They also go by the brand names Aroclor, Phenoclor and Kanechlor. PCBs were first commercially produced in 1929 by the Swan Corporation, which went on to become part of Monsanto.

Polychorinated biphenyls are created by heating benzene enough to bond two rings together. This creates diphenyl, which, when exposed to chlorine gas, forms chlorinated diphenyl. Exposing it to more or less chlorine gas gives us polychlorinated biphenyls.

PCBs conduct heat well, but do not burn, and they are insulators as far as electricity is concerned. For this reason, they are used in large electrical transformers and capacitors.

PCBs are soluble in fat, but not in water. For this reason, they spread up the food chain. In humans, PCBs can cause cancer, birth defects, small penis size, decreased sperm count, and numerous other negative effects.