London: Despite regulations and mitigation measures to reduce PCB (polychlorinated biphenyl) pollution, it still poses a great threat to the population of killer whales and dolphins, in European seas, according to a study published online on Thursday in the journal Scientific Reports.
As a chemical once used in electrical gear, paints and flame retardants, PCBs were banned in the US and EU by the end of the 20th century, due to their toxic effect in humans and animals, Xinhua reported.
But the new study, carried out by a team of international researchers, found that the chemicals' bio-magnification in marine food webs continued to cause severe impacts among cetacean top predators, including killer whales and dolphins, in European seas.
The researchers said parts of this PCBs might not be disposed of properly and were slowly leaking into rivers and estuaries from landfills, and eventually into the marine environment.
The team collected and analysed samples from over 1,000 killer whales and dolphins in Europe's waters.
The results showed that PCBs still persisted at dangerously high levels in European cetaceans, which were higher than those found in cetaceans in the waters around America and in the Arctic. Europe's coastal killer whales appeared to be among the hardest hit by the PCB pollution.
The PCB pollution could affect cetaceans' breeding success and newborn calves, said Paul Jepson from Zoological Society of London (ZSL), who is one of the authors of the study.
Cetaceans are mammals, who have a very high-fat milk, so an adult female can offload up to 90 percent of her body burden of PCBs through the milk to the vulnerable calf, he said.
Co-author Robin Law, also from ZSL, urged global policymakers to act quickly and decisively to tackle the toxic legacy of PCBs, before it's too late for these ocean animals.