FIVE THINGS

What to know about chemical cocktails found in polar bears by researchers in Hudson Bay 1 Persistent pollutants

Biologists have long known polar bears and other Arctic animals carry toxic chemicals known as persistent organic pollutants (POPs) in their bodies. Those chemicals damage immune, digestive and reproductive systems. Now new tests have found a wide range of previously undiscovered contaminants in polar bears around Hudson Bay.

2 210 chemicals found

Environment Canada researcher Robert Letcher and his colleagues tested for 295 POPs. They found 210 “with some frequency” in fat and liver samples collected from 41 bears harvested in 2013-14 from the western and southern shores of Hudson Bay.

3 Levels vary widely

The levels of contamination varied widely among the chemicals. Most were found in the range of parts per billion. Some, such as one chemical used as a water repellent for fabrics, were approaching parts per million.

4 It’s widespread

Some of the contaminants such as PCBs and DDT were restricted under the 2001 Stockholm Convention and have long been in decline. Levels of flame-retardant chemicals also seem to be dropping. But others don’t seem to be declining at all, despite being on the convention’s list for nearly a decade. The fact they’ve been found in a top-of-the-food-web predator suggest they’re widespread in the environment, Letcher said.

5 Climate change

Understanding the impact of the chemicals is complicated by the context of Arctic climate change, said Letcher, who is conducting further research.“It’s a major challenge for us to understand how climate change variables are affecting contaminant exposure.”