Assessing the toxicity of safer by design CuO surface-modifications using terrestrial multispecies assays

Safer by design (SBD) modifications of nanomaterials (NMs) have been pursued, aiming to maintain functionality and yet reduce hazard and support sustainable nanotechnology. The present case study involves copper oxide nanomaterials (CuO NMs) used in paint that have been surface modified by a SBD approach to particles coated with citrate (CIT-), ascorbate (ASC-), polyethylenimine (PEI+), and polyvinylpyrrolidone (PVP). We assessed the effect of the 4 different surface modified (CIT, ASC, PVP and PEI) NMs plus the pristine non-coated (PRI NM) and a Cu salt (CuCl2), using the soil multispecies test system (samples at 28-56-84 days). Further, the species were tested individually, and Cu was measured in the test media (soil and soil solution) and organisms. There was a potential relationship with zeta potential, and toxicity of CuO NMs was as follows: -PEI (+28 mV) caused the least impact, -ASC and -CIT (-17 mV, -18 mV) the most, while PVP and PRI (-8 mV, -9 mV) caused an intermediate response. Differences were not explained by the contribution of soluble Cu. Coating interfered with the release of Cu2+ and/or the activation of copper regulators and detoxification mechanisms in the organisms, i.e. time to reach some kind of stability in organisms' uptake was shorter for -ASC and longer for -PVP during prolonged time. Thus, one of the main findings is that NMs hazard assessment requires long term testing to understand predicted effects across materials. Further, the coverage using a multispecies approach offers increased relevance and a more ecosystem qualified response.publishe

Confirmatory assays for transient changes of omics in soil invertebrates - copper materials in a multigenerational exposure

Environmental risk assessment (ERA) based on effects caused by chronic and longer term exposure is highly relevant. Further, if mechanistic based approaches (e.g. omics) can be included, beyond apical endpoints (e.g. reproduction), the prediction of effects increases. For Cu NMs (and CuCl2) this has been studied in detail, covering multi-omics and apical effects using the soil standard species Enchytraeus crypticus. The intermediate level effects like cell/tissue and organ alterations represent a missing link. In the present study we aimed to: 1) perform long term exposure to Cu materials (full life cycle and multigeneration, 46 and 224 days) to collect samples; 2) perform histology and immunohistochemistry on collected samples at 12 time points and 17 treatments; 3) integrate all levels of biological organization onto an adverse outcome pathway (AOP) framework. CuO NMs and CuCl2 caused both similar and different stress response, either at molecular initiating events (MIE) or key events (KEs) of higher level of biological organization. Cell/Tissue and organ level, post-transcriptional and transcriptional mechanisms, through histone modifications and microRNA related protein, were similarly affected. While both Cu forms affected the Notch signalling pathway, CuCl2 also caused oxidative stress. Different mechanisms of DNA methylation (epigenetics) were activated by CuO NMs and CuCl2 at the MIE.publishe

Machine learning and materials modelling interpretation of in vivo toxicological response to TiO2 nanoparticles library (UV and non-UV exposure)

Assessing the risks of nanomaterials/nanoparticles (NMs/NPs) under various environmental conditions requires a more systematic approach, including the comparison of effects across many NMs with identified different but related characters/descriptors. Hence, there is an urgent need to provide coherent (eco)toxicological datasets containing comprehensive toxicity information relating to a diverse spectra of NPs characters. These datasets are test benches for developing holistic methodologies with broader applicability. In the present study we assessed the effects of a custom design Fe-doped TiO2 NPs library, using the soil invertebrate Enchytraeus crypticus (Oligochaeta), via a 5-day pulse via aqueous exposure followed by a 21-days recovery period in soil (survival, reproduction assessment). Obviously, when testing TiO2, realistic conditions should include UV exposure. The 11 Fe-TiO2 library contains NPs of size range between 5-27 nm with varying þ (enabling the photoactivation of TiO2 at energy wavelengths in the visible-light range). The NPs were each described by 122 descriptors, being a mixture of measured and atomistic model descriptors. The data were explored using single and univariate statistical methods, combined with machine learning and multiscale modelling techniques. An iterative pruning process was adopted for identifying automatically the most significant descriptors. TiO2 NPs toxicity decreased when combined with UV. Notably, the short-term water exposure induced lasting biological responses even after longer-term recovery in clean exposure. The correspondence with Fe-content correlated with the band-gap hence the reduction of UV oxidative stress. The inclusion of both measured and modelled materials data benefitted the explanation of the results, when combined with machine learning

Systems toxicology to advance human and environmental hazard assessment : A roadmap for advanced materials

