https://www.sciencedirect.com/science/article/pii/S0048969717322982">20-50 times greater</a> than those living away from it. We also saw higher concentrations of arsenic in the organs and nails of the Giant Mine hares. </p>
<p>Cadmium levels were also higher but the difference wasn’t as marked. Hares from both locations had weaker bones and showed signs of osteoporosis, probably due to <a href="https://academic.oup.com/toxsci/article/82/2/468/1656953">chronic exposure to cadmium</a>. </p>
<h2>Ecological implications</h2>
<p>This chronic exposure to elevated levels of arsenic and cadmium may explain why snowshoe hares living near the Giant Mine are in poor health. </p>
<p>Wildlife living in metal contaminated areas in other parts of the world have also shown problems with reproduction, osteoporosis, neurological damage and chronic metabolic disease. But in Canada, it’s the first time we’ve seen small wild mammals with chronic arsenic poisoning.</p>
<p>The high levels of pollutants could compromise the long-term survival of the snowshoe hare and other small mammals in the Yellowknife area. </p>
<p>The high arsenic and cadmium burden in hares could have consequences for other animals that prey on them, such as foxes, wolves or other carnivorous mammals, and <a href="https://www.aadnc-aandc.gc.ca/eng/1524242446493/1524243007228">for the people who hunt them</a>.</p><img src="https://counter.theconversation.com/content/95849/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr. Som Niyogi is a Professor at the Department of Biology and an associate faculty of Toxicology Program, University of Saskatchewan. He receives research funding from the Aurora Research Institute, and Natural Sciences and Engineering Research Council (NSERC) of Canada. </span></em></p><p class="fine-print"><em><span>Dr. Solomon Amuno is adjunct professor at the School of Environment and Sustainability, University of Saskatchewan. He receives funding from the Aurora Research Institute.</span></em></p>Historical gold mining at the Giant Mine near Yellowknife, N.W.T. released toxic arsenic into the environment. Snowshoe hares are showing signs of poisoning.Som Niyogi, Professor, University of SaskatchewanSolomon Amuno, Adjunct Professor, University of SaskatchewanLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/359532015-01-07T20:32:26Z2015-01-07T20:32:26ZAre quantum dot TVs – and their toxic ingredients – actually better for the environment?<p>Earlier this week, <a href="https://theconversation.com/the-future-is-bright-the-future-is-quantum-dot-televisions-35765">The Conversation</a> reported that, “The future is bright, the future is … quantum dot televisions.” And judging by the buzz coming from this week’s annual Consumer Electronics Show (<a href="http://www.cesweb.org/">CES</a>) that’s right – the technology is providing manufacturers with a cheap and efficient way of producing the next generation of brilliant, high-definition TV screens.</p>
<p>But the quantum dots in these displays also use materials and technologies – including engineered nanoparticles and the heavy metal cadmium – that have been a magnet for health and environmental concerns. Will the dazzling pictures this technology allow blind us to new health and environmental challenges, or do their benefits outweigh the potential risks?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Vials of quantum dots producing vivid colors from violet to deep red.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Quantum_Dots_with_emission_maxima_in_a_10-nm_step_are_being_produced_at_PlasmaChem_in_a_kg_scale.jpg">Antipoff</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Answer’s not black and white</h2>
<p>Quantum dots are a product of the emerging field of nanotechnology. They are made of nanometer-sized particles of a semiconducting material – often cadmium selenide. About 2,000 to 20,000 times smaller than the <a href="http://www.nano.gov/nanotech-101/what/nano-size">width</a> of a single human hair, they’re designed to absorb light of one color and emit it as another color – to fluoresce. This property makes them particularly well-suited for use in products like tablets and TVs that need bright, white, uniform backlights.</p>
<p>There are of course other chemicals, such as phosphor, that fluoresce and are used in consumer products. What is unique about quantum dots is that the color of the emitted light can be modified by simply changing the size of the quantum dot particles. And because this color-shifting is a physical phenomenon, quantum dots far outperform their chemical counterparts in brightness, color and durability.</p>
<p>Unfortunately, the heavy metal cadmium used in the production of many quantum dots is a health and environmental hazard. Under the <a href="http://ec.europa.eu/environment/waste/rohs_eee/legis_en.htm">European Restrictions on Hazardous Substances</a> directive, its use is restricted in electronic equipment. And cadmium and cadmium compounds have been classified as <a href="http://monographs.iarc.fr/ENG/Monographs/vol100C/mono100C-8.pdf">carcinogenic to humans</a> by the International Agency for Research on Cancer.</p>
<p>On top of this, the potential <a href="http://dx.doi.org/10.1093/toxsci/kfq372">health and environmental impacts</a> of engineered nanoparticles like quantum dots have been raising concerns with toxicologists and regulators for over a decade now. Research has shown that the size, shape and surface properties of some particles influence the harm they are capable of causing in humans and the environment; smaller particles are often more toxic than their larger counterparts. That said, this is an area where scientific understanding is still developing.</p>
