Firefighting classified as carcinogenic to humans

We asked scientists how the findings apply to wildland firefighters

crew from Minnesota
A crew from Minnesota mopping up on the King Fire east of Placerville, California in 2014. Incident Management Team photo.

The International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organization (WHO), has evaluated the carcinogenicity of occupational exposure as a firefighter.

A Working Group of 25 international experts, including 3 Invited Specialists from 8 countries was convened by the IARC Monographs program for a meeting in Lyon, France.

After thoroughly reviewing the available scientific literature, sufficient evidence led the Working Group to classify occupational exposure as a firefighter as carcinogenic to humans.

A summary of the final evaluations has now been published. The detailed assessment will be published in The Lancet Oncology in 2023 as Volume 132 of the IARC Monographs.

Evidence for cancer in humans 
The study found that occupational exposure as a firefighter causes cancer. There was sufficient evidence for cancer in humans for mesothelioma and bladder cancer.

There was limited evidence for cancer in humans for the following cancer types: colon cancer, prostate cancer, testicular cancer, melanoma of the skin, and non-Hodgkin lymphoma.

Strong mechanistic evidence 
The evaluation of the mechanistic evidence was based on exposures associated with fighting structure and wildland fires. There was strong mechanistic evidence in exposed humans that occupational exposure as a firefighter exhibits 5 of the 10 key characteristics of carcinogens: “is genotoxic”, “induces epigenetic alterations”, “induces oxidative stress”, “induces chronic inflammation”, and “modulates receptor-mediated effects”.

Exposure of firefighters
Firefighters are exposed to a complex mixture of combustion products from fires (e.g. polycyclic aromatic hydrocarbons, volatile organic compounds, metals, and particulates), diesel exhaust, building materials (e.g. asbestos), and other hazards (e.g. heat stress, shift work, and ultraviolet and other radiation). In addition, the use of flame retardants in textiles and of persistent organic pollutants (e.g. per- and polyfluorinated substances) in firefighting foams has increased over time.

This mixture may include many agents already classified by the IARC Monographs program in Group 1 (carcinogenic to humans), Group 2A (probably carcinogenic to humans), and Group 2B (possibly carcinogenic to humans). Dermal exposure, inhalation, and ingestion are common routes of exposure, and biomarker studies among firefighters have found enhanced levels of markers of exposure to polycyclic aromatic hydrocarbons, flame retardants, and persistent organic pollutants.


Most studies of firefighter health evaluate structural firefighters. We asked Dr. Kenny Fent and Dr. Kathleen Navarro of the National Institute for Occupational Safety and Health (NIOSH) questions about how these findings apply to wildland firefighters. Here is their joint response:


Summary of IARC Evaluation for Wildland Firefighters
The IARC evaluation of Occupational Exposure as a Firefighter included a review of the available scientific literature on occupational exposures, cancer epidemiology and the key characteristics of carcinogens. The evaluation did not differentiate between structural and wildland firefighters in making the determination of carcinogenicity. This is because the working group was not able to differentiate structure fire exposures (and other exposures) from wildfire exposures for firefighters in at least some of the cancer cohort studies that were included the evaluation.

In addition, many of the studies that provided the evidence of carcinogenicity included the evaluation of the key characteristics of carcinogens (intermediate health outcomes on the pathway to cancer). These included studies of wildland firefighters working on wildfires and prescribed fires.

Lastly, the exposure studies reviewed supported that both structural and wildland firefighters were exposed to similar types of carcinogens. As a result, the definition of “occupational exposure as a firefighter” for the IARC evaluation was kept broad and included a variety of hazards resulting from fires (e.g., structure, wildland, and vehicle fires) and other events (e.g., vehicle accidents, medical incidents, hazardous material releases, and building collapses).

Is mesothelioma only caused by exposure to asbestos, and are wildland firefighters generally exposed to it?
Yes, mesothelioma is caused by exposure to asbestos. Asbestos exposure is generally rare among wildland firefighters, with the exception for wildland firefighters who commonly encounter built environments (especially buildings constructed before the 1970s), areas with contamination (e.g., Libby, MT) or naturally occurring asbestos. A past NIOSH Health Hazard Evaluation reported that exposure to total asbestos fibers in air were less than the lowest occupational exposure limits while conducting a prescribed burn. However, the highest concentrations measured were during tasks with greater plant and soil disturbance and where water was not used (e.g., fire line construction and dry mop-up).


