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(38-08) Does exposure route influence bioavailability, toxicity and metabolism of fluoranthene in Capitella sp. I? Selck, Henriette*,1, Palmqvist, Annemette1, Forbes, Valery1, 1 Roskilde University, Dept. of Life Sciences and Chemisty, Roskilde, Denmark ABSTRACT- It is increasingly recognized that ingestion of sediment-bound toxicants may be an important exposure route for deposit feeders. However there is a lack of understanding of the factors controlling toxicant bioavailability from dissolved vs. sediment-bound compartments. Also, it is not known if exposure route affects metabolism, and hence toxicity of organic contaminants. We examined interactions among exposure route, bioavailability of fluoranthene (Flu), metabolism of sediment-associated and dissolved Flu and toxicity in polychaete worms (Capitella sp. I). 14C-Flu was used to examine Flu uptake (5-10 d), depuration (4-5 d) and metabolism. Individual Capitella were exposed to either dissolved- (Water-Only) or both dissolved and sediment-bound Flu (Porewater & Sediment). At specific time intervals individuals were analyzed for concentrations of parent Flu (P), water-soluble Flu-conjugates (C), Flu-metabolites (M) and tissue residue (R). Toxicity was assessed as changes in growth- (WO, PWS) and egestion rate (PWS). Toxicity was only detected in WO, despite a 7.5 times higher total Flu uptake and a 1.4 times higher volume-specific body-burden (BB) in PWS compared to WO. However, C constituted a greater and P a smaller fraction of the total uptake in WO compared to PWS. Worms in PWS decreased BB by 90 % whereas worms in WO did not depurate Flu significantly. Depuration did not affect the percent distribution of Flu within WO worms, but C, P and R were higher and M lower in PWS worms after depuration. Thus uptake from the sediment-associated pool may result in higher body burdens of metabolites than parent compound compared to uptake from the dissolved phase. This underscores the need to understand the potential for trophic transfer of metabolites to consumers of benthic invertebrates. Key words: PAH, exposure routes, metabolism, bioavailability |
