Polybrominated Diphenyl Ethers (PBDEs): Turning the Corner in Great Lakes Trout 1980–2009

Lake trout and walleye composites were collected between 2004 and 2009 as part of the Great Lakes Fish Monitoring and Surveillance Program (GLFMSP) and analyzed for polybrominated diphenyl ethers (PBDEs). Yearly mean total PBDE concentrations (sum of congeners BDE-47, BDE-99, BDE-100, BDE-153, BDE-154) ranged from 44–192, 28–113, 50–107, 37–111, and 11–22 ng/g wet wt. for Lakes Michigan, Huron, Ontario, and Superior lake trout, and Lake Erie walleye, respectively. A 1980–2009 temporal record of PBDE concentrations in the Great Lakes’ top predator fish (lake trout and walleye) was assembled by integrating previous GLFMSP data (1980–2003) with current results (2004–2009). Temporal profiles show obvious breakpoints between periods of PBDE accumulation and decline in trout for Lakes Huron, Michigan and Ontario with a significant (<i>p</i> < 0.0001 and <i>r</i> = 0.55, 0.72, and 0.51, respectively) decrease in concentration after 2000–2001. A similar transition was observed in Lake Superior for the nearshore site accompanied by a less significant decreasing trend (<i>p</i> = 0.016, <i>r</i> = 0.33), suggesting concentrations are declining very slowly or have leveled off. In contrast, Lake Erie walleye concentrations began leveling off in the late 1990s and no statistically significant trend (increasing or decreasing) has been observed in recent years. A decrease in the BDE-47/BDE-153 ratio was also recently observed, suggesting a transition to more highly brominated PBDEs is occurring in Great Lakes trout. This study provides region-wide evidence that PBDE concentrations are generally declining in Great Lakes trout, although there are clear exceptions to this trend. Results from this study reflect the positive impact of the 2004 PentaBDE ban on macro-scale aquatic freshwater ecosystems

Age-Corrected Trends and Toxic Equivalence of PCDD/F and CP-PCBs in Lake Trout and Walleye from the Great Lakes: 2004–2014

Our research reports polychlorinated dibenzo-<i>p</i>-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (CP-PCBs) concentrations and age-corrected trends for lake trout and walleye in the Great Lakes over the 2004–2014 period. We determined that age–contaminant corrections are required to accurately report contaminant trends due to significant lake trout age structure changes. The age-trend model (ATM) described here uses a lake-specific age–contaminant regression to mitigate the effect of a fluctuating lake trout age structure to directly improve the log–linear regression model. ATM results indicate that half-life (<i>t</i>_1/2) and percent decreases for PCDD/Fs, CP-PCBs, and toxic equivalence (TEQ) (average −56 to 70%) were fairly uniform and consistent across the Great Lakes over the 2004–2014 period. The vast majority of TEQ associated with all Great Lakes lake trout and walleye samples is due to the nonortho CP-PCBs (average = 79%) as compared with PCDD/Fs (average = 21%). On average, CP-PCB_126 individually accounted for over 95% of the total CP-PCB TEQ. A retrospective analysis (1977–2014) of 2378-TCDF and 2378-TCDD raw concentrations in Lake Ontario lake trout revealed decreases of 94% and 96%, respectively. Tissue residue guidelines for wildlife protection based on lake trout and walleye total TEQ were uniformly exceeded in all the Great Lakes