Future water quality monitoring--adapting tools to deal with mixtures of pollutants in water resource management

Capturing temporal variation in aquatic ecotoxicological risks: Chemical- versus effect-based assessment

The integration of effect-based and chemical profiling has been advocated to assess the potential ecotoxicological risks posed by chemical mixtures present in aquatic ecosystems. However, the concentrations of contaminants in surface waters can vary greatly over time and space, making it challenging to ensure risk assessment. Although the first results are promising, it has not yet been proven that these combined approaches are also capable of capturing temporal variation in aquatic ecotoxicological risks. The present study aimed to test this by combining passive time-integrative sampling with effect-based and chemical-analytical techniques in agricultural waterways. Silicone rubber sheets and polar organic chemical integrative samplers (POCIS) were deployed in four agricultural water bodies over four consecutive six-week periods. Passive sampler extracts were analysed using a battery of 22 in vitro and in vivo bioassays in tandem with extensive chemical target analysis of 225 compounds. The extracts induced fluctuating bioassay responses over time for all locations during all sampling periods, highlighting the presence of temporal and spatial variation in toxic pressure. A range of compounds, primarily fungicides and herbicides, were detected in the passive sampler extracts during all sampling periods and at all locations at variable concentrations, highlighting the persistent but variable chemical pressure in surface waters in agricultural regions. However, the toxicity observed in the in vitro bioassays could solely be attributed to detected chemicals in 6 % of the cases with those chemicals explaining only 1-16.9 % of the observed effects, indicating that these were predominantly caused by undetected chemicals. Risk assessments based on bioassay responses revealed frequent exceedances of effect-based trigger values at all locations and during all sampling periods. It is concluded that effect-based assessments better capture temporal variations in potential ecotoxicological risks than traditional chemical analyses, but that advanced chemical analysis is needed to explain the bioanalytical response profiles.

Characterizing environmental contamination by plant protection products along the land-to-sea continuum:a focus on France and French overseas territories

Environmental compartments are contaminated by a broad spectrum of plant protection products (PPPs) that are currently widely used in agriculture or, for some of them, whose use was banned many years ago. The aim of this study is to draw up an overview of the levels of contamination of soils, continental aquatic environments, seawaters and atmosphere by organic PPPs in France and the French overseas territories, based on data from the scientific publications and the grey literature. It is difficult to establish an exhaustive picture of the overall contamination of the environment because the various compartments monitored, the monitoring frequencies, the duration of the studies and the lists of substances are not the same. Of the 33 PPPs most often recorded at high concentration levels in at least one compartment, 5 are insecticides, 9 are fungicides, 15 are herbicides and 4 are transformation products. The PPP contamination of the environment shows generally a seasonal variation according to crop cycles. On a pluriannual scale, the contamination trends are linked to the level of use driven by the pest pressure, and especially to the ban of PPP. Overall, the quality of the data acquired has been improved thanks to new, more integrative sampling strategies and broad-spectrum analysis methods that make it possible to incorporate the search for emerging contaminants such as PPP transformation products. Taking into account additional information (such as the quantities applied, agricultural practices, meteorological conditions, the properties of PPPs and environmental conditions) combined with modelling tools will make it possible to better assess and understand the fate and transport of PPPs in the environment, inter-compartment transfers and to identify their potential impacts. Simultaneous monitoring of all environmental compartments as well as biota in selected and limited relevant areas would also help in this assessment.

Miniaturisation of the Daphnia magna immobilisation assay for the reliable testing of low volume samples

International standard test guidelines for the ecotoxicological characterisation of various substances use organisms such as algae, daphnids and fish embryos. These guidelines recommend or use relatively high volumes of water for the process of testing, for example, 200 mL for a complete dose-response relationship in a daphnia assay. However, for various samples such as concentrated extracts from environmental monitoring or leachates from microplastic ageing experiments, the amount of available sample volume is limited, that is, rather in the range of 10-50 mL/biotest. Using the exposure volumes as recommended in test guidelines would not allow to test a range of different concentrations or to repeat tests or use multiple different organismic bioassays. Lower media volumes would allow the testing of more samples (more concentrations per sample, more test repetitions for statistical robustness, etc.) but it may also decrease the possible number of organisms tested in the same volume. Here, we aimed at reducing the test volumes in the acute daphnia assay (using a maximum of 30 mL for a complete dose-response relationship) without impacting animals' sensitivity towards toxicants. A literature review on existing miniaturisation approaches was used as a starting point. Subsequently, assays employing conventional as well as reduced test volumes were compared for 16 selected test substances with a diverse spectrum of lipophilicity. Results showed that there are differences in EC50 between the two approaches, but that these differences were overall only within a range of a factor of two to three. Further, by retrieving EC50 values for the genus Daphnia and 16 test substances from the United States Environmental Protection Agency database, we demonstrated that our results are well in line with the general differences in sensitivities.

Selectively Quantify Toxic Pollutants in Water by Machine Learning Empowered Electrochemical Biosensors

Electroactive biofilm (EAB) sensors have become pivotal in water quality detection and early ecological risk warnings due to their remarkable sensitivity. However, it is challenging to identify multiple toxicants in complex water bodies concurrently. This research developed an innovative biosensor detection strategy combined with machine learning. To simultaneously quantify and qualitatively predict the presence of each toxin in a multitoxic system, we developed a prediction model (MEA-ANN) based on machine learning analysis of EABs by analyzing the electrochemical toxicity response parameters of various toxicants (Cd2+, Cr6+, triclosan, and trichloroacetic acid). Furthermore, the mean impact value was utilized to filter the characteristic response parameters of toxicants, enhancing the prediction accuracy and efficiency of the model. The optimized model (OMEA-ANN) demonstrated strong performance in predicting target toxicants within interference systems containing analogs. The practicability and feasibility of this model were validated using seven real water samples and spiked natural water samples, achieving R2 > 0.9. The novel, eco-friendly, and intelligent water ecological risk early warning strategy presented in this paper addresses the limitations of traditional EAB sensors. It expands the applicability of EAB sensors for detecting multiple toxicants in water, significantly advancing their role in water quality monitoring. This approach provides valuable insights for the intelligent management of sewage.

High-Throughput Effect-Directed Analysis of Androgenic Compounds in Hospital Wastewater: Identifying Effect Drivers through Non-Target Screening Supported by Toxicity Prediction

The increasing number of contaminants released into the environment necessitates innovative strategies for their detection and identification, particularly in complex environmental matrices like hospital wastewater. Hospital effluents contain both natural and synthetic hormones that might significantly contribute to endocrine disruption in aquatic ecosystems. In this study, HT-EDA has been implemented to identify the main effect-drivers (testosterone, androsterone and norgestrel) from hospital effluent using microplate fractionation, the AR-CALUX bioassay and an efficient data processing workflow. Through nontargeted screening, over 5000 features (ESI+) were initially detected, but our workflow's prioritization based on androgenic activity prediction reduced the number of features requiring further analysis by over 95%, significantly streamlining the workload. In addition, the semiquantitative nontarget analysis allowed for the calculation of the contribution of an identified compound to the total activity of the sample without the need for reference standards. While this contribution was low (∼4.3%) and applicable to only one compound (1,4-androstadiene-3,17-dione), it presents the first approach for calculating such contributions without relying on standards. Compared to the available alternatives our workflow demonstrates clear environmental relevance by enhancing HT-EDA for more efficient identification and prioritization of effect-drivers in hospital effluents, and it can be adapted to address other environmental threats in complex mixtures.

Private, public, and bottled drinking water: Shared contaminant-mixture exposures and effects challenge

BACKGROUND

Humans are primary drivers of environmental-contaminant exposures worldwide, including in drinking-water (DW). In the United States, point-of-use DW (POU-DW) is supplied via private tapwater (TW), public-supply TW, and bottled water (BW). Differences in management, monitoring, and messaging and lack of directly-intercomparable exposure data influence the actual and perceived quality and safety of different DW supplies and directly impact consumer decision-making.

OBJECTIVES

The purpose of this paper is to provide a meta-analysis (quantitative synthesis) of POU-DW contaminant-mixture exposures and corresponding potential human-health effects of private-TW, public-TW, and BW by aggregating exposure results and harmonizing apical-health-benchmark-weighted and bioactivity-weighted effects predictions across previous studies by this research group.

DISCUSSION

Simultaneous exposures to multiple inorganic and organic contaminants of known or suspected human-health concern are common across all three DW supplies, with substantial variability observed in each and no systematic difference in predicted cumulative risk between supplies. Differences in contaminant or contaminant-class exposures, with important implications for DW-quality improvements, were observed and attributed to corresponding differences in regulation and compliance monitoring.

CONCLUSION

The results indicate that human-health risks from contaminant exposures are common to and comparable in all three DW-supplies, including BW. Importantly, this study's target analytical coverage, which exceeds that currently feasible for water purveyors or homeowners, nevertheless is a substantial underestimation of the breadth of contaminant mixtures in the environment and potentially present in DW. Thus, the results emphasize the need for improved understanding of the adverse human-health implications of long-term exposures to low-level inorganic-/organic-contaminant mixtures across all three distribution pipelines and do not support commercial messaging of BW as a systematically safer alternative to public-TW. Regardless of the supply, increased public engagement in source-water protection and drinking-water treatment is necessary to reduce risks associated with long-term DW-contaminant exposures, especially in vulnerable populations, and to reduce environmental waste and plastics contamination.

Developing an Approach for Integrating Chemical Analysis and Transcriptional Changes to Assess Contaminants in Water, Sediment, and Fish

Pharmaceuticals in aquatic environments pose threats to aquatic organisms because of their continuous release and potential accumulation. Monitoring methods for these contaminants are inadequate, with targeted analyses falling short in assessing water quality's impact on biota. The present study advocates for integrated strategies combining suspect and targeted chemical analyses with molecular biomarker approaches to better understand the risks posed by complex chemical mixtures to nontarget organisms. The research aimed to integrate chemical analysis and transcriptome changes in fathead minnows to prioritize contaminants, assess their effects, and apply this strategy in Wascana Creek, Canada. Analysis revealed higher pharmaceutical concentrations downstream of a wastewater-treatment plant, with clozapine being the most abundant in fathead minnows, showing notable bioavailability from water and sediment sources. Considering the importance of bioaccumulation factor and biota-sediment accumulation factor in risk assessment, these coefficients were calculated based on field data collected during spring, summer, and fall seasons in 2021. Bioaccumulation was classified as very bioaccumulative with values >5000 L kg-1, suggesting the ability of pharmaceuticals to accumulate in aquatic organisms. The study highlighted the intricate relationship between nutrient availability, water quality, and key pathways affected by pharmaceuticals, personal care products, and rubber components. Prioritization of these chemicals was done through suspect analysis, supported by identifying perturbed pathways (specifically signaling and cellular processes) using transcriptomic analysis in exposed fish. This strategy not only aids in environmental risk assessment but also serves as a practical model for other watersheds, streamlining risk-assessment processes to identify environmental hazards and work toward reducing risks from contaminants of emerging concern. Environ Toxicol Chem 2024;43:2252-2273. © 2024 SETAC.

Evaluation of arsenic induced genotoxicity and its impact on life processes of Daphnia magna

Heavy metals like arsenic is ubiquitously present in the environment. Geologic and anthropogenic activities are the root cause behind high concentration of arsenic in natural water bodies demanding strict monitoring of water quality prior to human consumption and utilization. In the present study, we have employed Daphnia magna for studying the biological effects of environmentally relevant high concentration of arsenic in water. In acute toxicity study, the LC50 value for 24hr exposure was found to be 2.504 mg/L, which gradually decreased with increase in time period (24hr- 96hr) to 2.011 mg/ L at 96hr. Sub-chronic toxicity was evaluated over 12 days using sub-lethal concentrations (5 %, 10 %, 15 %, and 20 % of the 24-hr LC50). Survivability in Daphnia showed a decreasing trend from 96 % to 91 % with increase in arsenic concentrations from 5 % of LC50 24 hr value to 20 % of LC 50 24hr value respectively. Alongside decreased survivability, there was a significant reduction in body size, with organisms exposed to the highest concentration of arsenic measuring 0.87±0.01 mm compared to 1.51±0.10 mm in the control group. Reproductive potential declined concentration dependently with exposure, with the highest reduction observed at 20 % of LC50 24hr value, where offspring numbers decreased to 7±1 from 23±5 in the control. Heart rate decreased in concentration and time-dependent manners, with the lowest rates observed at the highest arsenic concentration (279±16 bpm after 24hr and 277±27 bpm after 48hr). Comet assay and micronucleus assay conducted after 48 hrs of exposure revealed concentration-dependent genotoxic effects in Daphnia magna. Our results indicate negative impact on physiology and reproduction of Daphnia magna at environmentally existent concentration of arsenic. Also Daphnia magna could serve as a sensitive test system for investigating arsenic contamination in water bodies.

Beyond the Drinking Water Directive: The use of reporter gene assays as an added tool for effect-based monitoring of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in drinking water sources

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are legacy organic micropollutants (OMPs) that are sporadically detected in drinking water (DW) sources. The European Drinking Water Directive requires EU member states to monitor 5 PAHs in DW and its sources. The Dutch national regulations require 6 additional PAHs to be monitored and 7 polychlorinated biphenyls (PCBs). These indicator compounds act as representatives for large compound classes. PCBs alone comprise 209 congeners, it is evident that conventional chemical target analysis (GC-tQ-MS) alone is not sufficient to monitor these entire compound classes. This study investigated the application of reporter gene assays as effect-based methods (EBMs) to monitor PAHs and PCBs in DW sources. Herein, it was assessed what added value the bioassays can bring compared to the current approach of chemical target analysis for PCBs and PAHs. Regulated and non-regulated PAHs and PCBs were tested in four bioassays to determine the relative potency factors (RPFs) for these compounds. Non-regulated congeners were found to be active in the PAH-CALUX and anti-AR CALUX. An assessment of surface water (SW) spiked with standard mixtures containing PAHs and PCBs confirmed the predictable behavior of the PAH-CALUX. Moreover, the bioassay was able to detect AhR-mediated activity caused by non-regulated PAHs and PCBs, whereas this would have been missed by conventional chemical target analysis. Last, a field study was conducted in Dutch DW sources at six sampling moments. The PAH-CALUX detected AhR-mediated activity at all sampling moments and an ecological effect-based trigger (EBT) value was exceeded on multiple accounts. Combined application of GC-tQ-MS and the PAH-CALUX ensures compliancy with monitoring legislation and provides additional insights into potential hazards to humans and the environment.

Efficacy of chemical digestion methods to reveal undamaged microplastics from planktonic samples

Standardisation and validation of methods for microplastics research is essential. A major methodological challenge is the removal of planktonic organisms from marine water samples allowing for the identification of microplastics associated to planktonic communities. To improve the reproducibility and accuracy of digestion methods for the removal of planktonic biomass, we compared and modified existing chemical digestion methods. These digestion methods included an acidic digestion using nitric acid, alkaline digestions with potassium hydroxide (alkaline 1 digestion) and sodium hydroxide from drain cleaner (alkaline 2 digestion), an oxidative digestion using sodium dodecyl sulfate with hydrogen peroxide, and an enzymatic digestion using enzyme drain clean pellets. Chemical digestion of three densities of zooplankton communities (high, medium, and low) in the presence of five commonly found environmental microplastic pollutants (polyamide, polyethylene, polyethylene terephthalate, polypropylene, and polystyrene) were performed for each treatment. The chemical treatments were assessed for (i) their digestion efficiency of zooplankton communities by different biomass densities, and (ii) their impact on microplastic particles through the comparison of both chemical (Raman spectroscopy) and physical (length, width, and visual) changes, between the pre-treatment and post-treatment microplastic particles. The alkaline 1, alkaline 2 and oxidative methods demonstrated significantly better digestion efficiency (p < 0.05) than the modified enzymatic and acidic treatments. The acidic, alkaline 1, and alkaline 2, treatments caused the most damages to the microplastic particles. We suggest future studies to implement the oxidative digestion method with sodium dodecyl sulfate and hydrogen peroxide because of its high digestion efficiency, and low damage to microplastic particles. This method is similar to the wet peroxide oxidation digestion method used throughout the literature but can be implemented at a lower cost.

Metagenomics-Based Microbial Ecological Community Threshold and Indicators of Anthropogenic Disturbances in Estuarine Sediments

Assessing the impacts of cumulative anthropogenic disturbances on estuarine ecosystem health is challenging. Using spatially distributed sediments from the Pearl River Estuary (PRE) in southern China, which are significantly influenced by anthropogenic activities, we demonstrated that metagenomics-based surveillance of benthic microbial communities is a robust approach to assess anthropogenic impacts on estuarine benthic ecosystems. Correlational and threshold analyses between microbial compositions and environmental conditions indicated that anthropogenic disturbances in the PRE sediments drove the taxonomic and functional variations in the benthic microbial communities. An ecological community threshold of anthropogenic disturbances was identified, which delineated the PRE sediments into two groups (H and L) with distinct taxa and functional traits. Group H, located nearshore and subjected to a higher level of anthropogenic disturbances, was enriched with pollutant degraders, putative human pathogens, fecal pollution indicators, and functional traits related to stress tolerance. In contrast, Group L, located offshore and subjected to a lower level of anthropogenic disturbances, was enriched with halotolerant and oligotrophic taxa and functional traits related to growth and resource acquisition. The machine learning random forest model identified a number of taxonomic and functional indicators that could differentiate PRE sediments between Groups H and L. The identified ecological community threshold and microbial indicators highlight the utility of metagenomics-based microbial surveillance in assessing the adverse impacts of anthropogenic disturbances in estuarine sediments, which can assist environmental management to better protect ecosystem health.

