Radiological Hazard Assessment of Soils from Lumoru Dumpsite, Kenya

Abstract

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.