Sonne Christian, Dietz Rune, Leifsson Pall S, Asmund Gert, Born Erik W, Kirkegaard Maja
Section for Contaminants, Effects and Marine Mammals, Department of Arctic Environment, National Environmental Research Institute, University of Aarhus, Frederiksborgvej, Roskilde, Denmark.
Environ Health. 2007 Apr 17;6:11. doi: 10.1186/1476-069X-6-11.
In the Arctic, polar bears (Ursus maritimus) bio-accumulate mercury as they prey on polluted ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus). Studies have shown that polar bears from East Greenland are among the most mercury polluted species in the Arctic. It is unknown whether these levels are toxic to liver and kidney tissue.
We investigated the histopathological impact from anthropogenic long-range transported mercury on East Greenland polar bear liver (n = 59) and kidney (n = 57) tissues.
Liver mercury levels ranged from 1.1-35.6 microg/g wet weight and renal levels ranged from 1-50 microg/g wet weight, of which 2 liver values and 9 kidney values were above known toxic threshold level of 30 microg/g wet weight in terrestrial mammals. Evaluated from age-correcting ANCOVA analyses, liver mercury levels were significantly higher in individuals with visible Ito cells (p < 0.02) and a similar trend was found for lipid granulomas (p = 0.07). Liver mercury levels were significantly lower in individuals with portal bile duct proliferation/fibrosis (p = 0.007) and a similar trend was found for proximal convoluted tubular hyalinisation in renal tissue (p = 0.07).
Based on these relationships and the nature of the chronic inflammation we conclude that the lesions were likely a result of recurrent infections and ageing but that long-term exposure to mercury could not be excluded as a co-factor. The information is important as it is likely that tropospheric mercury depletion events will continue to increase the concentrations of this toxic heavy metal in the Sub Arctic and Arctic marine food webs.
在北极地区，北极熊（ Ursus maritimus ）捕食受污染的环斑海豹（ Phoca hispida ）和髯海豹（ Erignathus barbatus ），从而生物累积汞。研究表明，来自东格陵兰的北极熊是北极地区汞污染最严重的物种之一。目前尚不清楚这些汞含量对肝脏和肾脏组织是否有毒性。
我们调查了人为远距离传输的汞对东格陵兰北极熊肝脏（ n = 59 ）和肾脏（ n = 57 ）组织的组织病理学影响。
肝脏汞含量范围为 1.1 - 35.6 微克 / 克湿重，肾脏汞含量范围为 1 - 50 微克 / 克湿重，其中 2 个肝脏样本值和 9 个肾脏样本值高于陆地哺乳动物已知的 30 微克 / 克湿重的毒性阈值水平。通过年龄校正的协方差分析评估，可见伊托细胞的个体肝脏汞含量显著更高（ p < 0.02 ），脂质肉芽肿也有类似趋势（ p = 0.07 ）。门静脉胆管增生 / 纤维化个体的肝脏汞含量显著更低（ p = 0.007 ），肾组织近端曲管玻璃样变也有类似趋势（ p = 0.07 ）。
基于这些关系以及慢性炎症的性质，我们得出结论，这些病变可能是反复感染和衰老的结果，但不能排除长期接触汞作为一个辅助因素。该信息很重要，因为对流层汞消耗事件可能会继续增加北极和亚北极海洋食物网中这种有毒重金属的浓度。
