Emerging organohalogen contaminants in a bioindicator bird from the St. Lawrence River basin: dietary sources, toxicokinetics and endocrine and bioenergetics effects.

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Aquatic birds are continuously exposed in their ecosystem to legacy (PCB, DDT, etc.) and to more recently introduced (emerging) organohalogenated contaminants (OHCs). Emerging OHCs may include product additives to achieve fire safety standards (brominated flame retardants-BFRs) and surface-active agents (polyfluorinated alkyl substances-PFASs). Some of these OHCs are currently produced and used in consumer products, and are released into the aquatic environment. There is at present a dearth of knowledge on the environmental sources, biotransformation capacity and biological effects of these emerging OHCs in Canadian wildlife, particularly in aquatic species that live in the most severely polluted areas. The proposed research will address these issues using a widespread aquatic bird (ring-billed gull) breeding in a highly polluted area in the St. Lawrence River basin near the Montreal Island. The main objectives of the present proposal are: 1) to determine the dietary sources of emerging OHCs (PFASs and BFRs) to the gulls using a new satellite-based tracking system, 2) to investigate the mechanisms of biotransformation of emerging OHCs in an in vitro system by measuring the catalytic activity, content and degradation capacity of metabolizing enzymes in gull liver, and 3) to study whether the tissue/blood concentrations of emerging OHCs in these birds are associated with changes in their daily energy expenditure and blood levels of hormones that are involved in metabolic functions (thyroid hormones and corticosterone). The novelty and expected significance of this work is that it combines for the first time a new satellite technology to track bird movements, endocrine parameters, a measure of daily energy expenditure and ecotoxicological data. The results anticipated from the proposed research will provide new knowledge on the dynamics and toxicological effects of emerging chemical stressors in the Canadian environment. This research will also generate critical information for ongoing and future chemical risk assessments and ecosystem health biosurveillance in Canada.