Hazard assessment of commonly used agricultural antibiotics on aquatic ecosystems Sujung Park Æ Kyungho Choi Accepted: 3 April 2008 / Published online: 1 May 2008 Ó Springer Science+Business Media, LLC 2008 Abstract In this study, eleven commonly used antibiotics including sulfonamides, tetracyclines, aminoglycosides, fluoroquinolones, and beta-lactams were evaluated for their acute and chronic aquatic toxicities using standard test organisms e.g., Vibrio fischeri, Daphnia magna, Moina macrocopa, and Oryzias latipes. Among the antibiotics tested for acute toxicity, neomycin was most toxic fol- lowed by trimethoprim, sulfamethoxazole and enrofloxacin. Sulfamethazine, oxytetracycline, chlortetracycline, sulfadi- methoxine and sulfathiazole were of intermediate toxicity, while ampicillin and amoxicillin were least toxic to the test organisms. There were no trends in sensitivity among test organisms or among different classes of the antibiotics. Only the beta-lactam class was the least toxic. In chronic toxicity test, neomycin affected reproduction and adult survival of D. magna and M. macrocopa with low mg/l levels exposure. Predicted no effect concentrations (PNECs) were derived from the acute and chronic toxicity information gleaned from this study and from literature. When the PNECs were com- pared with measured environmental concentrations (MECs) reported elsewhere for the test compounds, hazard quotients for sulfamethoxazole, sulfathiazole, chlortetracycline, oxy- tetracycline, and amoxicillin exceeded unity, which suggests potential ecological implication. Therefore, further studies including monitoring and detailed toxicological studies are required to assess potential ecological risk of these fre- quently used veterinary antibiotics. Keywords Veterinary antibiotics  Hazard assessment  Acute toxicity test  Chronic toxicity tests  Predicted no effect concentration Introduction A variety of drugs and feed additives are approved for use in livestock farming and companion animal medicine (Boxall et al. 2002; Sarmah et al. 2006). Among the drugs employed in agriculture, antibiotics are among the most widely used for animal health and management. Their major use in livestock farming is not only to treat diseases but also to enhance growth and feed efficiency in livestock (Levey 1992). Antibiotics play a major role in modern agriculture and livestock industries and their use has been on the rise in many parts of the world (Sarmah et al. 2006). For example, annual consumption of antibiotics in 1997 in Denmark exceeded more than 150 ton, out of which [ 100 ton was used as growth promoters. In US, there was an increase of nearly 80-fold in antibiotic usage for growth promotion within a span of four decades (Jensen 2001). Approximately 23,000 ton of antibiotics are produced each year and about 40% of the total are used in agriculture (Nawaz et al. 2001). A similar increase in antibiotic usage has been observed in several other countries, such as Aus- tralia, New Zealand, and EU (Sarmah et al. 2006). In Korea, relatively more amounts of antibiotics are being used in agriculture. The total amounts of veterinary antibiotics used in therapeutic purposes and as feeding additives were approximately 1,000 ton and 500 ton, respectively, in 2005 (KFDA 2005). The use of veterinary medicinal products eventually leads to their release into the various compartments of the environment. Veterinary medicines may release directly to S. Park  K. Choi (&) School of Public Health, Seoul National University, Seoul 110-799, Korea e-mail: kyungho@snu.ac.kr 123 Ecotoxicology (2008) 17:526–538 DOI 10.1007/s10646-008-0209-x