Physics of auroral phenomena : proceedings of the 35th Annual seminar, Apatity, 28 Februaru – 02 March, 2012 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2012. - 187 с. : ил., табл.

D A. Petrashova et al. Results and Discussion Measurement of natural radionuclides (232Th и 238U, 40K) on the ore body surface and in different compartments in the Lovozero district mine shaft (Revda) have shown that exposure dose at the ore body exit surface was 1.9 mSv/h while the gamma-ray background and the exposure rate throughout the mine were in the range of 0.5-1.5 mSv/h in the absence of tehnogenic radionuclides (13 Cs, ^Sr et al). The daughter products of 226Ra, 228Ra, 224Ra such as radon, thoron, RaA, RaV and RaS were found in the airspace in of all mine sections. The maximum concentrations of radon (20,000 Bq/m3) were found at the working face and in poorly ventilated areas (Петрашова и др., 2011). Thus, the miners were exposed to chronic irradiation by mixed sources of ionizing radiation of natural origin. The majority of buccal cells have a large cytoplasm relative to the nucleus and the shape of the cell is angular rather than spherical, the exception is basal cells. Genomic instability or genotoxic insult in the basal cells leads to chromosome breakage or loss and micronucleus formation. Some cells with genome damage may be eliminated via the apoptotic process. The daughter cells from the basal layer differentiate into “prickle cells” which are eventually differentiated into the flattened and keratinized surface mucosal cells which exfoliate from the surface of the oral lining. Each of these cell types may contain micronucleus (Holland et al., 2008). Photographies of the different buccal epithelial cell types are presented (Fig. 1). 1 2 3 4 Fig. 1. Different buccal epithelial cell types: 1 - with normal nucleus, 2 - binucleate cell; 3 - cell with micronucleus; 4 - cells with apoptosis. The cytogenetic characteristic frequencies in the exposed and unexposed groups are presented in the table. You can see that the frequency of cells with a normal nucleus in 2 times more in the unexposed group than in the exposed group (p = 0.0002). Miners have in 1.8 times more cells with karyolysis (p = 0.0064), in 12.4 times more cells with karyorrhexis (p = 0.0107) and in 2.26 times more binucleate cells. Table. Cytogenetic characteristic frequency (%) Type M±m Significance unexposed group exposed group level Cells with normal nucleus 58.70±5.09 29.23±3.86 p=0.0002 Cells with micronucleus 0.16±0.04 0.11±0.038 p=0.3675 Cells with karyolysis 27.02±3.84 49.25±5.53 p=0.0064 Cells with pyknosis 4.26±1.08 6.8Ш .09 p=0.1202 Cells with karyorrehxis 0.38±0.18 4.72±1.44 p=0.0107 Cells with vacuolizated nucleus 3.54±0.67 6.14±1.68 p=0.2076 Cells with fragmented nucleus 4.03±0.55 2.13±0.87 p=0.1025 Cells with apoptosis 1.88±0.37 0.93±0.29 p=0.0561 Binucleate cells 0.016±0.016 0.42±0.09 p=0.0015 Cells with nuclear bud - 0.09±0.04 Cells with nuclear cut - 0.17±0.07 The significant difference was not found between exposed and unexposed groups in relation to frequencies of micronucleus (p=0.37). The frequency of cells with apoptosis were at 2 time higher in the unexposed group than the exposed group (p=0.06). When all types of cytological and nuclear disorders had been combined by the type of cell death (apoptosis or necrosis) it was found that the buccal cell death by necrosis type occurred in 1.9 times more often in the exposed group (66.9% vs 35.2%, p=0.0001). That is necrosis type of cell death was dominated. At the same time, the buccal cell death by apoptosis type occurred in 1.8 times more often in unexposed group than in the exposed group (5.9% vs 3.3%, p=0.0771). Thus, we have shown that cytogenetic features in miner’s buccal epithelium cells, induced by the natural 184