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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

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.

In the 1950s, the Mayak nuclear weapons facility in Russia discharged liquid radioactive wastes into the Techa River causing exposure of riverside residents to protracted low-to-moderate doses of radiation. Almost 10,000 women received estimated doses to the stomach of up to 0.47 Gray (Gy) (mean dose=0.04 Gy) from external gamma-exposure and (137)Cs incorporation. We have been following this population for cancer incidence and mortality and as in the general Russian population, we found a significant temporal trend of breast cancer incidence. A significant linear radiation dose-response relationship was observed (P=0.01) with an estimated excess relative risk per Gray (ERR/Gy) of 5.00 (95% confidence interval (CI), 0.80, 12.76). We estimated that approximately 12% of the 109 observed cases could be attributed to radiation.