Arsenic Trioxide

Arsenic trioxide is an inorganic compound with the formula As4O6, a white solid that melts at about 312 degrees Celsius. Most of it is a by-product of processing other ores: roasting arsenopyrite, a common impurity in gold and copper ores, releases it, and roasting orpiment also yields it. Industrially it goes into wood preservatives, pesticides, and colourless glass, and with copper acetate it gives the green pigment Paris green. As a medicine it is given by injection to treat acute promyelocytic leukaemia. In traditional Chinese medicine it was used under the name pi-shuang, "arsenic frost", and some discredited patent medicines, such as Fowler's solution, held arsenic compounds. It is poisonous to living things: swallowing as little as 100 milligrams can be fatal, and long exposure, in smelter workers or from arsenic-rich drinking water, causes the chronic poisoning called arsenicosis. Many countries regulate its manufacture and sale.