Fatty Acids, Polychlorinated Biphenyls And Polybrominated Diphenyl Ethers In Fish From Taihu Lake: Their Levels, Distribution And Benefit-risk Assessment

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.