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EPA’s National Study of Chemical Residues in Lake Fish Tissue

Leanne Stahl 1, Blaine Snyder 2 and Jennifer Pitt 2

1 U.S. Environmental Protection Agency, Office of Water, Washington, DC
2 Tetra Tech, Inc., Owings Mills, Maryland

The Office of Water conducted the largest national freshwater fish contamination survey undertaken by EPA. The National Study of Chemical Residues in Lake Fish Tissue (or the National Lake Fish Tissue Study) includes the largest set of chemicals studied in fish, and it is the first national fish contamination survey to have sampling sites statistically selected. Agencies in 47 states and three tribes, along with two other federal agencies, collaborated with EPA for four years to collect fish from 500 lakes and reservoirs in the lower 48 states. Sampling teams applied consistent methods nationwide to collect samples of predator and bottom-dwelling species from each lake. EPA analyzed the fish tissue for 268 persistent, bioaccumulative, and toxic (PBT) chemicals, including mercury, arsenic, PCBs, dioxins and furans, and pesticides.

Results from the National Lake Fish Tissue Study indicate that mercury, PCBs, and dioxins and furans are widely distributed in lakes and reservoirs in the lower 48 states. Mercury and PCBs were detected in all the fish samples collected from the 500 sampling sites. Dioxins and furans were detected in 81% of the predator samples (fillet composites) and 99% of the bottom-dweller samples (whole-fish composites). EPA is using results from this study to develop national estimates of the median concentrations of the 268 PBT chemicals in lake fish and to define a national freshwater fish contamination baseline for tracking chemical reductions as a result of pollution control activities. The final report for this study is scheduled for release in Fall 2007.

Keywords: fish contamination, lake survey, mercury, PCBs, dioxins and furans

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