The article discusses the current state of normative ensuring of radiation safety of package drinking water. The article analyses radiation-hygienic requirements for packaged drinking water in the regulatory documents of the Customs Union and the Eurasian Economic Union. It is shown that the methodology for regulation of radiation safety of drinking water in the RSS-99/2009 and the “Guidelines for Drinking-water Quality” of the World Health Organization are practically identical. However, the direct application of the similar approach to the regulation of radiation safety indicators of packaged water is associated with significant difficulties, which in some degree are related to the lack of established classification of packaged drinking water. We propose to divide natural mineral medical water which is not intended for free sale as a separate category. For this category, regulations on the content of the radionuclides is not established. The article presents a justification of approaches to regulation of radiation safety of natural mineral drinking water and packaged blended drinking water. In the light of the unique flavor and medicinal properties of most of these waters, we considered various options for the radiation safety of the population, including through recommendations on limitation of the consumption of water. It is shown that for other types of packaged water, including drinking water for baby food, there is a perfectly acceptable application of the requirements on radiation safety, which are set for water.

A commercially available NaI(Tl) based spectrometer-dosimeter has been used to separate contributions of the terrestrial radionuclides (238U series, 232Th series and 40K) and 137Cs to the total ambient dose equivalent rate (ADER), Ḣ*(10) , outdoors. The device had been initially calibrated by the manufacturer to measure: 1) the total ADER; 2) activity concentrations of 226Ra, 232Th, 40K and ‘effective’ activity concentration of the terrestrial radionuclides, ACeff, in soil, agricultural raw materials, forestry products and construction materials; and 3) ground contamination density by 137Cs. In order to derive a conversion coefficient from ACeff to the ADER stipulated by the terrestrial radionuclides (ADERTRN), two series of additional calibration measurements were performed. The calibration measurements were conducted at 27 outdoor locations in the center of St.-Petersburg and in the Leningradskaya region  (background areas). The conversion coefficient from ACeff to ADERTRN of 0.51 (nSv h–1)/(Bq kg–1) has been obtained using a regression analysis of experimental data. The intrinsic noise of the spectrometer and its response to cosmic radiation at sea level has been estimated to 7 nSv h–1. The calibration factors must be used with caution and only for detectors similar to the one employed in this study (assembly based on a NaI(Tl) single crystal, 63 mm in diameter and 63 mm in length). The spectrometer-dosimeter and experimentally derived calibration coefficients have been tested in field at seven sites in the south-western districts of the Bryansk region that had been heavily contaminated by Chernobyl fallout. The contribution of 137Cs to the total ADER varies between 40% and 95%. The preliminary results of the measurements confirm the potential of in situ gamma-ray spectrometry for assaying natural and artificial components of the ambient dose equivalent rate outdoors.

The aim of the study was to analyze the effectiveness of measures on reduction of population radiation exposure at the radioactively contaminated territories by comparing radiation doses due to natural and technogenic sources. Materials and methods: the effective doses of radiation exposure due to the Techa River contamination in Muslyumovo were calculated using the data on radionuclide intakes and coefficients recommended by ICRP. Exposure to radon was estimated based on the results of radon surveys of Muslyumovo in 1992 and New Muslyumovo in 2015. Results: the total effective dose due to the Techa River contamination accumulated over the period 1950–2000 was 144 mSv. Annual effective doses due to radon in Muslyumovo and New Muslyumovo were 9,2 and 5,1 mSv respectively. The total effective dose received due to the natural and technogenic radiation was about 0,7 Sv (a contribution of radon is 77%). The total averted dose by the year 2015 due to resettlement in 2007 is 38 mSv. The dose reduction  appeared mostly due to lower radon exposure. Conclusion: the maximum reduction of population exposure could be achieved by means of timely evacuation to uncontaminated territory together with the indoor radon prevention measures.

Objective: Assessment of solid cancer incidence risk in the Chelyabinsk subcohort of the East Urals Radioactive Trace over the 53-year period of follow-up with use of the individualized doses accumulated in the soft tissues calculated on the basis of the new dosimetric system TRDS-2016. Materials and methods: The thermal explosion of the storage tank of the «Mayak» production Association radioactive waste in September, 1957 led to the formation of the East Urals Radioactive Trace and radiation exposure of the population living on the territory of the trace. Members of the created cohort received chronic external and internal radiation exposure. The mean dose to the soft tissues over the entire follow-up period amounted to 30 mGy, maximum – 960 mGy. The number of the study cohort is 21 394 persons. Over 53 years (from 1957 to 2009) 1426 cases of solid cancer excluding 73 hemoblastoses and 101 cases of  non-melanoma skin cancer are registered in the cohort on the catchment area. Person-years at risk amount to 437 719. Individualized doses for the cohort members were evaluated on the basis of the improved dosimetric system developed by the specialists of the Urals Research Center for Radiation Medicine. The analysis was carried
out by means of the Poisson regression method with the use of the software AMFIT. Confidence intervals were calculated using the maximum likelihood estimation. Results: Risk analysis of solid cancer incidence in Chelyabinsk subcohort of the East Urals Radioactive Trace has been carried out for the first time. A significant increase in solid cancer incidence risk with increasing the dose was obtained for the cohort members who were followed-up for 53 years. The excess relative risk per dose is 0.049/100mGy (90% of DI: 0.003; 0.010) according to the linear model. No significant effect modification of the excess relative risk value due to non-radiation factors was revealed. The results of the study demonstrate that the value of excess relative risk of solid cancer incidence per unit dose after chronic exposure at low or moderate doses can be compared to that at high doses.

