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| Scientists tested the fat of 139 polar bears in
the Arctic and found high levels of the pollutant PBDEs in their fat.
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OTTAWA | Jan.27, 2006 — 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?
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| 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." 
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A
study on PBDEs in polar bears [PDF]