Firefighters’ blood, urine had high levels of mercury, other toxins after Sonoma County’s Tubbs fire

Preliminary findings from a study of blood and urine samples in firefighters deployed to the 2017 Tubbs fire showed exposure to toxic substances. The tests have implications far beyond the fire service.|

Rancho Adobe Fire Capt. Jimmy Bernal won’t receive his individual results for a week or two.

But he’s already heard a recap of preliminary findings from a study of blood and urine samples collected from firefighters after the 2017 Tubbs fire, and it’s enough to make him nervous.

Specimens from 149 Bay Area firefighters deployed to the destructive wildfire yielded elevated levels of mercury, a neurotoxin and carcinogen, and two toxic man-made chemicals, compared to samples from 31 firefighters who stayed close to home.

Principal investigator Rachel Morello-Frosch, a UC Berkeley environmental health researcher, said the findings need to be viewed with caution.

There is not enough evidence to draw direct conclusions about whether substances found in firefighters’ systems reflect exposure sustained during any particular fire or implications for their health, she said.

But release of the study’s initial results this week has nonetheless stoked mounting concerns about firefighters’ exposure to toxins and alarming rates of cancer and other diseases in the profession. Those worries are growing given the proliferation of large wildfires in California at the edges of wildlands and suburban areas, which incinerate organic fuels and man-made materials in their path.

Greater awareness

The tests have implications far beyond the fire service. Morello-Frosch said firefighters are “sentinels of environmental chemical exposure” for anyone else in close proximity - including law enforcement officers who assist with evacuations and security, and civilians who stay behind to defend their homes.

But most firefighters need little reminding, given growing awareness of the risk they face through direct exposure to smoke, and the gases and particles within it.

If they aren’t hearing it through health and wellness training, they’re hearing about it through colleagues.

“When I started, we didn’t talk about firefighters having cancer,” said retired Marin County firefighter Bob Briare, 62, of Larkfield. “At the end of my career, not only did I have cancer, but many of my friends had cancer.”

Said Bernal, 40, “This is the career we chose. But it’s scary, because I have two kids, and I want to make sure I’m there for them.”

The Tubbs fire was one of several wildfires that broke out around the region amid extremely dry conditions and wildly gusting winds the night of Oct. 8, 2017. Until the Camp fire razed the town of Paradise a year later, it was the most destructive in California history, destroying more than 5,600 structures and killing 22 people as it rampaged west from Calistoga through Santa Rosa.

Anyone in the area experienced the caustic smoke that resulted from the blaze, but no one more than the first responders who were directly in the fire’s path - many of them for days on end, inhaling gases and particles from incinerated building materials, household goods, garden products, metals, electronics and all manner of harmless and hazardous substances.

“That was a large exposure,” said Petaluma firefighter Kevin Burris, a cancer survivor at 36. “A normal person would never get exposed to that many structure fires burning at once.”

Bernal remembers how crews worked for days in the noxious fumes, their heads aching, “constantly popping ibuprofen.” Ten Rancho Adobe firefighters would later provide blood and urine samples.

“We knew we were exposed to a lot of chemicals, garbage, vehicle fires, batteries, tires,” Bernal said. “All that stuff was out there burning at the same time, including the houses and vegetation. Everyone felt it afterward.”

On about Day 4 or 5, talking briefly with a civilian in one of those white, disposable respirator masks, he watched smoke turn it brown “within five minutes,” he said.

Air tanks unwieldy

Unfortunately, the bulky air tank and breathing apparatus that urban firefighters may use to attack a structure fire isn’t built for wildfire work. It doesn’t have the capacity or lend itself to the physical exertion and nimbleness required to battle a wildfire, firefighters said.

“There’s all kinds of chemicals that off-gas,” said Santa Rosa Fire Capt. Sage Howell. “In a structure fire, we’re protected respiratory wise, because we have respiratory protection. In those big wildland fires, you’re exposed to those same types of things, a little bit diluted obviously. But we don’t have any respiratory protection for that.”

What’s more, substances often embedded in firefighting gear like turnouts - the baggy yellow jackets and pants firefighters wear - and contained in fire retardant foam can themselves build up in a person’s system

Two such chemicals, types of perfluoroalkyls, or PFAS, were found at elevated levels among the firefighters deployed to the Tubbs fire, when compared to those who were not, Morello-Frosch said. And all firefighters, as a group, tended to have higher levels of the two PFAS substances than a sample of Los Angeles adults for whom data was available, Morello-Frosch said.

