Developmental Effects of Amoxicillin at Environmentally Relevant Concentration Using Zebrafish Embryotoxicity Test (ZET)

Abstract: Amoxicillin (AMX) is an antibiotic that has been added to the watch list of substances by the European Union, through the Water Framework Directive (WFD; 2000/60/EC) and its daughter regulation (Decision 2018/840) for which monitoring data have to be gathered with a possibility for future regulation. Previous studies have demonstrated that this antibiotic generates toxic effects, among which oxidative stress in aquatic organisms is noteworthy. The aim of this study was to evaluate the effect on embryonic development and the teratogenic effects induced by AMX at environmentally relevant concentrations in oocytes and embryos of Danio rerio. Furthermore, oxidative stress biomarkers were evaluated at 72 and 96 hpf. The LC₅₀ was 14.192 μgL⁻¹, EC₅₀ was 7.083 μgL⁻¹, and TI was 2.003. Biomarkers of cellular oxidation and antioxidant enzymes were modified in a concentration-dependent way with respect to the control group (p<0.05). The main malformations identified were tail malformation, pericardial edema, yolk sac malformation, scoliosis, pectoral fin absence, and no hatching. The results allow us to conclude that AMX at environmentally relevant concentrations is capable of inducing embryotoxic and teratogenic effects and oxidative damage. This compound represents a risk to aquatic organisms such as Danio rerio. Clinical Trials Registration: Not applicable.