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Physicochemical comparison of commercially available metal oxide nanoparticles: implications for engineered nanoparticle toxicology and risk assessment
Citation:
DREHER, K. L., N. S. Mandzy, W. Peng, AND E. A. Grulke. Physicochemical comparison of commercially available metal oxide nanoparticles: implications for engineered nanoparticle toxicology and risk assessment. Presented at The Society of Environmental Toxicology and Chemistry (SETAC) Meeting, Portland, OR, November 07 - 11, 2010.
Impact/Purpose:
This study summarizes physicochemical property characterizations of several commercial samples of nanoscale ceria (Ce02) and titania (Ti02) to be employed in toxicology studies.
Description:
Accurate and affordable physicochemical characterization of commercial engineered nanomaterials is required for toxicology studies to ultimately determine nanomaterial: hazard identification; dose to response metric(s); and mechanism(s) of injury. A minimal physical and chemical data set that includes nanoparticle: purity, sizes, agglomeration properties, shapes\morphology, surface area, chemistries and reactivities is needed. There are now a wide variety and increasing number of commercial sources and manufacturers of nanoparticles. In general, the control of nanoparticles properties in manufacturing processes is quite difficult, because most manufacturers do not have simple bulk property measurements that will verify their product's morphology on the nanoscale. In addition, it is unclear how well noncommerical laboratory generated engineered nanomaterials accurately represent their counterparts produced at the commercial scale, a critical issue in assessing the health risk of commercial nanomaterials. This study summarizes physicochemical property characterizations of several commercial samples of nanoscale ceria (Ce02) and titania (Ti02) to be employed in toxicology studies. The set included samples with different sizes, lots, manufacturing methods, and sources. The material properties considered were qualitative elemental analysis, quantitative analysis, specific surface area/porosity, primary and aggregate size, crystal structure, elemental and organic carbon analysis, and particle shape and morphology. All samples were crystalline, so in general their purity was relatively high. Materials from different suppliers had different levels of trace contaminants, probably reflecting the different precursor materials and manufacturing processes. No sample had significant porosity on the micro-or mesoscales, but several measured parameters such as primay and aggregrate size, specific surface area and crystalline structure often did not match that reported by the manufacturer. Some of the samples had lot-to-lot variations in particle size, shape, and morphology. However, this sample set had little extraneous organic carbon, probably due to the high temperatures used for vapor phase syntheses. These data illustrate the importance of analyzing nanomaterial properties of the specific samples to be used for toxicology studies as well as statistical analyses to link nanoparticle properties to toxicity for hazard identification and dose metric correlation. (This abstract does not necessarily reflect EPA policy)