Greenhouse gas formation during the ensiling process of grass and lucerne silage.

Silage is an essential global feedstuff and an emitter of greenhouse gases. However, few studies have examined the formation of carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) during the ensiling process. This study aimed to record the course of gas concentrations in forage during the ensiling process and determine the temporal variation in the (microbiological) formation processes. Grass and lucerne, each with two different dry matter (DM) concentrations (four variants, each n = 3), were ensiled in laboratory-scale barrels (120 L). Gas samples were taken from the headspace of the barrels and analysed using a gas chromatograph. The measurement period included the first 49 days of the ensiling process and the measurement interval was 0.5-48.0 h. For all variants, a rapid increase in CO2 concentration and a one-time N2O concentration peak was observed between ensiling hours 36 and 96. Lower DM concentration led to significantly faster CO2 production (p < 0.05). Lucerne forage and higher DM concentrations led to significantly increased N2O concentrations (p < 0.05). The extensive measurements demonstrated that butyric acid formation by clostridia contributes to CH4 formation; thus, lucerne silage had a significantly higher concentration from ensiling day 13 (p < 0.05). Therefore, malfermentation actively contributes to the formation of greenhouse gases. The method described here provides further insights into greenhouse gas formation during the ensiling process and can thus help to improve ensiling research and management.

The Role of Behavioral Ecotoxicology in Environmental Protection.

For decades, we have known that chemicals affect human and wildlife behavior. Moreover, due to recent technological and computational advances, scientists are now increasingly aware that a wide variety of contaminants and other environmental stressors adversely affect organismal behavior and subsequent ecological outcomes in terrestrial and aquatic ecosystems. There is also a groundswell of concern that regulatory ecotoxicology does not adequately consider behavior, primarily due to a lack of standardized toxicity methods. This has, in turn, led to the exclusion of many behavioral ecotoxicology studies from chemical risk assessments. To improve understanding of the challenges and opportunities for behavioral ecotoxicology within regulatory toxicology/risk assessment, a unique workshop with international representatives from the fields of behavioral ecology, ecotoxicology, regulatory (eco)toxicology, neurotoxicology, test standardization, and risk assessment resulted in the formation of consensus perspectives and recommendations, which promise to serve as a roadmap to advance interfaces among the basic and translational sciences, and regulatory practices.

A new experimental setup for measuring greenhouse gas and volatile organic compound emissions of silage during the aerobic storage period in a special silage respiration chamber.

The aim of this study was to develop a new experimental setup to determine parallel the emissions of greenhouse gases (GHG) and volatile organic compounds (VOCs) from silage during the opening as well as the subsequent aerobic storage phase of the complete bale without wrapping film. For this purpose, a special silage respiration chamber was used in which a silage bale could be examined. The gas analysis (CO2, methanol, ethanol, ethyl acetate) of inlet, ambient and outlet air of the silage respiration chamber was carried out by photoacoustic spectroscopy. The gas samples taken inside the bale were analysed by gas chromatography for CO2, O2, CH4, and N2O. Three silage bales (grass and lucerne) as the smallest silage unit commonly used in practice were examined. The emission behaviour of the bales was recorded during experimental periods up to 55 days. The results allow a differentiation of the outgassing processes. On the one hand, gases produced during the anaerobic ensiling process (CO2, CH4, N2O) are released once in a large amount during the first experimental hours after opening the silage. On the other hand, a continuous outgassing process takes place, which is particularly true for the VOCs ethanol, methanol, and ethyl acetate, whereby VOC emissions increase with rising ambient air temperatures. In this study, the emissions during the first 600 experimental hours from the grass silage bale and lucerne silage bale were 2313 g and 2612 g CO2, 17.6 g and 145.2 g methanol, 132.3 g and 675.9 g ethanol, 55.1 g and 66.2 g ethyl acetate, respectively. Nevertheless, the focus of this study was on the technical recording of gas concentrations inside the silage bale itself and the emissions in the ambient air of the bale. For a better interpretation of the data, additional factors should be considered in further investigations.

Emerging investigator series: use of behavioural endpoints in the regulation of chemicals.

