UK Whales and Dolphins at risk of extinction due to high levels of industrial toxin PCBMumbai, Jan 18(AZINS) According to a study released last week, European killer whales and bottlenose and striped dolphins are subject to the greatest levels of the banned industrial chemical Polychlorinated biphenyl (PCB.)

This man-made substance was at one time used widely in coolant fluids for electric machines, as dielectrics in batteries and in heat transfer fluids. However owing to its subsequent classification as an environmental toxin, its production was banned in America in 1979 and then by the Stockholm Convention on Persistent Organic Pollutants in 2001.

However over time, the presence of the substance in natural habitats has hindered the ability for whales and dolphins near the UK to bear offspring, to the extent that large numbers of these creatures have in recent years vanished or are on the brink of extinction.

In the study which was published in the Scientific Reports journal, researchers collated data on concentrations of PCBs in tissue samples from 1,081 aquatic mammals that harbour porpoises, striped and bottlenose dolphins, and killer whales with the animals coming from regions encompassing Ireland, France, Spain and UK. Even with the dangerous substance being banned for such decades, it was discovered that these PCBs were present in far higher levels in their bodies that can be considered safe. It is not known why this is so, given that the substance’s naturally occurring presence has seen a continual decline since the 80s.

“The answer to that is neither easy nor straightforward,” said Paul Jepson of the Zoological Society of London. “But mitigation measures should really involve dealing with historic and current industrial uses in old equipment—transformers and things, in electrical equipment—PCBs leaking out of landfill into rivers, PCBs in marine sediments, which are often dredged to keep shipping lanes open, which makes them more bioavailable to get into the marine food chains.”

One explanation could be the fact that PCBs tend to accumulate within body fat after ingested, implying these affected creatures could carry them in their blubber. To exacerbate the issue, these chemicals are resilient enough to pass on to other creatures--for example if they are ingested by higher-order predators, or when nursing females suckle their offspring.

This proliferation has a wider, more detrimental effect on the health of the ecosystem, which has contributed to the dwindling of these species in the region.