Solid-phase extraction as sample preparation of water samples for cell-based and other in vitro bioassays

Comparative evaluation of SPE methods for biotoxicity assessment of water and wastewater: Linkage between chemical extracting efficiency and biotoxicity outcome

Biotoxicity assessment results of environmental waters largely depend on the sample extraction protocols that enrich pollutants to meet the effect-trigger thresholds of bioassays. However, more chemical mixture does not necessarily translate to higher combined biotoxicity. Thus, there is a need to establish the link between chemical extracting efficiency and biotoxicity outcome to standardize extraction methods for biotoxicity assessment of environmental waters. This study compares the performance of five different extraction phases in solid phase extraction (SPE), namely HLB, HLB+Coconut, C18 cartridge, C18 disk and Strata-X, and evaluated their chemical extracting efficiencies and biotoxicity outcomes. We quantitatively assessed cytotoxicity, acute toxicity, genotoxicity, estrogenic activity, and neurotoxicity of the extracts using in vitro bioassays and characterized the chemical extracting efficiencies of the SPE methods through chemical recoveries of 23 model compounds with different polarities and total organic carbon. Using Pareto ranking, we identified HLB+Coconut as the optimal SPE method, which exhibited the highest level of water sample biotoxicity and recovered the most chemicals in water samples. We found that the biotoxicity outcomes of the extracted water samples significantly and positively correlated with the chemical extracting efficiencies of the SPE methods. Moreover, we observed synchronous changing patterns in biotoxicity outcome and chemical extracting efficiencies in response to increasing sample volumes per cartridge (SVPC) during SPE. Our findings underscore that higher chemical extracting efficiency of SPE corresponds to higher biotoxicity outcome of environmental water samples, providing a scientific basis for standardization of SPE methods for adequate assessment of biotoxicities of environmental waters.

Migration of endocrine and metabolism disrupting chemicals from plastic food packaging

Plastics constitute a vast array of substances, with over 16000 known plastic chemicals, including intentionally and non-intentionally added substances. Thousands of chemicals, including toxic ones, are extractable from plastics, however, the extent to which these compounds migrate from everyday products into food or water remains poorly understood. This study aims to characterize the endocrine and metabolism disrupting activity, as well as the chemical composition of migrates from plastic food contact articles (FCAs) from four countries as significant sources of human exposure. Fourteen plastic FCAs covering seven polymer types with high global market shares were migrated into water and a water-ethanol mixture as food simulants according to European regulations. The migrates were analyzed using reporter gene assays for nuclear receptors relevant to human health and non-target chemical analysis to characterize the chemical composition. Chemicals migrating from each FCA interfered with at least two nuclear receptors, predominantly targeting pregnane X receptor (24/28 migrates). Moreover, peroxisome proliferator receptor gamma was activated by 19 out of 28 migrates, though mostly with lower potencies. Estrogenic and antiandrogenic activity was detected in eight and seven migrates, respectively. Fewer chemicals and less toxicity migrated into water compared to the water-ethanol mixture. However, 73 % of the 15 430 extractable chemical features also transferred into food simulants, and the water-ethanol migrates exhibited a similar toxicity prevalence compared to methanol extracts. The chemical complexity differed largely between FCAs, with 8 to 10631 chemical features migrating into food simulants. Using stepwise partial least squares regressions, we successfully narrowed down the list of potential active chemicals, identified known endocrine disrupting chemicals, such as triphenyl phosphate, and prioritized chemical features for further identification. This study demonstrates the migration of endocrine and metabolism disrupting chemicals from plastic FCAs into food simulants, rendering a migration of these compounds into food and beverages probable.

Water Quality Monitoring with the Multiplexed Assay MitoOxTox for Mitochondrial Toxicity, Oxidative Stress Response, and Cytotoxicity in AREc32 Cells

Mitochondria play a key role in the energy production of cells, but their function can be disturbed by environmental toxicants. We developed a cell-based mitochondrial toxicity assay for environmental chemicals and their mixtures extracted from water samples. The reporter gene cell line AREc32, which is frequently used to quantify the cytotoxicity and oxidative stress response of water samples, was multiplexed with an endpoint of mitochondrial toxicity. The disruption of the mitochondrial membrane potential (MMP) was quantified by high-content imaging and compared to measured cytotoxicity, predicted baseline toxicity, and activation of the oxidative stress response. Mitochondrial complex I inhibitors showed highly specific effects on the MMP, with minor effects on cell viability. Uncouplers showed a wide distribution of specificity on the MMP, often accompanied by specific cytotoxicity (enhanced over baseline toxicity). Mitochondrial toxicity and the oxidative stress response were not directly associated. The multiplexed assay was applied to water samples ranging from wastewater treatment plant (WWTP) influent and effluent and surface water to drinking and bottled water from various European countries. Specific effects on MMP were observed for the WWTP influent and effluent. This new MitoOxTox assay is an important complement for existing in vitro test batteries for water quality testing and has potential for applications in human biomonitoring.

