Impact of industrial wastewater on heavy metal contamination in agricultural soils and associated health risks

This study evaluated heavy metal contamination in agricultural soils irrigated with untreated industrial wastewater from two major industrial zones in Lahore, Pakistan. Soil samples from cucumber (S1), wheat (S2), green chili (S3), potato (S4), ladyfinger (S5), and tomato (S6) field were collected from six industrial sites. Heavy metals including cadmium (Cd), chromium (Cr), lead (Pb), and nickel (Ni) were analyzed using atomic absorption spectroscopy (AAS). Various indices such as the contamination factor (CF), potential contamination index (PCI), geo-accumulation index (Igeo), potential ecological risk index (PERI), and human health risk assessment (HHRA) were employed to assess pollution levels and associated health risks. Results showed that most heavy metal concentrations were within permissible limits set by the European Union (EU) and World Health Organization (WHO), except at certain sites. For instance, Cd at Site 4 was 0.085 mg/kg (above EU/WHO guideline of 0.05 mg/kg), Cr exceeded the limit (0.10 mg/kg) at all sites except Site 1, and Pb levels were higher than (0.1 mg/kg) at all sites except Sites 1 and 4. Ni concentrations surpassed guidelines (0.14 mg/kg) at all sites except Sites 1 and 2. Among all elements, Cr exhibited the highest contamination factor. The PCI results also indicated that Cr and Ni posed significant contamination potential. All soil samples exhibited PERI values exceeding 600, indicating a very high ecological risk. HHRA analysis showed that children were more vulnerable than adults to all four heavy metals, as per USEPA guidelines. This study provides a comprehensive, multi-index assessment of industrial wastewater-induced soil pollution and its implications for human health. Unlike previous research that focused on individual contaminants, this work integrates ecological and human health risk assessments, offering novel insights for urban environmental protection and sustainable agricultural practices.