TITLE:
Radiological Assessment Due to Natural Radioactivity in Rocks and Associated Health Impacts in Chetambe Hills, Kenya
AUTHORS:
Mukanda Kere Wanyama, Michael Nakitare Waswa, Felix Omonya Wanjala, Nadir Omar Hashim
KEYWORDS:
Natural Radioactivity, Health Impact, Chetambe Hills
JOURNAL NAME:
Open Access Library Journal,
Vol.13 No.2,
February
2,
2026
ABSTRACT: A radiological assessment due to natural radioactivity in rocks and associated health impacts in Chetambe hills, Kenya has been done using NaI (TI) detector 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.