How is the methylmercury criterion derived?
To assess health risks, EPA developed a reference dose that is a scientifically justifiable maximum level of exposure to protect public health from all toxic effects. EPA based the methylmercury criterion on a new reference dose that protects all exposed populations. EPA also updated the exposure assessment and relative source contribution following the recently published 2000 Human Health Methodology. The resulting criterion of 0.3 mg methylmercury/kg in fish tissue should not be exceeded to protect the health of consumers of noncommercial freshwater/estuarine fish. EPA has taken into account the fact that consumers of freshwater/estuarine fish are also consumers of marine fish. EPA suggests three approaches that can be used to translate fish tissue methylmercury concentrations into concentrations of methylmercury found in the water column: • Calculate site-specific bioaccumulation factors based on data collected from a specific waterbody; • Calculate site-specific bioaccumulation fac
