Agricultural Roxarsone is a controversial<unk>  compound used as a feed ingredient for chickens. The toxicity of<unk>  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<unk> . An increased appreciation of the toxicity of<unk>  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).<unk>  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<unk>  – replaced lead arsenate in agriculture. These organic<unk> als were in turn phased out by 2013 in all agricultural activities except cotton farming. The biogeochemistry of<unk>  is complex and includes various adsorption and desorption processes. The toxicity of<unk>  is connected to its solubility and is affected by pH.<unk> e () is more soluble than arsenate () 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<unk>  phytotoxicity.<unk>  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<unk> , a carcinogen, in treated chickens. A successor to Alpharma, Zoetis, continues to sell nitarsone, primarily for use in turkeys.<unk>  is intentionally added to the feed of chickens raised for human consumption. Organic<unk>  compounds are less toxic than pure<unk> , and promote the growth of chickens. Under some conditions, the<unk>  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<unk> . Sydney veterinarian Percy Sykes stated, "In those days,<unk>  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<unk>  in their system." Medical use During the 17th, 18th, and 19th centuries, a number of<unk>  compounds were used as medicines, including arsphenamine (by Paul Ehrlich) and<unk>  trioxide (by Thomas Fowler). Arsphenamine, as well as neosalvarsan, was indicated for syphilis, but has been superseded by modern antibiotics. However,<unk> als 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.<unk>  trioxide has been used in a variety of ways over the past 500 years, 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<unk> -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<unk>  have shown ability to kill cancer cells with lesser cytotoxicity than other<unk>  formulations. In subtoxic doses, soluble<unk>  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<unk>  is in alloying with lead. Lead components in car batteries are strengthened by the presence of a very small percentage of<unk> . Dezincification of brass (a copper-zinc alloy) is greatly reduced by the addition of<unk> . "Phosphorus Deoxidized<unk> al Copper" with an<unk>  content of 0.3% has an increased corrosion stability in certain environments. Gallium<unk> e 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<unk>  poisonings. Scheele's Green, a copper arsenate, was used in the 19th century as a coloring agent in sweets. *<unk>  is used in bronzing and pyrotechnics. * As much as 2% of produced<unk>  is used in lead alloys for lead shot and bullets. *<unk>  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. *<unk>  is also used for taxonomic sample preservation. *<unk>  was used as an opacifier in ceramics, creating white glazes. * Until recently,<unk>  was used in optical glass. Modern glass manufacturers, under pressure from environmentalists, have ceased using both<unk>  and lead.
Arsenic
Vinyl chloride
Sybil 
Metaldehyde
Basilicon
Lewis lead
Mercury
Lead