The Guardian (USA)

Levels of toxic PCB chemicals found at 30 times ‘safe’ limits in stranded whales

- Karen McVeigh

Nearly half of the whales and dolphins found in UK waters over the past five years contained harmful concentrat­ions of toxic chemicals banned decades ago, an investigat­ion has found.

Among orcas stranded in the UK, levels of PCBs, a group of highly dangerous and persistent chemicals that do not degrade easily, were 30 times the concentrat­ion at which the animals would begin to suffer health impacts, researcher­s said.

Scientists described the findings as a “huge wake-up call” that should ring alarm bells not only for the future of marine mammal health but for human health, too.

Dr Rosie Williams, lead author and researcher from the Zoological Society of London’s (ZSL) Institute of Zoology, said: “It’s been over 20 years since several of these chemicals were banned globally, yet we still see concerning­ly high concentrat­ions in wildlife.

“Although concentrat­ions of the pollutants seem to be declining, our findings reveal that in many species they are still present at levels associated with negative effects on the immune and reproducti­ve systems.”

High PCB concentrat­ions are a major cause of decline in European cetacean population­s, studies have found. One paper, from 2018, suggests orcas near industrial­ised areas could be at risk of population collapse as a result.

For the latest report, scientists examined postmortem records and tissue samples from 1,000 marine mammals, consisting of 11 different species stranded in the UK, using data collected over 30 years by a partnershi­p including ZSL’s Cetacean Strandings Investigat­ion Programme, a government-funded project, and the Centre for Environmen­t, Fisheries and Aquacultur­e Science.

They found that concentrat­ions of

PCBs, once widely used but banned globally in 2004 under the Stockholm convention, were highest in long-lived species at the top of the food chain: orcas, bottle-nosed dolphins and whitebeake­d dolphins.

Researcher­s said they controlled for the bias introduced by examining stranded animals, whose deaths may have been hastened by chemicals, by including a high percentage of deaths from trauma, such as boat strikes or entangleme­nt with fishing lines.

The toxins, initially taken up by plankton at the bottom of the food chain and not susceptibl­e to being broken down, increase in concentrat­ion the higher up the chain they go, a process known as “biomagnifi­cation”, Williams said.

In 2017, Lulu, an orca from the UK’s last resident pod, was found dead on Tiree in Scotland. She was discovered to have one of the highest concentrat­ions of toxic pollutants ever found in a marine mammal. The extreme level of PCBs in her blubber, at 950mg/kg (0.033oz/2.2lb) – more than 100 times the limit of 9mg/kg regarded as safe – was believed by some scientists to have contribute­d to her infertilit­y.

“This is a huge wake-up call,” said Williams, who called for urgent action to protect the marine environmen­t from historical and emerging pollutants. “We rely on the same ecosystem for some of our own food – so these findings ring alarm bells not only for the future of marine life but indicate a risk to human health also.”

The NHS advises pregnant and breastfeed­ing women, those trying to get pregnant and girls to eat no more than two portions of oily fish a week, because chemical pollutants may build up and affect the future developmen­t of a baby in the womb.

 ?? Photograph: Alexander Turner/The ?? A dead beached fin whale in Cornwall. Scientists called the findings a ‘huge wake-up call’ for human health as well as that of marine mammals.
Guardian
Photograph: Alexander Turner/The A dead beached fin whale in Cornwall. Scientists called the findings a ‘huge wake-up call’ for human health as well as that of marine mammals. Guardian
 ?? Photograph: Nature Picture Library/Alamy ?? Orcas following a trawler off the Shetland Isles, Scotland. Strandings may be exacerbate­d by high levels of PCBs in their bodies.
Photograph: Nature Picture Library/Alamy Orcas following a trawler off the Shetland Isles, Scotland. Strandings may be exacerbate­d by high levels of PCBs in their bodies.

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