<p>Together, these factors would suggest caution is warranted in adopting quantum dot technologies. Yet taken in isolation they are misleading.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=453&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=453&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=453&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cadmium selenide nanocrystals on top of a silicon wafer. Each hexagon is 45 microns across.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/argonne/8023118362">Argonne National Laboratory</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>Quantum dots under glass</h2>
<p>The quantum dots currently being used in TVs are firmly embedded in the screens – usually enclosed behind multiple layers of glass and plastic. As a result, the chances of users being exposed to them during normal operation are pretty much nil.</p>
<p>The situation is potentially different during manufacturing, when there is a chance that someone could be inadvertently exposed to these nanoscopic particles. Scenarios like this have led to agencies like the US National Institute for Occupational Safety and Health taking a close look at safety when <a href="http://www.cdc.gov/niosh/topics/nanotech/">working with nanoparticles</a>. While the potential risks are not negligible, good working practices are effective at reducing or eliminating potentially harmful exposures.</p>
<p>End-of-life disposal raises additional concerns. While the nanoparticles are likely to remain firmly embedded within a trashed TV’s screen, the toxic materials they contain, including cadmium, could well be released into the environment. Cadmium is certainly a health and environmental issue with poorly regulated e-waste disposal and recycling. However, when appropriate procedures are used, exposures should be negligible.</p>
<p>These concerns could be enough to tip the balance against using quantum dots in consumer electronics for some. But they only tell part of the story because these small, bright particles also come with environmental benefits.</p>
<h2>But there are bright benefits</h2>
<p>Quantum dot TVs can be upward of 20% more energy efficient than conventional LED TV screens. And because quantum dots are such an efficient source of bright light, the amount of light-emitting material in these screens (as low a milligram of cadmium in some models) may actually reduce the overall amount of toxic materials used.</p>
<p>These energy and material savings translate into reduced environmental and health impacts. But are they enough to justify the use of a potentially toxic material? </p>
<p>The company <a href="http://www.qdvision.com/">QD Vision</a> has grappled with precisely this question. In developing quantum dots for products like TCL’s <a href="http://www.qdvision.com/content1657">Quantum Dot TV</a> (debuting at CES this year), the company explicitly adopted an approach to responsible development that considered health and environmental impacts. As a result, in 2014 they won the Presidential Green Chemistry Challenge Award from the US Environmental Protection Agency (EPA).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Coal-fired power plant emissions include cadmium.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/derguy/4586888887">Guy Gorek</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Although it seems counter-intuitive, analysis by the company that was made available to the EPA showed QD Vision’s products lead to a net decrease in environmental cadmium releases compared to conventional TVs. Cadmium is one of the pollutants emitted from coal-fired electrical power plants. Because TVs using the company’s quantum dots use substantially less power than their non-quantum counterparts, the combined cadmium in QD Vision TVs and the power plant emissions associated with their use is actally lower than that associated with conventional flat screen TVs. In other words, using cadmium in quantum dots for production of more energy-efficient displays can actually results in a net reduction in cadmium emissions.</p>
<p>This is a neat trick, and it eloquently demonstrates the dangers of jumping to conclusions over risks without seeing the full picture. It does, however, depend on a commitment to responsible innovation and development that considers future health and environmental impacts.</p>
<p>This week at CES, the future of quantum dot televisions is certainly shining bright. With smart approaches to balancing risks and benefits, there’s no reason why this light shouldn’t continue to shine – as long as manufacturers and consumers keep their eye on the big picture.</p>
<hr>
<p><em>This article has been updated to correct the manufacturer of one quantum dot TV that debuted at CES 2015.</em></p><img src="https://counter.theconversation.com/content/35953/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Maynard receives funding from the National Institute of Environmental Health Sciences. He directs the University of Michigan Risk Science Center, which is partly supported through the Gelman Educational Foundation. </span></em></p>Earlier this week, The Conversation reported that, “The future is bright, the future is … quantum dot televisions.” And judging by the buzz coming from this week’s annual Consumer Electronics Show (CES…Andrew Maynard, Director, Risk Science Center, University of MichiganLicensed as Creative Commons – attribution, no derivatives.