{{Merge to|Heavy metals#Toxicity|discuss=Talk:Toxic heavy metal#Merge proposal|date=March 2026}} {{short description|Harmful effects of certain metals}} {{Use American English|date=April 2025}} {{Use dmy dates|date=November 2025}} {{CS1 config|name-list-style=vanc|display-authors=3}} [[File:M(H2O)6 cation.png|thumb|170px|Structure of a metal aquo complex, a typical soluble form for many metal ions in water]]
'''Metal toxicity''' or '''metal poisoning''' is the toxic effect of certain metals that accumulate damage ecosystems, plants, and animals, including human health.<ref name="jomova">{{cite journal |vauthors=Jomova K, Alomar SY, Nepovimova E, Kuca K, Valko M |date=January 2025 |title=Heavy metals: toxicity and human health effects |journal=Archives of Toxicology |volume=99 |issue=1 |pages=153–209 |bibcode=2025ArTox..99..153J |doi=10.1007/s00204-024-03903-2 |pmc=11742009 |pmid=39567405}}</ref><ref name="fisher">{{cite web |date=27 February 2024 |title=Heavy metals |url=https://www.ncbi.nlm.nih.gov/books/NBK557806/ |access-date=17 April 2025 |publisher=StatPearls, US National Library of Medicine |vauthors=Fisher RM, Gupta V |pmid=32491738}}</ref><ref name="raj">{{cite web |date=23 March 2023 |title=Heavy metal toxicity |url=https://www.ncbi.nlm.nih.gov/books/NBK560920/ |access-date=17 April 2025 |publisher=StatPearls, US National Library of Medicine |vauthors=Rajkumar V, Lee VR, Gupta V |pmid=32809755 }}</ref><ref>{{Cite journal |last1=Gadd |first1=Geoffrey M. |last2=Griffiths |first2=Alan J. |date=1977-12-01 |title=Microorganisms and heavy metal toxicity |journal=Microbial Ecology |language=en |volume=4 |issue=4 |pages=303–317 |doi=10.1007/BF02013274 |pmid=24232222 |bibcode=1977MicEc...4..303G |issn=1432-184X}}</ref> Environmental pollution with heavy metals can result in contamination of drinking water, air, and waterways, accumulating in plants, crops, seafood, and meat.<ref name=raj/> Such pollution may indirectly affect humans via the food chain and through occupational or domestic exposure by inhalation, ingestion, or contact with the skin.<ref name=jomova/><ref name=raj/>
At low concentrations, heavy metals such as copper, iron, manganese, and zinc are essential nutrients obtained through the diet supporting health, but have toxicity at high exposure concentrations.<ref name=fisher/> Other heavy metals having no biological roles in animals, but with potential for toxicity include arsenic, cadmium, lead, mercury, and thallium.<ref name=jomova/><ref name=fisher/><ref>{{cite dictionary |year=2024 |title=Dictionary of Toxicology |publisher=Springer |doi=10.1007/978-981-99-9283-6 |isbn=978-981-99-9282-9 |vauthors=Pant A}}</ref>
Some metals are toxic when they form poisonous soluble compounds which interfere with enzyme systems, such as superoxide dismutase, catalase, or glutathione peroxidase.<ref name=jomova/> Only soluble metal-containing compounds are toxic by forming coordination complexes, which consist of a metal ion surrounded by ligands.<ref name=jomova/> Ligands can range from water in metal aquo complexes to methyl groups, as in tetraethyl lead.
