Drugs In Wastewater Research Articles

Assessment of illicit drugs in wastewater and estimation of drugs of abuse in Adana Province, Turkey

Wastewater-based epidemiology (WBE) is a rapidly developing discipline that has the potential to monitor real-time data on regional and temporal differences regarding the use of illicit drugs. With WBE, metabolic products discharged for drug consumption are rapidly collected by sewage systems, which provide valuable evidence on the types and quantities of drugs consumed by a given community. In this study, the samples were collected from the wastewaters entering the facilities in Seyhan and Yuregir Waste Water Treatment Plants (WWTPs), in Adana Province. Composite wastewater analysis was performed by using liquid chromatography tandem mass spectrometry (LC–MS/MS) and the analysis revealed multiple drugs including cocaine and its main metabolite, benzoylecgonine, amphetamine-like stimulants including amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxyethamphetamine (MDEA), opiates including morphine, codeine, heroin metabolite 6-acetylmorphine (6-MAM), the metabolite of cannabis, 11-nor-carboxy-THC (THC-COOH), and the main metabolite of Δ9-tetrahydrocannabinol (THC), 11-hydroxy (THC-OH). Mean drug consumption rates were as follows: cocaine, 0.18; amphetamine, 0.43; methamphetamine, 0.06; MDMA (ecstasy), 1.30; heroin, 1.03; THC (marijuana), 28.60 doses/day/1000 persons (15–64years). The consumption rates for some illicit drugs showed a significant difference between seasons, regions, and weekdays–weekends.

Self-assembling covalent organic framework functionalized poly (styrene-divinyl benzene-glycidylmethacrylate) composite for the rapid extraction of non-steroidal anti-inflammatory drugs in wastewater

The growing use of non-steroidal anti-inflammatory drugs (NSAIDs) has seriously affected human health and ecosystems, as a result, the World Health Organization (WHO) has regarded them as emerging contaminants. NSAID’s polar nature and trace amount present in wastewater make their extraction and determination challenging in modern analytical science. Therefore, regarding the need, we herein report a rapid, sensitive and selective in-syringe solid-phase extraction (SPE) method coupled with ultrahigh performance liquid chromatography and UV detector for the determination of seven NSAIDs in environmental water samples. Specifically, the NSAIDs in water samples were directly extracted by using synthesized porous covalent organic framework functionalized poly (styrene-divinyl benzene-glycidylmethacrylate) composite (COF@PS-GMA) without further cleanup procedures. The adsorption of NSAIDs on COF@PS-GMA sorbent was investigated by using adsorption isotherms and kinetic studies. Various parameters, including amount of sorbent, pH of the samples, the volume of desorption solvent, and desorption time that were involved in in-syringe SPE were optimized. Under the optimized conditions, good linearity was observed at 0.005–5.0 μg mL−1 with method quantification limits (LOQs) estimated between 0.54–2.74 μg L−1. The recoveries of the seven NSAIDs at the level of 0.5, 5.0 and 20.0 μg L−1 were ranging from 84.3% to 99.6%.

Electrochemical strategies for the detection of forensic drugs

Illicit drugs consumption and trafficking is spread worldwide and remains an increasing challenge for local authorities. Forensic drugs and their metabolites are released into wastewaters due to human excretion after illegal consumption of drugs and occasionally due to disposal of clandestine laboratory wastes into sewage systems, being recently classified as the latest group of ‘emerging pollutants’. Hence, it is essential to have efficient and accurate methods to detect these type of compounds in seized street samples, biological fluids and wastewaters in order to reduce and prevent trafficking and consumption and negative effects on aquatic systems. Electrochemical strategies offer a fast, portable, low-cost and accurate alternative to chromatographic and spectrometric methods, for the analysis of forensic drugs and metabolites in different matrices. Recent electrochemical strategies applied to the detection of illicit drugs in wastewaters, biological fluids and street samples are presented in this review, together with the impact of drug consumption on the environment.