Interest in behavioural ecotoxicology is growing, partly due to technological and computational advances in recording behaviours but also because of improvements of detection capacity facilitating reporting effects at environmentally relevant concentrations. The peer-reviewed literature now contains studies investigating the effects of chemicals, including pesticides and pharmaceuticals, on migration, dispersal, aggression, sociability, reproduction, feeding and anti-predator behaviours in vertebrates and invertebrates. To understand how behavioural studies could be used in regulatory decision-making we: (1) assessed the legal obstacles to using behavioural endpoints in EU chemicals regulation; (2) analysed the known cases of use of behavioural endpoints in EU chemicals regulation; and (3) provided examples of behavioural endpoints of relevance for population level effects. We conclude that the only legal obstacle to the use of behavioural endpoints in EU chemicals regulation is whether an endpoint is considered to be relevant at the population level or not. We also conclude that ecotoxicity studies investigating behavioural endpoints are occasionally used in the EU chemicals regulation, and underscore that behavioural endpoints can be relevant at the population level. To improve the current use of behavioural studies in regulatory decision-making contribution from all relevant stakeholders is required. We have the following recommendations: (1) researchers should conduct robust, well-designed and transparent studies that emphasize the relevance of the study for regulation of chemicals; (2) editors and scientific journals should promote detailed, reliable and clearly reported studies; (3) regulatory agencies and the chemical industry need to embrace new behavioural endpoints of relevance at the population level.

A critical review of the environmental occurrence and potential effects in aquatic vertebrates of the potent androgen receptor agonist 17ß-trenbolone.

Trenbolone acetate is widely used in some parts of the world for its desirable anabolic effects on livestock. Several metabolites of the acetate, including 17ß-trenbolone, have been detected at low nanograms per liter concentrations in surface waters associated with animal feedlots. The 17ß-trenbolone isomer can affect androgen receptor signaling pathways in various vertebrate species at comparatively low concentrations/doses. The present article provides a comprehensive review and synthesis of the existing literature concerning exposure to and biological effects of 17ß-trenbolone, with an emphasis on potential risks to aquatic animals. In vitro studies indicate that, although 17ß-trenbolone can activate several nuclear hormone receptors, its highest affinity is for the androgen receptor in all vertebrate taxa examined, including fish. Exposure of fish to nanograms per liter water concentrations of 17ß-trenbolone can cause changes in endocrine function in the short term, and adverse apical effects in longer exposures during development and reproduction. Impacts on endocrine function typically are indicative of inappropriate androgen receptor signaling, such as changes in sex steroid metabolism, impacts on gonadal stage, and masculinization of females. Exposure of fish to 17ß-trenbolone during sexual differentiation in early development can greatly skew sex ratios, whereas adult exposures can adversely impact fertility and fecundity. To fully assess ecosystem-level risks, additional research is warranted to address uncertainties as to the degree/breadth of environmental exposures and potential population-level effects of 17ß-trenbolone in sensitive species. Environ Toxicol Chem 2018;37:2064-2078. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

New approach to weight-of-evidence assessment of ecotoxicological effects in regulatory decision-making.

Ecological risk assessments and risk management decisions are only as sound as the underlying information and processes to integrate them. It is important to develop transparent and reproducible procedures a priori to integrate often-heterogeneous evidence. Current weight-of-evidence (WoE) approaches for effects or hazard assessment tend to conflate aspects of the assessment of the quality of the data with the strength of the body of evidence as a whole. We take forward recent developments in the critical appraisal of the reliability and relevance of individual ecotoxicological studies as part of the effect or hazard assessment of prospective risk assessments and propose a streamlined WoE approach. The aim is to avoid overlap and double accounting of criteria used in reliability and relevance with that used in current WoE methods. The protection goals, problem formulation, and evaluation process need to be clarified at the outset. The data are first integrated according to lines of evidence (LoEs), typically mechanistic insights (e.g., cellular, subcellular, genomic), in vivo experiments, and higher-tiered field or observational studies. Data are then plotted on the basis of both relevance and reliability scores or categories. This graphical approach provides a means to visually assess and communicate the credibility (reliability and relevance of available individual studies), quantity, diversity, and consistency of the evidence. In addition, the external coherence of the body of evidence needs to be considered. The final step in the process is to derive an expression of the confidence in the conclusions of integrating the information considering these 5 aspects in the context of remaining uncertainties. We suggest that this streamlined approach to WoE for the effects or hazard characterization should facilitate reproducible and transparent assessments of data across different regulatory requirements. Integr Environ Assess Manag 2017;13:573-579. © 2017 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Recommended approaches to the scientific evaluation of ecotoxicological hazards and risks of endocrine-active substances.

