Introducing the National Firefighter Registry for Cancer

the Synergist

A New Effort to Understand and Reduce Cancer in Firefighters

BY KENNETH FENT, MIRIAM SIEGEL, ALEX MAYER, AND ANDREA WILKINSON

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As industrial hygienists and occupational health professionals, we need to understand a process to be able to improve it. Our job involves observation to determine what tasks might increase exposures or put workers at risk. Our observations are often conducted in tandem with sampling to produce quantifiable information from which we can draw conclusions.

The same holds true for understanding disease trends among workers. If we want to improve occupational health outcomes, we need to fully understand workers’ jobs as well as the types and burden of diseases.

CURRENT UNDERSTANDING OF CANCER IN FIREFIGHTERS Several studies have indicated that firefighters have an increased risk of certain types of cancer. In the largest firefighter cohort study on cancer incidence and mortality in the United States, NIOSH found that firefighters employed at three municipal fire departments between 1950 and 2009 had an increased risk of being diagnosed with or dying from certain digestive, urinary, respiratory, and oral cancers when compared to the general U.S. population. In the same cohort, NIOSH found increased risk for lung cancer and leukemia with increasing exposure—for example, more fire hours, or total time spent at fires, or more fire runs. These studies were published in Occupational and Environmental Medicine in 2014 and 2015, respectively, and are listed among the resources below.

Earlier, in 2010, the International Agency for Research on Cancer (IARC) had classified the occupation of firefighting in Group 2B as “possibly carcinogenic to humans.” Just this past summer, IARC assembled the world’s experts on firefighters’ exposures, toxicity, and cancer to reevaluate the occupation of firefighting for carcinogenicity based on new epidemiological and biomechanistic evidence. The IARC working group conducted a review and meta-analysis of the literature and reached a new consensus, classifying firefighting as a Group 1 “known human carcinogen” based on sufficient evidence related to bladder cancer and mesothelioma in firefighters. The working group also found limited evidence for carcinogenicity related to five other cancers in firefighters: colon, prostate, testicular, melanoma of skin, and non-Hodgkin lymphoma. A summary of IARC’s evaluation is available online in The Lancet Oncology.

If we are successful, the NFR will be the largest cohort of firefighters and one of the largest occupational cohorts ever assembled.

KNOWLEDGE GAPS The latest IARC evaluation makes clear that there is sufficient evidence that firefighting can increase the risk of certain types of cancer, but many knowledge gaps related to cancer among firefighters remain. For example, very few studies have included enough women or non-white firefighters to draw conclusions about their risk of cancer.

There is also little research on cancer in volunteer firefighters. NFPA, the National Fire Protection Association, estimates that volunteer firefighters made up around 65 percent of the firefighting workforce in 2020, so their underrepresentation in firefighter cancer research is an especially large, missing piece of the puzzle.

Firefighters in subspecialties like fire-cause investigation, firefighter training, and wildland firefighting are also underrepresented in cancer research. Notably, wildfires are an emerging threat that is growing in frequency and intensity in many parts of the United States. Wildfires are more frequently encroaching on urban areas, as discussed in a 2018 research article in the Proceedings of the National Academy of Sciences, which describes this wildland-urban interface as “the area where houses and wildland vegetation meet or intermingle, and where wildfire problems are most pronounced.” These factors may be exacerbating or changing the magnitude and composition of exposures for wildland firefighters or structural firefighters who respond to wildfires.

Many types of cancer have yet to be thoroughly examined in firefighter health research because studies often lack enough cases to analyze. Therefore, substantial room for growth exists when it comes to understanding firefighting as a risk factor for specific cancer types.

EXPOSURES AND CONTROLS Several studies over the last decade have increased our understanding of firefighters’ unique exposure pathways. Exposure concerns include what firefighters may inhale at a fire incident when not wearing respiratory protection, like self-contained breath apparatus (SCBA), as well as what compounds contaminate and absorb through skin. Dermal exposure to combustion byproducts may happen not only during structural firefighting via ingress of contaminants through openings in turnout gear, but also after firefighting when firefighters remove contaminated turnout gear. Firefighters’ hands are especially likely to become contaminated from handling soot-covered gear and equipment, which also poses an inadvertent ingestion risk depending on hand hygiene. Neck skin is another vulnerable area for exposure due to incomplete dermal exposure protection from knit hoods and the fact that many firefighters pull their contaminated hoods down around their neck after firefighting. (An article published in Ergonomics in 2021 discusses how the design, laundering, and doffing of hoods affects their ability to protect firefighters from contamination.)

Because of this contamination, some fire departments now have policies and procedures to gross-decontaminate gear on scene after a fire response, place the gear in containers for transport back to the firehouse, and in some cases launder gear at the firehouse or via a professional service. Many fire departments also provide skin cleansing wipes or soap and water for firefighters to clean their skin on scene and encourage them to shower immediately upon return to the firehouse.

