Skip directly to local search Skip directly to A to Z list Skip directly to navigation Skip directly to site content Skip directly to page options
CDC Home

Enter search terms separated by spaces.

Silicon

Synonyms & Trade Names
Elemental silicon [Note: Does not occur freely in nature, but is found in silicon dioxide (silica) and in various silicates.]
CAS No.
7440-21-3
RTECS No.
VW0400000
DOT ID & Guide
1346 170 (amorphous powder)
Formula
Si
Conversion
IDLH
N.D.
See: IDLH INDEX
Exposure Limits
NIOSH REL
: TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)
OSHA PEL
†: TWA 15 mg/m3 (total) TWA 5 mg/m3 (resp)
Measurement Methods

NIOSH 0500 , 0600
See: NMAM or OSHA Methods
Physical Description
Black to gray, lustrous, needle-like crystals. [Note: The amorphous form is a dark-brown powder.]
MW:
28.1
BP:
4271°F		 MLT: 2570°F
Sol:
Insoluble
VP:
0 mmHg (approx)
IP:
NA
Sp.Gr(77°F): 2.33
Fl.P:
NA
UEL:
NA
LEL:
NA
MEC:
160 g/m3
Combustible Solid in powder form.
Incompatibilities & Reactivities
Chlorine, fluorine, oxidizers, calcium, cesium carbide, alkaline carbonates
Exposure Routes
inhalation, ingestion, skin and/or eye contact
Symptoms
irritation eyes, skin, upper respiratory system; cough
Target Organs
Eyes, skin, respiratory system
Personal Protection/Sanitation
(See protection codes)
Skin: No recommendation
Eyes: Prevent eye contact
Wash skin: No recommendation
Remove: No recommendation
Change: No recommendation
First Aid
(See procedures)
Eye: Irrigate immediately

Breathing: Fresh air
Swallow: Medical attention immediately
Respirator Recommendations

Not available.

Important additional information about respirator selection

See also: INTRODUCTION   See ICSC CARD: 1508
 

Order NIOSH Publications

Contact Us:
USA.gov: The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30333, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO