Synthetic vitreous fibers

Agent Name
Synthetic vitreous fibers
CAS Number
Varies; 142844-00-6
Major Category
Mineral Dusts
Mineral wool fiber; Manmade mineral fibers; Rock wool; Slag wool; Refractory ceramic fibers; Continuous filament glass fibers; Glass wool fibers; Rock wool fibers; Slag wool fibers; Special purpose glass fibers; [NIOSH]
Synthetic Vitreous Fibers
Produced by blowing steam or air through molten rock (rock wool) or various furnace slags that are by-products of metal smelting or refining processes (slag wool); [NIOSH] Occupational exposure occurs during manufacturing, processing, and installation. Continuous filament fibers are used in composite plastics and industrial fabrics. Glass, rock, and slag wools are used for insulation in buildings and around ducts and pipes. Refractory ceramic fibers are used in furnaces. [ACGIH] Refractory ceramic fibers (RCF): produced in the US since the early 1950s; Have insulating properties up to 2800 deg F. and used in industrial furnaces, and high temperature boilers, pipes, gaskets, and seals in the automotive, aerospace, and appliance industries; [PMID 16091350]
3 main groups of synthetic vitreous fibers: 1) glass wool (fiberglass or fibrous glass); 2) mineral wool (slag wool or rock wool); and 3) refractory ceramic fiber; [p. 335, Harber] Special purpose glass fibers and refractory ceramic fibers are classified as possible human carcinogens. Insulation glass wool, rock (stone) wool, and slag wool are not classifiable as to carcinogenicity to humans. [IARC] Continuous filament glass fibers = A4; Glass wool, rock wool, slag wool, special purpose fibers = A3; Refractory ceramic fibers (RCF) = A2; RCFs have been used since the 1970s, and studies have shown x-ray and lung function abnormalities in workers exposed for more than 20 years. Animal studies have shown that RCFs can cause lung fibrosis, pleural thickening, mesothelioma, and lung cancer. [ACGIH]; ". . . there is currently no conclusive evidence of any adverse respiratory disorder attributable to MMVF [man-made vitreous fibers] in man . . ." [Hendrick, p. 197] "Despite their intensely irritation effects on skin and mucous membranes, there is no firm evidence that these fibers produce lung fibrosis, pleural lesions, or nonspecific respiratory disease in humans. However, refractory ceramic fibers may enhance the effects of smoking in producing airway disease." [Murray, p. 1774] In a study of pulmonary function of US refractory ceramic fiber workers, "No consistent decline was observed longitudinally with exposure to RCF, although cross-sectional and longitudinal findings were discordant." [PMID 20798015]
Biomedical References

Exposure Assessment

Skin Designation (ACGIH)
5 mg/m3, inhal. fraction(continuous filament glass fibers), 1 respir. fiber/cc(glass wool,rock wool,slag wool,and special purpose glass fibers), 0.2 respir. fiber/cc(refractory ceramic fibers)

Adverse Effects

IARC Carcinogen
Possible (2b)
NTP Carcinogen
Anticipated human carcinogen
ACGIH Carcinogen
Confirmed Animal

Diseases, Processes, and Activities Linked to This Agent


Occupational diseases associated with exposure to this agent:


Industrial Processes with risk of exposure: