Identification of polar organic chemicals in the aquatic foodweb: Combining high-resolution mass spectrometry and trend analysis

Environmental risk assessment of chemical contaminants requires prioritizing of substances taken up by biota as it is a starting point for potential adverse effects. Although knowledge about the occurrence of known chemical pollutants in aquatic organisms has significantly improved during the last decade, there is still a poor understanding for a broad range of more polar compounds. To tackle this issue, we proposed an approach that identifies bioaccumulative and biomagnifiable polar chemicals using liquid chromatography coupled with electrospray ionization to high resolution tandem mass spectrometry (LC-HRMS/MS) and combine it with trend analysis using hierarchical clustering. As a proof-of-concept, this approach was implemented on various organisms and compartments (sediment, litter leaves, periphytic biofilm, invertebrates and fish) collected from a small urban river. HRMS/MS data measured via data-independent acquisition mode were retrospectively analysed using two analytical strategies: (1) retrospective target and (2) suspect/non-target screening. In the retrospective target analysis, 56 of 361 substances spanning a broad range of contaminant classes were detected (i.e. 26 in fish, 18 in macroinvertebrates, 28 in leaves, 29 in periphyton and 32 in sediments, with only 7 common to all compartments), among which 49 could be quantified using reference standards. The suspect screening approach based on two suspect lists (in-house, Norman SusDat) led to the confirmation of 5 compounds with standards (three xenobiotics at level 1 and two lipids at level 2) and tentative identification of seven industrial or natural chemicals at level 2 and 3 through a mass spectra library match. Overall, this proof-of-concept study provided a more comprehensive picture of the exposure of biota to emerging contaminants (i.e., the internal chemical exposome) and potential bioaccumulation or biomagnification of polar compounds along the trophic chain.

[Towards eco-responsible medical devices : life cycle analysis of medicine cups]

Human Health relies on Environmental Health, we thus must assess the environmental impact of healthcare systems. Life cycle analysis (LCA) quantifies the impacts on : human health, climate change, ecosystems and resources. This technique allows for evaluation of the environmental impacts of objects or processes. This article assessed the LCA of three medical cups to identify their specific strengths and weaknesses.

The Amphibian Short-Term Assay: Evaluation of a New Ecotoxicological Method for Amphibians Using Two Organophosphate Pesticides Commonly Found in Nature-Assessment of Behavioral Traits

Neurotoxic pesticides are used worldwide to protect crops from insects; they are recognized to impact nontarget organisms that live in areas surrounded by treated crops. Many biochemical and cell-based solutions have been developed for testing insecticide neurotoxicity. Nevertheless, such solutions provide a partial assessment of the impact of neurotoxicity, neglecting important phenotypic components such as behavior. Behavior is the apical endpoint altered by neurotoxicity, and scientists are increasingly recommending including behavioral endpoints in available tests or developing new methods for assessing contaminant-induced behavioral changes. In the present study, we extended an existing protocol (the amphibian short-term assay) with a behavioral test. To this purpose, we developed a homemade device along with an open-source computing solution for tracking trajectories of Xenopus laevis tadpoles exposed to two organophosphates insecticides (OPIs), diazinon (DZN) and chlorpyrifos (CPF). The data resulting from the tracking were then analyzed, and the impact of exposure to DZN and CPF was tested on speed- and direction-related components. Our results demonstrate weak impacts of DZN on the behavioral components, while CPF demonstrated strong effects, notably on speed-related components. Our results also suggest a time-dependent alteration of behavior by CPF, with the highest impacts at day 6 and an absence of impact at day 8. Although only two OPIs were tested, we argue that our solution coupled with biochemical biomarkers is promising for testing the neurotoxicity of this pesticide group on amphibians. Environ Toxicol Chem 2023;42:1595-1606. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

The Amphibian Short-Term Assay: Evaluation of a New Ecotoxicological Method for Amphibians Using Two Organophosphate Pesticides Commonly Found in Nature-Assessment of Biochemical, Morphological, and Life-History Traits

Amphibia is the most threatened class among vertebrates, with >40% of the species threatened with extinction. Pollution is thought to alter amphibian population dynamics. With the growing interest in behavioral ecotoxicology, the neurotoxic organophosphate pesticides are of special concern. Understanding how exposure to neurotoxics leads to behavioral alterations is of crucial importance, and mechanistic endpoints should be included in ecotoxicological methods. In the present study, we tested an 8-day assay to evaluate the toxicity of two organophosphates, diazinon and chlorpyrifos, on Xenopus laevis, that is, on biochemical, morphological, and life-history traits related to locomotion capacities. The method involves measuring biomarkers such as glutathione-S-transferase (GST) and ethoxyresorufin-O-deethylase (EROD; two indicators of the detoxifying system) in the 8-day-old larvae as well as acetylcholinesterase (AChE) activity (involved in the nervous system) in 4-day-old embryos and 8-day-old larvae. Snout-to-vent length and snout-to-tail length of 4-day-old embryos and 8-day larvae were recorded as well as the corresponding growth rate. Fin and tail muscle widths were measured as well for testing changes in tail shape. Both tests showed effects of both organophosphates on AChE activity; however, no changes were observed in GST and EROD. Furthermore, exposure to chlorpyrifos demonstrated impacts on morphological and life-history traits, presaging alteration of locomotor traits. In addition, the results suggest a lower sensitivity to chlorpyrifos of 4-day-old embryos compared to 8-day-old larvae. Tests on other organophosphates are needed to test the validity of this method for the whole organophosphate group. Environ Toxicol Chem 2022;41:2688-2699. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Study on the Establishment of the Gastropod Lymnaea stagnalis (Linné, 1758) as a Bio-sentinel to Monitor the Water Quality of North Algerian Rivers: Case of the El-Malah River

Biomonitoring is a key solution for assessing the effects and risks of pollutants to preserve the most vulnerable ecosystems, including aquatic ecosystems. This study aims in establishing the gastropod Lymnaea stagnalis, as a sentinel species to assess the water quality of the El-Malah river in the Algerian North-West. Three sites were chosen along the river: upstream (US), midstream (MS), and downstream (DS). The responsiveness of the aquatic snails has been compared using physiological and biological markers: condition index (CI), volumetric condition index (VCI), acetylcholinesterase (AChE), glutathione s-transferase (GST), and catalase (CAT). Additionally, the occurrence of changes in biometric parameters of the specimens has also been treated: shell height (SH), shell thickness (ST) total weight (TW), and the ratio ST/SH. Snails from the site MS reacted in front to the water deterioration with low biometric values (ST 1.28 ± 0.17 cm; SH 1.83 ± 0.20 cm; TW 2.95 ± 0.69 cm), and condition indices values (CI 31.19 ± 3.58; VCI 2.09 ± 0.53 g.cm-3), thereby signaling smaller individuals compared to the population of site US. Whereas, no specimen was recorded in the site submitted to wastewaters discharge (DS). This indicates that the degradation of the water quality affected the growth and the viability of the snails. Furthermore, a significant induction in the GST activity (88.98 ± 10.72 nmol min-1mg-1), and a significant inhibition in the CAT activity (82.85 ± 9.49 μmol min-1mg-1) were recorded in the site MS, whereas no statistically significant variation was observed in AChE activity. L. stagnalis demonstrated biological and physiological variability between the studied contrasting sites of the El-Malah River. These results allow us to propose this species as a model in the ecotoxicology of western Algerian freshwaters.

Efficiency of Several Cytochrome P450 Biomarkers in Highlighting the Exposure of Daphnia magna to an Organophosphate Pesticide

The cytochromes P450 (CYP450) represent a major enzyme family operating mostly in the first step of xenobiotic detoxification in aquatic organisms. The ability to measure these CYP450 enzymes' activities provides a crucial tool to understand organisms' response to chemical stressors. However, research on CYP450 activity measurement is still limited and has had variable success. In the present study, we optimize, compile, and compare existing scientific information and techniques for a series of CYP450 biomarkers (EROD, MROD, ECOD, APND, and ERND) used on Daphnia magna. Additionally, we explored these CYP450 biomarkers' activities through the first 5 days of life of daphnids, providing a link between their age and sensitivity to chemicals. In the experiment, daphnids were exposed to an organophosphate pesticide (diazinon) from birth to measure the molecular response of the detoxification process. Our results suggest EROD as the most applicable biomarker for organisms such as D. magna, with a higher organophosphate detoxification rate in daphnids that are 2 and 5 days old. Additionally, a larger body size allowed a more accurate EROD measurement; hence, we emphasize the use of 5-day-old daphnids when analyzing their detoxification response.