The modern approach to the radiation protection of the patients from medical exposure is mainly based on the principle of optimization using diagnostic reference levels. Implementation of diagnostic reference levels and optimization in Russian radiological practice is limited due to lack of methodology of data collection and patient dose assessment, investigation and management of abnormally high and low patient doses. Current study is focused on the justification of the diagnostic reference levels concept and practical aspects of establishment of diagnostic reference levels for common radiographic X-ray examinations and their use in clinical practice. It is proposed to establish diagnostic reference levels as the 75%-percentiles of X-ray unit distribution
by the patient standard doses for a given X-ray examination. Methodology for standard doses assessment is presented for different types of X-ray units. Based on the results of dose data collection in different regions of the Russian Federation in 2009–2014, the national diagnostic reference levels values are estimated in terms of effective dose for the radiographic examinations of skull, chest, cervical, thoracic and lumbar spine,
abdomen and pelvis. The methodology of the optimization process is developed for the hospital use. It includes a comparison of the patient standard doses with the national diagnostic reference levels, investigation and correction of abnormally high and low patient doses. A list of corrective measures is proposed: from additional training of the staff and manual adjustment of the parameters of examinations to the replacement of an X-ray unit. It is conferment that even a limited implementation of the optimization methodology would allow to reduce standard doses with a factor of 1,5.

The current study was devoted to estimation of effective and organ doses to the patients from the most common computed tomography (CT) examinations: head, chest, abdomen, chest+abdomen+pelvis in advanced scanners. Doses were estimated using dedicated software (CT-Expo, XCATdose, and NCICT) and conversion coefficients from the dose length product (DLP) to the effective dose according to Methodical
guidance 2.6.1.2944-11 “Assessment of effective dose to the patients undergoing X-ray examinations”. Results of the estimation of organ doses using tested software programs showed a lack of significant differences. Overall, 98% of organ doses estimated by each software program had a less than 20% difference compared with the average value of doses estimated by each software and 71% had less than 10% difference. Comparison of organ doses estimated for voxel and mathematical (MIRD-5) phantoms showed a difference up to 22%. The overestimation with a factor of two, in comparison with the software codes, was observed only for effective dose for the CT examination of a head determined according to existing guidelines. For other examinations, the differences in effective doses were insignificant. The effective dose assessed according to existing guidelines can be used to fill the report forms or rough risk estimate for justification of CT examinations.

Objective: A simulation of a large-scale epidemiological case-control study to identify the relationship between exposure to radon and lung cancer in the presence of factors that distort the results of the assessment of exposure to radon in homes. Materials and Methods: Analysis of sources of uncertainties arising during radon epidemiologic case-control studies. Evaluation of the uncertainties caused by the errors of the measurements of the long-term variations in the radon concentration, exposure to radon in other places of the human habitat, except dwellings, etc. Simulation by Monte Carlo technique of radon epidemiologic study, comparable to the combined European radon study, and assessment of uncertainties, which affect the evaluation of dose-effect dependence. Results: The multiplicative error in the assessment of individual exposure based on the radon concentration is shown generally caused by the combined effect of long-term variations of the radon concentration and the differences in the levels of the radon concentration in living houses and other places of the human habitat. The logarithmic standard deviation of this errors σerr is from 0,70 to 0,90. The estimated value of this error is 2,0 times higher than the value used for correction of the results of the combined European radon study. It is shown that for the σerr <0,9 regression calibration technique, there is a possibility to make a full correction of uncertainty. Conclusion: Errors in the assessment of uncertainties of the radon exposure based on the radon concentration in the combine European radon case-control study has led to an underestimation of the relative risk of lung cancer incidence at least with a factor of 1,5.

The paper presents the methods of risk assessment from exposure to radon. Proposed methods implement a differentiated approach to the risk estimates calculation procedure which depends on the purpose of risk assessment. This approach is based on the analysis of the results of practical tests of different risk assessment models on arrays Russian medical and demographic data with and without consideration of the synergistic effect of smoking, in simple and complex exposure scenarios. All of these tests were performed in previous 5 years (results are available elsewhere). In this work the evaluation of effectiveness of radon mitigation actions in schools was used as a test task and results obtained using 4 models («EPA-2003», «Wismut-2006», «FCZ» and «Tomasek-2014») were compared. If it is important to evaluate the effect of reduction of radon concentration on the health of children and adolescents in terms of lifetime
lung cancer risk, «Tomasek-2014» model will be the best choice. It is as sensitive as «FCZ» model and ERR is close to that from «Wismut-2006» model, which was earlier proposed by other authors for use with some modifications in Russia. If the data on radon concentration are limited (for example data from radiation-hygienic passports of territories) and constant lifelong exposure scenario is considered, it seems reasonable to apply more simple «Darby-2005» model. Thus, the proposed methods could be used by specialists in various fields in a wide range of tasks, from the risk assessment for  the purposes of radiation-hygienic certification and comparative assessment of radiation safety of the population of different regions of Russia on the basis of the generalized statistical data, to the risk assessment in practical works where large amounts of measurement data on the radon concentration and complex exposure scenarios are used.