Natural Radioactivity and Associated Dose Rates of 238U, 232Th and 40K Radionuclides in Hand-dug Well Water of Major Mining Sites in Oke-Ogun area, Oyo State, Nigeria

The objective of this paper is to measure the natural radioactivity and associated dose rates of 238U, 232Th and 40K radionuclides in hand-dug well water from mining sites in Oke-Ogun area, Oyo State, Nigeria using sodium iodide detector. The mean activity concentrations of 238U, 232Th and 40K, ranged from 5.21 ± 0.01 to 88.01 ± 1.10 Bq/L with a mean of 24.56 ± 1.28 Bq/L, 13.35 ± 0.28 to 290.12 ± 1.31 Bq/L with a mean of 101.88 ± 1.02 Bq/L, 4.52 ± 1.15 to 79.13 ± 2.01 Bq/L with a mean of 102.31 ± 1.23 Bq/L respectively. The mean values of the radium equivalent activity ranged from 21.34 Bq/L to 804.76 Bq/L with a mean of 245.17 Bq/L. The annual effective dose on the infants ranged from 5.87 mSv/y to 2.57 mSv/y with a mean of 1.14 mSv/y while the annual effective dose on children ranged from 8.31 mSv/y to 4.65 mSv/y with a mean of 2.25 mSv/y. The infant and children had the lowest and highest annual effective dose at Eluku and Ofiki mining sites, respectively. The annual effective dose on adults ranged from 6.56 mSv/y to 2.01 mSv/y at Igbeti and Sepeteri mining sites, respectively, with a mean of 4.18 mSv/y. The annual gonadal equivalent dose ranged from 65.00 to 2397.82 mSv/y with a mean of 732.55 mSv/y for the whole mining sites under study from Oke-Ogun area, Oyo State, Nigeria. Hence, the groundwater from the mining areas of the studied location is safe for drinking and domestic purposes. However, regular radiation monitoring and evaluation of groundwater from the studied area for any possible risk should be sustained.