Dioxin And PCBs In Zhejiang: Pollution Status And Their Risk Assessment To Human Health

Polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs) are two of the twelve persistent organic pollutants (POPs) recognized by Stockholm Convention. They are highly persistent compounds and have been detected in air, water, soil, sediment, animals and foods. In the past 2 decades, a great concern has been raised worldwidely on these pollutants due to their potential threats to human health. However, the determination of PCDD/Fs and PCBs is a complicated and expensive procedure, on the other hand, data that reflecting their background is not enough. Zhejiang is a fast-developing province in China; at the same time, its environment has been seriously influenced by side products of industry activity. The pollutants may orgin from municipal waste burning, waste water from paper making mills, and pesticide manufactory, etc. More badly, many of these contaminants contain toxical compounds like dioxin and PCBs with a certain extent. So it's absolutely necessary to monitor these kinds of pollutants and make corresponding evaluation on their risks to both environment and human health.The methods for the determination of PCDD/Fs and PCBs with stable isotope dilution technique and gas chromatography-mass spectrometry were established based on US EPA method 1613B and 1668A respectively. The methods were applied for the determination of dioxins and PCBs in fish (from Qiantang River), soil-sludge-fish (from five districts of Zhejiang) and human samples as well (breast milk, serum and human adipose tissue from Zhejiang general population) with the aim of monitoring PCDD/Fs-PCBs level and their corresponding congener profile in both environmental samples and bio-bodies. Furthermore, risk assessment was also carried out. The work is consisted of five parts:(1) A review of dioxin and PCBs, including their chemical and physical property, contamination source, toxicity and risk assessment, as well as the progress of analytical method. (2) In this part, the method for the determination of PCDD/Fs and PCBs in soil and bio-samples (fish and breast milk) was established based on US EPA method 1613B, 1668A and the method of Canada EPS 1/RM/31 for environmental samples. The extraction, purification, separation procedure and instrumental detection parameters were optimized. The method was validated using Certificated Reference Materials (CRM:WMF-01, Fortified fish samples). The recovery of 13C labeled PCDD/Fs in WMF-01 was in the range of 59.6%-122.1%, RSD was in the range of 1.60%-12.7% (n=6), The recovery of 13C labeled PCBs in WMF-01 was in the range of 55.6%-101.2%, RSD was in the range of 4.63%-11.6% (n=6). These results were within the range recommended by EPA 1613B and 1668A. We also participated in 2006 international comparsion on dioxin in food and our results were acceptable. The accuracy of the established method may provide an analyze basis for our later studies(3) In this part, the concentrations and congener patterns of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) were determined in the muscles of nineteen crucian carp and eleven White Amur bream collected from Qiantangjiang River. The means of total PCDD/Fs were 4.29 pg g"1 wet weight (ww) in crucial carp and 5.39 pg g-1 ww in White Amur bream. The means of total PCBs (sum of 23 congeners) were 4.70 ng g-1 ww in crucial carp and 2.36 ng g-1 ww in White Amur bream. The means of total TEQ were 1.24 pg g-1 ww in crucial carp and 1.11 pg g-1 ww in White Amur bream. The predominating PCDD/F congeners were 2,3,7,8-TCDF,1,2,3,7,8-PeCDF and 2,3,4,7,8-PeCDF. The level of lower chlorinated CB31/28 was high in two fish species. The levels of PCDD/Fs, PCBs and total TEQ in fish caught from Qiantangjiang River were similar to those in similar fish species caught from some rivers and lakes in China. The lower levels of total TEQ levels measured in fish muscles allow local residents consuming fish caught from Qiantangjiang River at an acceptable safety level.(4) In this chapter, we determined the concentrations and toxicity equivalences (TEQs) of PCDD/Fs and PCBs in fishes, soils and sediments from five districts to investigate the levels of these two pollutants in Zhejiang Province, China. The means of total PCDD/Fs in soils, sediments and fishes were 1993.5 pg g-1 dry weight (dw),2550.7 pg g-1dw and 5.25 pg g-1 wet weight (ww) respectively. The averages of total PCBs in soils, sediments and fishes were 97000 pg g-1 dw,306332 pg g-1dw and 12678 pg g-1 ww respectively. The means of total TEQs in soils, sediments and fishes were 27.6 pg g-1 dw,468.6 pg g-1dw and 8.2 pg g-1 ww respectively. Present research showed that Luqiao, one of selected five districts was seriously contaminated by PCDD/Fs and PCBs which presented the similar level to Guangdong (China) and Veitnam heavily polluted by chemical defoliants and electronic waste. High PCB level was also found in soil/sludge collected from Jinhua and Yongjia, but their possible sources were still unclear. We estimated daily exposure to these pollutants through dietary intake, the data showed the intake of Crucian Carp had a health risk. Accordingly,we suggest loacal residents eat little or no Crucian Carp from Luqiao.(5) In this part, concentration and congener profile (finger print) of dioxin and PCBs in human samples (blood, adipose tissue, breast milk) from genernal population of Zhejiang province were investigated. The data showed that the concentration of PCDD/Fs in human adipose tissue, breast milk and children blood were 108 pg/g lipid, 55.0±39.5 pg/g lipid and 208±172 pg/g lipid respectively, concentrations of 12 dioxin like PCB were 32.8 ng/g lipid,8.0±0.4 ng/g lipid and 9.8±5.3 ng/g lipid respectively, concentrations of indicator PCBs were 154 ng/g lipid,15.8±9.3 ng/g lipid and 28.3±11.9 ng/g lipid respectively. The corresponding TEQ of PCDD/Fs and PCBs in adipose tissue, breast milk and children blood were 9.22 pg/g lipid,3.09±2.36 pg/g lipid,11.7±7.9 pg/g lipid and 16.2 pg/g lipid,3.56 pg/g lipid,11.9±6.6 pg/g lipid respectively. The finger prints of PCDD/Fs and PCBs from major food category (egg, fish for example) were very similar to each other. Food intake represents the main route of human exposure to PCDD/Fs and PCBs. People in East Asia have similar diets, and their food intake of animal origin is generally lower than that of Europeans. This may partly explain why WHO PCDD/F TEQs for East Asia are generally lower than those for Europe. Prevention and control regulations for PCDD/Fs and PCBs are suggested in this paper according to contaminants sources and their transferring routes in the environment.