The concentration of cadmium, lead, and nitrate in tomato and onion from Fars province, Iran: a health risk assessment study

As the most abundant element in the atmosphere, nitrogen is a vital nutrient for plant growth. Nitrate is the main form of nitrogen uptake by plants. Although nitrates are relatively low in toxicity, if they accumulate in vegetables can be converted to nitrite and nitrous acids in the human body. This study collected 83 tomato and 40 onion samples cultivated in Fars province; then nitrate concentration was determined by an HPLC, also cadmium (Cd) and lead (Pb) concentration by an atomic absorption instrument. The Cd and Pb in samples were below the detection limits (LOD) of the techniques used. However, the nitrate concentration in tomato and onion samples from Fars province varied from 0 to 154.40 mg/kg and 0 to 317.20 mg/kg, respectively. The mean chronic daily intake (CDI) for tomatoes in children, women and men was 0.1188, 0.0375, and 0.0366, and for onions, 0.1899, 0.0605, and 0.0447, respectively. On the other hand, the 95th percentile hazard index in the probabilistic method for nitrate for children, women, and men were 0.81, 0.26, and 0.21, respectively. Also, nitrate concentration in onion for children and tomatoes in both men and women was identified as the most considerable parameter in assessing the non-carcinogenic risk of nitrate. This study showed that the amount of nitrate in some samples of tomatoes and onions was not within the acceptable international standard limits. Therefore, monitoring the nitrate concentration in these high-consumption vegetables is crucial.