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{{Infobox arsenic}}
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'''Arsenic''' ({{IPAc-en|icon|ˈ|ɑr|s|ən|ɪ|k}} {{respell|ARS|ə-nik}}, also {{IPAc-en|ɑr|ˈ|s|ɛ|n|ɪ|k}} {{respell|ar|SEN|ik}} when attributive) is the [[chemical element]] that has the symbol ''As'', [[atomic number]] 33 and [[atomic mass]] 74.92. Arsenic was first documented by [[Albertus Magnus]] in 1250.<ref name="BuildingBlocks451-3">{{cite book |last=Emsley |first=John |title=Nature's Building Blocks: An A-Z Guide to the Elements |year=2001 |isbn=0-19-850341-5|pages=43,513,529 |publisher=[[Oxford University Press]] |location=Oxford}}</ref> Arsenic is a notoriously poisonous [[metalloid]]. It can exists in various [[allotropy|allotropes]], although only the grey form is important in a technical sense.  Arsenic occurs in many minerals, mainly associated with sulfur and metals.  Arsenic and its compounds are mainly used as an alloying agent for lead batteries, but historically it was widely used as [[pesticides]], [[herbicide]]s, [[insecticide]]s, but these applications are declining.<ref name=Ullmann>Sabina C. Grund, Kunibert Hanusch, Hans Uwe Wolf "Arsenic and Arsenic Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, VCH-Wiley, 2008, Weinheim.{{DOI|10.1002/14356007.a03_113.pub2}}</ref>  The occurrence of arsenic in drinking water is problematic in some parts of the world.

==Characteristics==
===Physical characteristics=== 
The most common allotrope of arsenic is ''grey arsenic''. It adopts a layered structure, a ruffled analogue of [[graphite]], consisting of many interlocked six-membered rings. Each atom is bound to three other atoms in the layer and is coordinated by each 3 arsenic atoms in the upper and lower layer. This relatively close packing leads to a high density of 5.73&nbsp;g/cm<sup>3</sup>.<ref name="Holl"/>  It is a [[semiconductor]] and is soft ([[mohs scale]] = 3.5).

====Allotropes====
[[Image:White phosphrous molecule.jpg|left|thumb|100px| Structure of yellow arsenic As<sub>4</sub> and white [[phosphorus]] P<sub>4</sub>]] 
Like phosphorus, arsenic exhibits [[allotropy]], although only the gray allotrope is important under normal conditions. The three most common allotropes are ''metallic grey'', ''yellow'' and ''black arsenic''.<ref>{{cite book|title = Chemistry of Arsenic, Antimony and Bismuth|first = Nicholas C|last = Norman|publisher = Springer|year = 1998|isbn = 9780751403893|url = http://books.google.com/?id=vVhpurkfeN4C|pages = 50}}</ref>''Yellow arsenic'' ({{chem|As|4}}) is soft and waxy, somewhat similar to {{chem|P|4}}. Both have four atoms arranged in a [[tetrahedral]] structure in which each atom is bound to each of the other three atoms by a single bond. This unstable allotrope, being molecular, is the most volatile, least [[Density|dense]], and most toxic. Yellow arsenic is produced by rapid cooling of arsenic vapour, for example with liquid nitrogen. It is rapidly transformed into the grey arsenic by light. The yellow form has a density of 1.97 g/cm<sup>3</sup>.<ref name="Holl"/>

''Black arsenic'' is similar in structure to red phosphorus.<ref name="Holl"/><!--10.1002/jlac.18440490302 Ueber Allotropie bei einfachen Körpern, als eine der Ursachen der Isomerie bei ihren Verbindungen (pp. 247–264)
Jac. Berzelius Volume 49 Issue 3, Pages 247–366 (1844) Justus Liebigs Annalen der Chemie
10.1002/jlac.18671440115
10.1002/jlac.19134000206
10.1002/zaac.19020320158
10.1002/zaac.18940060139
10.1002/cber.19080410197
10.1002/zaac.18940060139
-->
Three metalloidal forms of arsenic, each with a different structure, are found free in nature (the minerals arsenic ''[[sensu stricto]]'' and the much rarer arsenolamprite and pararsenolamprite).

===Chemical properties===
When heated in air, arsenic [[oxidation|oxidizes]] to arsenic trioxide; the fumes from this reaction have an odour resembling [[garlic]]. This odour can be detected on striking arsenide minerals such as [[arsenopyrite]] with a hammer. Arsenic (and some arsenic compounds) [[sublimation (chemistry)|sublimes]] upon heating at atmospheric pressure, converting directly to a gaseous form without an intervening liquid state. The liquid state appears at 20 atmospheres and above, which explains why the melting point is higher than the boiling point.<ref name="Holl"/>

===Isotopes===
{{Main|Isotopes of arsenic}}
Naturally occurring arsenic is composed of one stable [[isotope]], <sup>75</sup>As.<ref name="NUBASE">{{cite journal| first = Audi| last = Georges|title = The NUBASE Evaluation of Nuclear and Decay Properties| journal = Nuclear Physics A| volume = 729| pages = 3–128| publisher = Atomic Mass Data Center| year = 2003| doi=10.1016/j.nuclphysa.2003.11.001}}</ref> As of 2003, at least 33 [[radioisotope]]s have also been synthesized, ranging in [[atomic mass]] from 60 to 92. The most stable of these is <sup>73</sup>As with a [[half-life]] of 80.3&nbsp;days. Isotopes that are lighter than the stable <sup>75</sup>As tend to decay by [[beta decay|β<sup>+</sup> decay]], and those that are heavier tend to decay by [[beta decay|β<sup>-</sup> decay]], with some exceptions.

At least 10 [[nuclear isomer]]s have been described, ranging in atomic mass from 66 to 84. The most stable of arsenic's isomers is <sup>68m</sup>As with a half-life of 111&nbsp;seconds.<ref name="NUBASE"/>

===Occurrence===
{{See also|:Category:Arsenide minerals|l1=Arsenide minerals|:Category:Arsenate minerals|l2=Arsenate minerals}}
[[Image:Native arsenic.jpg|left|200px|thumb|A large sample of native arsenic.]]

[[Mineral]]s with the formula MAsS and MAs<sub>2</sub> (M = Fe, Ni, Co) are the dominant commercial sources of arsenic together with realgar and native As. An illustrative mineral is [[Arsenopyrite]]<!--, also unofficially called mispickel,<ref>{{cite journal|journal = Geology Today|volume = 18|issue = 2|pages = 72–75|title = Minerals explained 35: Arsenopyrite|first =R. J.|last = King|year = 2002|doi = 10.1046/j.1365-2451.2002.t01-1-00006.x}}</ref>--> ([[iron|Fe]]As[[sulfur|S]]), which is structurally related to [[iron pyrite]].  [[Image:Mineraly.sk - realgar.jpg|thumb|Realgar]].  Otherwise many minor As-containing minerals are known.

