More than forty years after the first initiatives were taken to ban the use of PCBs, the chemical pollutants remain a deadly threat to animals at the top of the food chain.
A new study, just published in the journal Science, shows that the current concentrations of PCBs can lead to the disappearance of half of the world’s populations of killer whales from the most heavily contaminated areas within a period of just 30-50 years.
Killer whales (Orcinus orca) form the last link in a long food chain and are among the mammals with the highest level of PCBs (polychlorinated biphenyls) in their tissue. Researchers have measured values as high as 1300 milligrams per kilo in the fatty tissue (blubber) of killer whales. For comparison, a large number of studies show that animals with PCB levels as low as 50 milligrams per kilo of tissue may show signs of infertility and severe impacts on the immune system.
Together with colleagues from a wide range of international universities and research institutions, researchers from Aarhus University have documented that the number of killer whales is rapidly declining in 10 out of the 19 killer whale populations investigated and that the species may disappear entirely from several areas within a few decades.
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