Estrogenic activity in wastewater treatment plants through in vitro effect-based assays: Insights into extraction phase

Effluents of wastewater treatment plants can abundantly spread endocrine disrupting chemicals in the environment. To improve water quality monitoring, the use of effect-based tools that measure estrogenic activity has been suggested, however their results could be influenced by different factors. This study compared the estrogenic activity of wastewater samples extracted with two stationary phases and tested with two in vitro effect-based assays to investigate whether and how stationary phases and assays could influence biomonitoring data. During four seasonal periods, the effluents of six WWTPs located in northern Italy were sampled. After the extraction using two different stationary phases (HLB, C18), the samples (n = 72) were tested using two effect-based assays: a gene reporter luciferase assay on mammalian cells (MELN) and yeast estrogen screen assay (YES). The results showed that estrogenic activity of HLB extracts was significantly different from the activity of C18 extracts, suggesting that extraction phase can influence biomonitoring data. Moreover, the estrogenic activity was overall higher using gene reporter MELN assay than using YES assay, suggesting that, due to difference in cell membrane permeability and metabolic activation, the applied cell model can affect the biomonitoring results. Finally, from the comparison between the activity of the final effluent and the environmentally safe estrogenic levels in surface waters, MELN data suggested that the activity of this effluent may pose an environmental risk, while YES data showed that it should not be considered a threat to the receiving surface waters. This study pointed out that a standardized approach is needed to assess the estrogenic activity of waters; it reported important data to select the most suitable stationary phase for samples extraction (samples extracted with C18 sorbent showed higher estradiol equivalent concentration values) and the most appropriate bioassay (gene reporter luciferase MELN assay was more sensitive than YES assay) to assess the environmental risk, thus protecting human health.

Recovery of 400 Chemicals with Three Extraction Methods for Low Volumes of Human Plasma Quantified by Instrumental Analysis and In Vitro Bioassays

Human biomonitoring studies are important for understanding adverse health outcomes caused by exposure to chemicals. Complex mixtures of chemicals detected in blood - the blood exposome - may serve as proxies for systemic exposure. Ideally, several analytical methods are combined with in vitro bioassays to capture chemical mixtures as diverse as possible. How many and which (bio)analyses can be performed is limited by the sample volume and compatibility of extraction and (bio)analytical methods. We compared the extraction efficacy of three extraction methods using pooled human plasma spiked with >400 organic chemicals. Passive equilibrium sampling (PES) with polydimethylsiloxane (PDMS) followed by solid phase extraction (PES + SPE), SPE alone (SPE), and solvent precipitation (SolvPrec) were compared for chemical recovery in LC-HRMS and GC-HRMS as well as effect recovery in four mammalian cell lines (AhR-CALUX, SH-SY5Y, AREc32, PPARγ-BLA). The mean chemical recoveries were 38% for PES + SPE, 27% for SPE, and 61% for SolvPrec. PES + SPE enhanced the mean chemical recovery compared to SPE, especially for neutral hydrophobic chemicals. PES + SPE and SolvPrec had effect recoveries of 100-200% in all four cell lines, outperforming SPE, which had 30-100% effect recovery. Although SolvPrec has the best chemical recoveries, it does not remove matrix like inorganics or lipids, which might pose problems for some (bio)analytical methods. PES + SPE is the most promising method for sample preparation in human biomonitoring as it combines good recoveries with cleanup, enrichment, and potential for high throughput.

Water, Water Everywhere, but Every Drop Unique: Challenges in the Science to Understand the Role of Contaminants of Emerging Concern in the Management of Drinking Water Supplies

The protection and management of water resources continues to be challenged by multiple and ongoing factors such as shifts in demographic, social, economic, and public health requirements. Physical limitations placed on access to potable supplies include natural and human-caused factors such as aquifer depletion, aging infrastructure, saltwater intrusion, floods, and drought. These factors, although varying in magnitude, spatial extent, and timing, can exacerbate the potential for contaminants of concern (CECs) to be present in sources of drinking water, infrastructure, premise plumbing and associated tap water. This monograph examines how current and emerging scientific efforts and technologies increase our understanding of the range of CECs and drinking water issues facing current and future populations. It is not intended to be read in one sitting, but is instead a starting point for scientists wanting to learn more about the issues surrounding CECs. This text discusses the topical evolution CECs over time (Section 1), improvements in measuring chemical and microbial CECs, through both analysis of concentration and toxicity (Section 2) and modeling CEC exposure and fate (Section 3), forms of treatment effective at removing chemical and microbial CECs (Section 4), and potential for human health impacts from exposure to CECs (Section 5). The paper concludes with how changes to water quantity, both scarcity and surpluses, could affect water quality (Section 6). Taken together, these sections document the past 25 years of CEC research and the regulatory response to these contaminants, the current work to identify and monitor CECs and mitigate exposure, and the challenges facing the future.

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.

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.

Application of Effect-Based Methods to Water Quality Monitoring: Answering Frequently Asked Questions by Water Quality Managers, Regulators, and Policy Makers

Effect-based methods (EBM) have great potential for water quality monitoring as they can detect the mixture effects of all active known and unknown chemicals in a sample, which cannot be addressed by chemical analysis alone. To date, EBM have primarily been applied in a research context, with a lower level of uptake by the water sector and regulators. This is partly due to concerns regarding the reliability and interpretation of EBM. Using evidence from the peer-reviewed literature, this work aims to answer frequently asked questions about EBM. The questions were identified through consultation with the water industry and regulators and cover topics related to the basis for using EBM, practical considerations regarding reliability, sampling for EBM and quality control, and what to do with the information provided by EBM. The information provided in this work aims to give confidence to regulators and the water sector to stimulate the application of EBM for water quality monitoring.

