INESCAPABLE THREAT

Chemical pollution is the most underrated and underreported risk of the 21st century that threatens all species and regions

- ROHINI KRISHNAMURTHY

THE ORCAS or killer whales are the masters of the oceans. With no known natural predators, this formidable creature has been roaming across the world since it evolved from a small, deer-like land animal about 50 million years ago-much before the appearance of the first humans. But this resilient top predator is now teetering on the edge of extinction because of chemical contaminants released by human activities.

Scientists from Canada, Denmark, Norway, Iceland, US and Greenland have conducted a 10-year-long research on orcas of the North Atlantic Ocean. Even though the ranges of the studied individuals were far from human habitations, the scientists have found in the orcas' blubbers (fat layer under the skin) high levels of persistent organic pollutants (POPS)-toxic chemicals used in industrial and agricultural processes. One category of the POPs, the scientists write in Environmental Science and Technology in 2023, are polychlorinated biphenyls (PCBs). Used as coolants and lubricants in electrical components, they were banned in the US and Canada 50 years ago; yet PCBS were present at 10 times the threshold value considered safe for immune systems and fertility rate of orcas.

The blubber samples also contained several other categories of POPs, whose "production, use, and/or release" were to be reduced or eliminated under international environmental treaty Stockholm Convention on Persistent Organic Pollutants, signed in 2001.

The fact is these "persistent" pollutants do not break down easily. Thus they remain in the environment for decades, travel over great distances through water and wind and eventually work their way through the food chain by accumulating in the body fat of species.