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The Great Lakes (Superior, Michigan, Huron, Erie, and Ontario) are an important part of the physical and cultural heritage of North America. The magnitude of the Great Lakes water basin is difficult to appreciate. The lakes contain some 5,500 cubic miles of water, covering 94,000 square miles, with a shoreline of over 10,000 miles. The Great Lakes is the largest system of fresh surface water on earth, comprising roughly 18 % of the world supply. Only the polar ice caps contain more fresh water. Approximately 10% of the U.S. population and 25% of the Canadian population live in the region.
For over 200 years, industry, agriculture, shipping, and recreation used the Great Lakes basin as a resource. By the early 1960s, the environmental quality of the Great Lakes deteriorated because of eutrophication (excessive nutrients in a body of water, usually caused by runoff of nutrients (animal waste, fertilizers, sewage) from the land), overfishing, and the widespread presence of toxic substances. The physical nature of the basin and the long retention time of chemicals in the lakes combine to make this huge freshwater resource a repository for chemicals and their by-products. Despite their size, the lakes are especially sensitive to pollution. Less than one percent of their total volume flows out of the St. Lawrence River each year, allowing toxic substances to accumulate in the lake sediment.
Because of the persistence and widespread occurrence of these Great Lakes pollutants, toxic effects in wildlife are evident. Epidemiologic investigations suggest that adverse human health effects, i.e., reproductive, developmental, behavioral, neurologic, and immunologic, may result from exposure to Great Lakes pollutants. Given the implications of the association between persistent toxic substances in the Great Lakes and the potential for adverse human health outcomes, in 1990 the U.S. Congress amended the Great Lakes Critical Programs Act to investigate this human health concern.
Initiated in 1992, the Agency for Toxic Substances and Disease Registry (ATSDR) Great Lakes Human Health Effects Research Program is designed to characterize exposure to contaminants via consumption of Great Lakes fish, and investigate the potential for short- and long-term adverse health effects.