PCBs Were Banned Three Decades Ago, but They’re Still Hurting Marine Mammals

Don't drink the porpoise milk—it's contaminated.
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A porpoise and calf off of Scotland. (Photo: George Paterson/Flickr)

A porpoise and calf off of Scotland. (Photo: George Paterson/Flickr)

On April 19, 1979, the United States Environmental Protection Agency announced a five-year plan to phase out nearly all uses of polychlorinated biphenyls, or PCBs. The synthetic chemicals had been used in the manufacture of electronic equipment, motor oil, adhesive tapes, paint, and many other products.

“Although PCBs are no longer being produced in this country, we will now bring under control the vast majority of PCBs still in use," EPA administrator Douglas M. Costle boasted at the time. "This will help prevent further contamination of our air, water, and food supplies from a toxic and very persistent manmade chemical."

It turns out Costle celebrated too early—way, way too early. More than 36 years after being banned, PCBs continue to pollute ecosystems, according to a study released in the journal PLoS One. They pose a particular challenge to the survival of marine mammals like porpoises, whales, and dolphins.

Almost 20 percent of the female porpoises had delivered stillborn babies or experienced miscarriages. One in six had tumors or infections in its reproductive organs.

The Europe-based researchers found that PCBs accumulate in the fat tissue of cetaceans and stay with them throughout their lives. Some species of whales live more than 100 years, and many dolphins and porpoises can live 40 to 50 years. So that older individuals would still be carrying a chemical phased out in the overwhelming majority of countries in the 1980s, and banned globally more than a decade ago, is not surprising. But PCBs aren’t limited to cetaceans old enough to know Jacques Cousteau personally. The study found that mother porpoises—and likely other marine mammals—pass the chemicals to their young through their milk.

For those of you who are wondering: Yes, porpoise milk is a real thing. Cetaceans nurse their young just like land mammals do. Unlike the exposed nipples of humans and our closer kin, the mammary glands of dolphins and porpoises are concealed inside of abdominal slits. The mother squirts the milk into the calf’s mouth to account for the difficulty of underwater suckling. I’ve never tasted porpoise milk, but it’s apparently something special. It’s more than 45 percent fat, compared to just 3.5 percent in cow’s milk and four percent in human milk. Porpoise cheese must be a decadent experience.

You might want to stick with the cow stuff, though, because PCBs are pretty nasty. They are probable carcinogens and likely depress the immune, reproductive, neurological, and endocrine systems. And they’re not good for porpoises, either. This new study found that porpoises living in areas most polluted with the chemicals had extremely high rates of reproductive problems. Almost 20 percent of the females had delivered stillborn babies or experienced miscarriages. One in six had tumors or infections in its reproductive organs.

Paul Jepson, a co-author of the study and a veterinarian for the United Kingdom's Cetacean Strandings Investigation Programme, notes that PCB levels in U.K. porpoises initially declined after the country banned the chemicals in 1981, but levels have held steady since 1998. When porpoises will be free from the malign effects of the pollutant is not clear.

Once again, we’re shown just how persistent our industrial waste is. When we dump toxic chemicals into our water, they can harm ecosystems for generations into the future. Sorry, porpoises.

This post originally appeared on Earthwire as “Don't Drink Porpoise Milk” and is re-published here under a Creative Commons license.

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