What level of estrogenic activity determined by in vitro assays in municipal waste waters can be considered as safe?

Coastal wastewater treatment plants as a source of endocrine disrupting micropollutants: a case study of Lithuania in the Baltic Sea

In temperate coastal areas, the resident population often increases during holidays. As a result, this can lead to higher wastewater production and release of pollutants. The connection between micropollutants such as plasticizers and hormones with the changing resident population along the Baltic Sea coast has yet to be thoroughly studied. Therefore, we have monitored the wastewater quality and specific micropollutants before and after treatment at wastewater treatment plants (WWTPs) at small and large seaside resorts. The findings indicate a strong link between tourism indicators and wastewater production during the summer months. The rise in different micropollutants, specifically plasticizers, during the summer demonstrates a link with tourism activity. Furthermore, we have identified a non-linear association between the tourism indicators and the total estrogenic equivalent (EEQ). Overall, this research particularly emphasizes the growing importance of wastewater quality in terms of conventional nutrient pollution and various micropollutants.

A critical review on quantitative evaluation of aqueous toxicity in water quality assessment

Conventional chemical techniques have inherent limitations in detecting unknown chemical substances in water. As a result, effect-based methods have emerged as a viable alternative to overcome these limitations. These methods provide more accurate and intuitive evaluations of the toxic effects of water. While numerous studies have been conducted, only a few have been applied to national water quality monitoring. Therefore, it is crucial to develop toxicity evaluation methods and establish thresholds based on quantifying toxicity. This article provides an overview of the development and application of bioanalytical tools, including in vitro and in vivo bioassays. The available methods for quantifying toxicity are then summarized. These methods include aquatic life criteria for assessing the toxicity of a single compound, comprehensive wastewater toxicity testing for all contaminants in a water sample (toxicity units, whole effluent toxicity, the potential ecotoxic effects probe, the potential toxicology method, and the lowest ineffective dilution), methods based on mechanisms and relative toxicity ratios for substances with the same mode of action (the toxicity equivalency factors, toxic equivalents, bioanalytical equivalents), and effect-based trigger values for micropollutants. The article also highlights the advantages and disadvantages of each method. Finally, it proposes potential areas for applying toxicity quantification methods and offers insights into future research directions. This review emphasizes the significance of enhancing the evaluation methods for assessing aqueous toxicity in water quality assessment.

Potential risk of estrogenic compounds produced by water blooms to aquatic environment

Some freshwater phytoplankton species have been suggested to produce estrogenic compounds in concentrations which could cause adverse effects to aquatic biota, while other studies showed no estrogenic effects after exposure to phytoplankton extracts or pointed out possible sources of the overestimation of the estrogenic activity. This study aimed to clarify these research inconsistencies by investigating estrogenicity of biomass extracts from both environmental freshwater blooms and laboratory cyanobacterial and algae cultures by in vitro reporter bioassay. Biomasses of 8 cyanobacterial and 3 algal species from 7 taxonomic orders were extracted and tested. Next to this, samples of environmental water blooms collected from 8 independent water bodies dominated by phytoplankton species previously assessed as laboratory cultures were tested. The results showed undetectable or low estrogenicity of both freshwater blooms and laboratory cultures with E2 equivalent concentration (EEQ) in a range from LOQ up to 4.5 ng EEQ/g of dry mass. Moreover, the co-exposure of biomass extracts with environmentally relevant concentration of model estrogen (steroid hormone 17β-estradiol; E2), commonly occurring in surface waters, showed simple additive interaction. However, some of the biomass extracts elicited partially anti-estrogenic effects in co-exposure with higher E2 concentration. In conclusion, our study documents undetectable or relatively low estrogenic potential of biomass extracts from both environmental freshwater blooms and studied laboratory cultured cyanobacterial and algae species. Nevertheless, in case of very high-density water blooms, even this low estrogenicity (detected for two cyanobacterial species) could lead to EEQ content in biomass reaching effect-based trigger values indicating potential risk, if recalculated per water volume at field sites. However, these levels would not occur in water under realistic environmental scenarios and the potential estrogenic effects would be most probably minor compared to other toxic effects caused by massive freshwater blooms of such high densities.

Bioanalytical and chemical characterization of organic micropollutant mixtures in long-term exposed passive samplers from the Joint Danube Survey 4: Setting a baseline for water quality monitoring

Monitoring methodologies reflecting the long-term quality and contamination of surface waters are needed to obtain a representative picture of pollution and identify risk drivers. This study sets a baseline for characterizing chemical pollution in the Danube River using an innovative approach, combining continuous three-months use of passive sampling technology with comprehensive chemical (747 chemicals) and bioanalytical (seven in vitro bioassays) assessment during the Joint Danube Survey (JDS4). This is one of the world's largest investigative surface-water monitoring efforts in the longest river in the European Union, which water after riverbank filtration is broadly used for drinking water production. Two types of passive samplers, silicone rubber (SR) sheets for hydrophobic compounds and AttractSPETM HLB disks for hydrophilic compounds, were deployed at nine sites for approximately 100 days. The Danube River pollution was dominated by industrial compounds in SR samplers and by industrial compounds together with pharmaceuticals and personal care products in HLB samplers. Comparison of the Estimated Environmental Concentrations with Predicted No-Effect Concentrations revealed that at the studied sites, at least one (SR) and 4-7 (HLB) compound(s) exceeded the risk quotient of 1. We also detected AhR-mediated activity, oxidative stress response, peroxisome proliferator-activated receptor gamma-mediated activity, estrogenic, androgenic, and anti-androgenic activities using in vitro bioassays. A significant portion of the AhR-mediated and estrogenic activities could be explained by detected analytes at several sites, while for the other bioassays and other sites, much of the activity remained unexplained. The effect-based trigger values for estrogenic and anti-androgenic activities were exceeded at some sites. The identified drivers of mixture in vitro effects deserve further attention in ecotoxicological and environmental pollution research. This novel approach using long-term passive sampling provides a representative benchmark of pollution and effect potentials of chemical mixtures for future water quality monitoring of the Danube River and other large water bodies.

Comparison and quantification of estrogen receptor-mediated responsiveness to endocrine disruptors in bivalves by using complementary model and a novel yeast assay approach

Endocrine disrupting chemicals (EDCs) in estuaries and coastal habitats have been widely detected over the world and caused global concern. Bivalves have been shown to be vulnerable to endocrine disruption. However, estrogen receptors (ERs) sensitivity to steroids and EDCs has long been considered to be restricted to vertebrates. In the present study, a computational simulation docking model was applied to qualitatively predict the binding behavior of two bivalve ERs to estradiol and compared the docking activity with zebra fish ERa. A novel reconstituted yeast system was constructed by using transcriptional activator GAL-4 consists of ER-expressing plasmid and ERE (estrogen responsive element)-containing plasmid. The assays showed that bivalve ER specifically activate transcription in response to tested steroids and EDCs, but the activation ability is weaker compared to zebra fish ERa. The results corroborate the presence of an active ER in bivalve molluscs and provide a promising tool for screening of marine environmental pollutants active in disturbing ERs of bivalves, as well as understanding the underlying mechanism across taxonomic groups and phyla.

Interferences in the yeast estrogen screen (YES) assay for evaluation of estrogenicity in environmental samples, chemical mixtures, and individual substances

The Yeast Estrogen Screen (YES) has a specific mechanism of action that allows for the analysis of estrogenic EDC at low concentrations, and it has been broadly used to estimate the estrogenic potential of environmental samples. However, the experimental parameters of this assay still demand an investigation, such as cell density, incubation time, wavelength on the experimental outcome, cytotoxicity, and estrogenic activity adsorbed on suspended solids. We studied these interferences and applied the assay to single substances, mixtures, and environmental matrices from different sources. The increase in cell density amplifies the assay sensitivity only to a limited extent, while the reduction in incubation time decreased assay sensitivity - although it was not significant for surface water, no differences were observed between estradiol-equivalents derived of 48 h and 72 h measurements. The particulate phase was of utmost importance for the total estrogenic activity of the landfill leachate and surface water. Surface waters, landfill leachates and sediments also showed antiestrogenic activity and the integration of both estrogenic and antiestrogenic endpoints provided deeper insights into the potential risk associated with EDC. This study elucidated experimental interferences that may arise during the implementation and use of this assay, bringing more understanding to experimental parameters during the application of the assay for estrogenicity screening.

