Evaluation of Estrogenic Activity of Wastewater: Comparison Among In Vitro ERα Reporter Gene Assay, In Vivo Vitellogenin Induction, and Chemical Analysis

Microcystin-LR Induces Estrogenic Effects at Environmentally Relevant Concentration in Black-Spotted Pond Frogs (Pelophylax nigromaculatus): In Situ, In Vivo, In Vitro, and In Silico Investigations

Harmful cyanobacterial blooms are frequent and intense worldwide, creating hazards for aquatic biodiversity. The potential estrogen-like effect of Microcystin-LR (MC-LR) is a growing concern. In this study, we assessed the estrogenic potency of MC-LR in black-spotted frogs through combined field and laboratory approaches. In 13 bloom areas of Zhejiang province, China, the MC-LR concentrations in water ranged from 0.87 to 8.77 μg/L and were correlated with sex hormone profiles in frogs, suggesting possible estrogenic activity of MC-LR. Tadpoles exposed to 1 μg/L, an environmentally relevant concentration, displayed a female-biased sex ratio relative to controls. Transcriptomic results revealed that MC-LR induces numerous and complex effects on gene expression across multiple endocrine axes. In addition, exposure of male adults significantly increased the estradiol (E2)/testosterone (T) ratio by 3.5-fold relative to controls. Downregulation of genes related to male reproductive endocrine function was also identified. We also showed how MC-LR enhances the expression of specific estrogen receptor (ER) proteins, which induce estrogenic effects by activating the ER pathway and hypothalamic-pituitary-gonadal (HPG) axis. In aggregate, our results reveal multiple lines of evidence demonstrating that, for amphibians, MC-LR is an estrogenic endocrine disruptor at environmentally relevant concentrations. The data presented here support the need for a shift in the MC-LR risk assessment. While hepatoxicity has historically been the focus of MC-LR risk assessments, our data clearly demonstrate that estrogenicity is a major mode of toxicity at environmental levels and that estrogenic effects should be considered for risk assessments on MC-LR going forward.

Levonorgestrel causes feminization and dose-dependent masculinization in medaka fish (Oryzias latipes): Endocrine-disruption activity and its correlation with sex reversal

The effect of a synthetic progestin, levonorgestrel (LNG), on the sex of exposed embryos was examined in medaka fish (Oryzias latipes). The aims of this study are to clarify the dual effect of LNG on sex and the correlation with its androgenic/estrogenic potential in medaka. LNG exposure causes significant dose-dependent masculinization (0.1-100 μg/L), whereas a decrease in the masculinization ratio is observed at 100 μg/L. LNG also causes significant feminization at 1-100 μg/L, but not in a dose-dependent manner. Exposure of estrogen-responsive gene (choriogeninH-EGFP) transgenic embryos to 100 μg/L LNG produced significant fluorescent signals in hatched fry. In vitro transcriptional assays indicated that LNG at 10^-7-10^-5 M induced significant activity for estrogen receptor (ESR)2a and ESR2b, but not for ESR1. In pre-self-feeding fry at 5 days post hatching (dph), 1-100 μg/L LNG caused a significant increase in the mRNA of choriogeninH, irrespective of genetic sex. Moreover, LNG (10^-10-10^-5 M) also caused a significant increase in the transcriptional activity of androgen receptor (AR) α and ARβ in vitro, and 0.1 μg/L LNG significantly increased the mRNA levels of a testis-differentiation initiation factor, gonadal soma-derived factor (gsdf), as an androgen-upregulated and estrogen-downregulated gene, in 5 dph XX fry to levels similar to those in the control XY fry. However, 100 and 10 μg/L LNG suppressed or did not induce gsdf mRNA expression in XY and XX fry, respectively. Together, these findings show that LNG exerts estrogenic and androgenic activities in different concentration ranges, which correlate with the ratio of LNG-induced sex reversal. These results suggest for the first time, that medaka exposure to LNG can induce masculinization and feminization, based on the balance between androgenic and estrogenic activities, and the protocol applied in this study represents an alternative to the traditional animal model used to screen for endocrine-disrupting potential.

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.

Endocrine disrupting activity in sewage sludge: Screening method, microbial succession and cost-effective strategy for detoxification

Sewage sludge (SS) presents a high agronomic potential due to high concentrations of organic matter and nutrients, encouraging its recycling as a soil conditioner. However, the presence of toxic substances can preclude this use. To enable the safe disposal of this waste in agriculture, SS requires additional detoxification to decrease the environmental risks of this practice. Although some alternatives have been proposed in this sense, little attention is provided to eliminating endocrine-disrupting chemicals (EDCs). To fill this gap, this study aimed to develop effective and low-cost technology to eliminate EDCs from SS. For this, a detoxification process combining microorganisms and biostimulating agents (soil, sugarcane bagasse, and coffee grounds) was performed for 2, 4, and 6 months with aerobic and anaerobic SSs. The (anti-)estrogenic, (anti-)androgenic, retinoic-like, and dioxin-like activities of SSs samples were verified using yeast-based reporter-gene assays to prove the effectiveness of the treatments. A fractionation procedure of samples, dividing the target sample extract into several fractions according to their polarity, was conducted to decrease the matrix complexity and facilitate the identification of EDCs. A decrease in the abundance and microbial diversity of the SS samples was noted along the biostimulation with the predominance of filamentous fungal species over yeasts and gram-positive bacteria and non-fermenting rods over enterobacteria. Among the 9 EDCs quantified by LC-ESI-MS/MS, triclosan and alkylphenols presented the highest concentrations in both SS. Before detoxification, the studied SSs induced significant agonistic activity, especially at the human estrogen receptor α (hERα) and the human aryl hydrocarbon receptor (AhR). The raw anaerobic sludge also activated the androgen (hAR), retinoic acid (RARα), and retinoid X (RXRα) receptors. However, no significant endocrine-disrupting activities were observed after the SS detoxification, showing that the technology applied here efficiently eliminates receptor-mediated toxicity.

