| Agent Name |
Mica, respirable dust |
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| CAS Number |
12001-26-2 |
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| Major Category |
Mineral Dusts |
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| Synonyms |
Biotite; Lepidolite; Margarite; Muscovite; Phlogopite; Roscoelite; Zimmwaldite; [NIOSH] |
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| Category |
Other Mineral Dusts |
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| Description |
Colorless, odorless flakes or sheets of hydrous silicates; [NIOSH] Crystalline silica not bound to other minerals is "free" silica. Silicates are minerals in which silicon and oxygen are combined with other elements. [Rom, p. 364] |
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| Sources/Uses |
Mica, mainly muscovite and phlogopite, contains less than 1% quartz. Other species of mica are biotite, lepidolite, zimmwaldite, and roscoelite. Mica is used in shingles, wallpaper, and insulation. It is also used in oil well drilling, mold releasing, filtering, and in manufacturing heat-resistant windows. [ACGIH] Sericite is a variety of white mica; it is similar to muscovite and is used as a filler, carrier, and lubricant; [Reference #1] |
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| Comments |
Mica workers in India with 18 years of exposure to 20 mppcf showed evidence of mild pneumoconiosis on chest x-rays. [ACGIH] A mixed-dust pneumoconiosis reported in mica miners appears to be related to free silica contamination of ores. [Rosenstock, p. 412] The existence of a mica pneumoconiosis is controversial and is based on a few case reports. [Hendrick, p. 170] Three cases of pneumoconioses were diagnosed among sericite plant workers in Parana, Brazil. 44 workers with an average 13.5 years of exposure were examined. 52% of workers had chest x-ray opacities, and 18% had reduced FEV1 on pulmonary function testing. [Reference #1] |
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| Reference Link |
Pneumoconiosis after sericite inhalation. [Occup Environ Med. 2005] - PubMed Result |
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| Exposure Assessment |
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| Skin Designation (ACGIH) |
No |
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| Bioaccumulates |
Yes |
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| TLV (ACGIH) |
3 mg/m3, respirable fraction |
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| PEL (OSHA) | 20 mppcf, < 1% crystalline silica |
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| IDLH (NIOSH) |
1500 mg/m3 |
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| Excerpts from Documentation for IDLHs |
Basis for revised IDLH: The available toxicological data contain no evidence that an acute exposure to a high concentration of mica would impede escape or cause any irreversible health effects within 30 minutes. |
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| Adverse Effects |
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| Fibrogenic |
Yes |
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| Links to Other NLM Databases |
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| Health Studies |
Human Health Effects from Hazardous Substances Data Bank: MICA
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