Contamination profiles, mass loadings, and sewage epidemiology of neuropsychiatric and illicit drugs in wastewater and river waters from a community in the Midwestern United States

In this study, residues of the neuropsychiatric and illicit drugs including stimulants, opioids, hallucinogens, antischizophrenics, sedatives, and antidepressants were determined in influent and effluent samples from a small wastewater treatment plant, a receiving creek, and river waters in the Four Rivers region of the Midwestern United States. Nineteen neuropsychiatric drugs, eight illicit drugs, and three metabolites of illicit drugs were detected and quantitated in the water samples using HPLC–MS/MS. Residual concentrations of the drugs varied from below the detection limit to sub-μg/L levels. The source of residual cocaine and benzoylecgonine in wastewater is primarily from human consumption of cocaine rather than direct disposal. Wastewater based epidemiology is utilized to estimate the community usage of drugs based on the concentration of drug residues in wastewater, wastewater inflow, and the population served by the centralized wastewater treatment plant. The per-capita consumption rate of methamphetamine (1740 mg/d/1000 people) and amphetamine (970 mg/d/1000 people) found in this study were the highest reported per-capita consumption rates in the USA. Antidepressant venlafaxine found to have the highest environmental emission from the WWTP (333 ± 160 mg/d/1000 people) followed by citalopram (132 ± 60.2 mg/d/1000 people), methamphetamine (111 ± 43.6 mg/d/1000 people), and hydrocodone (108 ± 90.1 mg/d/1000 people). Bee Creek, an immediate receiving water body, is found to be a source of several neuropsychiatric and illicit drugs including methamphetamine, methadone, alprazolam, oxazepam, temazepam, carbamazepine, venlafaxine, citalopram, sertraline, oxycodone, and hydrocodone (p < 0.036) in the Clarks River.

Simple determination of some antidementia drugs in wastewater and human plasma samples by tandem dispersive liquid–liquid microextraction followed by high‐performance liquid chromatography

In this work, a simple method, namely, tandem dispersive liquid-liquid microextraction, with a high sample clean-up is applied for the rapid determination of the antidementia drugs rivastigmine and donepezil in wastewater and human plasma samples. This method, which is based on two consecutive dispersive microextractions, is performed in 7min. In the method, using a fast back-extraction step, the applicability of the dispersive microextraction methods in complicated matrixes is conveniently improved. This step can be performed in less than 2min, and very simple tools are required for this purpose. To achieve the best extraction efficiency, optimization of the variables affecting the method was carried out. Under the optimized experimental conditions, the relative standard deviations for the method were in the range of 6.9-8.7%. The calibration curves were obtained in the range of 2-1100ng/mL with good correlation coefficients, higher than 0.995, and the limits of detection ranged between 0.5 and 1.0ng/mL.

Analysis of stimulant drugs in the wastewater of five Nordic capitals

Wastewater-based epidemiology is an efficient way to assess illicit drug use, complementing currently used methods retrieved from different data sources. The aim of this study is to compare stimulant drug use in five Nordic capital cities that include for the first time wastewater samples from Torshavn in the Faroe Islands. Currently there are no published reports that compare stimulant drug use in these Nordic capitals. All wastewater samples were analyzed using solid phase extraction and ultra-high performance liquid chromatography coupled to tandem mass spectrometry. The results were compared with data published by the European Monitoring Centre for Drugs and Drug Addiction based on illicit drugs in wastewater from over 50 European cities. Confirming previous reports, the results showed high amphetamine loads compared with other European countries. Very little apparent abuse of stimulant drugs was detected in Torshavn. Methamphetamine loads were the highest from Helsinki of the Nordic countries, indicating substantial fluctuations in the availability of the drug compared with previous studies. Methamphetamine loads from Oslo confirmed that the use continues to be high. Estimated cocaine use was found to be in the lower range compared with other cities in the southern and western part of Europe. Ecstasy and cocaine showed clear variations between weekdays and weekends, indicating recreational use. This study further demonstrates geographical trends in the stimulant drug market in five Nordic capitals, which enables a better comparison with other areas of the continent.

Bio-electro-Fenton process for the degradation of Non-Steroidal Anti-Inflammatory Drugs in wastewater

