Document Type : Research Paper


Greenhouse Cultivation Research Department, Tehran Agricultural and Natural Resources Research and Education Center, AREEO, Varamin, Iran


In one study, nitrate and heavy metal concentrations in soil and lettuce in Varamin plain farms were measured. Average concentrations of nitrate, lead and cadmium in lettuce were 2756, 1.46 and 0.11 mg‌/‌kg fresh weight, respectively, which are 83, 630 and 10% higher than the standard declared by the National Standards Organization of Iran, respectively. The average concentrations of nitrate and total concentrations of lead, cadmium and nickel in the soil of lettuce fields were 27, 42, 0.64 and 42.5 mg‌/ kg, respectively. The concentrations of nitrate and lead were 35 and 180% higher than the allowable limits, respectively. Cadmium and nickel were within the permitted limits. To assess the risk of lettuce consumption, the risk index for non-cancerous diseases was used, which was less than one for all contaminants, which confirmed the risk of consumption. Accordingly, consuming 40 grams of lettuce per day does not pose a problem for the adult consumer. Bioaccumulation index was used to evaluate the uptake and accumulation of heavy metals in lettuce. For all the metals studied, this index was less than one. According to this study, the highest bioaccumulation factor belonged to the heavy metal cadmium, which indicates the tendency of lettuce to absorb and accumulate cadmium compared to other heavy metals. In order to reduce the concentration of nitrate and lead in the soil and prevent contamination of lettuce soils, it is recommended to avoid excessive use of fertilizers containing nitrogen and phosphorus and fertilizer application should be based on soil test.