What Is Methyl Methacrylate (MMA)? Uses, Hazards, and Exposure Symptoms

Methyl methacrylate (MMA) is a colorless, flammable liquid monomer used to make acrylic plastics and resins — most notably polymethyl methacrylate (PMMA), the rigid clear plastic sold under names like Plexiglas and Lucite, as well as adhesives, coatings, paints, and dental and medical materials. It is the chemical involved in the Garden Grove tank incident.

This page summarizes what regulatory and health agencies say about it. It is general information, not medical advice.

Key facts at a glance

• Chemical name: methyl methacrylate (MMA), methyl 2-methylpropenoate
• Formula: C5H8O2
• CAS number: 80-62-6
• Appearance / odor: colorless liquid with a sharp, fruity odor
• Primary use: monomer for polymethyl methacrylate (PMMA / "acrylic" plastics)
• Hazard classification (per NIOSH): flammable liquid; irritant to eyes, skin, and respiratory system

For the authoritative chemical card, see the NIOSH Pocket Guide entry.

What MMA is, and what it's used for

MMA is the small "building-block" molecule (a monomer) that, when linked into long chains (polymerized), becomes PMMA — the rigid, transparent plastic behind acrylic sheet, light fixtures, signage, aquarium panels, paint and adhesive chemistry, and dental and medical materials. In its liquid form it is flammable, and its vapors can travel.

Documented hazards

According to the NIOSH Pocket Guide, MMA is an irritant to the eyes, skin, and respiratory system. Occupational exposure limits exist precisely because inhaling its vapor at sufficient concentration can irritate the airways. For the authoritative detail — exposure limits, first aid, and protective measures — see the NIOSH Pocket Guide entry and the OSHA occupational chemical database.

Exposure symptoms

Commonly reported irritant effects include watering or stinging eyes, nose and throat irritation, coughing, and headache. People with asthma or other respiratory conditions may be more sensitive. Symptoms can appear during or shortly after exposure.

For the detailed CDC/NIOSH safety profile — exposure limits, target organs, first aid, and the flammable-vapor hazard — see CDC/NIOSH MMA exposure symptoms & flammable vapor.

For health questions specific to you, consult a clinician and the official toxicology sources above rather than relying on general summaries.

What to do

Check current air quality for your area on AirNow and review whether the air is safe near this incident. If you believe you were exposed, consider documenting it and seeking medical evaluation.