Selective uptake and biological consequences of environmentally relevant antidepressant pharmaceutical exposures on male fathead minnows

Transcriptomic Point of Departure (tPOD) of androstenedione in zebrafish embryos as a potential surrogate for chronic endpoints

The transcriptomic Point of Departure (tPOD) is increasingly used in ecotoxicology to derive quantitative endpoints from RNA sequencing studies. Utilizing transcriptomic data in zebrafish embryos as a New Approach Methodology (NAM) is beneficial due to its acknowledgment as an alternative to animal testing under EU Directive 2010/63/EU. Transcriptomic profiles are available in zebrafish for various modes of action (MoA). The limited literature available suggest that tPOD values from Fish Embryo Toxicity (FET) tests align with, but are generally lower than, No Observed Effect Concentrations (NOEC) from long-term chronic fish toxicity tests. In studies with the androgenic hormone androstenedione in a Fish Sexual Development Test (FSDT), a significant shift in the sex ratio towards males was noted at all test concentrations, making it impossible to determine a NOEC (NOEC <4.34 μg/L). To avoid additional animal testing in a repetition of the FSDT and adhere to the 3Rs principle (replacement, reduction, and refinement), a modified zebrafish FET (zFET) was conducted aiming to determine a regulatory acceptable effect threshold. This involved lower concentration ranges (20 to 6105 ng/L), overlapping with the masculinization-observed concentrations in the FSDT. The tPOD analysis in zFET showed consistent results with previous FSDT findings, observing strong expression changes in androgen-dependent genes at higher concentrations but not at lower ones, demonstrating a concentration-response relationship. The tPOD values for androstenedione were determined as 24 ng/L (10th percentile), 60 ng/L (20th gene), and 69 ng/L (1st peak). The 10th percentile tPOD value in zFET was 200 times lower than the lowest concentration in the FSDT. Comparing the tPOD values to literature suggests their potential to inform on the NOEC range in FSDT tests.

Comprehensive monitoring and prioritizing for contaminants of emerging concern in the Upper Yangtze River, China: An integrated approach

Contaminants of emerging concern (CECs) in aquatic environments can adversely impact ecosystems and human health even at low concentrations. This study assessed the risk of 162 CECs, including neonicotinoid pesticides, triazine pesticides, carbamate pesticides, psychoactive substances, organophosphate esters, antidepressants, per- and polyfluoroalkyl substances, and antibiotics in 10 drinking water sources and two tributaries (Jialing and Wujiang Rivers) of the Upper Yangtze River in Chongqing, China. Target screening detected 156 CECs at 0.01-2218.2 ng/L, while suspect screening via LC-QTOF-MS identified 64 CECs, with 13 pesticides, 29 pharmaceuticals and personal care products, and 2 industrial chemicals reported for the first time in the Yangtze River Basin. Risk quotient-based ecological risk assessment revealed that 48 CECs posed medium to high risks (RQ > 0.1) to aquatic life, with antibiotics (n = 20) as the main contributors. Non-carcinogenic risks were below negligible levels, but carcinogenic risks from neonicotinoids, triazines, antidepressants, and antibiotics were concerning. A multi-criteria prioritization approach integrating occurrence, physico-chemical properties, and toxicological data ranked 26 CECs as high priority. This study underscores the importance of comprehensive CEC screening in rivers and provides insights for future monitoring and management strategies.

Antidepressants - The new endocrine disruptors? The case of crustaceans

Antidepressants are high-volume pharmaceuticals that accumulate to concentrations in the μg·L-1 range in surface waters. The release of peptide hormones via neurosecretory cells appears as a natural target for antidepressants. Here I review research that suggests that antidepressants indeed disrupt endocrine signalling in crustaceans, by acting on the synthesis and release of neurohormones, such as crustacean hyperglycaemic hormone, moult inhibiting hormone and pigment dispersing hormone in decapods, as well as methyl farnesoate in Daphnids. Hence, antidepressants can affect hormonal regulation of physiological functions: increase in energy metabolism and activity, lowered ecdysteroid levels, potentially disrupting moult and somatic growth, reducing colour change capacity and compromising camouflage, as well as induction of male sex determination. Several studies further suggest effects of antidepressants on crustacean reproduction, but the hormonal regulation of these effects remains elusive. All things considered, a body of evidence strongly suggests that antidepressants are endocrine disrupting compounds in crustaceans.

Control list of high-priority chemicals based on 5-HT-RI functionality and the human health interference effects selective CNN-GRU deep learning model

The antidepressant drug known as 5-HT reuptake inhibitor (5-HT-RI) was commonly detected in biological tissues and result in significant adverse health effects. Homology modeling was used to characterize the functionalities (efficacy and resistance), and the adverse outcome pathway was used to characterize its human health interferences (olfactory toxicity, neurotoxicity, and gut microbial interference). The convolutional neural network coupled with the gated recurrent unit (CNN-GRU) deep learning method was used to construct a comprehensive model of 5-HT-RI functionality and human health interference effects selectivity with small sample data. The architecture with 2 SE, 320 neuronal nodes and 6-folds cross-validation showed the best applicability. The results showed that the confidence interval of the constructed model reached 90 % indicating that the model had reliable prediction ability and generalization ability. Based on the CNN-GRU deep learning model, seven high-priority chemicals with a weak comprehensive effect, including D-VEN, (1R,4S)-SER, S-FLX, CTP, S-CTP, NEF, and VEN, were screened. Based on the molecular three-dimensional structure information, a comprehensive-effect three-dimensional quantitative structure-activity relationship (3D-QSAR) model was constructed to confirm the reliability of the constructed control list of 5-HT-RI high-priority chemicals. Analysis with the ranking of calculated values based on the molecular dynamics method and predicted values based on the CNN-GRU deep learning model, we found that the consistency of the three methods was above 85 %. Additionally, by analyzing the sensitivity, molecular electrostatic potential, polar surface area of the comprehensive-effect CNN-GRU deep learning model, and the electrostatic field of the 3D-QSAR models, we found that the significant effects of five key characteristics (DM, Qyy, Qxz, I, and BP), molecular electronegativity, and polarity significantly affected the high-priority degree of 5-HT-RI. In this study, we provided reasonable and reliable prediction tools and discussed theoretical methods for the risk assessment of functionality and human health interference of emerging pollutants such as 5-HT-RI.

The occurrence of typical psychotropic drugs in the aquatic environments and their potential toxicity to aquatic organisms - A review

Psychotropic drugs (PDs) and their bioactive metabolites often persist in aquatic environments due to their typical physical properties, which made them resistant to removal by traditional wastewater treatment plants (WWTPs). Consequently, such drugs and/or their metabolites are frequently detected in both aquatic environments and organisms. Even at low concentrations, these drugs can exhibit toxic effects on non-target organisms including bony fish (zebrafish (Danio rerio) and fathead minnows) and bivalves (freshwater mussels and clams). This narrative review focuses on the quintessential representatives of three different categories of PDs-antiepileptics, antidepressants, and antipsychotics. The data regarding their concentrations occurring in the environment, patterns of distribution, the degree of enrichment in various tissues of aquatic organisms, and the toxicological effects on them are summarized. The toxicological assessments of these drugs included the evaluation of their effects on the reproductive, embryonic development, oxidative stress-related, neurobehavioral, and genetic functions in various experimental models. However, the mechanisms underlying the toxicity of PDs to aquatic organisms and their potential health risks to humans remain unclear. Most studies have focused on the effects caused by acute short-term exposure due to limitations in the experimental conditions, thus making it necessary to investigate the chronic toxic effects at concentrations that are in coherence with those occurring in the environment. Additionally, this review aims to raise awareness and stimulate further research efforts by highlighting the gaps in the understanding of the mechanisms behind PD-induced toxicity and potential health risks. Ultimately, the study underscores the importance of developing advanced remediation methods for the removal of PDs in WWTPs and encourages a broader discussion on mitigating their environmental impacts.

Aggression repeatability in stressed fish in response to an environmental concentration of sertraline and lunar cycle as evidenced by brain metabolomics

Sertraline is an environmental pollutant which received magnified scientific attention due to its global presence in waters. Adverse effects on feeding, reproduction and other traits were observed mostly in unstressed aquatic organisms. Chronic stress, however, induces significant physiological changes, and the effects of sertraline in stressed fish may differ from those observed in non-stressed individuals. The current laboratory study addresses this gap by repeatedly monitoring the individual aggression of chronically stressed juvenile chub (Squalius cephalus L.) using the non-reversing mirror test at an environmental sertraline concentration of 0.022 g/L every three to four days for a period of 39 days. Specifically, it was hypothesized that the level and repeatability of aggressiveness would be (i) correlated with the concentration of sertraline/norsertraline in the fish brain; (ii) linked to the individual brain metabolomic profile described by LC-HRMS analyses; (iii) related to the lunar cycle. Sertraline led to an increase in fish aggression and more repeatable/consistent behaviour compared to control fish. While the level of sertraline in the brain did not correlate with aggressiveness, aggressive responses increased with higher norsertraline concentration. The observed aggressive behaviour also varied depending on the individual metabolomic profile of the brain. The behavioural outcome and metabolic change in fish brain may indicate that sertraline has demonstrated neuroprotective effects by reducing cortisol release. It is possible that fish exposed to sertraline could suffer a blunted stress response under the chronic stressors in the wild. Aggressiveness of both treatments evolved in time, revealing a sinusoid-like pattern corresponding to a lunar cycle with a peak of the aggressiveness during the new moon. There is a need for future studies to focus on this relationship to reveal its details and general validity. Our results emphasize that long-term behavioural variability should generally be taken into account in laboratory behavioural studies.

