Analysis of potential mercury policies: The impact of stream basin characteristics on susceptible populations

Abstract

Human exposure to Hg through fish consumption from local waterways is an ongoing concern to regulatory decision makers. Previously described population exposure and bioaccumulation models were combined to analyze the impact of potential policies on susceptible populations. The combined model simulated the problem of Hg exposure by examining the system from the point of Hg in the water column to its concentration in population biomarkers. Evaluated policy scenarios included the protectiveness of fish consumption advisories, total maximum daily load changes, and watershed management strategies. Simulations indicated that the characteristics of a basin combined with the unique pattern of intake rates of susceptible populations determine the risk associated with fish consumption from a given waterway. Each population had a unique pattern of biomarker response to changes in fish tissue Hg. Management strategies that lowered bioaccumulation rates also reduced ecosystem services. Reducing fish tissue contamination through reductions in Hg loading to watersheds is a long-term solution. For the short-term, fish consumption advisories should be used to protect populations from adverse exposures. The combination of characteristics of the basin and the populations that fish from the waterway should be the determinant for setting advisories.