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1J - Bioaccumulation (WE9/7) Bioaccumulation of Phthalate Esters in an Aquatic Food-Web. Gobas, Frank1, Mackintosh, Cheryl1, Webster, Glenys1, Maldonado, Javier1, Ratzlaff, Deborah1, Ikonomou, Michael2, 1 Simon Fraser University, Burnaby, BC, Canada2 Contaminants Science Section, Institute for Ocean Sciences, Sidney, BC, Canada ABSTRACT- This paper summarizes the results of a large scale bioaccumulation field study in a marine ecosystem and several laboratory studies of the aqueous and dietary uptake, distribution and metabolism of individual and complex mixtures of phthalate ester congeners (PE's). The purpose of the presentation is to explain field observations of the distribution of phthalate esters in aquatic food-webs in terms of the mechanisms controlling the uptake and behavior of phthalate esters in aquatic organisms. Field measurements, involving co-analyses of PCBs and phthalate esters, show that while PCBs exhibit a high degree of food-chain bioaccumulation, none of the phthalate esters studied biomagnified in the food-web. The results suggest that dietary uptake of di-alkylesters is very low. This is supported by dietary bioaccumulation experiments in the laboratory that illustrate a rapid metabolic transfromation in the gastro-intestinal system and low uptake rates compared to co-administered PCBs. The presence of mono-alkyl phthalate esters in intestinal samples show that hydrolysis is a key metabolic process causing low dietary uptake rates of the dialkylphthalate esters. Bioconcentration experiments illustrate that lower molecular weight phthalate esters are efficiently absorbed from the water and that there is evidence of metabolic transfromation in the liver. The combined results illustrate that while phthalate esters and PCBs constitute a group of very hydrophobic chemicals with high Kow, phthalate esters do not appear to share the PCB's properties to biomagnify in aquatic food-webs. Key words: Phthalate esters, Bioaccumulation, PCBs, Fish |
