Photofate of oseltamivir (Tamiflu) and oseltamivir carboxylate under natural and simulated solar irradiation: kinetics, identification of the transformation products, and environmental occurrence

Recent advances in photocatalytic removal of antiviral drugs by Z-scheme and S-scheme heterojunction

The possible impact of antivirals on ecosystems and the emergence of antiviral resistance are the reasons for concern about their environmental release. Consequently, there has been a significant increase in curiosity regarding their presence in both organic and synthetic systems in recent years. The primary objective of this review is to address the void of information regarding the global presence of antiviral drugs in both wastewater and natural water sources. Photocatalytic degradation of pollutants is an eco-friendly, cost-effective method that effectively addresses environmental degradation. The development of efficient photocatalysts remains a significant issue in accelerating the degradation of pollutants, especially when employing solar light. Thus, the development of Z-scheme and S-scheme semiconductor heterojunctions has emerged as a viable method to improve light absorption and enhance the redox capability of photocatalysts. The principles of Z-scheme and S-scheme are reviewed extensively. The degradation route and occurrence of antiviral are discussed briefly. Finally, a short preview of the degradation of antiviral using Z-scheme and S-scheme is also highlighted.

Ranking the risks of eighty pharmaceuticals in surface water of a megacity: A multilevel optimization strategy

Pharmaceuticals in freshwater posed ecological risks to aquatic ecosystem, however, most risk assessments of pharmaceuticals were conducted at screening level, which were limited by the availability of the toxicity data. In this study, risks of 80 pharmaceuticals including 35 antibiotics, 13 antiviral drugs, 13 illicit drugs, and 19 antidepressants in surface water of Beijing were assessed with a proposed multilevel environmental risk optimization strategy. Target pharmaceuticals were detected in surface water samples with the detection frequency from 1.7 % to 100 % and the total concentrations from 31.1 ng/L to 2708 ng/L. Antiviral drugs were the dominant pharmaceuticals. Preliminary screening-level risk assessment indicated that 20 pharmaceuticals posed low to high risks with risk quotient from 0.14 (chloroquine diphosphate) to 27.8 (clarithromycin). Thirteen pharmaceuticals were recognized with low to high risks by an optimized risk assessment method. Of them, the refined probabilistic risk assessment of joint probability curves coupling with a quantitative structure activity relationship-interspecies correlation estimation (QSAR-ICE) model was applied. Clarithromycin, erythromycin and ofloxacin were identified to pose low risks with maximum risk products (RP) of 1.23 %, 0.41 % and 0.35 %, respectively, while 10 pharmaceuticals posed de minimis risks. Structural equation modeling disclosed that human land use and climate conditions influenced the risks of pharmaceuticals by indirectly influencing the concentrations of pharmaceuticals. The results indicated that the multilevel strategy coupling with QSAR-ICE model was appropriate and effective for screening priority pollutants, and the strategy can be used to prioritize pharmaceuticals and other emerging contaminants in the aquatic environment.

Antimicrobial Transformation Products in the Aquatic Environment: Global Occurrence, Ecotoxicological Risks, and Potential of Antibiotic Resistance

The global spread of antimicrobial resistance (AMR) is concerning for the health of humans, animals, and the environment in a One Health perspective. Assessments of AMR and associated environmental hazards mostly focus on antimicrobial parent compounds, while largely overlooking their transformation products (TPs). This review lists antimicrobial TPs identified in surface water environments and examines their potential for AMR promotion, ecological risk, as well as human health and environmental hazards using in silico models. Our review also summarizes the key transformation compartments of TPs, related pathways for TPs reaching surface waters and methodologies for studying the fate of TPs. The 56 antimicrobial TPs covered by the review were prioritized via scoring and ranking of various risk and hazard parameters. Most data on occurrences to date have been reported in Europe, while little is known about antibiotic TPs in Africa, Central and South America, Asia, and Oceania. Occurrence data on antiviral TPs and other antibacterial TPs are even scarcer. We propose evaluation of structural similarity between parent compounds and TPs for TP risk assessment. We predicted a risk of AMR for 13 TPs, especially TPs of tetracyclines and macrolides. We estimated the ecotoxicological effect concentrations of TPs from the experimental effect data of the parent chemical for bacteria, algae and water fleas, scaled by potency differences predicted by quantitative structure-activity relationships (QSARs) for baseline toxicity and a scaling factor for structural similarity. Inclusion of TPs in mixtures with their parent increased the ecological risk quotient over the threshold of one for 7 of the 24 antimicrobials included in this analysis, while only one parent had a risk quotient above one. Thirteen TPs, from which 6 were macrolide TPs, posed a risk to at least one of the three tested species. There were 12/21 TPs identified that are likely to exhibit a similar or higher level of mutagenicity/carcinogenicity, respectively, than their parent compound, with tetracycline TPs often showing increased mutagenicity. Most TPs with increased carcinogenicity belonged to sulfonamides. Most of the TPs were predicted to be mobile but not bioaccumulative, and 14 were predicted to be persistent. The six highest-priority TPs originated from the tetracycline antibiotic family and antivirals. This review, and in particular our ranking of antimicrobial TPs of concern, can support authorities in planning related intervention strategies and source mitigation of antimicrobials toward a sustainable future.

Abiotic transformation of kresoxim-methyl in aquatic environments: Structure elucidation of transformation products by LC-HRMS and toxicity assessment

In this study, abiotic transformation of an important strobilurin fungicide, kresoxim-methyl, was investigated under controlled laboratory conditions for the first time by studying its kinetics of hydrolysis and photolysis, degradation pathways and toxicity of possibly formed transformation products (TPs). The results indicated that kresoxim-methyl showed a fast degradation in pH9 solutions with DT₅₀ of 0.5 d but relatively stable under neutral or acidic environments in the dark. It was prone to photochemical reactions under simulated sunlight, and the photolysis behavior was easily affected by different natural substances such as humic acid (HA), Fe³⁺and NO₃^-which are ubiquitous in natural water, showing the complexity of degradation mechanisms and pathways of this chemical compound. The potential multiple photo-transformation pathways via photoisomerization, hydrolyzation of methyl ester, hydroxylation, cleavage of oxime ether and cleavage of benzyl ether were observed. 18 TPs generated from these transformations were structurally elucidated based on an integrated workflow combining suspect and nontarget screening by high resolution mass spectrum (HRMS), and two of them were confirmed with reference standards. Most of TPs, as far as we know, have never been described before. The in-silico toxicity assessment showed that some of TPs were still toxic or very toxic to aquatic organisms, although they exhibit lower aquatic toxicity compared to the parent compound. Therefore, the potential hazards of the TPs of kresoxim-methyl merits further evaluation.

