BIOAVAILABILITY OF CHLORINATED DIBENZO-p-DIOXINS AND DIBENZOFURANS TO DUNGENESS CRAB (CANCER MAGISTER) AT MARINE PULP MILL SITES IN BRITISH COLUMBIA, CANADA

Synchronous samples of sediment and Dungeness crab (Cancer magister) hepatopancreas, which were obtained for monitoring and assessment purposes at British Columbia, Canada, marine pulp mill sites between 1990 and 1995, were used to calculate biota-sediment accumulation factors (BSAFs) for individual chlorinated dibenzo-p -dioxin and dibenzofuran congeners (PCDD/Fs). The BSAFs for individual pairs of samples were highly variable, and no systematic trends were apparent in the observed accumulation factors over time, with crab size, with crab lipid concentration, with sediment percent organic carbon, or among mill sites or depositional environments. Composition and source differences in sedimentary PCDD/Fs, which are apparent as principal components analysis class separations in the sediment data set, also did not correlate with differences in BSAFs. This independence from environmental factors provides a valuable endorsement of the BASF concept for the formulation of aquatic effects-based sediment-quality criteria and human risk-assessment guidelines. However, BSAF values did exhibit a significant, nonlinear decrease with increasing log Kow and with sediment and crab PCDD/F concentrations. The correlation between BSAFs and sediment concentrations accounts for between 14 and 81% of the variability in the BSAF values. The PCDD/F congeners that are present in low concentrations and/or have reduced bioavailability are the congeners that have the strongest correlations between the BSAFs and the sediment PCDD/F concentrations. Congeners that are bioavailable to Dungeness crab exhibit poorer correlations between the BSAFs and sediment concentrations.