Translating Planetary Health Principles Into Sustainable Primary Care Services

Global anthropogenic environmental degradations such as climate change are increasingly recognized as critical public health issues, on which human beings should urgently act in order to preserve sustainable conditions of living on Earth. "Planetary Health" is a breakthrough concept and emerging research field based on the recognition of the interdependent relationships between living organisms-both human and non-human-and their ecosystems. In that regards, there have been numerous calls by healthcare professionals for a greater recognition and adoption of Planetary Health perspective. At the same time, current Western healthcare systems are facing their limits when it comes to providing affordable, equitable and sustainable healthcare services. Furthermore, while hospital-centrism remains the dominant model of Western health systems, primary care and public health continue to be largely undervalued by policy makers. While healthcare services will have to adapt to the sanitary impacts of environmental degradations, they should also ambition to accompany and accelerate the societal transformations required to re-inscribe the functioning of human societies within planetary boundaries. The entire health system requires profound transformations to achieve this, with obviously a key role for public health. But we argue that the first line of care represented by primary care might also have an important role to play, with its holistic, interdisciplinary, and longitudinal approach to patients, strongly grounded in their living environments and communities. This will require however to redefine the roles, activities and organization of primary care actors to better integrate socio-environmental determinants of health, strengthen interprofessional collaborations, including non-medical collaborations and more generally develop new, environmentally-centered models of care. Furthermore, a planetary health perspective translated in primary care will require the strengthening of synergies between institutions and actors in the field of health and sustainability.

Uptake, tissue distribution and toxicological effects of environmental microplastics in early juvenile fish Dicentrarchus labrax

As the smallest environmental microplastics (EMPs), even at nanoscale, are increasingly present in the environment, their availability and physical and chemical effects on marine organisms are poorly documented. In the present study, we primarily investigated the uptake and accumulation of a mixture of environmental microplastics (EMPs) obtained during an artificial degradation process in early-juvenile sea bass (Dicentrarchus labrax). Moreover, we evaluated their hazardous effects using biochemical markers of cytotoxicity. Polymer distribution and composition in gill, gut, and liver were analyzed using polarized light microscopy (PLM) and Raman microspectroscopy (RMS). Our findings revealed the size-dependent ingestion and accumulation of smaller MPs (0.45-3 µm) in fish tissues even after a short-term exposure (3 and 5 days). In addition to MPs, our results showed the presence of plastic additives including plasticizers, flame retardants, curing agents, heat stabilizers, and fiber-reinforced plastic materials in fish tissues, which contributed mostly to the larger-sized range (≥ 1.2 µm). Our data showed that significant oxidative alterations were highly correlated with MPs size range. Our results emphasized that the toxicity of smaller EMPs (≤ 3 µm) was closely related to different factors, including the target tissue, exposure duration, size range of MPs, and their chemical properties.

Modelling the effects of PSII inhibitor pulse exposure on two algae in co-culture

A weakness of standard testing procedures is that they do not consider interactions between organisms, and they focus only on single species. Furthermore, these procedures do not take into account pulse exposure. However, pulse exposure is of particular importance because in streams, after crop application and during and after precipitation, herbicide concentrations fluctuate widely and can exceed the Annual Average Environmental Quality Standards (AA-EQS), which aim to protect the aquatic environment. The sensitivity of the algae Scenedesmus vacuolatus and Pseudokirchneriella subcapitata in a co-culture exposed to pulses is thus analysed in this study. As a first step, the growths of the algae in co-culture are investigated. For initial cell densities fixed, respectively, to 100,000 and 50,000 cells/mL, the growth of each alga is exponential over at least 48 h. S. vacuolatus seems to influence the growth of P. subcapitata negatively. Allelopathy is a possible explanation for this growth inhibition. The toxicity of the herbicide isoproturon is later tested on the algae S. vacuolatus and P. subcapitata cultured alone and in the co-culture. Despite the supplementary stress on the algae in the co-culture competing for nutrients, the toxicity of the herbicide is lower for the two algae when they are in the co-culture than when they are in separated culture. A model is adapted and used to predict the cell-density inhibition on the alga S. vacuolatus in the co-culture with the alga P. subcapitata exposed to a pulse concentration of isoproturon. Four laboratory experiments are performed to validate the model. The comparison between the laboratory and the modelled effects shows good agreement. The differences can be considered minor most of time. For future studies, it is important to ensure that the cell count is precise, as it is used to determine the parameters of the model. The differences can be also induced by the fact that the cell number of the alga P. subcapitata re-suspended in a new OECD medium after the centrifugation process cannot be fixed.

Assessing watercourse quality: challenges in implementing European and Swiss legal frameworks

Hydro-climatic changes and the increasing release of pollutants into rivers by human activities tend to affect the quality of watercourses, to alter aquatic ecosystems and to reduce the amount of useable water. The ecological and chemical states of rivers and their evolution is thus of growing concern. In Europe and Switzerland, water policies are progressively shifting towards a holistic approach of river systems. The European Commission notably established a framework to highlight rivers' ecological deficits and to enhance regional or local water management plans. In Switzerland, a similar framework is currently under development. In this paper, both procedures are compared and implemented in a Swiss catchment dominated by agricultural activities. The aim is to define the challenges that still need to be addressed to assess and sustain river health. The hydromorphological, ecological, and ecotoxicological quality of the river was evaluated. Both frameworks highlighted the fact that no section of the river can currently be classified as being in a good environmental state and that the state deteriorates as tributaries and wastewater discharge flow into the main riverbed. Chemical issues and water quality changes due to hydro-climatic variations and management strategies were also pinpointed. Both frameworks are thus useful tools to survey changes in rivers quality in space and over time. However, challenges remain regarding the appropriate strategies to monitor and analyze chemicals, the definition of target values and conditions, the evaluation and integration of human-induced pressures, and the overall evaluation of the state of a river. The development of integrated indicators or of ecosystem services approaches is considered as a potential solution to explore river health and to define efficient restoration measures by water managers.

Spatial distribution and biological effects of trace metals (Cu, Zn, Pb, Cd) and organic micropollutants (PCBs, PAHs) in mussels Mytilus galloprovincialis along the Algerian west coast

Native mussels Mytilus galloprovincialis are used as bioindicator organisms to assess the concentration levels and toxic effects of persistent chemicals, polychlorobiphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and heavy metals using biomarker responses, such as catalase (CAT), glutathione s-transferase (GST), and condition indices, for the Algerian coast. The results show that mussels of Oran Harbour are extremely polluted by PCBs and PAHs, i.e., 97.6 and 2892.1μg/kg d.w., respectively. Other sites present low levels of pollution. Furthermore, high concentrations of zinc, lead and cadmium are found in mussels from fishing, agricultural and estuarine sites, respectively, while low concentrations of copper are found in all of the sites studied. CAT activity is negatively correlated with Cd and Cu, and Zn is positively correlated with GST and CAT. Site classification tools reveal the potential toxicity of coastal areas exposed to anthropogenic pressure and a gradient of toxicity along the Algerian west coast.

The 2015 Annual Meeting of SETAC German Language Branch in Zurich (7-10 September, 2015): Ecotoxicology and environmental chemistry-from research to application

This report provides a brief review of the 20th annual meeting of the German Language Branch of the Society of Environmental Toxicology and Chemistry (SETAC GLB) held from September 7th to 10th 2015 at ETH (Swiss Technical University) in Zurich, Switzerland. The event was chaired by Inge Werner, Director of the Swiss Centre for Applied Ecotoxicology (Ecotox Centre) Eawag-EPFL, and organized by a team from Ecotox Centre, Eawag, Federal Office of the Environment, Federal Office of Agriculture, and Mesocosm GmbH (Germany). Over 200 delegates from academia, public agencies and private industry of Germany, Switzerland and Austria attended and discussed the current state of science and its application presented in 75 talks and 83 posters. In addition, three invited keynote speakers provided new insights into scientific knowledge 'brokering', and-as it was the International Year of Soil-the important role of healthy soil ecosystems. Awards were presented to young scientists for best oral and poster presentations, and for best 2014 master and doctoral theses. Program and abstracts of the meeting (mostly in German) are provided as Additional file 1.

