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Please use this identifier to cite or link to this item: http://hdl.handle.net/2031/4325

Title: Assessment of organochlorines and environmental endocrine disruptors in Taihu Lake of China, and in vitro biochemical effects affected by metabolites of selected environmental pollutants
Other Titles: Tai Hu you ji lü he huan jing nei fen mi gan [i.e. gan] rao wu de diao cha ji xuan ding huan jing wu ran wu de dai xie chan wu zai sheng wu ti wai de sheng hua ying xiang
Tai Hu you ji lü he huan jing nei fen mi gan rao wu de diao cha ji xuan ding huan jing wu ran wu de dai xie chan wu zai sheng wu ti wai de sheng hua ying xiang
太湖有機氯和環境內分泌干擾物的調查及選定環境污染物的代謝產物在生物體外的生化影響
太湖有機氯和環境內分泌幹 [i.e. 干] 擾物的調查及選定環境污染物的代謝產物在生物體外的生化影響
Authors: Xu, Yan (許妍)
Department: Dept. of Biology and Chemistry
Degree: Master of Philosophy
Issue Date: 2006
Publisher: City University of Hong Kong
Subjects: Endocrine toxicology -- China -- Tai Lake
Organochlorine compounds -- Environmental aspects -- China -- Tai Lake
Pollutants -- China -- Tai Lake
Notes: CityU Call Number: QH545.O72 X8 2006
Includes bibliographical references (leaves 179-210)
Thesis (M.Phil.)--City University of Hong Kong, 2006
xvi, 210 leaves : ill. (some col.) ; 30 cm.
Type: Thesis
Abstract: Organochlorines have been proved to be persistent and carcinogenic pollutants for more than 30 years. Some records revealed that 10,000 tons PCBs were produced in China from 1965 to 1974 and 14 million hm2 of farmland considered as OC pesticides polluted in 1983. In the past 25 years, rapid development has been experiencing in China, especially the east and south China. Now, Yangtze River Delta is regarded as one of the fastest-growing industrial factory in the world, also, this region has become a significant pollution source. Taihu Lake is the third largest freshwater lake of China located in Yangtze River Delta and in the stress of heavy eutrophication and other pollutions. Under inefficient control of waste disposal, the quality of Taihu Lake water degraded 2–3 levels from 1970 to 1990s. Deterioration in water quality will not only threaten wildlife, but may cause deleterious effects on human health. The primary objective of this study is to provide baseline study on pollution levels with regard to persistent organic pollutants (PCBs, organochlorinated pesticides. Dioxin-like compounds), PAHs, in Meiliang Bay, Taihu Lake, China, with a view to evaluate the potential risks on assessment targets exposed to these environmental contaminants. Fresh water biotas and sediments were selected as the mainly assessment targets in the present study because their importance in the fresh water ecosystem, as well as, their susceptibility to the effects of pollutants. In present investigation, sediments were collected from Meiliang Bay, Taihu Lake China as the assessment target to evaluate the safety of fresh water ecosystem, while four species of fishes (White carp (Erythroculter ilisaeformis); Grass carp (Ctenopharyngodon idellus); Common carp (Cyprinus carpio); Crucian (Carassius auratus)) and fresh water snails (Bullacta exarata ) which are common in fish consumption were sampled for human health risk assessment. Preliminary ecological risk assessment of total PCBs, dioxin-like compounds, DDTs, CHLs, HCBs, HCHs, chlordane, and heptachlor epoxide were evaluated based on the levels of these contaminants detected in above samples. The finding showed that total PCBs had a good correlation with indicator PCBs in both sediments and biota samples. The hazard ratios (HRs) of PCBs, DDTs, HCBs, HCHs, chlordane, heptachlor epoxide and Dioxin-like PCBs were all below unity based on non-cancer endpoints, while the Cancer HRs were significant higher than 1.0 except Chlordane’s. Based on relative freshwater sediment quality guidelines, the organochlorine contaminations posed few reverse effects onto the local aquatic system. Dioxin-like compounds detected by H4IIE-luc cell bioassay indicated that intake of snail tissue may have a relative high health risk. And the PAHs contamination in sediments posed some risks to the local aquatic system. Some endocrine disrupting chemicals (EDCs) in the environment have been shown to exert their biological effects through interference with steroidogenesis. Even though PCBs are very persistent in environment, their metabolites were reported in many studies. In this study, the potential effects of four selected polychlorinated biphenyl (PCB) congeners (i.e., PCB101, PCB110, PCB126 and PCB149) as well as several of their environmentally-relevant methylsulfonyl- (MeSO2-) PCB metabolites (i.e., 3′-MeSO2-CB101, 4′-MeSO2-CB101, 4′-MeSO2-CB110, 3′-MeSO2-CB149 and 4′-MeSO2-CB149) on adrenocortical steroidogenesis were evaluated by use of an in vitro bioassay based on the human adrenocortical carcinoma H295R cell line. After the chemical treatments, changes in mRNA expression of 11 steroidogenic genes (CYP11A, CYP11B1, CYP11B2, CYP17, CYP19, CYP21, 3β-HSD1, 3β-HSD2, 17β-HSD1, StAR and HMGR) were quantified using molecular beacon-based real-time RT-PCR. Genes coding for enzymes involved in the later or final steps of steroid production (CYP11B1, CYP11B2, CYP19, 3β-HSD1, 3β-HSD2 and 17β-HSD1) were up-regulated to various extents by most PCBs. Increased expression of these steroidogenic genes might ultimately lead to a change in hormonal balance through excessive production of steroid hormones including aldosterone, cortisol and estradiol. In addition, co-treatment with 3′- and 4′-MeSO2-PCB149 resulted in a significant decrease in PCB149-induced 3β-HSD1 and 17β-HSD1 expression. This result indicates that some PCB congeners and their MeSO2-metabolites may affect steroidogenesis via different mechanisms. Overall, these findings suggest that PCBs and PCB metabolites can affect regulation of adrenocortical steroidogenesis. Irgarol-1051 (2-methythio-4-tert-butylamino-6-cyclopropylamino-s-triazine) is a popular marine antifouling coating in substitute of high toxic organotin-base antifoulants. Its very low water solubility allows the formulation of coatings with very low leaching rates and therefore long service life. It provides low biological activity to animals in general. Recently, a new Irgarol-1051 degradation product M2 (3-[4-tert-butylamino-6-methylthiol-s-triazin-2-ylamino]-propionaldehyde) was found. In order to explore the mechanism of action of M2, microarray technique of gene expression was used. The results showed limits of gene expressions were altered by M2 exposure to H4IIE cell. M2 may not be a stringently genotoxic chemical to mammals. Overall, the present study has provided the baseline information on a series of hot environmental contaminants and has evaluated the ecotoxicological risks and human health risks of study pollutants in Taihu Lake. In vitro bioassay and in vitro microarray techniques were applied in toxicity screening of selective pollutants.
Online Catalog Link: http://lib.cityu.edu.hk/record=b2147167
Appears in Collections:BCH - Master of Philosophy

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