Radium-226 and head-210 in agriculture products produced on the environs of the uranium mine and mill at the Pocos de Caldas plateau in Minas Gerais

Radium-226 and Lead-210 in agriculture products produced on the environs of the uranium mine and mill at the Pocos de Caldas Plateau in Minas Gerais. As a complement to the pre-operational environmental monitoring program of the Brazilian first uranium mine and mill, a survey of 226Ra and 210Pb in agriculture products, and in the corresponding soils, were carried out in the Pocos de Caldas Plateu. The survey intended to determine site specific transfer factors, in order to better estimate radiation doses on the population, resulting from the plant operation. In local soils, 226Ra and 210Pb have similar concentrations. The average contents are comparable to the values found in areas of normal radioactivity, but the maximum values are higher by one order of magnitude. In the vegetables analyzed (beans, carrot, corn and potato), 226Ra concentrations are slightly higher than those of 210Pb, and the maximum values are also one order of magnitude greater than in normal regions. For both radionuclides, the average soil-to-plant transfer factors are of the order of 10-3 and 10-2 when related to total and to exchangeable content soil, respectively. These results led to the conclusion that 226Ra and 210Pb have similar importance, concerning the population exposure via the foodstuff ingestion pathway. Therefore, it was recommended to carry on routine monitoring program for both radionuclides in the main agriculture crops. However, the naturally elevated radionuclide concentrations, in some local vegetables, will decrease the sensivity for detecting for detecting small increments resulting from the plant operation. (Author)