germanium ← arsenic → selenium P ↑ As ↓ Sb 33As Periodic table Appearance metallic grey General properties Name, symbol, number arsenic, As, 33 Pronunciation /ˈɑrsənɪk/ ARS-ə-nik, also /ɑrˈsɛnɪk/ ar-SEN-ik when attributive Element category metalloid Group, period, block 15, 4, p Standard atomic weight 74.92160g·mol−1 Electron configuration Ar 4s2 3d10 4p3 Electrons per shell 2, 8, 18, 5 (Image) Physical properties Phase solid Density (near r.t.) 5.727 g·cm−3 Liquid density at m.p. 5.22 g·cm−3 Sublimation point 887 K, 615 °C, 1137 °F Triple point 1090 K (817°C), 3628 2 kPa Critical point 1673 K, ? MPa Heat of fusion (grey) 24.44 kJ·mol−1 Heat of vaporization  ? 34.76 kJ·mol−1 Specific heat capacity (25 °C) 24.64 J·mol−1·K−1 Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 553 596 646 706 781 874 Atomic properties Oxidation states 5, 3, 2, 1,3 -3 (mildly acidic oxide) Electronegativity 2.18 (Pauling scale) Ionization energies (more) 1st: 947.0 kJ·mol−1 2nd: 1798 kJ·mol−1 3rd: 2735 kJ·mol−1 Atomic radius 119 pm Covalent radius 119±4 pm Van der Waals radius 185 pm Miscellanea Crystal structure trigonal1 Magnetic ordering diamagnetic4 Electrical resistivity (20 °C) 333 nΩ·m Thermal conductivity (300 K) 50.2 W·m−1·K−1 Young's modulus 8 GPa Bulk modulus 22 GPa Mohs hardness 3.5 Brinell hardness 1440 MPa CAS registry number 7440-38-2 Most stable isotopes Main article: Isotopes of arsenic iso NA half-life DM DE (MeV) DP 73As syn 80.3 d ε - 73Ge γ 0.05D, 0.01D, e - 74As syn 17.78 d ε - 74Ge β+ 0.941 74Ge γ 0.595, 0.634 - β− 1.35, 0.717 74Se 75As 100% 75As is stable with 42 neutrons v · d · e Arsenic ( /ˈɑrsənɪk/ ARS-ə-nik, also /ɑrˈsɛnɪk/ ar-SEN-ik when attributive) is the chemical element that has the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, mainly combined with sulfur and metals, and also naturally in the native (elemental) state. It was first documented by Albertus Magnus in 1250.5 Arsenic is a metalloid. It can exist in various allotropes, although only the grey form is industrially important. The main use of metallic arsenic is for strengthening alloys of copper and especially lead (for example, in automotive batteries). Arsenic is a common n-type dopant in semiconductor electronic devices, and the optoelectronic compound gallium arsenide is the most common semiconductor in use after doped silicon. A few species of bacteria are able to use arsenic compounds as respiratory metabolites, and are arsenic-tolerant. However, arsenic is notoriously poisonous to multicellular life, due to the interaction of arsenic ions with protein thiols. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides (treated wood products), herbicides and insecticides. These applications are declining, however, as many of these compounds are in the process of being banned.6 Meanwhile, arsenic poisoning as a result of the natural occurrence of arsenic compounds in drinking water remains a problem for many parts of the world including the United States. Contents 1 Characteristics 1.1 Physical characteristics 1.2 Isotopes 1.3 Chemistry 2 Compounds 2.1 Inorganic 2.2 Organoarsenic compounds 2.3 Alloys 3 Occurrence and production 4 History 5 Applications 5.1 Agricultural 5.2 Medical use 5.3 Alloys 5.4 Military 5.5 Other uses 6 Biological role 6.1 Arsenic reported substituting for phosphorus as a building block of life 6.2 Biomethylation of arsenic 6.3 Biochemical basis of arsenic toxicity 7 Environmental issues 7.1 Arsenic in drinking water 7.2 Wood preservation in the US 7.3 Mapping of industrial releases in the US 8 Toxicity and precautions 9 See also 10 References 11 External links 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 g/cm3.7 It is a semiconductor and a solid (mohs scale = 3.5). Structure of yellow arsenic As4 and white phosphorus P4 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.8Yellow arsenic (As4) is soft and waxy, somewhat similar to P4. 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 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/cm3.7

