Assessment of the Radiation Hazard Indices from Terrestrial Radiation in Mining Sites in Benue State, Nigeria

The assessment of the radiation hazard indices of solid minerals and sand in mining sites of Benue State, Nigeria was carried out using well calibrated radalert-50 and 100 meters and a Global Positioning System (Garmin 765). The sites investigated are Lessle (Barite), Gboko (Limestone), Owukpa (Coal) and Akuana (Salt) deposits fields. The mean background radiation ionization exposure rate of 0.019±0.004, 0.019±0.004, 0.014±0.002 and 0.023±0.005 mRh-1 were obtained respectively. The mean of absorbed dose rates estimated for the mining fields are 161.53, 169.40, 120.35 and 201.84 nGy/hr respectively. Estimated values of the annual effective dose equivalent (AEDE) for outdoor exposures 0.25, 0.26, 1.61, and 2.71 mSv/yr respectively while the mean excess lifetime cancer risk calculated for the mine fields values are (0.82, 0.86, 5.33 and 8.94) x 10-3 respectively. The obtained values for background ionizing radiation were higher than the recommended standard limits by ICRP while the AEDE calculated in the entire mine fields are within safe values but the absorbed dose (D) and excess lifetime cancer risk (ELCR) estimated were higher than their world permissible values of 89 nGy/hr and 0.29 x10-3 respectively. The work indicated that there is tendency for the residents near the mining sites to get high radiation doses and could develop radiation-related illness after a long time exposure.