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Every year, more and more data demonstrate that microRNA expression levels can be changed significantly after acute radiation exposure, and microRNAs themselves play an important role in the cellular response to ionizing radiation. However, regulation of microRNA expression after chronic radiation exposure within the low and middle dose range is poorly studied. In the present study, the expression of mature miR-29a, miR-30c, and miR-150 microRNAs in whole blood from 81 individuals in the long-term period after chronic low dose-rate radiation exposure was analyzed by real-time PCR method. The mean age of the studied people was 72 years, and the accumulated radiation doses in red bone marrow (RBM), thymus, and peripheral lymphoid organs ranged from 2.13 to 1867.55 mGy and from 0.18 to 488.79 mGy, respectively. More than 70 years after the onset of radiation exposure, a statistically significant dose-dependent decrease in miR-30c microRNA expression was found in exposed individuals in RBM, thymus, and peripheral lymphoid organs. [ABSTRACT FROM AUTHOR]

The data on the variability of aggregated transfer factors (Tag) of 90Sr in different species of woody plants growing in the area influenced by the Mayak Production Association are summarized. The radioecological situation in this territory is primarily determined by two events: the discharge of radioactive waste into the Techa River (1949−1951) and the Kyshtym accident (1957). The main causes of Tag variability are analyzed, including species-specific characteristics of plants, different soil moisture regimes, and the level of 90Sr contamination. The dependence of this radionuclide's Tag in trees on soil contamination density is described by a power function. In buffer zones and background areas the 90Sr Tag corresponds to the variability ranges established by the IAEA, while in more contaminated impact areas, the accumulation capacity in trees tends to decrease. [ABSTRACT FROM AUTHOR]

Chromosome aberrations are an example of the mutation process that happens at the chromosome level of DNA packaging. The occurrence of inversions and complex translocations has not been studied well enough due to the complexity of their detection using the conventional methods of differential staining. It is well-known that ionizing radiation is one of the factors that increases the frequency of chromosomal rearrangements. The objective of this pilot research was to study the frequency of inversions involving telomere regions of the chromosomes and complex translocations in T-cells of 25 chronically exposed residents of the Southern Urals. Inversions were studied in the group of 12 exposed individuals (one man, 11 women, exposure doses ranging from 0.001 to 2.9 Gy) using the Q-FISH method. Complex translocations were analyzed in the group of 13 people (nine women, four men, exposure dose ranging from 0.5 to 3.1 Gy) with the help of M-FISH method. The groups did not overlap. As a result of this analysis, it has been revealed that complex translocations occur six times less frequently than simple ones (р < 0.001). Chromatid variants of inversions predominated as compared to chromosomal ones (9 : 0.17 per 100 cells, p < 0.001). No dependence of the studied parameters on the exposure dose to red bone marrow was noted. [ABSTRACT FROM AUTHOR]

The study is aimed at the source-term reconstruction for the exposure of people to ionizing radiation who lived in 1949–1956 on the Techa riverside. It deals with the migration of γ-emitting nuclides (GENs), and specifically 95Zr and 95Nb, in the river system. It is known that 95Zr exhibits abnormally high sorption properties and is virtually completely and irreversibly sorbed onto bottom sediments (BSs) and suspended material already near the liquid radioactive waste (LRW) discharge site. Therefore, its further migration is possible only with the solid runoff. It was shown previously that the large-scale radioactive contamination of the river occurred in the relatively short period from July to October 1951, when the water flow rate in the upper section was varied from 8 to 30 m3/s. Under such water runoff conditions, the most contaminated BSs near the LRW discharge site undergo intense stirring-up (erosion), and the resulting suspensions are transferred with gradual sedimentation of the suspended material throughout the river stretch. After October 1951, when the LRW discharge into the river decreased by 2–3 orders of magnitude, the 95Zr distribution in BSs was determined only by the radioactive decay and transfer of suspended matters and saltation loads. Specific features of methods used in the 1950s for measuring the specific activity of the sum of β-emitting nuclides (BENs, AΣ, μCi/kg) and sum of GENs (МΣ, μg-equiv Ra/kg) are discussed. The use of the ratio RΣ = МΣ/АΣ as a criterion furnishes new information on the 95Zr activity concentration in BSs and allows picking out BS samples with prevalent contributions of 95Zr (МZr) и 95Nb (МNb) to МΣ from the whole set of the archive data. Analysis of the measured archive data on the specific activity of BS samples taken from different sections of the Techa River in 1952, 1954, and 1955 using the criterion RΣ = МΣ/АΣ allowed estimation of МΣ ≈ МZr + МNb and recalculation of these results taking into account the radioactive decay as of November 1, 1951. The results of MΣ measurements performed in 1952, 1954, and 1955 and converted to the level of November 1, 1951 appeared to be close, although the absolute activity level decreased by a factor of up to ~10 mln owing to radioactive decay. The 95Zr specific activity in the river BSs as of November 1951 remained virtually constant throughout the river stretch. These results provide a new approach to reconstruction of the external dose for the Techa riverside population. [ABSTRACT FROM AUTHOR]

