EVALUATION OF DOSE DUE TO INGESTION OF NATURAL RADIONUCLIDES OF THE URANIUM SERIES IN SPRING WATERS

The concentrations of uranium isotopes and their decay products Ra-226 , Rn-222, Pb-210 and Po-210 have been analyzed in the mineral spring w aters of a highly radioactive region of Brazil: Aguas da Prata. This r egion is located in the Pocos de Caldas Plateau, one of the largest we athered alkaline intrusions in the world. Dose calculations were perfo rmed to evaluate the relative importance of these radionuclides in the exposure of the local population to radiation. Based upon concentrati ons measured in all the springs available, effective doses per year va rying from 1.4 X 10(-4) mSv year(-1) for U-238 to 5.1 X 10(-2) mSv yea r(-1) for Rn-222 were observed. The doses from the ingestion of Rn-222 , Po-210 and Pb-210 are of the same order of magnitude, and therefore these radionuclides are the most critical as far as the consumption of these waters is concerned. (C) 1998 by Radiation Research Society.