Welding consisted of a hazardous process involving high temperatures and generating toxic fumes in the process. Therefore, welders were exposed to many occupational hazards. In the study, oxidative stress and DNA damage of 35 welders, in parallel with 25 control subjects working in Dhaka city was investigated. Oxidative stress level was measured by using five biochemical parameters such as thiobarbituric acid reactive substances (TBARS), phospholipid hydroperoxide (PLHP), total antioxidant status (TAS), superoxide dismutase (SOD) activity and vitamin C level in serum as well as DNA damage by alkaline comet assay. The welders were divided into two group; group I (≤10 years) and group II ( >10 years) on the basis of the duration of welding (years). Serum TBARS level (8.0 ± 0.4 vs. 4.0 ± 0.2 nmol MDA equivalent ml-1) and PLHP level (9.0 ± 0.9 vs. 5.0 ± 0.2 nmol ml-1) significantly (p<0.001) increased in welders compared to control subjects. Levels of TAS (0.3 ± 0.02 vs. 0.7 ± 0.03 mmol l-1), SOD activity (74 ± 2.0 vs. 94 ± 0.6 inhibition rate %) and vitamin C (0.4 ± 0.04 vs. 0.8 ± 0.05 mg dl-1) significantly (p<0.001) decreased in welders compared to control subjects. Elevated levels of TBARS, PLHP with decreased levels of TAS, SOD activity and vitamin C indicated that the production of reactive oxygen species (ROS) was higher in welders than that of control subjects. These results suggested that the exposure of welder to welding generated oxidative stress. TBARS level of welders of Group II was significantly higher (p<0.01) than that of welders of Group I (8.0 ± 0.3 vs. 10 ± 0.8 nmol MDA equivalent ml-1). The mean TBARS, mean PLHP, mean SOD Activity, mean vitamin C values significantly differs among smoker control group (SC), non-smoker control group (NSC), smoker welder group (SW) and non-smoker welder group (NSW). This results also supported by the result of comet assay, which indicated that higher DNA damage occurs in welders than that of control subjects. It was found that 15.6% and 6.5% cell’s DNA were moderately and severely damaged in control subjects, whereas in the welders cell’s DNA were 28.2% moderately and 21.0% severely damaged, respectively. When duration of welding (years) was considered, a modest increased in oxidative stress and DNA damage was associated with the higher exposure to welding than that of lower exposure. The evaluated effect of smoking on oxidative stress and DNA damage among all subjects showed that smokers had more DNA damage than non-smokers. In this study correlation was found between oxidative stress and DNA damage of the welders with the duration of exposure of welding fumes and smoking habits of welders.
Keywords: Welders, oxidative stress, DNA damage, comet assay