Dietary intakes and internal exposure doses received by residents of the Karachai Trace

Abstract. Due to several radioactive accidents at the Mayak Production Association, a facility for production of weapon plutonium put on line in 1948 in the Southern Urals (Russia), an substantial part of the Southern Urals territory was contaminated by long-lived radionuclides. One of the such accident was the wind resuspension of radionuclides (2⋅10Bq) from the shoreline of Karachai lake used as a depot of liquid radioactive waste, that formed the Karachai Trace in 1967. The main task of the present investigation is to estimate the dietary intakes of radionuclides and exposure doses for residents of settlements located on the Karachai Trace. For these purposes, dynamics of changes in the contents of Sr and Cs in main foodstuffs and diet composition were studied for residents of 6 settlements. Milk was found to be the main contributor of radionuclides to the residents’ diet. The pattern of the decrease in radionuclide concentration in milk can be described by a twoexponential dependence. The biological accessibility of Sr and Cs settled in the Karachai area was lower compared to that observed on the East-Urals Radiation Trace (formed in 1957 due an explosion in the radioactive waste-storage facility), or in the Chernobyl area. Accumulated and current exposure doses were estimated for each calendar year based on the data on contents of radionuclides in the residents’ diets. The accumulated whole body dose from Cs estimated for adult residents in the most heavily contaminated village of Sarykulmiak was 0.83 mSv. The accumulated red bone marrow dose from Sr was 19.1 mSv. The summary effective dose from Cs and Sr amounted to 3.7 mSv.