Radionuclides Concentrations in Soil and Excess Lifetime Cancer Risk Due to the Gamma Radioactivity in Kogi Central District, Kogi State, Nigeria

Abstract

The activity concentrations of the natural radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K were measured for eight soil samples collected from different location of high activity across the district, using high resolution gamma ray spectroscopy. The concentration of  ²²⁶Ra in the soil in Kogi central district varied from 27.99143.1965 to 73.50540.7592 Bq/kg with average of 48.91282.4373 Bq/kg. The minimum value was obtained in Itakpe1 and a maximum value at Steel complex. For ²³²Th, the measured activity ranged from 32.51682.0446 to 128.80902.0053 Bq/kg with an average of 90.06062.0495 Bq/kg. The minimum value was also obtained in Kuroko and a maximum value obtained at Itakpe2. The activity concentration of ⁴⁰K ranged from 114.38843.0568 to 448.490410.1357 Bq/kg with an average of 254.41764.6723 Bq/kg. The minimum value obtained in Kuroko and a maximum value obtained at Itakpe1. The calculated radium equivalent activity () values are within and less than the permissible limits of 370 Bq/kg and the determined values of external and internal hazard index are less than unity, however, all the values of gamma representative index is greater than unity except at Kuroko. The calculated absorbed dose rates due to the presence of ²²⁶Ra, ²³²Th and ⁴⁰K in each of the soil samples varied from 48.327 to 119.794 (nGy/h), with an average value of 91.446 (nGy/h). this is about 2 times higher than the world average of 43nGy/h. The calculated annual effective dose rate in all the soil samples varies from 0.059 mSv/y to 0.146 mSv/y with an average value of 0.11 mSv/y and it remains within the criterion of 1.0 mSv/y recommended. The range of Excess Lifetime Cancer Risk (ELCR) is 0.207 to 0.511with an average value of  which less than world average value of  .