Assessment of 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 absorbed dose rate (ADR) in air were conducted at thirty-two distinct locations within the sites and their surroundings, each positioned at 1.0 meters above ground level. The recorded ADR values ranged from 66 to 155 nGy h− 1 within the sites, with an average of 106 ± 22 nGy h− 1. These readings were slightly 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. The values, surpass the recommended limit value of 0.299×10− 3. While AEDE values were compliant with international recommendations 1mSv/y, ELCR values surpassed the average recommended limit. This suggests that the artisanal gold mining sites pose no immediate radiological health hazards due to the absorbed dose from BIR, yet the risk of cancer development over a lifetime of exposure remains considerably high. Thus, routine monitoring of BIR, radioactivity concentration in soil and rocks, and minimizing prolonged exposure are recommended to ensure the safety of workers and residents.