The study is aimed at reconstruction of the parameters of the source from which the Techa River was contaminated in the period 1949–1956 and deals with the migration of γ-emitting nuclides (GENs), namely, of 95Zr and 95Nb, in the river system. The archive (1951) results of measuring the specific activity of the sum of β-emitting nuclides (BENs), AΣ (μCi/kg), in the soil and plants in the Techa riverside regions that are not flooded by floodwaters are analyzed. Analysis shows that the radioactive contamination of riverside territories is not associated with atmospheric discharges from the enterprise stacks and that the measurement results do not correspond to the commonly accepted views on the contamination distribution. In particular, contamination of the riverside soil and plants varied nonmonotonically with increasing distance from the river bank and along the river (spotty contamination pattern was observed), whereas the absolute values of BEN specific activities were constant throughout the territory within an order of magnitude. Furthermore, the depth distribution of BEN specific activities in soil up to 0.5 m was virtually uniform, and in some cases the activity increased with the depth. Finally, the plants had both external (on leaves) and internal (in roots) contamination, and in some cases the BEN specific activity in stems and leaves was lower than in roots. Presumably, the radioactive contamination of the soil and plants was determined by 95Nb and was due to entrainment of an aqueous aerosol from the river water surface with the wind. The model calculations explain all the unusual distribution patterns observed and allow estimation of the upper boundary of the mean (for summer 1951) 95Nb activity concentration in the river water. [ABSTRACT FROM AUTHOR]

The study is aimed at reconstructing the parameters of the source from which the people living in 1949–1956 on the banks of the Techa River were irradiated. It deals with the migration of γ-emitting nuclides (GENs) and specifically 95Nb in the river water. Some assumptions concerning the sources from which 95Nb got into the river water and its migration with the river flow were made previously. It was noted that the 95Nb sorbability is abnormally low and it is readily transported over long distances with the river water, whereas 95Zr, on the contrary, is efficiently taken up by bottom sediments already at the point of the liquid radioactive waste (LRW) discharge and can migrate only in the form of suspended material or bed load. It was noted that 95Nb could get into the river water both directly with the discharged LRW (external source) and via release from bottom sediments (BSs) after the 95Zr decay (internal source). It was assumed that, after October 1951 when the LRW discharge into the river was reduced by 2–3 orders of magnitude, the internal source became the main source of the 95Nb supply into the river water. This study additionally confirms the above assumptions. Archive results of daily measurements of the water specific activity in 1952 in the upper reaches of the Techa River are considered. The activity concentration of the sum of β-emitting nuclides (BENs), AΣ (μCi/L), was determined by measuring the β-particle count rate with an end-window counter, and that of the sum of γ-emitting nuclides (GENs), МΣ (μg-equiv Ra/L), by comparing the ionizing power of the test and reference (226Ra) sources. In determining the activity concentration of jth BEN, the β-radiation absorption coefficient in the layer of all the materials between the sample and the end-window counter, Kj, should be taken into account. Determination of the ratio Rj = Мj/Аj = mj/Kj, where mj is the gamma equivalent of jth GEN (μg-equiv Ra/μCi), was suggested for each jth GEN in the discharged LRW. Comparison of the experimental ratios RΣ = МΣ/АΣ with the corresponding calculated values, Rj = mj/Kj, furnishes new valuable information on the 95Nb concentration in the river water. In the first half of the year 1952, the 95Nb activity concentration in river water was more than 10 times higher than the AΣ values measured with an end-window counter (practically, the 95Nb activity was not detected). The main source of the 95Nb supply into the river flow was the release of recoil nuclei from the BS surface layer upon 95Zr decay (internal source). It decreased with time by an exponential law in accordance with the 95Zr half-life. The 95Nb activity concentrations in water at Metlino village and Nadyrov Most settlement (42 km downstream LRW discharge point) were virtually the same, confirming abnormally low sorbability of 95Nb. [ABSTRACT FROM AUTHOR]

In the 1950s, V-2 reservoir (Lake Kyzyl-Tash) was used for cooling industrial uranium–graphite reactors (IUGRs). When water passed through the IUGR core, activation radionuclides (ARs) were produced by nuclear reactions of reactor neutrons with nuclei of chemical elements present in water and were accumulated in water. The AR activity concentration in water from V-2 reservoir depends on the concentration of chemical elements in the reservoir. Data on the content of 16 elements in V-2 water in the period 1948–1956 were collected. These data were analyzed taking into account the characteristic natural abundance of elements in water of the Irtyash–Kasli lake system and the additional technogenic pollution of the reservoir in the course of its operation. The main source of AR transfer from V-2 reservoir to the Techa River was controlled water discharge through open shutters of the P-2 dam (or uncontrolled water seepage through closed shutters). A mathematical model was suggested, and the activity concentrations in V-2 water were calculated for 16 elements and 31 nuclear reactions yielding 20 ARs. The model was verified using the archive data on the activity concentrations of 32Р in V-2 water in 1953–1956. All the calculation results well agree with the available experimental data. The source term for AR transfer from V-2 reservoir to the Techa River in relation to the water flow rate through P-2 dam was determined. The experimental data on the scale of the distribution of the 32Р activity concentration along the Techa River were analyzed. The results obtained allow taking into account the AR contribution to the total radioactive pollution of the river and evaluating the possible radiation impact on the population and biota. [ABSTRACT FROM AUTHOR]

