In vitro biomonitoring in polar extracts of solid phase matrices reveals the presence of unknown compounds with estrogenic activity

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

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

High estradiol exposure disrupts the reproductive cycle of the clam Ruditapes decussatus in a sex-specific way

Bivalve species may be susceptible to environmental estrogenic compounds including estradiol (E₂). However, they are able to biotransform the hormone quite readily and inactivate its estrogenic action. To study the long-term effects of elevated free E₂ tissue levels, we transiently exceeded the biotransformation capacity of the clam Ruditapes decussatus by exposing them with high E₂ concentrations (400 ng/L) and subsequently study the consequences on gametogenesis during the following reproductive cycle. Exposure to 400 ngE₂/L led to a significant increase in tissue free E₂ levels, which reached 10-50 ng E₂Eq/gww. No deleterious effect on gonado-somatic index (GSI), condition index (CI), or ability to respond to the stress on stress test could be detected after a month of exposure, suggesting the absence of negative effects on the clam's health. However, a marked increase in gametogenesis could be observed in both sexes during the exposure. Subsequent transplantation of the clams in the field allowed the normal development of the male clams and maturation of the gonads without any detrimental effect observed after 4 months. In contrast, in early July, all female clams formerly exposed to E₂ showed lower health status, and only ovaries with atretic oocytes while all control and indigenous females were normal and mature. These results show a sex-specific effect of high E₂ exposure and suggest either a direct or indirect role for E₂ in R. decussatus' reproduction.

Effect-directed analysis supporting monitoring of aquatic environments--An in-depth overview

Aquatic environments are often contaminated with complex mixtures of chemicals that may pose a risk to ecosystems and human health. This contamination cannot be addressed with target analysis alone but tools are required to reduce this complexity and identify those chemicals that might cause adverse effects. Effect-directed analysis (EDA) is designed to meet this challenge and faces increasing interest in water and sediment quality monitoring. Thus, the present paper summarizes current experience with the EDA approach and the tools required, and provides practical advice on their application. The paper highlights the need for proper problem formulation and gives general advice for study design. As the EDA approach is directed by toxicity, basic principles for the selection of bioassays are given as well as a comprehensive compilation of appropriate assays, including their strengths and weaknesses. A specific focus is given to strategies for sampling, extraction and bioassay dosing since they strongly impact prioritization of toxicants in EDA. Reduction of sample complexity mainly relies on fractionation procedures, which are discussed in this paper, including quality assurance and quality control. Automated combinations of fractionation, biotesting and chemical analysis using so-called hyphenated tools can enhance the throughput and might reduce the risk of artifacts in laboratory work. The key to determining the chemical structures causing effects is analytical toxicant identification. The latest approaches, tools, software and databases for target-, suspect and non-target screening as well as unknown identification are discussed together with analytical and toxicological confirmation approaches. A better understanding of optimal use and combination of EDA tools will help to design efficient and successful toxicant identification studies in the context of quality monitoring in multiply stressed environments.

The influence of extreme river discharge conditions on the quality of suspended particulate matter in Rivers Meuse and Rhine (The Netherlands)

As a consequence of climate change, increased precipitation in winter and longer periods of decreased precipitation in summer are expected to cause more frequent episodes of very high or very low river discharge in the Netherlands. To study the impact of such extreme river discharge conditions on water quality, toxicity profiles and pollutant profiles were determined of suspended particulate matter (SPM) collected from Rivers Meuse and Rhine. Archived (1993-2003) and fresh (2009-2011) SPM samples were selected from the Dutch annual monitoring program of the national water bodies (MWTL), representing episodes with river discharge conditions ranging from very low to regular to very high. SPM extracts were tested in a battery of in vitro bioassays for their potency to interact with the androgen receptor (AR), the estrogen receptor (ER), the arylhydrocarbon receptor (AhR), and the thyroid hormone transporter protein transthyretin (TTR). SPM extracts were further tested for their mutagenic potency (Ames assay) and their potency to inhibit bacterial respiration (Vibrio fischeri bioluminescence assay). Target-analyzed pollutant concentrations of the SPM samples and additional sample information were retrieved from a public database of MWTL results. In vitro toxicity profiles and pollutant profiles were analyzed in relation to discharge conditions and in relation to each other using correlation analysis and multivariate statistics. Compared to regular discharge conditions, composition of SPM during very high River Meuse and Rhine discharges shifted to more coarse, sandy, organic carbon (OC) poor particles. On the contrary, very low discharge led to a shift to more fine, OC rich material, probably dominated by algae. This shift was most evident in River Meuse, which is characterized by almost stagnant water conditions during episodes of drought. During such episodes, SPM extracts from River Meuse demonstrated increased potencies to inhibit bacterial respiration and to compete with thyroid hormone to bind to TTR, possibly due to the presence of fycotoxins. Meanwhile concentrations of polychlorobiphenyls (PCBs) in SPM were also increased. Very high River Meuse discharges on the other hand corresponded to increased androgenic and AhR agoniztic responses, which coincided with increased PAH levels and PAH-related in vivo risk estimates (i.e. multi-substance potentially affected fraction of species; msPAF). In River Rhine, very high discharges also corresponded to increasing androgenic potencies in SPM. Concentrations and corresponding msPAF values of PAHs (and metals), however, decreased with very high discharges in River Rhine in contrast to River Meuse. Mutagenicity was observed for SPM extracts from River Rhine collected during all discharge conditions, except during regular discharge. Aggregated toxicity index values, which were useful to identify toxicity profiles deviating from the generally observed pattern, did not correlate with river discharges, probably due to opposite effects of discharge conditions on different bioassay responses. In conclusion, SPM quality and related in vivo risk estimates changed during very low or very high discharge conditions but the changes were specific for the different toxic endpoints and pollutants in the different rivers. Moreover, bioassay responses to a series of consecutively collected samples from River Rhine during the Christmas flood of 1993 indicated that SPM quality is variable within a single episode of extreme discharge.