Toxic metal complexes can be detoxified by conversion to insoluble derivatives or by binding them in rigid molecular environments using chelating agents. An option for treatment of metal poisoning may be chelation therapy, which involves the administration of chelation agents to remove metals from the body.<ref name=raj/>
==Sources and site evidence== Heavy metals are found throughout natural ecosystems, including rocks, soils, and water, and originate from diverse sources, such as natural weathering, erosion, mining, industrial and urban runoff, sewage, pesticides on crops, metal pipes carrying potable water, traffic pollution, coal-burning emissions, and various other industrial and urban outputs.<ref name=jomova/><ref name=":7">{{cite journal |last=Musah |first=Baba Imoro |date=2024-12-03 |title=Effects of heavy metals and metalloids on plant-animal interaction and biodiversity of terrestrial ecosystems—an overview |journal=Environmental Monitoring and Assessment |language=en |volume=197 |issue=1 |article-number=12 |doi=10.1007/s10661-024-13490-5 |pmid=39623084 |bibcode=2024EMnAs.197...12M |issn=1573-2959}}</ref><ref name="epa">{{cite web |date=10 March 2025 |title=Metals |url=https://www.epa.gov/caddis/metals |access-date=17 April 2025 |publisher=Causal Analysis and Diagnosis Decision Information System (CADDIS), US Environmental Protection Agency}}</ref><ref>{{Cite journal |last1=Kazlauskaitė-Jadzevičė |first1=Asta |last2=Volungevičius |first2=Jonas |last3=Gregorauskienė |first3=Virginija |last4=Marcinkonis |first4=Saulius |date=2014-12-17 |title=The role of pH in heavy metal contamination of urban soil |url=https://journals.vilniustech.lt/index.php/JEELM/article/view/1829 |journal=Journal of Environmental Engineering and Landscape Management |language=en |volume=22 |issue=4 |pages=311–318 |doi=10.3846/16486897.2013.872117 |issn=1822-4199|doi-access=free |bibcode=2014JEELM..22..311K }}</ref>
Toxic metal particles in ecosystems may remain for hundreds or even thousands of years, with potentially millions of people exposed to high concentrations at some point in their lives.<ref name=epa/> Commonly, there is no visible evidence of metals pollution in soil or water.<ref name=epa/>
When metal toxicity in the environment is suspected, pathologies in fish, clams, birds, insects, and vegetation may serve as signals for contamination and toxicities.<ref name=epa/> Physiological mechanisms of metal toxicity may have a spectrum of effects, ranging from changes in behavior and symptoms of illness, to death of small animal species.<ref name=":7"/><ref name=epa/>
==Occupational exposure==
===Gold mining=== Artisanal small-scale gold miners are at high risk to exposure of metal toxicants.<ref name=":0">{{cite web |date=24 October 2024 |title=Mercury |url=https://www.who.int/news-room/fact-sheets/detail/mercury-and-health |access-date=10 November 2025 |website=World Health Organization |language=en}}</ref> While there is a wide array of hard metals that are toxic, mercury poses the greatest risk from inhalation and ingestion from environmental contamination.<ref name=":4">{{cite book |last1=Crespo-Lopez |first1=Maria Elena |url=https://www.sciencedirect.com/science/chapter/bookseries/abs/pii/S2468748022000030 |title=Advances in Neurotoxicology |last2=Augusto-Oliveira |first2=Marcus |last3=Lopes-Araújo |first3=Amanda |last4=Santos-Sacramento |first4=Letícia |last5=Souza-Monteiro |first5=José Rogério |last6=Farias da Rocha |first6=Felipe |last7=Arrifano |first7=Gabriela de Paula |publisher=Academic Press |year=2022 |isbn=978-0-12-819176-7 |volume=7 |pages=283–314 |language=en-US |chapter=Mercury neurotoxicity in gold miners |doi=10.1016/bs.ant.2022.04.003 |access-date=10 November 2025}}</ref><ref>{{Cite journal |last1=Wu |first1=Yuan-Seng |last2=Osman |first2=Ahmed I. |last3=Hosny |first3=Mohamed |last4=Elgarahy |first4=Ahmed M. |last5=Eltaweil |first5=Abdelazeem S. |last6=Rooney |first6=David W. |last7=Chen |first7=Zhonghao |last8=Rahim |first8=Nur Syafiqah |last9=Sekar |first9=Mahendran |last10=Gopinath |first10=Subash C. B. |last11=Mat Rani |first11=Nur Najihah Izzati |last12=Batumalaie |first12=Kalaivani |last13=Yap |first13=Pow-Seng |date=2024-02-06 |title=The Toxicity of Mercury and Its Chemical Compounds: Molecular Mechanisms and Environmental and Human Health Implications: A Comprehensive Review |journal=ACS Omega |language=en |volume=9 |issue=5 |pages=5100–5126 |doi=10.1021/acsomega.3c07047 |doi-access=free |issn=2470-1343 |pmc=10851382 |pmid=38343989 |bibcode=2024ACSOm...9.5100W }}</ref> thumb|Mercury being mixed with gold-containing materials to extract gold Mercury is commonly used in small scale gold mining. To do this, large amounts of mercury are usually mixed with gold-containing materials to create a gold-mercury alloy called amalgam.