Climate change is increasing the risk of wildfires which frequently extend into the wildland-urban interface (WUI).
WUI fires burn a mixture of vegetation, structures and vehicles and there is a marked research gap regarding
population exposures and health effects. Woodsmoke contains a toxic mixture of known and suspect
carcinogens including but not limited to benzene, aldehydes, and polycyclic aromatic hydrocarbons (PAHs).
However, wildland fire exposure monitoring has generally been limited to particulates for the general public and
PAHs for firefighters. Firefighters, a high exposure group, are requesting participatory research to measure WUI
fire exposures and effects and identify effective interventions. Silicone wrist bands can measure exposure
beyond PAHs, and urine metabolomics can identify both exposures and effects. While cancer or other diseases
caused by firefighting exposures can take many years to develop, metabolomic and epigenetic (microRNA and
DNA methylation) endpoints can serve as sub-clinical biomarkers of toxicity. Interventions of firefighter interest
include rapid provision of exposure data, improved personal protective equipment (PPE), more rapid dermal
decontamination, and administrative controls. We hypothesize that: a) use of silicone wristbands and targeted
urinary analyses (hydroxylated PAHs) will identify high-exposure settings and activities, and that untargeted
metabolomics will reveal novel environmental compounds of concern; b) the urine metabolome and microRNAs
will change acutely with exposures and cumulative exposures will be associated with long-term DNA methylation
changes in firefighters; and c) interventions chosen by firefighters will significantly reduce exposures. We will
test these hypotheses through evaluating firefighter exposures during WUI responses, measuring toxic effects,
and evaluating interventions to reduce exposures. Our fire service research champions have enrolled Los
Angeles County and Orange County firefighters who could respond to WUI fires in the Fire Fighter Cancer Cohort
Study (FFCCS), a fire service-academic community-engaged research collaborative. For the proposed research
we will measure exposures of firefighters during WUI responses using silicone wristbands and pre- and post-
exposure urine for targeted (hydroxylated PAHs) and untargeted (metabolomics) analyses. Occupational
fireground characteristics (type of fire, PPE, time at fire, activities) will be recorded. Using urine and blood
collected at baseline and post-exposure, we will evaluate acute effects with changes in endogenous metabolites
(pre/post urine) and microRNA (pre/post blood). Longer-term changes in DNA methylation will be evaluated
comparing baseline blood samples to three years afterwards. Exposure reduction interventions selected by the
fire service will be evaluated comparing intervention and activity control groups with pre- and post-exposure
wristband and urinary PAH metabolite measurements. We anticipate that the proposed research will provide a
more complete measure of the WUI fire exposure and associated toxicity, and identify interventions that
significantly reduce chemical exposures to firefighters and inform overall public health responses.