Adaptive stress response pathways induced by environmental mixtures of bioaccumulative chemicals in dugongs

To address the poorly understood mixture effects of chemicals in the marine mammal dugong, we coupled equilibrium-based passive sampling in blubber to a range of in vitro bioassays for screening mixtures of bioaccumulative chemicals. The modes of action included early effect indicators along important toxicity pathways, such as induction of xenobiotic metabolism, and some integrative indicators downstream of the molecular initiating event, such as adaptive stress responses. Activation of aryl hydrocarbon receptor (AhR) and Nrf2-mediated oxidative stress response were found to be the most prominent effects, while the p53-mediated DNA damage response and NF-κB-mediated response to inflammation were not significantly affected. Although polychlorinated dibenzo-p-dioxins (PCDDs) quantified in the samples accounted for the majority of AhR-mediated activity, PCDDs explained less than 5% of the total oxidative stress response, despite their known ability to activate this pathway. Altered oxidative stress response was observed with both individual chemicals and blubber extracts subject to metabolic activation by rat liver S9 fraction. Metabolic activation resulted in both enhanced and reduced toxicity, suggesting the relevance and utility of incorporating metabolic enzymes into in vitro bioassays. Our approach provides a first insight into the burden of toxicologically relevant bioaccumulative chemical mixtures in dugongs and can be applied to lipid tissue of other wildlife species.

Screening of multiple hormonal activities in water and sediment from the river Nile, Egypt, using in vitro bioassay and gonadal histology

In Egypt, until yet no records are available regarding possible multiple hormonal activities in the aquatic systems and especially in the river Nile. In this paper, in vitro yeast estrogen screen (YES) and yeast androgen screen (YAS) were used to assess (for the first time) the multiple hormonal activities in surface waters and sediments of the river Nile. This study aimed to determine whether river Nile water can cause changes in gonadal histology of Nile tilapia (Oreochromis niloticus niloticus). All water samples exhibited extremely low levels of estrogenicity. Estrogenicity was nearly not detected in any of the sediment samples. Unlike the estrogenicity, significant androgenic activities were recorded in the water and sediment samples along the course of the river Nile. The present study reports for the first time quantification anti-estrogenic and anti-androgenic activities with high levels in both water and sediment of the river Nile. The greatest anti-estrogenic and anti-androgenic activities were observed in samples from downstream river Nile. These results indicated that the anti-estrogenic and anti-androgenic activities along the Nile course were great and the pollution of the sites at downstream was more serious than the upstream sites due to industrial and anthropogenic activities at these sites. Good correlations were observed among some hormonal activities, suggesting coexistence of these contaminants in the environmental matrices. There were no signs of sexual disruption in any of the gonads analyzed from either male or female Nile tilapia, demonstrating that no hormonal activity present along the Nile course was sufficient to induce adverse effects on reproductive development. Further investigation is necessary to identify the compounds responsible for the hormonal activities in the river Nile and to examine effects of very low levels of hormonally active compounds on gonadal histology, as well as in the development of more sensitive biomarkers.

