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In this article it made analysis of concepts and values used in NRB-99/2009 and a number of national methodological documents on the assessment of risks associated with irradiation. It is concluded that NRB-99/2009 violates the logic in the presentation of this issue. It can be restored if a special section is introduced in the developed NSB-2019, with more detailed coverage of the terminological and methodological aspects of the assessment of such risks. The draft section is attached to this article In the draft introduces a number of new terms (radiogenic risk, nominal radiogenic risk, radiogenic risk of death from cancer and radiogenic risk of cancer and a number of others) with a clear interpretation of their meaning and purpose, as well as the sphere application of the relevant values. The draft proposes to replace the term generalized risk with radiation risk, which is more in line with its meaning. Given also specific formulas to calculate the radiogenic risk coefficients for different types of irradiation based on the real demographics data for exposed populations. Because of the cumbersome formulas, they can be given to the Annex of the NRB-2019 or issued in methodical instructions prepared in the elaboration of the provisions of the NRB-2019.

Research and Technical Center of Radiation-Chemical Safety and Hygiene (RTC RCSH), Moscow, Russia Generalized radiogenic risk models presented in ICRP Publication 103 have a number of attractive features. The models themselves and the corresponding models of background risks are generalized by a single function containing only three parameters specific to the localization of cancer, sex and risk indicator (absolute or relative; mortality or morbidity). However, there are several discrepancies in the values of model parameters for the individual cancer sites and in some predictions based on these models. The aim of this study was to clarify the possibility of refining the parameters of the ICRP models using the LSS cohort data. The method of calculation of the parameters of these models has been developed and verified based on the data on baseline mortality in the cohort and among entire Japanese population. The method consists in the averaging of the local estimates of the parameters calculated based on the values of the rate of the mortality in the ends of different segments of age at exposure and attained age within the entire examined area of change of these variables. The latest published mortality data in the cohort and mortality tables for Japan from the WHO database were used to calculate the mortality rate matrices. Data on the baseline mortality from solid cancers in LSS were in good agreement with statistically more reliable data for the entire Japanese population. Hence, the latter were used for verification of the method.According to the criteria of absolute and relative standard deviation, the ICRP models at whole better approximate baseline and radiogenic mortality from solid cancers in the cohort based on the values of parameters calculated using the proposed method compared to the values from the ICRP. The sets of parameter values for men and women, calculated from LSS data and for the Japanese population differ significantly, while in ICRP models they are almost the same.

The aim of this work was to determine the validity of the direct transfer of the recommendations of the ICRP on the nominal risk coefficients and tissue weighting factors in a future revision of the national Radiation Safety Standards (NRB). The article compares the background age and sex distribution, and morbidity and mortality rates of the nominal population, the ICRP used to develop the latest fundamental recommendations, with appropriate indicators for the populations of Russia and Japan as the main source of data for assessment of radiogenic risk in the second half of the last decade. It is revealed that the functions of survival and age-related morbidity and mortality of the Russian population, especially for males, is significantly different from the composite population, while for the Japanese population, the differences are relatively small. The estimates of radiogenic risk coefficients for cancers of various localization using calculation schemes and risk models of the ICRP Publication 103, but based on background data on incidence and mortality of the Russian population were obtained. Baseline incidence and mortality for the Russian population are worse compared to the composite population. Hence, risk coefficients for the Russian population can be taken lower than the recommended ICRP by approximately 20% for the total population and 30% for the persons of working ages. The results clearly demonstrate the inconsistency of the modern criteria of radiation protection, based almost exclusively on the account of carcinogenic effects of ionizing radiation, since it implies that radiation is more harmful for a healthier population. The results also show timeliness of issue of the choice of the calendar period for which the age-dependence of the intensity of cancer incidence and mortality from all causes are taken into account. The article justified the continuation of the discussion of the raised issues, as well as the issues of development the mathematical models used in the estimation of radiogenic risks.

Briefly considered history of the development and present status of the normative-methodical basis for the limitation of man-made and natural radon influence on personnel and population. It is analyzed the transfer factors from radon radiometric values to effective dose, corresponding to various versions of RSS and normative-methodical documents for limitation of the irradiation from natural sources. It is formulated proposals to the new RSS editing in a part of the standardization of radon.

The problem of reliable estimation of annual radon concentration in the new buildings by results of short-term measurements is still actual. The task is to determine the relevant real values of the coefficient of temporal variations of radon. To this end, analyzed two fundamentally different approach to research methodology and accounting regularities of variations of radon EEC in indoor buildings. Based on experimental data shows that in assessing the average radon EEC levels is the most effective and took into account the ratio of current and annual air temperature differences inside and outside the building. The proposed principle is recommended for use in the development of improved methods of radon control of buildings.

The methods: Linear differential equations were used to formalize contemporary assumptions of self –sustaining tissue cell kinetics under the impact of adverse factors, on the formation and repairing of cell “pre-cancer” defects, on inheritance and retaining such defects in daughter cells which results in malignant neoplasms, on age-dependent impairment of human body’s function to eliminate such cells.The results: The model reproduces the well-known regularities of radiogenic cancer morbidity increase depending on instantaneous radiation exposure age and on attained age: the relative reduction at increased radiation age which the model attributes to age decrease of stem cells, relative reduction at increased time after radiation induced by “sorting out” of cells with “pre-cancer” defects, absolute increase with age proportional to natural cause mortality rate.The relevance of the developed quasi-biological model is displayed via comparison to the ICRP model for radiogenic increase of solid carcinomas’ morbidity after single radiation exposure. The latter model had been developed after Japanese cohort observations. For both genders high goodness-of-fit was achieved between the models at values of Gompertz’ law factor which had been defined for men and women in this cohort via selecting the value of the only free parameter indicating age-dependent exponential retardation of stem cells’ division.The conclusion: The proposed model suggests that the estimation of radiogenic risk inter-population transfer can be done on the basis of the data on age-dependent mortality intensity increase from all natural causes. The model also creates the premises for inter-species transfer of risk following the well-known parameters of cell populations’ kinetics in animal’s organs and tissues and Gompertz’s law parameters. This model is applicable also for analyses of age-dependent changes of background cancer morbidity.

