Pulmonary toxicity of well-dispersed multi-wall carbon nanotubes following inhalation and intratracheal instillation

Abstract

Multi-walled carbon nanotubes (MWCNTs), dispersed in suspensions consisting mainly of individual tubes, were used for intratracheal instillation and inhalation studies. Rats intratracheally received a dose of 0.2 mg, or 1 mg of MWCNTs and were sacrificed from 3 days to 6 months. MWCNTs induced a pulmonary inflammation, as evidenced by a transient neutrophil response in the low-dose groups, and presence of small granulomatous lesion and persistent neutrophil infiltration in the high-dose groups. In the inhalation study, rats were exposed to 0.37 mg/m³ aerosols of well-dispersed MWCNTs (>70% of MWCNTs were individual fibers) for 4 weeks, and were sacrificed at 3 days, 1 month, and 3 months after the end of exposure. The inhalation exposures delivered less amounts of MWCNTs into the lungs, and therefore less pulmonary inflammation responses was observed, as compared to intratracheal instillation. The results of our study show that well-dispersed MWCNT can produce pulmonary lesions, including inflammation.

Keywords::

• Nanomaterial
• carbon nanotube
• inhalation
• intratracheal instillation
• dispersion

Declaration of interest:

This research was funded by a grant from the New Energy and Industrial Technology Development Organization of Japan (NEDO) titled: “Evaluating risks associated with manufactured nanomaterials; Developing toxicity evaluating methods by inhalation exposure (P06041)”. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.