Characterization of estrogenic compounds in water samples collected from United Kingdom estuaries

Graphene Oxide, Carbon Nanotubes, and Polyelectrolytes-Based Impedanciometric E-Tongue for Estrogen Detection in Complex Matrices

Currently, it is necessary to maintain the quality of aquifers and water bodies, which means the need for sensors that detect molecules as emerging pollutants (EPs) at low concentrations in aqueous complex solutions. In this work, an electronic tongue (e-tongue) prototype was developed to detect 17β-estradiol in tap water. To achieve such a prototype, an array of sensors was prepared. Each sensor consists of a solid support with interdigitated electrodes without or with thin films prepared with graphene oxide, nanotubes, and other polyelectrolytes molecules adsorbed on them. To collect data from each sensor, impedance spectroscopy was used to analyze the electrical characteristics of samples of estrogen solutions with different concentrations. To analyze the collected data from the sensors, principal components analysis (PCA) method was used to create a three-dimensional plane using the calculated principal components, namely PC1 and PC2, and the estrogen concentration values. Then, damped least squares (DLS) was used to find the optimal values for the hyperplane calibration, as the sensitivity of this e-tongue was not represented by a straight line but by a surface. For the collected data, from nanotubes and graphene oxide sensors, a calibration curve for concentration given by the 10PC1×0.492-PC2×0.14-14.5 surface was achieved. This e-tongue presented a detection limit of 10-16 M of 17β-estradiol in tap water.

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.

Endocrine Disrupting Compounds Removal Methods from Wastewater in the United Kingdom: A Review

Endocrine disrupting compounds (EDCs) are contaminants with estrogenic or androgenic activity that negatively impact human and animal communities. These compounds have become one of the most significant concerns for wastewater treatment in recent decades. Several studies have evaluated EDC removal methods from wastewater across the globe, including the United Kingdom (UK). Accordingly, the current study reviews EDC removal methods from municipal/domestic wastewater in the United Kingdom (UK) for the period of 2010–2017. The current study analysed original research articles (250), review articles (52), short communication (43), and other associated documents via the ScienceDirect.com database. A total of 25 published articles, which covered EDC removal methods from UK wastewaters, were reviewed rigorously. The research highlights that despite the relative efficacy of existing chemical and physical methods for removing certain EDCs from wastewater, there is emerging evidence supporting the need for more widespread application of nature-based and biological approaches, particularly the use of biofilms. The analysis reveals that there have been relatively few research studies on EDC removal methods carried out in the UK in the 2010–2017 period. Only four papers addressed the removal of specific endocrine disrupting compounds from UK municipal wastewater, and none of the studies addressed EDC removal by using direct biofilms. Finally, this review suggests that more research is needed to remove EDCs, particularly through the application of biofilms, from municipal wastewater in current scenarios.

Detecting Traces of 17α-Ethinylestradiol in Complex Water Matrices

Hormones have a harmful impact on the environment and their detection in water bodies is an urgent matter. In this work, we present and analyze a sensor device able to detect traces of the synthetic hormone 17α-ethinylestradiol (EE2) below 10⁻⁹ M in media of different complexities, namely, ultrapure, mineral and tap waters. This device consists of solid supports with interdigitated electrodes without and with a polyethylenimine (PEI) and poly (sodium 4-styrenesulfonate) (PSS) layer-by-layer film deposited on it. Device response was evaluated through capacitance, loss tangent and electric modulus spectra and the data were analyzed by principal component analysis method. While the three types of spectra were demonstrated to be able to clearly discriminate the different media, loss tangent spectra allow for the detection of EE2 concentration, with a sensitivity of −0.072 ± 0.009 and −0.44 ± 0.03 per decade of concentration, for mineral and tap water, respectively. Detection limits values were found to be lower than the ones present in the literature and presenting values of 8.6 fM (2.6 pg/L) and of 7.5 fM (22.2 pg/L) for tap and mineral waters, respectively. Moreover, the obtained response values follow the same behavior with EE2 concentration in any medium, meaning that loss tangent spectra allow the quantification of EE2 concentration in aqueous complex matrices.

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

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

Examining the role of estrogenic activity and ocean temperature on declines of a coastal demersal flatfish population near the municipal wastewater outfall of Orange County, California, USA

Wastewater treatment plant effluent introduces a mixture of pollutants into marine environments; however, the impacts of chronic sublethal exposures on populations are often unclear. Presence of estrogenic agents in sediments and uptake of these compounds by demersal flatfishes has been reported at the Orange County Sanitation District (OCSD) wastewater outfall. Furthermore, estrogenic activity has been identified in male flatfish in the area, potentially contributing to observed population declines in the OCSD region. Rising ocean temperatures may further contribute to flatfish declines as relationships between temperature and abundance have been reported in the Southern California Bight. To investigate declines, sex ratios, condition factor, organ health indices, hormones, and vitellogenin were quantified in flatfish collected at OCSD outfall and reference sites. Additionally, historical temperature data was examined for trends with population abundances. Rather than being linked to estrogenic activity, results indicated that population declines were more correlated to increases in ocean temperature.

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

In vitro bioassays are increasingly used for water quality monitoring. Surface water samples often need to be enriched to observe an effect and solid-phase extraction (SPE) is commonly applied for this purpose. The applied methods are typically optimised for the recovery of target chemicals and not for effect recovery for bioassays. A review of the few studies that have evaluated SPE recovery for bioassays showed a lack of experimentally determined recoveries. Therefore, we systematically measured effect recovery of a mixture of 579 organic chemicals covering a wide range of physicochemical properties that were spiked into a pristine water sample and extracted using large volume solid-phase extraction (LVSPE). Assays indicative of activation of xenobiotic metabolism, hormone receptor-mediated effects and adaptive stress responses were applied, with non-specific effects determined through cytotoxicity measurements. Overall, effect recovery was found to be similar to chemical recovery for the majority of bioassays and LVSPE blanks had no effect. Multi-layer SPE exhibited greater recovery of spiked chemicals compared to LVSPE, but the blanks triggered cytotoxicity at high enrichment. Chemical recovery data together with single chemical effect data were used to retrospectively estimate with reverse recovery modelling that there was typically less than 30% effect loss expected due to reduced SPE recovery in published surface water monitoring studies. The combination of targeted experiments and mixture modelling clearly shows the utility of SPE as a sample preparation method for surface water samples, but also emphasizes the need for adequate controls when extraction methods are adapted from chemical analysis workflows.

