**7. Toxicological risk of amoxicillin**

In aquatic environments, few studies have reported the effects of amoxicillin in fish, probably because it is not described as a toxic substance important in the scientific literature reporting that the LC50 at 96 hours for *Oryzias latipes* was 1000 mg / L [35].

However, Andreozzi et al., in 2004, reported a high toxicity of amoxicillin in the blue green algae *S. leopoliensis* (NOEC = 0.78µg / L; LOECs = 1.56µg / L; EC*50* = 2.22µg / L) at 96 hours in concentrations between of 50 ng/L and 50 mg/L [66].

Furthermore, in 2013 at the University of Aveiro Portugal, Oliveira et al., measured the effects of amoxicillin in embryos and adults of *Danio rerio*; the effects found in embryos exposed with amoxicillin were premature hatching, malformations such as edema and deformities in the tail as well as abnormal development of fish. In the other hand, in adults exposed to amoxicillin, they found that amoxicillin produce the inhibition on the activity of the enzyme catalase (CAT) in certain tissues such as gills and brain, as well as produce an induction of the activity of the enzyme glutathione transferase (GTS) in tissues such as muscle, gills and brain, indicating that this antibiotic is capable of modifying the normal enzyme activity in fish [118].

In addition, Liu et al., in 2015, reported that the exposure of the photosynthetic cyanobacteria *Microcystis aeruginosa* to different concentrations of amoxicillin produced a significant increase in reactive oxygen species (ROS) and an increase in the activity of superoxide dismutase (SOD), peroxidase (POD) and glutathione-S-transferase (GST) as well as an increase in the content of glutathione (GSH) and malondialdehyde (MDA) [119].

Similarly, Li, et al., in 2007 reported that amoxicillin has the potential to produce genomic injuries in human deoxyribonucleic acid (DNA), possibly by intracellular induction of reactive oxygen species (ROS) [120].

Although the full extent and consequences of antibiotics in the aquatic environment are still largely unknown, their biological activity and toxicology is of concern [70]. However, despite being an issue of global concern, research regarding toxicological testing and biological activity is still insufficient and necessary.
