- Wildlife researchers have found new evidence that Arctic
polar bears, already gravely threatened by the melting of their habitat
because of global warming, are being poisoned by chemical compounds commonly
used in Europe and North America to reduce the flammability of household
furnishings like sofas, clothing and carpets.
-
-
- Polar bears - the world's largest bears - are facing
a bleak future because of global warming and experts want them declared
a vulnerable species. (Photo: The Age)
-
- A team of scientists from Canada, Alaska, Denmark and
Norway is sounding the alarm about the flame retardants, known as polybrominated
diphenyls, or PBDEs, saying that significant deposits have recently been
found in the fatty tissues of polar bears, especially in eastern Greenland
and Norway's Svalbard islands.
-
- Studies are still being carried out on what impact the
chemicals might be having on the bears, but tests on laboratory animals
such as mice indicate that their effects can be considerable, attacking
the sex and thyroid glands, motor skills and brain function.
-
- There is also evidence that compounds similar to the
PBDEs have contributed to a surprisingly high rate of hermaphroditism in
polar bears. About one in 50 female bears on Svalbard has both male and
female sex organs, a phenomenon scientists link directly to the effects
of pollution.
-
- "The Arctic is now a chemical sink," declared
Colin Butfield, a campaign leader for the Worldwide Fund for Nature, which
last month indicated that killer whales in the Arctic were also suffering
from elevated levels of contamination with fire retardants as well as other
man-made compounds. "Chemicals from products that we use in our homes
every day are contaminating Arctic wildlife."
-
- The pollutants are carried northwards from industrialised
regions of the US and western Europe on currents and particularly on northbound
winds. Contaminated moisture often condenses on arriving in the cold Arctic
climes and is then deposited, ready to enter the food chain.
-
- For several years, scientists have observed how the concentrations
of the pollutants are magnified as they ascend the food chain, from plankton
to fish and then to marine mammals such as seals, whales and polar bears.
The new study, first published last month in the journal Environmental
Science and Technology, shows, for instance, that one compound was 71 times
more concentrated in polar bears than in the seals they normally feed upon.
-
- Conservationists are especially alarmed by these new
findings because of the already fragile condition of the Arctic polar bear
populations, some of which could be devastated before the end of the century.
As warming temperatures erode their hunting grounds, polar bears in Canada's
western Hudson Bay region, for instance, saw their numbers slide from 1,100
in 1995 to only 950 in 2004.
-
- The dangers now posed by the PBDEs are reminiscent of
the crisis 30 years ago over PCBs - polychlorinated biphenyls - a highly
toxic by-product of many industries that was also found to be migrating
to the Arctic. The dumping of PCBs was swiftly banned. Since 2004, manufacturing
has stopped in the US of two of the most toxic retardants, called penta
and octa. Stockpiles of both still exist, however.
-
- According to Derek Muir, of Canada's Environmental Department
and a leader of the new research, there are signs of a slightly different
retardant, typically used in construction materials and furnishings, also
showing up in the Arctic and in the bears, called HBCD. "It's a chemical
that needs to be watched, because it does biomagnify in the aquatic food
webs and appears to be a widespread pollutant."
-
- The research team tested 139 bears captured in 10 different
locations across the Arctic region. They found that the bears in Norway's
Svalbard, a wildlife refuge where all hunting is banned, had 10 times the
levels of the chemicals than bears in Alaska and four times those in Canada.
-
- http://www.commondreams.org/headlines06/0110-01.htm
|
