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Table 10 Microscopic findings in the nasal cavity and larynx of male and female rats 24 h and 90 days after a 90-day exposure to Graphistrength© C100

From: 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

  Males Females
Target concentration (mg/m3) 0 0.05 0.25 5.0 0 0.05 0.25 5.0
Number examined 10/10 10/0 10/10 10/10 10/10 10/0 10/10 10/10
(24 h/90 days)
Nasal cavity epithelium, eosinophilic globules         
minimal 4/2 - 2/3 2/6 -/3 - 3/2 1/4
slight -/1 - - 3/2 - - - 6/2
moderate - - - 5/2 - - - 2/3
Mean severitya 0.4/0.4 - 0.2/0.3 2.3/1.6 -/0.3 - 0.3/0.2 1.9/1.7
Larynx, squamous metaplasia         
minimal - - 2/- 4/- - - - 5/1
Mean severitya - - 0.2/- 0.4/- - - - 0.5/0.1
  1. Histopathological findings were graded in severity using a five point system of minimal (grade 1), slight (grade 2), moderate (grade 3), marked (grade 4) or severe (grade 5)a: mean severity is ∑ number of animals x severity / number of examined organs in the group
  2. a: mean severity is ∑ number of animals x severity / number of examined organs in the group - : no animal affected