The paper is aimed at reconstruction of a source term for external exposure of population that inhabited the banks of the Techa River from 1949 to 1956. The composition of γ-emitting nuclides contributing to radiation environment of the river banks and floodplain is also studied. The γ-emitting nuclides entered the river system both in solutions and as industrial and natural suspended matter. The paper considers archive data on measured parameters of radiation contamination of the Techa bottom sediments and riverside area. Results of the present-day radiation surveys of the Techa River show that the distribution of the exposure dose rate has a pronounced spotted and non-monotonic character along the entire river stretch and is due to sedimentation of suspended particles contaminated with the γ-emitting nuclides on the soil surface. The activity of γ-emitting nuclides accumulated in the upper reaches of the river due to sorption of water-soluble radionuclides onto bottom sediments and to sedimentation of contaminated suspended matter on the surface of bottom sediments was calculated using a stationary sorption model and a hydrodynamic model of settling ponds. Until July 1951, when the river runoff did not exceed 1 m3/s, practically all industrial and natural suspended particles settled to and accumulated at the bottom of Metlinsky Pond. Only a small portion of clay particles could enter the river below the dam of Metlinsky Pond. 95Zr and 95Nb are of high importance for reconstruction of the radiation environment in the Techa riverside area, because before 1953 the activity of the bottom sediments in all segments of the river was predominantly determined by these γ-emitting nuclides. There is practically no sorption of 95Nb onto bottom sediments and suspended matter, and the river flow carries predominantly soluble 95Nb species. 95Zr, on the contrary, is strongly sorbed onto bottom sediments and can be transferred for long distances only as suspended matter or bed silt. Until October 1951, the radiation environment along the entire river stretch below Metlinsky Pond was contributed predominantly by 95Nb and was characterized by uniform and stable contamination level in all swampy areas of the floodplain. Vast contamination of the bottom sediments and the floodplain along the entire river stretch by other γ-emitting nuclides (95Zr, 137Cs, 141,144Ce, 103,106Ru, etc.) could result only from "washing" of Metlinsky Pond in October 1951, when the flow rate in the upper reaches of the river was up to 30 m3/s. This was accompanied by intensive stirring-up of the bottom sediments and activity transfer out of Metlinsky Pond. [ABSTRACT FROM AUTHOR]

The paper presents the key milestones and outcomes of 65-year studies of the carcinogenic consequences of accidental radiation exposure of the population of the Ural region. The radioactive contamination of the Techa River and the 1957 accident at the Mayak Production Association were the reasons of the long-term population exposure at a wide dose-range. The most important tasks of the study were the reconstruction of individual doses, follow-up of the solid cancer and leukemia incidence and mortality among cohort members. The research results have shown that chronic human exposure, in comparison to acute exposure, does not reduce the risk of developing malignant tumors and leukemias. The value of the dose-rate factor does not exceed ''one''.Thus, according to our data, the Publication 103 of the International Commission on Radiological Protection seemed to underestimate the radiation risk of malignant tumors and leukemias in case of low dose-rate exposure of the population by a factor of two. Prospects for further radio-epidemiological studies in the Urals are associated with the analysis of the cohort of Southern Urals Populations Exposed to Radiation, which includes about 63 thousand exposed people and makes it possible to assess the radiation risk of solid cancers of certain localizations, certain types of leukemia, and non-cancer effects.

The causes of the abnormally high mobility of 95Nb in Techa River water are discussed from the viewpoint of general niobium chemistry, specific features of its chemistry on the tracer concentration level, and mode of its supply into the system. [ABSTRACT FROM AUTHOR]

Objectives. To assess cognitive impairment in people accidentally exposed to radiation. Materials and methods. The study included individuals living in the Techa river basin, who are included in the "People" database of the Urals Research Center for Radiation Medicine, Federal Medical and Biological Agency of Russia. The study group included 38 people with soft tissue irradiation doses of ≥0.07 Gy and the control group consisted of 38 people selected by the matched pair case-control method who had been exposed to soft tissue doses not exceeding the background level. Clinical methods, assessment of cognitive evoked potentials (EP), clinical psychological methods, and statistical methods were used. Results. The study group showed a tendency towards an increase in the proportion of subjects with mild cognitive impairment (F06.7) and statistically significantly greater proportions of individuals with cognitive impairment syndrome (p = 0.039; OR = 2.9; 95% CI 1.2–7.5), dyssomnia syndrome (p = 0.022; OR = 2.6; 95% CI 1.04–6.6), and complaints of decreased memory for current events (p = 0.034; OR = 2.8; 95% CI 1, 1–7.5). This group showed statistically significant differences as compared with the control group in individual indicators of P300 latency (LP) (p = 0.009); this group also showed a statistically significantly greater proportion of individuals with LP increased by 3 sigma or more (p = 0.025; OR = 6.4, 95% CI 1.3–31.7). Conclusions. Cognitive impairments were more marked in the study group, this being apparent as an increase in the proportion of subjects with mild cognitive impairment (F06.7), cognitive decline syndrome, complaints of deterioration in cognitive functions, and lengthening of P300 LP. [ABSTRACT FROM AUTHOR]

