PCB (polychlorinated biphenyls), Dioxins (polychlorinated dibenzo-p-dioxins), and Furans (polychlorinated dibenzofurans) are groups of persistent organic pollutants (POP) that have similar toxicity and share chemical characteristics. Dioxins and Furans are created as combustion byproducts during the production of certain chemicals such as pesticides, and in the pulp and paper industry during chlorine bleaching. Until their ban in 1979, PBC were manufactured as insulator fluids in heat-exchangers and transformers, as hydraulic fluids, and as additives to paints and oils. PCB remain in the environment even though they are no longer manufactured.
Exposure to these compounds can be highly toxic to humans when breathing contaminated air, drinking contaminated water or eating contaminated food. About 90% of exposure comes from eating contaminated food as these compounds tend to bioaccumulate in fatty tissues of animals. These pollutants have been shown to cause a skin condition called chloracne, liver problems, and elevated blood lipids in people who have been unintentionally exposed to large amounts. Extensive laboratory studies have also shown various effects on animals, including cancer and reproductive problems.