PH07 Environmental Chemistry and Toxicology of Chiral Pollutants
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(PH072) Bioaccumulation of Chiral Organochlorine Compounds by freshwater invertebrates.

Warner, N1, Wong, C1, 1 Universtiy of Alberta, Edmonton, Alberta, Canada

ABSTRACT- Chiral polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides were exposed to the freshwater invertebrate species, Mysis relicta, to determine if these macrozooplankton have the ability to bioaccumulate and biotransform these chemicals stereoselectively. Chiral compounds exist as two stereoisomers that have the same chemical/physical properties, but may differ in their toxicological effects and rates of biotransformation. Previous work using achiral indicators has found no evidence for biotransformation of PCBs and other persistent OC pollutants in low trophic level organisms such as invertebrates. Chiral analysis, however, found non-racemic enantiomer fractions (EFs) for macrozooplankton present in the Lake Superior aquatic food web. This suggests that stereoselective biotransformation in these organisms may be occurring; unlike achiral indicators, chiral analysis specifically traces stereoselective processes (i.e. biotransformation) that are not influenced by nonstereoselective processes (i.e. uptake/depuration). In this experiment, mysids collected from unimpacted lakes in the Canadian Rockies were exposed to sediments contaminated with racemic amounts of chiral PCBs, chlordanes, and a-hexachlorocyclohexane. Non-racemic EFs present in Mysis Relicta from this experiment provide insight into the biomagnification pathways of chiral contaminants as well as the metabolism at lower trophic levels.

Key words: Mysis Relicta, Chiral organochlorine pollutants, Bioaccumulation, Biotransformation

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