Book excerpt: This report summarizes what is currently known about the levels and the effects of toxic chemicals in the water, sediments, fish, wildlife and human residents of the Great Lakes basin. A list of critical pollutants is included. Particular attention is paid to the effects of toxic contaminants on double-crested cormorants, bald eagles, herring gulls, common terns, mink, common snapping turtles, and lake trout.