A Probability-based National Assessment of Contaminants in Fish from U.S. Rivers

Polyfluoroalkyl Substances (PFAS) in the Environment
Oral Presentation

Presented by H. McCarty
Prepared by J. Healey1, B. Snyder2, T. Cohen2, H. McCarty3
1 - U.S. Environmental Protection Agency, 1200 Pennsylvania Ave, NW, M/C 4305-T, Washington, DC, 20460, United States
2 - Tetra Tech, 10711 Red Run Blvd., Suite 105, Owings Mills, Maryland, 21117, United States
3 - General Dynamics Information Technology, 3170 Fairview Park Drive, 4th floor, Falls Church, Virginia, 22003, United States

Contact Information: [email protected]; 202-566-0176


Most existing fish consumption advisories in the United States (U.S.) have been issued for mercury and polychlorinated biphenyl (PCB) contamination, but states have recently begun to issue advisories for per- and polyfluoroalkyl substances (PFAS). The U.S. Environmental Protection Agency (EPA) developed an unequal probability survey design to allow a comprehensive characterization of mercury, PCB, and PFAS contamination in fish from U.S. rivers on a national scale. During 2018-2019, fish fillet samples were collected from 290 sites selected randomly from the target population of rivers (≥5th order in size) in the conterminous U.S. This comprised a nationally representative sample and allowed extrapolation to a sampled population of 66,142 river km. The goal was to develop estimates of the national distribution of total mercury, all 209 PCB congeners, and 33 PFAS (including perfluorooctane sulfonate or PFOS) in river fish. All fillet tissue samples contained detectable levels of mercury and PCBs. PFAS were detected in 95.2% of the fillet samples. Fish tissue screening levels (SLs) applied to national contaminant probability distributions allowed an estimation of the percentage of the sampled population of river km that contained fish with fillet concentrations above a level protective of human health. Fish tissue SL exceedances for an average level of fish consumption (i.e., the general population of fish consumers) were 26.0% for mercury (applying EPA’s 300 ng/g fish tissue-based water quality criterion), 17.3% for PCBs (using a derived 49 ng/g noncancer SL), 45.1% for PCBs (using a derived 12 ng/g cancer SL), 0.7% for PFOS (using a derived 46 ng/g noncancer SL). Fish tissue SL exceedances for high-frequency fish consumers (e.g., subsistence fishers) were 46.2% for PCBs (using a derived 11 ng/g noncancer SL), 73.8% for PCBs (above a 2.8 ng/g cancer SL), and 18.3% for PFOS (using a derived 11 ng/g noncancer SL).