A Novel Estrone Degradation Gene Cluster and Catabolic Mechanism in Microbacterium oxydans ML-6

Global-scale estrone (E1) contamination of soil and aquatic environments results from the widespread use of animal manure as fertilizer, threatening both human health and environmental security. A detailed understanding of the degradation of E1 by microorganisms and the associated catabolic mechanism remains a key challenge for the bioremediation of E1-contaminated soil. Here, Microbacterium oxydans ML-6, isolated from estrogen-contaminated soil, was shown to efficiently degrade E1. A complete catabolic pathway for E1 was proposed via liquid chromatography-tandem mass spectrometry (LC-MS/MS), genome sequencing, transcriptomic analysis, and quantitative reverse transcription-PCR (qRT-PCR). In particular, a novel gene cluster (moc) associated with E1 catabolism was predicted. The combination of heterologous expression, gene knockout, and complementation experiments demonstrated that the 3-hydroxybenzoate 4-monooxygenase (MocA; a single-component flavoprotein monooxygenase) encoded by the mocA gene was responsible for the initial hydroxylation of E1. Furthermore, to demonstrate the detoxification of E1 by strain ML-6, phytotoxicity tests were performed. Overall, our findings provide new insight into the molecular mechanism underlying the diversity of E1 catabolism in microorganisms and suggest that M. oxydans ML-6 and its enzymes have potential applications in E1 bioremediation to reduce or eliminate E1-related environmental pollution. IMPORTANCE Steroidal estrogens (SEs) are mainly produced by animals, while bacteria are major consumers of SEs in the biosphere. However, the understanding of the gene clusters that participate in E1 degradation is still limited, and the enzymes involved in the biodegradation of E1 have not been well characterized. The present study reports that M. oxydans ML-6 has effective SE degradation capacity, which facilitates the development of strain ML-6 as a broad-spectrum biocatalyst for the production of certain desired compounds. A novel gene cluster (moc) associated with E1 catabolism was predicted. The 3-hydroxybenzoate 4-monooxygenase (MocA; a single-component flavoprotein monooxygenase) identified in the moc cluster was found to be necessary and specific for the initial hydroxylation of E1 to generate 4-OHE1, providing new insight into the biological role of flavoprotein monooxygenase.

Ecological risk assessment associated with five endocrine-disrupting compounds in wastewater treatment plants of Northeast Mexico

The ecological risk associated with five endocrine-disrupting compounds (EDCs) was studied in four wastewater treatment plants (WWTPs) in Monterrey, Mexico. The EDCs, 17β-estradiol (E2), 17α-ethinylestradiol (EE2), bisphenol A (BPA), 4-nonylphenol (4NP), and 4-tert-octylphenol (4TOP) were determined by SPE/GC-MS method, where EE2 and 4TOP were the most abundant in effluents at levels from 1.6 - 26.8 ng/L (EE2) and < LOD - 5.0 ng/L (4TOP), which corroborate that the wastewater discharges represent critical sources of EDCs to the aquatic environments. In this study, the potential risk associated with selected EDCs was assessed through the risk quotients (RQs) and by estimating the estrogenic activity (expressed as EEQ). This study also constitutes the first approach for the ecological risk assessment in effluents of WWTPs in Northeast Mexico. The results demonstrated that the effluents of the WWTPs represent a high risk for the organisms living in the receiving water bodies because the residual estrogens effect E2 and EE2 with RQ values up to 49.1 and 1165.2. EEQ values between 6.3 and 24.6 ngEE2/L were considered the most hazardous compounds among the target EDCs, capable of causing some alterations in the endocrine system of aquatic and terrestrial organisms due to chronic exposition.

Effect-Based Trigger Values Are Essential for the Uptake of Effect-Based Methods in Water Safety Planning

Effect-based methods (EBMs) using in vitro bioassays and well plate-based in vivo assays are recommended for water quality monitoring because they can capture the mixture effects of the many chemicals present in water. Many in vitro bioassays are highly sensitive, so an effect in a bioassay does not necessarily indicate poor chemical water quality. Consequently, effect-based trigger values (EBTs) have been introduced to differentiate between acceptable and unacceptable chemical water quality and are required for the wider acceptance of EBMs by the water sector and regulatory bodies. These EBTs have been derived for both drinking water and surface water to protect human and ecological health, respectively, and are available for assays indicative of specific receptor-mediated effects, as well as assays indicative of adaptive stress responses, apical effects, and receptor-mediated effects triggered by many chemicals. An overview of currently available EBTs is provided, and a simple approach is proposed to predict interim EBTs for assays currently without an EBT based on the effect concentration of the assay reference compound. There was good agreement between EBTs predicted using this simplistic approach and EBTs from the literature derived using more robust methods. Finally, an interpretation framework that outlines the steps to take if the effect of a sample exceeds the EBT was developed to help facilitate the uptake of EBMs in routine water quality monitoring and water safety planning for drinking water production. Environ Toxicol Chem 2023;42:714-726. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Comparative cytotoxicity, endocrine-disrupting effects, oxidative stress of halophenolic disinfection byproducts and the underlying molecular mechanisms revealed by transcriptome analysis

Halophenolic disinfection byproducts (DBPs) are a class of emerging pollutants whose adverse effects on human cells and the underlying molecular mechanisms still need further exploration. In this study, we found that when halophenolic DBPs were substituted with the same halogen, the more substitution sites, the more cytotoxic, while when they were substituted at the same sites, the most toxic chemical was iodophenols, followed by bromophenols and chlorophenols. In addition, several of them exerted significant endocrine-disrupting effects at sublethal concentrations. 2,4,6-triiodophenol (TIP) and 2,4-dichlorophenol (2,4-DCP) showed the highest estradiol equivalent factor (EEF) of 4.41 × 10^-8 and flutamide equivalent factor (FEF) of 0.4, respectively. Furthermore, all of the halophenolic DBPs except for 2-chlorophenol (2-CP) and 2-bromophenol (2-BP) significantly increased the levels of reactive oxygen species (ROS) or 8-hydroxydeoxyguanosine (8-OHdG) in HepG2 cells. The lowest cytotoxicity and unchanged ROS and 8-OHdG levels after 2-CP exposure may result from the activation of the transporters of the adenosine triphosphate (ATP) binding cassette in cells. Transcriptome analysis revealed distinct grouping patterns of 2-CP, 2,6-dibromophenol (2,6-DBP), and TIP at the concentrations of EC₂₀, and the top differentially expressed genes (DEGs) were involved in the antioxidant-, immune-, and endocrine-associated systems. The weighted gene correlation network analysis well connected the phenotypes (EC₅₀, EEF, FEF, ROS, 8-OHdG, and ABC transporters) with the DEGs and revealed that the MAPK signaling pathway played a vital role in regulating the biological response after exposure to halophenolic DBPs. This study provides deep insights into the underlying mechanisms of the toxic effects induced by halophenolic DBPs.

Estrogenic activity response to best management practice implementation in agricultural watersheds in the Chesapeake Bay watershed

Best management practices (BMPs) have been predominantly used throughout the Chesapeake Bay watershed (CBW) to reduce nutrients and sediments entering streams, rivers, and the bay. These practices have been successful in reducing loads entering the estuary and have shown the potential to reduce other contaminants (pesticides, hormonally active compounds, pathogens) in localized studies and modeled load estimates. However, further understanding of relationships between BMPs and non-nutrient contaminant reductions at regional scales using sampled data would be beneficial. Total estrogenic activity was measured in surface water samples collected over a decade (2008-2018) in 211 undeveloped NHDPlus V2.1 watersheds within the CBW. Bayesian hierarchical modeling between total estrogenic activity and landscape predictors including landcover, runoff, BMP intensity, and a BMP*agriculture intensity interaction term indicates a 96% posterior probability that BMP intensity on agricultural land is reducing total estrogenic activity. Additionally, watersheds with high agriculture and low BMPs had a 49% posterior probability of exceeding an effects-based threshold in aquatic organisms of 1 ng/L but only a 1% posterior probability of exceeding this threshold in high-agriculture, high-BMP watersheds.

Estrogenic and retinoid-like activity in stagnant waters with mass occurrence of water blooms

Stagnant freshwaters can be affected by anthropogenic pollution and eutrophication that leads to massive growth of cyanobacteria and microalgae forming complex water blooms. These can produce various types of bioactive compounds, some of which may cause embryotoxicity, teratogenicity, endocrine disruption and impair animal or human health. This study focused on potential co-occurrence of estrogenic and retinoid-like activities in diverse stagnant freshwaters affected by phytoplankton blooms with varying taxonomic composition. Samples of phytoplankton bloom biomass and its surrounding water were collected from 17 independent stagnant water bodies in the Czech Republic and Hungary. Total estrogenic equivalents (EEQ) of the most potent samples reached up to 4.9 ng·g^-1 dry mass (dm) of biomass extract and 2.99 ng·L^-1 in surrounding water. Retinoic acid equivalent (REQ) measured by in vitro assay reached up to 3043 ng·g^-1 dm in phytoplankton biomass and 1202 ng·L^-1in surrounding water. Retinoid-like and estrogenic activities at some sites exceeded their PNEC and effect-based trigger values, respectively. The observed effects were not associated with any particular species of cyanobacteria or algae dominating the water blooms nor related to phytoplankton density. We found that taxonomically diverse phytoplankton communities can produce and release retinoid-like compounds to surrounding water, while estrogenic potency is likely related to estrogens of anthropogenic origin adsorbed to phytoplankton biomass. Retinoids occurring in water blooms are ubiquitous signalling molecules, which can affect development and neurogenesis. Selected water bloom samples (both water and biomass extracts) with retinoid-like activity caused effects on neurodifferentiation in vitro corresponding to those of equivalent all-trans-retinoic acid concentrations. Co-occurrence of estrogenic and retinoid-like activities in stagnant water bodies as well as the potential of compounds produced by water blooms to interfere with neural differentiation should be considered in the assessment of risks associated with water blooms, which can comprise complex mixtures of natural and anthropogenic bioactive compounds.

