Wanjala, BilhaNyukuri, Robert WanjalaKibe, Horace EyindaMakokha, John Wanjala2026-05-052026-05-052025-11-18Wanjala, B., Nyukuri, R.W., Kibe, H.E. and Makokha, J.W. (2025) Environmental Radiation Exposure and Lifetime Cancer Risk at Lumoru Dumpsite, Western Kenya. Open Access Library Journal , 12: e14461. https://doi.org/10.4236/oalib.11144612333-97212333-9705http://erepository.kibu.ac.ke/handle/123456789/11655Journal ArticleThis study quantified the activity concentrations of natural radionuclides 238U, 232Th, and 40K in soils from the Lumoru Dumpsite, Bungoma County, Kenya, using a NaI (Tl) gamma spectrometer. The mean concentrations were 7 ± 0.4 Bq/kg for 238U, 57 ± 2.0 Bq/kg for 232Th, and 25 ± 1.3 Bq/kg for 40K. From these values, the absorbed dose rate was estimated at 39 ± 3.4 nGy/h, the outdoor annual effective dose equivalent at 0.09 ± 0.01 mSv/y, and the radium equivalent activity at 91 ± 3.4 Bq/kg. The hazard indices (Hex = 0.25 ± 0.01; Hin = 0.28 ± 0.01) were all within international safety limits, while the mean excess lifetime cancer risk was 0.30 ± 0.03 × 10−3. Compared with similar dumpsites in Kenya and across Africa, Lumoru exhibited lower activity concentrations and radiological risks than Machinjoni, Nigerian, and Ukrainian landfills, though its risks remain comparable to food-chain pathways in Bungoma. These findings establish Lumoru as a moderately impacted site and provide a critical baseline for monitoring cumulative exposures from environmental and household sources in Western Kenya.enNatural Radionuclides238U232Th40KAnnual Effective DoseHazard IndicesExcess Lifetime Cancer RiskLumoru DumpsiteBungomaKenyaArticle