Some studies have documented the effectiveness of these measures at reducing exposure (for example, one published in 2020 in the Journal of Occupational and Environmental Medicine evaluated interventions to reduce firefighter exposures). However, even when firefighters adopt industry best practices including consistent use of SCBA and the various skin and PPE decontamination measures, studies have still documented absorption of combustion byproducts including polycyclic aromatic hydrocarbons (PAHs) and benzene (for instance, see a 2020 study published in the Journal of Exposure Science & Environmental Epidemiology). Reducing firefighters’ exposure to carcinogens is clearly important, and some of these control interventions have shown promise in doing just that. However, the impact that these measures have on reducing firefighters’ risk of developing cancer is largely unknown.

THE NATIONAL FIREFIGHTER REGISTRY FOR CANCER To help fill the remaining knowledge gaps and better understand the burden of cancer and cancer risk factors within the fire service, it’s necessary to assemble a large and diverse cohort of firefighters that can be followed over a long period. That is where the National Firefighter Registry (NFR) for Cancer comes into play. The NFR will function as a voluntary exposure surveillance system of firefighters designed to be linked with health surveillance systems, including population-based cancer registries.

The NFR was created through the Firefighter Cancer Registry Act of 2018. This Act mandates that CDC/NIOSH “develop and maintain . . . a voluntary registry of firefighters to collect relevant health and occupational information . . . for purposes of determining cancer incidence.” In the first year of the program (2019), NIOSH established the NFR Subcommittee—a subcommittee of the NIOSH Board of Scientific Counselors—to provide guidance to NIOSH on designing and carrying out the NFR. The NFR Subcommittee includes 13 subject matter experts in the fields of epidemiology, public health, medicine, and fire and emergency services. This subcommittee had a large role in defining key components of the NFR, which include: • collecting self-reported information from firefighters on workplace and personal characteristics through a secure web portal • obtaining records from fire departments or agencies to track trends and patterns of exposure • linking individual profiles in the NFR with health information databases including population-based cancer registries and the National Death Index (NDI) to evaluate cancer incidence and mortality • making de-identified data available for external researchers

For the NFR to be successful, it is critical that all current and former firefighters in the United States know that they are eligible to enroll, not just those with cancer.

Firefighters will enroll by accessing the secure web portal, creating a Login.gov account, reading and signing the consent form, and then creating a user profile and completing the enrollment questionnaire. The questionnaire, which is the longest part of the process (requiring around 20 to 30 minutes to complete), collects information on demographics, work history, health history, and lifestyle.

The work history section of the questionnaire gathers detailed information to use for exposure assessment. For example, firefighters are asked to provide details regarding departments they’ve served in, job titles they’ve held, and the numbers and types of fire responses per department or job. There are questions about if and when participants began practicing specific control interventions throughout their careers. Participants are also able to list major events that were unusual in length or severity, such as natural disasters or chemical incidents.

All questions are optional except for date of birth and sex at birth, which are needed to ensure participants meet age requirements and to populate sex-specific questions. The only eligibility requirements are that participants must be 18 years of age or older and have served as a firefighter at some point in their lifetime.

This poster encourages joining the NFR. Available for download from the NIOSH website.

Landing page for the NFR web portal as viewed on a mobile device.

This poster promotes the NFR using artwork from cartoonist Paul Combs. Available for download from the NIOSH website.

NIOSH is especially interested in ensuring heavy participation from women, non-white, and volunteer firefighters, which are all groups that were specified in the Act because they have been underrepresented in previous cancer studies. Other groups that have been underrepresented in cancer studies include fire instructors, fire investigators, and wildland firefighters. If we want to understand whether exposures and cancer outcomes differ for these specific groups, we need them to participate in the NFR in large numbers.

RECRUITMENT AND ENROLLMENT Because participation in the NFR is voluntary, it is important for NIOSH to disseminate detailed and clear information about the registry so that firefighters can make informed decisions about their participation. The voluntary nature of the NFR lends itself to selection bias if some groups of firefighters are more likely to enroll than others. Therefore, NIOSH developed a multi-faceted enrollment plan to help recruit a large, diverse group of firefighters, which in turn will help improve the generalizability of the NFR to the national firefighting workforce.

NIOSH is working with many fire service professional organizations and affinity groups to reach firefighters with different backgrounds and experiences. We have created communication materials such as informative videos, fact sheets, posters, and social media posts, all of which are freely available from the NIOSH website. We have presented to fire service audiences across the country, and we have further introduced the NFR to firefighters by hosting booths at large firefighter conferences and meetings. NIOSH will continue many of these communication activities over time to maximize awareness of and participation in the NFR.

Agency investigators will focus additional, targeted enrollment efforts on recruiting firefighters from selected departments to boost participation rates and improve participation from firefighters who may be less likely to enroll. Regardless, all individual firefighters who wish to participate will register for the NFR in the same fashion and have the ability to enroll at any time.

NIOSH also plans to leverage relationships with selected fire departments to collect incident and employment records that will help agency investigators estimate firefighters’ exposures over time. Such records can also be compared against self-reported response details in the enrollment questionnaire to evaluate the accuracy and precision of the self-reported data. These data sources will be used to generate job exposure matrices and conduct exposure-response analyses, which have largely been neglected in past studies on firefighter cancer.

