September 2005

NIOSH Publication Number 2005-149

Search the Pocket Guide 

Enter search terms separated by spaces. 

Methylene bisphenyl isocyanate 

Synonyms & Trade Names 4,4'-Diphenylmethane diisocyanate; MDI; Methylene bis(4-phenyl isocyanate); Methylene 

di-p-phenylene ester of isocyanic acid 

CAS No. 101-68-8 RTECS 

No. NQ9350000

(/nioshrtecs/NQ8EAB70.html) 

DOT ID & Guide

Formula CH2

(C6H4NCO)2

Conversion 1 ppm = 

10.24 mg/m 

IDLH 75 mg/m 

See: 101688 (/niosh/idlh/101688.html) 

Exposure Limits

NIOSH REL : TWA 0.05 mg/m (0.005 ppm) C 

0.2 mg/m (0.020 ppm) [10-minute] 

OSHA PEL : C 0.2 mg/m (0.02 ppm) 

Measurement Methods

NIOSH 5521 (/niosh/docs/2003-154/pdfs/5521.pdf) , 5522 

(/niosh/docs/2003-154/pdfs/5522.pdf) , 5525 (/niosh/docs/2003-

154/pdfs/5525.pdf) ; 

OSHA 18

(http://www.osha.gov/dts/sltc/methods/organic/org018/org018.html) 

See: NMAM (/niosh/docs/2003-154/) or OSHA Methods

(http://www.osha.gov/dts/sltc/methods/index.html) 

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.]

Exposure Routes inhalation, ingestion, skin and/or eye contact 

Symptoms irritation eyes, nose, throat; resp sensitization; cough, pulmonary secretions, chest pain, dyspnea 

(breathing difficulty); asthma 

Target Organs Eyes, respiratory system 

Personal Protection/Sanitation (See protection 

codes (protect.html) ) 

First Aid (See procedures (firstaid.html) ) 

Eye: Irrigate immediately 

3

3

3

3

3

CDC - NIOSH Pocket Guide to Chemical Hazards - Methylene bisphenyl isocyanate Page 1 of 2

http://www.cdc.gov/niosh/npg/npgd0413.html 7/29/2010
Page last reviewed: February 3, 2009

Page last updated: February 3, 2009

Content source: National Institute for Occupational Safety and Health (NIOSH) Education and Information Division

Centers for Disease Control and Prevention 1600 Clifton Rd. Atlanta, GA 30333, USA 

800-CDC-INFO (800-232-4636) TTY: (888) 232-6348, 24 Hours/Every Day - cdcinfo@cdc.gov

Skin: Prevent skin contact 

Eyes: Prevent eye contact 

Wash skin: When contaminated 

Remove: When wet or contaminated 

Change: Daily 

Skin: Soap wash immediately 

Breathing: Respiratory support 

Swallow: Medical attention immediately

Respirator Recommendations

NIOSH

Up to 0.5 mg/m : 

(APF = 10) Any supplied-air respirator* 

Up to 1.25 mg/m : 

(APF = 25) Any supplied-air respirator operated in a continuous-flow mode* 

Up to 2.5 mg/m : 

(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/m : 

(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 pressuredemand 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 an N100, R100, or P100 filter. 

Click here (pgintrod.html#nrp) for information on selection of N, R, or P filters.

Any appropriate escape-type, self-contained breathing apparatus 

Important additional information about respirator selection (pgintrod.html#mustread) 

See also: INTRODUCTION (/niosh/npg/pgintrod.html) See ICSC CARD: 0298 (/niosh/ipcsneng/neng0298.html) 

 See MEDICAL TESTS: 0147 (/niosh/docs/2005-110/nmed0147.html) 

3

3

3

3

CDC - NIOSH Pocket Guide to Chemical Hazards - Methylene bisphenyl isocyanate Page 2 of 2

http://www.cdc.gov/niosh/npg/npgd0413.html 7/29/2010