Science
Ten times worse than benzene — California updates its science on two chemicals in everyday air
Two toxic contaminants present in California’s ambient air appear to be much stronger carcinogens than previously known, state environmental health officials announced Thursday.
The draft finding from the state’s Office of Environmental Health Hazard Assessment finds that acrolein and ethylene oxide may pose an estimated cancer risk more than 10 times higher than benzene, a serious carcinogen linked to leukemia and other cancers.
It is the first step in a review process before final risk values are adopted, and it arrives at a time federal air-quality regulations are being reined in.
“If the early air monitoring results bear out, and if the draft cancer values developed are close to what eventually becomes final, then each air contaminant poses an unacceptable cancer risk,” said Kris Thayer, OEHHA’s director.
The update reflects the state’s evolving understanding of its most dangerous pollutants, which has shifted over the decades from visible pollutants, such as smog, to more invisible ones that cause cancer, heart disease and other health harms.
It comes only two months after the Trump administration’s Environmental Protection Agency moved to roll back standards on ethylene oxide, or EtO, in an effort to save millions of dollars in compliance costs for facilities that use the chemical for medical sterilization. The administration said it acted to “safeguard the supply of essential medical equipment,” but experts said the move will also expose more people to health risks.
It also follows a new national report from the American Lung Assn. that found 82% of Californians live in counties with unhealthful air, nearly double the national average.
“This is an important step to better understanding the harms of pollutants impacting Californians’ health,” said Will Barrett, assistant vice president for nationwide clean air policy at the American Lung Assn., who reviewed the state’s findings for The Times. “Following the latest available health science to determine risk is crucial to protecting health.”
Ethylene oxide is a colorless gas often used in the sterilization of medical devices, particularly those that can’t be cleaned using steam or radiation.
Acrolein can be formed when materials burn, such as cigarettes, e-cigarettes and vapes, wood, plastics and gasoline for cars, trucks, ships and aircraft. It can also be released by cooking fats and oils at high temperatures, and has been found in water produced by oil and gas operations and is an ingredient in some pesticides used in irrigation canals.
People can take steps to protect themselves from acrolein exposure in everyday life by avoiding smoking tobacco or using e-cigarettes and vaping products, avoiding smoke from fires or exhaust from diesel and gasoline vehicles and equipment — much of which can also help reduce exposure to ethylene oxide, officials said. When cooking with oils or fats, people should avoid very high temperatures and use a range hood fan when possible.
While both chemicals have been present in the state’s air for years, the new assessments from OEHHA are based on the latest science on health risks, officials said. Both acrolein and ethylene oxide were found to pose an estimated cancer risk exceeding 800 in 1 million — on par with the cancer risk that diesel exhaust was estimated to pose when it first emerged as a major public health concern in the 1990s, the agency said.
In response to the findings, Gov. Gavin Newsom’s May budget revision, released Thursday, includes $2.5 million in funding for the California Air Resources Board and OEHHA in support of research to help reduce people’s exposure to acrolein and ethylene oxide. The funding will help the state identify and track major sources of the chemicals and turn the findings into public health policy outcomes, officials said.
OEHHA’s assessment provides the first cancer risk value for acrolein since it was classified as probably cancer-causing to humans by the International Agency for Research on Cancer in 2020. Ethylene oxide was already identified as a carcinogen by the state, but the new assessment updates its risk levels based on the new research. The risk calculations are based on air monitoring data, which vary across the state depending on location, nearby sources and other factors.
Officials said the findings underscore the state’s efforts to strengthen environmental protection measures for residents at a moment when federal officials seek to loosen them.
“Especially in light of some of the national rollbacks we’re seeing on protections for public health, it really underscores how important the work that we’re doing here in California is,” said Courtney Smith, principal deputy executive officer with the Air Resources Board. “Not only for protecting the health of Californians, but also to ensure that there is rigorous, solid science available to other entities as well who may want to pursue additional protections.”
Short-term exposure to EtO by inhalation can cause headaches, dizziness, nausea, fatigue respiratory irritation and other adverse health effects, according to the federal Agency for Toxic Substances and Disease Registry. Longer-term exposure increases the risk of cancers of the white blood cells, such as non-Hodgkin’s lymphoma, as well as breast cancer.
Inhaling acrolein can cause nose and throat irritation and a decreased breathing rate. Chronic exposure, such as through cigarette smoke, has been linked to the development of asthma, chronic obstructive pulmonary disease and respiratory cancers.
