砷暴露勞工尿液中砷代謝物、氧化壓力標記和基因多型性之分析研究

砷為環境中的毒性物質，也是人類可能的致癌因子之一。當人體受到無機砷暴露之後，經由體內的解毒機制，砷的代謝物將會經由尿液排出。為了解個體間尿中砷代謝物的差異與基因多型性的關聯性，本研究針對砷暴露勞工進行尿中砷代謝物與GSTM1、T1、O1和MTHFR基因多型性之分析，並探討尿中砷代謝物與基因多型性的相關性。此外，為了解砷暴露對於人體氧化壓力的影響，本研究也針對砷暴露勞工進行尿中砷代謝物與血液中氧化壓力標記之分析，並探討其間的相關性。本研究收集半導體製造業員工之尿液與血液樣本，利用HPLC-HGAAS進行四種尿中砷代謝物(包括三價砷 (AsIII)、五價砷 (AsV)、單甲基砷 (MMAV)與雙甲基砷 (DMAV))的偵測；血清中氧化壓力標記-MDA則以HPLC分析之。基因多型性的分析則以週邊靜脈血液經萃取DNA後，利用PCR-RFLP進行分析。主要研究結果顯示，尿中砷代謝物種之分佈情形在男女性勞工之間沒有顯著的差異(P>0.05)。然而，本研究發現GST M1 null genotypes尿中無機砷與有機砷之比值則明顯大於non-null genotypes (P<0.05)；GST T1 null genotypes，其尿中總砷、有機砷及雙甲基砷的含量均較non-null genotypes明顯為低(P<0.05)。另外，GST O1 E155del 異基因型合子突變型的族群之尿中MMA濃度則顯著高於正常基因之族群(P<0.05)。針對本研究目前所分析之尿液中氧化壓力標記含量與尿液中砷代謝物種之間並未發現顯著的相關性(P>0.05)。

關鍵字

性氧化壓力標記；基因多型；尿中砷代謝物

並列摘要

Arsenic is a notorious environmental toxicant known as a carcinogen in human beings. Peoples exposed to inorganic arsenic compounds will excrete urinary arsenic metabolites via the detoxification process in the body. To understand the interindividual variability in urinary arsenic metabolites and the possible association with gene polymorphisms, this study was devoted to analyze the urinary arsenic metabolites and GSTM1, T1, O1, MTHFR gene polymorphisms in arsenic-exposed employees. In addition, to explore the possible effects of arsenic exposure on oxidative stress, this study also measured the serum malondialdehyde (MDA, a biomarker of oxidative stress) and investigated their relationship between arsenic metabolites and MDA in arsenic-exposed employees. Urine and peripheral blood samples were collected from semiconductor factory employees. The urine samples were analyzed with HPLC-HGAAS for arsenic metabolites, including arsenite (AsIII), arsenate (AsV), monomethyarsonic acid (MMAV), and dimethylarsinic acid (DMAV). Serum malondialdehyde was determined using HPLC method. DNA obtained from peripheral blood was genotyped using methods of polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP). The results indicate that no significant difference in arsenic methylation capability was observed for male and female. However, subjects with the null genotype of GST M1 have an increased inorganic arsenic/organic arsenic ratio compared to those with non-null genotype. A marked decrease in the concentrations of total arsenic and organic arsenic metabolites was found in the null genotype of GST T1 compared to those with non- null genotype. Furthermore, those with heterozygous genotype of GST O1 E155del have a decrease percentage of MMA in urine. No significant relationship between urinary arsenic metabolites and serum biomarker of oxidative stress in employees was observed in the present study.