Abstract

The determination of annual effective dose of radionuclides (⁴⁰K, ²³²Th and ²³²U) in water samples from communities along the banks of New Calabar River for infants was carried out. Twenty-eight (28) water samples were collected and treated with 1 M HNO₃ to allow for homogeneity and to avoid precipitation and adsorption of radionuclides on the walls of the containers. Activity concentrations of these radionuclides in the samples were first measured, using NaI spectrometer detector. The annual effective dose for infants due to the intake of the river water was determined by using the activity concentrations of the radionuclides with their ingested dose conversion factor. Results of the mean activity concentration () for ⁴⁰K, ²³²Th and ²³²U are: 62.43±3.26, 4.18±0.24 and 9.37±1.19 respectively. The mean annual effective dose () for infants 0-1yr and 1–2yrs are: 0.63±0.037 and 0.957±0.05 for ⁴⁰K; 3.548±0.203 and 0.687±0.039 for ²³²Th; 8.041±1.023 and 3.285±0.403 for ²³²U respectively. The mean total annual effective doses for infants of 0–1 yr and 1–2 yrs old are: 12.247±1.258 and 4.929±0.496 respectively. The results showed that the mean activity concentration of ⁴⁰K, ²³²Th and ²³²U () in all the water samples exceeded the WHO and UNSCEAR recommended safe limits of 10.0, 0.10 and 10.0 respectively. The mean total annual effective dose () of ⁴⁰K, ²³²Th and ²³²U for infants also exceeded the WHO and UNSCEAR recommended safe limits of 0.26. The water supplies under investigation have been found to be radiologically polluted and unsafe for human consumption. It is recommended that alternative safe sources of water supply be provided by Government, Non-Governmental Organizations and/or private individuals for the inhabitants of the study area.