Elucidation of Structure-Activity Relationships in Inhalation Nanotoxicology
EMSL Project ID
42693
Abstract
Multiwalled Carbon Nanotubes (MWCNT) are of great commercial interest. However, with increasing applications and production capacities of MWCNT, they are coming under intense scrutiny by the government, industry and consumers due to the concerns about their safety and potential for human exposure. MWCNT toxicity testing requires extensive characterization of the material's properties--particle size, shape, form, purity, surface chemistry-- and accurate measurement of the doses to determine the safe exposure level. To measure dose and identify the characteristics of a nanomaterials during a safety study, samples must be taken in air or other media and analyzed both with real-time and post exposure techniques. Since the mass associated with MWCNT is very small, chemical characterization of the exposure atmosphere to ensure chemical purity of the exposed chemical is extremely challenging. EMSL houses unparalleled state-of-the-art capabilities including a wide variety of sophisticated electron microscopy instruments and spectrometers. These capabilities can help provide valuable information about the particle size, shape, elemental composition and structural properties. In this study, we plan to develop an inhalation exposure system to aerosolize and expose seven different types of MWCNT, spanning a range of various sizes, purities, metal catalyst composition, in a whole body exposure chamber. The exposure atmosphere will be characterized real time as well as samples collected on various media for additional analysis at EMSL including Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Photoelectron Microscopy (XPS). SEM and TEM will be used to characterize the relevant morphological features while XPS will be used to determine the degree of surface functionalization of the MWCNT, and to determine to what extent (if any) aerosolization causes oxidation of the surface of the MWCNT. Subsequent inhalation toxicological exposure studies will be conducted and the results of both these studies and the MWCNT characterization experiments will be synthesized, resulting in a data set that can be used to determine the relationships between MWCNT properties and toxicity. This data set can then be used to inform the ongoing discussion regarding the most appropriate regulatory framework to govern the industrial use of MWCNT.
Project Details
Start Date
2010-12-02
End Date
2011-12-04
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members