Bioconcentration, metabolism and effects of diphenhydramine on behavioral and biochemical markers in crucian carp (Carassius auratus)

First insight into the formation of transformation products of a biopesticide guvermectin in rat and its health risk

Guvermectin is a new chemical isolated from the microbial metabolites and is registered as a novel plant growth regulator. However, the biotransformation behavior and toxicity of guvermectin to mammals remain unclear and have unknown implications for consumers or occupationally exposed persons. Therefore, we investigated the biotransformation of guvermectin in vivo and in vitro, its effects on CYP450s activities, and its oral toxicity in rats. The results showed that guvermectin could be rapidly absorbed when administered orally and eliminated rapidly in the serum, with a half-life of 6.3 h. Four phase І metabolism products of guvermectin in the serum were screened and identified using UPLC-QTOF/MS. Two products, adenine and psicofuramine, were confirmed using reference standards. Hydrolysis and oxidation reactions were the main transformation pathways. Oral toxicity tests in rats showed that guvermectin exhibited light toxicity to rats (LC50 > 5000 mg/kg b.w.). However, an in vitro probe drug experiment revealed that guvermectin could induce CYP2D6 activity, and a lower concentration of guvermectin exhibited a stronger effect on CYP2D6 than higher concentration (1.38-fold). Molecular docking studies implied that guvermectin was an antagonist of CYP1A2, CYP2C9, and CYP3A4. These findings provided a better understanding of the environmental and human health risks associated with guvermectin and promote its rational use. However, the potential risk of endocrine disruption can not be ignored due to the presence of nucleoside-like metabolites.

Effects of diphenhydramine on crayfish cytochrome P450 activity and antioxidant defence mechanisms: First evidence of CYP2C- and CYP3A-like activity in marbled crayfish

Growing evidence has reported that diphenhydramine (DPH), an ionisable antihistamine, is widely present in surface waters across the world. Relative to vertebrates studied, its impact on invertebrates, particularly concerning cytochrome P450 (CYP) metabolism and oxidative stress, remains poorly understood. In this study, we aimed to investigate the effects of 2, 20, and 200 µg/L DPH on marbled crayfish (Procambarus virginalis) after 96-h exposure. Specifically, we assessed CYP activity, antioxidant enzyme responses, and acetylcholinesterase (AChE) activity in gills, muscle, and hepatopancreas. The crayfish CYP metabolised fluorogenic CYP-metabolic substrates of 7-benzyloxy-4-trifluoromethylcoumarin (BFC) and dibenzylfluorescein (DBF), which evidenced the activity of CYP2C and CYP3A isoforms, well known in mammalian detoxification metabolism. Both BFC and DBF dealkylations showed a positive correlation with each other but were negatively correlated to water and haemolymph DPH concentrations. Exposure to 200 µg/L DPH elicited an apparent inhibition trend, albeit not significant, in BFC- and DBF-transformation activities in crayfish. Other tested 7-benzyloxyresorufin and 7-pentoxyresorufin substrates were poorly metabolised, suggesting their relatively low activity or the lack of mammalian-like CYP1A and CYP2B isoforms in marbled crayfish. The significant modulation of antioxidant enzymes was demonstrated in gills and hepatopancreas. The exposure to DPH did not alter the activity of AChE. Integrated biomarker response version 2 showed the highest cumulative effect of DPH exposure on gills, implying that gill tissue is the most reliable matrix for evaluating DPH toxicity. Activities of glutathione peroxidase and glutathione-S-transferase were the most deviated determinants among the investigated biomarkers, providing insights into the DPH toxicity in crayfish. This study brought the first insight into utilising the fluorogenically active substrates BFC and DBF to demonstrate the CYP involvement in the detoxification metabolism in marbled crayfish. Further, our results provided information on valuable antioxidant defence mechanisms and biomarker responses for a future DPH toxicity assessment in aquatic organisms.

Assessment, distribution, and ecological risk of contaminants of emerging concern in a surface water-sediment-fish system impacted by wastewater

The presence of contaminants of emerging concern in aquatic ecosystems represents an ever-increasing environmental problem. Aquatic biota is exposed to these contaminants, which can be absorbed and distributed to their organs. This study focused on the assessment, distribution, and ecological risk of 32 CECs in a Spanish river impacted by effluents from a wastewater treatment plant, analyzing the organs and plasma of common carp. Environmental concentrations in water and sediment were examined at sites upstream and downstream of the wastewater treatment plant. The two downstream sites showed 15 times higher total concentrations (12.4 μg L-1 and 30.1 μg L-1) than the two upstream sites (2.08 μg L-1 and 1.66 μg L-1). Half of the CECs were detected in fish organs, with amantadine having the highest concentrations in the kidney (158 ng g-1 w.w.) and liver (93 ng g-1 w.w.), followed by terbutryn, diazepam, and bisphenol F in the brain (50.2, 3.82 and 1.18 ng g-1 w.w.). The experimental bioaccumulation factors per organ were compared with the bioconcentration factors predicted by a physiologically based pharmacokinetic model, obtaining differences of one to two logarithmic units for most compounds. Risk quotients indicated a low risk for 38 % of the contaminants. However, caffeine and terbutryn showed an elevated risk for fish. The mixed risk quotient revealed a medium risk for most of the samples in the three environmental compartments: surface water, sediment, and fish.

Effects of diphenhydramine exposure on reproduction of mature Japanese medaka (Oryzias latipes)

Diphenhydramine (DPH) is an antihistamine drug. It has been frequently detected in the environment, because it is not completely degraded in wastewater treatment plants. Recent studies have shown the adverse effects of DPH exposure to various aquatic organisms; however, its chronic effects on fish have been poorly elucidated. In this study, several pairs of mature Japanese medaka (Oryzias latipes) were exposed to DPH for a long period to determine the effects of DPH exposure on the subsequent generations, number of spawned and fertilized eggs, expression of sex-related genes, feeding behavior, embryo development, hatching rate, malformations among the hatched larvae, and mortality rate. The number of spawned eggs significantly decreased, when the parent fish were continuously exposed to 31.6 μg/L DPH for over 46 days. DPH exposure also altered the feeding behavior of medaka individuals, and increased the larval mortality rate. The effects of DPH exposure to fish may occur to some extent in the actual aquatic environment, although the risk evaluations in the field are limited.

Hepatotoxic effects of chronic exposure to environmentally relevant concentrations of Di-(2-ethylhexyl) phthalate (DEHP) on crucian carp: Insights from multi-omics analyses

Di-(2-ethylhexyl) phthalate (DEHP) is an extensively used phthalate esters (PAEs) that raise growing ecotoxicological concerns due to detrimental effects on living organisms and ecosystems. This study performed hepatotoxic investigations on crucian carp under chronic low-dosage (CLD) exposure to DEHP at environmentally relevant concentrations (20-500 μg/L). The results demonstrated that the CLD exposure induced irreversible damage to the liver tissue. Multi-omics (transcriptomics and metabolomics) analyses revealed the predominant toxicological mechanisms underlying DEHP-induced hepatotoxicity by inhibiting energy production pathways and the up-regulation of the purine metabolism. Disruption of metabolic pathways led to excessive reactive oxygen species (ROS) production and subsequent oxidative stress. The adverse metabolic effects were exacerbated by an interplay between oxidative stress and endoplasmic reticulum stress. This study not only provides new mechanistic insights into the ecotoxicological effects of DEHP under chronic low-dosage exposure, but also suggests a potential strategy for further ecological risk assessment of PAEs.

Emerging micropollutants in aquatic ecosystems and nanotechnology-based removal alternatives: A review

There is a significant concern about the accessibility of uncontaminated and safe drinking water, a fundamental necessity for human beings. This concern is attributed to the toxic micropollutants from several emission sources, including industrial toxins, agricultural runoff, wastewater discharges, sewer overflows, landfills, algal blooms and microbiota. Emerging micropollutants (EMs) encompass a broad spectrum of compounds, including pharmaceutically active chemicals, personal care products, pesticides, industrial chemicals, steroid hormones, toxic nanomaterials, microplastics, heavy metals, and microorganisms. The pervasive and enduring nature of EMs has resulted in a detrimental impact on global urban water systems. Of late, these contaminants are receiving more attention due to their inherent potential to generate environmental toxicity and adverse health effects on humans and aquatic life. Although little progress has been made in discovering removal methodologies for EMs, a basic categorization procedure is required to identify and restrict the EMs to tackle the problem of these emerging contaminants. The present review paper provides a crude classification of EMs and their associated negative impact on aquatic life. Furthermore, it delves into various nanotechnology-based approaches as effective solutions to address the challenge of removing EMs from water, thereby ensuring potable drinking water. To conclude, this review paper addresses the challenges associated with the commercialization of nanomaterial, such as toxicity, high cost, inadequate government policies, and incompatibility with the present water purification system and recommends crucial directions for further research that should be pursued.