Metabolic activation of nonpolar sediment extracts results in enhanced thyroid hormone disrupting potency

Traditional sediment risk assessment predominantly considers the hazard derived from legacy contaminants that are present in nonpolar sediment extracts, such as polychlorinated biphenyls (PCBs), dioxins, furans (PCDD/Fs), and polyaromatic hydrocarbons (PAHs). Although in vivo experiments with these compounds have shown to be thyroid hormone disrupting (THD), in vitro their THD potency is not observed in nonpolar sediment extracts. This is hypothesized to be due to the absence of in vitro biotransformation which will result in bioactivation of the lipophilic compounds into THD hydroxyl metabolites. This study reveals that indeed metabolically activated nonpolar contaminants in sediments can competitively bind to thyroid hormone transport proteins. Sediment fractions were incubated with S9 rat microsomes, and the metabolites were extracted with a newly developed method that excludes most of the lipids to avoid interference in the applied nonradioactive 96-well plate TTR competitive binding assay. Metabolic activation increased the TTR binding potency of nonpolar fractions of POP-polluted sediments up to 100 times, resulting in potencies up to 240 nmol T4 equivalents/g sediment equivalent (nmol T4-Eq/g SEQ). This demonstrates that a more realistic in vitro sediment THD risk characterization should also include testing of both polar and medium polar sediment extracts for THD, as well as bioactivated nonpolar sediment fractions to prevent underestimation of its toxic potency.

Similarities in the endocrine-disrupting potencies of indoor dust and flame retardants by using human osteosarcoma (U2OS) cell-based reporter gene assays

Indoor dust is a sink for many kinds of pollutants, including flame retardants (FRs), plasticizers, and their contaminants and degradation products. These pollutants can be migrated to indoor dust from household items such as televisions and computers. To reveal high-priority end points of and contaminant candidates in indoor dust, using CALUX reporter gene assays based on human osteosarcoma (U2OS) cell lines, we evaluated and characterized the endocrine-disrupting potencies of crude extracts of indoor dust collected from Japan (n = 8), the United States (n = 21), Vietnam (n = 10), the Philippines (n = 17), and Indonesia (n = 10) and for 23 selected FRs. The CALUX reporter gene assays used were specific for compounds interacting with the human androgen receptor (AR), estrogen receptor α (ERα), progesterone receptor (PR), glucocorticoid receptor (GR), and peroxisome proliferator-activated receptor γ2 (PPARγ2). Indoor dust extracts were agonistic to ERα, GR, and PPARγ2 and antagonistic against AR, PR, GR, and PPARγ2. In comparison, a majority of FRs was agonistic to ERα and PPARγ2 only, and some FRs demonstrated receptor-specific antagonism against all tested nuclear receptors. Hierarchical clustering clearly indicated that agonism of ERα and antagonism of AR and PR were common, frequently detected end points for indoor dust and tested FRs. Given our previous results regarding the concentrations of FRs in indoor dust and in light of our current results, candidate contributors to these effects include not only internationally controlled brominated FRs but also alternatives such as some phosphorus-containing FRs. In the context of indoor pollution, high-frequency effects of FRs such as agonism of ERα and antagonism of AR and PR are candidate high-priority end points for further investigation.

Assessing estrogenic chemicals in anchovy and mussel samples from Karachi, Pakistan with the yeast estrogen screen bioassay

Endocrine disrupting chemicals (EDCs) are introduced into the aquatic environment through industrial and municipal effluents along with urban and agricultural runoffs. Exposure of aquatic organisms to EDCs may lead to hormonal disruption and adverse health effects. The goals of our study were: to collect anchovy and mussel samples from the coastal region of Karachi, to use the yeast estrogen screen (YES) bioassay in estimating xeno-estrogen content in these samples, and to investigate if the bioassay could be used to quantify known amounts of 17β-estradiol (E2) injected into cod and salmon fillets. Results of the studies showed that mussel estrogenic activity in Karachi decreased in the order of Buleji point 1 (8.91 ± 4.77, mean ± SD) > Paradise point 1 (1.72 ± 0.81) > Paradise point 2 (0.61 ± 0.84) ng E2 equivalents/g wet wt (p < 0.05). By comparison, anchovy estrogenic activity at Korangi/Phitti Creek was much higher than at Manora. Together, these results confirmed previous reports that both Buleji point 1 and Korangi/Phitti Creek were the most contaminated areas of Karachi. The YES bioassay was only a semi-quantitative method in determining the contents of xeno-estrogens in aquatic organisms; it consistently overestimated the amounts of E2 injected into cod and salmon fillets due to additive and/or non-additive interactions between E2 and endogenous estrogens. Nevertheless, the YES bioassay was able to identify the contaminated sites in the coastal region of Karachi.

