Table 2.
Incidences of tumors, tumor types and preneoplasias in the lungs of female Wistar rats after intratracheal instillation of granular dusts
| Control | Crystalline silica Quartz DQ12 | Crystalline silica Quartz DQ12 + PVNO | Amorphous silica Aerosil® 150 | Carbon black PRINTEX® 90 | Coal dust | |
|---|---|---|---|---|---|---|
| No. of rats examined | 55 | 53 | 56 | 53 | 59 | 51 |
| No. of rats with lung tumors | 0 (0%)a | 21 (39.6%) | 12 (21.4%) | 5 (9.4%) | 9 (15%) | 0 (0%) |
| No. of rats with multiple tumors | 0 (0%) | 11 (21%) | 4 (7%) | 0 (0%) | 2 (3.3%) | 0 (0%) |
| Total number of lung tumors/group | 0 | 46 | 18 | 5 | 13 | 0 |
| Frequency of lung tumor types | ||||||
| No. of rats with bronchiolo-alveolar adenoma | 0 (0%) | 6 (11.3%) | 2 (3.6%) | 2 (3.8%) | 2 (3.4%) | 0 (0%) |
| No. of rats with bronchiolo-alveolar carcinoma | 0 (0%) | 14 (26.4%) | 6 (10.7%) | 2 (3.8%) | 6 (10.2%) | 0 (0%) |
| No. of rats with cystic keratinizing epithelioma | 0 (0%) | 5 (9.4%) | 2 (3.6%) | 0 (0%) | 1 (1.7%) | 0 (0%) |
| No. of rats with squamous cell carcinoma | 0 (0%) | 7 (13.2%) | 2 (3.6%) | 1 (1.9%) | 2 (3.4%) | 0 (0%) |
| No. of rats with adenosquamous carcinoma | 0 (0%) | 0 (0%) | 1 (1.8%) | 0 (0%) | 0 (0%) | 0 (0%) |
| Frequency of preneoplasias graded severe/very severe with signs of cytological atypia | ||||||
| No. of rats with bronchiolo-alveolar hyperplasia | 1 (2%)a | 23 (43.4%) | 7 (21.4%) | 1 (1.9%) | 9 (15%) | 1 (2%) |
| No. of rats with squamous cell metaplasia | 0 (0%) | 4 (7.6%) | 5 (8.9%) | 0 (0%) | 4 (6.8%) | 0 (0%) |
| Total number of rats with preneoplastic lesions | 1 (2%) | 23 (43.4%) | 10 (17.9%) | 1 (1.9%) | 12 (20.3%) | 1 (2%) |
a
Number of tumor-bearing rats expressed as a percentage of the total number of rats examined in this treatment group