Oxidative damage can be induced by many environmental stressors. 
8-Hydroxydeoxyguanosine (8-OHdG) has been used as a biomarker of oxidative DNA 
damage in both in vitro and in vivo studies. In the present study, Wistar rats 
were exposed to radon gas at a concentration of 100,000Bq/m(3) for 12 h/d for 
30, 60, and 120 d, equivalent to cumulative doses of 60, 120, and 240 working 
level months (WLM), respectively. Changes in levels of 8-OHdG, reactive oxygen 
species (ROS), and total antioxidant (T-AOC), as well as expressions of some DNA 
repair enzymes such as 8-oxoguanine DNA glycosylase (OGG1) and MutT homolog 1 
(oxidized purine nucleoside triphosphatase, MTH1), were determined in rat urine, 
peripheral blood lymphocytes, and lung after exposure to radon. The results 
revealed an increase in 8-OHdG and ROS levels, a decrease in T-AOC levels, and 
reduced OGG1 and MTH1 expression levels. The elevated amount of 8-OHdG in urine 
or lymphocytes was positively correlated with the cumulative exposure dose, 
whereas OGG1 and MHT1 expression levels in lung were inversely correlated with 
cumulative exposure dose. These findings indicate that oxidative damage induced 
by radon may be involved in radon-induced carcinogenesis.