A Probability-Based Assessment of Contaminants in Great Lakes Fish

Multiple EPA offices collaborated to conduct the first probabilistic survey of fish contamination in the Great Lakes.  The Great Lakes Human Health Fish Tissue Study added a human health component to the ecological assessments EPA conducted under the statistically designed National Coastal Condition Assessment.  This study involved collecting one fish composite sample from 157 randomly selected nearshore sites throughout the five Great Lakes.  The composite samples consisted of five similarly sized adult fish of the same species that are commonly consumed by humans.  Fillet samples were analyzed for mercury, the full suite of 209 polychlorinated biphenyls (PCBs), and 52 polybrominated diphenyl ether congeners (PBDEs).  Field crews collected the fish samples for this study from mid-May through mid-November in 2010.  Lake Trout, Smallmouth Bass, Walleye, and Chinook Salmon accounted for 67% of the composites.  All of the fillet samples contained detectable levels of mercury, PCBs, and PBDEs.  The statistically derived median mercury, PCB, and PBDE concentrations in fillets were 139 ppb, 179 ppb, and 13 ppb, respectively, for the Great Lakes nearshore sampled population of 11,091 km² (4,282 mi²).  Maximum measured mercury, PCB, and PBDE concentrations in fillet tissue were 956 ppb, 2,379 ppb, and 227 ppb, respectively.