Removing ethinylestradiol from wastewater by microalgae mutant Chlorella PY-ZU1 with CO2 fixation

Removal of endocrine-disrupting chemical ethinylestradiol (EE2) from wastewater by microalgal mutant Chlorella PY-ZU1 under 15% CO₂ were investigated. Moreover, the effects of EE2 on microscopic structure and antioxidation ability of microalgal cells were determined. EE2 concentrations in range of 0.01-5 mg L^-1 stimulated microalgal growth. Increasing the original EE2 concentration from 0 to 5 mg L^-1 increased the cell fractal dimension from 1.38 to 1.59 and reduced the cell size from 5.18 to 3.41 μm. Meanwhile, superoxide dismutase and catalase activities, which represented cellular antioxidant capacity, first increased from 44.59 and 0.54 U mL^-1 to peak values of 65.57 and 1.49 U mL^-1, respectively, and then correspondingly decreased to 34.36 and 0.36 U mL^-1. Malondialdehyde content that indicated the cell oxidation damage degree first decreased from 2.57 to 2.03 nmol mL^-1, then increased to 2.59 nmol mL^-1. The highest EE2 removal efficiency of 94% by Chlorella PY-ZU1 was achieved at the original EE2 concentration of 5 mg L^-1.

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

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

Co-metabolic degradation of steroid estrogens by heterotrophic bacteria and nitrifying bacteria in MBRs

Three membrane bioreactors (MBRs) with different carbon/nitrogen ratios were operated in parallel to investigate the effects of heterotrophic bacteria and nitrifying bacteria on the co-metabolic degradation of the steroid estrogens (SEs) estrone (E1) and 17α-ethinylestradiol (EE2). The functional community structures of the MBRs were analyzed using fluorescence in situ hybridization, and correlations between the functional community structures and SE removal efficiencies were established. The results showed that α-Proteobacteria, β-Proteobacteria, and γ-proteobacteria were responsible for the removal of E1, whereas ammonia-oxidizing bacteria, Nitrosomonas sp., Nitrosospira sp., Nitrospira sp., and Nitrobacter sp. were responsible for EE2 removal. Nitrifying activated sludge degraded E1 and EE2 alone, with degradation efficiencies of 71.04 and 65.51%, respectively. Moreover, biodegradation of E1 and EE2 was reduced significantly (by 30.30 and 34.03%, respectively) when nitrification was inhibited. Heterotrophic and nitrifying bacteria were responsible for E1 and EE2 degradation, but nitrification was considered to be the key process in the enhancement of SE degradation. Organic co-metabolism by heterotrophic bacteria had a significant effect on E1 removal, and nitrification co-metabolism by nitrifying bacteria had a significant effect on EE2 removal. These results improve our understanding of the co-metabolic degradation of SEs, which is useful for improving SE removal and guaranteeing the health of aqueous environments.

Assessment of a novel device for onsite integrative large-volume solid phase extraction of water samples to enable a comprehensive chemical and effect-based analysis

The implementation of targeted and nontargeted chemical screening analysis in combination with in vitro and organism-level bioassays is a prerequisite for a more holistic monitoring of water quality in the future. For chemical analysis, little or no sample enrichment is often sufficient, while bioanalysis often requires larger sample volumes at a certain enrichment factor for conducting comprehensive bioassays on different endpoints or further effect-directed analysis (EDA). To avoid logistic and technical issues related to the storage and transport of large volumes of water, sampling would benefit greatly from onsite extraction. This study presents a novel onsite large volume solid phase extraction (LVSPE) device tailored to fulfill the requirements for the successful effect-based and chemical screening of water resources and complies with available international standards for automated sampling devices. Laboratory recovery experiments using 251 organic compounds in the log D range from -3.6 to 9.4 (at pH7.0) spiked into pristine water resulted in acceptable recoveries and from 60 to 123% for 159 out of 251 substances. Within a European-wide demonstration program, the LVSPE was able to enrich compounds in concentration ranges over three orders of magnitude (1ngL^-1 to 2400ngL^-1). It was possible to discriminate responsive samples from samples with no or only low effects in a set of six different bioassays (i.e. acetylcholinesterase and algal growth inhibition, androgenicity, estrogenicity, fish embryo toxicity, glucocorticoid activity). The LVSPE thus proved applicable for onsite extraction of sufficient amounts of water to investigate water quality thoroughly by means of chemical analysis and effect-based tools without the common limitations due to small sample volumes.

Screening for contaminant hotspots in the marine environment of Kuwait using ecotoxicological and chemical screening techniques

Kuwait is a country with low rainfall and highly concentrated industrial and domestic effluents entering its coastal waters. These can be both treated and untreated. In this study we sampled a series of coastal and open-sea sites and used a variety of analyses to identify those sites requiring the most attention. We used a high throughput GC-MS screen to look for over 1000 chemicals in the samples. Estrogen and androgen screens assessed the potential to disrupt endocrine activity. An oyster embryo development screen was used to assess biological effect potential. The chemical screen identified sites which had high numbers of identified industrial and domestic chemicals. The oyster screen showed that these sites had also caused high levels of developmental abnormalities with 100% of embryos affected at some sites. The yeast screen showed that estrogenic chemicals were present in outfalls at 2-3 ng/l E2 equivalent, and detectable even in some open water sites.

