title: Characteristics of multiwall carbon nanotubes for an intratracheal instillation study with rats.
abstract: Much concern has been raised over the health consequences of workers exposed to carbon nanotubes. In order to characterize multi-wall carbon nanotubes (MWCNT) suspended in a phosphate-buffered saline containing 0.1% Tween 80 for an intratracheal instillation study. Length and width distributions of the MWCNT fibers, dispersion of MWCNT in the suspension and in the lung tissue and the MWCNT contents of metal impurities were investigated. Arithmetic mean length and width of the MWCNT fibers as measured on scanning electron microscope (SEM) photographs were 5.0 microm and 88 nm, respectively, and fibers longer than 5.0 microm were 38.9% of all fibers measured. Dynamic light scattering size measurement revealed that 5-min ultrasonication, together with addition of Tween 80 into the suspension, decreased the hydrodynamic diameters of the agglomerated MWCNT to those of finer particles below 1.0 microm. SEM observation showed good dispersion of MWCNT in the suspension, and in the alveoli on Day 1 after instillation. Concentration of iron, chromium and nickel in the MWCNT were 4,400, 48 and 17 ppm (wt/wt), respectively, all of which were below levels that would elicit positive pulmonary toxic responses to these metals. The results suggest that well-dispersed, long and thin MWCNT fibers exhibit asbestos-like pathogenicity in the lung.
authors: National Institute of Occupational Safety and Health, Nagao, Tama-ku, Kawasaki, Kanagawa. takaya@h.jniosh.go.jp
authors: Mitsutoshi
authors: M
authors: Takaya
authors: Fumio
authors: F
authors: Serita
authors: Kazunori
authors: K
authors: Yamazaki
authors: Shigetoshi
authors: S
authors: Aiso
authors: Hisayo
authors: H
authors: Kubota
authors: Masumi
authors: M
authors: Asakura
authors: Naoki
authors: N
authors: Ikawa
authors: Kasuke
authors: K
authors: Nagano
authors: Heihachiro
authors: H
authors: Arito
authors: Shoji
authors: S
authors: Fukushima
mesh_terms: D000818:Animals; D002857:Chromium / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D008168:Lung / Q000187:drug effects* / Q000473:pathology; D008297:Male; D008855:Microscopy, Electron, Scanning; D037742:Nanotubes, Carbon / Q000009:adverse effects / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry; D010316:Particle Size; D051381:Rats; D011916:Rats, Inbred F344; D013535:Suspensions; D014132:Trachea
chemical_list: D037742:Nanotubes, Carbon; D013535:Suspensions; D002857:Chromium; D009532:Nickel; D007501:Iron