Acute toxicity of deltamethrin to Amazonian freshwater fish

Abstract

This study determined the acute toxicity to deltamethrin for five Amazonian fish species: Carnegiella strigata, Colossoma macropomum, Corydoras schwartzi, Hemigrammus rhodostomus, and Paracheirodon axelrodi. Toxicity tests (LC50-96 h) were conducted by exposing the different fish species to five concentrations of commercial deltamethrin (Poison®-10 g/L), ranging from 1.3 to 2.2 µg a.i/L, following OECD guidelines for testing the acute effects of chemicals on aquatic organisms. Sensitivity of Amazonian fish was compared with data from other fish species obtained in the literature, using the species sensitivity distribution (SSD) approach. Deltamethrin was highly toxic to the fish studied, with LC50-96 h values ranging from 6.69 to 23.63 μg/L, apart from C. schwartzi, where the LC50-96 h value was 183.51 μg/L. Colossoma macropomum, one of the most valuable commercial fish in the Amazon, was the species most sensitive to deltamethrin. Differences in sensitivity to deltamethrin between Amazonian and temperate fish were not evidenced. A Predicted No Effect Concentration (PNEC) of 0.16 µg/L was calculated from the SSD curve. Deltamethrin was found to be highly toxic to most of the Amazonian fish species evaluated. Data on the concentrations of this pyrethroid in Brazilian waters suggest risks to the fish community. However, a water quality standard for deltamethrin was not established within the Brazilian legislative framework.