PFAS substances have been linked to increased cancer risk, immune disorders and hormone disruption in some studies, according to the federal Agency for Toxic Substances and Disease Registry. They are commonly used in a wide variety of consumer products, including nonstick pans and pizza boxes, for their oil, grease and water repellent properties.

Specific details of the chemical findings were not available, but there are no benchmark levels against which risk can be measured, Morello-Frosch said.

Ten of the firefighters who provided samples had mercury levels above the “level of concern” for vulnerable populations, like women of childbearing age, compared to one from the nondeployed group, she said.

Eating in dirty clothes

Growing awareness of exposure and cancer risk has inspired significant changes in how firefighters deal with their personal safety and equipment hygiene after each fire call, particularly over the last 10 years.

Things like showering as soon as possible after exposure, maintaining two sets of turnouts so there’s always a clean one to climb into, traveling with dirty turnouts stored outside the engine cab and keeping dirty equipment away from home and family are among the new norm.

“A lot has changed,” said Sonoma County Fire Capt. Ryan Estes, 37, a 19-year veteran. “When I first started out, if your helmet was dirty, it was cool. Sometimes you didn’t even wash your gear.”

Many agencies have acquired extractors, specialty washers that clean bulky firefighting clothes and remove the chemicals that can get into them.

But a life in public safety doesn’t always allow for showers and cleanup on an ideal schedule, said Bill Harper, a captain with Sonoma Valley Fire and Rescue Authority and union president.

“We don’t stop what we’re doing and not help someone,” he said. “There’s always people in need and stuff to clean up.”

At the Tubbs fire, for instance, Bernal said, “We were eating, sleeping, wearing the same clothes night in and night out, without even taking a shower after the initial attack.”

Flame retardants

The related exposure investigation was largely funded by the 12-year-old San Francisco Firefighters Cancer Prevention Foundation, which hastily mobilized the effort, benefiting from Morello-Frosch’s ongoing research into breast cancer among female San Francisco firefighters.

But it wasn’t until nearly three weeks after the fire was contained that authorization for the study was obtained and medical personnel were able to get to various communities from Santa Clara to Sonoma counties to collect firefighter samples.

Researchers were able to analyze the specimens for heavy metals, including lead, manganese, antimony and cadmium, Morello-Frosch said, as well as for a flame retardant substance called polybrominated diphenyl ethers, or PBDEs, and for various PFAS substances.

Retired San Francisco Fire captain and cancer survivor Tony Stefani, president of the Cancer Prevention Foundation, said additional study samples were collected during last year’s Camp fire from about 100 front-line firefighters at a hospital in Chico because so many were text messaging back to headquarters about severe headaches and illness.

No analysis has been done yet, but those results may shed more light because they should reveal immediate exposure levels.

Under federal legislation passed last year, the Centers for Disease Control is setting up a national firefighter registry to help track cancer trends among active-duty and retired firefighters, Morello-Frosch said. It should launch in a year or two.

More study needed

But she said she hopes that what she calls her “pilot study” better prepares the scientific community to respond next time and get more real-time samples.

“We need to get back out there and do more of this work, and we need to do it better, and we need to get out there in real time combining biomonitoring with environmental sampling,” she said.

John Bagala, vice president for Marin Professional Firefighters, said the issue of toxic exposure is a national one.

“The scopes of our disasters are getting larger,” he said. “The fires are bigger, seems like we’re fighting more floods. So what’s happening is the people that are on the job, the operational tempo and their chance of getting exposure, it’s increasing day by day.”

You can reach Staff Writer Mary Callahan at 707-521-5249 or On Twitter @MaryCallahanB.

Mary Callahan

Environment and Climate Change, The Press Democrat

I am in awe of the breathtaking nature here in Sonoma County and am so grateful to live in this spectacular region we call home. I am amazed, too, by the expertise in our community and by the commitment to protecting the land, its waterways, its wildlife and its residents. My goal is to improve understanding of the issues, to find hope and to help all of us navigate the future of our environment. 

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