Dr. Kenny Fent leads the National Firefighter Registry at NIOSH and was the chair of the exposure characterization subgroup for the IARC working group.

Dr. Kathleen Navarro leads the Wildland Firefighter Safety and Health program at NIOSH and was a Representative of a national health agency for the IARC evaluation.

Respirator being developed for wildland firefighters

Wildland fire respirator
Development of a wildland fire respirator. Two versions are being tested, with the filter being carried on the chest hip. Department of Homeland Security photo.

A working group for the International Agency for Research on Cancer, the cancer agency of the World Health Organization, has just “classified occupational exposure as a firefighter as carcinogenic to humans.” Part of the reason is the toxic gasses firefighters are exposed to.

Wildland firefighters working on a vegetation fire can’t wear the conventional self contained breathing apparatus used by structural firefighters. It is too bulky, heavy, and only lasts 10 to 30 minutes.

In an effort to provide less carcinogenic air to wildland firefighters, the Department of Homeland Security’s Science and Technology Directorate  is developing a respirator capable of removing airborne hazards present in the wildland firefighting operating environment. They are working with the International Association of Firefighters, National Fire Protection Association, International Association of Fire Chiefs, U.S. Forest Service, and local Colorado fire departments to develop and test the Directorate’s Wildland Firefighter Respirator (WFR). It contains a HEPA filter module that will remove very fine particulates, and a carbon sorbent to remove toxic gases. The team is investigating wildland firefighter-approved designs like the Radio Carrier and Hip-Mounted units shown in the photo below.

Wildland fire respirator
Development of a wildland fire respirator. Two versions are being tested, with the filter being carried on the chest hip. Department of Homeland Security photo.

The WFR was designed around a lightweight mask covering just the mouth and nose. It relies on filtration, designed to go a whole shift before needing to be changed.

“Our system pushes clean air to firefighters using a powered blower with HEPA and carbon filters,” said S&T Program Manager Kimberli Jones-Holt. The system connects to the half-mask through a lightweight, flexible breathing hose to provide clean air and draws in air from the bottom of the unit to prevent rain or water infiltration.

“The filters were also designed to be inexpensive and easily replaced at $5 to $10 each,” Jones-Holt continued.

It uses an electric blower to force filtered air to the mask, relying on AA batteries for power.

The DHS says if wildland firefighters use respiratory protection, their careers could be significantly extended, leading to a more educated and experienced workforce capable of more efficient operations, with lower medical bills and training costs.

Thanks and a tip of the hat go out to Bob.

Study confirms extreme wildfires of 2020 in Western Oregon were not unprecedented

satellite photo fires smoke Washington, Oregon, and California
GOES-17 photo of smoke from wildfires in Washington, Oregon, and California at 5:56 p.m. PDT Sept. 8, 2020. The photo was taken during a very strong wind event.

By U.S. Forest Service

When the 2020 Labor Day Fires torched more than 300,000 hectares over the span of two weeks in parts of western Oregon and Washington, they devastated communities and put the threat of west-side fires squarely into focus. A new study led by the USDA Forest Service’s Pacific Northwest Research Station examines the context surrounding the fires and offers insight into the historical role of large, high-severity fires—and the future of wildfires—west of the Cascades.

“Without a doubt, the 2020 Labor Day Fires were a significant fire event on many levels, and one that was a wake-up call for the region,” said Matthew Reilly, research forester and lead author of the study, which is published in the journal Ecosphere. “The goal of our study was to help understand how this event compared to past west-side fires so that we can help inform adaptation strategies aimed at preventing or mitigating similar events in the future.”

Drawing from a literature review, extensive historical data, and new analysis, Reilly and his co-authors explored five questions surrounding the 2020 Labor Day Fires: how the 2020 fires compared with historical fires in the region, the role of weather and climate, the effects of forest management and pre-fire forest structure on burn severity, the impacts of these fires on west-side landscapes, and what can be done to adapt to similar fires in the future. Ultimately, they found that the 2020 fires were remarkably consistent with historical fires on the west side, both in terms of their timing and size and the cause of their rapid spread—dry conditions combined with strong east winds.