In addition to the inorganic forms mentioned above, arsenic also occurs in various organic forms in the environment.<ref name="geosphere">{{cite journal|journal = The Science of the Total Environment|volume = 249|issues = 1–3|year = 2000|pages = 297–312| doi = 10.1016/S0048-9697(99)00524-0|title = Arsenic in the geosphere — a review|first = Jörg|last = Matschullat|pmid = 10813460|issue = 1-3}}</ref>

Other naturally occurring pathways of exposure include volcanic ash, weathering of the arsenic-containing mineral and ores as well as groundwater. It is also found in food, water, soil and air.<ref>{{cite web | url = http://www.atsdr.cdc.gov/HEC/CSEM/arsenic/docs/arsenic.pdf | title = Case Studies in Environmental Medicine (CSEM) Arsenic Toxicity Exposure Pathways. | publisher = Agency for Toxic Substances & Disease Registry | accessdate = 2010-05-15}}</ref>  The most common pathway of exposure for humans is ingestion, and the predominant source of arsenic in our diet is through seafood.<ref name="atsdr.cdc.gov">The Agency for Toxic Substances and Disease Registry (2009). Retrieved at http://www.atsdr.cdc.gov/</ref>

==Production==
[[Image:World Arsenic Production 2006.svg‎|thumb|250px|Arsenic output in 2006<ref name="USGSCS2006">{{cite web|url = http://minerals.er.usgs.gov/minerals/pubs/commodity/arsenic/mcs-2008-arsen.pdf|first = William E.|last = Brooks| publisher = United States Geological Survey|accessdate = 2008-11-25|title = Mineral Commodity Summaries 2007: Arsenic}}</ref>]]
In 2005, China was the top producer of white arsenic with almost 50% world share, followed by Chile, Peru and Morocco, reports the [[British Geological Survey]] and the [[United States Geological Survey]].<ref name ="USGSCS2006"/> Most operations in the US and Europe closed for environmental reasons.  The arsenic is recovered mainly as a side product from the purification of copper. Arsenic is part of the smelter dust from copper, gold, and lead smelters.<ref name=USGSYB2007/>

On roasting in air of arsenopyrite, arsenic sublimes as arsenic(III) oxide leaving iron oxides,<ref name="geosphere"/> while roasting without air results in the production of metallic arsenic. Further purification from sulfur and other chalcogens is achieved by sublimation in vacuum or in a hydrogen atmosphere or by distillation from molten lead-arsenic mixture.<ref>{{cite journal|title = Separation of Sulfur, Selenium, and Tellurium from Arsenic|journal = Journal of the Electrochemical Society|volume = 107|issue = 12|pages = 982–985|year = 1960|first = J. M.|last = Whelan|doi = 10.1149/1.2427585|last2 = Struthers|first2 = J. D.|last3 = Ditzenberger|first3 = J. A.}}</ref><!-- 10.1023/A:1012370808738-->

==Compounds of arsenic==
{{See also cat|Arsenic compounds}}
Arsenic compounds resemble in some respects those of [[phosphorus]], which occupies the same group (column) of the [[periodic table]].  Arsenic is less commonly observed in the pentavalent state, however.  The most common [[oxidation state]]s for arsenic are −3 ([[arsenide]]s,  such as alloy-like intermetallic compounds, +3 in arsenates(III) ([[arsenite]]s) and most organoarsenic compounds). Arsenic also bonds readily to itself as seen in the square As{{su|b=4|p=3−}} ions in the mineral [[skutterudite]]. In the +3 oxidation state, arsenic is typically pyramindal, owing to the influence of the [[lone pair]] of [[electrons]].

===Oxides===
Arsenic forms colourless, odourless, crystalline oxides [[Arsenic trioxide|As<sub>2</sub>O<sub>3</sub>]] ("[[white arsenic]]") and [[Arsenic pentoxide|As<sub>2</sub>O<sub>5</sub>]] which are [[hygroscopic]] and readily soluble in water to form acidic solutions. [[Arsenic acid|Arsenic(V) acid]] is a weak acid. Its salts are called ([[arsenate]]s, e.g. [[Paris Green]], [[calcium arsenate]], and [[lead hydrogen arsenate]]. The latter three have been used as [[agriculture|agricultural]] [[insecticide]]s and [[poison]]s.  The protonation steps between the arsenate and arsenic acid are similar to those between [[phosphate]] and [[phosphoric acid]]. However, arsenite and [[arsenous acid]] contain arsenic bonded to three oxygen and not hydrogen atoms, in contrast to [[phosphite]] and [[phosphorous acid]] (more accurately termed 'phosphonic acid'), which contains a non-acidic P-H bond. Arsenous acid is genuinely tribasic, whereas phosphonic acid is not.

===Sulfides and related derivatives===
A broad variety of sulfur compounds of arsenic are known.  Orpiment (As<sub>2</sub>S<sub>3</sub>, [[arsenic trisulfide|As<sub>2</sub>S<sub>3</sub>]]) and realgar ([[tetraarsenic tetrasulfide|As<sub>4</sub>S<sub>4</sub>]], As<sub>4</sub>S<sub>4</sub>) are somewhat abundant and were formerly used as painting pigments.  Other sulfides include [[tetraarsenic trisulfide|As<sub>4</sub>S<sub>3</sub>]] and  and As<sub>4</sub>S<sub>10</sub>. Arsenic has a formal oxidation state of +2 in As<sub>4</sub>S<sub>4</sub>]], which features As-As bonds so that the total covalency of As is still in fact three.<ref>{{cite web|url=http://www.webelements.com/webelements/compounds/text/As/As4S4-12279902.html|title=Arsenic: arsenic(II) sulfide compound data|accessdate=2007-12-10|publisher=WebElements.com}}</ref>

===Halides===
The trifloride, trichloride, tribromide, and triiodide of arsenic(III) are well known, whereas only AsF<sub>5</sub> is the main pentahalide. [[Arsenic pentafluoride]] is stable at room temperature, whereas the [[Arsenic pentachloride|pentachloride]] is only stable below −50&nbsp;°C.<ref name="Holl"/>

===Alloys===
Arsenic is used as group 5 element as components of the [[III-V semiconductor]]s. [[Gallium arsenide]], [[indium arsenide]] and [[aluminium arsenide]] are used as semiconductor materials.  The valence electron count of GaAs is the same as a pair of Si atoms but the band structure is completely different, which results distinct bulk properties. Other arsenic alloys include [[cadmium arsenide]], [[gallium arsenide]].

===Organoarsenic compounds===
{{Main|organoarsenic chemistry}}
[[Image:Trimethylarsine-2D.png|left| thumb| Trimethylarsine]]
A large variety of organoarsenic compounds are known.  Many were initially prepared for use in chemical warfare during World War I.  Representative compounds have the formulae R<sub>3-x</sub>AsCl<sub>x</sub> (where R = alkyl and aryl, and x = 0,1,2).  Cacodylic acid which is of historic and practical interest, arises from the methylation of arsenic trioxide, a reaction that has no analogy in phosphorus chemistry.