The objective of the work was to study the prevalence of undifferentiated oligophrenia in the offspring of antenatally exposed parents. The analysis included 2,908 offspring of the Techa River antenatally exposed residents within Chelyabinsk Oblast born in the period 1974-1992. 1,705 of them were born to an antenatally exposed mother, 1,668 – to an antenatally exposed father, and 368 – to both antenatally exposed parents. Mean in-utero dose for the cohort of in-utero exposed population was 5.8 mGy, while the mean dose of mothers of oligophrenic persons was 12.6 mGy, and that of antenatally exposed fathers – 5.3 mGy. It was found that the prevalence of oligophrenia of different degrees of severity compared to the control group, which included the offspring of unexposed persons of the same age, ethnicity and living in adjacent territories, tends to increase More than 20% of cases of moderate oligophrenia in both main and control groups were of familial nature. All cases of severe oligophrenia in the compared groups were sporadic. There was an increase (p0.05. No dependence of the prevalence of oligophrenia on the maternal and paternal in-utero dose has been detected.

The objective of this work was to reveal the relations between thyroid pathology prevalence and absorbed thyroid radiation dose from 131I in the individuals relocated into Ozyorsk from the radioactively contaminated areas of South Urals. The sources of data for statistical analysis were the electronic database “Thyroid” containing clinical and laboratory data, and electronic database “The man and the environment” containing dosimetry information on irradiated individuals. Thyroid diseases and individual thyroid doses from all sources of ionizing radiation were collate for 195 persons relocated into Ozyorsk from the villages of the Techa riverside and of the territory of the East Ural Radioactive Trace. Statistical analysis of the data was performed using a software package (Excel, Statistica 6.1). The prevalence of thyroid nodules increased in relocated female statistically significantly 1.7 times (p=0.03) in the range of thyroid doses of 1000-1499 mGy and 2 times (p=0.003) in the range of doses of 1500–1999 mGy compared to this parameter at the doses below 1000 mGy. The prevalence of all thyroid abnormalities has been increased 1.5 times (p=0.007) in the range of thyroid doses of 1500-1999 mGy. An increased prevalence of thyroid diseases by 1.6 times (p=0.02) relative to non-irradiated persons was noted for relocated female whose age at the time of the medical examination was less than 60 years only. A significant number of risk factors requires the use the multivariate statistical analysis to assess their contribution for the development of thyroid pathology in the individuals residing in childhood in radioactively contaminated areas.

The cytokine network is an important integrative and regulatory mechanism of the immune, endocrine, and nervous systems. Disturbances of this mechanism could play a role in the development of long-term biological effects of ionizing radiation at the subcellular, cellular, and whole body levels. Changes in the immune system of chronically exposed people, including specific features of the cytokine profile, were noted decades after the onset of exposure and were more pronounced in prenatally exposed individuals. The aim of this study was to assess the concentrations of certain cytokines in the blood serum of chronically exposed residents of the riverside villages of the Techa River 65–68 years after the onset of radiation exposure and correlations of the revealed changes with the dose to red bone marrow (RBM) and certain nonradiation factors. 406 people from the Techa River cohort (main group) were examined. Mean cumulative dose estimated for RBM in this group was 950.4 mGy; the median age of the patients was 70.0 years. Mean cumulative dose to RBM for 149 unexposed people included in the comparison group was 23.5 mGy; the median age of patients in this group was 68.5 years. The groups did not have statistically significant differences in age, sex, ethnic composition, or socio-economic living conditions of the people. The concentrations of IL-1β, IL-1(RA), IL-2, IL-4, IL-6, IL-8, IL-10, TNFα, IFNα, and IFNγ in the blood serum were assessed using enzyme-linked immunosorbent assay. Chronically exposed individuals were revealed to have a statistically significant increase in the content of three proinflammatory cytokines: IL-8 (3.12 pg/mL, p = 0.010), TNFα (4.40 pg/mL, p = 0.010), and IFNγ (10.67 pg/mL, p = 0.040) relative to unexposed people (2.28, 3.61 and 8.34 pg/mL, respectively) and a decrease in the concentration of the main anti-inflammatory cytokines. Thus, the content of IL-4 in the main group was 1.14 pg/mL versus 3.48 pg/mL in the comparison group (p = 0.010), and the level of IL-10 was 6.18 pg/mL relative to 7.52 pg/mL in unexposed people (p = 0.010). The serum concentrations of IL-1β, IL-1α, IL-1(RA), IL-2, IL-6, CSF-GM, CSF-G, and IFNα did not differ in either group. The content of TNFα in the blood serum was weakly positively correlated with the individual cumulative dose of RBM exposure (SR = 0.14, p = 0.003). The concentrations of IL-4, IL-10, and IFNγ showed a weak negative correlation with the age of the examined people of the main group (SR = ‒0.19, p < 0.001; SR = –0.12, p = 0.020 and SR = –0.16, p = 0.002, respectively). In the comparison group, IL-4 correlated with age weakly negatively (SR = –0.30, p < 0.001), and IFNγ correlated with it weakly positively (SR = 0.18, p = 0.040). The level of IL-8 in the comparison group correlated weakly negatively with sex (SR = –0.18, p = 0.030); in the main group such a relationship was not found. Chronically exposed people were revealed to have proinflammatory changes in the serum cytokine profile with signs of an imbalance 65–68 years after the start of exposure. These changes did not depend (for most parameters) or depended little of the dose of RBM exposure (TNFα concentration) and the age (IL-4, IL-10, and IFNγ concentrations) of patients. [ABSTRACT FROM AUTHOR]

