A Regulatory Analysis of EPA's Proposed Rule to Reduce Mercury Emissions from Utility Boilers

Abstract

EPA's proposed rule for mercury reductions from coal-fired utility boilers is unlikely to provide significant health benefits, both because mercury exposure at current levels is unlikely to be causing harm, and because even in a best case scenario the mercury rule could reduce mercury in fish by no more than a few percent. The claim that reducing mercury in fish will reduce neurological harm to fetuses of exposed pregnant women is based on the assumptions that the results of an epidemiologic study of mothers and children in the Faroe Islands represents a genuine cause-effect relationship between low-level mercury exposure and children's neurological health, and that Faroes-like effects would occur in Americans even at mercury exposures as low as 1/15th the minimum level associated with health effects in the Faroes study. But even accepting these assumptions at face value, the reported health effects are subtle and at current American mercury exposure levels have no implications for general neurological or cognitive health. For example, based on the Faroes results, a complete elimination of U.S. utility mercury emissions could, in a best-case scenario, move children who are at, say, the 10th percentile on neurological and cognitive test scores to between the 10.3 and 10.6 percentiles. Even this small improvement is unrealistically optimistic, because it also assumes a one-to-one correspondence between mercury emission reductions and mercury levels in freshwater fish, and that people with high mercury exposures receive all of their mercury from non-commercial, freshwater fish. Furthermore, a similar study of children in the Seychelles reported no harm from mercury exposures several times higher than even relatively highly exposed Americans. The Seychelles study may be more relevant to Americans, because people in the Seychelles are exposed to mercury through eating ocean fish, while people in the Faroe Islands are exposed through eating whale blubber. EPA's mercury rule is thus likely to provide few or no health benefits. On the other hand, EPA estimates even modest utility mercury reductions will cost about $1.4 billion per year. These costs will in part be passed through to consumers, reducing the resources available for other health- and welfare-enhancing expenditures. If EPA still wishes to go forward with utility regulations, rather than regulate mercury directly, EPA should scrap both its mercury rule and its companion Interstate Air Quality Rule, which would regulate utility nitrogen oxides and sulfur dioxide (SO2), and instead require reductions only in SO2 emissions. SO2 reductions will reduce mercury levels in fish by reducing sulfate levels in lakes and streams, which reduces methylmercury formation, the form of mercury that gets into fish and to which people are exposed. Furthermore, the SO2 reductions will reduce mercury in freshwater fish regardless of where the mercury in fish is coming from and will cost less than mercury reductions. SO2 reductions will also reduce sulfate particulate matter and regional haze, and the measures necessary to reduce SO2 emissions will also modestly reduce mercury emissions. While the costs of additional SO2 reductions might still outweigh their benefits, the cost-benefit picture for utility SO2 reductions is far superior to even the most generous best-case benefit estimates for EPA's proposed utility mercury rule.