California health officials dropped some unsettling numbers on Thursday, releasing draft cancer risk values for two common air contaminants, acrolein and ethylene oxide, that suggest both may be more than 10 times as carcinogenic as benzene. The draft assessments, published May 14, estimate lifetime cancer risks in some situations above 800 in 1 million and trigger a 45-day public comment window. Governor Gavin Newsom’s May budget revision sets aside $2.5 million to help state agencies track where the chemicals are coming from and reduce exposure.
According to the OEHHA, the proposed inhalation unit risk factors are built on recent studies and California air-monitoring data. The numbers are not final yet, and will go through public comment, peer review and possible revision before they influence policy. State scientists say the updated estimates put acrolein and ethylene oxide in the same league as the cancer risks that once focused public attention on diesel exhaust in the 1990s, and that the chemicals deserve targeted research. “We will continue to use rigorous scientific methods and public peer review,” OEHHA Director Kris Thayer said in the announcement.
New risk estimates
The draft findings conclude that both acrolein and ethylene oxide may carry estimated cancer risks that exceed 800 in 1 million, “more than 10 times higher than benzene,” as reported by the Los Angeles Times. For acrolein, this is the first time OEHHA has proposed a cancer risk value since the International Agency for Research on Cancer classified the chemical as “probably carcinogenic to humans” in 2020. The governor’s May budget proposal also includes $2.5 million to help the California Air Resources Board and OEHHA expand monitoring and research on the two pollutants, the Times noted.
Where the pollution comes from
State officials say acrolein shows up whenever materials burn, whether that is wildfire smoke, cigarette smoke or high-temperature cooking, and it can add to the cocktail of irritants already in California’s air. Ethylene oxide, by contrast, is produced and used by industry to sterilize medical devices and to manufacture other chemicals, according to the California Air Resources Board. CARB has rolled out new web pages and tools that let communities look more closely at local exposure levels, and the agency plans to work with OEHHA and local air districts on targeted monitoring.
Why it matters in California
The findings hit especially hard in a state that already struggles with dirty air. The American Lung Association’s 2026 “State of the Air” report found that about 82% of Californians live in counties with unhealthy air quality. The American Lung Association reported that parts of Southern California remain national hotspots for ozone and particle pollution, meaning any extra dose of toxic chemicals like acrolein and ethylene oxide could worsen already risky conditions.
Health effects
Short-term inhalation of ethylene oxide can cause headaches, dizziness and irritation of the eyes and respiratory system, while long-term exposure increases the risk of breast cancer and cancers of the blood, according to the Agency for Toxic Substances and Disease Registry. The ATSDR cites occupational and community studies that link chronic exposure to ethylene oxide with leukemia and lymphoma. Acrolein, meanwhile, is a strong respiratory irritant associated with worsened asthma and chronic lung problems, and occupational safety guidance sets exposure limits and emergency procedures for the chemical, per OSHA.
Regulatory and legal fallout
The state’s announcement lands as the federal Environmental Protection Agency is proposing to reconsider parts of a 2024 rule that tightened emissions limits on commercial sterilizers that use ethylene oxide. The Environmental Protection Agency says its proposal is meant to balance public health protections with keeping medical supply chains intact. Environmental advocates counter that the shift would undercut protections for nearby neighborhoods. The Southern Environmental Law Center has called the proposed changes a gift to polluters and warned that rolling back standards would increase cancer risks for people who live close to sterilization plants, according to the Southern Environmental Law Center.
How to weigh in
OEHHA has opened a 45-day public comment period running from May 14 through June 29 and plans to hold public workshops in early June. Draft technical documents, workshop details and instructions for submitting comments are posted on the agency’s website. OEHHA is urging scientists, local governments and community members to review the material and share data, questions or concerns.
Once the comment period ends, the draft values will be revised as needed, undergo another round of internal review and then be scrutinized by the state’s Scientific Review Panel on Toxic Air Contaminants before any regulatory moves are made. As the Los Angeles Times reported, state officials say the aim is to build a solid scientific foundation for monitoring and policy work, not to trigger immediate changes to facility permits.
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