Biotransformation of environment contaminants in biota

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The environment is a top priority for Canadians. More specifically, Canadians are concerned about the presence of chemical contaminants in their bodies and the health effects of these contaminants. In my research program, we are studying the metabolism, fate, and toxicity of two major classes of contaminants, namely polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). These chemicals are persistent, accumulate in food chains, and have been detected at relatively high levels in tissues from humans and wildlife. The main route for the metabolism and subsequent elimination of these chemicals in humans and other animals starts with hydroxylation reactions. The reactions occur in the liver and are catalyzed by family of enzymes called the cytochrome P450 enzymes. Building on work conducted during the tenure of my current NSERC grant, we will use recently developed assays to measure the rate and extent of metabolism of PCBs and PBDEs in humans and various wildlife species. We will also study the toxic effects of the hydroxy-metabolites produced. Increased understanding of the metabolism of chemical contaminants is important for evaluating possible mechanisms of toxicity and for assessing an organism's capacity to accumulate or eliminate these contaminants. This information will provide a measure of how well humans and wildlife are able to cope with contaminant exposure and will help define a threshold between tolerable and intolerable levels of contaminant exposure. It may also be useful in predicting which species might be most at risk. This research is relevant to all Canadians, and especially those exposed to high levels of PBDEs or PCBs via diet, workplace or other environmental factors.