Experimental exposure of naive bank voles (Clethrionomys glareolus) to theChornobyl, Ukraine, environment: A test of radioresistance

Previous studies have demonstrated no difference in micronucleus (MN) frequ encies between wild rodents chronically exposed to the environmental radiat ion contamination of the Chornobyl (Ukraine) exclusion zone and those inhab iting reference populations. The aim of the present study was to test the h ypothesis that a population of bank votes (Clethrionomys glareolus) has dev eloped radioresistance as a result of 14 years of chronic, low-dose radiati on exposure. Naive votes were placed in environmental enclosures in the Red Forest region of the exclusion zone for 30 d. Blood samples were obtained at regular intervals, and the MN assay was used to assess chromosomal damag e. Additionally, radionuclide uptake was monitored throughout the study, an d dose was documented for each individual as well as for their offspring' T otal dose for the votes experimentally exposed in this environment averaged 1.09 Gy (36.20 mGy d(-1)) for the 30-d study period. Our results indicate that exposure to radiation levels well above regulatory statutes did not re sult in an increased MN frequency. Furthermore, our results do not support the hypothesis that votes chronically exposed to these radiation levels hav e developed a genetic basis for radioresistance that is unique from that pr esent in naive populations. The use of C. glareolas as a sentinel species f or environmental studies of radiation contamination and the question of whe ther the NLN assay is an appropriate endpoint for studies of low-dose, chro nic radiation exposure are also discussed.