Arsenic is a naturally occurring element in the earth’s crust with a long history of use as a constituent of commercial and industrial products, as a component in pharmaceuticals, and as an agent of deliberate poisoning. Recent commercial applications of arsenic include its use in the manufacture of semiconductors, wood pre-servatives for industrial applications (eg, marine timbers or utility poles), nonferrous alloys, glass, gel-based insecticidal ant baits, and veterinary pharmaceuticals. In some regions of the world, ground-water may contain high levels of arsenic that has leached from natural mineral deposits. Arsenic in drinking water in the Ganges delta of India and Bangladesh is now recognized as one of the world’s most pressing environmental health problems. Arsine, an arsenous hydride (AsH3) gas with potent hemolytic effects, is manu-factured predominantly for use in the semiconductor industry but may also be generated accidentally when arsenic-containing ores come in contact with acidic solutions.
It is of historical interest that Fowler’s solution, which contains 1% potassium arsenite, was widely used as a medicine for many conditions from the eighteenth century through the mid-twentieth century. Organic arsenicals were the first pharmaceutical antimi-crobials∗ and were widely used for the first half of the twentieth century until supplanted by sulfonamides and other more effective and less toxic agents.
Other organoarsenicals, most notably lewisite (dichloro-[2-chlorovinyl]arsine), were developed in the early twentieth cen-tury as chemical warfare agents. Arsenic trioxide was reintroduced into the United States Pharmacopeia in 2000 as an orphan drug for the treatment of relapsed acute promyelocytic leukemia and is find-ing expanded use in experimental cancer treatment protocols . Melarsoprol, another trivalent arsenical, is used in the treatment of advanced African trypanosomiasis .