PCBs off West Africa High levels of polychlorinated biphenyls (PCBs) have been detected along the coasts of West Africa, the scientists who discovered the pollutants suggest that they could come from the illegal dumping of waste or from an enormous ship breaking yard in Mauritania. PCBs were used years as dielectric fluids in electrical transformers, condensers and as coolants for various devices. However, production was banned in the US in 1979 because of toxicity and carcinogenicity concerns and because they are persistent environmental pollutants. They have also been banned since 2001 under the Stockholm Convention on Persistent Organic Compounds. Rosalinda Gioia of Lancaster University, UK, and colleagues have identified PCBs at concentrations of 10 to 360 picograms per cubic meter in some countries of West Africa, such as Gambia and Ivory Coast, and all along this coast.