Effect of an environmental microplastic mixture from the Seine River and one of the main associated plasticizers, dibutylphthalate, on the sentinel species Hediste diversicolor

The aim of this study was to explore the adverse effects of a microplastic (MP) mixture obtained from litter accumulated in the Seine River (France) compared to those of their major co-plasticizer, dibutylphthalate (DBP), on the sentinel species Hediste diversicolor. A suite of biomarkers has been investigated to study the impacts of MPs (100 mg kg-1 sediment), DBP (38 μg kg-1 sediment) on worms compared to non-exposed individuals after 4 and 21 days. The antioxidant response, immunity, neurotoxicity and energy and respiratory metabolism were investigated using biomarkers. After 21 days, worms exposed to MPs showed an increasing aerobic metabolism, an enhancement of both antioxidant and neuroimmune responses. Energy-related biomarkers demonstrated that the energy reallocated to the defence system may come from proteins. A similar impact was depicted after DBP exposure, except for neurotoxicity. Our results provide a better understanding of the ecotoxicological effects of environmental MPs and their associated-contaminants on H. diversicolor.

Cocktail effects of emerging contaminants on zebrafish: Nanoplastics and the pharmaceutical diphenhydramine

Nanoplastics (NPLs) became ubiquitous in the environment, from the air we breathe to the food we eat. One of the main concerns about the NPLs risks is their role as carrier of other environmental contaminants, potentially increasing their uptake, bioaccumulation and toxicity to the organisms. Therefore, the main aim of this study was to understand how the presence of polystyrene NPLs (∅ 44 nm) will influence the toxicity (synergism, additivity or antagonism) of the antihistamine diphenhydramine (DPH), towards zebrafish (Danio rerio) embryos, when in dual mixtures. After 96 hours (h) exposure, at the organismal level, NPLs (0.015 or 1.5 mg/L) + DPH (10 mg/L) induced embryo mortality (90%) and malformations (100%) and decreased hatching (80%) and heartbeat rates (60%). After 120 h exposure, NPLs (0.015 or 1.5 mg/L) + DPH (0.01 mg/L) decreased larvae swimming distance (30-40%). At the biochemical level, increased glutathione S-transferases (55-122%) and cholinesterase (182-343%) activities were found after 96 h exposure to NPLs (0.015 or 1.5 mg/L) + DPH (0.01 mg/L). However, catalase (CAT) activity remained similar to the control group in the mixtures, inhibiting the effects detected after the exposure to 1.5 mg/L NPLs alone (increased 230% of CAT activity). In general, the effects of dual combination - NPLs + DPH (even at concentrations as low as 10 μg/L of DPH) - were more harmful than the correspondent individual exposures, showing the synergistic interactions of the dual mixture and answering to the main question of this work. The obtained results, namely the altered toxicity patterns of NPLs + DPH compared with the individual exposures, show the importance of an environmental risk assessment considering NPLs as a co-contaminant due to the potential NPLs role as vector for other contaminants.

Oxidative Stress of Cadmium and Lead at Environmentally Relevant Concentrations on Hepatopancreas of Macrobrachium nipponensis and Their Mixture Interactivity: Implications for Water Quality Criteria Amendment

The biotoxicity of heavy metals in water has always been the focus of ecological health research. In this study, the oxidative stress-associated toxicity of cadmium (Cd) and lead (Pb) at environmentally relevant concentrations on the hepatopancreas of Macrobrachium nipponensis was investigated based on multiple biomarker responses in a 28-day indoor exposure study. Changes in integrated biomarker responses (IBR) and their interactivity were subsequently analyzed. No dead individuals were found across any of the tested conditions. The chronic toxicity of heavy metals depended on their type and exposure time at the same concentration. At low concentrations, organisms have a regulatory capacity to cope with the excess reactive oxygen species (ROS) induced by Pb stress over time. In detail, the activity of superoxide dismutase (SOD) was inhibited by Pb stress at a high concentration as time passed. The sensitivity of metallothionein (MT) to Cd was stronger than Pb, and the potential for Cd to cause lipid peroxidation damage was higher than Pb. At the same time, Pb had a greater disturbance effect on the nervous system than Cd, especially in the early exposure stage. The contribution of Cd and Pb to the interaction effect varied dynamically with time and concentration of exposure, but mostly showed antagonism. The results of this study have important significance for guiding the diagnosis of ecological water health, the amendment of water quality criteria, and the management of wastewater discharge.

Integrated biomarker response in signal crayfish Pacifastacus leniusculus exposed to diphenhydramine

Diphenhydramine (DPH) is a pharmaceutical with multiple modes of action, primarily designed as an antihistamine therapeutic drug. Among antihistamines, DPH is a significant contaminant in the environment, frequently detected in surface waters, sediments, and tissues of aquatic biota. In the present study, signal crayfish Pacifastacus leniusculus was used as a model organism because of their prominent ecological roles in freshwater ecosystems. The biochemical effects were investigated in crayfish exposed to the environmental (low: 2 μg L^-1), ten times elevated (medium: 20 μg L^-1), and the sublethal (high: 200 μg L^-1) nominal concentrations of DPH in water for 96 h. Lipid peroxidation, antioxidant enzyme activities, and acetylcholinesterase activity were assessed as toxicological biomarkers in crayfish hepatopancreas, gills, and muscles. Low and medium DPH exposure caused imbalances only in glutathione-like enzyme activities. Integrated biomarker response showed the absolute DPH toxicity effects on all tested tissues under high exposure. This study identified that high, short-term DPH exposure induced oxidative stress in crayfish on multiple tissue levels, with the most considerable extent in muscles.

Multi-omics profiling and biochemical assays reveal the acute toxicity of environmental related concentrations of Di-(2-ethylhexyl) phthalate (DEHP) on the gill of crucian carp (Carassius auratus)

Di-(2-ethylhexyl) phthalate (DEHP) is one of the most extensively utilized plasticizers in the plastic manufacturing process. It is widely used in various fields due to its low cost and excellent effect. Although there is evidence that DEHP is harmful to animal and human health, DEHP-induced gill toxicity in aquatic organisms is inconclusive, and its mechanism has not been fully elucidated. Here, we investigated the effects of DEHP acute exposure on crucian carp gills at environmentally relevant concentrations of 20, 100, and 500 μg/L. Multi-omics profiling and biochemical assays were employed to characterize the potential toxicological mechanisms. The results showed that acute exposure to 100 and 500 μg/L of DEHP leads to oxidative stress in gills, as evidenced by overproduction of reactive oxygen species (ROS), increased antioxidant enzyme activity, and the transformation of glutathione from reduced to oxidized form, resulting in lipid peroxidation. Integrative analysis of transcriptomics and metabolomics indicated that increased purine metabolism was the potential source of increased ROS. Moreover, lipid metabolism disorder, including arachidonic acid metabolism, induces inflammation. Further, DEHP causes the imbalance of the CYP enzyme system in the gill, and DEHP-induced gill toxicity in crucian carp was associated with interference with CYP450 homeostasis. Taken together, this study broadens the molecular understanding of the DEHP-induced gill toxicity in aquatic organisms and provides novel perspectives for assessing the effects of DEHP on target and non-target aquatic organisms in the environment.

Assessment of diphenhydramine toxicity - Is its mode of action conserved between human and zebrafish?