<ref name=":1">{{cite web |date=26 August 2015 |title=How People are Exposed to Mercury |url=https://www.epa.gov/mercury/how-people-are-exposed-mercury |access-date=10 November 2025 |website=EPA.gov |language=en}}</ref> To separate the gold, the amalgam is heated in a furnace causing the mercury to vaporize.<ref name=":1"/> During this process, miners are directly exposed to mercury vapors, and surrounding communities may be indirectly exposed through contaminated air, water, and soil.<ref name=":0"/>
Continuous high levels of mercury vapor inhalation can cause a variety of health effects. Inhalation may result in tremors, mood swings, muscle weakness, memory loss, or headaches.<ref name=":4"/><ref name=":1"/> Prolonged exposure can lead to kidney damage, respiratory failure, and even death.<ref name=":5">{{cite web |last=US EPA |first=OCSPP |date=2015-09-03 |title=Health Effects of Exposures to Mercury |url=https://www.epa.gov/mercury/health-effects-exposures-mercury |access-date=2025-11-18 |website=epa.gov |language=en}}</ref> Ingestion of mercury through contaminated water, food, or soil pose great risk to pregnant women and their developing fetuses.<ref name=":0"/> When born, this can impair the infants' cognitive functions, memory, language development, and fine motor skills.<ref name=":5"/>
Despite its widespread use across countries, mercury exposure in artisanal small-scale gold mining is preventable.<ref name=":4"/> Mercury-free techniques like direct smelting result in gold recovery without the need of mercury resulting in the elimination of mercury.<ref name=":6">{{cite web |last=US EPA |first=OITA |date=2015-01-22 |title=Artisanal and Small-Scale Gold Mining Without Mercury |url=https://www.epa.gov/international-cooperation/artisanal-and-small-scale-gold-mining-without-mercury |access-date=2025-11-18 |website=epa.gov |language=en}}</ref> In this method, borax is used to decrease the viscosity and melting temperature of non-gold minerals so they can be easily separated from the gold.<ref name=":6"/> This not only results in improved worker and community health but also lower in cost and eco-friendly.<ref>{{cite journal |last1=Stoffersen |first1=Birgitte |last2=Appel |first2=Peter Wu |last3=Na-Oy |first3=Leoncio D. |last4=Sekamane |first4=Asta Selloane |last5=Ruiz |first5=Ivan Zahinos |last6=Køster-Rasmussen |first6=Rasmus |date=September 2018 |title=Introduction of Mercury-Free Gold Extraction to Small-Scale Miners in the Cabo Delgado Province in Mozambique |journal=Journal of Health and Pollution |volume=8 |issue=19 |article-number=180909 |doi=10.5696/2156-9614-8.19.180909 |issn=2156-9614 |pmc=6257171 |pmid=30524868}}</ref><ref name=":0"/>
===Construction and renovation===
In a 2022 report on workplace lead exposure trends, the US CDC notes that construction is among the top four main industries at risk for lead exposure.<ref>{{Cite web |last=CDC |date=2026-03-02 |title=Workplace Lead Exposure Trends |url=https://www.cdc.gov/niosh/bulletin/2022/lead-trends.html |access-date=2026-04-01 |website=NIOSH Science Bulletin |language=en-us}}</ref> In Ghana, workers who paint or spray/paint have been tested with the highest prevalence of elevated blood lead levels in a study conducted on blood lead levels in high-risk occupational groups.<ref>{{Cite journal |last1=Agyemang |first1=Veronica |last2=Acquaye |first2=Joseph K. |last3=Harrison |first3=Samuel B. E. |last4=Oppong |first4=Felix B. |last5=Gyaase |first5=Stephany |last6=Asante |first6=Kwaku P. |last7=Olayemi |first7=Edeghonghon |date=2020-07-10 |title=Blood Lead Levels among Blood Donors and High-Risk Occupational Groups in a Mining Area in Ghana: Implications for Blood Transfusion among Vulnerable Populations |journal=Journal of Tropical Medicine |language=en |volume=2020 |pages=1–8 |doi=10.1155/2020/6718985 |doi-access=free |issn=1687-9686 |pmc=7368927 |pmid=32695185}}</ref> Amongst different paint usage in Iran, a small study found that car and building painters have elevated blood lead levels, in which car painters had higher blood lead levels than building painters.<ref>{{Cite journal |title=Sage Journals: Discover world-class research |url=https://journals.sagepub.com/action/cookieAbsent |access-date=2026-04-01 |journal=Toxicology and Industrial Health |date=2021 |volume=37 |issue=12 |pages=737–744 |language=en |doi=10.1177/07482337211042731 |pmid=34797729 | vauthors = Ghaffarian-Bahraman A, Taherifard A, Esmaeili A, Ahmadinia H, Rezaeian M |url-access=subscription }}</ref>
