Assessment of radiation contamination of villages in northeastern Kazakhstan not covered by exposure rate measurements after atmospheric nuclear weapons tests conducted at the Semipalatinsk nuclear test site.

This paper presents the results of the first comprehensive assessment of radiation contamination of villages in Kazakhstan not covered by exposure rate measurements after atmospheric nuclear weapons tests conducted at the Semipalatinsk nuclear test site in 1949-1962. This was necessary to estimate radiation thyroid doses in 3183 individuals included in a cohort study of the prevalence of thyroid nodules detected by ultrasound, who lived during the testing period in 111 settlements where radiation measurements were not done. The values of exposure rate in these settlements were assessed using developed approaches to reconstruct the exposure rate along and across the fallout trace based on exposure rate measurements made at neighboring settlements after the same test. A total of 66 locations with measured exposure rates were available for the study. The validity of the approaches was tested using 24 pairs of exposure rates measured in villages located along the fallout trace at similar distances from the trace axis as well as by comparing with literature data. The results of this study are used to reconstruct thyroid doses in individuals who were exposed as children and young adults to fallout from atmospheric nuclear weapons tests conducted at the Semipalatinsk nuclear test site between 1949 and 1962.