Radiological and Health Risk Assessment of Naturally Occurring Radioisotopes and Toxic Metals in Sediments of Some Selected Beaches in Lagos State, Southwest Nigeria

The concentration of natural occurring radionuclides (²³⁸U, ²³²Th and ⁴⁰K) and heavy metals (Pb, Cd, Cr and Fe) was analyzed in Eleko and Elegushi beach sediments in Lagos, Nigeria with the aim of evaluating human health, pollution and radiological risk assessment using atomic absorption spectrophotometer (AAS) and high purity germanium (HPGe) γ-ray spectrometry techniques. Fourier infrared spectrometer and X-ray diffraction were used for sediment characterization and mineralogical analysis. The activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K ranged from 0.66 to 2.92, BDL-2.32, 0.08–1.58 and 0.26–1.17, 165.13–284.98 and 204.42–287.20 Bq kg⁻¹ for Eleko and Elegushi beach, respectively. The values obtained were below the specified worldwide average threshold value in all the samples. Three other radiological and health hazard indices such as absorbed dose rate (D_R), Radium equivalent (Ra_eq) and indoor excessive lifetime cancer risk (ELCR) were determined alongside the pollution and human health risk assessment of heavy metals. The indoor ELCR) for Elegushi beach sediment was higher than the worldwide average value set of 0.29 in one sample. The health risk assessment model was employed to calculate the carcinogenic and non-carcinogenic risks of heavy metals. Multivariate statistical analysis was used for the pollution sources identification. All the heavy metal concentrations in Eleko and Elegushi beach sediments were slightly higher than the local soil background values, indicating that this pollution might have resulted from anthropogenic inputs. Pollution assessment performed on the sample showed that the soil is strongly to moderately polluted and enriched with the heavy metals in the order: Fe > Cr > Pb > Cd mg/kg. Therefore, measures to reduce the human exposure to carcinogenic metals and radionuclides from the selected beaches must be implemented by the concerned stakeholders.