Table
22. Summary of data on lung tumors induced in rats by crystalline
silica
|
Sample
and exposure conditions
|
Rat
strain
|
Sex
|
Incidence
of lung tumors*
|
Reference
|
Comments
|
Treated
rats
|
Controls
|
Quartz
(Min-U-Sil 5):
|
Intratracheal
instillation of
7 mg/wk for 10 wk |
Sprague-Dawley
|
|
6/36
|
0/58
|
Holland
et al. [1983]
|
Treated
rats had 1 adenoma and
5 carcinomas. |
Inhalation
(nose only) of 12 ± 5 mg/m3 for up to 2 yr |
Fischer
344
|
F
|
20/60
|
0/54
|
Holland
et al. [1986]
|
Treated
rats had
6 adenomas, 11 adenocarcinomas, and 3 epidermoid carcinomas. |
Inhalation
of
51.6 mg/m3 for various durations; sacrificed at 24 months |
Fischer
344
|
F
|
10/53
|
0/47
|
Dagle
et al. [1986]
|
Treated
female rats had 10 epidermoid carcinomas. |
M
|
1/47
|
0/42
|
Intratracheal
instillation of 20 mg in left lung; sacrificed at 12, 18, or 22 months,
or found dead |
Fischer
344
|
M
|
30/67
|
1/75
|
Groth
et al. [1986]
|
Treated
rats had
30 adenocarcinomas. Controls had
1 adenocarcinoma. |
Novaculite
(i.e., micro-crystalline quartz):
|
Intratracheal
instillation of 20 mg in left lung; sacrificed at 12, 18, or 22 months,
or found dead |
Fischer
344
|
M
|
21/72
|
1/75
|
Groth
et al. [1986]
|
Treated
rats had
20 adenocarcinomas and 1 epidermoid carcinoma. Controls had
1 adenocarcinoma. |
Raw
shale dust:
|
Inhalation
(nose only) of 152 ± 51 mg/m3 (average quartz content:
8%12%) |
Fischer
344
|
F
|
17/59
|
0/54
1/15
|
Holland
et al. [1986]
|
Treated
rats had
2 adenomas, 8 adenocarcinomas, and 7 epidermoid carcinomas. Controls
had 1 adenoma. |
Spent
shale dust:
|
Inhalation
(nose only) of 176 ±
75 mg/m3 (average quartz content: 8%12%) |
Fischer
344
|
F
|
11/59
|
0/54
1/15
|
Holland
et al. [1986]
|
Treated
rats had 2 adenomas,
8 adenocarcinomas, and 1 epidermoid carcinoma. Controls had 1 adenoma. |
Quartz
(DQ12):
|
Inhalation
of 1 mg/m3 for 24 months |
Fischer
344
|
F
|
12/50
|
3/100
(male and female)
|
Muhle
et al. [1989]
|
Treated
female rats had 2 keratinizing cystic squamous
cell tumors,
2 adenomas, and
8 adenocarcinomas. Treated male rats had 2 keratinizing cystic squamous
cell tumors,
2 adenocarcinomas,
1 adenosquamous carcinoma, and
1 squamous cell carcinoma. Controls had 2 adenomas and 1 adenocarcinoma. |
Fischer
344
|
M
|
6/50
|
|
Inhalation
(nose only) of 6 mg/m3 for 29 days followed by lifetime
observation |
Wistar
|
F
|
62/82
|
0/85
|
Spiethoff
et al. [1992]
|
Treated
rats had
8 adenomas,
17 bronchioloalveolar carcinomas, and
37 squamous cell carcinomas. |
Inhalation
(nose only) of 30 mg/m3 for 29 days followed by lifetime
observation |
Wistar
|
F
|
69/82
|
0/85
|
Spiethoff
et al. [1992]
|
Treated
rats had
13 adenomas,
26 bronchioloalveolar carcinomas, and
30 squamous cell carcinomas. |
Source:
Adapted from Saffiotti et al. [1996].
*Number of lung tumors per number of rats observed.
Not reported.
Investigators used two control groups. |