Review of ecologically relevant in vitro bioassays to supplement current in vivo tests for whole effluent toxicity testing - Part 1: Apical endpoints

Whole effluent toxicity (WET) testing is commonly used to ensure that wastewater discharges do not pose an unacceptable risk to receiving environments. Traditional WET testing involves exposing animals to (waste)water samples to assess four major ecologically relevant apical endpoints: mortality, growth, development, and reproduction. Recently, with the widespread implementation of the 3Rs to replace, reduce and refine the use of animals in research and testing, there has been a global shift away from in vivo testing towards in vitro alternatives. However, prior to the inclusion of in vitro bioassays in regulatory frameworks, it is critical to establish their ecological relevance and technical suitability. This is part 1 of a two-part review that aims to identify in vitro bioassays that can be used in WET testing and relate them to ecologically relevant endpoints through toxicity pathways, providing the reader with a high-level overview of current capabilities. Part 1 of this review focuses on four apical endpoints currently included in WET testing: mortality, growth, development, and reproduction. For each endpoint, the link between responses at the molecular or cellular level, that can be measured in vitro, and the adverse outcome at the organism level were established through simplified toxicity pathways. Additionally, literature from 2015 to 2020 on the use of in vitro bioassays for water quality assessments was reviewed to identify a list of suitable bioassays for each endpoint. This review will enable the prioritization of relevant endpoints and bioassays for incorporation into WET testing.

Wastewater toxicity removal: Integrated chemical and effect-based monitoring of full-scale conventional activated sludge and membrane bioreactor plants

The literature is currently lacking effect-based monitoring studies targeted at evaluating the performance of full-scale membrane bioreactor plants. In this research, a monitoring campaign was performed at a full-scale wastewater treatment facility with two parallel lines (traditional activated sludge and membrane bioreactor). Beside the standard parameters (COD, nitrogen, phosphorus, and metals), 6 polynuclear aromatic hydrocarbons, 29 insecticides, 2 herbicides, and 3 endocrine disrupting compounds were measured. A multi-tiered battery of bioassays complemented the investigation, targeting different toxic modes of action and employing various biological systems (uni/multicellular, prokaryotes/eukaryotes, trophic level occupation). A traffic light scoring approach was proposed to quickly visualize the impact of treatment on overall toxicity that occurred after the exposure to raw and concentrated wastewater. Analysis of the effluents of the CAS and MBR lines show very good performance of the two systems for removal of organic micropollutants and metals. The most noticeable differences between CAS and MBR occurred in the concentration of suspended solids; chemical analyses did not show major differences. On the other hand, bioassays demonstrated better performance for the MBR. Both treatment lines complied with the Italian law's "ecotoxicity standard for effluent discharge in surface water". Yet, residual biological activity was still detected, demonstrating the adequacy and sensitivity of the toxicological tools, which, by their inherent nature, allow the overall effects of complex mixtures to be taken into account.

Endocrine disrupting chemicals entering European rivers: Occurrence and adverse mixture effects in treated wastewater

In the present study on endocrine disrupting chemicals (EDCs) in treated wastewater, we used chemical and effect-based tools to analyse 56 wastewater treatment plant (WWTP) effluents from 15 European countries. The main objectives were (i) to compare three different receptor-based estrogenicity assays (ERα-GeneBLAzer, p-YES, ERα-CALUX®), and (ii) to investigate a combined approach of chemical target analysis and receptor-based testing for estrogenicity, glucocorticogenic activity, androgenicity and progestagenic activity (ERα-, GR-, AR- and PR-GeneBLAzer assays, respectively) in treated wastewater. A total of 56 steroids and phenols were detected at concentrations ranging from 25 pg/L (estriol, E3) up to 2.4 μg/L (cortisone). WWTP effluents, which passed an advanced treatment via ozonation or via activated carbon, were found to be less contaminated, in terms of lower or no detection of steroids and phenols, as well as hormone receptor-mediated effects. This result was confirmed by the effect screening, including the three ERα-bioassays. In the GeneBLAzer assays, ERα-activity was detected in 82 %, and GR-activity in 73 % of the samples, while AR- and PR-activity were only measured in 14 % and 21 % of the samples, respectively. 17β-estradiol was confirmed as the estrogen dominating the observed estrogenic mixture effect and triamcinolone acetonide was the dominant driver of glucocorticogenic activity. The comparison of bioanalytical equivalent concentrations (BEQ) predicted from the detected concentrations and the relative effect potency (BEQ_chem) with measured BEQ (BEQ_bio) demonstrated good correlations of chemical target analysis and receptor-based testing results with deviations mostly within a factor of 10. Bioassay-specific effect-based trigger values (EBTs) from the literature, but also newly calculated EBTs based on previously proposed derivation options, were applied and allowed a preliminary assessment of the water quality of the tested WWTP effluent samples. Overall, this study demonstrates the high potential of linking chemical with effect-based analysis in water quality assessment with regard to EDC contamination.

Effect-directed analysis of a hospital effluent sample using A-YES for the identification of endocrine disrupting compounds

An effect-directed analysis (EDA) approach was used to identify the compounds responsible for endocrine disruption in a hospital effluent (Basque Country). In order to facilitate the identification of the potentially toxic substances, a sample was collected using an automated onsite large volume solid phase extraction (LV-SPE) system. Then, it was fractionated with a two-step orthogonal chromatographic separation and tested for estrogenic effects with a recombinant yeast (A-YES) in-vitro bioassay. The fractionation method was optimized and validated for 184 compounds, and its application to the hospital effluent sample allowed reducing the number of unknowns from 292 in the raw sample to 35 after suspect analysis of the bioactive fractions. Among those, 7 of them were confirmed with chemical standards. In addition, target analysis of the raw sample confirmed the presence of mestranol, estrone and dodemorph in the fractions showing estrogenic activity. Predictive estrogenic activity modelling using quantitative structure-activity relationships indicated that the hormones mestranol (5840 ng/L) and estrone (128 ng/L), the plasticiser bisphenol A (9219 ng/L) and the preservative butylparaben (1224 ng/L) were the main contributors of the potential toxicity. Derived bioanalytical equivalents (BEQs) pointed mestranol and estrone as the main contributors (56 % and 43 %, respectively) of the 50 % of the sample's explained total estrogenic activity.

Evaluation of Three ISO Estrogen Receptor Transactivation Assays Applied to 52 Domestic Effluent Samples

Estrogens are released to the aquatic environment by wastewater treatment plant (WWTP) effluents and can affect wildlife. In the last three decades, many in vitro assay platforms have been developed to detect and quantify estrogenicity in water. In 2018, the International Organization for Standardization (ISO) standardized protocols became available for three types of in vitro estrogen receptor transactivation assays (ERTAs) detecting estrogenicity in 96-well plates (ISO19040 1-3). Two ERTAs-lyticase Yeast Estrogen Screen (L-YES) and Arxula YES (A-YES)-use genetically modified yeast strains, whereas the third utilizes stably transfected human cells. One human cell based assay is ERα-CALUX, which is based on a genetically modified human bone osteosarcoma cell line. In the present study, we characterized the performance, comparability, and effectiveness of these three ERTAs, including an evaluation involving proposed water quality thresholds (effect-based trigger values [EBTs]). For a robust evaluation, we collected 52 effluent samples over three sampling campaigns at 15 different WWTPs in Switzerland. Estrogen receptor transactivation assay results were correlated and compared with results from chemical analysis targeting known estrogens. The three ERTAs showed comparable data over all campaigns. However, the selection of EBTs plays a significant role in the interpretation and comparison of bioassay results to distinguish between acceptable and unacceptable water quality. Applying a fixed cross-assay EBT for effluent of 4 ng L^-1 resulted in varying numbers of threshold exceedances ranging between zero and four samples depending on the ERTA used. Using assay-specific EBTs showed exceedances in eight samples (ERα-CALUX) and in one sample (A-YES), respectively. Thus, proposed EBTs do not produce similar risk profiles across samples and further refinement of assay-specific EBTs is needed to account for assay-specific differences and to enable the application of ERTAs as effect-based methods in environmental monitoring. Environ Toxicol Chem 2022;41:2512-2526. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Molecular Characterization of Estrogen Receptor Agonists during Sewage Treatment Processes Using Effect-Directed Analysis Combined with High-Resolution Full-Scan Screening

Endocrine-disrupting potential was evaluated during the sewage treatment process using in vitro bioassays. Aryl hydrocarbon receptor (AhR)-, androgen receptor (AR)-, glucocorticoid receptor (GR)-, and estrogen receptor (ER)-mediated activities were assessed over five steps of the treatment process. Bioassays of organic extracts showed that AhR, AR, and GR potencies tended to decrease through the sewage treatment process, whereas ER potencies did not significantly decrease. Bioassays on reverse-phase high-performance liquid chromatography fractions showed that F5 (log K_OW 2.5-3.0) had great ER potencies. Full-scan screening of these fractions detected two novel ER agonists, arenobufagin and loratadine, which are used pharmaceuticals. These compounds accounted for 3.3-25% of the total ER potencies and 4% of the ER potencies in the final effluent. The well-known ER agonists, estrone and 17β-estradiol, accounted for 60 and 17% of the ER potencies in F5 of the influent and primary treatment, respectively. Fourier transform ion cyclotron resonance mass spectrometry analysis showed that various molecules were generated during the treatment process, especially CHO and CHOS (C: carbon, H: hydrogen, O: oxygen, and S: sulfur). This study documented that widely used pharmaceuticals are introduced into the aquatic environments without being removed during the sewage treatment process.