===Agricultural workers=== Arsenic exposure remains a major concern in agricultural communities that rely on untreated groundwater for crop irrigation and drinking.<ref>{{Cite journal |last1=Rokonuzzaman |first1=Md |last2=Ye |first2=Zhihong |last3=Wu |first3=Chuan |last4=Li |first4=Wai-Chin |date=2023-03-12 |title=Arsenic Elevated Groundwater Irrigation: Farmers' Perception of Rice and Vegetable Contamination in a Naturally Arsenic Endemic Area |journal=International Journal of Environmental Research and Public Health |language=en |volume=20 |issue=6 |page=4989 |doi=10.3390/ijerph20064989 |doi-access=free |issn=1660-4601 |pmc=10049387 |pmid=36981898}}</ref> Studies have found higher urinary arsenic levels among farm workers exposed to contaminated well water and pesticides.<ref name="Rahman2021">{{cite journal |last1=Rahman |first1=M. M. |last2=Rahman |first2=M. A. |last3=Hossain |first3=A. |last4=Nahar |first4=N. |year=2021 |title=Arsenic exposure among agricultural communities: Sources, health effects, and prevention |journal=Environmental Research |volume=192 |article-number=110257 |doi=10.1016/j.envres.2020.110257|pmid=33031811 |hdl=10261/265868 |hdl-access=free}}</ref>
=== Welders === People who work as welders can be exposed to metal fumes because welding uses extremely high heat, which turns the metal into very small airborne particles.<ref name=":2">{{cite web |title=Controlling Hazardous Fume and Gases during Welding |website=osha.gov |url=https://www.osha.gov/sites/default/files/publications/OSHA_FS-3647_WELDING.pdf |access-date=2025-11-18 |url-status=live |archive-url=https://web.archive.org/web/20250902144948/https://www.osha.gov/sites/default/files/publications/OSHA_FS-3647_Welding.pdf |archive-date=2025-09-02}}</ref> These fumes often contain metals like manganese, chromium, nickel, and lead, depending on the materials being welded.<ref name=":3">{{cite web |last=CDC |date=2025-06-02 |title=Welding Fumes and Manganese |url=https://www.cdc.gov/niosh/welding/about/index.html |access-date=2025-11-18 |website=Welding Fumes and Manganese |language=en-us}}</ref> Breathing in these particles over time can lead to different health issues, including neurological symptoms associated with manganese<ref name=":3"/>and lung irritation from the fumes. Stainless steel welding can also create hexavalent chromium<ref name=":3"/>, which is a known carcinogen.<ref name=":3"/> Exposures to metals are regulated in most countries. In the US, the Occupational Safety and Health Administration (OSHA) sets ''permissible'' exposure limits for metals found in welding fumes, while the National Institute for Occupational Safety and Health (NIOSH) identifies ''recommended'' exposure limits.<ref name=":2"/><ref name=":3"/> Using some industrial hygiene controls such as local exhaust ventilation, fume extraction systems, respirators, and routine air monitoring can help protect welders from harmful metal exposure.<ref name=":2"/> Because welding is widely used in construction and manufacturing and many more occupations, controlling metal fumes is essential for maintaining worker health and safety.
=== Metal Recycling and e-waste === Occupational exposure to PBDEs from e-waste and battery recycling has been found to be a common risk for workers. In southern China, workers have been observed to have high blood PBDE concentrations. E-waste surface dust can also be inhaled as fumes, or dermal contact. Dust particles can become suspended in air, contributing to air pollution, or leach into water and soils.<ref>{{Cite journal |last1=Kumari |first1=Hina |last2=Yadav |first2=Sudesh |date=2023-12-15 |title=A comparative study on metal pollution from surface dust of informal and formal e-waste recycling sectors in national capital region of New Delhi and associated risk assessment |url=https://www.sciencedirect.com/science/article/pii/S0048969723054165 |journal=Science of the Total Environment |volume=904 |article-number=166791 |doi=10.1016/j.scitotenv.2023.166791 |pmid=37678522 |bibcode=2023ScTEn.90466791K |issn=0048-9697}}</ref><ref>{{Cite journal |last1=Qu |first1=Weiyue |last2=Bi |first2=Xinhui |last3=Sheng |first3=Guoying |last4=Lu |first4=Shaoyou |last5=Fu |first5=Jiamo |last6=Yuan |first6=Jing |last7=Li |first7=Liping |date=2007-11-01 |title=Exposure to polybrominated diphenyl ethers among workers at an electronic waste dismantling region in Guangdong, China |url=https://www.sciencedirect.com/science/article/pii/S0160412007001043 |journal=Environment International |volume=33 |issue=8 |pages=1029–1034 |doi=10.1016/j.envint.2007.05.009 |pmid=17618686 |bibcode=2007EnInt..33.1029Q |issn=0160-4120}}</ref> Uncontrolled e-waste handling also poses a hazard to public health, another study has shown that vegetables near e-waste sites have been found to be contaminated with PBDEs.