Polychlorinated biphenyls (PCBs) are organo-halogens, a class of chemical compounds that contain two or more chlorine atoms attached to a bonded pair of benzene rings. When improperly disposed or burned, PCBs are highly carcinogeni (cancer causing) and lipophilic . This means they persist indefinitely in the body fat of living organisms and are easily passed on to other creatures through the food chain. First developed in 1881, PCBs were introduced into American industry on a large scale in 1929, and since then their commercial use has been widespread. They are nonflammable, chemically stable, heat resistant, and have low electrical conductivity. PCBs are also thick, odorless, colorless, and inert. These properties made PCBs very attractive to industry.

PCBs were first used to insulate electrical transformers and as hydraulic fluids. Their applications multiplied as electricity became the primary industrial power source, and eventually included transformers (especially those used on...