De Guise S, Martineau D, Béland P, Fournier M
TOXEN, Université du Québec à Montréal, Canada.
Environ Health Perspect. 1995 May;103 Suppl 4(Suppl 4):73-7. doi: 10.1289/ehp.95103s473.
A small isolated population of beluga whales (Delphinapterus leucas) that are highly contaminated by pollutants, mostly of industrial origin, resides in the St. Lawrence estuary, Québec, Canada. Overhunting in the first half of the century was the probable cause for this population to dwindle from several thousand animals to the current estimate of 500. The failure of the population to recover might be due to contamination by organochlorine compounds, which are known to lead to reproductive failure and immunosuppression in domestic and laboratory animals and seals. Functional and morphological changes have been demonstrated in thyroid gland and adrenal cortex in many species exposed to organochlorinated compounds, including seals. Morphological lesions, although different, were also found in belugas. Functional evaluation of thyroid and adrenal glands of contaminated (St. Lawrence) versus much less contaminated (Arctic) belugas is currently under way. Necropsy of St. Lawrence belugas showed numerous severe and disseminated infections with rather mildly pathogenic bacteria, which suggests immunosuppression. Organochlorine compounds and other contaminants found in beluga whales cause immunosuppression in a variety of animal species including seals. Thirty-seven percent of all the tumors reported in cetaceans were observed in St. Lawrence beluga whales. This could be explained by two different mechanisms: high exposure to environmental carcinogens and suppression of immunosurveillance against tumors. Overall, St. Lawrence belugas might well represent the risk associated with long-term exposure to pollutants present in their environment and might be a good model to predict health problems that could emerge in highly exposed human populations over time.
一小群孤立的白鲸（白鲸属）生活在加拿大魁北克省的圣劳伦斯河口，它们受到污染物的高度污染，这些污染物大多源自工业。在本世纪上半叶的过度捕猎可能是导致该种群数量从数千头减少到目前估计的500头的原因。种群未能恢复可能是由于有机氯化合物的污染，已知这些化合物会导致家养动物、实验动物和海豹出现生殖功能衰竭和免疫抑制。在包括海豹在内的许多接触有机氯化合物的物种中，甲状腺和肾上腺皮质已出现功能和形态变化。白鲸身上也发现了形态学病变，尽管有所不同。目前正在对受污染（圣劳伦斯）和污染程度低得多（北极）的白鲸的甲状腺和肾上腺进行功能评估。对圣劳伦斯白鲸的尸检显示，它们受到了大量致病性相当温和的细菌的严重且广泛的感染，这表明存在免疫抑制。在白鲸体内发现的有机氯化合物和其他污染物会导致包括海豹在内的多种动物物种出现免疫抑制。在鲸类动物报告的所有肿瘤中，37%出现在圣劳伦斯白鲸身上。这可以用两种不同的机制来解释：高暴露于环境致癌物以及对肿瘤免疫监视的抑制。总体而言，圣劳伦斯白鲸很可能代表了长期接触其环境中存在的污染物所带来的风险，并且可能是预测随着时间推移在高暴露人群中可能出现的健康问题的一个良好模型。
