Identification of markers of occupational combined radiation exposure using a molecular cytogenetic mFISH technique

The present study was aimed to analyze damages of chromosome structures in Mayak PA workers occupationally exposed to combined radiation using an up-to-date molecular cytogenetic mFISH technique. The study of chromosome spreads showed that the stable chromosome aberration frequency in the group of workers exposed to external gamma-rays at cumulative absorbed red bone marrow (RBM) doses exceeding 0.2 Gy was significantly increased compared to the stable chromosome aberration frequency in the group of workers exposed at doses below 0.2 Gy due to the increased level of translocations which are a biological marker of external radiation exposure. The frequency of stable chromosome aberrations was significantly higher in the group of workers with 239Pu body burden exceeding 1.48 kBq due to a considerable number of cells carrying complex chromosome rearrangements. We observed linear associations of translocation frequency with absorbed RBM dose from external gamma-rays and of complex chromosome rearrangement level with 239Pu body burden. The frequency of chromosome aberrations (translocations and complex chromosome rearrangements) revealed by mFISH technique was shown to be an effective biological indicator for combined radiation exposure.