Dynamics of active pharmaceutical ingredients loads in a Swiss university hospital wastewaters and prediction of the related environmental risk for the aquatic ecosystems

The wastewater contamination of a Swiss university hospital by active pharmaceutical ingredient (API) residues was evaluated with a three months monitoring campaign at the outlet of the main building. Flow-proportional samples were collected with an automatic refrigerated sampler and analyzed for 15 API, including antibiotics, analgesics, antiepileptic and anti-inflammatory drugs, by using a validated LC-MS/MS method. The metals Gd and Pt were also analyzed using ICP-MS. Measured concentrations were compared to the predicted ones calculated after the drug average consumption data obtained from the hospital pharmacy. The hospital contribution to the total urban load was calculated according to the consumption data obtained from city pharmacies. Lastly, the environmental hazard and risk quotients (RQ) related to the hospital fraction and the total urban consumption were calculated. Median concentrations of the 15 selected compounds were ranging from 0.04 to 675 μg/L, with a mean detection frequency of 84%. The ratio between predicted and measured environmental concentrations (PEC/MEC) has shown a good accuracy for 5 out of 15 compounds, revealing over- and under-estimations of the PEC model. Mean daily loads were ranging between 0.01 and 14.2g/d, with the exception of paracetamol (109.7 g/d). The hospital contribution to the total urban loads varied from 2.1 to 100% according to the compound. While taking into account dilution and removal efficiencies in wastewater treatment plant, only the hospital fraction of the antibiotics ciprofloxacin and sulfamethoxazole showed, respectively, a high (RQ>1) and moderate (RQ>0.1) risk for the aquatic ecosystems. Nevertheless, when considering the total urban consumption, 7 compounds showed potential deleterious effects on aquatic organisms (RQ>1): gabapentin, sulfamethoxazole, ciprofloxacin, piperacillin, ibuprofen, diclofenac and mefenamic acid. In order to reduce inputs of API residues originating from hospitals various solutions can be envisioned. With results of the present study, hospital managers can start handling this important issue.

Multigenerational effects of the anticancer drug tamoxifen and its metabolite 4-hydroxy-tamoxifen on Daphnia pulex

Tamoxifen and its metabolite 4-hydroxy-tamoxifen (4OHTam) are two potent molecules that have anticancer properties on breast cancers. Their medical use is expected to increase with the increasing global cancer rate. After consumption, patients excrete tamoxifen and the 4OHTam metabolite into wastewaters, and tamoxifen has been already detected in wastewaters and natural waters. The concentrations of 4OHTam in waters have never been reported. A single study reported 4OHTam effects on the microcrustacean Daphnia pulex. The effects of tamoxifen and 4OHTam over more than two generations are unknown in aquatic invertebrates. The main goal of this study was to assess the long-term sensitivity of the microcrustacean D. pulex over four generations, based on size, reproduction, viability and the intrinsic rate of natural increase (r). Additional experiments were carried out to observe whether the effects of tamoxifen and 4OHTam were reversible in the next generation after descendants were withdrawn from chemical stress (i.e., recovery experiment), and whether the lowest test concentration of each chemical induced toxic effects when both concentrations were combined (i.e., mixture experiments). Our results showed that tamoxifen and 4OHTam induced the adverse effects at environmentally relevant concentrations. Tamoxifen and 4OHTam impaired size, viability, reproduction and the r in four generations of treated D. pulex, but these effects were not clearly magnified over generations. Tamoxifen was more potent than 4OHTam on D. pulex. When used in a mixture, the combination of tamoxifen and 4OHTam induced effects in offspring, whereas no effects were observed when these chemicals were tested individually. In the recovery experiment, the reproduction and size were reduced in offspring withdrawn from chemical exposures. Our results suggested that tamoxifen and its metabolite may be a relevant pharmaceutical to consider in risk assessment.

Comparison of specific versus literature species sensitivity distributions for herbicides risk assessment

Species sensitivity distributions (SSDs) are an important predictive tool in risk assessment. Usually, literature data are used to build SSDs that are mostly based on planktonic species. But, to get adequate protective thresholds for environmental communities, one could argue that SSD should be built on ecotoxicological data obtained from species found in the ecosystem that should be protected. This is particularly true when benthic algae are of concern. Due to the lack of literature data, building SSD on benthic microalgae is difficult. This paper aims in comparing SSDs, and thus protective thresholds (hazardous concentration that affects 5% of the species of a community, HC5), built on ecotoxicological data obtained (1) from literature and (2) with specific bioassays on benthic diatoms from a lake. Thresholds were derived for protection against four herbicides separately and for a mixture of them. Sensitivity data obtained from literature were statistically lower than the specific data for all herbicides: Species tested in the literature were usually more sensitive (mainly chlorophytes), leading to more protective lower HC5. The HC5 thresholds (literature or specific) derived for protection against the mixture were also compared to the observed sensitivity of an assemblage of benthic diatom species exposed to an increasing range of herbicide mixture concentrations. We observed that one species within the assemblage (Fragilaria rumpens) was affected at a concentration below both the literature and the specific HC5 thresholds.

Modelling the effect of exposing algae to pulses of S-metolachlor: How to include a delay to the onset of the effect and in the recovery

In agriculture, herbicides are applied to improve crop productivity. During and after rain event, herbicides can be transported by surface runoff in streams and rivers. As a result, the exposure pattern in creeks is time-varying, i.e., a repeated pollution of aquatic system. In previous studies, we developed a model to assess the effects of pulse exposure patterns on algae. This model was validated for triazines and phenylureas, which are substances that induce effects directly after exposure with no delay in recovery. However, other herbicides display a mode of action characterized by a time-dependency effect and a delay in recovery. In this study, we therefore investigate whether this previous model could be used to assess the effects of pulse exposure by herbicides with time delay in effect and recovery. The current study focuses on the herbicide S-metolachlor. We showed that the effect of the herbicide begins only after 20 h of exposure for the alga Scenedesmus vacuolatus based on both the optical density and algal cells size measurements. Furthermore, the duration of delay of the recovery for algae previously exposed to S-metolachlor was 20 h and did not depend on the pulse exposure duration or the height of the peak concentration. By accounting for these specific effects, the measured and predicted effects were similar when pulse exposure of S-metolachlor is tested on the alga S. vacuolatus. However, the sensitivity of the alga is greatly modified after being previously exposed to a pulse of S-metolachlor. In the case of scenarios composed of several pulses, this sensitivity should be considered in the modelling. Therefore, modelling the effects of any pulse scenario of S-metolachlor on an alga is feasible but requires the determination of the effect trigger, the delay in recovery and the possible change in the sensitivity of the alga to the substance.

Modelling the effects of pulse exposure of several PSII inhibitors on two algae

Subsequent to crop application and during precipitation events, herbicides can reach surface waters in pulses of high concentrations. These pulses can exceed the Annual Average Environmental Quality Standards (AA-EQS), defined in the EU Water Framework Directive, which aims to protect the aquatic environment. A model was developed in a previous study to evaluate the effects of pulse exposure for the herbicide isoproturon on the alga Scenedesmus vacuolatus. In this study, the model was extended to other substances acting as photosystem II inhibitors and to other algae. The measured and predicted effects were equivalent when pulse exposure of atrazine and diuron were tested on S. vacuolatus. The results were consistent for isoproturon on the alga Pseudokirchneriella subcapitata. The model is thus suitable for the effect prediction of phenylureas and triazines and for the algae used: S. vacuolatus and P. subcapitata. The toxicity classification obtained from the dose-response curves (diuron>atrazine>isoproturon) was conserved for the pulse exposure scenarios modelled for S. vacuolatus. Toxicity was identical for isoproturon on the two algae when the dose-response curves were compared and also for the pulse exposure scenarios. Modelling the effects of any pulse scenario of photosystem II inhibitors on algae is therefore feasible and only requires the determination of the dose-response curves of the substance and growth rate of unexposed algae. It is crucial to detect the longest pulses when measurements of herbicide concentrations are performed in streams because the model showed that they principally affect the cell density inhibition of algae.

