TABLE 6.
Lung Lesions after Subchronic Exposure to Diacetyl
| Lesion | 0 ppm | 25 ppm | 50 ppm | 100 ppm |
|---|---|---|---|---|
| 6-week exposure | ||||
| Peribronchial lymphocytic inflammation | 0/5a | 3/5 (1.0)b | 5/5 (1.6) | 5/5 (2.6) |
| Bronchial epithelial atrophy and denudation | 0/5 | 0/5 | 1/5 (1.0) | 5/5 (2.8) |
| Bronchial epithelial regeneration | 0/5 | 0/5 | 0/5 | 5/5 (2.8) |
| Peribronchiolar lymphocytic inflammation | 2/5 (1.0) | 0/5 | 1/5 (1.0) | 3/5 (1.0) |
| Total group score | 2c | 3 | 10 | 44 |
| 12-week exposure | ||||
| Peribronchial lymphocytic inflammation | 0/5 | 2/5 (1.0) | 4/5 (1.5) | 5/5 (2.6) |
| Bronchial epithelial atrophy and denudation | 0/5 | 0/5 | 0/5 | 5/5 (3.0) |
| Bronchial epithelial regeneration | 0/5 | 0/5 | 0/5 | 5/5 (3.0) |
| Peribronchiolar lymphocytic inflammation | 0/5 | 0/5 | 0/5 | 3/5 (1.3) |
| Total group score | 0 | 2 | 6 | 47 |
| 6-weeks postexposure | ||||
| Peribronchial lymphocytic inflammation | 3/5 (1.3) | 1/5 (2.0) | 4/5 (1.8) | 5/5 (2.8) |
| Bronchial epithelial atrophy | 0/5 | 0/5 | 0/5 | 3/5 (1.0) |
| Bronchial epithelial regeneration | 0/5 | 0/5 | 0/5 | 5/5 (2.0) |
| Peribronchiolar lymphocytic inflammation | 0/5 | 0/5 | 0/5 | 2/5 (1.0) |
| Total group score | 4 | 2 | 7 | 29 |
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.