title: Aspect ratio has no effect on genotoxicity of multi-wall carbon nanotubes.
abstract: Carbon nanotubes (CNTs) have specific physico-chemical and electrical properties that are useful for telecommunications, medicine, materials, manufacturing processes and the environmental and energy sectors. Yet, despite their many advantages, it is also important to determine whether CNTs may represent a hazard to the environment and human health. Like asbestos, the aspect ratio (length:diameter) and metal components of CNTs are known to have an effect on the toxicity of carbon nanotubes. Thus, to evaluate the toxic potential of CNTs in relation to their aspect ratio and metal contamination, in vivo and in vitro genotoxicity tests were conducted using high-aspect-ratio (diameter: 10-15 nm, length: ~10 μm) and low-aspect-ratio multi-wall carbon nanotubes (MWCNTs, diameter: 10-15 nm, length: ~150 nm) according to OECD test guidelines 471 (bacterial reverse mutation test), 473 (in vitro chromosome aberration test), and 474 (in vivo micronuclei test) with a good laboratory practice system. To determine the treatment concentration for all the tests, a solubility and dispersive test was performed, and a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) solution found to be more suitable than distilled water. Neither the high- nor the low-aspect-ratio MWCNTs induced any genotoxicity in a bacterial reverse mutation test (~1,000 μg/plate), in vitro chromosome aberration test (without S9: ~6.25 μg/ml, with S9: ~50 μg/ml), or in vivo micronuclei test (~50 mg/kg). However, the high-aspect-ratio MWCNTs were found to be more toxic than the low-aspect-ratio MWCNTs. Thus, while high-aspect-ratio MWCNTs do not induce direct genotoxicity or metabolic activation-mediated genotoxicity, genotoxicity could still be induced indirectly through oxidative stress or inflammation.
authors.affiliation: Biosafety Evaluation Headquarter, Korea Environment and Merchandise Testing Institute, Incheon, South Korea.
authors.forename: Jin Sik
authors.initials: JS
authors.lastname: Kim
authors.forename: Kyu
authors.initials: K
authors.lastname: Lee
authors.forename: Young Hee
authors.initials: YH
authors.lastname: Lee
authors.forename: Hyun Sun
authors.initials: HS
authors.lastname: Cho
authors.forename: Ki Heon
authors.initials: KH
authors.lastname: Kim
authors.forename: Kyung Hee
authors.initials: KH
authors.lastname: Choi
authors.forename: Sang Hee
authors.initials: SH
authors.lastname: Lee
authors.forename: Kyung Seuk
authors.initials: KS
authors.lastname: Song
authors.forename: Chang Soo
authors.initials: CS
authors.lastname: Kang
authors.forename: Il Je
authors.initials: IJ
authors.lastname: Yu
mesh_terms: D000818:Animals; D016466:CHO Cells; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002869:Chromosome Aberrations / Q000139:chemically induced; D006224:Cricetinae; D003412:Cricetulus; D004926:Escherichia coli / Q000187:drug effects; D017408:Guidelines as Topic; D008297:Male; D008422:Materials Testing / Q000592:standards; D051379:Mice; D008813:Mice, Inbred ICR; D048629:Micronuclei, Chromosome-Defective / Q000139:chemically induced; D009153:Mutagens / Q000737:chemistry* / Q000493:pharmacokinetics / Q000633:toxicity*; D009154:Mutation / Q000187:drug effects; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000633:toxicity* / Q000648:ultrastructure; D010316:Particle Size; D012486:Salmonella typhimurium / Q000187:drug effects; D013047:Specific Pathogen-Free Organisms; D014018:Tissue Distribution
chemical_list: D009153:Mutagens; D037742:Nanotubes, Carbon