| Summary: | 碩士 === 國立陽明大學 === 環境與職業衛生研究所 === 100 === Dioxin is an environmental pollutant that had various toxic effects and associated adverse health implications in human and environment. Dioxin released to the atmosphere was mainly from anthropogenic activities, including waste incineration, high-temperature sources and metallurgical processes.
The purposes of our study were fourfold: (1) to collect emission sources and environment media monitoring data, (2) to use geographic information system (GIS) as a tool to present the simulated dioxin air concentration in study area by Industrial Source Complex Short Term model (ISC ST3), (3) to estimate the residents' dioxin daily exposure dose in their lifetime and cancer risk, and (4) to investigate the association between cancer mortality and dioxin concentration.
Simulation model show that the dioxin concentrations in central and north Taiwan were higher than southern Taiwan. As for township, the top three simulated airborne dioxin concentrations were Houli township, Taichung county (0.110 pg-I-TEQ/m3) and Bade City, Taoyuan County (0.087 pg-I-TEQ/m3) and Shengang township, Taichung county (0.057 pg-I-TEQ/m3).
The results showed that total lifetime average daily dose for Taiwanese ranged from 2.16×10^(-4)-5.27×10^(-2) pg I-TEQ/kg/d, the predominant pathway (>98%) of dioxin exposure is via food intake. The maximum total cancer risk for children was 5.27×10^(-6) which appeared in Shengang Township, Changhua County.
This study also showed that the cancer mortality trends of study area were not apparently increasing from 2001 to 2007 year, but we found the cancer mortality of higher simulated airborne dioxin concentrations regions was higher than that of lower ones in central and southern Taiwan. However, the correlation between cancer mortality and dioxin concentration was low.
Iron and steel industries were major dioxin emission sources. Elevated airborne dioxin concentrations in central and north Taiwan indicated potential contribution surrounding iron and steel plants. Some strategies, such as environmental media monitoring and the risk assessment, should be taken to reduce health risk of dioxin exposure.
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