<ref>{{Cite journal |last1=Wang |first1=Yan |last2=Luo |first2=Chunling |last3=Li |first3=Jun |last4=Yin |first4=Hua |last5=Li |first5=Xiangdong |last6=Zhang |first6=Gan |date=2011-10-01 |title=Characterization of PBDEs in soils and vegetations near an e-waste recycling site in South China |url=https://www.sciencedirect.com/science/article/pii/S0269749111003587 |journal=Environmental Pollution |series=Nitrogen Deposition, Critical Loads and Biodiversity |volume=159 |issue=10 |pages=2443–2448 |doi=10.1016/j.envpol.2011.06.030 |pmid=21763040 |bibcode=2011EPoll.159.2443W |issn=0269-7491}}</ref>
==Major types of metal poisoning==
===Arsenic poisoning=== {{Main|Arsenic poisoning}} A dominant kind of metal toxicity is arsenic poisoning, which mainly arises from ground water naturally containing high concentrations of arsenic in the supply of drinking water.<ref name=jomova/><ref name=fisher/>
===Lead poisoning=== {{Main|Lead poisoning}}
Lead poisoning, in contrast to arsenic poisoning, is caused by industrial materials, such as leaded gasoline and lead leached from plumbing.<ref name=jomova/><ref name=fisher/><ref name=raj/> Use of leaded gasoline has declined precipitously since the 1970s.<ref>{{cite book |last1=Carr |first1=Dodd S. |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2000 |isbn=978-3-527-30385-4 |chapter=Lead Compounds |doi=10.1002/14356007.a15_249}}</ref><ref>{{cite web |last1=O'Malley |first1=R. |last2=O'Malley |first2=G. |date=February 2018 |title=Lead Poisoning (Plumbism) |url=https://www.merckmanuals.com/professional/injuries-poisoning/poisoning/lead-poisoning#v1119464 |website=Merck Manual}}</ref>
==Toxicities from metals== {{Periodic table (by nutritional elements)}} Some metal elements are required for life, although they may be toxic in high exposure amounts.<ref name=jomova/><ref name=fisher/><ref name=raj/> Included are cobalt, copper, iron, manganese,<ref name="Couper1837">{{cite journal |last=Couper |first=J. |year=1837 |title=Sur les effets du peroxide de manganèse |url=https://books.google.com/books?id=WpQ3AAAAMAAJ&pg=PA233 |url-status=live |journal=Journal de chimie médicale, de pharmacie et de toxicologie |volume=3 |pages=223–225 |archive-url=https://web.archive.org/web/20140722061529/http://books.google.com/books?id=WpQ3AAAAMAAJ&pg=PA233 |archive-date=22 July 2014}}</ref> selenium,<ref name="ods">{{cite web |date=15 April 2024 |title=Dietary Supplement Fact Sheet: Selenium |url=https://ods.od.nih.gov/factsheets/selenium-HealthProfessional/ |access-date=17 April 2025 |publisher=Office of Dietary Supplements, US National Institutes of Health}}</ref> and zinc.<ref name="Fosmire">{{cite journal |last1=Fosmire |first1=Gary J |year=1990 |title=Zinc toxicity |url=http://www.ajcn.org/cgi/pmidlookup?view=long&pmid=2407097 |journal=The American Journal of Clinical Nutrition |volume=51 |issue=2 |pages=225–7 |doi=10.1093/ajcn/51.2.225 |pmid=2407097 |url-access=subscription}}</ref> Excessive absorption of zinc can suppress copper and iron absorption. The free zinc ion in solution is highly toxic to bacteria, plants, invertebrates, and fish.<ref>{{cite book |last1=Rout |first1=Gyana Ranjan |url=https://archive.org/details/sustainableagric00lich |title=Sustainable Agriculture |last2=Das |first2=Premananda |year=2009 |isbn=978-90-481-2666-8 |editor1-last=Lichtfouse |editor1-first=Eric |pages=[https://archive.org/details/sustainableagric00lich/page/n843 873]–84 |chapter=Effect of Metal Toxicity on Plant Growth and Metabolism: I. Zinc |doi=10.1007/978-90-481-2666-8_53 |id={{INIST|14709198}} |editor2-last=Navarrete |editor2-first=Mireille |editor3-last=Debaeke |editor3-first=Philippe |editor4-last=Véronique |editor4-first=Souchere |editor5-last=Alberola |editor5-first=Caroline |url-access=limited |s2cid=84595949}}</ref>