Prioritization methodology for the monitoring of active pharmaceutical ingredients in hospital effluents

The important number of active pharmaceutical ingredients (API) available on the market along with their potential adverse effects in the aquatic ecosystems, lead to the development of prioritization methods, which allow choosing priority molecules to monitor based on a set of selected criteria. Due to the large volumes of API used in hospitals, an increasing attention has been recently paid to their effluents as a source of environmental pollution. Based on the consumption data of a Swiss university hospital, about hundred of API has been prioritized following an OPBT approach (Occurrence, Persistence, Bioaccumulation and Toxicity). In addition, an Environmental Risk Assessment (ERA) allowed prioritizing API based on predicted concentrations and environmental toxicity data found in the literature for 71 compounds. Both prioritization approaches were compared. OPBT prioritization results highlight the high concern of some non steroidal anti-inflammatory drugs and antiviral drugs, whereas antibiotics are revealed by ERA as potentially problematic to the aquatic ecosystems. Nevertheless, according to the predicted risk quotient, only the hospital fraction of ciprofloxacin represents a risk to the aquatic organisms. Some compounds were highlighted as high-priority with both methods: ibuprofen, trimethoprim, sulfamethoxazole, ritonavir, gabapentin, amoxicillin, ciprofloxacin, raltegravir, propofol, etc. Analyzing consumption data and building prioritization lists helped choosing about 15 API to be monitored in hospital wastewaters. The API ranking approach adopted in this study can be easily transposed to any other hospitals, which have the will to look at the contamination of their effluents.

The anticancer drug metabolites endoxifen and 4-hydroxy-tamoxifen induce toxic effects on Daphnia pulex in a two-generation study

Although pharmaceutical metabolites are found in the aquatic environment, their toxicity on living organisms is poorly studied in general. Endoxifen and 4-hydroxy-tamoxifen (4OHTam) are two metabolites of the widely used anticancer drug tamoxifen for the prevention and treatment of breast cancers. Both metabolites have a high pharmacological potency in vertebrates, attributing prodrug characteristics to tamoxifen. Tamoxifen and its metabolites are body-excreted by patients, and the parent compound is found in sewage treatment plan effluents and natural waters. The toxicity of these potent metabolites on non-target aquatic species is unknown, which forces environmental risk assessors to predict their toxicity on aquatic species using knowledge on the parent compounds. Therefore, the aim of this study was to assess the sensitivity of two generations of the freshwater microcrustacean Daphnia pulex towards 4OHTam and endoxifen. Two chronic tests of 4OHTam and endoxifen were run in parallel and several endpoints were assessed. The results show that the metabolites 4OHTam and endoxifen induced reproductive and survival effects. For both metabolites, the sensitivity of D. pulex increased in the second generation. The intrinsic rate of natural increase (r) decreased with increasing 4OHTam and endoxifen concentrations. The No-Observed Effect Concentrations (NOECs) calculated for the reproduction of the second generation exposed to 4OHTam and endoxifen were <1.8 and 4.3 μg/L, respectively, whereas the NOECs that were calculated for the intrinsic rate of natural increase were <1.8 and 0.4 μg/L, respectively. Our study raises questions about prodrug and active metabolites in environmental toxicology assessments of pharmaceuticals. Our findings also emphasize the importance of performing long-term experiments and considering multi-endpoints instead of the standard reproduction outcome.

Integrated use of biomarkers and condition indices in mussels (Mytilus galloprovincialis) for monitoring pollution and development of biomarker index to assess the potential toxic of coastal sites

In this study, we are interested in spatial and temporal variations of the biological and physiological responses of mussels collected from contrasting marine sites regarding their levels of pollution. We measured both the conditions indices and the enzymatic biomarker expression: acetylcholinesterase (AChE), catalase (CAT) and glutathione S-transferase (GST) activity. The enzymatic biomarkers were chosen because they respond to environmental stress. Results show a significant interactions between biomarker variations and conditions indices in the industrial harbor site throughout the seasons. But no significant changes in the reference site. Furthermore, we classified the sites along the seasons according to their potential ecotoxicity, calculated based on the sum of the normalised values of the biomarkers. The results show a very high biomarker index in the impacted site with irregular changes between seasons. This biomarker index is therefore a valuable tool that could be used to classify the toxic potential of coastal sites.

Modelling the effect of fluctuating herbicide concentrations on algae growth

Herbicide concentrations fluctuate widely in watercourses after crop applications and rain events. The level of concentrations in pulses can exceed the water chronic quality criteria. In the present study, we proposed modelling the effects of successive pulse exposure on algae. The deterministic model proposed is based on two parameters: (i) the typical growth rate of the algae, obtained by monitoring growth rates of several successive batch cultures in growth media, characterizing both the growth of the control and during the recovery periods; (ii) the growth rate of the algae exposed to pulses, determined from a dose-response curve obtained with a standard toxicity test. We focused on the herbicide isoproturon and on the freshwater alga Scenedesmus vacuolatus, and we validated the model prediction based on effect measured during five sequential pulse exposures in laboratory. The comparison between the laboratory and the modelled effects illustrated that the results yielded were consistent, making the model suitable for effect prediction of the herbicide photosystem II inhibitor isoproturon on the alga S. vacuolatus. More generally, modelling showed that both pulse duration and level of concentration play a crucial role. The application of the model to a real case demonstrated that both the highest peaks and the low peaks with a long duration affect principally the cell density inhibition of the alga S. vacuolatus. It is therefore essential to detect these characteristic pulses when monitoring of herbicide concentrations are conducted in rivers.

Additive genetic variation for tolerance to estrogen pollution in natural populations of Alpine whitefish (Coregonus sp., Salmonidae)

The evolutionary potential of natural populations to adapt to anthropogenic threats critically depends on whether there exists additive genetic variation for tolerance to the threat. A major problem for water-dwelling organisms is chemical pollution, and among the most common pollutants is 17α-ethinylestradiol (EE2), the synthetic estrogen that is used in oral contraceptives and that can affect fish at various developmental stages, including embryogenesis. We tested whether there is variation in the tolerance to EE2 within Alpine whitefish. We sampled spawners from two species of different lakes, bred them in vitro in a full-factorial design each, and studied growth and mortality of embryos. Exposure to EE2 turned out to be toxic in all concentrations we tested (≥1 ng/L). It reduced embryo viability and slowed down embryogenesis. We found significant additive genetic variation in EE2-induced mortality in both species, that is, genotypes differed in their tolerance to estrogen pollution. We also found maternal effects on embryo development to be influenced by EE2, that is, some maternal sib groups were more susceptible to EE2 than others. In conclusion, the toxic effects of EE2 were strong, but both species demonstrated the kind of additive genetic variation that is necessary for an evolutionary response to this type of pollution.

Seasonal shift in the sensitivity of a natural benthic microalgal community to a herbicide mixture: impact on the protective level of thresholds derived from species sensitivity distributions

Seasonal changes in the structure and composition of a benthic microalgal community may lead to different responses to herbicide contamination during different seasons. Consequently, the thresholds derived from risk assessment tools such as species sensitivity distributions (SSDs) must allow for these changes. We built a single-substance SSD for each of four herbicides (atrazine, terbutryn, diuron and isoproturon), which was specific to the sensitivity of the benthic diatoms found in Lake Geneva, in order to derive protective thresholds for a mixture of these four herbicides using the concentration addition model. We then investigated (1) the structural parameters of a Lake Geneva benthic microalgal community during two contrasting seasons (summer 2012 and winter 2013), (2) the response of these communities to a herbicide mixture, and (3) the protective levels of the thresholds derived. The winter community was characterized by having greater biomass, diatom species richness, and diversity metrics, and lower non-diatom species richness than the summer community. The differences in the diatom communities composition in these seasons appeared to be primarily driven by the environmental nitrate concentrations and the temperature. Moreover, the species in the winter community were more resistant to herbicides than those found in the summer community. Consequently, the protective threshold for this herbicide mixture obtained in this study was in fact protective for the winter community, but not for the summer community based on their structural parameters. Thus, the protective level against herbicides of the threshold for the benthic microalgal community should take into account changes in the environmental physico-chemical conditions that strongly influence the structure and composition of the community. The fact that the succession of species over time (i.e., over the seasons) is difficult to predict introduces uncertainties into the estimation of protective thresholds and questions their applicability year round.

