Polychlorinated biphenyls or PCBs refer to a group of up to 209 chemical compounds that were widely used as coolants and insulators for a variety of industrial and commercial purposes. These compounds have unique properties that make them particularly useful for capacitors, transformers, and other electrical equipment. PCBs are known to have electrical insulating qualities, and are nonflammable and able to withstand very high temperatures. Aside from electrical tools and construction materials, PCBs were also used for a variety of commercial products like flameproof Christmas trees.
Before the U.S. government imposed a ban against the use and manufacture of PCBs in 1979, these widely used chemical mixtures were solely produced by the agrochemical company Monsanto under the brand name Aroclor. Monstanto monopolized the PCBs market for almost 4 decades until controversy regarding its safety to human health and the environment came to light. It was soon found that Monsanto had long been aware of the toxicity problem of the product they were manufacturing. In fact, internal communications that surfaced during a long legal battle showed that they actively tried to hide the devastating effects caused by PCB contamination to water sources near their Anniston, Alabama chemical plant. Because of public pressure, the production of Monsanto PCBs came to a full stop two years before the federal ban.
Today, the health risks associated with PCB exposure have been well-researched and established by the scientific community. The Environmental Protection Agency recognizes PCBs as probable human carcinogen. They also point out that prolonged PCB exposure can cause other non-cancer health conditions. In particular, researchers have found that PCBs can affect the immune, nervous, endocrine, and reproductive systems of animals and humans. PCB exposure is also known to cause liver damage and chloracne, a severe acne-like skin irritation. Some studies on animals also found that PCB can cause birth defects and other fetal health issues.