Our objective is to enroll 200,000 or more firefighters over the next few years. NIOSH intends to continuously enroll firefighters across the country and over time to achieve that goal. If we are successful, the NFR will be the largest cohort of firefighters and one of the largest occupational cohorts ever assembled. For perspective, the highly successful Nurses’ Health Study, which began in 1976 and continues today, currently has more than 275,000 participants.

FOLLOW-UP QUESTIONNAIRES AND DATA LINKAGES NIOSH plans to administer follow-up questionnaires to collect longitudinal information on occupational and non-occupational factors that may affect cancer risk. These questionnaires will be optional. We know that some firefighters will choose not to participate in these follow-up questionnaires. However, it is important to note that even if we never hear from firefighters after their initial enrollment, we can still use the information they provide at enrollment (name, date of birth, residential address, and last four digits of their social security number, for example) to match against health outcome databases, namely state cancer registries and the NDI.

Cancer is a nationally notifiable illness in the United States, meaning that healthcare institutions must collect and report data on cancer patients to population-based, central cancer registries maintained by a state, territory, or other jurisdiction. NIOSH plans to perform linkages between data collected in the NFR to information on cancer diagnoses and outcomes from all state cancer registries on a periodic basis (likely every few years). This will enable NIOSH to track cancer diagnoses among NFR participants. By conducting linkages to the NDI, NIOSH will also be able to track cancer mortality and other causes of death among participants who pass away after registering. The NFR will be used to analyze cancer incidence among participants prospectively. Cancer is typically characterized by a long latency period, so linkages to health outcome databases like population-based cancer registries and the NDI will need to occur for decades to maximize the potential impact of the data collection.

MAXIMIZING IMPACT Another way to maximize the impact of the NFR is to make de-identified data available to external researchers, which is mandated under the Firefighter Cancer Registry Act of 2018. The NFR program has an assurance of confidentiality, which requires that NIOSH maintain participants’ privacy and establishes the parameters by which data can be shared. In the future, external researchers will be able to apply for access to de-identified data collected in the NFR. External researchers will only have access to the de-identified data through a secure and restricted mechanism, such as a research data center. Nevertheless, external researchers’ access to the data means that additional comprehensive and robust analyses can be performed, summarized, and disseminated to decision makers who can do something positive and meaningful with the results.

NIOSH has a rich history of working closely with the fire service to understand and improve firefighters’ equipment, working conditions, and health outcomes. The NFR is the latest program at NIOSH that aims to help firefighters, with the ultimate goal of reducing their risk of cancer. The fire service has provided substantial input in the design of the NFR. Their input, along with that from other experts, has resulted in a system that will greatly improve our collective understanding of firefighting and its relationship with cancer. Moreover, the NFR provides a mechanism for identifying important factors associated with cancer risk, which can then inform interventions or policies to lessen that risk.

The NFR has the potential to become one of the most important occupational health programs ever developed in the United States. We aspire to equip the fire service and public health professionals with critical data and knowledge that can support policies and procedures and protect firefighters for generations to come.

KENNETH FENT, PhD, CIH, is the head of the National Firefighter Registry Program at NIOSH and a research industrial hygienist by training. He is a member of AIHA and has published more than 80 scientific articles and reports.

MIRIAM SIEGEL, DrPH, MPH, is the lead epidemiologist for the National Firefighter Registry for Cancer. She has also worked on a range of projects related to reproductive health, outbreak investigation, and workplace violence.

ALEX MAYER, MPH, is a health scientist for the National Firefighter Registry Program at NIOSH. He has published more than 20 scientific articles and reports.

ANDREA WILKINSON, MS, is a health scientist at NIOSH working on the National Firefighter Registry for Cancer and a member of CDC’s Global Rapid Response Team. She has extensive experience in cardiac rehabilitation, athletic training, and exercise physiology.

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Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention.

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RESOURCES

Ergonomics: “Effects of Firefighting Hood Design, Laundering and Doffing on Smoke Protection, Heat Stress and Wearability” (2021).

Journal of Exposure Science & Environmental Epidemiology: “Firefighters’ Absorption of PAHs and VOCs during Controlled Residential Fires by Job Assignment and Fire Attack Tactic” (2020).

Journal of Occupational and Environmental Medicine: “Evaluation of Interventions to Reduce Firefighter Exposures” (2020).

The Lancet Oncology: “Carcinogenicity of Occupational Exposure as a Firefighter” (2022).

NFPA: “U.S. Fire Department Profile 2020” (PDF, 2022).

NIOSH: “Communication Materials – National Firefighter Registry (NFR) for Cancer.”

NIOSH: “National Firefighter Registry Subcommittee (NFRS).”

Occupational and Environmental Medicine: “Exposure-Response Relationships for Select Cancer and Non-Cancer Health Outcomes in a Cohort of U.S. Firefighters from San Francisco, Chicago and Philadelphia (1950-2009)” (2015).

Occupational and Environmental Medicine: “Mortality and Cancer Incidence in a Pooled Cohort of U.S. Firefighters from San Francisco, Chicago and Philadelphia (1950-2009)” (2014).

Proceedings of the National Academy of Sciences: “Rapid Growth of the U.S. Wildland-Urban Interface Raises Wildfire Risk” (2018).