Critical issues in using the common mixture toxicity models concentration addition or response addition on species sensitivity distributions: a theoretical approach

The risk of chemical mixtures to ecosystems is often assessed by applying the model of concentration addition or response addition combined with species sensitivity distribution (SSD) curves. Mixture effect predictions have been shown to be consistent only when these models are applied for a single species, however, and not with several species simultaneously aggregated to SSDs. The more stringent procedure for mixture risk assessment would hence be to apply first the concentration addition or response addition models to each species separately and, in a second step, to combine the results to construct an SSD for a mixture. Unfortunately, this methodology is not applicable in most cases because the large data sets it requires are usually unavailable. Based on theoretical data sets generated, the authors aimed to characterize the difference that can exist between these 2 methodologies. Results show that the use of concentration addition on SSD directly may lead to underestimations of the mixture concentration affecting 5% or 50% of species, especially when substances present a large standard deviation in ecotoxicity data constructing their SSD. The application of response addition can lead to over- or underestimations, depending mainly on the slope of the dose–response curves of the individual species. When assessing the risk of mixtures, one must therefore keep in mind this source of error when applying concentration addition or response addition to SSDs directly.

Treatment of micropollutants in municipal wastewater: ozone or powdered activated carbon?

Many organic micropollutants present in wastewater, such as pharmaceuticals and pesticides, are poorly removed in conventional wastewater treatment plants (WWTPs). To reduce the release of these substances into the aquatic environment, advanced wastewater treatments are necessary. In this context, two large-scale pilot advanced treatments were tested in parallel over more than one year at the municipal WWTP of Lausanne, Switzerland. The treatments were: i) oxidation by ozone followed by sand filtration (SF) and ii) powdered activated carbon (PAC) adsorption followed by either ultrafiltration (UF) or sand filtration. More than 70 potentially problematic substances (pharmaceuticals, pesticides, endocrine disruptors, drug metabolites and other common chemicals) were regularly measured at different stages of treatment. Additionally, several ecotoxicological tests such as the Yeast Estrogen Screen, a combined algae bioassay and a fish early life stage test were performed to evaluate effluent toxicity. Both treatments significantly improved the effluent quality. Micropollutants were removed on average over 80% compared with raw wastewater, with an average ozone dose of 5.7 mg O3 l(-1) or a PAC dose between 10 and 20 mg l(-1). Depending on the chemical properties of the substances (presence of electron-rich moieties, charge and hydrophobicity), either ozone or PAC performed better. Both advanced treatments led to a clear reduction in toxicity of the effluents, with PAC-UF performing slightly better overall. As both treatments had, on average, relatively similar efficiency, further criteria relevant to their implementation were considered, including local constraints (e.g., safety, sludge disposal, disinfection), operational feasibility and cost. For sensitive receiving waters (drinking water resources or recreational waters), the PAC-UF treatment, despite its current higher cost, was considered to be the most suitable option, enabling good removal of most micropollutants and macropollutants without forming problematic by-products, the strongest decrease in toxicity and a total disinfection of the effluent.

Dynamics and environmental risk assessment of the herbicide glyphosate and its metabolite AMPA in a small vineyard river of the Lake Geneva catchment

The use of pesticides may lead to environmental problems, such as surface water pollution, with a risk for aquatic organisms. In the present study, a typical vineyard river of western Switzerland was first monitored to measure discharged loads, identify sources, and assess the dynamic of the herbicide glyphosate and its metabolite aminomethylphosphonic acid (AMPA). Second, based on river concentrations, an associated environmental risk was calculated using laboratory tests and ecotoxicity data from the literature. Measured concentrations confirmed the mobility of these molecules with elevated peaks during flood events, up to 4970 ng/L. From April 2011 to September 2011, a total load of 7.1 kg was calculated, with 85% coming from vineyards and minor urban sources and 15% from arable crops. Compared with the existing literature, this load represents an important fraction (6-12%) of the estimated amount applied because of the steep vineyard slopes (∼10%). The associated risk of these compounds toward aquatic species was found to be negligible in the present study, as well as for other rivers in Switzerland. A growth stimulation was nevertheless observed for the algae Scenedesmus vacuolatus with low concentrations of glyphosate, which could indicate a risk of perturbation in aquatic ecosystems, such as eutrophication. The combination of field and ecotoxicity data allowed the performance of a realistic risk assessment for glyphosate and AMPA, which should be applied to other pesticide molecules.

Substance flow analysis as a tool for mitigating the impact of pharmaceuticals on the aquatic system

Pharmaceuticals constitute an important environmental issue for receiving waters. A holistic approach, taking into consideration the sources of these compounds (hospitals, domestic use), discharges (wastewater effluent, combined sewer overflows) and related risks to the environment, is therefore needed to develop the best protection strategy. The substance flow analysis (SFA) approach, applied, for example, to the city of Lausanne, Switzerland, is an ideal tool to tackle these issues. Four substances were considered: one antibiotic (ciprofloxacin), an analgesic (diclofenac), and two anti-epileptics (carbamazepine and gabapentin). Consumption data for the main hospital of the city (916 beds) and for the population were available. Micropollutant concentrations were measured at different points of the system: wastewater inlet and outlet (WWTP), combined sewer overflows (CSO) and in the receiving waters (Vidy Bay, Lake Geneva). Measured and predicted concentrations were in agreement, except for diclofenac, for which analytical uncertainties were expected. Seven different scenarios were considered (supplementary treatment at the WWTP, at the hospital or at both places, etc.). Based on the results obtained, the supplementary treatment at the WWTP decreases the load of pharmaceuticals reaching surface water by a factor between 2 and 27, depending on the compound and on the technique. The treatment at the hospitals only influences the amount of ciprofloxacin reaching the environment and decreases the release by one third. The contribution of CSO to surface water pollution is low compared to that of the WWTP for the selected compounds. Regarding the risk for the receiving waters, ciprofloxacin was found to be the most problematic compound, with a risk quotient far above 1. In this particular case, a treatment at the WWTP is not sufficient to reduce the risk, and additional measures at the CSO or at the hospital should be considered. SFA is an ideal tool for developing the best strategy for pharmaceutical elimination, but its application depends on data availability and local conditions.

Sediment contamination assessment in urban areas based on total suspended solids

Sediment represents an important compartment in surface waters. It constitutes a habitat or spawning site for many organisms and is an essential trophic resource for higher level organisms. It can be impacted by anthropogenic activities, particularly through urban wet-weather discharges like stormwater and combined sewer overflows. An approach was presented for assessing the risks caused by urban wet-weather discharges to the sediment compartment based on total suspended solids (TSS). TSS is routinely measured in field surveys and can be considered as a tracer for urban wet-weather contamination. Three assessment endpoints linked with TSS were proposed: a) siltation of the riverbed, b) oxygen demand due to organic matter degradation and c) accumulation of ecotoxic contaminants on the riverbed (heavy metals, PAHs). These criteria were translated in terms of the maximal TSS accumulation load and exposure time (percentage of time exceeding the accumulation criteria) to account for sediment accumulation dynamics and resuspension in streams impacted by urban wet-weather discharges. These assessment endpoints were implemented in a stochastic model that calculates TSS behavior in receiving waters and allows therefore an assessment of potential impacts. The approach was applied to three Swiss case studies. For each, good agreement was found between the risk predictions and the field measurements confirming the reliability of the approach.

Risk of herbicide mixtures as a key parameter to explain phytoplankton fluctuation in a great lake: the case of Lake Geneva, Switzerland

Mixture risk assessment predictions have rarely been confronted with biological changes observed in the environment. In this study, long-term monitoring of a European great lake, Lake Geneva, provides the opportunity to assess to what extent the predicted toxicity of herbicide mixtures explains the changes in the composition of the phytoplankton community next to other classical limnology parameters such as nutrients. To reach this goal, the gradient of the mixture toxicity of 14 herbicides regularly detected in the lake was calculated using concentration addition and response addition models. A temporal gradient of toxicity was observed which decreased from 2004 to 2009. Redundancy analysis and partial redundancy analysis showed that this gradient explains a significant portion of the variation in phytoplankton community composition with and without having removed the effect of all other co-variables. Moreover, species that are significantly influenced, positively or negatively, by the decrease of toxicity in the lake over time are highlighted. It can be concluded that the herbicide mixture toxicity is one of the key parameters to explain phytoplankton changes in Lake Geneva.

