Suchergebnisse

In the European Union an environmental risk assessment is required for the registration of new chemicals, biocides, pesticides and pharmaceuticals. In order to avoid the release of potential hazardous substances, various ecotoxicity tests are performed, including acute and chronic fish tests. As a consequence of the new program of the European Union "Registration, Evaluation and Authorisation of Chemicals" (REACH) the number of animal experiments for environmental risk assessment is expected to increase remarkably within the next years. On the other hand there is a strong societal demand for reducing the number of animal tests by using alternative in vitro models. According to EU directives, investigations using non-human vertebrate embryos are considered pain free in vitro methods and are therefore accepted as alternatives to animal experiments. For the acute fish test, the Danio rerio embryo test (DarT) has been established as a replacement method and included in national regulations at least for waste water (German Waste Water Dues Law). However, no alternatives for chronic fish tests are currently available. The overall goal of this thesis was to work towards such a replacement by extending DarT zu Gene-DarT. Toxicants will initially interact at the molecular level with consequences for physiology, fitness and survival. The analysis of gene expression patterns may unravel elements of these molecular events before any phenotypic changes are visible. The hypothesis of this thesis therefore was that chemical-sensitive genes in embryos exposed in a conventional DarT may indicate toxic impact of substances at sub-acute concentrations and thus enhance the sensitivity of the embryo toxicity test. Furthermore, unlike the conventional DarT-endpoints, gene expression analysis will provide insights into mechanistic processes underlying toxicity. The 3,4-dichloroaniline (3,4-DCA), which is used as a reference compound in the DarT, was selected as model chemical in this thesis. In a first step, differentially expressed genes in embryos exposed to 3,4-DCA were identified by microarray technology and RT-PCR techniques. Six dose-dependent significant differentially expressed genes were identified. These genes were involved in biotransformation pathways (cyp1a, ahr2), stress response (nrf2, maft, ho-1) and cell cycle control (fzr1). Differential expression upon 3,4-DCA exposure was detected below the LOEC (lowest observed effect concentration = 6.2 µM) of survival or developmental disorders of the embryo test (0.78 µM and above). For the validation of stage specific sensitivity, genes were also analysed in post-hatched stages. Extension of exposure to post-hatched stages resulted in a differential expression at lower concentrations as for the embryonic stages, indicating an improved sensitivity due to stage-specific sensitivity or exposure time. To confirm the adaptive function of the 3,4-DCA-sensitive genes, embryonic mRNA abundance was experimentally manipulated by knock down and overexpression. By injection of sense (mRNA) or antisense (siRNA) RNA in one-cell-stages of embryos, the transcript levels of genes were transiently enhanced or repressed in embryos exposed to 3,4-DCA. mRNA injection of the genes cyp1a, ho-1 and nrf2 reduced the number of embryos with 3,4-DCA-induced malformations. In contrast, siRNA injections for the same genes led to an increase in the severity and frequency of developmental disorders. The results clearly indicate the adaptive functions of the investigated genes or their corresponding proteins. This study demonstrates that the analysis of chemical-sensitive gene expression shows the potential to increase the sensitivity of conventional toxicity tests. The analysis of gene expression also provides additional mechanistic information for toxic action, e.g. in the presented study, the involvement of Ah-receptor regulated pathways as an adaptive response. Furthermore, the presented data indicate that functional manipulations, using mRNA and siRNA-injection, are suitable to evaluate the role of differentially expressed genes for toxicity.

In this report the background, course and content of the development of an OECD Guidance Document (GD) for the testing of dissolution and dispersion stability of nanomaterials in the environment and the use of data on these endpoints for further environmental testing and assessment strategies is presented. The dissolution (rate) and dispersion stability of nanomaterials are considered as main drivers determining environmental fate and behavior in the environment. There is already an OECD Test Guideline (TG) 318 on dispersion stability of nanomaterials in the environment, and an OECD TG on dissolution (rate) of nanomaterials in the environment is still under development. As no specific OECD TG for dissolution for nanomaterials is available, the GD integrates methods meaningful for nanomaterials present from science or available by OECD TG/GDs. Also regards to TG318 for dispersion stability, more information on data presentation and interpretation is added to the GD. Furthermore, important interim guidance on testing heteroagglomeration of nanomaterials in the environment is given. The report also presents the importance of this GD for environmental assessment of nanomaterials as well as gives an insight into the regulatory implications it may have in future. The final GD was adopted by OECD Working Group of National Co-ordinators of the OECD Test Guidelines Programme (WNT) in April 2020 and can be found at the webpages of the OECD Test Guideline Programme upon publication.

