NIOSH Pocket Guide to Chemical Hazards

Methacrylic acid

CAS 79-41-4


RTECS OZ2975000
Synonyms & Trade Names
Methacrylic acid (glacial), Methacrylic acid (inhibited), alpha-Methacrylic acid, 2-Methylacrylic acid, 2-Methylpropenoic acid
DOT ID & Guide
2531 153P (inhibited)


NIOSH REL: TWA 20 ppm (70 mg/m3) [skin]
OSHA PEL: none
IDLH N.D. See: IDLH INDEX Conversion 1 ppm = 3.52 mg/m3
Physical Description
Colorless liquid or solid (below 61°F) with an acrid, repulsive odor.
MW: 86.1
BP: 325°F
FRZ: 61°F
Sol(77°F): 9%
VP: 0.7 mmHg
IP: ?

Sp.Gr: 1.02 (Liquid)
Fl.P(oc): 171°F
UEL: ?
LEL: ?

Class IIIA Combustible Liquid: Fl.P. at or above 140F and below 200F.
Incompatibilities & Reactivities
Oxidizers, elevated temperatures, hydrochloric acid [Note: Typically contains 100 ppm of the monomethyl ether of hydroquinone to prevent polymerization.]
Measurement Methods
See: NMAM or OSHA Methods
Personal Protection & Sanitation (See protection)
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated
Remove: When wet or contaminated
Change: Daily
Provide: Eyewash, Quick drench
First Aid (See procedures)
Eye: Irrigate immediately
Skin: Water flush immediately
Breathing: Respiratory support
Swallow: Medical attention immediately
Important additional information about respirator selection
Respirator Recommendations Not available.
Exposure Routes inhalation, skin absorption, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, mucous membrane; eye, skin burns
Target Organs Eyes, skin, respiratory system
See also: INTRODUCTION   See ICSC CARD: 0917