Editing Arsenic poisoning (section)

==Causes==
Arsenic poisoning is caused by incidental ingestion or inhalation of arsenic, typically from drinking contaminated [[well]] water, eating food cooked in contaminated water, or being exposed to arsenic-containing pesticides, folk medicines, or industrial chemicals.<ref name=Mahajan2020/> The [[World Health Organization]] considers arsenic levels above 10 [[parts per billion]] (10 [[microgram]]s per [[liter]]) to be unsafe.<ref name=Martinez2021/>

=== Sources ===
Because of its high toxicity, arsenic is seldom used in the Western world, although in Asia it is still a popular pesticide. Arsenic is mainly encountered occupationally in the smelting of zinc and copper ores.

====Groundwater====
{{See also|Arsenic contamination of groundwater}}
Arsenic is a ubiquitous naturally occurring [[chemical element]], and the 20th most common element on Earth.<ref name=Gupta2017>{{cite book|chapter=Arsenic Contamination from Historical Aspects to the Present |vauthors=Gupta DK, Tiwari S, Razafindrabe BH, Chatterjee S |publisher=Springer |date=2017 |doi=10.1007/978-3-319-54356-7_1 |title=Arsenic Contamination in the Environment: The Issues and Solutions |pages=1–12 |isbn=978-3-319-54354-3 |veditors = Gupta DK, Chatterjee S}}</ref> Arsenic levels in the groundwater vary from around 0.5 parts per billion to 5000 parts per billion, depending on an area's geologic features, and possible presence on industrial waste.<ref name=Gupta2017/><ref name=Chen2021>{{cite journal |vauthors=Chen QY, Costa M |title=Arsenic: A Global Environmental Challenge |journal=Annu Rev Pharmacol Toxicol |volume=61 |issue= |pages=47–63 |date=January 2021 |pmid=33411580 |doi=10.1146/annurev-pharmtox-030220-013418 |url=|doi-access=free }}</ref> The highest groundwater arsenic levels have been recorded in Brazil, Cambodia, Afghanistan, Australia, and [[Water supply and sanitation in Bangladesh#Arsenic contamination of groundwater|Bangladesh]].<ref name=Chen2021/>

