Kyshtym Accident Research Articles

Risk of death from hematological malignancies in the South Urals Population Exposed to Radiation cohort

The results of studies of long-term effects of population exposure in the South Urals in the 1950s were based for a long time on studies of the effects of exposure in the Techa River cohort and later in the East Urals Radioactive Trace cohort. After the creation of the South Urals Population Exposed to Radiation cohort, combining all persons exposed in the South Urals in the period from January 1, 1950, to December 31, 1960 the size of the cohort doubled, follow-up period reached 71 years, and the number of person-years at risk increased to 1,964,333. The average dose to red bone marrow for all cohort members was 231mGy. Regression analysis using a simple parametric excess relative risk model was performed using the EPICURE statistical package. The analysis resulted in confirmation of a statistically significant (p <0.001) linear doseresponse relationship of mortality for all hemoblastoses, and leukemia. The excess relative risk and 95% confidence intervals of death at 2-year latency period from all hemoblastoses were 0.71/Gy (0.28;1.31); from all leukemias - 1.28/Gy (0.55-2.39) and from leukemias excluding chronic lymphocytic leukemia -1.52/Gy (0.64-2.94). The quadratic model also significantly described the dose dependence; (the differences between the models were not significant). Increasing the follow-up period to 71 years resulted in a slight decrease in risk estimates. The width of the confidence intervals of the risk estimates decreased by more than a factor of 3 compared to earlier studies in the Techa River cohort, which indicates a decrease in uncertainties of risk estimates. Increasing the size of the cohort made it possible to obtain significant risk values for individual population groups (by sex, age, etc.). Analysis of risk values modification did not reveal significant differences in dose dependence on the studied factors, including attained age and age at exposure. The study will be continued to investigate in more detail the influence of time-dependent factors on dose dependence, as well as to assess the risk of death from different cellular forms of leukemia.

Cancer mortality risk in the Urals Cohort of Exposed Population Offspring

The objective of the study is to analyze solid cancer mortality and estimate the risk value of solid cancer mortality in the offspring of parents irradiated in the Southern Urals, depending on the dose to the parents' gonads as well as to conduct a preliminary assessment of the mortality risk from cancer of individual locations depending on the gonadal dose. The issue of the transgenerational effects of the human gonad exposure is still very important. There exists conclusive evidence of the presence of such effects in experimental animals. However, there is no proof of the existence of these effects in humans despite a great number of research on this subject. International scientific community and international organizations, UNSCEAR and ICRP being among them, regard this issue as the one that has not been solved yet and requires further studies. Urals Cohort of offspring of the population exposed on the Techa River and on the territory of the East Ural radioactive trace was established in the Urals research Center for Radiation medicine in 2022. The key feature of the cohort is the exclusion of the offspring with postnatal exposure. The size of the cohort as of September 2023 is 31,154 persons. The number of person-years over the whole follow-up period from 1950 through 2020 is 1 226 380. Mean dose to the gonads of mothers of all the cohort members is 41 mGy, to those of the fathers' — 35 mGy, mean combined gonad dose is 76 mGy. Over the whole follow-up period 3,774 deaths from all causes including 284 deaths from solid cancers were registered in the cohort. The mean age of the cohort members at the end of the follow-up period was 42 years. The risk of death was analyzed using Poisson regression by the programs of the EPICURE statistical software package. Three models of dose dependence were tested: linear, quadratic, and linear-quadratic models of paternal gonadal dose, maternal gonadal dose, and total gonadal dose. Mortality risk analysis of all solid cancers in the offspring cohort showed no statistically significant effect with parental gonadal dose (we have obtained positive although statistically insignificant values of solid cancers mortality risk) which is consistent with the results of other studies in human populations. At the same time, the analysis for the first time obtained a statistically significant linear dependence of the solid cancer mortality risk in offspring with father's age over 45 years depending on the dose to the father's gonads. The excess relative risk of death was 8.09/Gy, (0.51-22.93), p < 0.05. Also, for the first time, evidence of dose dependence of the mortality risk of lung cancer in male offspring on maternal gonadal dose, paternal gonadal dose, and combined gonadal dose was obtained. The values of excess relative risk of lung cancer and 95% confidence intervals according to the linear model were 5.39/Gy (0.46; 15.56) from paternal gonad dose, 4.36/Gy (0.15; 13.48) from maternal gonad dose, and - 3.95/Gy (0.55; 12.14) from combined gonad dose. Point risk estimates of lung cancer at this stage are characterized by wide confidence intervals and require additional studies to assess the influence of possible effect modifiers, but with a high degree of probability indicate the presence of dose dependence of this effect. Increasing the follow-up period and attained age, will increase the number of cancers in the future and will reduce dose response uncertainties and provide more accurate estimates of the risk of death in the offspring cohort.

