Cytogenetic analysis of peripheral blood lymphocytes, many years after exposure of workers to low-dose ionizing radiation

• Long-term cytogenetic analysis for subjects exposed to low-dose radiation.
• Obviously elevated rates of chromosome-type aberrations and MN were observed.
• Genotoxic effect of ionizing radiation remains in the subjects long after exposure.

The present study aims to measure chromosomal aberrations and micronuclei in peripheral blood lymphocytes from 25 subjects exposed to 0.10–0.33 Gy external or internal irradiation 32–41 years ago using conventional cytogenetic analysis methods. The frequencies of total chromosome-type aberrations and micronucleus significantly increased in the exposed group compared with that in age-matched control group (p < 0.001); chromatid-type aberrations showed no difference between the two groups (p > 0.05). When exposed subjects were divided into two groups based on exposure dose, higher levels of dicentric plus translocation frequencies were observed in the ≥0.15 Gy dose group compared with those in the <0.15 Gy dose group, though the difference was not significant. Borderline association between exposure dose and dicentric frequency was detected in the exposed group (r = 0.358; p = 0.079). These results suggest that the genotoxic effects of ionizing radiation remain in subjects exposed to low-dose radiation even decades after exposure.