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This has led to PCB infiltration into the oceans, where they pose a particular risk to marine mammals at the top of the food chain, such as orcas. Because chemicals do not break down easily, their concentration increases in the body of predators as they eat more and more fish contaminated with PCBs.
For mammals, PCB contamination is intergenerational, with mothers transmitting chemicals to their offspring through milk.
Orcas are the last link in a long food chain and are therefore among the most affected by this problem in their 50 to 80 year old lives.
"Absolutely tragic"
The researchers found that the effects of PCBs on fertility and immunity had devastated many populations, resulting in a rapid decline in the number of killer whales in 10 of the 19 populations studied.
"The results are surprising, and we find that more than half of the studied populations of killer whales in the world are seriously affected by PCBs," said Jean-Pierre Desforges of the University of Aarhus in Denmark.
Desforges added that it was "scary to see that models predict a high risk of population collapse in these areas by 30 to 40 years from now.
Due to the long life of whales, high levels of PCBs released into the environment decades ago still have an effect, which will only increase as fatal pollutants continue to spread. 39 to be produced and used.
But co-author of the study, Paul Jepson, of the UK's Institute of Zoology, said current efforts "have not been effective enough to prevent PCB buildup in so many species. than killer whales ".
"There is therefore an urgent need for new initiatives than those of the Stockholm Convention," said Jepson in a statement.
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