A comparative study of human health risks via consumption of food crops grown on wastewater irrigated soil (Peshawar) and relatively clean water irrigated soil (lower Dir).

Food crops irrigated with wastewater are mostly contaminated with heavy metals and considered as a main pathway for human exposure. In this study, soil and food crops samples were collected from wastewater irrigated soils, background and relatively less polluted areas. Results of the sequential extraction and total metals concentrations in soils indicated that wastewater irrigation has significantly increased (p > or = 0.001) the bioavailable and total metal contents in wastewater irrigated soil as compared to background and control soils. Heavy metal concentrations in the food crops grown on wastewater irrigated soil were higher than those grown on background and control soils but were found within WHO/FAO permissible limits except for Zn. Health risk index values were less than 1 for both control and wastewater irrigated soils (except Mn). However, the food crops such as Brassica rapa, Spinacia oleracae L., Lycopersicum esculantum, Mentha viridis, Coriandum sativum and Lactuca sativa grown on wastewater irrigated soil can pose health risks because of the high concentration of Mn.