PCBs belong to the 12 toxic chemicals called the POPs (Persistent Organic Pollutants). The POPs consist of pesticides (e.g. DDT, Lindan), industrial chemicals (e.g. PCBs) and by-products (dioxins and furans), which are unintentionally formed and released from thermal processes involving organic matter and chlorine as a result of incomplete combustion or chemical reactions.
Although PCBs had already been synthesised in 1866 for the first time, the commercial production only began in 1929 by the American Monsanto-Chemical Company under the trade name «Askarel». In Western Europe, PCBs were particularly used between 1950 and 1983.
The outstanding dielectric characteristics of the PCBs were later clouded by their bad impact on the environment. The extinction of otters in Switzerland, for example, was caused by PCB contamination. If PCBs are exposed to heat and/or fire the highly toxic chemical PCDD, better known as dioxin, can be formed.
PCBs were mainly used as cooling fluids in electrical equipment like transformers and capacitors, the so-called «closed systems».
In the 60s and 70s, however, PCBs were also used as chemicals in the building industry in so called «open systems». The main application field was the use as plasticiser in sealants.
Coatings, paints and impregnation agents (ceiling boards or protective paints) can also contain PCBs (see «open systems»).
More than 1.5 million tons of PCBs were produced worldwide, and a high percentage has already found its way to the environment. Technical equipment, products and buildings still hold a considerable reservoir of PCBs. Due to the ignorance of such contamination, the materials are not usually defined as hazardous waste. Consequently, the pollutant can be released into the environment by improper removal, dumping or inexpert incineration.