Modernizing persistence-bioaccumulation-toxicity (PBT) assessment with high throughput animal-free methods

The assessment of persistence (P), bioaccumulation (B), and toxicity (T) of a chemical is a crucial first step at ensuring chemical safety and is a cornerstone of the European Union's chemicals regulation REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals). Existing methods for PBT assessment are overly complex and cumbersome, have produced incorrect conclusions, and rely heavily on animal-intensive testing. We explore how new-approach methodologies (NAMs) can overcome the limitations of current PBT assessment. We propose two innovative hazard indicators, termed cumulative toxicity equivalents (CTE) and persistent toxicity equivalents (PTE). Together they are intended to replace existing PBT indicators and can also accommodate the emerging concept of PMT (where M stands for mobility). The proposed "toxicity equivalents" can be measured with high throughput in vitro bioassays. CTE refers to the toxic effects measured directly in any given sample, including single chemicals, substitution products, or mixtures. PTE is the equivalent measure of cumulative toxicity equivalents measured after simulated environmental degradation of the sample. With an appropriate panel of animal-free or alternative in vitro bioassays, CTE and PTE comprise key environmental and human health hazard indicators. CTE and PTE do not require analytical identification of transformation products and mixture components but instead prompt two key questions: is the chemical or mixture toxic, and is this toxicity persistent or can it be attenuated by environmental degradation? Taken together, the proposed hazard indicators CTE and PTE have the potential to integrate P, B/M and T assessment into one high-throughput experimental workflow that sidesteps the need for analytical measurements and will support the Chemicals Strategy for Sustainability of the European Union.

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.

In vitro bioanalytical assessment of the occurrence and removal of bioactive chemicals in municipal wastewater treatment plants in Korea

Effluents of wastewater treatment plants (WWTPs) contain various organic micropollutants, some of which can exert negative effects on the quality of receiving waters or drinking water sources. This study monitored two full-scale WWTPs in Korea for the occurrence and removal of bioactive chemicals for a one-year period using a battery of in vitro bioassays as a complementary approach to chemical analysis. Bioassays covering different endpoints were employed, such as hormone receptor activation (AR and ERα), xenobiotic metabolism (PAH and PXR), oxidative stress response (Nrf2), and cytotoxicity. The WWTP influents showed AR, ERα, and PAH activities at ng/L - μg/L and PXR and Nrf2 activities at μg/L - mg/L as bioanalytical equivalent concentrations of a reference compound for each bioassay. These bioactivities decreased along with the WWTP treatment train, with significant removals achieved by the secondary biological treatment processes. Cytotoxicity was observed only for some municipal wastewater (M-WWTP) influents but was below the limit of quantification for most cases. The influent and effluent bioactivities observed in this study were mostly comparable to those reported in other WWTPs in the literature. Comparison of the bioactivities with the effect-based trigger (EBT) values indicates that the impact of WWTP effluents on receiving water quality was low for most endpoints. For Nrf2, however, further investigation is required to evaluate the observed high bioactivities compared with the current EBT. The observed ERα activity could partly be explained by the presence of some steroid estrogens. Overall, our results contribute to an important database for the concentrations and removal efficiencies of bioactive chemicals in WWTPs and demonstrate bioassays as a useful tool for urban water quality monitoring.

Monitoring Mixture Effects of Neurotoxicants in Surface Water and Wastewater Treatment Plant Effluents with Neurite Outgrowth Inhibition in SH-SY5Y Cells

Cell-based assays covering environmentally relevant modes of action are widely used for water quality monitoring. However, no high-throughput assays are available for testing developmental neurotoxicity of water samples. We implemented an assay that quantifies neurite outgrowth, which is one of the neurodevelopmental key events, and cell viability in human neuroblastoma SH-SY5Y cells using imaging techniques. We used this assay for testing of extracts of surface water collected in agricultural areas during rain events and effluents from wastewater treatment plants (WWTPs), where more than 200 chemicals had been quantified. Forty-one chemicals were tested individually that were suspected to contribute to the mixture effects among the detected chemicals in environmental samples. Sample sensitivity distributions indicated higher neurotoxicity for surface water samples than for effluents, and the endpoint of neurite outgrowth inhibition was six times more sensitive than cytotoxicity in the surface water samples and only three times more sensitive in the effluent samples. Eight environmental pollutants showed high specificity, and those ranged from pharmaceuticals (mebendazole and verapamil) to pesticides (methiocarb and clomazone), biocides (1,2-benzisothiazolin-3-one), and industrial chemicals (N-methyl-2-pyrrolidone, 7-diethylamino-4-methylcoumarin, and 2-(4-morpholinyl)benzothiazole). Although neurotoxic effects were newly detected for some of our test chemicals, less than 1% of the measured effects were explained by the detected and toxicologically characterized chemicals. The neurotoxicity assay was benchmarked against other bioassays: activations of the aryl hydrocarbon receptor and the peroxisome proliferator-activated receptor were similar in sensitivity, highly sensitive and did not differ much between the two water types, with surface water having slightly higher effects than the WWTP effluent. Oxidative stress response mirrored neurotoxicity quite well but was caused by different chemicals in the two water types. Overall, the new cell-based neurotoxicity assay is a valuable complement to the existing battery of effect-based monitoring tools.