“Our findings suggest that these severe fires are normal for west-side landscapes when you look at historical fire regimes at longer time scales,” Reilly said. In fact, the researchers identified similarly large historical fires in the early 20th century under similar weather conditions—some even burning right around Labor Day—in some of the same locations that burned in 2020.

Because of the abundant and productive forests characteristic of the west side and the driving role of extreme winds, conventional fire management tools used in dry forests, like prescribed burning and fuels management, will likely be less effective in west-side forests than they are on the east side. This is particularly the case, their study found, when fire weather conditions are as extreme as those witnessed during the 2020 fires.

“Our study indicates we need very different approaches and adaptation strategies in west-side forests compared to those we use in dry forests,” Reilly said.

The study was conducted as part of the Pacific Northwest Research Station’s ongoing West-side Fire Research Initiative, which was launched in 2019 to develop science-based tools to help resource managers respond to wildfire risk in west-side forests. The study’s coauthors are from the Washington State Department of Natural Resources, University of Washington, Oregon State University, and USDA Forest Service’s Pacific Northwest Region.

Highlights

  • The 2020 Labor Day Fires were much larger and more severe than others in the recent record, but they were remarkably consistent with many historical fires. Strong east winds and dry conditions are the common denominators in both large historical fires of the past and the 2020 fires.
  • Forest management and fuel treatments are unlikely to influence fire severity in the most extreme wind-driven fires, like the 2020 Labor Day Fires. Pre-fire forest structure, largely the result of previous forest management activities, had little effect on burn severity when east winds were strong during the 2020 fires.
  • Fuel treatments around homes and infrastructure may still be beneficial under low and moderate fire-weather conditions.
  • Adaptation strategies for similar fires in the future in west-side communities might, instead, focus on ignition prevention, fire suppression, and community preparedness.

More information:

Matthew J. Reilly et al, Cascadia Burning: The historic, but not historically unprecedented, 2020 wildfires in the Pacific Northwest, USA, Ecosphere (2022). DOI: 10.1002/ecs2.4070

Wildfire Today, articles posted in September, 2020 tagged Oregon, or Washington.

Survey of more than 700 wildland firefighters identifies 10 strategies for improving working conditions

“Recruitment and retention of qualified firefighters is a critical issue for national security”

Morning briefing on the Calf Canyon - Hermits Peak Fire
Morning briefing May 8, 2022 on the Calf Canyon – Hermits Peak Fire as firefighters break out into Divisions. USFS photo.

A survey of 708 federal wildland firefighters found that they reported dissatisfaction with recruitment and hiring processes, insufficient base salaries, poor mental health outcomes, elevated risks to health and safety, and significant effects of wildland firefighting on family status.

It was conducted by Robin M. Verble, Rachel Granberg, and Seth Person, the latter two of which are federal wildland firefighters. On their wildlandfiresurvey.com website all three are seen in photos wearing Nomex fire clothing.

“Given the ever-increasing length, extent, and intensity of wildfire season, recruitment and retention of qualified WFF is a critical issue for national security,” the researchers concluded. “Concentrated legislative, organizational, and agency efforts are needed to systemically address the issues identified in this survey: Our survey provides specific actionable items that can improve retention and recruitment, as prioritized by current federal WFFs.”

The majority of respondents  had a bachelors degree or higher, had a mean base salary of $28,545 to $37,113, and 75 percent worked for the US Forest Service.

Here are a few of the survey’s many findings:

  • 92% of the respondents stated that they needed more than 300 hours of overtime work annually to pay their bills. 27% needed over 900 hours of overtime work annually to pay their bills.
  • Most of the respondents disagree or strongly disagree that they have affordable childcare options.
  • Approximately 67% of respondents reported that they have experienced an injury or illness as a result of their work in wildland fire.
  • Wildland firefighters divorce at a rate 2.5 times the national average.
  • Approximately 60% said they have missed out on jobs because of mistakes that Human Resources made.
  • Conservatively estimated rates of suicidal thoughts and ideation among WFFs is 16.5%.
  • Respondents report rates of ADHD at approximately 4 times the national average.

