Investigating the Amount of Heavy Metals in Different Parts of Some Consumable Vegetables in Karaj City

Heavy metals are seriously dangerous for the human body and their accumulation in the body can cause pathological changes in the organs and this can result in cardiovascular, liver and bone diseases, and even cancer. Human is exposed daily to these pollutants via consumption of food and water.
Considering the cumulative properties of these metals in plant organs, the amount of Cr, Mn, and Fe in soil and leaf, stem, and root tissues of cabbage, lettuce, spinach, and onions in Karaj City were investigated. For this purpose, 15 samples were randomly collected from each part of the plants, and then, the density of heavy metals was measured via atomic absorption spectrometer after cleansing, grinding, drying, and acid digestion. The data were then analyzed using SPSS software.
It was found that leaves of spinach, cabbage, lettuce, and onion have higher concentrations of Cr, Mn, and Fe rather than their stems and roots. The roots of plants contain the least densities of metals. Moreover, concentrations of Fe, Cr, and Mn in soil were 11.87, 3.99 and 17.78 mg/kg, respectively. This was due to the high transportation of these metals to air-related parts of the plant like leaves. This research also showed that the densities of Cr, Mn, and Fe in leaves of studied spinach, onion, cabbage, and lettuce exceeded the FAO/WHO standard limitations (0.15, 0.3, and 0.3 mg/kg for Cr, Fe and Mn, respectively).
Due to the high concentrations of Cr, Mn, and Fe in studied vegetables in Karaj City, the consumption of these kinds of vegetables by citizens must be taken into consideration by regulatory agencies.