Preself-Feeding Medaka Fry Provides a Suitable Screening System for in Vivo Assessment of Thyroid Hormone-Disrupting Potential

Endocrine-disrupting chemicals are assessed based on their physiological potential and their potential associated adverse effects. However, suitable end points for detection of chemicals that interfere with the thyroid hormone (TH) system have not been established in nonmammals, with the exception of amphibian metamorphosis. The aims of the current study were to develop an in vivo screening system using preself-feeding medaka fry (Oryzias latipes) for the detection of TH-disrupting chemicals and elucidate the underlying molecular mechanism. 17α-Ethinylestradiol (EE2: <100 ng/L) did not induce mRNA expression of estrogen-responsive genes, vitellogenins (vtgs) mRNA. Meanwhile, coexposure with thyroxin (T4) induced an increase of vtg expression. TH-disrupting chemicals (thiourea (TU), perfluorooctanoic acid (PFOA), and tetrabromobisphenol A (TBBPA)) significantly suppressed EE2 (1,000 ng/L)-induced vtg1 expression, while T4 rescued their expression as well as that of thyroid hormone receptor α (tRα) and estrogen receptors (esrs). These results were supported by in silico analysis of the 5'-transcriptional regulatory region of these genes. Furthermore, the esr1 null mutant revealed that EE2-induced vtg1 expression requires mainly esr2a and esr2b in a TH-dependent manner in preself-feeding fry. Application of preself-feeding medaka fry as a screening system might help decipher the in vivo mechanisms of action of TH-disrupting molecules, while providing an alternative to the traditional animal model.

Evaluation of estrogenic and antiestrogenic activity in sludge and explanation of individual compound contributions

Mixture toxicity, including agonistic and antagonistic effects, is an unrevealed environmental problem. Estrogenic endocrine disruptors are known to cause adverse effects for aquatic biota, but causative chemicals and their contributions to the total activity in sewage sludge remain unknown. Therefore, advanced analytical methods, a yeast bioassay and mixture toxicity models were concurrently applied for the characterization of 8 selected sludges with delectable estrogenic activity (and 3 sludges with no activity as blanks) out of 25 samples from wastewater treatment plants (WWTPs). The first applied full logistic model adequately explained total activity by considering the concentrations of the monitored compounds. The results showed that the activity was primarily caused by natural estrogens in municipal WWTP sludge. Nevertheless, activity in a sample originating from a car-wash facility was dominantly caused by partial agonists - nonylphenols - and only a model enabling prediction of all dose-response curve parameters of the final mixture curve explained these results. Antiestrogenic effects were negligible, and effect-directed analysis identified the causative chemicals.

The agonistic bioanalytical equivalent concentration: A novel tool for assessing the endocrine activity of environmental mixtures

Cell-based bioassays are very sensitive and allow integrative effect screening of the whole environmental sample, which is usually composed of a mixture of agonists and antagonists. Measured toxicity is usually expressed as a bioanalytical equivalent concentration. So far, it is not possible to distinguish which part of this value is caused by the agonists and which by the antagonists. In this article, we present a simple method to analyze the dose-response curve of a mixture and to determine an agonistic bioanalytical equivalent concentration: a concentration of a reference chemical that would elicit the same effect as do only agonists in an unknown mixture. The method has been validated using several artificially prepared mixtures of agonists and competitive antagonists measured in a recombinant yeast assay. No difference was observed between the calculated equivalent concentrations and the used concentrations of the agonist in the mixture.

Insight into the mechanism of action of scoparone inhibiting egg development of Tetranychus cinnabarinus Boisduval

Investigating the mechanisms of action of natural bioactive products against pests is a vital strategy to develop novel promising biopesticides. Scoparone, isolated from Artemisia capillaris, exhibited potent oviposition inhibition activity against Tetranychus cinnabarinus (a crop-threatening mite pests with strong fecundity). To explore the underlying mechanism, the vitellogenin (Vg) protein content, and Vg gene expression of mites from three consecutive generations of G0 individuals exposed to scoparone were determined, revealing marked inhibition. This study is the first to explore the egg development defect behaviour of mite pests induced by scoparone. The egg-laying inhibition of mites by scoparone was significantly increased by 47.43% compared with that of the control when TcVg was silenced by RNA interference (RNAi), suggesting that egg-development inhibition of female T. cinnabarinus by scoparone was mediated by low Vg gene expression. Furthermore, scoparone bound to the Vg protein in vitro, and its K_d value was 218.9 μM, implying its potential function in inhibiting the egg development of mites by directly targeting the Vg protein. This study will lay the foundation for the future applications of scoparone as an agrochemical for controlling the strong egg-laying capacity mite pests in agriculture.

