[Mike]

from rocky
http://www.smh.com.au

Toxins threaten polar bears
January 17, 2006

LOS ANGELES: Already imperiled by melting ice and a brew of toxic
chemicals, polar bears throughout the Arctic, particularly in remote
dens near the North Pole, face an additional threat as flame
retardants originating largely in the US are building up in their
bodies, an international team of wildlife scientists says.

The flame retardants are one of the newest additions to hundreds of
industrial compounds and pesticides carried to the Arctic by winds and
ocean currents. Accumulating in the fatty tissues of animals, many
chemicals grow more concentrated as larger creatures eat smaller ones.

In urban areas, particularly in North America, researchers have shown
that levels of flame retardants called polybrominated diphenyls, or
PBDEs, are growing at a rapid pace in people and wildlife. Although
they have been found in much lower concentrations in the Arctic,
scientists say their toxic legacy will persist there for years because
they are slow to break down, particularly in cold climates.

In polar bears, the effects are unknown. But in tests on laboratory
animals, PBDEs disrupted thyroid and sex hormones and damaged
developing brains, impairing motor skills and mental abilities,
including memory and learning.

Scientists say that other industrial chemicals with properties similar
to PBDEs are already weakening the bears’ immune systems, altering
their bone structure and skewing their sex hormones.

Derek Muir from Canada’s National Water Research Institute, who led
the new research, said the geographical patterns in contamination
suggest that the east coast of North America and north-western Europe
are the primary sources of the flame retardants.

Los Angeles Times