Future trends in environmental mercury concentrations: implications for prevention strategies

In their recent article, Bellanger et al. [1] quantified the monetary benefits from control of methylmercury (MeHg) toxicity in European Union (EU) countries at between €8,000 and €9,000 million per year. The authors used population biomarker data to estimate that 1.5 to 2.0 million EU children are born each year exceeding exposure limits associated with long term IQ deficits. Given these severe effects and high costs to society, information on the benefits of global emissions reduction is critically needed to support regulatory efforts aimed at reducing MeHg exposures.Quantitative relationships linking changes in global anthropogenic mercury releases to human and biological exposures are still being developed. However, available information suggests aggressive global action to curb emissions is necessary to achieve declines in environmental concentrations. Here we briefly review biological exposures to mercury, environmental sources, and trends in concentrations that could impact human exposure. We conclude by discussing implications for prevention strategies.A dominant fraction of human exposure to MeHg is from consuming marine fish. For example, for the United States population an estimated 77% of MeHg exposure is from offshore marine fisheries [2,3]. Many vulnerable populations, particularly in northern regions, consume substantial quantities of marine mammals such as whale and seal that are also high in MeHg [4-6].Given the importance of marine fish for human and biological exposures, much debate has arisen about the origin of mercury in marine ecosystems and the extent of perturbation by human influences. While some prior research suggested that MeHg in marine fish is naturally occurring (e.g., [7]), recent studies indicate that human impacts on ocean ecosystems are larger than previously thought [8,9]. Environmental concentrations of inorganic mercury drive the pool available for conversion to MeHg and subsequent bioaccumulation in aquatic food chains [10-12]