NIOSH Publication No. 2005-151:

NIOSH Pocket Guide to Chemical Hazards

September 2005

Phosphoric acid

CAS
7664-38-2

H3PO4

RTECS
TB6300000
Synonyms & Trade Names

Orthophosphoric acid, Phosphoric acid (aqueous), White phosphoric acid
DOT ID & Guide
1805 / 154 (liquid or solution)
3453 / 154 (solid)

Exposure
Limits

NIOSH REL: TWA 1 mg/m3 ST 3 mg/m3
OSHA PEL: TWA 1 mg/m3
IDLH
1000 mg/m3 See: 7664382
Conversion
Physical Description
Thick, colorless, odorless, crystalline solid. [Note: Often used in an aqueous solution.]
MW: 98.0
BP: 415°F
MLT: 108°F
Sol: Miscible
VP: 0.03 mmHg
IP: ?

Sp.Gr(77°F): 1.87 (pure) 1.33 (50% solution)
Fl.P: NA
UEL: NA
LEL: NA

Noncombustible Solid
Incompatibilities & Reactivities

Strong caustics, most metals [Note: Readily reacts with metals to form flammable hydrogen gas. DO NOT MIX WITH SOLUTIONS CONTAINING BLEACH OR AMMONIA.]
Measurement Methods
NIOSH 7903; OSHA ID165SG
See: NMAM or OSHA Methods
Personal Protection & Sanitation
(See protection)
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated
Remove: When wet or contaminated
Change: Daily
Provide: Eyewash (>1.6%), Quick drench (>1.6%)
First Aid
(See procedures)
Eye: Irrigate immediately
Skin: Water flush immediately
Breathing: Respiratory support
Swallow: Medical attention immediately
Respirator Recommendations
NIOSH/OSHA
Up to 25 mg/m3:
(APF = 25) Any supplied-air respirator operated in a continuous-flow mode*
Up to 50 mg/m3:
(APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter. Click here for information on selection of N, R, or P filters.
(APF = 50) Any self-contained breathing apparatus with a full facepiece
(APF = 50) Any supplied-air respirator with a full facepiece
Up to 1000 mg/m3:
(APF = 2000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode
Emergency or planned entry into unknown concentrations or IDLH conditions:
(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode
(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus
Escape:
(APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter. Click here for information on selection of N, R, or P filters./Any appropriate escape-type, self-contained breathing apparatus
Important additional information about respirator selection
Exposure Routes
inhalation, ingestion, skin and/or eye contact
Symptoms
Irritation eyes, skin, upper respiratory system; eye, skin, burns; dermatitis
Target Organs
Eyes, skin, respiratory system
See also: INTRODUCTION   See ICSC CARD: 1008