Black arsenic is similar in structure to red phosphorus.7 It is glassy, brittle and a poor semiconductor. 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). Isotopes Main article: Isotopes of arsenic Naturally occurring arsenic is composed of one stable isotope, 75As.9 As of 2003, at least 33 radioisotopes have also been synthesized, ranging in atomic mass from 60 to 92. The most stable of these is 73As with a half-life of 80.3 days. Isotopes that are lighter than the stable 75As tend to decay by β+ decay, and those that are heavier tend to decay by β- decay, with some exceptions. At least 10 nuclear isomers have been described, ranging in atomic mass from 66 to 84. The most stable of arsenic's isomers is 68mAs with a half-life of 111 seconds.9 Chemistry When heated in air, arsenic 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) 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.7 Arsenic makes arsenic acid with concentrated nitric acid, arsenious acid with dilute nitric acid, and arsenic trioxide with concentrated sulfuric acid.10 Compounds See also Category: 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 states for arsenic are −3 (arsenides, such as alloy-like intermetallic compounds, +3 in arsenates(III) (arsenites) and most organoarsenic compounds). Arsenic also bonds readily to itself as seen in the square As3− 4 ions in the mineral skutterudite. In the +3 oxidation state, arsenic is typically pyramidal, owing to the influence of the lone pair of electrons. Inorganic Arsenic forms colourless, odourless, crystalline oxides As2O3 ("white arsenic") and As2O5 which are hygroscopic and readily soluble in water to form acidic solutions. Arsenic(V) acid is a weak acid. Its salts are called arsenates, e.g. Paris Green, calcium arsenate and lead hydrogen arsenate. The latter three have been used as agricultural insecticides and poisons. 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 phosphonic acid, which contains a non-acidic P-H bond. Arsenous acid is genuinely tribasic, whereas phosphonic acid is not. A broad variety of sulfur compounds of arsenic are known. Orpiment (As2S3) and realgar (As4S4) are somewhat abundant and were formerly used as painting pigments. Other sulfides include As4S3 and As4S10. Arsenic has a formal oxidation state of +2 in As4S4, which features As-As bonds so that the total covalency of As is still in fact three.11 The trifluoride, trichloride, tribromide and triiodide of arsenic(III) are well known, whereas only AsF5 is the main pentahalide. Arsenic pentafluoride is stable at room temperature, whereas the pentachloride is only stable below −50 °C.7 Organoarsenic compounds Main article: organoarsenic chemistry 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 R3-xAsClx (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. Alloys Arsenic is used as group 5 element as components of the III-V semiconductors. 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. Occurrence and production See also: Arsenide minerals and Arsenate minerals A large sample of native arsenic. Minerals with the formula MAsS and MAs2 (M = Fe, Ni, Co) are the dominant commercial sources of arsenic, together with realgar (an arsenic sulfide mineral) and native arsenic. An illustrative mineral is arsenopyrite (FeAsS), which is structurally related to iron pyrite. 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.12 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.13 The most common pathway of exposure for humans is ingestion, and the predominant source of arsenic in our diet is through seafood.14 An additional route of exposure is through inhalation.15 Arsenic output in 200616

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.16 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.17 On roasting in air of arsenopyrite, arsenic sublimes as arsenic(III) oxide leaving iron oxides,12 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.18 History Realgar Alchemical symbol for arsenic The word arsenic was borrowed from the Syriac word ܠܐ ܙܐܦܢܝܐ (al) zarniqa 19 and the Persian word زرنيخ Zarnikh, meaning "yellow orpiment", into 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.19 Arsenic sulfides (orpiment, realgar) and oxides have been known and used since ancient times.20 Zosimos (circa 300 AD) describes roasting sandarach (realgar) to obtain cloud of arsenic (arsenious oxide) which he then reduces to metallic arsenic.21 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.22 During the Bronze Age, arsenic was often included in bronze, which made the alloy harder (so-called "arsenical bronze"23). 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.5 In 1649, Johann Schröder published two ways of preparing arsenic. Cadet's fuming liquid (impure cacodyl), often claimed as the first synthetic organometallic compound, was synthesized in 1760 by Louis Claude Cadet de Gassicourt by the reaction of potassium acetate with arsenic trioxide.24 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 in 1858, which resulted in approximately 20 deaths.25 Applications Agricultural Roxarsone is a controversial arsenic compound used as a nutritional supplement for chickens. The toxicity of arsenic to insects, bacteria and fungi led to its use as a wood preservative.26 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. An increased appreciation of the toxicity of arsenic resulted in a ban for the use of CCA in consumer products; the European Union and United States initiated this process in 2004.2728 CCA remains in heavy use in other countries however, e.g. Malaysian rubber plantations.6 Arsenic was also used in various agricultural insecticides, termination and poisons. For example, lead hydrogen arsenate was a common insecticide on fruit trees,29 but contact with the compound sometimes resulted in brain damage among those working the sprayers. In the second half of the 20th century, monosodium methyl arsenate (MSMA) and disodium methyl arsenate (DSMA) – less toxic organic forms of arsenic – have replaced lead arsenate in agriculture. Arsenic is still added to animal food, particularly in the U.S. as a method of disease prevention3031 and growth stimulation. One example is roxarsone which is used as a broiler starter by about 70% of the broiler growers since 1995.32 The Poison-Free Poultry Act of 2009 proposes to ban the use of roxarsone in industrial swine and poultry production.33 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). 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 ATRA.34 It was also used as Fowler's solution in psoriasis.35 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 PET scan is clearer as the body tends to transport iodine to the thyroid gland producing a lot of noise.36

