title: Lung carcinogenicity of inhaled multi-walled carbon nanotube in rats.
abstract: Multi-walled carbon nanotubes (MWCNTs) constitute one of the most promising types of nanomaterials in industry today. With their increasing use, the potential toxicity and carcinogenicity of MWCNT needs to be evaluated in bioassay studies using rodents. Since humans are mainly exposed to MWCNT by inhalation, we performed a 104-week carcinogenicity study using whole-body inhalation exposure chambers with a fibrous straight type of MWCNT at concentrations of 0, 0.02, 0.2, and 2 mg/m3using male and female F344 rats.
  
  
  
  Lung carcinomas, mainly bronchiolo-alveolar carcinoma, and combined carcinomas and adenomas were significantly increased in males exposed to 0.2 and 2 mg/m3MWNT-7 and in females exposed to 2 mg/m3MWNT-7 compared to the clean air control group. However, no development of pleural mesothelioma was observed. Concentration-dependent toxic effects in the lung such as epithelial hyperplasia, granulomatous change, localized fibrosis, and alteration in BALF parameters were found in MWNT-7 treatment groups of both sexes. There were no MWNT-7-specific macroscopic findings in the other organs, including the pleura and peritoneum. Absolute and relative lung weights were significantly elevated in male rats exposed to 0.2 and 2 mg/m3MWNT-7 and in all exposed female groups. The lung burdens of MWNT-7 were clearly increased in a concentration-dependent as well as a duration-dependent manner.
  
  
  
  There is clear evidence that MWNT-7 is carcinogenic to the lungs of male and female F344 rats, however no plural mesothelioma was observed.
authors.affiliation: Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan. tatsuya-kasai@jbrc.johas.go.jp.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kasai
authors.affiliation: Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Umeda
authors.affiliation: Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ohnishi
authors.affiliation: Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Mine
authors.affiliation: Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Kondo
authors.affiliation: Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Takeuchi
authors.affiliation: Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan.
authors.forename: Michiharu
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan.
authors.forename: Shoji
authors.initials: S
authors.lastname: Fukushima
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001992:Bronchoalveolar Lavage Fluid; D005260:Female; D019570:Inhalation Exposure; D008175:Lung Neoplasms / Q000139:chemically induced* / Q000473:pathology; D008297:Male; D037742:Nanotubes, Carbon / Q000633:toxicity*; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D037742:Nanotubes, Carbon
keywords: Inhalation carcinogenicity; Lung carcinogenicity; Lung carcinoma; MWCNT; MWNT-7; Multi-walled carbon nanotube; Rat; Whole body inhalation