Tracing thyroid hormone-disrupting compounds: database compilation and structure-activity evaluation for an effect-directed analysis of sediment

A variety of anthropogenic compounds has been found to be capable of disrupting the endocrine systems of organisms, in laboratory studies as well as in wildlife. The most widely described endpoint is estrogenicity, but other hormonal disturbances, e.g., thyroid hormone disruption, are gaining more and more attention. Here, we present a review and chemical characterization, using principal component analysis, of organic compounds that have been tested for their capacity to bind competitively to the thyroid hormone transport protein transthyretin (TTR). The database contains 250 individual compounds and technical mixtures, of which 144 compounds are defined as TTR binders. Almost one third of these compounds (n = 52) were even more potent than the natural hormone thyroxine (T₄). The database was used as a tool to assist in the identification of thyroid hormone-disrupting compounds (THDCs) in an effect-directed analysis (EDA) study of a sediment sample. Two compounds could be confirmed to contribute to the detected TTR-binding potency in the sediment sample, i.e., triclosan and nonylphenol technical mixture. They constituted less than 1 % of the TTR-binding potency of the unfractionated extract. The low rate of explained activity may be attributed to the challenges related to identification of unknown contaminants in combination with the limited knowledge about THDCs in general. This study demonstrates the need for databases containing compound-specific toxicological properties. In the framework of EDA, such a database could be used to assist in the identification and confirmation of causative compounds focusing on thyroid hormone disruption.

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

Environmental quality monitoring of water resources is challenged with providing the basis for safeguarding the environment against adverse biological effects of anthropogenic chemical contamination from diffuse and point sources. While current regulatory efforts focus on monitoring and assessing a few legacy chemicals, many more anthropogenic chemicals can be detected simultaneously in our aquatic resources. However, exposure to chemical mixtures does not necessarily translate into adverse biological effects nor clearly shows whether mitigation measures are needed. Thus, the question which mixtures are present and which have associated combined effects becomes central for defining adequate monitoring and assessment strategies. Here we describe the vision of the international, EU-funded project SOLUTIONS, where three routes are explored to link the occurrence of chemical mixtures at specific sites to the assessment of adverse biological combination effects. First of all, multi-residue target and non-target screening techniques covering a broader range of anticipated chemicals co-occurring in the environment are being developed. By improving sensitivity and detection limits for known bioactive compounds of concern, new analytical chemistry data for multiple components can be obtained and used to characterise priority mixtures. This information on chemical occurrence will be used to predict mixture toxicity and to derive combined effect estimates suitable for advancing environmental quality standards. Secondly, bioanalytical tools will be explored to provide aggregate bioactivity measures integrating all components that produce common (adverse) outcomes even for mixtures of varying compositions. The ambition is to provide comprehensive arrays of effect-based tools and trait-based field observations that link multiple chemical exposures to various environmental protection goals more directly and to provide improved in situ observations for impact assessment of mixtures. Thirdly, effect-directed analysis (EDA) will be applied to identify major drivers of mixture toxicity. Refinements of EDA include the use of statistical approaches with monitoring information for guidance of experimental EDA studies. These three approaches will be explored using case studies at the Danube and Rhine river basins as well as rivers of the Iberian Peninsula. The synthesis of findings will be organised to provide guidance for future solution-oriented environmental monitoring and explore more systematic ways to assess mixture exposures and combination effects in future water quality monitoring.

Why endocrine disrupting chemicals (EDCs) challenge traditional risk assessment and how to respond

Endocrine disrupting compounds (EDCs) are a diverse group of "chemicals of emerging concern" which have attracted much interest from the research community since the 1990s. Today there is still no definitive risk assessment tool for EDCs. While some decision making organizations have attempted to design methodology guidelines to evaluate the potential risk from this broadly defined group of constituents, risk assessors still face many uncertainties and unknowns. Until a risk assessment paradigm is designed specifically for EDCs and is vetted by the field, traditional risk assessment tools may be used with caution to evaluate EDCs. In doing so, each issue of contention should be addressed with transparency in order to leverage available information and technology without sacrificing integrity or accuracy. The challenges that EDCs pose to traditional risk assessment are described in this article to assist in this process.

Adsorption behaviors of 17α-ethinylestradiol in sediment-water system in northern Taihu Lake, China

Adsorption behavior of 17α-ethinylestradiol (EE2) in northern Taihu Lake sediment was analyzed by using batch equilibrium experiment. Freundlich isotherm could describe the adsorption thermodynamic behavior of EE2 in sediment. Sediment organic matter (SOM) contents had important impacts on the adsorption capacity for EE2. The pH values also influenced the adsorption capacity for EE2. Increase of pH value could decrease the EE2 adsorption, which might be due to the electrostatic repulsion between the anionic form of EE2 and sediments with negative charge under high pH values. Competitive effects of bisphenol A (BPA) on EE2 adsorption were further analyzed. The results showed that low concentration BPA did not have significant influences on EE2 adsorption. However, high concentration BPA could reduce EE2 adsorption, which might be due to the similar molecular diameter of BPA with adsorption sites and one more benzene ring with a hydroxyl group in BPA. These results provide primary information of EE2 adsorption in sediment-water system in Taihu Lake, which is useful for the environmental risk assessment and management of EE2 in studied area.

Toxicity screening of produced water extracts in a zebrafish embryo assay

Produced water is the largest effluent discharge from oil and gas/condensate production facilities in the North Sea. There is concern that contaminants originating from the reservoir and chemicals used in the production process may affect marine organisms. Developmental toxicity of extractable organic compounds in produced water effluents from oil and gas/condensate production platforms in the Norwegian sector of the North Sea was assessed in a temporal and spatial manner using zebrafish (Danio rerio) embryos. Large-scale solid-phase extraction (SPE) and on-column fractionation of water-soluble fraction (WSF) and an oil/particulate fraction was used in a rapid screening bioassay for embryotoxicity. Exposure to produced water extracts increased rate of mortality and reduced pigmentation and heart rate, as well as delaying time to hatch. The oil/particulate fraction was 10-fold less toxic than WSF, indicating that toxicity was predominantly produced by moderately polar and bioavailable compounds. Large spatial and temporal variation in produced water toxicity was observed, displaying considerable variability in the reservoir, oil well, and effluent composition over time. The noted toxicity did not correlate well with either reported produced water composition or parameters such as total hydrocarbons, thus challenging chemical measurements as a reliable source of information for predicting complex effects. Although embryotoxicity was observed following exposure to the extracts, dilution and transformation of produced water in the recipient are expected to rapidly reduce the concentrations of compounds in the effluents to levels below the thresholds of observed effects.

