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Polychlorinated Biphenyls (PCBs)
Kodavanti, P. Polychlorinated Biphenyls (PCBs). Chapter 0, Online Module, Neuroscience and Biobehavioral Psychology. ELSEVIER, AMSTERDAM, Holland, , N/A, (2017).
Polychorinated biphenyls (PCBs), originally termed "chlorinated diphenyls", were first synthesized in the early 1880s by Schmidt and Schultz (1881) and were commercially produced beginning in 1929. The manufacturing levels of PCBs increased with the demand of the electrical industry for a safer cooling and insulating fluid for industrial transformers and capacitors. PCB formulations sold in the commercial market have had varied trade names; for example, Aroclor was the most common trade name in the United States and Great Britain. PCB mixture formulations were different depending on the country of origin, and were produced in Germany (Clofen}, France (Phenoclor and Pyralene, Japan (Kanechlor), Italy (Fenclor),Russia (Sovol) and Czechoslovakia (Delor). The mixtures were named according to their chlorine content. Millions of tons of PCBs have been produced worldwide - around 700,000 tons in the USA before they were banned following two major poisoning incidents, first in Japan in 1968 and ten years later in Taiwan. It has been estimated that more than 1.2 x 109 kg of PCBs have been manufactured throughout the world; 3.7 X 108 kg of PCBs have already been released into the environment, and an additional 7.8 X 108kg are still available for release from transformers or other commercial products.
Polychlorinated biphenyls (PCBs) are a group of man-made organic chemicals and have been widely used as coolants and lubricants in transformers, capacitors, and other electrical equipment. Food contamination is probably the single most significant source of human exposure. Studies in humans and animals have indicated that neurological development is one of the primary targets of PCBs. The effects included impaired visual recognition, depressed responsiveness,and IQ deficits. Since PCBs persist in the environment and bioaccumulate in the food chain, steps should be taken to reduce unnecessary exposures to protect the human population from the possible long-term health effects.