Ecotoxicological assessment of amoxicillin trihydrate: Stability, solubility, and acute toxicity for Oreochromis niloticus, Lemna minor, and Daphnia magna

Abstract

Among the different pharmaceuticals present in water as micro-contaminants, antibiotics are considered an important risk group for the aquatic ecosystem, since their increasing use in human and veterinary medicine could affect the diversity of microorganism communities. This study aims to classify the acute toxicity of amoxicillin trihydrate for organisms of different trophic levels of aquatic biological chains, represented by Oreochromis niloticus (fish), Lemna minor (macrophyte) and Daphnia magna (microcrustacean). For this purpose, amoxicillin trihydrate degradability in water as well as changes in physicochemical characteristics are focused herein. Initial tests were performed to validate the assay, including drug dissolution in M4 medium, drug degradation in various culture media, sensitivity of experimental organisms as well as preliminary drug intoxication test. Upon validation tests, 2.6 g L−1 amoxicillin was determined as the concentration to evaluate the toxicity factor. Static (48 h) and semi-static (168 h) assays were performed. Therefore, amoxicillin trihydrate did not have an acute toxic effect at the concentration of 2.6 g L−1 under the experimental conditions applied to the species Lemna minor, Daphnia magna and Oreochromis niloticus. demonstrating the very low acute toxicity to aquatic organisms at different trophic levels.