Estimating the transfer factor of natural radionuclides from soil to food chain pathways at a farmland in the southwestern Nigeria

Abstract The transfer factors of naturally existing radionuclides (NRs) from soil to food chain pathways on a farmland in southwestern Nigeria were estimated by measuring the activity concentrations of NRs in 20 soil samples taken from the study site using sodium iodide NaI (Ti) spectrometer detector. According to the results, the mean activity concentrations of 238U, 232Th, and 40K were 12. 53 ± 4. 66 Bq/kg, 20. 76 ± 7. 51 Bq/kg, and 310. 79 ± 85. 91Bq/kg, respectively. These results fell below the recommended upper limit of NRs in soil. The calculated outdoor absorbed dose rate (DR), radium equivalent activity (Re) and gamma representative index (\ (\: I\: \) ) were 32. 02nGyh− 1, 66. 15 Bq/kg and 0. 5 Bq/kg respectively. The DR, Re and Iγ were within the recommended range. The activity concentrations of 238U and 232Th in the vegetation and in the meat and milk produced by grazing animals on the farm were estimated. 238U and 232Th were estimated to be present in vegetation at concentrations of 0. 2572 and 1. 9049 (Bq/kg), respectively; in cow milk produced from cow grazing at the research site, the concentrations were 2. 408 and 1. 714 (Bq/L) and; in cow meat, they were 0. 802 and 0. 175 (Bq/kg). These values are considerably safe and may not pose significant health concerns when food processed at the study site is consumed. The calculated transfer factors from soil into vegetation for 238U and 232Th were 0. 02 and 0. 0903 respectively while those from soil into cow milk were 1. 902e− 4 and 8. 256e− 6, respectively; those from soil into cow meat were 6. 4e− 5 and 8. 43e− 7 respectively.