A SETAC Pellston Workshop® "Environmental Hazard and Risk Assessment Approaches for Endocrine-Active Substances (EHRA)" was held in February 2016 in Pensacola, Florida, USA. The primary objective of the workshop was to provide advice, based on current scientific understanding, to regulators and policy makers; the aim being to make considered, informed decisions on whether to select an ecotoxicological hazard- or a risk-based approach for regulating a given endocrine-disrupting substance (EDS) under review. The workshop additionally considered recent developments in the identification of EDS. Case studies were undertaken on 6 endocrine-active substances (EAS-not necessarily proven EDS, but substances known to interact directly with the endocrine system) that are representative of a range of perturbations of the endocrine system and considered to be data rich in relevant information at multiple biological levels of organization for 1 or more ecologically relevant taxa. The substances selected were 17α-ethinylestradiol, perchlorate, propiconazole, 17ß-trenbolone, tributyltin, and vinclozolin. The 6 case studies were not comprehensive safety evaluations but provided foundations for clarifying key issues and procedures that should be considered when assessing the ecotoxicological hazards and risks of EAS and EDS. The workshop also highlighted areas of scientific uncertainty, and made specific recommendations for research and methods-development to resolve some of the identified issues. The present paper provides broad guidance for scientists in regulatory authorities, industry, and academia on issues likely to arise during the ecotoxicological hazard and risk assessment of EAS and EDS. The primary conclusion of this paper, and of the SETAC Pellston Workshop on which it is based, is that if data on environmental exposure, effects on sensitive species and life-stages, delayed effects, and effects at low concentrations are robust, initiating environmental risk assessment of EDS is scientifically sound and sufficiently reliable and protective of the environment. In the absence of such data, assessment on the basis of hazard is scientifically justified until such time as relevant new information is available. Integr Environ Assess Manag 2017;13:267-279. © 2017 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Evaluating the credibility of histopathology data in environmental endocrine toxicity studies.

Agencies responsible for environmental protection are tasked with developing regulatory guidance that is based on the best available scientific evidence. Histopathology is a common endpoint in toxicologic bioassays; however, because of the subjective nature of this endpoint, and the advanced level of specialized training required for its effective utilization, the reliability of histopathology data can be inconsistent. Consequently, mechanisms for evaluating such data on a case-by-case basis are needed. The purposes of the present review are to describe a methodology that can be used to evaluate the credibility of histopathology findings and to discuss the results of such assessments as applied to real-world data collected from the scientific literature. A key outcome of these efforts was the finding that only 54% of the studies examined contained histopathology data that were considered to be either highly credible or credible, whereas data in 46% of those studies were of equivocal, dubious, or no credibility. In addition, the results indicated that the quality of the data examined tended to decline during the past 15 yr. The ultimate goals of the present review are to draw attention to reliability issues that can affect histopathology results, provide recommendations to improve the quality of this endpoint, and suggest an approach for the expeditious and judicious use of histopathology data in the weight-of-evidence determinations required for hazard and/or risk assessment. This exercise was conducted initially as part of a SETAC Pellston Workshop™ entitled "Environmental Hazard and Risk Assessment Approaches for Endocrine-Active Chemicals (EHRA): Developing Technical Guidance Based on Case Studies to Support Decision Making" that was held in Pensacola, Florida (USA) from 31 January to 5 February 2016. Environ Toxicol Chem 2017;36:601-611. © 2016 SETAC.

Current limitations and recommendations to improve testing for the environmental assessment of endocrine active substances.