The results of mRNA expression of the GATA3, FOXP3, TBX21, STAT3, NFKB1, and MAPK8 transcription factors in peripheral blood cells of 264 residents of the Techa riverside villages of the Chelyabinsk and Kurgan regions, who were affected by chronic low dose-rate exposure in the 1950s, are shown. The range of individual doses to the red bone marrow due to external gamma exposure and 90Sr was 77.8–3507.1 mGy, and the mean dose was 706.3±46.3 mGy. It has been found that changes in the transcriptional response of the cell occur at the molecular level in the long term after chronic exposure. A modified expression of the immunoregulatory genes NFKB1 and MAPK8 in the peripheral blood cells of exposed people was found. A comparative analysis of the interaction of the studied mRNAs demonstrated the presence of a link between the MAPK8 and NFKB1 genes in the group of chronically exposed individuals. The results obtained may indicate the involvement of these transcription factors in the impairment of the immune response in the exposed population. [ABSTRACT FROM AUTHOR]

The paper presents the key milestones and outcomes of 65-year studies of the carcinogenic consequences of accidental radiation exposure of the population of the Urals region. The radioactive contamination of the Techa River and the 1957accident at the Mayak PA were the reasons for the long-term exposure of the population at a wide range of doses. The most important tasks of the study were the reconstruction of individual doses, follow-up of the health and life status of cohort members. The research results have shown that chronic human exposure, in comparison to acute exposure, does not reduce the risk of developing malignant tumors and leukemias, and the value of the dose-rate factor does not exceed “one”. Thus, according to our data, the current recommendations of the International Commission on Radiological Protection underestimate the radiation risk of malignant tumors and leukemias in case of chronic exposure of the population by a factor of two. Prospects for further radio-epidemiological studies in the Urals are associated with the analysis of the cohort of Southern Urals Populations Exposed to Radiation (SUPER), which includes about 63 thousand exposed people and makes it possible to assess the radiation risk of solid cancers of certain localizations, certain types of leukemia, and non-cancer effects.

Uncertainties of radiation risk of late radiation exposure effects in humans are to a great extent determined by completeness and quality of epidemiological data. The registry of the studied cohort is of fundamental importance for the cohort studies. Particular difficulties appear in the course of development of the exposed population offspring registry as these people in contrast to their parents were not affected by radiation exposure. The formation of the cohort of the exposed population offspring has its peculiarities and requires evaluation of its completeness and quality. The objective of this research is to study the value of the sex ratio as a possible criterion to assess the completeness and quality of the registry of the Techa River Cohort offspring. The register of descendants of the irradiated population at the end of 2019 included information on 25930 persons. The formation of the register of descendants of the population irradiated on the Techa River was started in the mid-1950s. At the same time, various documents were used to confirm the fact of birth of a child in irradiated persons. In the Techa River population the proportion of offspring with exposed mother and unexposed father is 22.2%, those with exposed father and unexposed mother made up 13.9%; the proportion of in utero exposed offspring is 44.6%. In accordance to the widely accepted published data it was to be expected that the number of male 1st-generation offspring in the cohort would be lower. However, the results of the conducted research show no changes in the sex ratio among offspring relative to the population-based control. Moreover, it was stated that the sex ratio in the population of the 1st-generation offspring of the exposed residents of the Techa River settlements should not be viewed as secondary. The assumption about the influence of the pre-conceptional exposure of the parents as well as that of the in utero exposure on changes in the sex ratio was not confirmed. It is shown that the decrease in the value of the sex ratio is associated with misreporting of the male 1st -generation offspring who died in childhood and at young age. The value of the sex ratio in groups formed based on the character and dose of exposure, depended mainly on the source of information used in the course of the offspring registry development.

The paper deals with the evaluation of the efficiency of the implemented protective measures in the event of accidental exposure of the Urals region population due to radioactive contamination of the Techa River and the 1957 accident. Both of the accidents occurred in one and the same region within approximately the same time frame, and were caused by discharges of Mayak Production Association radioactive waste into the Techa River (1949–1956) and into the atmosphere (1957). Counter-measures that had been undertaken to provide radiation safety of the population differed both in nature and in timeline. Their efficiency was insufficient in the Techa River basin as they were delayed in time and were not implemented to a full extent. But countermeasures in the East Urals Radioactive Trace were much more effective according to medical and dosimetric criteria. As a result, residents of the Techa riverside settlements received much higher organ doses, including doses to red bone marrow, and health effects of accidental exposure were registered in them both soon after and long after the radiation exposure.

