【作者】 张东平；

【导师】 傅家谟； 余应新；

【作者基本信息】 上海大学 ， 环境工程， 2012， 博士

【摘要】 鱼类作为一种动物性食品,含有丰富的n-3系多不饱和脂肪酸,特别是二十碳五烯酸(Eicosapentaenoic acid,EPA)和二十二碳六烯酸(Docosahexaenoic acid,DHA)具有促进婴幼儿生长发育、防治心血管疾病、防癌抗癌等功效,因而鱼类食品受到广大消费者的青睐。然而鱼类也容易富集各类污染物,如多氯联苯(PCBs)和多溴联苯醚(PBDEs)等持久性有机污染物。大量的研究表明鱼类是PCBs和PBDEs对人体暴露的最主要的食物来源之一,因此消费者在食用鱼类时不得不更为谨慎。究竟该不该吃鱼,如何吃鱼开始困扰着广大的消费者。太湖是我国的第二大淡水湖,也是我国重要的渔业基地,但对于该湖区鱼类脂肪酸的含量与组成以及PCBs和PBDEs在鱼类的暴露水平和分布特征很少报道。本研究采集了太湖9种常见鱼类,并选取了其中4种大中型鱼类不同部位的肌肉,测定了其各类脂肪酸的含量与组成特征,分析了其营养价值,并同时测定了其肌肉组织中PCBs和PBDEs的含量与分布特征,并对鱼体肌肉中营养物(EPA+DHA)和污染物(PCBs和PBDEs)共摄入时的益害风险进行了评估。本次所研究的9种太湖鱼类均属于极低脂肪鱼类,鱼体内脂肪酸的含量与鱼体的脂肪含量呈正相关,其肌肉组织的脂肪酸组成以棕榈酸、油酸及DHA为主。PUFA的浓度水平在1.6 - 3.7mg/g湿重之间,EPA+DHA的浓度水平在0.6 - 1.4mg/g湿重之间。四种鱼的背、腹和尾部的肌肉中各类脂肪酸的浓度水平也与该部位的脂肪含量正相关,而与所在的部位无关;背、腹、尾部的肌肉中脂肪酸的组成无明显差异。肝脏中各类脂肪酸含量最高,肌肉的含量最低,各组织中脂肪酸的百分组成存在种间及组织差异,可能与各组织的生理功能不同有关。九种太湖鱼类其混合肌肉中PCBs和PBDEs浓度范围分别为278.6 - 1 071.3和98.2 - 268.5 pg/g湿重,与国内其他中等污染湖区的鱼样浓度相当,低于美国挪威等国淡水鱼中的浓度。与2009年采集的样品相比,两种污染物的浓度均略有降低。四种鱼类中3个不同部位(背、腹、尾)的肌肉样品中PCBs和PBDEs浓度差别较大,这与不同部位的脂肪含量及污染物的亲脂性差异有关,4种鱼类的背部肌肉样品中PCBs和PBDEs的平均浓度最低;PCBs浓度最高出现尾部肌肉中,PBDEs浓度最高出现腹部肌肉中。太湖9种鱼的混合肌肉及4种鱼的背、腹、尾部肌肉具有较高的PUFA/SFA比值和较低的n-6/n-3 PUFA比值,表明这9种鱼及4种鱼的背、腹和尾部肌肉中脂肪酸均具有较高的营养价值。在同时考虑鱼体中EPA+DHA的益处和PCBs的健康危害时,发现在达到EPA+DHA建议摄入量(250 mg/d)的情况下,健康成人食用这9种鱼的混合肌肉不会带来致癌与非致癌的健康风险。食用花鲢、白鲢、鲤鱼及翘嘴红鲌的背、腹和尾部肌肉均不会带来非致癌的健康风险。但食用翘嘴红鲌腹部肌肉会有潜在的致癌风险。更多还原

【Abstract】 As a kind of animal-based food, fish contain high levels of n-3 polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are important for neurodevelopment during gestation and infancy, and can reduce the risk of coronary heart disease (CVD) and cancer. Fish is becoming more and more popular in diet. However, fish also accumulate various contaminants, such as persistent organic pollutants (POPs) (e.g., PCBs and PBDEs). Many results indicated that fish is one of the main sources of PCBs and PBDEs for human exposure. The public is faced with conflicting sugestion on the risks and benefits of fish intake, resulting controversy and confusion over the role of fish consumption in a healthy diet. Taihu Lake is the second largest lake in China, and also is an important fishery base. But report on fatty acids, PCBs and PBDEs in fish from this lake was limited. In this study, 9 species fish were collected from Taihu Lake. The mixed muscle of nine species and the muscle tissue of three portions (i.e., dorsal, ventral, and tail muscle) from four species fish were selected to measure the concentration and the composition of fatty acids in order to assess the nutritive value. Simultaneously, the concentration of PCBs and PBDEs in fish were measured, and the benefit and risk of co-ingestion of nutrients (EPA+DHA) and pollutants (PCBs and PBDEs) were evaluated.All the nine species can be categorized as a very low fat fish. The concentrations of fatty acids were significantly positively correlated to the lipid contents in fish. Palmitic acid, oleic acid, and DHA were the predominant fatty acids in all species. The average total concentrations of PUFA and (EPA+DHA) varied from 1.6 to 3.7 mg/g and from 0.6 to 1.4 mg/g in the species, respectively. The concentrations of fatty acids in three portions (i.e., dorsal, ventral, and tail muscle) and three viscera tissues (heart, liver, and kidney) of four species were significantly positively correlated to their lipid contents. The concentrations of fatty acids were highest in liver and lowest in muscle among them. The intraspecies and interspecies difference of composition of fatty acids is maybe caused by the difference of physiological function of tissues.The concentrations of PCBs and PBDEs in mixed muscle of nine species fish ranged from 278.6 to 1 071.3 pg/g and 98.2 to 268.5 pg/g, respectively. These data were ranged in those of fish from the water bodies moderately contaminated in China. These data were generally much lower than those of freshwater fish from Norway and U.S.A. Compared with samples collected in 2009, the total concentrations of PCBs and PBDEs in the present study were slightly lower. The significant differences of the concentrations of PCBs and PBDEs in three portions (i.e., dorsal, ventral, and tail muscle) of four species were caused by the lipid contents and hydrophobic property of pollutants. The average concentrations of PCBs and PBDEs were lowest in dorsal muscle among three portions. The average concentrations of PCBs were highest in tail muscle, and the average concentrations of PBDEs were highest in ventral muscle.The nutritive value of mixed muscle of all nine species and three portions of four species was high based on the ratios of polyunsaturated fatty acids to saturated fatty acids and n-6 to n-3 polyunsaturated fatty acids (n-6/n-3 PUFA). When the benefits of (EPA+DHA) and the risk of PCBs were considered simultaneously, there is not the noncarcinogenic risk to achieve the recommended EFA intake of 250 mg/d for a healthy adult via consumption of the mixed muscles and different portion muscles. However, the consumption of the ventral muscles of topmouth culter maybe causes carinogenic risk.更多还原