PCBs (Polychlorinated Biphenyls) are a group of chemicals which were produced in large quantities by companies such as Monsanto, and were widely used in electrical equipment, sealants and paints. Their production was phased out in the mid 1980’s in Europe, and they are now banned by the global Stockholm convention, as they were found to be toxic and to accumulate in wildlife … [Read more...] about Killer whales under threat from persistent PCB chemicals, yet emissions continue