The main aim of the study is to evaluate the effects of the pharmaceutical diphenhydramine (DPH) on embryo-larvae Danio rerio across distinct levels of organization - individual and subcellular - and correlate those effects with the DPH mode of action (MoA) assessed by in silico analysis. An embryos heartbeat rate reduction was observed at 10 mg/L DPH, but 0.001 to 10 mg/L did not significantly affect the zebrafish survival, hatching and morphology. Larvae swimming distance decreased (hypoactivity) at 1 and 10 mg/L DPH. Moreover, the straightforward movements decrease and the increase in the zigzag movements or movements with direction changes, shown an erratic swimming behavior. Energy budgets decreased for lipid (0.01 mg/L DPH) and carbohydrate (10 mg/L DPH) contents. Cholinesterase (neural function) and glutathione S-transferase (Phase II biotransformation/antioxidant processes) increased their activities at 10 mg/L DPH, where a decrease in the total glutathione content (antioxidant system) was observed. DNA damage was found at 0.01 and 10 mg/L DPH. However, a DNA repair occurred after subsequent 72 h in clean media. The in silico study revealed a relevant conservation between human and zebrafish DPH target molecules. These data provide a valuable ecotoxicological information about the DPH effects and MoA to non-target organisms.

Integrated application of multi-omics approach and biochemical assays provides insights into physiological responses to saline-alkaline stress in the gills of crucian carp (Carassius auratus)

Given the decline of freshwater resources in recent years, the accessible space for freshwater aquaculture is rapidly shrinking, and aquaculture in saline-alkaline water has become a critical approach to meet the rising demand. However, the molecular mechanism behind the adverse effects of saline-alkaline water on fish and the regulatory mechanism in fish tolerance remains unclear. Here, adult crucian carp (Carassius auratus) were exposed to 60 mmol/L NaHCO₃ for 30 days. It was observed that long-term carbonate alkalinity (CA) exposure not only caused gill oxidative stress but also changed the levels of several physiological parameters associated with ammonia transport, including blood ammonia, urea nitrogen (BUN), glutamine (Gln), and glutamine synthetase (GS). According to the metabolomics study, differential metabolites (DMs) engaged in various metabolic pathways, such as glycerophospholipid metabolism, sphingolipid metabolism, and arachidonic acid metabolism. In addition, transcriptomics data showed that differentially expressed genes (DEGs) were closely related to ammonia transport, apoptosis, and immunological response. In general, comprehensive multi-omics and biochemical analysis revealed that crucian carp might adopt Rh glycoprotein as a carrier to mediate ammonia transport and increase glutamine and urea synthesis under long-term high saline-alkaline stress to mitigate the adverse effects of blocked ammonia excretion. Simultaneously, saline-alkaline stress caused the destruction of the antioxidant system and the disorder of lipid metabolism in the crucian carp gills, which induced apoptosis and immunological response. To our knowledge, this is the first study to investigate fish's molecular and metabolic mechanisms under saline-alkaline stress using integrated metabolomics, transcriptomics, and biochemical assays. Overall, the results of this study provided new insights into the molecular mechanism behind the adverse effects of saline-alkaline water on fish and the regulatory mechanism in fish tolerance.

Single and Mixture Toxicity of Boron and Vanadium Nanoparticles in the Soil Annelid Enchytraeus crypticus: A Multi-Biomarker Approach

The increased use and production of new materials has contributed to Anthropocene biodiversity decrease. Therefore, a careful and effective toxicity evaluation of these new materials is crucial. However, environmental risk assessment is facing new challenges due to the specific characteristics of nanomaterials (NMs). Most of the available ecotoxicity studies target the aquatic ecosystems and single exposures of NMs. The present study evaluated Enchytraeus crypticus survival and reproduction (28 days) and biochemical responses (14 days) when exposed to nanoparticles of vanadium (VNPs) and boron (BNPs) (single and mixture; tested concentrations: 10 and 50 mg/kg). Although at the organism level the combined exposures (VNPs + BNPs) did not induce a different toxicity from the single exposures, the biochemical analysis revealed a more complex picture. VNPs presented a higher toxicity than BNPs. VNPs (50 mg/kg), independently of the presence of BNPs (additive or independent effects), caused a decrease in survival and reproduction. However, acetylcholinesterase, glutathione S-transferase, catalase, glutathione reductase activities, and lipid peroxidation levels revealed alterations in neurotoxicity, detoxification and antioxidant responses, depending on the time and type of exposure (single or mixture). The results from this study highlight different responses of the organisms to contaminants in single versus mixture exposures, mainly at the biochemical level.

Does aquatic sediment pollution result in contaminated food sources?

The sediment pollution of the aquatic environment by waste due to anthropogenic activity is of an increasing concern. The contaminants coming from the aquatic environment can enter the aquatic food chain and accumulate in the tissues of fish and shellfish used for human consumption. The aim of this study was to sum up the current level of knowledge concerning the pollution of aquatic sediments and its transfer to aquatic foods as well as to indicate whether such contamination has the potential to affect the health and welfare of aquatic organisms as well as the quality and safety of the species intended for human consumption. Based on the results of scientific studies, the European Food Safety Authority, and the Rapid Alert System for Food and Feed, contamination of fish and seafood occurs predominantly through their diet and the levels of bioaccumulative contaminants are higher in fish which rank higher in the food chain. Contamination of aquatic habitats can not only significantly affect behavior, development, and welfare of aquatic organisms, but it can also affect the safety of fish and seafood for human consumption.

Pharmaceutical uptake kinetics in rainbow trout: In situ bioaccumulation in an effluent-dominated river influenced by snowmelt

Whether seasonal instream flow dynamics influence bioaccumulation of pharmaceuticals by fish is not well understood, specifically for urban lotic systems in semi-arid regions when flows are influenced by snowmelt. We examined uptake of select pharmaceuticals in rainbow trout (Oncorhynchus mykiss) caged in situ upstream and at incremental distances downstream (0.1, 1.4, 13 miles) from a municipal effluent discharge to East Canyon Creek in Park City, Utah, USA during summer and fall of 2018. Fish were sampled over 7-d to examine if uptake occurred, and to define uptake kinetics. Water and fish tissues were analyzed via isotope dilution liquid chromatography tandem mass spectrometry. Several pharmaceuticals were consistently detected in water, fish tissue and plasma, including carbamazepine, diphenhydramine, diltiazem, and fluoxetine. Pharmaceutical levels in water ranged up to 151 ng/L for carbamazepine, whereas the effluent tracer sucralose was consistently observed at low μg/L levels. During both summer and fall experiments at each of three downstream locations from effluent discharge, rainbow trout rapidly accumulated these pharmaceuticals; tissue levels reached steady state conditions within 24-96 h. Spatial and temporal differences for pharmaceutical levels in rainbow trout directly corresponded with surface water exposure concentrations, and uptake kinetics for individual pharmaceuticals did not vary among sites or seasons. Such observations are consistent with recent laboratory bioconcentration studies, which collectively indicate inhalational exposure from water governs rapid accumulation of ionizable base pharmaceuticals by fish in inland surface waters.

A review of the influences of microplastics on toxicity and transgenerational effects of pharmaceutical and personal care products in aquatic environment

PPCPs (pharmaceutical and personal care products) and microplastics (MPs) are two types of emerging pollutants that are ubiquitous and widely concerned in the environment. Both of them can accumulate in fish or aquatic invertebrates and transfer to offspring, thereby producing toxic effects on both parents and offspring, in which the characteristics of MPs also enable them to adsorb PPCPs thus producing carrier effects. In this study, we have conducted a comprehensive review of MPs and PPCPs and found that MPs can act as a carrier of PPCPs to influence the bioaccumulation of PPCPs. MPs and PPCPs have toxicity and transgenerational effects on both fish and aquatic invertebrates in many aspects, and MPs can also affect the toxicity and transgenerational effects of PPCPs due to their carrier effects. This paper revealed that MPs may have an important impact on the bioavailability of PPCPs and the interaction between MPs and PPCPs is a hot topic in future research. This study also puts forward the shortcomings of the current research and related suggestions, and relevant research should be carried out as soon as possible to provide the basis for the prevention and treatment of fresh water.

