COMPARISON OF DOSE-RESPONSE CURVES FOR CHROMOSOMAL-ABERRATIONS ESTABLISHED BY CHROMOSOME PAINTING AND CONVENTIONAL ANALYSIS

Purpose: To establish Co-60 gamma-ray dose-response curves for dicentr ics and translocations visualized by chromosome painting and for dicen trics analysed after conventional solid staining. Materials and method s: Analysis of chromosomal aberrations was performed on peripheral blo od lymphocytes obtained from 48 h old cultures of irradiated whole blo od. Dicentrics were scored from Giemsa-stained preparations, and bi-co loured dicentrics and translocations after FISH painting of chromosome s 1, 2 and dr. Results: Equal frequencies of complete dicentrics and t ranslocations, where both members of the exchanges were seen, were obs erved in the chromosome painting analysis at all doses, resulting in s imilar calibration curves. Due to differences in scoring criteria, dic entrics scored in conventionally Giemsa-stained slides agreed better w ith data for total than for complete exchanges. Donor differences for translocations at the control level and at low doses were seen and lar ge uncertainty surrounds the linear component of the dose-response for total translocations. Conclusions: Dose reconstruction of past exposu res in cases of low doses is very dependent on the linear coefficient of the curve. Results indicate that total translocations would give le ss reliable dose estimates and therefore complete translocations are p referred.