Effects of synthetic sex steroid hormone exposures on gonadal sex differentiation and dynamics of a male-related gene, Gonadal soma-derived factor (Gsdf) and an estrogen up-regulated gene, Choriogenine-H (ChgH) gene expression in the euryhaline Javafish medaka, Oryzias javanicus, based on genetic sexes

To clarify the basal aspects of sexual development in Javafish medaka, Oryzias javanicus (ZZ/ZW), a model marine species for ecotoxicity testing, we examined the details of gonadal sex differentiation and exogenous sex hormone-dependent sex reversals using genetic sex-linked DNA markers. Sex differences in germ cell numbers were observed at 5 days post hatching (dph), in which there was a significant increase in the germ cells of ZW. In ZW, diplotene oocytes and the ovarian cavity appeared at approximately 10, and 30 dph, respectively. In ZZ, spermatogonial proliferation was observed at approximately 20 dph. A ZZ-dominant expression of Gonadal soma-derived factor (Gsdf) mRNA was detected before hatching. The exposure of embryos to 17α-ethinylestradiol (EE2; 0.1, 1, 10 ng/mL) did not cause sex reversals in most cases. However, EE2 exposures led to significant Choriogenin-H (ChgH) mRNA expression, an estrogen up-regulated gene, in all fry; these exposures did not suppress Gsdf expression in ZZ fry. The exposure of embryos to 17α-methyltestosterone (MT; 0.1, 1, 10 ng/mL) caused sex reversals but only at low frequencies in ZW and ZZ fish. Although the 10 ng/mL MT exposure was accompanied by induction of significant Gsdf expression in ZW fry, induction of ChgH expression was also observed in several fry. Together, the present study indicates for the first time that male-dominant sexual dimorphic expression of Gsdf precedes the first morphological sex difference, i.e., the sex difference in germ cell number, and results strongly suggest that exogenous sex hormone-dependent sex reversal is not induced easily in O. javanicus.

Bioaccumulation of estrogenic hormones and UV-filters in red swamp crayfish (Procambarus clarkii)

Estrogenic hormones and organic ultraviolet-filters (UV-filters) have attracted increased attention as endocrine disrupting chemicals (EDCs) due to their potent estrogenicity and widespread occurrence in the environment. This study investigated the accumulation of three estrogenic hormones and five UV-filters in red swamp crayfish (Procambarus clarkii). Exposure experiments were conducted for 42 days with a mixture of EDCs at two environmentally-relevant design concentrations (i.e., 500 and 5000 ng L^-1). The aqueous-phase EDC concentrations decreased over time and were re-established every two days. Within 14 days of exposure, the five UV-filters were measured at 2.2 to 265 ng g^-1 (dry weight) in crayfish tail tissue. Only one estrogenic hormone, 17β-estradiol, was detected in the crayfish at 10.4-13.5 ng g^-1. No apparent changes were observed for EDC concentrations in the tail tissue over the next four weeks of exposure. The apparent bioaccumulation factors for the EDCs ranged from 23 L (kg tail tissue, dry weight)^-1 for 4-methylbenzylidene camphor to 1050 L (kg tail tissue, dry weight)^-1 for 2-ethylhexyl-4-methoxycinnamate. EDC input was stopped after 42 days, and the more hydrophobic UV-filters (i.e., octocrylene, 2-ethylhexyl-4-methoxycinnamate, homosalate) were found to be persistent throughout a 14-d elimination period. A lyticase-assisted yeast estrogen screen demonstrated that the residual estrogenic activity of water samples aligned with (or was lower than) predictions from targeted chemical analysis. These results suggest that the transformation products did not contribute significant estrogenicity, although further analysis of endocrine disruption outcomes in crayfish is recommended.

Biomonitoring the effects of urban-stream waters on the health status of pale chub (Zacco platypus): A comparative analysis of biological indexes and biomarker levels

The objective of this study was to biomonitor the effects of potential environmental pollutants in urban-stream waters, on fish health. Pale chub (Zacco platypus), a dominant species in the Korea urban stream waters, was chosen and biomonitoring indicators for the different spatial characteristics were tailored in an urban watershed. Biological responses including biotic-somatic index as well as gonadal development phase and plasma steroids levels, and the biochemical responses, ethoxyresorufin-o-deethylase (EROD) and acetylcholinesterase (AChE) activities, were measured. No significant difference was observed in the length-weight relationship between the up-stream waters and the down-stream waters. However, changes in the gonad-somatic index (GSI) levels, plasma 17β-estradiol (E2) levels, and mature oocyte frequencies in the female fish collected during the spawning season were observed in the down-stream waters at each monitoring site. Moreover, intersex condition (testis-ova) in the male fish in down-stream waters was recorded, even if it was just one fish. Although no significant difference was observed in the EROD and AChE activities between the up-stream waters and the down-stream waters, changes in the reproductive biomarker levels, including the GSI levels, plasma E2 levels, and gonadal maturation, lead to variable biomonitoring endpoints between the spatial different sites. These results imply that exposure to the down-stream waters can cause reproductive impairment in wild Z. platypus, individual variability in the biological responses further indicate the reproductive health was affected more by the down-stream waters than the up-stream waters. The finding from this study can provide the biomonitoring endpoint on the wild fish health in urban watershed that is crucial to the early risk assessment of its biological impacts. More multi-biomarkers studies reflecting the variation in the biological organization of wild fish and, therefore, the effects of urban-stream waters in the fish health are warranted.