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are ubiquitous municipal wastewater pollutants of which several are resistant to degradation in conventional wastewater treatment, and represent a major environmental health concern worldwide. An alternative treatment, the bio-electro-Fenton process, has received increasing attention in past years. In this process the strong oxidant HO is formed using the electrons derived from bacterial oxidation of organic substrate. In this work, a laboratory scale microbial electrolysis cell based bio-electro-Fenton process was developed for the treatment of four different NSAIDs. The system was demonstrated to remove low concentration NSAIDs from water and wastewater and all tested parameters (cathode pH, cathode air-flow, cathode Fe2+ concentration, applied voltage, NSAIDs concentration and reaction time) were found to affect the apparent first order rate constant and removal efficiency for NSAIDs. Optimum parameter values were found to be pH = 2, Fe+2 = 7.5 mM, air-flow = 8 mL min−1, applied voltage = 0.3 V; the apparent rate constant was higher for higher NSAIDs initial concentration. For reaction times of 5 h removal efficiencies were 59–61% for Ketoprofen, 87–97% for Diclofenac, 80–86% for Ibuprofen and 75–81% for Naproxen. Prolonged reaction times lead to substantial increase in removal efficiencies for Ketoprofen and Naproxen. Finally results obtained with real wastewater show lower removal rate constants than with distilled water matrices suggesting interference from wastewater components in the NSAIDs oxidation process. The results offer insight into future developments of an efficient platform for wastewater treatment technology targeting micropollutants.

Estimation of Community Usage of Drugs Utilizing Sewage Epidemiology.

Drug abuse is considered to be a national epidemic in many countries including the USA, and is associated with impaired social indicators including economic loss and adverse public health. The conventional methods of estimation of drug usage in communities are based on self-reported surveys, overdose or toxicological reports, drug-related crime statistics, and hospital admissions. Conventional methods suffer from several shortcomings including cost and time intensiveness, nonresponse bias, bias in the selection of sample population, and consumer's unawareness on the actual composition of used drugs. Sewage epidemiology utilizes the mass load of drugs in wastewater influent to estimate the drug usage in a community. Despite several challenges to the determination of the human excretion profile of drugs, the stability of drugs in wastewater, the dynamics of the population, sewage epidemiology provides several opportunities, including a cost-effective, comprehensive, noninvasive, and nearly real-time measure of trends of drug use over time.

Analysis of Illicit Drugs in Wastewater Using High-Performance Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry (HPLC-ESI-MS/MS).

Consumption of illicit drugs is considered to be a global socioeconomic burden of adverse ecological and public health. Proper identification and quantification of trace level residues of illicit drugs in wastewater allow for an estimation of drug usage in a community, the amount of drug discharge into the environment, and the overall fate of drugs in the environment. This chapter provides a procedural detail of the determination of select illicit drugs and their metabolites in wastewater, suspended particulate matter, and sewage sludge using high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry.

Qualitative and quantitative temporal analysis of licit and illicit drugs in wastewater in Australia using liquid chromatography coupled to mass spectrometry.

The combination of qualitative and quantitative bimonthly analysis of pharmaceuticals and illicit drugs using liquid chromatography coupled to mass spectrometry is presented. A liquid chromatography-quadrupole time of flight instrument equipped with Sequential Window Acquisition of all THeoretical fragment-ion spectra (SWATH) was used to qualitatively screen 346 compounds in influent wastewater from two wastewater treatment plants in South Australia over a 14-month period. A total of 100 compounds were confirmed and/or detected using this strategy, with 61 confirmed in all samples including antidepressants (amitriptyline, dothiepin, doxepin), antipsychotics (amisulpride, clozapine), illicit drugs (cocaine, methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine (MDMA)), and known drug adulterants (lidocaine and tetramisole). A subset of these compounds was also included in a quantitative method, analyzed on a liquid chromatography-triple quadrupole mass spectrometer. The use of illicit stimulants (methamphetamine) showed a clear decrease, levels of opioid analgesics (morphine and methadone) remained relatively stable, while the use of new psychoactive substances (methylenedioxypyrovalerone (MDPV) and Alpha PVP) varied with no visible trend. This work demonstrates the value that high-frequency sampling combined with quantitative and qualitative analysis can deliver. Graphical abstract Temporal analysis of licit and illicit drugs in South Australia.

