Induction of chromosome aberrations and cell killing in Syrian hamster fibroblasts by gamma-rays, X-rays and fast neutrons.

Chromosome aberrations were scored in BHK21 C13 Syrian hamster fibroblasts, exposed to 60Co gamma-rays, 250 kV X-rays, 15 MeV neutrons or neutrons of mean energy 2.1 MeV produced from the 9Be(d,n)10B reaction. The cells were irradiated in stationary phase, where they are concentrated in the G1 phase of the cell cycle. Within experimental uncertainty there was no detectable difference between the responses to 60Co gamma-rays and to 250kV X-rays. The r.b.e. for the production of dicentrics, based on the 'one-hit' component of response, was (5 +/- 2) for the 15 MeV neutrons and (12 +/- 5) for the 2.1 MeV neutrons. For each radiation, a graph of the proportion of cells without a dicentric, centric ring or acentric fragment corresponded closely to the survival curve for stationary-phase cells obtained in the same experiment.