==History==
The word ''arsenic'' was borrowed from the [[Syriac language|Syriac]] word ܠܐ ܙܐܦܢܝܐ ''(al) zarniqa'' <ref name="etymonline.com">{{cite web | url = http://www.etymonline.com/index.php?term=arsenic | title = arsenic  | accessdate = 2010-05-15| publisher = Online Etymology Dictionary}}</ref> and the [[Persian language|Persian]] word {{lang|fa|زرنيخ}} ''Zarnikh'', meaning "yellow [[orpiment]]", into [[Greek language|Greek]] as ''arsenikon'' (Αρσενικόν). It is also related to the similar Greek word ''arsenikos'' (Αρσενικός), meaning "masculine" or "potent". The word was adopted in Latin ''arsenicum'' and Old French ''arsenic,'' from which the English word ''arsenic'' is derived.<ref name="etymonline.com"/> Arsenic sulfides (orpiment, [[realgar]]) and oxides have been known and used since ancient times.<ref name="Curiosa">{{cite journal|title = Arsenic Curiosa and Humanity|journal = The Chemical Educator
|volume = 7| issue = 2|year = 2002|pages = 51|first = Ronald|last = Bentley|url = http://192.129.24.144/licensed_materials/00897/sbibs/s0007002/spapers/720051rb.pdf|doi = 10.1007/s00897020539a|last2 = Chasteen|first2 = Thomas G.}}</ref> [[Zosimos of Panopolis|Zosimos]] (circa 300 AD) describes roasting ''sandarach'' (realgar) to obtain ''cloud of arsenic'' ([[arsenious oxide]]) which he then reduces to metallic arsenic.<ref>{{cite book|title=Makers of Chemistry|author=Holmyard John Eric|publisher=Read Books|year=2007|isbn=1406732753}}</ref> As the symptoms of [[arsenic poisoning]] were somewhat ill-defined, it was frequently used for [[murder]] until the advent of the [[Marsh test]], a sensitive chemical test for its presence. (Another less sensitive but more general test is the [[Reinsch test]].) Owing to its use by the ruling class to murder one another and its potency and discreetness, arsenic has been called the ''Poison of Kings'' and the ''King of Poisons''.<ref>{{cite journal|doi = 10.1177/0960327107084539|year = 2007|title = Arsenic neurotoxicity - a review|volume = 26|issue = 10|pages = 823–32|pmid = 18025055|journal = Human & experimental toxicology|last1 = Vahidnia|first1 = A.|last2 = Van Der Voet|first2 = G. B.|last3 = De Wolff|first3 = F. A.}}</ref>

During the [[Bronze Age]], arsenic was often included in [[bronze]], which made the alloy harder (so-called "[[arsenical bronze]]").
[[Albertus Magnus]] (Albert the Great, 1193–1280) is believed to have been the first to isolate the element in 1250 by heating soap together with [[arsenic trisulfide]].<ref name="BuildingBlocks451-3"/> In 1649, [[Johann Schröder]] published two ways of preparing arsenic.

[[Image:Arsenic alchemical symbol.svg|75px|thumb|left|[[Alchemical symbol]] for arsenic]]

[[Cadet's fuming liquid]] (impure [[cacodyl]]), often claimed as the first synthetic [[Organometallic chemistry|organometallic compound]], was synthesized in 1760 by [[Louis Claude Cadet de Gassicourt]] by the reaction of [[potassium acetate]] with [[arsenic trioxide]].<ref>{{cite journal|title = Cadet's Fuming Arsenical Liquid and the Cacodyl Compounds of Bunsen|first = Dietmar|last = Seyferth|journal = Organometallics|year = 2001|volume = 20|issue = 8|pages = 1488–1498|doi = 10.1021/om0101947|url = http://pubs.acs.org/cgi-bin/abstract.cgi/orgnd7/2001/20/i08/abs/om0101947.html}}</ref>

In the [[Victorian era]], "arsenic" ("white arsenic" trioxide) was mixed with [[vinegar]] and [[chalk]] and eaten by women to improve the [[complexion]] of their faces, making their skin paler to show they did not work in the fields. Arsenic was also rubbed into the faces and arms of women to "improve their complexion". The accidental use of arsenic in the adulteration of foodstuffs led to [[The Bradford Sweet Poisoning|the Bradford sweet poisoning]] in 1858, which resulted in approximately 20 deaths.<ref name="Food">{{cite journal|journal =British Food Journal|volume = 101|issue = 4|year = 1999|pages = 274–283|title = Viewpoint: the story so far: An overview of developments in UK food regulation and associated advisory committees|first = Alan|last = Turner |url = http://www.emeraldinsight.com/Insight/ViewContentServlet?Filename=Published/EmeraldFullTextArticle/Pdf/0701010401.pdf |doi =10.1108/00070709910272141}}</ref>

==Applications==
The largest application of arsenic is for alloying with copper and especially lead.  Lead used in automotive batteries is strengthened by the presence of a few percent of arsenic.

===Wood preservation===
The toxicity of arsenic to [[insect]]s, [[bacteria]], and [[fungi]] led to its use as a wood preservative.<ref>Rahman FA, Allan DL, Rosen CJ, Sadowsky MJ. "Arsenic availability from chromated copper arsenate (CCA)-treated wood" J Environ Qual. 2004 Jan-Feb;33(1):173-80. pmid = 14964372 }}</ref>
In the 1950s a process of treating wood with [[chromated copper arsenate]] (also known as CCA or [[Tanalith]]) was invented, and for decades this treatment was the most extensive industrial use of arsenic. Due to an increased understanding of arsenic's high level of toxicity, most countries banned the use of CCA in consumer products. The [[European Union]] and United States led this ban, beginning in 2004.<ref>{{cite book|title = Environmental Chemistry: Green Chemistry and Pollutants in Ecosystems|editors = Lichtfouse, Eric; Schwarzbauer, Jan; Robert, Didier|year = 2004|isbn = 9783540228608|url = http://books.google.com/?id=IDGLh_cWAIwC|chapter = Electrodialytical Removal of Cu, Cr and As from Threaded Wood|first = Eric | last = Lichtfouse |publisher = Springer|location = Berlin}}</ref><ref name="round">{{cite journal|journal = Talanta|volume = 58|issue = 1|year = 2002|pages = 201–235|doi = 10.1016/S0039-9140(02)00268-0|title = Arsenic round the world: a review|first = Badal Kumar|last = Mandal|pmid = 18968746|last2 = Suzuki|first2 = K. T.}}</ref>

[[Image:Roxarsone.png|thumb|190 px|[[Roxarsone]] is a widely used and controversial arsenic compound that is used as a nutritional supplement for chickens.]]