A high-throughput solid-phase microextraction and post-loop mixing large volume injection method for water samples

This article presents a novel approach for the analysis of 13 drugs in wastewater for use in wastewater-based epidemiology (WBE) studies. Sample preparation remains one of the principal bottlenecks in modern high-throughput analysis by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The proposed methodology is based on the micro-extraction of small volumes (1 ml) of wastewater using a HLB 96-well microplate and both large volume injection (LVI) and post-loop mixing injection (PLM). With this configuration, the limits of quantification (LOQ) were below the reported environmental concentrations of the target compounds in wastewater. Furthermore, both the complexity of collecting, transporting and storing the wastewater sample, sample preparation time, cost and amount of solvent used are all diminished, enhancing the suitability of this methodology for future WBE studies. A new workflow is also proposed in order to create a virtual specimen library bank for WBE by using high-resolution mass spectrometry (HRMS). The method was validated and the limits of quantification were between 0.2 and 6.3 ng L−1. The relative standard deviations (RSD) for a standard mixture at 200 ng L−1 (n = 6) was between 3.4 and 14.4% while the recoveries for the 13 drug target residues (DTR) were between 92 and 110%. The developed and validated method was finally successfully applied to 10 wastewater samples collected from Oslo, Norway.

Investigation and Application of a New Passive Sampling Technique for in Situ Monitoring of Illicit Drugs in Waste Waters and Rivers.

Illicit drugs constitute a class of emerging contaminants that has been drawing significant concern due to its potent pharmacological and biological activities. In this study, an in situ passive sampling approach that uses diffusive gradients in thin films (DGT) was successfully tested for measuring ketamine (KET), methamphetamine (METH), and amphetamine (AMP) in water. The diffusion coefficients of KET, METH, and AMP in diffusive gel were (8.13 ± 0.12) × 10-6, (8.55 ± 0.14) × 10-6, and (7.72 ± 0.18) × 10-6 cm2 s-1 at 22 °C, respectively. The capacities of an XAD binding gel for KET, METH, and AMP were 92, 57, and 45 μg per binding gel disc, which were suitable for long-term environmental monitoring. The DGT measurement of these drugs was not influenced by the pH (4 to 9) and the ionic strength (0.001 M - 0.1 M) and unaffected by the water flow, demonstrating the effectiveness of the XAD-based DGT for the in situ monitoring of illicit drugs. DGT samplers were deployed in a WWTP influent and natural rivers in Beijing, China. The ng L-1 levels of the drugs were high in the wastewater influent and low in river waters, with an insignificant fluctuation during the seven-day monitoring. The DGT-measured concentrations were comparable to the average concentrations determined by SPE method, which suggested that the average data measured by DGT could be substituted for high-frequency grab sampling. This study has demonstrated systematically for the first time that DGT is effective and accurate for monitoring illicit drugs in wastewater and surface waters, and provides a powerful tool to investigating the presence, transport, and environmental behaviors of these drugs in the aquatic ecosystem.

Metagenomic insights into the influence of salinity and cytostatic drugs on the composition and functional genes of microbial community in forward osmosis anaerobic membrane bioreactors

Wastewater treatment using forward osmosis anaerobic membrane bioreactors (FO-AnMBR) has a number of advantages over traditional wastewater treatment approaches. Previous studies have investigated the overall performance of lab-scale FO-AnMBR in treating synthetic wastewater. Due to enhanced physical rejection of osmosis membrane, salinity gradually increased and emerging contaminants such as cytostatic drugs in wastewater would also be accumulated during operation. The objective of this study was to investigate the influence of increased salinity and the accumulation of cytostatic drugs on the composition and function of the microbial community in FO-AnMBR through a metagenomics approach. We found that salinity increase in FO-AnMBR was the key factor driving compositional and functional transitions in microbial community. At high salinity condition, methane-producing archaea (MPA) became less competitive than sulphate-reducing bacteria (SRB), resulting in a reduced methane yield rate. The reduced methane production could be restored in the next successive cycle and salt-tolerant MPA was continuously enriched in the entire operation. Relative abundance of genes involved in nitrogen metabolism, cell attachment and biofilm related signalling increased from low salinity to high salinity condition, while those for methanogenesis and iron metabolism were found to decrease. The presence of cytostatic drugs caused the inhibition of microbial metabolism and increased extracellular polymeric substances (EPS) concentration. Due to their differential influences on community members, the evenness of community decreased after drug treatment. After the drug treatment, biofilm-forming and siderophore-producing bacteria were found to be more dominant in the microbial community.

