Grantee Research Project Results
Final Report: Pharmaceuticals and Antiseptics: Occurrence and Fate in Drinking Water, Sewage Treatment Facilities, and Coastal Waters
EPA Grant Number: R829004Title: Pharmaceuticals and Antiseptics: Occurrence and Fate in Drinking Water, Sewage Treatment Facilities, and Coastal Waters
Investigators: Roberts, A. Lynn , Bouwer, Edward J.
Institution: The Johns Hopkins University
EPA Project Officer: Page, Angela
Project Period: September 1, 2001 through August 31, 2004 (Extended to August 9, 2006)
Project Amount: $524,890
RFA: Drinking Water (2000) RFA Text | Recipients Lists
Research Category: Drinking Water , Water Quality , Water
Objective:
Prior to initiating this research, there was a paucity of information concerning the occurrence, (eco)toxic risk, and fate of pharmaceuticals and antiseptics in U.S environmental systems. This research project is designed to redress critical aspects of this deficiency by providing an assessment of the prevalence of important pharmaceuticals and antiseptics in drinking water, sewage treatment plant (STP) influent and effluent, and receiving waters. The specific objectives of this research project are to: (1) compile data on pharmaceutical usage, probable environmental concentrations and associated risk, and selected target compounds based on resulting calculations of potential environmental concentrations and, where possible, environmental risk; (2) refine analytical methods for quantification of pharmaceuticals and antiseptics in sewage and drinking water samples using gas chromatography/mass spectroscopy (GC/MS) techniques that can be readily adopted by others; (3) analyze concentrations of target pharmaceuticals and antiseptics in raw and finished drinking water samples from public utilities to relate removal efficiency with the treatment process employed; (4) examine the adequacy of current wastewater treatment practices for reducing pharmaceutical and antiseptic emissions by analyzing influent and effluent samples; (5) examine the biodegradability of select pharmaceuticals and antiseptics in simulated wastewater treatment systems and in real wastewater to examine the influence of interactions with co-contaminants on biodegradability at the low levels encountered in the environment; and (6) conduct field studies to determine vertical and longitudinal distributions of target pharmaceuticals and antiseptics in the upper Chesapeake Bay to seek evidence of rapid natural attenuation.
Approach:
Final selection of target compounds will be based in part on calculations of potential environmental concentrations and (where possible) environmental risk associated with existing products (Task 1), along with preliminary screening studies in STPs. Analytical methods previously developed elsewhere will be refined (Task 2) so as to provide the extremely high sensitivity needed for analyzing trace concentrations in drinking water, while relying on benchtop GC/MS techniques that can readily be adopted by others. We are confident that by modifying derivatization methods to take advantage of the sensitivity and selectivity of negative chemical ionization GC/MS, and by using large-volume injection techniques, we can attain detection limits three orders of magnitude below those reported by others. In Task 3, concentrations of analytes will be determined in raw and finished drinking water samples obtained from public utilities across the U.S. Removal efficiencies will be related to treatment processes employed. In Task 4, the adequacy of current wastewater treatment practices for reducing emission of pharmaceuticals and antiseptics will be examined by measuring their concentrations at three STPs (Deer Island in Boston, MA; Back River and Patapsco STPs in Baltimore, MD). Two (Deer Island and Back River) receive substantial hospital wastewater inputs, and Back River discharges its treated effluent to the Chesapeake Bay, the largest and most important estuary in the U.S. In Task 5 we will examine the biodegradability of selected pharmaceuticals and antiseptics in simulated wastewater treatment systems and in real wastewater, in order to examine the influence of interactions with co-contaminants on biodegradability at the low levels encountered in the environment. Finally, in Task 6, we will determine vertical and longitudinal distributions of target pharmaceuticals and antiseptics in the upper Chesapeake Bay to seek evidence of rapid natural attenuation.Summary/Accomplishments (Outputs/Outcomes):
The contamination of water by trace amounts of pharmaceuticals, largely introduced through their incomplete removal by municipal sewage treatment plants (STPs) has recently attracted intense public attention. Although the effects of steroid hormones on aquatic species has been intensively investigated, much less is known about the wide variety of non-hormonal human pharmaceuticals or other wastewater-related compounds (such as antiseptics) that may be present. At present, the extent to which such micropollutants represents a public health concern, or a risk to aquatic ecosystems, remains an open question. One factor that hampers its resolution relates to the difficulty associated with assessing exposure by measuring such compounds at trace levels in natural waters or STP influent or effluent using GC/MS instruments that are the “workhorses” of most environmental laboratories in the United States. At present, few simple GC/MS methods exist that are suitable for measuring a wide array of such compounds.
