Oxidative stress estimated by urinary 8-OHdG for workers exposed to low level benzene

摘要

Benzene is identified as a carcinogen and can be released into our ambient environment by vehicles powered by petroleum fuel. Occupational exposure to benzene owing to traffic emission has been reported including street vendors, traffic policemen, gas station workers and outdoor workers etc. These people, compared with those working in industries, were exposed to low level of benzene. The health risk due to low level exposure to benzene may thus need to be investigated. Oxidative stress is a potential indicator of DNA damage and therefore might provide information of cancer incidence. This study invited ten workers who were identified to be exposed to low levels benzene. They provided their start-of-shift and end-of-shift urine samples for consecutive five days. The levels of urinary 8-OHdG and t,t MA were analyzed to estimate the potential oxidative stress and benzene exposure. The overall average of urinary 8-OHdG was 9.8 ± 5.8 mg/g creatinine. The average of 8-OHdG in the start-of-shift and end-of-shift were 8.5 ± 9.5 and 11.1 ± 11.5 mg/g creatinine, respectively. The paired-t test indicated no difference between the 8-OHdG level in urines from start-of-shift and end-of-shift. In addition, there was no difference observed among various weekdays' samples. The phenomena may be due to 8-OHdG not being a specific indicator of any hazardous stress. However, urinary 8-OHdG and t,t MA levels were significantly positively correlated. The regression model also showed consistent results (p ＜ 0.01). Our results show that the low level benzene exposure would result in an increase of oxidative stress; however, the urinary 8-OHdG may be influenced by some other hazardous stress as well. Thus further assessment of multiple exposures may be warranted for the workers studied here.