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 G0 irradiation in vitro with a mixed fission neutron-gamma-ray beam, 220 kV X-rays and 60Co gamma-rays. The dose-response relationships for the micronucleus yields were linear-quadratic for both types of low LET radiations. The linear model applied for neutron-induced micronuclei over the dose range 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 derived from the ratio of the alpha coefficients of neutrons and 60Co gamma-rays.