US Health and Human Services…
How can synthetic vitreous fibers affect my health?
When synthetic vitreous fibers are suspended in air they can cause irritation of the eyes, the nose and throat, and parts of the lung. When these fibers contact the skin, they may also cause irritation. These effects are reversible and disappear shortly after exposure stops.
Animal studies show that repeatedly breathing air containing a lot of synthetic vitreous fibers can lead to inflammation and fibrosis of the lung. If pulmonary inflammation continues over a long period of time, a slow build up of scar tissue may occur in the lungs and in the membrane encasing the lungs called the pleura. This effect is called pulmonary fibrosis or pleural fibrosis. Glass fibers commonly used in home insulation materials did not cause fibrosis in animals, but refractory ceramic fibers did.
You are unlikely to develop long-term pulmonary inflammation or pulmonary fibrosis from synthetic vitreous fibers, unless you are exposed to very dusty conditions daily for many years. Studies of workers from factories that make synthetic vitreous fibers used in home insulation materials did not find abnormal numbers of cases of long-term pulmonary inflammation, breathing problems, or changes in chest x-rays. Some workers who made refractory ceramic fibers showed changes in chest x-rays that are called pleural plaques, but their ability to breathe was normal. Pleural plaques are small areas of very mildly scarred pleural tissue.
How likely are synthetic vitreous fibers to cause cancer?
You are unlikely to develop cancer from breathing in air with small amounts of synthetic vitreous fibers. Studies of workers from factories that make synthetic vitreous fibers have not found increased rates of lung cancer or cancer of the pleura, called mesothelioma. Animals exposed for life to air containing refractory ceramic fibers showed increased rates of lung cancer and mesothelioma, but animals exposed to insulation glass wools and stone wools did not.
The International Agency for Research on Cancer (IARC) determined that insulation glass wool, stone wool, and slag wool, and continuous filament glass are not classifiable as to carcinogenicity to humans because of the inadequate evidence of carcinogenicity in humans and the relatively low biopersistence of these materials. IARC determined that refractory ceramic fibers are possibly carcinogenic to humans because of their relatively high biopersistence and the findings of cancer in animals that repeatedly breathed in high levels of refractory ceramic fibers. The EPA has classified refractory ceramic fibers as a probable human carcinogen.