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

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

	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)	10/10	10/0	10/10	10/10	10/10	10/0	10/10	10/10
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 severity^a	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 severity^a	-	-	0.2/-	0.4/-	-	-	-	0.5/0.1

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
^a: mean severity is ∑ number of animals x severity / number of examined organs in the group - : no animal affected