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Table 9 Microscopic findings in the tracheobronchial lymph nodes 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 10/8 10/9 10/10 10/8 9/10 10/10 10/10
(24 h/90 days)
Black particle deposition         
minimal - - 8/5 - - - 5/3 1
slight - - -/2 6/3 - - - 7/1
moderate - - - 4/7 - - - 1/9
Mean severitya - - 0.8/0.9 2.4/2.7 - - 0.5/0.3 1.8/2.9
Increased lymphocytes, cortex/paracortex         
minimal - - 3/- 4/7 - - 1/- 3/6
slight - - - 3/2 - - - 7/-
moderate - - - 3/- - - - -
Mean severitya - - 0.3/- 1.9/1.1 - - 0.1/- 1.7/0.6
Endothelial vacuolation, high endothelial venule         
minimal - - 1/- 1/2 - - - 2/5
slight - - 1/- 7/1 - - - 5/-
Mean severitya - - 0.3/- 1.5/0.4 - - - 1.2/0.5
  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