Baby seals at risk from chemicals in mothers’ milk

Baby seals at risk from chemicals in mothers’ milk

Baby seals around the UK coast are at risk from toxic chemicals present in their mothers’ milk, new research has found

Long-lasting chemicals from man-made contaminants have been recognised as harmful to wildlife since the 1970s, with marine mammals facing the biggest threat because they feed at the top of the food chain.

A substance ban designed to stop the damage has been in force since the early 2000s and helped reduce the levels of these chemicals, which enter the environment from the likes of paints, sealants, industrial lubricants, electrical transformers and pesticides.

"Our new research shows that blubber, which is a vital for seals and whales, could be vulnerable to harmful effects at levels much lower than previously thought” - Dr Kimberley Bennett

However a new study, led by Abertay University in Dundee, in partnership with the Sea Mammal Research Unit at the University of St Andrews and colleagues in Belgium, has now shown that ban may not go far enough to protect wildlife.

The team found that the chemicals - known as PCBs (Polychlorinated Biphenyls) and DDT (Dichlorodiphenyltrichloroethane) - can interfere with the way seal blubber tissue works, even at low exposure levels, potentially altering the way pups gain fat vital to their survival.

Part of the so-called “dirty dozen” marine pollutants, these chemicals are banned from production and release into UK waters under the Stockholm Convention, but still make their way into the sea through incineration, effluent and landfill, and can travel a long way from where they were released.

Conducted on the Isle of May in the Firth of Forth, the study, funded by the Natural Environment Research Council (NERC), focused on grey seal pups in their first weeks of life.

Principal investigator, Dr Kimberley Bennett of Abertay University, is concerned that even the relatively low levels found in this study can harm marine mammals in unexpected ways.

She said the chemicals have been locked in the ecosystem, with mother seals accumulating them from fish and passing on the harmful effects to their young through their milk.

“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,” Dr Bennett said.

“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.”

Co-investigators 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.”

To read the full study visit https://pubs.acs.org/doi/10.1021/acs.est.8b04240

To find out more about studying science at Abertay visit https://www.abertay.ac.uk/schools/science-engineering-and-technology/division-of-science/