Purpose: To determine the relative biological effectiveness (RBE) of a mixed neutron-gamma-radiation field and its high LET component on the induction of chromosome aberrations in human lymphocytes.
Materials and methods: Human lymphocyte cultures were exposed in vitro to low doses of simulated cosmic radiation (2.39-5.81 mGy) at low dose rates (0.04-0.15 mGy/h). Chromosome aberrations, micronuclei, and sister chromatid exchanges (SCE) were analysed. The RBE for dicentric chromosomes was given in comparison to 60Co gamma-rays.
Results: For the induction of dicentric chromosomes by simulated cosmic radiation the RBE was up to 64, and up to 113 when calculating only the high LET component. The investigation of micronuclei and SCE showed no significant differences between controls and irradiated samples.
Conclusions: Preliminary data indicate a high biological effectiveness of cosmic radiation and its neutron component in comparison with 60Co gamma-radiation.