Pulmonary Toxicity of Single-Wall Carbon Nanotubes in Mice 7

1,13

MB

and 90 Days after Intratracheal Instillation

21

stron

6326

ID

National Aeronautics and Space Administration

2003

rok

ABSTRACT

Nanomaterials are part of an industrial revolution to develop lightweight, but strong materials for a

variety of purposes. Single-wall carbon nanotubes are an important member of this class of

materials. They structurally resemble rolled-up graphite sheets, usually with one end capped;

individually they are about 1 nm in diameter and several microns long, but they often pack tightly

together to form rods or ropes. Carbon nanotubes possess unique electrical, mechanical, and

thermal properties and have many potential applications in the electronics, computer, and

aerospace industries. Unprocessed nanotubes are very light and could become airborne and

potentially reach the lungs. Because the toxicity of nanotubes in the lung is not known, their

pulmonary toxicity was investigated. The three products studied were made by different methods,

and contained different types and amounts of residual catalytic metals. Mice were each

intratracheally instilled with 0, 0.1, or 0.5 mg of carbon nanotubes, a carbon black negative control,

or a quartz positive control, and euthanized 7 d or 90 d after the single treatment for

histopathological study of the lungs. All nanotube products induced dose-dependent epithelioid

granulomas, and in some cases interstitial inflammation in the animals of the 7-d groups. These

lesions persisted and were more pronounced in the 90-d groups; the lungs of some animals also

revealed peribronchial inflammation and necrosis that had extended into the alveolar septa. The

lungs of mice treated with carbon black were normal, whereas those treated with high-dose quartz

revealed mild to moderate inflammation. These results show that, for the test conditions described

here and on an equal-weight basis, if carbon nanotubes reach the lungs, they are much more toxic

than carbon black and can be more toxic than quartz, which is considered a serious occupational

health hazard in chronic inhalation exposures.