Polychlorinated biphenyl PCB (polychlorinated biphenyls) in 1929, until the late 70 's a synthetic organic compound used on the North American business, although Canada did not produce this chemical, but has also been widely used in electrical equipment, heat exchangers, hydraulic systems and other special applications.
After decades later did people realize PCB-pollution of the global environment, which is a mixture of various chlorinated biphenyls, does great harm to the human body. Canada Government has taken measures to eliminate PCB, but in 1977 in Canada illegally importing, processing, and sales of PCB, PCB in 1985 and their illegal releases into the environment, and Canada's Constitution allows owners of PCB equipment continued to use the PCB until the life cycle of the device. Since 1988 Canada provincial governments began to PCB storage, transportation and destruction were provided.
PCB does not break down easily in the environment and is spreading very far, PCB production, processing, use, transportation and waste processing into air, soil and rivers and seas, small marine organisms and fish PCB inhaled, and they also become food for marine life, so that the PCB enters the body of all marine life, including marine mammals. PCB accumulation in organism is that it's content in the water of thousands of times.