Nanoscale reference materials for environmental, health and safety measurements: needs, gaps, and opportunities.
Stefaniak-AB; Hackley-VA; Roebben-G; Ehara-K; Hankin-S; Postek-MT; Lynch-I; Fu-W-E; Linsinger-TPJ; Thunemann-AF
Nanotechnology 2013 Dec; 7(8):1325-1337
We critically reviewed published lists of nano-objects and their physico-chemical properties deemed important for risk assessment and discuss metrological challenges associated with the development of nanoscale reference materials (RMs). Five lists were identified that contained 25 (classes of) nano-objects; only four (gold, silicon dioxide, silver, titanium dioxide) appeared on all lists. Twenty three properties were identified for characterization; only (specific) surface area appeared on all lists. The key themes that emerged from our review were: 1) various groups have prioritized nano-objects for development as 'candidate RMs' with limited consensus; 2) a lack of harmonized terminology hinders accurate description of many nanoobject properties; 3) many properties identified for characterization are ill-defined or qualitative and hence are not metrologically traceable; 4) standardized protocols are critically needed for characterization of nano-objects as delivered in relevant media and as administered to toxicological models; 5) the measurement processes being used to characterize a nano-object must be understood because instruments may measure a given sample in a different way; 6) appropriate RMs should be used for both accurate instrument calibration and for more general testing purposes (e.g., protocol validation); 7) there is a need to clarify that where RMs are not available, if '(representative) test materials' that lack reference or certified values may be useful for toxicology testing; and, 8) there is a need for consensus building within the nanotechnology and environmental, health and safety communities to prioritize RM needs and better define the required properties and (physical or chemical) forms of the candidate materials.
Nanotechnology; Risk-factors; Silicates; Silicon-compounds; Particulate-dust; Particulates; Dusts; Dust-particles;
Author Keywords: Engineered nanomaterials; Nano-objects; Nanoparticles; Nanotechnology; Reference materials; Characterization; Physico-chemical properties; Exposure; Risk
Aleksandr B. Stefaniak, National Institute for Occupational Safety and Health, Morgantown, WV 26505
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