A sustainable approach for the removal methods and analytical determination methods of antiviral drugs from water/wastewater: A review

In the last years, antiviral drugs especially used for the treatment of COVID-19 have been considered emerging contaminants because of their continuous occurrence and persistence in water/wastewater even at low concentrations. Furthermore, as compared to antiviral drugs, their metabolites and transformation products of these pharmaceuticals are more persistent in the environment. They have been found in environmental matrices all over the world, demonstrating that conventional treatment technologies are unsuccessful for removing them from water/wastewater. Several approaches for degrading/removing antiviral drugs have been studied to avoid this contamination. In this study, the present level of knowledge on the input sources, occurrence, determination methods and, especially, the degradation and removal methods of antiviral drugs are discussed in water/wastewater. Different removal methods, such as conventional treatment methods (i.e. activated sludge), advanced oxidation processes (AOPs), adsorption, membrane processes, and combined processes, were evaluated. In addition, the antiviral drugs and these metabolites, as well as the transformation products created as a result of treatment, were examined. Future perspectives for removing antiviral drugs, their metabolites, and transformation products were also considered.

Antiviral drugs against influenza: Treatment methods, environmental risk assessment and analytical determination

Over the past few years, antiviral drugs against influenza are considered emerging contaminants since they cause environmental toxicity even at low concentrations. They have been found in environmental matrices all around the world, showing that conventional treatment methods fail to remove them from water and wastewater. In addition, the metabolites and transformation products of these drugs can be more persistent than original in the environment. Several techniques to degrade/remove antiviral drugs against influenza have been investigated to prevent this contamination. In this study, the characteristics of antiviral drugs against influenza, their measurement by analytical methods, and their removal in both water and wastewater treatment plants (WWTPs) were presented. Different treatment methods, such as traditional procedures (biological processes, filtration, coagulation, flocculation, and sedimentation), advanced oxidation processes (AOPs), adsorption and combined methods, were assessed. Ecotoxicological effects of both the antiviral drug and its metabolites as well as the transformation products formed as a result of treatment were evaluated. In addition, future perspectives for improving the removal of antiviral drugs against influenza, their metabolites and transformation products were further discussed. The research indicated that the main tested techniques in this study were ozonation, photolysis and photocatalysis. Combined methods, particularly those that use renewable energy and waste materials, appear to be the optimum approach for the treatment of effluents containing antiviral drugs against influenza. In light of high concentrations or probable antiviral resistance, this comprehensive assessment suggests that antiviral drug monitoring is required, and some of those substances may cause toxicological effects.

Montmorillonite promoted photodegradation of amlodipine in natural water via formation of surface complexes

The photolysis of amlodipine (AML) as a ubiquitous pollutant in natural water has been extensively studied. Montmorillonite (MMT), a major component of suspended particles in surface aquifers, plays key roles in the natural transportation and transformation of organic contaminants in the environment. However, literature has scarcely focused on whether and how suspended particles affect the phototransformation of AML. This study systematically investigated the phototransformation behavior of AML in MMT suspensions under simulated sunlight. The results obtained showed that MMT significantly enhanced the photolysis of AML. The photodegradation of AML in 0.05 g/L MMT suspension reached 92.2 % after 3 h irradiation under the simulated sunlight. The photodecomposition followed the pseudo-first-order kinetic with a rate constant of 0.803 h^-1 in the presence of 0.05 g/L MMT, which is about 19 times larger than that in the absence of MMT (0.0421 h^-1). Further mechanistic investigation suggested that MMT accelerated the photolysis of AML by the formation of surface complexes between cationic amino groups of AML and the negatively charged sites on MMT surface, which greatly facilitated light absorption and electron transfer for the production of cationic radical AML^+·. Meanwhile, the hydroxyl radicals generated by irradiated MMT also played an important role in the photocatalytic degradation of AML. The probable photodegradation pathways of AML in MMT suspension further supported the proposed mechanisms. The toxicity evaluation of phototransformation products of AML with ECOSAR program indicated that photolysis could reduce its potential threats. These findings reveal an important and previously overlooked phototransformation mechanisms of AML in the presence of MMT clays, which is of importance in assessing the environmental fate of other similar organic contaminants.

Hydroxychloroquine in COVID-19: therapeutic promises, current status, and environmental implications

The outbreak of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected the entire world with its infectious spread and mortality rate. The severe cases of coronavirus disease 2019 (COVID-19) are characterized by hypoxia and acute respiratory distress syndrome. In the absence of any specific treatment, just the preventive and supportive care options are available. Therefore, much focus is given to assess the available therapeutic options not only to avoid acute respiratory failure and hypoxia but also to reduce the viral load to control the severity of the disease. The antimalarial drug hydroxychloroquine (HCQ) is among the much-discussed drugs for the treatment and management of COVID-19 patients. This article reviews the therapeutic potential of HCQ in the treatment of COVID-19 based on the available in vitro and clinical evidence, current status of registered HCQ-based clinical trials investigating therapeutic options for COVID-19, and environmental implications of HCQ.

Enhanced phototransformation of atorvastatin by polystyrene microplastics: Critical role of aging

Reactive oxygen species (ROS) generated from light irradiation of microplastics (MPs) can potentially affect the environmental fate of organic contaminants when they coexist in the same environment. This study investigated the effect of polystyrene (PS) MPs with different aging degrees on the phototransformation of atorvastatin (ATV) under simulated sunlight. Results showed that the presence of PS MPs facilitated the phototransformation of ATV, and the degradation rate was linearly correlated with the aging degree (i.e., carbonyl index) of MPs. The enhanced effects mainly depended on the contents of oxygen-containing functional groups of PS MPs, which increased the absorption of light energy and the generation of ROS (e.g., singlet oxygen (¹O₂) and triplet-excited state PS (³PS*)). Quenching experiments indicated that ¹O₂ generated from photosensitization of PS was the major contributor to the increased phototransformation of ATV. Additionally, the role of ³PS* became more important in the photodegradation mediated by higher degree aged MPs because much more ¹O₂ was generated from the ³PS* . PS MPs also increased the types and yields of degradation products, especially for higher degree aged MPs, despite the low effect on leachate toxicity. The findings provide a novel insight into the critical role of MPs in the fate of organic contaminants in aquatic environments.

Antiviral drugs in aquatic environment and wastewater treatment plants: A review on occurrence, fate, removal and ecotoxicity

The environmental release of antiviral drugs is of considerable concern due to potential ecosystem alterations and the development of antiviral resistance. As a result, interest on their occurrence and fate in natural and engineered systems has grown substantially in recent years. The main scope of this review is to fill the void of information on the knowledge on the worldwide occurrence of antiviral drugs in wastewaters and natural waters and correlate their levels with their environmental fate. According to the conducted literature survey, few monitoring data exists for several European countries, such as Germany, France, and the UK. Lesser data are available for Asia, where approximately 80% of the studies focus on Japan. Several articles study the occurrence of mostly antiretroantivirals in sub-Saharan African countries, while there is a lack of data for other developing regions of the world, including the rest of Africa, South America, and the biggest part of Asia. An importantly smaller number of studies exists for North America, while no studies exist for Oceania. The against innfluenza drug oseltamivir along with its active carboxy metabolite is found to be the most studied antiviral drug. The distribution of antiviral drugs across all geographic regions varies from low ng L^-1 to high μg L^-1 levels, in some cases, even in surface waters. This overarching review reveals that monitoring of antiviral drugs is necessary, and some of those compounds may require toxicological attention, in the light of either spatial and temporal high concentration or potential antiviral resistance. Based on the information provided herein, the need for a better understanding of the water quality hazards posed by antiviral drugs existence in wastewater outputs and freshwater ecosystems is demosntrated. Finally, the future challenges concerning the occurrence, fate, and potential ecotoxicological risk to organisms posed by antiviral drug residues are discussed.