Method validation and environmental monitoring of triethanolamine ester quaternary ammonium compounds

In this study water and sediment samples, collected from the River Nene (Northamptonshire) at several sites in the vicinity of the Great Billing sewage treatment plant (STP), were analysed for triethanolamine quaternary compounds (TEAQ, ester quats). A method was developed using liquid chromatography tandem mass spectrometry (LC/MS/MS) with a electrospray ionisation source (ESI). Ten components were determined using a characterised commercial sample of Tallow TEAQ as a standard. To our knowledge this is the first time environmental concentrations of a wide spectrum of individual homologues of TEAQ have been reliably quantified covering a broad range of environmental matrices (STP influent, STP effluent, surface waters and sediments), due to the challenging nature of the analytical method. The method featured novel solutions for the determination of long and multiple chain length alkyl quats, controlling loss processes, background contamination and chromatographic performance. TEAQ compounds were found to be highly removed in the sewage treatment plant resulting in low effluent concentrations. Low concentrations in both river water and sediment samples were found also. In many cases levels were below the Method Detection Limit (MDL). In river water samples, mean values of TEAQ compounds found were 210-398 ng/L for C16:0/C18:0 TEAQ diester and 126-287 ng/L for C18:0/C18:0 TEAQ diester. River sediment was found to contain mean TEAQ levels of 7.07-12.5, 19.7 to 40.3 and 7.04-35.1 μg/kg dry weight for C16:0/C16:0, C16:0/C18:0, and C18:0/C18:0 TEAQ, respectively. At Great Billing STP monoesters and diesters of TEAQ were shown to be efficiently removed (>97 and 99 %, respectively), although limited samples were taken on this occasion.

Impact of sample acidification and extract storage on hormone receptor-mediated and oxidative stress activities in wastewater

An underemphasized aspect of sampling strategies in effect-based in vitro testing is to determine suitable collection and preparation techniques. In the current study, the impact of sample acidification on bioactivities was assessed using in vitro bioassays for hormone receptor-mediated effects (estrogen receptor [ER] and androgen receptor [AR]) and the oxidative stress response (Nrf2 activity). Sampling was conducted at a recently upgraded Swedish wastewater treatment plant. Future plans for the treated wastewater include reuse for irrigation or as a potential drinking water source. In the AR and Nrf2 assays, acidification decreased bioactivities in the wastewater influent sample extracts, whereas acidification increased bioactivities following further treatment (disc filtration). In the ER assay, acidification had no impact on the observed bioactivities in the sample extracts. A secondary objective of the study was to assess the stability of the sample extracts over time. Lower activities were detected in the ER and AR assays in all extracts after storage for approximately 1 year. Nrf2 activities did not decrease over time, but rather increased in some of the acidified sample extracts. Overall, the findings suggest that sampling strategies involving acidification may need to be tailored depending on the selected bioassay(s) and the type of wastewater treatments being assessed.

Changes in chemical occurrence, concentration, and bioactivity in the Colorado River before and after replacement of the Moab, Utah wastewater treatment plant

Long-term (2010-19) water-quality monitoring on the Colorado River downstream from Moab Utah indicated the persistent presence of Bioactive Chemicals (BC), such as pesticides and pharmaceuticals. This stream reach near Canyonlands National Park provides critical habitat for federally endangered species. The Moab wastewater treatment plant (WWTP) outfall discharges to the Colorado River and is the nearest potential point-source to this reach. The original WWTP was replaced in 2018. In 2016-19, a study was completed to determine if the new plant reduced BC input to the Colorado River at, and downstream from, the outfall. Water samples were collected before and after the plant replacement at sites upstream and downstream from the outfall. Samples were analyzed for as many as 243 pesticides, 109 pharmaceuticals, 20 hormones, 51 wastewater indicator chemicals, 20 metals, and 8 nutrients. BC concentrations, hazard quotients (HQs), and exposure activity ratios (EARs) were used to identify and prioritize contaminants for their potential to have adverse biological effects on the health of native and endangered wildlife. There were 22 BC with HQs >1, mostly metals and hormones; and 23 BC with EARs >0.1, mostly hormones and pharmaceuticals. Most high HQs or EARs were associated with samples collected at the WWTP outfall site prior to its replacement. Discharge from the new plant had reduced concentrations of nutrients, hormones, pharmaceuticals, and other BC. For example, all 16 of the hormones detected at the WWTP outfall site had maximum concentrations in samples collected prior to the WWTP replacement. The WWTP replacement had less effect on instream concentrations of metals and pesticides, BC whose sources are less directly tied to domestic wastewater. Study results indicate that improved WWTP technology can create substantial reductions in concentrations of non-regulated BC such as pharmaceuticals, in addition to regulated contaminants such as nutrients.

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.

Land Use Influencing the Distribution of Pesticides in Surface Water: The Case of the Ma River and Its Tributaries in Thanh Hoa Province, Vietnam

Pesticide residues are regularly found in surface water, which could be dangerous for freshwater ecosystems and biodiversity. Pesticides may enter waters through a variety of pathways, but runoff from irrigation or precipitation has the highest quantities. Previous studies analyzing the pesticides pollution or ecological risks of pesticides focused on few regions (e.g., European and United States), whereas analysis of pesticide pollution in Southeast Asia and especially in Vietnam is limited. This study presents an investigation of banned pesticides used across the range of land use in catchments of the Ma river and its tributaries in Thanh Hoa province, Vietnam. Applying principal component analysis (PCA), we investigated the relationship between specific pesticides and land use. Besides, cluster analysis (CA), the method of aggregating monitoring locations, was applied in this study to find spatial pattern of pesticides pollution. Due to their persistence and remobilization during floods and runoff, all ten banned pesticides-eight insecticides (aldrin/dieldrin, BHC, chlordane, endrin, heptachlor, lindane, malathion, and parathion) and two herbicides (paraquat, and 2,4D)-still remain in surface water and are not presumably influenced by the fraction of land use area in the catchments. Clustering results revealed that banned pesticides still occur in some areas. Site TH08 close to Le Mon industrial zone and TH18 in Thanh Hoa city have higher concentrations of banned pesticides than other sites due to their highly toxic and long-time existence in the environment. Overall, our study provides approach to investigate pesticides in surface water for a province in Vietnam that may be used for future ecotoxicological studies to enhance risk assessment for stream ecosystems.

Effects of multiple stressors on benthic invertebrates using Water Framework Directive monitoring data

Multiple stressors affect freshwater systems and cause a deficient ecological status according to the European Water Framework Directive (WFD). To select effective mitigation measures and improve the ecological status, knowledge on the stressor hierarchy and individual and joined effects is necessary. However, compared to common stressors like nutrient enrichment and morphological degradation, the relative importance of micropollutants such as pesticides and pharmaceuticals is largely unaddressed. We used WFD monitoring data from Saxony (Germany) to investigate the importance of 85 environmental variables (including 34 micropollutants) for 18 benthic invertebrate metrics at 108 sites. The environmental variables were assigned to five groups (natural factors, nutrient enrichment, metals, micropollutants and morphological degradation) and were ranked according to their relative importance as group and individually within and across groups using Principal Component Analyses (PCAs) and Boosted Regression Trees (BRTs). Overall, natural factors contributed the most to the total explained deviance of the models. This variable group represented not only typological differences between sampling sites but also a gradient of human impact by strongly anthropogenically influenced variables such as electric conductivity and dissolved oxygen. These large-scale effects can mask the individual importance of the other variable groups, which may act more specifically at a subset of sites. Accordingly, micropollutants were not represented by a few dominant variables but rather a diverse palette of different chemicals with similar contribution. As a group, micropollutants contributed similarly as metals, nutrient enrichment and morphological degradation. However, the importance of micropollutants might be underestimated due to limitations of the current chemical monitoring practices.

Risk evaluation and prioritization of contaminants of emerging concern and other organic micropollutants in two river basins of central Argentina

A research gap exists in baseline concentrations of organic micropollutants in South American rivers. Identification of areas with different degrees of contamination and risk to the inhabitant biota is needed to improve management of freshwater resources. Here we inform the incidence and ecological risk assessment (ERA) of current used pesticides (CUPs), pharmaceutical and personal care products (PPCPs) and cyanotoxins (CTX) measured in two river basins from central Argentina (South America). Risk Quotients approach was used for ERA differentiating wet and dry seasons. High risk was associated to CUPs in both basins (45 % and 30 % of sites from Suquía and Ctalamochita rivers, respectively), mostly in the basins extremes. Main contributors to risk in water were insecticides and herbicides in Suquía river and insecticides and fungicides in Ctalamochita river. In Suquía river sediments, a very high risk was observed in the lower basin, mainly from AMPA contribution. Additionally, 36 % of the sites showed very high risk of PCPPs in Suquía river water, with the highest risk downstream the wastewater treatment plant of Córdoba city. Main contribution was from a psychiatric drug and analgesics. In sediments medium risk was observed at the same places with antibiotics and psychiatrics as main contributors. Few data of PPCPs are available in the Ctalamochita river. The risk in water was low, with one site (downstream Santa Rosa de Calamuchita town) presenting moderated risk caused by an antibiotic. CTX represented in general medium risk in San Roque reservoir, with San Antonio river mouth and the dam exit showing high risk during the wet season. The main contributor was microcystin-LR. Priority chemicals for monitoring or further management include two CUPs, two PPCPs, and one CTX, demonstrating a significant input of pollutants to water ecosystems from different sources and the need to include organic micropollutants in current and future monitoring.

