Determination of potentially toxic elements in soil, river water and spinach samples from the Lesser Himalaya (Pakistan) by ICP-OES: Implications for food security and public health

Abstract

Potentially toxic element (PTE) contamination of soils, irrigation water and vegetables poses food insecurity and human health concerns. This study investigated PTE contamination in water, soil, and spinach from two agricultural areas, Baffa and Ichrian, in the Mansehra District of Pakistan. The cadmium (Cd), chromium (Cr) and lead (Pb) contents of the samples were determined using inductively coupled plasma-optical emission spectrometry (ICP-OES) to evaluate their contamination status and ecological risks, plant bioaccumulation factor (PBAF) and potential human health risks. The results showed that Baffa's water had higher Cd (0.77–2.93 µg L^–1) and Pb (0.10–10.98 µg L^–1) levels than Ichrian’s water, but was safe for drinking and irrigation according to guideline values. Soil concentrations of Cd, Cr, and Pb were higher in Baffa, with Cd levels surpassing global upper continental crust values in all samples and exceeding the recommended levels set by the Food and Agriculture Organization/World Health Organization (FAO/WHO) in 33 % of samples. Furthermore, the average Cd concentration in Baffa soils exceeded the European soil average. However, spinach PTE levels did not exceed guideline values. Contamination and ecological risk indices indicated moderate pollution in Baffa and low pollution in Ichrian, presenting moderate and low potential ecological risks, respectively. Based on plant bioconcentration factor analysis, minimal (<0.2) metal accumulation was recorded in spinach. The estimated daily intake (EDI) values revealed a metal ranking of Cr > Pb > Cd, with all values falling below the tolerable daily intake (TDI) levels, indicating no potential health risks. Target hazard quotient (THQ) and hazard index (HI) were below threshold level (<1), indicating no non-carcinogenic risk to the population. Although PTE levels in spinach were within safe limits, our findings emphasize the need for ongoing monitoring of PTE concentrations in soils and a broader range of vegetables, as cumulative exposure through consumption of multiple types of vegetables could exceed threshold limits, posing potential health risks.