Asian pesticides turning up in local lakes 

No danger to humans, but may pose a risk to wildlife

An Environment Canada researcher made a startling discovery in two of Whistler’s biggest lakes – the presence of toxaphene, a toxic insecticide that has never been licensed for used in Canada, and was banned in the United States more than 20 years ago.

Biologist Patrick Shaw made that discovery and others in a study of rainbow trout fat cells from 18 different lakes that drain into the Georgia Basin. Five of the lakes were on Vancouver Island, and four more were in the Lower Mainland. The other lakes were located in remote areas along the coast as far north as Powell River, and about halfway up the Fraser Valley.

The two Whistler lakes in the study, Cheakamus Lake and Garibaldi Lake, showed the highest concentrations of toxaphene, plus the presence of other toxins like PCBs and DDT.

Health Canada has not established safe consumption levels for toxaphene because it’s not supposed to be here, but Shaw believes that the levels he detected were significantly higher than Health Canada’s alert levels.

"With the absence of guideline levels, Health Canada alert levels are typically about 10 nanograms per gram of tissue," says Shaw. "In most lakes around B.C. we would find levels of about five nanograms per gram of tissue, but in Garibaldi (and Cheakamus lakes) the level is about 160 nanograms.

"The numbers we got wouldn’t prevent me from eating a few fish out of the lakes up there now and then, but they were surprisingly high."

According to Shaw, the real risk arises from a process known as bioaccumulation. Predators that live off of fish that have concentrations of toxins, such as bald eagles, osprey and minks, will rapidly accumulate dangerous levels of the toxins in their bodies. At every stage of the food chain, the accumulation of toxins is more pronounced.

That can lead to birth defects, illness, and even death. Rachel Carson first documented the theory of bioaccumulation in her book Silent Spring, which linked the demise of the eagle population to the bioaccumulation of the pesticide DDT.

But if toxins like taxaphene, PCBs and other organic chlorines are banned in Canada, how do they wind up in Whistler lakes?

According to Shaw, the toxins originated in Asia, where they are still being used, and brought across the ocean to North America by the Pacific Transfer air current.

"When it snows, (the toxins) are scoured out of the air and deposited on our local glaciers," explains Shaw. "When the glaciers melt, the toxins get concentrated in our lakes."

The more it snows, the more potential there is to accumulate airborne toxins.

The process has been well-documented in Canada, and especially in our northern regions where toxins are trapped in the area by the cold and snow.

These toxins show up in lakes and species of animals around the world, according to Shaw, but concentrations can be reduced over time as governments ban toxic compounds.

While there’s little that can be done to lower the levels of toxaphene in Cheakamus and Garibaldi lakes, which share many of the same glaciers, Shaw hopes that the Canadian government can use his report to exert pressure on foreign governments to sign on to the 1979 Convention on Long-Range Transboundary Air Pollution on Persistent Organic Pollutants, or the POPs international protocol. More than 90 countries have signed the POPs protocol since it was introduced at the United Nations in 1998.

POPs covers a dozen chemicals that pose health risks for humans, wildlife and the environment. They are Aldrin, Hexachlorobenzene, Chlordane, Mirex, DDT, Toxaphene, Dieldrin, Polychlorinated biphenyls (PCBs), Endrin, dioxins, heptachlor and furans.

According to Shaw, a tracking experiment discovered that toxins can travel from central Asia to Canada in about five days.

"The only thing that really moves faster is an airplane," he says.

The Environment Canada study was conducted to find out what contaminants were turning up in the areas as a result of the Pacific Transfer air current. There are no immediate plans for follow-up studies or continued monitoring, says Shaw, although he believes they may be possible after his report is published.

"It wouldn’t be a bad idea," he says. "What this is is a wake-up call to be more careful in what we spread around," says Shaw.

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