DDT found in BC high alpine lakes
REVELSTOKE, B.C. July 14, 2010 – Dangerously high levels of DDT have been detected in the seldom-visited high alpine lakes of Mount Revelstoke National Park. How did the chemical get there? Nobody really knows, although scientists say they have theories.
TheRevelstoke Times Review explains that Health Canada advised that fish caught in the high lakes not be eaten because the fish contain up to 16 times more DDT than the agency recommends.
Only a dozen or so fishing permits were issued for the high lakes last year, indicating the advisory won’t affect that many people. But the issue does hit close to home, as the community has been considering a ban on what are called “cosmetic” herbicides and pesticides applied to achieve aesthetic landscaping goals.
Parks Canada, the administrator of the national park, has two theories that might explain the DDT presence. One theory holds that the DDT was deposited in the 1960s when it was used as an insecticide. It does not readily break down and can remain in the environment for a century.
A second theory sees more distant, even global sources. The theory holds that DDT can evaporate along with water and then be redeposited elsewhere. But if a lake remains frozen well into July, as is the case in Mount Revelstoke National Park, then the water in which the DDT is found has little opportunity for evap- oration and deposition elsewhere.
DDT was banned in Canada in 1972 because, among other reasons, it weakens the egg shells of raptors.The Revelstoke area has osprey and bald eagles.
Sarah Boyle, a conservation biologist with Parks Canada, says that this case illustrates why Revelstoke and other communities should carefully evaluate scientific evidence about long-term effects of chemicals such as Roundup.
“I think that is a really good example of what happens when we use persistent chemicals in the environment (without knowing) how long they last and what the legacy effects are. And I don’t think it’s worth the ecological or human health risks,” she said.