Methodology to account for uncertainties and tradeoffs in pharmaceutical environmental hazard assessment

Many pharmaceutical products find their way into receiving waters, giving rise to concerns regarding their environmental impact. A procedure was proposed that enables ranking of the hazard to aquatic species and human health due to such products. In the procedure, hazard assessment is based on five of the pharmaceutical product's individual physico-chemical properties. These properties are aggregated using the weighted Euclidian distance as the utility function. The weights and physico-chemical properties are considered as random variables. Physico-chemical property uncertainty criteria are obtained from a literature review. Weight uncertainty is based on a hazard ranking from a panel of experts, the histogram of which is converted into a continuous probability density function using statistical Kernel smoothing technique. The hazard-ranking procedure was applied to a list of common pharmaceuticals used in Switzerland. The procedure is target-specific. Two rankings were presented: One giving priority to environmental protection and the other to human health. For most substances, the hazard rank depends on the target. For the Swiss case study, the ranking procedure led to the conclusion that the hormones ethinylestradiol and testosterone, along with the antibiotic erythromycin A, should be in all cases included in risk-assessment methodologies, environmental concentration estimates and regular measurement campaigns. The methodology proposed is flexible and can be extrapolated to other substances and groups of experts.

Spatial and temporal presence of a wastewater-derived micropollutant plume in Lake Geneva

This study discusses the occurrence and environmental risk associated with a micropollutant plume originating from the direct discharge of treated wastewater into the Vidy Bay of Lake Geneva, Switzerland. The temporal variations and spatial extent of the plume and its effect on the presence of 39 pharmaceuticals and other micropollutants in the Vidy Bay were assessed over a 10 month period. A pronounced plume was observed from April to October, leading to locally elevated (up to 70-fold) pharmaceutical concentrations compared to the surrounding water column. For three of the measured substances, these plume-associated concentrations were sufficiently high to pose an ecotoxicological risk. The plume depth followed the thermal lake stratification, which moved to lower depths over the course of the warm seasons. Pharmaceutical hotspots associated with the plume were detected as far as 1.5 km downstream of the effluent wastewater outfall, but concentrations typically decreased with increasing distance from the wastewater outfall as a result of dilution and photodegradation. From November to January, when uniform temperature prevailed throughout the water column, no micropollutant plumes were detected. In contrast to pharmaceuticals, most pesticides showed homogeneous concentrations throughout the Vidy Bay during the whole study period, indicating that the effluent wastewater was not their dominant source. A strong linear correlation between electrical conductivity and concentrations of wastewater-derived micropollutants was identified. This relation will allow future estimates of wastewater-derived micropollutant concentrations via simple conductivity measurements.

Samplinghelper a web-based tool to assess the reliability of sampling strategies in sewers and receiving waters

Sampling is a key step in the analysis of chemical compounds. It is particularly important in the environmental field, for example for wastewater effluents, wet-weather discharges or streams in which the flows and concentrations vary greatly over time. In contrast to the improvements that have occurred in analytical measurement, developments in the field of sampling are less active. However, sampling errors may exceed by an order of magnitude those related to analytical processes. We proposed an Internet-based application based on a sampling theory to identify and quantify the errors in the process of taking samples. This general theory of sampling, already applied to different areas, helps to answer questions related to the number of samples, their volume, their representativeness, etc. The use of the internet to host this application facilitates use of theoretical tools and raise awareness of the uncertainties related to sampling. An example is presented, which highlights the importance of the sampling step in the quality of analytical results.

Substance flow analysis as a tool for urban water management

Human activity results in the production of a wide range of pollutants that can enter the water cycle through stormwater or wastewater. Among others, heavy metals are still detected in high concentrations around urban areas and their impact on aquatic organisms is of major concern. In this study, we propose to use a substance flow analysis as a tool for heavy metals management in urban areas. We illustrate the approach with the case of copper in Lausanne, Switzerland. The results show that around 1,500 kg of copper enter the aquatic compartment yearly. This amount contributes to sediment enrichment, which may pose a long-term risk for benthic organisms. The major sources of copper in receiving surface water are roofs and catenaries of trolleybuses. They represent 75% of the total input of copper into the urban water system. Actions to reduce copper pollution should therefore focus on these sources. Substance flow analysis also highlights that copper enters surface water mainly during rain events, i.e., without passing through any treatment procedure. A reduction in pollution could also be achieved by improving stormwater management. In conclusion, the study showed that substance flow analysis is a very effective tool for sustainable urban water management.

Occurrence and fate of micropollutants in the Vidy Bay of Lake Geneva, Switzerland. Part II: micropollutant removal between wastewater and raw drinking water

The occurrence and removal of 58 pharmaceuticals, endocrine disruptors, corrosion inhibitors, biocides, and pesticides, were assessed in the wastewater treatment plant (WWTP) of the city of Lausanne, Switzerland, as well as in the effluent-receiving water body, the Vidy Bay of Lake Geneva. An analytical screening method to simultaneously measure all of the 58 micropollutants was developed based on ultra performance liquid chromatography coupled to a tandem mass spectrometer (UPLC-MS/MS). The selection of pharmaceuticals was primarily based on a prioritization study, which designated them as environmentally relevant for the Lake Geneva region. Except for the endocrine disruptor 17alpha-ethinylestradiol, all substances were detected in 24-h composite samples of wastewater entering the WWTP or in the treated effluent. Of these compounds, 40% were also detected in raw drinking water, pumped from the lake 3 km downstream of the WWTP. The contributions of dilution and degradation to micropollutant elimination between the WWTP outlet and the raw drinking water intake were established in different model scenarios using hypothetical residence times of the wastewater in Vidy Bay of 1, 4, or 90 d. Concentration decrease due to processes other than dilution was observed for diclofenac, beta-blockers, several antibiotics, corrosion inhibitors, and pesticides. Measured environmental concentrations (MECs) of pharmaceuticals were compared to the predicted environmental concentrations (PECs) determined in the prioritization study and agreed within one order of magnitude, but MECs were typically greater than the corresponding PECs. Predicted no-effect concentrations of the analgesic paracetamol, and the two antibiotics ciprofloxacin and sulfamethoxazole, were exceeded in raw drinking water samples and therefore present a potential risk to the ecosystem.

Occurrence and fate of micropollutants in the Vidy Bay of Lake Geneva, Switzerland. Part I: priority list for environmental risk assessment of pharmaceuticals

Pharmaceuticals are substances designed to have a biological effect in humans. Their presence in the environment, especially in surface waters, is of increasing concern because of their potential risk to non-target species. A large number of pharmaceuticals are on the market; for example, approximately 2,000 active ingredients are approved in Europe, and many of them have already been detected in surface water. It is therefore crucial to select the substances that may do the most harm to the environment prior to performing measurements and extensive risk assessment. In the present study, a method to determine a list of pharmaceuticals to survey in surface water is proposed. Inclusion of substances on the list was based on a screening procedure, the analytical feasibility, and previous knowledge of pharmaceuticals detected in water. The screening procedure proposed here is an improvement on the standard procedure of the European Medicine Evaluation Agency (EMEA). It is designed to decrease the number of pharmaceuticals to be evaluated in a stepwise manner, thus decreasing the number of data necessary for the evaluation. We applied our approach to determine a list of 37 pharmaceuticals and four hormones to survey in a specific region of Switzerland, the Lake Geneva area, and discussed the advantages and weak points of the method.

Effect of sequential isoproturon pulse exposure on Scenedesmus vacuolatus

Aquatic organisms are typically exposed to fluctuating concentrations of herbicides in streams. To assess the effects on algae of repeated peak exposure to the herbicide isoproturon, we subjected the alga Scenedesmus vacuolatus to two sequential pulse exposure scenarios. Effects on growth and on the inhibition of the effective quantum yield of photosystem II (PSII) were measured. In the first scenario, algae were exposed to short, 5-h pulses at high isoproturon concentrations (400 and 1000 microg/l), each followed by a recovery period of 18 h, while the second scenario consisted of 22.5-h pulses at lower concentrations (60 and 120 microg/l), alternating with short recovery periods (1.5 h). In addition, any changes in the sensitivity of the algae to isoproturon following sequential pulses were examined by determining the growth rate-EC(50) prior to and following exposure. In both exposure scenarios, we found that algal growth and its effective quantum yield were systematically inhibited during the exposures and that these effects were reversible. Sequential pulses to isoproturon could be considered a sequence of independent events. Nevertheless, a consequence of inhibited growth during the repeated exposures is the cumulative decrease in biomass production. Furthermore, in the second scenario, when the sequence of long pulses began to approach a scenario of continuous exposure, a slight increase in the tolerance of the algae to isoproturon was observed. These findings indicated that sequential pulses do affect algae during each pulse exposure, even if algae recover between the exposures. These observations could support an improved risk assessment of fluctuating exposures to reversibly acting herbicides.

