Sensitivity of peripheral blood lymphocytes of pilots and astronauts to γ-radiation:: Induction of double-stranded DNA breaks

The levels of DNA breaks before and after in vitro irradiation (1 Gy) of lymphocytes from 17 donors, 41 pilots, and 8 astronauts were studied by comet assay. Seventeen donors, 41 pilots, and 8 astronauts were examined. The flights augmented individual differences in the levels of DNA breaks in blood lymphocytes and in the severity of injuries inflicted by radiation exposure to lymphocyte DNA. Dispersions in the distribution of the initial levels of DNA breaks in pilots and astronauts differed significantly from the control according to Fisher's F test. The dispersion of distribution of the levels of double-stranded DNA breaks after in vitro irradiation in the group of pilots also differed significantly from the control distribution. These results necessitate evaluation of individual sensitivity to the mission conditions during medical selection.