Vitellogenin as biomarker for estrogenicity in flounder Platichthys flesus in the field and exposed to 17α-ethinylestradiol via food and water in the laboratory

The ability of 17α-ethinylestradiol (EE2) to elevate vitellogenin levels were investigated in male flounder Platichthys flesus and vitellogenin concentrations in flounders from the Danish coastal environment were determined. Male flounders were exposed to 17α-ethinylestradiol (EE2) via food or water. Average vitellogenin concentrations in the control fish ranged between 25 and 100 ng mL(-)(1). Exposure to 5.1, 8.1 and 16.8 ng EE2 L(-)(1) in water and 500 and 5000 ng EE2 kg(-)(1) body weight (bw) every second day in the food increased the plasma vitellogenin concentration in a concentration and time dependent manner, whereas exposure to 2.7 ng EE2 L(-)(1) in water for 21 d and 5 and 50 ng EE2 kg(-)(1) bw for 12 days in the food did not. EE2 could be detected in liver and testes (but not in muscle) after exposure to 8.1 and 16.8 ng EE2 L(-)(1) in the water and 5000 ng EE2 kg(-)(1) bw in the food; the highest concentration was 6 ng g(-)(1) wet weight in liver. The majority of the male flounders collected from nine coastal Danish sites from 1999 to 2004 had vitellogenin concentrations below 100 ng mL(-)(1), and only at two sites moderate estrogenic inputs were indicated.

Effects-directed analysis (EDA) and toxicity identification evaluation (TIE): Complementary but different approaches for diagnosing causes of environmental toxicity

Currently, 2 approaches are available for performing environmental diagnostics on samples like municipal and industrial effluents, interstitial waters, and whole sediments to identify anthropogenic contaminants causing toxicological effects. One approach is toxicity identification evaluation (TIE), which was developed primarily in North America to determine active toxicants to whole-organism endpoints. The second approach is effects-directed analysis (EDA), which has origins in both Europe and North America. Unlike TIE, EDA uses primarily in vitro endpoints with an emphasis on organic contaminants as the cause of observed toxicity. The 2 approaches have fundamental differences that make them distinct techniques. In EDA, the sophisticated and elegant fractionation and chemical analyses performed to identify the causes of toxicity with a high degree of specificity often compromise contaminant bioavailability. In contrast, in TIE, toxicant bioavailability is maintained and is considered critical to accurately identifying the causes of environmental toxicity. However, maintaining contaminant bioavailability comes with the cost of limiting, at least until recently, the use of the types of sophisticated fractionation and elegant chemical analyses that have resulted in the high specificity of toxicant diagnosis performed in EDA. The present study provides an overview of each approach and highlights areas where the 2 approaches can complement one another and lead to the improvement of both.

Characterisation of genes transcriptionally upregulated in the liver of sand goby (Pomatoschistus minutus) by 17α-ethinyloestradiol: identification of distinct vitellogenin and zona radiata protein transcripts

The sand goby (Pomatoschistus minutus), is a marine and estuarine teleost that is used in environmental, reproductive and behavioural studies of oestrogenic endocrine disruption. The xeno-oestrogen, 17α-ethinyloestradiol (EE2), induces expression of egg proteins vitellogenin (VTG) and zona radiata protein (ZRP) in male fish and impairs reproduction. Multiple forms of VTG and ZRP genes are found in other teleost species, yet the characteristics of VTG and ZRP in the sand goby are unknown. In this investigation, Suppressive Subtractive Hybridization was used to isolate cDNA fragments from liver, identified as belonging to 11 distinct sand goby genes, suggesting that these genes are transcriptionally upregulated by EE2. Assembly of these fragments revealed three VTG genes which shared homology with VTG classes A, B and C in other fish and two ZRP genes sharing homology with ZRP classes Ba and Bb. RTqPCR of RNA from the sand goby liver was used to show that these VTGs and ZRPs were present in low levels in control males and high levels in mature females. Exposure of males to a concentration of 11 ngL(-1) EE2 caused a significant increase in all VTG and ZRP transcript levels. The identification of these egg protein transcripts and the development of validated assays for their quantification will facilitate future work with this useful model species.

Prioritisation of organic contaminants in a river basin using chemical analyses and bioassays

Region-specific contaminant prioritisation is an important prerequisite for sustainable and cost-effective monitoring due to the high number of different contaminants that may be present. Surface water and sediment samples from the Sava River, Croatia, were collected at four locations covering a 150-km-long river section characterised by well-defined pollution gradients. Analysis of contaminant profiles along the pollution gradients was performed by combining toxicity screening using a battery of small-scale or in vitro bioassays, which covered different modes of action, with detailed chemical characterisation based on gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). A large number of contaminants, belonging to different toxicant classes, were identified in both analysed matrices. Analyses of water samples showed that contaminants having polar character occurred in the highest concentrations, while in sediments, contributions from both non-polar and amphiphilic contaminants should be taken into account. Estimated contributions of individual contaminant classes to the overall toxicity indicated that, besides the classical pollutants, a number of emerging contaminants, including surfactants, pharmaceuticals, personal care products and plasticizers, should be taken into consideration in future monitoring activities. This work demonstrates the importance of the integrated chemical and bioanalytical approach for a systematic region-specific pollutant prioritisation. Finally, the results presented in this study confirm that hazard assessment in complex environmental matrices should be directed towards identification of key pollutants, rather than focusing on a priori selected contaminants alone.

