The Ojibwa Health Study: fish residue comparisons for Lakes Superior, Michigan, and Huron

The Ojibwa Health Study is a descriptive epidemiology study of six Ojibwa reservations in the Upper Great Lakes. Fish consumption habits, contaminant (mercury [Hg], polychlorinated biphenyls [PCBs], and other organochlorines [OCs]) residues in dietary fish and humans, and chronic disease outcomes currently are being documented. Four hundred and fifty questionnaires and approximately 200 biological samples had been collected as of December 1994. Fish collections from reservations included lake trout, walleye, lake whitefish, and lake herring from Lakes Superior (three sites), Michigan, and Huron. Hg and OC residue analyses have been completed for the fish composite samples. A preliminary examination of the data has revealed regional differences in the contaminant burdens of the fish. Lake Michigan and Lake Huron whitefish composite samples had approximately twice the OC concentrations of Lake Superior whitefish samples. In general, the whitefish composite samples were far below the U.S. Food and Drug Administration or any state advisory limits for OC or Hg residues. Lake trout samples contained higher amounts of all residues than did the whitefish samples.