Influence of aquatic colloids on the bioaccumulation and biological effects of diclofenac in zebrafish (Danio rerio)

Natural aquatic colloids play an important role in the migration, transformation of pollutants in the environment, but their potential effects are often ignored in ecotoxicology research. In this study, diclofenac (DCF) was selected as a typical drug to study the effects of natural colloids on the bioaccumulation and biotoxicity in juvenile zebrafish (Danio rerio) exposed to an environmentally relevant concentration (1 μg/L) and a high concentration (100 μg/L) of DCF. The results showed that the presence of colloids accelerated and enhanced the accumulation of DCF in zebrafish muscle and viscera, and the effects are greater at the environmentally relevant concentration of DCF. However, the colloids enhanced the burden in the head in the environmentally relevant concentration group, but reduced it in the high concentration group. This observation may be related to the occurrence of variations in the contribution of the adsorption forms of DCF and the colloids depending on different DCF concentrations. At the same time, the presence of colloids can significantly induce AChE activity of DCF in the brain and alter swimming activity and shoaling behaviour of the individuals, however no significant effects on the attack and shock behaviour were observed. These findings indicate that the combination of natural colloids and pollutants may change with pollutant concentrations, thereby altering the bioaccumulation and biological effects in aquatic organisms.

Interactive effects of diclofenac and copper on bioconcentration and multiple biomarkers in crucian carp (Carassius auratus)

Diclofenac (DCF), a non-steroidal anti-inflammatory drug, is widespread in aquatic environments and coexists with heavy metals to form combined pollution. However, the interactive effects of DCF and heavy metals on aquatic organisms remain unknown. This study aimed to investigate the interactive effects of DCF and copper (Cu) on the bioconcentration, oxidative stress status and detoxification-related gene expression in crucian carp (Carassius auratus). Fish were exposed to Cu (100 μg L^-1) and DCF (1, 10, 100 and 1000 μg L^-1) alone or in combination for 7 days. Results obtained showed that the treatment of Cu combined with high levels of DCF (100 and 1000 μg L^-1) significantly decreased tissue concentrations of DCF and Cu compared to the correspondingly individual exposure. Concerning oxidative stress status, as reflected by the activities of antioxidant enzymes and malondialdehyde content, low exposure concentrations of DCF (1 and 10 μg L^-1) seemed to mitigate the oxidative stress induced by Cu, whereas the co-exposure of Cu with the highest level of DCF (1000 μg L^-1) led to stronger oxidative damage in fish liver than Cu exposure alone. With regarding to detoxification-related genes, in most cases, the expressions of cyp 1a, cyp 3a, gstα, gstπ, pxr and P-gp in crucian carp were significantly altered upon exposure to the compounds in combination compared to exposure to the compounds individually. Collectively, these findings indicate the capacity of each of these pollutants to alter bioconcentration potential, pro-oxidative effects and detoxification-related gene responses of the other when both co-occur at specific concentrations.

Toxicity assessment of municipal sewage treatment plant effluent by an integrated biomarker response in the liver of crucian carp (Carassius auratus)

In this study, crucian carp (Carassius auratus) was exposed to the increasing concentrations of municipal sewage treatment plant effluent (MSTPE) for 15 days, and the activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and acetylcholinesterase (AChE), together with the contents of malondialdehyde (MDA) and glutathione (GSH) in the liver of C. auratus were investigated. Moreover, the integrated biomarker response (IBR) approach was applied to assess the adverse effects of MSTPE in freshwater. The aim of the study was to provide an effective biological indicator for evaluating the toxicity effects and ecological risks of MSTPE in the freshwater environment quantitatively. Results showed that MSTPE could cause oxidative damage to the liver of C. auratus, which reflected through the increasing MDA content over the exposure period. MSTPE also led to the biochemical responses of antioxidant defense in C. auratus liver, such as the enhancement of SOD, CAT, and GPx activities, as well as the inhibition of AChE activity and GSH content. It was found that MDA, SOD, GPx, and GSH could be used as the biomarkers for reflecting the adverse effects of MSTPE in the receiving freshwater on the 12th day of exposure. A significant increase of IBR values was observed as the increasing concentration of MSTPE, and the IBR values presented a significant positive correlation (r = 0.891, P < 0.05) with the increasing concentrations of MSTPE, indicating that IBR approach is a promising tool for assessing the toxicity effects of MSTPE in environmental freshwater.

Metabolomic Investigations of the Temporal Effects of Exposure to Pharmaceuticals and Personal Care Products and Their Mixture in the Eastern Oyster (Crassostrea virginica)

The eastern oyster (Crassostrea virginica) supports a large aquaculture industry and is a keystone species along the Atlantic seaboard. Native oysters are routinely exposed to a complex mixture of contaminants that increasingly includes pharmaceuticals and personal care products (PPCPs). Unfortunately, the biological effects of chemical mixtures on oysters are poorly understood. Untargeted gas chromatography-mass spectrometry metabolomics was utilized to quantify the response of oysters exposed to fluoxetine, N,N-diethyl-meta-toluamide, 17α-ethynylestradiol, diphenhydramine, and their mixture. Oysters were exposed to 1 µg/L of each chemical or mixture for 10 d, followed by an 8-d depuration period. Adductor muscle (n = 14/treatment) was sampled at days 0, 1, 5, 10, and 18. Trajectory analysis illustrated that metabolic effects and class separation of the treatments varied at each time point and that, overall, the oysters were only able to partially recover from these exposures post-depuration. Altered metabolites were associated with cellular energetics (i.e., Krebs cycle intermediates), as well as amino acid metabolism and fatty acids. Exposure to these PPCPs also affected metabolic pathways associated with anaerobic metabolism, osmotic stress, and oxidative stress, in addition to the physiological effects of each chemical's postulated mechanism of action. Following depuration, fewer metabolites were altered, but none of the treatments returned them to their initial control values, indicating that metabolic disruptions were long-lasting. Interestingly, the mixture did not directly cluster with individual treatments in the scores plot from partial least squares discriminant analysis, and many of its affected metabolic pathways were not well predicted from the individual treatments. The present study highlights the utility of untargeted metabolomics in developing exposure biomarkers for compounds with different modes of action in bivalves. Environ Toxicol Chem 2020;39:419-436. © 2019 SETAC.

Occurrence, spatial-temporal distribution and ecological risks of pharmaceuticals and personal care products response to water diversion across the rivers in Nanjing, China

Water diversion projects have been continuously used to alleviate water quality issues that arise during urbanization. However, studies about whether it has possible effects on the status of pharmaceutical and personal care products (PPCPs) are limited. In this study, the occurrence trends and spatial-temporal distribution characteristics of 50 PPCPs were investigated in surface water, suspended particulate matter (SPM) and sediments in Nanjing urban rivers under the background of the water diversion project from the Yangtze River to the Qinhuai River. In the four field campaigns that were embarked on April to July 2018, a total of 40, 38 and 24 PPCPs were detected in surface water, SPM and sediments, respectively, with overall concentrations of 138-1990 ng/L, 3214-33,701 ng/g and 12.1-109 ng/g dry weight (dw) among nine sampling sites. The excessive concentration of caffeine (20.6-905 ng/L) may be evidence of the direct discharge of untreated sewage and an obvious indicator of the overall concentrations of PPCPs. The PPCPs contamination levels in surface water were increased along with the direction of the water diversion in urban runoff, and decreased by 8-31% due to the increase in volume attributable to the water diversion. The distribution coefficients (K_d) of pollutants in the SPM-water phases (3.0-5.6 L/kg) were two orders of magnitude higher than those in the sediment-water phases (0.3-3.3 L/kg). And the positive correlations between their log K_ow and SPM-water log K_d values indicated SPM was the important carrier determining the fate of organic UV filters. Furthermore, the results of ecological risk assessment demonstrated that although the increase in the volume of water caused by the water diversion reduced the overall ecological risks of PPCPs in urban rivers, the current contamination level still represents high risks to algae and fish.