In the present study, existing regulatory frameworks and test systems for assessing potential endocrine active chemicals are described, and associated challenges are discussed, along with proposed approaches to address these challenges. Regulatory frameworks vary somewhat across geographies, but all basically evaluate whether a chemical possesses endocrine activity and whether this activity can result in adverse outcomes either to humans or to the environment. Current test systems include in silico, in vitro, and in vivo techniques focused on detecting potential endocrine activity, and in vivo tests that collect apical data to detect possible adverse effects. These test systems are currently designed to robustly assess endocrine activity and/or adverse effects in the estrogen, androgen, and thyroid hormone signaling pathways; however, there are some limitations of current test systems for evaluating endocrine hazard and risk. These limitations include a lack of certainty regarding: 1) adequately sensitive species and life stages; 2) mechanistic endpoints that are diagnostic for endocrine pathways of concern; and 3) the linkage between mechanistic responses and apical, adverse outcomes. Furthermore, some existing test methods are resource intensive with regard to time, cost, and use of animals. However, based on recent experiences, there are opportunities to improve approaches to and guidance for existing test methods and to reduce uncertainty. For example, in vitro high-throughput screening could be used to prioritize chemicals for testing and provide insights as to the most appropriate assays for characterizing hazard and risk. Other recommendations include adding endpoints for elucidating connections between mechanistic effects and adverse outcomes, identifying potentially sensitive taxa for which test methods currently do not exist, and addressing key endocrine pathways of possible concern in addition to those associated with estrogen, androgen, and thyroid signaling. Integr Environ Assess Manag 2017;13:302-316. © 2016 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Identification, assessment and management of "endocrine disruptors" in wildlife in the EU substance legislation--discussion paper from the German Federal Environment Agency (UBA).

A discussion paper was developed by a panel of experts of the German Federal Environment Agency (UBA) contributing to the on-going debate on the identification, assessment and management of endocrine disruptors with a view to protect wildlife according to the EU substance legislation (plant protection products, biocides, industrial chemicals). Based on a critical synthesis of the state-of-the-art regarding regulatory requirements, testing methods, assessment schemes, decision-making criteria and risk management options, we advise an appropriate and consistent implementation of this important subject into existing chemicals legislation in Europe. Our proposal for a balanced risk management of endocrine disruptors essentially advocates transparent regulatory decision making based on a scientifically robust weight of evidence approach and an adequate risk management consistent across different legislations. With respect to the latter, a more explicit consideration of the principle of proportionality of regulatory decision making and socio-economic benefits in the on-going debate is further encouraged.

The zebrafish embryo model in toxicology and teratology, September 2­3, 2010, Karlsruhe, Germany.

The use of fish embryos is gaining popularity for research in the area of toxicology and teratology. Particularly embryos of the zebrafish offer an array of different applications ranging from regulatory testing to mechanistic research. For this reason a consortium of two research centres and a company with the support of the COST Action EuFishBiomed has organised the Workshop "The zebrafish embryo model in toxicology and teratology", in Karlsruhe, Germany, 2nd­3rd September 2010. The workshop aimed at bringing together experts from different areas of toxicology using the (zebra)fish embryo and stimulating networking between scientists and representatives from regulatory bodies, research institutions and industry. Recent findings, presented in various platform presentations in the area of regulatory toxicity, high throughput screening, toxicogenomics, as well as environmental and human risk assessment are highlighted in this meeting report. Furthermore, the constraints and possibilities of the model as discussed at the workshop are described. A follow up-meeting was appreciated by the about 120 participants and is planned for 2012.

Short-term exposure to a treated sewage effluent alters reproductive behaviour in the three-spined stickleback (Gasterosteus aculeatus).

