Assessment of Activity Concentration and Health Hazards of Radiation Exposure in Soil from Mamara Jidda and Waja Tin Mining Sites in Northern Nasarawa State, Nigeria

Abstract

Natural background radiation exposure is an inevitable occurrence on Earth, and humans are exposed to radiation in their surroundings whether consciously or unconsciously. However, increased artisanal and illegal mining could harm the local environment and increase background radiation levels, affecting the community's overall health. This study assessed the activity concentration of primordial radionuclides (226Ra, 232Th, and 40K) from soil samples obtained from Mamara Jidda and Waja tin mine sites in Nasarawa State, Nigeria, and its risk to human health. The gamma spectroscopy using a Sodium iodide-thallium activated detector was used to measure the activity concentrations of primordial radionuclides in the surface soils/sediments samples. The activity concentrations of 226Ra, 232Th, and 40K for Mamara Jidda and Waja were found to be within the range of 4 - 18 Bq kg-1, 41 - 105 Bq kg-1, and 524 - 717 Bq kg-1; 13 - 40 Bq kg-1, 75 - 134 Bq kg-1, and 591 - 882 Bq kg-1 respectively. The average values show that 40K and 232Th concentrations are above the recommended limit set by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) in Mamara Jidda and Waja mine sites. The annual gonadal dose equivalent (AGDE), annual effective dose rate (AEDE), radium equivalent (Raeq), absorbed dose rate (D), and external hazard index (Hex) for Mamara Jidda and Waja were found to be 0.56 mSv yr-1, 0.10 mSv yr-1, 588.58 Bq kg-1, 78.26 nGy hr-1 and 0.46; 0.73 mSv yr-1, 0.13 mS yr-1, 742.74 Bq kg-1, 103.72 nGy hr-1 and 0.61 respectively. The AEDE and Hex are below the recommended safety limits. However, the high values of AGDE in both mining sites and D in Waja mine demonstrate that with continuous exposure to radiation, a significant genetic impact is eminent to the miners and inhabitants of these areas. Also, the Raeq values for both mines suggest that their soils are unsafe for use as building materials.