Congener-specific model for polychlorinated biphenyl effects on otter (Lutra lutra) and associated sediment quality criteria

A model for risk assessment was built for simultaneous, congener-specific P CB bioaccumulation from sediment to fish to otters (Lutra lutra). Toxic equ ivalence factors (TEFs) were used to sum individual congeners in otters to a toxic equivalent concentration (TEQ) relative to 2,3,7,8-tetrachlorodiben zo-p-dioxin. Microbial dechlorination and burial in sediments and bioaccumu lation are modeled to predict time trends of PCB concentrations in otters. Effects of accumulated PCBs on otters were assessed for vitamin A metabolis m and reproduction, taking model uncertainty into account. Three locations in The Netherlands were modeled with PCB levels in sediment of 1 to 171 pg TEQ/g organic carbon (OC). Almost 100% reduction in litter size was predict ed for the most polluted area in 1996. Due to large associated uncertainty, a period of 25 to 80 years may be needed for recovery of otter vitamin A l evels and litter size at this site. Calculated median sediment quality crit eria (SQC)range between 1 and 12 pg TEQ/g OC, depending on the chosen effec t criterion. Uncertainty in calculated effects and SQCs is substantial and is mainly caused by uncertainty in PCB congener 126 accumulation.