Decades after they were banned, chemicals known as PCBs continue to pose a threat to marine mammals in the waters off Europe. The situation is especially dire for killer whales, the Christian Science Monitor reports. "We think there is a very high extinction risk for killer whales as a species in industrialized regions of Europe," says Paul Jepson, who led a study on the effects of PCBs (or polychlorinated biphenyls, which were widely used in plastics, paints, electrical equipment, and building materials before being banned) on orcas, dolphins, and porpoises. Researchers took samples from 1,000 animals, the BBC reports, and found that PCB contamination persists at "dangerously high levels." "Europe is a big big hotspot," Jepson says, adding that PCBs seem to negatively affect breeding success and newborn calves.
A nursing calf can end up ingesting up to 90% of its mother's PCB contamination, Jepson explains. West of Scotland and Ireland, he tells the BBC, there are only eight killer whales left, and they haven't produced a calf in many years: "So that population will go extinct." Another two pods of 36 orcas in southern Europe suffer from low birthrates and are also at risk of extinction. "And then," Jepson says, "That is it." Europe produced about 300,000 tons of PCBs from 1954 to 1984. They were banned in the US in 1979, the UK in 1981, and the rest of Europe in 1987. Researchers believe the toxic chemicals are leaching from landfills and ending up in the ocean, where they work their way up the food chain. Global policymakers, say researchers, must put new regulations on how materials containing PCBs are stored and disposed of. (Some good news: Killer whales in the waters of the Pacific Northwest appear to be rebounding.)