| Agent Name |
Silica, amorphous |
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| CAS Number |
61790-53-2; 68895-54-9; 112926-00-8; 69012-64-2; 60676-86-0 |
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| Formula |
O2-Si |
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| Major Category |
Mineral Dusts |
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| Synonyms |
Diatomaceous earth, containing < 1% crystalline silica; Diatomaceous silica; Diatomite; Precipitated amorphous silica; Silica gel; Silicon dioxide (amorphous); [NIOSH] |
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| Category |
Other Mineral Dusts |
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| Description |
Transparent to gray, odorless powder. [Note: Amorphous silica is the non-crystalline form of SiO2.]; [NIOSH] |
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| Sources/Uses |
Used as a filler in rubber products, paints, animal feeds, pesticides, insulation materials, and cosmetics; [Rom, p. 527] |
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| Comments |
Silica, amorphous (7631-86-9) is "not classifiable as to carcinogenicity to humans." [IARC] Documentation and TLV withdrawn in 2006 because of insufficient data; [ACGIH] The main problem in assessing the risk of exposure to diatomaceous earth is its varying degree of contamination with crystalline silica. While the natural version usually contains about 1%, up to 60% may be present in flux-calcined amorphous silica. [Rom, p. 527] |
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| Exposure Assessment |
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| Skin Designation (ACGIH) |
Not evaluated |
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| Bioaccumulates |
Yes |
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| PEL (OSHA) | 20 mppcf(diatomaceous earth uncalcined, precipitated silica and silica gel), 30 mg/m3/%SiO2+2, total dust, 10 mg/m3/%SiO2+2, respir. dust(silica fused) |
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| MAK |
4 mg/m3, inhal. fraction(diatomaceous earth uncalcined, precipitated silica, and silica gel), 0.3 mg/m3, respir. fraction(diatomaceous earth calcined, silica fume, and silica fused) |
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| IDLH (NIOSH) |
3000 mg/m3 |
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| Adverse Effects |
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| Fibrogenic |
Yes |
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| IARC Carcinogen |
Not Classifiable |
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| Links to Other NLM Databases |
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| Health Studies |
Human Health Effects from Hazardous Substances Data Bank: AMORPHOUS SILICA
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