Tracking drugged waters from various sources to drinking water-its persistence, environmental risk assessment, and removal techniques

Pharmaceuticals have become a major concern due to their nature of persistence and accumulation in the environment. Very few studies have been performed relating to its toxicity and ill effects on the aquatic/terrestrial flora and fauna. The typical wastewater and water treatment processes are not efficient enough to get these persistent pollutants treated, and there are hardly any guidelines followed. Most of them do not get fully metabolized and end up in rivers through human excreta and household discharge. Various methods have been adopted with the advancement in technology, sustainable methods are more in demand as they are usually cost-effective, and hardly any toxic by-products are produced. This paper aims to illustrate the concerns related to pharmaceutical contaminants in water, commonly found drugs in the various rivers and their existing guidelines, ill effects of highly detected pharmaceuticals on aquatic flora and fauna, and its removal and remediation techniques putting more emphasis on sustainable processes.

Cost-Effective Pharmaceutical Implants in Fish: Validating the Performance of Slow-Release Implants for the Antidepressant Fluoxetine

Internal, slow-release implants can be an effective way to manipulate animal physiology or deliver a chemical exposure over long periods of time without the need for an exogenous exposure route. Slow-release implants involve dissolving a compound in a lipid-based carrier, which is inserted into the body of an organism. However, the release kinetics of the compound from the implant to body tissues also requires careful validation. We tested and validated a slow-release implant methodology for exposing fish to a pharmaceutical pollutant, fluoxetine. We tested two lipid-based carriers (coconut oil or vegetable shortening) in the common roach (Rutilus rutilus). The implants contained either a high (50 μg/g), low (25 μg/g), or control (0 μg/g) concentration of fluoxetine, and we measured tissue uptake in the brain, muscle, and plasma of implanted fish over 25 days. The two carriers released fluoxetine differently over time: coconut oil released fluoxetine in an accelerating manner (tissue uptake displayed a positive quadratic curvature), whereas vegetable shortening released fluoxetine in a decelerating manner (a negative quadratic curvature). For both carrier types, fluoxetine was measured at the highest concentration in the brain, followed by muscle and plasma. By comparing the implant exposures with waterborne exposures in the published literature, we showed that the implants delivered an internal exposure that would be similar if fish were exposed in surface waters containing effluents. Overall, we showed that slow-release internal implants are an effective method for delivering chronic exposures of fluoxetine over at least 1-month time scales. Internal exposures can be an especially powerful experimental tool when coupled with field-based study designs to assess the impacts of pharmaceutical pollutants in complex natural environments. Environ Toxicol Chem 2023;42:1326-1336. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Effect of psychoactive substances on cardiac and locomotory activity of juvenile marbled crayfish Procambarus virginalis

Pharmaceutically active compounds are common and increasing in the aquatic environment. Evidence suggests they have adverse effects on non-target organisms, and they are classified as emerging pollutants for a variety of aquatic organisms. To determine the effects of environmentally relevant levels of psychoactive compounds on non-target organisms, we analyzed cardiac and locomotory activity in early developmental stages of marbled crayfish Procambarus virginalis. Responses to sertraline, methamphetamine, and a mixture of citalopram, oxazepam, sertraline, tramadol, venlafaxine, and methamphetamine at a concentration of 1 µg L^-1 of each compound were assessed. On day four of exposure, cardiac activity was recorded for 5 min, and on day eight, locomotory activity was recorded for 15 min. There was a significant increase (p < 0.01) in heart rate in methamphetamine-exposed and Mix-exposed juveniles compared to the unexposed control and there was significant difference (p < 0.01) in proportion of time (activity %) was observed with sertraline-exposed, whereas velocity, and distance moved did not significantly differ (p > 0.05) in exposed and control animals. These findings revealed that low concentrations of chemicals and their mixtures can modify the physiological state of aquatic animals without outward manifestations (activity, distance moved, and velocity). Aquatic animals can be impacted earlier than is visible, but effects can potentially lead to substantial changes in populations and in ecosystem processes. Additional research to investigate chemical combinations, exposure systems, and organism physiological and molecular responses may provide evidence of broad impact of environmental pharmaceuticals.

Antidepressant pharmaceuticals in aquatic systems, individual-level ecotoxicological effects: growth, survival and behavior

The growing consumption of antidepressant pharmaceuticals has resulted in their widespread occurrence in the environment, particularly in waterways with a typical concentration range from ng L^-1 to μg L^-1. An increasing number of studies have confirmed the ecotoxic potency of antidepressants, not only at high concentrations but also at environmentally relevant levels. The present review covers literature from the last decade on the individual-level ecotoxicological effects of the most commonly used antidepressants, including their impact on behavior, growth, and survival. We focus on the relationship between antidepressants physico-chemical properties and dynamics in the environment. Furthermore, we discuss the advantages of considering behavioral changes as sensitive endpoints in ecotoxicology, as well as some current methodological shortcomings in the field, including low standardization, reproducibility and context-dependency.

Biological-Activity-Based Prioritization of Antidepressants in Wastewater in England and Japan

Antidepressants are one of the most commonly prescribed pharmaceuticals. Although they have been frequently detected in aquatic environments around the globe, little is known regarding their adverse effects on humans and aquatic organisms. Recently, an in vitro monoamine transporter inhibition assay was developed to detect transporter-inhibitory activities of antidepressants in wastewater in Japan. However, it was unclear which antidepressants were responsible for transporter-inhibitory activities in wastewater. Herein, the per capita consumption of 32 antidepressants, their excretion of unchanged parent compounds, per capita water consumption, removal rate during wastewater treatment processes, and potency values from the monoamine transporter inhibition assay were used to prioritize antidepressants of concern in effluent wastewater in England and Japan. In both countries, sertraline and O-desmethylvenlafaxine had the highest contribution to inhibitory activities against the human serotonin transporter (hSERT) and zebrafish SERT (zSERT), respectively. It was found that the antidepressants inhibited the zSERT more strongly than the hSERT. The inhibitory activities found against the zSERT in wastewater in England and Japan were higher than thresholds for abnormal behavior in fish. The antidepressants prioritized in this study provide insight into launching environmental monitoring and ecotoxicological studies of antidepressants.

Bioaccumulation as a method of removing psychoactive compounds from wastewater using aquatic plants

Since WWTPs are not able to eliminate all psychoactive pharmaceuticals, these compounds become a part of the aquatic ecosystem. Our results indicate that compounds such as codeine or citalopram are eliminated with low efficiency (<38%), and compounds such as venlafaxine, oxazepam, or tramadol even with almost no efficiency. Lower elimination efficiency may be caused by the accumulation of these compounds in the wastewater treatment process. This study is focused on the possibility to remove problematic psychoactive compounds using aquatic plants. HPLC-MS analysis of the leaf extract obtained from studied plants showed that the amount of accumulated methamphetamine was highest in Pistia stratiotes and lower in the leaves of Limnophila sessiliflora and Cabomba caroliniana. However, tramadol and venlafaxine were accumulated considerably only in Cabomba caroliniana. Our study demonstrates that especially these three compounds - tramadol, venlafaxine, and methamphetamine, are accumulated in aquatic plants and can be removed from the aquatic environment. In our study was also observed that helophytic aquatic plants show a higher ability to remove psychoactive compounds from wastewater. Iris pseudacorus showed the best results in selected pharmaceuticals removal with no bioaccumulation effect in leaves or roots.

Interactive effects of venlafaxine and thermal stress on zebrafish (Danio rerio) inflammatory and heat shock responses

Venlafaxine (VFX), a commonly prescribed antidepressant often detected in wastewater effluent, and acute temperature elevations from climate change and increased urbanization, are two environmental stressors currently placing freshwater ecosystems at risk. This study focused on understanding if exposure to VFX impacts the agitation temperature (T_ag) and critical thermal maximum (CT_max) of zebrafish (Danio rerio). Additionally, we examined the interactive effects of VFX and acute thermal stress on zebrafish heat shock and inflammatory immune responses. A 96 h 1.0 μg/L VFX exposure experiment was conducted, followed by assessment of thermal tolerance via CT_max challenge. Heat shock proteins and pro-inflammatory immune cytokines were quantified through gene expression analysis by quantitative PCR (qPCR) on hsp 70, hsp 90, hsp 47, il-8, tnfα, and il-1β within gill and liver tissue. No significant changes in agitation temperature between control and exposed fish were observed, nor were there any differences in CT_max based on treatment. Unsurprisingly, hsp 47, 70, and 90 were all upregulated in groups exposed solely to CT_max, while only hsp 47 within gill tissue showed signs of interactive effects, which was significantly decreased in fish exposed to both VFX and CT_max. No induction of an inflammatory response occurred. This study demonstrated that environmentally relevant concentrations of VFX have no impact on thermal tolerance performance in zebrafish. However, VFX can cause diminished function of protective heat shock mechanisms, which could be detrimental to freshwater fish populations and aquatic ecosystems as temperature spikes become more frequent from climate change and urbanization near watersheds.

