Seals living off the coast of the UK face a threat to their survival from toxic chemicals that are ending up in pups’ milk, a new study has revealed.

Despite bans on the substances in question, which range from paint additives to pesticides, they are still finding their way into the ocean from sewage and landfill sites.

Scientists are warning the contaminants trigger changes in the way pups gain the fatty blubber they need to survive.

Researchers from Abertay University in Dundee found even low levels of the fat-altering chemicals, known as PCBs and DDT, in the sea are putting the lives of pups at risk.

The research, in partnership with the sea mammal research unit at the University of St Andrews and Belgian academics, confirms the ban – introduced in the early 2000s – may not go far enough to protect wildlife.

Conducted on the Isle of May in the Firth of Forth, the study focused on grey seal pups in their first weeks of life.

Group leader Dr Kimberley Bennett 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.

“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,” she said.

“They may even drive some populations towards extinction.

Plastic waste across the world: in pictures Show all 15 1 /15 Plastic waste across the world: in pictures Plastic waste across the world: in pictures A father and son on a makeshift boat made from styrofoam paddle through a garbage filled river as they collect plastic bottles that they can sell in junkshops in Manila. The father and son team earn some three US dollars a day retrieving recyclables from the river. AFP/Getty Plastic waste across the world: in pictures A composite image of items found on the shore of the Thames Estuary in Rainham, Kent. Tons of plastic and other waste lines areas along the Thames Estuary shoreline, an important feeding ground for wading birds and other marine wildlife. Getty Images Plastic waste across the world: in pictures Children collect plastic water bottles among the garbage washed ashore at the Manila Bay. According to the United Nations Environment Programme, at current rates of pollution, there will likely be more plastic in the sea than fish by 2050. AFP/Getty Plastic waste across the world: in pictures Plastics and other detritus line the shore of the Thames Estuary. In December 2017 Britain joined the other 193 UN countries and signed up to a resolution to help eliminate marine litter and microplastics in the sea. It is estimated that about eight million metric tons of plastic find their way into the world's oceans every year. Once in the Ocean plastic can take hundreds of years to degrade, all the while breaking down into smaller and smaller 'microplastics,' which can be consumed by marine animals, and find their way into the human food chain. Getty Plastic waste across the world: in pictures A dump site in Manila in 2013. The Philippines financial capital banned disposable plastic shopping bags and styrofoam food containers, as part of escalating efforts across the nation's capital to curb rubbish that exacerbates deadly flooding. AFP/Getty Images Plastic waste across the world: in pictures Children swims in the sea full of garbage in North Jakarta, Indonesia. Getty Plastic waste across the world: in pictures An Indian woman holds a jar filled with Yamuna river water polluted with froth and toxic foam to be used for rituals at the river bank in New Delhi, India. The Yamuna River, like all other holy rivers in India, has been massively polluted for decades now. The river that originates in a glacier in the pristine and unpolluted Himalayas, and flows through Haryana, Delhi and Uttar Pradesh before merging with the Ganges River in Allahabad, once used to be the lifeline of the Indian capital. Currently, it is no more than a large, open sewer that is choking with industrial and domestic discharge that includes plastic, flowers and debris and has virtually no aquatic life. EPA Plastic waste across the world: in pictures Plastic waste is washed up on South Troon beach in Scotland. Recent reports by scientists have confirmed, plastics dumped in the world oceans are reaching a dangerous level with micro plastic particles now being found inside filter feeding animals and amongst sand grains on our beaches. Getty Plastic waste across the world: in pictures Children collect plastic to be sold and recycled, in a polluted river in suburban Manila. The city's trash disposal agency traps solid waste floating down waterways that was thrown into the water by residents of slums along riverbanks upstream. AFP/Getty Plastic waste across the world: in pictures View of the Carpayo Beach in La Punta, Callao, some 15 km of Lima. In 2013, the NGO VIDA labeled the Carpayo Beach as the most polluted in the country - 40 tons of trash on each 500m2. AFP/Getty Plastic waste across the world: in pictures Trash from Kamilo Beach in Hawaii. Gabriella Levine/Flickr Plastic waste across the world: in pictures A scavenger collects plastic cups for recycling in a river covered with rubbish near Pluit dam in Jakarta. Reuters Plastic waste across the world: in pictures Rubbish fills Omoa beach in Honduras. Floating masses of garbage offshore from some of the Caribbean's pristine beaches are testimony to a vast and growing problem of plastic pollution heedlessly dumped in our oceans, locals, activists and experts say. AFP/Getty Plastic waste across the world: in pictures A man climbs down to a garbage filled river in Manila. Plastic rubbish will outweigh fish in the oceans by 2050 unless the world takes drastic action to recycle the material, a report warned in 2016. AFP/Getty Plastic waste across the world: in pictures Garbage on East Beach, Henderson Island (Pitcairn Islands), in the south Pacific Ocean. The uninhabited island has been found to have the world's highest density of waste plastic, with more than 3,500 additional pieces of litter washing ashore daily at just one of its beaches. EPA

“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 entering the oceans.

The contaminants have been seen as 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 said: “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.”

These results were published in the journal Environmental Science and Technology.

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Concern about pollution in the ocean has shot up as public awareness of plastic waste has grown, and there have been several high-profile cases of seals harmed by plastic debris.

However scientists are also concerned plastic fragments may add to the burden of dangerous chemical pollution in waterways, as these small objects are often contaminated with substances they have picked up either during manufacture or from the environment.

Some preliminary studies have suggested that chemicals found in plastic may have an impact on animal behaviour.