Toxicity and Genotoxicity of Three Antimicrobials Commonly Used in Veterinary Medicine

The toxicity of chlortetracycline (CTC), oxytetracycline (OTC) and enrofloxacin (ENF) was tested on two green algal species: the international standard Pseudokirchneriella subcapitata and the native Argentine species Ankistrodesmus fusiformis. All three antibiotics inhibited the algal growth. The most sensitive species was P. subcapitata, for which the EC₅₀ for CTC, OTC and ENF were 1.19 ± 0.53, 0.92 ± 0.30 and 5.18 ± 3.80 mg L^-1, respectively. The EC₅₀ for A. fusiformis, were 3.23 ± 0.53, 7.15 ± 2.69 and 10.6 ± 1.28 mg L^-1, respectively. The genotoxicity of these veterinary antibiotics was also assessed using chromosome aberration (CA) and micronuclei (MN) induction in Allium cepa roots. Three concentrations were tested (0.1, 1 and 10 mg L^-1). Only ENF at 1 and 10 mg L^-1 showed any significant MN induction. These data revealed that CTC, OTC and ENF could cause toxicity on green algae, whereas ENF could cause genotoxicity on A. cepa plants.