Background: Firefighters experience repeated occupational exposure to complex mixtures of carcinogens generated during fire suppression. Epidemiologic studies have consistently reported elevated risks for multiple cancer types among firefighters, yet many investigations rely on indirect exposure metrics, resulting in substantial exposure misclassification. Across the state of Texas, reported cancer cases among firefighters have increased markedly—approximately five-fold compared with estimates reported in earlier statewide assessments—highlighting an urgent need for longitudinal exposure characterization. The present study establishes a comprehensive occupational exposure and biomarker platform to support rigorous evaluation of fireground carcinogen exposure and early biological responses across the professional career continuum.
Objectives: 1) Quantify ambient exposure to fire-related carcinogens including nanoparticles, polycyclic aromatic hydrocarbons [PAHs], and toxic metals during fire suppression and characterize deposition on turnout gear and skin; and 2) evaluate the accumulated exposure to carcinogens for individual firefighters based on their measured exposure levels and work and medical history.
Methods: The current study is a prospective longitudinal cohort study enrolling 700 Texas firefighters across three cohorts (new recruits, active-duty, and retirees) in partnership with municipal fire departments statewide. New and active cohorts complete baseline orientation and biospecimen collection (Visit 1), post-fire suppression sampling within 24 hours (Visit 2), and a six-month follow-up (Visit 3). Retired firefighters complete baseline (Visit 1), six-month (Visit 2), and twelve-month (Visit 3) visits. During fire suppression, field monitoring characterizes inhalation and dermal exposure using personal breathing-zone air sampling and dermal/turnout-gear surface sampling. Real-time aerosol monitoring and integrated air sampling quantify particle size distributions and mass concentrations; filters/sorbents and wipe samples measure PAHs and toxic metals in air and on turnout gear/skin. At each visit, participants complete questionnaires and provide biospecimens (blood, urine, nasal swabs, saliva, and skin) for multi-omics analyses of cancer-related biomarkers.
Results: We will generate integrated carcinogenic exposure profiles and firefighter-specific cancer biomarkers. To date, ~80% new recruits have been enrolled and their baseline sampling has been completed. Primary outcomes are concentrations of nanoparticles, PAHs, and toxic metals in personal/area air measurements and contaminant deposition on turnout gear/skin. Secondary outcomes are molecular changes in cancer-related biomarkers across visits and their associations with measured carcinogenic exposures, adjusting for demographics and occupational factors.
Conclusions/Implications: Integrating direct fireground exposure characterization with repeated biospecimen collection across the professional-career continuum will generate high-resolution exposure profiles and identify exposure-associated molecular signatures relevant to cancer risk. Linkage with work and medical history will enhance objective longitudinal outcome capture beyond study visits. Findings are expected to inform evidence-based interventions and task- and station-level mitigation strategies to reduce carcinogenic exposures and improve firefighter health.