Steroid hormones and estrogenic activity in the wastewater outfall and receiving waters of the Chascomús chained shallow lakes system (Argentina)

Natural and synthetic steroid hormones, excreted by humans and farmed animals, have been considered as important sources of environmental endocrine disruptors. A suite of estrogens, androgens and progestogens was measured in the wastewater treatment plant outfall (WWTPO) of Chascomús city (Buenos Aires province, Argentina), and receiving waters located downstream and upstream from the WWTPO, using solid phase extraction and high-performance liquid chromatography mass spectrometry. The following natural hormones were measured: 17β-estradiol (E₂), estrone (E₁), estriol (E₃), testosterone (T), 5α-dihydrotestosterone (DHT), progesterone (P), 17-hydroxyprogesterone (17OHP) and the synthetic estrogen 17α-ethinylestradiol (EE₂). Also, in order to complement the analytical method, the estrogenic activity in these surface water samples was evaluated using the in vitro transactivation bioassay that measures the estrogen receptor (ER) activity using mammalian cells. All-natural steroid hormones measured, except 17OHP, were detected in all analyzed water samples. E₃, E₁, EE₂ and DHT were the most abundant and frequently detected. Downstream of the WWTPO, the concentration levels of all compounds decreased reaching low levels at 4500 m from the WWTPO. Upstream, 1500 m from the WWTPO, six out of eight steroid hormones analyzed were detected: DHT, T, P, 17OHP, E₃ and E₂. Moreover, water samples from the WWTPO and 200 m downstream from it showed estrogenic activity exceeding that of the EC₅₀ of the E₂ standard curve. In sum, this work demonstrates the presence of sex steroid hormones and estrogenic activity, as measured by an in vitro assay, in superficial waters of the Pampas region. It also suggests the possibility of an unidentified source upstream of the wastewater outfall.

Determination and ecological risk assessment of two endocrine disruptors from River Buffalo, South Africa

4-tert-Octylphenol (4-tOP) and triclosan (TCS) are endocrine disruptors which have been detected in environmental matrices such as air, soil and water at ultra-low levels. Exposure to endocrine disruptors may account at least in part, for the global increase in the incidence of non-communicable diseases like cancers and diabetes and may also lead to an imbalance in the aquatic ecosystem. River Buffalo is an important natural resource in the Eastern Cape of South Africa serving more than half a million people. The presence of the two compounds in the river water hitherto unknown was investigated during winter seasons using solid-phase extraction and gas chromatography-mass spectrometric techniques. The sampling points differed by some physicochemical parameters. The concentration of 4-tOP ranged 0-755 ng/L, median value 88.1 ng/L while that of TCS ranged 0-1264.2 ng/L and the median value was 82.1 ng/L. Hazard quotient as an index of exposure risk varied according to daphnids ˃ fish ˃ algae for 4-tOP exposure while HQ for TCS exposure was algae > daphnids = fish showing that both compounds were capable of causing imbalance in the aquatic ecosystem. Graphical abstract.

Estrogenic activity of surface waters using zebrafish- and human-based in vitro assays: The Danube as a case-study

Most in vitro reporter gene assays used to assess estrogenic contamination are based on human estrogen receptor α (hERα) activation. However, fish bioassays can have distinct response to estrogenic chemicals and mixtures, questioning the relevance of human-based bioassays for assessing risk to this species. In this study, zebrafish liver cells stably expressing zebrafish ERβ2 (ZELHβ2) and human breast cancer cells expressing hERα (MELN) were used to quantify the estrogenic activity of 25 surface water samples of the Danube River, for which chemicals have been previously quantified. Most samples had a low estrogenic activity below 0.1 ng/L 17β-estradiol-equivalents that was more often detected by MELN cells, while ZELHβ2 response tend to be lower than predicted based on the chemicals identified. Nevertheless, both bioassays quantified well a higher estrogenic activity at two sites, which was confirmed in vivo using a transgenic zebrafish assay. The results are discussed considering the effect-based trigger values proposed for water quality monitoring.

Current issues confounding the rapid toxicological assessment of oil spills

Oil spills of varying magnitude occur every year, each presenting a unique challenge to the local ecosystem. The complex, changeable nature of oil makes standardised risk assessment difficult. Our review of the state of science regarding oil's unique complexity; biological impact of oil spills and use of rapid assessment tools, including commercial toxicity kits and bioassays, allows us to explore the current issues preventing effective, rapid risk assessment of oils. We found that despite the advantages to monitoring programmes of using well validated standardised tests, which investigate impacts across trophic levels at environmentally relevant concentrations, only a small percentage of the available tests are specialised for use within the marine environment, or validated for the assessment of crude oil toxicity. We discuss the use of rapid tests at low trophic levels in addition to relevant sublethal toxicity assays to allow the characterisation of oil, dispersant and oil and dispersant mixture toxicity. We identify novel, passive dosing techniques as a practical and reproducible means of improving the accuracy and maintenance of nominal concentrations. Future work should explore the possibility of linking this tiered testing system with ecosystem models to allow the prediction and risk assessment of the entire ecosystem.

