Evaluation of NORM and Associated Radiological Hazards at Mada Walabu and Eastern Walabu District in Eastern Borena Zone, Oromia, Ethiopia

This research was aimed to investigate the presence of Naturally Occurring Radioactive Materials (NORMs) mainly uranium-238 (U-238), thorium-232 (Th-232), and potassium-40 (K-40) in soil and water samples from artisanal mining and farmland areas in Madawalabu and Eastern Walabu Woreda. Using a High-Purity Germanium (HPGe) detector, the research aimed to quantify activity concentrations, assess radiological hazard indices, and estimate excess lifetime cancer risk. The results revealed that soil samples from artisanal mining sites exhibited remarkably elevated activity concentrations of U-238 (123 ± 6.12 Bq/kg), Th-232 (150 ± 11.01 Bq/kg), and K-40 (717 ± 34.29 Bq/kg), all greater than global averages. Corresponding radiological hazards also exceeded the permissible world limits, with calculated values such as D (177.057 nGy/h), Eγ,ext (0.22 mSv/y), and CRlifetime (7.76×10⁻⁴). In contrary, farmland soils showed slight elevations for Th-232 and K-40, but U-238 remained below global limits. Some hazard indices—like D (68.55 nGy/h) and Iγ (1.106) were exceeded permissible levels, while others remained within permissible limits. Water sample analysis found no detectable U-238 but measured Th-232 (1.825 ± 0.745 Bq/l), exceeding WHO guidelines, and K-40 (14.75 Bq/l), for which no limit is specified by WHO guidelines. Radiological risks from water remained low, though CRlifetime still slightly above the permissible world limits. Employing the Linear No-threshold radiation model, the study emphasized potential long-term health risks in exposed populations. Key recommendations included continuous radiation monitoring with Optically Stimulated Luminescence Dosimeters, public awareness initiatives, relocation of vulnerable residents, restrict mining site access, and on-site use of portable HPGe detectors for future assessments.