Eight-year follow-up study of three individuals accidentally exposed to 60Co radiation: Chromosome aberration and micronucleus analysis

•The stable aberration remained at a high level 8 year after the accident.•Dic + r and CBMN reduced gradually 8 year after the radiation exposure t.•All cytogenetic techniques had individual characteristics as dosimetry methods.

We assessed dose levels and the persistence of chromosomal aberrations and micronuclei in three individuals in the 8 year following accidental 60Co radiation exposure. Venous blood samples were collected and used for analyses: traditional chromosome aberration (CA) measurement, G-banding, and the cytokinesis-block micronucleus (CBMN) assay. For CA analysis, we scored dicentric chromosomes (dic) and rings (r) in peripheral blood lymphocytes. The radiation doses (Gy) suffered by the individuals were estimated as: 1.79–2.43 (A), 2.36–2.86 (B), 1.58–1.82 (C), based on CA analysis; and 1.8–2.34 (A), 2.52–2.98 (B), 1.53–1.77 (C), based on CBMN frequencies. G-banding analysis was used to record translocations (t), inversions (inv), and deletions (del). Following the accident, unstable CAs reduced gradually, but stable aberrations persisted. Unstable CAs and CBMN may be valuable biomarkers for dose estimation shortly after high-dose radiation accidents, while stable aberrations may be more useful for assessing long-term effects.