Assessment of the Annual Effective Dose and Excess Lifetime Cancer Risk Due to Natural Background Radiation Levels in West Pokot, Kenya

Abstract

This research determined the annual effective dose equivalent (AEDE) and excess lifetime cancer risk (ELCR) resulting from background ionizing radiation (BIR) within the vicinity of the Ortum and River Muruny artisanal gold mining sites in West Pokot, Kenya. The study employed a portable hand-held Thermo Scientific RADEYE PRD Personal Radiation Detector for data collection. Measurements of the ADR in air were conducted at thirty-two distinct locations within the sites and their surroundings, each positioned 1.0 meters above ground level. The recorded ADRs ranged from 66 to 155 nGy h− 1 within the sites, with an average of 106 ± 22 nGy h− 1. These readings were above the global average value of 60 nGy h− 1. The AEDE ranged from 0.08 to 0.19 mSv, with a mean of 0.13 ± 0.03 mSv/yr, which is below the threshold limit of 1 mSv/yr. The excess lifetime cancer risk (ELCR) ranged from 0.28x10− 3 to 0.67x10− 3, with an average of 0.46 ± 0.10. These values surpass the recommended limit value of 0.299×10− 3. While the AEDE values were compliant with international recommendations of 1 mSv/y, the ELCR values surpassed the average recommended limit. This suggests that artisanal gold mining sites pose no immediate radiological health hazards due to the absorbed dose from the BIR, yet the risk of cancer development over a lifetime of exposure remains considerably high. Thus, routine monitoring of the BIR and radioactivity concentration in soil and rocks and minimizing prolonged exposure are recommended to ensure the safety of workers and residents.