Development of a macroporous ceramic passive sampler for the monitoring of cytostatic drugs in water

The aim of this study was to develop and calibrate a macroporous ceramic passive sampler (MCPS) for the monitoring of anticancer drugs in wastewater. This system was designed by the Spanish Research Council (CSIC) and consists in a porous ceramic tube to allow a high diffusion of contaminants. The MCPS has been calibrated for 16 cytostatic drugs over time periods up to 9 d in spiked water under controlled laboratory conditions. Optimal uptake was accomplished for 7 compounds, namely ifosfamide, cyclophosphamide, capecitabine, prednisone, megestrol, cyproterone and mycophenolic acid, whereas cytarabine was not adsorbed in the receiving phase and the rest were hydrolyzed over the deployment period. The sampling rate for these 7 compounds was between 0.825 and 3.350 mL day−1 and the diffusion coefficients varied from 1.01E-07 to 4.12E-07 cm2 s−1. To prove the applicability of the MCPSs, samplers (n = 3) were deployed in influent and effluent waters of a WWTP for a period of 6 d and results were compared to grab sampling and extraction with Solid Phase Extraction (SPE). In influent waters, MCPS were clogged due to the high amount of suspended solids in these waters. In effluents, MCPS detected cyclophosphamide and mycophenolic acid at concentrations of 19 ± 3 and 136 ± 28 ng L−1 with a good agreement with the levels obtained by grab sampling. The study discusses the use and performance of the MCPS for the monitoring of stable cytostatic compounds in a complex matrix such as wastewater.

Optimization and Validation of the Analytical Method to Detect Common Illicit Drugs in Wastewater

Illicit drugs have been recognized as a group of emerging pollutants.Based on previous research,procedures to pre-treat wastewater including SPE column,pH of water samples,and processes of washing,acidifying and re-dissolving were compared.It was found that the best recovery was achieved when wastewater was adjusted to pH=2 and Oasis MCX column was used.It was not necessary to flush the loaded column or to acidify the eluate prior to evaporation using nitrogen steam.After evaporation,it is recommended to redissolve the evaporated samples using 200 μL acetonitrile and 100 μL acetonitrile+100 μL 5 mmol·L-1 ammonium acetate in Milli-Q water for HILIC-UPLC-MS/MS and C18-UPLC-MS/MS,respectively.After comparing retention times,limit of detection,limit of quantification,recoveries,and matrix effects of HILIC and C18 methods,C18-UPLC-MS/MS was chosen.Influent and effluent samples from 12 wastewater treatment plants in Beijing were analyzed using the optimized method for validation.The validated methods set a firm foundation to apply the sewage-based epidemiology to monitor illicit drug abuse in China.

LC-MS-MS Method for the Analysis of Miscellaneous Drugs in Wastewater During Football Games III.

Continuing our previous studies analyzing drugs of abuse in municipal wastewater, a method was developed for the analysis of miscellaneous drugs of abuse in wastewater samples using liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS). Eight drugs and metabolites were analyzed including 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrolidine (EDDP), fentanyl, norfentanyl, meperidine, normeperidine, methadone, phencyclidine and tramadol. These drugs were chosen because of their widespread abuse. Wastewater samples were collected at both the Oxford Waste Water Treatment Plant in Oxford, Mississippi (MS) and the University Wastewater Treatment Plant in University, MS. These wastewater samples were collected on weekends in which the University of Mississippi football team (colloquially the "Ole Miss Rebels" football team) held home games (Vaught-Hemingway Stadium, University, MS 38677). The collected samples were analyzed using a validated method and found to contain tramadol in 25 samples at quantifiable levels. EDDP, meperidine, normeperidine and methadone were also detected but were under the limit of quantitation.

The Presence of Stimulant Drugs in Wastewater from Krakow (Poland): A Snapshot.

An analysis of wastewater from Krakow (Poland) for the presence of controlled and uncontrolled stimulant drugs of abuse was performed. Samples were collected from the Plaszow wastewater treatment plant, Krakow, Poland, and prepared by solid phase extraction. The LC-QTOFMS method was applied for identification and quantification of popular stimulants: MDMA, mephedrone, 4-MEC, MDPV and mCPP. Environmental loads of illicit drugs were calculated; the WWTP discharged loads ranging from 3.6 to 6.7 mg day−1 1000 inhabitants−1 of MDMA, 3.6 to 7.1 mg day−1 1000 inhabitants−1 of mephedrone and 4.8 to 5.8 mg day−1 1000 inhabitants−1 of 4-MEC. The results confirmed the growing popularity of new psychoactive substances in Poland.

Analysis of illicit drugs in wastewater – Is there an added value for law enforcement?