Holistic approach to chemical and microbiological quality of aquatic ecosystems impacted by wastewater effluent discharges

Wastewater treatment plants (WWTPs) collect wastewater from various sources and use different treatment processes to reduce the load of pollutants in the environment. Since the removal of many chemical pollutants and bacteria by WWTPs is incomplete, they constitute a potential source of contaminants. The continuous release of contaminants through WWTP effluents can compromise the health of the aquatic ecosystems, even if they occur at very low concentrations. The main objective of this work was to characterize, over a period of four months, the treatment steps starting from income to the effluent and 5 km downstream to the receiving river. In this context, the efficiency removal of chemical pollutants (e.g. hormones and pharmaceuticals, including antibiotics) and bacteria was assessed in a WWTP case study by using a holistic approach. It embraces different chemical and biological-based methods, such as pharmaceutical analysis by HPLC-MSMS, growth rate inhibition in algae, ligand binding estrogen receptor assay, microbial community study by 16S and shotgun sequencing along with relative quantification of resistance genes by quantitative polymerase chain reaction. Although both, chemical and biological-based methods showed a significant reduction of the pollutant burden in effluent and surface waters compared to the influent of the WWTP, no complete removal of pollutants, pathogens and antibiotic resistance genes was observed.

Substances of emerging concern in Baltic Sea water: Review on methodological advances for the environmental assessment and proposal for future monitoring

The Baltic Sea is among the most polluted seas worldwide. Anthropogenic contaminants are mainly introduced via riverine discharge and atmospheric deposition. Regional and international measures have successfully been employed to reduce concentrations of several legacy contaminants. However, current Baltic Sea monitoring programs do not address compounds of emerging concern. Hence, potentially harmful pharmaceuticals, UV filters, polar pesticides, estrogenic compounds, per- and polyfluoroalkyl substances, or naturally produced algal toxins are not taken into account during the assessment of the state of the Baltic Sea. Herein, we conducted literature searches based on systematic approaches and compiled reported data on these substances in Baltic Sea surface water and on methodological advances for sample processing and chemical as well as effect-based analysis of these analytically challenging marine pollutants. Finally, we provide recommendations for improvement of future contaminant and risk assessment in the Baltic Sea, which revolve around a combination of both chemical and effect-based analyses.

Emerging Pollutants in Wastewater, Advanced Oxidation Processes as an Alternative Treatment and Perspectives

Emerging pollutants are present in wastewaters treated by conventional processes. Due to water cycle interactions, these contaminants have been reported in groundwater, surface water, and drinking waters. Since conventional processes cannot guarantee their removal or biotransformation, it is necessary to study processes that comply with complete elimination. The current literature review was conducted to describe and provide an overview of the available information about the most significant groups of emerging pollutants that could potentially be found in the wastewater and the environment. In addition, it describes the main entry and distribution pathways of emerging contaminants into the environment through the water and wastewater cycle, as well as some of the potential effects they may cause to flora, fauna, and humans. Relevant information on the SARS-CoV-2 virus and its potential spread through wastewater is included. Furthermore, it also outlines some of the Advanced Oxidation Processes (AOPs) used for the total or partial emerging pollutants removal, emphasizing the reaction mechanisms and process parameters that need to be considered. As well, some biological processes that, although slow, are effective for the biotransformation of some emerging contaminants and can be used in combination with advanced oxidation processes.

Estrogenic activity and ecological risk of steroids, bisphenol A and phthalates after secondary and tertiary sewage treatment processes

Effluents of sewage treatment plants (STPs) are an important source of estrogenic substances to the receiving water bodies affecting their ecological safety. In this study, steroids, bisphenol A (BPA) and phthalates were assessed in the secondary (SE) and tertiary effluent (TE) of three typical urban STPs in Beijing (China). In addition, the overall estrogenic activity in these effluents was assessed by an in-vitro bioassay (ERE-CALUX). Results showed that the concentrations and activities of estrogenic compounds in TE were lower than those in SE. The residual concentration of 17β-estradiol (E2) was the highest among the detected steroids, accounting for 51.6 ± 5.1% in SE and 57.5 ± 24.8% in TE. The residual level (25.2-41.6 ng/L) of BPA in effluents was significantly higher than that of steroids (0.2-28.8 ng/L). The residual concentration of diethyl phthalate was the highest among the detected phthalates accounting for 47.1 ± 5.1% in SE and 37.6 ± 11.5% in TE. Steroids and BPA had a higher removal rate (83.5% and 96.7%) in secondary and tertiary treatment than phthalates (68.8% and 83.1%). The hydrophobic characteristics of these estrogenic compounds determined the removal mechanism. The removal of steroids, BPA, dimethyl phthalate and diethyl phthalate (LogKow= 1.61-4.15) mainly occurred through biodegradation in the water phase, while the removal of dibutyl phthalate, butylbenzyl phthalate and di(2-ethylhexyl) phthalate (LogKow= 4.27-7.50) mainly occurred in the solid phase after adsorption on and sedimentation of the suspended particulate matter. According to ERE-CALUX, the estrogenic activity in the final STP effluents was 3.2-45.6 ng E2-equivalents/L, which is higher than reported levels in the effluents of European STPs. Calculation of estrogenic equivalents by using substance specific chemical analysis indicated that the dominant contributor was E2 (56.4-88.4%), followed by 17α-ethinylestradiol (EE2) (4.1-34.8%), both also exerting a moderate risk to the aquatic ecosystem. While the upgrade of treatment processes in STPs has efficiently reduced the emission of estrogenic substances, their ecological risk was not yet phased out.

Towards regulation of Endocrine Disrupting chemicals (EDCs) in water resources using bioassays - A guide to developing a testing strategy

Endocrine disrupting chemicals (EDCs) are found in every environmental medium and are chemically diverse. Their presence in water resources can negatively impact the health of both human and wildlife. Currently, there are no mandatory screening mandates or regulations for EDC levels in complex water samples globally. Bioassays, which allow quantifying in vivo or in vitro biological effects of chemicals are used commonly to assess acute toxicity in water. The existing OECD framework to identify single-compound EDCs offers a set of bioassays that are validated for the Estrogen-, Androgen-, and Thyroid hormones, and for Steroidogenesis pathways (EATS). In this review, we discussed bioassays that could be potentially used to screen EDCs in water resources, including in vivo and in vitro bioassays using invertebrates, fish, amphibians, and/or mammalians species. Strengths and weaknesses of samples preparation for complex water samples are discussed. We also review how to calculate the Effect-Based Trigger values, which could serve as thresholds to determine if a given water sample poses a risk based on existing quality standards. This work aims to assist governments and regulatory agencies in developing a testing strategy towards regulation of EDCs in water resources worldwide. The main recommendations include 1) opting for internationally validated cell reporter in vitro bioassays to reduce animal use & cost; 2) testing for cell viability (a critical parameter) when using in vitro bioassays; and 3) evaluating the recovery of the water sample preparation method selected. This review also highlights future research avenues for the EDC screening revolution (e.g., 3D tissue culture, transgenic animals, OMICs, and Adverse Outcome Pathways (AOPs)).

Extensive rain events have a more substantial impact than advanced effluent treatment on the endocrine-disrupting activity in an effluent-dominated small river

Wastewater treatment plants (WWTPs) remain an important primary source of emission for endocrine-disrupting compounds in the environment. As an advanced wastewater treatment process, ozonation is known to reduce endocrine-disrupting activity. However, it remains unclear to which extend improved wastewater treatment may reduce the endocrine-disrupting activity in the receiving water body. The present study investigated possible factors for the endocrine-disrupting activity in a small receiving water body, the Wurm River (North-Rhine Westphalia, Germany), up- and downstream of a local WWTP. The cell-based reporter gene CALUX® assay was applied to identify the endocrine-disrupting activity in the water, sediment, and suspended particulate matter. The water phase and the effluent sampling were primarily driven by applying the full-scale effluent ozonation (sampling campaigns in June 2017 and March 2019). In contrast, the sediment sampling aimed to compare the particle-bound endocrine-disrupting activity during dry (June 2017) and rainy summer (June 2018) seasons. The water phase showed low to moderate estrogenic/antiandrogenic activity. Advanced effluent treatment by ozonation led to a complete reduction of the endocrine-disrupting activity according to the limit of detection of the CALUX® assays. The suspended particulate matter originated from the water phase of the second sampling campaign revealed antiandrogenic activity only. Sediments at the sampling sites along the local WWTP revealed higher estrogenic and antiandrogenic activity after extensive rain events and were not affected by the ozonated effluent. Fluctuation patterns of the endocrine-disrupting activity in sediments were in line with fluctuated concentrations of polycyclic aromatic hydrocarbons. Rainwater overflow basin release was suggested as a vector for particle-bound and dissolved endocrine-disrupting activity in the receiving water body. The present study underlined the necessity for monitoring both water and sediment phases to achieve reliable profiling of the endocrine-disrupting activity. The receptor-mediated CALUX® assays were proven to be suitable for investigating the endocrine-disrupting activity distribution in different river compartments and WWTP effluents.