In-situ multi-mode extraction (iMME) sampler for a wide-scope analysis of chemical and biological targets in water in urbanized and remote (off-the-grid) locations

Chemical pollution (including chemicals of emerging concern - CECs) continues to gain increasing attention as a global threat to human health and the environment, with numerous reports on the adverse and sometimes devastating effects upon ecosystems the presence of these chemicals can have. Whilst many studies have investigated presence of CECs in aquatic environments, these studies have been often focused on higher income countries, leaving significant knowledge gaps for many low-middle income countries. This study proposes a new integrated powerless, in-situ multi-mode extraction (iMME) sampler for the analysis of chemicals (105 CECs) and biological (5 genes) markers in water in contrasting settings: an urbanized Avon River in the UK and remote Olifants River in Kruger National Park in South Africa. The overarching goal was to develop a sampling device that maintains integrity of a diverse range of analytes via analyte immobilization using polymeric and glass fibre materials, without access to power supply or cold chain (continuous chilled storage) for sample transportation. Chemical analysis was achieved using ultra-performance liquid chromatography coupled with tandem mass spectrometry. Several mobile CECs showed low stability in river water, at room temperature and typical 24 h sampling/transport time. It is therefore recommended that, in the absence of cooling, environmental water samples are spiked with internal standards on site, immediately after collection and analyte immobilization option is considered, in order to allow fully quantitative analysis. iMME has proven effective in immobilization, concentration and increased stability of CECs at room temperature (and at least 7 days storage) allowing for sample collection at remote locations. The results from the River Avon and Olifants River sampling indicate that the pristine environment of Olifants catchment is largely unaffected by CECs common in the urbanized River Avon in the UK with a few exceptions: lifestyle chemicals (e.g., caffeine, nicotine and their metabolites), paracetamol and UV filters due to tourism and carbamazepine due to its persistent nature. iMME equipped with an additional gene extraction capability provides an exciting new opportunity of comprehensive biochemical profiling of aqueous samples with one powerless in-situ device. Further work is required to provide full integration of the device and comprehensive assessment of performance in both chemical and biological targets.

Acute and chronic ecotoxicological effects of pharmaceuticals and their mixtures in Daphnia similis

Pharmaceuticals have increasingly received attention from the scientific community due to their growing intake, improved detection and potential ecological risks. Several pharmaceuticals, including antidepressants, anti-inflammatory and antidiabetic compounds and antibiotics, have been described as contaminants in different water matrices. In this context, the aim of the present study was to assess the acute and chronic effects of four classes of pharmaceuticals (acetylsalicylic acid, fluoxetine, metformin and ciprofloxacin) individually and in binary and quartenary mixture. Furthermore, the toxicity of binary mixtures containing the antidepressant fluoxetine was also evaluated. The results of the single acute and chronic toxicity assays indicate lower acetylsalicylic acid and higher fluoxetine toxicity towards Daphnia similis. Regarding the evaluated mixture toxicity, the nature of potential toxicological interactions was predicted by applying mathematical concentration addition and independent action models. The findings revealed both antagonistic and synergistic features, depending on the applied amounts and doses. Finally, the chronic assays performed with the quaternary mixture indicated the presence of a hormetic effect at low concentrations. In sum, the present study demonstrated that the effects of individual pharmaceuticals can underestimate the risk level of these contaminants in the environment.

Developmental exposure to sertraline impaired zebrafish behavioral and neurochemical profiles

The number of people suffering from mental health problems is rising, with anxiety and depression now the most commonly diagnosed psychiatric conditions. Selective serotonin reuptake inhibitors (SSRIs) are one of the most prescribed pharmaceuticals to treat these conditions, which has led to their common detection in many aquatic ecosystems. As the monoaminergic system shows a high degree of structural conservation across diverse animal phyla, a reasonable assumption is that the environmental levels of SSRIs in surface water can lead to adverse effects on fish and other aquatic wildlife. For instance, Sertraline (SER), a widely prescribed SSRI, has been shown to induce adverse effects in fish, albeit most of the reports used exposure concentrations exceeding those occurring in natural environments. Therefore, there is still a great lack of knowledge regarding SERs effects in fish species, especially during early life stages. This study describes the evaluation of developmental exposure of zebrafish (Danio rerio) to environmentally relevant concentrations of SER (from 0.01 to 10 μg/L), using a battery of key survival behaviors and further relating them with the expression of genes and neurochemical profiles of the monoaminergic system. We found that developmental exposure to SER did not affect embryo morphogenesis and growth. However, concentrations as low as 0.1 μg/L induced hypolocomotion and delayed learning. The observed behavioral impairment was associated with augmented serotonin levels rather than other neurochemicals and molecular markers, highlighting the relationship between serotonin signaling and behavior in zebrafish.

Anaerobic membrane bioreactors for pharmaceutical-laden wastewater treatment: A critical review

Pharmaceuticalsare a diverse group of chemical compounds widely used for prevention and treatment of infectious diseases in both humans and animals. Pharmaceuticals, either in their original or metabolite form, find way into the wastewater treatment plants (WWTPs) from different sources. Recently, anaerobic membrane bioreactors (AnMBR) has received significant research attention for the treatment of pharmaceuticals in various wastewater streams. This review critically examines the behaviour and removal of a wide array of pharmaceuticals in AnMBR with primary focus on their removal efficiencies and mechanisms, critical influencing factors, and the microbial community structures. Subsequently, the inhibitory effects of pharmaceuticals on the performance of AnMBR and membrane fouling are critically discussed. Furthermore, the imperative role of membrane biofouling layer and its components in pharmaceuticals removal is highlighted. Finally, recent advancements in AnMBR configurations for membrane fouling control and enhanced pharmaceuticals removal are systemically discussed.

Transcriptome profiling reveals toxicity mechanisms following sertraline exposure in the brain of juvenile zebrafish (Danio rerio)

Sertraline (SER) is one of the most commonly detected antidepressants in the aquatic environment that can negatively affect aquatic organisms at low concentrations. Despite some knowledge on its acute toxicity to fish, the effects of chronic SER exposure remain poorly understood along with any underlying mechanisms of SER-induced toxicity. To address this knowledge gap, the effects of chronic exposure to three SER concentrations from low to high were investigated in zebrafish. Juvenile zebrafish were exposed to three concentrations of 1, 10, or 100 μg/L of SER for 28 d, after which indicators of oxidative stress and neurotoxicity in the brain were measured. Superoxide dismutase (SOD) activity was significantly enhanced by SER at 1 up to 100 μg/L, and catalase (CAT) activity was significantly induced by SER at 1 or 10 μg/L. The activity of acetylcholinesterase (AChE) was significantly induced by 10 and 100 μg/L of SER, and the serotonin (5-HT) level was significantly increased by all three concentrations of SER. To ascertain mechanisms of SER-induced toxicity, transcriptomics was conducted in the brain of zebrafish following 100 μg/L SER exposure. The molecular signaling pathways connected with circadian system and the immune system were significantly altered in the zebrafish brain. Based on transcriptomic data, the expression levels of six circadian clock genes were measured, and three genes were significantly altered in relative abundance in fish from all experimental treatments with SER, including cryptochrome circadian regulator 2 (cry2), period circadian clock 2 (per2), and period circadian clock 3 (per3). We hypothesize that the circadian system may be related to SER-induced neurotoxicity and oxidative stress in the central nervous system. This study reveals potential mechanisms and key events (i.e., oxidative stress and neurotoxicity) associated with SER-induced toxicity, and improves understanding of the molecular and biochemical pathways putatively perturbed by SER.

Low doses and lifecycle exposure of waterborne antidepressants in zebrafish model: A survey on sperm traits, reproductive behaviours, and transcriptome responses

Venlafaxine and citalopram have been commonly found in surface water and may disrupt fish reproduction, yet the long-term impact and the underlying mechanism are largely unknown. Here, zebrafish were exposed to 0.1-100 μg/L venlafaxine and citalopram for their entire life cycle from embryo to adult, respectively. After exposure for 180 days, the lowest observable effective concentration (LOEC) of venlafaxine and citalopram to significantly reduce the mean number of egg production in adults were 10 and 1 μg/L, respectively, whereas the fertilization rate displayed no significant changes. Further, we investigated the impacts of venlafaxine and citalopram in a reproductive context, including sperm quality and reproductive behaviour. In contrast, venlafaxine and citalopram exposure did not affect sperm quality but caused a reduction of reproductive behaviour (e.g., mating duration and mating interval) of adults exposed to 1-10 μg/L of the antidepressant. Transcriptomic profiling of the whole ovary revealed that lifecycle venlafaxine and citalopram exposure significantly affected the Na⁺/Cl^- dependent neurotransmitter transporters signaling. Moreover, immune system-mediated ovarian regeneration and creatine metabolism regulated energy metabolism were proposed as the novel mechanism in the observed effects. Taken together, our results highlight the risk of lifecycle venlafaxine and citalopram exposure to fish reproduction and provide novel perspectives for unveiling the mechanism of female reproductive dysfunction.

