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

水生鸟类在其生态系统中不断暴露于遗留物（多氯联苯、滴滴涕等）。以及最近引入的（新兴的）有机卤化污染物（OHC）。新出现的有机碳氢化合物可能包括产品添加剂，以达到消防安全标准（溴化阻燃剂）和表面活性剂（多氟烷基物质）。其中一些OHC目前被生产和用于消费品，并被释放到水生环境中。目前缺乏知识的环境来源，生物转化能力和加拿大野生动物，特别是生活在污染最严重的地区的水生物种，这些新兴的OHCs的生物影响。拟议的研究将利用蒙特利尔岛附近圣劳伦斯河流域一个高度污染地区繁殖的一种广泛分布的水鸟（环嘴鸥）来解决这些问题。本提案的主要目标是：1）确定新出现的OHC的饮食来源（2）通过测定海鸥肝脏中代谢酶的催化活性、含量和降解能力，探讨新出现的OHC在体外系统中的生物转化机制，以及3）研究这些鸟类中新出现的OHC的组织/血液浓度是否与它们的每日能量消耗和参与代谢功能的激素（甲状腺激素和皮质酮）的血液水平的变化相关。这项工作的新奇和预期的重要性在于，它首次结合了一种新的卫星技术来跟踪鸟类的活动、内分泌参数、每日能量消耗的衡量标准和生态毒理学数据。从拟议的研究预期的结果将提供新的知识，在加拿大环境中出现的化学压力的动态和毒理学影响。这项研究还将为加拿大目前和今后的化学品风险评估和生态系统健康生物监测提供重要信息。

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.