# NIOSH Pocket Guide to Chemical Hazards
Phthalic anhydride | CAS 85-44-9
C6H4(CO)2O | RTECS TI3150000
Synonyms & Trade Names 1,2-Benzenedicarboxylic anhydride; PAN; Phthalic acid anhydride | DOT ID & Guide 2214 156
Exposure Limits | NIOSH REL: TWA 6 mg/m3 (1 ppm)
OSHA PEL†: TWA 12 mg/m3 (2 ppm)
IDLH 60 mg/m3 | Conversion 1 ppm = 6.06 mg/m3
Physical Description White solid (flake) or a clear, colorless, mobile liquid (molten) with a characteristic, acrid odor.
MW: 148.1 | BP: 563°F | MLT: 267°F | Sol: 0.6%
VP: 0.0015 mmHg | IP: 10.00 eV |  | Sp.Gr: 1.53 (Flake) 1.20 (Molten)
Fl.P: 305°F | UEL: 10.5% | LEL: 1.7% |
Combustible Solid
Incompatibilities & Reactivities Strong oxidizers, water [Note: Converted to phthalic acid in hot water.]
Measurement Methods NIOSH S179 (II-3); OSHA 90
Personal Protection & Sanitation Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When contaminated Remove: When wet or contaminated Change: Daily | First Aid (See procedures) Eye: Irrigate immediately Skin: Soap wash promptly Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations NIOSH Up to 30 mg/m3: (APF = 5) Any dust and mist respirator* Up to 60 mg/m3: (APF = 10) Any dust and mist respirator except single-use and quarter-mask respirators*/(APF = 50) Any air-purifying, full-facepiece respirator with a high-efficiency particulate filter/(APF = 25) Any powered, air-purifying respirator with a dust and mist filter*/(APF = 10) Any supplied-air respirator*/(APF = 50) Any self-contained breathing apparatus 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 with a high-efficiency particulate filter/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, upper respiratory system; conjunctivitis; nasal ulcer bleeding; bronchitis, bronchial asthma; dermatitis; in animals: liver, kidney damage
Target Organs Eyes, skin, respiratory system, liver, kidneys
See also: INTRODUCTION