===Medical use===
During the 18th, 19th, and 20th centuries, a number of arsenic compounds have been used as medicines, including [[arsphenamine]] (by [[Paul Ehrlich]]) and [[arsenic trioxide]] (by [[Thomas Fowler (inventor)|Thomas Fowler]]).  Arsphenamine as well as [[Neosalvarsan]] was indicated for [[syphilis]] and [[trypanosomiasis]], but has been superseded by modern [[antibiotics]]. Arsenic trioxide has been used in a variety of ways over the past 500 years, but most commonly in the treatment of [[cancer]]. The US [[Food and Drug Administration]] in 2000 approved this compound for the treatment of patients with [[acute promyelocytic leukemia]] that is resistant to [[all-trans retinoic acid|ATRA]].<ref>{{cite journal|last = Antman |first = Karen H.|year = 2001|url= http://theoncologist.alphamedpress.org/cgi/content/full/6/suppl_2/1|title = The History of Arsenic Trioxide in Cancer Therapy|volume = 6|issue =Suppl 2|pages = 1–2|pmid = 11331433|doi = 10.1634/theoncologist.6-suppl_2-1|journal = The oncologist}}</ref> It was also used as [[Fowler's solution]] in [[psoriasis]].<ref>{{cite journal| title = Noncirrhotic presinusoidal portal hypertension associated with chronic arsenical intoxication|journal = Gastroenterology| year = 1975| volume = 68'| issue = 5 Pt 1|pages =1270–1277|pmid = 1126603|format = Free full text| last1 = Huet| first1 = P. M.| last2 = Guillaume| first2 = E.| last3 = Cote| first3 = J.| last4 = Légaré| first4 = A.| last5 = Lavoie| first5 = P.| last6 = Viallet| first6 = A.}}</ref> Recently new research has been done in locating tumours using arsenic-74 (a positron emitter). The advantages of using this isotope instead of the previously used [[iodine]]-124 is that the signal in the [[Positron emission tomography|PET scan]] is clearer as the body tends to transport iodine to the thyroid gland producing a lot of noise.<ref>{{cite journal|journal = Journal of Clinical Cancer|year = 2008|volume = 14|pages =1377–1385|doi = 10.1158/1078-0432.CCR-07-1516|title = Vascular Imaging of Solid Tumors in Rats with a Radioactive Arsenic-Labeled Antibody that Binds Exposed Phosphatidylserine|last = Jennewein|first =Marc|pmid = 18316558|issue = 5|format = Free full text|last2 = Lewis|first2 = M. A.|last3 = Zhao|first3 = D.|last4 = Tsyganov|first4 = E.|last5 = Slavine|first5 = N.|last6 = He|first6 = J.|last7 = Watkins|first7 = L.|last8 = Kodibagkar|first8 = V. D.|last9 = O'Kelly|first9 = S.}}</ref>

===Pigments===
Copper acetoarsenite was used as a green [[pigment]] known under many names, including '[[Paris Green]]' and 'Emerald Green'. It caused numerous [[arsenic poisoning]]s. [[Scheele's Green]], a copper arsenate, was used in the 19th century as a [[food dye|colouring agent]] in [[sweets]].<ref>{{cite book|title = The Poison Paradox: Chemicals as Friends and Foes|chapter = Butter Yellow and Scheele's Green|first = John|last = Timbrell|publisher = Oxford University Press|year = 2005|isbn = 9780192804952|url = http://books.google.com/?id=qYYOtQU37jcC}}</ref>

===Military===
After [[World War I]], the United States built up a stockpile of {{gaps|20|000|tons}} of [[lewisite]](ClCH=CHAsCl<sub>2</sub>), a [[Chemical warfare|chemical weapon]] that is a [[vesicant]] (blister agent) and [[lung]] irritant. The stockpile was neutralized with bleach and dumped into the [[Gulf of Mexico]] after the 1950s.<ref>{{cite web | url = http://library.thinkquest.org/05aug/00639/en/w_chemical_blister.html | publisher  = Code Red - Weapons of Mass Destruction  |title = Blister Agents | accessdate = 2010-05-15}}</ref> During the [[Vietnam War]] the [[United States]] used [[Agent Blue]], a mixture of [[sodium cacodylate]]) and its acid form, as one of the [[rainbow herbicides]] to deprive the Vietnamese of valuable crops.

===Other uses===
*Various [[agriculture|agricultural]] insecticides, termination and poisons. For example [[Lead hydrogen arsenate]] was used well into the 20th century as an [[insecticide]] on [[fruit tree]]s.<ref>Peryea F. J. 1998. Historical use of lead arsenate insecticides, resulting in soil contamination and implications for soil remediation. Proceedings, 16th World Congress of Soil Science, Montpellier, France. 20–26. Aug. Available online: http://soils.tfrec.wsu.edu/leadhistory.htm</ref> Its use sometimes resulted in [[brain damage]] to those working the sprayers. In the last half century, [[monosodium methyl arsenate]] (MSMA) and [[disodium methyl arsenate]] (DSMA), a less toxic organic form of arsenic, has replaced lead arsenate's role in agriculture.
*Used in animal feed, particularly in the US as a method of disease prevention<ref>{{cite journal|journal = Environmental Health Perspective|year = 2005|volume = 113|issue = 9|pages = 1123–1124|doi = 10.1289/ehp.7834|title = Arsenic: A Roadblock to Potential Animal Waste Management Solutions|first = Keeve E|last = Nachman|last2 = Graham|first2 = Jay P.|last3 = Price|first3 = Lance B.|last4 = Silbergeld|first4 = Ellen K.}}</ref><ref>{{cite web|url=http://www.atsdr.cdc.gov/toxprofiles/tp2-c5.pdf|title=section 5.3, pg. 310|publisher=Agency for Toxic Substances and Disease Registry}}</ref> and growth stimulation. One example is [[roxarsone]] which was used by 69.8 and 73.9% of the [[broiler]] starter and growers between 1995 to 2000.<ref>{{cite journal|title =A Broad View of Arsenic|url = http://ps.fass.org/cgi/content/abstract/86/1/2|year = 2007|volume = 86|pages = 2–14|journal = Poultry Science|first = F. T.|last =Jones|pmid =17179408|issue =1}}</ref>
*[[Gallium arsenide]] is an important [[semiconductor]] material, used in [[integrated circuit]]s. Circuits made using the compound are much faster (but also much more expensive) than those made in [[silicon]]. Unlike silicon it is [[direct bandgap]], and so can be used in [[laser diode]]s and [[LED]]s to directly convert [[electricity]] into [[light]].
*Also used in [[bronzing]] and [[pyrotechnics]].
*Up to 2% of arsenic is used in lead alloys for [[lead shot]]s and [[bullet]]s.<ref>{{cite book|title = Engineering Properties and Applications of Lead Alloys|chapter = XIV. Ammunition|first = Sivaraman|last = Guruswamy|publisher = CRC Press|year = 1999|isbn = 9780824782474|url = http://books.google.com/?id=TtGmjOv9CUAC|pages = 569–570}}</ref>
*Arsenic is added in small quantities to brass to make it [[dezincification]] resistant. This grade of brass is used to make plumbing fittings.
*Arsenic is also used for taxonomic sample preservation.
*Until recently Arsenic was used in optical glass. Modern glass manufacturers, under pressure from environmentalists, have removed it, along with [[Lead]].<ref>{{cite book | url = http://books.google.com/?id=Qt7sNqoP_CkC&pg=PA68 | page =68 | title = Pollution technology review 214: Mercury and arsenic wastes: removal, recovery, treatment, and disposal | publisher = William Andrew | year =  1993 | isbn = 9780815513261 | chapter = Arsenic Supply Demand and the Environment}}</ref>