Indication of radioactive contamination of forest ecosystems in the zone of the east Ural radioactive trace using methods of quantitative wood anatomy

The anatomical structure of the annual rings of Scots pine, formed before and after the Kyshtym accident, is analyzed. In trees growing closer to the central axis of the East Ural radioactive trace (EURT), a decrease in the number of cells in the annual ring, as well as a decrease in the diameter of the lumens and the thickness of the cell walls, was noted. It is assumed that radiation-induced damage to the photo-assimilation apparatus of trees led to disturbances in physiological processes that were reflected in the anatomical structure of wood.

The risk of developing cancer of the digestive organs (excluding intestines) in the South Urals Population Exposed to Radiation Cohort

Evaluation of the low dose effect on population health is still a relevant issue. It requires further studies to improve our understanding of these effects. To solve this problem, it is important to conduct studies of the late effects of radiation exposure with direct risk estimation in the population that combines all strata of the society: people of different sex, age, initial health status, social and economic status. Moreover, this population should be sizeable and has been followed up for a long-term period. This manuscript is the first to present the findings of the analysis of the incidence risk of cancer of all the digestive organs, excluding intestines, and stomach cancer taken separately in members of the Southern Urals Population Exposed to Radiation Cohort depending on the dose accumulated in the stomach over the period from 1956 through 2018. This cohort is comprised of individuals exposed in the Southern Urals in two radiation accidents (on the Techa River and in the East-Urals Radioactive Trace) over the period from 01.01.1950 through 31.12.1960. The cohort also includes those who were born during this period; they could have additional in utero exposure or have exposed parents. The population was affected by long-term combined exposure (external and internal) at the low-to-medium soft tissue dose range (up to 1.1 Gy). The size of the incidence cohort was 47,282 people. Over the follow-up period 01.01.1956-31.12.2018, the number of person-years made up 1 292 930; mean dose to the stomach was 47 mGy, maximum – 1,132 mGy. Excess relative risk of the cancer incidence of the digestive organs was assessed using the Poisson regression analysis. Calculations were performed using the EPICURE Statistical software package. Excess relative risk for stomach cancer with a 2-year minimal, was 0.98/Gy (р=0.026), for all cancers of the digestive organs, excluding intestines, – 0.58/Gy, р=0.06. There was no significant modification of the effect by non-radiation factors. These values of excess relative risk do not disagree with the results of similar studies in the Japanese cohort of the atomic bomb survivors who were compatible in terms of age but had acute exposure at higher doses. No significant dose dependence of the cancer incidence of the oral cavity, esophagus, liver, or pancreas was detected at this stage.

Indication of Radioactive Contamination of Forest Ecosystems in the Zone of the East Ural Radioactive Trace Using Methods of Quantitative Wood Anatomy

Indication of Radioactive Contamination of Forest Ecosystems in the Zone of the East Ural Radioactive Trace Using Methods of Quantitative Wood Anatomy

Investigation of biological-rhythm patterns: physiological and biochemical effects in herbaceous plants exposed to low-level chronic radiation – part 1: nonirradiated seeds

