Nitrogen oxides (NOx) and polycyclic aromatic hydrocarbons are common air pollutants generated from automobile exhaust and cigarette smoke. This study was to investigate urinary 8-hydroxydeoxyguanosine (8-OHdG) as an effective biomarker on DNA damage from traffic exhaust and/or smoking in exposed and non-exposed individuals. With subject consents, the levels of plasma NOx, urinary 1-hydroxypyrene (1-OHP) and 8-OHdG were determined for 95 male taxi drivers and 75 male community residents as the reference group. After adjusting for associate variables, there was a significant correlation between the levels of urinary 8-OHdG and 1-OHP but not NOx. The average level of urinary 8-OHdG was significantly higher in drivers than in community men (13.4 ± 4.7 vs. 11.5 ± 4.7 μg/g creatinine in mean ± standard deviation). Compared with non-smoking community men, the multivariate logistic regression showed that the odds ratios (OR) of having elevated levels of urinary 8-OHdG (greater than the overall median value, 12.1 μg/g creatinine) were 6.6 (95% confidence interval (CI)=2.1–20.8) for smoking community men, 5.0 (95% CI=1.7–14.7) for non-smoking taxi drivers and 4.6 (95% CI=1.4–15.0) for smoking taxi drivers. Higher risk was also observed for areca quid chewers compared with non-chewers (OR=1.6; 95% CI=1.1–3.6). In conclusion, taxi driving and smoking may contribute independently to elevated DNA damage using urinary 8-OHdG levels as a sensitive biomarker. This effect is most potent on heavy smokers.