==Biological role==
[[Image:ArsenobetainePIC.svg|thumb| Arsenobetaine]]
The similarity between arsenic and phosphorus is so great that arsenic will partly substitute for phosphorus in biochemical reactions. However, in subtoxic doses, soluble arsenic compounds act as [[stimulant]]s, and were once popular in small doses as medicine by people in the mid 18th century.<ref name="Holl">{{cite book|publisher = Walter de Gruyter|year = 1985|edition = 91–100|pages = 675–681|isbn = 3110075113|title = Lehrbuch der Anorganischen Chemie|first = Arnold F.|last = Holleman|coauthors = Wiberg, Egon; Wiberg, Nils|language = German|chapter = Arsen}}</ref>

Some species of [[bacteria]] obtain their energy by [[redox|oxidizing]] various fuels while [[redox|reducing]] arsenate to arsenite. The [[enzyme]]s involved are known as [[arsenate reductase]]s (Arr).

In 2008, bacteria were discovered that employ a version of [[photosynthesis]] in the absence of oxygen with arsenites as [[electron donor]]s, producing arsenates (just like ordinary photosynthesis uses water as electron donor, producing molecular oxygen). Researchers conjecture that historically these photosynthesizing organisms produced the arsenates that allowed the arsenate-reducing bacteria to thrive. One [[strain (biology)|strain]] PHS-1 has been isolated and is related to the [[γ-Proteobacterium]] ''[[Ectothiorhodospira shaposhnikovii]]''. The mechanism is unknown, but an encoded Arr enzyme may function in reverse to its known [[homology (biology)|homologues]].<ref>{{cite journal|author= Kulp, T. R|year = 2008|title = Arsenic(III) fuels anoxygenic photosynthesis in hot spring biofilms from Mono Lake, California|journal = [[Science (journal)|Science]]|volume = 321 |issue = 5891|pages = 967–970|doi = 10.1126/science.1160799|laysummary = http://www.rsc.org/chemistryworld/News/2008/August/15080802.asp|laysource = Chemistry World, 15 August 2008|pmid= 18703741|last2= Hoeft|first2= S. E.|last3= Asao|first3= M.|last4= Madigan|first4= M. T.|last5= Hollibaugh|first5= J. T.|last6= Fisher|first6= J. C.|last7= Stolz|first7= J. F.|last8= Culbertson|first8= C. W.|last9= Miller|first9= L. G.}}</ref>

Arsenic has been linked to epigenetic changes which are heritable changes in gene expression that occur without changes in DNA sequence and include DNA methylation, histone modification and RNA interference. Toxic levels of arsenic cause significant DNA hypermethylation of tumour suppressor genes p16 and p53 thus increasing risk of carcinogenesis. These epigenetic events have been observed in ''in vitro'' studies with human kidney cells and ''in vivo'' tests with rat liver cells and peripheral blood leukocytes in humans.<ref>{{cite journal|last=Baccarelli|first=A.|year=2009|title=Epigenetics and environmental chemicals|journal=Current opinion in Pediatrics |issue=2 |volume=21 |pages=243–251 |doi=10.1097/MOP.0b013e32832925cc |pmid=19663042|last2=Bollati|first2=V.}}</ref> Inductive coupled plasma mass spectrometry (ICP-MS) is used to detect precise levels of intracellular of arsenic and its other bases involved in epigenetic modification of DNA.<ref>{{cite journal|last=Nicholis|first=I.|year=2009|title=Arsenite medicinal use, metabolism, pharmacokinetics and monitoring in human hair| journal=Biochimie| pmid=19527769| doi=10.1016/j.biochi.2009.06.003 |last2=Curis |last3=Deschamps|last4=Bénazeth|volume=91|pages=12601267 |first2=E.|first3=P.|first4=S.|issue=10}}</ref> Studies investigating arsenic as an epigenetic factor will help in developing precise biomarkers of exposure and susceptibility.

The Chinese brake fern (''[[Pteris vittata]]''), hyperaccumulates arsenic present in the soil into its leaves and has a proposed use in [[phytoremediation]].<ref>{{cite jstor|1514012}}</ref>

===Biomethylation of arsenic===
Inorganic arsenic and its compounds, upon entering the [[food chain]], are progressively metabolised to less toxic forms of arsenic through a process of [[methylation]]. For example, the mold [[Scopulariopsis brevicaulis]] produce significant amounts of [[trimethylarsine]] if inorganic arsenic is present.<ref>{{cite journal|first = Ronald|last = Bentley|title = Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth|journal = Microbiology and Molecular Biology Reviews|year = 2002|volume = 66|issue = 2|pages = 250–271|doi = 10.1128/MMBR.66.2.250-271.2002|pmid = 12040126|format = Free full text|last2 = Chasteen|first2 = TG|pmc = 120786}}</ref> The organic compound [[arsenobetaine]] is found in some marine foods such as fish and algae, and also in mushrooms in larger concentrations. The average person's intake is about 10–50&nbsp;µg/day. Values about 1000&nbsp;µg are not unusual following consumption of fish or mushrooms. But there is little danger in eating fish because this arsenic compound is nearly non-toxic.<ref>{{cite journal|title = Arsenic speciation in the environment|first = William R|last = Cullen|journal = Chemical Reviews|year = 1989|volume = 89|issue = 4|pages =713–764|doi = 10.1021/cr00094a002|last2 = Reimer|first2 = Kenneth J.}}</ref>

===Biochemical basis of arsenic toxicity===
The high affinity of arsenic(III) oxides for thiols is usually assigned as the cause of the high toxicity.  Thiols in the form of cysteine residues, are situated at the active sites of many important [[enzyme]]s.<ref name=Ullmann/> 

