Determination of238U, 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 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb in faecal samples of inhabitants of this area was determined by a sequential analytical method. The results of the average concentration in faeces of inhabitants of Buena are 9.4 ± 3.4 mBq/gash for 238U, 9.2 ± 4.0 mBq/gash for 234U, 7.0 ± 4.2 mBq/gash for 232Th, 256.1 ± 134.6 mBq/gash for 228Th, 335.5 ± 192.8 mBq/gash for 228Ra, 156.6 ± 74.1 mBq/gash for 226Ra and 66.7 ± 17.7 mBq/gash for 210Pb. The results were compared with the background concentrations from faecal samples from individuals living in Rio de Janeiro City. For most of the radionuclides analysed, the average concentration in faeces from inhabitants of the high natural radiation background were higher than the concentration found in Rio de Janeiro considered a 'normal' background area.