The present study sought to redress this deficiency through developing simple, yet robust, GC/MS methods, complemented by sample preconcentration via solid phase extraction (SPE), with broad applicability. In seeking to develop GC/MS methods, our work emphasizes those compounds that are likely to occur in STP influents at relatively high expected introductory concentrations (EIC values). Our work began by computing EIC values for relevant constituents of the top 200 drugs (ranked by sales) in the following categories: brand name, generic, hospital, and over-the-counter medications. The results reveal a large number of constituents likely to be introduced at concentrations in the μg/L range. When coupled with toxicity data (as in our ongoing work), the results will prove helpful in prioritizing constituents for additional study.
The first multiresidue method we developed makes use of pentafluorobenzylation for derivatization of acidic pharmaceuticals following concentration of samples via SPE. In optimizing our pentafluorobenzylation method for the analysis of 12 pharmaceuticals (valproic acid, phenytoin, gabapentin, gemfibrozil, 5-fluorouracil, secobarbital, phenobarbital, acetaminophen, naproxen, ketoprofen, diclofenac, ibuprofen) and six phenolic antiseptic agents (chlorophene, p-chloro-m-xylenol, biphenylol, triclosan, p-chloro-m-cresol, and biosol), careful attention was paid to optimizing reaction conditions, including the identity of reaction solvent, identity and concentration of bases, reaction times, reaction temperatures, reagent concentrations, and identity of extraction solvents. Our method also destroys excess derivatizing agent, thereby reducing the need for maintenance of the GC/MS instrument. We also systematically investigated the influence on SPE medium identity and matrix effects on sample recoveries. This effort was aided by our having purchased or synthesized 15 different isotopically labeled variants of the 18 target analytes in this study. Aqueous acetonitrile, a solvent mixture that appears to have been overlooked in prior studies of pentafluorobenzylation, proved to exhibit many attractive features as a reaction solvent. Not only did it afford better apparent derivatization yields than the other solvents investigated, but it also eliminates the need for drying of the SPE cartridge, and enables all elution and derivatization steps to be conducted using a single test tube. The method affords high sensitivity and reproducibility, with a detection limit in the low ng/L range for the majority of analytes. This method was validated through determining concentrations of the 18 analytes in grab samples obtained from a local STP. Sixteen of the 18 analytes were detected in STP influent, and 10 in effluent samples. Seven of these were detected, to the best of our knowledge, for the first time in the United States. Although recoveries were in some cases low (necessitating corrections for accurate quantitation of the corresponding analytes), recoveries obtained from laboratory fortification of field samples compared closely with those obtained using isotopically labeled surrogate standards. We anticipate that this method will prove applicable to a wide array of acidic pharmaceuticals; preliminary data indicate its suitability to an additional 10 wastewater-derived compounds or acidic herbicides often used in urban settings (oxybenzone, butylated hydrolyanisole, 2,4,6- tribromophenol, 2,4-dichlorophenol, 2,4-dichlorophenoxyacetic acid, 2-methyl-4- chlorophenoxyacetic acid, n-octylphenol, n-nonylphenol, p-tert-amylphenol, and bisphenol A), extending the list of analytes amenable to analysis via this method to 28 compounds.
The second GC/MS method we explored involves an investigation of derivatization approaches suitable for the analysis of basic and neutral pharmaceuticals. Eight different silylating or acetylating agents (or combinations of silylating agents) were examined to assess their ability to derivatize a suite of basic pharmaceuticals. This suite was selected on the basis of their EIC values. Experiments were conducted to optimize reaction time, temperature, and reaction solvent identity, in addition to derivatizing agent identity. SPE sorbent medium identity, elution solvent identity, and extraction pH have also been systematically investigated to optimize analyte recoveries. A mixture of N,Nbis(trimethylsilyl)-trifluoroacetamide (BSTFA) and chlorotrimethylsilane (TMCS) provided the highest derivatization yields for the majority of constituents within the analyte suite. Method recovery studies are currently under way, as are determinations of method detection limits (MDL values). When these studies have been completed, and the method has been validated by application to wastewater samples, we anticipate this method will prove applicable for the analysis of a total of 20 compounds (16 pharmaceuticals representing 12 therapeutic classes: terbinafine, diazepam, carbazepine, brompheniramine, oxcarbazepine, primidone, amitryptyline, albuterol, fenofibrate, triamterine, allopurinol, metoprolol, propanolol, acetaminophen, carisoprodol, and caffeine), and 4 other wastewater-derived contaminants (diethyltoluamide, nbutyl-benzene sulfonate, n-octylphenol, and n-nonylphenol). As some analyte occurs in common between this and the pentafluobenzylation method described in Chapter 1, we anticipate that the two methods will collectively prove useful for the analysis of as many as 27 pharmaceuticals and 6 antiseptic agents, in addition to a number of other organic pollutants likely to occur in wastewater.