This report summarizes the contents and outcomes of the Scientific Stakeholder Meeting on Nanomaterials in the Environment which took place on the 10th and 11th October 2017 at the headquarters of the German Environment Agency (UBA) in Dessau-Rosslau, Germany. The meeting was hosted by UBA and financed by the German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety. The meeting focused on regulatory relevant results of German and European research projects on nanomaterials in the environment which are carried out or finalised in the current years. By this, it gave a forum to present the state of the knowledge on environmental nanosafety in a regulatory context as well as to discuss the scientific results and their regulatory relevance between affected stakeholders. Therefore, the meeting particularly addressed representatives of science, industry, risk assessors, regulatory experts, and NGOs. It included key note talks, invited platform presentations as well as poster presentations. A Knowledge Café provided the opportunity to discuss selected topics with regard to environmental safety of nanomaterials in smaller groups. The meeting was closed with a discussion on the lessons learned highlighting the outcomes of the meeting by the views of different stakeholders.

The project "Thematic Conferences on Advanced Materials" aimed at supporting the German Authorities in structuring the field of advanced materials and identifying work priorities related to chemical safety. In the first part of the project, information on advanced materials was gathered via an extensive literature review, an online expert survey and expert interviews. In a second part, three international conferences were organised, of which one was separated into two online events, to invite stakeholders in the field to reflect on the research outcomes and involve in a discussion about chemical safety of advanced materials. Overall, the project initiated discussions about advanced materials at global, EU and national level and promoted an active reflection on the potential safety challenges and sustainability, amongst others due to lack of data, methods and coverage of advanced materials in current regulation. The report provides an overview of the work process and summarises the main discussion issues at the conferences.

Increasing amounts of MNMs are produced for industrial purpose and released to the environment by their usage or disposal of the products. Due to the high production volume MNMs are subject to PBT-assessment to estimate their potential environmental impact. The classical method to elucidate the bioaccumulation potential of chemicals is the flow-through approach with fish according to OECD TG 305 providing a BCF estimate. However, most MNMs tend to sediment in the aquatic environment and are thus difficult to be tested following the established test concept where constant and continous exposure conditions need to be achieved. The freshwater filter feeding bivalve Corbicula fluminea has previously shown to ingest and accumulate MNMs present in the water phase. To investigate the suitability of C. fluminea as test organism for bioaccumulation studies we developed a new flow-through system to expose the mussels under constant expsosure conditions. Different MNMs, each having different characteristics, were applied to determine their bioaccumulation potential. The silver nanoparticle NM 300K (Ag NP) was tested as a well dispersable and ion releasing MNM. In addition, C. fluminea was exposed to AgNO3 as a source of dissolved Ag+ to compare the bioaccumulation of Ag from dissolved and nanoparticulate sources. The titanium dioxide NP NM 105 was used for testing a non ion releasing MNM and the polystyrene nanoparticle (nPS) Fluoro-Max™, containing a fluorescence dye, was tested representing MNMs that are based on organic polymers. The uptake and distribution of nPS in the mussel soft tissue were observed using a fluorescence microscope. Following exposure to metal and metal oxides we were able to determine BAFss and BCFss values. BAFss values of 31 and 128 for two NM 300K concentrations (0.624 and 6.177 μg Ag/L) and of 6,150 and 9,022 for two NM 105 concentrations (0.099 and 0.589 μg TiO2/L) showed that the BAFss depends on the exposure concentration. Also for AgNO3, concentration depending BCFss of 31 and 711 were estimated for the higher and lower concentration, respectively. The analysis of metals in the soft tissue of previously exposed mussels and the resulting compartment specific distribution factors provide clear indications, that the uptake of NPs was mainly driven by the simple ingestion of NPs rather than the accumulation of dissolved ions. This was supported by the measurement of particle concentrations in mussel tissue using single particle ICP-MS.

