Characterization of Commercial Metal Oxide Nanomaterials: Crystalline Phase, Particle Size and Specific Surface Area
- DOI
- Language of the publication
- English
- Date
- 2020-09-11
- Type
- Article
- Author(s)
- Bushell, Michael
- Beauchemin, Suzanne
- Kunc, Filip
- Gardner, David
- Ovens, Jeffrey
- Toll, Floyd
- Kennedy, David
- Nguyen, Kathy
- Vladisavljevic, Djordje
- Rasmussen, Pat E.
- Johnston, Linda J.
- Publisher
- MDPI
Abstract
Physical chemical characterization of nanomaterials is critical to assessing quality control during production, evaluating the impact of material properties on human health and the environment, and developing regulatory frameworks for their use. We have investigated a set of 29 nanomaterials from four metal oxide families (aluminum, copper, titanium and zinc) with a focus on the measurands that are important for the basic characterization of dry nanomaterials and the determination of the dose metrics for nanotoxicology. These include crystalline phase and crystallite size, measured by powder X-ray diffraction, particle shape and size distributions from transmission electron microscopy, and specific surface area, measured by gas adsorption. The results are compared to the nominal data provided by the manufacturer, where available. While the crystalline phase data are generally reliable, data on minor components that may impact toxicity is often lacking. The crystal and particle size data highlight the issues in obtaining size measurements of materials with broad size distributions and significant levels of aggregation, and indicate that reliance on nominal values provided by the manufacturer is frequently inadequate for toxicological studies aimed at identifying differences between nanoforms. The data will be used for the development of models and strategies for grouping and read-across to support regulatory human health and environmental assessments of metal oxide nanomaterials.
Plain language summary
Health Canada is responsible for assessing and managing risks associated with engineered nanomaterials (materials in a size range of 1-100 nanometers). As part of their risk assessment activities, New Substances Assessment and Control Bureau (NSACB) purchased commercially available metal oxide nanopowders to characterize their physical-chemical and toxicological properties. EHSRB joined forces with the National Research Council to investigate a set of 29 metal oxide nanomaterials representing four metal oxides (aluminum, copper, titanium and zinc). Physical-chemical properties critical for assessing their impact on human health and the environment were characterized: particle size distribution, mineral form, surface area. Key findings are: (i) minor mineral phase generally not reported by the manufacturers were detected and (ii) the estimated particle size significantly differed from the manufacturers information in some cases and depended on the analytical approach selected for particle size determination. Considering that these basic properties influence the nanomaterial toxicity, the results highlight the importance of not relying solely on the manufacturer information for material characterization in toxicological studies. Data obtained will be useful to support regulatory human health and environmental assessments of the nanomaterials in Canada.
Subject
- Health,
- Health and safety