Search

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 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 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