How to categorise nanomaterials for effective hazard and risk assessment
Nanotechnologies and MNMs are often seen as revolutionary, with various applications in medicine, transportation, energy, food safety, security, ICT and environmental science. Thanks to enhanced properties like greater strength, lighter weight, increased electrical conductivity and chemical reactivity, MNMs are increasingly used in a variety of products, including mobile phones, computer chips, batteries, cosmetics, paints and sportswear. Despite their advantages, MNMs also pose new challenges in health and environmental safety. Organisms could be exposed to nanomaterials (NMs) through the lungs, making their risk assessment crucial. In the rapidly changing landscape of MNMs, regulatory systems need to be robust enough to cope with diversifying materials over time, where safe-by-design (SbD) principles could be useful. The EU-funded NanoREG II project has made great strides in addressing this issue and created principles to support the modification of existing nanosafety regulations. It has developed a more efficient risk assessment process through grouping and testing strategies integrating the SbD concept that includes three pillars: safe design, safe production and safe use. “It is virtually impossible to test the theoretically unlimited number of NM variants with respect to all relevant toxicological endpoints. Therefore, the development of NM grouping approaches for a more efficient assessment is indispensable,” noted a team of scientists, including researchers from project partner German Federal Institute for Risk Assessment, who recently published a study in the journal ‘Particle and Fibre Toxicology’.
NM grouping
In the same journal article, the researchers argue that NM grouping is more difficult than that of conventional chemicals. “A chemical category comprises a group of chemicals whose physico-chemical and (eco-) toxicological and/or environmental fate properties are likely to be similar or follow a regular pattern as a result of structural similarity,” they say. “Grouping of NMs is much more challenging as for instance demonstrating structural similarity requires more parameters. Moreover, several NM physico-chemical properties change during the life cycle due to agglomeration, dissolution, aging or interactions with biomolecules.” According to the researchers, “scientifically sound NM grouping approaches should consider NM MoA [mode of action],” where integrated multi-omics approaches could be beneficial. In the study, the researchers have identified NMs with similar MoAs using a multi-omics approach. Omics refer to technologies that measure some characteristic of a large family of cellular molecules such as genes, proteins or small metabolites. “Proteomics is the method of choice for the analysis of changes at the protein level,” the study says. “Metabolomics is the omics method closest to the phenotype of a biological system. Despite this, the use of metabolomics in nanotoxicology is relatively scarce,” it adds. “While one omics method alone conveys a single section of the state of the cell or tissue, a combination of these techniques leads to a more global overview of cellular responses. Therefore, integration of results across multiple cellular response layers from various omics approaches results in higher confidence and allows for unravelling NM MoAs, establishing toxicity pathways and identifying key events.” The multi-omics study involved 12 industrially relevant NMs, including silica and titanium dioxide. The team also used a rat cell model “to compare the outcome of this study with available in vivo data obtained in rats.” The NanoREG II (Development and implementation of Grouping and Safe-by-Design approaches within regulatory frameworks) project ended in February 2019. For more information, please see: NanoREG II project website
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