Results of EPA’s Assessment of Fish Tissue from U.S. Rivers for Mercury and Persistent Organic Compounds with Implications for Aquatic Life and Human Health

Oral Presentation

Prepared by J. Wathen1, L. Stahl1, J. Lazorchak2, A. Batt3, B. Snyder4, H. McCarty5
1 - U.S. EPA Office of Water, 1200 Pennsylvania Ave, NW, MC 4305T, Washington, DC, 20460, United States
2 - U.S. EPA ORD, 26 W Martin Luther King Drive, Cinncinatti, OH, 45268, United States
3 - U.S. EPA Office of Research and Development, 26 W Martin Luther King Drive, Cincinnati, OH, 45268, United States
4 - Tetra Tech, Inc, 400 Red Brook Blvd, Suite 200, Owings Mills, MD, 21117, United States
5 - CSC, 6101 Stevenson Avenue, Alexandria, VA, 22304, United States

Contact Information:; 202-566-0367


Mercury and persistent halogenated organic compounds occur in fish tissue in U.S. lakes, rivers, and streams. Mercury, PCBs, and DDT occurring in fish tissue are the leading cause of fish consumption advisories. In a continuing effort to characterize the extent of contamination in the Nation’s waters, EPA’s Office of Water and Office of Research and Development collaborated to conduct the first statistically based survey of persistent and bio-accumulative contaminants in fish from U.S. rivers. This national fish survey was conducted in 2008 and 2009 within EPA’s National Rivers and Streams Assessment (NRSA), a probability-based survey designed to assess the condition of the Nation’s streams and rivers. Field teams applied consistent methods nationwide to collect samples of fish species of sizes consumed by humans at 541 randomly selected river locations (≥ 5th order) in the lower 48 states during June through October. They collected one fish composited sample consisting of five similarly sized adult fish of the same species at every sampling location. Largemouth and smallmouth bass were the primary species collected for the study, accounting for 34% and 24% of all fish composites, respectively. Homogenate samples were analyzed for Hg and a suite of ~50 organo-halogen compounds including PCBs (21 congeners), PBDEs (8 congeners), chlordane and DDT compounds and degradation products, and other pesticides, (Aldrin Dieldrin, Mirex, and Endosulfan) by GC-ECD. Samples were collected from both non-urban (379 sites) and urban locations (162 sites). All samples contained Hg above the quantitation level, and study data indicate that PCBs, PBDEs, chlordane, and DDT compounds occur at quantifiable levels in almost every fish sample collected for the study. Ongoing analysis of the data from this study will apply both human health and aquatic life thresholds to fish tissue concentrations of Hg and these four organo-halogen contaminant groups from both urban and non-urban sites. In addition, we are examining the percentages of co-occurrence of Hg and these four compound groups at concentrations above the respective contaminant group medians.