The findings also come as California continues to receive poor grades on air quality. The American Lung Assn. annual State of the Air report found that the five U.S. counties with the worst smog pollution are all in California. Bakersfield was the metropolitan area with the worst level of year-round particle pollution for the seventh year in a row, while Los Angeles was the city with the worst ozone pollution, as it has been for 26 of the last 27 years.
“Californians face the most significant smog and soot challenges in the nation, but our air agencies have followed the science to build policies and programs to make real headway,” Barrett said. The state’s latest assessment “speaks to the need for ongoing local efforts while the federal government ignores the science and opens the door for more pollution. California must continue to invest in things like cleaning up truck fleets, broader public education and the underlying science to guide policies to protect health.”
Thursday’s announcement kicks off a 45-day public comment period, after which the draft assessments may be revised before undergoing additional public comment, peer review by the state’s Scientific Review Panel on Toxic Air Contaminants, and eventual adoption.
Science
After bold pledge, EPA shelves microplastics testing in U.S. drinking water
For the next five years, the Environmental Protection Agency has indicated it will not require public water utilities to test for microplastics or pharmaceuticals in drinking water, according to a proposed rule published in the Federal Register.
On Friday, the EPA submitted a list of chemicals it plans to test for under the Unregulated Contaminant Monitoring Rule, a mandatory testing program used to collect information about concerning chemicals in drinking water that could be harming human health. It did not include microplastics or pharmaceuticals.
The omissions come after announcements by EPA Administrator Lee Zeldin earlier this year that his agency was designating microplastics and pharmaceuticals priority contaminants for testing.
“This is a direct response to the concern of millions of Americans who have long demanded answers about what they and their families are drinking every day,” he said at an April news conference with Health and Human Secretary Robert F. Kennedy Jr. at EPA headquarters.
Zeldin’s announcement was seen at the time as a move to placate the increasingly disgruntled Make America Healthy Again contingent of Trump supporters.
Now the agency says it has no validated or standardized method to test for the plastic particles in drinking water, and wouldn’t be able to develop one before December, when testing is required to begin.
Among the 33 chemicals the EPA will require water utilities to test for are seven PFAS, or forever chemicals, and three pesticide residues.
It will be five years before the EPA proposes another list.
The EPA did not respond to a request for comment.
The agency noted in its proposed rule that it will collaborate with other federal agencies to “evaluate risks and exposures” of microplastics for future monitoring.
Environmentalists reacted with frustration and resignation. They pointed out that the European Union has developed methods to test for the tiny plastic particles, which have been found in people’s blood, brains and lung tissue. California has one in the works.
“The California water board has spent a lot of time and money on how to measure in drinking water,” said Judith Enck, a former EPA regional administrator and president of the anti-plastic environmental group Beyond Plastics. “EPA should give them a call.”
California was required by a 2018 state law to establish a protocol for local water utilities to test for the particles in drinking water. The state has not yet begun reporting its results, but protocols were established in 2021. Blair Robertson, a spokesman for the State Water Resources Control Board, said it’s not “a fully validated, end-to-end regulatory method” yet.
At the April meeting, Zeldin announced that he would place microplastics on what is known as the Contaminant Candidate List, which acts as a preliminary “watch list” of unregulated, priority contaminants in drinking water. Like the mandatory monitoring list, it is updated only every five years. The most recent list was published on April 2 — the day he made his announcement.
“Americans have been ignored as they sound the alarm about plastics in their drinking water,” Zeldin said during the announcement. “That ends today by placing microplastics on the contaminant candidate list for the first time ever. EPA will follow the science, will pursue answers and will hold ourselves to the highest standards to protect the health of Americans.”
There appears to be no clear association between these two lists, although the contaminant list is supposed to inform the monitoring list. Seventy-five chemicals and four chemical groups (microplastics, pharmaceuticals, PFAS chemicals, and disinfection byproducts) were listed on the 2026 contaminant list. Only seven of those chemicals were also on the proposed monitoring list (as well as seven PFAS chemicals).
When Zeldin announced microplastics as “‘a priority contaminant for regulation,’ and called it ‘a historic action on microplastics,’ he made it seem like the administration was going to take microplastics seriously,” said Mary Grant, water policy director for the environmental group Food & Water Watch.
“By not including them, they made it clear they don’t actually have plans to immediately address this crisis by getting the real-world monitoring data that we need right now to really start correcting ourselves,” she said.
Craig Davis, senior director of plastics chemistry at the American Chemistry Council — the nation’s largest trade group for chemical companies — said that while his organization supports microplastic research, it also agrees with the EPA’s decision not to include them in the monitoring list.
