Frequent Questions

How can EPA say in the Hazardous Waste Combustion Emission Standards Rule that the risks are low when EPA's risk assessment for mercury has many uncertainties?

We conclude that sufficient technical basis exists for conducting a quantitative analysis of mercury exposures from hazardous waste combustors. EPA has issued its Mercury Study Report to Congress and Utility Study Report to Congress and both include quantitative modeling analyses of mercury exposures, the most important of which are from consumption of fish. While our analysis suggests that hazardous waste combustors by themselves are not likely to result in exceedances of EPA's reference dose for methyl mercury, we did not consider concurrent exposures that may occur in areas with relatively high background environmental mercury levels nor did we consider all the site-specific factors that determine the levels of mercury in fish. We recognize, therefore, that significant uncertainties remain in our national risk assessment, and believe the results of our mercury analysis should be interpreted with this in mind.

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