Interactive Effects of Sertraline and Diphenhydramine on Biochemical and Behavioral Responses in Crucian Carp (Carassius auratus)

The ecotoxicity of psychiatric pharmaceuticals to aquatic organisms is being increasingly recognized. However, current ecological studies focus on the effects of individual psychiatric pharmaceuticals, with little attention being given to their combined effects. In this study, the interactive effects of two psychiatric pharmaceuticals, sertraline (SER) and diphenhydramine (DPH), on bioconcentration and biochemical and behavioral responses were investigated in crucian carp (Carassius auratus) after seven days of exposure. DPH was found to increase the accumulation of SER in fish tissues relative to SER-alone exposure. In addition, the mixture of SER and DPH significantly changed the activities of antioxidant enzymes and led to significant increases in malondialdehyde content, relative to SER alone. Concerning the neurotoxicity, relative to SER-alone exposure, brain AChE activity was significantly enhanced in fish following the combined exposure. Regarding behavioral responses, swimming activity and shoaling behavior were significantly altered in co-exposure treatments compared with the SER alone. Moreover, the inhibition effects on the feeding rates were increased in co-exposure treatments compared to SER alone. Collectively, our results suggest that the mixtures of psychiatric pharmaceuticals may pose more severe ecological risks to aquatic organisms compared to these compounds individually.

pH-Dependent Uptake and Sublethal Effects of Antihistamines in Zebrafish (Danio rerio) Embryos

Reported off-target effects of antihistamines in humans draw interest in ecotoxicity testing of first- and second-generation antihistamines, the latter of which have fewer reported side effects in humans. Because antihistamines are ionizable compounds, the pH influences uptake and toxicity and thus is highly relevant when conducting toxicity experiments. Zebrafish embryo toxicity tests were performed with the 3 first-generation antihistamines ketotifen, doxylamine, and dimethindene and the 2 second-generation antihistamines cetirizine and levocabastine at pH 5.5, 7.0, and 8.0. We detected effects on survival, phenotype, swimming activity, and heart rate for 4 antihistamines with the exception of levocabastine, which did not show any lethal or sublethal effects. When compared to lethal concentrations, effect concentrations neither of phenotype malformation nor of swimming activity or heart rate deviated by more than a factor of 10 from lethal concentrations, indicating that all sublethal effects were fairly nonspecific. First-generation antihistamines are weak bases and showed decreasing external effect concentrations with increasing neutral fraction, accompanied by increased uptake in the fish embryo. As a result, internal effect concentrations were independent from external pH. The pH-dependent toxicity originates from speciation-dependent uptake, with neutral species taken up in higher amounts than the corresponding ionic species. Cetirizine, which shifts from a zwitterionic to an anionic state in the measured pH range, did not show any pH-dependent uptake or toxicity. Environ Toxicol Chem 2019;00:1-11. © 2019 SETAC.

Physiologically based toxicokinetics (PBTK) models for pharmaceuticals and personal care products in wild common carp (Cyprinus carpio)

Pharmaceutical and personal care products (PPCPs) are regarded as "pseudo-persistent" pollutants due to their being continuously loaded into the aquatic environment. Physiologically based toxicokinetics (PBTK) models that can quantitatively describe absorption, distribution, metabolism and excretion processes of chemicals in biota are of importance to predict internal exposure (e.g. doses at specific target tissues/organs) from external exposure concentrations. In this study, PBTK models with up to six compartments including brain, liver, kidney, gills, richly perfused tissues and poorly perfused tissues, were developed for predicting internal distribution of 10 PPCPs in wild common carp (Cyprinus carpio). The PBTK predicted concentrations were close to the measured ones, with deviations less than 1 log unit for most of PPCPs. Sensitivity analysis showed that various partition coefficients of the chemicals exerted significant influence on model outputs.

Molecular and phenotypic responses of male crucian carp (Carassius auratus) exposed to perfluorooctanoic acid

Perfluorooctanoic acid (PFOA) has long been produced and widely used due to its excellent water and oil repellent properties. However, this trend has facilitated to the ubiquitous existence of PFOA in environmental matrix, and the potential ecotoxicity on aquatic organisms has not been fully elucidated. To study the tissue-specific bioconcentration and the nervous system- and energy-related biochemical effects of PFOA, as well as the phenotypic alterations by this chemical, male crucian carp (Carassius auratus) were exposed to gradient concentrations of PFOA (nominal 0.2, 10, 500 and 25,000 μg/L) in a flow-through apparatus for 7 days. PFOA was enriched in tissues following an order of blood > kidney ≥ liver > gill > brain > muscle. The bioconcentration factors ranged from 0.1 to 60.4. Acetylcholinesterase activity in the fish brain was inhibited, while liver carboxylesterase was induced in most cases and attenuated with time. The acyl-CoA oxidase activity was dose-dependently elevated and accompanied by a decline of ATP contents. PFOA treatments also inhibited the activity of the electron transport system (ETS). At the transcriptional level, ETS component complexes II and IV were concordantly depressed, and ATP synthesis was also downregulated. The mRNA level of peroxisome proliferator activated receptor α was increasingly upregulated, with related downstream genes upregulated in varying degrees. The phenotypes showed patterns of increased liver pathology and reduced swimming activity. In summary, PFOA leads to adverse effects in Carassius auratus related to multiple aspects, which may be associated with the nervous system, fundamental energy metabolism and other unpredictable factors. The results obtained in this study are expected to help clarify the PFOA toxic mechanisms on energy relevance.

Bioconcentration and ecotoxicity of sulfadiazine in the aquatic midge Chironomus riparius

Although sulfadiazine (SDZ) is widespread in aquatic environments, information regarding the effects of SDZ on aquatic insects is still limited. In the present study, the bioconcentration and the effects of SDZ on the antioxidant system and the expression of endocrine and stress-related genes in Chironomus riparius larvae were investigated. The larvae were exposed to SDZ at the nominal concentrations of 2, 20 and 200 μg/L for 48 h. The results showed that SDZ was taken up by C. riparius despite presenting low bioconcentration factor values (0.99-3.92). In addition, superoxide dismutase activity was markedly reduced compared with the control group, whereas the levels of malondialdehyde were not significantly affected by SDZ. Moreover, the mRNA expression of genes related to heat shock proteins (Hsp70 and Hsp27) and ecdysone pathway (EcR and E74) were significantly up-regulated following all SDZ treatments. In aggregate, our work provides novel and interesting results regarding the potential biochemical and genetic effects of SDZ on freshwater insects.

Bioconcentration, metabolism and the effects of tetracycline on multiple biomarkers in Chironomus riparius larvae

The antibiotic tetracycline (TC) is widespread in surface waters, but few data are available regarding its adverse effects on aquatic insects. In this study, we investigated the bioconcentration, metabolism, and effects of TC on Chironomus riparius larvae exposed to different concentrations of TC (1.83, 18.5 and 174 μg L^-1) for 48 h. The bioconcentration factors were 3.65, 0.74 and 0.23 in larvae with exposure to 1.83, 18.5 and 174 μg L^-1 TC, respectively. High concentration ratios of the metabolites anhydrotetracycline (0.56-0.60), 4-epitetracycline (0.43-0.69), and 4-epianhydrotetracycline (0.50-0.55) to the unmetabolized compound were found. Additionally, the activities of superoxide dismutase and glutathione S-transferase were markedly inhibited with a significant increase in malondialdehyde contents at high exposure concentrations of TC (18.5 and 174 μg L^-1). Moreover, significant up-regulation of heat shock genes (hsp70 and hsp27), the ecdysone receptor gene, and the E74 early ecdysone responsive gene was observed at all exposure concentrations except for hsp70 at 1.83 μg L^-1. Collectively, these results suggested that TC was quickly absorbed and metabolized by C. riparius and resulted in molecular and biochemical disturbances.

Parental transfer of ethylhexyl methoxy cinnamate and induced biochemical responses in zebrafish

Ethylhexyl methoxy cinnamate (EHMC) is one of the major organic ultraviolet (UV) filter pollutants in the environment. The purpose of this study was to investigate the parental transfer of EHMC and induced biochemical responses in zebrafish (Danio rerio). Zebrafish embryos were exposed to EHMC solution (1, 10, and 100 μg/L) for 4 months until sexual maturation. Then male and female parents were paired to lay eggs. F1 generations were divided into 2 categories: with and without continued EHMC exposure. EHMC was detected in both F0 parents and F1 eggs, indicating that EHMC can accumulate in zebrafish and transfer to offspring through reproduction. The hatching rate decreased and malformation rate increased significantly among parents and progeny embryos in the high concentration exposure group. For 40 dpf (days post-fertilisation) F0 generations, estradiol hormone and vitellogenin (Vtg) contents, the expression levels of Vtg1, P450 aromatase (Cyp19a and Cyp19b), 17β-hydroxysteroid dehydrogenase (Hsd17b1, Hsd17b3), estrogen receptor-alpha and progesterone receptor in all concentration groups decreased significantly, while androgen receptor increased significantly in 10 and 100 μg/L exposure groups compared with the corresponding control group, showing anti-estrogen and androgen effects. For 120 dpf F0 generations, acetylcholinesterase activity was significantly decreased and glutathione and malondialdehyde levels, superoxide dismutase, catalase and glutathione reductase activities were significantly increased in all treatment groups compared with the corresponding control group. In addition, F1 offspring with or without continued exposure to EHMC suffered similar or stronger oxidative stress compared with their parents. DNA breakage and apoptosis also occurred in 120 dpf parental liver cells in all treatment groups as a result of oxidative damage. Results suggested that EHMC have transfer effects between parents and offspring, which may cause negative effects on growth and development of zebrafish and induce biochemical responses in both parents and offspring.

