Published studies report that pulmonary exposure to single-walled carbon nanotubes (SWCNT) or multi-walled carbon nanotubes (MWCNT) causes transient inflammation, granulomatous legions, and persistent fibrosis. Due to the fibrous shape of carbon nanotubes (CNT), questions concerning asbestos-like induction of lung cancer and mesothelioma have also been raised. Therefore, hazard assessment for CNT is essential. There are at least three distinct synthesis processes for CNT. In addition, CNT can exist in the raw (catalytic metals present) or purified (metals removed) forms. Physical dimensions (both width and length) can vary among SWCNT and MWCNT. Furthermore, the degree of agglomeration of CNT can result in a wide range of structure sizes. Lastly, CNT can be functionalized in multiple ways, resulting in altered surface properties. Thus, hundreds of types of CNT are possible. Since it will not be feasible to evaluate the toxic potential of each CNT type, it is critical to determine the relationships between physicochemical characteristics of CNT and bioactivity. Development of such relationships requires the collaboration between material scientists and toxicologists. Such a matrix of physicochemical properties vs. bioactivity is critical for risk analysis. Existing data concerning the effects of metal contamination, dimension, and agglomeration state on the pulmonary reactions to CNT exposure will be presented. Another issue for risk assessment is the relevance of pulmonary responses after a bolus exposure to inhalation of CNT. In this presentation, pulmonary responses to bolus exposure (pharyngeal aspiration) will be compared to those after short term inhalation of SWCNT and MWCNT.
Airborne-particles; Air-contamination; Asbestos-fibers; Biological-effects; Carcinogenicity; Carcinogens; Cytotoxic-effects; Cytotoxicity; Fibrogenicity; Fibrosis; Health-hazards; Inhalation-studies; Lung-disorders; Lung-irritants; Microscopic-analysis; Nanotechnology; Physiological-effects; Pulmonary-cancer; Pulmonary-system; Pulmonary-system-disorders; Quantitative-analysis; Respiratory-hypersensitivity; Respiratory-irritants; Respiratory-system-disorders; Statistical-analysis; Toxic-effects; Toxic-materials
The Toxicologist. Society of Toxicology 50th Annual Meeting and ToxExpo, March 6-10, 2011, Washington, DC