Evaluation of in vitro toxicity information for zebrafish as a promising alternative for chemical hazard and risk assessment

In vitro assays are widely proposed as a test alternative to traditional in vivo standard acute and chronic toxicity tests. However, whether toxicity information derived from in vitro assays instead of in vivo tests could provide sufficient protection (e.g., 95 % of protection) for chemical risks remain evaluated. To investigate the feasibility of zebrafish (Danio rerio) cell-based in vitro test method as a test alternative, we comprehensively compared sensitivity differences among endpoints, among test methods (in vitro, FET and in vivo), and between zebrafish and rat (Rattus norvegicus), respectively using chemical toxicity distribution (CTD) approach. For each test method involved, sublethal endpoints were more sensitive than lethal endpoints for both zebrafish and rat, respectively. Biochemistry (zebrafish in vitro), development (zebrafish in vivo and FET), physiology (rat in vitro) and development (rat in vivo) were the most sensitive endpoints for each test method. Nonetheless, zebrafish FET test was the least sensitive one compared to its in vivo and in vitro tests for either lethal or sublethal responses. Comparatively, rat in vitro tests considering cell viability and physiology endpoints were more sensitive than rat in vivo test. Zebrafish was found to be more sensitive than rat regardless of in vivo or in vitro tests for each pairwise endpoint of concern. Those findings indicate that zebrafish in vitro test is a feasible test alternative to zebrafish in vivo and FET test and traditional mammalian test. It is suggesting that zebrafish in vitro test can be optimized by choosing more sensitive endpoints, such as biochemistry to provide sufficient protection for zebrafish in vivo test and to establish applications of zebrafish in vitro test in future risk assessment. Our findings are vital for evaluating and further application of in vitro toxicity toxicity information as an alternative for chemical hazard and risk assessment.

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.

Freshwater Cyanobacterial Toxins, Cyanopeptides and Neurodegenerative Diseases

Cyanobacteria produce a wide range of structurally diverse cyanotoxins and bioactive cyanopeptides in freshwater, marine, and terrestrial ecosystems. The health significance of these metabolites, which include genotoxic- and neurotoxic agents, is confirmed by continued associations between the occurrence of animal and human acute toxic events and, in the long term, by associations between cyanobacteria and neurodegenerative diseases. Major mechanisms related to the neurotoxicity of cyanobacteria compounds include (1) blocking of key proteins and channels; (2) inhibition of essential enzymes in mammalian cells such as protein phosphatases and phosphoprotein phosphatases as well as new molecular targets such as toll-like receptors 4 and 8. One of the widely discussed implicated mechanisms includes a misincorporation of cyanobacterial non-proteogenic amino acids. Recent research provides evidence that non-proteinogenic amino acid BMAA produced by cyanobacteria have multiple effects on translation process and bypasses the proof-reading ability of the aminoacyl-tRNA-synthetase. Aberrant proteins generated by non-canonical translation may be a factor in neuronal death and neurodegeneration. We hypothesize that the production of cyanopeptides and non-canonical amino acids is a more general mechanism, leading to mistranslation, affecting protein homeostasis, and targeting mitochondria in eukaryotic cells. It can be evolutionarily ancient and initially developed to control phytoplankton communities during algal blooms. Outcompeting gut symbiotic microorganisms may lead to dysbiosis, increased gut permeability, a shift in blood-brain-barrier functionality, and eventually, mitochondrial dysfunction in high-energy demanding neurons. A better understanding of the interaction between cyanopeptides metabolism and the nervous system will be crucial to target or to prevent neurodegenerative diseases.

Risk from unintentional environmental mixtures in EU surface waters is dominated by a limited number of substances

Unintentional environmental mixtures happen when multiple chemicals co-occur in the environment. A generic mixture assessment factor (MAF), has been proposed to account for this. The MAF is a number by which safe exposure levels for single chemicals are divided to ensure protection against combined exposures to multiple chemicals. Two key elements to judge the appropriateness of a generic MAF are (1) defining the scope of mixtures that need to be addressed by a MAF (i.e.: simple mixtures vs complex mixtures), and (2) the existence of common risk drivers across large spatial scales. Simple mixtures with one to three risk drivers can easily be addressed by chemical-by-chemical regulatory action. Our work provides evidence on the prevalence and complexity of cumulative risk in EU freshwaters based on chemical monitoring data from one of the largest databases in the EU. With 334 chemicals being monitored, low complexity mixtures (one to 3 three risk drivers) dominated. After excluding metals, only 15 out of 307 chemicals (5 %) were most frequent chemical risk drivers. When these 15 chemicals were excluded from the analysis, 95 % of all monitoring site - year combinations did not pose a concern for cumulative risk. Most of these 15 chemicals are already banned or listed in various priority lists, showing that current regulatory frameworks were effective in identifying drivers of single chemical and cumulative risk. Although the monitoring data do not represent the entirety of environmental mixtures in the EU, the observed patterns of (1) limited prevalence of truly complex mixtures, and (2) limited number of overall risk drivers, argue against the need for implementing a generic MAF as a regulatory tool to address risk from unintentional mixtures in EU freshwaters.

Pre-selection of monitoring stations for marine water quality using affinity propagation: A case study of Xincun Lagoon, hainan, China

The development, protection, and restoration of bays require works in scientific research and applications, and the success of which depends on a well deployment of monitoring stations for marine water quality. However, for bays without historical data, it is difficult to carry out related research on deployment of the monitoring stations, resulting in very few research works. This paper has introduced the affinity propagation (AP) clustering algorithm and achieved good results by correcting the preferences. The results show that under the given preference, that is, when the value of M is -6800, the number of monitoring stations in the Xincun lagoon area is 24. Simultaneous the sensitivity analysis of preferences shows that the number of exemplars decreases with lower preferences, that is, when M decreased from -4000 to -12000, the number also decreased from 70 to 36. However, some exemplars remain unchanged or being changed to adjacent positioning. This shows the stability of computation results and the rationality of AP. The research results can be well applied to other bays, even open waters.

Evaluation of effects-based methods as monitoring tools for assessing ecological impacts of metals in aquatic ecosystems

Effects-based methods (EBMs) are considered part of a more integrative strategy for regulating substances of concern under the European Union Water Framework Directive. In general, EBMs have been demonstrated as useful indicators of effects on biota, although links to population and community-level effects are sometimes uncertain. When EBMs are sufficiently specific and sensitive, and links between measured endpoints and apical or higher level effects are established, they can be a useful tool in assessing effects from a specific toxicant or class of toxicants. This is particularly valuable for toxicants that are difficult to measure and for assessing the effects of toxicant mixtures. This paper evaluates 12 EBMs that have been proposed for potential use in the assessment of metals. Each EBM was evaluated with respect to metal specificity and sensitivity, sensitivity to other classes of toxicants, and the strength of the relationship between EBM endpoints and effects observed at the whole organism or population levels of biological organization. The evaluation concluded that none of the EBMs evaluated meet all three criteria of being sensitive to metals, insensitive to other classes of toxicants, and a strong indicator of effects at the whole organism or population level. Given the lack of suitable EBMs for metals, we recommended that the continued development of mixture biotic ligand models (mBLMs) may be the most effective way to achieve the goal of a more holistic approach to regulating metals in aquatic ecosystems. Given the need to further develop and validate mBLMs, we suggest an interim weight-of-evidence approach that includes mBLMs, macroinvertebrate community bioassessment, and measurement of metals in key macroinvertebrate species. This approach provides a near-term solution and simultaneously generates data needed for the refinement and validation of mBLMs. Once validated, it should be possible to rely primarily on mBLMs as an alternative to EBMs for metals. Integr Environ Assess Manag 2023;19:24-31.  © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Detection and identification of a mixed cyanobacteria and microalgae culture using derivative spectrophotometry

Early detection and monitoring of algal blooms and potentially toxic cyanobacteria in source waters are becoming increasingly important with rising climate change and industrialization. There is a growing need to measure the mixed microalgae cultures sensitively and accurately, as multiple algae species are present in natural source waters. This study investigated the detection of an equal concentration, mixed-culture of cyanobacteria (Microcystis aeruginosa) and a common green algae (Chlorella vulgaris) in water using UV-Vis spectrophotometry while employing longer pathlengths and derivative spectrophotometry to improve the detection limit. A strong linear relationship (R² > 0.99) was found between the concentration and absorbance of the mixed-culture at 682 nm using 50 and 100 mm pathlengths. This study showed that the cyanobacterial (phycocyanin) peak could be separately identified in mixed-culture setting, while the chlorophyll peaks of both algae overlapped each other. The lowest detection limit of the mixed algal culture using traditional spectrophotometry and derivative spectrophotometry was calculated to be 25,997 cells/mL and 5505 cells/mL using a 100 mm cuvette pathlength. Lastly, the performance of mixed-culture and individual algal cultures were compared, and analyses were carried out to evaluate differences in slopes which can be used for quantification purposes. The results indicate that derivative spectrophotometry significantly improved the detection limit making the method potentially viable for the early detection of mixed algal cultures.

