Assessment of the current levels of 241Am and 137Сs in soils and foodstuff, as well as of public internal exposure to ionizing radiation in populated areas adjacent to the Chernobyl NPP exclusion zone (case study: the Bragin district of the Gomel region, Belarus)

Abstract

This paper is part of a research cycle focusing on studying the current levels of 241Am and 137Cs in soils and local foodstuffs of populated areas neighboring the Chernobyl exclusion zone. Our objective was to estimate the maximum annual committed internal doses to individuals of the Bragin-area settlements from inhalation and consumption of locally produced foods. We updated the data on the levels of 241Am and 137Сs in soils of 28 settlements of the district. Specific activity of 241Am in soils in two of the settlements were the highest of all; we took and analyzed samples of local-grown foodstuff. 241Am in food samples was measured via a radiochemical method with the use of selective chromatographic resins and alpha-spectrometry measurement. A gammaspectrometry technique was used to measure 241Am in soil and 137Сs in soil and food samples. The most contaminated by 241Am and 137Cs appeared the soils in the town of Bragin, the administrative center of the district where the respective levels were as high as 2.8 and 560 kBq/m2. Among the analyzed samples, the specific activities of 241Am in root and tuber crops were one-digit values, while the samples of leafy vegetables contained a few tens of mBq/kg of the same radionuclide. That said, however, 241Am concentrations in food samples were lower than those of 137Сs by three orders of magnitude. The results showed an apparent difference between estimated annual committed internal doses to the Bragin residents due to 241Am intake and that resulting from 137Сs with the respective 0.03 and 1.7 mSv/year. The maximum doses to population of the Bragin-district villages from inhalation of 241Am varied from 0.006 to 0.033 mSv/year exceeding the doses from inhaled 137Сs – 0.0002-0.002 mSv/year – by one order of magnitude. The major contribution to the public internal exposure today is 137Сs intake through consumption of contaminated food that produced locally; its contribution is about 93-99% of the total internal dose received by the Bragin-district residents.