Unveiling sources, contamination, and eco-human health implications of potentially toxic metals from urban road dust

To investigate the pollution characteristics, ecological and health risks assessment, and source apportionment of potentially toxic metal(loid)s (PTMs) in urban road dust, 140 dust samples collected from eight renowned roads of city Lahore, Pakistan. The geo-accumulation index (I_geo) and enrichment factor (EF) were used for pollution characteristics, modified ecological risk index used for ecological risk assessment, the USEPA models used for health risk assessment, and multivariate statistical analyses were used for source apportionment of PTMs. The ranges of average concentrations (mgkg^-1) in road dust Cd, Hg, Mo, and Pb were 1.91 (CR) to 3.35 (BR), 11.7 (JR) to 29.3 (MuR), 452 (JR) to 1115 (MuR), and 36.9 (MaR) to 110 (BR), respectively, which were several times higher than reference values. The Cd was moderate to highly polluted in road dust with highest I_geo=2.58 from MuR and EF = 26.9 from CR. Whereas Hg and Mo were categorized as extremely polluted PTMs with mean I_geo and EF values beyond the uppermost level (class 5). The road dust collected from mall road (MaR) was polluted with high levels of most of the PTMs among other roads. The adjacent areas of roads were at extreme ecological risks due to Cd, Hg, and Mo pollution. The employed statistical methods proved that PTMs pollution was induced severely by industrial, exhaustive, and non-exhaustive vehicular emissions in road dust. The Hg pollution in road dust was causing potential non-carcinogenic risks in children with HQing and HI higher than 1. No carcinogenic risk was found for both adults and children. The study helps to create awareness about PTMs' pollution and associated health concerns among public.