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 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

	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)	10/10	10/8	10/9	10/10	10/8	9/10	10/10	10/10
Black particle deposition
minimal	-	-	8/5	-	-	-	5/3	1
slight	-	-	-/2	6/3	-	-	-	7/1
moderate	-	-	-	4/7	-	-	-	1/9
Mean severity^a	-	-	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 severity^a	-	-	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 severity^a	-	-	0.3/-	1.5/0.4	-	-	-	1.2/0.5

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