DDT
DDT was supposed to be the magic bullet vs. the scourge of insect-borne diseases like malaria. Discovered in 1873, DDT (short for the less catchy dichloro-diphenyl-trichloroethane) wasn't used widely until 1939, when Swiss chemist Paul Hermann Muller noted its effectiveness as a pesticide during World War II, a discovery that earned him a Nobel Prize in 1948. After the war, use exploded: from 1942 to 1972, some 1.35 billion lb. of DDT were used in the U.S.
But absent from the DDT mania was consideration of the environmental effects of dumping millions of pounds of potent pesticides each year. Rachel Carson's seminal 1962 environmental tract Silent Spring was the first to call attention to the nasty little fact that DDT produced fertility and neurological problems in humans and accumulated up the food chain in wildlife, poisoning birds. Use of the compound plummeted, and in 1972, DDT was banned in the U.S. entirely.