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Lead hydrogen arsenate has been used, well into the 20th century, as an insecticide on fruit trees (sometimes resulting in brain damage to those working the sprayers), and Scheele's Green (a copper arsenate) has even been recorded in the 19th century as a coloring agent in sweets. In the last half century, monosodium methyl arsenate (MSMA), a less toxic organic form of arsenic, has replaced lead arsenate's role in agriculture.The application of most concern to the general public is probably that of wood which has been treated with chromated copper arsenate ("CCA", or "Tanalith", and the vast majority of older "pressure treated" wood). CCA timber 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, where there was a risk of rot, or insect infestation in untreated timber. Although widespread bans followed the publication of studies which showed low-level leaching from in-situ timbers (such as children's playground equipment) into surrounding soil, the most serious risk is presented by the burning of CCA timber. Recent years have seen fatal animal poisonings, and serious human poisonings resulting from the ingestion - directly or indirectly - of wood ash from CCA timber (the lethal human dose is approximately 20 grams of ash). Scrap CCA construction timber continues to be widely burnt through ignorance, in both commercial and domestic fires. Protocols for safe disposal of CCA timber are still in place only patchily; there is concern in some quarters about the widespread landfill disposal of such timber.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 Arsphenamine as well as Neosalvarsan was indicated for syphilis and trypanosomiasis, but has been superseded by modern antibiotics.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 200 years, but most commonly in the treatment of cancer. The Food and Drug Administration in 2000 approved this compound for the treatment of patients with acute promyelocytic leukemia that is resistant to ATRA. It was also used as Fowler's solution in psoriasis.Copper acetoarsenite was used as a green pigment known under many different names, including 'Paris Green' and 'Emerald Green'. It caused numerous arsenic poisonings.Other uses;Various agricultural insecticides, termination and poisons.Gallium arsenide is an important semiconductor material, used in integrated circuits. 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 diodes and LEDs to directly convert electricity into light.Also used in bronzing and pyrotechny.
Table 1. Prohibited pesticidesM&S says the following 79 pesticides are a priority for action and will prohibit their use on produce it purchases throughout the world in a phased approach starting 1 January 2002:UK usage 2-aminobutane, Atrazine, Bromoxynil, Carbaryl, Carbofuran, Chlorfenvinphos, Dichlorvos, Dimethoate, Disulfoton, Endosulfan, Etrimfos, Fenitrothion, Fentin acetate, Lindane, Malathion, Maneb, Methomyl, Methyl bromide, Permethrin, Propoxur, Quintozene, Simazine, Sulphuric acid, Tecnazene, Tridemorph, Vinclozolin.Non UK usage 2,4,5-T, Acetochlor, Alachlor, Aldrin, Antu, Azinphos-methyl, Azobenzene, Binapacryl, Cadmium compounds, Calcium arsenate, Camphechlor, Captafol, Chlordane, Chlordecone, Chlordimeform, Chlorobenzilate, Cyhexatin, DDT, Demeton-S-methyl, Diazinon, Dieldrin, Dinoseb, Dinoterb, DNOC, EDB, EDC, Endrin, Ethiofencarb, Ethylene oxide, Fluoracetamide, HCB, HCH, Heptachlor, Heptenophos, Mephosfolan, Mercury compounds, Methamidophos, Methyl parathion, Monocrotophos, Nitrofen, Parathion, Pentachlorophenol, Phosalone, Phosphamidon, Potassium arsenite, Pyrazophos, Quinalphos, Selenium compounds, Sodium arsenite, 1,1,2,2-tetrachloroethane, Thiometon, Toxaphene, Trichlorfon.
Yes George,arsenic seems to be severely restricted, but not banned, and still a matter of concern for public health: