Evidence of temperature-dependent effects on the estrogenic response of fish: implications with regard to climate change

The official published version can be obtained from the link below - Copyright @ 2008 Elsevier BV.Chemical risk assessment is fraught with difficulty due to the problem of accounting for the effects of mixtures. In addition to the uncertainty arising from chemical-to-chemical interactions, it is possible that environmental variables, such as temperature, influence the biological response to chemical challenge, acting as confounding factors in the analysis of mixture effects. Here, we investigate the effects of temperature on the response of fish to a defined mixture of estrogenic chemicals. It was anticipated that the response to the mixture may be exacerbated at higher temperatures, due to an increase in the rate of physiological processing. This is a pertinent issue in view of global climate change. Fathead minnows (Pimephales promelas) were exposed to the mixture in parallel exposure studies, which were carried out at different temperatures (20 and 30 degrees C). The estrogenic response was characterised using an established assay, involving the analysis of the egg yolk protein, vitellogenin (VTG). Patterns of VTG gene expression were also analysed using real-time QPCR. The results revealed that there was no effect of temperature on the magnitude of the VTG response after 2 weeks of chemical exposure. However, the analysis of mixture effects at two additional time points (24 h and 7 days) revealed that the response was induced more rapidly at the higher temperature. This trend was apparent from the analysis of effects both at the molecular and biochemical level. Whilst this indicates that climatic effects on water temperature are not a significant issue with regard to the long-term risk assessment of estrogenic chemicals, the relevance of short-term effects is, as yet, unclear. Furthermore, analysis of the patterns of VTG gene expression versus protein induction gives an insight into the physiological mechanisms responsible for temperature-dependent effects on the reproductive phenology of species such as roach. Hence, the data contribute to our understanding of the implications of global climate change for wild fish populations.This work was funded by a grant from the Natural Environment Research Council NE/D00389X/1). Additional support was provided by a small research grant from the Fisheries Society of the British Isles

EDEN. Exploring novel endpoints, exposure, low-dose and mixture effects in humans, aquatic wildlife and laboratory animals. Final Report.

The EDEN project is an interdisciplinary effort conceived to address key issues that have hampered sound hazard and risk assessment for endocrine disrupting chemicals (EDCs) in the European Union. It has adopted an approach that fully integrates human, wildlife, exposures, mechanisms and low-dose/mixture evaluations. The project was structured into four interlocking themes focusing on EDC mixture exposures, mechanisms of action and novel endpoints, effects on male reproductive health and the evaluation of low-dose and mixture effects of EDCs. For the first time, the simultaneous occurrence of nearly 150 different EDCs in human and wildlife tissues was measured. These studies revealed that numerous EDCs occur together in humans, yet differences in the levels of individual EDCs in specimens from boys with cryptorchidism and from women suffering from breast cancer and their respective controls did not become apparent. It appears that the likelihood of developing any of the above conditions cannot be attributed to any individual chemical at relevant exposure levels. However, there are signs that simultaneous exposure to many different EDCs may play a cumulative role in these disease processes. This means that efforts to develop biomarkers of cumulative EDC exposure should be re-doubled. In contrast, symptoms of endocrine disruption in fish could be explained largely in terms of exposure to estrogenic chemicals, but the possible role of antiandrogenic chemicals in disrupting sexual development in fish requires urgent attention. Fish caught in certain Dutch rivers exceeded the EU permissible levels for polychlorinated dioxins and furans. Considerable progress has been made in establishing relevant modes of action of EDCs and in assessing new endpoints. The screening for EDCs, with its focus on steroid receptor interactions, has not kept up with the progress made in understanding rapid cellular signalling events that occur in the wake of receptor activation. In the interest of avoiding overlooking endocrine active agents it is necessary to expand screening tools to capture rapid signalling events. Substantial progress has been also achieved in characterising the role of the aromatase system in fish as a target of EDCs and the consequences of steroid synthesis disruption on sexual differentiation, reproduction as well as non-reproductive processes such as neurodifferentiation. Extensive investigations of the role of certain phthalates in disrupting male sexual development have revealed delays in germ cell differentiation and other molecular effects as key events underlying the induction of the testicular dysgenesis syndrome. The role of the InsL3 protein in promoting male sexual development proved to be more complex than thought previously. Although the development and validation of an assay for the measurement of InsL3 blood levels was successful, the differences in blood InsL3 levels in normal and cryptorchid boys were too small to exploit InsL3 as a biomarker indicative of disruption of testis descent. The hypothalamic pituitary unit proved to be exquisitely sensitive to the effects of several EDCs, and the effects may account for precocious sexual development observed after early EDC exposure. EDEN has advanced the study of endocrine disruption in fish with activities including the development of microarrays for assessing endocrine disruption in zebrafish and establishing sensitive screening tools for endocrine disruption in fish. The development of a transgenic fish model for the detection of EDC effects proved to be technically too demanding to be completed in time, but efforts continue to complete this project after conclusion of EDEN. An in vivo model in fish (the three-spined stickleback) for the detection of antiandrogenic EDC was developed as a complement to the Hershberger assay. Male reproductive health in Denmark and Finland showed a worrying declining trend. For the first time, it could be established that the same is true for young men in Germany. It is of concern that semen quality among young Germans is similar to the values found in young Danes, a group previously thought to show the lowest semen quality in Europe. Foetal exposure to smoking has been identified as one reason for these effects. Observations of a declining total natural conception rate among the young Danish cohorts imply that the current poor semen quality has an impact on the population fertility in the future – a situation which will be difficult to reverse in the short term. The current and projected widespread use of assisted reproductive technologies may be a sign of such an emerging public health problem which also adds to the load of medical costs in young population. It is of vital importance to continue surveillance of semen quality and all efforts should be made to identify the factors that may cause harm in order to prevent further deterioration. Extensive low-dose studies with EDCs have shown that the conventional estimation of no-observed-adverse-effect-levels (NOAEL), with their reliance on hypothesis testing methods is inadequate for capturing low-dose effects of EDCs. Whenever possible, regression-based approaches with benchmark dose limits should replace NOAEL as the basis for establishing acceptable human exposure levels. A framework was developed to combine the strengths of both methodologies by making considerations of statistical detection limits and statistical power the starting point of testing procedures. Implementation of this framework will require a significant change in toxicological testing practice. Determinants of additivity for EDC mixtures have been characterised and are now well understood for combinations of similarly acting EDCs. Experimental studies have produced evidence that EDCs of relatively low potency and at low exposure levels can still work together to produce significant combination effects when they are present in sufficient numbers. The perceived low potency of many EDCs alone is uninformative in anticipating possible risks stemming from these chemicals. Where EDCs act in concert with endogenous hormones, significant additional effects may result under certain circumstances. Uncertainty still exists in relation to the likelihood of synergistic mixture effects, and concerted efforts should be made to fill this gap. Another source of uncertainty that will hamper sound EDC mixture risk assessment is incomplete knowledge about the identity of EDCs, their exposure levels and number. This issue can only be resolved through the development of dedicated exposure assessment strategies that take account of cumulative exposures. Despite these uncertainties, knowledge about determinants and factors that govern the joint action of similarly acting EDCs is now sufficiently advanced to come to pragmatic risk assessment approaches that take mixture effects into consideration. A modus operandi for EDC mixtures was developed which includes the use of dose addition (including the toxic equivalency factor approach) to arrive at a “mixture no-observed-adverse-effect-level” (MNOAEL) for endpoints relevant to endocrine disruption. These are then combined with a safety factor to arrive at estimates of tolerable human exposure. “Data-poor” situations may require estimation of a crude MNOAEL by dividing individual NOAEL of certain prototype chemicals by the anticipated number of relevant similarly acting chemicals

Early enhancement of kindergarten children potentially at risk in learning school mathematics - Design and Findings of an intervention study

Peter-Koop A, Grüßing M. Early enhancement of kindergarten children potentially at risk in learning school mathematics - Design and Findings of an intervention study. In: Kortenkamp U, Brandt B, Benz C, Krummheuer G, Ladel S, Vogel R, eds. Early mathematics learning. Selected Papers of the POEM 2012 Conference. New York: Springer; 2014: 307-321

An Advanced Methodological Framework for the Identification of Priority Pollutants and Priority Mixtures of Pollutants in European Freshwaters

