Polychlorinated biphenyl << `pol` ee KLAWR uh `nay` tihd by FEHN uhl >> (PCB) is any of a group of synthetic compounds formed by substituting atoms of chlorine for atoms of hydrogen in a compound called biphenyl. A PCB molecule may have from 1 to 10 chlorine atoms.
PCB’s once were widely used in the United States in manufactured products. In 1979, however, the United States government prohibited the production of PCB’s because of concerns about the effects of PCB’s on people. Scientific studies had shown that high concentrations of PCB’s may cause birth defects, cancer, liver damage, and nerve disorders. Manufacturers used PCB’s in such products as paints and adhesives and in fluids for lubricating industrial machinery. PCB’s also were used as insulators in transformers, capacitors, and other electrical equipment.