The object of the study is the cohort of individuals exposed in the Southern Urals in the 1950s at the age of 0–19 years. The relevance of the creation of the cohort of individuals exposed in childhood and adolescence is determined by their high sensitivity to radiation exposure and is associated with the need for differentiated assessments of the radiation risk of morbidity and mortality for individuals exposed at different stages of ontogenesis. The work includes definition of the cohort, the criteria for inclusion and exclusion from the cohort. According to the data as of 01.01.2019, the created cohort includes 32,461 potential members exposed as a result of living in the riverside villages of the Techa River and on the territory of the East Ural radioactive trace; the follow-up period of the cohort is 70 years (from 1950 to 2019). The cohort has an almost equal number of men and women, includes two ethnic groups (Slavs and Turks), the age range is from 0 to 91 years. The formed cohort can be used to assess the radiogenic risk of cancer and non-cancer morbidity and mortality for the low and medium doses of exposure

One of the main clinical manifestations of radiation exposure in the early and later periods is headache. Until present time there is no clear understanding of the mechanisms of headache development under radiation exposure. The theories that exist (more than 30) do not give a comprehensive answer to these questions. Out of all primary headaches, tension headache is diagnosed more often. Emotional factors including psychological stress is the major cause of its development. In the current paper the findings of the in-depth clinical examination of 92 people are presented. Clinical characteristics of three groups that of exposed people with tension headache, unexposed people with tension headache, exposed people without tension headache are described. Nosological and clinical forms of headaches in exposed people are investigated, psychological (accentuation on personality traits, state anxiety, depression), psychophysiological characteristics of the examined people, and clinical manifestations of the tension headache are studied.

Evaluation of the frequency of chromosome translocations in peripheral blood T-lymphocytes is a generally accepted method of retrospective biodosimetry. Accidental contamination of the Techa River (Chelyabinsk Oblast) in 1950s with bone-seeking long-lived strontium-90 gave an opportunity to evaluate the effect of local red bone marrow (RBM) exposure on translocation formation in the peripheral T-lymphocytes of local inhabitants. The studies of the inhabitants using fluorescent in situ hybridization (FISH) showed that RBM doses calculated based on FISH results were lower than those estimated based on 90Sr body burden measurements. The current study presents analytical review of the published data dealing with the most important processes of the T-lymphocyte development and formation of chromosome aberrations: characteristics of the main compartments where the exposure of T-cell occurs; assessment of the time spent by T-lymphocytes and their progenitors in these compartments; analysis of the dynamics of T-cell populations (proliferation and death); age-related aspects. The paper presents a concept of T-cell Genus (TG) united all the progeny of T progenitor with inheritable specific aberrations that could have developed in bone marrow. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess main regularities of resettlement of the first generation offspring of the exposed Techa River population. In the given paper the information on places and periods of residence of the population exposed on the Techa River and their offspring, obtained from the medical-dosimetric database of the URCRM was used. Groups of the first generation offspring of exposed people living at various distances from the Techa River were identified. Main regularities of resettlement of a large group of offspring of the exposed Techa River population (26 300 persons) over the period 1950-2010 were revealed. Chelyabinsk Oblast is the main resettlement area of the first generation offspring of the exposed Techa River population. The proportion of offspring living outside of their primary resettlement area is gradually increasing. Offspring outflow from the Kurgan Oblast is greater than that from the Chelyabinsk Oblast. The main part (45.9%) of the first generation offspring of the exposed Techa River population alive as of 2010 was gathered in cities. Migration of the exposed population promoted increase in the number of marriages between exposed and unexposed persons, to the birth of offspring whose one parent (either mother or father) was exposed and led to decrease in the number of offspring whose both parents were exposed. In the current study for the first time peculiarities of resettlement of two generation of people residing on radioactively-contaminated territories, exposed people and their offspring, were compared. Marked differences in the nature of resettlement of the Techa River exposed population offspring relative to their parents were registered. Offspring migrated more frequently, which is expressed in the increase in their proportion in cities up to 45.9% as compared to that of exposed persons – 30.8% (p

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.

Application of two inorganic hexacyanoferrate sorbents (T-35 and NPF-HTD) for radiochemical analysis of 137Cs in various water samples was studied. The results of batch experiment for cesium sorption revealed that both sorbents are suitable for preconcentration of cesium at the pH range of 0.5–11. Column experiments revealed that the NPF-HTD sorbent provided significantly better cesium sorption than the T-35 sorbent due to better sorption kinetics. The sorbents were tested using 1 L of raw and acidified fresh water and seawater as well as 7.2 L water sample from Techa River (activity of 1.36 ± 0.21 Bq L−1 was found). 1.5 g of the NPF-HTD allowed for cesium recovery of 86–98.7% depending on type of water sample. [ABSTRACT FROM AUTHOR]

