Physicochemical Characterization of Engineered Nanoparticles: The measurands that influence Nano EHS

A. Hight-Walker
National Institute of Standards and Technology, US

Keywords: Standards, Nanoscale, Characterization

Summary:

There is general consensus that toxicology assessment of engineered nanoparticles (NPs) is hampered by a lack of reproducibility.  In general, there is a dearth of comparable and validated outcomes, even though substantial time and resources have been devoted to the cause. One reason is the lack of thorough characterization of the NPs under study, i.e. are we testing the same NP or not? As batch-to-batch and company-to-company variability is significant at the nanoscale, this question must be asked. This issue, combined with the recent nano definition adopted within the EU which cannot be realized with current metrology, has the focus once again on the measurement science community.  Work ongoing within the standards organization of ISO/TC 229-Nanotechnology strives to establish guidance on the physicochemical characterization necessary to forge a path towards validation.  This work is collaborative with many other groups that have also proposed a minimum set of measurements necessary, such as OECD and MinChar.  Through a consensus process, these parameters have been assigned measurands‹the quantity that is intended be measured‹to aid the toxicologists and ultimately reach comparability between studies. These measurands have also been assigned measurement methods and appropriate caveats to consider when working in the nano regime.  NIST is incorporating these terms, measurands and measurement method into our Nano EHS program and looking to establish metrological collaborations to reduce measurement uncertainty and increase comparability of toxicological studies in order to rigorously establish connections between physicochemical properties and toxicological response