Mortality and cancer incidence have been studied in a cohort of about 175,000 persons on the National Registry for Radiation Workers (NRRW) who were followed until the end of 2001. This analysis was based on a larger cohort and nine years’ further follow-up compared with the second NRRW analysis, and includes cancer registration data for the first time.
As in previous NRRW analyses, total mortality and mortality from major causes were less than would be expected based on rates for England and Wales; the Standardised Mortality Ratio (SMR) for all causes was 81, whilst the SMR for all malignant neoplasms was 84. This ‘healthy worker effect’ was still present after adjustment for social class. The only cause for which mortality was statistically significantly greater than expected from national rates was pleural cancer, probably reflecting exposure to asbestos.
This analysis provided, when published, the most precise estimates of the risks of mortality and cancer incidence following occupational radiation exposure and strengthened the evidence for raised risks due to these exposures. The cancer risk estimates obtained here are consistent with values used by national and international bodies in setting radiation protection standards. Continued follow-up of these workers should be valuable to see whether radiation-associated risks vary over time or by age, and to study specific cancers and causes of death in more detail.