September 2010
NIOSH Publication Number 2010-168c

Plaster of Paris

Synonyms & Trade Names
Calcium sulfate hemihydrate, Dried calcium sulfate, Gypsum hemihydrate, Hemihydrate gypsum [Note: Plaster of Paris is the hemihydrate form of Calcium Sulfate & Gypsum is the dihydrate form.]
CAS No.
26499-65-0
RTECS No.
TP0700000
DOT ID & Guide
Formula
CaSO4 • 0.5H2O
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 0600
Physical Description
White or yellowish, finely divided, odorless powder.
MW:
145.2
BP:
?		 MLT: 325°F (Loses H2O) Sol(77°F): 0.3%
VP:
0 mmHg (approx)
IP:
NA
Sp.Gr:
2.5
Fl.P:
NA
UEL:
NA
LEL:
NA
Noncombustible Solid
Incompatibilities & Reactivities
Moisture, water [Note: Hygroscopic (i.e., absorbs moisture from the air). Reacts with water to form Gypsum.]
Exposure Routes
inhalation, ingestion, skin and/or eye contact
Symptoms
irritation eyes, skin, mucous membrane, respiratory system; cough
Target Organs
Eyes, skin, respiratory system
Personal Protection/Sanitation
(See protection codes)
Skin: No recommendation
Eyes: No recommendation
Wash skin: No recommendation
Remove: No recommendation
Change: No recommendation
First Aid
(See procedures)
Eye: Irrigate immediately

Breathing: Respiratory support
Swallow: Medical attention immediately
Respirator Recommendations

Not available.

Important additional information about respirator selection

See also: INTRODUCTION   See ICSC CARD: 1217