July 2, 2004
Banned Chemical Still Shows Up in Lake Superior Fish
Ann Arbor, Mich. — Toxaphene is a major contaminant in Lake Superior fish, even though this substitute for DDT was banned as an agricultural insecticide in 1985 in Canada and 1990 in the United States.
Scientists from both countries collaborated to examine how this chemical, which enters the lake mainly from atmospheric deposition, accumulates from lake water and sediments in top predator fish.
Toxaphene is a mix of up to 1,400 possible compounds, making it a challenge to measure. The study, funded by the U.S. Environmental Protection Agency, found that certain components of toxaphene become more and more concentrated as they are passed along the food chain from water to lake trout, magnified 10 million to 5 billion times.
Similar biomagnification occurs for toxaphene in other nearby lakes, such as the remote Siskiwit Lake on Isle Royale, an island in Lake Superior, although absolute levels in the lake trout from Siskwit Lake are about 15 times lower than in Lake Superior. This may be because Lake Superior lake trout rely on forage fish as food, placing them higher up the food chain. Another possible factor is that the chemical may last longer in the cold, deep waters of Lake Superior.
Original Publication Information
Results of this study, "Bioaccumulation of Toxaphene Congeners in the Lake Superior Food Web," are reported by Derek C.G. Muir, D. Michael Whittle, David S. DeVault, Charles R. Bronte, Heidi Karlsson, Sean Backus and Camilla Teixeira in the latest issue (Volume 30, No. 2, pp. 316-340) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2004.
Contacts
For information about the study, contact Derek Muir, National Water Research Institute, Environment Canada, 867 Lakeshore Road, Burlington ON L7R 4A6 Canada; Derek.muir@ec.gc.ca; 905-319-6921.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; marlene.evans@ec.gc.ca; (306) 975-5310.
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.
