Mercury pollution has adverse impacts on human and ecosystem health. Mercury is transformed in water bodies and wetlands into methylmercury, which accumulates in fish and bio-magnifies up the food chain. Fish contaminated with mercury are poisonous to the creatures that consume them. The first loon death directly attributed to mercury poisoning was witnessed in Kejimkujik National Park, Nova Scotia, where mercury is linked to loon reproductive failures. It takes only one gram of mercury (a little more than is found in a single car switch) to contaminate a 20 acre lake to levels where the fish are unsafe for consumption.

Mercury pollution in Canada's North has led to dangerously high levels of mercury in Canadian aboriginal peoples. The UN estimates that mercury toxicity has caused learning disabilities and impaired the nervous system of millions of children worldwide.

In an effort to mitigate the impacts of mercury pollution, mercury laden fish consumption warnings are now issued for 90 percent of lakes in Ontario and Eastern Canada, the North-eastern United States, and the US Midwest. Health Canada, the US Food and Drug Agency, and other organizations have also recommended limiting intake of large, predator ocean-fish, particularly for children and women of childbearing years.

The Minamata Tragedy Memorial In 1956, many of the residents of Minamata, Japan became seriously ill, or died, after eating the fish and shellfish of Minamata Bay. A nearby chemical plant was spewing methylmercury-contaminated wastes into a body of water which provided the fish and shellfish which formed a large part of the local residents' diet. Hundreds died from mercury poisoning soon after, including many still born children. New research from Kumamoto University suggests that up to 35,000 people were affected. Today, the symptoms of severe mercury poisoning are still referred to as "Minamata Disease".

For more information on mercury and its effects on human and ecosystem health, see Links & Resources.