| Summary: | 碩士 === 中國醫藥學院 === 環境醫學研究所 === 88 === Tobacco smoke is considered as the most important factor in environmental carcinogenesis and contains numerous carcinogens. Among them, ethylene oxide is classified as a known human carcinogen, and there is about 5μg per cigarette. It has been of interest to study the potential cancer risk caused by ethylene oxide exposures during smoking.
The objective of the study was to establish the modified Edman degradation methods to analyze ethylene oxide-induced hemoglobin adducts (N-hydroxyethylvaline, HEV), and then to investigate the factors that affect the formation of HEV in smokers and non-smokers. Results from this study would be used to estimate the accumulated internal doses and external exposures of ethylene oxide and finally to assess cancer risk. Ten ml of blood samples was collected from 162 volunteers which background informations were collected by questionnaires. Red blood cells were immediately harvested from each fresh blood sample and stored at -80oC until used for purification of hemoglobin. Approximate 100 mg of globin was dissolved in formamide and derivatized with pentafluorophenyl isothiocyanate. After cleanup, samples were analyzed using gas chromatograph / negative chemical ionization-mass spectrometer (GC/NCI-MS). The amounts of HEV are 58.3±45.6 pmol/g Hb in non-smokers and 205.9±151.4 pmol/g Hb in smokers which are significantly different (p<0.0001). Our results show that the amounts of HEV are linearly correlated with number of cigarettes smoked per day (r = 0.53), years of smoking (r = 0.28), and bags of cigarettes smoked per day (r = 0.44). Cumulative external exposures are estimated to be 259.2 and 915.1 ppm×h of ethylene oxide in non-smokers and smokers, respectively. The corresponding cancer risk are 4.15×10-5 and 1.46×10-4. This study validates that HEV is a sensitive and specific biomarker to assess ethylene oxide exposures from tobacco smoke. These results also confirm that smokers will have higher cancer risk than nonsmokers due to the exposures to ethylene oxide.
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