In vitro biomonitoring of contamination by estrogenic compounds in coastal environments: comments on the use of M. galloprovincialis

The use of mussel extracts in in vitro bioassays which express the estrogen receptor could provide valuable information on the bioavailability of endocrine disruptors in coastal environments. The aim of this study was to assess the temporal variability of the estrogenic responses in bioassays in Mytilus galloprovincialis. A 6-month in situ experiment was conducted in order to follow the estrogenic activity on MELN cell line during the reproduction stages of mussels. Estradiol equivalents (EEQ) determined in mussels using the MELN cell lines ranged from 0.79 to 3.72 ng/g dry weight (d.w.) in males, from 0.42 to 2.33 ng/g d.w. in females and from 3.41 to 4.2 d.w. in undifferentiated bivalves. We observed an increase in EEQ values during the spawning stage for males, not for female. The maximal EEQ values were observed at the indifferent stage. We discuss these results in regards to the actual knowledge on mussels' reproductive cycle and to the possible impact of xeno-estrogens. Variations of E2 levels in mussels must be taken into account for further studies on xeno-estrogens monitoring using hER reporter cell-lines bioassays.

Estrogen receptor mediated activity in bankside groundwater, with flood suspended particulate matter and floodplain soil - an approach combining tracer substance, bioassay and target analysis

Bankside groundwater is widely used as drinking water resource and, therefore, contamination has to be avoided. In the European Union groundwater protection is explicit subject to Water Framework Directive. While groundwater pollution may originate from different sources, this study investigated on impacts via flood events. Groundwater was sampled with increasing distance to the river Rhine near Karlsruhe, Germany. Samples were HPLC-MS-MS analyzed for the river contaminant carbamazepine to indicate river water infiltration, giving permanent presence in 250 m distance to the river (14-47 μg L⁻¹). Following a flood event, concentrations of about 16-20 μg L⁻¹ could also be detected in a distance of 750 m to the river. Furthermore, estrogenic activity as determined with the Yeast Estrogen Screen assay was determined to increase up to a 17β-ethinylestradiol equivalent concentration (E-EQ)=2.9 ng L⁻¹ near the river, while activity was initially measured following the flood with up to E-EQ=2.6 ng L⁻¹ in 750 m distance. Detections were delayed with increasing distance to the river indicating river water expansion into the aquifer. Flood suspended matter and floodplain soil were fractionated and analyzed for estrogenic activity in parallel giving up to 1.4 ng g⁻¹ and up to 0.7 ng g⁻¹, respectively. Target analysis focusing on known estrogenic active substances only explained < 1% of measured activities. Nevertheless, river water infiltration was shown deep into bankside groundwater, thus, impacting groundwater quality. Therefore, flood events have to be in the focus when aiming for groundwater and drinking water protection as well as for implementation of Water Framework Directive.

Estrogen pollution in a highly productive ecosystem off central-south Chile

While the presence of steroid estrogens in the environment has become a major environmental and health concern, their occurrence in coastal sediments remains poorly characterized. In this study, we measured the levels of three natural (estrone, 17β-estradiol, estriol) and one synthetic (17α-ethinylestradiol) estrogens in 54 coastal sediment samples collected from nine locations off central-southern Chile. Steroid estrogens were found in every sample. Remarkably high levels of 17α-ethinylestradiol were detected, reaching up to 48.14 ng/g dry weight. As a result, the global estrogenic loads were estimated to be high at all sites. Interestingly, they were found to correlate with the size of human populations served by sewage plants. Our study indicates that 17α-ethinylestradiol may accumulate in coastal sediments. The possible impact of this highly potent synthetic estrogen on the biota of the marine ecosystem off central-south Chile and on human health remains an open question.

The endocrine disrupting potential of sediments from the Upper Danube River (Germany) as revealed by in vitro bioassays and chemical analysis

INTRODUCTION

The present study was part of a comprehensive weight-of-evidence approach with the goal of identifying potential causes for the declines in fish populations, which have been observed during the past decades in the Upper Danube River.

METHODS

The specific goal was the investigation of the endocrine disrupting potential of sediment extracts from different sites along the Danube River. Parallel to the identification and quantification of target estrogens, two in vitro bioassays were employed to assess the estrogenic potential (yeast estrogen screen, YES) of the sediment samples and to evaluate their effects on the production of testosterone (T) and E2 (H295R Steroidogenesis Assay). Using a potency balance approach, the contribution of the measured compounds (Chem-EEQs) to the total endocrine activity measured by the YES (YES-EEQs) was calculated.