Smartphone-based holographic measurement of polydisperse suspended particulate matter with various mass concentration ratios

Real-time monitoring of suspended particulate matter (PM) has become essential in daily life due to the adverse effects of long-term exposure to PMs on human health and ecosystems. However, conventional techniques for measuring micro-scale particulates commonly require expensive instruments. In this study, a smartphone-based device is developed for real-time monitoring of suspended PMs by integrating a smartphone-based digital holographic microscopy (S-DHM) and deep learning algorithms. The proposed S-DHM-based PM monitoring device is composed of affordable commercial optical components and a smartphone. Overall procedures including digital image processing, deep learning training, and correction process are optimized to minimize the prediction error and computational cost. The proposed device can rapidly measure the mass concentrations of coarse and fine PMs from holographic speckle patterns of suspended polydisperse PMs in water with measurement errors of 22.8 ± 18.1% and 13.5 ± 9.8%, respectively. With further advances in data acquisition and deep learning training, this study would contribute to the development of hand-held devices for monitoring polydisperse non-spherical pollutants suspended in various media.

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.

Decoding river pollution trends and their landscape determinants in an ecologically fragile karst basin using a machine learning model

Karst watersheds accommodate high landscape complexity and are influenced by both human-induced and natural activity, which affects the formation and process of runoff, sediment connectivity and contaminant transport and alters natural hydrological and nutrient cycling. However, physical monitoring stations are costly and labor-intensive, which has confined the assessment of water quality impairments on spatial scale. The geographical characteristics of catchments are potential influencing factors of water quality, often overlooked in previous studies of highly heterogeneous karst landscape. To solve this problem, we developed a machining learning method and applied Extreme Gradient Boosting (XGBoost) to predict the spatial distribution of water quality in the world's most ecologically fragile karst watershed. We used the Shapley Addition interpretation (SHAP) to explain the potential determinants. Before this process, we first used the water quality damage index (WQI-DET) to evaluate the water quality impairment status and determined that COD_Mn, TN and TP were causing river water quality impairments in the WRB. Second, we selected 46 watershed features based on the three key processes (sources-mobilization-transport) which affect the temporal and spatial variation of river pollutants to predict water quality in unmonitored reaches and decipher the potential determinants of river impairments. The predicting range of COD_Mn spanned from 1.39 mg/L to 17.40 mg/L. The predictions of TP and TN ranged from 0.02 to 1.31 mg/L and 0.25-5.72 mg/L, respectively. In general, the XGBoost model performs well in predicting the concentration of water quality in the WRB. SHAP explained that pollutant levels may be driven by three factors: anthropogenic sources (agricultural pollution inputs), fragile soils (low organic carbon content and high soil permeability to water flow), and pollutant transport mechanisms (TWI, carbonate rocks). Our study provides key data to support decision-making for water quality restoration projects in the WRB and information to help bridge the science:policy gap.

Using the Daphnia magna Transcriptome to Distinguish Water Source: Wetland and Stormwater Case Studies

A major challenge in ecotoxicology is accurately and sufficiently measuring chemical exposures and biological effects given the presence of complex and dynamic contaminant mixtures in surface waters. It is impractical to quantify all chemicals in such matrices over space and time, and even if it were practical, concomitant biological effects would not be elucidated. Our study examined the performance of the Daphnia magna transcriptome to detect distinct responses across three water sources in Minnesota: laboratory (well) waters, wetland waters, and storm waters. Pyriproxyfen was included as a gene expression and male neonate production positive control to examine whether gene expression resulting from exposure to this well-studied juvenoid hormone analog can be detected in complex matrices. Laboratory-reared (<24 h) D. magna were exposed to a water source and/or pyriproxyfen for 16 days to monitor phenotypic changes or 96 h to examine gene expression responses using Illumina HiSeq 2500 (10 million reads per library, 50-bp paired end [2 × 50]). The results indicated that a unique gene expression profile was produced for each water source. At 119 ng/L pyriproxyfen (~25% effect concentration) for male neonate production, as expected, the Doublesex1 gene was up-regulated. In descending order, gene expression patterns were most discernable with respect to pyriproxyfen exposure status, season of stormwater sample collection, and wetland quality, as indicated by the index of biological integrity. However, the biological implications of the affected genes were not broadly clear given limited genome resources for invertebrates. Our study provides support for the utility of short-term whole-organism transcriptomic testing in D. magna to discern sample type, but highlights the need for further work on invertebrate genomics. Environ Toxicol Chem 2022;41:2107-2123. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Assessment of surface water quality of the bois river (Goiás, Brazil) using an integrated physicochemical, microbiological and ecotoxicological approach

The data on water pollution is scarce in developing countries, including Brazil. The water quality assessment is important implementing the monitoring and remediation programs to minimize the risk of hazardous substances in freshwaters. Thus, this study evaluated the surface water quality of a stretch of the Bois River (Brazil), based on the physicochemical, microbiological and ecotoxicological analyses conducted in 2017, using Standard Methods and fish embryo acute toxicity (FET) test with zebrafish (Danio rerio). The results indicated that the quality of water samples located close to the discharge of tannery effluents was most impaired. Total phosphorus, BOD, DO, ammoniacal nitrogen, and thermotolerant coliforms parameters in P4 were not in accordance with the standards of current Brazilian legislation. Iron, lead, and copper levels were higher than environmental standards. The physicochemical quality of water samples was lower in the dry season than the rainy season. All samples (P1, P3, and P5) in rainy and dry seasons did not induce significant acute toxicity for zebrafish early-life stage; however other trophic levels (algae and microcrustacean) should be investigated to gain a better understanding of the toxicity during water quality analysis. In conclusion, the physicochemical and microbiological changes in the water of the Bois River can affect aquatic organisms as well as humans when it is used for drinking or in agriculture.

Characterizing the Chemical Profile of Biological Decline in Stormwater-Impacted Urban Watersheds

Chemical contamination is an increasingly important conservation issue in urban runoff-impacted watersheds. Regulatory and restoration efforts typically evaluate limited conventional parameters and pollutants. However, complex urban chemical mixtures contain hundreds to thousands of organic contaminants that remain unidentified, unregulated, and poorly understood. This study aimed to develop broadly representative metrics of water quality impairment corresponding to previously documented biological degradation along gradients of human impacts. Stream samples (n = 65, baseflow/rainfall conditions, 2017-2018) were collected from 15 regional watersheds (Puget Sound, WA, USA) across an urbanization gradient defined by landscape characteristics. Surface water chemical composition characterized via non-targeted high-resolution mass spectrometry (7068 detections) was highly correlated with landscape-based urbanization gradient (p < 0.01) and season (p < 0.01). Landscape-scale changes in chemical composition closely aligned with two anchors of biological decline: coho salmon (Oncorhynchus kisutch) mortality risk (p < 0.001) and loss of stream macroinvertebrate diversity and abundance (p < 0.001). We isolated and identified 32 indicators for urban runoff impacts and corresponding receiving water ecological health, including well-known anthropogenic contaminants (e.g., caffeine, organophosphates, vehicle-derived chemicals), two related environmental transformation products, and a novel (methoxymethyl)melamine compound. Outcomes support data-directed selection of next-generation water quality indicators for prioritization and evaluation of watershed management efforts intended to protect aquatic ecosystems.

Assessing the genotoxic potential of freshwater sediments after extensive rain events - Lessons learned from a case study in an effluent-dominated river in Germany

Wastewater treatment plant effluents and releases from rainwater overflow basins can contribute to the input of genotoxic micropollutants in aquatic ecosystems. Predominantly lipophilic genotoxic compounds tend to sorb to particulate matter, making sediment a source and a sink of pollution. Therefore, the present study aims to investigate the genotoxic potential of freshwater sediments (i) during the dry period and (ii) after extensive rain events by collecting sediment samples in one small anthropogenically impacted river in Germany up- and downstream of the local wastewater treatment plant. The Micronucleus and Ames fluctuation assays with Salmonella typhimurium strains TA98, TA100, YG1041, and YG1042 were used to assess the genotoxic potential of organic sediment extracts. For evaluation of possible genotoxicity drivers, target analysis for 168 chemical compounds was performed. No clastogenic effects were observed, while the genotoxic potential was observed at all sampling sites primarily driven by polycyclic aromatic hydrocarbons, nitroarenes, aromatic amines, and polycyclic heteroarenes. Freshwater sediments' genotoxic potential increased after extensive rain events due to sediment perturbation and the rainwater overflow basin release. In the present study, the rainwater overflow basin was a significant source for particle-bound pollutants from untreated wastewater, suggesting its role as a possible source of genotoxic potential. The present study showed high sensitivity and applicability of the bacterial Salmonella typhimurium strains YG1041 and YG1042 to organic sediment extracts to assess the different classes of genotoxic compounds. A combination of effect-based methods and a chemical analysis was shown as a suitable tool for a genotoxic assessment of freshwater sediments.