Based on the survey, the researchers listed ten strategies that federal agencies can implement to improve working conditions for wildland firefighters. In the report each one is explained in detail, but here are the topics:

  1. Provide the right pay for the right job
  2. Recognize the strain on families
  3. Increase mental health care accessibility and resources
  4. Combat unhealthy and unsustainable work-life imbalance
  5. Rectify issues with workplace safety (rates of injury, violence, and sexul assault)
  6. Improve health insurance benefits and timely injury compensation
  7. Reimagine the hiring process
  8. Address chronic mismanagement at the Albuquerque Service Center (human resources and hiring)
  9. Promote a new deal for diversity
  10. Build organizational trust through empowering local units

 

Data from Granberg, R., Pearson, S., and Verble, R. 2022. Survey of federal wildland firefighters: working conditions, safety, morale, & barriers to recruitment & retention. Report. Available online at wildlandfiresurvey.com 

New fire shelter prototypes tested

Four new designs remain within survival limits longer

fire shelter design testing
Layout of field equipment. TC, thermocouple trees; shelters in random plot location, and anemometer. Photo was from Mount Palomar Test 1.

By Laura Oleniacz, North Carolina State University

North Carolina State University researchers found that four new designs for shelters to protect firefighters trapped in wildfires could increase the survival time inside the shelters compared with the current industry standard. In lab simulations of wildfire burn-overs — where a wildfire sweeps over a group of trapped firefighters or equipment — temperatures inside the shelters remained within survival limits for longer, and the shelters took longer to break open.

Researchers hope their findings from the lab, as well as from field tests conducted across North America, could spur the development of new, better shelters. In addition, they hope the findings will inform new standards for shelter design and testing.

“For the wildland firefighter, deploying a shelter is the last thing they want to do — it’s the final resort, the last line of defense,” said study co-author Roger Barker, the Burlington Distinguished Professor of Textile Technology at NC State and the director of the Textile Protection and Comfort Center (TPACC). “While there’s no such thing as ‘fire-proof,’ what we’re trying to do is to buy more time. We were able to demonstrate our shelters could increase the time to failure — time that could be critical for survival.”

One problem with the industry standard shelter is that the aluminum outer layer will melt in contact with direct flame.

“In light of the failure mechanisms of shelters that we observed during wildland fires, we thought we could develop better shelters that provide enhanced protection by incorporating an inner heat-blocking barrier and additional thermal insulation into the construction,” said the study’s lead author Joseph Roise, professor of forestry and environmental resources at NC State. “We know we can make a better shelter.”

With that goal in mind, the researchers designed two leading prototypes and two lighter versions weighing less than 5 pounds. They added insulating materials, and experimented with different seam designs to keep them from falling apart.

fire shelter design testing
Photo of PyroDome: top left shows the shelter layout, burners and heat sensors; top right is the dome to concentrate flames and turbulence; bottom is an interior view of the shelter during test, showing small thermocouple tree.

In the TPACC lab, researchers tested the designs against the industry standard in a test chamber called the PyroDome Turbulent Flame Fire Shelter Test System. They blasted the shelters with direct flame from propane burners for 60 seconds, and measured how long it took the temperature at the floor of the shelters to reach 302 degrees Fahrenheit, the temperature threshold for survival. They also set up cameras inside PyroDome to see when the inner layer of the shelters would break open.

All of the prototypes had improved survival metrics compared to the standard, which reached the survival limit in less than 40 seconds. Meanwhile, the temperature in one of their designs was nowhere near the survival limit temperature at 60 seconds.

fire shelter design testing
Internal and external temperature profiles (Prototype 4, field test 1). For every test and for every shelter, there is a temperature profile. The upper horizontal line is the melting point of aluminium. Summing the time of both TC1 and TC4 above that line gives us ∑t660. The lower solid line is the internal shelter temperature 5.1 cm (2 in) from ground. The difference between peak and ambient temperature gives us ΔT. R660 = ΔT[∑t660]−1 is the insulation performance index.
The researchers also tested the shelters’ performance in variety of conditions in controlled burns in Canada, California, North Carolina and South Dakota. However, they found the field tests were not reliable enough to draw statistically significant conclusions because of wind, fuel and fire conditions.

“We went all over North America to find different fire conditions that would give different types of fire exposures,” Barker said. “What we found is there is so much variability in the field test, confirming how useful it was for us to have PyroDome.”

fire shelter design testing
Photo of Prototype 4 in Field Test 1. Left shows 99% exterior damage and right shows interior free of damage.