Improvement of wastewater and water quality via a full-scale ozonation plant? - A comprehensive analysis of the endocrine potential using effect-based methods

Micropollutants (MPs), especially endocrine disrupting compounds (EDCs), are mainly released from WWTPs into surface water bodies and can subsequently lead to adverse effects in biota. Treatment with ozone proved to be a suitable method for eliminating such MPs. This method was implemented at the WWTP Aachen-Soers by commissioning the largest full-scale ozonation plant in Europe at the moment. Recently, effect-based methods (EBMs) have been successfully proved for compliance monitoring, e.g. estrogenic compounds. Therefore, the impact of ozone treatment on endocrine potential (agonistic and antagonistic) of treated wastewater was investigated using the ERα- and AR CALUX assays. Additionally, the impact on the receiving stream and a potential preload of the water body was assessed. Therefore, the current study could deal as a case study for small rivers being highly impacted by WWTPs. The estrogenic potential was nearly fully eliminated after ozone treatment. Contrary, the antagonistic (anti-estrogenic and anti-androgenic) potential did not show a clear elimination pattern after ozone treatment independent of the applied ozone dosage and control system. Therefore, further investigations are required regarding the antagonistic potential. Additionally, preloading of the receiving stream was found during the study period. One significant impact is a rain overflow basin (ROB) located upstream of the WWTP effluent. The highest endocrine potential was found after a ROB overflow (2.7 ng EEQ/L, 2.4 μg TMX-EQ/L, 104 μg FLU-EQ/L), suggesting that such runoff events after a heavy rainfall may act as a driver of endocrine loading to the water body. This manuscript contributes significantly to the basic understanding of the efficiency of eliminating the endocrine potential of ozone treatment by, e.g., showing that there is a further need for improving the removal efficiency of antagonistic potential. Moreover, it highlights the need to include other point sources, such as ROBs, to assess polluted surface waters comprehensively.

Monitoring of emerging contaminants of concern in the aquatic environment: a review of studies showing the application of effect-based measures

Water scarcity is increasingly a global cause of concern mainly due to widespread changes in climate conditions and increased consumptive water use driven by the exponential increase in population growth. In addition, increased pollution of fresh water sources due to rising production and consumption of pharmaceuticals and organic chemicals will further exacerbate this concern. Although surface water contamination by individual chemicals is often at very low concentration, pharmaceuticals for instance are designed to be efficacious at low concentrations, creating genuine concern for their presence in freshwater sources. Furthermore, the additive impact of multiple compounds may result in toxic or other biological effects that otherwise will not be induced by individual chemicals. Globally, different legislative frameworks have led to pre-emptive efforts which aim to ensure good water ecological status. Reports detailing the use and types of effect-based measures covering specific bioassay batteries that can identify specific mode of actions of chemical pollutants in the aquatic ecosystem to evaluate the real threat of pollutants to aquatic lives and ultimately human lives have recently emerged from monitoring networks such as the NORMAN network. In this review, we critically evaluate some studies within the last decade that have implemented effect-based monitoring of pharmaceuticals and organic chemicals in aquatic fauna, evaluating the occurrence of different chemical pollutants and the impact of these pollutants on aquatic fauna with special focus on pollutants that are contaminants of emerging concern (CEC) in urban wastewater. A critical discussion on studies that have used effect-based measures to assess biological impact of pharmaceutical/organic compound in the aquatic ecosystem and the endpoints measurements employed is presented. The application of effect-based monitoring of chemicals other than assessment of water quality status is also discussed.

Impact of peri-urban landscape on the organic and mineral contamination of pond waters and related risk assessment

Ponds are important for their ecological value and for the ecosystem services they provide to human societies, but they are strongly affected by human activities. Peri-urban development, currently one of the most pervasive processes of land use change in Europe, exposes ponds to both urban and agricultural contaminants, causing a potential combination of adverse effects. This study, focused on 12 ponds located in a peri-urban area, has two main objectives: (1) to link the physico-chemical characteristics of the waters and the nature of their contaminants, either organic or mineral, with the human activities around ponds, and (2) to estimate the environmental risk caused by these contaminants. The ponds were sampled during two consecutive years in both spring and in autumn. Although the ponds were distributed over a limited geographical area, their contamination profiles were different and more correlated with the agricultural than the urban land use. In terms of aptitude for biology, half of the ponds were classified in degraded states due to their physico-chemical parameters, but without correlation with the endocrine disrupting activities and the levels of organic pollutants as indicators. The main quantified organic pollutants, however, were pesticides with sufficiently high levels in certain cases to induce an environmental risk exceeding the classical thresholds of risk quotient.

Estrogenicity of chemical mixtures revealed by a panel of bioassays

Estrogenic compounds are widely released to surface waters and may cause adverse effects to sensitive aquatic species. Three hormones, estrone, 17β-estradiol and 17α-ethinylestradiol, are of particular concern as they are bioactive at very low concentrations. Current analytical methods are not all sensitive enough for monitoring these substances in water and do not cover mixture effects. Bioassays could complement chemical analysis since they detect the overall effect of complex mixtures. Here, four chemical mixtures and two hormone mixtures were prepared and tested as reference materials together with two environmental water samples by eight laboratories employing nine in vitro and in vivo bioassays covering different steps involved in the estrogenic response. The reference materials included priority substances under the European Water Framework Directive, hormones and other emerging pollutants. Each substance in the mixture was present at its proposed safety limit concentration (EQS) in the European legislation. The in vitro bioassays detected the estrogenic effect of chemical mixtures even when 17β-estradiol was not present but differences in responsiveness were observed. LiBERA was the most responsive, followed by LYES. The additive effect of the hormones was captured by ERα-CALUX, MELN, LYES and LiBERA. Particularly, all in vitro bioassays detected the estrogenic effects in environmental water samples (EEQ values in the range of 0.75-304 × EQS), although the concentrations of hormones were below the limit of quantification in analytical measurements. The present study confirms the applicability of reference materials for estrogenic effects' detection through bioassays and indicates possible methodological drawbacks of some of them that may lead to false negative/positive outcomes. The observed difference in responsiveness among bioassays - based on mixture composition - is probably due to biological differences between them, suggesting that panels of bioassays with different characteristics should be applied according to specific environmental pollution conditions.

Removal of micropollutants and biological effects by conventional and intensified constructed wetlands treating municipal wastewater

Seven treatment wetlands and a municipal wastewater treatment plant (WWTP) were weekly monitored over the course of one year for removal of conventional wastewater parameters, selected micropollutants (caffeine, ibuprofen, naproxen, benzotriazole, diclofenac, acesulfame, and carbamazepine) and biological effects. The treatment wetland designs investigated include a horizontal subsurface flow (HF) wetland and a variety of wetlands with intensification (aeration, two-stages, or reciprocating flow). Complementary to the common approach of analyzing individual chemicals, in vitro bioassays can detect the toxicity of a mixture of known and unknown components given in a water sample. A panel of five in vitro cell-based reporter gene bioassays was selected to cover environmentally relevant endpoints (AhR: indicative of activation of the aryl hydrocarbon receptor; PPARγ: binding to the peroxisome proliferator-activated receptor gamma; ERα: activation of the estrogen receptor alpha; GR: activation of the glucocorticoid receptor; oxidative stress response). While carbamazepine was persistent in the intensified treatment wetlands, mean monthly mass removal of up to 51% was achieved in the HF wetland. The two-stage wetland system showed highest removal efficacy for all biological effects (91% to >99%). The removal efficacy for biological effects ranged from 56% to 77% for the HF wetland and 60% to 99% for the WWTP. Bioanalytical equivalent concentrations (BEQs) for AhR, PPARγ, and oxidative stress response were often below the recommended effect-based trigger (EBT) values for surface water, indicating the great benefit for using nature-based solutions for water treatment. Intensified treatment wetlands remove both individual micropollutants and mixture effects more efficiently than conventional (non-aerated) HF wetlands, and in some cases, the WWTP.

Secondary treatment phase of tertiary wastewater treatment works significantly reduces estrogenic load

Estrogenic compounds enter waterways via effluents from wastewater treatment works (WWTW), thereby indicating a potential risk to organisms inhabiting adjacent receiving waters. However, little is known about the loads or concentrations of estrogenic compounds that enter Australian WWTWs, the efficiency of removing estrogenic compounds throughout the various stages of tertiary WWTW processes (which are common in Australia), nor the concentrations released into estuarine or marine receiving waters, and the associated risk for aquatic taxa residing in these environments. Therefore, seven estrogenic compounds, comprising the natural estrogens estrone (E1), 17β-estradiol (E2) and estriol (E3), the synthetic estrogen (EE2), and the industrial chemicals bisphenol A (BPA), 4-t-octyl phenol (4-t-OP) and 4-nonyl phenol (4-NP), in wastewater samples were quantified via liquid chromatographic-mass spectrometry (LC-MS) after solid-phase extraction at different stages of wastewater treatment and associated receiving waters. The concentrations of the target compounds in wastewater ranged from < LOQ (limit of quantification) to 158 ng/L for Tanilba Bay WWTW and < LOQ to 162 ng/L for Belmont WWTW. Most target compounds significantly declined after the secondary treatment phase. Appreciable removal efficiency throughout the treatment process was observed with removal from 39.21 to 99.98% of influent values at both WWTWs. The reduction of the natural estrogens (E1, E2 and E3) and 4-t-OP were significantly greater than EE2, BPA, and 4-NP in both WWTWs. Risk quotients (RQs) were calculated to assess potential ecological risks from individual estrogenic compounds. In predicted diluted effluents, no targeted compounds showed any ecological risk (RQ ≤1.65 × 10^-2) at both WWTWs. Similarly, all RQs for shore samples at both WWTWs were below 1. Finally, the hazard index (HI), which represents combined estrogenic contaminants' ecological risk, indicated no mentionable risk for predicted diluted effluents (HI = 0.0097 to 0.0218) as well as shoreline samples (HI = 0.393 to 0.522) in the receiving estuarine or marine waters.

