Assessing the Levels of Heavy Metals of Lead (Pb), Mercury (Hg), and Cadmium (Cd) in Native Fishes of the Saimareh River and Farmed Fishes in Ilam Province, Western Iran

Introduction: Heavy metals tend to accumulate in fish tissues, making fish effective biological indicators for environmental contamination. As fish occupy higher levels in the food chain and represent a key component of the human diet, monitoring their health is critical for food safety. This study aimed to evaluate the concentrations of lead (Pb), mercury (Hg), and cadmium (Cd) in native fish species from the Saimareh River and farmed rainbow trout in Ilam Province, western Iran. Methods: A total of 30 randomly selected samples, including native fish from the Saimareh River and farmed rainbow trout from Ilam Province, were collected for analysis. Samples were washed with distilled water, dried at 105°C for 24 hours, and weighed. Heavy metal concentrations were measured in dry weight using a PG Instruments AA990F atomic absorption spectrophotometer. Data were analyzed using STATA version 18. Results: In farmed rainbow trout, the mean concentrations of lead, mercury, and cadmium were 0.079, 0.033, and 0.037 mg/kg, respectively, with standard deviations of 0.05, 0.03, and 0.05. The average weight of these fish was approximately 1400 grams. In native fish, the mean concentrations of lead, mercury, and cadmium were 0.1, 0.023, and 0.013 mg/kg, respectively, with standard deviations of 0.03, 0.01, and 0.01. The average weight of native fish was about 1314 grams. The overall mean concentrations for lead, mercury, and cadmium across all samples were 0.089, 0.028, and 0.025 mg/kg, respectively, with an average weight of around 1350 grams. Overall, native fish had higher lead levels compared to farmed trout, while farmed trout showed higher concentrations of mercury and cadmium. Conclusion: The concentrations of Pb, Hg, and Cd in both farmed and native rainbow trout from Ilam Province were within acceptable safety limits, posing no significant health risk to consumers. These findings support the safety of consuming these fish species from a heavy metal contamination perspective.