Changes in the estimated median ratios (95% CIs) of firefighting activity for urinary 8-OH-dG concentrations according to GSTT1 polymorphism
| Firefighting activity | GSTT1 positive | GSTT1 null |
| Unexposed | 1.000 | 1.000 |
| Less active duty | 1.008 (0.933 to 1.089) | 0.976 (0.848 to 1.123) |
| More active duty | 1.054 (0.961 to 1.158) | 0.916 (0.732 to 1.146) |