Contaminant Mixtures in Fish: Toxicity and Risk Assessment

Session: Chemical Monitoring and Surveillance in the Great Lakes: Multimedia (2)

Noel Urban, Dept. Civil & Environment Eng., Michigan Technological Univ., [email protected]
Judith Perlinger, Michigan Tech. University, Civil & Environmental Engineering Dept., [email protected]
Emily Shaw, Michigan Technological Univ., [email protected]

Abstract

Historically, risk from fish consumption has been assessed for single contaminants, although evidence suggests that mixture toxicity is greater than that of single components.  Historically, we have also focused on distributions among locations of single contaminants rather than of cumulative mixtures.  Toxicity measurements of contaminant mixtures are still in their infancy, although protocols exist.  We present here an analysis of the co-distribution of PCBs and mercury, the two predominant contaminants in Great Lakes fish, in waterways throughout Michigan, among the Great Lakes, and in a national lake survey.  We examined distributions of combined toxicity (Hg, PCBs) using an additive model.  In all Great Lakes and Michigan rivers, the combined toxicity is strongly dominated by PCBs.  In Michigan’s inland lakes, the situation is fundamentally different with nearly equal contributions from Hg and PCBs.  The national lake survey reveals that the combined risk in top predator fish is dominated by Hg while that in bottom dwelling fish is dominated by PCBs.  These results indicate that in some water bodies, the toxic risk from fish consumption is seriously underestimated when only single contaminants are considered.