Emerson Rosemount OCX8800A - Page 309

of cristobalite present will depend on the temperature and length of time in
service.
See Special protection information for permissible exposure levels.
Special toxic effects
The existing toxicology and epidemiology data bases for refractory ceramic fibers
(RCFs) are still prelimnary. Information will be updated as studies are completed
and reviewed. The following is a review of the results to date:
Epidemiology
At this time, there are no known published reports demonstrating negative health
outcomes of workers exposed to RCF. Epidemiologic investigation of RCF
production workers are ongoing.
1. There is no evidence of any fibrotic lung disease (interstitial fibrosis)
whatsoever on x-ray.
2. There is no evidence of any lung disease among those employees exposed
to RCF that had never smoked.
3. A statistical trend was observed in the exposed population between the
duration of exposure to RCF and a decrease in some measures of
pulmonary function. These observations are clinically insignificant. In other
words, if these observations were made on an individual employee, the
results would be interpreted as being within the normal range.
4. Pleural plaques (thickening along the chest wall) have been observed in a
small number of employees who had a long duration of employment. There
are several occupational and non-occupational causes for pleural plaque. It
should be noted that plaques are not pre-cancer, nor are they associated
with any measurable effect in lung function.
Toxicology
A number of studies on the health effects of inhalation exposure of rats and
hamsters are available. Rats were exposed to RCF in a series of life-time nose-only
inhalation studies. The animals were exposed to 30, 16, 9, and 3 mg/m
3
, which
corresponds with approximately 200, 150, 75, and 25 fibers/cc.
Animals exposed to 30 and 16 mg/m
3
were observed to have developed a pleural
and parenchymal fibrosis; animals exposed to 9 mg/m
3
had developed a mild
parenchymal fibrosis; animals exposed to the lowest dose were found to have the
response typically observed any time a material is inhaled into the deep lung.
While a statistically significant increase in lung tumors was observed following
exposure to the highest dose, there were no excess lung cancers at the other
doses. Two rats exposed to 30 mg/m
3
and one rat exposed to 9 mg/m
3
developed
masotheliomas.
The International Agency for Research on Cancer (IARC) reviewed the
carcinogenicity data on man-made vitreous fibers (including ceramic fiber,
glasswool, rockwool, and slagwool) in 1987. IARC classified ceramic fibers, fibrous
glasswool, and mineral wool (rockwool and slagwool) as possible human
carcinogens (Group 2B).
Manual
Safety data
00809-0500-4880 December 2022
Rosemount OCX8800A 309