Toxaphene in great lakes fish: A temporal, spatial, and trophic study

We report here on the concentrations of toxaphene, a complex mixture of hexa- to decachlorinated norbornanes and norbornenes, in Great Lakes' lake trout and smelt sampled in 1982 and 1992. Lake trout from Lakes Superior, Michigan, and Huron had higher lipid-normalized toxaphene concentrations than the smelt, while in Lakes Ontario and Erie both trophic levels had about the same concentrations. Concentrations in both species declined between 1982 and 1992, with the exception of Lake Superior, where there was no significant difference. Except for the Lake Superior samples, these trends were expected because toxaphene was banned in the United States in 1982. The fact that the Lake Superior samples did not show lower concentrations over time suggests that there may be some lake-specific source that is continuing to load toxaphene into Lake Superior or that toxaphene is not being removed from Lake Superior as quickly as the other Great Lakes.