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

We assessed dose levels and the persistence of chromosomal aberrations and micronuclei in three individuals in the 8 year following accidental (60)Co 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.