ASSESSMENT OF RADIONUCLIDE BIOACCUMULATION IN RICE AND SWEET POTATOES CULTIVATED ACROSS SELECTED AGRICULTURAL COMMUNITIES IN KEBBI STATE, NIGERIA

This study investigates the bioaccumulation of natural radionuclides in rice and sweet potato samples obtained from selected farmlands across Kebbi State, Nigeria. Samples from three different local government areas were analyzed using gamma-ray spectroscopy with a NaI(Tl) detector to determine the activity concentrations of 238U, 232Th, and ^40K. In rice samples, the activity concentrations ranged from 2.51 ± 0.22 to 3.01 ± 0.14 Bq/kg for 238U, 6.30 ± 0.14 to 9.71 ± 1.23 Bq/kg for 232Th, and 76.65 ± 1.38 to 101.09 ± 2.73 Bq/kg for 40K, with mean values of 2.33 ± 0.19, 7.12 ± 1.51, and 79.07 ± 1.55 Bq/kg, respectively. For sweet potatoes, activity concentrations varied from 0.50 ± 0.08 to 2.03 ± 0.03 Bq/kg (238U), 3.17 ± 0.31 to 5.19 ± 0.25 Bq/kg (232Th), and 42–133.30 ± 3.40 Bq/kg (40K). The bioaccumulation factors for all radionuclides were found to be below unity, indicating insignificant accumulation in the analyzed crops. Corresponding excess lifetime cancer risk (ELCR) values for rice and sweet potatoes across the study sites were within acceptable safety limits, with average values ranging from 251.77 to 421.93 for rice and 342.83 to 428.33 for sweet potatoes. These results suggest that the potential radiological health risk to consumers is minimal, and the investigated crops do not constitute a significant source of radiotoxicity to local communities. The study concludes that the current levels of natural radionuclides in rice and sweet potatoes cultivated in Kebbi State are within international safety standards, supporting their safe consumption and continued agricultural production.