Background and purpose: Pesticides are used in agriculture to increase crop production. Organophosphate pesticides are used more than other pesticides since they are inexpensive and more influential on a wide range of pests. Fish containing pesticides have significant human health consequences. In this study, three types of most consumed fish in the Caspian Sea were evaluated for Diazinon organophosphate levels.

Materials and methods: Twenty seven samples of three species of fish (Rutilus frisii kutum, Cyprinus carpio, leaping mullet) were randomly collected from three stations in central coast of Caspian Sea. The samples were digested and extracted and Diazinon residues were extracted. Diazinon concentrations were determined using a Gas chromatography (GC-MS) method. All results were statistically analyzed using One-way analysis of variance (ANOVA) and t-test. Then Tukey-post test was applied to compare the pesticide residues levels in the samples.

Results: Diazinon was found detected in all samples. The leaping mullet samples collected from Babolsar and Khazarabad stations showed higher levels of Diazinon (55.25±48.03, 55.17±52.5 µg/kg, respectively) compared to others. ANOVA did not show any significant difference between all three types of fish in concentration of diazinon (P=0.33).

Conclusion: In this study, Diazinon was found at a high level in all samples (115.78 µ µg/kg) in leaping mullet sample from Babolsar region. However, it was not more than acceptable level determined by WHO (0.01 mg/kg). Hence, the three investigated species fish are considered to be safe for human consumption.