Human health risks assessment of vegetables irrigated with different water qualities

Abstract

Abstract Heavy metals in vegetables grown with contaminated irrigation water pose a significant threat to human health. This study evaluated heavy metal accumulation and the associated carcinogenic and non-carcinogenic health risks in vegetables irrigated with groundwater and untreated sewage water. The overall mean concentration of the analyzed heavy metals (Zn, Cu, Fe, Mn, Ni, Cr, Pb, and Cd) was 2.07-fold higher in sewage-irrigated vegetables than in groundwater-irrigated vegetables. Compared with the FAO/WHO permissible limits (Zn: 60.0, Cu: 30.0, Fe: 425.5, Mn: 500, Ni: 1.5, Cr: 2.3, Pb: 0.3, and Cd: 0.2 mg kg⁻¹), Cu, Ni, and Pb consistently exceeded the permissible limits under both irrigation regimes, while sewage irrigation further increased Zn, Fe, Cr, and Cd concentrations beyond the recommended limits in selected vegetables. Health risk assessment showed that the target hazard quotient (THQ) values for individual metals remained below the safety threshold, whereas the hazard index (HI) exceeded unity for spinach, mint, and fenugreek irrigated with groundwater and for all sewage-irrigated vegetables, indicating potential non-carcinogenic health risks associated with combined metal exposure. Furthermore, the target carcinogenic risk (TCR) values for Ni, Cr, and Cd exceeded the USEPA acceptable lifetime risk threshold (1 × 10⁻⁴), indicating potential carcinogenic risks associated with long-term consumption. Overall, these findings demonstrate that irrigation water quality plays a critical role in heavy metal accumulation and the associated health risks, highlighting the need for effective wastewater management and continuous monitoring of irrigation water, agricultural soils, and edible crops to protect food safety and public health.