Examples of Contaminated Sites and Potential Risk Exposure Pathways

1 Examples of Contaminated Sites and Potential Risk Exposure Pathways 

As a result of these improper disposal practices, sites contaminated with hazardous wastes came to public attention throughout the 1970s and 1980s. The effects of improper hazardous waste disposal may persist for decades or even centuries when the contaminants have low degradation rates and migrate slowly through the subsurface. 

The US EPA summarized the results of studies of potential pathways for the release of chemicals from Superfund sites (US EPA, 1988). Migration to groundwater was cited as the primary pathway of contaminants at these hazardous waste sites, a trend confirmed by the data in Table 1 37% of sites involved releases to groundwater and 23% were responsible for releases to both groundwater and surface water. Other studies document the potential hazards of hazardous waste disposal. The EPA, in a survey of 466 public water supply wells, found that one or more volatile organic 

A primary directive of CERCLA is the protection of public health. Because the hazards that exist at Superfund sites tend to be quite variable, it has not been possible to establish specific cleanup criteria for Ae hazardous substances regulated under CERCLA potential human health effects must be evaluated by quantitative risk assessment on a site-by-site basis. Each Superfund site is assessed individually to determine how clean is clean. The rationale is that the hazard of a contaminant is a function of its potential to reach a receptor (e.g., groundwater, population) and the potential harm to the exposed receptor. The ability of a contaminant to migrate, its potential to degrade, and its distance to a receptor of concern (i.e., the risk), all are site-specific. Only on the basis of such individualized risk assessment is it possible to achieve efficient and cost-effective cleanup of the thousands of hazardous waste sites throughout the US. 

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