# NIOSH Pocket Guide to Chemical Hazards
Propionic acid | CAS 79-09-4
CH3CH2COOH | RTECS UE5950000
Synonyms & Trade Names Carboxyethane, Ethanecarboxylic acid, Ethylformic acid, Metacetonic acid, Methyl acetic acid, Propanoic acid | DOT ID & Guide 1848 132
Exposure Limits | NIOSH REL: TWA 10 ppm (30 mg/m3) ST 15 ppm (45 mg/m3)
OSHA PEL†: none
IDLH N.D. | Conversion 1 ppm = 3.03 mg/m3
Physical Description Colorless, oily liquid with a pungent, disagreeable, rancid odor. [Note: A solid below 5°F.]
MW: 74.1 | BP: 286°F | FRZ: 5°F | Sol: Miscible
VP: 3 mmHg | IP: 10.24 eV |  | Sp.Gr: 0.99
Fl.P: 126°F | UEL: 12.1% | LEL: 2.9% |
Class II Combustible Liquid: Fl.P. at or above 100°F and below 140°F.
Incompatibilities & Reactivities Alkalis, strong oxidizers (e.g., chromium trioxide) [Note: Corrosive to steel.]
Measurement Methods None available
Personal Protection & Sanitation Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When contaminated Remove: When wet or contaminated Change: No recommendation Provide: Eyewash, Quick drench | First Aid (See procedures) Eye: Irrigate immediately Skin: Water flush immediately Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations To be added later
Exposure Routes inhalation, skin absorption, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, nose, throat; blurred vision, corneal burns; skin burns; abdominal pain, nausea, vomiting
Target Organs Eyes, skin, respiratory system
See also: INTRODUCTION