Assessment of potentially toxic elements and health risks of agricultural soil in Southwest Riyadh, Saudi Arabia

The rise of emerging pollutants in the environment as a result of economic growth poses a worldwide challenge for the management of environmental and human health. The objective of this study was to assess the presence of potentially toxic elements (PTEs) in the agricultural soil of southwest Riyadh, Saudi Arabia, and to evaluate the potential health risks associated with these elements. Soil samples were collected from 31 farms, and the concentrations of As, Pb, Cu, Ni, Zn, and Fe were analyzed using inductively coupled plasma-atomic emission spectrometry. Various contamination and health risk indices, along with multivariate analyses, were employed in the evaluation. The mean concentrations of PTEs (mg/kg) followed the order: Fe (15,556) > Zn (53.36) > Ni (21.78) > Cu (11.92) > Pb (10.42) > As (2.64). The average PTE concentrations were found to be lower than background levels and the world-soil average. Contamination indices indicated that the studied soil was moderately enriched and contaminated for As, slightly enriched for Zn and Ni, and not enriched for Cu and Pb. This suggests that the PTEs in the soil do not pose a significant threat, although some individual samples exhibited significant enrichment for Zn and Pb. Multivariate analyses suggested a geogenic source for the PTEs, with some contribution from anthropogenic factors for As, Zn, and Pb. The average hazard index values ranged from 0.000293 (Zn) to 0.030561 (Fe) for adults and from 0.002726541 (Zn) to 0.284670158 (Fe) for children, indicating no significant non-carcinogenic risk to the population in the study area. Additionally, the Lifetime Cancer Risk values for adults and children ranged from 6.94 × 10−6 to 6.46 × 10−5 for As and from 7.13 × 10−8 to 6.65 × 10−7 for Pb, suggesting acceptable or tolerable carcinogenic risk and no significant health hazards.