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Title: Health risk assessment of organohalogen compounds associated with seafood consumption in coastal cities in China
Other Titles: Zai Zhongguo yan hai cheng shi you hai chan pin she ru de you ji lu lei hua he wu de jian kang feng xian ping gu
Authors: Jiang, Qinting (蔣沁婷)
Department: Dept. of Biology and Chemistry
Degree: Doctor of Philosophy
Issue Date: 2006
Publisher: City University of Hong Kong
Subjects: Organohalogen compounds -- Environmental aspects -- China
Persistent pollutants -- Environmental aspects -- China
Seafood -- Contamination -- China
Notes: CityU Call Number: TD196.H35 J53 2006
Includes bibliographical references (leaves 150-184)
Thesis (Ph.D.)--City University of Hong Kong, 2006
xvi, 188 leaves : ill. ; 30 cm.
Type: Thesis
Abstract: Food consumption is an important pathway of human exposure to persistent organic pollutants (POPs). Market basket surveys for POPs have been conducted worldwide; however, there are very few surveys that cover all the major POPs for a comprehensive assessment of overall exposure. The primary objective of this study is to monitor a broad spectrum of POPs present in seafood samples collected from two coastal cities in China, with a view to evaluate the potential cancer and noncancer risks on humans exposed to these contaminants due to food consumption. Seafood is a major dietary component for coastal populations in China. According to a questionnaire-based dietary survey conducted in a Chinese coastal city, Zhoushan, in 2001, daily consumption of fishes, crabs, cephalopods, shrimps and bivalves were 105 g, 17.3 g, 3.37 g, 54.1 g, and 76.5 g wet wt., respectively, for an adult. In the first instance, fish samples were selected as the study targets because fish constitute an important dietary component in Chinese coastal cities. The concentrations of organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) ranged from 0.67 to 13 and 0.24 to 1.4 ng/g wet wt., respectively. The hazard ratios (HRs), based on non-cancer endpoints, were all less than unity, while the cancer-based HRs were greater than unity for certain contaminants based on the 95th centile concentration in fish tissue. Results of this preliminary study indicated that fish consumption may pose a lifetime cancer risk of greater than one in one million, and thus further studies were conducted to cover a wider range of contaminants in a more extensive selection of seafood samples. In the second study, comprehensive market basket surveys were undertaken at two coastal cities, Guangzhou and Zhoushan. In this study, polychlorinated compounds, including PCBs, non- and mono-ortho-PCBs, polychlorinated naphthalenes (PCNs) and polychlorinated dibenzo-p-dioxins and furans (PCDDs/DFs); polybrominated compounds, including polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and polybrominated dibenzo-p-dioxins and furans (PBDDs/DFs); perfluorinated compounds, including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were analyzed for five categories of seafood, including fish, shrimp, cephalopods, crab and bivalves. The concentrations of total PCBs, non- and mono-ortho-PCBs, PBDEs and PFOS in seafood samples were higher in Guangzhou than those in Zhoushan, while the levels of PCNs, PCDDs/DFs, PBBs, PBDDs/DFs and PFOA were lower in Guangzhou than those in Zhoushan, or comparable between the two cities. The total daily intakes of PCDDs/DFs, coPCBs and PCNs were 1.05 and 0.86 WHO-TEQ pg/kg body weight in Guangzhou and Zhoushan, respectively. The total daily intakes of PBDEs, PBBs, PBDDs and PBDFs were 946, 249, 6.39 and 6.54 pg/kg body weight in Guangzhou; 489, 299, 4.99 and 7.65 pg/kg body weight in Zhoushan. Daily intakes of PFOS and PFOA were 10.97 and 1.06 pg/kg body weight in Guangzhou, and 4.19 and 0.64 pg/kg body weight in Zhoushan, respectively. Hazard ratios (HRs) for PCBs, PCNs, PCDDs/DFs, PBDEs, PBBs, PFOS and PFOA were all lower than unity in the present study, indicating that these contaminants would be unlikely cause any adverse effects. Notwithstanding, HRs for PBDDs and PBDFs were both greater than unity suggesting that there may be some concern for potential noncancer effects. The overall noncancer risks of human exposure to all the contaminants analyzed in the present study were, respectively, 9.38 and 8.42 in Guangzhou and Zhoushan (at low bound level), and 10.62 and 10.14 (at high bound level). All HRs are greater than unity. These findings suggest that a comprehensive risk assessment of the type described in this study may allow an investigation of the cumulative potential health risks, which will be more informative than individual assessments involving a single class of compounds only. In addition, the lifetime excess cancer risks resulting from the daily intake of contaminated seafood in Guangzhou and Zhoushan were found to be 10-3. This range of cancer risks for the general population is about 10 times greater than those reported from other countries. It is noted that the results shown here only represent a preliminary assessment of potential health risks; further study, particularly with an improved knowledge of toxicity equivalency factors (TEFs) and Minimal Risk Levels (MRLs) or Reference Doses (RfDs) for PBDDs/DFs, is required to verify these results.
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