Some UK sewage treatment work (STW) effluents have been found to contain high levels of anti-androgenic activity, but the biological significance of this activity to fish has not been determined. The aim of this study was to investigate the effects of exposure to a STW effluent with anti-androgenic activity on the reproductive physiology and behaviour of three-spined sticklebacks (Gasterosteus aculeatus). Fish were exposed to a STW effluent (50 and 100%, v/v) with a strong anti-androgenic activity (328.56±36.83 µgl(-1) flutamide equivalent, as quantified in a recombinant yeast assay containing the human androgen receptor) and a low level of oestrogenic activity (3.32±0.66 ngl(-1) oestradiol equivalent, quantified in a recombinant yeast assay containing the human oestrogen receptor) for a period of 21 days in a flow-through system in the laboratory. Levels of spiggin, an androgen-regulated protein, were not affected by the STW effluent exposure, nor were levels of vitellogenin (a biomarker of oestrogen exposure), but the reproductive behaviour of the males was impacted. Males exposed to full strength STW effluent built fewer nests and there was a significant reduction in male courtship behaviour for exposures to both the 50 and 100% STW effluent treatments compared with controls. The effect seen on the reproduction of male sticklebacks may not necessarily have been as a consequence of the endocrine active chemicals present in the STW effluent alone, but could relate to other features of the effluent, such as turbidity that can impair visual signalling important for courtship interactions. Regardless the specific causation, the data presented show that effluents from STW have an impact on reproductive behaviour in male sticklebacks which in turn affects reproductive performance/outcome. The study further highlights the use of fish behaviour as a sensitive endpoint for assessing potential effects of contaminated water bodies on fish reproduction.

Estrogenic wastewater treatment works effluents reduce egg production in fish.

Estrogenic chemicals found within wastewater treatment work (WwTW) effluents have been shown individually to inhibit reproduction in fish, but the impact of the WwTW effluents themselves and the complex mixtures of environmental estrogens and other endocrine disrupting chemicals they contain has not been established. In this investigation, the effect of exposure to three WwTW effluents, with differing levels of estrogenic activity, was assessed on egg production in pair-breeding fathead minnow. Exposure to two of the three effluents tested resulted in a reduced egg production (by 28% for effluent I at a dilution of 50% and by 44% for effluent III at full strength), which was proportional to the estrogenic content of the effluents. The test effluents, however, had a greater effect on egg production than might be expected, on the basis of both the response they induced for induction of vitellogenin (an estrogen exposure biomarker) and when compared with an equivalent estrogen exposure to EE2. These data show that reliance on relatively simple biomarker responses for estrogenic activity alone, such as vitellogenin, can significantly underestimate the impacts of estrogenic WwTW effluents on fitness parameters such as reproductive health that are regulated by more complex estrogenic (and other endocrine) signaling mechanisms.

A practicable laboratory flow-through exposure system for assessing the health effects of effluents in fish.

The knowledge that exposure to estrogenic wastewater treatment work (WwTW) effluents induces a range of reproductive abnormalities in fish has highlighted the need to understand the wider health effects of effluents. Access to laboratory-based testing systems for WwTW effluents could greatly facilitate this endeavour. In this investigation, a laboratory-based test system was developed and applied for WwTW effluents using fathead minnows (Pimephales promelas). Sexually maturing fathead minnows were exposed, under flow-through conditions in the laboratory, for up to 21 days to graded concentrations of effluent from three different UK (temperate) WwTWs. The stability of the estrogenic component within the test system was assessed via measurements for estradiol and estrone concentrations in the effluent, and through determining estrogenic responses in an in vitro recombinant yeast estrogen screen (rYES) and in fish (plasma vitellogenin induction). The estrogen component of the effluents was stable within the holding system used (chilled <10 degrees C) for up to 7 days and measured concentrations of estradiol and estrone were shown to differ by less than 20% between the first and final day of use for each batch of effluent. Total estrogenic activity as measured in the rYES was found to be more variable (up to 66% variance between measurements for the two time points) but there was no consistent trend for a reduction in estrogenic activity. Vitellogenin was induced in males in a concentration-dependent manner and the magnitude of the response observed was proportional to the average measured concentrations of estradiol and estrone in the exposure effluent. The system described, thus, provides a robust test method for evaluating the estrogenic effects of temperate WwTW effluents that could be further applied to assess wider health effects, including population-relevant endpoints such as reproduction, using model OECD warm-water fish species such as the fathead minnow.

Gene expression profiles revealing the mechanisms of anti-androgen- and estrogen-induced feminization in fish.

