Concentrations, toxic equivalence, and age-corrected trends of legacy organic contaminants in Lake Champlain lake trout: 2012-2018

Our study is the first comprehensive, multi-year assessment of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), polychlorinated naphthalenes (PCNs), polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans (PCDD/Fs) lake trout concentrations and trends in Lake Champlain (LC). Lake trout whole-fish, fillets, and eggs were collected over the 2012-2018 study period. Total PCB concentrations (395.7 ng/g wet weight (ww)) were the highest average concentration of any contaminant grouping reported in this study. Whole-fish lake trout modeling revealed highly significant (p < 0.05) log-linear correlations for all dioxin-like contaminants measured. Overall contaminant decreases for the 2012-2018 period ranged from 20.9% (total PCNs) to 39.3% (2378-TCDD). Contaminant decreases for total PCBs and total-5-PBDEs were 30.9% and 48.3%, respectively. Of particular significance were the measured total PBDE concentrations (74.3 ng/g ww) found in LC whole-fish lake trout. Log-linear forecasting indicates that whole-fish lake trout TEQs will be below the guidelines protective of wildlife thresholds during the periods 2035-2047 (TRG_bird) and 2062-2088 (TRG_mammal). Based on current USEPA guidelines, all lake trout fillets from Lake Champlain analyzed for this study exceed the human health cancer screening value of 0.15 pg-TEQ/g ww by a substantial margin (average = 8.61 pg-TEQ/g ww). Dioxin-like trend data collected for Lake Champlain indicates that the mechanisms of contaminant uptake, trends, and yearly percent decline reflect those found in the Great Lakes.