Instrumental and bioanalytical assessment of pharmaceuticals and hormone-like compounds in a major drinking water source-wastewater receiving Zayandeh Rood river, Iran

Zayandeh Rood river is the most important river in central Iran supplying water for a variety of uses including drinking water for approximately three million inhabitants. The study aimed to investigate the quality of water concerning the presence of pharmaceutical active compounds (PhACs) and hormonelike compounds, which have been only poorly studied in this region. Sampling was performed at seven sites along the river (from headwater sites to downstream drinking water source, corresponding drinking water, and treated wastewater) affected by wastewater effluents, specific drought conditions, and high river-water demand. The targeted and nontargeted chemical analyses and in vitro bioassays were used to evaluate the presence of PhACs and hormonelike compounds in river water. In the samples, 57 PhACs and estrogens were detected with LC-MS/MS with the most common and abundant compounds valsartan, carbamazepine, and caffeine present in the highest concentrations in the treated wastewater in the concentrations of 8.4, 19, and 140 μg/L, respectively. A battery of in vitro bioassays detected high estrogenicity, androgenicity, and AhR-mediated activity (viz., in treated wastewater) in the concentrations 24.2 ng/L, 62.2 ng/L, and 0.98 ng/L of 17β-estradiol, dihydrotestosterone and 2,3,7,8-TCDD equivalents, respectively. In surface water samples, estrogenicity was detected in the range of <0.42 (LOD) to 1.92 ng/L of 17β-estradiol equivalents, and the drinking water source contained 0.74 ng/L of 17β-estradiol equivalents. About 19% of the estrogenicity could be explained by target chemical analyses, and the remaining estrogenicity can be at least partially attributed to the potentiation effect of detected surfactant residues. Drinking water contained several PhACs and estrogens, but the overall assessment suggested minor human health risk according to the relevant effect-based trigger values. To our knowledge, this study provides some of the first comprehensive information on the levels of PhACs and hormones in Iranian waters.

Characterization of the contamination fingerprint of wastewater treatment plant effluents in the Henares River Basin (central Spain) based on target and suspect screening analysis

The interest in contaminants of emerging concern (CECs) has increased lately due to their continued emission and potential ecotoxicological hazards. Wastewater treatment plants (WWTPs) are generally not capable of eliminating them and are considered the main pathway for CECs to the aquatic environment. The number of CECs in WWTPs effluents is often so large that complementary approaches to the conventional target analysis need to be implemented. Within this context, multitarget quantitative analysis (162 compounds) and a suspect screening (>40,000 suspects) approaches were applied to characterize the CEC fingerprint in effluents of five WWTPs in the Henares River basin (central Spain) during two sampling campaigns (summer and autumn). The results indicated that 76% of the compounds quantified corresponded to pharmaceuticals, 21% to pesticides and 3% to industrial chemicals. Apart from the 82 compounds quantified, suspect screening increased the list to 297 annotated compounds. Significant differences in the CEC fingerprint were observed between summer and autumn campaigns and between the WWTPs, being those serving the city of Alcalá de Henares the ones with the largest number of compounds and concentrations. Finally, a risk prioritization approach was applied based on risk quotients (RQs) for algae, invertebrates, and fish. Azithromycin, diuron, chlortoluron, clarithromycin, sertraline and sulfamethoxazole were identified as having the largest risks to algae. As for invertebrates, the compounds having the largest RQs were carbendazim, fenoxycarb and eprosartan, and for fish acetaminophen, DEET, carbendazim, caffeine, fluconazole, and azithromycin. The two WWTPs showing higher calculated Risk Indexes had tertiary treatments, which points towards the need of increasing the removal efficiency in urban WWTPs. Furthermore, considering the complex mixtures emitted into the environment and the low dilution capacity of Mediterranean rivers, we recommend the development of detailed monitoring plans and stricter regulations to control the chemical burden created to freshwater ecosystems.

Demonstration of an aggregated biomarker response approach to assess the impact of point and diffuse contaminant sources in feral fish in a small river case study

The assessment of the exposure of aquatic wildlife to complex environmental mixtures of chemicals originating from both point and diffuse sources and evaluating the potential impact thereof constitutes a significant step towards mitigating toxic pressure and the improvement of ecological status. In the current proof-of-concept study, we demonstrate the potential of a novel Aggregated Biomarker Response (ABR) approach involving a comprehensive set of biomarkers to identify complex exposure and impacts on wild brown trout (Salmo trutta fario). Our scenario used a small lowland river in Germany (Holtemme river in the Elbe river catchment) impacted by two wastewater treatment plants (WWTP) and diffuse agricultural runoff as a case study. The trout were collected along a pollution gradient (characterised in a parallel study) in the river. Compared to fish from the reference site upstream of the first WWTP, the trout collected downstream of the WWTPs showed a significant increase in micronucleus formation, phase I and II enzyme activities, and oxidative stress parameters in agreement with increasing exposure to various chemicals. By integrating single biomarker responses into an aggregated biomarker response, the two WWTPs' contribution to the observed toxicity could be clearly differentiated. The ABR results were supported by chemical analyses and whole transcriptome data, which revealed alterations of steroid biosynthesis and associated pathways, including an anti-androgenic effect, as some of the key drivers of the observed toxicity. Overall, this combined approach of in situ biomarker responses complemented with molecular pathway analysis allowed for a comprehensive ecotoxicological assessment of fish along the river. This study provides evidence for specific hazard potentials caused by mixtures of agricultural and WWTP derived chemicals at sublethal concentrations. Using aggregated biomarker responses combined with chemical analyses enabled an evidence-based ranking of sites with different degrees of pollution according to toxic stress and observed effects.

Can a mixture of agrochemicals (glyphosate, chlorpyrifos and chlorothalonil) mask the perception of an individual chemical? A hidden trap underlying ecological risk

As aquatic environments associated with conventional agriculture are exposed to various pesticides, it is important to identify any possible interactions that modify their effects when in a mixture. We applied avoidance tests with Danio rerio, exposing juveniles to three relevant current use pesticides: chlorpyrifos (CPF), chlorothalonil (CTL) and glyphosate (Gly), individually and in binary mixtures (CPF-Gly and CTL-Gly). Our goal was to identify the potential of contaminants to trigger the avoidance response in fish and detect any changes to that response resulting from binary mixtures. Avoidance was assessed for three hours using an open gradient system with six levels of increasing concentrations. Fish avoided environmentally relevant concentrations of the three compounds. The avoidance of CPF [AC50 = 7.95 (3.3-36.3) µg/L] and CTL [AC50 = 3.41 (1.2-41.6) µg/L] was evident during the entire period of observation. In the case of Gly, the response changed throughout the experiment: initially (until 100 min) the fish tolerated higher concentrations of the herbicide [AC50 = 52.2 (12.1-2700) µg/L] while during the later period (after 100 min) a clearer avoidance [1.5 (0.8-4.2) µg/L] was observed. The avoidance recorded using CPF and CTL alone was attenuated by the presence of Gly. Applying an additive concentration model, Gly initially acted synergistically with the other two compounds, although this interaction was not observed during the later period. Avoidance gives us an idea of how the distribution of populations may be altered by contamination, our results suggest that in some mixtures this response may be inhibited, at least temporarily, thus masking the ecological risk of the exposure.

Biological effect and chemical monitoring of Watch List substances in European surface waters: Steroidal estrogens and diclofenac - Effect-based methods for monitoring frameworks

Three steroidal estrogens, 17α-ethinylestradiol (EE2), 17β-estradiol (E2), estrone (E1), and the non-steroidal anti-inflammatory drug (NSAID), diclofenac have been included in the first Watch List of the Water Framework Directive (WFD, EU Directive 2000/60/EC, EU Implementing Decision 2015/495). This triggered the need for more EU-wide surface water monitoring data on these micropollutants, before they can be considered for inclusion in the list of priority substances regularly monitored in aquatic ecosystems. The revision of the priority substance list of the WFD offers the opportunity to incorporate more holistic bioanalytical approaches, such as effect-based monitoring, alongside single substance chemical monitoring. Effect-based methods (EBMs) are able to measure total biological activities (e.g., estrogenic activity or cyxlooxygenase [COX]-inhibition) of specific group of substances (such as estrogens and NSAIDs) in the aquatic environment at low concentrations (pg/L). This makes them potential tools for a cost-effective and ecotoxicologically comprehensive water quality assessment. In parallel, the use of such methods could build a bridge from chemical status assessments towards ecological status assessments by adressing mixture effects for relevant modes of action. Our study aimed to assess the suitability of implementing EBMs in the WFD, by conducting a large-scale sampling and analysis campaign of more than 70 surface waters across Europe. This resulted in the generation of high-quality chemical and effect-based monitoring data for the selected Watch List substances. Overall, water samples contained low estrogenicity (0.01-1.3 ng E2-Equivalent/L) and a range of COX-inhibition activity similar to previously reported levels (12-1600 ng Diclofenac-Equivalent/L). Comparison between effect-based and conventional analytical chemical methods showed that the chemical analytical approach for steroidal estrogens resulted in more (76%) non-quantifiable data, i.e., concentrations were below detection limits, compared to the EBMs (28%). These results demonstrate the excellent and sensitive screening capability of EBMs.

