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 Aquatic EcosystemsToxic Chemicals: Page 9 Air pollution regulations in the 1980s and 1990s mandated removal of the majority of sulphur dioxides prior to the release of emissions, and this has made a difference in the rate of acidification in North America and Europe. In parts of Europe, lime has been broadcast from small planes on some of these lifeless lakes to lower acidity. Usually, liming has to be frequently repeated and is not always effective. When pollution is decreased, however, life forms return, and air pollution controls have resulted in decreased acidification in some areas.
Dioxin, a chemical emitted by paper and plastic manufacturing plants and incinerators, has been found in aquatic ecosystems. It is toxic to many fish and their eggs, and is considered a cancer risk to humans. Dioxin residues in Lake Ontario, Canada, began killing the eggs of Lake Trout as early as the 1940s, and the species became extinct in the lake by the early 1950s (Colborn et al. 1996). Dioxin has been found in high concentrations in Eskimos of the Canadian arctic who eat caribou and seal meat; the latter animals consumed dioxins contained in their food from airborne dioxin generated by incinerators in the United States and Mexico (Hilts 2000).
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