==Environmental issues==
===Arsenic in drinking water===
{{Main|Arsenic contamination of groundwater}}
Widespread arsenic contamination of groundwater has led to a massive epidemic of [[arsenic poisoning]] in [[Water supply and sanitation in Bangladesh|Bangladesh]]<ref>{{cite book | first = Andrew | last = Meharg | title = Venomous Earth - How Arsenic Caused The World's Worst Mass Poisoning | isbn = 9781403944993 | publisher =  Macmillan Science | year = 2005}}</ref> and neighbouring countries. Presently 42 major incidents around the world have been reported on groundwater arsenic contamination. It is estimated that approximately 57&nbsp;million people<!--just Bangladesh, or total?--> are drinking [[groundwater]] with arsenic concentrations elevated above the [[World Health Organization]]'s standard of 10 [[Concentration#.22Parts-per.22 notation|parts per billion]]. However, a study of cancer rates in Taiwan<ref>{{cite journal |doi=10.1289/ehp.8704 |journal=Environ. Health Perspect. |volume=114 |issue=7 |pages=1077–82 |year=2006 |pmid=16835062 |pmc=1513326 |last1=Lamm |first1=S. H. |last2=Engel |first2=A. |last3=Penn |first3=C. A. |last4=Chen |first4=R. |last5=Feinleib |first5=M. |title=Arsenic cancer risk confounder in southwest Taiwan data set.}}</ref> suggested that significant increases in cancer mortality appear only at levels above 150 parts per billion. The arsenic in the groundwater is of natural origin, and is released from the sediment into the groundwater owing to the anoxic conditions of the subsurface. This groundwater began to be used after local and western [[Non-governmental organization|NGOs]] and the Bangladeshi government undertook a massive shallow tube [[Water well|well]] drinking-water program in the late twentieth century. This program was designed to prevent drinking of bacterially contaminated surface waters, but failed to test for arsenic in the groundwater. Many other countries and districts in [[Southeast Asia|South East Asia]], such as [[Vietnam]], [[Cambodia]], and [[China]] have geological environments conducive to generation of high-arsenic groundwaters. [[Arsenic_poisoning#Arsenicosis:_chronic_arsenic_poisoning_from_drinking_water|Arsenicosis]] was reported in [[Nakhon Si Thammarat]], [[Thailand]] in 1987, and the dissolved arsenic in the [[Chao Phraya River]] is suspected of containing high levels of naturally occurring arsenic, but has not been a public health problem owing to the use of bottled water.<ref>{{cite web|publisher = 28th WEDC Conference Calcutta|year = 2002|url = http://wedc.lboro.ac.uk/conferences/pdfs/28/Kohnhorst.pdf|title = Groundwater arsenic in central Thailand|first1 = Andrew|last1 = Kohnhorst|first2 = Allan |last2 = Laird|first3 = Pokethitiyoke|last3 = Prayad|first4 = Anyapo|last4 = Suthida|accessdate = 2009-01-29}}</ref>

In the United States, arsenic is most commonly found in the ground waters of the southwest.<ref name="test">{{cite web | url = http://h2oc.com/pdfs/Occurrence.pdf | title =  Arsenic in Drinking Water: 3. Occurrence in U.S. Waters | accessdate = 2010-05-15}}</ref> Parts of [[New England]], [[Michigan]], [[Wisconsin]], [[Minnesota]] and the Dakotas are also known to have significant{{Clarify|date=May 2010}} concentrations of arsenic in ground water. Increased levels of skin cancer have been associated with arsenic exposure in Wisconsin, even at levels below the 10 part per billion drinking water standard.<ref>{{cite journal  |title=Association of arsenic-contaminated drinking-water with prevalence of skin cancer in Wisconsin's Fox River Valley |journal=J. Health Popul Nutr |volume=24 |issue=2 |pages=206–13 |year=2006 |pmid=17195561|format=Free full text  |last1=Knobeloch  |first1=L. M.  |last2=Zierold  |first2=K. M.  |last3=Anderson  |first3=H. A.}}</ref> According to a recent film funded by the US [[Superfund]], millions of private wells have unknown arsenic levels, and in some areas of the US, over 20% of wells may contain levels that exceed established limits.<ref>{{cite web |url=http://www.dartmouth.edu/~toxmetal/InSmallDoses/ |title=In Small Doses}}</ref>

Low-level exposure to arsenic at concentrations found commonly in US drinking water compromises the initial immune response to H1N1 or swine flu infection according to NIEHS-supported scientists. The study, conducted in laboratory mice, suggests that people exposed to arsenic in their drinking water may be at increased risk for more serious illness or death in response to infection from the virus.<ref>{{cite journal|last=Courtney|first=D|year=2009|title=Low Dose Arsenic Compromises the Immune Response to Influenza A Infection in vivo|pages=1441–7|pmid=19750111| magazine=Environ Health Perspect|pmc=2737023|issue=9|doi=10.1289/ehp.0900911|last2=Ely|volume=117|first2=Kenneth H.|last3=Enelow|first3=Richard I.|last4=Hamilton|first4=Joshua W.|journal=Environmental Health Perspectives}}</ref>

Epidemiological evidence from [[Chile]] shows a dose dependent connection between chronic arsenic exposure and various forms of cancer, particularly when other risk factors, such as cigarette smoking, are present. These effects have been demonstrated to persist below 50 parts per billion.<ref>{{cite journal |title=Arsenic exposure and its impact on health in Chile |journal=J Health Popul Nutr |volume=24 |issue=2 |pages=164–75 |year=2006 |pmid=17195557|format=Free full text |last1=Ferreccio |first1=C. |last2=Sancha |first2=A. M.}}</ref>

Analyzing multiple epidemiological studies on inorganic arsenic exposure suggests a small but measurable risk increase for bladder cancer at 10 parts per billion.<ref>{{cite journal |last1=Chu | first1= H. A. |last2 = Crawford-Brown | first2= D. J. |title=Inorganic arsenic in drinking water and bladder cancer: a meta-analysis for dose-response assessment |journal=Int. J. Environ. Res. Public Health |volume=3 |issue=4 |pages=316–22 |year=2006 |pmid=17159272 |doi=10.3390/ijerph2006030039|format=Free full text}}</ref> According to Peter Ravenscroft of the Department of Geography at the University of Cambridge,<ref>{{cite news |url = http://www.usatoday.com/news/world/2007-08-30-553404631_x.htm|title = Arsenic in drinking water seen as threat - USATODAY.com|accessdate = 2008-01-01 | work=USA Today | date=2007-08-30}}</ref> roughly 80 million people worldwide consume between 10 and 50 parts per billion arsenic in their drinking water. If they all consumed exactly 10 parts per billion arsenic in their drinking water, the previously cited multiple epidemiological study analysis would predict an additional 2,000 cases of bladder cancer alone. This represents a clear underestimate of the overall impact, since it does not include lung or skin cancer, and explicitly underestimates the exposure. Those exposed to levels of arsenic above the current WHO standard should weigh the costs and benefits of arsenic remediation.