Predicting cytotoxicity of binary pollutants towards a human cell panel in environmental water by experimentation and deep learning methods

Biological assays are useful in water quality evaluation by providing the overall toxicity of chemical mixtures in environmental waters. However, it is impossible to elucidate the source of toxicity and some lethal combination of pollutants simply using biological assays. As facile and cost-effective methods, computation model-based toxicity assessments are complementary technologies. Herein, we predicted the human health risk of binary pollutant mixtures (i.e., binary combinations of As(III), Cd(II), Cr(VI), Pb(II) and F(I)) in water using in vitro biological assays and deep learning methods. By employing a human cell panel containing human stomach, colon, liver, and kidney cell lines, we assessed the human health risk mimicking cellular responses after oral exposures of environmental water containing pollutants. Based on the experimental cytotoxicity data in pure water, multi-task deep learning was applied to predict cellular response of binary pollutant mixtures in environmental water. Using additive descriptors and single pollutant toxicity data in pure water, the established deep learning model could predict the toxicity of most binary mixtures in environmental water, with coefficient of determination (R²) > 0.65 and root mean squared error (RMSE) < 0.22. Further combining the experimental data on synergistic and antagonistic effects of pollutant mixtures, deep learning helped improve the predictive ability of the model (R² > 0.74 and RMSE <0.17). Moreover, predictive models allowed us identify a number of toxicity source-related physiochemical properties. This study illustrates the combination of experimental findings and deep learning methods in the water quality evaluation.

An integrated approach for chemical water quality assessment of an urban river stretch through Effect-Based Methods and emerging pollutants analysis with a focus on genotoxicity

The impact of emerging chemical pollutants, on both status and functionality of aquatic ecosystems is worldwide recognized as a relevant issue of concern that should be assessed and managed by researchers, policymakers, and all relevant stakeholders. In Europe, the Reach Regulation has registered more than 100.000 chemical substances daily released in the environment. Furthermore, the effects related to the mixture of substances present in aquatic ecosystems may not be predictable on the basis of chemical analyses alone. This evidence, coupled with the dramatic effects of climate changes on water resources through water scarcity and flooding, makes urgent the application of innovative, fast and reliable monitoring methods. In this context, Effect-Based Methods (EBMs) have been applied in the urban stretch of the Tiber River (Central Italy) with the aim of understanding if detrimental pressures affect aquatic environmental health. In particular, different eco-genotoxicological assays have been used in order to detect genotoxic activity of chemicals present in the river, concurrently characterized by chemical analysis. Teratogenicity and embryo-toxicity have been studied in order to cover additional endpoints. The EBMs have highlighted the presence of diffuse chemical pollution and ecotoxicological effects in the three sampling stations, genotoxicological effects have been also detected through the use of different tests and organisms. The chemical analyses confirmed that in the aquatic ecosystems there is a diffuse presence, even at low concentrations, of emerging contaminants such as pharmaceuticals, not routinely monitored pesticides, personal care products, PFAS. The results of this study can help to identify an appropriate battery of EBMs for future studies and the application of more appropriate measures in order to monitor, mitigate or eliminate chemical contamination and remediate its adverse/detrimental effects on the ecosystem health.

Aquatic occurrence of phytotoxins in small streams triggered by biogeography, vegetation growth stage, and precipitation

Toxic plant secondary metabolites (PSMs), so-called phytotoxins, occur widely in plant species. Many of these phytotoxins have similar mobility, persistence, and toxicity properties in the environment as anthropogenic micropollutants, which increasingly contaminate surface waters. Although recent case studies have shown the aquatic relevance of phytotoxins, the overall exposure remains unknown. Therefore, we performed a detailed occurrence analysis covering 134 phytotoxins from 27 PSM classes. Water samples from seven small Swiss streams with catchment areas from 1.7 to 23 km² and varying land uses were gathered over several months to investigate seasonal impacts. They were complemented with samples from different biogeographical regions to cover variations in vegetation. A broad SPE-LC-HRMS/MS method was applied with limits of detection below 5 ng/L for over 80% of the 134 included phytotoxins. In total, we confirmed 39 phytotoxins belonging to 13 PSM classes, which corresponds to almost 30% of all included phytotoxins. Several alkaloids were regularly detected in the low ng/L-range, with average detection frequencies of 21%. This is consistent with the previously estimated persistence and mobility properties that indicated a high contamination potential. Coumarins were previously predicted to be unstable, however, detection frequencies were around 89%, and maximal concentrations up to 90 ng/L were measured for fraxetin produced by various trees. Overall, rainy weather conditions at full vegetation led to the highest total phytotoxin concentrations, which might potentially be most critical for aquatic organisms.

Spatial heterogeneity modeling of water quality based on random forest regression and model interpretation

A systematic understanding of the spatial distribution of water quality is critical for successful watershed management; however, the limited number of physical monitoring stations has restricted the evaluation of spatial water quality distribution and the identification of features impacting the water quality. To fill this gap, we developed a modeling process that employed the random forest regression (RFR) to model the water quality distribution for the Taihu Lake basin in Zhejiang Province, China, and adopted the Shapley Additive exPlanations (SHAP) method to interpret the underlying driving forces. We first used RFR to model three water quality parameters: permanganate index (COD_Mn), total phosphorus (TP), and total nitrogen (TN), based on 16 watershed features. We then applied the built models to generate water quality distribution maps for the basin, with the COD_Mn ranging from 1.39 to 6.40 mg/L, TP from 0.02 to 0.23 mg/L, and TN from 1.43 to 4.27 mg/L. These maps showed generally consistent patterns among the COD_Mn, TN, and TP with minor differences in the spatial distribution. The SHAP analysis showed that the TN was mainly affected by agricultural non-point sources, while the COD_Mn and TP were affected by agricultural and domestic sources. Due to differences in sewage collection and treatment between urban and rural areas, the water quality in highly populated urban areas was better than that in rural areas, which led to an unexpected positive relationship between water quality and population density. Overall, with the RFR models and SHAP interpretation, we obtained a continuous distribution pattern of the water quality and identified its driving forces in the basin. These findings provided important information to assist water quality restoration projects.

Identifying Chemicals and Mixtures of Potential Biological Concern Detected in Passive Samplers from Great Lakes Tributaries Using High-Throughput Data and Biological Pathways

Waterborne contaminants were monitored in 69 tributaries of the Laurentian Great Lakes in 2010 and 2014 using semipermeable membrane devices (SPMDs) and polar organic chemical integrative samplers (POCIS). A risk-based screening approach was used to prioritize chemicals and chemical mixtures, identify sites at greatest risk for biological impacts, and identify potential hazards to monitor at those sites. Analyses included 185 chemicals (143 detected) including polycyclic aromatic hydrocarbons (PAHs), legacy and current-use pesticides, fire retardants, pharmaceuticals, and fragrances. Hazard quotients were calculated by dividing detected concentrations by biological effect concentrations reported in the ECOTOX Knowledgebase (toxicity quotients) or ToxCast database (exposure-activity ratios [EARs]). Mixture effects were estimated by summation of EAR values for chemicals that influence ToxCast assays with common gene targets. Nineteen chemicals-atrazine, N,N-diethyltoluamide, di(2-ethylhexyl)phthalate, dl-menthol, galaxolide, p-tert-octylphenol, 3 organochlorine pesticides, 3 PAHs, 4 pharmaceuticals, and 3 phosphate flame retardants-had toxicity quotients >0.1 or EARs for individual chemicals >10^-3 at 10% or more of the sites monitored. An additional 4 chemicals (tributyl phosphate, triethyl citrate, benz[a]anthracene, and benzo[b]fluoranthene) were present in mixtures with EARs >10^-3 . To evaluate potential apical effects and biological endpoints to monitor in exposed wildlife, in vitro bioactivity data were compared to adverse outcome pathway gene ontology information. Endpoints and effects associated with endocrine disruption, alterations in xenobiotic metabolism, and potentially neuronal development would be relevant to monitor at the priority sites. The EAR threshold exceedance for many chemical classes was correlated with urban land cover and wastewater effluent influence, whereas herbicides and fire retardants were also correlated to agricultural land cover. Environ Toxicol Chem 2021;40:2165-2182. Published 2021. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Laboratory-Based Comparison for the Effects of Environmental Stressors Supports Field Evidence for the Relative Importance of Pollution on Life History and Behavior of the Pond Snail, Lymnaea stagnalis

Biodiversity is declining at an alarming rate globally, with freshwater ecosystems particularly threatened. Field-based correlational studies have "ranked" stressors according to their relative effects on freshwater biota, however, supporting cause-effect data from laboratory exposures are lacking. Here, we designed exposures to elicit chronic effects over equivalent exposure ranges for three ubiquitous stressors (temperature: 22-28 °C; pollution [14 component mixture]: 0.05-50 μg/L; invasive predator cue [signal crayfish, Pacifasticus leniusculus]: 25-100% cue) and investigated effects on physiological end points in the pond snail (Lymnaeastagnalis). All stressors reduced posthatch survival at their highest exposure levels, however, highly divergent effects were observed at lower test levels. Temperature stimulated hatching, growth, and reproduction, whereas pollution delayed hatching, decreased growth, reduced egg number/embryo viability, and induced avoidance behavior. The invasive predator cue stimulated growth and reduced embryo viability. In agreement with field-based ranking of stressors, pollution was identified as having the most severe effects in our test system. We demonstrate here the utility of laboratory studies to effectively determine hierarchy of stressors according to their likelihood of causing harm in the field, which has importance for conservation. Finally, we report negative impacts on life-history traits central to population stability (survival/reproduction) at the lowest pollution level tested (0.05 μg/L).

