The accumulation of mercury by fish and the potential human health effects of eating mercury-contaminated fish have been well documented. However, elevated mercury concentrations in fish from dilute, low-pH lakes have only recently been associated with increased lake acidity. Nevertheless, there now is ample evidence to document that elevated levels of mercury are found in fish from lakes in remote areas with no known point sources of mercury and that an apparent relationship exists between lake pH and fish mercury level. The U.S. Food and Drug Administration (FDA) has set an action level of 1.0 ppm methyl mercury as the limit for human consumption. Many state fisheries agencies in the United States have established advisories regarding consumption of fish with mercury levels that do not exceed the standard of 1.0 ppm, usually invoking a standard of 0.5 ppm. Forty-nine drainage and seepage lakes in the Upper Michigan Peninsula were sampled in conjunction with Phase 2 of the U.S. Environmental Protection Agency's Eastern Lake Survey to explore the relationship between chemical and physical characteristics of lakes and mercury concentrations in fish tissue. The lakes were selected using a stratified random design weighted for low pH so that acidification effects on mercury accumulation could be evaluated. By coupling the study to Phase I, the authors were able to examine the role of chemical and physical lake variables on the assimilation of mercury by fish.

Distributed to depository libraries in microfiche. "November 1990." Includes bibliographical references (pages 81-84). "EPA/600/3-90/068." "Funded wholly or in part by the U.S. Environmental Agency under cooperative agreements CR814602 (Cornell University), CR814951 (Syracuse University), and contract 68-03-3439 (Kilkelly Environmental Associates)"--Title page verso.