RESULTS AND DISCUSSION

Of the nine sediment extracts tested five extracts exhibited significant estrogenic activities in the YES, which suggested the presence of ER agonists in these samples. The xenoestrogens nonylphenol (NP) and bisphenol A (BPA) and the natural estrogen estrone (E1) were detected while concentrations of 17β-estradiol (E2) and ethinylestradiol (EE2) were less than their respective limits of quantification in all sediment extracts. A comparison of the measured YES-EEQs and the calculated Chem-EEQs revealed that as much as 6% of estrogenic activity in extracts of most sediments could be explained by two xeno- and one natural estrogen. Exposure of H295R cells to sediment extracts from four different locations in the Danube River resulted in significantly increased concentrations of E2, but only slight inhibition of T synthesis. Furthermore, application of the H295R Steroidogenesis Assay provided evidence for endocrine disrupting potencies in sediment samples from the Upper Danube River, some of which were not detectable with the YES. In conclusion, differential endocrine activities were associated with several sediments from the Upper Danube River. Further investigations will have to show whether the observed activities are of biological relevance with regard to declines in fish populations in the Upper Danube River.

Testing endocrine disruption in biota samples: a method to remove interfering lipids and natural hormones

A cleanup method was developed to remove coextracted lipids and natural hormones from biota samples in order to test the endocrine-disrupting (ED) capacity of their extracts in in vitro bioassays. Unspiked and spiked fish tissues were cleaned with a combination of dialysis, gel permeation chromatography (GPC), and normal-phase liquid chromatography (NP-HPLC). The spiking mixture consisted of a broad range of environmental pollutants (endocrine disruptors and genotoxic compounds). Chemical recoveries of each test compound, and thyroid-hormone-like and (anti)androgenic activities of the cleaned extracts were investigated. Despite the chemical and toxicological complexity of the spiking mixture and the sequential sample treatment, chemical analysis revealed acceptable recoveries on average: 89 ± 8% after each cleanup step separately and 75 ± 3% after the whole extraction and cleanup procedure in the extracts. In addition, recovered activities in the bioassays were in good agreement with the spiking levels. The developed cleanup method proved to be capable of lipid and natural hormone removal from fish extracts, enabling the measurement of selected endocrine-hormone-like activities in T(4)*-TTR and AR-CALUX bioassays. The method can be used as a sample preparation method of biota samples for toxicity profiling and effect-directed analysis (EDA).

Application of bioassays in toxicological hazard, risk and impact assessments of dredged sediments

Given the potential environmental consequences of dumped dredged harbour sediments it is vital to establish the potential risks from exposure before disposal at sea. Currently, European legislation for disposal of contaminated sediments at sea is based on chemical analysis of a limited number of well-known contaminants for which maximum acceptable concentrations, action levels (ALs), have been set. The present paper addresses the issue of the applicability of in vitro and in vivo bioassays for hazard, risk and local impact assessment of dredged polluted sediments to be disposed of at sea. It discusses how and to what extent selected bioassays can fill in the gaps left open by chemical analysis and the way in which the bioassays may contribute to the present licensing system for disposal. Three different purposes for application were distinguished: the most basic application (A) is a rapid determination of the hazard (potential toxicity) of dredged sediments which is then compared to ALs in a licensing system. As with chemical analysis on whole sediment extracts, the bioavailability of the chemicals is not taken into account. As in vitro assays with sediment extracts are not sensitive to matrix effects, a selection of specific in vitro bioassays can be suitable fast and standardized additions for the licensing system. When the outcome of (A) does not convincingly demonstrate whether the sediment is clean enough or too polluted, further bioanalysis can help the decision making process (B). More aspects of the mostly unknown complex chemical mixtures are taken into account, including the bioavailability and chronic toxicity focusing on ecologically relevant endpoints. The ecotoxicological pressure imposed by the dredged sediments can be quantified as the potentially affected fraction (PAF) based on chemical or biological analysis of levels of contaminants in sediment or biota. To validate the predicted risk, the actual impact of dumped harbour sediments on local ecosystems (C) can be determined using a dedicated set of in vitro and in vivo bioassays as well as bio-indicators selected based on the information obtained from (A) and (B) and on the characteristics of the local ecosystem. Conversely, the local sediment impact assessment (C) can direct fine-tuning of the selection of chemical and bioassay analyses and for setting safe levels in the licensing system. It is concluded that in vitro and in vivo bioassays and biological indicators are useful tools in the process of hazard, ecotoxicological risk and impact assessment of dredged harbour sediments, provided they are consciously chosen and quality criteria for assay performance are defined.

