A Methylmercury Risk Screening Assessment to Identify Fish Species and Populations of Potential Concern

Abstract

State fish consumption advisories provide meal limit recommendations for recreationally-caught fish. In Louisiana, these recommendations are based on species-specific fish tissue contaminant concentrations, and default assumptions about fish consumption. This approach can lead to advisories for infrequently eaten species, and inappropriately targeted monitoring and outreach activities. The goal of this study is to identify and prioritize species, populations and areas of potential concern based on a screen of mercury intake. Mercury doses were estimated based on species-specific fish consumption data from a population-based survey of Louisiana's recreational fishers (n=1774), and regional fish tissue mercury concentration data (n=15,030). Estimates of species-specific mercury doses were derived for each survey respondent based on mean and 90 th percentile fish tissue mercury levels. Mercury exposure distributions for various species and sub-populations were compared to the U.S. Environmental Protection Agency's health-based standard for methyl-mercury. As children and commercial and subsistence fishers were not surveyed, conclusions presented here are only applicable to adult recreational fishers, who are expected to eat less fish than commercial and subsistence fishers. Species with the largest number of at-risk fishers were drum (primarily red drum), speckled trout, catfish, crappie, bass and bream. Populations of potential concern included women of childbearing age; African- and Native-Americans; fishers from northern Louisiana; and fishers with Hook and Line and Basic licenses. Results were used to make recommendations to optimize monitoring, advisory development and outreach activities. This study demonstrates the importance of collecting fish consumption data for ensuring adequate public health protection.