Distribution of vitellogenin in Japanese flounder (Paralichthys olivaceus) for biomarker analysis of marine environmental estrogens

Estrogen pollution in marine environments has become a research hotspot due to its adverse effects on the reproduction of wild organisms. To early detection of estrogen pollution, this study developed two methods for detecting Japanese flounder vitellogenin (Vtg), a sensitive biomarker for environmental estrogens. Firstly, monoclonal antibodies (mAb) specific to Vtg were prepared using purified lipovitellin (Lv), a main Vtg-derived yolk protein. Anti-Lv mAb (C1F1) had the highest titer (1:256,000) and was labeled with fluorescein isothiocyanate to establish a direct immunofluorescence (DIF) method for histological detection of Vtg in tissues. Additionally, using the purified Lv and mAb, an enzyme-linked immunosorbent assay (ELISA) was developed and this assay had a detection limit of 0.75 ng/mL and a working range of 1.95-250 ng/mL. Furthermore, Vtg induction in the plasma of Japanese flounder exposed to 17β-estradiol (E₂), 17α-ethinylestradiol (EE₂), and bisphenol A (BPA) were quantified by ELISA, and Vtg induction in the liver of EE₂-exposed Japanese flounder were measured by DIF. Finally, the distribution of Vtg in Japanese flounder was detected using these two methods. The results revealed that Vtg mainly appeared in the terminal tail fin, liver, kidney, intestine, and spleen. Considering the high concentration of Vtg and easy sample collection, the terminal tail fin could be a new alternative to plasma for Vtg quantification, while kidney and liver are suitable for histological detection of Vtg.

Monitoring estrogenic activities of waste and surface waters using a novel in vivo zebrafish embryonic (EASZY) assay: Comparison with in vitro cell-based assays and determination of effect-based trigger values

This study reports the use of the recently developed EASZY assay that uses transgenic cyp19a1b-GFP zebrafish (Danio rerio) embryos to assess in vivo estrogenic activity of 33 surface (SW) and waste water (WW) samples collected across Europe that were previously well-characterized for estrogen hormones and in vitro estrogenic activity. We showed that 18 out of the 33 SW and WW samples induced estrogenic responses in the EASZY assay leading to a significant and concentration-dependent up-regulation of the ER-regulated cyp19a1b gene expression in the developing brain. The in vivo 17β-estradiol-equivalents (EEQs) were highly correlated with, both, the chemical analytical risk quotient (RQ) based on steroidal estrogen concentrations and EEQs reported from five different in vitro reporter gene assays. Regression analyses between the vitro and in vivo effect concentrations allowed us to determine an optimal cut-off value for each in vitro assay, above which in vivo responses were observed. These in vitro assay-specific effect-based trigger values (EBTs), ranging from 0.28 to 0.58 ng EEQ/L define the sensitivity and specificity of the individual in vitro assays for predicting a risk associated with substances acting through the same mode of action in water samples. Altogether, this study demonstrates the toxicological relevance of in vitro-based assessment of estrogenic activity and recommends the use of such in vitro/in vivo comparative approach to refine and validate EBTs for mechanism-based bioassays.

Systematic Review of Toxicity Removal by Advanced Wastewater Treatment Technologies via Ozonation and Activated Carbon

Upgrading wastewater treatment plants (WWTPs) with advanced technologies is one key strategy to reduce micropollutant emissions. Given the complex chemical composition of wastewater, toxicity removal is an integral parameter to assess the performance of WWTPs. Thus, the goal of this systematic review is to evaluate how effectively ozonation and activated carbon remove in vitro and in vivo toxicity. Out of 2464 publications, we extracted 46 relevant studies conducted at 22 pilot or full-scale WWTPs. We performed a quantitative and qualitative evaluation of in vitro (100 assays) and in vivo data (20 species), respectively. Data is more abundant on ozonation (573 data points) than on an activated carbon treatment (162 data points), and certain in vitro end points (especially estrogenicity) and in vivo models (e.g., daphnids) dominate. The literature shows that while a conventional treatment effectively reduces toxicity, residual effects in the effluents may represent a risk to the receiving ecosystem on the basis of effect-based trigger values. In general, an upgrade to ozonation or activated carbon treatment will significantly increase toxicity removal with similar performance. Nevertheless, ozonation generates toxic transformation products that can be removed by a post-treatment. By assessing the growing body of effect-based studies, we identify sensitive and underrepresented end points and species and provide guidance for future research.

Combined effects of environmental xeno-estrogens within multi-component mixtures: Comparison of in vitro human- and zebrafish-based estrogenicity bioassays

Some recent studies showed that in vitro bioassays based on fish or human estrogen receptor (ER) activation may have distinct responses to environmental samples, highlighting the need to better understand bioassay-specific ER response to environmental mixtures. For this purpose, we investigated a 12-compound mixture in two mixture ratios (M1 and M2) on zebrafish (zf) liver cells stably expressing zfERα (ZELHα cells) or zfERβ2 (ZELHβ2 cells) and on human ER-reporter gene (MELN) cells. The mixture included the well-known ER ligands bisphenol A (BPA) and genistein (GEN), and other compounds representatives of a freshwater background contamination. In this context, the study aimed at assessing the robustness of concentration addition (CA) model and the potential confounding influence of other chemicals by testing subgroups of ER activators, ER inhibitors or ER activators and inhibitors combined. Individual chemical testing showed a higher prevalence of ER inhibitors in zebrafish than human cells (e.g. propiconazole), and some chemicals inhibited zfER but activated hER response (e.g. benzo(a)pyrene, triphenylphosphate). The estrogenic activity of M1 and M2 was well predicted by CA in MELN cells, whereas it was significantly lower than predicted in ZELHβ2 cells, contrasting with the additive effects observed for BPA and GEN binary mixtures. When testing the subgroups of ER activators and inhibitors combined, the deviation from additivity in ZELHβ2 cells was caused by zebrafish-specific inhibiting chemicals. This study provides novel information on the ability of environmental pollutants to interfere with zfER signalling and shows that non-estrogenic chemicals can influence the response to a mixture of xeno-estrogens in a bioassay-specific manner.