We present a proposal for an advanced methodological framework for identifying priority pollutants and priority mixtures of pollutants in European freshwaters. The proposal was developed by the EU project SOLUTIONS. It aims to tackle major shortcomings of current prioritisation procedures under the EU Water Framework Directive (WFD): (i) For most aquatic pollutants the high data demands for a conclusive risk assessment cannot be met. Significant risks from so-called emerging pollutants may remain undetected. The WFD does not include an effective mechanism to close such knowledge gaps. The introduction of a watch-list mechanism for up to 10 substances provided a minor improvement but no fundamental change to this situation. (ii) Individual pollutants are assessed as if they would occur in isolation, largely ignoring the fact that they are part of complex multi-constituent mixtures. Environmental quality standards that have been established for single priority pollutants may not be sufficiently protective against mixture effects. Regulatory approaches for effectively tackling the problem are missing. The advanced framework integrates all available lines of evidence (LOE) on significant risks. This includes evidence from (i) ecological monitoring (field observations on so-called biological quality elements), (ii) effect-based monitoring (in vitro or in vivo testing in the lab or onsite), (iii) chemical monitoring in combination with so-called component-based mixture risk assessment approaches, (iv) integrated modelling of co-exposure and resulting mixture risks. Where one or more lines of evidence identify groups of pollutants presenting a significant risk, these should be subject to prioritisation for risk reduction measures. Where appropriate, such groups may be reduced to few mixture components or even one single component which can be demonstrated to explain most of the overall risk, so-called drivers of mixture risks. Wherever conclusive evidence on significant risks and needs for risk reduction cannot be reached because all possible LOEs are somewhere blocked by significant data or knowledge gaps, mixture components of potential concern are not left unnoticed but they are prioritised for further research and testing. Some elements of the advanced methodological framework may be readily applicable under the existing WFD. Full implementation, however, requires changes in the legal text, as detailed in Brack et al. 2017 (Sci Total Environ 576:720-737)

Consensus on the key characteristics of endocrine-disrupting chemicals as a basis for hazard identification.

Endocrine-disrupting chemicals (EDCs) are exogenous chemicals that interfere with hormone action, thereby increasing the risk of adverse health outcomes, including cancer, reproductive impairment, cognitive deficits and obesity. A complex literature of mechanistic studies provides evidence on the hazards of EDC exposure, yet there is no widely accepted systematic method to integrate these data to help identify EDC hazards. Inspired by work to improve hazard identification of carcinogens using key characteristics (KCs), we have developed ten KCs of EDCs based on our knowledge of hormone actions and EDC effects. In this Expert Consensus Statement, we describe the logic by which these KCs are identified and the assays that could be used to assess several of these KCs. We reflect on how these ten KCs can be used to identify, organize and utilize mechanistic data when evaluating chemicals as EDCs, and we use diethylstilbestrol, bisphenol A and perchlorate as examples to illustrate this approach

Consensus on the key characteristics of endocrine-disrupting chemicals as a basis for hazard identification.

Endocrine-disrupting chemicals (EDCs) are exogenous chemicals that interfere with hormone action, thereby increasing the risk of adverse health outcomes, including cancer, reproductive impairment, cognitive deficits and obesity. A complex literature of mechanistic studies provides evidence on the hazards of EDC exposure, yet there is no widely accepted systematic method to integrate these data to help identify EDC hazards. Inspired by work to improve hazard identification of carcinogens using key characteristics (KCs), we have developed ten KCs of EDCs based on our knowledge of hormone actions and EDC effects. In this Expert Consensus Statement, we describe the logic by which these KCs are identified and the assays that could be used to assess several of these KCs. We reflect on how these ten KCs can be used to identify, organize and utilize mechanistic data when evaluating chemicals as EDCs, and we use diethylstilbestrol, bisphenol A and perchlorate as examples to illustrate this approach

Strengthen the European collaborative environmental research to meet European policy goals for achieving a sustainable, non-toxic environment

International audienceTo meet the United Nations (UN) sustainable development goals and the European Union (EU) strategy for a non-toxic environment, water resources and ecosystems management require cost-efficient solutions for prevailing complex contamination and multiple stressor exposures. For the protection of water resources under global change conditions, specific research needs for prediction, monitoring, assessment and abatement of multiple stressors emerge with respect to maintaining human needs, biodiversity, and ecosystem services. Collaborative European research seems an ideal instrument to mobilize the required transdisciplinary scientific support and tackle the large-scale dimension and develop options required for implementation of European policies. Calls for research on minimizing society’s chemical footprints in the water–food–energy–security nexus are required. European research should be complemented with targeted national scientific funding to address specific transformation pathways and support the evaluation, demonstration and implementation of novel approaches on regional scales. The foreseeable pressure developments due to demographic, economic and climate changes require solution-oriented thinking, focusing on the assessment of sustainable abatement options and transformation pathways rather than on status evaluation. Stakeholder involvement is a key success factor in collaborative projects as it allows capturing added value, to address other levels of complexity, and find smarter solutions by synthesizing scientific evidence, integrating governance issues, and addressing transition pathways. This increases the chances of closing the value chain by implementing novel solutions. For the water quality topic, the interacting European collaborative projects SOLUTIONS, MARS and GLOBAQUA and the NORMAN network provide best practice examples for successful applied collaborative research including multi-stakeholder involvement. They provided innovative conceptual, modelling and instrumental options for future monitoring and management of chemical mixtures and multiple stressors in European water resources. Advancement of EU water framework directive-related policies has therefore become an option