Assessment of Louisiana's Fish Tissue Mercury Levels, Sportfish Consumption, Methylmercury Intake and Potential Risk: Implications for Monitoring, Advisory Development and Outreach

Exposure to methylmercury has been associated with deficits in fetal and childhood neurodevelopment. Louisiana has some of the highest fish methylmercury levels in the country; yet exposure through local fish consumption remains largely untracked. The ultimate goal of this study was to obtain data in support of recommendations to optimize monitoring, advisory development and outreach for a high exposure population with unique seafood consumption patterns. The objectives of this study are to characterize fish tissue mercury levels and local fish consumption, and estimate potential mercury intake. To achieve these objectives, I conducted the first tissue mercury levels and local fish consumption, and estimate potential mercury intake. To achieve these objectives, I conducted the first comprehensive analysis of Louisiana's fish tissue mercury data (n=14,344); and analyzed data from the first known population-based survey of Louisiana's recreational fishers (n=1774). These data were integrated to estimate mercury intake for survey respondents; and prioritize species, areas and populations of potential concern. Fish tissue mercury levels ranged from 0.001 ppm (the detection limit) to 5.904 ppm for king mackerel; with an overall geometric mean of 0.218 ppm. Forty-four percent of all samples had mercury levels above the U.S. EPA's methylmercury fish tissue criterion of 0.3 ppm for sportfish. The highest normalized fish mercury levels were observed in Pearl and Calcasieu basins. In the year prior, 95% of respondents reported eating sportfish. Respondents ate a mean of four total fish meals per month, of which, approximately half were sportfish. Over half of all sportfish meals (54%) were caught in the Gulf of Mexico or bordering brackish areas. The most frequently consumed sportfish species were red drum, speckled trout, catfish, bass, crappie, bream and flounder. Species with the largest number of at-risk fishers based on mean fish tissue mercury levels were drum (primarily red drum), speckled trout, catfish, crappie, bass and bream. Populations with the largest proportion of at-risk fishers based on mean fish tissue mercury levels included women of childbearing age; African-Americans; fishers from north Louisiana; and fishers with Hook and Line, and Basic fishing licenses. Results were used to make recommendations to optimize monitoring, advisory development and outreach activities.