Effect-directed analysis of endocrine-disrupting compounds in multi-contaminated sediment: identification of novel ligands of estrogen and pregnane X receptors

Effect-directed analysis (EDA)-based strategies have been increasingly used in order to identify the causative link between adverse (eco-)toxic effects and chemical contaminants. In this study, we report the development and use of an EDA approach to identify endocrine-disrupting chemicals (EDCs) in a multi-contaminated river sediment. The battery of in vitro reporter cell-based bioassays, measuring estrogenic, (anti)androgenic, dioxin-like, and pregnane X receptor (PXR)-like activities, revealed multi-contamination profiles. To isolate active compounds of a wide polarity range, we established a multi-step fractionation procedure combining: (1) a primary fractionation step using normal phase-based solid-phase extraction (SPE), validated with a mixture of 12 non-polar to polar standard EDCs; (2) a secondary fractionation using reversed-phase-based high-performance liquid chromatography (RP-HPLC) calibrated with 33 standard EDCs; and (3) a purification step using a recombinant estrogen receptor (ER) affinity column. In vitro SPE and HPLC profiles revealed that ER and PXR activities were mainly due to polar to mid-polar compounds, while dioxin-like and anti-androgenic activities were in the less polar fractions. The overall procedure allowed final isolation and identification of new environmental PXR (e.g., di-iso-octylphthalate) and ER (e.g., 2,4-di-tert-butylphenol and 2,6-di-tert-butyl-α-methoxy-p-cresol) ligands by using gas chromatography coupled with mass spectrometry with full-scan mode acquisition in mid-polar fractions. In vitro biological activity of these chemicals was further confirmed using commercial standards, with di-iso-octylphthalate identified for the first time as a potent hPXR environmental agonist.

Acetylcholine esterase inhibitors in effluents from oil production platforms in the North Sea

Inhibition of acetylcholine esterase (AChE) activity is a biomarker for the exposure to neurotoxic compounds such as organophosphates and is intimately associated with the toxicity of several pesticides. In the present study, the AChE inhibiting potential of organic extracts of production water (produced water) from oil and gas production platforms in the Norwegian sector of the North Sea was determined in an in vitro bioassay based on commercially available purified AChE from the electric organ of Electrophorus electricus (L.). The results from the studies show that produced water contains a combination of AChE inhibiting compounds and compounds stimulating AChE enzymatic activity. The AChE inhibition was predominantly caused by unidentified aromatic compounds in the oil/particulate fraction of produced water, whereas polar compounds in both the water soluble and oil/particulate fraction of produced water caused an apparent stimulation of AChE activity. Substrate saturation studies with fixed concentrations of produced water extracts confirmed that the inhibition occurred in a non-destructive and competitive manner. The concentrations of AChE inhibitors (7.9-453 ng paraoxon-equivalents L⁻¹, 2.2-178 μg dichlorvos-equivalents L⁻¹) were in many cases found to be several orders of magnitude higher than background levels. The findings demonstrate that produced water contains potentially neurotoxic compounds and suggest that further laboratory studies with fish or field studies in the vicinity of oil production facilities are highly warranted.

Modulation of estrogen synthesis through activation of protein kinase A in H295R cells by extracts of estuary sediments

Sediments from two estuaries within Liaodong Bay, China, were examined for the effects on steroidogenesis using H295R human adrenocortical carcinoma cells. Total extracts (TE) isolated from sediments by Soxhlet extraction were separated into three fractions (F1, F2, and F3) using Florisil columns. After exposing H295R cells to each TE and fractions, the expressions of six steroidogenic genes (cytochrome P450 cholesterol side-chain cleavage [CYP11A], 3β-hydroxysteroid dehydrogenase type 1 [3β-HSD1], 3β-hydroxysteroid dehydrogenase type 2 [3β-HSD2], cytochrome P450 17-hydroxylase/17-20 lyase [CYP17], cytochrome P450 aromatase [CYP19], 17β-hydroxysteroid dehydrogenase [17β-HSD]), and the production of six steroid hormones (progesterone [PGT], 17-hydroxyprogesterone [17-HPT], testosterone [TTR], androstenedione [ADD], estrone [E1], and 17β-estradiol [17β-E2]) were measured. The gene expressions of CYP11A, CYP17, 3β-HSD2, and CYP19, and hormone productions of PGT, 17-HPT, TTR, ADD, E1, and 17β-E2 were significantly increased after exposure to F3 extracts from the Daliao River. In particular, greater concentrations of E1 (up to 48-fold) and 17β-E2 (up to 20-fold), as well as up-regulation of CYP19 gene expression (up to tenfold), were caused by exposure to the F3 fraction from the Daliao River, but not from the Daling River. Insight into the mechanism of action was obtained by use of principal component analysis (PCA), the results of which were consistent with unidentified constituents in F3 from the Daliao River activating the protein kinase A (PKA) pathway. This hypothesis was confirmed by reversal of the effects caused by F3 through a co-exposure of a PKA inhibitor (H89) and F3 extract. The H89 down-regulated CYP19 messenger RNA (mRNA) expression with concomitant lesser production of E1 and 17β-E2 in the co-exposure group, indicating unidentified constituents that could modulate estrogen synthesis, primarily through a mechanism of PKA activation.

Identification of estrogen receptor agonists in sediments from Wenyu River, Beijing, China

Assignment of ecological impacts of contamination to specific classes of contaminants is a prerequisite for risk assessment and remediation. In this study, the combination of polarity-based fractionation, two-hybrid yeast bioassay, and chemical analysis were used to evaluate and identify estrogen receptor agonists (ER-agonists) in sediments from Wenyu River, Beijing, China. By bioassay, organic raw sediment extracts could induce significant estrogenicity and the bioassay-derived 17β-estradiol equivalents (EEQs) of raw extracts (EEQ(raw)s) ranged from 0.8 to 19.8 ng/g dry weight. By polarity-based fractionation, the raw extracts were separated into three fractions, i.e. non-polar, moderately polar, and polar fractions, which were subjected to bioassay and chemical analysis. The highest estrogenicity was observed in the polar fraction, which accounted for more than 78% of the total. The medium polar fraction contains PAHs and OCPs, and the estrogenic activities in this fraction contributed 3%-12% of the total in raw extract. An estrogenic activity of non-polarity fraction was negligible in compare to other two fractions. By chemical analysis and toxic equivalent calculation, major part of the estrogenicity in polar fraction could be attributed to six natural/synthetic estrogens (16%-63%), i.e. 17β-estradiol, estrone, estriol, 17α-ethynylestradiol, diethylstilbestrol, and β-estradiol-17-valerate, and to nonylphenols (26%-55%). The proposed approach has been successfully used for characterization of ER-agonists in this case study.

