Understanding the Factors Driving Intra-Specific Tissue Variations, and the Endocrine and Metabolic Impacts of Flame Retardant Exposure in Birds

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A growing number of new organic contaminants of potential environmental concern are constantly discharged into terrestrial and aquatic ecosystems in industrialized regions, and have the potential to bioaccumulate and be toxic to the most susceptible wildlife species such as birds. This may be the case for the numerous emerging halogenated flame retardants (HFRs) for which no national or international regulations exist despite their massive usage in a wide range of consumer and industrial products (e.g., cars, electronic circuitry, upholstered furniture, construction materials, etc.) to achieve fire safety standards, that is, to slow down the spread of fire. A recent study conducted by my research group reported unexpectedly high concentrations of the HFR class polybrominated diphenyl ethers (PBDEs) as well as several as yet undetected emerging HFRs in tissues of a urban-adapted avian species, the ring-billed gull (Larus delawarensis), breeding in the Montreal area. Evidence from my laboratory suggests that the endocrine system (e.g., thyroid hormone levels) and certain related endpoints (e.g., bone metabolism) may be adversely affected in the most HFR-exposed ring-billed gulls. Using the ring-billed gull as bioindicator species of environmental HFR exposure and ecosystem health in the greater Montreal area and St. Lawrence River, the proposed research program aims to investigate in ring-billed gulls: 1) the bioaccumulation dynamics and maternal transfer of novel and emerging HFRs of suspected health concern to wildlife species, 2) the biotransformation capacity towards selected high-priority PBDEs and emerging HFRs via analysis of the expression, substrate specificity, and catalytic activity of hepatic enzymes, and 3) the exposure-related effects of PBDEs and emerging HFRs on hypothalamic-pituitary-thyroid (HPT) and -adrenal (HPA) axes via analysis of thyroid and glucocorticoid hormone levels, transcription of selected genes involved in the regulation of these endocrine axes as well as energy expenditure (metabolic rates). The novelty and expected significance of this work is that the bioaccumulation, biotransformation, and exposure-related health impacts (e.g., endocrine, enzymatic, and metabolic) on animals exposed to currently-used contaminants including HFRs are understudied fields of research. One other significant aspect of this work is the comparative approach, that is, the examination of differences in chemically-induced effects among naturally-exposed bird populations (wild gull) and a captive avian model (chicken). This proposed research program will thus provide new knowledge on the dynamics and bioactivity of novel chemical stressors in the Canadian environment. Furthermore, it represents a unique HQP training opportunity in novel aspects of animal bioenergetics, ecotoxicology, toxicokinetics, analytical chemistry, and endocrinology.