ALDRIN

one of the several isomers (compounds with the same composition but different structures) of hexachlorohexahydrodimethanonaphthalene, a chlorinated hydrocarbon used as an insecticide. Aldrin was first prepared in the late 1940s and is manufactured by the reaction of hexachlorocyclopentadiene with bicycloheptadiene (both derived from hydrocarbons obtained from petroleum). Aldrin stimulates the central nervous system and is toxic to warm-blooded animals; poisoning can result from ingestion, inhalation, or absorption through the skin. The insecticide dieldrin is made from aldrin by treatment with peroxyacetic acid. Isodrin, a stereoisomer of aldrin, is made from cyclopentadiene and hexachlorobicycloheptadiene; it has insecticidal properties similar to those of aldrin and can be treated with peroxyacetic acid to form another insecticide, endrin, a stereoisomer of dieldrin. Aldrin, dieldrin, isodrin, and endrin, along with other chlorinated hydrocarbons, are being discontinued as insecticides because of their injurious effects on other animals that become exposed to them.