Gender difference in smoking effect on chromosome sensitivity to gamma radiation in a healthy population

In the general population, there is variation in radiosensitivity associate d with cancer risk. However, data on the role of epigenetic factors in the variation of radiosensitivity are scarce. Thus we investigated the effects of smoking and age on the radiosensitivity of human lymphocytes by measurin g the frequency of chromosome aberrations after in vitro exposure to gamma rays in peripheral lymphocytes from 441 healthy subjects (18-95 years old). We analyzed the frequency of both spontaneous (baseline) and in vitro gamm a-ray-induced (1.5 Gy) chromatid breaks in 50 well-spread metaphases per su bject. The overall mean frequencies of spontaneous and induced breaks were 0.02 and 0.45 per cell, respectively. The mean frequency of induced breaks was significantly higher in men than in women (P = 0.03) but did not differ by age or ethnicity. Donors who had ever smoked showed a small but signifi cantly increased frequency of induced breaks (mean = 0.47) compared to nons mokers (mean = 0.41; P = 0.005). Further stratification and multivariate an alyses revealed that the smoking effect was more pronounced in men than in women. These findings support a smoking effect on radiosensitivity in a hea lthy population, particularly in men, Therefore, when evaluating the associ ation between radiosensitivity and susceptibility to smoking-related cancer s, the effect of smoking should be taken into account. (C) 2000 by Radiatio n Research Society.