A new University of Toronto study is using polar bear scat to reveal how certain chemical contaminants can become trapped—and build up—inside the body.
Polar bears are prone to storing certain contaminants in their bodies because they are at the top of the food chain, have a very fatty diet and have evolved to absorb high amounts of fat.
“They’re like a trap for these chemicals,” says Frank Wania, a professor in department of physical and environmental science at U of T Scarborough who was one of the study’s authors.
“Their contaminant intake is very high, but their ability to expel it is very low.”
For the study, published in the journal Environmental Science & Technology, Wania and Ph.D. student Yuhao Chen developed a new method to study how certain chemicals, called polychlorinated biphenyls (PCBs), accumulate inside polar bears from contaminated food. They analyzed the diet and fecal samples of polar bears from the Toronto Zoo to see what quantity of PCBs get trapped compared to how much gets excreted.
Polar bears experience what’s known as bio-magnification, where greater levels of toxins accumulate higher up in the food chain. Since polar bears are at the top, they’ve consumed the highest level of contaminants in their diet. (A polar bear has higher levels of contaminants than the seal it eats, the seal has more than a cod, the cod more than a small fish etc.)
Lead Image: Researchers at U of T Scarborough developed a new method to study how PCBs accumulate inside polar bears after they eat contaminated food. Credit: Vaclav Sebek/Shutterstock.
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