Inhalation Toxicity of Multiwall Carbon Nanotubes in Rats Exposed for 3 Months

Abstract

Carbon nanotubes (CNT) are of great commercial interest. Theoretically, during processing and handling of CNT and in abrasion processes on composites containing CNT, inhalable CNT particles might be set free. For hazard assessment, we performed a 90-day inhalation toxicity study with a multiwall CNT (MWCNT) material (Nanocyl NC 7000) according to Organisation for Economic Co-operation and Development test guideline 413. Wistar rats were head-nose exposed for 6 h/day, 5 days/week, 13 weeks, total 65 exposures, to MWCNT concentrations of 0 (control), 0.1, 0.5, or 2.5 mg/m(3). Highly respirable dust aerosols were produced with a proprietary brush generator which neither damaged the tube structure nor increased reactive oxygen species on the surface. Inhalation exposure to MWCNT produced no systemic toxicity. However, increased lung weights, pronounced multifocal granulomatous inflammation, diffuse histiocytic and neutrophilic inflammation, and intra-alveolar lipoproteinosis were observed in lung and lung-associated lymph nodes at 0.5 and 2.5 mg/m(3). These effects were accompanied by slight blood neutrophilia at 2.5 mg/m(3). Incidence and severity of the effects were concentration related. At 0.1 mg/m(3), there was still minimal granulomatous inflammation in the lung and in lung-associated lymph nodes; a no observed effect concentration was therefore not established in this study. The test substance has low dust-forming potential, as demonstrated by dustiness measurements, but nonetheless strict industrial hygiene measures must be taken during handling and processing. Toxicity and dustiness data such as these can be used to compare different MWCNT materials and to select the material with the lowest risk potential for a given application.

Cytotoxicity and genotoxicity of multi-walled carbon nanotubes with human ocular cells

“…They found that MWNT induced massive loss of cell viability through DNA damage and programmed cell-death. Inhalation exposure of MWCNTs to rats were found to cause increased lung weights, pronounced multifocal granulomatous inflammation, diffuse histiocytic and neutrophilic inflammation, and intra-alveolar lipoproteinosis [18]. The genotoxicity of MWCNTs have also been investigated in our previous work [19].…”

Computational studies on the interactions of nanomaterials with proteins and their impacts

“…[17][18][19][20][21] On the other hand, the inhaled carbon nanomaterials may lead to stress, inflammation, lung insult and a variety of cardiovascular effects. [22][23][24][25][26][27][28] There are growing numbers of computational studies to investigate the mechanisms behind the spectrum of biological effects. Because of their well-defined structure, carbon nanomaterials also serve as the representative hydrophobic nanomaterials in the pioneering studies about the protein-nanomaterial interaction.…”

A Cost-Effective Method of Aerosolizing Dry Powdered Nanoparticles

“…The accuracy of d m as a measure of an aerosol's true size has been questioned, especially for irregularly shaped aerosols, such as those composed of carbon nanotubes (Ku et al 2007;Ma-Hock et al 2009). While the aerosols in this work are not spherical, as is assumed when d m is calculated, the particle morphology is noticeably more densely packed than are carbon nanotube aerosols.…”

“…When dispersed into a ∼500 L chamber, the ENPs produced number concentrations of 6.82 × 10 4 -1.40 × 10 6 , TABLE 2 Statistics of nanoparticle aerosols generated by various dry powder dispersion techniques. All values are number-weighted unless otherwise specified Primary for C 60 , 0.4 g cm −3 for TiO 2 , and 0.2 g cm −3 for CeO 2 ), these number concentrations translate into mass concentrations (Figure 4) that are of similar order of magnitude to those used for inhalation nanotoxicology studies (Ma-Hock et al 2009;Chen et al 2012;Kim et al 2012;Noel et al 2012). The actual densities of aerosol particles, however, are likely to be higher than the bulk powder densities since the primary particles appear tightly packed within the aerosols, as discussed below.…”

“…To produce TiO 2 agglomerates for a rat inhalation study, Noel et al (2012) coupled commercially available dispersion equipment with a custom-built venturi flow ejector; the median size of their aerosols was 185-194 nm. A custom-built system designed to aerosolize carbonaceous ENPs for inhalation toxicology studies produced single-walled carbon nanotube (SWCNT) aerosols over 1 μm in size (Madl et al 2012), while a rodent inhalation study used a proprietary brush technique to generate multiwalled carbon nanotube (MWCNT) aerosols 0.7-2.0 μm in size as measured by cascade impaction (Ma-Hock et al 2009). …”