PMID- 21539476
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20121002
LR  - 20110504
IS  - 0895-8378 (Print)
IS  - 0895-8378 (Linking)
VI  - 7
IP  - 4
DP  - 1995
TI  - Studies on the chronic toxicity (inhalation) of four types of refractory ceramic 
      fiber in male Fischer 344 rats.
PG  - 425-67
LID - 10.3109/08958379509015208 [doi]
AB  - Abstract Refractory ceramic fibers (RCF) are man-made vitreous fibers used 
      primarily in industrial high-temperature applications, especially for insulation 
      of furnaces and kilns. Because of their increasing use and potential for human 
      exposure, a chronic toxicity/carcinogenicity inhalation study was conducted in 
      Fischer 344 (F344) rats. Five groups of 140 weanling male F344 rats were exposed 
      via noseonly inhalation to either HEPA-filtered air (chamber controls) or 30 
      mg/m(3) (approximately 220 fibers/cm(3)) of three types [kaolin-based, 
      high-purity, and aluminum zirconia silica (AZS)] of "size-selected" RCF fibers 
      (approximately 1micro in diameter and approximately 20 um in length) and an 
      "after-service" heat-treated (2400 degrees F for 24 h) kaolin-based fiber for 6 h/day, 5 
      days/wk for 24 mo. They were then held unexposed until approximately 20% survival 
      and then sacrificed at 30 mo. A positive control group of 80 F344 rats was 
      exposed to 10 mg/m(3) chrysotile asbestos. Croups of 3-6 animals were sacrificed 
      at 3, 6, 9, 12, 15, 18, and 24 mo to follow the progression of lesions and to 
      determine fiber lung burdens. Additional groups of 3 rats were removed from 
      exposure at 3, 6, 9, 12, and 18 mo and were held until sacrificed at 24 mo 
      (recovery groups) for similar determinations. Lung burdens increased rapidly for 
      all RCFs, appearing to plateau by about 12 mo. By 24 mo, lung burdens ranged from 
      2.6 to 9.6 x 10(5) fiberslmg of dry lung tissue for the RCFs tested. 
      Treatment-related lesions were restricted to the lungs. To some extent all types 
      of RCF resulted in macrophage infiltration, bronchiolization of proximal alveoli, 
      and microgranuloma formation by 3 mo of exposure. Interstitial fibrosis was 
      observed at 6 mo for all types of RCF, except the "after-service" fiber where 
      fibrosis was not seen until 12 mo. The lesions progressed in severity until 12-15 
      mo, after which they plateaued. A minimal amount of focal pleural fibrosis was 
      first observed at 9 mo and progressed to a mild severity by the end of the study. 
      Fxposure-related pulmonary neoplasms (bronchoalveolar adenomas and carcinomas 
      combined) were observed with all 4 types of RCF [kaolin, 16 of 123 (13%); AZS, 9 
      of 121 (7.4%); high-purity, 19 of 121 (15.7%); and "after-service,"4 of 118 
      (3.4%)], compared to 2 of 120 (1.5%) in the untreated air controls. Pleural 
      mesotheliomas were observed in two kaolin, three AZS, two high-purity, and one 
      "after-service" exposed rats. A comparable but slightly greater amount of 
      fibrosis was observed in the lungs of the positive (chrysotile asbestos) 
      controls. The incidence of bronchoalveolar neoplasms in the chrysotile exposed 
      rats was 13 of 69 (18.8%), and a mesothelioma occurred in 1 (1.4%) animal. The 
      results of this study showed that the four types of RCF studied had carcinogenic 
      activity in rats at the maximum tolerated dose.
FAU - Mast, R W
AU  - Mast RW
AD  - Carborundum Company, Niagara Falls, New York, USA.
FAU - McConnell, E E
AU  - McConnell EE
FAU - Anderson, R
AU  - Anderson R
FAU - Chevalier, J
AU  - Chevalier J
FAU - Kotin, P
AU  - Kotin P
FAU - Bernstein, D M
AU  - Bernstein DM
FAU - Thevenaz, P
AU  - Thevenaz P
FAU - Glass, L R
AU  - Glass LR
FAU - Miiller, W C
AU  - Miiller WC
FAU - Hesterberg, T W
AU  - Hesterberg TW
LA  - eng
PT  - Journal Article
PL  - England
TA  - Inhal Toxicol
JT  - Inhalation toxicology
JID - 8910739
EDAT- 1995/01/01 00:00
MHDA- 1995/01/01 00:01
CRDT- 2011/05/05 06:00
PHST- 2011/05/05 06:00 [entrez]
PHST- 1995/01/01 00:00 [pubmed]
PHST- 1995/01/01 00:01 [medline]
AID - 10.3109/08958379509015208 [doi]
PST - ppublish
SO  - Inhal Toxicol. 1995;7(4):425-67. doi: 10.3109/08958379509015208.