Polychlorinated biphenyl

Polychlorinated biphenyls (PCBs) are a group of man-made chemicals that were widely used in the past, notably in coolant fluids. PCBs are toxic to humans and the environment, and are classified as persistent organic pollutants (POPs).

History

PCBs were first synthesized in the late 19th century. Commercial production started in 1929 but their use has been banned or severely restricted in many countries since the 1970s because of the possible risks to human health and the environment.

Production and use

PCBs were used for a wide range of applications because of their chemical stability, low flammability, and electrical insulating properties. They were used in coolants and lubricants in transformers, capacitors, and other electrical equipment. The manufacture of PCBs was banned in the U.S. in 1979 due to evidence of environmental and health risks.

Health effects

Exposure to PCBs can lead to skin conditions such as acne and rashes. Studies in workers exposed to PCBs have shown changes in blood and urine that may indicate liver damage. In 2013, the International Agency for Research on Cancer (IARC) classified PCBs as human carcinogens.

Environmental effects

PCBs are persistent organic pollutants that resist breaking down in the environment. They can travel long distances and have been found in snow and sea water far from where they were released. They can accumulate in the leaves and above-ground parts of plants and food crops. They are also taken up by small organisms and fish and move up the food chain.

See also

• Persistent organic pollutant
• Toxicity
• Environmental health

References

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  Chemical structure of Polychlorinated biphenyl

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  PCB warning sign on power supply transformer

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  Diagram of PCB with labels

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  Diagram showing biomagnification of PCBs

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  Label indicating presence of PCBs

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  Power supply transformer with PCB warning

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  Sign warning about fish contamination with PCBs