Grantee Research Project Results
2003 Progress Report: Fate and Effects of Fluoroquinolone Antibacterial Agents in Aquatic Ecosystems
EPA Grant Number: R829008Title: Fate and Effects of Fluoroquinolone Antibacterial Agents in Aquatic Ecosystems
Investigators: Graham, David W. , deNoyelles, Frank J. , Lydy, Michael J. , Larive, Cynthia K.
Institution: University of Kansas
EPA Project Officer: Page, Angela
Project Period: August 20, 2001 through August 19, 2004 (Extended to August 19, 2006)
Project Period Covered by this Report: August 20, 2002 through August 19, 2003
Project Amount: $520,976
RFA: Drinking Water (2000) RFA Text | Recipients Lists
Research Category: Drinking Water , Water Quality , Water
Objective:
The major objective of this research project is to assess the fate, attenuation, and ecotoxicity of selected fluoroquinolone (FQ) antibiotics on surface water quality. These compounds are of concern because: (1) they are potent antibacterial agents and possible genotoxins; (2) they are frequently used in agriculture and medicine; and (3) little is known about their environmental fate or impact. Another objective is to assess the fate and impact of FQs in aquatic systems using both laboratory- and field-scale studies. Associated with these efforts, new methods for detecting and analyzing FQs and their degradation products at low concentrations are being developed. Novel methods also are being developed for the monitoring of FQ antibacterial resistance using molecular biological techniques.
Progress Summary:
Early work focused on developing new methods for the analysis of ciprofloxacin (cipro) and enrofloxacin (enro) and their breakdown products at low levels in the environment. This task has been largely achieved, primarily using refined extraction and concentration protocols and liquid chromatography (LC)-nuclear magnetic resonance and LC-mass spectrometry (MS)/MS methods. These methods currently are being extended to other related FQ compounds.
These methods were used for monitoring cipro and enro fate in controlled laboratory and field tests aimed at determining factors that dictate cipro and enro fate in the natural environment. The results suggest that particulate organic matter (POC) and light intensity and wavelength are the most important factors for FQ disappearance in aquatic systems. Photodegradation reactions completely destroy both cipro and enro at half-lives as low as 1.2 hours under natural sunlight and ambient water conditions. Additionally, both FQs readily adsorb onto POC in solution, although the final fate of the FQs after adsorption has not been defined fully. In general, the environmental half-lives of both cipro and enro appear to be very short in aquatic systems that have even minimal light exposure or high POC. This hypothesis was tested using 11.3 m3 aquatic field mesocosms in which cipro fate was dominantly impacted by light exposure levels and secondarily impacted by POC levels. Alternately, early data suggest that FQ half-lives can be very long in sediments under low light conditions.
Concurrent to the work assessing FQ fate in aquatic systems, efforts have been ongoing on the development of molecular biological methods for monitoring FQ resistance in environmental organisms. This work is being performed in collaboration with Dr. Elizabeth Wellington at the University of Warwick in the United Kingdom. The new methods use density gradient gel electrophoresis for tracking mutations in the gyrA gene sequence (the quinolone resistance-determining region), which is known to confer resistance in selected bacteria (e.g., Pseudomonas aeruginosa). The new methods currently are being trialed on chicken manure in the United Kingdom and in cipro-amended aquatic field mesocosms in the United States. Early results look promising, and three manuscripts are in preparation to report the new methods.
Toxicity tests were performed with seven FQ antibiotics—cipro, lomefloxacin, ofloxacin, levofloxacin, clinafloxacin, enro, and flumequine—on five aquatic organisms. Overall toxicity values ranged from 1,100-23,000 µg/L. Microcystis aeruginosa, the cyanobacteria, was the most sensitive organism tested to FQ exposure. Based on 5-day growth and reproduction studies, effective concentrations (EC50) ranged from 7.9 to 1,960 µg/L, with a median level of 49 µg/L. Duckweed (Lemna minor) and the green algae (Pseudokirchneriella subcapitata) were less sensitive than M. aeruginosa. The results from toxicological testing on the crustacean Daphnia magna (48-hour survival) and fathead minnows (Pimephales promelas, 7-day early life stage survival and growth) showed limited toxicity with no observed effect concentrations at or near 10 mg/L. Fish dry weights obtained under ciprofloxacin, levofloxacin, and ofloxacin treatments (10 mg/L), however, were significantly higher than control fish. Hazard assessment testing is commencing based on the new toxicological data.
