NIOSH Pocket Guide to Chemical Hazards

o-Tolidine CAS 119-93-7
C14H16N2 RTECS DD1225000
Synonyms & Trade Names
4,4'-Diamino-3,3'-dimethylbiphenyl; Diaminoditolyl; 3,3'-Dimethylbenzidine; 3,3'-Dimethyl-4,4'-diphenyldiamine; 3,3'-Tolidine
DOT ID & Guide
NIOSH REL: Ca C 0.02 mg/m3 [60-minute] [skin] See Appendix A See Appendix C
OSHA PEL: See Appendix C
IDLH Ca [N.D.] Conversion
Physical Description
White to reddish crystals or powder. [Note: Darkens on exposure to air. Often used in paste or wet cake form. Used as a basis for many dyes.]
MW: 212.3
BP: 572°F
MLT: 264°F
Sol: 0.1%
VP: ?
IP: ?

Sp.Gr: ?
Fl.P: ?
UEL: ?
LEL: ?

Combustible Solid
Incompatibilities & Reactivities
Strong oxidizers
Measurement Methods
NIOSH 5013; OSHA 71
Personal Protection & Sanitation
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated/Daily
Remove: When wet or contaminated
Change: Daily
Provide: Eyewash, Quick drench
First Aid (See procedures)
Eye: Irrigate immediately
Skin: Soap 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 organic vapor canister having a high-efficiency particulate filter/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, skin absorption, ingestion, skin and/or eye contact
Symptoms Irritation eyes, nose; in animals: liver, kidney damage; [potential occupational carcinogen]
Target Organs Eyes, respiratory system, liver, kidneys

Cancer Site [in animals: liver, bladder & mammary gland tumors]