The Montrose Chemical Corporation of California was a chemical corporation that was the largest producer of the insecticide DDT in the United States from 1947 until it stopped production in 1982. Its improper disposal of chemical waste from DDT production resulted in serious environmental damage to the Pacific Ocean near Los Angeles, and its former main plant in Harbor Gateway South area of Los Angeles near Torrance, California has been designated as a Superfund site by the United States Environmental Protection Agency.