Assessing illicit drug use through the analysis of wastewater is progressively being integrated into existing methods used to monitor the epidemiology of drug use. However, the approach's potential to deliver pertinent information for law enforcement has been discussed only limitedly. Thus, this work focuses on evaluating the added value of the approach from the perspective of law enforcement. Results from wastewater analysis carried out in two cities in Switzerland were scrutinised, taking into account intelligence derived from the work of drug enforcement in the area. Focus was set on three substances, namely cocaine, heroin and methamphetamine. Findings show that results from wastewater analysis can be used by law enforcement to assess the market share held by criminal groups. Combined with intelligence resulting from police work (e.g., investigations and informants), wastewater analysis can contribute to deciphering the structure of drug markets, as well as the local organisation of trafficking networks. The results presented here constitute valuable pieces of information, which can be used by law enforcement to guide decisions at strategic and/or operational levels. Furthermore, intelligence gathered through investigations and surveillance constitutes an alternative viewpoint to evaluate results of wastewater analysis.

Popular pharmaceutical residues in hospital wastewater: quantification and qualification of degradation products by mass spectroscopy after treatment with membrane bioreactor.

The occurrence of drugs in wastewater has been considered an imminent risk to the population, for the treatments used are usually ineffective. The presence of four popular drug residues (metformin, paracetamol, tetracycline, and enalapril) in hospital effluents, by using ultra-fast liquid chromatography tandem mass spectrometry (UFLC-MS/MS) with electrospray (ESI) ionization, and removal/degradation by membrane bioreactor (MBR) system are investigated in this study. For analysis method, all standard calibration curves showed satisfactory linearity (R (2) ≥ 0.993) within a relatively wide range. The recovery was between 70.4 and 105.0%, and the relative standard deviation (RSD) values were within the ranges of 8.2 and 13.5%. The effluent samples were collected at the end of the process treated in a bench-scale MBR treatment system and preconcentrated on solid-phase extraction (SPE) cartridges. Following that procedure, the chemical analysis demonstrated that the MBR system was effective in enalapril 94.3 ± 7.63%, tetracycline 99.4 ± 0.02%, and paracetamol 98.8 ± 0.86% removal. However, the polar metformin was less effectively removed (35.4 ± 12.49%). Moreover, the degradation products were investigated using high-resolution mass spectrometry (HRMS) by quadrupole-time of flight (Q-TOF), which has been indicated a tetracycline metabolite. In order to investigate the environmental impact, the wastewater potential risk was evaluated. The risk quotient (RQ) by measure environmental concentration (MEC) and its predicted no effect concentration (PNEC) ratio (RQ = MEC/PNEC) was between 0.003 (enalapril) to 0.815 (paracetamol). Finally, this work demonstrates that UFLC-MS/MS (ESI-Q) is a sensitive and selective method for drug analysis in wastewater and with ESI-Q-TOF has the accuracy required for determining the degradation products of these compounds. Also, it indicated that membrane bioreactor systems represent a new generation of processes that have proved to outperform conventional treatment showing better effluent quality. The removal capacity studied in this work demonstrates the efficiency of this process.

New Framework To Diagnose the Direct Disposal of Prescribed Drugs in Wastewater - A Case Study of the Antidepressant Fluoxetine.

Intentional or accidental release (direct disposal) of high loads of unused pharmaceuticals into wastewater can go unnoticed. Here, direct disposal of a pharmaceutical drug via the sewer network was identified for the first time using wastewater analysis. An irregularly high load of the antidepressant fluoxetine in raw wastewater (10.5 ± 2.4 g d(-1)) was up to 11 times greater than any other day. National prescription data revealed a predicted daily fluoxetine load for the studied treatment works to be 0.4-1.6 g d(-1). Enantio-selective analysis showed the high load of fluoxetine was present as a racemic mixture, which is typical for fluoxetine in dispensed formulations. As fluoxetine undergoes stereoselective metabolism within the body, a racemic mixture in wastewater suggests a nonconsumed drug was the major contributor of the high load. This was confirmed by its major metabolite norfluoxetine whose load did not increase on this day. Considering the most commonly prescribed formulation of fluoxetine, this increased load accounts for the disposal of ∼915 capsules. Furthermore, as fluoxetine is prescribed as one capsule per day, disposal is unlikely to be at the patient level. It is postulated that direct disposal was from a facility which handles larger quantities of the drug (e.g., a pharmacy).