SWAN Village-to-Village Messaging System: Dog Fur Reveals Mercury Pollution

Dog Fur Reveals Mercury Pollution

Posted by Margaret on 3/21/2008, 3:11 pm
12.46.50.194

Dog Fur Reveals Mercury Pollution

By Emily V. Driscoll, Scienceline

posted: 21 March 2008 ET
Add to delicious del.icio.us
Digg It! Digg It!
Save to Newsvine Newsvine
Add to reddit reddit
Yahoo! Buzz
0 Comments | 3 Recommend
A husky sled dog. Scientists can monitor levels of
mercury pollution with clippings of hair. Credit: Jim
Doeden
Full Size
Previous Image Next Image
1 of 1

A husky sled dog. Scientists can monitor levels of
mercury pollution with clippings of hair. Credit: Jim
Doeden

A sled dog's thick fur coat may do more than protect
it from inclement weather: Scientists say it can be
used to detect mercury contamination in the
environment — and possibly even in humans.

"The foods sled dogs are eating are scraps left over
from people in the villages," said Peter Bowers, an
archaeologist at Northern Land Use Research, an
Alaskan consulting firm, who contributed to a study
published in the journal Science of the Total
Environment in October.

Since the sled dog's fish diet is similar to that of
Alaska's indigenous population, scientists believe the
racing huskies can provide a unique insight not only
into how much mercury humans are eating, but also into
where the toxin enters the food chain. Other animals
like caribou and coyotes may not be as suited to
predict the element in humans because they are
difficult to follow and have different diets. Mercury
levels in fish change depending on their location and
feeding habits, and testing dog hair from different
husky populations that eat those fish shows scientists
the areas of high mercury.

The researchers analyzed hair from huskies in five
regions of Alaska; they also analyzed a sample from
sled dog remains dating back to 780 A.D. Of the
present-day dogs feasting on salmon, those from
Russian Mission, Alaska — a village near the Bering
Sea — had the most mercury, topping out at more than a
third of the toxic level. Hair samples taken from dogs
at Fort Yukon, 800 miles from the sea, had the lowest
mercury levels, which were not significantly different
from the control group. In contrast, archaeological
samples had roughly half the mercury of the lowest
modern-day sample.

"The levels of [present-day] mercury decreased as you
go up the Yukon and away from the mouth of the Bering
Sea," said Kriya Dunlap, the lead author of the study
and a chemist at the University of Alaska, plus a
championship sled dog racer to boot. According to
Dunlap, salmon fast when they move inland.

Salmon become contaminated from eating plankton and
algae tainted with mercury from pollution. They have
difficulty metabolizing the toxin, so it builds up in
their systems and gets passed on to anything that eats
them — including sled dogs and people. Dogs with more
mercury were found closer to the sea where the salmon
feed. "It makes sense because the salmon aren't eating
[further inland]," Dunlap said. Mercury accumulates in
fats and proteins, and when the fish aren't eating,
they burn off those same fats and proteins for energy.
This helps to eliminate the toxin, and may be why
fasting fish have less mercury.

Sled dog fur is not the only mechanism to measure
mercury. Scientists can also study mercury levels in
human and animal organs, blood, breath and hair.
Mercury gets into hair through the blood that
follicles need to grow hair. Scientists have used hair
to test for minerals for about 75 years.

The researchers studied mercury in sled dogs because
it's difficult to get permission to test on people,
according to Dunlap. When they do manage to get hair
samples from people, scientists can learn about
mercury deposits. Human hair grows one centimeter a
month, so scientists can track where a person has
traveled and compare it with different parts of his or
her hair, according to Lori Verbrugge, an
environmental toxicologist with the Alaska Public
Health Laboratory.

The hair testing method has a big advantage over
testing organs, both in people and dogs. "Hair is a
pretty good indicator of mercury ... and you don't
have to kill the animal," said Verbrugge.

The archaeological samples of sled dog hair show that
mercury also occurs naturally in the environment, like
in geologic deposits and volcanic ash. But the recent
increase has researchers worried. "Global change
contaminates the environment and a large population
[in Alaska] still relies heavily on traditional food,"
said Dunlap.

This article is provided by Scienceline, a project of
New York University's Science, Health and
Environmental Reporting Program.

* What's Your Environmental Footprint?
* 10 Ways to Green Your Home
* Top 10 Most Polluted Places