A potential explosion or chemical spill in Garden Grove involving the substance methyl methacrylate, or MMA, used in aerospace manufacturing, could cause serious harm to residents’ respiratory or nervous systems if they are exposed to it, experts said Friday, May 22.
Officials believe a compromised tank at the Garden Grove facility will explode or spill in the coming hours or days, although they aren’t sure when, and the threat has already triggered the evacuation of some 40,000 residents. If it explodes, it could produce a toxic cloud, officials said. A spill, while dangerous on its own, would create a mess near the site but without the far-reaching uncertainty, officials said.
Health authorities expanded the evacuation zone on Friday afternoon to prevent impacts of the risks posed by the substance in the event that there is a vapor, which can be a fruity and heavy smell.
“So no matter what happens with the situation, whether the polymer just leaks out and then just hardens, or it does explode and there is a vapor, you are safe as long as you are out of the zone that was determined to be an evacuation zone,” said Dr. Regina “C.K.” Chinsio-Kwong, an Orange County Health Officer.
Smelling the scent of the vapor does not necessarily mean that someone will experience symptoms, but authorities want to know if anyone does smell it in the air. So far, the South Coast AQMD has not reported detecting it in the air, Chinsio-Kwong said.
MMA is widely used, particularly in the plastics and aerospace industries, so the substance’s toxicity for humans is tracked pretty closely. It is, for now, known to be an irritant, particularly for the lungs and heart. But it is not, at this point, a known carcinogen in humans. That said, the toxicity in the event playing out in Garden Grove could ramp up quite a bit — and become lethal — if people are exposed to enough of the chemical.
Michael Kleinman, a professor at UC Irvine who teaches at the Joe C. Wen School of Population and Public Health, said “the real risk here is a sudden rupture.”
If large amounts of MMA are spilled from the vats or released into the air following a fire or explosion, he explained, the public could be in danger of illness or powerful irritation. The chemical is particularly tough on the human respiratory system and, depending on how much a person inhales, MMA can cause everything from sore throats and cough to dizziness, nausea and, at the highest levels, damage to the nervous system, Kleinman said.
Those most at risk are people who already struggle with respiratory issues, such as asthma and people who have worked with MMA have developed allergies to the chemical over time. That means people in some jobs — including plastics and aerospace manufacturing, and working in nail salons — could be primed for a negative reaction if they’re exposed in this event, Kleinman said.
An explosion or spillage of the chemical, the scenarios put forth by the Orange County Fire Authority as potential outcomes, both create problems, because MMA is heavier than air, Kleinman said. If it erupts as a fire or in an explosion, it would rise high into the air but rapidly reduce in concentration and be moved by wind patterns before slowly falling back to the ground. The exposure zone, in that scenario, is less easy to predict. If it spills, it would spread in large concentrations, low to the ground, probably for about a mile from the plant, he said. In that scenario it would be important for people to leave the area, he said.
Kleinman said the chemical poses a long-term environmental risk, as it is likely to reach the ground, from which it could eventually seep into the groundwater system. After that, the risk would rise or fall based on the level of contamination. In the air, the effects are less well known. In recent years, toxic events have transpired following rail accidents, and the long-term impact of those clouds, which involved different chemicals, are still being studied.
Kleinman said masks like those ubiquitous with the Covid pandemic wouldn’t help.
“Masks for covid were designed for protecting against particles. This is an organic vapor that would probably penetrate right through that,” he said. Emergency workers at the scene, he noted, would be wearing “respiratory protection with chemical filters,” which isn’t something available for most households.
In the short term, methyl methacrylate causes respiratory irritation, but little is known about the long-term effects of the substance on humans, Dr. Chinsio-Kwong, the Orange County Health Officer, said at a press conference Friday.
“In this situation, our biggest concern is when this chemical reacts and the temperatures rise, it can cause a vapor,” she said. Inhaling that vapor can cause damage, including irritation to the eyes and nose, respiratory tract and lungs, bringing on symptoms like sore throats, runny noses, itching and burning eyes, dizziness, headaches and nausea.
Long-term consequences include effects on other organs, she said. Various animals have been affected differently, she said. Long-term human effects are not exactly known, but effects seen in mice could be seen in humans, she added. She is working with Environmental Protection Agency and the South Coast AQMD to provide more information.
“This is a unique situation. We don’t have information of a similar situation where this happened,” she said.