# NIOSH Pocket Guide to Chemical Hazards
Maleic anhydride | CAS 108-31-6
C4H2O3 | RTECS ON3675000
Synonyms & Trade Names cis-Butenedioic anhydride; 2,5-Furanedione; Maleic acid anhydride; Toxilic anhydride | DOT ID & Guide 2215 156
Exposure Limits | NIOSH REL: TWA 1 mg/m3 (0.25 ppm)
OSHA PEL: TWA 1 mg/m3 (0.25 ppm)
IDLH 10 mg/m3 | Conversion 1 ppm = 4.01 mg/m3
Physical Description Colorless needles, white lumps, or pellets with an irritating, choking odor.
MW: 98.1 | BP: 396°F | MLT: 127°F | Sol: Reacts
VP: 0.2 mmHg | IP: 9.90 eV |  | Sp.Gr: 1.48
Fl.P: 218°F | UEL: 7.1% | LEL: 1.4% |
Combustible Solid, but may be difficult to ignite.
Incompatibilities & Reactivities Strong oxidizers, water, alkalis, metals, caustics & amines above 150°F [Note: Reacts slowly with water (hydrolyzes) to form maleic acid.]
Measurement Methods NIOSH 3512; OSHA 25, 86
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 | First Aid (See procedures) Eye: Irrigate immediately Skin: Soap wash immediately Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations NIOSH/OSHA Up to 10 mg/m3: (APF = 25) Any supplied-air respirator operated in a continuous-flow mode£/(APF = 50) Any self-contained breathing apparatus with a full facepiece/(APF = 50) Any supplied-air respirator with a full facepiece 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 (gas mask) with a chin-style, front- or back-mounted organic vapor canister having a high-efficiency particulate filter/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, ingestion, skin and/or eye contact
Symptoms Irritation nose, upper respiratory system; conjunctivitis; photophobia (abnormal visual intolerance to light), double vision; bronchial asthma; dermatitis
Target Organs Eyes, skin, respiratory system
See also: INTRODUCTION