Evaluation of sister chromatid exchanges, micronuclei, and proliferating rate index in hospital workers chronically exposed to ionizing radiation.

PURPOSE The aim of this study was to determine the incidence of sister chromatid exchanges (SCE), micronuclei (MN) and proliferation rate of harvested lymphocytes obtained from medical stuff professionally exposed to low-dose ionizing radiation. The influence of tobacco smoking status and working conditions as confounding factors were also investigated. PATIENTS AND METHODS Thirty subjects chronically exposed to low-dose ionizing radiation were examined (12 workers in the radiotherapy unit and 18 workers in the cardiology unit), and were compared to 15 unexposed healthy volunteers. There were 18 nonsmokers and 12 smokers among the exposed workers and 8 nonsmokers and 7 smokers among the control group. Standard cytokinesis-block MN assay, the SCE assay, and the proliferating index (PI) rate were analyzed. RESULTS An increased frequency of SCE and MN in occupationally exposed workers were found compared to unexposed individuals. The PI was significantly lower in occupationally exposed workers in comparison to the control group. In relation to the working conditions, a significantly higher number of MN in the group of workers in the radiology unit compared to the control was found (p=0.03). The frequency of SCE was increased in occupationally exposed smokers compared with nonsmoking workers (p=0.005). Smokers in the control and radiation exposed group had lower MN frequency contrary to nonsmokers in both groups. CONCLUSION The obtained results show higher incidence of SCE and MN in the exposed groups compared to the controls. Cigarette smoking and working conditions as confounding factors should be included into genetic monitoring studies assessing the risk associated with low-level radiation exposure.