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/m(3) 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.

Multi‐walled carbon nanotubes translocate into the pleural cavity and induce visceral mesothelial proliferation in rats

“…Intrapulmonary spraying has been shown to be an efficient method to deliver particle materials deep into the lung. (20)(21)(22)(23)(24) Our results demonstrated that MWCNT, like asbestos, translocated from the lung into the pleural cavity and induced inflammatory responses in the pleural cavity and, importantly, hyperplastic visceral mesothelial proliferation. These findings are important in understanding whether MWCNT have the potential to cause asbestos-like pleural lesions.…”

Long‐term retention of pristine multi‐walled carbon nanotubes in rat lungs after intratracheal instillation

“…To prepare a stable suspension, MWCNTs, which were synthesized using a floating catalyst method (Nikkiso Co. Ltd., Japan), were sonicated (180W) for 30 min in an aqueous solution of 0.5 mg ml −1 polyoxyethylene octyl phenyl ether (Triton‐X, Wako Pure Chemical Industries Co. Ltd., Osaka, Japan) using an ultrasonic bath (5510‐MT; Branson Ultrasonics Co., Danbury, CT, USA) according to previously described methods (Kobayashi et al ., 2010; Chen et al ., 2011; Morimoto et al ., 2012). …”

In vivo Toxicity Studies of Pristine Carbon Nanotubes: A Review

“…intratracheal instillation or inhalation) and dose, produce pulmonary lesions (Morimoto et al, 2011). The MWNTs that were used in this study were ground in a fructose mold -the fructose was rinsed afterwards with water and hydrogen peroxide.…”

“…The MWNTs that were used in this study were ground in a fructose mold -the fructose was rinsed afterwards with water and hydrogen peroxide. According to the authors this process slightly oxidized the tubes, which were subsequently dispersed in a 0.05% Triton X-100 solution (Morimoto et al, 2011). Triton X-100 is often used in cell biology to digest the cell membrane and cytoplasm to access the cell nucleus (http://fr.wikipedia.org/wiki/Triton_X-100).…”

“…While only a transient infiltration of inflammatory cells was observed for 0.2 mg treated animals, the high dose caused small granulomatous lesions and transient collagen depositions. In parallel, the authors conducted an inhalation study of dispersed MWNTs in a daily average mass of 0.37 ± 0.18 mg/m 3 (Morimoto et al, 2011). The rats were exposed to aerosol particles for 6h per day, 5 days a week for 4 weeks.…”