Investigation and risk assessment of heavy metals in walnuts produced in Toyserkan County, Hamedan, Iran

Background: Walnut is the most widely distributed tree nut worldwide and has been consumed as a nutrient-rich food for many years. The aim of this study was to investigate the concentration and risk assessment of heavy metals in walnuts produced in Toyserkan County, Hamedan Province. Materials and Methods: 45 walnut samples were collected from 3 cities and 15 villages of Toyserkan county by systematic-random method. After preparation and digestion of the samples by acid method, the concentration of heavy metals was measured by atomic absorption spectrometry. EDI, HQ and HI indices were used for risk assessment. Results: The average concentrations of heavy metals Cu, Zn, Fe, Mn, Na and K were 16.12, 47.43, 88.53, 44.25, 280.9, and 182.6 mg/kg, respectively. The results of the Kruskal-Wallis and Mann-Whitney tests showed that the difference between the mean concentrations of iron, manganese, sodium, and potassium was significant with the change in location. Spearman correlation test also showed that there is a significant correlation between heavy metals and mineral elements. The EDI and HQ index for each of the studied heavy metals and the HI index for the total of heavy metals in both age groups were less than 1 and within the permissible limit. Conclusion: The average concentration of copper and manganese was higher and zinc was lower than the amount recommended by FAO and World Health Organization. Compared to other different countries in the world, the concentration of iron, zinc, manganese and sodium was higher and potassium was lower. The heavy metals studied were considered to be non-carcinogenic for both adults and children and did not pose a significant risk of adverse health effects. Special attention to the contamination of soil and agricultural products, especially walnuts, with heavy metals and the control and reduction of the entry of these pollutants through human sources such as chemical fertilizers and pesticides in Toyserkan County is necessary.