DOSE AND DOSE-RATE RESPONSE OF LYMPHOCYTE CHROMOSOME ABERRATIONS IN MICE CHRONICALLY IRRADIATED WITHIN A LOW-DOSE-RATE RANGE AFTER AGE ADJUSTMENT

摘要

The incidences of chromosome aberrations were analysed in splenic lymphocytes from mice that were continuously exposed to ~(137)Cs gamma rays within the low-dose-rate (LDR) range to evaluate the dose-response and dose-rate effects. Chromosome aberrations were detected by fluorescence in situ hybridisation method, and these were found to increase in frequency up to 8000 mGy at 20 mGy for 22 h d~(-1) and to 700 mGy at 1 mGy for 22 h d~(-1). Translocations increased in a linear quadratic manner with age in non-exposed mice. The dose-response relationship for the frequency of translocations at each dose rate (20 and 1 mGy for 22 h d~(-1)) was obtained using age-adjusted multiple linear regression analysis. Values of the linear term, shown as the slope, decreased as the dose rate was reduced from 20 to 1 mGy for 22 h d~(-1), indicating a positive dose-rate effect in the LDR range. These results will be useful for estimating the risk of LDR radiation exposure and radiation protection.