Naturally Occurring Radioactive Concentrations and the Associated Cancer risks from Tailings by Kaolin Mining in Katsina, Nigeria

Abstract

This research was carried out to assess the health hazards associated with environmental radioactivity around Kankara and Dutsinma Kaolin mining sites Katsina State; Nine (09) Kaolin samples were collected randomly from the mining sites for the study. The radioactivity analysis was done experimentally using NaI(Ti) gamma spectrometer at Center for energy research and training, Ahmadu Bello University Zaria. The health hazards were evaluated using numerous radiological, Statistical and USEPA models.

The hazard indices were found to be below the USEPA threshold limit for non-carcinogenic risks of 1.0 indicating that the exposed population ages are unlikely to experience any adverse non-carcinogenic risks. The radiological parameters obtained are 226Ra, 238U, 232Th and 40K of NORMs (Naturally Occurring Radioactive Materials) with activity concentration of 100.889, 0.129 and 224.040 (Bq-kg^-1) in the soil samples, at the studied area. Absorbed dose rate in air (D) measured in nGyh-1 at 1 meter above the ground, was calculated from the mean radioactivity concentrations and obtained as 77.575 while the total annual effective dose (AED) in mSv/y had average value of 0.099 in soil. The values obtained for external and internal radiological hazard indices Hext and Hint are 0.471 and 0.741 in soil; which were lower than the UNSCEAR recommended limit of unity. Finally, the overall excess lifetime cancer risk due to NORMs were 5.63E-06 and 4.15E-06 for adults and children respectively in whole population indicating that a maximum of 6 adults per 1 million may be affected while a maximum of 4 children per 1 million may be affected. These values were within the USEPA threshold of 1E-04.