Radiogenic Components of Limestone Samples Collected from Ewekoro SW Nigeria: Implications for Public Radiological Health Risks Assessment and Monitoring

Kehinde David Oyeyemi; Ahzegbobor Phillips Aizebeokhai; Osagie Ayo Ekhaguere; Douglas Emeka Chinwuba; Charity Ada Onumejor

doi:10.3889/oamjms.2019.661

Radiogenic Components of Limestone Samples Collected from Ewekoro SW Nigeria: Implications for Public Radiological Health Risks Assessment and Monitoring

Open Access Maced J Med Sci. 2019 Oct 10;7(19):3287-3293. doi: 10.3889/oamjms.2019.661. eCollection 2019 Oct 15.

Authors

Kehinde David Oyeyemi¹, Ahzegbobor Phillips Aizebeokhai¹, Osagie Ayo Ekhaguere², Douglas Emeka Chinwuba¹, Charity Ada Onumejor¹

Affiliations

¹ Department of Physics, College of Science and Technology, Covenant University, Ota, Nigeria.
² Department of Physics, Federal University of Agriculture, Abeokuta, Nigeria.

Abstract

Aim: This research presents the radiogenic components in thirteen limestone samples from a quarry site in Ewekoro, southwestern Nigeria.

Methods: The distributions of natural radionuclides (²³⁸U, ²³²Th and ⁴⁰K) in the limestone samples were determined by gamma spectroscopy using a well-type thallium-doped sodium iodide detector. Also, estimated associated radiological hazards are presented and compared with the standard threshold values.

Results: The activity concentrations for ²³⁸U, ²³²Th and ⁴⁰K radionuclides range 18.09 ± 3.43-239.50 ± 25.74 Bqkg-1, 8.33 ± 0.83 - 360.01 ± 21.33 Bqkg-1 and 11.28 ± 0.81-735.26 ± 0.95 Bqkg-1 respectively. The radium equivalent activity concentration in the samples ranges 58.857-758.832 Bqkg-1 with samples S3, S4 and S11 values higher than the threshold limit of 370 Bqkg-1. Estimated dose rate and annual effective dose rate (AEDE) from the samples have ranges 28.754-330.917 nGyh-1 and 35.26-405.84 μSvy-1 respectively greater than the standard limit of 59 nGyh-1 and 70 μSvy-1 respectively for all samples except S9. The estimated external and internal indices are ranging 0.16 - 2.05 and 0.21 - 2.68 respectively, greater than permissible unity in some limestone samples such as S3, S4, S8, S11 and S13. Excess lifetime cancer risk was also computed using a life expectancy of 54.5 years. The results of higher radiological parameters in the limestone samples revealed that the miners have a high probability of contracting induced cancer.

Conclusion: A regular check-up is recommended for the miners and staffs within the quarry site. Also, the residents within the environs should be relocated far away from the quarry site, as the particulates from the limestone rock blasting could contaminate the air in the study area.

Keywords: Cancer risks; Ewekoro limestone; Medical geology; Natural radioactivity; Public health assessment; Radiogenic composition.