The role of photodegradation in the environmental fate of hydroxychloroquine

For many organic pollutants present in surface waters, photolysis is considered as a major abiotic degradation process. The present study aimed to explore the role of photolysis in the environmental fate of hydroxychloroquine (HCQ) for the first time. The photolytic degradation of HCQ was investigated under simulated solar radiation (300-800 nm) in ultrapure, spring, river, and sea water. The effect of pH on the photodegradation rate was substantial and it was observed that degradation was faster at higher pH-values. Obtained half-lives ranged from 5.5 min at pH 9 to 23.1 h at pH 4. Humic acids, nitrate and iron(III) enhanced photodegradation of HCQ due to formation of hydroxyl radicals and its attack on HCQ molecule. In contrast, chloride, sulfate and bromide inhibited photodegradation. Additionally, the humic acids exhibited a dual role, photosensitization and inner filter effect. The study of the reaction kinetics was performed with HPLC-PDA, while the identification of degradation products formed during photolytic degradation was carried out using HPLC-MS/MS and NMR spectroscopy. The hydroxylation was recognized as the dominant path of photoproducts formation. The results of this research reveal the importance of photolytic degradation in environmental fate of HCQ and enable a better understanding of its behavior in the environment. Moreover, the results showing the significant effect of pH on the photodegradation of HCQ can be very useful in water treatment processes.

Preliminary results on the uptake and biochemical response to water-exposure of Tamiflu® (oseltamivir phosphate) in two marine bivalves

Tamiflu® (oseltamivir phosphate, OST) is an antiviral drug used for the pandemic treatment of avian influenza but few data are available regarding its toxicity. It should be noted that acute adverse responses are not likely to occur due to low environmental presence of this drug. Nonetheless, water concentration levels of this compound may reach the µg/L range under influenza episodes. Bivalves are reliable sentinels of chemical exposure due to their low metabolism; however, biotransformation of drugs does occur in these aquatic invertebrates. Two species of bivalves, namely mussels Mytilus galloprovincialis and clams Ruditapes philippinarum, were exposed for 48 h to 100 µg/L OST. Hemolymph from control and treated bivalves was withdrawn and the presence of OST and its metabolite oseltamivir carboxylate (OST-C) determined by LC-MS/MS. Gills and digestive gland were excised from control and exposed bivalves and carboxylesterase (CE) activities measured using different substrates. In addition, antioxidant defences and lipid peroxidation levels were determined. Higher metabolism of OST seemed to occur in mussels, since both OST and OST-C were found in hemolymph, whereas in clams only the parent compound was detected. In contrast, biomarker responses were more evident in exposed clams which indicate that this species may be considered as more sensitive to OST exposure. CE-related activities successfully reflected OST exposure, with substrates 1-naphthyl acetate (1NA) and 1-naphthyl butyrate (1NB) displaying the highest sensitivity in the two bivalve species. Data thus indicate the usefulness of CE-related activities as biomarkers for OST exposure in bivalves.

Photolysis of atorvastatin in aquatic environment: Influencing factors, products, and pathways

Atorvastatin (ATV), a second generation cholesterol-lowering drug, is detected frequently in natural water because of its extensive use and incomplete removal from wastewater. In this study, the photochemical behavior of ATV under simulated solar irradiation was systematically investigated in order to assess the potential of photolysis as its transformation pathway in aquatic environment. The quantum yield of ATV direct photolysis was determined to be 0.0041. Among various water components investigated, including pH, Suwannee River Fulvic Acid (SRFA), Fe³⁺, HCO₃^-, SO₄^2- and NO₃^-, the major factors contributing to the indirect photolysis of ATV were SRFA and NO₃^-, and the co-existence of SRFA and NO₃^- showed no interaction in synthetic water containing the above water components. The results were further verified in natural water samples. Singlet oxygen (¹O₂) played dominant role in the indirect photolysis of ATV, and the contributions of ¹O₂ and ·OH to the photolysis of ATV in the solution with optimum combination of water components were calculated to be 67.14% and 0.66%, respectively. Nine phototransformation intermediates were identified by liquid chromatography - time-of-flight - mass spectrometry (LC-TOF-MS), and the degradation pathways were speculated as hydroxyl addition, pyrrole-ring open and debenzamide reactions. In addition, the evolution of products in the degradation process showed that the ring-opened product P416 and hydroxylation product P575 still remained at a certain level after two days of photodegradation, which may accumulate and cause additional ecological risks. This study provides significant information for understanding the risk and fate of ATV in aquatic environment.

Antimicrobial Use and Ecotoxicological Risks from Pandemics and Epidemics

Pandemics and epidemics represent an uncharacterized risk to human health—ranging from episodic to chronic pathogens and from chronic diseases. Society's capacity to respond to these threats with an even increasing range of pharmaceuticals presents a novel challenge to environmental scientists and public health officials. The environmental and human health risks posed by society's medical response to pandemics and epidemics will be discussed in the context of influenza as a case study and a range of existing pathogen and noncommunicable pathogen risks.

In vivo mallard experiments indicate that zanamivir has less potential for environmental influenza A virus resistance development than oseltamivir

Neuraminidase inhibitors are a cornerstone of influenza pandemic preparedness before vaccines can be mass-produced and thus a neuraminidase inhibitor-resistant pandemic is a serious threat to public health. Earlier work has demonstrated the potential for development and persistence of oseltamivir resistance in influenza A viruses exposed to environmentally relevant water concentrations of the drug when infecting mallards, the natural influenza reservoir that serves as the genetic base for human pandemics. As zanamivir is the major second-line neuraminidase inhibitor treatment, this study aimed to assess the potential for development and persistence of zanamivir resistance in an in vivo mallard model; especially important as zanamivir will probably be increasingly used. Our results indicate less potential for development and persistence of resistance due to zanamivir than oseltamivir in an environmental setting. This conclusion is based on: (1) the lower increase in zanamivir IC₅₀ conferred by the mutations caused by zanamivir exposure (2-17-fold); (2) the higher zanamivir water concentration needed to induce resistance (at least 10 µg l^-1); (3) the lack of zanamivir resistance persistence without drug pressure; and (4) the multiple resistance-related substitutions seen during zanamivir exposure (V116A, A138V, R152K, T157I and D199G) suggesting lack of one straight-forward evolutionary path to resistance. Our study also adds further evidence regarding the stability of the oseltamivir-induced substitution H275Y without drug pressure, and demonstrates the ability of a H275Y-carrying virus to acquire secondary mutations, further boosting oseltamivir resistance when exposed to zanamivir. Similar studies using influenza A viruses of the N2-phylogenetic group of neuraminidases are recommended.