Comprehensive assessment of chemical residues in surface and wastewater using passive sampling, chemical, biological, and fish behavioral assays

Effluents from ten full-scale municipal wastewater treatment plants (WWTPs) that discharge into the Hudson River, surface waters, and wild-caught fish samples were analyzed using liquid chromatography with tandem mass spectrometry (LC/MS/MS) to examine the influence of wastewater discharge on the concentrations of contaminants of emerging concern (CECs) and their ecological impacts on fish. Analysis was based on targeted detection of 41 pharmaceuticals, and non-targeted analysis (suspect screening) of CECs. Biological effects of treated WWTP effluents were assessed using a larval zebrafish (Danio rerio) swimming behavior assay. Concentrations of residues in surface waters were determined in grab samples and polar organic chemical integrative samplers (POCIS). In addition, vitellogenin peptides, used as biomarkers of endocrine disruption, were quantified using LC/MS/MS in the wild-caught fish plasma samples. Overall, 94 chemical residues were identified, including 63 pharmaceuticals, 10 industrial chemicals, and 21 pesticides. Eight targeted pharmaceuticals were detected in 100% of effluent samples with median detections of: bupropion (194 ng/L), carbamazepine (91 ng/L), ciprofloxacin (190 ng/L), citalopram (172 ng/L), desvenlafaxine (667 ng/L), iopamidol (3790 ng/L), primidone (86 ng/L), and venlafaxine (231 ng/L). Over 30 chemical residues were detected in wild-caught fish tissues. Notably, zebrafish larvae exposed to chemical extracts of effluents from 9 of 10 WWTPs, in at least one season, were significantly hyperactive. Vitellogenin expression in male or immature fish occurred 2.8 times more frequently in fish collected from the Hudson River as compared to a reference site receiving no direct effluent input. Due to the low concentrations of pharmaceuticals detected in effluents, it is likely that chemicals other than pharmaceuticals measured are responsible for the behavioral changes observed. The combined use of POCIS and non-target analysis demonstrated significant increase in the chemical coverage for CEC detection, providing a better insight on the impacts of WWTP effluents and agricultural practices on surface water quality.

Modeling Risk Dynamics of Contaminants of Emerging Concern in a Temperate-region Wastewater Effluent-dominated Stream

Wastewater effluent-dominated streams are becoming increasingly common worldwide, including in temperate regions, with potential impacts on ecological systems and drinking water sources. We recently quantified the occurrence/ spatiotemporal dynamics of pharmaceutical mixtures in a representative temperate-region wastewater effluent-dominated stream (Muddy Creek, Iowa) under baseflow conditions and characterized relevant fate processes. Herein, we quantified the ecological risk quotients (RQs) of 19 effluent-derived contaminants of emerging concern (CECs; including: 14 pharmaceuticals, 2 industrial chemicals, and 3 neonicotinoid insecticides) and 1 run-off-derived compound (atrazine) in the stream under baseflow conditions, and estimated the probabilistic risks of effluent-derived CECs under all-flow conditions (i.e., including runoff events) using stochastic risk modeling. We determined that 11 out of 20 CECs pose medium-to-high risks to local ecological systems (i.e., algae, invertebrates, fish) based on literature-derived acute effects under measured baseflow conditions. Stochastic risk modeling indicated decreased, but still problematic, risk of effluent-derived CECs (i.e., RQ≥0.1) under all-flow conditions when runoff events were included. Dilution of effluent-derived chemicals from storm flows thus only minimally decreased risk to aquatic biota in the effluent-dominated stream. We also modeled in-stream transport. Thirteen out of 14 pharmaceuticals persisted along the stream reach (median attenuation rate constant k<0.1 h^-1) and entered the Iowa River at elevated concentrations. Predicted and measured concentrations in the drinking water treatment plant were below the human health benchmarks. This study demonstrates the application of probabilistic risk assessments for effluent-derived CECs in a representative effluent-dominated stream under variable flow conditions (when measurements are less practical) and provides an enhanced prediction tool transferable to other effluent-dominated systems.

Characterizing toxicity pathways of fluoxetine to predict adverse outcomes in adult fathead minnows (Pimephales promelas)

Current ecotoxicity testing programs are impeded as they predominantly rely on slow and expensive animal tests measuring adverse outcomes. Therefore, new approach methodologies (NAMs) increasingly involve short-term mechanistic assays that employ molecular endpoints to predict adverse outcomes of regulatory relevance. This study aimed to elucidate the application of NAMs in adult fathead minnows using fluoxetine (FLX) as a model compound. Fish were exposed to three FLX concentrations (measured: 2.42, 10.7, and 56.7 μgL^-1) and a control. After 96 h, molecular toxicity signatures were characterized using proteomics and transcriptomics analyses in livers and brains of a sub-set of fish. The remaining fish were sampled at 21 days and assessed for liver histopathology and morphometric measurements. Fecundity was monitored throughout the study. In the livers, 56.7 μgL^-1 FLX caused enrichment of PPAR signaling in the proteome and fatty acid-related pathways in the transcriptome, potential upstream responses that led to lipid-type vacuolation of hepatocytes, observed via histopathology. Upregulated genes in the brain suggested alterations in serotonin-related signaling processes and reproductive behaviour, which may explain the observed significant decrease in fecundity. While the relationships between molecular responses and adverse outcomes remain complex, this research provided important insights into the mechanistic toxicity of FLX.

Effects of aqueous fluoxetine exposure on gut microbiome of adult Pimephales promelas

The microbiome of the gut is vital for homeostasis of hosts with its ability to detoxify and activate toxicants, as well as signal to the immune and nervous systems. However, in the field of environmental toxicology, the gut microbiome has only recently been identified as a measurable indicator for exposure to environmental pollutants. Antidepressants found in effluents of wastewater treatment plants and surface waters have been shown to exhibit antibacterial-like properties in vitro, where some bacteria are known to express homologous proteins that bind antidepressants in vertebrates. Therefore, it has been hypothesized that exposure to antidepressant drugs might affect gut microbiota of aquatic organisms. In this study, the common antidepressant, fluoxetine, was investigated to determine whether it can modulate the gut microbiome of adult fathead minnows. A 28-day, sub-chronic, static renewal exposure was performed with nominal fluoxetine concentrations of 0.01, 10 or 100 μg/L. Using 16S rRNA amplicon sequencing, shifts among the gut-associated microbiota were observed in individuals exposed to the greatest concentration, with greater effects observed in females. These changes were associated with a decrease in relative proportions of commensal bacteria, which can be important for health of fish including bacteria essential for fatty acid oxidation, and an increase in relative proportions of pathogenic bacteria associated with inflammation. Results demonstrate, for the first time, how antidepressants found in some aquatic environments can influence gut microbiota of fishes.

A cross-species comparative approach to assessing multi- and transgenerational effects of endocrine disrupting chemicals

A wide range of chemicals have been identified as endocrine disrupting chemicals (EDCs) in vertebrate species. Most studies of EDCs have focused on exposure of both male and female adults to these chemicals; however, there is clear evidence that EDCs have dramatic effects when mature or developing gametes are exposed, and consequently are associated with in multigenerational and transgenerational effects. Several publications have reviewed such actions of EDCs in subgroups of species, e.g., fish or rodents. In this review, we take a holistic approach synthesizing knowledge of the effects of EDCs across vertebrate species, including fish, anurans, birds, and mammals, and discuss the potential mechanism(s) mediating such multi- and transgenerational effects. We also propose a series of recommendations aimed at moving the field forward in a structured and coherent manner.

Proximate causes and ultimate effects of common antidepressants, fluoxetine and venlafaxine, on fish behavior

Antidepressant (AD) drugs are widely prescribed for the treatment of psychiatric disorders, including depression and anxiety disorders. The continuous use of ADs causes significant quantities of these bioactive chemicals to enter the aquatic ecosystems mainly through wastewater effluent discharge. This may result in many aquatic organisms being inadvertently affected by these drugs. Fluoxetine (FLX) and venlafaxine (VEN) are currently among the most widely detected ADs in aquatic systems. A growing body of experimental evidence demonstrates that FLX and VEN have a substantial capacity to induce neurotoxicity and cause behavioral dysfunctions in a wide range of teleost species. At the same time, these studies often report seemingly contradictory results that are confounding in nature. Hence, we clearly require comprehensive reviews that attempt to find overarching patterns and establish possible causes for these variable results. This review aims to explore the current state of knowledge regarding the neurobehavioral effects of FLX and VEN on fishes. This study also discusses the potential mechanistic linkage between the neurotoxicity of ADs and behavioral dysfunction and identifies key knowledge gaps and areas for future research.

