This paper reports the findings of an historical chromosome analysis for unstable aberrations, undertaken on 34 nuclear workers with monitored exposure to tritium. The mean recorded β-particle dose from tritium was 9.33 mGy (range 0.25-79.71 mGy) and the mean occupational dose from external, mainly γ-ray, irradiation was 1.94 mGy (range 0.00-7.71 mGy). The dicentric frequency of 1.91 ±0.53 ×10-3 per cell was significantly raised, in comparison with that of 0.61 ±0.30 ×10-3 per cell for a group of 66 comparable worker controls unexposed to occupational radiation. The frequency of total aberrations was also significantly higher in the tritium workers. Comparisons with in vitro studies indicate that at these dose levels an increase in aberration frequency is not expected. However, the available historical tritium dose records were produced for the purposes of radiological protection and based on a methodology that has since been updated, so tritium doses are subject to considerable uncertainty. It is therefore recommended that, if possible, tritium doses are reassessed using information on historical recording practices in combination with current dosimetry methodology, and that further chromosome studies are undertaken using modern FISH techniques to establish stable aberration frequencies, as these will provide information on a cumulative biological effect.
Bibliographical noteFunding Information:
We thank the workers who supported this study and provided blood samples. The study was facilitated by Dr Eric Barker. Les Scott supplied dosimetry data from the BNFL worker epidemiology database. We also thank Professor Richard Wakeford for advice on the manuscript, and whose continuing support has enabled the completion of this work. The work was supported by the former British Nuclear Fuels plc, the Nuclear Decommissioning Authority, and Public Health England’s Centre for Radiation, Chemical and Environmental Hazards.
© 2018 IOP Publishing Ltd.
- chromosome aberrations
- occupational exposure