Radiation Doses and Risk Assessment Due to Water Intake at Oyo Town, Southwestern Nigeria

Abstract

From the long standing nature of water usage, water has been has had a significant impact to all great development. Potable water has been recognized as the water intended for human consumption for the purpose of research and other human activities. Therefore, the World Health Organization (WHO) classified ²³⁰Th, ²²⁶Ra, ²¹⁰Pb, ²¹⁰Po, ²³²Th, ²²⁸Ra, ⁴⁰ K and ²²⁸Th as naturally occurring radionuclide contaminants in water and a possible threat to human existence. This work evaluated the activity concentration of natural radionuclide in ground water, examine radiation doses and the threat due to water intake from Oyo town using a 5 cm × 5 cm solid NaI(Tl) gamma-ray  spectrometric manufactured by ORTEC and coupled to a Digital-based multi-channel analyzer (MCA). From the results, 92.5 per percent of ⁴⁰K, 87.5 per cent of ²²⁶Ra and 95 of ²³²Th was greater than the IAEA safe limit of 1.00 Bql⁻¹limit. The average value of an annual effective dose for adults was 0.17±0.06 mSvy⁻¹ and 0.43±0.17 mSvy⁻¹ for children. Cancer risk assessment was obtained to 2.98 x 10⁻³ compared to ICRP recommended value of 8.4 × 10⁻³. Health risk implication resulting from consumption of water from the study area poses no health concern, no artificial radionuclide was detected and the chance of cancer occurrence resulting from drinking water from the study area is stochastic. It is recommended that caution should be taken on the fertilizer application on the farm land. Further research is recommended on the radioactivity measure of the soil and food crops grown in the study area.