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Washington DC, September 30: Chemical pollutants, banned more than 40 years ago, still have a devastating effect on marine life and could result in the demise of half of the world's population of killer whales before the end of the century .
According to a new study, killer whales, or orcas, are the most exposed to polychlorinated biphenyls (PCBs), formerly widely used as coolants and carbonless paper production before being highly toxic and carcinogenic.
PCB production was banned in the United States in 1979, but it is still used in many parts of the world and should not be completely phased out until 2025.
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.
Orcs are the last link in a long food chain and are therefore among the most affected by this problem during their 50 to 80 years of existence.
The researchers found that PCB concentrations of up to 1,300 milligrams per kilogram in the fat of some orcas have shown that only 50 milligrams per kilogram can cause problems with infertility and the immune system.
The results are published in the Journal of Science.
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