Investigation of heavy metal hazards Status and their potential health risks in vegetables Irrigated with treated wastewater in Oodi gardens

Abstract

This study was conducted in Oodi Village, Botswana to investigate human health risk associated with heavy metals: Mn, Fe, Cu, Ni and Zn intake via consumption of contaminated locally grown vegetable: Spinacia oleracea L. (spinach) collected from wastewater irrigated farms. The results showed that the highest concentrations of metals found in spinach at the study site were Fe and Mn whereas Ni and Cu were the lowest. Nickel was found to be 20 fold above the prescribed safe limit whereas all the other studied metals were below the prescribed safe limits by the international scientific expert committee administered jointly by the Food and Agriculture Organization of the United Nations and the World Health Organisation. Moderate to significant enrichment of Ni and Fe, respectively, were observed in spinach which suggested that the two metals were transferred from the soils to the edible parts of spinach. Based on the oral reference values for Mn, Fe, Cu, Ni and Zn, respectively, the estimated daily intake of metal values for Mn, Fe and Ni were greater than unity, suggesting that consumption of spinach irrigated with treated wastewater had the potential to pose health risk to consumers.