What Are Polychlorinated Biphenyls (PCBs)?

PCBs, or polychlorinated biphenyls, are a class of highly toxic chemical compounds widely used in construction materials and electrical products in many buildings from the 1950s until their phase-out in 1978. These chemicals may still be present in products and materials produced before the 1979 PCB ban.

Prior to the 1979 ban, PCBs entered the environment during their manufacture and use in the United States. Today they can still be released into the environment from poorly maintained hazardous waste sites that contain PCBs; illegal or improper dumping of PCB wastes; leaks or releases from electrical transformers containing PCBs; and disposal of PCB-containing consumer products into municipal or other landfills not designed to handle hazardous waste. PCBs may also be released into the environment by the burning of some wastes in municipal and industrial incinerators.

Once in the environment, PCBs do not readily break down and therefore may remain for long periods of time cycling between air, water, and soil. PCBs can accumulate in the leaves and above-ground parts of plants and food crops. They are also taken up into the bodies of small organisms and fish. As a result, people who eat fish may be exposed to PCBs that have bioaccumulated in the fish they are ingesting.

Virtually every person alive today has some amount of PCBs in their bodies. PCBs can pass from mother to child during pregnancy or later, through breast milk. You can also ingest PCBs by eating animal products. Once PCBs enter your body, they can stay there for decades. In general, the longer you live, the more PCBs build up in your system.