Chromosomal aberration analysis in chronically exposed radiation workers

We performed a chromosomal aberration analysis on blood samples of 15 radiation workers by scoring dicentric aberrations. These workers were chronically exposed to cumulative doses of approximately 500 mSv over a period of two to three decades. The biological doses estimated using the linear coefficient of the in vitro dose/response curve based on dicentric frequency varied from 0 to 259 mGy, even though all the radiation workers had received approximately the same physical dose-i.e., 500 mSv. In all cases of chronic exposure, the estimated biological doses were found to be lower than the measured physical doses. The measured physical doses were corrected by applying the biphasic decay pattern of lymphocytes and also taking into consideration the time course of accumulation of doses in each individual. The corrected physical doses thus obtained were then compared with the estimated biological doses, and a reasonably good correlation was found between these two sets of values. However, on the whole, the corrected physical doses were found to be smaller than the estimated biological doses in most of the cases. This observation suggests that the kinetics of turnover of lymphocytes in conditions of chronic exposure maybe slower than estimated so far in various studies involving exposures to high doses, wherein the estimation of life span of lymphocytes was carried out in patients undergoing radiotherapy.