Toxic substances, Great Lakes

This paper discusses some of the impacts of development on the Great Lakes. Efforts that have been made to resolve individual problems are also discussed including the unique Canada/U.S. institutional framework for addressing these issues. Emphasis is placed on eutrophication and toxic substances, issues which have been the major focus of concern over the last three decades. 

The unique physical characteristics of the Great Lakes also contribute to their sensitivity to toxic substance inputs. The vast surface areas of the lakes makes atmospheric contributions of these chemicals, even at low concentrations, quantitatively significant. The relatively large ratio of the lake surface to drainage basin area, and the fact that the boundary of the drainage basin in some locations... 

Durham, R.W. Oliver, B.G. J. Great Lakes Res. 1983, P, 160-168. Thomas, R.L. Veik. Intemat. Verein. Limnol. 1981, 21, 1666-1680. Literature Review of the Effects of Persistent Toxic Substances on Great Lakes Biota Fitchko, J., Ed. Report to the Great Lakes Science Advisory Board, International Joint Commission, Windsor, Ontario, 1986, 256p. Allan, R.J. Symp. Biol. Hung. 1989, 38, 217-243. 

Bowerman, D.A., Best, T.G., and Grubb, G.M. et al. (1998). Trends of contaminants and effects in bald eagles of the Great Lakes Basin. In M. Gilbertson et al. (Eds.) Trends in Levels and Effects of Persistent Toxic Substances in the Great Lakes, 197-212. 

The Binational Toxics Strategy between the USA and Canada has identified 12 bioaccumulative substances (referred to as Level-1 substances) having significant persistency and toxicity to the Great Lakes system, with the goal of reducing the sources of these substances to achieve naturally occurring levels [23]. Six of the 12 Level-1 substances are OC pesticides aldrin/dieldrin, chlordane, DDT, HCB, mirex, and toxaphene. Several other OC pesticides, such as endrin, heptachlor/heptachlor epoxide, hexachloro-cyclohexanes, tetra- and penta-chlorobenzenes, and pentachlorophenol, have been identified as Level-2 substances. 

USEPA (1998) Atmospheric deposition of toxic substances to the Great Lakes IADN results through 1998. Environment Canada and the USEPA docket EPA905-R-01-007... 

Eisenreich SJ, Strachan WMJ (1992) Estimating atmospheric deposition of toxic substances to the Great Lakes. Workshop Report, Jan 31-Feb 2, 1992. Great Lakes Protection Fund and Environment Canada, Burlington, ON... 

Johnson, B.L., 1998. Public health implications of persistent toxic substances in the Great lakes and St. Lawrence basins. J. Great Lakes Res. 24, 698-722. 

The Great Lakes region has accumulated persistent toxic substances, including PCBs, to the extent that fish, other wildlife, and human populations face potentially high exposures to these constituents (Hicks... 

Scheider WA, Cox C, Hayton A, et al. 1998. Current status and temporal trends in concentrations of persistent toxic substances in sport fish and juvenile forage fish in the Canadian waters of the Great Lakes. Environ Monit Assess 53 57-76. 

Although bioconcentration causes the level of a potentially toxic substance to be much higher in an aquatic organism than in the water in which it lives, equilibrium is not always reached. For example, the weight-adjusted body burden of PCBs in lake trout captured from the Great Lakes (North America) increases with size/age (Bunce, 1994). See more details in Box 3. 

WC are not listed in national EPA water quality criteria documents, in part because the development of these criteria is relatively new and in part because the criteria are speciAc to particular aquatic ecosystems. The WC for the Great Lakes are thought provoking. In the case of mercury, for example, the WC is 1.3 ng/L. This compares with the national HHC for mercury of 50 ng/L. Why is the WC almost 40 times lower than the HHC The answer is that only a fraction of the diet of most Americans comes from Ash. Animals that prey on Ash almost exclusively or are predators of such animals are obviously at much greater risk from the standpoint of exposure to toxic substances. 

Polychlorinated biphenyls (PCBs). Polychlorinated biphenyls are organic chemicals that formerly had widespread use in electrical transformers and hydraulic equipment. This class of chemicals is extremely persistent in the environment and has been proven to bioconcentrate in the food chain, thereby leading to environmental and human health concerns in areas such as the Great Lakes. Because of their potential to accumulate in the food chain, PCBs were intensely regulated and subsequently prohibited from manufacture by the Toxic Substances Control Act (TSCA) of 1976. Disposal of PCBs is tightly restricted by the TSCA o... 

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