Genotoxic evaluation of welders occupationally exposed to chromium and nickel using the Comet and micronucleus assays

Chromium (Cr) and nickel (Ni) are widely used industrial chemicals. Welders in India are inclined to possible occupational Cr and Ni exposure. The carcinogenic potential of metals is a major issue in defining human health risk from exposure. Hence, in the present investigation, 102 welders and an equal number of control subjects were monitored for DNA damage in blood leucocytes utilizing the Comet assay. The two groups had similar mean ages and smoking prevalences. A few subjects were randomly selected for estimation of Cr and Ni content in whole blood by inductively coupled plasma mass spectrometry. The Comet assay was carried out to quantify basal DNA damage. The mean comet tail length was used to measure DNA damage. Welders had higher Cr and Ni content when compared with controls (Cr, 151.65 versus 17.86 micro g/l; Ni 132.39 versus 16.91 micro g/l; P < 0.001). The results indicated that the welders had a larger mean comet tail length than that of the controls (mean +/- SD, 23.05 +/- 3.86 versus 8.94 +/- 3.16; P < 0.001). In addition, the micronucleus test on buccal epithelial cells was carried out in a few randomly selected subjects. Welders showed a significant increase in micronucleated cells compared with controls (1.30 versus 0.32; P < 0.001). Analysis of variance revealed that occupational exposure (P < 0.05) had a significant effect on DNA mean tail length, whereas smoking and age had no significant effect on DNA damage. The current study suggested that chronic occupational exposure to Cr and Ni during welding could lead to increased levels of DNA damage.