Pollution and Health Risks of Potentially Toxic Elements in Road Dust from Ibadan, Nigeria

In this study, the pollution and health risks of potentially toxic elements (PTEs) in dust from selected roads in Ibadan metropolis, Southwestern Nigeria, were assessed. Sixty-three road dust samples (including control soils) were collected and analyzed for PTEs [zinc (Zn), copper (Cu), nickel (Ni), lead (Pb), cadmium (Cd), and vanadium (V)] using Microwave Plasma Atomic Emission Spectrometry. HM data underwent descriptive and inferential statistical analysis. Pollution Index (PI), Ecological Risk Index (ERI), Numerov Integrated Pollution Index (NIPI), and Enrichment Factor (EF) were evaluated. The health risks of PTEs were assessed for non-carcinogenic hazard quotient (HQ), hazard index (HI), and cancer risk (CR). The concentration ranges of PTEs (mg kg-1) in dust samples were Zn (100.50 - 4.67), Cu (197.33 - 1.63), Ni (35.83-< 0.10), Pb (47.83-2.50), Cd (30.67-0.50), and V (275.33 - 75.83). The concentrations of Cu and Cd exceeded the WHO permissible limits of 100 and 0.8 mg kg-1, respectively. Principal component analysis indicated vehicular emissions as the likely of PTEs in road dust. The PI revealed high pollution levels for V, Zn, Cu, and Pb, while Cd and Ni showed low-to-moderate pollution levels. Vanadium showed the ERI value exceeding the threshold limit of 150, while Zn and V indicated the NIPI values higher than the acceptable limit of 3.0. The low EF (<5.0) values of Ni, Pb, and Cd, and high EF (>5.0) of Cu, Zn and V established deficient and high enrichments, respectively. At some sampling sites, HQs > 1.0 were observed for Pb, Cd and V, indicating adverse health effects. The CRs of Ni and Cd were higher than the acceptable limit of 1.0 x 10-4, suggesting a potential for cancer development. This study revealed that metals in road dust could pose carcinogenic and non-carcinogenic risks to both children and adults.