==Toxicities from nonessential metals== No global mechanism has been identified for the toxicities of these metal ions. Excessive exposure, when it occurs, typically is associated with industrial activities. *Beryllium poisoning is attributed to the ability of Be<sup>2+</sup> to replace Mg<sup>2+</sup> in some enzymes.<ref>{{Greenwood&Earnshaw2nd|page=107}}</ref> Be has been classified by one agency as a carcinogen.<ref>{{cite web |year=1993 |title=IARC Monograph, Volume 58 |url=http://www.inchem.org/documents/iarc/vol58/mono58-1.html |url-status=live |archive-url=https://web.archive.org/web/20120803081509/http://www.inchem.org/documents/iarc/vol58/mono58-1.html |archive-date=3 August 2012 |access-date=18 September 2008 |publisher=International Agency for Research on Cancer}}</ref> *Cadmium poisoning came into focus with the discovery of itai-itai disease due to cadmium-contaminated waters resulting from mining in the Toyama Prefecture starting around 1912.<ref name="icett">ICETT Itai-itai disease (1998) {{cite web |date=1998 |title=Preventative Measures Against Water Pollution |url=http://www.icett.or.jp/lpca_jp.nsf/a21a0d8b94740fbd492567ca000d5879/b30e2e489f4b4ff1492567ca0011ff90?OpenDocument |archive-url=https://web.archive.org/web/20080415154342/http://www.icett.or.jp/lpca_jp.nsf/a21a0d8b94740fbd492567ca000d5879/b30e2e489f4b4ff1492567ca0011ff90?OpenDocument |archive-date=15 April 2008 |access-date=1 May 2008 |website=International Center for Environmental Technology Transfer}}</ref> The term refers to the severe pains ({{langx|ja|痛い|translit=itai}}) people with the condition felt in the spine and joints. Cd<sup>2+</sup> is thought to accumulate in the kidneys, where it tightly binds to the sulfur in cysteine-containing proteins.<ref>{{Greenwood&Earnshaw2nd|page=1225}}</ref> Cadmium is also present as a material used in many electronic devices, thus it can leach into groundwater after being disposed of into landfills of electronic waste.<ref>Arain, A. L., Pummill, R., Adu-Brimpong, J., Becker, S., Green, M., Ilardi, M., Van Dam, E., & Neitzel, R. L. (2020). Analysis of E-waste recycling behavior based on survey at a Midwestern US University. ''Waste Management'', ''105'', 119–127. <nowiki>https://doi.org/10.1016/j.wasman.2020.02.002</nowiki></ref> *Lithium toxicity arises from overdose of lithium-containing drugs.<ref name="Stat2019">{{cite book |last1=Hedya |first1=Shireen A. |title=StatPearls |last2=Avula |first2=Akshay |last3=Swoboda |first3=Henry D. |date=2019 |publisher=StatPearls Publishing |chapter=Lithium Toxicity |pmid=29763168 |access-date=22 December 2019 |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK499992/}}</ref> *Mercury poisoning came into sharp focus with the discovery of Minamata disease, named for the Japanese city of Minamata. In 1956, a factory in the city released methylmercury in the industrial wastewater resulting in thousands of deaths and many other health problems.<ref name="officialnumbers">Official government figure as of March 2001. See [https://www.env.go.jp/en/chemi/hs/minamata2002/ch2.html "Minamata Disease: The History and Measures, ch2"]</ref> This incident alerted the world to the phenomenon of bioaccumulation. While all mercury compounds are toxic, organomercury compounds are especially dangerous because they are more mobile. Methylmercury and related compounds are thought to bind to the sulfur of cysteinyl residues in proteins.<ref>{{Greenwood&Earnshaw2nd|page=1226}}</ref> thumb|right|A 92-year-old Caucasian man (right) with pigmentary changes had used nose drops containing silver for many years. His skin biopsy showed silver deposits in the dermis, confirming the diagnosis of generalized argyria.<ref>{{cite book |last=Fred |first=Herbert |title=Images of Memorable Cases: 50 Years at the Bedside |date=2008 |publisher=Long Tail Press/Rice University Press |isbn=978-0-89263-000-4}}</ref> *Silver poisoning,<ref name="Andrews">{{cite book |last1=James |first1=William D. |url=https://archive.org/details/andrewsdiseasess00mdwi_659 |title=Andrews' diseases of the skin: clinical dermatology |last2=Berger |first2=Timothy G. |last3=Elston |first3=Dirk M. |last4=Odom |first4=Richard B. |publisher=Saunders Elsevier |year=2006 |isbn=0-7216-2921-0 |page=[https://archive.org/details/andrewsdiseasess00mdwi_659/page/n868 858] |oclc=62736861 |url-access=limited}}</ref> like lithium poisoning, arises from misapplication of medications. A dramatic symptom of "argyria" is that the skin turns blue or bluish-grey.<ref>{{cite journal |author=Verena Isak |author2=Tobias Beerli |author3=Antonio Cozzio |author4=Lukas Flatz |date=January–April 2019 |title=A Rare Case of Localized Argyria on the Face |journal=Case Reports in Dermatology |volume=11 |issue=1 |pages=23–27 |doi=10.1159/000494610 |pmc=6477469 |pmid=31043936 |doi-access=free}}</ref> *Thallium poisoning has been observed on several occasions, and it is well known that thallium compounds are highly toxic. Nonetheless, incidents of thallium poisoning are few.