Tawn, E. J., Whitehouse, C. A., Daniel, C. P., Tarone, R.;thE., Bothwell, A. M. and Fisher, A. Somatic Cell Mutations at the Glycophorin A Locus in Erythrocytes of Radiation Workers from the Sellafield Nuclear Facility. Radiat. Res. 159, 117–122 (2003).
The glycophorin A (GPA) somatic mutation assay for N0 and NN mutant erythrocytes was performed on 245 current and 48 retired workers who had been occupationally exposed to radiation at the British Nuclear Fuels plc facility at Sellafield. A positive association with increasing age was found for current workers for both N0 and NN frequencies of 0.14 ± 0.05 × 10–6 (P = 0.012) and 0.25 ± 0.07 × 10–6 (P = 0.0003) per year, respectively. No association with age was found for the retired workers. In a comparison of ever-smokers with never-smokers, no difference was observed for N0 frequencies for current workers, but a significantly higher frequency was found for ever-smokers in the retired group (P = 0.001). NN mutant frequencies were slightly higher in ever-smokers than in never-smokers for both current and retired workers, but in neither case was the increase significant. In age-adjusted analyses for N0 mutant frequencies, a slight positive radiation dose response was found for current workers (1.6 ± 3.8 × 10–6 per Sv), for retired workers (2.9 ± 2.5 × 10–6 per Sv), and in the combined analysis (2.6 ± 2.2 × 10–6 per Sv), but in no case did this reach significance. Similar analyses for NN mutant frequencies revealed a positive dose response for current workers (4.7 ± 4.6 × 10–6 per Sv) and a negative response for retired workers (–2.4 ± 3.6 × 10–6 per Sv) that was maintained in the combined analysis (–1.4 ± 2.8 × 10–6 per Sv), but none of these slopes was significantly different from zero. The results suggest that the GPA mutation assay is insufficiently sensitive to be used as a biological marker of low-dose chronic exposure and provide further evidence that, in contrast to high acute radiation exposure, protracted exposure is much less effective at inducing somatic mutations in vivo.