Hypothesis Because reactive oxygen species are involved in the regulation of biological rhythms, we hypothesized that intra-annual variability of seed progeny quality at low doses of ionizing radiation (LDIRs) would differ from that of background plants. Materials and methods We conducted 12 consecutive experiments using the roll culture method by germinating seeds (monthly for 3 weeks) of six herbaceous plant species (Bromus inermis, Geum aleppicum, Plantago major, Rumex confertus, Silene latifolia, and Taraxacum officinale) growing under conditions of chronic radiation in the East Ural Radioactive Trace (EURT). We assessed physiological (seed viability and abnormality frequency) and biochemical (low-molecular-weight antioxidants, LMWAs) parameters of seedlings. Results Total absorbed dose rates of maternal plants (TADRplants) and seed embryos (TADRseeds) in the EURT exceeded background levels by 1–3 and 1–2 orders of magnitude, respectively. Nonlinear dependencies on TADR were mainly characteristic of physiological and biochemical parameters. For most populations of the studied species (B. inermis, G. aleppicum, R. confertus, and S. latifolia), seedling survival and root length decreased in the autumn–winter period, while the frequency of abnormal seedlings increased. The content of LMWAs could be ranked as R. confertus > B. inermis > G. aleppicum > S. latifolia, in good agreement with the presence of anthocyanin pigmentation in the plants. The lowest synthesis of antioxidants in seedlings was observed in winter. A high LMWA content promoted growth and reduced the frequency of abnormal seedlings. Conclusions These results underscore a multistage nature of the impact of LDIRs on intra-annual biological rhythms in plants. High heterogeneity in reference group ‘wild grasses’ and diversity of their radiobiological effects should help to develop methods of radiation protection for natural ecosystems and facilitate approaches used by the International Commission on Radiological Protection. Highlights Absorbed dose rates for six plant species in the East Ural Radioactive Trace (EURT) area range from 0.11 to 73.89 µGy h−s (plants) and 0.11 to 6.88 µGy h−s (seed embryos). Intra-annual rhythms of physiological and biochemical parameters in the EURT zone differ from those in background seedlings. Plants in the EURT area exhibit a wide range of trait variability, asynchrony of the manifestation of the effects, nonlinear dose–response relations, and hormesis. A high content of low-molecular-weight antioxidants (LMWAs) is associated with low frequency of developmental abnormalities and high viability of seed progeny.

Исследование факторов риска развития катаракты нерадиационной природы у лиц, подвергшихся хроническому радиационному воздействию

Relevance. Epidemiological data have revealed a significant association between exposure to ionizing radiation, loss of lens optical function, and cataract formation. Cataract is a multifactorial disease that is traditionally associated with age, exposure to ultraviolet radiation, diabetes, smoking, alcohol abuse, obesity, steroid hormones, hypertension, etc. The chronic nature of the effects of radiation on the body, including both cell damage and regenerative processes, complicates the issue of assessment of the nature and magnitude of the dose-dependence of effects. Purpose. To investigate the potential risk factors of cataract development in different morphological layers, depending on social conditions and several diseases (non-radiation factors) in the population affected by two radiation accidents (dumping of radioactive waste into the Techa River and the East Ural Radioactive Trace) in the Southern Urals. Material and methods. The data from an in-depth examination of patients by an ophthalmologist in the Clinical Department of the URCRM were analyzed. The study involved 1377 patients. The «case» and «control» groups, comparable in sex and age, were selected from the general population. The impact of each factor was assessed on the basis of the Odds Ratio (OR) indicator. Risk factors associated with the development of cataracts in different layers of the lens included arterial hypertension, body mass index, age at the onset of exposure, level of education, alcohol consumption, smoking, ethnicity. Results. An increased risk of developing cataracts in the lens nucleus (1st sample: OR=0.54 (1st sample: 95% CI: 0.34–0.86; 2nd sample: OR=0.51 (95% CI: 0.32–0.82) (p<0.05)) and the intensity of its color (1st sample: OR=0.48 (95% CI: 0.29–0.80); 2nd sample: OR=0.56 (95% CI: 0.34–0.94) (p<0.05)) was established in persons who were at the age over 6 at the onset of exposure. Conclusion. The analysis did not reveal a statistically significant relationship of changes in the cortical layers, the nucleus and the posterior capsule of the lens with other studied risk factors in persons exposed to chronic radiation at a low to medium dose range. There was an increased risk of cataract development in the lens nucleus and the intensity of its color in persons who began to be exposed at the age of over 6 years. Key words: risk factors, cortical cataract, nuclear cataract, posterior subcapsular cataract, chronic exposure

90Sr in the Skeleton of Rodents from the Zone of the East Ural Radioactive Trace: Inter- and Intraspecific Features of Accumulation

90Sr in the Skeleton of Rodents from the Zone of the East Ural Radioactive Trace: Inter- and Intraspecific Features of Accumulation

