Measurements of Terrestrial Gamma Dose Rate Distributions along Idiroko Road, Ota, Ogun State, Nigeria: Health Implications on Roadside Dwellers

Abstract

An extensive study concerning the terrestrial gamma dose rates of the surface soils from Canaanland entrance Road, Ota to Eleha Complex along Idiroko Road, Ota has been carried out to cover the road running across both areas. The In-situ measurements of gamma dose rates and radionuclides were carried out using the Gamma detector (Super Spec RS 125). The result shows that the average outdoor gamma dose rate in the study area is 73.57 nGyh−1. The average values of the radionuclides obtained were 32.9 Bq/kg for 238U, 68.4 Bq/kg for 232Th, and 328.7 Bq/kg for 40K. The background dose rate of 113.3 nGy/h was found in station 9 and is twice higher than the recommended permissible limit of 59 nGy/h suggested by UNCSEAR, 2000, and ICRP, 1999, respectively. Results were obtained based on radiological parameters for the outdoor absorbed dose rate (Dout) with a mean value of 73.57 nGyh−1, the indoor absorbed dose rate (Din) with a mean value of 131.84 nGyh−1, the annual effective dose rate (AEDR) with a mean value of 0.74, the radium equivalent (Raeq) with a mean value of 156.0, the internal hazard index (Hin) with a mean value of 0.51, the external hazard index (Hex) with a mean value of 0.42 and the excess lifetime cancer risk (ELCR) with a mean value of 2.57. Similarly, results obtained from estimated radiological parameters show that the station with the highest value for radium equivalent (Raeq), external hazard index (Hex), internal hazard index (Hin), and annual effective dose rate (AEDR) is Station 9 at 237.91 Bq/Kg, 0.64, 0.72 and 1.13 mSvy−1 respectively while the station with the lowest value for radium equivalent (Raeq), external hazard index (Hex), internal hazard index (Hin) and annual effective dose rate (AEDR) is Station 17 at 85.58 Bq/Kg, 0.23, 0.27 and 0.40 mSvy−1 respectively. This study will serve as a guide on assessing the road construction materials on radioactive contents before application to reduce the exposure risks to the populace along the busy roadsides.