Atrazine toxicity in a native fish species Cnesterodon decemmaculatus: An initial assessment

Atrazine is a widely used pesticide with high persistence in the aquatic environment. This study aimed to assess the toxicity of an atrazine-based herbicide (Atramyl 90 WG®) in a native fish species, Cnesterodon decemmaculatus (Teleostei, Poeciliidae). Fish were exposed to a wide range of concentrations (0.5 - 100 mg/L) for acute (96 h) and subchronic (336 h) periods. Lethality, ethological alterations, neurotoxicity and genotoxicity were evaluated. The 96 and 336h-LC₅₀ were 74.03 and 13.61 mg/L, respectively. Fish speed decreased at 10 mg/L, but movement time was higher in the fish acutely exposed to 2 mg/L. Inhibition of acetyl and butyrylcholinesterase activity was recorded at 96 h in the highest concentration tested and increased butyrylcholinesterase activity in the lowest concentrations at both exposure times. Genotoxicity assessment showed increased notched and lobed nuclei frequency (1 - 10 mg/L). Finally, risk assessment determined potential chronic risk, providing valuable evidence of atrazine toxicity.