The liver plays an important role in the metabolism and elimination of endogenic and exogenic lipid-soluble compounds. Multiple studies have shown that polychlorinated biphenyls (PCB) and dichlorodiphenyl trichloroethane (DDT) lead to morphological changes in liver cells. The aim of the present study was therefore to analyse liver changes over time in Baltic grey seals (Halichoerus grypus) and to correlate these with historical PCB and DDT contaminations. A total of 191 liver samples were collected between 1981 and 2015 in the Gulf of Bothnia and northern Baltic Proper. Six histological features were evaluated, including portal mononuclear cell infiltration, random mononuclear cell infiltration, lipid granulomas, hepatocellular fat vacuoles, hepatic stellate cells and mild multifocal bile duct hyperplasia accompanied by portal fibrosis. Three of the six lesions showed a significant correlation with age. Furthermore, a positive correlation between portal mononuclear cell infiltration and mild multifocal bile duct hyperplasia was found. Additionally, lipid granulomas were significantly correlated with hepatic stellate cells. More importantly, hepatic stellate cells and mild multifocal bile duct hyperplasia were correlated with adipose tissue (blubber) concentrations of ƩPCB, measured in a subsample (n = 34) of all individuals. No correlation with lesions and ƩDDT concentrations were found. These results show that age is an important factor for the development of these liver lesions, but PCBs burden may be an influencing factor. This is in agreement with previous studies of marine mammals in the Baltic Sea as well as in the Arctic. We therefore conclude that not only age of the animals, but also exposure to PCBs should be taken into account when understanding and evaluating the current health status of Baltic grey seals.

肝脏在内源性和外源性脂溶性化合物的代谢和消除中起重要作用。多项研究表明，多氯联苯（PCB）和二氯二苯基三氯乙烷（DDT）会导致肝细胞的形态变化。因此，本研究的目的是分析波罗的海灰海豹（Halichoerus grypus），并将其与历史PCB和DDT污染相关联。1981年至2015年之间，在博特尼亚湾和波罗的海北部共采集了191个肝样本。评价了六个组织学特征，包括门静脉单核细胞浸润，随机单核细胞浸润，脂质肉芽肿，肝细胞脂肪液泡，肝星状细胞和轻度多灶性胆管增生并伴有门脉纤维化。六个病变中有三个与年龄呈显着相关性。此外，发现门脉单核细胞浸润与轻度多灶性胆管增生之间存在正相关。另外，脂质肉芽肿与肝星状细胞显着相关。更重要的是，肝星状细胞和轻度多灶性胆管增生与所有组织的亚样本（n = 34）中脂肪组织（脂）的PCB浓度相关。与病变和ƩDDT浓度无相关性。这些结果表明，年龄是这些肝脏病变发展的重要因素，但多氯联苯的负担可能是一个影响因素。这与先前对波罗的海以及北极的海洋哺乳动物的研究一致。因此，我们得出的结论是，在了解和评估波罗的海灰海豹的当前健康状况时，不仅要考虑动物的年龄，还要考虑多氯联苯的暴露。这些结果表明，年龄是这些肝脏病变发展的重要因素，但多氯联苯的负担可能是一个影响因素。这与先前对波罗的海以及北极的海洋哺乳动物的研究一致。因此，我们得出的结论是，在了解和评估波罗的海灰海豹的当前健康状况时，不仅要考虑动物的年龄，还要考虑多氯联苯的暴露。这些结果表明，年龄是这些肝脏病变发展的重要因素，但多氯联苯的负担可能是一个影响因素。这与先前对波罗的海以及北极的海洋哺乳动物的研究一致。因此，我们得出的结论是，在了解和评估波罗的海灰海豹的当前健康状况时，不仅应考虑动物的年龄，还应考虑接触多氯联苯。