Arsenic is a ubiquitous element present in American drinking water.<ref>{{cite web|url=http://water.usgs.gov/nawqa/trace/arsenic/|title=USGS NAWQA Arsenic in Groundwater|url-status=live|archive-url=https://web.archive.org/web/20100531210457/http://water.usgs.gov/nawqa/trace/arsenic/|archive-date=2010-05-31}}</ref>  In the US, the [[United States Geological Survey|U.S. Geological Survey]] estimates that the median groundwater concentration is 1&nbsp;μg/L or less, although some groundwater [[aquifer]]s, particularly in the western United States, can contain much higher levels. For example, median levels in Nevada were about 8&nbsp;μg/L<ref>{{cite web|last1=Ryker|first1=Welch|title=Arsenic in Ground-Water Resources of the United States: A New National-Scale Analysis|url=https://wwwbrr.cr.usgs.gov/projects/GWC_chemtherm/FinalAbsPDF/ryker.pdf}}</ref> but levels of naturally occurring arsenic as high as 1000&nbsp;μg/L have been measured in the United States in drinking water.<ref>{{cite journal|last1=D R|first1=Lewis|title=Drinking water arsenic in Utah: A cohort mortality study.|journal=Environmental Health Perspectives|volume=107|issue=5|pages=359–365|pmc=1566417|year=1999|pmid=10210691|doi=10.1289/ehp.99107359|bibcode=1999EnvHP.107..359L }}</ref> Groundwater associated with volcanics in California contain As at concentrations ranging up to 48,000 μg/L, with As-bearing sulfide minerals as the main source.<ref>{{cite journal|last1=Welch|first1=Alan H.|last2=Lico|first2=Michael S.|last3=Hughes|first3=Jennifer L.|title=Arsenic in Ground Water of the Western United States|journal=Ground Water|date=1 May 1988|volume=26|issue=3|pages=333–347|doi=10.1111/j.1745-6584.1988.tb00397.x|bibcode=1988GrWat..26..333W |language=en|issn=1745-6584}}</ref> Geothermal waters on Dominica in the Lesser Antilles also contain concentrations of As >50 μg/L.<ref>{{cite journal|last1=Breuer|first1=Christian|last2=Pichler|first2=Thomas|title=Arsenic in marine hydrothermal fluids|journal=Chemical Geology|date=1 June 2013|volume=348|pages=2–14|doi=10.1016/j.chemgeo.2012.10.044|url=https://www.researchgate.net/publication/256681266|bibcode=2013ChGeo.348....2B}}</ref> In Wisconsin, As concentrations of water in sandstone and dolomite aquifers were as high as 100&nbsp;μg/L. Oxidation of pyrite hosted by these formations was the likely source of the As.<ref>{{cite journal|last1=Thornburg|first1=Katie|last2=Sahai|first2=Nita|title=Arsenic occurrence, mobility, and retardation in sandstone and dolomite formations of the Fox River Valley, Eastern Wisconsin|pmid=15506203|journal=Environmental Science & Technology|volume=38|issue=19|pages=5087–5094|date=1 October 2004|doi=10.1021/es049968b|bibcode=2004EnST...38.5087T}}</ref> In the Piedmont of Pennsylvania and New Jersey, groundwater in [[Mesozoic]] age aquifers contains elevated levels of As—domestic well waters from Pennsylvania contained up to 65&nbsp;μg/L,<ref>{{cite journal|last1=Peters|first1=Stephen C.|last2=Burkert|first2=Lori|title=The occurrence and geochemistry of arsenic in groundwaters of the Newark basin of Pennsylvania|journal=Applied Geochemistry|date=January 2008|volume=23|issue=1|pages=85–98|doi=10.1016/j.apgeochem.2007.10.008|bibcode=2008ApGC...23...85P}}</ref> whereas in New Jersey the highest concentration measured recently was 215&nbsp;μg/L.<ref>{{cite journal|last1=E. Serfes|first1=Michael|last2=Herman|first2=Gregory|last3=E. Spayd|first3=Steven|last4=Reinfelder|first4=John|title=Sources, mobilization and transport of arsenic in groundwater in the Passaic and Lockatong Formations of the Newark Basin, New Jersey|journal=N J Geol Soc Bull|date=1 January 2010|volume=77|pages=E1–E40|url=https://www.researchgate.net/publication/270273467}}</ref>

====Rice and Seafood====
Organic arsenic is less harmful than inorganic arsenic. Seafood is a common source of the less toxic organic arsenic in the form of [[arsenobetaine]].<ref name=EFSA2009>{{cite journal|title=Scientific Opinion on Arsenic in Food|journal=EFSA Journal|date=22 October 2009|volume=7|issue=10|pages=1351|doi=10.2903/j.efsa.2009.1351|url=http://www.efsa.europa.eu/en/efsajournal/pub/1351|access-date=22 November 2012|author=EFSA Panel on Contaminants in the Food Chain (CONTAM)|doi-access=free}}</ref>

In the United States, Schoof et al. estimated an average adult intake of 3.2&nbsp;μg/day, with a range of 1–20&nbsp;μg/day.<ref>{{cite journal|last1 = Schoof|first1 = R. A.|last2 = Yost|first2 = L. J.|display-authors = etal|date = Aug 1999|title = A market basket survey of inorganic arsenic in food|journal = [[Food Chem. Toxicol.]]|volume = 37|issue = 8|pages = 839–846|doi = 10.1016/S0278-6915(99)00073-3|pmid = 10506007}}</ref> Estimates for children were similar.<ref name="YostTao2004">{{cite journal|last1 = Yost|first1 = L. J.|last2 = Tao|first2 = S.-H.|display-authors = etal|date = 2004|title = Estimation of dietary intake of inorganic arsenic in U.S. children|journal = [[Hum. Ecol. Risk Assess.]]|volume = 10|issue = 3|pages = 473–483|doi = 10.1080/10807030490452151| bibcode=2004HERA...10..473Y |s2cid = 36682079}}</ref> Food also contains many organic arsenic compounds. The key organic arsenic compounds that can be routinely found in food (depending on food type) include monomethylarsonic acid (MMAsV), dimethylarsinic acid (DMAsV), arsenobetaine, arsenocholine, arsenosugars, and arsenolipids. DMAsV or MMAsV can be found in various types of fin fish, crabs, and mollusks, but often at very low levels.<ref>{{cite journal|last1=Hosgood|first1=Borak|title=Seafood arsenic: implications for human risk assessment|journal=[[Regulatory Toxicology and Pharmacology]]|volume=47|issue=2|pages=204–12|pmid=17092619|year=2007|doi=10.1016/j.yrtph.2006.09.005}}</ref>

