# NIOSH Pocket Guide to Chemical Hazards
Methylene bisphenyl isocyanate | CAS 101-68-8
CH2(C6H4NCO)2 | RTECS NQ9350000
Synonyms & Trade Names 4,4'-Diphenylmethane diisocyanate; MDI; Methylene bis(4-phenyl isocyanate); Methylene di-p-phenylene ester of isocyanic acid | DOT ID & Guide 2489 156
Exposure Limits | NIOSH REL: TWA 0.05 mg/m3 (0.005 ppm) C 0.2 mg/m3 (0.020 ppm) [10-minute]
OSHA PEL: C 0.2 mg/m3 (0.02 ppm)
IDLH 75 mg/m3 | Conversion 1 ppm = 10.24 mg/m3
Physical Description White to light-yellow, odorless flakes. [Note: A liquid above 99°F.]
MW: 250.3 | BP: 597°F | MLT: 99°F | Sol: 0.2%
VP(77°F): 0.000005 mmHg | IP: ? |  | Sp.Gr: 1.23 (Solid at 77°F) 1.19 (Liquid at 122°F)
Fl.P: 390°F | UEL: ? | LEL: ? |
Combustible Solid
Incompatibilities & Reactivities Strong alkalis, acids, alcohol [Note: Polymerizes at 450°F.]
Measurement Methods NIOSH 5521, 5522; OSHA 18
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 immediately Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations NIOSH Up to 0.5 mg/m3: (APF = 10) Any supplied-air respirator* Up to 1.25 mg/m3: (APF = 25) Any supplied-air respirator operated in a continuous-flow mode* Up to 2.5 mg/m3: (APF = 50) Any self-contained breathing apparatus with a full facepiece/(APF = 50) Any supplied-air respirator with a full facepiece Up to 75 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 (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 eyes, nose, throat; respiratory sensitization; cough, pulmonary secretions, chest pain, dyspnea (breathing difficulty); asthma
Target Organs Eyes, respiratory system
See also: INTRODUCTION