Chapter 10
Challenges to Health from the Major Environmental Chemical Contaminants in the Saint Lawrence River 1
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S. Raman and K. S.
23 ,
Subramanian
1
Department of Epidemiology and Community Medicine, University of Ottawa School of Medicine, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada Environmental Health Directorate, Postal Locator 0800B3, Health Canada, Tunney's Pasture, Ottawa, Ontario K1A 0L2, Canada
2
The International Joint Commission (IJC) has identified polychlorinatedbiphenyls (PCBs) and mercury as the major chemical contaminants in the St. Lawrence River system. Since 1979, PCBs have been repeatedly identified in sediment, forage, sport fish, water fowl, snapping turtles and native mussels at various locations in the St. Lawrence River from Cornwall, Ontario to Valleyfield, Quebec. PCB concentrations in the river have rarely been below 1 ng/L, the Ontario Water Quality Objective. Since 1988, mercury levels in the Cornwall-Massena area of the St. Lawrence River have been found to be below the analytical detection limit of 10 ng/L. However, there are no systematic population monitoring of the health effects of the contaminants in the St. Lawrence river. One way of assessing the impact is through the National Vital Statistics on mortality and hospital morbidity. This paper discusses the limitations of such conventional epidemiologic studies in assessing the impact of environmental chemical contaminants on population health. "Environmental degradation inevitably causes a degradation of human life, even when it does not interfere with fundamental biological activities" (7). This simple yet poignant statement implies that mankind is dependent on clean water, fresh air and unpolluted land for continued sustenance. Nevertheless, human beings have been degrading the environment at an alarming rate within the past 50 years, thereby causing considerable damage to human and ecosystem health. A prime example of this is the St. Lawrence River. This is a major river system that constitutes the outflow of the largest reservoir of fresh water on earth. It serves 3
Corresponding author
© 1997 American Chemical Society
In Environmental Biomonitoring; Subramanian, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1997.
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10.
RAMAN & SUBRAMANIAN
Contaminants in the St. Lawrence River 97
as a source for a number of vital services, including the provision of drinking water, transportation, sport and commercial fisheries, tourism and a host of industrial activities. Historically, the River has served as a rich habitat for a variety of wild life, and a means of livelihood for people living on its shores. However, the river has reached a state of both chronic and acute ill-health owing to nearly two centuries of human habitation and commercial exploitation relative to its pristine paleolimnological picture (2). In recent decades, the River has exhibited increasing symptoms of ecological pathology. The high levels of organic and inorganic pollutants in the water sediment and biota have wrought drastic and generally undesirable changes to the lives of many people whose traditional livelihood depended on theriver.This has resulted in legitimate concerns about risks to human health. This chapter will focus on epidemiologic aspects of the challenges especially in predicting the relationship between exposure to a given contaminant (or contaminants) and the consequent development of an adverse effect - to health from some of the major environmental contaminants in the St. Lawrence River. The investigation is part of our mandate to study the gaps in knowledge in relation to the ecological impact of the River on the health of the Cornwall and Akwasasne communities (5). The final report of this 3-year (1993-1996) multidisciplinary study will identify the course of action required for the écologie rehabilitation of the degraded River system with a focus on the sustainable re development of the Cornwall region. History of Chemical Contaminants in the St. Lawrence In epidemiologic parlance the chemicals represent the agent, exposure to some of which have adverse health consequence. In 1981 the IJC compiled an inventoiy of over 1000 chemical substances; 360 of which were applicable to the Great Lakes system and about 100 of these compounds have potentially adverse health effects in humans (4, 5). Environment Canada and the Quebec Ministiy of Environment have conducted surveys of over 100 sampling stations in the St. Lawrence River and collected information on 45 variables which have been entered into a national database for the 1978-1988 decade (