Estrogenicity profile and estrogenic compounds determined in river sediments by chemical analysis, ELISA and yeast assays

An effects-directed strategy was applied to bed sediments of a polluted tributary in order to isolate and identify the major estrogenic chemicals it discharges into the River Po, the principal Italian watercourse. Sediment extract was concentrated by solid phase extraction and then fractioned into 10 fractions by reversed phase high performance liquid chromatography (RP-HPLC). Estrogenic activity of whole extract and fractions were determined using a recombinant yeast assay containing the human estrogen receptor (YES). The 10 fractions and whole extract were analysed for target compounds, e.g. estrone (E1), 17beta-estradiol (E2), estriol (E3), 4-nonylphenol (NP), 4-tert-octylphenol (t-OP), bisphenol A (BPA), using both liquid chromatography-tandem mass spectrometry (LC-MS/MS) and non-competitive enzyme-linked immunosorbent assays (ELISA). The YES assay determined high estrogenic activity in whole sediment (15.6 ng/g EE2 equivalents), and positive results for fractions nr 1, 2, 6, 7 and 8. E1, E3 and NP were the main estrogenic chemicals, however, other unidentified compounds contributed to sediment estrogenicity, particularly for polar fractions nr 1 and 2. A GC-MS screening performed in scan mode identified other potential contributors such as phthalates (DBP, BBP), and OP isomers. A next sampling campaign extended to other tributaries and receiving stretches of the River Po confirmed E1, E3 and NP as major estrogenic chemicals potentially threatening other sites of the main river. In general, target compound ELISAs have been shown to be suitable tools for a rapid screening of wide areas or large numbers of environmental samples for estrogenic risk. The potential for interferences suggests however to use cautiously the concentration values obtained from some of the immunoassays.

Sample preparation method for the ER-CALUX bioassay screening of (xeno-)estrogenic activity in sediment extracts

The application of bioassays to assess the occurrence of estrogenic compounds in the environment is increasing in both a scientific and statutory context. The availability of appropriate validated methods for sample pre-treatment and analysis is crucial for the successful implementation of bioassays. Here, we present a sample preparation method for the bioassay screening of estrogenic activity in sediment with the in vitro Estrogen Receptor mediated Chemical Activated LUciferase gene eXpression (ER-CALUX) assay. The method makes use of an Accelerated Solvent (ASE) or Soxhlet extraction with a mixture of dichloromethane and acetone (3:1, v/v), followed by clean up of the extract by Gel Permeation Chromatography (GPC). Recoveries of a panel of 17 pollutants differing largely in physical-chemical properties from spiked sediment were determined and appeared to be on average about 86%. Furthermore, the estrogenic potencies of all test compounds were individually assessed by determination of concentration-response relationships in the ER-CALUX assay. Concentration dependent estrogenic potency was found for 14 of the 17 compounds, with potencies of about 10(5) to 10(7) fold lower than the natural estrogenic hormone 17beta-estradiol. Anti-estrogenic potency was assessed by testing combinations of estradiol and individual test compounds, but was found for none of the compounds. The low estrogenic activity of the test compounds in the spiking mixture was well recovered during GPC treatment of the pure mixture, but did not contribute significantly to the background estrogenic activity present in the spiked sediment. Application of the method to field samples showed that estrogenic activity can be found at different types of locations, and demonstrated that levels between locations may vary considerably over relatively short distances.

Profiles of environmental and endogenous estrogens in the zebra mussel Dreissena polymorpha

Contamination of freshwater environments by estrogenic compounds has led to concern over potential impacts on invertebrate species. The uptake of the environmental estrogen 17beta-estradiol (E2) by the freshwater bivalve Dreissena polymorpha and the nature of estrogenic substances in tissues of D. polymorpha mussels collected from four freshwater sites were investigated. Exposure of mussels to [(14)C]-E2 (7.5 ngl(-1), 13 days) revealed that the estrogen bioconcentrated 840+/-58 (males) and 580+/-77 (females) fold (mean+/-95% confidence limits) and was metabolised in tissues to a persistent lipophilic ester. Estrogenic activity, measured using a recombinant human estrogen receptor transcription screen (YES), was detected in tissue extracts of all mussels sampled from freshwater sites. At two reference sites the estrogenic activities of mussel tissues were <1ng E2 equivalents g(-1) wet weight tissue (ng EEQ g(-1) ww) which increased to 7.4-45.7ng EEQg(-1) ww for both free and esterified estrogens extracted from hydrolysed tissue extracts. In mussels collected from two contaminated river sites, estrogenic activity was 0.2-6.7ng EEQ g(-1) ww (free estrogens) and 25.6-316.2ng EEQ g(-1) ww for total estrogens. Fractionation of the tissue extracts revealed that E2 (as the ester) was the predominant estrogen detected in both sexes of D. polymorpha, however, the xenoestrogen nonylphenol (NP) was also detected in mussels sampled from contaminated rivers. The detection of endogenous esterified E2 and the potential for accumulation of exogenous E2 and NP in D. polymorpha tissues suggests that this bivalve could be susceptible to exposure to estrogenic contaminants in the aquatic environment.