The two tests in southern California had the best burn conditions, and researchers saw one of their prototypes performed well in a burn-over. In a test in South Dakota, researchers witnessed shelter failures when grass roots caught fire to spread under the walls inside the shelter. That underscored the importance of fully clearing the area around the shelter, and even scraping down underneath them to remove all organic material.

“If you have a sample of two, you can’t make any statistical comparisons,” Roise said. “But we did see that after the test in California, one of our best-performing prototypes got the full brunt of the fire. It was totally burned on the outside, but the inside was undamaged.”

fire shelter design testing
Summary of peak internal fire shelter temperatures at 5cm (2 in).

The new findings could give manufacturers and people developing these shelters a new target to shoot for in terms of both how to test them and minimal performance requirements, according to Barker.

The study, “Field and full-scale laboratory testing of prototype wildland fire shelters,” was published online in the International Journal of Wildland Fire. In addition to Barker and Roise, other authors include John Williams, a former research assistant in forestry and environmental resources at NC State, and John Morton-Aslanis, a research assistant in TPACC. The study was funded by the DHS FEMA Assistance to Firefighters Grant Program.

(All of the images are from the IJWF study)

Thanks and a tip of the hat go out to Gerald.

Researchers develop new modeling tools for prescribed fire

USFWS Rx fire
Florida Panther National Wildlife Refuge conducted a 704-acre prescribed fire on April 4, 2014 in the southeast corner of the refuge near I-75 and SR 29 in southwest Florida. Firefighter Connor Bowden uses a drip torch to ignite a portion of the prescribed fire. Photo Credit: Paul Stevko – USFWS

Below are portions of a press release issued March 24 by the U.S. Forest Service’s Southern Research Station.


By Stephanie Siegel, Southern Research Station

March 24, 2022 – Much of what is known about planned fire comes from a burn manager’s memory.

“It takes years to get that kind of experience,” says Joseph O’Brien, fire research ecologist with the USDA Forest Service. “If things are changing, like invasive species or climate, or if you’re a new manager, you need help.”

O’Brien, writing in Fire Ecology with J. Kevin Hiers of Tall Timbers Research Station and others, identified a need for more science-based prescribed fire predictions and models. Fire researchers and managers can use these tools to test scenarios, teach new prescribed fire managers, and identify possible improvements in fire prescriptions and plans.

For predicting fire behavior, the Southern Research Station (SRS) team developed and is testing QUIC-Fire. The real-time modeling tool uses 3D maps of fuels and forest structure and accounts for how chemistry, material science, fluid mechanics, and heat transfer interact to influence fire behavior — yet it can run on a laptop computer. “It’s definitely a revolution in modeling and a quantum leap in fire management,” says O’Brien.

QUIC-Fire was created, evaluated, and improved by access to prescribed fire operations, “where we could measure conditions before, during, and after the burn in detailed and extensive ways,” adds O’Brien.

After ten years in development, QUIC-Fire is getting good results in testing.

“We have been building demonstration landscapes on Oconee National Forest and Piedmont National Wildlife Refuge,” says O’Brien. “We’re going to get feedback from the managers who know those lands best. Managers’ insights will mold the product to meet timber stand management objectives. “For example, a land manager could say, ‘We want to manage underbrush without scorching the pines.’”

The new WIFIRE Lab at the University of California, San Diego has integrated QUIC-Fire as the model behind its new prescribed fire decision support tool BurnPro3D.

QUIC-Fire’s developers organized themselves this year as a modeling hub for advanced forest and fire technology. They teamed up with partners from Tall Timbers, the Forest Service’s Pacific Northwest Research Station, Los Alamos National Laboratory, and the University of Georgia.

Based at the Athens Prescribed Fire Lab, the hub includes seven scientists who previously created the Prescribed Fire Science Consortium. The Consortium brought together various fire managers and scientists annually at a burn site to observe, network, share experiences, and vet ideas.

“Anybody who manages land that is prone to fire has insights that are valuable,” says O’Brien. “Our collaboration with Southern Region fire management gave us the exposure to fire operations that generated the insights we are pursuing. Fire managers have the knowledge we need, and there are gaps they need to fill.  There’s respect for each other on both sides.”

“The goal of the modeling hub is to operationalize QUIC-Fire and the framework of required 3D inputs that also serve to revolutionize fire effects assessment and fuels treatment monitoring,” says O’Brien.