A radiological assessment due to natural radioactivity in rocks and associat-ed health impacts in Chetambe hills, Kenya has been done using NaI (TI) de-tector employing gamma ray spectrometry technique. The activity concentrations of 238U in the rock samples ranged from a minimum of 33 ± 1.65 Bq/Kg to a maximum of 119 ± 5.97 Bq/Kg with an average of 68 ± 3.23 Bq/Kg. The activity concentrations of 232Th varied from a minimum 15 ± 0.75 Bq/Kg to a maximum of 167 ± 8.39 Bq/Kg with an average of 72 ± 3.48 Bq/Kg while the activity concentrations of 40K varied from a minimum of 50 ± 2.5 Bq/Kg to a maximum of 2042 ± 6.43 Bq/Kg with an average of 866 ± 5.78 Bq/Kg. The averages for the three radionuclides all exceeded 33 Bq/Kg, 45 Bq/Kg and 420 Bq/Kg for 238U, 232Th and 40K respectively. The absorbed dose rate (Dr) ranged from a minimum of 33 ± 1.67 nGy/h to a maximum of 230 ± 11.53 nGy/h with an average of 111 ± 7.32 nGy. The AEDRin ranged from a minimum of 0.1 ± 0 mSv/y to a maximum of 0.8 ± 0.04 mSv/y with an average of 0.4 ± 0.02 mSv/y. AEDRout ranged from a minimum of 0.2 ± 0.01 mSv/y to a maximum of 0.5 ± 0.02 mSv/y with a mean of 0.2 ± 0.01 mSv/y. The radium equivalent for the study area varied from a minimum of 74 ± 3.74 Bq/kg to a maximum of 492 ± 24.61 Bq/kg with a mean value of 238 ± 6.34 Bq/kg which was below the world average value of 370 Bq/kg. The internal hazard indices varied from a minimum of 0.2 ± 0.01 mSv/y to a maximum of 1.3 ± 0.06 mSv/y with mean of 0.6 ± 0.02 mSv/y while external hazard indices varied from a minimum of 0.3 ± 0.01 mSv/y to a maximum of 1.6 ± 0.08 mSv/y with an average of 0.8 ± 0.03 mSv/y. The mean values of Hin and Hex were both below the unity. The ELCRout values varied from 0.2 ± 0.09 to 1.9 ± 0.08 with a mean of 0.9 ± 0.06 that was below the acceptable limit of 2.9 × 10？4. The values for ELCRin ranged from 0.4 ± 0.03 to 2.9 ± 0.07 with a mean value of 1.4 ± 0.05 which was equally lower than the world average of 2.9 × 10？4. Thus radiation exposure from the rocks does not pose a health risk to the general public.
Cite this paper
Wanyama, M. K. , Waswa, M. N. , Wanjala, F. O. and Hashim, N. O. (2026). Radiological Assessment Due to Natural Radioactivity in Rocks and Associated Health Impacts in Chetambe Hills, Kenya. Open Access Library Journal, 13, e14863. doi: http://dx.doi.org/10.4236/oalib.1114863.
Ugbede, F.O. and Akpolile, A.F. (2019) Determination of Specific Activity of 238U, 232Th and 40K and Radiological Hazard Assessment of Tuomo River Sediments in Burutu, Delta State, Nigeria. Journal of Applied Sciences and Environmental Management, 23, Article 727. https://doi.org/10.4314/jasem.v23i4.24
Omonya, W.F. (2021) Human Exposure and Associated Risks Due to Natural Radioactivity and Heavy Metals in Ortum, West Pokot County, Kenya. Doctoral Dissertation, Kenyatta Universi-ty.
Kinyua, R., Atambo, V.O. and Ongeri, R.M. (2011) Activity Concentra-tions of 40K, 232Th, 226Ra and Radiation Exposure Levels in the Tabaka Soapstone Quarries of the Kisii Region, Kenya. African Journal of Environmental Science and Technology, 5, 682-688.
Ribeiro, F.C.A., Silva, J.I.R., Lima, E.S.A., do Amaral Sobrinho, N.M.B., Perez, D.V. and Lauria, D.C. (2018) Natural Radioac-tivity in Soils of the State of Rio De Janeiro (Brazil): Radiological Characterization and Relationships to Geological Formation, Soil Types and Soil Properties. Jour-nal of Environmental Radioactivity, 182, 34-43. https://doi.org/10.1016/j.jenvrad.2017.11.017
Villa, I.M., Bonardi, M.L., De Bièvre, P., Holden, N.E. and Renne, P.R. (2016) IUPAC-IUGS Status Report on the Half-Lives of 238U, 235U and 234u. Geochimica et Cosmochimica Acta, 172, 387-392. https://doi.org/10.1016/j.gca.2015.10.011
Krieger, H.L. and Whittaker, E.L. (1980) Prescribed Procedures for Measurement of Radioactivity in Drinking Water (Vol. 1). Environmental Monitoring and Support Laboratory, Office of Research and Development, US Environmental Protection Agen-cy.
