Standardization of nanoecotoxicology to facilitate grouping strategies for engineered nanomaterials

Nanoecotoxicology hypothesizes that alterations to a nanoform's physical structure can influence ecotoxicology. Grouping and read-across approaches have been proposed to streamline hazard assessments and reduce the burden of regulatory approval. The NanoReg2 project investigated the capacity of historical ecotoxicity data to support read-across approaches and found that the data were insufficient and the information reported was inconsistent. To explore the potential for grouping in ecotoxicology, the NanoReg2 project created a harmonized ecotoxicological database using nanomaterials representative of those available on the European Single Market. Relationships between pristine physicochemical properties, system-dependent changes to physical structure, and ecotoxicological responses were explored using mixed modelling. The study also explored the application of the NanoGENOTOX SOP to ecotoxicology to investigate the application of bovine serum albumin to create stable stock suspensions. Results demonstrated that nanomaterials can be grouped based on their core element (carbon, silicon, titanium, and zinc) and that inherent properties (initial size, density, surface area, purity) could be correlated to biological responses. Results also demonstrated that the use of bovine serum albumin influences the ecotoxicological potential of the tested nanomaterials, which may be attributed to their stability in suspension. While results were promising, initial physicochemical properties are autocorrelated, which challenges discrimination between nanoforms. The NanoReg2 project identified two barriers to implementing grouping approaches: inconsistent test preparations and limited access to historical data. To address these issues, developing FAIR (Findable, Accessible, Interoperable, and Reusable) data is necessary to integrate ecotoxicology into regulatory paradigms.