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Title: Persistent organic pollutants and trace elements in marine fish from Chinese coastal waters : levels, distribution and human health risk assessment
Other Titles: Zhongguo yan hai di qu hai yu ti nei chi jiu xing you ji wu ran wu he hen liang yuan su de wu ran shui ping yi ji dui ren lei jian kang de wei xian ping gu
Authors: Xia, Chonghuan ( 夏重歡)
Department: Department of Biology and Chemistry
Degree: Doctor of Philosophy
Issue Date: 2011
Publisher: City University of Hong Kong
Subjects: Organic compounds -- Environmental aspects -- China.
Organic compounds -- Bioaccumulation.
Persistent pollutants -- Environmental aspects -- China.
Persistent pollutants -- Bioaccumulation.
Marine fishes -- Effect of water pollution on -- China.
Fish as food -- Health aspects -- China.
Notes: CityU Call Number: TD196.O73 X53 2011
xix, 222 leaves : ill. 30 cm.
Thesis (Ph.D.)--City University of Hong Kong, 2011.
Includes bibliographical references (leaves 192-222)
Type: thesis
Abstract: 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, causing the pollution of the coastal marine ecosystem to become worse. In recent years, global public concern over the accumulation of pollutants in marine organisms has increased because it not only threatens life, but may also lead to adverse health effects to the population, considering that 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. In addition to their commercial value and as a food source, fish have been established as good bioindicators of environmental pollution because their tissues can accumulate high concentrations of contaminants 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 suite of organochlorine compounds, brominated flame retardants and metals in marine fish all over the world, and suggested that they may pose human health risks. In this work, two species of marine fish, namely large yellow croaker (Pseudosciaena crocea) and sliver pomfret (Pampus argenteus) collected from nine coastal cities (e.g. Dalian, Tianjin, Qingdao, Shanghai, Zhoushan, Wenzhou, Fuzhou, Quanzhou and Xiamen) 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 (DDT) and its metabolites, hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and chlordane compounds were the most 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. The composition of DDTs revealed that the main source of DDTs was possibly due to the heavy historical agricultural and public health usage. The high proportion of γ-HCH in the Chinese coastal environment suggested the continuous use of lindane. Cancer and noncancer risk assessments suggested a possible lifetime cancer risk, especially from DDTs. The calculated daily and meal consumption limits were 9 g/day and 1 meal/month for croakers, and 67 g/day and 9 meals/month for pomfrets, respectively. Total PCB concentrations were at the low end of the worldwide figures. The levels of total dioxin-like PCBs were found to be strongly positively correlated to total PCB concentrations, indicating total PCB levels can explain 80% of the 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 nine cities was observed. Risk estimation indicated that PCBs may pose a health risk to heavy seafood consumers. PBDEs and HBCDs are widely used as additive brominated flame retardants (BFRs) in electronic equipment, plastics, textiles, building materials and other application to avoid catching fire. Although they were detected in all of the fish samples, their concentrations were comparatively lower than other regions of the world, especially North America and Europe where Penta-BDE and HBCDs were extensively used, respectively. BDE47 and BDE154 were the predominant congeners in both species, accounting for more than 60% of the total PBDE concentrations, which differed from the commonly detected patterns in fish reported in previous studies. Among the three individual HBCD isomers, the α-isomer showed remarkable predominance, reflecting its higher bioaccumulative potential. Estimated daily intakes of PBDEs and HBCDs via fish consumption for the Chinese population were much lower than the effect levels, suggesting that large yellow croakers and pomfrets were safe to eat with respect to these chemicals. Methylmercury and trace elements (total mercury, selenium, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, strontium and zinc) were also investigated. The levels of mercury, iron and nickel were at the low end of the global range, while the concentrations of the other elements were found to be globally within the same range of concentrations. Except for cadmium which was found to be higher than the criterion recommended by the European Commission Regulation in 16% of the samples, the concentrations of the other metals were well below the international standards. From a 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 the current knowledge concerning various contaminants levels in marine fish from China and provided a preliminary health risk assessment 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 is advised. Moreover, in addition to advisory consumption recommendations, actions need to be implemented in order to reduce the environmental levels of DDTs.
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