Early (1973) evaluations of the removal of dissolved arsenic by drinking water treatment processes demonstrated that arsenic is very effectively removed by co-precipitation with either iron or aluminum oxides. The use of iron as a coagulant, in particular, was found to remove arsenic with efficiencies exceeding 90%.<ref>{{cite journal|title=Removal of Arsenic (V) from Water by Adsorption on Aluminum and Ferric Hydroxides|journal=J. American Water Works Assn.| volume=65| issue=8|pages=548–552|year=1973 | last1 = Gulledge |  first1 = John H.| last2 = O'Connor | first2 = John T.}}</ref><ref>{{cite news|url=http://www.h2oc.com/pdfs/Removal.pdf|title=Arsenic in Drinking Water: 4. Removal Methods| last1 =O'Connor|  first1 = J. T.| last2 =  O'Connor|  first2 = T. L.}}</ref> Several adsorptive media systems have been approved for point-of-service use in a study funded by the [[United States Environmental Protection Agency]] (U.S.EPA) and the [[National Science Foundation]] (NSF). A team of European and Indian scientists and engineers have set up six arsenic treatment plants in [[West Bengal]] based on in-situ remediation method (SAR Technology). This technology does not use any chemicals and arsenic is left as an insoluble form (+5 state) in the subterranean zone by recharging aerated water into the aquifer and thus developing an oxidation zone to support arsenic oxidizing micro-organisms. This process does not produce any waste stream or sludge and is relatively cheap.<ref>{{cite web | url = http://www.insituarsenic.org | title = In situ arsenic treatment | accessdate = 2010-05-13}}</ref>

Magnetic separations of arsenic at very low magnetic field [[gradient]]s have been demonstrated in point-of-use water purification with high-surface-area and [[monodisperse]] [[magnetite]] (Fe<sub>3</sub>O<sub>4</sub>) [[nanocrystal]]s. Using the high specific surface area of Fe<sub>3</sub>O<sub>4</sub> nanocrystals the mass of waste associated with arsenic removal from water has been dramatically reduced.<ref>{{cite journal|last = Yavuz|first = Cafer T|title = Low-Field Magnetic Separation of Monodisperse Fe<sub>3</sub>O<sub>4</sub> Nanocrystals|journal = Science|year = 2005|doi = 10.1126/science.1131475|volume = 314|issue = 5801|pages = 964–967|pmid = 17095696|last2 = Mayo|first2 = J. T.|last3 = Yu|first3 = W. W.|last4 = Prakash|first4 = A.|last5 = Falkner|first5 = J. C.|last6 = Yean|first6 = S.|last7 = Cong|first7 = L.|last8 = Shipley|first8 = H. J.|last9 = Kan|first9 = A.}}</ref>

Epidemiological studies have suggested a correlation between chronic consumption of drinking water contaminated with arsenic and the incidence of all leading causes of mortality.  The literature provides reason to believe arsenic exposure is causative in the pathogenesis of diabetes.

===Wood preservation in the US===
As of 2002, US-based industries consumed 19,600 metric tons of arsenic. 90% of this was used for treatment of wood with CCA. In 2007, 50% of the 5,280 metric tons of consumption was still used for this purpose.<ref name=USGSYB2007>{{cite web|url = http://minerals.er.usgs.gov/minerals/pubs/commodity/arsenic/myb1-2007-arsen.pdf|first = William E.|last = Brooks|publisher = [[United States Geological Survey]]|accessdate = 2008-11-08|title = Minerals Yearbook 2007: Arsenic}}</ref><ref>{{cite web|url = http://minerals.er.usgs.gov/minerals/pubs/commodity/arsenic/160302.pdf|first = Robert G.|last = Reese, Jr|publisher = [[United States Geological Survey]]|accessdate = 2008-11-08|title = Commodity Summaries 2002: Arsenic}}</ref> In the United States, the use of arsenic in consumer products was discontinued for residential and general consumer construction on December 31, 2003 and alternative chemicals are now used, such as [[Alkaline Copper Quaternary]], [[borate]]s, [[Wood_preservation#Copper_azole|copper azole]], cyproconazole, and [[propiconazole]].<ref>{{cite web|url=http://www.epa.gov/oppad001/reregistration/cca/|title=Chromated Copper Arsenate (CCA)|publisher=US Environmental Protection Agency}}</ref>

Although discontinued, this application is also one of the most concern to the general public. The vast majority of older [[Timber treatment|pressure-treated]] wood was treated with CCA. CCA lumber is still in widespread use in many countries, and was heavily used during the latter half of the 20th century as a structural and outdoor [[building material]]. Although the use of CCA lumber was banned in many areas after studies showed that arsenic could leach out of the wood into the surrounding [[soil]] (from playground equipment, for instance), a risk is also presented by the burning of older CCA timber. The direct or indirect ingestion of wood ash from burnt CCA lumber has caused fatalities in animals and serious poisonings in humans; the lethal human dose is approximately 20&nbsp;grams of ash. Scrap CCA lumber from construction and demolition sites may be inadvertently used in commercial and domestic fires. Protocols for safe disposal of CCA lumber do not exist evenly throughout the world; there is also concern in some quarters about the widespread [[landfill]] disposal of such timber.

===Mapping of industrial releases in the US===
One tool that maps releases of arsenic to particular locations in the United States<ref>{{cite web|url=http://toxmap.nlm.nih.gov/toxmap/tri/mapIt.do?chemicalName=arsenic |title=TRI Releases Map |publisher=Toxmap.nlm.nih.gov |accessdate=2010-03-23}}</ref> and also provides additional information about such releases is [[TOXMAP]]. TOXMAP is a Geographic Information System (GIS) from the Division of Specialized Information Services of the [[United States National Library of Medicine]] (NLM) that uses maps of the United States to help users visually explore data from the [[United States Environmental Protection Agency]]'s (EPA) [[Toxics Release Inventory]] and [[Superfund Basic Research Program]]s. TOXMAP is a resource funded by the US Federal Government. TOXMAP's chemical and environmental health information is taken from NLM's Toxicology Data Network (TOXNET)<ref>[http://toxnet.nlm.nih.gov TOXNET - Databases on toxicology, hazardous chemicals, environmental health, and toxic releases]</ref> and [[PubMed]], and from other authoritative sources.

