Abstract

This study was carried out to determine the annual effective dose of radionuclides; Potassium (⁴⁰K), Uranium (²³²U)   and Thorium (²³²Th) from the ingestion of groundwater in Veritas and its environs. Thirty (30) water samples were collected and analyzed by adding 1ml of nitric acid (HNO₃) to prevent adsorption of radionuclides to the container walls and kept for 30 days to attain secular equilibrium after which NaI detector was used to measure the activity concentration.  Results showed that the estimated mean activity concentrations were 88.50±7.84Bq.l^-1, 9.28±1.71Bq.l^-1 and 6.87±0.60Bq.l^-1 for ⁴⁰K, ²³⁸U and ²³²Th respectively. The mean annual effective dose to children of ages 7-12 months, 1-3 years and 4-8 years are: 1.602±0.142mSvBq^-1, 1.764±0.156mSvBq^-1, and 1.153±0.101mSvBq^-1, respectively for ⁴⁰K; 0.379±0.070mSvBq^-1, 0.528±0.098mSvBq^-1, and 0.461±0.085mSvBq^-1 respectively for ²³⁸U and 9.223±0.812mSvBq^-1, 1.466±0.129mSvBq^-1, and1.491±0.131 mSvBq^-1 respectively for ²³²Th. The total annual effective doses (AED) and mean total AED to children of age 7-12 months, 1-3 years and 4-8 years was estimated. The results showed that the mean activity concentration of ⁴⁰K, ²³⁸U and ²³²Th (Bq.l^-1) in all the water samples exceeded the WHO and UNSCEAR recommended safe limits of 10.0, 10.0 and 0.10 respectively. The mean total annual effective dose (mSvyr^-1) of ⁴⁰K, ²³²Th and ²³⁸U for children within the ages of 7 months to 8 years also exceeded the WHO and UNSCEAR recommended safe limits of 0.26-1mSvyr^-1. Thus, the groundwater supplies under investigation have been found to be radiologically contaminated and unsafe for human consumption. It is hereby recommended that, Government, Non-Governmental Organizations and private individuals should provide alternate safe sources of water supply for residents of the study area as to protect public health and prevent any public health challenges.