title: Genotoxicity and cytotoxicity of multi-wall carbon nanotubes in cultured Chinese hamster lung cells in comparison with chrysotile A fibers.
abstract: OBJECTIVE
  The potential applications and industrial production of multi-wall carbon nanotubes (MWCNT) have raised serious concerns about their safety for human health and the environment. The present study was designed to examine the in vitro cytotoxicity and genotoxicity of MWCNT and UICC chrysotile A (chrysotile).
  
  
  METHODS
  Cytotoxicity using both colony formation and lactate dehydrogenase (LDH) assays and genotoxicity including chromosome aberration, micronucleus induction and hgprt mutagenicity were examined by exposing cultured Chinese hamster lung (CHL/IU) cells to MWCNT or chrysotile at different concentrations.
  
  
  RESULTS
  The in vitro cytotoxicity of MWCNT depended on the solvent used for suspension of MWCNT and ultrasonication duration of the MWCNT suspension. A combination of DMSO/culture medium and 3-minute ultrasonication resulted in a well-dispersed medium with dispersion and isolation of agglomerated MWCNT by ultrasonication which manifested the highest cytotoxicity. The cytotoxicity was more potent for chrysotile than MWCNT. The genotoxicity of MWCNT was characterized by the formation of polyploidy without structural chromosome aberration, and an increased number of bi- and multi-nucleated cells without micronucleus induction, as well as negative hgprt mutagenicity. Chrysotile exhibited essentially the same genotoxicity as MWCNT, except for marginal but significant induction of micronuclei. MWCNT and chrysotile were incompletely internalized in the cells and localized in the cytoplasm.
  
  
  CONCLUSIONS
  MWCNT and chrysotile were cytotoxic and genotoxic in Chinese hamster lung cells, but might interact indirectly with DNA. The results suggest that both test substances interfere physically with biological processes during cytokinesis.
authors.affiliation: Japan Bioassay Research Center, Japan Industrial Safety and Health Association, 2445 Hirasawa, Hadano, Kanagawa, Japan. m-asakura@jisha.or.jp
authors.forename: Masumi
authors.initials: M
authors.lastname: Asakura
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Sasaki
authors.forename: Toshie
authors.initials: T
authors.lastname: Sugiyama
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Takaya
authors.forename: Shigeki
authors.initials: S
authors.lastname: Koda
authors.forename: Kasuke
authors.initials: K
authors.lastname: Nagano
authors.forename: Heihachiro
authors.initials: H
authors.lastname: Arito
authors.forename: Shoji
authors.initials: S
authors.lastname: Fukushima
mesh_terms: D000818:Animals; D017632:Asbestos, Serpentine / Q000633:toxicity*; D016466:CHO Cells / Q000187:drug effects / Q000648:ultrastructure; D002869:Chromosome Aberrations / Q000139:chemically induced; D006224:Cricetinae; D003412:Cricetulus; D048749:Cytokinesis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D007770:L-Lactate Dehydrogenase / Q000096:biosynthesis; D015162:Micronucleus Tests; D008855:Microscopy, Electron, Scanning; D037742:Nanotubes, Carbon / Q000633:toxicity*
chemical_list: D017632:Asbestos, Serpentine; D037742:Nanotubes, Carbon; D007770:L-Lactate Dehydrogenase