“National drinking water monitoring should be based on validated, standardized methods that can produce reliable and comparable data,” said Davis in a statement. He said “limited” national monitoring resources should be focused where data can produce “actionable public health information.”
The public has 60 days to comment once the plan is published in the Federal Register.
Science
Hospital visits for smoke inhalation spiked during Boyle Heights warehouse fire
The number of Angelenos who went to the hospital with throat pain and concerns about smoke inhalation spiked as a fire burned through the massive Lineage cold storage warehouse in Boyle Heights this month, The Times has learned.
The blaze burned for eight days beginning June 17 and involved solar panels, insulation foam and other industrial materials.
During that time, more than three times as many people went to emergency departments within 10 miles of the warehouse mentioning the fire or smoke inhalation compared with the two weeks prior, according to data from the Los Angeles County Department of Public Health obtained through a public records request.
The agency also noted a near doubling of patients mentioning throat pain within five miles of the fire June 21 — 1.9 times the baseline levels.
Usually, fewer than 50 people go to the emergency room each day for throat pain, and fewer than 20 people for smoke inhalation, the department said.
The hospitalization data was tracked through the department’s syndromic surveillance project, which monitors trends in what people report when they come to emergency departments in L.A. County, as well as diagnosis codes noted by providers. The system is not as comprehensive as full patient health records, and clinicians may not always include key words about “fire,” “smoke” or other circumstantial information in their diagnoses, the public health department said.
As such, it “cannot capture the true number of [emergency department] visits related to symptoms from the fire and likely underestimates the true burden of fire related symptoms,” the department said.
Perhaps unexpectedly, the department said it did not note a substantial increase in asthma, acute respiratory symptoms or chronic obstructive pulmonary disease-related emergency department visits during the fire.
But even these preliminary findings are concerning, experts said. The fire is believed to have started on the solar array on the roof of the 500,000 square-foot building, which housed 85 million pounds of frozen food. It then reached an ammonia line, prompting two brief shelter-in-place orders for nearby residents.
Over the next week, the fire continued to burn through dense insulation foam within the building’s walls and other unknown industrial materials, blanketing much of L.A. in acrid smoke. Residents in downtown L.A., northeast L.A., Burbank, the San Gabriel Valley and many other parts of the city and county reported seeing and smelling the fumes.
The South Coast Air Quality Management District issued multiple warnings about unhealthy levels of PM 2.5, or fine particulate matter. The city and county opened two smoke respite shelters in the immediate area so that people could breath cleaner air.
It is still unclear what exactly was in the smoke that people breathed in. Industrial fires release far more materials than the burned wood smoke that is emitted during wildfires.
“The makeup of the smoke can include toxic chemicals, fine particles and other serious risks to lung health depending on fire conditions and what is burned,” Will Barrett, assistant vice president for nationwide clean air policy at the American Lung Assn., said as the fire was burning. Children and elderly people are particularly at risk.
David Eisenman, director of the UCLA Center for Public Health and Disasters, said urban industrial fires also can represent a hazard that standard PM 2.5 warnings don’t always address. Those advisories are “blunt instruments” that don’t adequately capture emissions from burning man-made goods — or convey that the source of pollution may include burning batteries or toxic refrigerants, he said.
The fact that initial numbers don’t show a spike in asthma attacks is “somewhat reassuring,” Eisenman said. But “people may have gone to their primary care doctors, which this would not capture. This data deserves follow up.”
The air district and the U.S. Environmental Protection Agency deployed air monitors to assess particulate matter, airborne toxic metals and other harmful compounds during the early days of the blaze. The air district said it didn’t find significant levels of air toxics during the first two days of the fire, although it did record significantly elevated concentrations of particulate matter within the plume downwind.
Some of the measurements it took with mobile monitors, which are five-minute snapshots, also showed increased bromine and chlorine, which often are found when buildings burn and were at levels “below short-term health-based exposure thresholds,” the air district said. It began continuous PM 2.5. monitoring at two nearby elementary schools on the third day.
The L.A. Fire Department said it detected low-levels of toxic hydrogen fluoride on the second day of the fire, which can be a byproduct of burning lithium-ion batteries.
Lineage, the tenant-operator of the warehouse, said no concentrations of ammonia were detected in the air at any time.
“There’s no doubt this fire has had a huge impact on the local community, and we are committed to showing up in every way we can,” company officials wrote in a statement last week. They said Lineage worked closely with the Fire Department during the blaze and delivered masks, air purifiers and other supplies to the community, and will work to ensure the fastest cleanup possible.
