Revised Technical Support Document: National-Scale Assessment of Mercury Risk to Populations with High Consumption of Self-Caught Freshwater Fish. In Support of the Appropriate and Necessary Finding for Coal- and Oil-Fired Electric Generating Units

摘要

The goal of this assessment was to determine whether mercury emitted from U.S. EGUs poses a potential public health hazard. Therefore, we have designed this risk assessment as a screening analysis focused on identifying watersheds where there is a public health hazard attributable to U.S. EGU mercury deposition. Mercury emitted from U.S. EGUs, depending on the form of mercury emitted and other factors, can deposit locally and regionally in U.S. waterbodies, as well as contribute to the global pool of mercury, where it can be transported and eventually deposited around the world. This deposited mercury is transformed into methylmercury (MeHg) by microorganisms and then bioaccumulates as MeHg in fish. The primary pathway of concern from a public health standpoint is consumption of mercur-ycontaminated fish by women of child bearing age (since mercury can stay in the system for some time, both women who are pregnant or about to be pregnant are of concern.) Depending on the level of prenatal exposure, children born to those women may then experience a range of neurodevelopmental effects including decrements on a number of neuropsychological measures.