| Summary: | Objective of the study: To conduct a comprehensive analysis and assessment of the dynamics of internal exposure levels in the territories contaminated due to the activities of the Mayak Production Association, based upon the results of long-term monitoring of the long-lived anthropogenic radionuclide body burden in residents of the Urals region. Materials and methods: The data of postmortem and in vivo examinations for three groups of population were analyzed: 1) residents of riverside villages of the upper and middle reaches of the Techa River, contaminated in 1949-1956 with liquid radioactive waste; 2) people who were exposed as a result of the 1957 accident on the territory of the East Urals Radioactive Trace; 3) residents of the Ozyorsk city, located at an 8 km distance from the enterprise. The following methods of the examinations were used: 1) radiochemical analysis of specimens of organs and tissues sampled at autopsy; 2) in vivo measurements with the use of the whole body counters. The results of measurements of cesium-137, strontium-90 and trans-uranium radionuclide body burden over the period 1950s – present are provided. Data analysis made it possible to distinguish two historically formed groups of population with the maximum levels of current strontium-90 and plutonium body burden. The first group included people who lived in the early 1950’s in the basin of the Techa River, for whom the levels of oral intake of 90Sr reached 1.4 MBq/year. The second group comprised residents of the Ozyorsk city, for whom the levels of inhalation intake of plutonium in the period 1951–1958 reached 8 Bq/year. Conclusion: Estimates of the committed effective doses due to the intake of long-lived radionuclides over the period from 1949 through 2012 for critical groups of residents of the Urals were: 300 mSv for former residents of the Muslyumovo settlement on the Techa River (90Sr contribution – 85%) and 13 mSv for residents of the Ozyorsk city (the contribution of trans-uranium radionuclides is 30%).
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