Radiological Impact Assessment of Activity Concentrations in Soil Samples of Selected Region of Kwara State Nigeria

The soil, being a natural source of radiation consists of 238U, 232Th and 40K radionuclides which at elevated levels can pose a radiological health concern to humans as man is continuously exposed to radiation in the environment. Studies on soil activity levels and radionuclide distributions in selected region of Kwara state were carried out to provide a baseline data on gamma radiation due to soil samples. Following standard procedures, Gamma spectroscopy measurements were performed on a total of sixty four (64) collected soil samples from sixteen (16) selected regions using a high-resolution NaI(Ti) detector. Activity concentrations of 238U and 232Th vary from 1.76?1.5 to 16.25?2.1 below 35Bq/kg world limit at ASD location and 2.98?4.8 to 33.9?3.8 below 30 Bq/kg world limit at TK location. The activity of 40K was found significantly higher than 400 Bq/kg limit in 14 sampling regions. From gamma spectroscopy results, radiological hazard indices were estimated to assess the safety of the residents of the study area. In all locations, external and internal hazard indices revealed values significantly lower than ?unity? which is the limit set by International Commission on Radiation Protection (ICRP). The average values for annual effective dose falls below 1 mSv/yr limit set by (ICRP). Excess lifetime cancer risk (ELCR) estimated in TK location only showed value (0.4050 ?10-3) higher than the world average(0.29 ? 10-3). Overall, average ELCR (0.2564 ?10-3) value in the study area falls below the world average value. This implies that cancer risk of one member of the public in the study area over a 70 years lifetime is high.