Determination of the actual term of relocation of representatives of the Ural cohort of accidentally irradiated population from radioactively contaminated territories

The main effective radiation protection measures, in addition to decontamination measures and limiting the consumption of food products of local origin, include the evacuation and resettlement of residents. Nevertheless, forced changes in usual habitat of residents can have a negative impact on the quality of their life. The study of the impact of radiation and non-radiation factors on the health of the exposed population requires classifying for the studied cohort by the criterion of forced relocation (relocation due to implementation of radiation protection measure). However, the quality of retrospective information and the specifics of the implementation of this action do not always unambiguously allow to determine the moment of time when displacement of residents from radioactively contaminated territories actually began. The purpose of this study is to determine the actual term of relocation of settlements whose residents are included in the Ural cohort of accidentally irradiated population. Materials and methods: The main source of in-formation in this study was the medical-dosimetric database on exposed residents of radioactively contaminated territories due to two situations: discharges of liquid radioactive waste from a chemical plant in the late 1940s and early 1950s into the Techa River and the 1957 radiation accident at the same plant. The study cohort numbered approximately 63,000 people. Establishing criteria for forced relocation has been carried out using methods of demographic analysis of the collected data, and time frames of relocation has been determined using historical materials. Results and Discussion: The migration activity of residents between 1950 and 1960 has been studied for the two radiation situations. The net migration rate per year has been determined as a basic criterion (minus 100 ‰ for relatively large- and medium-sized settlements, minus 150 ‰ for small ones). The year of the beginning of the forced resettlement of residents and the year of the end of the resettlement have been determined for each resettled settlement. Conclusion: The study of migration processes allowed to define the criterion for forced relocation and determine actual time frames for the implementation of the protective action in relation to members of the cohort.