Garden Grove, California – The toxic chemical leaking from a large tank in Garden Grove, California, is methyl methacrylate, or MMA, a highly hazardous substance that can pose significant health and safety risks depending on exposure, officials said.
Methyl methacrylate is used to produce break-resistant acrylic glass, paints, adhesives, resins, and plastics. Authorities describe it as highly toxic and highly flammable, with the potential to become explosive under certain conditions.
Orange County fire officials said the incident involved a large amount of the chemical, with estimates suggesting up to 7,000 gallons leaked from the tank. The Orange County Fire Authority notes that incidents involving this type of chemical are rare, with limited case studies available to guide response efforts.
“It’s a respiratory irritant, so it can start out very mild, but it can progress to a point where, yes, you’ll probably need to be hospitalized, if not more,” said Chief Nick Freeman of the Orange County Fire Authority.
Health experts say exposure can occur through inhalation or direct contact. Short-term exposure may cause skin, eye and respiratory irritation, while high concentrations can cause more serious effects.
“At very high levels, it can cause severe shortness of breath and hospitalization, and that’s where we really need everyone to heed all evacuation orders,” said Dr. Regina Chinseo Kwong, Orange County’s deputy health officer.
Officials stressed that MMA vapor is heavier than air, meaning it could settle near the ground if released, increasing risks in surrounding areas.
First responders are also monitoring the possibility of a dangerous airborne plume, although its size and concentration remain uncertain.
“We don’t know, we don’t know in terms of whether there is a plume, how heavy the plume is and the concentration of the material in that plume,” Chenseo Kwong said. “If that happens, we want everyone to be away from the area we have created to protect everyone’s health,” he added.
Doctors said that the effect of the chemical depends largely on the level and duration of exposure. In addition to lung and skin irritation, sudden contact can affect multiple organs, while prolonged or slow leaks may lead to long-term health effects.
People working with methyl methacrylate are usually required to wear protective equipment such as goggles and respirators due to its hazardous nature.
While research on long-term health effects is still limited, officials say methyl methacrylate is not currently considered a carcinogen.
The substance can also affect animals, including birds, although effects may vary by species.
No injuries or deaths were reported.
Authorities continue to stress the importance of following evacuation orders as crews work to contain the leak and prevent ignition, citing the flammability of the chemical and the limited experience responders have in incidents of this magnitude.
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