Anoxybacillus flavithermus loaded ɣ-Fe2O3 magnetic nanoparticles as an efficient magnetic sorbent for the preconcentrations of Cu(II) and Mn(II)

It was hypothesized that -iron( oxide nanoparticles (ɣ-Fe₂O₃ NPs) functionalized with Anoxybacillus flavithermus (A. flavithermus) as an effective magnetic sorbent for the preconcentrations of toxic metal ions. It is clear to conclude that the main novelty of this study is that ɣ-Fe₂O₃ NPs loaded with A. flavithermus is selective-specific for Cu(II), Mn(II). Structural functional groups of the samples were elucidated by FTIR, and SEM. Significant experimental parameters were investigated in detail. 0.2 mL min^-1 of flow rate, 5 mL of 1 M of hydrochloric acid as eluent, 150 mg biogenic mass sample, and 150 mg ɣ-Fe₂O₃ NPs for supporting material were found as the best conditions. This developed method has been tested and verified using certified and standard reference materials. As a result of the studies, the pre-concentration factor of the Cu(II), Mn(II) metals was calculated as 40. All measurements showed that the developed solid-phase extraction (SPE) columns are available for 32 cycles. The use of ɣ-Fe₂O₃ NPs equipped with A. flavithermus as an effective magnetic sorbent for the first measurements of ions was thoroughly studied. In order of the biosorption capacities were calculated as 26.0, and 30.3 mg/g for Cu(II), Mn(II), respectively. The developed method for specifying the samples showed excellent to excellent results.

Organic Anion Detection with Functionalized SERS Substrates via Coupled Electrokinetic Preconcentration, Analyte Capture, and Charge Transfer

Detecting ultralow concentrations of anionic analytes in solution by surface-enhanced Raman spectroscopy (SERS) remains challenging due to their low affinity for SERS substrates. Two strategies were examined to enable in situ, liquid phase detection using 5(6)-carboxyfluorescein (5(6)-FAM) as a model analyte: functionalization of a gold nanopillar substrate with cationic cysteamine self-assembled monolayer (CA-SAM) and electrokinetic preconcentration (EP-SERS) with potentials ranging from 0 to +500 mV. The CA-SAM did not enable detection without an applied field, likely due to insufficient accumulation of 5(6)-FAM on the substrate surface limited by passive diffusion. 5(6)-FAM could only be reliably detected with an applied electric field with the charged molecules driven by electroconvection to the substrate surface and the SERS intensity following the Langmuir adsorption model. The obtained limits of detection (LODs) with an applied field were 97.5 and 6.4 nM on bare and CA-SAM substrates, respectively. For the CA-SAM substrates, both the ligand and analyte displayed an ∼15-fold signal enhancement with an applied field, revealing an additional enhancement due to charge-transfer resonance taking place between the metal and 5(6)-FAM that improved the LOD by an order of magnitude.

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.

Effects of leachates from UV-weathered microplastic on the microalgae Scenedesmus vacuolatus

Plastics undergo successive fragmentation and chemical leaching steps in the environment due to weathering processes such as photo-oxidation. Here, we report the effects of leachates from UV-irradiated microplastics towards the chlorophyte Scenedesmus vacuolatus. The microplastics tested were derived from an additive-containing electronic waste (EW) and a computer keyboard (KB) as well as commercial virgin polymers with low additive content, including polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS). Whereas leachates from additive-containing EW and KB induced severe effects, the leachates from virgin PET, PP, and PS did not show substantial adverse effects in our autotrophic test system. Leachates from PE reduced algae biomass, cell growth, and photosynthetic activity. Experimental data were consistent with predicted effect concentrations based on the ionization-corrected liposome/water distribution ratios (D_lip/w) of polymer degradation products of PE (mono- and dicarboxylic acids), indicating that leachates from weathering PE were mainly baseline toxic. This study provides insight into algae toxicity elicited by leachates from UV-weathered microplastics of different origin, complementing the current particle- vs. chemical-focused research towards the toxicity of plastics and their leachates.

Microorganisms as Bio-SPE Materials for Extraction of Pharmaceutical Drugs: Mechanism of Extraction

In solid-phase extraction (SPE), the extraction materials depend on the physicochemical interactions to obtain the target analytes from complex systems. However, many matrix interferences existing in real samples influence the extraction efficiency through these common interactions. Therefore, extraction materials based on more special interactions for biological systems need to be developed. In this work, live microorganisms including Escherichia coli and Staphylococcus aureus were considered as the potential biological SPE (bio-SPE) materials with their biological functions in the live state. To study the enrichment and selectivity of the bio-SPE, four antibacterial drugs and two non-antibacterial drugs were employed as the target analytes. The enrichment factor (EF) was used as the evaluation index. The results showed that when using chlorpheniramine (CPM) and ofloxacin (OFLO), the enrichment capacity of E. coli was better than that of S. aureus. When extracting a single analyte, the enrichment ability of E. coli for CPM was significantly higher than other analytes, and the EF was 8.5. In a mixture solution of antibacterial analytes, OFLO could be enriched mostly by E. coli. However, in the mixture solution of antibacterial and non-antibacterial analytes, CPM was enriched more than that of antibacterial analytes. In real rat plasma, bio-SPE using live E. coli could obviously extract CPM, while traditional liquid-liquid extraction could not. The confocal microscopy results showed that the extraction mechanism may not only depend on the surface adsorption of bacteria with analytes but also on the uptake into bacteria. This provides a valuable basis for the development of more biological separation materials based on biological interactions.

