Evaluation of Naturally Occurring Radionuclides Concentration and Associated Radiological Health Risks in Agricultural Soils from Iwerele, Oyo State, Nigeria.

Abstract

Artisanal and small-scale mining activities often pose environmental and health risks to surrounding ecosystems. This study evaluates radiological hazards and potential exposure levels in soils from active and abandoned mining sites in Iwere-Ile, Oyo State, Nigeria. Twenty-two soil samples were analyzed using a Gamma-ray Spectrometer with a NaI(Tl) detector to determine the activity concentrations of naturally occurring radionuclides. The mean specific activities of ⁴⁰K and ²³²Th contributed about 15% and 9%, respectively, to the total radioactivity. The absorbed dose rate from terrestrial gamma radiation ranged from 5.86 to 217.48 nGy h⁻¹, averaging 58.06 nGy h⁻¹, slightly above the UNSCEAR global reference value of 55 nGy h⁻¹. The annual effective dose equivalent (AEDE) varied between 0.02 and 0.76 mSv yr⁻¹, remaining below the 1 mSv yr⁻¹ public dose limit. Although the annual gonadal dose equivalent (AGDE) exceeded international recommendations, the internal and external hazard indices were both less than unity, indicating minimal radiological threat. Overall, agricultural activities in the area can be considered radiologically safe despite ongoing mining operations.