Assessing the Mercury Health Risks Associated with Coal-fired Power Plants: Impacts of Local Depositions

The U.S. Environmental Protection Agency has announced plans to regulate emissions of mercury to the atmosphere from coal-fired power plants. However, there is still debate over whether the limits should be placed on a nationwide or a plant-specific basis. Before a nationwide limit is selected, it must be demonstrated that local deposition of mercury from coal-fired power plants does not impose an excessive local health risk. The principal health concern is exposure of pregnant females to methyl mercury in seafood. This paper presents a quantitative assessment of the health risks for populations within 50 km of a power plant. Probabilistic risk assessments were performed for two power plants, Bruce Mansfield in western Pennsylvania and Monticello in eastern Texas. Local hourly meteorological data was obtained for these sites and deposition modeling was performed for a region 50 Km around the site. Risk assessments were performed for two population groups (general and subsistence fishers) and the modeled deposition patterns. The risk assessments indicated that for the general population local deposition associated with the emissions from the coal-fired power plant were small (< 10 risk of observed neurological effects) but risks could be two orders of magnitude higher for subsistence fisher populations. Estimated risks were more highly dependent on consumption patterns than increases in deposition due to coal-fired power plant emissions.