Agent Name

Mica, respirable dust

CAS Number

12001-26-2

Major Category

Mineral Dusts

Synonyms

Biotite; Lepidolite; Margarite; Muscovite; Phlogopite; Roscoelite; Zimmwaldite; [NIOSH]

Category

Other Mineral Dusts

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]

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]

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] "Occupational exposure to mica dust is responsible for diffuse infiltrative lung disease by overload processes." [Reference #2]

Reference Link

Pneumoconiosis after sericite inhalation. [Occup Environ Med. 2005] - PubMed Result

Exposure Assessment
Skin Designation (ACGIH)

Insufficient data

Bioaccumulates

Yes

TLV (ACGIH)

3 mg/m3, respirable fraction

PEL (OSHA)

20 mppcf, < 1% crystalline silica

IDLH (NIOSH)

1500 mg/m3

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.

Reference Link

Mica dust and pneumoconiosis: example of a pure occupational exposure in a muscovite milling unit.

Adverse Effects
Fibrogenic

Yes

Links to Other NLM Databases
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Related Information in HazMap
Diseases

Occupational diseases associated with exposure to this agent:

Processes

Industrial Processes with risk of exposure: