title: Fate of the antibiotic sulfamethoxazole and its two major human metabolites in a water sediment test.
abstract: Sulfonamide antibiotics are widely used in human and veterinary medicine. After their application, they are excreted in unchanged as well as in metabolized form. Due to incomplete elimination in wastewater treatment plants, they can be emitted into surface water. The environmental fate of both parent compounds and metabolites is currently unknown. The aim of this study was to determine the biodegradation potential of river sediment for the sulfonamide sulfamethoxazole (SMX) and its two major human metabolites N4-acetyl-SMX and SMX-N1-glucuronide using a water sediment test system. Each compound was tested in a separate series together with sterile and "water only" controls. All three compounds were efficiently removed from the test system by biodegradation in the sediment. Only for SMX-N1-glucuronide, a substantial removal in the absence of sediment was determined. Dissipation times from the aqueous phase (DT50) between 8.5 and 17.2 days were measured. Sorption to sediment was of minor importance due to the slightly basic pH of the test system. By the application of a mathematical model, biodegradation half-lives in sediment between 3.3 and 25.6 h were calculated for SMX and its metabolites. The results of this study highlight the capability of native river sediment for degrading sulfonamide antibiotics, but also the potential of human metabolites to retransform into parent SMX under environmental conditions. Based on this study, it is unlikely that SMX or its metabolites will persist or accumulate in river sediments under pH conditions where sorption is of minor importance.
authors.affiliation: Department of Hydrology, University of Bayreuth, 95440 Bayreuth, Germany, Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376 Stuttgart, Germany. michael.radke@uni-bayreuth.de
authors.forename: Michael
authors.initials: M
authors.lastname: Radke
authors.forename: Christoph
authors.initials: C
authors.lastname: Lauwigi
authors.forename: Georg
authors.initials: G
authors.lastname: Heinkele
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Mürdter
authors.forename: Marion
authors.initials: M
authors.lastname: Letzel
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D019015:Geologic Sediments / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D045483:Rivers / Q000737:chemistry; D013420:Sulfamethoxazole / Q000031:analogs & derivatives* / Q000032:analysis* / Q000302:isolation & purification; D013997:Time Factors; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D014874:Water Pollutants, Chemical; D014867:Water; D013420:Sulfamethoxazole