An LAist investigation found arsenic, cadmium, chromium and lead in samples of fire retardant collected from the Palisades, Eaton and Franklin fires.
By Jacob Margolis, LAist
This article was originally published by LAist on April3, 2025.
Not long after the Palisades Fire broke out Jan. 7, firefighting aircraft began drawing bright red lines with fire retardant across the Santa Monica Mountains, in an effort to slow and contain the flames.
By the time the fire was out about three weeks later, the MD-87s, S-2Ts and mammoth DC-10s had performed more than 280 drops across 20 square miles, according to data from Cal Fire obtained via public records requests.
LAist partnered with researchers at USC to test samples of the fire retardant gathered from fire zones in the weeks after the Palisades, Eaton and Franklin fires where it remained on the ground.
Those tests found toxic heavy metals including lead, arsenic, cadmium and chromium, which can accumulate in the environment and pose risks to humans and wildlife, according to federal and state environmental agencies.
A product called MVP-FX, a variant of Perimeter Solutions’ Phos-Chek, was the primary aerial retardant dropped on the Eaton and Palisades fires, according to the company.
The presence of heavy metals in MVP-Fx has not been previously reported.
LAist shared the USC lab results with Perimeter Solutions. Jeff Emery, Perimeter’s president of global fire safety, said the company’s products, including Phos-Chek MVP-Fx, have passed extensive testing. He added that the amount of heavy metals found by LAist was far below limits set by the Environmental Protection Agency and “any concerning levels for human health and safety.”
The presence of heavy metals isn’t noted in safety documents publicly shared by Perimeter Solutions.
Aircraft often drop more retardant than water each year on fires in California. From 2006 to 2024, more than 194 million gallons of various types of fire retardant were dropped by aircraft, according to data from Cal Fire.
“We don’t check into every single thing that’s in there,” said Chris Jurasek, deputy chief of tactical operations at Cal Fire.
He said his agency relies on the U.S. Forest Service to test and verify the safety of the retardants it uses. The use of fire retardants is a “critical” component of the firefighting arsenal, according to both Cal Fire and the U.S. Forest Service.
Why we had to run our own tests
Late last year, LAist requested samples of MVP-Fx from Cal Fire, the U.S. Forest Service and Perimeter Solutions, which manufactures the product, for the purpose of running an independent analysis for heavy metals. All declined.
“It’s not in our interest to share product with public or private agencies,” Jurasek said at the time. “You are not the first person to ask for us to give them fire retardant. It happens. It’s not something we do.”So over the next few months we gathered our own samples from the field.After the Franklin, Eaton and Palisades fires were under control, I hiked to remote sites and collected vegetation, trash and dirt that had been caked with fire retardant. The samples were placed into baggies and taken to the Environmental Chemistry Laboratory at USC, where the fire retardant was tested for heavy metals.
Marella Schammel, a Ph.D. student, scraped dried red flakes into tubes filled with a diluted mixture of nitric acid and ran them through an inductively coupled plasma mass spectrometer.Arsenic, cadmium, chromium, copper, manganese, nickel, lead, antimony, thallium, vanadium and zinc were all found in the samples.
Emery told LAist that any trace heavy metals found in testing were “naturally occurring.”
Phos-Chek MVP-Fx is primarily made of ammonium phosphates, which are derived from phosphate. That rock, when mined, can contain trace amounts of heavy metals.
“There are no heavy metals added to any of our formulations,” Emery said.
Cal Fire, the U.S. Forest Service and Perimeter Solutions all dismissed the results of the testing — saying that the samples couldn’t be relied on because they were gathered in the field. That the potential for contamination by ash from burning structures and brush after the retardant was dropped from planes was too great.
Eventually, LAist obtained unused, unmixed MVP-Fx and verified the source and authenticity of the material.
What we found
Like the materials collected in fire zones, this unused sample was sent to the USC lab.
Schammel processed the MVP-Fx and found the same heavy metals present as the field samples we gathered.
There were some differences. However, it’s unclear if those differences are due to contamination on the ground or if there’s a variance in the amount of heavy metals present in different batches of the product.
“I’m not too surprised,” said Daniel McCurry, professor of civil and environmental engineering, who oversaw the testing process. Last year he and Schammel analyzed another Phos-Chek variant — LC95 — and found heavy metals as well.
LC95 is one of several USDA approved retardants in use today and one of the variants manufactured by Perimeter Solutions. Cal Fire doesn’t use the LC95 variant.
Those results — from tests sparked in part by questions I’d asked McCurry in 2019 about whether we should be concerned about what was in fire retardants — made me want to know more about what is in the fire retardants in use now.
In an effort to compare USC’s test results to the official safety testing required by the federal government, LAist reached out to both Perimeter Solutions and the U.S. Forest Service, an agency within the USDA, for detailed test results for MVP-Fx. Neither would provide them.
