The SOLUTIONS project: challenges and responses for present and future emerging pollutants in land and water resources management

SOLUTIONS (2013 to 2018) is a European Union Seventh Framework Programme Project (EU-FP7). The project aims to deliver a conceptual framework to support the evidence-based development of environmental policies with regard to water quality. SOLUTIONS will develop the tools for the identification, prioritisation and assessment of those water contaminants that may pose a risk to ecosystems and human health. To this end, a new generation of chemical and effect-based monitoring tools is developed and integrated with a full set of exposure, effect and risk assessment models. SOLUTIONS attempts to address legacy, present and future contamination by integrating monitoring and modelling based approaches with scenarios on future developments in society, economy and technology and thus in contamination. The project follows a solutions-oriented approach by addressing major problems of water and chemicals management and by assessing abatement options. SOLUTIONS takes advantage of the access to the infrastructure necessary to investigate the large basins of the Danube and Rhine as well as relevant Mediterranean basins as case studies, and puts major efforts on stakeholder dialogue and support. Particularly, the EU Water Framework Directive (WFD) Common Implementation Strategy (CIS) working groups, International River Commissions, and water works associations are directly supported with consistent guidance for the early detection, identification, prioritisation, and abatement of chemicals in the water cycle. SOLUTIONS will give a specific emphasis on concepts and tools for the impact and risk assessment of complex mixtures of emerging pollutants, their metabolites and transformation products. Analytical and effect-based screening tools will be applied together with ecological assessment tools for the identification of toxicants and their impacts. The SOLUTIONS approach is expected to provide transparent and evidence-based candidates or River Basin Specific Pollutants in the case study basins and to assist future review of priority pollutants under the WFD as well as potential abatement options.

The Precision Toxicology Initiative

The goal of PrecisionTox is to overcome conceptual barriers to replacing traditional mammalian chemical safety testing by accelerating the discovery of evolutionarily conserved toxicity pathways that are shared by descent among humans and more distantly related animals. An international consortium is systematically testing the toxicological effects of a diverse set of chemicals on a suite of five model species comprising fruit flies, nematodes, water fleas, and embryos of clawed frogs and zebrafish along with human cell lines. Multiple forms of omics and comparative toxicology data are integrated to map the evolutionary origins of biomolecular interactions, which are predictive of adverse health effects, to major branches of the animal phylogeny. These conserved elements of adverse outcome pathways (AOPs) and their biomarkers are expect to provide mechanistic insight useful for regulating groups of chemicals based on their shared modes of action. PrecisionTox also aims to quantify risk variation within populations by recognizing susceptibility as a heritable trait that varies with genetic diversity. This initiative incorporates legal experts and collaborates with risk managers to address specific needs within European chemicals legislation, including the uptake of new approach methodologies (NAMs) for setting precise regulatory limits on toxic chemicals.

Xeredar: An open-source R-package for the statistical analysis of endocrine new approach methods (NAMs) using fish or amphibian eleutheroembryos

The experimental design of New Approach Methodologies (NAMs) might deviate from common ecotoxicological studies, often requiring tailored statistical approaches. For instance, in NAMs developed for the detection of endocrine activity using aquatic vertebrate eleutheroembryos (Xenopus Eleutheroembryonic Thyroid Assay (XETA), Rapid Androgen Disruption Activity Reporter (RADAR) assay and Rapid Estrogen Activity In Vivo (REACTIV) assay), all concentration groups are nested within three independent study repeats, named 'runs' in the relevant Test Guidelines. Here, runs are referred to as replicates to emphasize their role as the repeated, independent entity. By contrast, for most other ecotoxicological studies the replicates are nested in the concentration groups. This leads to a different dependency structure for the XETA, RADAR and REACTIV assays. Disregarding this violates the basic statistical requirement for independence of observations potentially leading to incorrect conclusions. Unfortunately, in the statistical sections of the Test Guidelines of the XETA, RADAR and REACTIV assay, it is not clearly recommended to regard this dependency structure as statistical recommendations using a mixed ANOVA are provided only in the annexes. Here, we present "xeredar", an open-source R-package allowing automated statistical analysis of XETA, RADAR and REACTIV assays where the dependency structure of the data is correctly regarded through a mixed ANOVA. xeredar was validated on 36 XETA ring test studies and further tested on 41 RADAR ring test studies. A power analysis was carried out for the REACTIV assay, demonstrating that ignoring the dependency structure potentially leads to lower power and an increased false positive rate in comparison to the mixed ANOVA approach. The open-source R-package "xeredar" also comes with a Shiny app, making it accessible to everyone and thereby enhancing standardization and reproducibility for the statistical analyses of XETA, RADAR, and REACTIV assays.

How the Xenopus eleutheroembryonic thyroid assay compares to the amphibian metamorphosis assay for detecting thyroid active chemicals

The Xenopus Eleutheroembryonic Thyroid Assay (XETA) was recently published as an OECD Test Guideline for detecting chemicals acting on the thyroid axis. However, the OECD validation did not cover all mechanisms that can potentially be detected by the XETA. This study was therefore initiated to investigate and consolidate the applicability domain of the XETA regarding the following mechanisms: thyroid hormone receptor (THR) agonism, sodium-iodide symporter (NIS) inhibition, thyroperoxidase (TPO) inhibition, deiodinase (DIO) inhibition, glucocorticoid receptor (GR) agonism, and uridine 5'-diphospho-glucuronosyltransferase (UDPGT) induction. In total, 22 chemicals identified as thyroid-active or -inactive in Amphibian Metamorphosis Assays (AMAs) were tested using the XETA OECD Test Guideline. The comparison showed that both assays are highly concordant in identifying chemicals with mechanisms of action related to THR agonism, DIO inhibition, and GR agonism. They also consistently identified the UDPGT inducers as thyroid inactive. NIS inhibition, investigated using sodium perchlorate, was not detected in the XETA. TPO inhibition requires further mechanistic investigations as the reference chemicals tested resulted in opposing response directions in the XETA and AMA. This study contributes refining the applicability domain of the XETA, thereby helping to clarify the conditions where it can be used as an ethical alternative to the AMA.