Effects of oxidative stress induced by environmental relevant concentrations of fluoxetine on the embryonic development on Danio rerio

Fluoxetine (FLX) is a psychoactive drug that acts as an antidepressant. FLX is one of the world's best-selling prescription antidepressants. FLX is widely used for the treatment of various psychiatric disorders. For these reasons, this drug may eventually end up in the aquatic environment via municipal, industrial, and hospital discharges. Even though the occurrence of FLX in aquatic environments has been reported as ubiquitous, the toxic effects that this drug may induce, especially at environmentally relevant concentrations, on essential biological processes of aquatic organisms require more attention. In the light of this information, this work aimed to investigate the influence that fluoxetine oxidative stress-induced got over the embryonic development of Danio rerio. For this purpose, D. rerio embryos (4 h post fertilization) were exposed to environmentally relevant concentrations (5, 10, 15, 20, 25, 30, 35, and 40 ng L^-1) of fluoxetine, until 96 h post fecundation. Along the exposure, survival, alterations to embryonic development, and teratogenic effects were evaluated using a stereomicroscope. Furthermore, oxidative stress biomarkers (superoxide dismutase, catalase, glutathione peroxidase, lipid peroxidation, hydroperoxide, and carbonyl content) were evaluated at 72 and 96 h post fecundation. LC₅₀, EC_50m, and teratogenic index were 30 ng L^-1, 16 ng L^-1, and 1.9, respectively. The main teratogenic effects induced by fluoxetine were pericardial edema, hatching retardation, spine alterations and craniofacial malformations. Concerning oxidative stress, our integrated biomarkers (IBR) analysis demonstrated that as the concentration increased, oxidative damage biomarkers got more influence over the embryos than antioxidant enzymes. Thus, fluoxetine induces an important oxidative stress response on the embryos of D. rerio. Collectively, our results allow us to concluded that FLX is a dangerous drug in the early life stages of D. rerio due to its high teratogenic potential and that FLX-oxidative stress induced may be involved in this toxic process.

Bioavailability of citalopram to Daphnia magna in the presence of suspended sediments with various properties

The influence of suspended sediment (SPS) properties on the biological effects of antidepressant citalopram (CIT) was investigated in our study. For CIT exposure alone, the feeding behavior, energy available, glutathione-S-transferase (GST) activity of D. magna were vitally induced at 10 μg/L. In the presence of SPS, significant dose-dependent reduction in the ingestion and filtration rates were observed with the increase of SPS concentration, while SPS organic content (f_oc) of 1% exhibited the most serious aggravation. The protein was the main contributor to detoxification and cellular protection under the stress of CIT and SPS. Obvious disturbance effects on the malonaldehyde content, catalase and GST activities were observed for SPS of 0.1 g/L, 60-90 μm and f_oc of 2%. Overall, the important role of SPS properties on the biological effects of CIT should be taken into consideration for the accurate risk assessment of pollutants.

Fluoxetine in the environment may interfere with the neurotransmission or endocrine systems of aquatic animals

Antidepressants are extensively used to treat the symptoms of depression in humans, and the environmentally discharged drugs potentially threaten aquatic organisms. In this study, the acute toxic effects of fluoxetine (FLX) were investigated in two aquatic organisms, the freshwater polyp (Hydra magnipapillata) and Javanese medaka (Oryzias javanicus). The median lethal concentration (LC₅₀) of FLX in H. magnipapillata was 3.678, 3.082, and 2.901 mg/L after 24, 48, and 72 h, respectively. Morphological observations of the FLX-exposed H. magnipapillata showed that 1.5 mg/L FLX induced the contraction of the tentacles and body column. The LC₅₀ of FLX in O. javanicus was 2.046, 1.936, 1.532, and 1.237 mg/L after 24, 48, 72, and 96 h, respectively. Observation of the behavior of the FLX-exposed fish showed that FLX reduced their swimming performance at a minimum concentration of 10 µg/L. The half-maximal effective concentration (EC₅₀) of FLX for swimming behavior in O. javanicus was 0.135, 0.108, and 0.011 mg/L after 12, 24, and 96 h, respectively. Transcriptomic analyses indicated that FLX affects various physiological and metabolic processes in both species. FLX exposure induced oxidative stress, reproductive deficiency, abnormal pattern formation, DNA damage, and neurotransmission disturbance in H. magnipapillata, whereas it adversely affected O. javanicus by inducing oxidative stress, DNA damage, endoplasmic reticulum stress, and mRNA instability. Neurotransmission-based behavioral changes and endocrine disruption were strongly suspected in the FLX-exposed fish. These results suggest that FLX affects the behavior and metabolic regulation of aquatic organisms.

Transcriptional analyses reveal different mechanism of toxicity for a chronic exposure to fluoxetine and venlafaxine on the brain of the marine fish Dicentrarchrus labrax

Selective serotonin reuptake inhibitor (SSRI) and serotonin norepinephrine reuptake inhibitor (SNRI) are prescribed for clinical depression and detected in aquatic ecosystems. The main aim of this study was to explore and evaluate transcriptional responses of neurotransmitter genes in the brain of a marine fish species, European seabass, and to analyze global brain transcriptomic changes by a RNA-seq technology (MACE, massive analysis of cDNA ends). The juveniles were exposed to two psychopharmaceuticals: (i) fluoxetine (FLX) at the concentration of 0.5 μg/L and 50 μg/L; (ii) venlafaxine (VENX) at the concentration of 0.01 μg/L and 1 μg/L. The exposures were performed for 21 days, followed by a 7-day recovery period to assess the reversibility of effects. Both psychopharmaceuticals affected differentially the neurotransmitter mRNA expression analyzed by RT-qPCR (serotonin receptors: 5-ht3a, 5-ht3b; dopamine receptors: d2, d3; neurotransmitter transporter: sert, vmat; degrading enzyme: mao). Transcriptomic analyses after 21 days of exposure revealed 689 and 632 significant different transcripts by FLX at 0.5 and 50 μg/L, respectively, and 432 and 1250 by VENX at 0.01 and 1 μg/L, respectively, and confirmed different mechanism of toxicity between both compounds. At environmental concentrations, more general pathways including energy metabolism were affected, while at the higher concentration effects on neurotransmitter pathways were observed (FLX: exocytosis and vesicle formation; VENX: small molecule catabolism regulating dopamine and tyrosine level). These results provided new insights into the chronic effects of psychopharmaceutical compounds on marine fish and suggest the need of a separate ecotoxicological risk analysis.

Effects of the anxiolytic benzodiazepine oxazepam on freshwater gastropod reproduction: a prospective study

Psychoactive drugs have emerged as contaminants over the last few decades. These drugs are frequently prescribed and poorly eliminated by wastewater treatment plants, and many are present at non-negligible concentrations in surface waters. Several studies have investigated the non-target organism toxicity of one such drug, oxazepam, a benzodiazepine anxiolytic frequently detected in rivers. However, very little is known about the impact of this drug on reproduction. We investigated the effects of environmentally relevant concentrations of oxazepam on Radix balthica, a freshwater gastropod widespread in Europe. We identified the reproductive organs of Radix balthica. We then exposed this gastropod to oxazepam for two months and assessed several reproductive parameters, from reproductive organ status to behavioral parameters. We found that adults exposed to 10 µg/L oxazepam display an increase in the density of spermatozoa, and that adults exposed to 0.8 µg/L oxazepam displayed a decrease in the number of eggs per egg mass over time. By contrast, oxazepam had no effect on shell length, the size of male reproductive organs or social interactions. Finally, a locomotor activity analysis showed the distance covered over time decreased in all conditions of exposure to oxazepam, potentially reflecting a disturbance of exploratory activity. These results shed light on the effects of oxazepam on the reproduction of a non-target freshwater mollusk.

Tandem field and laboratory approaches to quantify attenuation mechanisms of pharmaceutical and pharmaceutical transformation products in a wastewater effluent-dominated stream

Evolving complex mixtures of pharmaceuticals and transformation products in effluent-dominated streams pose potential impacts to aquatic species; thus, understanding the attenuation dynamics in the field and characterizing the prominent attenuation mechanisms of pharmaceuticals and their transformation products (TPs) is critical for hazard assessments. Herein, we determined the attenuation dynamics and the associated prominent mechanisms of pharmaceuticals and their corresponding TPs via a combined long-term field study and controlled laboratory experiments. For the field study, we quantified spatiotemporal exposure concentrations of five pharmaceuticals and six associated TPs in a small, temperate-region effluent-dominated stream during baseflow conditions where the wastewater plant was the main source of pharmaceuticals. We selected four sites (upstream, at, and two progressively downstream from effluent discharge) and collected water samples at 16 time points (64 samples in total, approximately twice monthly, depending on flows) for 1 year. Concurrently, we conducted photolysis, sorption, and biodegradation batch tests under controlled conditions to determine the major attenuation mechanisms. We observed 10-fold greater attenuation rates in the field compared to batch tests, demonstrating that connecting laboratory batch tests with field measurements to enhance predictive power is a critical need. Batch systems alone, often used for assessment, are useful for determining fate processes but poorly approximate in-stream attenuation kinetics. Sorption was the dominant attenuation process (t_1/2<7.7 d) for 5 of 11 compounds in the batch tests, while the other compounds (n = 6) persisted in the batch tests and along the 5.1 km stream reach. In-stream parent-to-product transformation was minimal. Differential attenuation contributed to the evolving pharmaceutical mixture and created changing exposure conditions with concomitant implications for aquatic and terrestrial biota. Tandem field and laboratory characterization can better inform modeling efforts for transport and risk assessments.

