Retrospective biodosimetry of Chernobyl clean-up workers using chromosome painting and conventional chromosome analysis

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Abstract
Blood samples of 52 Chernobyl clean-up workers were analysed by fluorescence in situ hybridization (FISH) using whole-chromosome painting probes for chromosomes 1, 4 and 12, simultaneously with a pancentromeric probe and by conventional chromosome analysis, for radiation-induced symmetrical translocations and dicentrics in T-lymphocytes. Based on FISH measurements of translocations, individual biodosimetry estimates between 0.32 and 1.0 Gy were obtained from 18 cases. Pooled data for the total group of 52 workers provided a collective biodosimetry estimate of 0.23 Gy. For a group of 34 workers with documented doses, the mean dose estimate of 0.25 Gy compared well with the mean documented dose of 0.26Gy. However, no correlation between individual translocation frequencies (F) and docuG mented doses could be found. A statistical analysis of the expected dose-response suggests exposures to higher doses than documented for a substantial fraction of workers with ascribed doses <0.2 Sv. For subjects working repeatedly at the reactor site between 1986 and 1995 the mean translocation frequency was significantly higher than for those working only in 1986. A comparison of dicentric frequencies obtained by conventional scoring and by FISH measurements showed no significant difference, although only two of 52 cases revealed significantly higher yields than the mean control level. Based on conventionally scored dicentric frequencies, a collective biodosimetry estimate of 0.23 Gy could be derived only of the group of persons working at Chernobyl exclusively in 1986 for which a documented average dose of 0.19 Gy was reported.