LED irradiated photo-Fenton for the removal of estrogenic activity and endocrine disruptors from wastewater treatment plant effluent

The goal of this work was to evaluate the performance of the LED irradiated photo-Fenton process on the removal of (i) estrogenic activity and (ii) seven endocrine disruptors (EDs) (4-octylphenol, 4-nonylphenol, bisphenol A, estrone, 17β-estradiol, 17α-ethinylestradiol, and estriol) from real wastewater treatment plant effluent (WWTPE). EDs are a group of contaminants of emerging concern present in WWTPE and which may be recognized by hormone receptors, thus harming animal and human health. The yeast estrogenic screen test (YES) was used to quantify estrogenic activity promoted by EDs in WWTPE samples before and after photo-Fenton treatment. Tests were performed following a factorial design with different iron (20, 40, and 60 mg L^-1) and hydrogen peroxide (100, 200, and 300 mg L^-1) concentrations in a laboratory scale LED photoreactor (λ = 455 nm, 1.5 L, 1.6 × 10^-6 Einstein s^-1). EDs were analyzed by gas chromatography coupled to a mass spectrometer. Control experiments consisted of Fenton process, iron only, LED irradiation only, and H₂O₂ only. Optimum experimental conditions for LED photo-Fenton resulted in 62% removal of estrogenic activity and 59% mineralization. In addition, treated WWTPE was not toxic to Aliivibrio fischeri and more than 80% of EDs were removed during LED irradiated photo-Fenton. Although Fenton process showed similar efficiency to that obtained by LED photo-Fenton, a higher volume of sludge was generated in the dark. Finally, results obtained in this study confirm the applicability of LED irradiated photo-Fenton process for improving the quality of WWTPE as an alternative to solar photo-Fenton in case solar radiation is not available, thus reducing hazards associated to WWTPE reuse or discharge.

Biodegradation of natural and synthetic endocrine-disrupting chemicals by aerobic granular sludge reactor: Evaluating estrogenic activity and estrogens fate

In this study, the biodegradation of endocrine-disrupting chemicals (EDCs) (namely the natural and synthetic estrogens 17β-estradiol (E2) and 17α-ethinylestradiol (EE2), respectively) was assessed in an aerobic granular sludge (AGS) sequencing batch reactor (SBR) treating simulated domestic sewage. To better understand the fate of these compounds, their concentrations were determined in both liquid and solid (biomass) samples. Throughout the operation of the reactor, subjected to alternating anaerobic and aerated conditions, the removal of the hormones, both present in the influent at a concentration of 20 μg L^-1, amounted to 99% (for E2) and 93% (for EE2), with the latter showing higher resistance to biodegradation. Through yeast estrogen screen assays, an average moderate residual estrogenic activity (0.09 μg L^-1 EQ-E2) was found in the samples analysed. E2 and EE2 profiles over the SBR cycle suggest a rapid initial adsorption of these compounds on the granular biomass occurring anaerobically, followed by biodegradation under aeration. A possible sequence of steps for the removal of the micropollutants, including the key microbial players, was proposed. Besides the good capability of the AGS on EDCs removal, the results revealed high removal efficiencies (>90%) of COD, ammonium and phosphate. Most of the incoming organics (>80%) were consumed under anaerobic conditions, when phosphate was released (75.2 mgP L^-1). Nitrification and phosphate uptake took place along the aeration phase, with effluent ammonium and phosphate levels around 2 mg L^-1. Although nitrite accumulation took place over the cycle, nitrate consisted of the main oxidized nitrogen form in the effluent. The specific ammonium and phosphate uptake rates attained in the SBR were found to be 3.3 mgNH₄⁺-N gVSS^-1.h^-1 and 6.7 mgPO₄^3--P gVSS^-1 h^-1, respectively, while the specific denitrification rate corresponded to 1.0 mgNO_x^--N gVSS^-1 h^-1.

Application of an Effects-Based Monitoring Strategy to Assess the Impact of Contaminants on Fish Health in an Urbanized Watershed

Effects-based monitoring frameworks that combine the use of analytical chemistry with in vitro cell bioassays, as well as in vivo whole organism tests offer an integrative approach to broadly screen for chemical contaminants and link their presence with adverse effects on aquatic organisms. California (USA) is currently evaluating the use of such a framework to assess the impact of contaminants of emerging concern (CECs) on biota in urbanized rivers and other waterbodies. In the present study, the occurrence and effects of contaminants found in the Los Angeles River (Los Angeles County, CA, USA) were examined using analytical chemistry and in vitro and in vivo bioassays. Male fathead minnows were deployed in field-based exposure units and exposed to river water for 21 d. The 2 field sites (above Bull Creek [BLC] and below Glendale Water Reclamation Plant [GWR]) were selected based on their unique characteristics and different contaminant discharge sources. In addition, 2 control units (filtered city water and estrone-spiked water) were added to the experimental design. Chemical analyses revealed differences in abundance of CECs between the 2 field sites and the controls, with GWR having the highest number and concentrations of CECs and metals. Cell bioassays screening for estrogenic, glucocorticoid, progestin, and dioxin-like activities were near or below detection limits in all river water samples, indicating a low potential for endocrine-related toxicity and tissue damage. Cell bioassay results were corroborated by the in vivo analyses. Field-exposed fish exhibited no changes in plasma hormones (e.g., estradiol), vitellogenin, or gonad maturation, but gene biomarkers of chemical exposure (cytochrome p450 1A and metallothionein) were significantly elevated, confirming exposure of the fish to complex chemical mixtures. The results demonstrate the value of a tiered monitoring approach to assess the sublethal effects of chemical mixtures on aquatic life. Environ Toxicol Chem 2021;40:402-412. © 2020 SETAC.

Recent Advances in the Rejection of Endocrine-Disrupting Compounds from Water Using Membrane and Membrane Bioreactor Technologies: A Review

Water is a critical resource necessary for life to be sustained, and its availability should be secured, appropriated, and easily obtainable. The continual detection of endocrine-disrupting chemicals (EDCs) (ng/L or µg/L) in water and wastewater has attracted critical concerns among the regulatory authorities and general public, due to its associated public health, ecological risks, and a threat to global water quality. Presently, there is a lack of stringent discharge standards regulating the emerging multiclass contaminants to obviate its possible undesirable impacts. The conventional treatment processes have reportedly ineffectual in eliminating the persistent EDCs pollutants, necessitating the researchers to develop alternative treatment methods. Occurrences of the EDCs and the attributed effects on humans and the environment are adequately reviewed. It indicated that comprehensive information on the recent advances in the rejection of EDCs via a novel membrane and membrane bioreactor (MBR) treatment techniques are still lacking. This paper critically studies and reports on recent advances in the membrane and MBR treatment methods for removing EDCs, fouling challenges, and its mitigation strategies. The removal mechanisms and the operating factors influencing the EDCs remediation were also examined. Membranes and MBR approaches have proven successful and viable to eliminate various EDCs contaminants.

Wastewater treatment efficacy evaluated with in vitro bioassays

Bioassays show promise as a complementary approach to chemical analysis to assess the efficacy of wastewater treatment processes as they can detect the mixture effects of all bioactive chemicals in a sample. We investigated the treatment efficacy of ten Australian wastewater treatment plants (WWTPs) covering 42% of the national population over seven consecutive days. Solid-phase extracts of influent and effluent were subjected to an in vitro test battery with six bioassays covering nine endpoints that captured the major modes of action detected in receiving surface waters. WWTP influents and effluents were compared on the basis of population- and flow-normalised effect loads, which provided insights into the biological effects exhibited by the mixture of chemicals before and after treatment. Effect removal efficacy varied between effect endpoints and depended on the treatment process. An ozonation treatment step had the best treatment efficacy, while WWTPs with only primary treatment resulted in poor removal of effects. Effect removal was generally better for estrogenic effects and the peroxisome proliferator-activated receptor than for inhibition of photosynthesis, which is consistent with the persistence of herbicides causing this effect. Cytotoxicity and oxidative stress response provided a sum parameter of all bioactive chemicals including transformation products and removal was poorer than for specific endpoints except for photosynthesis inhibition. Although more than 500 chemicals were analysed, the detected chemicals explained typically less than 10% of the measured biological effect, apart from algal toxicity, where the majority of the effect could be explained by one dominant herbicide, diuron. Overall, the current study demonstrated the utility of applying bioassays alongside chemical analysis to evaluate loads of chemical pollution reaching WWTPs and treatment efficacy.

