and lead smelters, and is recovered primarily from copper refinement dust. on roasting arsenopyrite in air, arsenic sublimes as arsenic(iii) oxide leaving iron oxides, while roasting without air results in the production of gray arsenic. further purification from sulfur and other chalcogens is achieved by sublimation in vacuum, in a hydrogen atmosphere, or by distillation from molten lead-arsenic mixture. rankcountry2014 as2o3 production 1 china25,000 t 2 morocco8,800 t 3 russia1,500 t 4 belgium1,000 t 5 bolivia52 t 6 japan45 t —world total (rounded)36,400 t history realgar alchemical symbol for arsenic the word arsenic has its origin in the syriac word ܙܪܢܝܟܐ zarnika, from arabic al-zarnīḵ الزرنيخ 'the orpiment', based on persian zar 'gold' from the word زرنيخ zarnikh, meaning "yellow" (literally "gold-colored") and hence "(yellow) orpiment". it was adopted into greek as arsenikon (ἀρσενικόν), a form that is folk etymology, being the neuter form of the greek word arsenikos (ἀρσενικός), meaning "male", "virile". the greek word was adopted in latin as arsenicum, which in french became arsenic, from which the english word arsenic is taken. arsenic sulfides (orpiment, realgar) and oxides have been known and used since ancient times. zosimos (circa 300 ad) describes roasting sandarach (realgar) to obtain cloud of arsenic (arsenic trioxide), which he then reduces to gray arsenic. as the symptoms of arsenic poisoning are not very specific, 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". in the renaissance era, arsenic was known as "inheritance powder" due to use in killing family members. the arsenic labyrinth, part of botallack mine, cornwall during the bronze age, arsenic was often included in bronze, which made the alloy harder (so-called "arsenical bronze"). the isolation of arsenic was described by jabir ibn hayyan before 815 ad. albertus magnus (albert the great, 1193–1280) later isolated the element from a compound in 1250, by heating soap together with arsenic trisulfide. in 1649, johann schröder published two ways of preparing arsenic. crystals of elemental (native) arsenic are found in nature, although rare. 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. satirical cartoon by honoré daumier of a chemist giving a public demonstration of arsenic, 1841 in the victorian era, "arsenic" ("white arsenic" or 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. the accidental use of arsenic in the adulteration of foodstuffs led to the bradford sweet poisoning in 1858, which resulted in 21 deaths. wallpaper production also began to use dyes made from arsenic, which was thought to increase the pigment's brightness. two arsenic pigments have been widely used since their discovery – paris green and scheele's green. after the toxicity of arsenic became widely known, these chemicals were used less often as pigments and more often as insecticides. in the 1860s, an arsenic byproduct of dye production, london purple, was widely used. this was a solid mixture of arsenic trioxide, aniline, lime, and ferrous oxide, insoluble in water and very toxic by inhalation or ingestion but it was later replaced with paris green, another arsenic-based dye. with better understanding of the toxicology mechanism, two other compounds were used starting in the 1890s. arsenite of lime and arsenate of lead were used widely as insecticides until the discovery of ddt in 1942. applications agricultural roxarsone is a controversial arsenic compound used as a feed ingredient for chickens. the toxicity of arsenic to insects, bacteria, and fungi led to its use as a wood preservative. in the 1930s, 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 led to a ban of cca in consumer products in 2004, initiated by the european union and united states. however, cca remains in heavy use in other countries (such as on malaysian rubber plantations). arsenic was also used in various agricultural insecticides and poisons. for example, lead hydrogen arsenate was a common insecticide on fruit trees, 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 – replaced lead arsenate in agriculture. these organic arsenicals were in turn phased out by 2013 in all agricultural activities except cotton farming. the biogeochemistry of arsenic is complex and includes various adsorption and desorption processes. the toxicity of arsenic is connected to its solubility and is affected by ph. arsenite (aso3−3) is more soluble than arsenate (aso3−4) and is more toxic; however, at a lower ph, arsenate becomes more mobile and toxic. it was found that addition of sulfur, phosphorus, and iron oxides to high-arsenite soils greatly reduces arsenic phytotoxicity. arsenic is used as a feed additive in poultry and swine production, in particular in the u.s. to increase weight gain, improve feed efficiency, and prevent disease. an example is roxarsone, which had been used as a broiler starter by about 70% of u.s. broiler growers. alpharma, a subsidiary of pfizer inc., which produces roxarsone, voluntarily suspended sales of the drug in response to studies showing elevated levels of inorganic arsenic, a carcinogen, in treated chickens. a successor to alpharma, zoetis, continues to sell nitarsone, primarily for use in turkeys. arsenic is intentionally added to the feed of chickens raised for human consumption. organic arsenic compounds are less toxic than pure arsenic, and promote the growth of chickens. under some conditions, the arsenic in chicken feed is converted to the toxic inorganic form. a 2006 study of the remains of the australian racehorse, phar lap, determined that the 1932 death of the famous champion was caused by a massive overdose of arsenic. sydney veterinarian percy sykes stated, "in those days, arsenic was quite a common tonic, usually given in the form of a solution (fowler's solution) ... it was so common that i'd reckon 90 per cent of the horses had arsenic in their system." medical use during the 17th, 18th, and 19th centuries, a number of arsenic compounds were used as medicines, including arsphenamine (by paul ehrlich) and arsenic trioxide (by thomas fowler). arsphenamine, as well as neosalvarsan, was indicated for syphilis, but has been superseded by modern antibiotics. however, arsenicals such as melarsoprol are still used for the treatment of trypanosomiasis, since although these drugs have the disadvantage of severe toxicity, the disease is almost uniformly fatal if untreated. arsenic trioxide has been used in a variety of ways since the 15th century, most commonly in the treatment of cancer, but also in medications as diverse as fowler's solution in psoriasis. the us food and drug administration in the year 2000 approved this compound for the treatment of patients with acute promyelocytic leukemia that is resistant to all-trans retinoic acid. a 2008 paper reports success in locating tumors using arsenic-74 (a positron emitter). this isotope produces clearer pet scan images than the previous radioactive agent, iodine-124, because the body tends to transport iodine to the thyroid gland producing signal noise. nanoparticles of arsenic have shown ability to kill cancer cells with lesser cytotoxicity than other arsenic formulations. in subtoxic doses, soluble arsenic compounds act as stimulants, and were once popular in small doses as medicine by people in the mid-18th to 19th centuries; its use as a stimulant was especially prevalent as sport animals such as race horses or with work dogs. alloys the main use of arsenic is in alloying with lead. lead components in car batteries are strengthened by the presence of a very small percentage of arsenic. dezincification of brass (a copper-zinc alloy) is greatly reduced by the addition of arsenic. "phosphorus deoxidized arsenical copper" with an arsenic content of 0.3% has an increased corrosion stability in certain environments. gallium arsenide is an important semiconductor material, used in integrated circuits. circuits made from gaas are much faster (but also much more expensive) than those made from silicon. unlike silicon, gaas has a direct bandgap, and can be used in laser diodes and leds to convert electrical energy directly into light. military after world war i, the united states built a stockpile of 20,000 tons of weaponized lewisite (clch=chascl2), an organoarsenic vesicant (blister agent) and lung irritant. the stockpile was neutralized with bleach and dumped into the gulf of mexico in the 1950s. 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 north vietnamese soldiers of foliage cover and rice. 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 coloring agent in sweets. arsenic is used in bronzing and pyrotechnics. as much as 2% of produced arsenic is used in lead alloys for lead shot and bullets. arsenic is added in small quantities to alpha-brass to make it dezincification-resistant. this grade of brass is used in plumbing fittings and other wet environments. arsenic is also used for taxonomic sample preservation. it was also used in embalming fluids historically. arsenic was used as an opacifier in ceramics, creating white glazes. until recently, arsenic was used in optical glass. modern glass manufacturers, under pressure from environmentalists, have ceased using both arsenic and lead. in computers; arsenic is used in the chips as the n-type doping biological role bacteria some species of bacteria obtain their energy in the absence of oxygen by oxidizing various fuels while reducing arsenate to arsenite. under oxidative environmental conditions some bacteria use arsenite as fuel, which they oxidize to arsenate. 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 as ordinary photosynthesis uses water as electron donor, producing molecular oxygen). researchers conjecture that, over the course of history, 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 gammaproteobacterium ectothiorhodospira shaposhnikovii. the mechanism is unknown, but an encoded arr enzyme may function in reverse to its known homologues. in 2011, it was postulated that a strain of halomonadaceae could be grown in the absence of phosphorus if that element were substituted with arsenic, exploiting the fact that the arsenate and phosphate anions are similar structurally. the study was widely criticised and subsequently refuted by independent researcher groups. essential trace element in higher animals arsenic is understood to be an essential trace mineral in birds as it is involved in the synthesis of methionine metabolites, with feeding recommendations being between 0.012 and 0.050 mg/kg. some evidence indicates that arsenic is an essential trace mineral in mammals. however, the biological function is not known. heredity arsenic has been linked to epigenetic changes, heritable changes in gene expression that occur without changes in dna sequence. these include dna methylation, histone modification, and rna interference. toxic levels of arsenic cause significant dna hypermethylation of tumor suppressor genes p16 and p53, thus increasing risk of carcinogenesis. these epigenetic events have been studied in vitro using human kidney cells and in vivo using rat liver cells and peripheral blood leukocytes in humans. inductively coupled plasma mass spectrometry (icp-ms) is used to detect precise levels of intracellular arsenic and other arsenic bases involved in epigenetic modification of dna. studies investigating arsenic as an epigenetic factor can be used to develop precise biomarkers of exposure and susceptibility. the chinese brake fern (pteris vittata) hyperaccumulates arsenic from the soil into its leaves and has a proposed use in