TABLE 3.
Lung Lesions after Intermittent Exposures to Diacetyl
| Lesion | 0 ppm | 100 ppm | 200 ppm | 400 ppm |
|---|---|---|---|---|
| 2-week exposure | ||||
| Peribronchial lymphocytic inflammation | 0/5a | 4/5 (2.0)b | 5/5 (2.4) | 5/5 (3.0) |
| Peribronchiolar lymphocytic inflammation | 0/5 | 1/5 (1.0) | 0/5 | 1/5 (1.0) |
| Total group score | 0c | 9c | 12 | 16 |
| 4-week exposure | ||||
| Peribronchial lymphocytic inflammation | 0/3 | 2/3 (1.0) | 5/5 (2.4) | 5/5 (3.0) |
| Peribronchiolar lymphocytic inflammation | 0/3 | 0/3 | 1/5 (1.0) | 3/5 (1.0) |
| Total group score | 0 | 3 | 13 | 18 |
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 scores were 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.