Great Lakes Fact Sheet #10: Harmful Pollutants

File Size2.68 MB
PublishedMarch 9, 2013

Toxic Substances, Legacy Contaminants and Substances of Emerging Concern
What happens when harmful pollutants end up in the Great Lakes?

The Great Lakes played a critical part in North America’s industrial development. Substances such as mercury, PCBs (polychlorinated biphenyls) and DDT (dichlorodiphenyltrichloroethane) were widely used and often ended up in the lakes because the resulting environmental and health impacts were not well understood. Canada and the United States have made considerable progress in reducing the levels of some of these historical contaminants found in the lakes.

However, some relatively new substances, as well as older substances whose effects are only now being detected, are presenting new challenges. Although the effects of exposure to current levels of these substances of emerging concern remain unclear, they are considered potential risks to the environment and human health.