The article presents major results of the work performed by St. Petersburg Research Institute of Radiation Hygiene after Professor P. V. Ramzaev on public contracts signed within the implementation of the Federal targeted program “ Mitigation of the radiation accidents’ consequences for the period until 2015” ( Direction IV “ Streamlining of monitoring systems and their elements and situation forecasting on radioactively contaminated territories paragraph 14 “The analyses and comprehensive evaluation of radiation situation changes on radioactively contaminated territories “ aimed at compilation of radioactively contaminated zones’ settlements list and Direction VI “Awareness raising and social -psychological rehabilitation of radiation- affected residents”, paragraph 20 “Creation of unified informational system on ensuring population’s radiation safety and overcoming radiation accidents’ consequences via development of the federal and regional informational resources’ systems” and “ Joint activities program on mitigation of the Chernobyl disaster within the Union State for the period until 2016” ( Direction II “ Streamlining of unified radiation protection system in radioactively contaminated territories” paragraph 2.1 “ The harmonization of requirements, methods and technologies aimed at mitigation of Russian and Belorussian population’s internal and external exposure, the development of radiation control and monitoring unified system”, sub-paragraph 2.1.1 “The development of unified assessment and forecast system for population exposure doses and rationing of radionuclide – containing foodstuffs, agricultural products and forest preserves based on the international approaches” ) over the period from 2011 to 2015.

For revealing the main factors determining the frequency of radiation reactions and radiation complications in cancer patients previously exposed to chronic accidental exposure associated with the activity of the plant «Mayak», the data from medical records of 89 patients, treated with external beam radiotherapy from 1995 to 2011, and had reference to chronic radiation exposure history are analyzed. The assessment of peripheral blood, the nature and severity of radiation reactions and complications was performed. Statistical processing of the data revealed that the factors determining the frequency and severity of radiation reactions did not differ in features in cancer patients with chronic radiation exposure history. The value of absorbed dose has no significant effect on the frequency of radiation reactions.

A part of the Urals territory was contaminated with 90Sr and 137Cs in the 1950s as a result of accidents at the “Mayak” Production Association. The paper describes the analysis of in vivo 90Sr measurements in Urals residents. The measurements were performed with the use of Whole-Body Counter SICH-9.1M in 2006–2012. Totally 5840 measurements for 4876 persons were performed from 2006 to 2012; maximal measured value was 24 kBq. Earlier, similar measurements were performed with SICH-9.1 (1974–1997). Comparison of the results obtained with SICH-9.1 and SICH-9.1.M has shown a good agreement of the two data sets

The method of fluorescence in situ hybridization (FISH) applied to peripheral blood T lymphocytes is used for retrospective dose estimation, and the results obtained from the analysis of stable chromosomal aberrations are usually interpreted as a dose accumulated in the red bone marrow (RBM). However, after local internal exposure of the RBM, doses derived from FISH were found to be lower than those derived from direct measurements of radionuclides accumulated in the bodies of exposed persons. These results were obtained for people residing near the Techa River contaminated by Sr (beta-emitters) in 1949-1956 (Chelyabinsk Oblast, Russia). A new analysis has been performed of the combined results of FISH studies ( n = 178) undertaken during 1994-2012 for persons living on the Techa Riverside. Analysis confirms the lower slope of the translocation yield per Gy (8.0 ± 0.7 × 10) for Techa residents in comparison with FISH data for donors with external exposures (11.6 ± 1.6 × 10, Tawn et al., Radiat Res 184(3):296-303, 2015). It was suggested that some portion of T cells remained unexposed, because they represented the descendants of T cell progenitors, which had migrated to the thymus before the start of Sr intakes. To clarify this problem, the dynamics of T-cell Genera (TG), combining all descendants of specific T-cell progenitor reaching the thymus, was considered. Rates of TGs produced by RBM over different age periods of human life were estimated with the use of the mathematic model of T-cell homeostasis (Bains, Mathematical modeling of T-cell homeostasis. A thesis submitted for the degree of Doctor of Philosophy of the University College London. , 2010). The rate of TG loss during the lifetime was assumed to be very small in comparison with production rate. The recirculation of mature T lymphocytes in contaminated RBM was taken into account. According to our model estimates, at the time of blood sampling, the fraction of exposed T lymphocytes (whose progenitors were irradiated) ranged from 20 to 80% depending on the donors' age at the start of exposure to Sr. Dose to T lymphocytes, estimated from FISH studies, should be about 0.6-0.9 of RBM dose for residents of the upper Techa region and about 0.4-0.8 in the middle Techa region. Our results could explain the lower value of translocation yield per Gy obtained for Techa residents. The approaches for further model improvement and validation are discussed in this paper. [ABSTRACT FROM AUTHOR]

Waterborne radioactive releases into the Techa River from the Mayak Production Association in Russia during 1949-1956 resulted in significant doses to about 30,000 persons who lived in downstream settlements. The residents were exposed to internal and external radiation. Two methods for reconstruction of the external dose are considered in this paper, electron paramagnetic resonance (EPR) measurements of teeth, and fluorescence in situ hybridization (FISH) measurements of chromosome translocations in circulating lymphocytes. The main issue in the application of the EPR and FISH methods for reconstruction of the external dose for the Techa Riverside residents was strontium radioisotopes incorporated in teeth and bones that act as a source of confounding local exposures. In order to estimate and subtract doses from incorporated Sr, the EPR and FISH assays were supported by measurements of Sr-body burdens and estimates of Sr concentrations in dental tissues by the luminescence method. The resulting dose estimates derived from EPR to FISH measurements for residents of the upper Techa River were found to be consistent: The mean values vary from 510 to 550 mGy for the villages located close to the site of radioactive release to 130-160 mGy for the more distant villages. The upper bound of individual estimates for both methods is equal to 2.2-2.3 Gy. The EPR- and FISH-based dose estimates were compared with the doses calculated for the donors using the most recent Techa River Dosimetry System (TRDS). The TRDS external dose assessments are based on the data on contamination of the Techa River floodplain, simulation of air kerma above the contaminated soil, age-dependent lifestyles and individual residence histories. For correct comparison, TRDS-based doses were calculated from two sources: external exposure from the contaminated environment and internal exposure from Cs incorporated in donors' soft tissues. It is shown here that the TRDS-based absorbed doses in tooth enamel and muscle are in agreement with EPR- and FISH-based estimates within uncertainty bounds. Basically, this agreement between the estimates has confirmed the validity of external doses calculated with the TRDS. [ABSTRACT FROM AUTHOR]

