Jan 15, 2016 11:20 AM EST By Russell Westerholm, UniversityHerald Reporter

Though PCBs have been banned in Europe since the 1970s, they are linked today to threatening orca whales and dolphins with extinction.

According to BBC News, PCBs were most common in electrical gear, paints, and flame retardants. Despite their ban some 40 years ago for their toxicity, PCBs are more present in European oceans' crustaceans than anywhere else in the world's waters.

The researchers published their study in the journal Scientific Reports.

"The long life expectancy and position as apex or top marine predators make species like killer whales and bottlenose dolphins particularly vulnerable to the accumulation of PCBs through marine food webs. Our findings show that, despite the ban and initial decline in environmental contamination, PCBs still persist at dangerously high levels in European cetaceans," study lead author Paul Jepson, a specialist wildlife veterinarian at the Zoological Society of London's Institute of Zoology, said in a news release. "Few coastal orca populations remain in western European waters. Those that do persist are very small and suffering low or zero rates of reproduction. The risk of extinction therefore appears high for these discrete and highly contaminated populations. Without further measures, these chemicals will continue to suppress populations of orcas and other dolphin species for many decades to come."

PCBs are highly resilient and some experts believe Europe's wildlife might be suffering because the European Union banned them later than other places in the world. Orca whales appear to be suffering the most, as the researchers noted five calves in two pods of 36 killer whales survived between 1999 and 2011.

"Our research underlines the critical need for global policymakers to act quickly and decisively to tackle the lingering toxic legacy of PCBs, before it's too late for some of our most iconic and important marine predators," study co-author Robin Law said in the release. "We also need to better understand the various pathways through which these iconic species are able to accumulate such high PCB concentrations through their diets."

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