Effects of lomefloxacin on survival, growth and reproduction of Daphnia magna under simulated sunlight radiation

Lomefloxacin, an antibacterial agent with known photo-induced toxicity in clinical studies, is frequently detected in aquatic environments. Investigating the photo-induced toxicity of lomefloxacin in aquatic organisms is therefore of importance for assessing its ecological risks. In this study, the effects of lomefloxacin on survival, growth and reproduction of Daphnia magna under simulated sunlight radiation (SSR) were investigated, and the mechanism of action was revealed. Results indicated that SSR containing UV radiation increased the acute toxicity of lomefloxacin to Daphnia magna relative to white fluorescent light irradiation. Under SSR, 100 μM lomefloxacin significantly enhanced reactive oxygen species (ROS) generation and lipid peroxidation, and decreased activities of superoxide dismutase and catalase. The biochemical observations and apparent effects on the organism indicate that oxidative stress plays a central role in the acute photo-induced toxicity. Chronic toxicity results showed that SSR significantly affected growth and reproduction of Daphnia magna, whereas lomefloxacin reduced the damage of UV radiation in SSR through light shielding. This study provides insight into the mechanism of photo-induced toxicity and can support the risk assessment of chemicals in the aquatic environment by including the impacts of sunlight irradiation on toxicity.

Pharmaceuticals, hormones, pesticides, and other bioactive contaminants in water, sediment, and tissue from Rocky Mountain National Park, 2012-2013

Pharmaceuticals, hormones, pesticides, and other bioactive contaminants (BCs) are commonly detected in surface water and bed sediment in urban and suburban areas, but these contaminants are understudied in remote locations. In Rocky Mountain National Park (RMNP), Colorado, USA, BCs may threaten the reproductive success and survival of native aquatic species, benthic communities, and pelagic food webs. In 2012-2013, 67 water, 57 sediment, 63 fish, 10 frog, and 12 quality-control samples (8 water and 4 sediment) were collected from 20 sites in RMNP. Samples were analyzed for 369 parameters including 149 pharmaceuticals, 22 hormones, 137 pesticides, and 61 other chemicals or conditions to provide a representative assessment of BC occurrence within RMNP. Results indicate that BCs were detected in water and/or sediment from both remote and more accessible locations in RMNP. The most commonly detected BCs in water were caffeine, camphor, para-cresol, and DEET; and the most commonly detected BCs in sediment were indole, 3-methyl-1H-indole, para-cresol, and 2,6-dimethyl-naphthalene. Some detected contaminants, including carbaryl, caffeine, and oxycodone, are clearly attributable to direct local human input, whereas others may be transported into the park atmospherically (e.g., atrazine) or have local natural sources (e.g., para-cresol). One or more pharmaceuticals were detected in at least 1 sample from 15 of 20 sites. Most of the 29 detected pharmaceuticals are excreted primarily in human urine, not feces. Elevated net estrogenicity was observed in 18% of water samples, and elevated vitellogenin in blood was observed in 12% of male trout, both evidence of potential endocrine disruption. Hormone concentrations in sediment tended to be greater than concentrations in water. Most BCs were observed at concentrations below those not expected to pose adverse effects to aquatic life. Results indicate that even in remote locations aquatic wildlife can be exposed to pharmaceuticals, hormones, pesticides, and other bioactive contaminants.

Bioaccumulation and Biomagnification of 2-Ethylhexyl-4-dimethylaminobenzoate in Aquatic Animals

2-Ethylhexyl-4-dimethylaminobenzoate (EHDAB) is a commonly used organic ultraviolet filter. The bioaccumulation and biomagnification of EHDAB were investigated in two aquatic animals, the larvae of midge (Chironomus riparius) and crucian carp (Carassius carassius), and the metabolic enzyme responses in fish liver were determined. EHDAB in the larvae of midge reached a steady state within 10 days of sediment exposure. The biota-sediment accumulation factors ranged from 0.10 to 0.54, and were inversely proportional to the exposure concentrations. The EHDAB-contaminated larvae were used to feed the crucian carp. Within 28 days of feeding exposure, the EHDAB levels in fish tissues gradually increased with the increase of the exposure concentration, exhibiting an apparent concentration-dependence and time-dependence. The liver and kidneys were the main organs of accumulation, and the biomagnification factors of EHDAB ranged from 8.97 to 11.0 and 6.44 to 10.8, respectively. In addition, EHDAB significantly increased the activities of cytochrome P450 (CYP) 1A, CYP3A and glutathione S-transferase in the fish liver. Our results indicate that EHDAB may pose a risk of biomagnification in an aquatic environment and influence the biological processes of exposed organisms.

Responses of antioxidant and biotransformation enzymes in Carassius carassius exposed to hexabromocyclododecane

The ubiquitous existence of hexabromocyclododecane (HBCD) in environmental matrices has made it attractive to both field investigators as well as laboratory researchers. However, literature on the biological effects caused by HBCD on aquatic vertebrates seldom exist. This has inevitably increased the difficulty of toxicological assessment in the aquatic environment. Juvenile crucian carp (Carassius carassius) were exposed (flow-through) to different concentrations of technical HBCD (nominal 2, 20, 200 μg L^-1) for 7 days to determine the responses of antioxidant and biotransformation enzymes. HBCD was found to be increasingly bioconcentrated in the fish livers as time proceeds. Also, the contribution of α-HBCD exhibited an enhancement from 13% in the exposure solutions to 24% in crucian carp, still much lower than in wild fishes (ca. 80%). HBCD induced activities of antioxidant enzymes in most cases, as well as increased level of lipid peroxidation. In contrast to the weak response of 7-ethoxyresorufin-O-deethylase (EROD), 7-pentoxyresorufin-O-depentylase (PROD) activity was generally induced in a time-dependent manner with peaks at day 2. Phase II enzyme Glutathione-S-transferase (GST) showed a dose-dependent induction with maximums in the 20 μg L^-1 treatment at all the four timepoints of 1, 2, 4 and 7 days. Some enzymatic responses showed good associations, indicating coordinated functions. To sum up, tHBCD exposure in the present circumstance had produced an ecological stress to crucian carp. The low levels of biotransformation and slow rates of bioisomerization suggest a possible long-term toxic effect, especially around HBCD point sources.

The antihistamine diphenhydramine is demethylated by anaerobic wastewater microorganisms

While emerging pharmaceutical contaminants are monitored in wastewater treatment and the environment, there is little information concerning their microbial metabolites. The transformation of diphenhydramine by microorganisms in anaerobic digester sludge was investigated using anaerobic cultures amended with 1 mM diphenhydramine as the sole carbon source. Complete transformation of the parent compound to a persistent metabolite occurred within 191 days. Using GC/MS analysis, the metabolite was identified as N-desmethyl diphenhydramine. Loss of the parent compound diphenhydramine followed a first order rate constant of 0.013 day^-1. There was no observed decrease in metabolite concentration even after a further 12 months of incubation, suggesting that the metabolite resists further degradation during wastewater treatment. Bacterial community diversity in the diphenhydramine transforming assay cultures showed enrichment in Comamonadaceae, Symbiobacteriaceae, Anaerolineaceae, and Prevotellaceae relative to unamended background controls. An anaerobic toxicity assay demonstrated that diphenhydramine has an inhibitory effect on both fermentative bacteria and methanogenic archaea in the wastewater community. In contrast, the metabolite N-desmethyl diphenhydramine partially suppressed methanogens but did not impact the fermenting community. To our knowledge, this is the first report of diphenhydramine metabolism by a bacterial community. The limited transformation of diphenhydramine by wastewater microorganisms indicates that N-desmethyl diphenhydramine will enter the environment along with unmetabolized diphenhydramine.

