# NIOSH Pocket Guide to Chemical Hazards
Propylene oxide | CAS 75-56-9
C3H6O | RTECS TZ2975000
Synonyms & Trade Names 1,2-Epoxy propane; Methyl ethylene oxide; Methyloxirane; Propene oxide; 1,2-Propylene oxide | DOT ID & Guide 1280 127P
Exposure Limits | NIOSH REL: Ca See Appendix A
OSHA PEL†: TWA 100 ppm (240 mg/m3)
IDLH Ca [400 ppm] | Conversion 1 ppm = 2.38 mg/m3
Physical Description Colorless liquid with a benzene-like odor. [Note: A gas above 94°F.]
MW: 58.1 | BP: 94°F | FRZ: -170°F | Sol: 41%
VP: 445 mmHg | IP: 9.81 eV |  | Sp.Gr: 0.83
Fl.P: -35°F | UEL: 36% | LEL: 2.3% |
Class IA Flammable Liquid: Fl.P. below 73°F and BP below 100°F.
Incompatibilities & Reactivities Anhydrous metal chlorides; iron; strong acids, caustics & peroxides [Note: Polymerization may occur due to high temperatures or contamination with alkalis, aqueous acids, amines & acidic alcohols.]
Measurement Methods NIOSH 1612; OSHA 88
Personal Protection & Sanitation Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When contaminated Remove: When wet (flammable) Change: No recommendation Provide: Quick drench | First Aid (See procedures) Eye: Irrigate immediately Skin: Water flush immediately Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations NIOSH At concentrations above the NIOSH REL, or where there is no REL, at any detectable concentration: (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 (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, respiratory system; skin blisters, burns; [potential occupational carcinogen]
Target Organs Eyes, skin, respiratory system Cancer Site [in animals: nasal tumors]
See also: INTRODUCTION