PARENT SESSION

(03-05) Exposure Routes of Fluoroquinolone Antibacterial Agents in the Aquatic and Terrestrial Environment.

Golet, Eva^*,1, Alder, Alfredo¹, Xifra, Irene², Strehler, Adrian¹, Giger, Walter¹, ¹ EAWAG/ETH, Swiss Federal Institute for Environmental Science, Dübendorf, Switzerland² UdG, Universitat de Girona, Girona, Spain

ABSTRACT- The increasing concern over the hazard associated to pharmaceutical residues in the environment has stimulated a widespread interest among pharmaceutical manufactures and governmental regulatory agencies in assessing the exposure and risk of these compounds in different environmental compartments. Fluoroquinolones (FQs) represent an important class of antibacterial agents, an example is ciprofloxacin which is the medicine of choice for the treatment of anthrax infections. Herein we report on the occurrence and fate of the two leading FQs in Switzerland, ciprofloxacin and norfloxacin, in several aquatic and terrestrial compartments. The primary entry route of FQs into the environment is mainly via human excretion into wastewaters. Our data indicated concentrations in raw sewage of 260-570 ng/L per FQ. After an overall removal of 79 to 87% during mechanical-biological wastewater treatment, individual FQ concentrations in final effluents ranged from 40 to 110 ng/L. The main elimination pathway is the sorption to sewage sludge with FQ concentrations of 1 to 3 mg/Kg dry sludge. After wastewater treatment, final effluents are discharged to the receiving waters where concentrations up to 18 ng/L of each FQ were measured. Over a 36 km stretch of river, FQ load in the water decreased 48 to 66%. The most relevant entry route of FQs into the terrestrial environment is via dispersion of sludge into agricultural soils; FQs were detected in the upper layers of sludge-treated soils up to several months after application.

Key words: antibiotics, exposure, fate, environment