<ref>{{cite book |last1=Micke |first1=Heinrich |title=Ullmann's Encyclopedia of Industrial Chemistry |last2=Wolf |first2=Hans Uwe |date=2000 |isbn=3-527-30673-0 |chapter=Thallium and Thallium Compounds |doi=10.1002/14356007.a26_607}}</ref> Tl is located on the periodic table near two other highly toxic metals, mercury and lead. *Tin poisoning from tin metal, its oxides, and its salts are "almost unknown"; on the other hand certain organotin compounds are almost as toxic as cyanide. Such organotin compounds were once widely used as anti-fouling agents.<ref name="Ullmann">{{cite book |last1=Graf |first1=Günter G. |title=Ullmann's Encyclopedia of Industrial Chemistry |publisher=Wiley |year=2000 |isbn=978-3-527-30673-2 |chapter=Tin, Tin Alloys, and Tin Compounds |doi=10.1002/14356007.a27_049}}</ref>
==Treatment for poisoning==
===Chelation therapy=== {{Main|Chelation therapy}}
{{Further|Heavy metal detoxification}} Chelation therapy is a medical procedure that involves the administration of chelating agents to remove or deactivate heavy metals from the body.<ref name=raj/> Chelating agents are molecules that form particularly stable coordination complexes with metal ions.<ref name=raj/> Complexation prevents the metal ions from reacting with molecules in the body, and enable them to be dissolved in blood and eliminated in urine.<ref name=raj/><ref name="toxicfive-4">{{citation |author1=American College of Medical Toxicology |title=Five Things Physicians and Patients Should Question |date=February 2013 |work=Choosing Wisely: an initiative of the ABIM Foundation |url=http://www.choosingwisely.org/doctor-patient-lists/american-college-of-medical-toxicology-and-the-american-academy-of-clinical-toxicology/ |access-date=5 December 2013 |archive-url=https://web.archive.org/web/20131204163006/http://www.choosingwisely.org/doctor-patient-lists/american-college-of-medical-toxicology-and-the-american-academy-of-clinical-toxicology/ |archive-date=4 December 2013 |url-status=live |publisher=American College of Medical Toxicology and American Academy of Clinical Toxicology |author2=American Academy of Clinical Toxicology |author1-link=American College of Medical Toxicology |author2-link=American Academy of Clinical Toxicology}}</ref><ref>{{cite journal |author1=Medical Letter consultants |date=20 September 2010 |title=Nonstandard uses of chelation therapy |url=http://secure.medicalletter.org/w1347c |url-status=live |journal=The Medical Letter on Drugs and Therapeutics |volume=52 |issue=1347 |pages=75–6 |pmid=20847718 |archive-url=https://web.archive.org/web/20140714190248/http://secure.medicalletter.org/w1347c |archive-date=14 July 2014}}</ref><ref>{{cite journal |last1=Kosnett |first1=M J |year=2010 |title=Chelation for Heavy Metals (Arsenic, Lead, and Mercury): Protective or Perilous? |journal=Clinical Pharmacology & Therapeutics |volume=88 |issue=3 |pages=412–415 |doi=10.1038/clpt.2010.132 |issn=0009-9236 |pmid=20664538 |s2cid=28321495}}</ref>
===Other conditions=== It is difficult to differentiate the effects of low level metal poisoning from the environment with other kinds of environmental harms, including nonmetal pollution.<ref name=jomova/> Generally, increased exposure to heavy metals in the environment increases the risks for several diseases.<ref name=jomova/> Despite a lack of evidence to support its use, some people seek chelation therapy to treat a wide variety of conditions such as autism, cardiovascular disease, Alzheimer's disease, or any sort of neurodegeneration.<ref name="toxicfive-4"/>
Alternative medicine practitioners have promoted chelation therapy for autism based on an unsupported hypothesis that autism is a result of heavy metal poisoning. This hypothesis likely emerged from the more specific claim that autism was caused by the preservative thiomersal, which in the past has been used in multi-dose vials of vaccines. Despite extensive study, no connection has been found between vaccines and autism diagnosis rates.