Arsenobetaine is the major form of arsenic in marine animals, and is considered nontoxic. Arsenocholine, which is mainly found in shrimp, is chemically similar to arsenobetaine, and is considered to be "essentially nontoxic".<ref>{{cite web|title=Toxicological Profile for Arsenic|date=27 July 2021|url=https://www.atsdr.cdc.gov/toxprofiles/TP.asp?id=22&tid=3|access-date=30 March 2018|archive-date=25 January 2018|archive-url=https://web.archive.org/web/20180125173856/https://www.atsdr.cdc.gov/toxprofiles/TP.asp?id=22&tid=3|url-status=dead}}</ref> Although arsenobetaine is little studied, available information indicates it is not mutagenic, immunotoxic, or embryotoxic.<ref>{{cite journal|last1=Borak J|first1=Hosgood HD.|title=Seafood arsenic: implications for human risk assessment|journal=Regulatory Toxicology and Pharmacology|volume=47|issue=2|pages=204–12|pmid=17092619|year=2007|doi=10.1016/j.yrtph.2006.09.005}}</ref> Arsenosugars and arsenolipids have recently been identified. Exposure to these compounds and toxicological implications are currently being studied. Arsenosugars are detected mainly in seaweed but are also found to a lesser extent in marine mollusks.<ref>{{cite journal|author = CONTAM|date = Oct 2009|title = Scientific opinion on arsenic in food|journal = EFSA J.|volume = 7|issue = 10|pages = 1351|doi = 10.2903/j.efsa.2009.1351|doi-access = free}}</ref> Studies addressing arsenosugar toxicity, however, have largely been limited to in vitro studies, which show that arsenosugars are significantly less toxic than both inorganic arsenic and trivalent methylated arsenic metabolites.<ref>{{cite journal|last = Fujiwara|first = S.|display-authors = etal|date = Jan 2000|title = Isolation and characterization of arsenate-sensitive and resistant mutants of Chlamydomonas reinhardtii|journal = Plant Cell Physiol.|volume = 41|issue = 1|pages = 77–83|doi = 10.1093/pcp/41.1.77|pmid = 10750711|doi-access = free}}</ref>

It has been found that rice is particularly susceptible to accumulation of arsenic from soil.<ref>{{cite news|title=Do you need to worry about arsenic in rice?|last=Kotz|first=Deborah|url=http://bostonglobe.com/lifestyle/health-wellness/2011/12/08/you-need-worry-about-arsenic-rice/KGsMAwBoe0NnYupiC68v9N/story.html|newspaper=Boston Globe|date=December 8, 2011|access-date=December 8, 2011|url-status=live|archive-url=https://web.archive.org/web/20120415015618/http://bostonglobe.com/lifestyle/health-wellness/2011/12/08/you-need-worry-about-arsenic-rice/KGsMAwBoe0NnYupiC68v9N/story.html|archive-date=April 15, 2012}}</ref>  Rice grown in the United States has an average 260&nbsp;[[Parts-per notation|ppb]] of arsenic, according to a study; but U.S. arsenic intake remains far below [[World Health Organization]]-recommended limits.<ref>{{cite web | url = http://www.speciation.net/News/Surprisingly-high-concentrations-of-toxic-arsenic-species-found-in-US-rice-;~/2005/08/03/1561.html | title = Surprisingly high concentrations of toxic arsenic species found in U.S. rice | url-status = live | archive-url = https://web.archive.org/web/20110724081546/http://www.speciation.net/News/Surprisingly-high-concentrations-of-toxic-arsenic-species-found-in-US-rice-%3B~/2005/08/03/1561.html | archive-date = 2011-07-24 }}</ref>  China has set a standard for arsenic limits in food (150&nbsp;ppb),<ref>{{cite web | url = http://medicalxpress.com/news/2011-12-rice-source-arsenic-exposure.html | title = Rice as a source of arsenic exposure | url-status = live | archive-url = https://web.archive.org/web/20140110085539/http://medicalxpress.com/news/2011-12-rice-source-arsenic-exposure.html | archive-date = 2014-01-10 }}</ref> as levels in rice exceed those in water.<ref>{{cite web | url = http://www.speciation.net/News/China-Inorganic-Arsenic-in-Rice--An-Underestimated-Health-Threat--;~/2010/05/19/5027.html | title = China: Inorganic Arsenic in Rice – An Underestimated Health Threat? | url-status = live | archive-url = https://web.archive.org/web/20110724081531/http://www.speciation.net/News/China-Inorganic-Arsenic-in-Rice--An-Underestimated-Health-Threat--%3B~/2010/05/19/5027.html | archive-date = 2011-07-24 }}</ref>