Дальние перемещения мелких млекопитающих в осенне-зимний период

First time in the East Urals radioactive trace zone (EURT) (Chelyabinsk region, Southern Urals) small mammals from natural population with rhodamine B (RB) label, received in last year were revealed. The aim of this study was to estimate long-distance movements (LDM) of small mammals during the autumn–winter season by method of group marking with bait containing RB. One-time ingestion of bait with RB ensures systemic marking, which fixed in keratin-containing structures (hairs, claws, vibrissae). Retention time of RB-label for wood mouse (Sylvaemus uralensis Pallas, 1811) was 338 days, for common shrew (Sorex araneus Linnaeus, 1758) – 312 days, for red-backed vole (Myodes rutilus Pallas, 1779) – 251 days. It has allowed for the first time to estimate LDM of wintering individuals during autumn–winter season from EURT zone to adjacent territories and vice versa. It was found that S. uralensis are able to settle within 10800 m, M. rutilus – 9500 m, S. araneus – 9300 m. These data are the maximum recorded distance for these species. There is a predominance of females both among wintering settled animals and distant migrants. Probably LDM of females is evolutionary more favorable to population as they serve as the potential reserve of a genetic variety. LDM provides spatial and functional connectivity of mouse-sized mammal’s populations and possibility of genetic information exchange between population groupings on both the impact and background territories. The technique of group marking with bait containing RB has shown the efficiency at research of spatial structure of small mammals during the autumn-winter period. It is advisable to include it in monitoring system in areas of local technogenic pollution as well as to use it to calibrate samples of animals in the study of remote effects of radiating and other toxic effects.

Dose estimates and their uncertainties for use in epidemiological studies of radiation-exposed populations in the Russian Southern Urals.

Many residents of the Russian Southern Urals were exposed to radioactive environmental pollution created by the operations of the Mayak Production Association in the mid- 20th century. There were two major releases: the discharge of about 1x1017 Bq of liquid waste into the Techa River between 1949 and 1959; and the atmospheric release of 7.4 * 1016 Bq as a result an explosion in the radioactive waste-storage facility in 1957. The releases into the Techa River resulted in the exposure of more than 30,000 people who lived in riverside villages between 1950 and 1961. The 1957 accident contaminated a larger area with the highest exposure levels in an area that is called the East Urals Radioactive Trace (EURT). Current epidemiologic studies of the exposed populations are based on dose estimates obtained using a Monte-Carlo dosimetry system (TRDS-2016MC) that provides multiple realizations of the annual doses for each cohort member. These dose realizations provide a central estimate of the individual dose and information on the uncertainty of these dose estimates. In addition, the correlation of individual annual doses over realizations provides important information on shared uncertainties that can be used to assess the impact of shared dose uncertainties on risk estimate uncertainty.This paper considers dose uncertainties in the TRDS-2016MC. Individual doses from external and internal radiation sources were reconstructed for 48,036 people based on environmental contamination patterns, residential histories, individual 90Sr body-burden measurements and dietary intakes. Dietary intake of 90Sr resulted in doses accumulated in active bone marrow (or simply, marrow) that were an order of magnitude greater than those in soft tissues. About 84% of the marrow dose and 50% of the stomach dose was associated with internal exposures. The lognormal distribution is well-fitted to the individual dose realizations, which, therefore, could be expressed and easily operated in terms of geometric mean (GM) and geometric standard deviation (GSD). Cohort average GM for marrow and stomach cumulative doses are 0.21 and 0.03 Gy, respectively. Cohort average dose uncertainties in terms of GSD are as follows: for marrow it is 2.93 (90%CI: 2.02-4.34); for stomach and the other non-calcified tissues it is 2.32 (90% CI: 1.78-2.9).

Multiannual Assessment of Quality of Plantago major L. Seed Progeny from Kyshtym Radiation Accident Area: Weather-Dependent Effects.

The effects of low-dose radiation that are observed in plant populations in radioactively contaminated areas are variable. One of the reasons is the influence of fluctuating weather conditions and the interaction of radiation with weather factors. This article summarizes results of 12-year research on the viability and radioresistance of greater plantain (Plantago major L.) seed progeny growing in the East Ural Radioactive Trace (EURT) zone and in control (nonradioactive) areas, with consideration of weather conditions' variability. The EURT was formed by the Kyshtym accident, which occurred in 1957 at the Mayak Production Association. Absorbed dose rates of P. major parental plants in the pollution gradient were 14.5-165.9 μGy h-1, which correspond to a low-dose range. Seed progeny quality was evaluated as seed weight, the survival rate, and root length of 21-day seedlings. Interannual variability in the studied parameters was high, and their ranges overlapped between EURT groups of seeds and control groups in most cases. The number of significant correlations between the parameters of seed quality and weather conditions was higher in EURT groups than in control populations. In the control groups of seeds, 88.9% of correlations were negative, whereas in the EURT groups, 78.5% were positive.

