PCB production was banned in the 70s because of its high toxicity, and is classified as a persistent organic pollutant that bioaccumulates, or is absorbed by organisms at a faster rate than the rate at which it is lost, in animals.
There has been a number of large-scale environmental contamination incidents linked to PCBs. In New York, between 1947 and 1977, GE Company released over a million pounds of PCBs into the Hudson River. This resulted in high levels of PCBs in the local fish, which put fish consumers at an unacceptably high level for health problems.
Beginning in the late 1950s and continuing through 1977, Westinghouse Electric dumped rejected capacitors containing PCBs into area landfills and salvage yards. PCB was also dumped down factory drains, causing contamination of the Bloomington, Indiana sewage treatment plant.
Humans exposed to PCBs can develop a number of adverse health effects. Workers exposed to levels of PCBs have shown blood and urine changes consistent with liver damage. In Japan, PCB contamination of rice bran oil led to a mass poisoning of over fourteen thousand people. Other results consist of irregular menstrual cycles, lowered immune response, and, in children, poor cognitive development.
PCB has also been linked to specific kinds of cancer within humans, such as liver cancer and cancer of the biliary tract. According to the Department of Health and Human Services (DHHS), the United States Environmental Protection Agency (EPA), and the International Agency for Research on Cancer (IRAC), as well as a number of other institutes and organizations, PCBs may reasonably be anticipated to be carcinogens.
PCBs are regulated under the Toxic Substances Control Act, which was enacted into law on October 11, 1976. 40 CFR 761.
PCBs are different that DDT. DDT is a synthetic pesticide, whereas PCBs are man-made organic compounds used