Assessment of toxicological profiles of the municipal wastewater effluents using chemical analyses and bioassays

The hazardous chemical contamination of untreated wastewater and secondary effluent from the wastewater treatment plant (WWTP) of the city of Zagreb, Croatia was comprehensively characterized using large-volume solid-phase extraction (SPE) and silica gel fractionation, followed by a detailed analysis of the resulting extracts by a combination of chemical and bioassay methods. Over 100 individual contaminants or closely related-contaminant groups were identified by high-resolution gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-QTOF). Ecotoxicity profiling of the investigated samples, including cytotoxicity, chronic toxicity and EROD activity; inhibition of the multixenobiotic resistance (MXR), genotoxicity and estrogenic potential, revealed the most significant contribution of toxic compounds to be present in polar fractions. Wastewater treatment using conventional activated sludge process reduced the initial toxicity of raw wastewater to various extents, ranging from 28% for algal toxicity to 73.2% for an estrogenic activity. The most efficient toxicity removal was observed for the polar compounds.

Screening complex effluents for estrogenic activity with the T47D-KBluc cell bioassay: assay optimization and comparison with in vivo responses in fish

Wastewater treatment plant (WWTP) effluents can contain estrogenic chemicals, which potentially disrupt fish reproduction and development. The current study focused on the use of an estrogen-responsive in vitro cell bioassay (T47D-KBluc), to quantify total estrogenicity of WWTP effluents. We tested a novel sample preparation method for the T47D-KBluc assay, using powdered media prepared with direct effluent. Results of the T47D-KBluc assay were compared with the induction of estrogen receptor-regulated gene transcription in male fathead minnows (Pimephales promelas) exposed to the same effluents. Effluent samples for the paired studies were collected over the course of three months. According to the T47D-KBluc assay, the effluent estrogenicity ranged from 1.13 to 2.00 ng 17β-estradiol (E2) equivalents/L. Corresponding in vivo studies exposing male fathead minnows to 0, 10, 50, and 100% effluent dilutions demonstrated that exposure to 100% effluent significantly increased hepatic vitellogenin (VTG) and estrogen receptor α subunit transcripts relative to controls. The induction was also significant in males exposed to 250 ng E2/L or 100 ng E2/L. The in vitro and in vivo results support the conclusion that the effluent contains significant estrogenic activity, but there was a discrepancy between in vitro- and in vivo-based E2 equivalent estimates. Our results suggest that the direct effluent preparation method for the T47D-KBluc assay is a reasonable approach to estimate the estrogenicity of wastewater effluent.

Improved removal of estrogenic and pharmaceutical compounds in sewage effluent by full scale granular activated carbon: impact on receiving river water

Sewage effluents are widely recognised as the main source of emerging contaminants, such as endocrine disrupting chemicals (EDCs) and pharmaceuticals in surface waters. A full-scale granular activated carbon (GAC) plant has been installed as an advanced technology for the removal of these contaminants, in a major sewage treatment works (STW) in South-West England as part of the UK National Demonstration Programme for EDCs. This study presented for the first time, an assessment of the impact of a recently commissioned, post-tertiary GAC plant in the removal of emerging contaminants in a working STW. Through regular sampling followed by solid-phase extraction and analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS), a significant reduction in the concentrations of steroidal estrogens was observed (>43-64%). In addition, significant reductions were observed for many of the pharmaceutical compounds such as mebeverine (84-99%), although the reduction was less dramatic for some of the more widely used pharmaceuticals analysed, including carbamazepine and propranolol (17-23%).

Effects-directed analysis of sediments from polluted marine sites in Norway

The environmental status of two polluted marine sites in Norway was investigated by a combination of target chemical analysis and effect-directed analysis (EDA). The two selected sites, the Grenland area and Oslo harbor, in addition to two reference sites, were classified according to the Norwegian environmental classification system based upon results of the target chemical analyses. The polluted sites were characterized by high levels of metals, polycyclic aromatic hydrocarbons (PAH), and polychlorinated biphenyls (PCB). High levels of organotin compounds were also detected in Oslo harbor. The aryl hydrocarbon receptor (AhR) agonist activity in extracts of sediments from marine sites close to Oslo, Oslo harbor, and Grenland were investigated using the CALUX (chemical-activated luciferase expression) assay, which showed elevated levels of activity. As expected from the history of dioxin release into the Grenland area, the results were highest in this area. The presence of estrogen receptor (ER) and androgen receptor (AR) antagonists was also detected in the sediment extracts. Following fractionation of the sediment extracts, EDA was used to tentatively identify the AhR agonists. The compounds responsible for AhR agonist activity in samples from Oslo harbor were isolated in fraction 13, and to a lesser extent in fractions 9-11. In Grenland, the main activity was found in the more polar fractions, namely fractions 14-18. The AhR agonists identified in Oslo harbor were mainly PAH, while in the Grenland area the compounds identified were mainly nitrogen/oxygen-containing polyaromatic compounds (N/O-PAC).

Produced water extracts from North Sea oil production platforms result in cellular oxidative stress in a rainbow trout in vitro bioassay

Produced water (PW) discharged from offshore oil industry contains chemicals known to contribute to different mechanisms of toxicity. The present study aimed to investigate oxidative stress and cytotoxicity in rainbow trout primary hepatocytes exposed to the water soluble and particulate organic fraction of PW from 10 different North Sea oil production platforms. The PW fractions caused a concentration-dependent increase in reactive oxygen species (ROS) after 1h exposure, as well as changes in levels of total glutathione (tGSH) and cytotoxicity after 96 h. Interestingly, the water soluble organic compounds of PW were major contributors to oxidative stress and cytotoxicity, and effects was not correlated to the content of total oil in PW. Bioassay effects were only observed at high PW concentrations (3-fold concentrated), indicating that bioaccumulation needs to occur to cause similar short term toxic effects in wild fish.

HPLC/APCI-FTICR-MS as a tool for identification of partial polar mutagenic compounds in effect-directed analysis

Identification of unknown compounds remains one of the biggest challenges for the assignment of adverse effects of sediment contamination and other complex environmental mixtures to responsible toxicants by effect-directed analysis (EDA). The identification depends on information gained from biotesting, chromatographic separation, and mass spectrometric detection. Thus, a methodology is provided for non-target identification of partial polar mutagenic polyaromatic compounds in sediment extracts by using polymeric reversed-phase HPLC column, high-resolution mass spectrometry and PubChem database. After visualization and processing the chromatogram constituents by using deconvolution software, the unambiguous elemental compositions generated were used as input in PubChem database to find a possible identity for the suspected species. The retrieved structures from the database search were refined by characterized chromatographic and mass spectrometric classifiers based on 55 model compounds comprising eight different classes representing mutagenic substructures. The applicability of the method was demonstrated by positive and tentative identification of constituents of mutagenic sediment fractions similar to selected model compounds.

