Influence of genetic susceptibility on the urinary excretion of 8-hydroxydeoxyguanosine of firefighters

Objectives-Oxidative DNA damage has been implicated in carcinogenesis. The DNA damage can be assessed from the urinary excretion of the DNA-repair pro duct 8-hydroxydeoxyguano sine (8-OH-dG). The factors were investigated that influenced the excretion of urinary 8-OH-dG in 78 firefighters. Methods-53 Out of 78 firefighters were exposed to fire within 5 days of the study and 25 were not. 8-OH-dG was measured by ELISA and the distribution of the genotypes of CYP1A1, CYP2E1, GSTM1, and GSTT1 was measured by polyme rase chain reaction. Results-The homozygous wild type frequencies of CYP1A1 MspI, CYP1AL ile-val , CYPZE1, GSTM1, and GSTT1 were 31.5%, 56.2%, 60.3%, 50.7%, and 53.4%, resp ectively. The geometric mean of urinary 8-OH-dG was 14.1 ng/mg creatinine i n more active firefighters and 12.3 ng/mg creatinine in non-exposed and les s active subjects. Significantly increased concentrations of urinary 8-OH-d G were found to be associated with cigarette smoking, and 14% of the variat ion of 8-OH-dG was explained by cigarettes smoked per day. The CYP1A1 MspI, CYP1A1 ile-val, GSTM1, and GSTT1 genetic polymorphisms were not found to b e significantly associated with the urinary excretion of 8-OH-dG. However, the subjects carrying the CYP2E1 mutant type excreted higher concentrations of 8-OH-dG and there was a marginally significant interaction of GSTT1 wit h firefighting activity. Multiple regression analysis confirmed that smokin g was the strongest predictor of excretion of 8-OH-dG. Age, body mass index , and firefighting activity were not significant predictive factors for uri nary 8-OH-dG. Conclusion-Smoking and CYP2E1 gene polymorphism may be important factors in carcinogenesis and the GSTT1 positive genotype may be a genetic susceptibi lity factor in firefighters who are exposed regularly to various chemical c arcinogens.