The goal of this project is to provide support of National Toxicology Program (NTP) hazard identification activities targeted toward the prevention of diseases or adverse effects caused by environmental exposure to nanomaterials. Toxicity testing is an important aspect of public health research in that it serves to identify chemicals that are hazardous to human health. Proper chemical analyses are required to ensure that, in toxicity studies, the test species are exposed to the prescribed chemicals at the specified dose concentrations. This contract contributes to the ability of toxicity studies to provide evidence of heightened cancer risk along with other toxicological outcomes, by providing characterization of the chemicals studied, confirmation of the dose levels administered, and internal dose determinations. This information is critical to evaluation of toxicity tests and development of sound, scientific conclusions about the potential toxicity of the study chemical in the test species and ultimately supports the risk assessment efforts of National Toxicology Program and other federal agencies. With internal dose information provided by this contract, extrapolations to humans can be made so that the public can be adequately informed about risk factors arising from exposure to studied chemicals. During FY09 more than 12 tasks were begun, performed, and/or completed in support of NTP and DIR Nanomaterials research and testing protocols. The chemistry support contractor procured and characterized 6 types of multiwalled carbon nanotubes (MWCNT) from different vendors, 24 samples in all. MWCNTs were characterized as to purity, diameter and length. Thermogravimetric analysis was used to assess purity of the materials, showing what percent of each material was amorphous carbon, and what percent was composed of carbon nanotubes. Each sample was also analyzed for metals content using inductively coupled plasma mass spectrometry (ICP-MS). Scanning Electron Microscopy (SEM) was used to determine the diameter of the each MWCNT sample, while Tunneling Electron Microscopy (TEM) was used to assess the length. One sample of each MWCNT type with the highest purity was selected for further testing.
