Analysis of Radiological Hazard Indices from Mining Sites in Adamawa State, Nigeria

Aims: To analyse the radiological hazard indices from mining sites in Adamawa State, Nigeria.

Study Design: Experimental study design using Gamma ray spectroscopy with a well calibrated Sodium Iodide (NaI) detector.

Place and Duration of Study: Adamawa State, Nigeria and Department of Physics, Nasarawa State University Keffi, Nigeria, and Centre for Energy Research and Training (CERT) Laboratory, Ahmadu Bello University Zaria, Nigeria between November 2019 and August 2020.

Methodology: Fifteen composite samples of soil from four mining sites collected using the systematic sampling techniques were analysed for activity concentrations of Ra-226, Th-232 and K-40 and Gamma Absorbed Dose Rate, Radium Equivalent Activity, External Hazard Index, Annual Effective Dose Rate and Excessive Life Cancer Risk were calculated.

Results: Mean activity concentrations Ra-226 (107.60Bq/kg), Th-232 (84.89Bq/kg), and K-40 (475.34Bq/kg) were all above the world average values 35Bq/kg, 30Bq/kg and 400Bq/kg recommended by UNSCEAR. Mean Gamma Absorbed Dose Rate, Radium Equivalent Activity, Annual Effective Dose Rate, External Hazard Index, and Excessive Life Cancer Risk were 120.31nGy/h, 265.469Bq/kg, 0.148mSv/y, 0.401, and 0.369 respectively, against recommended values 59nGy/h, 370Bq/kg, 1mSv/y, 0.45, and 0.29 according to UNSCER, NEA-OECD and ICRP.

Conclusion: High values of Activity Concentrations, Gamma Absorbed Dose, and Excessive Life Cancer Risk poses significant threat to the host community, especially around the 3 mining sites SA, SB and SC.

Therefore, safety distance from mining areas is recommended by the competent Authority responsible for radiation protection matters in Nigeria. General awareness to enlighten the public about the possible dangers of undue radiation exposure and the risk of residing close to mining vicinity is required, for adequate protection of the host community.