Adapting standard aquatic and sediment toxicity tests for use with manufactured nanomaterials: Key issues, expert consensus, and recommendations
Résumé
The unique properties of manufactured nanomaterials (MNs) suggest that their direct use or application in nano-enabled products will increase in the future. This will result in increased potential for human and environmental exposure to MNs during their manufacture, use, or disposal and suggests the need for MN-specific hazard and risk assessment approaches. Assessment of MN risk will require reliable, standardized hazard testing methods such as those provided by the Organization of Economic Cooperation and Development (OECD). However, guidance on how to design studies to address the many difficulties in testing MN, due to their particulate, fibrous, and colloidal properties, has yet to be developed. Here, we summarize findings from an expert workshop convened (as part of OECD's Working Party on Manufactured Nanomaterials ongoing activities) for the purpose of developing such a guidance document for aquatic and sediment testing. Workshop attendees (23 experts from 6 countries) identified critical components of test guidelines that will require additional or modified guidance. The discussion was based on attendees own research experience and on literature information elucidating the common issues related to material losses, dissolution, or modification in exposure systems and inconsistencies in testing practices. These include preparation of dispersions, exposure metrics, maintaining (and monitoring) consistent exposure levels, and reliable analytical and quantitative methods. In this presentation, we discuss these topics and identify where consensus was, and was not, achieved including the heavily-debated issues of use of dispersants, manipulation of media properties (e.g. ionic strength or composition), testing unstable materials, using a water accommodated fraction approach, and adhering to the 20% exposure fluctuation thresholds (or applying other, MN-specific thresholds) common to many test guidelines. Workshop attendees also identified specific information gaps that might be addressed in future research to facilitate development of testing guidance. In addition to addressing standardized testing, the workshop findings will also facilitate more consistent testing and reporting of results in more exploratory research.
Domaines
Ecotoxicologie
Origine : Fichiers produits par l'(les) auteur(s)
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