The production and use of toxic synthetic chemicals called polychlorinated biphenyls (PCBs) were banned internationally more than 40 years ago. There is a great deal of evidence that they are carcinogens and hormone disrupters in mammals and can cause birth defects.
PCBs can build up in the tissues in increasing amounts over time (bioaccumulate) in long-lived animals and people exposed to them. They also biomagnify in the environment meaning they build up in food chains – smaller animals take them into their tissues, those are then eaten by larger animals (such as fish), which themselves are eaten by humans and marine mammals such as dolphins and seals living in Britain’s waters.