In subtoxic doses, soluble arsenic compounds act as stimulants, and were once popular in small doses as medicine by people in the mid 18th century.7 Alloys The main use of metallic arsenic is for alloying with copper and especially lead. Lead components in automotive batteries are strengthened by the presence of a few percent of arsenic. Gallium arsenide is an important semiconductor material, used in integrated circuits. It is fabricated by chemical vapor deposition. Circuits made from GaAs 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 diodes and LEDs to directly convert electricity into light.6 Military After World War I, the United States built up a stockpile of 20000tons of lewisite (ClCH=CHAsCl2), a 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.37 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 Copper acetoarsenite was used as a green pigment known under many names, including 'Paris Green' and 'Emerald Green'. It caused numerous arsenic poisonings. Scheele's Green, a copper arsenate, was used in the 19th century as a colouring agent in sweets.38 Also used in bronzing and pyrotechnics. Up to 2% of arsenic is used in lead alloys for lead shots and bullets.39 Arsenic is added in small quantities to alpha-brass to make it dezincification resistant. This grade of brass is used to make plumbing fittings or other items which are in constant contact with water.40 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.41 Biological role Arsenobetaine Some species of bacteria obtain their energy by oxidizing various fuels while reducing arsenate to arsenite. Under oxidative environmental conditions some bacteria use arsenite, which is oxidized to arsenate as fuel for their metabolism.42 The enzymes involved are known as arsenate reductases (Arr). In 2008, bacteria were discovered that employ a version of photosynthesis in the absence of oxygen with arsenites as electron donors, 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 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 homologues.43 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.44 Inductive coupled plasma mass spectrometry (ICP-MS) is used to detect precise levels of intracellular arsenic and its other bases involved in epigenetic modification of DNA.45 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.46 Arsenic reported substituting for phosphorus as a building block of life A NASA-funded astrobiology research team claimed on December 2, 2010 that the microbe strain GFAJ-1 of the Gammaproteobacteria (designated Halomonadaceae) group has the ability to substitute arsenic for at least part of the phosphorus in the molecules of its cells, including DNA and ATP.4748 Bacteria from Mono Lake, a naturally arsenic-rich site in California, were cultured in an environment high in arsenic but low in phosphorus. The finding has critics, however, who have asked for proof that arsenic is actually incorporated into biomolecules.4950 Biomethylation of arsenic Inorganic arsenic and its compounds, upon entering the food chain, are progressively metabolised through a process of methylation.51 For example, the mold Scopulariopsis brevicaulis produce significant amounts of trimethylarsine if inorganic arsenic is present.52 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 µg/day. Values about 1000 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.53 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 enzymes.6 Environmental issues Arsenic in drinking water Main article: Arsenic contamination of groundwater Widespread arsenic contamination of groundwater has ledwhen? to a massive epidemic of arsenic poisoning in Bangladesh54 and neighbouring countries. Presently 42 major incidents around the world have been reported on groundwater arsenic contamination. It is estimated that approximately 57 million people are drinking groundwater with arsenic concentrations elevated above the World Health Organization's standard of 10 parts per billion. However, a study of cancer rates in Taiwan55 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 NGOs and the Bangladeshi government undertook a massive shallow tube 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 South East Asia, such as Vietnam, Cambodia and China have geological environments conducive to generation of high-arsenic groundwaters. 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.56 In the United States, arsenic is most commonly found in the ground waters of the southwest.57 Parts of New England, Michigan, Wisconsin, Minnesota and the Dakotas are also known to have significantclarification needed 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.58 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.59 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.60 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.61 Analyzing multiple epidemiological studies on inorganic arsenic exposure suggests a small but measurable risk increase for bladder cancer at 10 parts per billion.62 According to Peter Ravenscroft of the Department of Geography at the University of Cambridge,63 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%.6465 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.66 Magnetic separations of arsenic at very low magnetic field gradients have been demonstrated in point-of-use water purification with high-surface-area and monodisperse magnetite (Fe3O4) nanocrystals. Using the high specific surface area of Fe3O4 nanocrystals the mass of waste associated with arsenic removal from water has been dramatically reduced.67

