Polychlorinated Biphenyls are a class of synthetic organic chemicals. Since 1930 PCBs were used for a variety of industrial uses (mainly as dielectric fluids in capacitors and transformers but also as flame retardants, ink solvents, plasticizers, etc.) because of their chemical stability. PCBs are fire resistant, have a low electrical conductivity, high resistance to thermal breakdown and a high resistance to oxidants and other chemicals. When researches in the 1970s found out that these characteristic that made them a popular additive represented a serious threat to human health and the environment, their production was gradually stopped. PCBs are considered to be immunotoxic and affect reproduction. Adverse effects associated to the exposure of PCBs are damage to the immune system, liver, skin, reproductive system, gastrointestinal tract and thyroid gland.
Around 1.7 million tonnes of PCBs were produced between 1929 and 1989 and a lot of the equipment containing PCBs is still in use somewhere or stocked awaiting final disposal. As PCBs once released into the environment do not break down but travel over long distances and continue to pose health risks to humans, it is important to remove them from use and destroy existing stockpiles. Existing PCBs can be destroyed through the breaking of their molecular bonds by the input of either chemical or thermal energy. The most common method is high temperature incineration, though other non-incinerative methods like declorination exist.