Cytogenetic consequences of chronic irradiation in rodent populations inhabiting the Eastern Ural Radioactive Trace zone

Chromosome instability in bone-marrow cells and ⁹⁰Sr accumulation in the bone tissue are studied in rodents (Apodemus (Sylvaemus) uralensis Pall., 1811 and Apodemus agrarius Pall., 1771)* inhabiting the Eastern Ural Radioactive Trace (EURT) zone (Kyshtym radiation accident 1957) and adjacent areas of the Urals. Intensive mutagenic process in both species from impact plots (soil pollution by ⁹⁰Sr, 2322–16690 kBq/m²) is found. Significant positive correlation of the frequency of aberrant cells and the concentration of ⁹⁰Sr is shown. Possible causes of the lack of resistance to long-term mutagenic factors (over 100 generations in the 50 years since the accident), such as migration of animals and the specific configuration of the EURT zone (an extended narrow territory with a sharply falling gradient of radionuclide pollution), which considerably decrease the probability that certain changes will be fixed and inherited in a series of generations of rodents, are discussed.