Ideally, a Systems Toxicology (ST) approach is aimed at by (eco)toxicologists, i.e. a multidisciplinary area incorporating classical toxicological concepts with omics technologies, and the understanding of this through computational data sciences, chemistry, mathematics, and physics modelling. As outlined in sev-eral public reports (e.g. from ECHA-European Chemical Agency and EFSA-European Food Safety Authority), the way forward in the coming years in Europe is to integrate New Approach Methodologies (NAMs) (in-cluding omics technologies) into hazard and hence risk assessment (RA). Adverse Outcome Pathways (AOPs) describe a sequence of events in response to stress, from the molecular initiating event until an adverse outcome, which is relevant to RA or regulatory decision-making. AOPs are one of the facilitators to integrate mechanistic data into RA, but it is urgent to increase the inclusion of the vast mechanistic knowledge available, especially for the RA of novel smart and advanced materials (AdMa) with multi-functional characteristics. There are still many challenges to the routine usage of NAMs, e.g. omics-based information. Here, we summarise the current state of the art of ST, the benefits of human and environ-mental health cross knowledge and the available methods and output. The importance of this area has been highlighted for many years but is even more pressing in the context of AdMa. Furthermore, we outline the challenges and suggest recommendations for future implementation.(c) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Regulatory ecotoxicity testing of nanomaterials – proposed modifications of OECD test guidelines based on laboratory experience with silver and titanium dioxide nanoparticles

Conservation Biolog

Concern-driven integrated approaches to nanomaterial testing and assessment - report of the NanoSafety Cluster Working Group

Abstract Bringing together topic-related European Union (EU)-funded projects, the so-called "NanoSafety Cluster" aims at identifying key areas for further research on risk assessment procedures for nanomaterials (NM). The outcome of NanoSafety Cluster Working Group 10, this commentary presents a vision for concern-driven integrated approaches for the (eco-)toxicological testing and assessment (IATA) of NM. Such approaches should start out by determining concerns, i.e., specific information needs for a given NM based on realistic exposure scenarios. Recognised concerns can be addressed in a set of tiers using standardised protocols for NM preparation and testing. Tier 1 includes determining physico-chemical properties, non-testing (e.g., structure-activity relationships) and evaluating existing data. In tier 2, a limited set of in vitro and in vivo tests are performed that can either indicate that the risk of the specific concern is sufficiently known or indicate the need for further testing, including details for such testing. Ecotoxicological testing begins with representative test organisms followed by complex test systems. After each tier, it is evaluated whether the information gained permits assessing the safety of the NM so that further testing can be waived. By effectively exploiting all available information, IATA allow accelerating the risk assessment process and reducing testing costs and animal use (in line with the 3Rs principle implemented in EU Directive 2010/63/EU). Combining material properties, exposure, biokinetics and hazard data, information gained with IATA can be used to recognise groups of NM based upon similar modes of action. Grouping of substances in return should form integral part of the IATA themselves

ITS-NANO - Prioritising nanosafety research to develop a stakeholder driven intelligent testing strategy

Background To assess the risk of all nanomaterials (NMs) on a case-by-case basis is challenging in terms of financial, ethical and time resources. Instead a more intelligent approach to knowledge gain and risk assessment is required. Methods A framework of future research priorities was developed from the accorded opinion of experts covering all major stake holder groups (government, industry, academia, funders and NGOs). It recognises and stresses the major topics of physicochemical characterisation, exposure identification, hazard identification and modelling approaches as key components of the current and future risk assessment of NMs. Results The framework for future research has been developed from the opinions of over 80 stakeholders, that describes the research priorities for effective development of an intelligent testing strategy (ITS) to allow risk evaluation of NMs. In this context, an ITS is a process that allows the risks of NMs to be assessed accurately, effectively and efficiently, thereby reducing the need to test NMs on a case-by-case basis. For each of the major topics of physicochemical characterisation, exposure identification, hazard identification and modelling, key-priority research areas are described via a series of stepping stones, or hexagon diagrams structured into a time perspective. Importantly, this framework is flexible, allowing individual stakeholders to identify where their own activities and expertise are positioned within the prioritisation pathway and furthermore to identify how they can effectively contribute and structure their work accordingly. In other words, the prioritisation hexagon diagrams provide a tool that individual stakeholders can adapt to meet their own particular needs and to deliver an ITS for NMs risk assessment. Such an approach would, over time, reduce the need for testing by increasing the reliability and sophistication of in silico approaches. The manuscript includes an appraisal of how this framework relates to the current risk assessment approaches and how future risk assessment could adapt to accommodate these new approaches. A full report is available in electronic format (pdf) at http://www.nano.hw.ac.uk/research-projects/itsnano.html webcite. Conclusion ITS-NANO has delivered a detailed, stakeholder driven and flexible research prioritisation (or strategy) tool, which identifies specific research needs, suggests connections between areas, and frames this in a time-perspective