High resolution effect-directed analysis of steroid hormone (ant)agonists in surface and wastewater quality monitoring

Monitoring of chemical water quality is extremely challenging due to the large variety of compounds and the presence of biologically active compounds with unknown chemical identity. Previously, we developed a high resolution Effect-Directed Analysis (EDA) platform that combines liquid chromatography with high resolution mass spectrometry and parallel bioassay detection. In this study, the platform is combined with CALUX bioassays for (anti)androgenic, estrogenic and glucocorticoid activities, and the performance of the platform is evaluated. It appeared to render very repeatable results, with high recoveries of spiked compounds and high consistency between the mass spectrometric and bioassay results. Application of the platform to wastewater treatment plant effluent and surface water samples led to the identification of several compounds contributing to the measured activities. Eventually, a workflow is proposed for the application of the platform in a routine monitoring context. The workflow divides the platform into four phases, of which one to all can be performed depending on the research question and the results obtained. This allows one to make a balance between the effort put into the platform and the certainty and depth by which active compounds will be identified. The EDA platform is a valuable tool to identify unknown bioactive compounds, both in an academic setting as in the context of legislative, governmental or routine monitoring.

Nonylphenol ethoxylates biodegradation increases estrogenicity of textile wastewater in biological treatment systems

The formation of estrogenic intermediates, i.e. nonylphenol diethoxylate (NP2EO), nonylphenol monoethoxylate (NP1EO), and nonylphenol (NP), following nonylphenol ethoxylates (NPEOs) biodegradation in textile wastewater raises concerns about its endocrine disruptive activity, but the estrogenicity changes of textile wastewater throughout biological treatment processes remain unknown. In the present study, the estrogenicity of textile wastewater sampled from 10 wastewater treatment plants (WWTPs) were investigated using the reporter gene-based T47D-KBluc bioassay. Results showed that the estrogenicity of the textile wastewater significantly increased after either anaerobic or aerobic treatment in all WWTPs, with an average fold change of 3.21, although traditional pollutants were effectively removed. The estradiol equivalents of the effluent (ranging from 1.50 to 4.12 ng-E2/L) were generally higher than published effect based trigger values, indicating an increased risk for the receiving waters. Removal efficiency was high (84.46%) for NPEOs, but was low for NP2EO and NP1EO in the biological treatment processes. Nevertheless, NP had increased concentrations after the treatment. Bioanalytical equivalent concentration of the textile wastewater and that of NP2EO, NP1EO, and NP showed a good linear correlation, of which NP alone contributed more than 70% to the observed estrogenicity. Extending hydraulic retention time was found effective in reducing the estrogenicity as it allows relatively complete degradation of NP, which was further confirmed by running lab-scale A/O reactors fed with NP10EO. The results may extend our knowledge regarding the estrogenicity of textile wastewater and its reduction technologies used in WWTPs.

Investigating (anti)estrogenic activities within South African wastewater and receiving surface waters: Implication for reliable monitoring

Natural and synthetic steroid hormones and many persistent organic pollutants are of concern for their endocrine-disrupting activities observed in receiving surface waters. Apart from the demonstrated presence of estrogen- and estrogen-mimicking compounds in surface waters, antagonistic (anti-estrogenic) responses originating from wastewater effluent have been reported but are less known. Estrogenicity and anti-estrogenicity were assessed using recombinant yeast estrogen receptor binding assays (YES/YAES) at ten South African wastewater treatment works (WWTWs) and receiving rivers in two separate sampling campaigns during the summer- and winter periods in the area. Four WWTWs were then further investigated to show daily variation in estrogenic endocrine-disrupting activities during the treatment process. Although estrogenicity was notably reduced at most of the WWTWs, some treated effluent and river water samples were shown to be above effect-based trigger values posing an endocrine-disrupting risk for aquatic life and potential health risks for humans. Furthermore, estrogenicity recorded in samples collected upstream from some WWTW discharge points also exceeded some calculated risk trigger values, which highlights the impact of alternative pollution sources contributing towards endocrine disrupting contaminants (EDCs) in the environment. The YAES further showed variable anti-estrogenic activities in treated wastewater. The current study highlights a variety of factors that may affect bioassay outcomes and conclusions drawn from the results for risk decision-making. For example, mismatches were found between estrogenic and anti-estrogenic activity, which suggests a potential masking effect in WWTW effluents and highlights the complexity of environmental samples containing chemical mixtures having variable endocrine-disrupting modes of action. Although the recombinant yeast assay is not without its limitations to show endocrine-disrupting modulation in test water systems, it serves as a cost-effective tier-1 scoping assay for further risk characterisation and intervention.

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.

Steroid hormone micropollutant removal from water with activated carbon fiber-ultrafiltration composite membranes

Short activated carbon fibers (ACF) with high surface area were fabricated via carbonization in N₂ and activation in CO₂ at high temperatures, with cellulose fibers as the raw materials. The obtained ACF were subsequently deposited into the support layer of a polyethersulfone (PES) ultrafiltration membrane by a facile filtration process to obtain the sandwich structured ACF-PES composite membrane. The hormone (17β-estradiol, E2) adsorption kinetics and isotherm of ACF in static conditions, as well as E2 removal by filtration with the ACF-PES composite membrane were investigated. In static conditions, ACF rapidly and efficiently adsorbs E2 evidenced by a high removal of >97 %. The fitting of second order kinetics and linear (Henry) adsorption isotherm models indicated the availability of easily accessible adsorption sites. Besides, such efficient E2 adsorption was contributed by many interactions between E2 and ACF, namely hydrophobic interactions, hydrogen bonding and π-π stacking. The incorporation of ACF in a PES membrane resulted in a minor loss of filtration flux compared with the control membrane, but significantly improved E2 removal through adsorption pathway. With only 1.0 mg ACF incorporated (loading 2.0 g/m²), the composite membrane could reject 76 % of E2 from a 100 ng/L solution at a flux of 450 L/m²∙h, demonstrating that ACF-PES can overcome the permeability-selectivity trade-off of traditional UF membranes.

Development of a separation framework for effects-based targeted and non-targeted toxicological screening of water and wastewater

An environmental water sample fractionation framework was developed based on effects-directed analysis (EDA) to detect known and unknown compounds of concern in different waters. Secondary effluent from a wastewater treatment plant was used to demonstrate the effectiveness of the developed framework for characterizing estrogenic compounds in the effluent. The effluent was spiked with known estrogenic compounds to validate the framework in a targeted approach and an unspiked sample was also investigated in a non-targeted approach. The framework separated compounds based on polarity and adsorption using liquid-liquid extraction followed by solid phase extraction. The targeted and non-targeted effluents generated six fractions each, which were assessed for estrogenic activity using an in vitro bioassay (yeast estrogen screen - YES). Three out of the six fractions in each case, along with the raw effluent, showed estrogen equivalent concentrations (EEQs) ranging between 1.0 and 3.0 μg/L. Directed by the assay results, these estrogenic fractions were further analyzed using liquid- and gas-chromatography coupled with mass spectrometry for compound identification. The developed separation framework coupled with a bioassay aided in identification of both known and unknown compounds producing estrogenic effects in the water sample. The approach of fractionation followed by concentration helped isolate and elevate contaminant levels without necessarily concentrating potential matrix effects that could cause interfering cytotoxicity and inhibition in the bioassay. The targeted analysis showed consistency between predicted and observed results, while the non-targeted analysis revealed the presence of three estrogenic compounds in the unspiked effluent: di-isobutyl phthalate, diethyl phthalate and benzophenone, that were confirmed with standards. The study mainly aimed at development and validation of a simple yet effective EDA framework with low cost techniques for water and wastewater toxicity screening and evaluation, and the results suggested that the developed framework could be used as a screening tool for isolating and identifying unknown compounds in a complex water sample.

Evaluation of a biological post-treatment after full-scale ozonation at a municipal wastewater treatment plant

To reduce the discharge of trace organic compounds into water bodies associated with potential toxic effects such as endocrine disruption, new advanced treatment methods are being investigated at several wastewater treatment plants (WWTPs). One of the most studied and already implemented technologies is ozonation. However, ozonation only partially oxidizes trace organic compounds (TrOC) and as a result, transformation products (TPs) with unknown properties can be formed. In order to minimise the risk of releasing unknown and potentially toxic TPs into surface water, it is recommended to install a biological post-treatment after ozonation. The aim of this study was to evaluate the efficiency of a moving bed reactor following ozonation in a full-scale plant. Different ozone dosages (z_spec. = 0.3, 0.5, 0.7 mg _O3/mg_DOC) were investigated. To assess the biological activity of the post-treatment, the assimilable organic carbon (AOC) was determined in addition to the formed biomass. Furthermore, selected TrOC were analysed in parallel to monitor the ozonation efficiency at different ozone doses. In addition, estrogenic, androgenic as well as corresponding antagonistic effects were investigated after each treatment step using the A-YES and A-YAS assay. A non-target screening was performed to evaluate a trend analysis of formed TPs as well as their removal by the post-treatment procedure. The results proved the successful design of the biological post-treatment reactor by a constant biofilm development and reduction of the AOC. Endocrine effects were removed below the limit of detection (LOD) of 10 pg EEQ/L already after ozonation for all applied ozone doses. Antagonistic effects were not significantly reduced during ozonation and subsequent biological post-treatment. For this reason, further research is needed to evaluate different post-treatment technologies. The trend analysis from non-target screening data showed a reduction of about 95% of the number of formed TPs by the biological post-treatment. Consequently, an assessment of the biological activity and the elimination capacity of a certain biological post-treatment technique is thus possible by applying the AOC in combination with a non-target screening.

