Browsing by Author "Nyukuri, Robert Wanjala"

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    Environmental Radiation Exposure and Lifetime Cancer Risk at Lumoru Dumpsite, Western Kenya
    (Open Access Library Journal, 2025-11-18) Wanjala, Bilha; Nyukuri, Robert Wanjala; Kibe, Horace Eyinda; Makokha, John Wanjala
    This 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.
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    Radiological Hazard Assessment of Soils from Lumoru Dumpsite, Kenya
    (Journal of Multidisciplinary Engineering Science and Technology, 2025-10-05) Wanjala, Bilha; Nyukuri, Robert Wanjala; Kibe, Horace; Makokha, John Wanjala; Tsimbasi, Stanley
    This study assessed the radiological status of soils from Lumoru dumpsite, Kenya, by measuring activity concentrations of ⁴⁰K, ²³²Th, and ²³⁸U using a thallium-activated sodium iodide (NaI(Tl)) detector, and evaluating radium equivalent (Raeq), absorbed dose rates, and annual effective dose equivalents (AEDE). Average activities were 25 Bq/kg for ⁴⁰K, 57 Bq/kg for ²³²Th, and 7 Bq/kg for ²³⁸U, all below global average thresholds of 420, 45, and 35 Bq/kg, respectively. Raeq averaged 91 Bq/kg, absorbed dose rate 39.2 nGy/h, AEDEout 0.09 mSv/y, and AEDEin 0.20 mSv/y, all within recommended safety limits, although indoor exposure was higher. Spatial heterogeneity, particularly of ²³²Th, was linked to mineral-rich construction debris and uneven waste disposal. Patterns align with Machinjoni and Dandora dumpsites in Kenya, and sites in Dar es Salaam, Tanzania. Overall, Lumoru soils are broadly safe, but localized hotspots and elevated indoor exposure highlight the need for monitoring, improved waste management, and public awareness.