Toxicity of triclosan, penconazole and metalaxyl on Caulobacter crescentus and a freshwater microbial community as assessed by flow cytometry

Biocides are widely used for domestic hygiene, agricultural and industrial applications. Their widespread use has resulted in their introduction into the environment and raised concerns about potential deleterious effects on aquatic ecosystems. In this study, the toxicity of the biocides triclosan, penconazole and metalaxyl were evaluated with the freshwater bacterium Caulobacter crescentus and with a freshwater microbial community using a combination of single- and double-stain flow cytometric assays. Growth of C.  crescentus and the freshwater community were repressed by triclosan but not by penconazole or metalaxyl at concentrations up to 250 μM. The repressive effect of triclosan was dependent on culture conditions. Caulobacter crescentus was more sensitive to triclosan when grown with high glucose at high cell density than when grown directly in sterilized lake water at low cell density. This suggests that the use of conventional growth conditions may overestimate biocide toxicity. Additional experiments showed that the freshwater community was more sensitive to triclosan than C.  crescentus, with 10 nM of triclosan being sufficient to repress growth and change the phylogenetic composition of the community. These results demonstrate that isolate-based assays may underestimate biocide toxicity and highlight the importance of assessing toxicity directly on natural microbial communities. Because 10 nM of triclosan is within the range of concentrations observed in freshwater systems, these results also raise concerns about the risk of introducing triclosan into the environment.

Determination of water quality standards for chemical mixtures: extension of a methodology developed for herbicides to a group of insecticides and a group of pharmaceuticals

Monitoring surveys throughout America and Europe have demonstrated the widespread presence of organic synthetic substances such as pesticides and pharmaceuticals in surface water. To avoid deleterious effects on the aquatic system, many countries determine water quality criteria for pesticides. For each substance, the comparison of the concentration measured in water with its criterion gives an indication of the pressure this substance put on the aquatic system. However, in the environment, aquatic organisms are not only exposed to single pesticides but typically to mixtures of these substances. It is therefore of particular importance to take mixtures into account when defining water quality criteria, which is rarely done yet. We recently developed a method to define consistent and comparable water quality criteria for mixtures of herbicides having a similar mode of action. These criteria are calculated based on species sensitivity curves; the method assumes that these curves are parallel for substances having similar mode of action. The aim of this study was to apply our method to six organophosphates (insecticides) and to three β-blockers (pharmaceuticals), other groups of compounds commonly detected in surface water. We found some evidence that the developed methodology gives consistent results for these groups too. The hypothesis of parallelism was accepted in 2/3 (β-blockers) and 2/6 of the cases (organophosphates) for both species sensitivity curves based on effect concentrations 50% and on no-observed effect concentrations. The use of water quality criteria for mixture is illustrated by two case studies, which show the importance of taking mixtures into account in water quality legislation.

S-metolachlor pulse exposure on the alga Scenedesmus vacuolatus: effects during exposure and the subsequent recovery

In streams and creeks, the aquatic flora is exposed to fluctuating concentrations of herbicides during and following their application. Peak concentrations of herbicides, like the chloroacetanilide S-metolachlor, are usually detected following rain events. In this study, we assessed the effect of S-metolachlor pulse exposure on the algae Scenedesmus vacuolatus. We measured the time-dependency of effects during exposure on algae population and identified the algae development stage most sensitive to S-metolachlor. Furthermore, we assessed the time-to-recovery of the algae following exposure. A 6h pulse exposure at 598microgl(-1) was sufficient to inhibit cell reproduction by 50%. However, the exposure period had to coincide with the cell development stage specifically inhibited by S-metolachlor, which is the end of the cell growth phase. In algae populations composed of cells at all development stages, we initially observed an increase in the size of some algal cells, ultimately leading to an inhibition of the growth rate. In these experimental conditions, effects were observed after 18h of exposure and greatly increased with time. The recovery of algae following exposure to strongly inhibiting S-metolachlor concentrations was delayed and only occurred after 29h. These findings suggest that peak exposure to S-metolachlor may affect the growth of sensitive alga in surface waters, considering that the effects extend beyond the period of exposure.

Cost-effective experimental design to support modeling of concentration-response functions

Modeling concentration-response function became extremely popular in ecotoxicology during the last decade. Indeed, modeling allows determining the total response pattern of a given substance. However, reliable modeling is consuming in term of data, which is in contradiction with the current trend in ecotoxicology, which aims to reduce, for cost and ethical reasons, the number of data produced during an experiment. It is therefore crucial to determine experimental design in a cost-effective manner. In this paper, we propose to use the theory of locally D-optimal designs to determine the set of concentrations to be tested so that the parameters of the concentration-response function can be estimated with high precision. We illustrated this approach by determining the locally D-optimal designs to estimate the toxicity of the herbicide dinoseb on daphnids and algae. The results show that the number of concentrations to be tested is often equal to the number of parameters and often related to the their meaning, i.e. they are located close to the parameters. Furthermore, the results show that the locally D-optimal design often has the minimal number of support points and is not much sensitive to small changes in nominal values of the parameters. In order to reduce the experimental cost and the use of test organisms, especially in case of long-term studies, reliable nominal values may therefore be fixed based on prior knowledge and literature research instead of on preliminary experiments.

Effect of pulse herbicidal exposure on scenedesmus vacuolatus: a comparison of two photosystem II inhibitors

Herbicide concentrations fluctuate in rivers following crop application and can reach high levels after rain events, yet the duration of these pulses is short. In the present study, we assessed the effect of atrazine and isoproturon pulse exposure on Scenedesmus vacuolatus (Chlorophyceae; strain 211-8b, Kessler) as well as the recovery in the postexposure period. We further explored whether the time-dependent toxicity is similar for herbicides inhibiting the photosystem II (PSII). The growth rate was assessed for different exposure durations, and in addition the inhibition of the effective quantum yield of PSII was measured to monitor the response at the target site. Atrazine and isoproturon did not have similar time-dependent effects on growth rate, despite their same primary mode of action on PSII. Atrazine was less toxic than isoproturon after 10 h of exposure, but the toxicity of both herbicides was similar after 48 h of exposure. However, both compounds inhibited the PSII effective quantum yield within 1 h following exposure. Similarly, the effective quantum yield recovered completely within 4 h after removal of the toxicants, leading to rapid recovery of algal growth. The rapid onset of effects of isoproturon on the growth of the alga during exposure suggests that a single pulse to this herbicide is likely to induce greater effects than an atrazine pulse at the same concentration, even if these effects are reversible. The information gained in the present study should support the effect assessment of sequential exposures as well as the risk evaluation of fluctuating herbicidal exposure.

Including mixtures in the determination of water quality criteria for herbicides in surface water

Monitoring programs throughout America and Europe have demonstrated the common occurrence of herbicides in surface water. Nevertheless, mixtures are rarely taken into account in water quality regulation. Taking mixtures into account is only feasible if the water quality criteria (WQC) of the single compounds are derived by a common and consistent methodology, which overcomes differences in data quality without settling on the lowest common denominator but making best use of all available data. In this paper, we present a method of defining a risk quotient for mixtures of herbicides with a similar mode of action (RQm). Consistent and comparable WQC are defined for single herbicides as a basis for the calculation of the RQm. Derived from the concentration addition model, the RQm can be expressed as the sum of the ratios of the measured environmental concentration and the WQC for each herbicide. The RQm should be less than one to ensure an acceptable risk to aquatic life. This approach has the advantage of being easy to calculate and communicate, and is proposed as a replacement for the current limit of 0.1 microg/L for herbicides in Switzerland. We illustrate the proposed approach on the example of five commonly applied herbicides (atrazine, simazine, terbuthylazine, isoproturon, and diuron). Their risk profile, i.e., the RQm as a function of time for one exemplary river, clearly shows that the single compounds rarely exceeded their individual WQC. However, the contribution of peaks of different seasonally applied herbicides, whose application periods partially overlap, together with the continuously emitted herbicides from nonagricultural use, results in the exceedance of the RQm threshold value of one upon several occasions.

