Chromosome aberrations in nuclear power plant workers: The influence of dose accumulation and lymphocyte life-time

Chromosome analyses were performed in blood lymphocytes of 22 nuclear power plant workers with a mean accumulated radiation dose of 390 mSv (270-530 mSv). Nineteen workers had received 300 mSv 4-16 years prior to sampling. The frequency of dicentrics and ring chromosomes (1.75x10-3) was significantly elevated as compared to a control group (0.58x10-3). Based on the initial slope of an in vitro 60Co γ-ray curve, a biological dose estimate of only 110 mSv was derived. This can be interpreted in terms of an 'equivalent-acute' dose at the time of blood sampling which can be derived by weighting annual doses during working periods of 12-30 years for a mean life-time m of lymphocytes. The annual doses were additionally weighted for a uniform distribution during a whole year. Using m=10 years, a mean 'equivalent-acute' dose of 90 mSv (64-157 mSv) is obtained, which compares more closely to the biologically estimated dose than 20 mSv (7-71 mSv) based on m=4.3 years