Risk assessment of heavy metals (Zn, Cu, Pb, and Ni) in the edible tissue of Oncorhynchus mykiss trout in the rivers of the southern Caspian Sea and the northern and southeast coast of Iran

The study aims to monitor and compare the concentration of heavy metals viz., zinc, copper, lead and nickel in the edible tissue of Oncorhynchus mykiss trout in the southern coast of Caspian Sea and the rivers of Khash city in the north-southeast coast of Iran. The average concentrations of zinc, copper, lead and nickel for the Stations in the north of Iran and the southeast of Iran were found 10.1, 8.1, 5.9, 4.7 and 6.5, 6.1, 3.5, 3.2 μg/g dry weight, respectively. Lead exceeded was the recommended standard limits by WHO, FAO, NHMRC, EC and UKMAFF. Based on the results, the average nickel metal was higher than the allowed concentration of international standards in all the studied stations, which indicates that more control should be done on the sources producing this metal around the target areas. furthermore, the daily intake (EDI) of the studied metals in all age groups were lower than the reference dose determined by the EPA organization and the tolerable intake (TI) provided by the FAO/WHO organization. The lowest frequency of daily consumption of Oncorhynchus mykiss was reported for the group of adult males and based on nickel metal (1.67 μg/g) and lead metal (1.14 μg/g) in the rivers located in the south of the Caspian Sea and the rivers of Khash city located in the southeast of Iran, respectively. The risk potential and risk index for non-cancerous diseases for all age groups in the muscle tissue of this fish was less than one, which shows that the consumption of this type of fish for human consumption will not cause a problem from the point of view of health and public health. However, management measures are necessary to prevent and control pollutants, especially in the southern shores of the Caspian Sea.