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The Persistent Killer of Killer Whales


Killer whales are at risk due to PCB contamination despite a near-global ban more than 30 years ago. The threat affects more than half of the world’s orcas, and whale populations near industrialised regions and at the top of the food-chain are at a high risk of population collapse over the next 100 years.

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This valuable study in Science ( extends previous work within the author team, which found alarming levels of polychlorinated biphenyls (PCBs) in North Atlantic killer whales, and further, found these levels to have an immunotoxicological impact. The author team showed that PCB-mediated effects on reproduction and immune function threaten the long-term viability of more than 50% of the world’s killer whale populations. Indeed, in a number of populations today there is strong evidence of reduced fertility and even complete cessation of reproduction.

PCBs manufacture has been tightly regulated worldwide for more than a decade, yet the legacy of these chemicals remains a constant environmental threat for high trophic level consumers such as killer whales. Further, 10 million new chemical substances are produced every year for application in everything we consume and use. As such, the effects of known harmful chemicals, such as PCBs, must be considered in the context of the cocktail of chemicals humans and wildlife alike are exposed to daily, for which toxicity is yet to be properly evaluated.

Associate Professor Susan Bengtson Nash is Director of the Southern Ocean Persistent Organic Pollutants Program at Griffith University.

Polychlorinated biphenyls...

The full text of this article can be purchased from Informit.