Solid cancer mortality risk in the Southern Urals populations exposed to radiation cohort: 1950-2019

The objective of the study is to obtain direct risk estimates of solid cancer mortality for members of the Southern Urals Populations Exposed to Radiation Cohort. Materials and methods: the cohort was first created in 2018 and combines all the residents of the Southern Urals exposed to radiation in the territory of the Techa River and East Urals Radioactive Trace. Combining individuals exposed in the two radiation accidents increased the number of cohort members to 62.5 thousand people, the number of solid cancer cases included in the analysis to 4,511 and the number of person-years at risk to 1.956 million with the maximum follow-up period up to 70 years. The analysis was conducted with the use of regression analysis and a simple parametric model for excess relative risk. Maximum likelihood method was used to calculate 95% confidence intervals. Stomach dose was taken as an analogue of the dose to soft tissues accumulated over the entire follow-up period, and calculated using the updated Dosimetry System-2016 in the Urals Research Center for Radiation Medicine. Results: the analysis revealed a statistically significant linear dependence of solid cancer mortality rates on the dose, which confirms and clarifies the conclusions of previous studies. Solid cancer mortality ERR was 0.078/100 mGy. The increase of the statistical power of the analysis due to the increase of the cohort size and extension of the follow-up period enabled to obtain statistically significant ERR values for certain population groups by sex, ethnicity and other parameters. It refines the previously obtained values, reduces uncertainty and allows using the data to refine the radiation safety standards for the population exposed to radiation in various situations.

Hygienic assessment of 90Sr and 137Cs contamination of water and fish in the lakes of the head part of the peripheral zone of the East Ural radioactive trace

Introduction. The article presents the results of studies of the specific activity of 90Sr and 137Cs in the water and fish of the Irtyash and Kazhakul lakes located in the peripheral zone of the head of the East Ural Radioactive trace in 2014-2017.
 Materials and methods. Determination of the levels of specific 90Sr and 137Cs in the water and the body of the resource-forming species of Siberian roach (soroga, chebak) Rutilus rutilus lacustris (Linnaeus, 1758) from the studied lakes was carried out over the period of 2012–2017. The measurements were carried out using standardized methods adopted in in the Federal State Budgetary Institution of Health “Central Medical and Sanitary Unit No. 71 of the Federal Medical and Biological Agency of Russia” (FGBUZ TsMSCH No. 71 of the Federal Medical and Biological Agency of Russia) and the Southern Ural.
 Results. The research was carried out over 2014 to 2017. Since the accident at the Mayak enterprise in the fall of 1957, the specific radioactivity of the water in the studied lakes was found to decrease. The concentration of 90Sr in the water of Irtyash lake was 0.019±0.008, and 137Cs – 0.028±0.009, and in Lake Kazhakul – 0.19±0.06 and 0.14±0.06, respectively. These values are much lower than the level of intervention according to NRB-99/2009. 
 The water of the lakes is used to meet household needs. The water of Lake Irtyash is used for drinking water supply of the city of Ozersk. The specific activity of the raw mass of a roach carcass from the Irtyash and Kazhakul lakes for the accumulation of 90Sr is 2.7± 1.7 and 64.5±19 and 137Cs – 1.68± 0.8 and 38±33.5Bq/kg, respectively. All the samples studied separately according to 90Sr and 137Cs had levels of radioactive contamination at or below the regulatory compliance indicator (SanPiN 2.3.2.1078–01). At the same time, taking into account the absolute extended uncertainty (with a coverage factor of k = 2) roach from Kazhakul lake has a significant excess of the limit level of radioactive contamination.
 Limitations. Hydrochemical parameters of the aquatic environment in various reservoirs can vary significantly over time and affect the accumulation of radionuclides by hydrobionts. Therefore, the research results are relevant only for the research period. To obtain more reliable results, long-term comprehensive monitoring is necessary.
 Conclusion. Over the past 60 years after the accident at the Mayak enterprise in 1957, the levels of radioactive contamination of water and fish in the studied lakes Irtyash and Kozhakul have decreased by more than 10 times. Calculation of doses of ionizing radiation for certain groups of the population of areas contaminated as a result of accidents, living near lakes, is a complex task, for which additional research is needed.