Diagnosing Down-the-Drain Disposal of Unused Pharmaceuticals at a River Catchment Level: Unrecognized Sources of Environmental Contamination That Require Nontechnological Solutions

Down-the-drain disposal of pharmaceuticals remains an overlooked and unrecognized source of environmental contamination that requires nontechnological "at-source" solutions. Monitoring of 31 pharmaceuticals over 7 days in five wastewater treatment plants (WWTPs) serving five cities in South-West UK revealed down-the-drain codisposal of six pharmaceuticals to three WWTPs (carbamazepine and propranolol in city A, sildenafil in city B, and diltiazem, capecitabine, and sertraline in city D), with a one-off record codisposal of estimated 253 pills = 40 g of carbamazepine and estimated 96 pills = 4 g of propranolol in city A accounting for their 10- and 3-fold respective increases in wastewater daily loads. Direct disposal of pharmaceuticals was found to affect the efficiency of wastewater treatment with much higher pharmaceutical removal (decrease in daily load) during "down-the-drain disposal" days. This is due to lack of conjugated glucuronide metabolites that are cleaved during "consumption-only" days, with the release of a parent pharmaceutical counterbalancing its removal. Higher removal of pharmaceuticals during down-the-drain disposal days reduced pharmaceutical loads reaching receiving environment, albeit with significant levels remaining. The estimated daily loads in receiving water downstream from a discharge point accounted for 13.8 ± 3.4 and 2.1 ± 0.2 g day^-1 of carbamazepine and propranolol, respectively, during consumption-only days and peaked at 20.9 g day^-1 (carbamazepine) and 4.6 g day^-1 (propranolol) during down-the-drain disposal days. Actions are needed to reduce down-the-drain disposal of pharmaceuticals. Our recent work indicated that down-the-drain disposal of pharmaceuticals doubled since the last study in 2005, which may be due to the lack of information and messaging that informs people to dispose of unused medicines at pharmacies. Media campaigns that inform the public of how to safely dispose of medicines are key to improving rates of return and reducing pharmaceutical waste in the environment. The environment is a key motivator for returning unused medicines to a pharmacy and so messaging should highlight environmental risks associated with improper disposal.

Antidepressants Modify Cryptic Behavior in Juvenile Cuttlefish at Environmentally Realistic Concentrations

Contamination of the marine environment by antidepressants may affect neurophysiological processes in nontarget organisms, such as the common cuttlefish, Sepia officinalis. The present study tested whether environmentally realistic concentrations of antidepressants, that is, fluoxetine alone (5 ng L^-1 ) or cumulated with venlafaxine (2.5 or 5 ng L^-1 ), affect camouflage in newly hatched cuttlefish. The results show that antidepressants improved uniform body patterns, whereas disruptive body patterns were not affected. Environ Toxicol Chem 2021;40:2571-2577. © 2021 SETAC.

Simple and effective removal of psychiatric pharmaceuticals from wastewater treatment plant effluents by magnetite red mud nanoparticles

Psychological disorders due to the COVID-19 pandemic have increased the consumption of psychiatric pharmaceuticals on a global scale in last year. These compounds reach wastewater treatment plants (WWTP) through sewerage system and are not sufficiently removed by using conventional treatment process. Psychiatric drugs released with WWTP effluent may cause possible risks to the receiving aquatic environment. Also, two antidepressants have been included in the "watch list" in 2020. Therefore, simple and relatively cost effective removal of psychiatric drugs from wastewaters becomes important. Magnetite red mud nanoparticles (RM-NPs) synthesized was applied for the removal of psychiatric drugs (fluoxetine, paroxetine, carbamazepine, diazepam, and lorazepam) in WWTP effluent first time in this study. The adsorption of carbamazepine as a model compound was fitted well with pseudo-second-order kinetic model. The Freundlich isotherm model better represented the sorption data than the Langmuir model. High adsorption capacity (90.5 mg/g) was reached at 30 min contact time at pH 6.5-7.0 at 25 °C. The adsorption rate was described by the pseudo second order model and its rate control mechanism was controlled by film diffusion. The magnetite RM-NPs were efficiently used for the removal of carbamazepine from real WWTP effluents. The adsorption capacity and the magnetic separability of the regenerated magnetite RM-NPs were unaffected five cycles. Due to its simple application, low cost and high adsorption capacity, magnetite RM-NPs can be recommended as a better adsorbent comparing to commercial adsorbents to remove psychiatric drugs from WWTP effluents.

Elucidating venlafaxine metabolism in the Mediterranean mussel (Mytilus galloprovincialis) through combined targeted and non-targeted approaches

Exposure of aquatic organisms to antidepressants is currently well documented, while little information is available on how wild organisms cope with exposure to these pharmaceutical products. Studies on antidepressant metabolism in exposed organisms could generate information on their detoxification pathways and pharmacokinetics. The goal of this study was to enhance knowledge on the metabolism of venlafaxine (VEN)-an antidepressant frequently found in aquatic ecosystems-in Mytilus galloprovincialis, a bivalve that is present worldwide. An original tissue extraction technique based on the cationic properties of VEN was developed for further analysis of VEN and its metabolites using targeted and non-targeted approaches. This extraction method was assessed in terms of recovery and matrix effects for VEN metabolites. Commercial analytical standards were applied to characterize metabolites found in mussels exposed to 10 μg/L VEN for 3 and 7 days. Targeted and non-targeted approaches using liquid chromatography (LC) combined with high-resolution mass spectrometry (HRMS) were implemented to screen for expected metabolites based on the literature on aquatic species, and for metabolites not previously documented. Four venlafaxine metabolites were identified, namely N-desmethylvenlafaxine and O-desmethylvenlafaxine, which were clearly identified using analytical standards, and two other metabolites revealed by non-target analysis. According to the signal intensity, hydroxy-venlafaxine (OH-VEN) was the predominant metabolite detected in mussels exposed for 3 and 7 days.

Traces of tramadol in water impact behaviour in a native European fish

Tramadol is a widely used analgesic with additional antidepressant and anxiolytic effects. This compound has been reported in continental waters reaching concentrations of µg/L as a consequence of its inefficient removal in sewage treatment plants and increasing use over time. In this study, European chubs (Squalius cephalus) were exposed to 1 µg/L of tramadol in water for 42 days with a subsequent 14 days of depuration. Our results revealed that chubs exposed to this analgesic underwent changes in their behaviour as compared to the control group. The behavioural outcome was also influenced by the individual concentration of tramadol in brain tissue. In particular, experimental fish presented anxiolytic-like effects, characterized by less bold and less social individuals. Exposed animals were less frequently out of the shelter and moved a shorter distance, indicating that they explored the new environment less during the boldness test. In the novel object recognition experiment, although they distinguished the new item, they examined it less and displayed a reduced activity. Shoal cohesion was disrupted as observed in an increased distance between individuals. After the depuration phase, this alteration remained whereas the boldness effect disappeared. Moreover, the degree of behavioural changes was correlated with the concentration of the substance in brain. According to our findings, chronic presence of tramadol in the environment can impact the fitness of exposed aquatic fauna by altering evolutionary crucial behaviours.

Molecular and behavioral responses of zebrafish embryos/larvae after sertraline exposure

Sertraline (SER) is one of the most frequently detected antidepressant drugs in aquatic environments. However, knowledge regarding SER-induced behavioral alterations in fish is insufficient, as well as the mechanisms underlying SER-induced toxicity. The present study aimed to determine behavioral and molecular responses in larval fish following SER exposure with a focus on its mode of action. Zebrafish embryos (~6 h-post-fertilization, hpf) were exposed to one of three concentrations of SER (1, 10, 100 μg/L) for 6 days, respectively. Evaluated parameters included development, behavior, transcripts related to serotonin signaling, serotonin levels, and acetylcholinesterase activity. Accelerated hatching of zebrafish embryos was observed for those fish exposed to 100 μg/L SER at 54 hpf. Locomotor activity (e.g. distance moved and mobile cumulative duration) was significantly reduced in larval zebrafish following exposure to 10 and 100 μg/L SER. Conversely, larval fish showed increased dark-avoidance after exposure to 1-100 μg/L SER. Of the measured transcripts related to serotonin signaling, only serotonin transporter (serta) and serotonin receptor 2c (5-ht2c) mRNA levels were increased in fish in response to 10 μg/L SER treatment. However, serotonin levels were unaltered in larvae exposed to SER. There were no differences among groups in acetylcholinesterase activity at any concentration tested. Taking together, the results evidenced that exposure to SER alters behavioral responses in early-staged zebrafish, which may be related to the abnormal expression of 5-ht2c. This study elucidates molecular responses to SER and characterizes targets that may be sensitive to antidepressant pharmaceuticals in larval fish.