Removal of 30 active pharmaceutical ingredients in surface water under long-term artificial UV irradiation

This study investigated the i) kinetics, and ii) proportion of photolysis of 30 relatively stable active pharmaceutical ingredients (APIs) during artificial UV irradiation for 28 d in ammonium acetate buffer, filtered and unfiltered river water. Buffer was included to control removal kinetics under stable pH conditions and without particulate matter. Dark controls were used to determine removal due to other processes than photolysis and calculate the proportion of photolysis of the total removal. The removal of each API in each matrix was determined using online solid phase extraction/liquid chromatography tandem mass spectrometry (online SPE/LC-MS/MS). Most APIs transformed during the 28 d of UV irradiation and the dark controls showed that photolysis was the major removal process for the majority of the APIs studied. The half-lives ranged from 6 h (amitriptyline) in unfiltered river water to 884 h (37 d, carbamazepine) in buffer. In unfiltered river water, the proportion of APIs with short half-lives (<48 h) was much higher (29%) than in the other matrices (4%), probably due to additional organic carbon, which could have promoted indirect photolysis. Furthermore, two APIs, memantine and fluconazole, were stable in all three matrices, while alprazolam was stable in buffer and unfiltered river water and four additional APIs were stable in buffer. Considering the relatively long-term UV-exposure, this study enabled the investigation of environmentally relevant half-lives in natural waters. Many APIs showed high persistence, which is environmentally concerning and emphasizes the importance of further studies on their environmental fate and effects.

Fate of new three anti-influenza drugs and one prodrug in the water environment

We evaluated the environmental fate of new three anti-influenza drugs, favipiravir (FAV), peramivir (PER), and laninamivir (LAN), and an active prodrug of LAN, laninamivir octanoate (LANO), in comparison with four conventional drugs, oseltamivir (OS), oseltamivir carboxylate (OC), amantadine (AMN), and zanamivir (ZAN) by photodegradation, biodegradation, and sorption to river sediments. In addition, we conducted 9-month survey of urban rivers in the Yodo River basin from 2015 to 2016 (including the influenza season) to investigate the current status of occurrence of these drugs in the river environment. The results clearly showed that FAV and LAN rapidly disappeared through photodegradation (half-lives 1 and 8 h, respectively), followed by LANO which gradually disappeared through biodegradation (half-life, 2 days). The remained PER and conventional drugs were, however, persistent and transported from upstream to downstream sites. Rates of their sorption to river sediments were negligibly small. Detected levels remained were in the range from N.D. to 89 ng/L for the river waters and from N.D. to 906 ng/L in sewage effluent. However, all of the remained drugs were effectively removed by ozonation after chlorination at a sewage treatment plant. These findings suggest the importance of introducing ozonation for reduction of pollution loads in rivers, helping to keep river environments safe. To the best of our knowledge, this is the first evaluation of the removal effects of natural sunlight, biodegradation, and sorption to river sediments on FAV, PER, LAN, LANO, and a conventional drug, AMN.

Risk of resistant avian influenza A virus in wild waterfowl as a result of environmental release of oseltamivir

Oseltamivir is the best available anti-influenza drug and has therefore been stockpiled worldwide in large quantities as part of influenza pandemic preparedness planning. The active metabolite oseltamivir carboxylate (OC) is stable and is not removed by conventional sewage treatment. Active OC has been detected in river water at concentrations up to 0.86 µg/L. Although the natural reservoir hosts of influenza A virus (IAV) are wild waterfowl that reside in aquatic environments, the ecologic risks associated with environmental OC release and its potential to generate resistant viral variants among wild birds has largely been unknown. However, in recent years a number of in vivo mallard (Anas platyrhynchos) studies have been conducted regarding the potential of avian IAVs to become resistant to OC in natural reservoir birds if these are drug exposed. Development of resistance to OC was observed both in Group 1 (N1) and Group 2 (N2, N9) neuraminidase subtypes, when infected ducks were exposed to OC at concentrations between 0.95 and 12 µg/L in their water. All resistant variants maintained replication and transmission between ducks during drug exposure. In an A(H1N1)/H274Y virus, the OC resistance mutation persisted without selective drug pressure, demonstrating the potential of an IAV with a permissive genetic background to acquire and maintain OC resistance, potentially allowing circulation of the resistant variant among wild birds. The experimental studies have improved the appreciation of the risks associated with the environmental release of OC related to resistance development of avian IAVs among wild birds. Combined with knowledge of efficient methods for improved sewage treatment, the observations warrant implementation of novel efficient wastewater treatment methods, rational use of anti-influenza drugs, and improved surveillance of IAV resistance in wild birds.

Fate of three anti-influenza drugs during ozonation of wastewater effluents - degradation and formation of transformation products

Anti-influenza drugs constitute a key component of pandemic preparedness plans against influenza. However, the occurrence of such drugs in water environments, the potential of resistance development in the natural hosts, and the risk for transmission of antiviral resistance to humans call for measures to increase removal in wastewater treatment plants (WWTPs). In this study, removal of three anti-influenza drugs; amantadine (AM), oseltamivir carboxylate (OC) and zanamivir (ZA), and formation/removal of their transformation products during ozonation of wastewater effluents from two Swedish WWTPs in Uppsala and Stockholm were studied. The removal profile of target antivirals and formation/removal of their transformation products were studied by liquid chromatography/high resolution mass spectrometry. 3.5 h of ozone exposure (total dose of ozone 5.95 g) led to complete removal of the three anti-influenza drugs with a degradation in the following order ZA > OC > AM. Two, five and one transformation products were identified and semi-quantified for AM, OC and ZA, respectively. Increasing and later decreasing transformation products concentration followed the decrease in concentration of target compounds. All transformation products detected, except one of AM in wastewater from Stockholm WWTP, were removed at the end of the experiment. The removal efficiency was higher for all studied compounds in wastewater from Uppsala WWTP, which had lower TOC and COD values, less phosphorus, and also higher pH in the water. Ozonation thus offers multiple benefits through its potential to degrade influenza antivirals, hence decrease the risk of environmental resistance development, in addition to degrading other pharmaceuticals and resistant microorganisms.

