Determination of heavy metal residues in leafy vegetables from peri-urban agricultural lands

Urban Farm DB summary

Six heavy metals (lead, cadmium, chromium, nickel, copper, zinc) were measured by atomic absorption spectrophotometry in spinach, amaranth and fenugreek collected from four peri-urban sites around Dhaka, Bangladesh, during January-March 2024, where more than 2,000 hectares of vegetable land are irrigated with untreated industrial and domestic wastewater via canal networks. Lead in amaranth from the industrial-effluent site reached 0.94 mg/kg fresh weight, more than three times the WHO/FAO permissible limit of 0.30 mg/kg, while cadmium, chromium and nickel stayed within permissible limits at all sites and zinc, though highest in absolute terms (8.6-14.7 mg/kg), also remained within safe limits; contamination was highest at the industrial-effluent site and lowest at the borewell-irrigated control site, indicating a localized food-safety risk for consumers of peri-urban leafy greens grown with wastewater irrigation.