The long-term health effects of the fire and its smoke probably won’t be known unless researchers conduct a follow-up study, said Eisenman of UCLA.
For example, there may have been delayed pulmonary effects from the hydrogen fluoride and burning insulation foam that — when combined with the elevated PM 2.5 levels in a dense urban environment — produced health effects that didn’t show up in the emergency room data.
“They will show up in increased primary care office visits and exacerbations of chronic disease over the next few weeks,” he said. “So from a public health standpoint, this fire is not over.”
Science
Water from Boyle Heights warehouse fire carries foam into L.A. River, sparks testing
LOS ANGELES — All the water unleashed onto the warehouse fire in Boyle Heights — some of it 480 gallons at a time by helicopter — had to end up somewhere.
That somewhere is the Los Angeles River.
Los Angeles Fire Department crews ripped through 50-foot walls filled with foam insulation to get to the building’s steel skeleton and its storage racks.
Charred chunks of foam have been floating from the burn site, partially blocking storm drains. Now organizers from East Yard Communities for Environmental Justice are teaming up with scientists from UCLA and Columbia University to find out more about what’s in the runoff.
“The community here is really interested in knowing, ‘Are there any contaminants that are potentially making their way down to the L.A. River?’” said Yoshira “Yoshi” Ornelas Van Horne, UCLA assistant professor in environmental health sciences. “We really can’t answer that unless we actually have measures and samples analyzed.”
Water samples collected directly from the warehouse fire runoff have been shipped to Columbia‘s Multi-Element Trace Analysis Laboratory in New York, which has a spectrometer that can identify trace levels of elements. The lab also has relationships with researchers in Southern California.
1. Emmanuel Carrera Ruedas, left, and Casey Cooper prep containers to take water samples from the L.A. River. 2. Casey Cooper holds a water sample. (Christina House / Los Angeles Times)
The data will then come back to UCLA for analysis. For now, the scientists and community advocates only have the money to test for copper, lead and arsenic, Ornelas Van Horne said. Residents have expressed interest in testing for more contaminants.
As the water from the firefighting efforts trickles through the warehouse in rivulets, it forms a stream at the corner of S. Indiana and Noakes streets, that gushed into the storm drain. On a recent visit, the water traversed a smoky 10-foot canyon of charred foam and twisted wall panels on its way to the drain.
From there, the water flows to the L.A. River. Despite the fact that its concrete design is intended to whisk water out of the city as fast as possible, life stubbornly persists in the river and nearby. Recreational swimming is not permitted, yet anglers fishing for tilapia, largemouth bass and carp are a common sight along the rocky sides of the soft-bottom areas.
The L.A. River, and all it carries with it, meets the ocean in Long Beach.
The L.A. County Public Works Department said it has deployed three containment booms — floating barriers — on the L.A. River, and is continuing to monitor the water as it makes its way to the ocean.
Emmanuel Carrera Ruedas takes a water sample.
(Christina House / Los Angeles Times)
Before it gets there, the river passes through the Dominguez wetlands, where Public Works is removing some number of dead fish. The wetland has absorbed toxic runoff from a warehouse fire before, resulting in a fish die-off.
“For so long, the L.A. River has been used as a dumping ground for all kinds of chemicals,” said Emmanuel Carrera Ruedas, a community scientist and member of East Yard Communities for Environmental Justice.
Pollution has plagued the L.A. River, but it does have allies. In the 1980s, the Friends of the LA River pushed to address street runoff and trash that had made the water body infamous. Significant progress from advocacy and government initiatives improved water conditions, but these efforts have not been equally distributed.
Carrera said the samples represent “proof of what’s actually going on, and accountability, too, for the city, of not just what’s happening in our air, but what’s actually happening in our waterways.”
The first samples for the project were taken last Friday, the second day of the fire.
They were the first of 20 samples the research groups have agreed to test at no cost to see if any exceed regulatory standards and could pose a risk to people nearby.
The warehouse fire represents the latest environmental disaster for people in Boyle Heights and East L.A. Just four weeks ago, a telecommunications crew accidentally struck one of the many oil pipelines beneath the L.A. area, spilling 25,000 gallons of crude oil near Eastern and Cesar Chavez avenues — including into storm drains feeding to the L.A. River.
“I think it really is difficult to see disaster after disaster hit the communities here, with not a lot of talk about how we can move through these disasters together,” said Casey Cooper, a volunteer community scientist involved in the sampling. They were inspired, they said, by the response of neighbors, and how people were supporting one another.
Results from the laboratory analysis could be back to Ornelas Van Horne within a month.
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