Adsorption removal of antiviral drug oseltamivir and its metabolite oseltamivir carboxylate by carbon nanotubes: Effects of carbon nanotube properties and media

This investigation evaluated the adsorption behavior of the antiviral drugs of oseltamivir (OE) and its metabolites (i.e., oseltamivir carboxylate (OC)) on three types of carbon nanotubes (CNTs) including single-walled CNT (SWCNT), multi-walled CNT (MWCNT), and carboxylated SWCNT (SWCNT-COOH). CNTs can efficiently remove more than 90% of the OE and OC from aqueous solution when the initial concentration was lower than 10(-4) mmol/L. The Polanyi-Manes model depicted the adsorption isotherms of OE and OC on CNTs better than the Langmuir and Freundlich models. The properties of OE/OC and the characteristics of CNTs, particularly the oxygen functional groups (e.g., SWCNT-COOH) played important roles during the adsorption processes. OE showed a higher adsorption affinity than OC. By comparing the different adsorbates adsorption on each CNT and each adsorbate adsorption on different CNTs, the adsorption mechanisms of hydrophobic interaction, electrostatic interaction, van der Waals force, and H-bonding were proposed as the contributing factors for OE and OC adsorption on CNTs. Particularly, for verifying the contribution of electrostatic interaction, the changes of adsorption partition efficiency (Kd) of OE and OC on CNTs were evaluated by varying pH from 2 to 11 and the importance of isoelectric point (pHIEP) of CNTs on OE and OC adsorption was addressed.

Oseltamivir Resistance in Influenza A(H6N2) Caused by an R292K Substitution in Neuraminidase Is Not Maintained in Mallards without Drug Pressure

Background

Wild waterfowl is the natural reservoir of influenza A virus (IAV); hosted viruses are very variable and provide a source for genetic segments which can reassort with poultry or mammalian adapted IAVs to generate novel species crossing viruses. Additionally, wild waterfowl act as a reservoir for highly pathogenic IAVs. Exposure of wild birds to the antiviral drug oseltamivir may occur in the environment as its active metabolite can be released from sewage treatment plants to river water. Resistance to oseltamivir, or to other neuraminidase inhibitors (NAIs), in IAVs of wild waterfowl has not been extensively studied.

Aim and Methods

In a previous in vivo Mallard experiment, an influenza A(H6N2) virus developed oseltamivir resistance by the R292K substitution in the neuraminidase (NA), when the birds were exposed to oseltamivir. In this study we tested if the resistance could be maintained in Mallards without drug exposure. Three variants of resistant H6N2/R292K virus were each propagated during 17 days in five successive pairs of naïve Mallards, while oseltamivir exposure was decreased and removed. Daily fecal samples were analyzed for viral presence, genotype and phenotype.

Results and Conclusion

Within three days without drug exposure no resistant viruses could be detected by NA sequencing, which was confirmed by functional NAI sensitivity testing. We conclude that this resistant N2 virus could not compete in fitness with wild type subpopulations without oseltamivir drug pressure, and thus has no potential to circulate among wild birds. The results of this study contrast to previous observations of drug induced resistance in an avian H1N1 virus, which was maintained also without drug exposure in Mallards. Experimental observations on persistence of NAI resistance in avian IAVs resemble NAI resistance seen in human IAVs, in which resistant N2 subtypes do not circulate, while N1 subtypes with permissive mutations can circulate without drug pressure. We speculate that the phylogenetic group N1 NAs may easier compensate for NAI resistance than group N2 NAs, though further studies are needed to confirm such conclusions.

Prediction, risk and control of anti-influenza drugs in the Yodo River Basin, Japan during seasonal and pandemic influenza using the transmission model for infectious disease

To reduce the risk of producing an anti-influenza drug-resistant virus from wildfowl, it is important to estimate the concentrations of anti-influenza drugs in river water during an influenza pandemic and to evaluate the concentrations that keep river basins safe. We first created a newly designed infectious disease transmission model based on the Susceptible-Infected-Recovered model. This model was then applied to replicate the transitional changes of three representative anti-influenza drugs, oseltamivir (OS), oseltamivir carboxylate (OC), and zanamivir (ZAN), in the urban area of the Yodo River system, which is one of the major basins in Japan with a population of 12 million; this region contains nearly 10% of the country's flu cases during the seasonal influenza outbreaks between 1999 and 2010. The results showed high correlations between the estimated number of influenza cases and the concentrations of the three investigated anti-influenza drugs with the reported values. We then extended the application of the model to estimate the concentration level of these anti-influenza drugs during the several influenza pandemics. The maximum estimated concentrations for OS, OC, and ZAN were known to be 260-450ng/L, 1500-2600ng/L and 40-70ng/L, respectively, at the peak of the influenza pandemic. These results suggest that it is possible that a drug-resistant influenza virus can originate from wild mallard when there is a large-scale influenza pandemic. However, ozonation before discharge at sewage treatment plants is known to significantly reduce the release of such drugs into the aquatic environment to reduce the risk of a drug-resistant virus outbreak. It was also suggested that further environmental risk could be reduced by decreasing these concentrations further in river water.

Photocatalytic degradation of the antiviral drug Tamiflu by UV-A/TiO2: Kinetics and mechanisms

The photocatalytic degradation of the antiviral drug Tamiflu (oseltamivir phosphate, OP) by TiO2 - P25, ST-01 and ATO was investigated in aqueous solution under ultraviolet (UV-A) irradiation. The photocatalysis of OP is well described by pseudo-first-order kinetics with r2>98.0% for all cases. The kinetic constant of P25 with 80% anatase and 20% rutile (0.040 min(-1)) is 4 and 10 times higher than that of ATO and ST-01 with 100% purity of anatase, respectively. We examined the effects of the catalyst loading and initial OP concentration on the photodegradation of OP, and used potassium iodine, isopropanol, and calcium fluorine as radical quenchers to evaluate the contributions of the hydroxyl radical (OH) and photo hole (h+) in the photodegradation. Results confirmed that 80% of the contribution came from the OH species. Although more than 95% of the OP (21 μM) was removed after 80 min of UV-A irradiation with 20 and 100 mg L(-1) P25, the removal efficiencies of total organic carbon (TOC) were only 45.6% and 67.0%, respectively, after 360 min UV-A irradiation. Based on an intermediate analysis by HPLC coupled with a triple quadrupole spectrometer and an ion trap mass spectrometer, typical intermediate species such as hydration derivatives, hydroxyl substitutes and keto-derivatives were identified and possible degradation pathways of OP by P25 were proposed.

Detection of peramivir and laninamivir, new anti-influenza drugs, in sewage effluent and river waters in Japan

This is the first report of the detection of two new anti-influenza drugs, peramivir (PER) and laninamivir (LAN), in Japanese sewage effluent and river waters. Over about 1 year from October 2013 to July 2014, including the influenza prevalence season in January and February 2014, we monitored for five anti-influenza drugs—oseltamivir (OS), oseltamivir carboxylate (OC), zanamivir (ZAN), PER, and LAN—in river waters and in sewage effluent flowing into urban rivers of the Yodo River system in Japan. The dynamic profiles of these anti-influenza drugs were synchronized well with that of the numbers of influenza patients treated with the drugs. The highest levels in sewage effluents and river waters were, respectively, 82 and 41 ng/L (OS), 347 and 125 ng/L (OC), 110 and 35 ng/L (ZAN), 64 and 11 ng/L (PER), and 21 and 9 ng/L (LAN). However, application of ozone treatment before discharge from sewage treatment plants was effective in reducing the levels of these anti-influenza drugs in effluent. The effectiveness of the ozone treatment and the drug dependent difference in susceptibility against ozone were further evidenced by ozonation of a STP effluent in a batch reactor. These findings should help to promote further environmental risk assessment of the generation of drug-resistant influenza viruses in aquatic environments.

