Assessment of effective dose and radiation risk due to 226Ra, 40K, and 232Th exposure within the soil of artisanal gold mine using the RESRAD code.

This study aimed to estimate the excess lifetime cancer risk (ELCR) from internal and external exposures to naturally occurring radionuclides of 226Ra, 232Th, and 40K in soil from three artisanal mining and resident agricultural regions in Niger State, North Central Nigeria. A NaI(Tl) detector was used to determine NORM concentrations in the soil samples, and the ELCR for artisanal miners and resident farmers was simulated using the RESRAD (residual radioactivity) code. The average activity concentrations of NORMs (226Ra, 232Th, and 40K) were estimated to be 18.79 ± 0.91, 7.87 ± 1.23, and 346.39 ± 10.35 Bq/kg, respectively. The excess cancer risks from the exposure to these radionuclides were estimated by the application of the RESRAD code. The simulation results indicate that the ELCR ranged from 2.33 × 10⁻⁶ to 5.40 × 10⁻⁶ within the evaluated time period (1-100 years), with the minimum value associated with 232Th and the maximum value associated with 22⁶Ra. These results show that 226Ra has the highest ELCR over 100 years, followed by 232Th in the soil from the artisanal mining areas. The results show that the dominant exposure pathways were through direct radiation from soil (direct and airborne) and inhalation. The findings of this study could help determine the risk of environmental natural radioactivity as well as in making decisions about radiation protection.