Environmental anti-androgens are increasingly being recognized as potential contributing factors in the chemically induced feminization of wild fish because, by blocking androgen action, they can produce phenotypic effects similar to environmental estrogens. The molecular mechanisms by which anti-androgens and estrogens exert feminizing effects, however, have not been systematically compared. Using a targeted approach, we profiled the expression responses of a suite of 22 genes involved in reproduction, growth and development (processes controlled by androgens and estrogens) in the liver and gonad in adult male and female fathead minnow (Pimephales promelas) exposed to the model anti-androgen flutamide and the model synthetic estrogen 17alpha-ethinylestradiol (EE(2)). Both flutamide (320 microg/L) and EE(2) (10ng/L) produced phenotypic effects indicative of feminization (induction of plasma vitellogenin, reduced gonadosomatic index, and reduced secondary sex characters), although for the chosen test concentrations EE(2) was the more potent. For the genes studied, flutamide and EE(2) produced distinct expression profiles, suggesting that they largely operate via distinct molecular mechanisms. As examples, in liver EE(2) (but not flutamide) exposure up-regulated estrogen receptor (ER) alpha mRNA, whereas flutamide exposure increased ERbeta and ERgamma mRNAs in males and resulted in decreased androgen receptor (AR) mRNA in females. In the testis, flutamide up-regulated genes coding for enzymes involved in androgen biosynthesis (cytochrome P450 17 [CYP17] and 11beta-hydroxysteroid dehydrogenase [11beta-HSD]) implying an inhibitory action on androgen negative feedback pathways. EE(2), in contrast, inhibited the expression of enzymes involved in androgen biosynthesis (CYP17, 11beta-HSD and 17beta-hydroxysteroid dehydrogenase [17beta-HSD]). There were also some commonalities in the molecular mechanisms of flutamide and EE(2) action, including the down-regulation of gonadal sex steroid receptor expression (gonadal AR and ovarian ERalpha), increased expression of genes coding for estrogen-producing enzymes (cytochrome P450 19A and B [CYP19A and CYP19B]), decreased expression of genes involved in testis differentiation (anti-Mullerian hormone [AMH] and doublesex and mab-3 related transcription factor 1 [DMRT1]), and decreased expression of hepatic genes which mediate wider physiological processes such as somatic growth (growth hormone [GH], GH receptor [GHR], insulin-like growth factor-I [IGF-I], IGF-I receptor [IGF-IR], thyroid hormone receptor alpha [TRalpha] and beta [TRbeta]).

Gene expression profiling for understanding chemical causation of biological effects for complex mixtures: a case study on estrogens.

Gene expression profiling offers considerable potential for identifying chemical causation of effects induced in exposures to complex mixtures, and for understanding the mechanistic basis for their phenotypic effects. We characterized gene expression responses in livers and gonads of fathead minnow (Pimephales promelas) exposed (for 14-21 days) to estrogenic wastewater treatment works final effluents with varying potencies and assessed the extent to which these expression profiles mapped with those induced by individual steroid estrogens present in the effluents (17beta-estradiol and 17alpha-ethinylestradiol) and, thus, were diagnostic of estrogen exposure. For these studies, we adopted a targeted approach (via real-time PCR) with a suite of 12 genes in liver and 21 genes in gonad known to play key roles in reproduction, growth and development (processes controlled by estrogens) and responses were compared with effects on phenotypic end points indicative of feminization. Gene responses to effluent were induced predominantly in a linear (monotonic) concentration-dependent manner but were complex with many genes responding differently between tissue types and sexes. The gene expression profiles for the estrogenic effluents and the individual steroid estrogens had many common features. There were marked differences in the profiles between the two effluents, however, that were not explained by differences in their estrogenic potencies, suggesting that these may have arisen as a consequence of differences in the contents of other chemicals, which may act directly or indirectly with the estrogen-response pathway to alter estrogen-induced gene expression. These data demonstrate that the patterns of gene expression induced by estrogenic effluents, although complex, can be diagnostic for some of the estrogens they contain and provide insights into the mechanistic basis for the phenotypic effects seen.