Tuesday, July 15, 2008

Toxic chemical levels finally dropping in Arctic food animals, new study shows

Posted by Neill Abayon

After decades of concern about southern pollutants poisoning traditional foods that northern aboriginals depend on, a new government study suggests levels of toxic chemicals in a wide range of animals across the Arctic are finally dropping.

The study, the first large-scale attempt in a decade to measure contaminants in common Arctic food animals, found carcinogens such as PCBs and other toxins derived from pesticides sprayed in the south have largely levelled off or have begun declining.

"Organochlorines, like DDT or chlordane or toxaphene or industrial chemicals like PCB, are declining," said project leader Laurie Chan of the University of Northern British Columbia. "That's good news."

However, the study found that mercury, probably from the increasing use of coal in power generation around the globe, remains stubborn and is even rising in some animals.

Still, Chan said, the falling organochlorine levels are proof that international agreements on limiting the use of toxic chemicals can produce real improvements in food safety.

"It seems that the Stockholm Convention is having some effect," Chan said.

That convention - heavily pushed by Canada - came into effect in 2004 and limited the use of the so-called "dirty dozen" chemicals pushed into the Arctic and concentrated there by global air currents.

At one time, Canada's Inuit had some of the highest PCB levels in the world, up to 10 times the levels found in southern Canada. The chemical was even found in the breast milk of Inuit mothers.

A 2003 study found subtle but statistically significant nervous system and behavioural changes in Inuit babies that may be linked to PCBs.

But now, PCB levels in beluga, narwhal, walrus and ringed seal have fallen by an average of 43 per cent since 1997. Although it varies in different parts of the Arctic, the amount of the chemical that Inuivialuit or Inuit people are exposed to has dropped by an average of 20 per cent over the last decade.

Similarly, human exposure to toxaphene - an insecticide that can damage the lungs, nervous system and kidneys - has fallen an average of one-third across the Arctic.

The results from Chan's group, which are currently being prepared for publication in a scientific journal, echoed a smaller study released last fall.

That study found average PCB levels in the blood of pregnant women from 14 communities in the northwestern Northwest Territories fell 24 per cent between 2000 and 2007.

Mercury remains a problem. Levels of the toxic metal increased 42 per cent in ringed seal flesh, although the average exposure increase for humans was marginal.

"We don't see any decrease in mercury across the board," Chan said.

"The major source of mercury is air pollution, from coal-fired power generation. We know that is increasing all the time."

The study is good news for aboriginal people in the North, many whom still depend on food they harvest from the land and sea. A 2006 survey of 45 communities across the Canadian North suggested that between 20 and 30 per cent of the diet of aboriginal northerners consists of so-called country food.

Nutritionists say such foods are often healthier than the highly processed - and highly expensive - foods available in northern groceries.

Still, Chan acknowledges there's still more work to do. His research, for example, didn't include caribou, which many northerners eat on a near-daily basis.

A comprehensive health survey of all coastal Inuit communities is underway which will measure actual contaminant blood levels. That study, which is being done by researchers on the Coast Guard icebreaker CCG Amundsen, is complete for Nunavut and the results are expected next summer.

A similar survey in communities on the north coast of the Northwest Territories as well as Labrador will be conducted this summer.


1 comment:

yuva said...

your site is interesting to visit!!!!!
Have a look on my two sites too.......