Mica

Agent Name
Mica
CAS Number
12001-26-2
Major Category
Mineral Dusts
Synonyms
Biotite; Lepidolite; Margarite; Muscovite; Phlogopite; Roscoelite; Zimmwaldite; [NIOSH] Mica, respirable dusts;
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. Used as a filler for paint, cement, asphalt, and insulation material for electrical cables; Also used in drilling muds, cosmetics, and vacuum tubes/condensers; [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
"However, information is sufficient to establish that mica pneumoconiosis is most commonly seen in individuals who have had 10-20 years of exposure to mica, after a latency period of several decades. . . . In one study which examined the relationship between mica concentration, duration of exposure, and onset of disease, it was reported that no cases were observed among workers exposed to mica dusts at concentrations of 1.8 mg/m3 or less, irrespective of exposure duration." [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 pneumoconiosis 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]
Biomedical References

Exposure Assessment

Skin Designation (ACGIH)
Insufficient data
Bioaccumulates
Yes
TLV (ACGIH)
0.1 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.

Adverse Effects

Fibrogenic
Yes

Diseases, Processes, and Activities Linked to This Agent

Diseases

Occupational diseases associated with exposure to this agent:

Processes

Industrial Processes with risk of exposure: