| Concentration (mg/m3) | 0 | 0.8 | 4 | 20 | 0 | 0.8 | 4 | 20 |
| Lung |
| Number of animals | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| Degeneration/regeneration, terminal bronchiolar epithelium | (0) | (0) | (2) | (5) | (0) | (0) | (0) | (3) |
| Minimal | 0 | 0 | 2 | 3 | 0 | 0 | 0 | 3 |
| Mild | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 0 |
| Mean ± SD | 0 | 0 | 0.40 ± 0.55 | 1.40 ± 0.55 | 0 | 0 | 0 | 0.60 ± 0.55 |
| Hypertrophy/hyperplasia, mucous cells, bronchi/bronchiole | (0) | (5) | (5) | (3) | (0) | (3) | (5) | (4) |
| Minimal | 0 | 0 | 0 | 2 | 0 | 3 | 1 | 3 |
| Mild | 0 | 5 | 3 | 1 | 0 | 0 | 2 | 1 |
| Moderate | 0 | 0 | 2 | 0 | 0 | 0 | 2 | 0 |
| Mean ± SD | 0 | 2.00 ± 0.00 | 2.40 ± 0.55 | 0.80 ± 0.84 | 0 | 0.60 ± 0.55 | 2.20 ± 0.84 | 1.00 ± 0.71 |
| Smooth muscle hypertrophy, bronchioloalveolar junction | (0) | (0) | (3) | (5) | (0) | (0) | (0) | (3) |
| Minimal | 0 | 0 | 3 | 5 | 0 | 0 | 0 | 3 |
| Mean ± SD | 0 | 0 | 0.60 ± 0.55 | 1.00 ± 0.00 | 0 | 0 | 0 | 0.60 ± 0.55 |
| Infiltration, eosinophil, perivascular | (0) | (1) | (3) | (1) | (0) | (0) | (0) | (2) |
| Minimal | 0 | 1 | 3 | 1 | 0 | 0 | 0 | 2 |
| Mean ± SD | 0 | 0.20 ± 0.45 | 0.60 ± 0.55 | 0.20 ± 0.45 | 0 | 0 | 0 | 0.40 ± 0.55 |
| Cellular debris, alveolar lumen | (0) | (0) | (3) | (2) | (0) | (0) | (0) | (1) |
| Minimal | 0 | 0 | 3 | 2 | 0 | 0 | 0 | 1 |
| Mean ± SD | 0 | 0 | 0.60 ± 0.55 | 0.40 ± 0.55 | 0 | 0 | 0 | 0.20 ± 0.45 |
| Nasal cavity |
| Number of animals | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| Ulceration with suppurative inflammation, respiratory epithelium | (0) | (0) | (0) | (1) | (0) | (0) | (0) | (2) |
| Mild | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
| Marked | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Mean ± SD | 0 | 0 | 0 | 0.40 ± 0.89 | 0 | 0 | 0 | 1.20 ± 1.79 |
| Ulceration with suppurative inflammation, transitional epithelium | (0) | (0) | (0) | (3) | (0) | (0) | (0) | (0) |
| Mild | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 |
| Moderate | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Marked | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 0 |
| Mean ± SD | 0 | 0 | 0 | 2.00 ± 2.00 | 0 | 0 | 0 | 0.60 ± 1.34 |
| Squamous metaplasia, respiratory epithelium | (0) | (0) | (0) | (5) | (0) | (0) | (0) | (5) |
| Minimal | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Mild | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 2 |
| Moderate | 0 | 0 | 0 | 3 | 0 | 0 | 0 | 1 |
| Marked | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Mean ± SD | 0 | 0 | 0 | 2.20 ± 1.10 | 0 | 0 | 0 | 2.40 ± 1.14 |
| Squamous metaplasia, transitional epithelium | (0) | (0) | (0) | (5) | (0) | (0) | (0) | (1) |
| Minimal | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 4 |
| Mild | 0 | 0 | 0 | 4 | 0 | 0 | 0 | 1 |
| Moderate | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 |
| Mean ± SD | 0 | 0 | 0 | 1.40 ± 0.89 | 0 | 0 | 0 | 1.20 ± 0.45 |
| Erosion with necrosis, respiratory epithelium | (0) | (0) | (0) | (5) | (0) | (0) | (0) | (3) |
| Minimal | 0 | 0 | 0 | 3 | 0 | 0 | 0 | 0 |
| Mild | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
| Moderate | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
| Marked | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Mean ± SD | 0 | 0 | 0 | 1.60 ± 0.89 | 0 | 0 | 0 | 1.80 ± 1.79 |
| Erosion with necrosis, transitional epithelium | (0) | (0) | (0) | (5) | (0) | (0) | (0) | (4) |
| Minimal | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 1 |
| Mild | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 |
| Moderate | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
| Marked | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 2 |
| Mean ± SD | 0 | 0 | 0 | 2.20 ± 1.30 | 0 | 0 | 0 | 2.40 ± 1.82 |
| Hypertrophy/hyperplasia, mucous cells, respiratory epithelium | (0) | (5) | (5) | (5) | (0) | (5) | (5) | (5) |
| Minimal | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 0 |
| Mild | 0 | 3 | 0 | 2 | 0 | 0 | 2 | 5 |
| Moderate | 0 | 2 | 4 | 2 | 0 | 4 | 2 | 0 |
| Marked | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
| Mean ± SD | 0 | 2.40 ± 0.55 | 2.60 ± 0.89 | 2.20 ± 0.84 | 0 | 3.20 ± 0.45 | 2.20 ± 0.84 | 1.20 ± 0.45 |
| Metaplasia, mucous cells, transitional epithelium | (0) | (5) | (5) | (0) | (0) | (5) | (5) | (0) |
| Minimal | 0 | 0 | 4 | 0 | 0 | 0 | 1 | 0 |
| Mild | 0 | 1 | 1 | 0 | 0 | 1 | 4 | 0 |
| Moderate | 0 | 4 | 0 | 0 | 0 | 4 | 0 | 0 |
| Mean ± SD | 0 | 2.80 ± 0.45 | 1.20 ± 0.45 | 0 | 0 | 2.80 ± 0.45 | 1.80 ± 0.45 | 0 |
| Atrophy, olfactory epithelium | (0) | (0) | (0) | (1) | (0) | (0) | (0) | (2) |
| Mild | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
| Moderate | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Mean ± SD | 0 | 0 | 0 | 0.20 ± 0.45 | 0 | 0 | 0 | 0.60 ± 0.89 |