|
|
:
|
The concentration of nitrate and heavy metals in edible agricultural products is a global concern that has drawn significant attention. The presence of these contaminants at levels exceeding permissible limits in food products increases the risk of various cancers, neurological disorders, and methemoglobinemia in infants. Moreover, excessive concentrations of nitrate and heavy metals in agricultural products can pose challenges to export activities and result in substantial economic losses. Given that nearly 80% of nitrate and a significant portion of heavy metals in the human diet originate from agricultural products, assessing their concentrations in crops is of critical importance. Therefore, the present study aimed to evaluate the levels of heavy metals and nitrate in greenhouse-grown cucumber and tomato. A total of 450 samples, including 353 cucumber and 97 tomato samples, were collected and analyzed from major greenhouse production regions across different provinces of the country. Standard ISO 6635 methods were used to determine nitrate concentration, graphite furnace atomic absorption spectrometry (GFAAS) for cadmium and lead measurement, and hydride generation atomic absorption spectrometry (HG-AAS) for arsenic quantification. The results indicated that the mean nitrate concentrations in cucumber and tomato were 136.8 and 12.6 mg/kg, respectively, which were significantly lower than the maximum allowable limits set by the Iranian national standard. Based on the findings, 91.5% of cucumber samples and all tomato samples contained nitrate concentrations below the permissible limit. Similarly, the mean concentrations of cadmium, lead, and arsenic in cucumber samples were 0.0036, 0.0051, and 0.0214 mg/kg, respectively, while in tomato samples, they were 0.0029, 0.0045, and 0.0023 mg/kg, all of which were well below the Iranian national standard limits (0.05 mg/kg for cadmium and lead). The maximum detected concentrations of cadmium, lead, and arsenic were 0.0694, 0.0482, and 0.0715 mg/kg in cucumber and 0.0281, 0.0452, and 0.0192 mg/kg in tomato. Except for cadmium in cucumber, the maximum concentrations of these heavy metals were within acceptable limits. Furthermore, over 99% of cucumber samples and all tomato samples contained cadmium and lead concentrations below the national standard limits. Currently, no regulatory limit has been established for the maximum arsenic concentration in the examined agricultural products. However, its concentration in several samples exceeded that of cadmium and lead. Overall, the findings suggest that greenhouse-grown cucumber, tomato, and bell pepper produced in the country are generally within safe limits regarding nitrate, cadmium, lead, and arsenic residues. Nonetheless, the elevated nitrate levels observed in certain greenhouse cucumber samples warrant serious attention.
|