Quantifying the health and economic impacts of mercury : an integrated assessment approach

Abstract

Mercury is a toxic pollutant that endangers human and ecosystem health. Especially potent in the form of methyl mercury, exposure is known to lead to adverse neurological effects, and, a growing body of evidence suggests, cardiovascular ones. Mercury's health impacts have economic consequences, and benefit-cost analyses focusing on these health benefits are used to motivate regulatory action in the United States and elsewhere. However, many existing valuation studies of the health impacts of mercury have substantial limitations, both from a scientific and economic perspective. Because they do not fully model mercury's path from emissions to impacts, they do not fully reflect the spatial and temporal dimensions of the mercury problem. In addition, many do not consider uncertain, but potentially policy-relevant health effects like cardiovascular disease. This thesis develops an integrated assessment framework that more completely represents mercury's emissions-to-impacts path, and then evaluates its policy relevance. The assessment framework integrates chemical transport modelling, exposure and health impacts modelling, and general equilibrium modelling of the US economy. As a case study, the framework is used to evaluate the benefits of the Mercury and Air Toxics Standards-a recent US regulation that targets emissions from coal-fired power plants-until 2050. I estimate the annual benefit of MATS to be 13 million 2005 USD, compared to a scenario that includes stringent air quality policy, and 414 million 2005 USD when compared to a no policy scenario. I find that the estimate is highly sensitive to uncertainties along the emissions-to-impacts path-in particular, dose-response parameterization, ecosystem lag times, and discount rate. The analysis suggests that given the large ranges of uncertainty involved, more fully representing the emissions-to-impact chain does not lead to substantially different aggregate benefits estimates, compared to those existing in the literature. However, because this approach does provide more insight into the controlling influences behind benefits, it can inform decisions about where policies should be implemented, and of what type, as well as best practices for transparently assessing mercury-related policies.