Abstract/Summary

This study aimed to assess the radiological health implications to humans due to the use of kaolin from kaolin mines in Nigeria. A calibrated RS-125 spectrometer was used in-situ to monitor the activity concentrations of 40K, 238U, 232Th and dose-rate of kaolin minefields in Ilorin-south and Ilorin-west, Nigeria. The in-situ monitoring and measurements were done in 90 locations selected at random in the study areas. The in-situ measurements were consolidated via laboratory analysis of 48 samples of Kaolin bricks using lead-shielded NaI(Tl) detector. The estimated average values for all radiological hazard parameters for the in-situ measurements of Ilorin-west are higher than that of Ilorin-south minefield. However, the opposite was the case with the laboratory analysis of the bricks. This apparent conundrum was due to the higher values of 238U observed in the samples of bricks from Ilorin-south. In addition, the measured activity concentration of the primordial radionuclides in the Kaolin bricks from both mines are lower than the on-site measurements. This was attributed to the contribution from other terrestrial materials on-site. The 5th, 50th, and 95th percentiles of the cumulative probabilities for the excess lifetime cancer risk using the Monte Carlo simulation are 167.00 × 10–6, 281.00 × 10–6, 414.00 × 10–6 for Ilorin-west (in-situ), 104.00 × 10–6, 232.00 × 10–6, 392.00 × 10–6 for Ilorin-south (in-situ), 706.00 × 10–6, 1,250.00 × 10–6, 1,900.00 × 10–6 for Ilorin-west (lab), and 742.00 × 10–6, 1,480.00 × 10–6, 2,460.00 × 10–6 for Ilorin-south (lab), respectively. Therefore, the cancer risks are within the acceptable limits for both mining sites. This study is useful in developing radiation risk assessment models for decision makers in different fields of environmental sciences.