USE OF BIOTA-SEDIMENT ACCUMULATION FACTORS TO ASSESS SIMILARITY OF NONIONIC ORGANIC-CHEMICAL EXPOSURE TO BENTHICALLY-COUPLED ORGANISMS OF DIFFERING TROPHIC MODE

The U.S. Environmental Protection Agency is in the process of developi ng Sediment Quality Criteria (SQC) to specify the acceptable degree of risk from sediment-mediated chemical exposure for the protection of b enthically-coupled organisms. In this study, potential differences in chemical exposure for benthic organisms of differing habitats or feedi ng types were evaluated through the use of Biota-Sediment Accumulation Factors (BSAFs). It was hypothesized that If species of different hab itats have similar exposures, then the BSAF values should not be diffe rent. The BSAFs are calculated using the concentrations of chemicals i n an organism (mu g/g lipid) divided by the concentrations of the same chemicals in sediment (mu g/g(oc)). Data from both freshwater and sal twater studies that met specified criteria for data quality were obtai ned from published papers or reports. These included three laboratory and five field studies containing 27 species and 4054 BSAF values. The BSAFs were intercompared for similarity of central tendency as groupe d by chemical class (PCBs, PAHs, pesticides), individual species, and species grouped by habitat (infaunal deposit feeder, scavenger, filter feeder, and benthically-coupled fish). Plots of BSAFs grouped by clas s and K-ow revealed that the BSAFs for the PAHs were uniformly lower ( mean 0.34) than the PCB (1.03) or pesticide (1.36) classes. For the PC Bs, the BSAFs for all species exhibited a K-ow dependency with decreas ed bioaccumulation evident above and below the range of 5.99-7.27 log( 10) K-ow. In order to optimize the detection of species/habitat differ ences in the BSAFs, further analyses were segregated by chemical class and excluded PCB data outside the above K-ow range. These analyses re vealed similar BSAF values for various species both within and among h abitat groups, and indicated that the sum total of exposures from all routes is similar across species. This similarity of chemical exposure across benthic species, and the similarity of sensitivities between b enthic species and species used to derive WQC FCVs supports the applic ability of SQC for all benthic organisms as a group.