Induction of micronuclei by irradiation with neutrons produced from 600 MeV protons

In an attempt to evaluate the production of micronuclei as a test for the evaluation of radiation damage, a study has been made of the induction of micronuclei in Vicia faba roots up to 72 h after irradiation by neutrons ranging from a few MeV to 600 MeV. The values obtained for irradiations with 600 MeV neutrons and 60Co γrays showed a large variation of RBE with dose, over a dose range 0 to 200 cGy. The number of cells containing micronuclei was related to the growth reduction in ten days. A complete loss of the proliferative capacity of the meristem ten days after irradiation was found when the total growth in ten days was reduced by 75% when about 27% of the meristem cells contained micronuclei. Assuming a linear relation between growth and micronuclei, good agreement was obtained between estimated and experimental results. (U.K.)