An Analysis of Potentially Exposed Populations Living Near Coal Combustion Waste Facilities and Associated Cancer Risks

摘要

In 2010, the US Environmental Protection Agency (US EPA) published the results of a probabilistic risk assessment examining risks associated with the leaching of constituents in coal combustion residues (CCR) from different types of waste management units (WMUs), finding that exposure to arsenic via drinking water posed the most significant risk. Based on these results, US EPA conducted a Regulatory Impact Analysis (RIA) to estimate the regulatory benefits associated with avoiding excess cancer cases from arsenic exposure. In this paper, we present an alternative approach for determining the estimated number of excess cancer cases through a refined analysis of the size of the population that could potentially be exposed to arsenic leaching from WMUs. To perform this assessment, we located 511 coal-fired power plants on aerial imagery, mapped known or estimated groundwater flow direction, and counted apparent dwellings within one mile downgradient from the plant (excluding areas served by public water supplies) to identify the number of potentially exposed individuals. From the 511 identified power plants, we determined that 73 had potential downgradient receptors that are not on a municipal water supply. These 73 plants had 2,659 apparent dwellings, with an estimated population of 6,913 individuals. Although we took a markedly different approach, our evaluation was in reasonable agreement with US EPA's. Our evaluation provides a refined assessment of the population that may be potentially exposed to CCR leachate and further informs risk management decisions regarding the safe storage of CCRs.