Exclusion of Estrogenic and Androgenic Steroid Hormones from Municipal Membrane Bioreactor Wastewater Using UF/NF/RO Membranes for Water Reuse Application

In the context of water scarcity, domestic secondary effluent reuse may be an option as a reliable source for alleviating acute water shortage. The increasing risks linked with the presence of natural steroid hormones and many emerging anthropogenic micropollutants (MPs) passing through municipal wastewater treatment works (MWWTWs) are of concern for their endocrine-disrupting activities. In this study, domestic wastewater treated by a full-scale membrane bioreactor (MBR) at an MWWTW in the Western Cape Province, South Africa, was used directly as the influent to a reverse osmosis (RO) pilot plant for the removal of selected natural steroid hormones 17β-estradiol (E₂) and testosterone (T) as a potential indirect water recycling application. Estrogenicity and androgenicity were assessed using the enzyme-linked immunosorbent assays (ELISA) and the recombinant yeast estrogen receptor binding assays (YES). The influent pH and flux did not influence the rejection of E₂ and T, which was most likely due to adsorption, size exclusion, and diffusion simultaneously. RO and nanofiltration (NF) exhibited excellent removal rates (>95%) for E₂ and T. All the E₂ effluent samples with MBR/ultrafiltration (UF), MBR/NF, and MBR/RO were lower than the US EPA and WHO trigger value of 0.7 ng/L, as well as the predicted no-effect concentration (PNEC) values for fish (1 ng E₂/L).

Patterns of estrogenic activity in the Baltic Sea

Compounds such as estradiol and ethinylestradiol belong to contaminants of emerging concern, as they can disrupt the endocrine system of an organism with a hormonal system. The determination of such compounds is still challenging due to required low detection and quantification limits. Bioassays have proved to be sensitive tools for investigating the full potential of all compounds that can elicit an estrogenic response. In this study, surface water samples from different sampling sites and seasons in the Baltic Sea were analyzed for estrogenic activity with the Arxula adeninivorans yeast estrogen screen. Observed estradiol equivalent concentrations were in the range of <LOD - 0.38ngL^-1. In general, a seasonal trend was observed, i.e., with an increase in water temperature in late spring, estradiol equivalent concentrations rose suddenly and decreased as abruptly when the temperature declined in autumn. An initial risk assessment shows that observed estradiol equivalent concentrations potentially affect organisms at a medium risk level based on determined risk quotients.

Ecofriendly laccases treatment to challenge micropollutants issue in municipal wastewaters

In this study, a multidisciplinary approach investigated the enzymatic degradation of micropollutants in real, not modified, municipal wastewaters of a plant located in Italy. Stir Bar Sorptive Extraction combined to Gas Chromatography-Mass Spectrometric detection (SBSE-GC-MS) was applied to profile targeted pollutants in wastewaters collected after the primary sedimentation (W1) and the final effluent (W2). Fifteen compounds were detected at ng/L - μg/L, including pesticides, personal care products (PCPs) and drugs. The most abundant micropollutants were bis(2-ethylhexyl) phthalate, diethyl phthalate and ketoprofen. Laccases of Trametes pubescens MUT 2400 were very active against all the target micropollutants: except few cases, their concentration was reduced more than 60%. Chemical analysis and environmental risk do not always come together. To verify whether the treated wastewaters can represent a stressor for the aquatic ecosystem, toxicity was also evaluated. Raphidocelis subcapitata and Lepidium sativum tests showed a clear ecotoxicity reduction, even though they did not evenly respond. Two in vitro tests (E-screen test and MELN assay) were used to evaluate the estrogenic activity. Treatments already operating in the plant (e.g. activated sludge) partially reduced the estradiol equivalent concentration, and it was almost negligible after the laccases treatment. The results of this study suggest that laccases of T. pubescens are promising biocatalysts for the micropollutants transformation in wastewaters and surface waters.

Receptor-mediated estrogenicity of native and chemically dispersed crude oil determined using adapted microscale reporter gene assays

Endocrine disrupting compounds (EDCs) emerged as a major concern for water quality in the last decade and have been studied extensively since. Besides typical natural and synthetic estrogens also petroleum product compounds such as some PAHs have been identified as potential EDCs, revealing endocrine disruption to be a relevant mode of action for crude oil toxicity. Hence, in the context of a comprehensive retro- or prospective risk assessment of oil spills the implementation of mechanism-specific toxicity such as endocrine disruption is of high importance. To evaluate the exposure risk for the aquatic biota, research focuses on water-soluble fractions underlying an oil slick that could be simulated via water-accommodated fractions (WAF). Against this background human (ERα-CALUX®) and yeast based (A-YES®) reporter gene bioassays were successfully optimized for the application in estrogenicity evaluation of the water-accommodated fraction (WAF) from a crude oil. Combining different approaches, the estrogenicity of the WAFs from a naphthenic North Sea crude oil was tested with and without the addition of a chemical dispersant addressing specific aspects of estrogenicity including the influence of biotransformation capacities and different salinity conditions. Both the WAF free from droplets (LEWAF) as well as the chemically dispersed WAF (CEWAF) gave indications of an ER-mediated estrogenicity with much stronger ERα agonists in the CEWAF treatment. Resulting estradiol equivalents of the WAFs were above the established effect-based trigger values for both bioassays. Results indicate that the dispersant rather increased the fraction of ER-activating crude oil compounds instead of interacting with the receptor itself. Only slight changes in estrogenic responses were observed when cells capable of active metabolism (T47D) were used instead of cells without endogenous metabolism (U2-OS) in the recombinant ER transactivation CALUX assay. With the yeast cells a higher estrogenic activity was observed in the experiments under elevated salinity conditions (6‰), which was in contrast to previous expectations due to typical decrease in dissolved PAH fraction with increasing salinity (salting-out effect) but might be related to increased cell sensitivity.

Environmental Water Pollution, Endocrine Interference and Ecotoxicity of 4-tert-Octylphenol: A Review

4-tert-Octylphenol is a degradation product of non-ionic surfactants alkylphenol polyethoxylates as well as raw material for a number of industrial applications. It is a multimedia compound having been detected in all environmental compartments such as indoor air and surface waters. The pollutant is biodegradable, but certain degradation products are more toxic than the parent compound. Newer removal techniques from environmental waters have been presented, but they still require development for large-scale applications. Wastewater treatment by plant enzymes such as peroxidases offers promise in total removal of 4-tert-octylphenol leaving less toxic degradation products. The pollutant's endocrine interference has been well reported but more in oestrogens than in any other signalling pathways through which it is believed to exert toxicity on human and wildlife. In this paper we carried out a review of the activities of this pollutant in environmental waters, endocrine interference and relevance to its toxicities and concluded that inadequate knowledge of its endocrine activities impedes understanding of its toxicity which may frustrate current efforts at ridding the compound from the environment.

Experience Gained from Ecotoxicological Studies in the Seine River and Its Drainage Basin Over the Last Decade: Applicative Examples and Research Perspectives

The Seine River and its drainage basin are recognised as one of the most urbanised water systems in France. This chapter gathers typical applications of complementary ecotoxicological tools that were used in PIREN-Seine programmes for a decade to reflect the Seine River contamination as well as its biological repercussions on organisms. Ecotoxicological studies focused on both (1) specific bioassays and (2) (sub)-individual biological responses (i.e. biomarkers) measured in diverse taxa (i.e. crustaceans, mussels and fishes) representative of the trophic network. Experience gained from these studies made it possible to establish reference and threshold values for numerous biological endpoints. They now can be combined with chemical measurements within integrated models (i.e. the Weight of Evidence [WOE] approach) generating a global index of waterbody pollution. These biological endpoints today appear sufficiently relevant and mature to be proposed to water stakeholders as efficient tools to support environmental management strategies.

Towards Sustainable Environmental Quality: Priority Research Questions for the Australasian Region of Oceania

Environmental challenges persist across the world, including the Australasian region of Oceania, where biodiversity hotspots and unique ecosystems such as the Great Barrier Reef are common. These systems are routinely affected by multiple stressors from anthropogenic activities, and increasingly influenced by global megatrends (e.g., the food-energy-water nexus, demographic transitions to cities) and climate change. Here we report priority research questions from the Global Horizon Scanning Project, which aimed to identify, prioritize, and advance environmental quality research needs from an Australasian perspective, within a global context. We employed a transparent and inclusive process of soliciting key questions from Australasian members of the Society of Environmental Toxicology and Chemistry. Following submission of 78 questions, 20 priority research questions were identified during an expert workshop in Nelson, New Zealand. These research questions covered a range of issues of global relevance, including research needed to more closely integrate ecotoxicology and ecology for the protection of ecosystems, increase flexibility for prioritizing chemical substances currently in commerce, understand the impacts of complex mixtures and multiple stressors, and define environmental quality and ecosystem integrity of temporary waters. Some questions have specific relevance to Australasia, particularly the uncertainties associated with using toxicity data from exotic species to protect unique indigenous species. Several related priority questions deal with the theme of how widely international ecotoxicological data and databases can be applied to regional ecosystems. Other timely questions, which focus on improving predictive chemistry and toxicology tools and techniques, will be important to answer several of the priority questions identified here. Another important question raised was how to protect local cultural and social values and maintain indigenous engagement during problem formulation and identification of ecosystem protection goals. Addressing these questions will be challenging, but doing so promises to advance environmental sustainability in Oceania and globally.