Effect-directed identification of naphthenic acids as important in vitro xeno-estrogens and anti-androgens in North sea offshore produced water discharges

Produced water from offshore oil production platforms represents the largest direct discharge of effluent into the offshore environment. Produced water effluents contain a complex mixture of substances which are known to bind to the estrogen receptor (ER) and antagonize the androgen receptor (AR). Short-chain petrogenic alkylphenols have been identified as responsible for around 35% of the ER agonist activity measured in vitro while the compounds responsible for antagonizing the androgen receptor are unknown. For the first time we report that petrogenic naphthenic acids are weak ER agonists that account for much of the 65% of the "unknown" ER agonist potency in North Sea produced waters while also disrupting the binding of AR agonists to the AR ligand receptor. We also report other known petrogenic components such as polycyclic aromatic hydrocarbons (PAHs) and alkylphenols as environmental AR antagonists. Our investigation shows that these petrogenic components are responsible for the majority of the ER and AR receptor mediated activity in produced waters. This hypothesis is supported by data from an effects-directed analysis of produced water using normal-phase high-performance liquid chromatography (HPLC) fractionation in combination with the yeast estrogen and androgen assays as well as androgen receptor binding assays of commercially available mixtures of naphthenic acids.

Biological removal of 17alpha-ethinylestradiol by a nitrifier enrichment culture in a membrane bioreactor

Increasing concern about the fate of 17alpha-ethinylestradiol (EE2) in the environment stimulates the search for alternative methods for wastewater treatment plant (WWTP) effluent polishing. The aim of this study was to establish an innovative and effective biological removal technique for EE2 by means of a nitrifier enrichment culture (NEC) applied in a membrane bioreactor (MBR). In batch incubation tests, the microbial consortium was able to remove EE2 from both a synthetic minimal medium and WWTP effluent. A maximum EE2 removal rate of 9.0 microg EE2 g(-1)biomass-VSS h(-1) was achieved (>94% removal efficiency). Incubation of the heterotrophic bacteria isolated from the NEC did not result in a significant EE2 removal, indicating the importance of nitrification as driving force in the mechanism. Application of the NEC in a MBR to treat a synthetic influent with an EE2 concentration of 83 ng EE2 L(-1) resulted in a removal efficiency of 99% (loading rates up to 208 ng EE2 L(-1)d(-1); membrane flux rate: 6.9 L m(-2) h(-1)). Simultaneously, complete nitrification was achieved at an optimal ammonium influent concentration of 1.0 mg NH(4)(+)-N L(-1). This minimal NH(4)(+)-N input is very advantageous for effluent polishing since the concomitant effluent nitrate concentrations will be low as well and it offers opportunities for the nitrifying MBR as a promising add-on technology for WWTP effluent polishing.

Manganese-oxidizing bacteria mediate the degradation of 17α-ethinylestradiol

Manganese (II) and manganese‐oxidizing bacteria were used as an efficient biological system for the degradation of the xenoestrogen 17α‐ethinylestradiol (EE2) at trace concentrations. Mn²⁺‐derived higher oxidation states of Mn (Mn³⁺, Mn⁴⁺) by Mn²⁺‐oxidizing bacteria mediate the oxidative cleavage of the polycyclic target compound EE2. The presence of manganese (II) was found to be essential for the degradation of EE2 by Leptothrix discophora, Pseudomonas putida MB1, P. putida MB6 and P. putida MB29. Mn²⁺‐dependent degradation of EE2 was found to be a slow process, which requires multi‐fold excess of Mn²⁺ and occurs in the late stationary phase of growth, implying a chemical process taking place. EE2‐derived degradation products were shown to no longer exhibit undesirable estrogenic activity.

Chronic toxicity of the Sava River (SE Europe) sediments and river water to the algae Pseudokirchneriella subcapitata

The Sava River, the largest and most commercially valuable water body in the riparian countries, receives inputs of organic and inorganic compounds from a variety of domestic and industrial activities that may affect the health of human beings and wildlife. In this work, the chronic toxicity of sediment, sediment porewater and surface water from the Sava River and connecting tributaries to the freshwater algae Pseudokirchneriella subcapitata was assessed to characterise the potential impact on aquatic organisms. Samples of different environmental matrices were either tested directly (porewater) or subjected to pre-concentration (sediments and surface water) prior to testing in a 72 h growth inhibition assay using P. subcapitata. The results show that a combination of pre-concentration and bioassay testing was able to characterise the toxic potential and to identify several compartment-specific "hot spots" along the Sava River. Based on the resulting data, a crude risk assessment identified that some of the locations may represent a risk to algae. Additional testing using multiple species and exposure phases is required to conduct a thorough risk assessment, however.

Assessing and managing risks arising from exposure to endocrine-active chemicals

Managing risks to human health and the environment produced by endocrine-active chemicals (EAC) is dependent on sound principles of risk assessment and risk management, which need to be adapted to address the uncertainties in the state of the science of EAC. Quantifying EAC hazard identification, mechanisms of action, and dose-response curves is complicated by a range of chemical structure/toxicology classes, receptors and receptor subtypes, and nonlinear dose-response curves with low-dose effects. Advances in risk science including toxicogenomics and quantitative structure-activity relationships (QSAR) along with a return to the biological process of hormesis are proposed to complement existing risk assessment strategies, including that of the Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC 1998). EAC represents a policy issue that has captured the public's fears and concerns about environmental health. This overview describes the process of EAC risk assessment and risk management in the context of traditional risk management frameworks, with emphasis on the National Research Council Framework (1983), taking into consideration the strategies for EAC management in Canada, the United States, and the European Union.

