Estimation of public radiological dose from mining activities in some selected cities in Nigeria

Abstract

Mining activities is one of the most significant sources of radiation exposure from long-lived naturally occurring radioactive materials (NORMs), and have resulted in unjustifiable public exposure doses which contravene radiation protection standards. As a result, estimating the extent of such exposure is essential for keeping the recommended public dose limit. This study therefore aims at estimating the public radiation dose around mining areas and its environs in some selected cities across Nigeria. Data on measured activity concentration of NORMs radionuclides comprising of U-238, Ra-226, Th-232 and K-40 from soil round mining areas in some selected cities in Nigeria were extracted from previous literatures and are used for public dose estimation using RESRAD computer code. From the calculated mean activity concentration, the results from each mining locations shows the maximum dose are lower than International Commission on Radiological Protection (ICRP), commended public dosage boundary of 1 mSv/yr with highest dose of 0.91 mSv/yr from Ra-226, Th-232 and K-40 over the period of 47.9 years reported from Gura Top mining site in Jos, Plateau State, while the lowest dose of 0.09 mSv/yr each over the period of 14.06 and 20.27 years occurred at Itagunmodi and Arufu sites for U-238, Th-232 and K-40. The highest dose recorded in Gura Top was due to numerous mining activities in the region. According to the ICRP, there is no safe level of radiation exposure. Therefore, there is need for competent authorities to conduct periodic assessment of radiation exposure from mining sites to ensure that all exposure emanating as a result of such activities are kept below the prescribed dose limit in accordance to the principle of As Low As Reasonably Achievable (ALARA), thereby ensuring public protection from unjustified radiation exposure.