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 chromated copper arsenate (CCA). In 2007, 50% of the 5,280 metric tons of consumption was still used for this purpose.1768 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, borates, copper azole, cyproconazole and propiconazole.69 Although discontinued, this application is also one of the most concern to the general public. The vast majority of older 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 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 States70 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 Programs. 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)71 and PubMed, and from other authoritative sources. Toxicity and precautions Main articles: Arsenic poisoning and Arsenic toxicity Arsenic and many of its compounds are especially potent poisons. Many water supplies close to mines are contaminated by these poisons. Arsenic disrupts ATP production through several mechanisms. At the level of the citric acid cycle, arsenic inhibits lipoic acid which is a cofactor for pyruvate dehydrogenase; and by competing with phosphate it uncouples oxidative phosphorylation, thus inhibiting energy-linked reduction of 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.72 Elemental arsenic and arsenic compounds are classified as "toxic" and "dangerous for the environment" in the European Union under directive 67/548/EEC. The International Agency for Research on Cancer (IARC) recognizes arsenic and arsenic compounds as group 1 carcinogens, and the EU lists arsenic trioxide, arsenic pentoxide and arsenate salts as category 1 carcinogens. Arsenic is known to cause arsenicosis owing to its manifestation in drinking water, “the most common species being arsenate [HAsO42- ; As(V)] and arsenite [H3AsO3 ; 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.73 Treatment of chronic arsenic poisoning is easily accomplished. British anti-lewisite (dimercaprol) is prescribed in dosages of 5 mg/kg up to 300 mg each 4 hours for the first day. Then administer the same dosage each 6 hours for the second day. Then prescribe this dosage each 8 hours for eight additional days.74 However the Agency for Toxic Substances and Disease Registry (ATSDR) states that the long term effects of arsenic exposure cannot be predicted.14 Blood, urine, hair and nails may be tested for arsenic, however these tests cannot foresee possible health outcomes due to the exposure.14 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.75

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.76 See also Book: Arsenic Wikipedia Books are collections of articles that can be downloaded or ordered in print. Aqua Tofana Arsenic biochemistry Arsenic compounds Arsenic poisoning Arsenic toxicity Arsenic trioxide Fowler's solution GFAJ-1 Grainger challenge Hypothetical types of biochemistry Organoarsenic chemistry White arsenic References ^ Arsenic, mindat.org ^ Gokcen, N. A (1989). "The As (arsenic) system". Bull. Alloy Phase Diagrams 10: 11–22. doi:10.1007/BF02882166.  ^ Ellis, Bobby D. (2004). "Stabilized Arsenic(I) Iodide: A Ready Source of Arsenic Iodide Fragments and a Useful Reagent for the Generation of Clusters". 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Evaluation of the carcinogenicity of arsenic and arsenic compounds by the IARC. National Institute for Occupational Safety and Health - Arsenic Page National Pollutant Inventory - Arsenic origen.net – CCA wood and arsenic: toxicological effects of arsenic WebElements.com – Arsenic Arsenic, Agency for Toxic Substances and Disease Registry v · d · e Periodic table H   He Li Be   B C N O F Ne Na Mg   Al Si P S Cl Ar K Ca   Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr   Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Uuq Uup Uuh Uus Uuo Alkali metals Alkaline earth metals Lanthanides Actinides Transition metals Other metals Metalloids Other nonmetals Halogens Noble gases Unknown chem. properties Large version  v · d · e Arsenic compounds

AsBr3 · AsCl3 · AsCl5 · AsF3 · AsF5 · AsH3 · AsI3 · As2O3 · As2O5 · As2S3 · As2S5 · As2Se3 · As4S4

AsBr3 · AsCl3 · AsCl5 · AsF3 · AsF5 · AsH3 · AsI3 · As2O3 · As2O5 · As2S3 · As2S5 · As2Se3 · As4S4

AsBr3 · AsCl3 · AsCl5 · AsF3 · AsF5 · AsH3 · AsI3 · As2O3 · As2O5 · As2S3 · As2S5 · As2Se3 · As4S4