Heavy metal content of some leafy vegetable crops grown with waste water in southern suburb of Tehran-Iran

Abstract

Vegetables are the main source of many beneficial substances such as vitamins, minerals, fiber and various antioxidant compounds in human diet. Heavy metals contamination of vegetable crops is always of great concerns, which cause significant reduction in their quality. In this study, accumulation of heavy metals of Cd, Pb, Ni, Cr, Ar, Co, Cu and Zn in green leafy vegetable crops of coriander, garden cress, lettuce and spinach were evaluated under waste water irrigation in fields located in southern suburb of Tehran-Iran. In vegetable samples that were grown under waste water irrigation, the concentration of all heavy metals were significantly higher than WHO-FAO permissible limits for these heavy metals in edible plant tissues. Among the vegetable crops spinach and garden cress accumulated more of heavy metals compared to coriander and lettuce plants. Central leaves of lettuce, however, showed the lowest heavy metal content. This indicates that a national strategy is required toward more safe production of vegetable crops, or to change the cultivation program toward industrial crops in such polluted areas.