<ref>{{cite journal |last1=Price |first1=Cristofer S. |last2=Thompson |first2=William W. |last3=Goodson |first3=Barbara |last4=Weintraub |first4=Eric S. |last5=Croen |first5=Lisa A. |last6=Hinrichsen |first6=Virginia L. |last7=Marcy |first7=Michael |last8=Robertson |first8=Anne |last9=Eriksen |first9=Eileen |last10=Lewis |first10=Edwin |last11=Bernal |first11=Pilar |last12=Shay |first12=David |last13=Davis |first13=Robert L. |last14=DeStefano |first14=Frank |date=1 October 2010 |title=Prenatal and Infant Exposure to Thimerosal From Vaccines and Immunoglobulins and Risk of Autism |url=https://publications.aap.org/pediatrics/article/126/4/656/65633/Prenatal-and-Infant-Exposure-to-Thimerosal-From |journal=Pediatrics |language=en |volume=126 |issue=4 |pages=656–664 |doi=10.1542/peds.2010-0309 |issn=0031-4005 |pmid=20837594 |bibcode=2010Pedia.126..656P |url-access=subscription}}</ref><ref>{{cite journal |last1=Madsen |first1=Kreesten M. |last2=Lauritsen |first2=Marlene B. |last3=Pedersen |first3=Carsten B. |last4=Thorsen |first4=Poul |last5=Plesner |first5=Anne-Marie |last6=Andersen |first6=Peter H. |last7=Mortensen |first7=Preben B. |date=1 September 2003 |title=Thimerosal and the Occurrence of Autism: Negative Ecological Evidence From Danish Population-Based Data |url=https://publications.aap.org/pediatrics/article/112/3/604/28678/Thimerosal-and-the-Occurrence-of-Autism-Negative |journal=Pediatrics |language=en |volume=112 |issue=3 |pages=604–606 |doi=10.1542/peds.112.3.604 |pmid=12949291 |bibcode=2003Pedia.112..604M |issn=0031-4005 |url-access=subscription}}</ref> Despite this lack of evidence, thimerosal was removed from vaccines out of an abundance of caution by 2001; autism diagnosis rates did not decrease in response to the exclusion of thimerosal, disproving the association.<ref>{{cite journal |last1=Schechter |first1=Robert |last2=Grether |first2=Judith K. |date=1 January 2008 |title=Continuing Increases in Autism Reported to California's Developmental Services System: Mercury in Retrograde |url=http://archpsyc.jamanetwork.com/article.aspx?doi=10.1001/archgenpsychiatry.2007.1 |journal=Archives of General Psychiatry |language=en |volume=65 |issue=1 |pages=19–24 |doi=10.1001/archgenpsychiatry.2007.1 |issn=0003-990X |pmid=18180424 |url-access=subscription}}</ref><ref>{{cite journal |last=Fombonne |first=Eric |date=1 January 2008 |title=Thimerosal Disappears but Autism Remains |url=http://archpsyc.jamanetwork.com/article.aspx?doi=10.1001/archgenpsychiatry.2007.2 |journal=Archives of General Psychiatry |language=en |volume=65 |issue=1 |pages=15–16 |doi=10.1001/archgenpsychiatry.2007.2 |issn=0003-990X |pmid=18180423 |url-access=subscription}}</ref> Regardless of the removal of thimerosal and the evidence that it never influenced autism in the first place, the idea of heavy metal exposure causing autism has persisted, and thus has the use of chelation therapy as treatment. Systematic reviews of available evidence do not support the use of chelation therapy for autism,<ref>{{cite journal |last1=Sinha |first1=Yashwant |last2=Silove |first2=Natalie |last3=Williams |first3=Katrina |date=7 October 2006 |title=Chelation therapy and autism |journal=BMJ |language=en |volume=333 |issue=7571 |pages=756.1 |doi=10.1136/bmj.333.7571.756 |issn=0959-8138 |pmc=1592402 |pmid=17023484}}</ref><ref>{{cite journal |last=Brent |first=Jeffrey |date=1 December 2013 |title=Commentary on the Abuse of Metal Chelation Therapy in Patients with Autism Spectrum Disorders |journal=Journal of Medical Toxicology |language=en |volume=9 |issue=4 |pages=370–372 |doi=10.1007/s13181-013-0345-4 |issn=1937-6995 |pmc=3846967 |pmid=24113859}}</ref> and at least one child has died due to errors in administration of chelation therapy for this purpose.<ref>{{cite web |date=25 August 2005 |title=Boy with autism dies after chelation therapy |url=https://www.nbcnews.com/id/wbna9074208 |access-date=16 April 2025 |website=NBC News |language=en |agency=Associated Press}}</ref><ref>{{cite journal |last1=Baxter |first1=Arla J. |last2=Krenzelok |first2=Edward P. |date=January 2008 |title=Pediatric fatality secondary to EDTA chelation |url=http://www.tandfonline.com/doi/full/10.1080/15563650701261488 |journal=Clinical Toxicology |language=en |volume=46 |issue=10 |pages=1083–1084 |doi=10.1080/15563650701261488 |issn=1556-3650 |pmid=18949650 |url-access=subscription}}</ref><ref>{{cite web |last=Offit |first=Paul |date=31 August 2005 |title=Death of an Autistic Child From Chelation Therapy - Op-ed |url=https://www.chop.edu/news/death-autistic-child-chelation-therapy-oped |access-date=16 April 2025 |website=Children's Hospital of Philadelphia |language=en}}</ref>
==References== {{Reflist}}
==External links== * [https://sites.dartmouth.edu/toxmetal/ Dartmouth Toxic Metals Superfund Research Program] * [https://www.osha.gov/toxic-metals Toxic Metals] (OSHA)
{{Poisoning and toxicity}} {{Elements in biology}}
Category:Toxic effects of metals Category:Element toxicology Category:Metals Category:Toxicology