Biotransformation of commercial chemicals in food-webs

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This research program aims to enhance knowledge of the environmental fate and effects of commercial chemicals and to develop better methods for measuring & assessing chemical exposure and risks to wildlife & humans in support of national and international initiatives to protect human and environmental health. Previous research involved the role of physical-chemical factors controlling the bioaccumulation of chemicals in aquatic and terrestrial food-webs. The proposed research investigates the role of biotransformation on bioaccumulation in food-webs. The lack of methods to measure biotransformation rates and the subsequent lack of biotransformation data for most commercial substances have now been identified as a key scientific knowledge gap in the on-going evaluation of the fate and effects of chemicals in the environment. The goal of the research is (i) to develop methods for determining the rate of biotransformation of chemicals in in-vitro and in-vivo studies and (ii) to investigate the relationship between biotransformation rates measured in in-vitro and in-vivo studies and in the field and (iii) to develop and test mathematical bioaccumulation models for metabolizing substances that can be used for regulatory purposes. The research includes 4 projects involving a common set of chemical substances. Project 1 includes the development of a novel in-vitro dosing system to measure in-vitro biotransformation rates of extremely hydrophobic substances in liver and intestinal homogenates. Project 2 develops and applies methods for measuring in-vivo biotransformation rates in rats and rainbow trout. Project 3 involves the development of a pharmacokinetic model for relating in-vitro and in-vivo biotransformation rates. Project 4 develops and tests a food-chain bioaccumulation model for substances that undergo biotransformation. This research produces benefits to (i) wildlife and human health (by identifying harmful substances), (ii) chemical manufacturers (by improving regulatory chemical evaluation protocols), (iii) environmental consulting industry (by establishing know-how on biotransformation test protocols, and (iv) supports the Canadian government in their national and international initiatives of chemical stewardship.