Future Activities:
The four main ongoing tasks will continue. First, analytical methods are being extended to include the identification and quantification of FQ breakdown products, which ultimately will permit the monitoring of FQ-related reactions in the environment. Second, the new molecular biological protocols are being refined and efforts are being made to quantify resistance genes using modified versions of the techniques. Protocols are focusing on “real-time” PCR technology. Third, we are expanding the mesocosm-testing program to include enrofloxacin, the examination of cipro formation in enro-exposed aquatic systems, and the affect of FQ exposure on the simultaneous degradation of other contaminants, including selected herbicides. These studies are employing the new molecular methods and traditional microbial enumeration techniques to track possible impacts of FQs on aquatic communities. Finally, ecotoxicological results are being extended to assess true risks associated with FQ exposure in the environment at environmentally relevant concentrations.
Journal Articles on this Report : 4 Displayed | Download in RIS Format
Other project views: | All 43 publications | 19 publications in selected types | All 18 journal articles |
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Cardoza LA, Almeida VK, Carr A, Larive CK, Graham DW. Separations coupled with NMR detection. Trends in Analytical Chemistry 2003;22(10):766-775. |
R829008 (2002) R829008 (2003) R829008 (2004) R829008 (2005) R829008 (Final) |
Exit Exit Exit |
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Cardoza LA, Korir AK, Otto WH, Wurrey CJ, Larive CK. Applications of NMR spectroscopy in environmental science. Progress in Nuclear Magnetic Resonance Spectroscopy 2004;45(3-4):209-238. |
R829008 (2003) R829008 (2004) R829008 (2005) R829008 (Final) |
not available |
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Cardoza LA, Knapp CW, Larive CK, Belden JB, Lydy M, Graham DW. Factors affecting the fate of ciprofloxacin in aquatic field systems. Water, Air and Soil Pollution 2005;161(1-4):383-398. |
R829008 (2003) R829008 (2004) R829008 (2005) R829008 (Final) |
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Robinson AA, Belden JB, Lydy MJ. Toxicity of fluoroquinolone antibiotics to aquatic organisms. Environmental Toxicology and Chemistry 2005;24(2):423-430. |
R829008 (2003) R829008 (2004) R829008 (2005) R829008 (Final) |
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Supplemental Keywords:
fluoroquinolone, FQ, photodegradation, adsorption, density gradient gel electrophoresis, DGGE, ecotoxicology, antibacterial resistance, real-time PCR, tetracyclines, quinolone resistance-determining region, QRDR, ciprofloxacin, cipro, enrofloxacin, ecosystem protection/environmental exposure and risk, waste, water, drinking water, ecological effects/environmental exposure and risk, ecological effects, human health, ecological risk assessment, ecosystem/assessment/indicators, environmental chemistry, health risk assessment, antibacterial agents, antibiotics, antiseptics, aquatic ecosystems, chemical contaminants, drinking water contaminants, ecological exposure, exposure, exposure and effects, fate, fate and transport, human health effects, microbial contamination, microbial effects, microbial risk management, monitoring, risk management, pharmaceuticals, stressors, toxicokinetics,, RFA, Scientific Discipline, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Environmental Chemistry, Ecosystem/Assessment/Indicators, Health Risk Assessment, Fate & Transport, Ecological Effects - Environmental Exposure & Risk, Ecological Effects - Human Health, Ecological Risk Assessment, Ecology and Ecosystems, Drinking Water, monitoring, fate and transport, ecological effects, ecological exposure, fate, microbial contamination, antibiotics, human health effects, stressors, antibacterial agents, exposure and effects, pharmaceuticals, exposure, chemical contaminants, fluoroquinolone, microbial effects, microbial risk management, water quality, aquatic ecosystems, drinking water contaminants, other - risk management, anticepticsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.