Population dose from the uranium-phosphate region in Pernambuco State (Brazil), due to the presence of uranium and 226 Ra in the crops

This study aimed to determine the concentrations of uranium and 226 Ra in soils as well as in locally grown vegetables that are part of the diet of the local population. The annual intake of each radionuclide and the average annual food consumption were then used to estimate both, the dose to the critical organ and the effective dose. Analysis were carried out through fluorimetry, gamma spectrometry, and through the radon emanation technique. The maximum concentrations of uranium and 226 Ra found in the crops were 186 m Bq/Kg (wet) and 2,209 m Bq/Kg (wet), respectively. Maximum concentrations in soil, on the other hand, were 300 Bq/Kg (dry) and 240 Bq/Kg (dry) for total uranium and 226 Ra, respectively. Beans presented the highest average concentrations of both, uranium and 226 Ra, with cashew presenting roughly the same average value for uranium as that found in beans. The daily intake for the rural population was 0.82 μg for uranium, and 190 mBq/Kg for 226 Ra. Therefore, the doses to the critical organ (bones) were 1.1 x 10 -3 mSv/Y and 5.2 x 10 -1 mSv/Y for uranium and 226 Ra, respectively. The effective doses, on the hand, were 1.6 x 10 -4 mSv/Y and 2.7 x 10 -2 mSv/Y for uranium and 226 Ra, respectively. Considering the average amount of the 226 Ra ingested per year, a 3% increase in the rate of head carcinoma and a 1% increase in the rate of bone sarcoma were estimated. (author). 103 refs., 48 figs., 11 tabs