In a statement, the U.S. Forest Service said that retardants that qualify for use have to show “nondetectable or trace levels” of certain heavy metals. However, the test results are proprietary information protected by nondisclosure agreements.
‘Let people know what they’re dealing with’
LAist’s review of publicly available documentation related to MVP-Fx, including its safety data sheet — which is required to warn those who may come in contact with the product of potential risks — found no reference to the presence of heavy metals.After reviewing LAist’s results and the company’s safety data sheet, Claudia Polsky, director of the Environmental Law Clinic at UC Berkeley School of Law, said the company is likely in violation of multiple California laws and regulations including Cal OSHA standards, unfair competition law and Proposition 65.
“The Cal OSHA hazard communication standards require that a safety data sheet identify every hazardous ingredient in the product,” Polsky said. “Companies often resist disclosure requirements.
“To me this situation is disturbing if unsurprising.”
When asked about the safety data sheet, Emery said that the company works to “ensure compliance with all applicable regulatory requirements concerning our product.”Some who regularly work with Phos-Chek said that LAist’s findings were a surprise to them.
“ The heavy metal thing, I can tell you, was news to me,” said Joel Lane, air tactical group supervisor with the Orange County Fire Authority. He’s worked in the industry for decades and has come in contact with different variants of Phos-Chek, both during preparation and when it’s been dropped on him by aircraft.
Lane said that he’s never been told or read in official documentation that heavy metals could potentially be present in retardant, which he finds upsetting.
He said the lack of transparency is concerning, but that it wouldn’t be the first time.
Lane feels firefighters were left in the dark about the risk of PFAS — long-lasting chemicals used in firefighting foam and in the heavy gear firefighters wear — that have been tied to elevated rates of cancer, according to the Environmental Protection Agency. Lane himself recently survived prostate cancer.
“ Be transparent, be open. Let people know what they’re dealing with,” Lane said. It’s only then that they can make informed decisions about risks for themselves, he added.
LAist asked the U.S. Forest Service about potential risks to firefighters, to which they responded that “risk assessments of firefighter exposure to retardants do not indicate an increased risk for health effects,” pointing to a health assessment conducted by the agency, which includes MVP-Fx.
Although the assessment says risks are expected to be generally negligible, it doesn’t explicitly mention heavy metal exposure. The U.S. Forest Service didn’t respond to whether heavy metal contamination was taken into consideration for the assessment.
What’s the risk to you?
Heavy metals can pose a serious health risk and have been tied to increased rates of cancer, as well as reproductive and developmental issues in humans.
That said, multiple health experts told LAist that the risk to members of the public exposed to the retardant when doing activities like hiking, is likely low, given the concentration of contaminants present in our samples.
“It should not be a reason for panic, but maybe it’s a reason for caution,” said Dr. Ana Navas-Acien, professor and chair of Environmental Health Sciences at the Mailman School of Public Health at Columbia University, who reviewed the results.
Sanjay Mohanty, associate professor of civil and environmental engineering at UCLA, agreed, saying that the risk for people with limited exposure, such as homeowners or hikers, is “very low.”
If you or your pets are exposed, it’s a good idea to wash it off.
Environmental effects
Fire retardants can be particularly dangerous to aquatic ecosystems, according to a U.S. Forest Service environmental impact study published in 2011.
Once retardant enters waterways it can lead to elevated ammonia levels, which in turn can be toxic to salmon and trout. And there’s a possibility that an influx of nutrients from retardant can boost algal growth and create dead zones, killing off organisms there.
Because of these risks, the U.S. Forest Service prohibits the dropping of retardant within 300 feet of waterways, though it does happen. There have been more than 240 intrusions since 2012, according to another U.S. Forest Service environmental impact study from 2023.
However, even if the retardant doesn’t get dropped directly on waterways, it can get washed into them by rain. Heavy metals can settle in streams and ponds and potentially have devastating impacts on organisms there.
William Clements, a professor in the Department of Fish and Wildlife Conservation at Colorado State University, homed in on the cadmium LAist found in the MVP-Fx.
“ If even a small fraction of that ends up in that stream, that is cause for concern,” he said.
The heavy metal can get taken up by sponge-like algae, which is then eaten by aquatic insects such as mayflies and stoneflies, which can die when exposed to the cadmium. Exposure to the heavy metal can also inhibit their reproduction, growth and ability to emerge from streams, compromising a source of food for fish and birds, according to Clements.
“ The levels of metals will increase and will be bioconcentrated over time. Not now, but in a year, two years, maybe five years from now,” said Dmitri Deheyn, a marine toxicologist at the Scripps Institution of Oceanography.
“ People need to make the association that the impact is a lingering impact that will be diffused and diluted over time and space.”
In an effort to figure out how much heavy metal was spread throughout the San Gabriel and Santa Monica mountains during the Eaton and Palisades fires, LAist requested information on the total number of gallons of retardant dropped, from both the U.S. Forest Service and Cal Fire, via records requests. None were fulfilled.