Influenza A(H7N9) virus acquires resistance-related neuraminidase I222T substitution when infected mallards are exposed to low levels of oseltamivir in water

Influenza A virus (IAV) has its natural reservoir in wild waterfowl, and new human IAVs often contain gene segments originating from avian IAVs. Treatment options for severe human influenza are principally restricted to neuraminidase inhibitors (NAIs), among which oseltamivir is stockpiled in preparedness for influenza pandemics. There is evolutionary pressure in the environment for resistance development to oseltamivir in avian IAVs, as the active metabolite oseltamivir carboxylate (OC) passes largely undegraded through sewage treatment to river water where waterfowl reside. In an in vivo mallard (Anas platyrhynchos) model, we tested if low-pathogenic avian influenza A(H7N9) virus might become resistant if the host was exposed to low levels of OC. Ducks were experimentally infected, and OC was added to their water, after which infection and transmission were maintained by successive introductions of uninfected birds. Daily fecal samples were tested for IAV excretion, genotype, and phenotype. Following mallard exposure to 2.5 μg/liter OC, the resistance-related neuraminidase (NA) I222T substitution, was detected within 2 days during the first passage and was found in all viruses sequenced from subsequently introduced ducks. The substitution generated 8-fold and 2.4-fold increases in the 50% inhibitory concentration (IC50) for OC (P < 0.001) and zanamivir (P = 0.016), respectively. We conclude that OC exposure of IAV hosts, in the same concentration magnitude as found in the environment, may result in amino acid substitutions, leading to changed antiviral sensitivity in an IAV subtype that can be highly pathogenic to humans. Prudent use of oseltamivir and resistance surveillance of IAVs in wild birds are warranted.

LC-HRMS suspect screening for detection-based prioritization of iodinated contrast media photodegradates in surface waters

The objective of the study was to demonstrate the applicability of suspect screening for the detection of six iodinated contrast media (ICM) and their phototransformation products (TPs) in surface waters. First, a photodegradation study of ICM in surface water using a sunlight lab-scale simulator was performed. By means of a guided differential sample analysis, the exact masses of the molecular ions and the retention times of TPs were identified. Positive findings were filtered manually generating a suspect list of 108 photoproducts. Following a generic solid-phase extraction of surface water samples, LC-HRMS was used to screen for the presence of the compounds previously detected in the photodegradation samples. On the basis of detection frequencies (>50% of the samples), 11 TPs were prioritized and their structures elucidated by HRMS and NMR. In the real surface water samples, median concentration of parent compounds was 110 ng/L reaching up to 6 μg/L for iomeprol, while TPs were found at median concentration of 8 ng/L, reaching up to 0.4 μg/L for iomeprol TP651-B. In summary, the proposed screening approach facilitates the evaluation of the degradation of polar compounds at a real scale with a fast detection of TPs without prior availability of the standards.

Identification of chlorinated oligomers formed during anodic oxidation of phenol in the presence of chloride

Chlorinated oligomer intermediates formed during the anodic electrochemical oxidation of phenol with a boron-doped diamond electrode were studied at two different concentrations of chloride (5mM and 50mM). Under the same ionic strength, with sodium sulfate being the make-up ion, a 10-fold increase in Cl(-) led to removal rates 10.8, 1.5, and 1.4 times higher for phenol, TOC, and COD, respectively. Mono-, di- and trichlorophenols resulting from electrophilic substitution were the identified by-products. Nevertheless, discrepancies between theoretical and measured TOC values along with gaps in the mass balance of chlorine-containing species indicated the formation of unaccounted-for chlorinated by-products. Accurate mass measurements by liquid chromatography quadrupole time-of-flight mass spectrometry and MS-MS fragmentation spectra showed that additional compounds formed were dimers and trimers of phenol with structures similar to triclosan and polychlorinated dibenzo-p-dioxins.

Contaminant-mediated photobleaching of wetland chromophoric dissolved organic matter

Photolytic transformation of organic contaminants in wetlands can be mediated by chromophoric dissolved organic matter (CDOM), which in turn can lose its reactivity from photobleaching. We collected water from a small agricultural wetland (Ohio), Kawai Nui Marsh (Hawaii), the Everglades (Florida), and Okefenokee Swamp (Georgia) to assess the effect of photobleaching on the photofate of two herbicides, acetochlor and isoproturon. Analyte-spiked water samples were irradiated using a solar simulator and monitored for changes in CDOM light absorbance and dissolved oxygen. Photobleaching did not significantly impact the indirect photolysis rates of either herbicide over 24 hours of irradiation. Surprisingly, the opposite effect was observed with isoproturon, which accelerated DOM photobleaching. This phenomenon was more pronounced in higher-CDOM waters, and we believe that the redox pathway between triplet-state CDOM and isoproturon may be responsible for our observations. By contrast, acetochlor indirect photolysis was dependent on reaction with the hydroxyl radical and did not accelerate photobleaching of wetland water as much as isoproturon. Finally, herbicide indirect photolysis rate constants did not correlate strongly to any one chemical or optical property of the sampled waters.

Survey of the occurrence of pharmaceuticals in Spanish finished drinking waters

Fifty samples of finished drinking waters (FDWs) from Spain covering 12 million inhabitants were tested for 53 pharmaceuticals pertaining to 12 different Anatomical Therapeutic Chemical (ATC) classification system codes. The studied compounds are a combination of most commonly consumed pharmaceuticals with other barely reported in the literature. Five compounds, azithromycin, clarithromycin, erythromycin, sulfamethoxazole, and ibuprofen were tentatively identified by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in some samples (2 to 15 %), but only ibuprofen and azithromycin could be confirmed when analyzed by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) with a quadrupole-Orbitrap instrument. Concentration levels of ibuprofen in the positive samples ranged from 12 to 17 ng/L (n = 6) while for azithromycin values from 5 to 9.5 ng/L (n = 3) were found. Ibuprofen fragmentation behaviour in different mass spectrometry instrument configurations (triple quadrupole, quadrupole-ion trap, and quadrupole-Orbitrap) was evaluated.

