Agent Name

Kaolin

CAS Number

1332-58-7

Major Category

Mineral Dusts

Synonyms

China clay; Clay; Hydrated aluminum silicate; Hydrite; Porcelain clay [Note: Main constituent of Kaolin is Kaolinite (Al2Si2O5(OH)4).]; [NIOSH]

Category

Other Mineral Dusts

Description

White, yellow, or grayish powder; Darkens & develops clay-like odor when moistened; [NIOSH]

Sources/Uses

Used to manufacture refractory bricks and fibers; Used as an absorbent and as a filler in paints, plastics, and pharmaceuticals; [Rosenstock, p. 511] Also used to produce paper pulp, paper, rubber, wall tiles, and sanitary ware; [Rom, p. 531] 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]

Comments

Kaolin ores may contain mica and silica. Kaolin workers may develop a simple or complicated pneumconiosis with lung opacities and restrictive or mixed pattern on spirometry. [Sullivan, p. 544] Kaolin pneumoconiosis has been reported in miners, millers, and end users. [Rosenstock, p. 411] The highest exposures have been found in workers who process the clay (dry, mill, or load) rather than in end users. A study published in 1988 of 2000 U.S. kaolin workers found a prevalence for simple and complicated pneumoconiosis of 3.2% and 0.63%, respectively. [Rom, p. 531-2]

Exposure Assessment
Skin Designation (ACGIH)

Insufficient data

TLV (ACGIH)

2 mg/m3, respirable fraction

PEL (OSHA)

15 mg/m3(total dust), 5 mg/m3(respirable fraction)

Adverse Effects
Fibrogenic

Yes

ACGIH Carcinogen

Not Classifiable

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