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Background. Cytogenetic damage (СD) in lymphocytes induced by low doses (up to 0.1 Sv) of ionizing radiation (IR) is the main cytogenetic sign of individual radiosensitivity of the human body. In addition to DNA repair and cell death, which affect the formation of СD and its elimination, IR effects on the cell can be manifested through changes in proliferation of cells with unrepaired DNA damage. The system of cyclins and cyclin-dependent kinases (CDK), which provide coordination of mitotic events during passage of a cell through the cell cycle, plays a crucial role in regulation of cell proliferation.Aim. To evaluate the relationship of single-nucleotide polymorphisms (SNPs) of cell cycle genes with an increased frequency of СD in workers of a nuclear power plant affected by chronic occupational radiation exposure in the dose range of 100–500 mSv.Materials and methods. The object of the study was blood of 55 conditionally healthy workers of Siberian Chemical Plant (SCP) who were affected by chronic occupational radiation exposure (gamma radiation) in the dose range of 100–500 mSv. A standard cytogenetic analysis of blood lymphocytes was performed for all examined individuals. Genomic DNA was isolated from the blood of the workers using the QIAamp DNA Blood Mini Kit (QIAGEN, Germany). DNA was genotyped using 257 SNPs of cyclin genes and neighboring intergenic regions using DNA microarrays from the high-density CytoScan HD Array (Affymetrix, USA).Results. Taking into account the Bonferroni correction, only statistically significant associations of SNPs with the frequency of dicentric chromosomes were found; all other types of chromosomal aberrations did not show statistical significance. The rs803054 CCNI2 was associated with an increased frequency of dicentric chromosomes arising under the influence of chronic occupational radiation exposure.Conclusion. The discovered SNP (rs803054), whose recessive genotype is associated with an increased frequency of dicentric chromosomes in workers of SCP exposed to radiation at doses of 100–500 mSv over a long time, can be considered as a potential marker of individual radiosensitivity. To confirm the identified associations, further validation studies are needed on an expanded sample of people affected by chronic occupational radiation exposure.

Background. One of the main directions in the field of ensuring radiation safety of “nuclear legacy” facilities is the assessment of radiation effects and most significant radiogenic risks in employees of nuclear enterprises and their descendants.Objective. Analysis of the cancer incidence among employees of the Siberian Group of Chemical Enterprises (SGCE) exposed to ionizing radiation in the course of their professional activities.Material and Methods. The actual values and standardized estimated risks of developing cancer among the SGCE workers occupationally exposed to ionizing radiation were calculated using generally accepted methods based on the information of the regional medical dosimetry registry of Seversk Biophysical Research Center of FMBA, containing updated data on all SGCE employees diagnosed with cancer (period from 01.01.1950 to 31.12.2015 inclusive). The control group consisted of workers who were not occupationally exposed to ionizing radiation.Results. Among the male personnel of the SGCE, the highest incidence of cancer of the digestive, respiratory, and skin organs (including melanoma) was observed in patients aged 50–59 and 70–79 years. Among the female workers, the highest cancer incidence was in the age group 40–49 years; cancer of the gastrointestinal tract, genital tract and breast was the most common. The cancer incidence rate in the SGCE workers who occupationally exposed to ionizing radiation was not higher that that observed in the control group. The median age of male cancer patients occupationally exposed to ionizing radiation was significantly lower than the median age of male cancer patients of the control group. In female cancer patients, a significant difference in the median age of cancer diagnosis was found only in relation to skin cancer. Both male and female SGCE personnel occupationally exposed to ionizing radiation was at high risk of certain cancers: among male patients – cancer of the mesothelium and soft tissues, genital organs, eyes and brain, as well as multiple primary tumors; among female patients – cancer of lips, oral cavity, pharynx, digestive system, respiratory system, skin (including melanoma), mesothelium, soft tissues, breast, urinary tract, lymphatic and hematopoietic tissues, as well as multiple primary tumors.Conclusion. The data obtained will allow determination of the main directions for assessing the health risks of personnel of radiation hazardous facilities and the formation of a set of measures aimed at improving the system of protection and improving the health of workers at radiation hazardous enterprises and the extension of their working longevity.

Objective: To estimate the incidence of malignant neoplasms of lymphoid tissue (MNLT) among employees of the siberian chemical combine (SCC) occupationally exposed to prolonged ionizing radiation.Material and methods. The study included 44,041 employees of the SCC, of whom 16,938 were occupationally exposed to prolonged low-intensity ionizing radiation (IR). Of 295 cases with hemoblastoses, there were 89 with occupational exposure to IR. The structure and incidence of hemoblastoses (based on the number of person-years of observation, (PYO), as well as the standardized relative risk (SRR) of their development and excess relative risk (err) per unit dose of radiation (GR) were evaluated. Calculation of SRR was carried out for the following intervals of the total dose of external exposure: 0; >0–0.05; >0.05–0.10; >0.10-0.15; >0.15–0.20; >0.20-0.30; >0.30-0.50; >0.5–1.0; ≥ 1.0 Gy. The control group consisted of occupationally non-exposed employees of the SCC. The calculation of SRR and err was performed using the poisson regression using the amfit module of the EPICURE package.Results. The incidence of MNLT among males of SCC was 17.1 per 100,000 PYO, with the highest incidence rates for Non-Hodgkin’s lymphoma (NHL), chronic lymphocytic leukemia (CLL) and chronic leukemia (CL) excluding CLL. Among females of the SCC, the incidence of MNLT was 21.3 per 100,000 PYO. It was found that in none of the intervals of the external exposure there was no statistically significant excess of the SRR compared with the control group. The results of ERR/GY calculation also did not demonstrate the increased risk of hemoblastosis among people occupationally exposed to IR.Conclusion. Occupational exposure in the studied dose range does not increase the risk of developing MNLT.