Assay of micronuclei in peripheral blood lymphocytes as a biological indicator of radiation dose

Chromosomal aberration analysis (CA) has regularly been used as a biological dosemeter to evaluate suspected overexposures to ionising radiations. Recently, the micronucleus (MN) assay has been suggested as an alternative method. An attempt has been made to explore the dose response parameters of MN assay in cytokinesis-blocked lymphocytes. Whole blood was irradiated with 60Co gamma rays or 250 kVp X rays. A dose-dependent increase in micronuclei yield was observed. The background value derived for 25 samples from healthy individuals ranged from 6-18 micronuclei per 1000 cells, with a mean value of 12 ± 4 x 10-3. Biological dose estimates for individuals exposed in the range 0.1-1 Gy made by MN and CA methods yielded similar results for doses ≥ 0.5 Gy. Due to the uncertainties in the background incidence of MN, at present this technique cannot provide reliable estimates at low doses. (author)