Evaluation of mixture effects of endocrine active substances in wastewater using CALUX reporter-gene assays

Endocrine active substances (EAS), which are commonly used in pharmaceuticals and personal care products, are released into surface water mainly through WWTP effluents and have been shown to cause adverse effects in aquatic organisms. In wastewater, a variety of EAS with different hormonal activities is present, which can lead to additive effects or mask an endocrine activity. To investigate hormonal combination effects, with a focus on estrogen and androgen-modulators, influent samples from municipal and hospital wastewater treatmenr plants were spiked with 17α-ethinylestradiol, toremifene, 17α-methyltestosterone and bicalutamide and analyzed using in vitro reporter gene CALUX assays. All wastewaters caused endocrine activities in human cells, which were modified by adding one or several endocrine active substances. As expected, estrogenic activity was reduced in presence of the anti-estrogenic toremifene and androgenic activity decreased with the anti-androgen bicalutamide. In general, substance addition caused a similar trend in altered endocrine activities; however, their intensities differed between the wastewaters. Our results indicate that masking effects, leading to a suppressed biological signal, are of significant importance in the assessment of complex water samples, and combination effects rather than single substances determine the final biological effect. This emphasizes the need of effect-based tools in the assessment of water samples.

Trace organic contaminant removal in six full-scale integrated fixed-film activated sludge (IFAS) systems treating municipal wastewater

Trace organic contaminants (TrOCs) often pass through conventional activated sludge wastewater treatment plants (CAS-WWTPs) and are discharged into surface waters, where they can threaten aquatic ecosystems and human health, largely due to the hormone disrupting effects of certain TrOCs. The integrated fixed-film activated sludge (IFAS) process is a cost-effective means of upgrading CAS-WWTPs by adding free-floating carrier media, which promotes biofilm formation in the well-mixed suspended growth reactors, providing a potential niche for slow-growing microorganisms. Although IFAS upgrades are typically aimed at enhancing nutrient removal, limited bench- and pilot-scale data indicate that TrOC removal may also be improved. However, only limited reports which focus on a small number of compounds in individual full-scale IFAS-WWTPs have been published to date, and no data is available regarding the removal of estrogenic activity in full-scale IFAS-WWTPs. In this study, six full-scale IFAS-WWTPs were surveyed to quantify TrOC and estrogenic activity removal. Twenty-four hour composite samples of secondary influent and effluent (pre-disinfection) were analyzed for total suspended solids (TSS), chemical oxygen demand (COD), ammonia, total nitrogen (TN), total phosphorus (TP), estrogenic activity, and 98 TrOCs. The biomass distribution between the suspended growth phase (i.e. mixed liquor) and IFAS media was also assessed. All IFAS-WWTPs performed well in terms of TSS, COD, and ammonia removal. TN removal varied in accordance with nitrate removal. Total solids per liter of wetted reactor volume ranged from 2.5 to 7.6 g, with 40-60% attached to media. TrOCs with no detection (17) and those with high median removal (23, ≥90% average removal) were observed. Other TrOCs had lower and more variable removal efficiencies. Qualitative comparison with CAS literature shows potentially higher IFAS removal efficiencies for a number of compounds including several which have been previously indicated in bench- or pilot-scale studies (atenolol, diclofenac, gemfibrozil, DEET, 4-nonylphenol, and 4-tert-octylphenol), as well as the chlorinated flame retardants TCIPP and TDCIPP. Effluent estrogenic activity was found to be similar to that reported for full-scale CAS-WWTPs. These results provide the first survey of multiple full-scale IFAS-WWTPs employing mobile plastic carrier media in terms of basic chemical endpoints (removal of ammonia, TN, TP, and COD), the distribution of solids within the systems, and the removal of TrOCs and estrogenic activity.

Impact of Soil Filtration on Metals, Nutrients, and Estrogenic Activity of Reclaimed Water

This study examined the impact of soil filtration on water quality for reclaimed water from two municipal wastewater treatment processes with two soils (forest and farm). Soils were watered for 16 wk. Nutrients (NO-N, NH-N, and PO), electrical conductivity, hardness, pH, total metals, and estrogenic activity in source and effluents were measured. Results were evaluated in reference to current regulations in Washington State. Both reclaimed waters met standards for unrestricted agricultural use but did not meet current state regulations for ecological use. Metal concentrations in reclaimed waters were generally similar to the control (tap water). Both source and soil filtered water met Washington State stream water criteria for chronic exposure for As but exceeded groundwater standards. Concentrations of Cd, Pb, Ag, and Zn in the effluents were similar or slightly elevated to reclaimed source water for both soils and water types. Soil filtration improved water quality to levels within Washington State regulatory limits for ecological use for Cd, Cu, and Zn but decreased water quality for Pb for both soil and reclaimed water types. Phosphate concentrations were reduced by soil filtration, but NO concentrations were increased for both soils and all water types above source water concentrations. The estrogenic activity of the sand-filtered water decreased to near detection limits in the forest soil and by >200% in the farm soil. The degradation in water quality (increased NO, As, and Mn) after soil filtration observed in this study would likely occur with any water type, including rainwater.