Effect-based evaluation of ozone treatment for removal of micropollutants and their transformation products in waste water

The aim of this interdisciplinary research project in North Rhine-Westphalia (NRW), Germany, entitled "Elimination of pharmaceuticals and organic micropollutants from waste water" involved the conception of cost-effective and innovative waste-water cleaning methods. In this project in vitro assays, in vivo assays and chemical analyses were performed on three municipal waste-water treatment plants (WWTP). This publication focuses on the study of the in vitro bioassays. Cytotoxic, estrogenic, genotoxic and mutagenic effects of the original as well as enriched water samples were monitored before and after wastewater treatment steps using MTT and PAN I, ER Calux and A-YES, micronucleus and Comet assays as well as AMES test. In most cases, the measured effects were reduced after ozonation, but in general, the biological response depended upon the water composition of the WWTP, in particular on the formed by-products and concentration of micropollutants. In order to be able to assess the genotoxic and/or mutagenic potential of waste-water samples using bioassays like Ames test, Comet assay or micronucleus test an enrichment of the water sample via solid-phase extraction is recommended. This is in agreement with previous studies such as the "ToxBox"-Project of the Environmental Agency in Germany.

Suspended Particulate Matter-A Source or Sink for Chemical Mixtures of Organic Micropollutants in a Small River under Baseflow Conditions?

Suspended particulate matter (SPM) plays an important role in the fate of organic micropollutants in rivers during rain events, when sediments are remobilized and turbid runoff components enter the rivers. Under baseflow conditions, the SPM concentration is low and the contribution of SPM-bound contaminants to the overall risk of organic contaminants in rivers is assumed to be negligible. To challenge this assumption, we explored if SPM may act as a source or sink for all or specific groups of organic chemicals in a small river. The concentrations of over 600 contaminants and the mixture effects stemming from all chemicals in in vitro bioassays were measured for river water, SPM, and the surface sediment after solid-phase extraction or exhaustive solvent extraction. The bioavailable fractions of chemicals and mixture effects were estimated after passive equilibrium sampling of enriched SPM slurries and sediments in the lab. Dissolved compounds dominated the total chemical burden in the water column (water plus SPM) of the river, whereas SPM-bound chemicals contributed up to 46% of the effect burden even if the SPM concentration in rivers was merely 1 mg/L. The equilibrium between water and SPM was still not reached under low-flow conditions with SPM as a source of water contamination. The ratios of SPM-associated to sediment-associated neutral and hydrophobic chemicals as well as the ratios of the mixture effects expressed as bioanalytical equivalent concentrations were close to 1, suggesting that the surface sediment can be used as a proxy for SPM under baseflow conditions when the sampling of a large amount of water to obtain sufficient SPM cannot be realized.

Elevated Levels of Oxidative Nucleic Acid Modification Markers in Urine From Gastric Cancer Patients: Quantitative Analysis by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

Oxidative nucleic acid modifications have attracted increasing attention in recent years since they have been found to be related to a number of diseases including cancer. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) and 8-hydroxyguanosine (8-OHG) are the typical markers of oxidative modification of DNA and RNA, respectively, and they are emerging biomarkers for the early detection of diseases. Urine is a favored biofluid for biomarker discovery due to its noninvasiveness to patients. Accurate quantification of these oxidative nucleic acid modifications still has challenges because their amounts in urine are very low and the interferences in urine samples are complicated. Herein, we developed and validated an accurate and robust solid-phase extraction (SPE) coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantification of these oxidative nucleic acid modifications in human urine. Stable isotope dilution strategy was utilized and the method shows good precision on intraday and interday measurements. Meanwhile, recovery was satisfactory by utilizing the Oasis hydrophilic-lipophilic balance (HLB) cartridge for sample pretreatment at three spiked levels. We successfully quantified urinary 8-OHdG and 8-OHG from 60 gastric cancer patients and 70 healthy controls by using this method. The measured contents of 8-OHdG and 8-OHG in urine from gastric cancer patients are both increased, compared with those in urine from healthy controls, indicating these oxidative nucleic acid modifications could act as potential non-invasive markers for early diagnosis of gastric cancer. Moreover, the present study will stimulate investigations of the effects of oxidative stress and nucleic acid modifications on the initiation and progression of gastric cancer.

Application of the Sea Urchin Embryo Test in Toxicity Evaluation and Effect-Directed Analysis of Wastewater Treatment Plant Effluents

Sea urchin embryo assay was used to assess general toxicity at four wastewater treatment plant effluents of Biscay (Gorliz, Mungia, Gernika, and Galindo), and within the tested range, all the extracts showed embryo growth inhibition and skeleton malformation activities with EC₅₀ values, in relative enrichment factor units, between 1.1-16.8 and 1.1-8.8, respectively. To identify the causative compounds, effect-directed analysis was successfully applied for the first time using a sea urchin embryo test to the secondary treatment of the Galindo effluent. To this end, two subsequent fractionation steps were performed using C18 (21 fractions) and aminopropyl columns (15 fractions). By this fractionation, the number of features detected by LC-HRMS in the raw sample was drastically reduced from 1500 to 9, and among them, two pesticides (mexacarbate, 17 ng/L, and fenpropidin, 23 ng/L), two antidepressants (amitriptyline, 304 ng/L, and paroxetine, 26 ng/L), and two anthelmintic agents (mebendazole, 65 ng/L, and albendazole, 48 ng/L) could be identified in the two toxic fractions. The artificial mixture of the identified six compounds could explain 79% of the observed effect, with albendazole and paroxetine as the predominant contributors (49% and 49%, respectively) affecting the sea urchin embryogenesis activity.

