A cytogenetic study of radiological workers: effect of age, smoking and radiation burden on the micronucleus frequency

A large scale cytogenetic study of the radiation damage in nuclear power plant workers and medical workers handling X-ray machines (269 individuals) was undertaken using the micronucleus assay for peripheral blood lymphocytes. The micronucleus frequency was found to increase systematically with donor age. After correction for the age-dependence, no correlation of the micronucleus frequency with smoking habits, expressed as cigarette-years and cigarette consumption per day, could be observed. Compared to the group of administrative workers receiving doses below 1 mSv/year, limit recommended by the ICRP for public exposure, the micronucleus frequency was slightly increased in the group of radiation workers, exposed occupationally. However, applying the Mann-Whitney test, the observed differences are not statistically significant. After correction of the dose accumulation pattern for the turn-over of the lymphocyte pool, a weak correlation between the micronucleus frequency and the equivalent dose accumulated over the 10 years preceding the study was obtained. For clear-cut conclusions on the radiation damage of low-dose worker cohorts, an increase in the sensitivity of the assay, e.g., by analysis of the micronuclei for the presence of centromeres is necessary