An in vitro/in vivo screening assay as a sensitive tool to assess endocrine disruptive activity in surface water

Adult male fathead minnow were exposed for 14 or 28-days under flow-through conditions to undiluted filtered water samples from the rivers Meuse and Rhine in the Netherlands. The experiment included two vessels per treatment each containing 10 fish and samples of five fish were taken after 14 and 28 days. Additional groups were exposed to 17alpha-ethinylestradiol (EE2) as a reference and untreated drinking water as a negative control. Major endpoints examined included induction of vitellogenin (VTG) synthesis, VTG mRNA activity, hepato- and gonadosomatic indices (HSI and GSI) and gonadal histology. No significant difference was recorded in body weight or mean GSI values between the various treatments. Only exposure to Meuse water resulted in significantly higher HSI means after 14 days. Histological examination showed no apparent effects on gonadal tissue except for eosinophilic blood plasma in fish exposed to Meuse water or EE2. After 14 and 28 days, elevated VTG and VTG mRNA levels were measured in most livers of the fish exposed to Meuse water, but not in the fish exposed to Rhine water. This was confirmed by measuring estrogenic responses in the in vitro ER CALUX assay. Induction of VTG synthesis proved to be the most sensitive endpoint in the Non Spawning Male Fish Assay for in vivo detection of bio-available estrogenic activity supplementary to a sensitive in vitro assay. The other endpoints examined varied too much and required a higher number of fish or replicates to achieve sufficient power for statistical testing making them less animal friendly.

Estrogenic and dioxin-like compounds in sediment from Zierikzee harbour identified with CALUX assay-directed fractionation combined with one and two dimensional gas chromatography analyses

The identity of compounds responsible for estrogenic and dioxin-like activities in sediment from the harbour of the small town Zierikzee in Zeeland, The Netherlands, was investigated using a bioassay directed fractionation approach with the in vitro estrogen and dioxin responsive reporter gene assays ER- and DR-CALUX. For identification of compounds exhibiting activity in the bioassays, either one or two-dimensional GC in combination with quadrupole (MSD), ion trap (ITD) or time-of-flight mass spectrometric detection (ToF-MS) was used, depending on the biological and chemical characteristics and the complexity of the fractions. The natural estrogenic hormone 17-beta-estradiol and its metabolite estrone were identified with GC-ITD as the main contributors to the estrogenic activity. After successive rounds of fractionation, the dioxin-like activity could be explained by the presence of various polycyclic aromatic hydrocarbons identified with GC-MSD and two-dimensional comprehensive GC x GC-ToF-MS. Some estrogenic activity of a relatively non-polar nature remained unidentified.

Biological validation of a sample preparation method for ER-CALUX bioanalysis of estrogenic activity in sediment using mixtures of xeno-estrogens

The combined estrogenic effects of mixtures of environmental pollutants in the in vitro ER-CALUX (chemical activated luciferase gene expression) bioassaywere examined to biologically validate a sample preparation method for the analysis of estrogenic compounds in sediment. The method used accelerated solvent extraction (ASE) and gel permeation chromatography (GPC) and was validated with respect to recovery of biological response taking mixture effects into account. Four mixtures of three to six xenoestrogenic compounds (bisphenol A, 4-nonylphenol, (4,4'-dichlorodiphenyl)trichloroethane, (2,4'-dichlorodiphenyl)trichloroethane, dieldrin, 4-n-octylphenol, alpha-chlordane, dibutylphthalate, (4,4'-dichlorodiphenyl)dichloroethylene, and 2,4,5-trichlorobiphenyl) were prepared. Experimentally determined mixture effects were well described by the concept of concentration addition (CA), as expected for similarly acting compounds. Observed estradiol equivalence factors of the mixtures (on average 1.2 +/- 0.3) agreed very well with the value predicted according to CA. The sample preparation method was then applied to pure mixtures of standards and to sediment spiked with one of the mixtures. Recoveries of estrogenic compounds were estimated by determination of their mixture potencies in ER-CALUX and compared to the mixture effects predicted by CA. Recoveries of estrogenic activity were between 80 and 129%, indicating that the additive behavior of mixtures of xeno-estrogens is well conserved during sample preparation. Together with an average repeatability of 18.3%, low average limit of detection (2.6 +/- 1.8 pg of EEQ/ g), and coefficient of variance (3.5 +/- 3.3%),this demonstrated the suitability of the sample preparation method for the analysis of mixtures of (xeno-)estrogenic compounds in sediment with the ER-CALUX assay.