Assessing the Mixture Effects in In Vitro Bioassays of Chemicals Occurring in Small Agricultural Streams during Rain Events

Rain events may impact the chemical pollution burden in rivers. Forty-four small streams in Germany were profiled during several rain events for the presence of 395 chemicals and five types of mixture effects in in vitro bioassays (cytotoxicity; activation of the estrogen, aryl hydrocarbon, and peroxisome proliferator-activated receptors; and oxidative stress response). While these streams were selected to cover a wide range of agricultural impacts, in addition to the expected pesticides, wastewater-derived chemicals and chemicals typical for street runoff were detected. The unexpectedly high estrogenic effects in many samples indicated the impact by wastewater or overflow of combined sewer systems. The 128 water samples exhibited a high diversity of chemical and effect patterns, even for different rain events at the same site. The detected 290 chemicals explained only a small fraction (<8%) of the measured effects. The experimental effects of the designed mixtures of detected chemicals that were expected to dominate the mixture effects of detected chemicals were consistent with predictions for concentration addition within a factor of two for 94% of the mixtures. Overall, the burden of chemicals and effects was much higher than that previously detected in surface water during dry weather, with the effects often exceeding proposed effect-based trigger values.

A Tiered Approach for Screening and Assessment of Environmental Mixtures by Omics and In Vitro Assays

New methodology approaches with a broad coverage of the biological effects are urgently needed to evaluate the safety of the universe of environmentally relevant chemicals. Here, we propose a tiered approach incorporating transcriptomics and in vitro bioassays to assess environmental mixtures. The mixture samples and the perturbed biological pathways are prioritized by concentration-dependent transcriptome (CDT) and then used to guide the selection of in vitro bioassays for toxicant identification. To evaluate omics' screening capability, we first applied a CDT technique to test mixture samples by HepG2 and MCF7 cells. The effect recoveries of large-volume solid-phase extraction on the overall bioactivity of the mixture were 48.9% in HepG2 and 58.3% in MCF7. The overall bioactivity potencies obtained by transcriptomics were positively correlated with the panel of 8 bioassays among 14 mixture samples combined with the previous data. Transcriptomics could predict their activation status (AUC = 0.783) and the relative potency (p < 0.05) of bioassays for four of the eight receptors (AhR, ER, AR, and Nrf2). Furthermore, the CDT identified other biological pathways perturbated by mixture samples, such as the pathway related to TP53, CAR, FXR, HIF, THRA, etc. Overall, this study demonstrates the potential of concentration-dependent omics for effect-based water quality assessment.

Recent Progress in Surface-Enhanced Raman Scattering for the Detection of Chemical Contaminants in Water

Water is a matter of vital importance for all developed countries due to the strong impact on human health and aquatic, wetlands and terrestrial environments. Therefore, the monitoring of water quality is of tremendous importance. The enormous advantages that Surface-enhanced Raman scattering (SERS) spectroscopy offers, such as fingerprint recognition, multiplex capabilities, high sensitivity, and selectivity or non-destructive testing, make this analytical tool very attractive for this purpose. This minireview aims to provide a summary of current approaches for the implementation of SERS sensors in monitoring organic and inorganic pollutants in water. In addition, we briefly highlight current challenges and provide an outlook for the application of SERS in environmental monitoring.

Occurrence of selected endocrine disrupting compounds in the eastern cape province of South Africa

Endocrine-disrupting compounds are attracting attention worldwide because of their effects on living things in the environment. Ten endocrine disrupting compounds: 4-nonylphenol, 2,4-dichlorophenol, estrone, 17β-estradiol, bisphenol A, 4-tert-octylphenol, triclosan, atrazine, imidazole and 1,2,4-triazole were investigated in four rivers and wastewater treatment plants in this study. Rivers were sampled at upstream, midstream and downstream reaches, while the influent and effluent samples of wastewater were collected from treatment plants near the receiving rivers. Sample waters were freeze-dried followed by extraction of the organic content and purification by solid-phase extraction. Concentrations of the compounds in the samples were determined with ultra-high performance liquid chromatography-tandem mass spectrometry. The instrument was operated in the positive electrospray ionization (ESI) mode. The results showed that these compounds are present in the samples with nonylphenol > dichlorophenol > bisphenol A > triclosan > octylphenol > imidazole > atrazine > triazole > estrone > estradiol. Nonylphenol has its highest concentration of 6.72 μg/L in King Williams Town wastewater influent and 2.55 μg/L in midstream Bloukrans River. Dichlorophenol has its highest concentration in Alice wastewater influent with 2.20 μg/L, while it was 0.737 μg/L in midstream Bloukrans River. Uitenhage wastewater effluent has bisphenol A concentration of 1.684 μg/L while it was 0.477 μg/L in the downstream samples of the Bloukrans River. Generally, the upstream samples of the rivers had lesser concentrations of the compounds. The wastewater treatment plants were not able to achieve total removal of the compounds in the wastewater while runoffs and wastes dump from the cities contributed to the concentrations of the compounds in the rivers.

