Ethylene Oxide and Acrolein in California: The Invisible Carcinogens in the Air We Breathe

Urban California communities face chronic exposure to air pollutants like ethylene oxide and acrolein, with elevated cancer risk.

By Dr. Alberto Augsten, Toxicologist and Psychopharmacologist

In May 2026, California's Office of Environmental Health Hazard Assessment (OEHHA) released new draft cancer risk assessments for two pollutants millions of Californians breathe every day: ethylene oxide and acrolein. The findings are alarming: both chemicals can pose an estimated cancer risk of more than 800 per million people exposed, with communities near industrial facilities facing even higher risks.

What Is Ethylene Oxide?

Ethylene oxide (EtO) is a colorless gas used primarily to sterilize medical equipment and as a chemical intermediate in the manufacture of plastics, antifreeze, and textiles. It is a confirmed human carcinogen per EPA and IARC, associated with leukemia, lymphoma, and breast cancer. Communities near medical sterilization plants in California — particularly in the southern part of the state — have shown concerning ambient levels.

What Is Acrolein?

Acrolein is a highly reactive aldehyde formed during incomplete combustion: wildfire smoke, diesel exhaust, tobacco smoke, and high-heat cooking with vegetable oils. In California, increasingly frequent wildfires have raised chronic population exposure. Acrolein causes severe respiratory irritation, DNA damage, and is suspected to contribute to chronic lung disease and lung cancer.

Recent Incidents and Acute Risk

Concern about chemical exposures in California is not theoretical. In May 2026, an imminent leak in Garden Grove (Orange County) involving methyl methacrylate (MMA) led to the evacuation of 40,000 residents. EPA warns that even short-term MMA exposure can cause severe skin, eye, and respiratory irritation.

Most Vulnerable Populations

Children, pregnant women, older adults, and people with asthma or COPD are especially sensitive. Low-income and predominantly Latino communities in the Central Valley, South Los Angeles, and the Long Beach port area bear a disproportionate burden of air pollution exposure.

How to Protect Yourself

Monitor air quality: use AirNow.gov or your local air-quality district app. When the index is in the red or purple zone, stay indoors.

Use air purifiers with HEPA + activated carbon filters: HEPA captures particles; activated carbon adsorbs volatile organic gases like acrolein and formaldehyde.

N95 or KN95 masks during smoke events: surgical masks do not protect against fine particulates (PM2.5).

Ventilate when cooking: turn on the range hood and open windows when cooking on high heat, especially with oils.

Know your environment: CalEPA's CalEnviroScreen tool lets you see cumulative pollution levels in your ZIP code.

Report unusual chemical leaks or odors to 911 and your local Air Quality Management District.

The Toxicology Perspective

Exposure to airborne carcinogens is as much a question of environmental justice as it is of public health. The new OEHHA assessments should accelerate stricter industrial emissions regulations and better protection for frontline communities. In the meantime, personal prevention and community advocacy are our best tools.

For urgent toxicology questions, call the California Poison Control Center at 1-800-222-1222.