Evaluation of Gamma Radiation Dose Level in Mining Sites of Riruwai, Kano, Nigeria

Abstract

Aminu Ismaila^*, Abubakar Sadiq Aliyu and Yakub Viva Ibrahim

Some radioelements are natural with redistribution related to human activities like mining. Human beings are constantly associated with these radioelements through water and food intake and may be exposed to background natural radiation from terrestrial and cosmic sources. Among all types of radiation, gamma rays are the most penetrating radiation that emanates from natural and artificial sources. External exposure to gamma radiation varies from one location to another, depending on the geological composition, and elemental content (especially those of U, Th and K in rocks of a particular region). In this study, gamma radiations around mining areas in Riruwai were measured using RadEye Portable Radiation Detector. Gamma dose measurements were taken from 40 sampling locations and at 1 m above the soil surface. Geographical coordinates of the locations were taken using a Global Positioning System (GPS). The analyses show that the gamma radiation dose level attended a mean value of 749 nGy/hr which is thirteen times greater than the maximum permissible value (57-59 nGy/hr) recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The mean indoor and outdoor annual effective doses (AED) were 0.91 and 3.65mSv/yr, which are about three and four times more than their respective world average values of 0.3 mSv/y and 1mSv/y respectively. The Excess Lifetime Cancer Risk (ELCR) factors were 2.51 ×10^-3 and 10.5 ×10^-3 for indoor and outdoor respectively and these correspond to a nine-fold increase of their world average values of 0.29 × 10⁻³ and 1.16 × 10⁻³ as prescribed by the UNSCEAR. The computed data indicated that miners and the public residing close to the mining zone may be at risk and there is a need for an urgent remediation process. The results of this study can provide valuable information on radiological risk which could be used for radiation safety and protection and in the utilization of the soil in the region for agriculture and domestic use. It also contributes to baseline radiological data that could be used by the policymakers and for future studies.