Tracking complex mixtures of chemicals in our changing environment

Chemicals have improved our quality of life, but the resulting environmental pollution has the potential to cause detrimental effects on humans and the environment. People and biota are chronically exposed to thousands of chemicals from various environmental sources through multiple pathways. Environmental chemists and toxicologists have moved beyond detecting and quantifying single chemicals to characterizing complex mixtures of chemicals in indoor and outdoor environments and biological matrices. We highlight analytical and bioanalytical approaches to isolating, characterizing, and tracking groups of chemicals of concern in complex matrices. Techniques that combine chemical analysis and bioassays have the potential to facilitate the identification of mixtures of chemicals that pose a combined risk.

Baseline Toxicity and Volatility Cutoff in Reporter Gene Assays Used for High-Throughput Screening

Most studies using high-throughput in vitro cell-based bioassays tested chemicals up to a certain fixed concentration. It would be more appropriate to test up to concentrations predicted to elicit baseline toxicity because this is the minimal toxicity of every chemical. Baseline toxicity is also called narcosis and refers to nonspecific intercalation of chemicals in biological membranes, leading to loss of membrane structure and impaired functioning of membrane-related processes such as mitochondrial respiration. In cells, baseline toxicity manifests as cytotoxicity, which was quantified by a robust live-cell imaging method. Inhibitory concentrations for baseline toxicity varied by orders of magnitude between chemicals and were described by a simple quantitative structure activity relationship (QSAR) with the liposome-water partition constant as a sole descriptor. The QSAR equations were remarkably similar for eight reporter gene cell lines of different cellular origin, six of which were used in Tox21. Mass-balance models indicated constant critical membrane concentrations for all cells and all chemicals with a mean of 69 mmol·kg_lip^-1(95% CI: 49-89), which is in the same range as for bacteria and aquatic organisms and consistent with the theory of critical membrane burden of narcosis. The challenge of developing baseline QSARs for cell lines is that many confirmed baseline toxicants are rather volatile. We deduced from cytotoxicity experiments with semi-volatile chemicals that only chemicals with medium-air partition constants >10,000 L/L can be tested in standard robotic setups without appreciable loss of effect. Chemicals just below that cutoff showed crossover effects in neighboring wells, whereas the effects of chemicals with lower medium-air partition constants were plainly lost. Applying the "volatility cut-off" to >8000 chemicals tested in Tox21 indicated that approximately 20% of Tox21 chemicals could have partially been lost during the experiments. We recommend applying the baseline QSARs together with volatility cut-offs for experimental planning of reporter gene assays, that is, to dose only chemicals with medium-air partition constants >10,000 at concentrations up to the baseline toxicity level.

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.

Solid-phase extraction of estrogens and herbicides from environmental waters for bioassay analysis-effects of sample volume on recoveries

Ecotoxicological screening of surface waters can involve multiple analyses using multiple bioassay and chemical analytical methods that require enriched samples to reach low concentrations. Such broad screening of the same sample necessitates sufficient sample volume-typically several liters-to produce a sufficient amount of enriched sample. Often, this is achieved by performing parallel solid-phase extractions (SPE) where extracts are combined into a pool-this is a laborious process. In this study, we first validated our existing SPE method for the chemical recovery of an extended set of compounds. We spiked four estrogenic compounds and 11 herbicides to samples from independent rivers (1 L) and wastewater treatment plant effluents (0.5 L). Then, we investigated the effect of increased sample loading of the SPE cartridges on both chemical and biological recoveries by comparing the validated volumes with four times larger sample volumes (i.e., 4 L river water and 2 L effluent). Samples were analyzed by LC-MS/MS and three bioassays: an estrogen receptor transactivation assay (ERα-CALUX), the combined algae test, and a bacterial bioluminescence inhibition assay. Our existing SPE method was found to be suitable for enriching the extended set of estrogens and herbicides in river water and effluents with near to perfect chemical recoveries (~ 100%), except for the herbicide metribuzin (46 ± 19%). In the large volume river and effluent samples, the biological activities and concentrations of the spiked compounds were between 87 and 104% of those measured with the lower sample loading, which is adequate. In addition, the ratio between the large and original volume SPE method for the non-target endpoint (bacterial bioluminescence inhibition) was acceptable (on average 82 ± 9%). Results indicate that our current water extraction method can be applied to up to four times larger sample volumes, resulting in four times more extract volumes, without significant reductions in recoveries for the tested estrogens and herbicides. Graphical abstract ᅟ.

