Resumo

MARIN MENDEZ, Gira Alejandra; CHACON NOVOA, Roberto Andrés; CESPEDES RUBIO, Ángel Enrique  e  RONDON BARRAGAN, Iang Schroniltgen. Toxicity of trichlorfon exposure using an experimentally induced model with Silver Pacu (Piaractus brachypomus). Ces. Med. Vet. Zootec. [online]. 2014, vol.9, n.2, pp.190-202. ISSN 1900-9607.

The trichlorfon (TCF) is an organophosphate insecticide widely used in agricultural systems and livestock production. However, its indiscriminate use has generated serious problems affecting organisms in aquatic ecosystems that are not direct targets of the chemical. Therefore, the aim of this study was to assess acute toxicity (LC₅₀) and chronic subletal of TCF in cachama blanca fingerlings (Piaractus brachypomus). Acute toxicity was evaluated at 96 hours, using four concentrations of TCF (0.01, 0.1, 0.25, 0.5 mg/L) and a control group, each group consisted of 8 animals (2.5 ± 0.5 g). The LC₅₀ value calculated using the Trimmed Spearman-Karber software was 0.18 mg/L (p<0,05). The evaluation of the effect of chronic exposure to sublethal TCF on the immune response of P. brachypomus was performed by testing respiratory burst, showing significant increase in animals exposed to 0.029 mg / L during the first 10 days of exposure compared to control. Likewise, the plasma bactericidal capacity was evaluated in TCF exposed fish using Aeromonas hydrophila, finding greater of colony forming units on day 20 and 30 of exposure to the concentration 0.018 mg/L as opposed to the control. In addition, a histopathological study was performed, finding gill lesions compatible with epithelial cell hypertrophy and lamellar detachment in fish exposed to 0,05 mg/L on day 30 of exposure. This work showed the cachama blanca as a biomarker in contaminations associated with these xenobiotics.

Palavras-chave : Fish; organophosphate; pesticide; toxicity; trichlorfon.

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