Contributors to estrogenic activity in wastewater from a large wastewater treatment plant in Beijing, China

Wastewater at various stages of treatment was sampled from a large wastewater treatment plant (WWTP) in Beijing, China. A fractionation method was conducted to identify the dominant contributors to estrogenic activity of those samples using silica gel column chromatography combined with a recombinant yeast bioassay for detecting estrogenic activity and gas chromatography-mass spectrometry (GC/MS) for quantifying estrogenic substances. Total estradiol equivalents (EEQ) found in the influent and effluent of the WWTP were 15.7±2.0 and 10.4±0.4ng/L, indicating the low removal efficiency of the WWTP. The endocrine disrupting chemicals (EDCs) most frequently detected in the wastewater by GC/MS included phthalate esters, PAHs and phenolic compounds, while the natural and synthetic estrogens such as estradiol (E2), estrone (E1), and ethinylestradiol (EE2) were not detected. The concentrations of nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA) were 13.4, 1.4 and 89.0μg/L in the influent and 0.41, 0.11 and 0.32μg/L in the effluent, respectively. Based on the concentrations and estradiol equivalency factors (EEF) of NP, OP and BPA, 60% of the total estrogenic activity in GBD-WWTP influent could be explained by the calculated EEQ, showing that BPA, OP and NP were mainly responsible for estrogenic activity in the influent. However, their contributions to estrogenic activity in the effluent were only 3%, indicating that some unknown estrogenic components were still present in the wastewater.

Modulation of aryl hydrocarbon receptor transactivation by carbaryl, a nonconventional ligand

Carbaryl (1-naphthyl-N-methylcarbamate), a widely used carbamate insecticide, induces cytochrome P450 1A gene expression in mammalian cells. This activity is usually mediated by the interaction of the compound with the aryl hydrocarbon receptor. However, it has been proposed that this mechanism does not apply to carbaryl because its structure differs from that of typical aryl hydrocarbon receptor ligands. We show here that carbaryl promotes activation of target genes in a yeast-based bioassay expressing both aryl hydrocarbon receptor and aryl hydrocarbon receptor nuclear translocator. By contrast, carbaryl acted as a competitive inhibitor, rather than as an agonist, in a simplified yeast system, in which aryl hydrocarbon receptor nuclear translocator function is bypassed by fusing aryl hydrocarbon receptor to a heterologous DNA binding domain. This dual action of carbaryl, agonist and partial antagonist, was also observed by comparing carbaryl response in two vertebrate cell lines. A yeast two-hybrid assay showed that the mammalian coactivator cAMP response element-binding protein readily interacts with aryl hydrocarbon receptor bound to its canonical ligand beta-naphthoflavone, but not with the carbaryl-aryl hydrocarbon receptor complex. We propose that carbaryl interacts with aryl hydrocarbon receptor, but that its peculiar structure imposes a substandard configuration on the aryl hydrocarbon receptor ligand-binding domain that prevents interaction with key coactivators and activates transcription without the need for aryl hydrocarbon receptor nuclear translocator. This effect may be relevant in explaining its physiological effects in exposed animals, and may help to predict its effects, and that of similar compounds, in humans. Our data also identify the aryl hydrocarbon receptor/cAMP response element-binding protein interaction as a molecular target for the identification and development of new aryl hydrocarbon receptor antagonists.

Bioindicators and reproductive effects of prolonged 17beta-oestradiol exposure in a marine fish, the sand goby (Pomatoschistus minutus)

The effects of 17beta-oestradiol (E2) on mortality, growth rates, sexual maturation, hepatic vitellogenin (VTG) mRNA expression and reproductive success were investigated during an 8-month, water-borne exposure of a marine fish, the sand goby (Pomatoschistus minutus). Indicators of oestrogenic exposure were investigated as predictors of population-level reproductive success. E2 exposure concentrations were <5 (below limit of detection), 16+/-3, 97+/-20 and 669+/-151 ng l(-1) (bootstrap means and standard errors). The carrier solvent (<20 microl l(-1) propan-2-ol) significantly reduced the rate of egg production compared to untreated fish, but did not significantly affect male VTG mRNA expression, brood size, or the other studied parameters. Fish exposed to 16 ng l(-1) E2 showed few adverse effects compared with solvent only-exposed fish. Exposure to 97 ng l(-1) E2 significantly inhibited male sexual maturation, induced male VTG mRNA expression and delayed spawning. The 97 ng l(-1) E2 exposed population also produced fertile eggs at a significantly slower rate than solvent controls; however, brood size, fertility and overall reproductive success were not significantly affected. Exposure to 669 ng l(-1) E2 significantly increased mortality, adversely affected haematological parameters and caused an almost total lack of reproductive activity, with both sexes failing to mature. Reproductive failure following exposure to 669 ng l(-1) E2 was evident in both sexes when crossed with untreated animals. This work indicates that marine fish are similarly as sensitive to oestrogenic exposure as freshwater fish, that exposure biomarkers such as VTG are more sensitive to exposure than are reproductive effects, and that the use of carrier solvents in long-term reproductive studies should be avoided.

Estrogen receptor (ER) agonists and androgen receptor (AR) antagonists in effluents from Norwegian North Sea oil production platforms

The in vitro estrogen receptor (ER) agonist and androgen receptor (AR) antagonist potencies of offshore produced water effluents collected from the Norwegian Sector were determined using recombinant yeast estrogen and androgen screens. Solid phase extraction (SPE) concentrates of the effluents showed E2 agonist activities similar to those previously reported for the United Kingdom (UK) Continental Shelf (<0.1-4 ng E2 L(-1)). No activity was detected in the filtered oil droplets suggesting that produced water ER activity is primarily associated with the dissolved phase. Targeted analysis for methyl- to nonyl-substituted alkylphenol isomers show the occurrence of known ER agonists in the analysed samples. For the first time, AR antagonists were detected in both the dissolved and oil associated phase at concentrations of between 20 and 8000 microg of flutamide equivalents L(-1). The identity of the AR antagonists is unknown, however this represents a significant input into the marine environment of unknown compounds that exert a known biological effect. It is recommended that further analysis using techniques such as bioassay-directed analysis is performed to identify the compounds/groups of compounds that are responsible in order to improve the assessment of the risk posed by produced water discharges to the marine environment.