Aarhus University, Faculty of Science and Technology, Department of Bioscience, Arctic Research Centre (ARC), Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark.
Wildlife Management Division, Department of Environment, Government of Nunavut, PO Box 209, Igloolik NU X0A 0L0, Canada.
Environ Res. 2015 Feb;137:287-91. doi: 10.1016/j.envres.2014.12.026. Epub 2015 Jan 16.
Industrially produced chemicals have been a major environmental concern across our entire Globe since the onset of rapid industrial development around the early 1900. Many of the substances being used are known to be endocrine disrupting chemicals (EDCs) and are also known to be long-range dispersed and to biomagnify to very high concentrations in the tissues of Arctic apex predators such as polar bears (Ursus maritimus). A major concern relating to EDCs is their effects on vital organ-tissues such as bone and it is possible that EDCs represent a more serious challenge to the species' survival than the more conventionally proposed prey reductions linked to climate change. We therefore analyzed penile bone mineral density (BMD) as a key phenotype for reproductive success in 279 polar bear samples born 1990-2000 representing eight polar bear subpopulations. Since EDC concentrations were not available from the same specimens, we compared BMD with published literature information on EDC concentrations. Latitudinal and longitudinal BMD and EDC gradients were clearly observed, with Western Hudson bears having the highest BMD and lowest EDCs, and North East Greenland polar bears carrying the lowest BMD and highest EDCs. A BMD vs. polychlorinated biphenyls (PCB) regression analysis showed that BMD decreased as a function of the eight subpopulations' PCB concentrations and this relationship was close to being significant (p=0.10, R(2)=0.39). Risk quotient (RQ) estimation demonstrated that PCBs could be in a range that may lead to disruption of normal reproduction and development. It is therefore likely that EDCs directly affect development and bone density in polar bears. Canadian bears had in general the best health and the North East Greenland subpopulation being at the highest risk of having negative health effects. While reductions in BMD is in general unhealthy, reductions in penile BMD could lead to increased risk of species extinction because of mating and subsequent fertilization failure as a result of weak penile bones and risk of fractures. Based on this, future studies should assess how polar bear subpopulations respond upon EDC exposure since information and understanding about their circumpolar reproductive health is vital for future conservation.
自 1900 年代初快速工业化发展以来，工业生产的化学物质一直是全球范围内的主要环境关注点。许多正在使用的物质被认为是内分泌干扰化学物质（EDCs），并且已知它们具有长距离分散性，并在北极顶级捕食者（如北极熊（Ursus maritimus））的组织中生物放大到非常高的浓度。与 EDC 相关的一个主要问题是它们对骨骼等重要器官组织的影响，而且 EDC 可能代表对物种生存的更严重挑战，而不是与气候变化相关的更传统的提议的猎物减少。因此，我们分析了阴茎骨矿物质密度（BMD）作为 279 只 1990-2000 年出生的北极熊样本繁殖成功的关键表型，这些样本代表了八个北极熊亚种群。由于无法从同一标本中获得 EDC 浓度，因此我们将 BMD 与已发表的 EDC 浓度文献信息进行了比较。明显观察到纬度和经度 BMD 和 EDC 梯度，哈德逊湾西部的熊具有最高的 BMD 和最低的 EDC，而东北格陵兰的北极熊则具有最低的 BMD 和最高的 EDC。BMD 与多氯联苯（PCB）回归分析表明，BMD 随着八个亚种群 PCB 浓度的函数而降低，并且这种关系接近显著（p=0.10，R（2）=0.39）。风险商（RQ）估计表明，PCBs 可能处于可能导致正常繁殖和发育中断的范围内。因此，EDCs 可能直接影响北极熊的发育和骨密度。加拿大的熊总体上健康状况最好，而东北格陵兰亚种群则处于健康状况恶化的最高风险中。虽然 BMD 降低通常是不健康的，但由于阴茎骨骼较弱和骨折风险导致交配和随后受精失败，阴茎 BMD 的降低可能会导致物种灭绝的风险增加。基于此，未来的研究应该评估北极熊亚种群在接触 EDC 后的反应，因为了解它们的环极繁殖健康状况对于未来的保护至关重要。
