POTENTIAL AND LIMITATIONS OF FLUORESCENCE IN SITU HYBRIDIZATION AS A TECHNIQUE FOR RETROSPECTIVE ANALYSIS OF LOW DOSE RADIATION EFFECTS IN PEOPLE IN THE POST-CHERNOBYL PERIOD

摘要

Fluorescence in situ hybridization (FISH) analysis was done in remote periods after the Chernobyl accident in groups of rescue workers, evacuees from the 30 km exclusion zone, residents of radioactively contaminated areas, and control donors age-matched to exposed people. Stable and unstable chromosome type exchanges were recorded using a hybrid conventional-PAINT nomenclature. The average yield of stable chromosome exchanges in rescue workers did not correlate with registered radiation doses but had a clear negative dependence on the duration of rescue workers' stay in the Chernobyl zone. That was in a good agreement with early data based on conventional analysis of dicentrics and rings. We observed excess in stable chromosome exchanges over the spontaneous level. It was higher in evacuees 16-40 years of age than in senior people, whereas age-dependent difference was not observed for initially induced dicentrics and rings in this group. The stable chromosome exchange yield, combined yield (dicentrics and rings), and potentially unstable incomplete translocations in residents of radioactively contaminated areas demonstrated positive correlation with ~(137)Cs contamination. The observed yields of stable chromosome exchanges in all three groups are somewhat lower than those expected for unstable exchanges, which were considered as in vitro dose response of stable output of exchanges in human lymphocytes. Thus, FISH analysis can be successfully applied to qualitative cytogenetic analysis of previous constant radiation exposure to low doses. However, adjustment of the FISH-based system is still required for quantitative dose assessment. Some practical approaches of solving this problem are discussed.