SEAL pups in Scottish waters are being poisoned by toxic chemicals present in their mothers' milk.
Researchers in Dundee say that the contamination comes from man-made waste draining into the sea which causes changes to how the juvenile mammals gain the fatty blubber they need to survive.
Scientists are now warning the dangerous toxins could lead to extinction of the animals from the UK coast.
It comes as the first rescued pups of the season were released from the SPCA's National Wildlife Centre in Fishcross, Clackmannanshire.
READ MORE: Jet skiers deliberately driving at seals in north-east Fife
A ban designed to stop the toxic chemicals getting into the sea - from sources such as paint, pesticides, electrical transformers and lubricants - is not working, according to a study led by Abertay University in Dundee.
The research, in partnership with the Sea Mammal Research Unit at the University of St Andrews and Belgian academics, has now shown the ban introduced in the early 2000s may not go far enough to protect wildlife.
Scientists found that even low levels of the fat-altering chemicals known as PCBs (Polychlorinated Biphenyls) and DDT (Dichlorodiphenyltrichloroethane) in the sea are putting the lives of pups at risk.
The study, conducted on the Isle of May in the Firth of Forth, focused on grey seal pups in their first weeks of life.
PCBs were banned in the late 70s amid fears about their toxicity.
READ MORE: On the breeding beach with Scotland's grey seals
Recent estimates suggest that Europe produced between 299,000 and 585,000 tonnes of PCBs. But while industry has stopped using the chemicals, millions of tonnes of the chemicals continue to be in circulation.
While PCBs are no longer produced, they are extremely hardy as they were designed to resist extreme heat.
Principal investigator, Dr Kimberley Bennett of Abertay University, explained how the chemicals have become locked in the ecosystem, with mother seals accumulating them from fish and passing on the harmful effects to their young through their milk.
Dr Bennett said: "We've known for a long time that high levels of these chemicals are very dangerous and can hamper reproduction and immunity in marine mammals.
"They may even drive some populations towards extinction.
"Efforts to reduce levels in the environment have been successful. But our new research shows that blubber, which is a vital for seals and whales, could be vulnerable to harmful effects of PCBs and DDT at levels much lower than previously thought."
Although the so-called "dirty dozen" chemicals are banned from being produced and released into UK waters under the Stockholm Convention, they are still finding their way into the sea through sewage and landfill.
The contaminants were found to harmful to wildlife since the 1970s, with marine mammals facing the biggest threat because they feed at the top of the food chain.
Dr Kelly Robinson and Prof Ailsa Hall of the University of St Andrews Sea Mammal Research Unit added: "We have already shown that these chemicals can reduce the likelihood that a seal pup will survive to its first birthday.
"We've now discovered why this is the case and how these toxins add to the seals' burden of potential health effects."
Meanwhile, Scotland’s animal welfare charity released two rescued seals at Silver Sands beach in Aberdour ,after each had been taken into its care following reports from the public.
READ MORE: Record year for birth of grey seal pups around east coast
This year pups in the wildlife centre have been given Harry Potter-themed names, with the first two dubbed Hermione and Hufflepuff.
Centre Manager Colin Seddon said, “Hermione and Hufflepuff were our first releases of the season.
“Hermione was quite the size, weighing 45.3kg. She was rescued from Dunglass beach in the Borders on Sunday 25th November by our Inspector Jenny Scott.
“It was quite the rescue as Hermione was so heavy and the tide was not on their side.
“Jenny was bitten by Hermione so this is a stern reminder for the public not to approach or allow dogs near seals on the beach.
“Hermione would have felt stressed and threatened and the bite is a result of that."
He added: “If you spot a pup with a white coat on a public beach, please contact our animal helpline as chances are, it is in trouble and needs our attention. Do not go near it.
“Grey seal pups which no longer have a white coat may still need our assistance if they are on a public beach and at risk, or have visible signs of injury, such as bleeding, crusty or damaged eyes, discharge from the nose, coughing or generally looking unwell.
“The public should contact our animal helpline and an operator will be able to assist. If the seal pup is not at risk and looks and acts healthy it should be left alone.”
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