Determination of 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb concentration in excreta samples of inhabitants of a high natural background area

The high concentration of uranium and thorium in certain Brazilian areas provides an opportunity to evaluate the radiation exposure due to intake of radionuclides by the populations that live and work in areas with a high natural radiation background. Buena, where this study was conducted, is a small village on the coast in the northern part of Rio de Janeiro State, characterised by the presence of a large deposit of monazite sand. In this paper. the concentrations of U-238, U-234, Th-232, Th-228, Ra-228, Ra-226 and Pb-210 in faecal samples from inhabitants of this area were determined by a sequential analytical method. The results of the average concentrations in faeces of inhabitants of Buena are 9.4 +/- 3.4 mBq g(ash)(-1), for U-238, 9.2 +/- 4.0 mBq g(ash)(-1) for U-234, 7.0 +/- 4.2 mBq g(ash)(-1) for Th-232 256.1 +/- 134.6 mBq g(ash)(-1) for Th-228, 335.5 +/- 192.8 mBq g(ash)(-1) for Ra-228, 156.6 +/- 74.1 mBq g(ash)(-1) for Ra-226 and 66.7 +/- 17.7 mBq g(ash)(-1) for Pb-210. The results were compared with background concentrations from faecal Janeiro City. For most of the radionuclides analysed, the average concentration in samples from individuals living in Rio de faeces from inhabitants of the high natural radiation background was higher than the concentration found in Rio de Janeiro, considered a 'normal' background area.