In vivo visual reporter system for detection of estrogen-like substances by transgenic medaka

Detection of endocrine disrupting chemicals, in particular, environmental estrogens with living organisms, has many advantages if compared to chemical analysis. The screening of novel pollutants with meaningful endpoints, the integration of uptake, bioconcentration, and excretion as well as the evaluation of endocrine disrupting effects with respect to toxicity require in vivo biotests for estrogen-like substances (ELSs). Critical disadvantages of whole organism biotests are their low sensitivity and the need for laborious and time-consuming work. To overcome these problems, we have developed a transgenic medaka strain harboring the green fluorescence protein (GFP) gene driven by choriogenin H gene regulatory elements. Choriogenin H is an egg envelope protein induced by estrogens in the liver. With yolk sac larvae of this strain, GFP induction in liver was observed 24 h after onset of aqueous exposure to 0.63 nM 17beta-estradiol (E2), 0.34 nM ethynylestradiol, or 14.8 nM estrone. Furthermore, concentrated sewage treatment effluent induced GFP expression. Comparison of E2 equivalents estimated by GFP-induction in transgenic medaka, a YES assay, and GC/MS showed detection limits in the same order of magnitude. These results indicated that the sensitivity of the transgenic medaka strain was sufficient for application as an alternative model in monitoring environmental water samples for ELSs.

Androgenic activity in surface water samples detected using the AR-LUX assay: indications for mixture effects

This paper describes the screening of 22 extracts from 18 different aquatic environmental samples for androgenic activity, including indirect and interactive effects on androgen receptor (AR)-mediated signal transduction, using the AR-LUX bioassay. Four samples, originating from an industrial wastewater treatment plant (WTP) or the river Meuse, were shown to contain substantial androgenic activity. Moreover, the samples originating from the industrial WTP showed an enhancement of the maximal androgenic response relative to that elicited by the standard androgen methyltrienolone (R1881) in the AR-LUX assay. This indicates the involvement of cellular mechanisms other than receptor-ligand interaction influencing AR-regulated pathways. This also demonstrates the additional value of cell based assays featuring a more complete array of fully functional interacting pathways. Chemical analysis using GC-MS confirmed the presence of a number of androgens and also estrogens in these WTP samples. Subsequently, we showed that estrone and tributyltin hydride (TBT-H) enhance the response to androgens. This indicates that the presence of numerous compounds in addition to androgens in environmental mixtures might very well result in a more profound perturbation of the normal physiology of exposed organisms than estimated based on the androgen levels alone. Therefore, risk assessment of environmental samples should include an evaluation of the presence and the interactive effects of (ant)agonists of carefully selected relevant cellular receptors in order to provide a realistic estimate of the integrated ecotoxicological risk of the compounds present.

Androgenic and estrogenic response of green mussel extracts from Singapore's coastal environment using a human cell-based bioassay

In the last decade, evidence of endocrine disruption in biota exposed to environmental pollutants has raised serious concern. Human cell-based bioassays have been developed to evaluate induced androgenic and estrogenic activities of chemical compounds. However, bioassays have been sparsely applied to environmental samples. In this study we present data on sex hormone activities in the green mussel, Perna viridis, in Singapore's coastal waters. P.viridis is a common bioindicator of marine contamination, and this study is a follow-up to an earlier investigation that reported the presence of sex hormone activities in seawater samples from Singapore's coastal environment. Specimens were collected from eight locations around the Singapore coastline and analyzed for persistent organic pollutants (POPs) and heavy metals. Tissue extracts were then screened for activities on androgen receptors (ARs) and estrogen receptors (ER-alpha and ER-beta) using a reporter gene bioassay based on a HeLa human cell line. Mussel extracts alone did not exhibit AR activity, but in the presence of the reference androgenic hormone dihydrotestosterone (DHT), activities were up to 340% higher than those observed for DHT alone. Peak activities were observed in locations adjacent to industrial and shipping activities. Estrogenic activities of the mussel extract both alone and in the presence of reference hormone were positive. Correlations were statistically investigated between sex hormone activities, levels of pollutants in the mussel tissues, and various biological parameters (specimen size, sex ratio, lipid and moisture content). Significant correlations exist between AR activities, in the presence of DHT, and total concentration of POPs (r= 0.725, p < 0.05).