Vol. 18  No. 1  Jan. 27, 2006  Next Issue: Feb. 10, 2006
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An unbearable load in the cold

Scientists examining wild polar bear
Scientists tested the fat of 139 polar bears in the Arctic and found high levels of the pollutant PBDEs in their fat.
OTTAWA | Scientists have discovered that toxic chemicals used to fireproof household items like couches are contaminating polar bears. That has federal officials worried about the health of the Arctic.

Polar bears are seen as symbols of Arctic health since they are at the top of the polar food chain.

A Canadian-led team of scientists studied the bears for signs of polybrominated diphenyl ethers in their fat and blood. Also known as PBDEs, these are a class of chemicals used to keep electronic circuit boards, carpets and foam furniture from exploding into flame.

Their study, published this January in the American journal Environmental Science and Technology, is the first to prove that there are heavy loads of the chemicals in bears throughout the Arctic.

Researchers fear that these chemicals could attack the hormonal systems of bears and people, threatening human health and endangering the polar bear.

"This is another in a series of compounds that polar bears are accumulating when they eat," says Andrew Derocher, a co-author of the study and a biologist at the University of Alberta in Edmonton.

A bear of a problem

Derek Muir, a scientist with Environment Canada and head of the study, says PBDEs are similar to polychlorinated biphenyls, or PCBs, another pollutant found in polar bears. Over time, both chemicals leak out of the products they were originally applied to and ride the winds to the Arctic.

PBDEs are a problem because of something called bio-magnification, Muir says. Polar bears need a lot of fat for insulation and get it from their diet of seals. Unfortunately, those seals eat fish and shrimp that absorb PBDEs. The seals cannot digest the chemicals, so they store them in their fat and pass them on to the bears. Since the bears eat a lot more food than the seals, they end up with higher concentrations of PBDEs in their bodies— up to 73 times higher than the seals, according to Muir's study.

'They want to know, "Okay, I've got this seal and I want to bring it home . . . but how do I cut around the contamination so I can feed my family?" The problem is, you can't.'

High doses of PBDEs cause memory loss and erratic behaviour in rats, and may, like PCBs, weaken immune systems and upset levels of sex hormones, creating hermaphroditic bears. Derocher says scientists aren't sure if the chemicals are actually killing bears, but believe the chemicals (and global warming) are sapping the strength they need to reproduce.

The human dimension

Humans absorb PBDEs just like polar bears. A 2003 U.S. study found that concentrations of these chemicals in people around the world jumped 100 times over the last 30 years, but were still far below the levels needed to cause any harm.

The Inuit are worried about these contaminants since they are in many of their traditional foods, such as Arctic char, seal, and polar bear, says Eric Loring, a researcher with Canada's national Inuit group,Inuit Tapiriit Kanatami.

On one hand, he says, contaminants like PBDEs are on the rise in Inuit communities, and could be harmful to their health. On the other, good food is hard to come by in the Arctic. Scare people off traditional foods like seal and polar bear, as happened in the 1980s with fears of PCBs, and they might starve.

"It's frustrating to them," Loring says. "They want to know, 'Okay, I've got this seal and I want to bring it home . . . but how do I cut around the contamination so I can feed my family?' The problem is, you can't."

A solution?

Polar bear cubs
Evidence suggests a ban on PBDEs could save polar bears.

Muir says his study suggests bears can eventually break down PBDEs like people can, given a decade or so: older bears did not have more of the chemicals in them than younger ones, which would be the case if they couldn't get rid of them. As a result, Muir says, if we stop producing the chemicals, concentrations in the bears should fall.

Easier said than done, notes Derocher. "They are probably in the cushion I am sitting on, the carpet in your house, your curtains, clothes. They're everywhere." Large amounts of PBDEs will probably leak into the atmosphere for years to come, he says.

Still, a ban on PBDEs should work given enough time. The European Union banned them in 2004. Muir says Canada is planning to ban them in the near future, meaning manufacturers would have to use other chemicals to fireproof their products. The fact that the main U.S. producer of PBDEs has already replaced them with another product should help matters, he adds.

Muir says people should be careful when introducing new chemicals to the environment. "When you see something in polar bears it means (that thing) has survived a long journey through the Arctic. That's not a good thing, as that means it can accumulate in people much closer to home."

"The Inuit and the polar bear are like the canary in the coal mine," Loring says. "As their health goes, so does the rest of the world, and right now the polar bear is sending out warning signals."

Related Links

Opens in a new windowA study on PBDEs in polar bears [PDF]

Opens in a new windowThe International Joint Commission's report on PBDEs in humans [PDF]

Opens in a new windowThe Department of Indian and Northern Affairs report on contaminants in the North [PDF]

Opens in a new windowInformation on polar bears from the Polar Bear Specialist Group

The bear facts

Ursus maritimus, or "bear of the sea," are the largest land-dwelling carnivores in the world. They have white fur, brown eyes, and black claws, tongues and skin. They moult once a year during the summer.

Polar bears eat mostly seals, and prefer to eat their fat, since they need it for energy and insulation.

There are about 21,500 to 25,000 bears in world, and about 15,000 in Canada.

Source: Environment Canada, IUCN Polar Bear Specialist Group

How heavy is "heavy"?

Physically, not very, according to Derek Muir's study of polar bears: the highest concentration of PBDEs found in bears was about 100 parts per billion, equivalent to about a drop of water in a swimming pool.

Source: Derek Muir, Environment Canada


Inuit Tapiriit Kanatami

Established in 1971, ITK represents Canada's Inuit on a federal and international level. Its name means, "Inuit are united in Canada."

Source: ITK website

Contaminants in the North

A 2003 study by the federal government found potentially dangerous levels of mercury and PCBs in the Inuit.

Scientists are still studying the effects of these pollutants on humans, but aren't advising Arctic residents to cut back on traditional foods; the foods contain nutrients that may actually counteract the effects of these pollutants.

Source: Northern Contaminants Program, Indian and Northern Affairs Canada

Global warming

Scientists say global warming is the biggest threat to the polar bear's survival.

Bear populations around Hudson's Bay are declining because ice floes are breaking up three weeks earlier than they did in the 1970s, cutting into the bears' feeding time. Less food means less energy for reproduction and fewer bears.

The International Union for the Conservation of Nature predicts 30 to 40 per cent of the world's polar bears will be gone in 40 years because of global warming.

Source: Andrew Derocher, University of Alberta

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