Comparison of pulmonary responses to single-walled vs. multi-walled carbon nanotubes.
Toxicologist 2007 Mar; 96(1):8
Exposure of mice to purified single-walled carbon nanotubes (<0.25% iron) by pharyngeal aspiration resulted in a rapid but transient inflammatory response as well as an early onset and progressive fibrotic reaction. Labeling of single-walled carbon nanotubes with gold nanoparticles indicated that granulomas occurred at deposition sites of large agglomerates, while interstitial fibrosis was associated with deposition of more dispersed nanotube structures. Techniques were developed to improve the dispersion of single-walled nanotubes. Aspiration of this dispersed single- walled carbon nanotube sample resulted in greater interstitial fibrosis in the absence of granulomas. Aspiration of a dispersed preparation of gold-labeled singlewalled carbon nanotubes resulted in rapid movement of nanotube structures into the alveolar interstitium and measurable translocation to systemic organs. Mice are currently being exposed by pharyngeal aspiration to a dispersed preparation of purified multi-walled carbon nanotubes. Results of these studies will be compared to those of single-walled carbon nanotubes to evaluate the effect of nanotube dimension (diameter) on pulmonary response. Single-walled carbon nanotubes were also evaluated in vitro to determine their ability to generate reactive species and stimulate oxidant production from macrophages. In vitro assays were not very good predictors of the in vivo fibrogenic potential of single-walled carbon nanotubes. In conclusion, results indicate that it would be prudent to implement strategies to limit exposure to carbon nanotubes in the workplace.
Bronchial-asthma; Respiratory-system-disorders; Pulmonary-system-disorders; Metals; Aerosols; Metal-compounds; Metal-dusts; Metallic-dusts; Metallic-compounds; Respirable-dust; Particulate-dust; Nanotechnology
The Toxicologist. Society of Toxicology 46th Annual Meeting and ToxExpo, March 25-29, 2007, Charlotte, North Carolina