Polychlorinated biphenyls (PCBs)

One of several aromatic compounds containing two benzene nuclei with two or more substituent chlorine atoms. They are colorless, toxic, viscous liquids. Because of their persistance and ecological damage from water pollution, their manufacture has been discontinued in the US (1976). (New York State Department of Environmental Conservation, In-Water and Riparian Management of Sediment and Dredged Material, November 2004)