Assessment of Gamma Radiation Dose Rates in Gold Mining Communities of Zamfara State

Artisanal gold mining activities in Zamfara State, North West Nigeria, have expanded dramatically over the past decade, raising significant concerns about occupational and environmental radiation exposure from naturally occurring radioactive materials in gold-bearing ores. This study assesses ambient gamma radiation dose rates in five active mining communities across Anka and Maru Local Government Areas using calibrated Geiger-Muller survey meters. Measurements were taken at mining pits, ore processing sites, residential areas, and reference control locations away from mining activity. Readings were recorded during three field campaigns spanning the dry and early wet seasons to capture temporal variation. Annual effective dose estimates were calculated using conversion factors recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation. Measured outdoor dose rates at mining sites ranged from 0.18 microsieverts per hour to 1.42 microsieverts per hour, significantly exceeding values at control locations. Processing sites where ore is crushed and washed recorded the highest values, consistent with the concentration of radionuclides during ore beneficiation. The study identifies radium-226 and thorium-232 as the primary gamma-emitting radionuclides contributing to elevated background readings. Health risk indices calculated for community residents indicate incremental lifetime cancer risk values above the one-in-one-million threshold for populations in direct proximity to processing areas. Recommendations include mandatory radiation monitoring, use of personal protective equipment, and relocation of ore processing activities away from residential settlements. Keywords: gamma radiation, gold mining, Zamfara, dose rate, occupational exposure