Nahar, A., Asaduzzaman, K., Islam, M.M., Rahman, M.M. and Begum, M. (2018) Assessment of Natural Radioactivity in Rice and Their Associated Population Dose Estimation. Radiation Effects and Defects in Solids, 173, 1105-1114. https://doi.org/10.1080/10420150.2018.1542696
Muchuma, K.F., Obando, J. and Kweyu, R. (2021) Land Use/Land Cover Change Detection Using Geospatial Techniques and Field Survey on Chetambe Hills in Bungoma County, Kenya. Middle East Journal of Applied Science & Technology, 4, 80-93.
United Nations Scientific Committee on the Effects of Atomic Radiation (2000) Sources and Ef-fects of Ionizing Radiation, United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2000 Report, Volume I: Report to the General As-sembly, with Scientific Annexes-Sources. United Nations.
IAEA (1997) Sampling, Storage and Sample Preparation Procedures for X Ray Fluorescence Analysis of Environmental Materials. Tech-nical Reports Series No. 486.
Nwankwo, C.U., Ogundare, F.O. and Folley, D.E. (2015) Radioactivity Concentration Variation with Depth and Assessment of Workers’ Doses in Selected Mining Sites. Journal of Radiation Research and Applied Sciences, 8, 216-220. https://doi.org/10.1016/j.jrras.2015.01.004
Al-Zahrani, J. (2017) Gamma Radiation Measurements of Naturally Occurring Radioactive in Igneous Rocks and Its Radiological Complications. World Journal of Nuclear Science and Technology, 7, 136-144. https://doi.org/10.4236/wjnst.2017.73012
Otwoma, D., Patel, J.P., Bartilol, S. and Mustapha, A.O. (2012) Radioactivity and Dose Assessment of Rock and Soil Samples from Homa Mountain, Homa Bay County, Ken-ya.
Jibiri, N.N., Alausa, S.K. and Farai, I.P. (2009) Assessment of External and Internal Doses Due to Farming in High Background Radiation Areas in Old Tin Mining Localities in Jos-Plateau, Nigeria. Radioprotection, 44, 139-151. https://doi.org/10.1051/radiopro/2009001
Gad, A., Saleh, A. and Kha-lifa, M. (2019) Assessment of Natural Radionuclides and Related Occupational Risk in Agricultural Soil, Southeastern Nile Delta, Egypt. Arabian Journal of Ge-osciences, 12, Article No. 188. https://doi.org/10.1007/s12517-019-4356-6
Beretka, J. and Mathew, P.J. (1985) Natural Radioactivity of Australian Building Materials, Industrial Wastes and By-Products. Health Physics, 48, 87-95. https://doi.org/10.1097/00004032-198501000-00007
Darwish, D.A.E., Abul-Nasr, K.T.M. and El-Khayatt, A.M. (2015) The Assessment of Nat-ural Radioactivity and Its Associated Radiological Hazards and Dose Parameters in Granite Samples from South Sinai, Egypt. Journal of Radiation Research and Applied Sciences, 8, 17-25. https://doi.org/10.1016/j.jrras.2014.10.003
Yu, F. and Turco, R.P. (2001) From Molecular Clusters to Nanoparticles: Role of Ambient Ionization in Tropospheric Aerosol Formation. Journal of Geophysical Research: Atmospheres, 106, 4797-4814. https://doi.org/10.1029/2000jd900539
Bolívar, J.P., Martín, J.E., Gar-cía-Tenorio, R., Pérez-Moreno, J.P. and Mas, J.L. (2009) Behaviour and Fluxes of Natural Radionuclides in the Production Process of a Phosphoric Acid Plant. Applied Radiation and Isotopes, 67, 345-356. https://doi.org/10.1016/j.apradiso.2008.10.012
El-Taher, A., Uosif, M.A.M. and Orabi, A.A. (2007) Natural Radioactivity Levels and Radiation Haz-ard Indices in Granite from Aswan to Wadi El-Allaqi Southeastern Desert, Egypt. Radiation Protection Dosimetry, 124, 148-154. https://doi.org/10.1093/rpd/ncm211
United Nations Scientific Com-mittee on the Effects of Atomic Radiation (2017) Sources, Effects and Risks of Ionizing Radiation, United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2016 Report: Report to the General Assembly, with Sci-entific Annexes. United Nations.
Akpanowo, M., Umaru, I., Iyakwari, S., Joshua, E.O., Yusuf, S. and Ekong, G.B. (2020) Determination of Natural Radioactivity Levels and Radiological Hazards in Environmental Samples from Artisanal Mining Sites of Anka, North-West Nigeria. Scientific African, 10, e00561. https://doi.org/10.1016/j.sciaf.2020.e00561
