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) hepato pancreas, which were obtained for monitoring and assessment purposes at Bri tish Columbia, Canada, marine pulp mill sites between 1990 and 1995, were u sed to calculate biota-sediment accumulation factors (BSAFs) for individual chlorinated dibenzo-p-dioxin and dibenzofuran congeners (PCDD/Fs). The BSA Fs for individual pairs of samples were highly variable, and no systematic trends were apparent in the observed accumulation factors over time, with c rab size, with crab lipid concentration, with sediment percent organic carb on, or among mill sites or depositional environments. Composition and sourc e differences in sedimentary PCDD/Fs, which are apparent as principal compo nents analysis class separations in the sediment data set, also did not cor relate with differences in BSAFs. This independence from environmental fact ors provides a valuable endorsement of the BASF concept for the formulation of aquatic effects-based sediment-quality criteria and human risk-assessme nt guidelines. However, BSAF values did exhibit a significant, nonlinear de crease with increasing log K-ow and with sediment and crab PCDD/F concentra tions. The correlation between BSAFs and sediment concentrations accounts f or between 14 and 81% of the variability in the BSAF values. The PCDD/F con geners that are present in low concentrations and/or have reduced bioavaila bility are the congeners that have the strongest correlations between the B SAFs and the sediment PCDD/F concentrations. Congeners that are bioavailabl e to Dungeness crab exhibit poorer correlations between the BSAFs and sedim ent concentrations.