Use of Biota-Sediment Accumulation Factors to assess similarity of nonionic organic chemical exposure to benthically-coupled organisms of differing trophic mode

Abstract

The U.S. Environmental Protection Agency is in the process of developing Sediment Quality Criteria (SQC) to specify the acceptable degree of risk from sediment-mediated chemical exposure for the protection of benthically-coupled organisms. In this study, potential differences in chemical exposure for benthic organisms of differing habitats or feeding types were evaluated through the use of Biota-Sediment Accumulation Factors (BSAFs). It was hypothesized that If species of different habitats have similar exposures, then the BSAF values should not be different. The BSAFs are calculated using the concentrations of chemicals in an organism (&mgr;g/g lipid) divided by the concentrations of the same chemicals in sediment (&mgr;g/gOC). Data from both freshwater and saltwater studies that met specified criteria for data quality were obtained 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 grouped 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 class and KOW 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 PCBs, the BSAFs for all species exhibited a KOW dependency with decreased bioaccumulation evident above and below the range of 5.99-7.27 log10 KOW. In order to optimize the detection of species/habitat differences in the BSAFs, further analyses were segregated by chemical class and excluded PCB data outside the above KOW range. These analyses revealed similar BSAF values for various species both within and among habitat 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 benthic species and species used to derive WQC FCVs supports the applicability of SQC for all benthic organisms as a group.

Bioaccumulation kinetics of polybrominated diphenyl ethers from estuarine sediments to the marine polychaete, Nereis virens

“…Polybrominated diphenyl ethers with the largest BSAFs 28 (BDEs 28/33, 66) had log K OW of approximately 6 to 7, with lower accumulation of the more hydrophobic congeners. This trend was generally consistent with other studies investigating BDE uptake by deposit feeders [27,28], other studies of HOC uptake by deposit feeders [36], and highly chlorinated PCBs specifically [37]. For HOCs with log K OW greater than 7, bioavailability generally decreases with increasing molecular weight because of stronger associations with sediment particles and lower solubility in water and digestive fluids.…”

Bioavailability of decabromodiphenyl ether to the marine polychaete Nereis virens

“…To compare the relative bioavailability of BDEs among field and spiked sediment treatments, biota-sediment accumulation factors (BSAFs) were calculated for each congener by dividing the lipid-normalized concentration in the worm (ng BDE/g lipid) by the organic carbon-normalized concentration in the sediment (ng BDE/g carbon). Used commonly as a metric for describing the relative bioavailability of a chemical from sediments [28], BSAFs were used to account for differences in organic carbon content between sediments and to facilitate comparisons with 28-d bioaccumulation experiments from other laboratories.…”

Occurrence of butyltin compounds in marine sediments and bivalves from three harbour areas (Saigon, Da Nang and Hai Phong) in Vietnam

“…These values are comparable to the BSAF of TBT (0.4 to 4.6) reported for other marine invertebrates 14,43 and those for neutral hydrophobic compounds such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and pesticides (0.3 to 1.4). 44 Much higher BSAF ranges for TBT (1.9 to 8.0) were reported for lipid tissues of the Asian clam, Potamocorbula amurensis, near Mare Island Naval Shipyard, San Francisco Bay, for which additional partitioning and binding processes were suggested for organotins compounds over the neutral hydrophobic PAHs and PCBs. 42 The bioconcentration factor of TBT between sediment and clam without normalization to organic carbon and lipid content (BCF tissue -sediment ) ranged from 0.23 to 0.60 (wet wt/dry wt) and from 1.0 to 2.7 (dry wt/dry wt).…”