Neuroactive drugs and other pharmaceuticals found in blood plasma of wild European fish

To gain a better understanding of which pharmaceuticals could pose a risk to fish, 94 pharmaceuticals representing 23 classes were analyzed in blood plasma from wild bream, chub, and roach captured at 18 sites in Germany, the Czech Republic and the UK, respectively. Based on read across from humans, we evaluated the risks of pharmacological effects occurring in the fish for each measured pharmaceutical. Twenty-three compounds were found in fish plasma, with the highest levels measured in chub from the Czech Republic. None of the German bream had detectable levels of pharmaceuticals, whereas roach from the Thames had mostly low concentrations. For two pharmaceuticals, four individual Czech fish had plasma concentrations higher than the concentrations reached in the blood of human patients taking the corresponding medication. For nine additional compounds, determined concentrations exceeded 10% of the corresponding human therapeutic plasma concentration in 12 fish. The majority of the pharmaceuticals where a clear risk for pharmacological effects was identified targets the central nervous system. These include e.g. flupentixol, haloperidol, and risperidone, all of which have the potential to affect fish behavior. In addition to identifying pharmaceuticals of environmental concern, the results emphasize the value of environmental monitoring of internal drug levels in aquatic wildlife, as well as the need for more research to establish concentration-response relationships.

Mixtures of co-occurring chemicals in freshwater systems across the continental US

Trace chemicals are common in marine and freshwater ecosystems globally. It is recognized that in the environment, individual chemicals are rarely found in isolation. Insufficient work has examined which chemicals co-occur and which methods best identify these mixtures. Using an existing data set, we found evidence that simple correlation analysis is better at identifying mixtures of commonly co-occurring trace chemicals than more commonly used PCA methods. Moreover, simple correlation analysis, unlike PCA, can be used in cases with unbalanced designs and with data points below reportable limits. Application of this approach allowed identification of 10 groups of chemicals commonly found together in freshwaters of the continental US, representing common "chemical syndromes." Better identification of co-occurring chemical combinations could aid in our understanding of biological and ecological effects of aquatic contaminants. This research provides evidence of correlation analyses as a more effective method for identifying commonly co-occurring aquatic contaminants. We also examined the patterns of these mixtures with a dataset consisting of concentrations of 406 trace chemicals from 38 sample locations across the continental US.

Renovated filter filled with poly-3-hydroxybutyrateco-hydroxyvalerate and granular activated carbon for simultaneous removal of nitrate and PPCPs from the secondary effluent

Reclaimed water is in huge demand in water-deficient cities. However, nitrogen, pharmaceuticals and personal care products (PPCPs) are frequent contaminants in reclaimed water that are probable to bring environmental risks. To develop a technology for safe reclaimed water production, in this study, a renovated filter that integrates solid-phase denitrification (SPD) with biodegradable polymer poly-3-hydroxybutyrate-co-hydroxyvalerate (PHBV) and granular activated carbon (GAC) adsorption (SPD-GAC filter) was proposed and applied to remove nitrogen and target PPCPs (metoprolol and diclofenac) simultaneously. The influences of different ratio of the filled PHBV and GAC, and the hydraulic retention time (HRT) on the removal performances were investigated. The results showed that the filter with PHBV/GAC = 1 (25 cm PHBV/25 cm GAC) simultaneously achieved an average NO₃^--N removal efficiency of about 95% with no accumulation of ammonia and nitrite, and an average removal efficiency of PPCPs of about 80%. Compared with PHBV-based SPD system, the integrated SPD-GAC filter significantly improved the control of carbon release and the PPCP removals. SPD-GAC filter also exhibited a strong tolerance for the variation of influent NO₃^--N loading rate, achieving a highest denitrification rate of 0.76-0.82 g N·(L·d)^-1. The integrated SPD-GAC filter proves to be a promising technology for the simultaneous removal of nitrogen and PPCPs from the secondary effluent.

Quantitation and localization of beta-blockers and SSRIs accumulation in fathead minnows by complementary mass spectrometry analyses

Beta-blockers and selective serotonin reuptake inhibitors (SSRIs) enter the environment through the improper disposal of drugs in garbage, sinks, or toilets as well as via excretion after their intended use. Beta-blockers and SSRIs are resistant to biodegradation and highly water soluble, leading to limited removal capabilities by wastewater treatment plants. As a result, these compounds can easily enter the aquatic environment in a biologically active state, posing risks to the behavior, anatomy, and physiology of aquatic organisms through exposure. However, there is insufficient research on the effects of beta-blockers on aquatic vertebrates to have a complete understanding of the impact of beta-blocker pollution on aquatic organisms. Exposing fathead minnows at environmentally-relevant concentrations allows for an accurate representation of how beta-blockers and SSRIs affect and accumulate in aquatic vertebrates. Singular exposures to two beta-blockers and two selective serotonin reuptake inhibitors (SSRIs) at seven days modeled how pollution affects aquatic wildlife during acute exposure events. After exposure, the entire organism was analyzed quantitatively by liquid chromatography mass spectrometry and qualitatively by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Imaging allowed for the determination of the part of the organism in which the drugs were accumulating. Results showed that after seven days of exposure there was accumulation of both the beta-blockers and SSRIs in the fathead minnows. This data represents the first application of LC-MS quantitation guided by MALDI-MSI in aquatic toxicology-type research in environmental analytical chemistry.

Occurrence and Spatiotemporal Dynamics of Pharmaceuticals in a Temperate-Region Wastewater Effluent-Dominated Stream: Variable Inputs and Differential Attenuation Yield Evolving Complex Exposure Mixtures

Effluent-dominated streams are becoming increasingly common in temperate regions and generate complex pharmaceutical mixture exposure conditions that may impact aquatic organisms via drug-drug interactions. Here, we quantified spatiotemporal pharmaceutical exposure concentrations and composition mixture dynamics during baseflow conditions at four sites in a temperate-region effluent-dominated stream (upstream, at, and progressively downstream from effluent discharge). Samples were analyzed monthly for 1 year for 109 pharmaceuticals/degradates using a comprehensive U.S. Geological Survey analytical method and biweekly for 2 years focused on 14 most common pharmaceuticals/degradates. We observed a strong chemical gradient with pharmaceuticals only sporadically detected upstream from the effluent. Seventy-four individual pharmaceuticals/degradates were detected, spanning 5 orders of magnitude from 0.28 to 13 500 ng/L, with 38 compounds detected in >50% of samples. "Biweekly" compounds represented 77 ± 8% of the overall pharmaceutical concentration. The antidiabetic drug metformin consistently had the highest concentration with limited in-stream attenuation. The antihistamine drug fexofenadine inputs were greater during warm- than cool-season conditions but also attenuated faster. Differential attenuation of individual pharmaceuticals (i.e., high = citalopram; low = metformin) contributed to complex mixture evolution along the stream reach. This research demonstrates that variable inputs over multiple years and differential in-stream attenuation of individual compounds generate evolving complex mixture exposure conditions for biota, with implications for interactive effects.

Insights on the metabolization of the antidepressant venlafaxine by meagre (Argyrosomus regius) using a combined target and suspect screening approach

Bioaccumulation of pharmaceuticals in fish exposed to contaminated water can be shaped by their capability to metabolize these xenobiotics, affecting their toxicity and animal welfare. In this study the in vivo metabolization of the antidepressant venlafaxine by the juvenile marine fish meagre (Argyrosomus regius) was evaluated using a combined target and suspect screening analytical approach. Thirteen venlafaxine metabolites were identified, namely N-desmethylvenlafaxine and N,N-didesmethylvenlafaxine, which were unequivocally identified using analytical standards, and 11 more tentatively identified by suspect screening analysis, including two Phase II metabolites formed by amino acid conjugation. All of them were detected in the liver, while in plasma and brain only 9 and 6 metabolites, respectively, were detected. Based on these findings, for the first time, a tentative metabolization pathway of venlafaxine by A. regius is proposed. Contrarily to what happen in humans, N-demethylation was identified as the main route of metabolization of venlafaxine by fish. Our findings highlight species-specificity in the metabolization of venlafaxine and allow a better understanding of venlafaxine's toxicokinetic in fish. These results emphasize the need to investigate the biotransformation of xenobiotics by non-target organisms to have an integrated overview of their environmental exposure and to improve future evaluations of environmental risk assessment.