Виртуальный образ экологической катастрофы (на примере Кыштымской аварии 1957 г.)

The article represents first results of the implementation of a scientific project dedicated to the problems of forming virtual images of some environmental processes taking place in the modern world. On the example of the Kyshtym accident in 1957 yr. authors analyze the main elements of the virtual image of one of the largest environmental disasters of the 20th century, show the dynamic and individualized nature of this image, note the high degree of its emotional perception by the youth (primarily student) audience. Also the article contains materials of a small sociological research of students of the South Ural State University in the spring of 2023, which studied the processes of forming the cultural memory of young people about the Kyshtym accident in 1957. The main conclusion of the research is that the most important component of the virtual image of the ecological catastrophe still is a visual range, however, as new information technologies develop, it may have «strong» competitors. From the point of view of the youth audience, today the strongest emotional impact on the consumer of the relevant content is provided by video materials, which include not only verbal information, but also musical accompaniment. To the number of elements of the image that create the most disturbing sensations from working with content dedicated to the Kyshtym accident in 1957 include: the radiation hazard sign, the Techa River, elements of a chemical protection suit, the word Chernobyl, a symbolic image of the explosion.

Анализ связи полиморфного локуса rs1052133 гена OGG1 с риском развития злокачественных новообразований у людей, подвергшихся радиационному воздействию

Genetic predisposition without doubt is one of the risk factors of cancer initiation. It is known that single nucleotide polymorphisms (SNP) of genes that maintain the genome stability, including SNP of DNA repair, may contribute to the initiation of carcinogenesis. Single-nucleotide polymorphisms of genes that support genome stability, including SNP of DNA repair genes, can contribute to cancer initiation. Polymorphism of the excision repair gene OGG1 causes interest of leading scientific groups from various countries. It is assumed that there is relationship between the rs1052133 polymorphism in the gene and predisposition to cancer initiation. The objective of this study was to establish association between rs1052133 polymorphism of base excision repair gene OGG1 and the risk of cancer initiation in people chronically exposed to ionizing radiation. Residents (888 people) of the Techa riverside settlements, chronically exposed to low or medium radiation from the Techa River and the East-Urals Radioactive Trace were included in the study. The study allowed researchers to establish that exposed to chronic radiation people, carriers of the rs1052133*G allele have increased risk of malignant neoplasms initiation: OR=1.38; 95% CI [1.05-1.83], p=0.023. The multifactorial synergistic interactions between the dose to the red bone marrow and the rs1052133 polymorphism of the OGG1 gene was found: Testing Balanced Accuracy (TBA)=0.56; Cross Validation Consistency (CVC)=10/10; p=0.01). The study found that the rs1052133 polymorphism may be considered as genetical marker of risk of cancer initiation in people, chronically exposed to radiation with doses ranged from 0.74 to 3507.07 mGy (average 523.10+/-33.89 mGy). It was found that the presence of the rs1052133*G in combination with radiation exposure can modify the risk of solid cancers initiation, as it is indicated by the synergistic relationship between the SNP and the radiation dose.

Migration of 90Sr in the Soils of the East Ural Radioactive Trace (EURT)

Migration of 90Sr in the Soils of the East Ural Radioactive Trace (EURT)

Stress memory in two generations of Plantago major from radioactive and chemical contaminated areas after the cessation of exposure

Hypothesis The differences in viability, root length, and pro/antioxidant features of Plantago major seedlings identified in seed progeny formed in areas of radioactive and chemical contamination can persist in subsequent generations after the elimination of the stress. Materials and methods The seed mixtures of F1 generation were collected from P. major natural populations (P plants) growing for a long time in the East Ural Radioactive Trace, the Karabash Copper Smelter zone, and background area. The seeds of F2 generation were obtained from F1 generation plants grown on experimental plots with ‘clean’ agricultural background; F3 generation was grown from F2 generation on the same plots. The viability of seed progeny was estimated by survival rate and root length. Pro/antioxidant features were determined spectrophotometrically by malondialdehyde content, superoxide dismutase and catalase activities, and total content of low molecular weight antioxidants in seedlings. Results and conclusions The hypothesis about the persistence of effects from chronic exposure to ionizing radiation and chemical contamination in the generations’ sequence of P. major after the removal of stress was confirmed only partially. The data obtained indicated that changes in the prooxidant and antioxidant features of plants in response to low doses of ionizing radiation can persist for at least in two generations after the stress removal. In the case of long-term exposure to chemical contaminants, we observed the persistence of the effect in a succession of generations only on the morphological indicator of root length.

