Histopathological study of single-walled carbon nanotubes in mice 7 and 90 days after instillation into the lungs

IEC 23

Chiu-wing Lam1, John T. James2, Richard McCluskey2, and Robert L. Hunter3. (1) Toxicology Section, Wyle Laboratories, Johnson Space Center, SF 23, Houston, TX 77058, (2) Space and Life Sciences, National Aeronautics and Space Administration, Johnson Space Center, SF 23, Houston, TX 77058, (3) Dept. of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Fannin Street, Houston, 77030
Single-walled carbon nanotubes (CNT), a novel material that has wide industrial applications, are light and could become airborne. The toxicity of three CNT products made by different methods, and containing different types or amounts of residual catalytic metals (Fe and Ni) was investigated in mice by intratracheal instillation. Mice (4 to 5 per group)were each instilled once with a suspension containing 0, 0.1 or 0.5 mg of CNT or a reference dust (carbon black or quartz) and killed 7 or 90 days later for lung histopathological study. Carbon black elicited minimal effects and high-dose quartz produced mild/moderate inflammation in the lungs. All the CNT products induced a dose-dependent formation of epithelioid granulomas in the centrilobular alveolar septa and, in some cases, interstitial inflammation in the 90-d groups; the granulomas consisted of aggregates of macrophages laden with black CNT particles. Less severe lesions were also seen in mice held for only 7 days. Our results show that, for the test conditions described here, if CNT reach the lung, they can be more toxic than quartz. If airborne CNT dusts are present, respiratory protection should be used to minimize inhalation exposures.