TABLE 5.
Nasal Lesions after Subchronic Exposure to Diacetyl
| Lesion | 0 ppm | 25 ppm | 50 ppm | 100 ppm |
|---|---|---|---|---|
| 6-week exposure | ||||
| Inflammation, chronic active | 2/5a (1.0)b | 2/4 (1.5) | 4/5 (1.5) | 5/5 (3.8) |
| Exudate, suppurative | 0/5 | 2/4 (1.0) | 4/5 (1.0) | 5/5 (3.8) |
| Respiratory epithelium, necrosis, and ulceration | 0/5 | 0/4 | 2/5 (1.0) | 5/5 (1.2) |
| Respiratory epithelium, metaplasia, squamous | 0/5 | 1/4 (1.0) | 3/5 (2.3) | 5/5 (3.0) |
| Olfactory epithelium, metaplasia, respiratory | 0/5 | 0/4 | 3/5 (1.7) | 1/5 (3.0) |
| Olfactory epithelium, atrophy | 0/5 | 0/4 | 4/5 (2.0) | 5/5 (2.9) |
| Total group score | 2c | 8 | 32 | 77 |
| 12-week exposure | ||||
| Inflammation, chronic active | 1/5 (1.0) | 4/5 (1.3) | 5/5 (1.8) | 5/5 (4.0) |
| Exudate, suppurative | 0/5 | 0/5 | 5/5 (2.2) | 5/5 (3.6) |
| Respiratory epithelium, necrosis, and ulceration | 0/5 | 0/5 | 1/5 (1) | 5/5 (2.6) |
| Respiratory epithelium, metaplasia, squamous | 0/5 | 2/5 (1.0) | 4/5 (1.3) | 5/5 (3.0) |
| Olfactory epithelium, metaplasia, respiratory | 0/5 | 0/5 | 5/5 (2.6) | 5/5 (3.4) |
| Olfactory epithelium, atrophy | 0/5 | 0/5 | 5/5 (1.8) | 5/5 (3.0) |
| Total group score | 1 | 7 | 48 | 98 |
| 6-weeks postexposure | ||||
| Inflammation, chronic active | 0/5 | 2/5 (1.0) | 4/5 (1.3) | 5/5 (2.2) |
| Exudate, suppurative | 0/5 | 0/5 | 0/5 | 3/5 (2.0) |
| Respiratory epithelium, necrosis, and ulceration | 0/5 | 0/5 | 0/5 | 0/5 |
| Respiratory epithelium, metaplasia, squamous | 0/5 | 1/5 (1.0) | 0/5 | 4/5 (1.0) |
| Olfactory epithelium, metaplasia, respiratory | 0/5 | 1/5 (1.0) | 4/5 (1.5) | 4/5 (2.3) |
| Olfactory epithelium, atrophy | 0/5 | 1/5 (1.0) | 3/5 (1.0) | 4/5 (2.0) |
| Total group score | 0 | 5 | 14 | 38 |
a
Number of animals with lesion/number evaluated.
b
Numbers in parentheses represent the average severity grades for those animals with the lesions. Severity grading scheme: minimal = 1, mild = 2, moderate = 3, marked = 4.
c
Total group score calculated by multiplying the number of animals with each lesion times the average severity grade for that lesion, and then adding the products obtained for each of these lesions. Group scores were weighted for lesions in which less than five animals were evaluated.