Reconstruction of 131I deposition density in regions of Belarus with estimation of thyroid doses from inhalation of 131I.

The relationship between 131I and 137Cs activity concentrations in 213 soil samples taken in 10 administrative districts of Belarus was derived. Analysis of the relationship shows a decreasing trend in the 131I/137Cs isotope ratio values with increasing 137Cs content in soil. Using the [131I-137Cs] relation obtained and the data on 137Cs contamination of settlements the 131I deposition density was evaluated for 1080 settlements situated in the area of investigation. Based on these assessments thyroid doses from inhalation of 131I were estimated. According to the results, the thyroid doses for the adult population vary from 5 to 40 mSv, the median dose is about 12 mSv. Uncertainties in the calculation of thyroid doses, based on the procedure applied, are discussed.