Assessment of radioactivity in soil samples from Wolaita Sodo town, Ethiopia: implications for environmental and public health

Abstract

This study assesses the activity concentrations of the radionuclides 238U, 232Th, and 40K in soil samples collected from Wolaita Sodo town, located in the Southern Nations, Nationalities, and Peoples' (SNNP) Region, Ethiopia. A gamma-ray spectrometer equipped with a NaI(Tl) detector was used for the measurements. The concentrations of 238U, 232Th, and 40K varied from 3.25 ± 1.5 to 13.84 ± 2.2 Bq.kg−1, 0.4 ± 0.9 to 85.12 ± 3.4 Bq.kg−1, and 34.43 ± 2.7 to 748.07 ± 5.9 Bq.kg−1, respectively. The average activity concentrations were 7.83 ± 1.9 Bq.kg−1, 40.74 ± 2.7 Bq.kg−1, and 161.63 ± 3.9 Bq.kg−1 for 238U, 232Th, and 40K, respectively. The average radium equivalent activity was 192.25 Bq.kg−1, well below the recommended safety limit of 370 Bq.kg−1. The average gamma dose rate, and annual effective dose rate were 35.68 nGy.h−1, and 0.18 mSv.y−1, respectively. The internal and external indexes are below the recommended limit set by UNSCEAR and ICRP. However, the estimated excess lifetime cancer risk and indoor radon concentrations are slightly higher. Despite this, the overall radiological impact on the environment and public health in the study area remains negligible. This study provides valuable baseline data for radiation protection and informs urban and environmental policy in the region.