====Air====
The European Commission (2000) reports that levels of arsenic in air range 0–1&nbsp;ng/m<sup>3</sup> in remote areas, 0.2–1.5&nbsp;ng/m<sup>3</sup> in rural areas, 0.5–3&nbsp;ng/m<sup>3</sup> in urban areas, and up to about 50&nbsp;ng/m<sup>3</sup> in the vicinity of industrial sites. Based on these data, the European Commission (2000) estimated that in relation to food, cigarette smoking, water, and soil, air contributes less than 1% of total arsenic exposure.{{Better source needed|date=February 2023|reason=no link and somewhat outdated}}

====Pesticides====
The use of lead arsenate pesticides has been effectively eliminated for over 50 years. However, because of the pesticide's environmental persistence, it is estimated that millions of acres of land are still contaminated with lead arsenate residues. This presents a potentially significant public health concern in some areas of the United States (e.g., New Jersey, Washington, and Wisconsin), where large areas of land used historically as orchards have been converted into residential developments.<ref>{{cite journal|last1=Hood|first1=E|title=The apple bites back: claiming old orchards for residential development|journal=Environmental Health Perspectives|date=August 2006|volume=114|issue=8|pages=A470–6|pmid=16882511|pmc=1551991|doi=10.1289/ehp.114-a470}}</ref>

Some modern uses of arsenic-based pesticides still exist. Chromated copper arsenate has been registered for use in the United States since the 1940s as a wood preservative, protecting wood from insects and microbial agents. In 2003, manufacturers of chromated copper arsenate instituted a voluntary recall of residential uses of wood treated with the chemical. The Environmental Protection Agency Act 2008 final report stated that chromated copper arsenate is still approved for use in nonresidential applications, such as in marine facilities (pilings and structures), utility poles, and sand highway structures.

====Copper smelting====
Exposure studies in the copper [[smelting]] industry are much more extensive and have established definitive links between arsenic, a by-product of copper smelting, and lung cancer via inhalation.<ref>{{cite journal|last1=Enterline|first1=P. E.|last2=Day|first2=R.|last3=Marsh|first3=G. M.|title=Cancers related to exposure to arsenic at a copper smelter|journal=Occupational and Environmental Medicine|volume=52|issue=1|pages=28–32|language=en|doi=10.1136/oem.52.1.28|pmid=7697137|pmc=1128146|date=1 January 1995}}</ref> Dermal and neurological effects were also increased in some of these studies.<ref>{{cite journal|last1=Lagerkvist|first1=B. J.|last2=Zetterlund|first2=B.|title=Assessment of exposure to arsenic among smelter workers: a five-year follow-up|pmid=7516623|journal=American Journal of Industrial Medicine|volume=25|issue=4|pages=477–488|year=1994|doi=10.1002/ajim.4700250403}}</ref> Although as time went on, occupational controls became more stringent and workers were exposed to reduced arsenic concentrations, the arsenic exposures measured from these studies ranged from about 0.05 to 0.3&nbsp;mg/m<sup>3</sup> and are significantly higher than airborne environmental exposures to arsenic (which range from 0 to 0.000003&nbsp;mg/m<sup>3</sup>).<ref>{{cite web|title=ATSDR – Toxicological Profile: Arsenic|url=https://www.atsdr.cdc.gov/toxprofiles/TP.asp?id=22&tid=3|website=www.atsdr.cdc.gov|date=27 July 2021|language=en|access-date=30 March 2018|archive-date=25 January 2018|archive-url=https://web.archive.org/web/20180125173856/https://www.atsdr.cdc.gov/toxprofiles/TP.asp?id=22&tid=3|url-status=dead}}</ref>