An immortal poison - the history of PCB

PCB (Polychlorinated Biphenyl) refers to a range of 209 manufactured compounds that served a variety of industrial purposes. They are very stable compounds that do not degrade easily. They were developed in the 1920s and introduced by the Monsanto Corporation into many compounds to give them qualities such as fire resistance, electrical insulation and improved pliability. They were extremely useful and came to be used very widely with no apparent drawbacks. However, industry used them carelessly and large quantities leaked (or were dumped) from factories into the environment, most seriously into rivers and lakes. They entered the food chain through fish and water-dwelling wildlife from where they went on to contaminate every living organism. Blood tests of 27 major countries’ environment ministers found 55 different PCBs present.

The toxicity of PCBs came to prominence when they were accidentally added to cooking oil in Japan with horrific consequences for those who consumed the oil. This led to widespread testing of humans and other mammals around the world and the scale of the contamination came to light. It was subsequently found that some of the worst contamination was of unborn foetuses whose mothers had been exposed. Studies demonstrated that contaminated children’s brain development is impaired.

PCBs were banned around the world in the late 1970s/ early 1980s and are now no longer produced. Unfortunately they degrade extremely slowly, so the PCBs that are already present in our environment will remain there for many generations.

National curriculum links:           

·          Geography KS3: 1e, 4b, 5a, 5b, 6j, 6k

·          Geography KS4 (humanities entitlement statement)

·          Design & technology KS3: 3c

·          Design & technology KS4: 1b, 3c

·          Citizenship KS3: 1i

·          Citizenship KS4: 1f, 1j

·          Science KS3: 1c

·          Science KS4 (breadth of study): 1a, 1c