Public and private tapwater: Comparative analysis of contaminant exposure and potential risk, Cape Cod, Massachusetts, USA

BACKGROUND

Humans are primary drivers of environmental contamination worldwide, including in drinking-water resources. In the United States (US), federal and state agencies regulate and monitor public-supply drinking water while private-supply monitoring is rare; the current lack of directly comparable information on contaminant-mixture exposures and risks between private- and public-supplies undermines tapwater (TW) consumer decision-making.

METHODS

We compared private- and public-supply residential point-of-use TW at Cape Cod, Massachusetts, where both supplies share the same groundwater source. TW from 10 private- and 10 public-supply homes was analyzed for 487 organic, 38 inorganic, 8 microbial indicators, and 3 in vitro bioactivities. Concentrations were compared to existing protective health-based benchmarks, and aggregated Hazard Indices (HI) of regulated and unregulated TW contaminants were calculated along with ratios of in vitro exposure-activity cutoffs.

RESULTS

Seventy organic and 28 inorganic constituents were detected in TW. Median detections were comparable, but median cumulative concentrations were substantially higher in public supply due to 6 chlorine-disinfected samples characterized by disinfection byproducts and corresponding lower heterotrophic plate counts. Public-supply applicable maximum contaminant (nitrate) and treatment action (lead and copper) levels were exceeded in private-supply TW samples only. Exceedances of health-based HI screening levels of concern were common to both TW supplies.

DISCUSSION

These Cape Cod results indicate comparable cumulative human-health concerns from contaminant exposures in private- and public-supply TW in a shared source-water setting. Importantly, although this study's analytical coverage exceeds that currently feasible for water purveyors or homeowners, it nevertheless is a substantial underestimation of the full breadth of contaminant mixtures documented in the environment and potentially present in drinking water.

CONCLUSION

Regardless of the supply, increased public engagement in source-water protection and drinking-water treatment, including consumer point-of-use treatment, is warranted to reduce risks associated with long-term TW contaminant exposures, especially in vulnerable populations.

Assessing the Quality of Amazon Aquatic Ecosystems with Multiple Lines of Evidence: The Case of the Northeast Andean Foothills of Ecuador

We assessed the quality of Andes-Amazonia streams in Ecuador impacted by gold mining (GM), discharges from inefficient sewage network in urban areas (UA), wastes from fish farming (FF) and from non-functional landfill (LF) and other few threats (FT). We selected three lines of evidence (LOE) that were used separately and integrated into a index: water quality (WQI) and macroinvertebrate community (AAMBI) indices and phytotoxicity tests. Streams affected by UA and LF had the lowest scores to WQI and phytotoxicity, and by GM had the lowest scores to AAMBI. Macroinvertebrate absence in GM should be considered as a warning signal of long-term mining impacts in the area. The integrated LOE index showed that sites with identified threats had 30%-53% stream quality decline compared to FT sites. The use of the selected LOE seems to be a useful tools for long-term monitoring and evaluation of this sensitive aquatic ecosystem.

Record of trace organic contaminants in a river sediment core: From historical wastewater management to historical use

Some trace organic contaminants (TrOCs) can be considered as ubiquitous contaminants since the 1950s, and the study of their historical distribution within river sediments allows us to better understand the temporal variation of the chemical quality of sediments, and make assumptions about the most insightful forcings impacting these distributions. In this study, the occurrence of 41 TrOCs of various classes (i.e. pharmaceutical products and pesticides) was studied in a sedimentary core sampled in a disused dock along the Seine River, France. This core covers a 60 year-long period between 1944 and 2003, and 23 TrOCs were detected at least once. Their concentrations mainly ranged between 1 and 10 ng g^-1 within the core, except for tetracycline that exhibited higher concentrations (~hundreds of ng·g^-1). The dating of the core, based on previous studies, enabled the characterization of the changes since 1945, potentially impacted by (i) the sewer connectivity, (ii) the upgrading of wastewater treatment technologies, (iii) historical modifications in the use of each TrOC, and (iv) the sedimentary composition. In every case the deepest occurrence of each TrOC in the core matched its market authorization date, indicating the potential of TrOC to be used as chronomarkers. This study also reveals that the recent upgrading of wastewater treatment technologies within the watershed decreased the concentrations of each TrOC, despite an increase in TrOC diversity in the most recent years.

Distribution and toxicity of persistent organic pollutants and methoxylated polybrominated diphenylethers in different tissues of the green turtle Chelonia mydas

Investigating environmental pollution is important to understand its impact on endangered species such as green turtles (Chelonia mydas). In this study, we investigated the accumulation and potential toxicity of selected persistent organic pollutants (POPs) and naturally occurring MeO-PBDEs in liver, fat, kidney and muscle of turtles (n = 30) of different gender, size, year of death, location and health status. Overall, POP concentrations were low and accumulation was highest in liver and lowest in fat which is likely due to the poor health of several animals, causing a remobilization of lipids and associated compounds. PCBs and p,p'-DDE dominated the POP profiles, and relatively high MeO-PBDE concentrations (2'-MeO-BDE 68 up to 192 ng/g lw, 6-MeO-BDE 47 up to 79 ng/g lw) were detected in all tissues. Only few influences of factors such as age, gender and location were found. While concentrations were low compared to other marine wildlife, biological toxicity equivalences obtained by screening the tissue extracts using the micro-EROD assay ranged from 2.8 to 356 pg/g and the highest values were observed in muscle, followed by kidney and liver. This emphazises that pollutant mixtures found in the turtles have the potential to cause dioxin-like effects in these animals and that dioxin-like compounds should not be overlooked in future studies.

Suspect and non-target screening: the last frontier in environmental analysis

Suspect and non-target screening (SNTS) techniques are arising as new analytical strategies useful to disentangle the environmental occurrence of the thousands of exogenous chemicals present in our ecosystems. The unbiased discovery of the wide number of substances present over environmental analysis needs to find a consensus with powerful technical and computational requirements, as well as with the time-consuming unequivocal identification of discovered analytes. Within these boundaries, the potential applications of SNTS include the studies of environmental pollution in aquatic, atmospheric, solid and biological samples, the assessment of new compounds, transformation products and metabolites, contaminant prioritization, bioremediation or soil/water treatment evaluation, and retrospective data analysis, among many others. In this review, we evaluate the state of the art of SNTS techniques going over the normalized workflow from sampling and sample treatment to instrumental analysis, data processing and a brief review of the more recent applications of SNTS in environmental occurrence and exposure to xenobiotics. The main issues related to harmonization and knowledge gaps are critically evaluated and the challenges of their implementation are assessed in order to ensure a proper use of these promising techniques in the near future.

A margin of safety approach for the assessment of environmentally realistic chemical mixtures in the marine environment based on combined passive sampling and ecotoxicity testing

Organisms in the marine environment are being exposed to an increasing variety of chemicals. This research presents an effect-based monitoring method for the derivation of a margin of safety for environmentally realistic chemical mixtures. The method is based on a combination of passive sampling and ecotoxicity testing. First, passive sampling was performed using H₂O-philic divinylbenzene Speedisks during 3 sampling campaigns between 2016 and 2018 at 4 sampling locations in the Belgian part of the North Sea. Next, we exposed the marine diatom Phaeodactylum tricornutum to Speedisk extracts that were reconstituted in HPLC-grade water and defined the MoS of each sample as the highest no-observed effect concentration, expressed as relative enrichment factor (REF). A REF was defined by comparing the concentrations of 89 personal care products, pesticides and pharmaceuticals in the biotest medium with those measured in water grab samples to relate exposure concentrations in the tests to environmental concentrations. Across eight marine samples, diatom growth inhibition was observed at REF ≥ 3.2 and margins of safety were found between REF 1.1-11.0. In addition, we found that reconstitution of extracts in HPLC-water was suitable to overcome the solvent-related challenges in biotesting that are usually associated with passive sampler extract spiking, whilst it still allowed REFs up to 44 in the biotest medium to be achieved. This method, however, likely covers mainly the polar fraction of environmentally realistic chemical mixtures and less the non-polar fraction. Nevertheless, for 5 out of 8 samples, the Margin of Safety (MoS) was found to be lower than 10, which represents the typically lowest possible assessment factor applied to no effects ecotoxicological data in conventional environmental risk assessments, suggesting ecological risks for these samples.

Development of a framework to derive effect-based trigger values to interpret CALUX data for drinking water quality

Bioassays are increasingly being implemented for water quality monitoring as targeted chemical analyses are not always sufficient for the detection of all emerging chemicals or transformation products. However, the interpretation of bioassay results remains challenging, in particular because a positive response does not necessarily indicate that there may be an increased risk. For this purpose, effect-based trigger (EBT) values have been introduced as thresholds above which action needs to be undertaken to determine the cause of the response. The goals of this study were to (i) evaluate various approaches used to determine EBT values and (ii) based on the findings, derive human health EBT values for Chemical Activated LUciferase gene eXpression (CALUX) in vitro bioassays used for routine monitoring of water quality in the Netherlands. Finally, (iii) an uncertainty analysis was carried out to determine the protective power of the derived EBT values and the chance that potentially harmful substances might not be detected. EBT values that can be implemented in routine monitoring could be determined for four of eight selected bioassays. These EBT were compared to bioassay results from routine water quality monitoring carried out in the Netherlands. Furthermore, a framework for the calculation and evaluation of derived EBT values for routine application to monitor drinking water and its sources is proposed.