/ 19 October 2018

Chemical killing the killer whales

Poison: PCBs become increasingly concentrated as they move up the food chain
Poison: PCBs become increasingly concentrated as they move up the food chain, leading to the death of orcas in oceans off industrialised countries. (George Karbus Photography)

Orcas, or killer whales (Orcinus orca) have been around for 11-million years. An apex predator, only humans dare hunt them. Evolved to live in every ocean on Earth, they are the perfect killing machine. But an industrial lubricant is going to wipe out half of all orca populations — even though it has been banned for 30 years.

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This is according to research published in the journal Science at the end of last month. Predicting global killer whale population collapse focused on the effect of one pollutant, polychlorinated biphenyls.

Discovered in the 1880s as a byproduct from burning coal, biphenyl was a miracle lubricant. The pale-yellow liquid could conduct heat, wouldn’t catch fire and stayed liquid at room temperature. Any heavy machinery that moved and got hot while moving was lubed up.

So much of it was used that biphenyls can still be found in the feathers of stuffed birds from the early 1900s. About 1.5-million tonnes were produced for use in the United States and Europe.

Then people started getting sick. Long-term exposure poisoned employees in the factories that made biphenyls. In Japan, 14 000 people became ill after eating rice bran that had been contaminated by the lubricant. Doctors linked it to damage to the thyroid and central nervous system.

In the US, production was banned in 1978, but it took until 2001 for a global treaty — the Stockholm Convention — to stop most other countries from using and producing it. South Africa passed legislation in 2014 that required companies to register their plans to destroy their stockpiles.

Big companies around the world have until 2025 to stop using it. Until then, it leaks into rivers and oceans. This gets picked up by plants and fish in the oceans. These are then eaten by other fish.

Orcas specialise in eating the fish that eat the fish that eat these plants, with most of their 200kg daily intake coming from tuna, sharks and seals.

The Science research looked at the level of biphenyls in the blubber of orcas. Very little of this research has been done before, with more attention focused on the drop in population levels of whales across the world. This new research found that biphenyls also transmit from mothers to their children in nutrients that are shared through the placenta and breast milk.

Of the 19 orca populations the researchers looked at, 10 were “at high risk of collapse over the next 100 years”. Biphenyls are mostly to blame. Orcas are also being squeezed out of their niche by people. Overfishing means they have less food to hunt, and noises from vessels are interfering with their ability to communicate underwater.

Worst affected by biphenyls are orca families living in the oceans around the US and Europe. The only population groups that are expanding are “those in the less-contaminated waters of the Arctic and Antarctic”. The researchers didn’t look at orca population levels around South Africa, but they did note that the country had used biphenyls at industrial scale — so there would inevitably be pollution in the surrounding oceans.

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Worryingly, the researchers found a range of other pollutants in the orcas’ blubber. These included flame retardant chemicals and acids used to feed chemical reactions. They said: “This raises concerns about the potential for other persistent contaminants to generate additional toxic injury” for other species that live for a long time, and are at the top of the food pyramid.

The plight of the killer whales is a warning of what happens when people pollute without thinking about the consequences that could follow decades — and even centuries — later.