Effects of single and combined exposure of pharmaceutical drugs (carbamazepine and cetirizine) and a metal (cadmium) on the biochemical responses of R. philippinarum

In the aquatic environment, organisms are exposed to complex mixtures of contaminants which may alter the toxicity profile of each compound, compared to its toxicity alone. Pharmaceutical drugs (e.g. carbamazepine (CBZ) and cetirizine (CTZ)) and metals (e.g. cadmium (Cd)) are among those contaminants that co-occur in the environment. However, most studies concerning their toxicity towards aquatic species are based on single exposure experiments. Thus, the present study aimed to evaluate single and combined effects of Cd and CBZ or CTZ (single conditions: Cd, CTZ, CBZ; combined conditions: CTZ + Cd, CBZ + Cd) on biomarkers related to oxidative stress and energy metabolism in the edible clam Ruditapes philippinarum, by exposing the organisms for 28 days to environmentally relevant concentrations of these contaminants. The biomarkers studied were: i) the electron transport system activity, protein and glycogen contents (indicators of organisms' metabolic status and energy reserves); ii) lipid peroxidation and the ratio between reduced and oxidized glutathione (indicators of oxidative stress); iii) superoxide dismutase and catalase activities (enzymes indicators of antioxidant defence) and iv) activity of glutathione S-transferases (family of enzymes indicators of biotransformation capacity). Results obtained showed that the uptake of Cd and CBZ was not affected by the combined presence of the contaminants. However, for CTZ, the uptake was higher in the presence than in the absence of Cd. Concerning toxicity data, in general, the combined exposures (CTZ + Cd, CBZ + Cd) had lower biological effects than the contaminants alone. Nevertheless, our data showed that despite the low concentrations tested, they were enough to exert biological effects that differed between single and combined treatments, evidencing the need to conduct more co-exposure studies to increase the environmental relevance of the gathered data.

Bioconcentration and effects of hexabromocyclododecane exposure in crucian carp (Carassius auratus)

As a cycloaliphatic brominated flame retardant, hexabromocyclododecane (HBCD) has been widely used in building thermal insulation and fireproof materials. However, there is little information on the bioconcentration as well as effects with respect to HBCD exposure in the aquatic environment. To investigate the bioconcentration of HBCD in tissues (muscle and liver) and its biochemical and behavioural effects, juvenile crucian carp (Carassius auratus) were exposed to different concentrations of technical HBCD (nominal concentrations, 2, 20, 200 μg/L) for 7 days, using a flow-through exposure system. HBCD was found to concentrate in the liver and muscle with a terminal concentration of 0.60 ± 0.22 μg/g lw (lipid weight) and 0.18 ± 0.02 μg/g lw, respectively, at an environmentally-relevant concentration (2 μg/L). The total thyroxine and total triiodothyronine in the fish plasma were lowered as a result of exposure to the HBCD. Acetylcholinesterase activity in the brain was increased, while swimming activity was inhibited and shoaling inclination was enhanced after exposure to 200 μg/L HBCD. Feeding rate was suppressed in the 20 and 200 μg/L treatment groups. In summary, HBCD concentrations 10-100× higher than the current environmentally-relevant exposures induced adverse effects in the fish species tested in this study. These results suggest that increasing environmental concentrations and/or species with higher sensitivity than carp might be adversely affected by HBCD.

Effects of dissolved organic matter, feeding, and water flow on the bioconcentration of diclofenac in crucian carp (Carassius auratus)

Diclofenac (DCF), a prevalent anti-inflammatory drug, is frequently detected in aquatic organisms. However, little is known about the environmental factors that affect the bioconcentration of DCF in aquatic environments. Here, we firstly investigated the bioconcentration of DCF by crucian carp (Carassius auratus) following aqueous exposure (3.57, 14.5, and 71.8 μg L^-1) for 21 days. DCF can accumulate in crucian carp, and the maximum bioconcentration factors (BCFs) of 121 L kg^-1 in the liver, 52.3 L kg^-1 in the gills, and 46.8 L kg^-1 in the muscle were always found at 3.57 μg L^-1 after 14 days of exposure. Secondly, the influences of dissolved organic matter (DOM), feeding, and water flow on the bioconcentration of DCF were determined at the nominal concentration of 4 μg L^-1 for 14 days. The BCFs of DCF in various fish tissues decreased by 0.5-85% with the increasing DOM concentrations. Feeding also led to lower body burden of DCF in fish tissues (6-55%) with the increasing food amount. In hydrodynamic experiment, the BCFs of DCF decreased by15-57% at most in various fish tissues. Collectively, our results demonstrated the bioconcentration of DCF in fish can be influenced by various environmental factors, which should be considered in the risk assessment of pharmaceuticals.

Mode of action characterization for adverse effect of propranolol in Daphnia magna based on behavior and physiology monitoring and metabolite profiling

Studies are underway to gather information about the mode of action (MOA) of emerging pollutants that could guide practical environmental decision making. Previously, we showed that propranolol, an active pharmaceutical ingredient, had adverse effects on Daphnia magna that were similar to its pharmaceutical action. In order to characterize the mode of action of propranolol in D. magna, which is suspected to be organ-specific pharmaceutical action or baseline toxicity, we performed time-series monitoring of behavior along with heart rate measurements and nuclear magnetic resonance (NMR) based metabolite profiling. Principle component analysis (PCA) and hierarchical clustering were used to categorize the mode of action of propranolol among 5 chemicals with different modes of action. The findings showed that the mode of action of propranolol in D. magna is organ-specific and vastly different from those of narcotics, even though metabolite regulation is similar between narcotic and non-narcotic candidates. The method applied in this study seems applicable to rapid characterization of the MOA of other cardiovascular pharmaceutical ingredients.

High-throughput metabolomics enables metabolite biomarkers and metabolic mechanism discovery of fish in response to alkalinity stress

High throughput mass spectrometry (MS)-based metabolomics is a popular platform for small molecule metabolites analyses that are widely used for detecting biomarkers in the research field of environmental assessment. Crucian carp (Carassius carassius, CC) is an economically and ecologically important fish in Asia. It can adapt to extremely high alkalinity, providing us with valuable material to understand the adaptation mechanism for extreme environmental stress. However, the information on the metabolite biomarkers and metabolic mechanisms of CC exposed to alkaline stress is not entirely clear. We applied high-throughput UPLC-Q-TOF/MS combined with chemometrics to identify changes in the metabolome of CC exposed to different concentrations of alkalinity for long term effects. Metabolic differences among alkalinity-treated groups were identified by multivariate statistical analysis. Further, 7 differential metabolites were found after exposure to alkaline conditions. In total, 23 metabolic pathways of these differential metabolites were significantly affected. Alkalinity exposure resulted in widespread change in metabolic profiles in the plasma with disruptions in the phenylalanine metabolism, glycine, serine and threonine metabolism, pyruvate metabolism, tyrosine metabolism, etc. The integrated pathway analysis of the associated metabolites showed that tRNA charging, l-cysteine degradation II, superpathway of methionine degradation, l-serine degradation, tyrosine biosynthesis IV, etc. appear to be the most significantly represented functional categories. Overall, this study demonstrated that metabolic changes in CC played a role in adaptation to the highly alkaline environmental stress.

High throughput mass spectrometry (MS)-based metabolomics is a popular platform for small molecule metabolites analyses that are widely used for detecting biomarkers in the research field of environmental assessment.

Reduced anxiety is associated with the accumulation of six serotonin reuptake inhibitors in wastewater treatment effluent exposed goldfish Carassius auratus

Pharmaceuticals and personal care products (PPCPs) have been found in wastewater treatment plant (WWTP) effluents and their recipient watersheds. To assess the potential of WWTP effluents to alter fish behaviour, we caged male goldfish (Carassius auratus) for 21-days at three sites along a contamination gradient downstream from a WWTP which discharges into Cootes Paradise Marsh, on the western tip of Lake Ontario. We also included a fourth caging site as an external reference site within Lake Ontario at the Jordan Harbour Conservation Area. We then measured concentrations of PPCPs and monoamine neurotransmitters in caged goldfish plasma, and conducted behavioural assays measuring activity, startle response, and feeding. We detected fifteen different PPCPs in goldfish plasma including six serotonin reuptake inhibitors (amitriptyline, citalopram, fluoxetine/norfluoxetine, sertraline, venlafaxine, and diphenhydramine). Plasma concentrations of serotonin were significantly greater in plasma of fish caged closer to the WWTP effluent outfall site. The fish caged near and downstream of the WWTP effluent were bolder, more exploratory, and more active overall than fish caged at the reference site. Taken together, our results suggest that fish downstream of WWTPs are accumulating PPCPs at levels sufficient to alter neurotransmitter concentrations and to also impair ecologically-relevant behaviours.

