Biotransformation and thyroidogenic effects of organochlorine and organobromine pollutants in avian and mammalian top predator sentinel species

在环境中持续存在并生物积累的人造化学物质越来越多地与对野生动物和人类的不利影响有关。野生动物中发现的许多生物累积的“遗留”和“新出现的”污染物含有氯和溴，包括多氯联苯(PCbs)和称为多溴联苯醚(PBDEs)的溴化阻燃剂(BFR)类别。生物体从体内清除有机卤素和其他外来化学物质的能力依赖于能够调节新陈代谢和生物转化的酶。关于生物转化(例如，氧化和脱溴过程)在氯化和溴化有机卤素的去向和生物积累中的作用和意义，包括在不同物种和食物网中，特别是在顶级捕食性野生动物中形成含有羟基(OH-)或“酚类”的代谢物，目前尚不清楚。正如一些野生动物中的多氯联苯和多溴二苯醚所显示的那样，生物转化可以导致持久性的羟基多氯联苯和羟基多溴二苯醚的代谢物，尽管对这些“二级”污染物的形成、生物积累和毒物动力学仍知之甚少。羟基多氯联苯、羟基多溴联苯醚、相关的酚类化合物/代谢物、多溴联苯醚的脱溴产物和目前使用的BFR通过激素模拟具有“生物活性”，并可干扰甲状腺激素依赖的功能和过程(例如，激素运输和酶介导的相互转化)。与有机卤素生物转化有关的内分泌(甲状腺)活动及其影响在顶级捕食者、海洋野生动物中受到的关注很少，因为海洋野生动物积累了较高的有机卤素水平。拟议的研究将扩大对物种特有的作用、机制和环境生态重要性的新研究，并对生物转化在五大湖(鲱鸥)和北极(北极熊和灰鸥)的命运、生物积累和甲状腺激素运输/相互转化中的特定物种作用、生物积累和甲状腺激素运输/相互转化、对顶级捕食者野生动物中遗留和新出现的氯化和溴化有机物以及来自五大湖(鲱鸥)和北极(北极熊和灰鸥)的其他(例如气候变化)压力的作用进行新的研究。

Man-made chemicals that persist and bioaccumulate in the environment are increasingly being linked to adverse effects in wildlife and humans. Many bioaccumulative "legacy" and "emerging' contaminants found wildlife contain chlorine and bromine, including polychlorinated biphenyls (PCBs) and the brominated flame retardant (BFR) class known as polybrominated diphenyl ethers (PBDEs). An organism's ability to eliminate organohalogens and other foreign chemicals from the body is dependent on enzymes that can mediate metabolism and biotransformation. Much remains unknown as to role and significance of biotransformation (e.g., oxidative and debromination processes) in the fate and bioaccumulation of chlorinated and brominated organohalogens, which includes the formation of hydroxyl- (OH-) containing or "phenolic" metabolites, in different species and food webs, and especially in top predator wildlife. As has been shown for PCBs and PBDEs in some wildlife, biotransformation can lead to persistent OH-PCB and OH-PBDE metabolites, although there remains minimal understanding of the formation, bioaccumulation and toxicokinetics of these "second level" pollutants. OH-PCBs, OH-PBDEs, related phenolic compounds/metabolites, and debrominated products of PBDEs and current-use BFRs are "bioactive" via hormone mimicry, and can interfere with thyroid hormone-dependent functions and processes (e.g., hormone transport and enzyme-mediated inter-conversion). Endocrine (thyroid) activity and effects in relation to organohalogen biotransformation has received minimal attention in top predator, marine wildlife, which accumulate high organohalogen levels. The proposed research will expand the understanding and commence with new research on the species-specific role, mechanisms and environmental ecological importance and significance of biotransformation in the fate, bioaccumulation and thyroid hormone transport/inter-conversion, on legacy and emerging, chlorinated and brominated organics in top-predator wildlife sentinels of contaminant and other (e.g., climate change) stresses from the Great Lakes (herring gulls) and the Arctic (polar bears and glaucous gulls).