Risk-based approach in the revised European Union drinking water legislation: Opportunities for bioanalytical tools

A plethora of in vitro bioassays are developed in the context of chemical risk assessment and clinical diagnostics to test effects on different biological processes. Such assays can also be implemented in effect-based monitoring (EBM) of (drinking) water quality alongside chemical analyses. Effects-based monitoring can provide insight into risks for the environment and human health associated with exposure to (unknown) complex, low-level mixtures of micropollutants, which fits in the risk-based approach that was recently introduced in the European Drinking Water Directive. Some challenges remain, in particular those related to selection and interpretation of bioassays. For water quality assessment, carcinogenesis, adverse effects on reproduction and development, effects on xenobiotic metabolism, modulation of hormone systems, DNA reactivity, and adaptive stress responses are considered the most relevant toxicological endpoints. An evaluation procedure of the applicability and performance of in vitro bioassays for water quality monitoring, based on existing information, has been developed, which can be expanded with guidelines for experimental evaluations. In addition, a methodology for the interpretation of in vitro monitoring data is required, because the sensitivity of specific in vitro bioassays in combination with sample concentration may lead to responses of chemicals (far) below exposure concentrations that are relevant for human health effects. Different approaches are proposed to derive effect-based trigger values (EBTs), including EBTs based on (1) relative ecotoxicity potency, (2) health-based threshold values for chronic exposure in humans and kinetics of reference chemicals, and (3) read-across from (drinking) water guideline values. Effects-based trigger values need to be chosen carefully in order to be sufficiently but not overly conservative to indicate potential health effects. Consensus on the crucial steps in the selection and interpretation of in vitro bioassay data will facilitate implementation and legal embedding in the context of water quality monitoring of such assays in EBM strategies. Integr Environ Assess Manag 2019;15:126-134. © 2018 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

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.

Fast and simple determination of moroxydine residues in pig and chicken samples by ultra-performance liquid chromatography-tandem mass spectrometry

A general solid-phase extraction (SPE) method using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the determination of moroxydine residues in pig and chicken samples has been developed. After extraction and purification of real samples, moroxydine residues were detected using a hydrophobic interaction liquid chromatography column with an optimised mobile phase composition. The extraction reagents, the kind of SPE columns and the type of eluents were optimised to achieve the maximum extraction efficiency. The matrix effects from the animal tissue influenced the quality of the quantitative data obtained. Under the optimised conditions, the moroxydine residues in pig and chicken samples spiked at three levels (1.0 μg/kg, 5.0 μg/kg and 10.0 μg/kg) were determined with good recoveries (61.5%-105.4%) and adequate relative standard deviations (3.2%-13.0%). In pig and chicken samples, the limit of detection (LOD) was 0.3 μg/kg, and the limit of quantification (LOQ) was 1.0 μg/kg. A sufficiently linear relationship in the range of 1.0 μg/kg-20.0 μg/kg was achieved with a good correlation coefficient (R² ≥ 0.99).

The advantages of linear concentration-response curves for in vitro bioassays with environmental samples

In vitro assays and high-throughput screening (HTS) tools are increasingly being employed as replacements for animal testing, but most concentration-response curves are still evaluated with models developed for animal testing. We argue that application of in vitro assays, particularly reporter gene assays, to environmental samples can benefit from a different approach to concentration-response modeling. First, cytotoxicity often occurs at higher concentrations, especially for weakly acting compounds and in complex environmental mixtures with many components. In these cases, specific effects can be masked by cytotoxicity. Second, for many HTS assays, low effect levels can be precisely quantified because of the low variability of controls in cell-based assays and the opportunity to run many concentrations and replicates when using high-density well-plate formats (e.g., 384 or more wells per plate). Hence, we recommend focusing concentration-response modeling on the lower portion of the concentration-response curve, which is approximately linear. Effect concentrations derived from low-effect level linear concentration-response models facilitate simple derivation of relative effect potencies and the correct application of mixture toxicity models in the calculation of bioanalytical equivalent concentrations. Environ Toxicol Chem 2018;37:2273-2280. © 2018 SETAC.

Towards a holistic and solution-oriented monitoring of chemical status of European water bodies: how to support the EU strategy for a non-toxic environment?

The definition of priority substances (PS) according to the Water Framework Directive (WFD) helped to remove many of these chemicals from the market and to reduce their concentrations in the European water bodies. However, it could not prevent that many of these chemicals have been replaced by others with similar risks. Today, monitoring of the PS-based chemical status according to WFD covers only a tiny fraction of toxic risks, extensively ignores mixture effects and lacks incentives and guidance for abatement. Thus, we suggest complement this purely status-related approach with more holistic and solution-oriented monitoring, which at the same time helps to provide links to the ecological status. Major elements include (1) advanced chemical screening techniques supporting mixture risk assessment and unraveling of source-related patterns in complex mixtures, (2) effect-based monitoring for the detection of groups of chemicals with similar effects and the establishment of toxicity fingerprints, (3) effect-directed analysis of drivers of toxicity and (4) to translate chemical and toxicological fingerprints into chemical footprints for prioritization of management measures. The requirement of more holistic and solution-oriented monitoring of chemical contamination is supported by the significant advancement of appropriate monitoring tools within the last years. Non-target screening technology, effect-based monitoring and basic understanding of mixture assessment are available conceptually and in research but also increasingly find their way into practical monitoring. Substantial progress in the development, evaluation and demonstration of these tools, for example, in the SOLUTIONS project enhanced their acceptability. Further advancement, integration and demonstration, extensive data exchange and closure of remaining knowledge gaps are suggested as high priority research needs for the next future to bridge the gap between insufficient ecological status and cost-efficient abatement measures.