Ecotoxicity of the antihistaminic drug cetirizine to Ruditapes philippinarum clams

Cetirizine (CTZ) is an antihistaminic drug present in the aquatic environment, with limited information on its toxicity to organisms inhabiting this system. This study intended to evaluate the effects of CTZ on oxidative stress and energy metabolism biomarkers in the edible clam Ruditapes philippinarum after a 28days exposure to environmentally relevant CTZ concentrations (0.0, 0.3, 3.0, 6.0 and 12.0μg/L). The results obtained showed that CTZ was accumulated by clams reaching maximum concentrations (up to ~22ng/g FW) at the highest CTZ exposure concentrations (6.0 and 12.0μg/L). The bioconcentration factor (average maximum values of ~5) decreased at 12.0μg/L reflecting a reduction in clams uptake or increase of excretion capacity at this condition. The present study revealed that, in general, clams decreased the metabolic potential after exposure to CTZ (decrease in electron transport system activity), a response that led to the maintenance of glycogen content in organisms exposed to CTZ in comparison to control values. Our findings also showed that, CTZ did not exert significant levels of oxidative injury to clams. However, comparing the control with the highest exposure concentrations (6.0 and 12.0μg/L) a significant increase of the antioxidant enzyme superoxide activity (~53 and ~44%) was observed in clams exposed to CTZ. Moreover, a tendency to increase lipid peroxidation (~14 and ~9%) and carbonyl groups on proteins (~11 and ~3%) was observed in clams exposed to CTZ (6.0 and 12.0μg/L) compared to control condition. Overall the present study suggests that toxic impacts may be induced in R. philippinarum if exposed for longer periods or higher CTZ concentrations.

Interaction of erythromycin and ketoconazole on the neurological, biochemical and behavioral responses in crucian carp

The presence of pharmaceuticals in the aquatic environment has received great attention due to their potential impacts on public health. The single, as well as the combined toxicities of erythromycin (ERY) and ketoconazole (KCZ) on the bioaccumulation, biochemical and behavioral responses, were examined in crucian carp. This study focused on the uptake of contaminants, acetylcholinesterase (AChE) activity in the brain, swimming and shoaling behavior of fish. After 14days of binary exposure, the addition of KCZ at nominal concentrations of 0.2, 2 and 20μg/L significantly increased the accumulation of ERY in the brain of the fish and the bioconcentration factor of 2.08 was 2.6-fold higher than that calculated from the ERY-alone exposure. The brain AChE activity was significantly inhibited by ERY and KCZ with a significant correlation with respect to the accumulative concentration of the contaminants. The inhibition rates of swimming activity to KCZ were increased with a corresponding increase in the exposure concentration of KCZ in the single exposure. However, this manner was altered by the combined exposure. In addition, shoaling was significantly enhanced by KCZ-alone exposure, which was significantly correlated with the swimming activity. This study indicates that the mixture of the contaminants may cause endocrine disrupting effects and behavior modification especially in fish with known ecological and evolutionary consequences.

Induction of EROD and BFCOD activities in tissues of barbel (Barbus callensis) from a water reservoir in Algeria

EROD and BFCOD activities were measured in liver and gills of barbel (Barbus callensis, a native North African species) captured at Beni Haroun lake, the most important water reservoir in Algeria. This lake receives wastewater from different origins. Thus, we assessed the level of pollution through the induction of detoxification activities in tissues of barbel, evaluating simultaneously the suitability of this species to be used as a sentinel. Fish were collected between March 2015 and January 2016 at three locations taking into account the pollution sources and accessibility. In liver, EROD and BFCOD showed the highest induction in October specially in the location of the dam that received pollutants. In gills, only EROD, but not BFCOD, activity was detected. Maximal EROD induction was noted in samples from January. Fish cell lines (RTG-2 and PLHC-1) were exposed to sediments extracts collected at Beni Haroun lake and enzyme activities (EROD and BFCOD, respectively) were measured. Sediment extracts did not induce BFCOD activity. The EROD induction observed in RTG-2 cells was in line with the results observed in fish tissues. Our results suggest that the lake is at risk from pollution and that Barbus callensis is a good sentinel species.

Bioconcentration and multi-biomarkers of organic UV filters (BM-DBM and OD-PABA) in crucian carp

Organic UV filters (OUV-Fs) are increasingly used in sunscreens and personal care products. In the present work, the bioconcentration and multi-biomarker effects of butyl methoxydibenzoylmethane (BM-DBM) and ethylhexyl dimethyl p-aminobenzoate (OD-PABA) were investigated in crucian carp (Carassius auratus). The fish were exposed to various concentrations of BM-DBM (3.88, 35.61, 181.85 and 337.15μg/L), OD-PABA (4.66, 53.83, 264.22 and 459.32μg/L) and their mixture (2.31+2.79, 23.69+26.18, 97.37+134.81 and 193.93+246.08μg/L) for 28 days. The maximal concentrations of two OUV-Fs were detected in the fish liver, followed by the brain, kidney, gill and muscle in most cases. The maximal BCF values of OD-PABA calculated in various exposure concentrations were 0.37 - 101.21 in single exposure groups and 0.11 - 31.09 in mixed exposure groups. Acetylcholinesterase (AChE) activity was significantly inhibited by BM-DBM as well as the mixtures at all of the exposure concentrations and by OD-PABA at higher concentrations (≥264.22μg/L) during 28 days of exposure. The maximal inhibition rates of AChE activity reached 64.04% for BM-DBM, 41.05% for OD-PABA and 61.50% for the mixtures at the highest concentration, which indicated that these two OUV-Fs might damage the central nervous system. Concerning oxidative stress status, BM-DBM and the mixtures significantly increased superoxide dismutase (SOD) and glutathione reductase (GR) activities and inhibited catalase (CAT) activity, while OD-PABA caused a significant increase of GR and CAT activities. AChE and GR activities seemed to be more sensitive biomarkers for BM-DBM and OD-PABA.

Pre/post-closure assessment of groundwater pharmaceutical fate in a wastewater-facility-impacted stream reach

Pharmaceutical contamination of contiguous groundwater is a substantial concern in wastewater-impacted streams, due to ubiquity in effluent, high aqueous mobility, designed bioactivity, and to effluent-driven hydraulic gradients. Wastewater treatment facility (WWTF) closures are rare environmental remediation events; offering unique insights into contaminant persistence, long-term wastewater impacts, and ecosystem recovery processes. The USGS conducted a combined pre/post-closure groundwater assessment adjacent to an effluent-impacted reach of Fourmile Creek, Ankeny, Iowa, USA. Higher surface-water concentrations, consistent surface-water to groundwater concentration gradients, and sustained groundwater detections tens of meters from the stream bank demonstrated the importance of WWTF effluent as the source of groundwater pharmaceuticals as well as the persistence of these contaminants under effluent-driven, pre-closure conditions. The number of analytes (110 total) detected in surface water decreased from 69 prior to closure down to 8 in the first post-closure sampling event approximately 30 d later, with a corresponding 2 order of magnitude decrease in the cumulative concentration of detected analytes. Post-closure cumulative concentrations of detected analytes were approximately 5 times higher in proximal groundwater than in surface water. About 40% of the 21 contaminants detected in a downstream groundwater transect immediately before WWTF closure exhibited rapid attenuation with estimated half-lives on the order of a few days; however, a comparable number exhibited no consistent attenuation during the year-long post-closure assessment. The results demonstrate the potential for effluent-impacted shallow groundwater systems to accumulate pharmaceutical contaminants and serve as long-term residual sources, further increasing the risk of adverse ecological effects in groundwater and the near-stream ecosystem.