title: Lung inflammation and lack of genotoxicity in the comet and micronucleus assays of industrial multiwalled carbon nanotubes Graphistrength(©) C100 after a 90-day nose-only inhalation exposure of rats.
abstract: BACKGROUND
  Graphistrength (©) C100 multiwalled carbon nanotubes (MWCNT) provide superior electrical and mechanical properties for various applications. The evaluation of the intrinsic hazard properties of Graphistrength(©) C100 is an essential step for safe use. A general feature of multiwalled carbon nanotubes after inhalation or intratracheal exposures is the induction of an inflammatory reaction in the lungs sometimes associated with local genotoxic effects.
  
  
  METHODS
  After investigating different parameters for the aerosol generation and performing a 5-day inhalation range finding study, male and female Wistar rats were exposed nose-only for 90 days to target concentrations of 0.05, 0.25 and 5.0 mg/m(3) air of Graphistrength (©) C100 and sacrificed 24 h and 90 days after the last exposure. Broncho-alveolar lavage fluid (BALF) was also collected and analyzed for inflammatory parameters. Twenty-four hours post-exposure, chromosomal aberrations in the bone marrow cells were evaluated by the micronucleus test and DNA damages in the lung, kidney and liver cells by both the standard and the human 8-oxoguanine DNA N-glycosylase 1 (hOGG1)-modified comet assay. All studies were performed according to the OECD test guidelines.
  
  
  RESULTS
  An inflammatory lung reaction and the release of inflammatory factors in the BALF were observed in all rats exposed to 5.0 mg/m(3), associated with changes in the differential white blood cells counts. The slight changes in BALF parameters at 0.25 mg/m(3) recovered and signs of lung clearance of the MWCNT were observed. No pathological changes were observed on the pleura. Neither increase in the number of micronucleated polychromatic erythrocytes nor increase in percent DNA damage were observed at any concentration.
  
  
  CONCLUSIONS
  Lung inflammation characteristic of an overload with insoluble particles was observed after a 90-day exposure to 5.0 mg/m(3) of Graphistrength (©) C100. Clear signs of clearance and recovery were observed at 0.25 mg/m(3). No genotoxicity was detected locally in lung and distally in bone marrow, liver and kidney. Therefore, Graphistrength (©) C100 appears of low concern in term of local and systemic genotoxicity and a No-Observed Adverse Effect Concentration (NOAEC) of 0.25 mg/m(3) (0.28 mg/m(3) as actual concentration) was established for the repeated-dose toxicity.
authors.affiliation: Harlan Laboratories Ltd, Zelgliweg 1, 4452, Itingen, Switzerland. Daniela.pothmann@gmx.de.
authors.forename: Daniela
authors.initials: D
authors.lastname: Pothmann
authors.affiliation: Laboratoire de Toxicologie Génétique, Institut Pasteur de Lille, 1 rue du Pr. Calmette, 59019, Lille, Cedex, France. sophie.simar@pasteur-lille.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Simar
authors.affiliation: Harlan Laboratories Ltd, Zelgliweg 1, 4452, Itingen, Switzerland. schuler@s-t-c.eu.
authors.forename: Detlef
authors.initials: D
authors.lastname: Schuler
authors.affiliation: Harlan Cytotest Cell Research GmbH, In den Leppsteinwiesen 19, 64380, Rossdorf, Germany. edony@harlan.com.
authors.forename: Eva
authors.initials: E
authors.lastname: Dony
authors.affiliation: Harlan Laboratories Ltd, Zelgliweg 1, 4452, Itingen, Switzerland. sgaering@harlan.com.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Gaering
authors.affiliation: Le Net Pathology Consulting, 18 rue Henry Dunant, 37400, Amboise, France. lenet@lenetpathologyconsulting.com.
authors.forename: Jean-Loïc
authors.initials: JL
authors.lastname: Le Net
authors.affiliation: AnaPath GmbH, Buchsweg 56, 4625, Oberbuchsiten, Switzerland. okazaki5374625@bluewin.ch.
authors.forename: Yoshi
authors.initials: Y
authors.lastname: Okazaki
authors.affiliation: Arkema France, Groupement de Recherches de Lacq (GRL), Laboratoires d'analyse de surface et microscopie et de chimie analytique, 64170, Lacq, France. jean-michel.chabagno@arkema.com.
authors.forename: Jean Michel
authors.initials: JM
authors.lastname: Chabagno
authors.affiliation: Arkema France, Groupement de Recherches de Lacq (GRL), Laboratoires d'analyse de surface et microscopie et de chimie analytique, 64170, Lacq, France. cecile.bessibes@arkema.com.
authors.forename: Cécile
authors.initials: C
authors.lastname: Bessibes
authors.affiliation: Arkema France, Groupement de Recherches de Lacq (GRL), Laboratoires d'analyse de surface et microscopie et de chimie analytique, 64170, Lacq, France. julien.beausoleil@arkema.com.
authors.forename: Julien
authors.initials: J
authors.lastname: Beausoleil
authors.affiliation: Laboratoire de Toxicologie Génétique, Institut Pasteur de Lille, 1 rue du Pr. Calmette, 59019, Lille, Cedex, France. fabrice.nesslany@pasteur-lille.fr.|UDSL, EA 4483, Département Toxicologie-Santé Publique-Environnement, Faculté de Pharmacie, 1 rue du Pr. Laguesse, 59019, Lille, France. fabrice.nesslany@pasteur-lille.fr.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Nesslany
authors.affiliation: Arkema France, Département Toxicologie et Environnement, 420 rue d' Estienne d' Orves, 92705, Colombes, France. jean-francois.regnier@arkema.com.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Régnier
mesh_terms: D000336:Aerosols; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D020552:Comet Assay; D004249:DNA Damage; D045647:DNA Glycosylases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D018836:Inflammation Mediators / Q000276:immunology / Q000378:metabolism; D019570:Inhalation Exposure / Q000009:adverse effects*; D008168:Lung / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008297:Male; D048629:Micronuclei, Chromosome-Defective / Q000139:chemically induced*; D015162:Micronucleus Tests; D037742:Nanotubes, Carbon / Q000633:toxicity*; D019055:No-Observed-Adverse-Effect Level; D010316:Particle Size; D011014:Pneumonia / Q000139:chemically induced* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D011237:Predictive Value of Tests; D017208:Rats, Wistar; D018570:Risk Assessment; D013997:Time Factors
chemical_list: D000336:Aerosols; D018836:Inflammation Mediators; D037742:Nanotubes, Carbon; D045647:DNA Glycosylases; C479058:oxoguanine glycosylase 1, human