Including mixtures in the determination of water quality criteria for herbicides in surface water

Monitoring programs throughout America and Europe have demonstrated the common occurrence of herbicides in surface water. Nevertheless, mixtures are rarely taken into account in water quality regulation. Taking mixtures into account is only feasible if the water quality criteria (WQC) of the single compounds are derived by a common and consistent methodology, which overcomes differences in data quality without settling on the lowest common denominator but making best use of all available data. In this paper, we present a method of defining a risk quotient for mixtures of herbicides with a similar mode of action (RQm). Consistent and comparable WQC are defined for single herbicides as a basis for the calculation of the RQm. Derived from the concentration addition model, the RQm can be expressed as the sum of the ratios of the measured environmental concentration and the WQC for each herbicide. The RQm should be less than one to ensure an acceptable risk to aquatic life. This approach has the advantage of being easy to calculate and communicate, and is proposed as a replacement for the current limit of 0.1 microg/L for herbicides in Switzerland. We illustrate the proposed approach on the example of five commonly applied herbicides (atrazine, simazine, terbuthylazine, isoproturon, and diuron). Their risk profile, i.e., the RQm as a function of time for one exemplary river, clearly shows that the single compounds rarely exceeded their individual WQC. However, the contribution of peaks of different seasonally applied herbicides, whose application periods partially overlap, together with the continuously emitted herbicides from nonagricultural use, results in the exceedance of the RQm threshold value of one upon several occasions.

Water quality criteria for total suspended solids (TSS) in urban wet-weather discharges

Total suspended solids (TSS) from combined sewer overflows (CSOs) and stormwater discharges represent a crucial parameter for evaluating wet-weather pollution in urban areas. In fact, the increase of TSS in water during rain events can have ecotoxic effects on aquatic organisms. Furthermore, major potentially harmful substances such as heavy metals, PAHs and organic matter are adsorbed onto TSS and later settle on sediment. Water quality criteria for TSS consequently enable the risk of wet-weather pollution to be assessed, for instance to avoid detrimental effects on aquatic organisms. The criteria proposed in this study cover the short-term impact of TSS on fish (acute quality criteria AQC), taking into account the duration of their exposure in the receiving water. The concentration-exposure duration-effect curve proposed here thus predicts "ill effects" on fish for different exposure times and TSS concentrations. The ecotoxic effects of adsorbed pollutants are also taken into account with an additional safety factor. We implement this TSS criteria in a software that allows us to estimate the number of rain events that exceed a given morbidity threshold for fishes per year.

Modeling the concentration-response function of the herbicide dinoseb on Daphnia magna (survival time, reproduction) and Pseudokirchneriella subcapitata (growth rate)

Models describing dose-response relationships are becoming increasingly popular in ecotoxicology. They allow simple and thorough evaluations of toxicity test results, including inter- and extrapolations to concentrations or exposure times other than those tested. Simple parametric regression models are of particular interest because their parameters may be attributed mechanistic meanings and they can be applied without sophisticated mathematical and computational support. We recently proposed a four-parameter logistic regression model to fit the survival data of Daphnia magna under dinoseb stress. The model parameters are the maximum survival time, the minimum time required for an individual to die, effect concentration, EC(50), and a curve shape parameter. This model has now been applied to compare the lethality and reproduction toxicity of D. magna and the growth inhibition of Pseudokirchneriella subcapitata under dinoseb stress. It can be fitted adequately to all the measured data and the parameters can be attributed biological meanings in any of the three endpoints. A comparison of the modeled concentration-response functions of all three endpoints for dinoseb toxicity shows that the range of ECs with respect to both D. magna and algae is steep (a decrease of between 0.1 and 0.6 mg/L). The survival and reproduction of D. magna exhibit similar characteristic concentration-response functions and toxicities. The statistical no-effect concentration (SNEC) is 0.14 (survival) and 0.11 (reproduction)mg/L, respectively. On the other hand, algae seem to be less sensitive to dinoseb than D. magna (SNEC: 0.48 mg/L). However, further investigations of individual algae may lead to a more suitable comparison. We speculate that the four parameters of the model function can be related to specific properties of chemicals and organisms. Characterization of these properties would allow simple and appropriate estimation of the toxic effects of these chemicals.

Toxicity assessment of oil-contaminated freshwater sediments

The performance of four microscale toxicity bioassays conducted on whole sediments was evaluated during a bioremediation project undertaken in 1999-2000 on a crude oil-contaminated freshwater shoreline of the St. Lawrence River, Quebec, Canada. The toxicity tests assessed included: (1) the Microtox solid-phase assay (MSPT), (2) the Biotox Flash solid-phase test (Flash), (3) the algal solid-phase assay (ASPA), and 4) the Ostracodtoxkit solid-phase assay. Data generated with these assays were compared with those obtained using the standard endobenthic amphipod (Hyalella azteca) bioassay. Bioanalytical comparisons indicated that all five solid-phase tests were useful in detecting the toxicity of oiled sediments; however, statistical analyses distinguished a difference in response between the invertebrate (amphipod and Ostracodtoxkit) and bacterial luminescence tests (MSPT and Flash). Based on these results, it is recommended that careful selection of biotests be made in the design of the test battery for assessment of residual oil sediment toxicity. Time-series toxicity data generated with ASPA indicated that oiled sediments in the freshwater wetlands of the St. Lawrence River remained toxic to phytoplankton for at least 65 weeks and that remediation treatment was able to accelerate detoxification by 16 weeks.

Development of a biomarker-based index for assessing the ecotoxic potential of aquatic sites

The use of biochemical or physiological measurements as indicators of ecotoxicity is under constant development and has the advantage of delineating effects before the appearance of disease. However, these biomarkers are often part of a battery of tests, and it is difficult to integrate them together to gain an overall view of an organism's health. The aim of this study was to develop an index that could integrate the data derived from a battery of biomarkers for application to both spatial and temporal studies. Mya arenaria clams were collected at different sites along the Saguenay Fjord (Quebec, Canada). Six biomarkers were measured: metallothioneins, DNA strand breakage, lipid peroxidation, vitellin-like proteins, phagocytosis, and non-specific esterase activity in haemocytes. A biomarker index was obtained by summing the biomarker values expressed in term of classes. Classes were determined by a distribution-free approach derived from the theory of rough sets. The results of the spatial study show that the index values discriminated well between contaminated and uncontaminated sites. The highly polluted sites had the highest index values (18 compared with a reference value of 14). In the temporal study, the index was also able to highlight possible contamination-induced alterations, even though the interpretation of temporal variation is complicated by natural variations occurring throughout the year. A control chart approach is proposed for determining contaminated sites in both spatial and temporal surveys.

Application of rough sets analysis to identify polluted aquatic sites based on a battery of biomarkers: a comparison with classical methods

The evaluation of toxicological effects at the cellular and molecular levels in organisms are often used to determine sites subjected to contamination problems that pose a threat to the long-term survival of organisms. However, the integration of multiple measurements on the health status of organisms into a model for site discrimination is challenging. This study compares two discrimination methods which are based on rule inference: rough sets (RS) analysis and classification trees (CT) with classical multivariate discriminant analysis (DA). Site classification was attempted with six biomarkers of effects: metallothionein levels, lipid peroxidation, DNA damage, levels of lipophosphoproteins (i.e., vitellins), phagocytosis activity and haemocyte cell viability on clam (Mya arenaria) populations from the Saguenay River fjord (Quebec, Canada). Rule based methods have the advantage of complete independence from data distribution constraints in contrast to the classification methods from multivariate analysis that are more commonly used in ecotoxicology. Results show that RS and CT gave better classifications than DA because they do not require strong distributional assumptions. Moreover, RS provided classification rules that could identify the most important biomarker(s) for site discrimination. RS and CT were shown to be simple and efficient methods for classifying multivariable ecotoxicological data. This methodology would be especially useful when freedom from distributional assumptions is required.