Once analytical methods had been successfully developed and validated, we undertook laboratory batch experiments to explore the biodegradability of the same array of acidic pharmaceuticals and phenolic antiseptics. Biodegradability was studied under a variety of different electron acceptor conditions (aerobic biodegradation, nitrate-reducing, and iron-reducing), using microbial inocula obtained from sewage as well as from soil. Initial concentration was another variable that was explored. We sought to conduct the majority of our experiments at initial concentrations of 1 μg/L, as close as was feasible to initial concentrations observed in STP influents, to enhance the applicability of our results. Results indicated that most of the pharmaceuticals and antiseptics investigated underwent > 80% biotransformation after 50 days of incubation. Results were similar for different microbial inocula (primary settled sewage and activated sludge) and different initial concentrations (50, 10 and 1 μg/L). The pharmaceuticals studied proved less biodegradable under anaerobic (nitrate and iron reducing) conditions. All antiseptics tested were biotransformed under both anaerobic and aerobic testing conditions. Our biodegradability results were compared to BIOWIN model predictions; this model proved relatively ineffective at predicting biodegradability of the compounds studied herein.
The final aspect of our study involved investigating the occurrence of acidic pharmaceuticals and antiseptics in STP influent and effluent from four major STPs along the Eastern seaboard. Composite samples (24 hour) were obtained from STPs located in four major urban areas: Baltimore, MD; the Washington, D. C. area; Philadelphia, PA; and a site in the New York City area. Nearly all of the 18 target analytes were detected in the sampled STP influents, with concentrations ranging from the low μg/L to ng/L level. Effluent concentrations were lower for many of the target analytes; nevertheless, incomplete removals were frequently encountered. A steady-state STP model incorporating biodegradation, sorption, and volatilization processes was formulated to provide insight into the fate of the pharmaceuticals and antiseptics during sewage treatment. The influence of compound ionization on sorption and volatilization was also incorporated into the model. The modeling exercise concluded that biodegradation was the dominant removal process. Consequently, operating the STPs with longer solids residence times should increase the removals of these compounds. Volatilization and sorption to waste biosolids contributed little to the removal of these pharmaceuticals and antiseptics.
Expected Results:
Based on recent studies conducted in Europe, we expect to encounter an array of pharmaceuticals in raw surface water supplies and in STP influent and effluent. The specific compounds (and concentrations) encountered are, however, likely to be very different, reflecting variations in therapeutic and water/wastewater treatment practices. The results of this study will quantify the effectiveness of current water and wastewater treatment practices for removing major pharmaceuticals and antiseptics. It will also provide exposure data needed to assess whether human and ecotoxic effects could be associated with pharmaceuticals and antiseptics in the environment. Finally, the results will be helpful in indicating whether natural removal processes are able to attenuate concentrations of what may prove to be a significant class of organic micropollutants.Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 20 publications | 2 publications in selected types | All 2 journal articles |
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Yu JT, Bouwer EJ, Coelhan M. Occurrence and biodegradability studies of selected pharmaceuticals and personal care products in sewage effluent. Agricultural Water Management 2006;86(1-2):72-80. |
R829004 (Final) |
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Supplemental Keywords:
groundwater, estuary, risk assessment, environmental engineering, environmental chemistry, analytical chemistry., RFA, Scientific Discipline, Water, Waste, Ecosystem Protection/Environmental Exposure & Risk, Wastewater, Environmental Chemistry, Fate & Transport, Analytical Chemistry, Monitoring/Modeling, Environmental Monitoring, Ecological Risk Assessment, Drinking Water, Environmental Engineering, Groundwater remediation, monitoring, fate and transport, exposure and effects, pharmaceuticals, exposure, other - risk assessment, wastewater treatment plants, chemical contaminants, personal care products, surface water, groundwater monitoring, treatment, analytical methods, water treatment, drinking water contaminants, effluents, anticeptics, sewage treatment plantsProgress 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.
Project Research Results
- 2005 Progress Report
- 2004 Progress Report
- 2003 Progress Report
- 2002 Progress Report
- Original Abstract
2 journal articles for this project