A critical assessment of the photodegradation of pharmaceuticals in aquatic environments: defining our current understanding and identifying knowledge gaps

This work presents a critical assessment of the state and quality of knowledge around the aquatic photochemistry of human- and veterinary-use pharmaceuticals from laboratory experiments and field observations. A standardized scoring rubric was used to assess relevant studies within four categories: experimental design, laboratory-based direct and indirect photolysis, and field/solar photolysis. Specific metrics for each category are defined to evaluate various aspects of experimental design (e.g., higher scores are given for more appropriate characterization of light source wavelength distribution). This weight of evidence-style approach allowed for identification of knowledge strengths and gaps covering three areas: first, the general extent of photochemical data for specific pharmaceuticals and classes; second, the overall quality of existing data (i.e., strong versus weak); and finally, trends in the photochemistry research around these specific compounds, e.g. the observation of specific and consistent oversights in experimental design. In general, those drugs that were most studied also had relatively good quality data. The four pharmaceuticals studied experimentally at least ten times in the literature had average total scores (lab and field combined) of ≥29, considered decent quality; carbamazepine (13 studies; average score of 31), diclofenac (12 studies; average score of 31), sulfamethoxazole (11 studies; average score of 34), and propranolol (11 studies; average score of 29). Major oversights and errors in data reporting and/or experimental design included: lack of measurement and reporting of incident light source intensity, lack of appropriate controls, use of organic co-solvents in irradiation solutions, and failure to consider solution pH. Consequently, a number of these experimental parameters were likely a cause of inconsistent measurements of direct photolysis rate constants and quantum yields, two photochemical properties that were highly variable in the literature. Overall, the assessment rubric provides an objective and scientifically-defensible set of metrics for assessing the quality of a study. A major recommendation is the development of a method guideline, based on this rubric, for conducting and reporting on photochemical studies that would produce consistent and reliable data for quantitative comparison across studies. Furthermore, an emphasis should be placed on conducting more dual-fate studies involving controlled photolysis experiments in natural sunlight, and whole system fate studies in either natural or artificial systems. This would provide accurate data describing the actual contribution of photolysis to the overall fate of pharmaceuticals in the environment.

Evaluation of the phototransformation of the antiviral zanamivir in surface waters through identification of transformation products

The antiviral zanamivir has been recently reported to occur in surface waters where its presence may lead to the selection of resistant strains of virus in aquatic fauna. In order to evaluate the fate of zanamivir in surface waters, its susceptibility to phototransformation was evaluated using simulated and natural sunlight. Upon exposure of aqueous solutions (20μgL(-1)) to simulated sunlight, zanamivir in surface water degraded at t1/23.6h. Under natural sunlight in surface water about 30% of the initial concentration of the antiviral disappeared within 18 days. The experiments with surface water showed similar effect as humic acid addition with expected decreasing effect on degradation while nitrate addition showed increasing effect. In the experiments with artificial sunlight at high concentrations of zanamivir, four photoproducts were tentatively identified by hydrophilic interaction chromatography-LTQ-Orbitrap-MS, showing [M+H](+) ions at m/z 112 (TP111), m/z 275 (TP274), m/z 323 (TP322), and m/z 333 (TP332). However at 20μgL(-1) only the formation of the recalcitrant TP111 was observed. The proposed structures were rationalized by photolysis mechanisms. Photoproduct TP111 was confirmed with a commercially available standard (isocytosine). In summary, the findings suggest that the photodegradation of zanamivir in surface waters proceeds with slow kinetics.

Profile and behavior of antiviral drugs in aquatic environments of the Pearl River Delta, China

Occurrence and behavior of six antiviral pharmaceuticals (acyclovir, ganciclovir, oseltamivir, ribavirin, stavudine and zidovudine) and one active metabolite oseltamivir carboxylate were investigated in wastewater, landfill leachate, river water, reservoir and well water in the vicinity of municipal landfills in the Pearl River Delta, China. Acyclovir was the only antiviral detected in the wastewater at 177-406 (mean=238) and 114-205 (mean=154) ng L(-1) in the influent and final effluent, respectively. Aerobic biodegradation appeared to be the main process for the elimination of acyclovir in the wastewater. Acyclovir was also the only antiviral quantitatively detected in the Pearl River and its tributaries, with a maximum concentration up to 113 ng L(-1). Treated wastewater was a major source of acyclovir in the rivers. The highest concentration of acyclovir was observed in winter in the river water and the dilution effect by precipitation was suggested to be the dominant factor impacting the seasonal pattern of acyclovir in the rivers. No antivirals were quantitatively detected in the well water whereas acyclovir was frequently detected in the reservoirs at a maximal concentration of 33.6 ng L(-1) in the vicinity of the municipal landfills. However, source identification and fate of acyclovir in the reservoirs pend on further research.

Mass balance of anti-influenza drugs discharged into the Yodo River system, Japan, under an influenza outbreak

In February 2011, at the peak of an influenza outbreak, we performed a comprehensive analysis of the mass balances of four anti-influenza drugs-oseltamivir (OS), oseltamivir carboxylate (OC), amantadine (AMN), and zanamivir (ZAN)-in the urban area of the Yodo River system. This area includes three main river catchments (the Katsura, Uji, and Kidzu Rivers) and is home to 12 million people, about 10% of Japan's population. Water was sampled at six main rivers and 13 tributary sites and eight sewage treatment plants (STPs). We concluded that the STP effluents were the major sources of the anti-influenza drug load in the Yodo River system (68-94% of total mass fluxes). Extended measurement throughout the Yodo River system further showed only small fluctuations of the ratio of OS to OC from 0.2 to 0.3, suggesting that OS and its metabolite are environmentally stable. The results also clearly showed the importance of reducing the levels of anti-influenza drugs in the water environment by reducing their emission at STPs.

Lorazepam photofate under photolysis and TiO2-assisted photocatalysis: identification and evolution profiles of by-products formed during phototreatment of a WWTP effluent

This manuscript reports on the study of Lorazepam (LZP) phototransformation pathways under artificial UV and natural solar irradiation, through photolytic and TiO2-assisted photocatalytic processes. Three experimental set-ups were employed: two lab-scale photoreactors, each provided with an UV lamp (one medium pressure mercury lamp and one blacklight blue lamp), and a pilot-scale Solar Plant with Compound Parabolic Collectors (CPCs). Samples collected along the different phototreatment experiments were analyzed by ultra-high performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry (UHPLC/QqToF-MS). The key assumption of the analytical approach was that related compounds (LZP and its by-products (LBPs)) provide identical "diagnostic fragment ions". Identification was also based on the chlorine atoms specific isotopic pattern, as well as accurate masses. Six major LBPs were identified and elucidated, with nominal [M + H](+) masses of 337, 303, 319, 275, 291 and 293 Da. The proposed LZP photodegradation mechanism included the initial opening of the diazepinone seven-membered ring, followed by a rearrangement into a highly stabilized six-membered aromatic ring and subsequent cleavage and/or hydroxylation reactions. The evolution profiles of LBPs were described for each of the three experimental prototypes and the CPCs Solar Pilot Plant proved to be the most efficient one. Finally, LZP photocatalytic degradation was further assessed on a municipal effluent, where the photoproducts generated showed to be more persistent than LZP itself.