To explain the known differences in the dose and age dependences of radiogenic mortality from leukemia and solid tumors after single exposure, a model was developed, which is a modification of the Kellerer-Rossi theory of dual radiation action. The model assumes formation in a cell of both single and double primary damages due to radiation and other carcinogens, while the recovery rate of single damages (φ) significantly exceeds that for double ones (ψ). Upon achieving a certain stage of the cell cycle (the critical age of cell – T), double damages become permanent and with probability of А can be inherited to daughter cells as “premalignant” defects. In contrast, in the Kellerer-Rossi theory, permanent damage is formed immediately after formation of the second damage at the next energy absorption event in the cell, i.e. ψ=0 .On the assumption that the premalignant defects only occur based on the double primary damages, i.e. φ>>ψ, the expressions for А were derived for the prompt radiation exposure and radiation exposure at a constant dose rate. They reproduce the effect increasing with decreasing of T, whereas the influence of T on the linear term of the dose expression in both cases is the same, but with decreasing of T the quadratic term increases faster for exposure at a constant dose rate than that for the prompt one. Thus, presence of the quadratic term in the dose expression for leukemia and its virtual complete absence for solid tumors may be due to lower T-value for hemopoietic stem cells. Predicted by the model dose rate influence on the quadratic term does not depend on the dose, so the reduction factor should be only applied to the quadratic term of the dose expression. This follows as well from the original version of the Kellerer-Rossi theory.

The purpose of the work was to obtain data about the level of population radon exposure on the surveyed settlements.Methods. Surveys were carried out by the integral track method with the use of the track chambers REI-4 from the kit TRACK-REI-1M. Were surveyed dwelling, schools, kindergartens and business premises. Duration of the each exposure was 2-4 months. The measured value was radon volume activity, then effective equilibrium radon concentration (EEC) was calculated using the values of the equilibrium coefficient F=0,5. Effective dose from radon was calculated using a dose coefficient 9•10-6mSv/(hour•Bq/m3). Describe theorganizational aspects of the surveys are described.Results. Survey of the premises to radon were conducted in the settlements of 26 administrative units for several seasons in 2008–2013. The surveyed settlements are cities with multi-storey or mixed buildings sites. The number of inspected premises in the settlement in one measurement period typically ranged from 100 to 200. Most premises were surveyed at least for two seasons (warm and cold). The total number of measurements is about 5300. The summarized results for all settlements were obtained: intervals and average values of the radon EEC, doses fromradon, the proportions of premises with EEC less than 100, 200 and 400 and more than 400 Bq/m3. The calculatedannual doses to the population from radon in a number of settlements are presented. Conclusion.Summarized information about the exposure of the population to radon are obtained. It is shown that «winter» radon EEC values not always exceeds summer values. For part of the settlements we can see even opposite picture. Criteria for assessing the relevance of the «radon situation» in the settlement are proposed. Based on the results of performed surveys the settlements ranked using this criterion.

A mathematical model for radiogenic increasing of mortality was proposed, taking into account spontaneous background damages of the genetic material, that always occur in cells due to the influence of non-radiation internal and environmental factors. The model is based on the representation of indistinguishability between radiogenic andspontaneous cancers and on the postulates of the Kellerer-Rossi dual action theory. It was proposed that duringformation of premalignant damages dual interactions occur both between primary radiation damages, and betweenradiation and spontaneous primary damages (hybrid interactions). The role of the latter is particularly important at low levels exposure that corresponds to a linear dependence of cancer incidence on dose. Their significance is indicated by the following factor: at the adopted value of the nominal (radiation) risk factor (0,05 Sv-1) and cancer mortality share among the population (0,15–0,2), the contribution of non-radiative carcinogenic factors for the total life is equivalent to radiation dose of 3–4 Sv or radiation at a constant dose rate of 40–50 mSv / year.The model assumes formation in DNA of both spaced apart (single) damages with high probability of recovery, and nearby (double) damages, which are more likely to interact, entering into the permanent state. Permanent damages being formed in certain portions of DNA can be inherited to daughter cells as premalignant defects. The relative role of spontaneous primary damages is greater the more single damages are formed as compared to double ones within the area of potential interaction.It was shown within this model that the presence of background cancer mortality for initial and finite population in the used by ICRP expression for interpopulation risk transfer has logical and biophysical justifications. Accounting of spontaneous primary damages and hybrid interactions enhances the capabilities for development of radiation risk models.

In this paper, we calculated the nominal value of the Russian population risk coefficient using an algorithm in which the ICRP calculations conducted for the "composite" population. Increasing the intensity of mortality after irradiation used the same as the ICRP. Background intensity of all-cause mortality and intensity of mortality from cancers of different localization for the Russian population took from the WHO data for 2008. In this paper цas obtained a factor of about 1.5 times greater than that calculated for a "composite" of the population in the same approximations.