Pollution sources identification, health, and radiological risk assessment of naturally occurring radioisotopes and heavy metals in waste dumpsites in Ijebu-Ode, Ogun State, Southwest Nigeria

Abstract

This study evaluates human health, pollution, and radiological risk assessment of potentially toxic metals (PTMs) (Pb, Cd, Cr, Ni, and Zn), radioisotopes (²³⁸U, ²³²Th, and ⁴⁰K) and its associated radiological indices from dumpsite soils in Ogun State, Nigeria, using a calibrated atomic absorption spectrophotometer (AAS) and highly shielded γ-ray spectrometry using NaI(TI) detector. Fourier transform infrared spectrometer (FTIR) complemented by X-ray diffraction (XRD) techniques were used to evaluate the mineralogical composition of the soils. Multivariate statistical analysis was used to apportion the source of PTMs and the radioisotopes. The mean concentration of Pb, Cd, Cr, Ni, and Zn obtained were 22.35, 17.95, 20.83, 19.02, and 75.88 mg kg⁻¹, respectively. The activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K ranged from 49.71 ± 16.3 − 314.15 ± 55.2, BDL − 87.54 ± 7.38, and BDL − 3721.3 ± 231.6 Bqkg⁻¹, respectively. The values obtained were above the global average value in most of the samples. According to the four-pollution and ecological risk assessment model, the dumpsite soils are strongly to low polluted and enriched with toxic metals in the order Zn > Cr > Pb > Ni > Cd. The estimated carcinogenic risk of the three carcinogenic PTMs for children and adults were higher than the acceptable limit (1 × 10⁻⁶). The results of the PCA and HCA results are consistent with the correlation coefficient analysis which showed that mixed natural, anthropogenic and lithogenic sources mainly from aggregation of lead-containing materials in the waste on the dumpsite, vehicular emission and industrial discharges are the main sources of Pb, Ni, and Cd in the three studied dumpsites. Thus, dumpsite soil poses great threat to health, increased pollution and enhances the radiological risk to the general population via human multiple exposure routes.

Keywords:

• Toxic metals
• radiological risk
• geo-accumulation
• mineralogical and carcinogenic risk

Acknowledgements

Authors wish to express appreciations Tai Solarin University of Education (TETFUND-IBR-Team 6) grant and Babcock University for providing the financial support through Babcock University Research Grant No: BU/RIIC/2018/016 to support this project. The authors also acknowledge the technical support received from Mrs Owoade and Mr Olubunmi Emmanuel Tope of the National Institute of Radiation and Protection, University of Ibadan, Ibadan during the analysis. All anonymous reviewers of this manuscript are well appreciated by the authors.

Disclosure statement

The authors declare no conflict of interest.