Advanced materials promise technical solutions to support sustainable transformation. They play an important role for a variety of environmental topics worked on at ⁠UBA⁠, such as energy transition, circular economy and chemical safety. Various sectors can benefit from the use of advanced materials, but they can also face challenges. The UBA position paper describes the area of tension between the promising use and possible challenges for environmental and health protection and other sustainability dimensions, illustrates this with various examples and derives corner stones for a safe and sustainable life cycle of advanced materials.

Neuartige Materialen versprechen technische Lösungen zur Unterstützung der nachhaltigen Transformation. Sie spielen eine wichtige Rolle für eine Vielzahl der am ⁠UBA⁠ bearbeiteten Umweltthemen wie beispielsweise die Energiewende, Kreislaufwirtschaft und Chemikaliensicherheit. Dabei können die verschiedenen Bereiche durch den Einsatz neuartiger Materialien profitieren, aber auch vor Herausforderungen gestellt werden. Das UBA-Positionspapier beschreibt das Spannungsfeld zwischen dem vielversprechenden Einsatz und möglichen Herausforderungen für den Umwelt- und Gesundheitsschutz und anderen Nachhaltigkeitsdimensionen, verdeutlicht dies an verschiedenen Beispielen und leitet Eckpunkte für ein sicheren und nachhaltigen Lebenszyklus von neuartigen Materialien ab.

Im Rahmen des Forschungsprojekts wurde eine neue OECD-Prüfrichtlinie (TG) für die Bestimmung von Partikelgrößen und Partikelgrößenverteilungen von Nanomaterialien entwickelt, da die existierende OECD TG 110 zur Bestimmung von Partikelgrößen in Bezug auf den anwendbaren Größenbereich und die gegebenen Methoden veraltet ist bzw. den Nanometerbereich < 200 nm nicht abdeckt. Mit ihrem Anwendungsbereich von 1 bis 1000 nm deckt die neue Prüfrichtlinie (TG PSD) die gesamte Nanoskala ab. Die TG PSD ist für partikel- und faserförmige Nanomaterialien anwendbar. Durch die, in der TG PSD vorgeschriebene, paarweise Messung von Faserdurchmesser und -länge ermöglicht diese TG zum ersten Mal Fasern hinsichtlich ihrer größenabhängigen Gefahrstoffeigenschaften zu unterscheiden. Die Messanweisungen aller enthaltenen Methoden wurden im Rahmen von zwei getrennten Ringversuchen validiert, da bei der Anwendung der Methoden eine Unterscheidung zwischen Partikeln und Fasern gemacht werden muss. Neben Angaben zum Inhalt und Struktur der TG PSD, befasst sich der vorliegende Abschlussbericht mit den wesentlichen Schritten, Überlegungen und organisatorischen Aspekten bei der Entwicklung der Prüfrichtlinie. Darüber hinaus werden Einblicke in die Auswahl, Vorbereitung und Prävalidierung der im Ringversuch verwendeten Testmaterialien gegeben. Schließlich werden die wichtigsten Ergebnisse aus den Ringversuchen und ihre Auswirkungen auf die TG PSD vorgestellt.

The project activities described in this report comprise a literature review, expert interviews, an online survey, desk research on relevance criteria and the organisation of the first of three thematic conferences that will take place in the context of this project. Based on the gathered information and experiences, advanced materials were clustered into different groups. Each group was characterised in form of factsheets. At the first conference, clustering approaches were discussed as well as the need to "define" advanced materials and aspects of including safety considerations into material design. A number of advanced material types were identified that could be of relevance with regard to chemical safety. This could, for example, be due to indications of hazards and risks that might require adequate risk management or due to insufficient regulatory coverage or missing risk assessment methods and tools. This report summarises the results of the project's first work package. It is discussion input to two further thematic conferences of the project as well as to discussions on approaches to cluster, describe and prioritize advanced materials in other contexts.