Table 1. Histopathological findings in the lung tissues intratracheally instilled with vehicle control, L-SWCNTs or H-SWCNTs.

Days post-instillation	Findings	Vehicle	L-SWCNT	H-SWCNT
3 days	SWCNTs in alveoli, alveolar wall or bronchiole	−	+	++
7 days	SWCNTs in alveoli, alveolar wall or bronchiole	−	+	++
30 days	SWCNTs in alveoli, alveolar wall or bronchiole	−	+	++
	Fibrin deposition	−	−	+
	90 days	SWCNTs in alveoli, alveolar wall or bronchiole	−	+	++
Fibrin deposition		−	−	+
Granuloma		−	−	+
180 days		SWCNTs in alveoli, alveolar wall or bronchiole	−	+	+
	Fibrin deposition	−	−	−
	Granuloma	−	+	±
	365 days	SWCNTs in alveoli, alveolar wall or bronchiole	−	+	+
Fibrin deposition		−	−	−
Granuloma		−	−	−
754 days		SWCNTs in alveoli, alveolar wall or bronchiole	−	+	+
	Fibrin deposition	−	−	−
	Granuloma	−	−	−

−: no remarkable change; ±: minimal change; +: mild change; and ++: moderate change.