Persistent Organic Pollutants And Trace Elements In Marine Fish From Chinese Coastal Waters: Levels, Distribution And Human Health Risk Assessment

Marine pollution has posed a grave challenge to China over the past years. Due to China's double-figure annual economic growth and the failure of factories, power plants., sewage systems and other sources to obey environmental regulations, pollution in China has risen sharply. Large amounts of contaminants are filtering from the land into the sea, which caused the coastal marine ecosystem to get worse. In recent years, global public concern over accumulation of pollutants in marine organisms has increased because it would not only threaten life themselves, but may also lead to adverse health effects to population considering seafood consumption is an important route of human exposure to environmental contaminants.In response to this concern, the present study aimed to determine the current levels of various organic and inorganic pollutants in different species of marine fish. At the same time, the potential health risks derived from the exposure to these contaminants for the general population were also assessed.As well as the commercial values and human consumption, fish have been established as good bio-indicators of environmental pollution because their tissues often contain high contaminant concentrations due to their relatively high position in the food chain and consequent elevated exposure levels in the aquatic environment. Many investigations have reported high concentrations of environmental contaminants including a suit of organochlorine compounds, brominated flame retardants (e.g. polybrominated diphenyl ethers and hexabromocyclododecanes) and metals in marine fish all over the world, and suggested that they may pose a health risk to human body.In this work, two species of marine fish, namely large yellow croaker (Pseudosciaena crocea) and sliver pomfret (Pampus argenteus) collected from nine coastal cities of eastern China in 2008 were analyzed for a series of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs) and a number of trace elements. Additional fish samples namely small yellow croaker(Pseudosciaena polyactis) were also determined for the trace elements.Among the OCPs, dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and chlordane compounds were the predominant and ubiquitous residues. In particular, the concentrations of DDTs were one order of magnitude greater than those from other countries, indicating that the coastal regions of China probably are among the most DDT-polluted areas in the world, although there was a decreasing trend of DDTs by comparing the results of previous studies in the past. The composition of DDTs revealed that the main source of DDTs was due to the heavy historical agricultural and public health usage, and a small proportion of fresh input from the use of dicofol and DDT-containing antifouling paint was possible. While, the high proportion of y-HCH in Chinese coastal environment suggested the continuous use of lindane. The result of principal component analysis (PCA) showed the coast of Dalian was the most heavily polluted area by OCP compounds among the locations investigated in this study. Cancer and noncancer risk assessments suggested a lifetime cancer risk is a possibility, especially from DDTs, while through intake of these pollutants by only fish consumption did probably not cause noncarcinogenic effects in human body. The calculated daily and meal consumption limits were 9g/day and 1 meal/month for croakers, and 67g/day and 9 meals/month for pomfrets, respectively.Thirty-six congener-specific PCBs were determined, in which,11 congeners are dioxin-like PCBs. The total PCB concentrations of the present study were at the low end of the worldwide figures, which may related to the fact of less usage and shorter consumption history of PCBs in China. For individual PCB congener, PCB 18,29, 52,66,101,104,138,153,180 and 194 were the major constituents. Regression analysis showed a strong positive correlation between total dioxin-like PCBs and total PCB concentrations, and that total PCB levels explain 80% variability in dioxin-like PCBs concentrations. Large yellow croakers have a greater tendency to bioaccumulate PCBs than pomfrets, which may be attributed to their different feeding and living habits. No significant difference in total PCB levels among the cities was observed, and the principal component analysis (PCA) regarding PCB profiles indicates that PCB pollutions came from similar sources in the sampling areas and there may be other different PCB sources in Dalian and Wenzhou. The calculated carcinogenic risks (CRs) were greater than 10-6, suggesting that daily exposure to dioxin-like PCBs via fish consumption had a lifetime cancer risk of greater than one in one million. In contrast, the hazard quotients (HQs) of noncancer risks were all less than unity.Although PBDEs were detected in all of the samples, the concentrations were relatively lower than other regions of the world, especially North America where Penta-BDE was extensively used. Geographically, the highest concentration of PBDEs was found in Xiamen, and the PBDE levels in yellow croakers were significantly higher than those in pomfrets in most of the selected cities, a pattern which may be related to the different feeding habits of the two species. The congener profiles of PBDEs were found to be different from the commonly detected pattern in fishes from other regions of the world (i.e., BDE47> BDE99, BDE100>BDE153, BDE154). BDE47 and BDE154 were the predominant congeners in both species, accounting for more than 60% of the total PBDE concentrations. The reasons for the relatively high proportion of BDE154 may be due to the debromination of higher brominated congeners such as BDE183 and BDE209 by these two species. Estimated daily intakes of PBDEs via fish consumption for the Chinese population were 10,000 times lower than the effect level, indicating the potential health risk caused by PBDEs via fish consumption could be neglected.HBCDs were detectable in all samples analyzed, indicating ubiquitous contamination of these compounds in the Chinese coastal environment. The total HBCD concentrations were relatively lower than other regions of the world, especially Europe, where HBCDs are intensively used. Among the three individual HBCD isomers (α-,β-andγ-HBCD) in all fish samples, the a-isomer showed a remarkable predominance, indicating its higher bioaccumulative potential. Geographically, the highest HBCD level present in fish was found in Dalian in northern China, and the lowest occurred in Wenzhou. Estimated daily intakes of HBCDs via fish consumption for the Chinese population were were much lower than the effect levels, suggesting that large yellow croakers and pomfrets were safe to eat according to HBCDs.Methylmercury and trace elements (total mercury, selenium, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, strontium and zinc) were also examined. The levels of mercury, iron and nickel were at the low end of the global range, while the results of other elements are globally within the same range of concentrations. Except for cadmium levels in 16% of the samples higher than criterion recommended by the European Commission Regulation, the concentrations of other metals were well below the international standards. From the human health point of view, the estimated daily intake of these metals did not exceed the reference dose established by US EPA, hence the hazard quotients (HQs) were all less than one, indicating a situation of no risk for the consumer.Overall, this study expanded current knowledge of various contaminants levels in marine fish from China and provided a preliminary health risk of these pollutants to human consumers via dietary fish consumption in Chinese coastal cities. Although the risks by trace metals and BFRs were not notable, continuous monitoring of these and other pollutants in the coastal marine ecosystem are remarkably advisable. Moreover, some actions need to be taken to reduce the environmental levels of DDTs besides giving advisory consumption recommendations.