Medical consequences of the Urals radiation accidents: Comparative analysis

• In 1957, liquid radioactive waste (LRW) was released into the Techa River and the explosion of the storage tank for LRW at the Mayak Production Association (Mayak PA) led to radioactive contamination and long-term public exposure of a part of the Urals region, Russia. • The countermeasures on the Techa River were insufficient and implemented with delay whereas those after the 1957 accident were immediate and more extensive. • 90 Sr-body burdens and exposure doses to red bone marrow in the residents of the Techa riverside settlements were significantly higher than those in the residents of the East Urals Radioactive Trace (EURT), and medical consequences were more severe despite the comparability of radioactivity emitted into environment. • Health damage of the Techa residents assessed by the criterion of collective effective dose was significantly higher than that of the EURT population, and it correlated with the registered early and late health effects. The paper provides comparative analysis of health effects after radioactive contamination of the Techa River and the 1957 radiation accident at the Mayak Production Association (Mayak PA) in terms of efficiency of performed protective measures. Both radiation accidents took place in the Urals Region, Russia, within a short period of time due to poor-quality of storage technology of liquid radioactive waste. Despite different pathways of radioactive contamination of the environment (air or water), similar long-term combined (external γ- and internal) exposure of the population took place. Countermeasures after the 1957 radiation accident included not only scheduled but also emergency evacuation of people. Scheduled activities on the Techa River were delayed and insufficient and resulted in exposure of local residents at doses greatly exceeding permissible levels. It also led to development of both early deterministic effects and increase in leukemia and solid cancer incidence, and mortality in the long-term period.

Overestimation of medical consequences of low-dose exposures to ionizing radiation

Overestimation of medical consequences of low-dose exposures to ionizing radiation contributes to the strangulation of nuclear energy production. Several examples of the overestimation are discussed here: the Chernobyl accident, East Urals Radioactive Trace and Semipalatinsk Nuclear Test Site. Results of certain studies of Chernobyl-related malignancies should be reassessed taking into account that some cases, classified as aggressive radiogenic cancers, were in fact late-stage malignancies. Associations of various markers with the tumor progression can become a field for future research and re-interpretation of data obtained in studies comparing malignancies from different regions. Reported correlations between low-dose exposures and non-malignant diseases call in question the cause-effect character of such correlations for cancer reported by the same and other researchers. The correlations may have been caused or influenced by bias, in particular, the dose-dependent selection and self-selection: individuals with higher dose estimates would be on average more motivated to undergo medical checkups and given more attention. Therefore, diagnostics tend to be more efficient in people with higher doses. Lifelong animal experiments are a promising approach to the research of dose-response relationships.

Accumulation of 90SR by Betula pendula within the East Ural Radioactive Trace zone

This study was conducted in 2010–2020 at the head of the East Ural Radioactive Trace (EURT), which was formed in 1957 as a result of the Kyshtym accident at the Mayak Production Association. The main contaminant in this zone is the long-lived radionuclide Strontium-90 (90Sr). Secondary forests dominated by silver birch (Betula pendula) occupy 45% of the EURT area. Concentration of 90Sr in birch leaves and small branches was higher than that in the trunks. The 90Sr content in birch sapwood varied slightly in the radial direction and did not depend on tree age. This was due to the dynamic equilibrium of the migration processes responsible for the accumulation and horizontal transfer of 90Sr. The 90Sr concentration increases in false heartwood, which is formed as a result of the secondary metabolism of dying parenchyma in the inner part of sapwood and is characterised by a high content of ash elements. The concentration of radionuclides in the aboveground organs of birch increased and the aggregated transfer factors (Tag) decreased with an increase in the soil contamination density, in accordance with the power function. The reasons for these patterns are also discussed.