Quantification of Pharmaceutical Related Biological Activity in Effluents from Wastewater Treatment Plants in UK and Japan

While pharmaceuticals are now routinely detected in aquatic environments, we know little of the biological activity their presence might provoke. It is estimated that nearly 40% of all marketed pharmaceuticals are G protein-coupled receptors (GPCRs) acting pharmaceuticals. Here, we applied an in-vitro assay, called the TGFα shedding assay, to measure the biological activities of GPCRs-acting pharmaceuticals present in effluents from municipal wastewater treatment plants in the United Kingdom (UK) and Japan from 2014 to 2016. The results indicated that compounds were present in the wastewater with antagonistic activities against angiotensin (AT1), dopamine (D2), adrenergic (β1), acetylcholine (M1), and histamine (H1) receptors in both countries. The most consistent and powerful antagonistic activity was against the H1, D2, and AT1 receptors at up to microgram-antagonist-equivalent quantity/L. Chemical analysis of the same UK samples was also conducted in parallel. Comparing the results of the bioassay with the chemical analysis indicated (1) the existence of other D2 or M1 receptor antagonists besides sulpiride (D2 antagonist) or pirenzepine (M1 antagonist) in wastewater and (2) that there might be a mixture effect between agonist and antagonistic activities against β1 receptor. GPCR-acting pharmaceuticals should be paid more attention in the environmental monitoring and toxicity testing in future studies.

Extended anaerobic conditions in the biological wastewater treatment: Higher reduction of toxicity compared to target organic micropollutants

Extended anaerobic conditions during biological wastewater treatment may enhance the biodegradation of micropollutants. To explore this, we combined iron-reducing or substrate-limited anaerobic conditions and aerobic pilot-scale reactors directly at a wastewater treatment plant. To investigate the detoxification by these processes, we applied two in vitro bioassays for baseline toxicity (Microtox) and reactive toxicity (AREc32) as well as in vivo bioassays with aquatic model species in two laboratory experiments (Desmodesmus subspicatus, Daphnia magna) and two on-site, flow-through experiments (Potamopyrgus antipodarum, Lumbriculus variegatus). Moreover, we analyzed 31 commonly occurring micropollutants and 10 metabolites. The baseline toxicity of raw wastewater was effectively removed in full-scale and reactor scale activated sludge treatment (>85%), while the oxidative stress response was only partially removed (>61%). A combination of an anaerobic pre-treatment under iron reducing conditions and an aerobic nitrification significantly further reduced the residual in vitro toxicities by 46-60% and outperformed the second combination consisting of an aerobic pre-treatment and an anaerobic post-treatment under substrate-limiting conditions (27-43%). Exposure to effluents of the activated sludge treatment did not induce adverse in vivo effects in aquatic invertebrates. Accordingly, no further improvement in water quality could be observed. Compared to that, the removal of persistent micropollutants was increased. However, this observation was restricted to a limited number of compounds and the removal of the sum concentration of all target micropollutants was relative low (14-17%). In conclusion, combinations of strictly anaerobic and aerobic processes significantly enhanced the removal of specific and non-specific in vitro toxicities. Thus, an optimization of biological wastewater treatment can lead to a substantially improved detoxification. These otherwise hidden capacities of a treatment technology can only be uncovered by a complementary biological analysis.

Occurrence and In Vitro Bioactivity of Estrogen, Androgen, and Glucocorticoid Compounds in a Nationwide Screen of United States Stream Waters

In vitro bioassays are sensitive, effect-based tools used to quantitatively screen for chemicals with nuclear receptor activity in environmental samples. We measured in vitro estrogen (ER), androgen (AR), and glucocorticoid receptor (GR) activity, along with a broad suite of chemical analytes, in streamwater from 35 well-characterized sites (3 reference and 32 impacted) across 24 states and Puerto Rico. ER agonism was the most frequently detected with nearly all sites (34/35) displaying activity (range, 0.054-116 ng E2Eq L-1). There was a strong linear relationship (r2 = 0.917) between in vitro ER activity and concentrations of steroidal estrogens after correcting for the in vitro potency of each compound. AR agonism was detected in 5/35 samples (range, 1.6-4.8 ng DHTEq L-1) but concentrations of androgenic compounds were largely unable to account for the in vitro activity. Similarly, GR agonism was detected in 9/35 samples (range, 6.0-43 ng DexEq L-1); however, none of the recognized GR-active compounds on the target-chemical analyte list were detected. The utility of in vitro assays in water quality monitoring was evident from both the quantitative agreement between ER activity and estrogen concentrations, as well as the detection of AR and GR activity for which there were limited or no corresponding target-chemical detections to explain the bioactivity. Incorporation of in vitro bioassays as complements to chemical analyses in standard water quality monitoring efforts would allow for more complete assessment of the chemical mixtures present in many surface waters.

