Determination of Radionuclides Concentration and Transfer Factor in Selected Crops in Ganye Local Government Area of Adamawa State, Nigeria

Abstract

The activity concentrations of natural radionuclides (²³⁸U, ²³²Th and ⁴⁰K) in the food crops grown in Ganye Local Government Area of Adamawa State with their corresponding soil samples were measured using gamma-ray spectroscopy. The research was to determine the concentration of radionuclides in selected crops and their Transfer factor. The activity concentrations of eight (8) maize samples, eight (8) groundnut samples and four (4) yam samples with their corresponding soil samples were determined using gamma spectroscopy with a 3'' x 3'' NaI (Tl) detector. Soil radioactivity exceeded UNSCEAR recommended values for ²³⁸U and ⁴⁰K, while ²³²Th generally remained within safe limits. In crops, ⁴⁰K showed the highest activity (ranging 88.38 ± 5.02 Bq/kg -148.42 ± 8.07 Bq/kg), followed by ²³⁸U (12.62 ± 2.52 – 25.12±3.90 Bq/kg) and ²³²Th (3.95 ± 0.33 - 15.19 ± 0.42 Bq/kg ). Transfer factors for all crops were below 1, indicating low soil-to-plant transfer. Radiological hazard indices including absorbed dose rate, radium equivalent, hazard indices, annual effective dose, and gamma index were all below international safety limits. However, the excess lifetime cancer risk (ELCR) exceeded the recommended threshold of 1E-4 to 1E-6 across all crops. This suggests a potential long-term cancer risk from continual consumption, despite the minimal transfer of radionuclides into crops. The findings indicate that while soils in the study area have elevated natural radioactivity, crop contamination remains low and does not pose an immediate health threat. Continuous monitoring and soil management are advised to ensure sustainable agricultural safety.