AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
An Inhalation Toxicological Characterization of Nano CeO2 Using the Harvard VENGES Toxicological Platform
Georgios Pyrgiotakis, Samuel Gass, William Goldsmith, David Frazer, Jane Ma, Walter McKinney, Mark Barger, Bridget Dolash, Vincent Castranova, PHILIP DEMOKRITOU, Harvard University
Abstract Number: 584 Working Group: Health Related Aerosols
Abstract Ceria nanoparticles are increasingly used for a number of industrial and commercial applications including catalysts, chemical mechanical polishing, UV-shielding, and nanocomposites. As the number of consumers and factory workers exposed to CeO2 nanoparticles increases, the need for a comprehensive toxicological characterization is pressing. While most in-vitro models predict minimal toxicity for nanosized CeO2, preliminary in-vivo animal models using instillation of CeO2 nanoparticles point to fibrogenicity. However, to date, most evidence is limited to intratracheal instillation studies that may not represent real-world exposure scenarios. Here, we present the first ever whole-body systematic animal inhalation study of nano-CeO2. In addition, the use of a nanothin amorphous SiO2 coating as means of mitigating CeO2 toxicity was evaluated as a safer formulation concept. CeO2 (uncoated and SiO2-coated) nanoparticles were synthesized using the Harvard Versatile Engineered Nanomaterial Generating System (VENGES), which enables the synthesis and coating of industrially relevant nanoparticles in the aerosol phase with precise control over primary particle size, aggregation, and aerosol concentration. The generated aerosol was diluted and introduced into a customized exposure chamber. The generated CeO2 particles (SiO2 coated and uncoated) were characterized (1) in-situ with respect to aerosol size distribution and number concentration (SMPS), aggregate morphology (TEM, SEM), and charge and aerosol length (AED) and (2) ex-situ with respect to crystallinity and chemical composition (XRD, XPS, EDX), surface area (BET), and morphology (TEM, SEM). Exposure atmospheres in the chamber were monitored in real time and characterized with respect to number and size aerosol concentration (CPC, SMPS), mass concentration (Gravimetric Filter Measurements), Mass Size Distribution (MOUDI), temperature, humidity, CO, CO2, (Q-Track) and NOx concentrations. Sprague Dawley rats (n=12/group) were exposed to either coated or uncoated CeO2 (2.7 mg/m3, 2 h/day, 4 days). Exposed animals, along with particle free- controls, were sacrificed at either 1 or 84 days post exposure. Pathophysiological analysis was performed and inflammatory and cytotoxic biomarkers were measured in the bronchoalveolar lung lavage of the animals.