FISH chromosome aberration analysis on retired radiation workers from the Sellafield nuclear facility

Chromosome analysis using fluorescence in situ hybridization was undertaken on 294 retired workers from the British Nuclear Fuels plc facility at Sellafield, 95 with external occupational exposure <50 mSv, 108 with 50-499 mSv, and 91 with >500 mSv. In univariate analyses, external dose (P <10-s) and age (P = 0.0075) were significantly associated with translocation frequency, but no effect was found for smoking status. In a multivariate analysis with age and external dose as continuous variables, the slopes were 0.017 +/- 0.0075 x 10(-2) translocations per cell per year for age (P = 0.024) and 1.11+/- 0.190 x 10(-2) translocations per cell per sievert for external dose (P < 10(-5)). The dose response for translocation induction for occupational workers is similar to the linear component of in vitro dose-response curves, thus supporting the use of translocation frequency for retrospective biological dosimetry in situations of chronic low-dose exposure occurring over many years. The dose response obtained in this study is lower than the linear component of the dose response for stable chromosome aberrations obtained for the Japanese atomic bomb survivors. Thus, if chromosome aberration levels are indicative of cancer risk, this would suggest that low-dose risks derived from the Japanese atomic bomb survivor data will overestimate the risks associated with the occupational exposure encountered by the men in this study.