Application of electrolysis for inactivation of an antiviral drug that is one of possible selection pressure to drug-resistant influenza viruses

The recent development of antiviral drugs has led to concern that the release of the chemicals in surface water due to expanded medical use could induce drug-resistant mutant viruses in zoonosis. Many researchers have noted that the appearance of an oseltamivir (Tamiflu(®))-resistant avian influenza mutant virus, which may spread to humans, could be induced by oseltamivir contamination of surface water. Although past studies have reported electrolysis as a possible method for degradation of antineoplastics and antibacterials in water, the validity of the method for treatment of antiviral drugs is unknown. In this study, electrolysis was used to degrade an antiviral prodrug, oseltamivir, and a stable active form, oseltamivir carboxylate, and the degradation process was monitored with HPLC-UV and the neuraminidase inhibitory assay. HPLC-UV-detectable oseltamivir and oseltamivir carboxylate were decomposed by electrolysis within 60 min, and inhibitory activity of neuraminidase decreased below the detection limit of the assay used. Cytotoxic and genotoxic activity were not detected in electrolyzed fluid. These results indicate that electrolysis is a possible treatment for inactivation of the antiviral drug oseltamivir.

Determination of testosterone and its photodegradation products in surface waters using solid-phase extraction followed by LC-MS/MS analysis

The formation of several by-products from the photodegradation of testosterone was previously observed under laboratory conditions. The objectives of the manuscript were to complete the identification of testosterone's photoproducts and to develop an analytical method for the detection of testosterone as well as its three main photoproducts in natural sunlit surface waters. To accomplish these tasks, an efficient extraction method was developed based on solid-phase extraction, followed by the use of liquid chromatography coupled to tandem mass spectrometry, a selective and sensitive detection method. This analytical procedure has the capability of detecting target analytes in the ng/L range, with recoveries above 80 %. The methodology was successfully applied to the analysis of testosterone and its photoproducts in several surface waters.

Synchronous dynamics of observed and predicted values of anti-influenza drugs in environmental waters during a seasonal influenza outbreak

Time-dependent dynamics in the concentrations of four anti-influenza drugs (oseltamivir, oseltamivir carboxylate, zanamivir, and amantadine) in environmental waters collected from the Yodo River basin, Japan, were monitored for the first time over a 1 year period (July 2010 to June 2011). The clear, convex dynamic profiles of oseltamivir, oseltamivir carboxylate, and zanamivir during a 3 month seasonal influenza outbreak (January to March 2011) were synchronized well with that of the numbers of influenza patients treated with the drugs. The highest levels in sewage treatment plants (STPs) and river waters were, respectively, 177 and 60 ng/L (oseltamivir), 827 and 288 ng/L (oseltamivir carboxylate), and 30 and 15 ng/L (zanamivir). Fixed levels of amantadine were detectable year-round (100-200 ng/L in the STPs and 10-30 ng/L in river waters). The predicted convex profiles of oseltamivir, oseltamivir carboxylate, and zanamivir in both STPs and river waters were significantly correlated (0.714 < R < 0.932) with the observed values. The profiles were predicted successfully by simple mathematical principles, taking the number of influenza patients, quantities of Tamiflu and Relenza used, dilution by drainwaters passing through STPs, removal rates at STPs, dilution rates in river effluents, and attenuation rates in rivers into consideration.

Occurrence and modeling of pharmaceuticals on a sewage-impacted Mediterranean river and their dynamics under different hydrological conditions

The occurrence of 73 representative pharmacologically active compounds (PhACs) was assessed in a sewage-impacted section of the Llobregat River (NE Catalonia, Spain). This Mediterranean river is characterized by flow rate fluctuations strongly influenced by seasonal rainfall. River flow variations increase the potential environmental risk posed by organic micro-pollutants as their concentrations may increase substantially under low flow conditions. Little is known about the transport behavior of emerging contaminants in surface waters once they are discharged from waste water treatment plants (WWTP) into rivers. This research aimed to study the presence and fate of emerging contaminants under different hydrological conditions by sampling two different sites along the river in different seasons. The highest levels of pharmaceuticals were determined during cold and dry periods. The impact of the flow changes on the concentration of the pharmaceuticals in the river was assessed with the relative sensitive coefficients. Due to expected dilution effects, the response of pharmaceuticals to river flow was negative. Only in a few cases, positive relationships between drug concentrations and flow were detected, suggesting an important role of other hydrological phenomena like sediment re-suspension as well as the source of pollutants. To evaluate the role of other factors influencing PhAC concentrations, a plug-flow model was applied to obtain disappearance constants "k" for a set of selected compounds. Erythromycin presented k values of -0.15 h(-1) in both sites being the compound more efficiently removed from the water column. The k values for ibuprofen, furosemide, enrofloxacin, enalapril, acetaminophen, diclofenac and Ketoprofen were between -0.04 and -0.10 h(-1) showing less disappearance than erythromycin in the water column. However, other compounds presented k values<0.06, which suggested conservative behavior of these compounds in the water column. This study supports the reliability of the calculated k values for the disappearance of compounds in river waters.

Removal of the antiviral agent oseltamivir and its biological activity by oxidative processes

The antiviral agent oseltamivir acid (OA, the active metabolite of Tamiflu(®)) may occur at high concentrations in wastewater during pandemic influenza events. To eliminate OA and its antiviral activity from wastewater, ozonation and advanced oxidation processes were investigated. For circumneutral pH, kinetic measurements yielded second-order rate constants of 1.7 ± 0.1 × 10(5) and 4.7 ± 0.2 × 10(9) M(-1) s(-1) for the reaction of OA with ozone and hydroxyl radical, respectively. During the degradation of OA by both oxidants, the antiviral activity of the treated aqueous solutions was measured by inhibition of neuraminidase activity of two different viral strains. A transient, moderate (two-fold) increase in antiviral activity was observed in solutions treated up to a level of 50% OA transformation, while for higher degrees of transformation the activity corresponded to that caused exclusively by OA. OA was efficiently removed by ozonation in a wastewater treatment plant effluent, suggesting that ozonation can be applied to remove OA from wastewater.

Environmental release of oseltamivir from a Norwegian sewage treatment plant during the 2009 influenza A (H1N1) pandemic

During the 2009 influenza type A(H1N1) pandemic, the antiviral drug oseltamivir (OP, Tamiflu®) was extensively used for treatment and prophylaxis after recommendation from World Health Organisation (WHO). Previous studies have indicated that the pharmaceutically active metabolite of OP, oseltamivir carboxylate (OC), is not readily degraded in sewage treatment plants (STPs) and therefore will be released into receiving waters in elevated concentrations during a pandemic outbreak of influenza. A method for analyzing OP and OC in wastewater by UPLC-TOF has been developed and validated. This analytical method has been used to study the release of OP and OC from a sewage treatment plant outside Oslo, Norway during the 2009 pandemic. Daily flow-proportional influent and effluent samples from 11 weeks covering the main wave of the influenza pandemic were analyzed, and the observed trend in OP and OC concentrations closely followed the trend in percentage of medical consultations caused by influenza-like illness. Concentrations in wastewater influent were in the range of 5-529 ng/L and 28-1213 ng/L for OP and OC, respectively. Concentration data from the 54 influent/effluent sample sets suggest STP removal in the range of -0.8% to 8% for OP and -14% to 0.6% for OC. Statistical analysis of the data sets was inconclusive in determining a removal rate different from 0.