Evaluating the potential role of bioactive chemicals on the distribution of invasive Asian carp upstream and downstream from river mile 278 in the Illinois waterway

Two non-native carp species have invaded the Illinois Waterway and are a threat to Great Lakes ecosystems. Poor water quality in the upper Illinois Waterway may be a factor contributing to the stalling of the carp population front near river mile 278. In 2015, the U.S. Geological Survey collected 4 sets of water samples from two sites upstream and 4 sites downstream from river mile 278, and one tributary. Each sample was analyzed for up to 649 unique constituents of which 287 were detected including 96 pesticides, 62 pharmaceuticals, 39 wastewater indicator chemicals, 29 metals, 19 volatile organic compounds (VOCs), 6 disinfection by-products (DBPs), 5 hormones, and 5 carboxylic acids. Potential for bioactivity was estimated by comparing chemical concentrations to aquatic life or human health criteria and to in-vitro bioactivity screening results in the U.S Environmental Protection Agency ToxCast™ database. The resulting hazard quotients and exposure-activity ratios (EARs) are toxicity indexes that can be used to rank potential bioactivity of individual chemicals and chemical mixtures. This analysis indicates that several bioactive chemicals (BCs) including: carbendazim, 2,4-D, metolachlor, terbuthylazine, and acetochlor (pesticides); 1,4-dioxane (VOC); metformin, diphenhydramine, sulfamethoxazole, tramadol, fexofenadine, and the anti-depressants (pharmaceuticals); bisphenol A, 4-nonylphenol, galaxolide, 4-tert-octylphenol (wastewater indicator chemical); lead and boron (metals); and estrone (hormone) all occur in the upper Illinois Waterway at concentrations that produce elevated EARs values and may be adversely affecting carp reproduction and health. The clear differences in water quality upstream and downstream from river mile 278 with higher contaminant concentrations and potential bioactivity upstream could represent a barrier to carp range expansion.

Enantiomer-specific bioaccumulation and distribution of chiral pharmaceuticals in a subtropical marine food web

There is a growing concern about the occurrence of chiral pharmaceuticals in the aquatic environment. However, trophic transfer of pharmaceutical enantiomers in marine organisms is still largely unknown. This study assessed the bioaccumulation and spatial distribution of four frequently detected pharmaceuticals - atenolol, metoprolol, venlafaxine, and chloramphenicol, in a subtropical marine food web in Hong Kong waters. Twenty-four species were analyzed, including mollusks, crustaceans, and fishes. Special focus was placed in the chirality of the four analytes comprising ten different stereoisomers. Results showed that mean concentrations of individual pharmaceuticals ranged from <0.03 to 5.88 ng/g wet weight, and invertebrates generally had higher concentrations than fishes. Organisms from Hong Kong western waters were likely more contaminated by the studied pharmaceuticals than those from southern and eastern waters. Trophic dilution was observed for atenolol and chloramphenicol, with trophic magnification factors of 0.164 and 0.517, respectively. R-(+)-atenolol, S-(-)-metoprolol, and R-(-)-venlafaxine were selectively accumulated in fishes, and stereoisomeric impurities of chloramphenicol, i.e., enantiomers apart from R,R-para-form, were widespread in the investigated species. Under the worst-case scenario, atenolol and metoprolol in collected fishes might exceed toxic threshold, while local adults were unlikely to experience health risks from pharmaceutical exposure via seafood consumption.

Environmentally relevant levels of four psychoactive compounds vary in their effects on freshwater fish condition: a brain concentration evidence approach

Background

The aquatic environment has been contaminated with various anthropogenic pollutants, including psychoactive compounds that may alter the physiology and behavior of free-living organisms. The present study focused on the condition and related mortality of the juvenile chub (Squalius cephalus). The aim of the study was to test whether the adverse effects of the antidepressants sertraline and citalopram, the analgesic tramadol and the illicit drug methamphetamine, on fish condition exist under environmentally relevant concentrations and whether these effects persist after a depuration period. Innovative analyses of the fish brain concentrations of these compounds were performed with the aim to show relationship between compound brain tissue concentration and fish condition.

Methods

The laboratory experiment consisted of 42 days of exposure and a subsequent 14-day depuration period with regular monitoring of the condition and mortality of exposed and control fish. Identical methodology, including individual brain concentration analyses for the tested compounds, was applied for all substances. Additional study on feeding under sertraline exposure was also conducted. The feeding was measured from the 28th day of the exposure, three times in a week, by observation of food intake during 15 minutes in social environment.

Results

The effects of particular psychoactive compounds on chub condition varied. While sertraline induced a lower condition and increased mortality, the effects of methamphetamine were inverse, and tramadol and citalopram had no significant effect at all. Individual brain concentrations of the tested compounds showed that the effects of sertraline and methamphetamine on fish condition were increased with brain concentration increases. Additionally, the food intake was reduced in case of sertraline. In contrast, there was no relationship between tramadol and citalopram brain tissue concentration and fish condition, suggesting that the concentration-dependent effect is strongly compound-specific. Methamphetamine was the only compound with a persistent effect after the depuration period. Our results demonstrate the suitability of the brain concentration evidence approach and suggest that changes in fish condition and other related parameters can be expected in freshwater ecosystems polluted with specific psychoactive compounds.

Dopamine mediates life-history responses to food abundance in Daphnia

Expression of adaptive reaction norms of life-history traits to spatio-temporal variation in food availability is crucial for individual fitness. Yet little is known about the neural signalling mechanisms underlying these reaction norms. Previous studies suggest a role for the dopamine system in regulating behavioural and morphological responses to food across a wide range of taxa. We tested whether this neural signalling system also regulates life-history reaction norms by exposing the zooplankton Daphnia magna to both dopamine and the dopamine reuptake inhibitor bupropion, an antidepressant that enters aquatic environments via various pathways. We recorded a range of life-history traits across two food levels. Both treatments induced changes to the life-history reaction norm slopes. These were due to the effects of the treatments being more pronounced at restricted food ration, where controls had lower somatic growth rates, higher age and larger size at maturation. This translated into a higher population growth rate (r) of dopamine and bupropion treatments when food was restricted. Our findings show that the dopamine system is an important regulatory mechanism underlying life-history trait responses to food abundance and that bupropion can strongly influence the life history of aquatic species such as D. magna. We discuss why D. magna do not evolve towards higher endogenous dopamine levels despite the apparent fitness benefits.

Selected Pharmaceuticals in Different Aquatic Compartments: Part II-Toxicity and Environmental Risk Assessment

Potential risks associated with releases of human pharmaceuticals into the environment have become an increasingly important issue in environmental health. This concern has been driven by the widespread detection of pharmaceuticals in all aquatic compartments. Therefore, 22 pharmaceuticals, 6 metabolites and transformation products, belonging to 7 therapeutic groups, were selected to perform a review on their toxicity and environmental risk assessment (ERA) in different aquatic compartments, important issues to tackle the water framework directive (WFD). The toxicity data collected reported, with the exception of anxiolytics, at least one toxicity value for concentrations below 1 µg L⁻¹. The results obtained for the ERA revealed risk quotients (RQs) higher than 1 in all the aquatic bodies and for the three trophic levels, algae, invertebrates and fish, posing ecotoxicological pressure in all of these compartments. The therapeutic groups with higher RQs were hormones, antiepileptics, anti-inflammatories and antibiotics. Unsurprisingly, RQs values were highest in wastewaters, however, less contaminated water bodies such as groundwaters still presented maximum values up to 91,150 regarding 17α-ethinylestradiol in fish. Overall, these results present an important input for setting prioritizing measures and sustainable strategies, minimizing their impact in the aquatic environment.

Depressed, hypertense and sore: Long-term effects of fluoxetine, propranolol and diclofenac exposure in a top predator fish

Pharmaceutical compounds are continuously released into the aquatic environment, resulting in their ubiquitous presence in many estuarine and coastal systems. As pharmaceuticals are designed to produce effects at very low concentrations and target specific evolutionary conserved pathways, there are growing concerns over their potential deleterious effects to the environment and specifically to aquatic organisms, namely in early life-stages. In this context, the long-term effects of exposure of juvenile meagre Argyrosomus regius to three different pharmaceuticals were investigated. Fish were exposed to environmental concentrations of one of three major used pharmaceuticals: the antidepressant fluoxetine (0.3 and 3 μg/L for 15 days), the anti-hypertensive propranolol and the non-steroidal anti-inflammatory agent diclofenac (0.3 and 15 μg/L for 30 days). Pharmaceuticals bioconcentration in fish muscle was examined, along with biomarkers in different tissues related with antioxidant and biotransformation responses (catalase, superoxide dismutase, ethoxyresorufin-O-deethylase and glutathione S-transferase), energetic metabolism (lactate dehydrogenase, isocitrate dehydrogenase and electron transport system activities), neurotransmission (acetylcholinesterase activity) and oxidative damage (DNA damage and lipid peroxidation levels). Overall, each pharmaceutical had different potential for bioconcentration in the muscle (FLX > PROP > DCF) and induced different biological responses: fluoxetine was the most toxic compound to juvenile meagre, affecting fish growth, triggering antioxidant defense responses, inhibiting detoxification mechanisms and increasing lipid peroxidation and DNA damage in the liver; propranolol exposure increased DNA damage and decreased aerobic metabolism in fish muscle; and diclofenac showed no potential to bioconcentrate, yet it affected fish metabolism by increasing cellular energy consumption in the muscle and consequently reducing fish net energy budget. The diverse response patterns evidence the need for future research focused on pharmaceuticals with different modes of action and their exposure effects on organismal physiological mechanisms and homeostatic status. Ultimately, the combination of sub-individual and individual responses is key for ecologically relevant assessments of pharmaceutical toxicity.