==Safety==
{{Main|Arsenic poisoning|Arsenic toxicity}}
[[Image:Skull and crossbones.svg|left|80px]]
Arsenic and many of its compounds are especially potent poisons. Arsenic disrupts [[Adenosine triphosphate|ATP]] production through several mechanisms. At the level of the [[citric acid cycle]], arsenic inhibits [[lipoic acid]] which is a [[Cofactor (biochemistry)|cofactor]] for [[pyruvate dehydrogenase]]; and by competing with phosphate it uncouples [[oxidative phosphorylation]], thus inhibiting energy-linked reduction of [[Nicotinamide adenine dinucleotide|NAD+]], mitochondrial respiration, and ATP synthesis. Hydrogen peroxide production is also increased, which might form reactive oxygen species and oxidative stress. These metabolic interferences lead to death from multi-system [[organ failure]], probably from [[necrotic]] cell death, not [[apoptosis]]. A [[post mortem]] reveals brick red coloured [[mucosa]], owing to severe [[haemorrhage]]. Although arsenic causes toxicity, it can also play a protective role.<ref>{{cite book|page=512|publisher = McGraw-Hill|isbn = 978-0071389143|title = Casarett and Doull's Essentials of Toxicology|year = 2003| first1 = Curtis|last1 = Klaassen|last2= Watkins |first2 = John}}</ref>

Elemental arsenic and arsenic compounds are classified as "[[toxicity|toxic]]" and "dangerous for the environment" in the [[European Union]] under [[directive 67/548/EEC]].
<!-- INDEX 033-001-00-X (arsenic) R23/25-50/53; S1/2-20/21-28-45-60-61 -->
<!-- INDEX 033-002-00-5 (other compounds) pareil -->The [[International Agency for Research on Cancer]] (IARC) recognizes arsenic and arsenic compounds as [[List of IARC Group 1 carcinogens|group 1 carcinogens]], and the EU lists arsenic trioxide, [[arsenic pentoxide]] and [[arsenate]] salts as category 1 [[carcinogen]]s.

Arsenic is known to cause [[Arsenic poisoning#Arsenicosis: chronic arsenic poisoning from drinking water|arsenicosis]] owing to its manifestation in drinking water, “the most common species being arsenate [HAsO<sub>4</sub><sup>2-</sup> ; As(V)] and arsenite [H<sub>3</sub>AsO<sub>3</sub> ; As(III)]”. The ability of arsenic to undergo redox conversion between As(III) and As(V) makes its availability in the environment more abundant. According to Croal, Gralnick, Malasarn, and Newman, “[the] understanding [of] what stimulates As(III) oxidation and/or limits As(V) reduction is relevant for bioremediation of contaminated sites (Croal). The study of chemolithoautotrophic As(III) oxidizers and the heterotrophic As(V) reducers can help the understanding of the oxidation and/or reduction of arsenic.<ref>{{cite journal|title=The Genetics of Geochemisty|journal=Annual Review of Genetics |volume=38 |year=2004 |pages=175–206|pmid=15568975 |doi=10.1146/annurev.genet.38.072902.091138|last1=Croal|first1=Laura R. |last2=Gralnick |first2=Jeffrey A. |last3=Malasarn |first3=Davin |last4=Newman |first4=Dianne K.}}</ref>

Treatment of chronic arsenic poisoning is easily accomplished. British anti-lewisite ([[dimercaprol]]) is prescribed in dosages of 5&nbsp;mg/kg up to 300&nbsp;mg each 4&nbsp;hours for the first day. Then administer the same dosage each 6&nbsp;hours for the second day. Then prescribe this dosage each 8&nbsp;hours for eight additional days.<ref>{{cite book|title=The Psychiatric, Psychogenic ans Somatopsychic Disorders Handbook |location=New Hyde Park, NY|publisher=Medical Examination Publishing Co |year=1978 |pages=81–82}}</ref> However the Agency for Toxic Substances and Disease Registry (ATSDR) states that the long term effects of arsenic exposure cannot be predicted.<ref name="atsdr.cdc.gov"/> Blood, urine, hair and nails may be tested for arsenic, however these tests cannot foresee possible health outcomes due to the exposure.<ref name="atsdr.cdc.gov"/> Excretion occurs in the urine and long term exposure to arsenic has been linked to bladder and kidney cancer in addition to cancer of the liver, prostate, skin, lungs and nasal cavity.<ref>The Tox Guide for Arsenic (2007). The Agency for Toxic Substances and Disease Registry.Retrieved at http://www.atsdr.cdc.gov/toxguides/toxguide-2.pdf?id=21&tid=3and long</ref>  

===Occupational exposure===

Occupational exposure and [[arsenic poisoning]] may occur in persons working in industries involving the use of inorganic arsenic and its compounds, such as wood preservation, glass production, nonferrous metal alloys, and electronic semiconductor manufacturing. Inorganic arsenic is also found in coke oven emissions associated with the smelter industry.<ref>{{cite web
|url= http://www.osha.gov/SLTC/arsenic/index.html
|title=OSHA Arsenic
|accessdate=2007-10-08
|publisher=United States Occupational Safety and Health Administration
}}</ref>

==See also==
{{Wikipedia-Books|Arsenic}}
{{colbegin|2}}
*[[Aqua Tofana]]
*[[Arsenic poisoning]]
*[[Arsenic trioxide]]
*[[Fowler's solution]]
*[[Grainger challenge]]
*[[White arsenic]]
{{colend}}

==References==
{{Reflist|2}}

==External links==
{{Commons|Arsenic}}
{{Wiktionary|arsenic}}
*[http://ctd.mdibl.org/detail.go?type=chem&acc=D001151&queryTerms=arsenic&queryType=contains CTD's Arsenic page] and [http://ctd.mdibl.org/detail.go?type=chem&acc=D001152&queryTerms=arsenicals&queryType=contains CTD's Arsenicals page] from the [[Comparative Toxicogenomics Database]]
*[http://www.asmalldoseof.org/ A Small Dose of Toxicology]
*[http://www.atsdr.cdc.gov/csem/arsenic/ ATSDR - Case Studies in Environmental Medicine: Arsenic Toxicity]
*[http://www.clu-in.org/contaminantfocus/default.focus/sec/arsenic/cat/Overview/ Contaminant Focus: Arsenic] by the [[United States Environmental Protection Agency|EPA]].
*[http://www.inchem.org/documents/ehc/ehc/ehc224.htm Environmental Health Criteria for Arsenic and Arsenic Compounds, 2001] by the [[World Health Organization|WHO]].
*[http://www.informaworld.com/smpp/content~db=all?content=10.1080/10934520600873571 Evaluation of the carcinogenicity of arsenic and arsenic compounds] by the [[International Agency for Research on Cancer|IARC]].
*[http://www.cdc.gov/niosh/topics/arsenic/ National Institute for Occupational Safety and Health - Arsenic Page]
*[http://www.npi.gov.au/database/substance-info/profiles/11.html National Pollutant Inventory - Arsenic]
*[http://www.origen.net/arsenic.html origen.net – CCA wood and arsenic: toxicological effects of arsenic]
*[http://www.webelements.com/webelements/elements/text/As/index.html WebElements.com – Arsenic]
{{Clear}}
{{compact periodic table}}
{{Arsenic compounds}}

[[Category:Metalloids]]
[[Category:Pnictogens]]
[[Category:Toxicology]]
[[Category:Chemical elements]]
[[Category:Endocrine disruptors]]
[[Category:Arsenic| ]]
[[Category:Occupational safety and health]]
[[Category:IARC Group 1 carcinogens]]
[[Category:Biology and pharmacology of chemical elements]]

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