Toxicity evaluation with Vibrio fischeri test of organic chemicals used in aquaculture

The evaluation of acute toxicity by Vibrio fischeri test for different organic chemicals (antibiotics, pesticides, therapeutants, herbicides) commonly applied in aquaculture and a degradation product of surfactants, 4-nonylphenol, is presented in this work. Simazine, atrazine, emamectin benzoate and leucomalachite green have no toxic effects on V. fischeri at the concentration tested (up to 6 mg l−1) which correspond to the maximum water solubility. Ciprofloxacin, terbutryn and deltamethrin, caused inhibition effects of 28%, 22% and 30% at concentrations up to 5 mg l−1. Toxic effects were not observed in the case of flumequine and oxolinic acid at the maximum concentration tested (0.189 mg l−1). According to the toxicity categories established in the EU legislation, ciprofloxacin, terbutryn and deltamethrin could be considered non-harmful for V. fischeri. Malachite green and 4-nonylphenol are “very toxic to aquatic organisms” (EC50,30min = 0.031 mg l−1 and 0.48 mg l−1, respectively). Carbaryl is “toxic to aquatic organisms” (2.4 mg l−1). and glyphosate is harmful to V. fischeri (EC50,30min = 44.2 mg l−1). The matrix effect was evaluated comparing the toxicity measurements of the target compounds solubilized in seawater and distilled water. Malachite green, 4-nonylphenol and glyphosate, showed higher toxicity in distilled water than in seawater. Carbaryl was more toxic in seawater. All the compounds tested in seawater were not harmful at concentrations of ng l−1 (10 and 50). However, 4-nonlylphenol and malachite green may act as toxic compounds in the environment at a low ppb level, since both may be detected in water at this concentration level.