EPR dose reconstruction of two Kazakh villages near the Semipalatinsk nuclear test site

Abstract

Electron paramagnetic resonance (EPR) dose reconstruction has been performed on archived tooth samples from residents of two villages near the Semipalatinsk nuclear test site in Kazakstan. The context of this work is a large multidisciplinary study of thyroid disease prevalence and radiation dose among long-term residents of villages near that nuclear test site, in which EPR is used for biodosimetric validation of the gamma-ray component of dose reconstruction algorithms applied to the data for various villages whose residents were exposed to radioactive fallout during 1949–1962, the period of above-ground atomic bomb testing. The tooth samples, nine from the village of Kainar and 23 from the village of Znamenka, were extracted in 1964 and 1967, respectively, and stored indoors in closed boxes in Semipalatinsk. According to provided information, some time in the past, the teeth from Kainar were heated to 80°C for one day. Experiments carried out on 12 teeth from US sources to determine the effects of long-term storage and heat treatment found that EPR assay findings were not compromised for storage times less than 35 years and annealing at temperatures below 200°C. For tooth enamel samples prepared from molars and premolars the average reconstructed gamma dose was 390±70 mGy for Kainar residents and 95±40 mGy for Znamenka residents.