The European Union's SOLO (Epidemiological Studies of Exposed Southern Urals Populations) project aims to improve understanding of cancer risks associated with chronic in utero radiation exposure. A comprehensive series of hybrid computational fetal phantoms was previously developed at the University of Florida in order to provide the SOLO project with the capability of computationally simulating and quantifying radiation exposures to individual fetal bones and soft tissue organs. To improve harmonization between the SOLO fetal biokinetic models and the computational phantoms, a subset of those phantoms was systematically modified to create a novel series of phantoms matching anatomical data representing Russian fetal biometry in the Southern Urals. Using previously established modeling techniques, eight computational Urals-based phantoms aged 8, 12, 18, 22, 26, 30, 34, and 38 weeks post-conception were constructed to match appropriate age-dependent femur lengths, biparietal diameters, individual bone masses and whole-body masses. Bone and soft tissue organ mass differences between the common ages of the subset of UF phantom series and the Urals-based phantom series illustrated the need for improved understanding of fetal bone densities as a critical parameter of computational phantom development. In anticipation for SOLO radiation dosimetry studies involving the developing fetus and pregnant female, the completed phantom series was successfully converted to a cuboidal voxel format easily interpreted by radiation transport software. [ABSTRACT FROM AUTHOR]

Objective of the research is to evaluate cognitive impairments in persons affected by accidental radiation exposure., Material and Methods: The study involved residents of the settlements located in the Techa River basin that are included into the database «Man» of the URCRM. The main group «case» consisted of 38 people with the dose to soft tissues ≥0.07 Gy. 38 people with the dose to soft tissues not exceeding the background level were selected using the matched pair case-control method («control»). The following methods were used: clinical method, method of evaluation of cognitive evoked potentials, clinical and psychological method, statistical methods., Results: In the group «case» the number of examined people with mild cognitive impairment (F06.7) to increase. There are statistically significantly more people with cognitive impairments ( p =0.039; OR=2.9; 95% CI: 1.2-7.5), dissomnic disorder ( p =0.022; OR=2.6; 95% CI: 1.04-6.6), complaints of difficulty remembering current events ( p =0.034; OR=2.8; 95% CI: 1.1-7.5). In this group statistically significant differences between the groups in terms of individual values of P300 latency ( p =0.009) are observed. The number of people with P300 latency increased by ≥3 Σ is also statistically significantly higher ( p =0.025; OR=6.4; 95% CI: 1.3-31.7) in this group., Conclusion: In the group «case»: cognitive impairments are more pronounced. It is manifested in the increase in the number of examined people with organic cognitive impairment, cognitive decline, complaints of deterioration of cognitive functions, prolongation of P300 latency.

The process of nuclear weapons production from 1949 to 1987 was accompanied by the generation of a great amount of radioactive waste. Waste processing operations and controls on discharges at this time were not to the same standard as today. Because of this, vast areas of the Urals region of Russia surrounding the Mayak Production Association (MPA) were exposed to routine and accidental radioactive contamination. The greatest contribution to the contamination was gas aerosol emissions from the MPA in the 1950s (total activity 38 PBq, mainly 131 I), releases of liquid radioactive waste into the Techa River from 1949 to 1956 (total activity 115 PBq, including long-lived 90 Sr and 137 Cs) and accidental atmospheric releases as a result of the thermochemical explosion of the storage tank for liquid radioactive waste in 1957 (74 PBq, relatively short-lived radionuclides being the main contributors). Protective measures helped to relieve the pressing problem of population safety in the 1950s and 1960s, but they led to the appearance of new sources of contamination in the territory surrounding the MPA-Lake Karachay (total activity of beta-emitters 4400 PBq) and the Techa Cascade of Reservoirs (TCR; total activity 8 PBq). Owing to natural radioactive decay and rehabilitation measures, the radiation situation in the East Urals Radioactive Trace (EURT) has improved considerably over the years. Economic activity has been partially restored in these territories. Only the most contaminated territory of the East Urals Radioactive Reserve cannot be used for any economic activities up to the present day. Marked non-uniformity of radioactive contamination of the EURT and the Techa River floodplain, as well as radionuclide washout from Lake Karachay and the TCR into the underground waters and the Techa River require on-going radioecological monitoring, management and regulatory supervision., (© 2021 Society for Radiological Protection. Published on behalf of SRP by IOP Publishing Limited. All rights reserved.)