DOSE-RESPONSE RELATIONSHIPS OF MICRONUCLEI IN HUMAN-LYMPHOCYTES INDUCED BY FISSION NEUTRONS AND BY LOW LET RADIATIONS

The induction of micronuclei in cytokinesis-blocked human lymphocytes of different donors has been measured after G(0) irradiation in vitro with a mixed fission neutron-gamma-ray beam, 220 kV gamma-rays and Co- 60 gamma-rays. The dose-response relationships for the micronucleus yi elds were linear-quadratic for both types of low LET radiations. The l inear model applied for neutron-induced micronuclei over the dose rang e 0-0.66 Gy. At higher doses a saturation effect became apparent. For neutron-induced micronucleus yields a limiting RBE value of 12.2 was d erived from the ratio of the alpha coefficients of neutrons and Co-60 gamma-rays.