Advancing Biological Wastewater Treatment: Extended Anaerobic Conditions Enhance the Removal of Endocrine and Dioxin-like Activities

Conventional activated sludge treatment of wastewater does not completely remove micropollutants. Here, extending anaerobic conditions may enhance biodegradation. To explore this, we combined iron-reducing or substrate-limiting and aerobic pilot-scale reactors directly at a wastewater treatment plant. To assess the removal of endocrine disrupting chemicals (EDCs) as group of micropollutants that adversely affects wildlife, we applied a bioanalytical approach. We used in vitro bioassays covering seven receptor-mediated mechanisms of action, including (anti)androgenicity, (anti)estrogenicity, retinoid-like, and dioxin-like activity. Untreated wastewater induced antiandrogenic, estrogenic, antiestrogenic, and retinoid-like activity. Full-scale as well as reactor-scale activated sludge treatment effectively removes the observed effects. Nevertheless, high antiandrogenic and minor dioxin-like and estrogenic effects persisted in the treated effluent that may still be environmentally relevant. The anaerobic post-treatment under substrate-limiting conditions resulted in an additional removal of endocrine activities by 17-40%. The anaerobic pre-treatment under iron-reducing conditions significantly enhanced the removal of the residual effects by 40-75%. In conclusion, this study demonstrates that a further optimization of biological wastewater treatment is possible. Here, implementing iron-reducing anaerobic conditions preceding aerobic treatment appears promising to improve the removal of receptor-mediated toxicity.

Zebrafish-based reporter gene assays reveal different estrogenic activities in river waters compared to a conventional human-derived assay

Endocrine disrupting chemicals (EDCs) act on the endocrine system through multiple mechanisms of action, among them interaction with estrogen receptors (ERs) is a well-identified key event in the initiation of adverse outcomes. As the most commonly used estrogen screening assays are either yeast- or human-cell based systems, the question of their (eco)toxicological relevance when assessing risks for aquatic species can be raised. The present study addresses the use of zebrafish (zf) derived reporter gene assays, both in vitro (i.e. zf liver cell lines stably expressing zfERα, zfERβ1 and zfERβ2 subtypes) and in vivo (i.e. transgenic cyp19a1b-GFP zf embryos), to assess estrogenic contaminants in river waters. By investigating 20 French river sites using passive sampling, high frequencies of in vitro zfER-mediated activities in water extracts were measured. Among the different in vitro assays, zfERβ2 assay was the most sensitive and responsive one, enabling the detection of active compounds at all investigated sites. In addition, comparison with a conventional human-based in vitro assay highlighted sites that were able to active zfERs but not human ER, suggesting the occurrence of zf-specific ER ligands. Furthermore, a significant in vivo estrogenic activity was detected at the most active sites in vitro, with a good accordance between estradiol equivalent (E2-EQ) concentrations derived from both in vitro and in vivo assays. Overall, this study shows the relevance and usefulness of such novel zebrafish-based assays as screening tools to monitor estrogenic activities in complex mixtures such as water extracts. It also supports their preferred use compared to human-based assays to assess the potential risks caused by endocrine disruptive chemicals for aquatic species such as fish.

Effect-directed analysis supporting monitoring of aquatic environments--An in-depth overview

Aquatic environments are often contaminated with complex mixtures of chemicals that may pose a risk to ecosystems and human health. This contamination cannot be addressed with target analysis alone but tools are required to reduce this complexity and identify those chemicals that might cause adverse effects. Effect-directed analysis (EDA) is designed to meet this challenge and faces increasing interest in water and sediment quality monitoring. Thus, the present paper summarizes current experience with the EDA approach and the tools required, and provides practical advice on their application. The paper highlights the need for proper problem formulation and gives general advice for study design. As the EDA approach is directed by toxicity, basic principles for the selection of bioassays are given as well as a comprehensive compilation of appropriate assays, including their strengths and weaknesses. A specific focus is given to strategies for sampling, extraction and bioassay dosing since they strongly impact prioritization of toxicants in EDA. Reduction of sample complexity mainly relies on fractionation procedures, which are discussed in this paper, including quality assurance and quality control. Automated combinations of fractionation, biotesting and chemical analysis using so-called hyphenated tools can enhance the throughput and might reduce the risk of artifacts in laboratory work. The key to determining the chemical structures causing effects is analytical toxicant identification. The latest approaches, tools, software and databases for target-, suspect and non-target screening as well as unknown identification are discussed together with analytical and toxicological confirmation approaches. A better understanding of optimal use and combination of EDA tools will help to design efficient and successful toxicant identification studies in the context of quality monitoring in multiply stressed environments.

Estrogenic activity in Finnish municipal wastewater effluents

Effluents from wastewater treatment plants (WWTPs) are a major source of estrogenic compounds to the aquatic environment. In the present work, estrogenic activities of effluents from eight municipal WWTPs in Finland were studied. The main objectives of the study were to quantify the concentrations of selected estrogenic compounds, to evaluate their contribution to estrogenic potency and to test the feasibility of the commercial bioassays for wastewater analysis. The effluent samples were analyzed by two in vitro tests, i.e. ERα-CALUX(®) and ELISA-E2, and by liquid chromatography mass spectrometry for six estrogenic compounds: estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), 17α-estradiol and bisphenol A (BPA). Estrogenic effects were found in all of the effluent samples with both of the bioassays. The concentrations measured with ELISA-E2 (8.6-61.6 ng/L) were clearly higher but exhibited a similar pattern than those with chemical analysis (E2 <limit of quantification - 6.8 ng/L) and ERα-CALUX(®) (0.8-29.7 ng E2 EEQ/L). Due to the concentrations under limit of quantification, the evaluation of the chemical contribution to estrogenic potency was possible only for E1 and BPA, which contributed less than 10% to the observed effects, except in one sample with a high BPA contribution (17%). The contribution of E2 was significant in two samples where it was detected (28% and 67%). The results demonstrated that more comprehensive information on potential estrogenic activity of wastewater effluents can be achieved by using in vitro biotests in addition to chemical analysis and their use would be beneficial in monitoring and screening purposes.