Gamma radiation exposure levels due to radionuclides in soils from selected gold mines in Karamoja

Abstract

The aim of this study was to determine radiation exposure levels due to gamma ray emitting radionuclides in soils from selected gold mines in Karamoja and the associated hazard indices. The people of Karamoja use poor methods of mining gold, therefore they are exposed to ionizing radiation of unknown concentrations. In this study, 60 samples from Rupa, Nakabaat, Morulem, Acerer, Nabulatuk and Morita were analysed using a Nal (TI) gamma-ray detector. The activity concentrations of natural radionuclides 226 Ra, 232 Th, 238 U and 4° K in soils were measured by gamma spectroscopy using sodium iodide detector. In addition, radiological assessment due to these radionuclides was also carried out. To ensure quality control, the samples collected from the sites were transferred to polythene bags, labeled and double-bagged. They were transported in boxes whose background radiation emissions were measured with an identifier. The average activity concentrations of 226 Ra, 232 Th, 238 U and 4° K were 49.26 ± 1.58, 44.29 ± 0.74, 16.57 ± 0.40 and 599.64 ± 7.33 Bqkg-1 respectively. The mean absorbed dose rate was 50.44 ± 1.48 nGhr-1 which is below the world average dose rate of 60 nGhr-1 • Radium equivalent values for the area studied ranged from 83 .83 ± 2.33 to 186.12 ± 3.52 Bqkg-1 with mean of 117.22 ± 2.30 Bqkg-1 which is below the world average of 370 Bqkg-1 • The mean external and internal hazard indices were both below unity. Therefore, though the results in the study indicated higher levels of natural radionuclides in soils of Karamoja region than the world average values, the mining activities pose no significant radiological hazard to the population and the soils from these areas can be safely used for construction purposes. The observed unprofessional practices such as lack of use of gas masks while working in the dust-filled mine caves could expose workers to possible risks from inhalation of respirable crystalline silica and radon gas; therefore miners must be educated and sensitized on the effects of exposure to radiation by the Atomic Energy Council of Uganda. These can be done by introducing Safety and Health awareness days. People of Nabulatuk and Acerer in Nakapiripirit district where concentrations of radionuclides are twice the world average levels must be advised to reduce on the time they spend in mines.