The production of chromosome aberrations in Chinese hamster fibroblasts by gamma and neutron radiation.

Chromosomal aberrations were scored in V79/4 Chinese hamster fibroblasts exposed to 60Co gamma-rays and to fast neutrons produced from the 9Be(d,n)10B reaction. In oder to avoid problems with the variation of aberration induction with the phase of the cell cycle, the cells were irradiated in stationary phase, where they are concentrated in the G1 phase of the cycle. The r.b.e. for the production of dicentrics was 2.7 +/- 0.2 at a neutron dose of 2.0 Cy; the r.b.e. of the 'one-hit' component of response was 6.4 +/- 1.1. These r.b.e. values are much lower than those reported for primary human lymphocytes. Graphs of the proportion of cells without a dicentric, centric-ring or acentric fragment, as a function of dose, corresponded closely to the survival curves of the cells, which had been obtained previously, for both radiations.