New research from UTHealth Houston found firefighters experience measurable biological changes in their blood and urine within 24 hours of fighting a fire–changes that may help identify early cancer risk, the leading cause of death among firefighters.
The study was published in Environment & Health and led by Jooyeon Hwang , PhD, associate professor in the Department of Environmental and Occupational Health Sciences at UTHealth Houston School of Public Health.
Repeated exposure to harmful chemicals such as particles, heavy metals, and polycyclic aromatic hydrocarbons in fire smoke, common in the work of firefighters, can cause long-term chronic health problems including cancer, according to previous work by Hwang.
In this study, researchers analyzed blood and urine samples from 30 firefighters before and after fire exposure to better understand how the body immediately responds. The team identified and quantified a baseline of 330 protein groups in blood serum and 1,085 in urine samples. Post-exposure analysis uncovered clear exposure-related shifts, revealing 75 significantly altered proteins in urine after exposure compared to just 10 in blood serum.
Urine showed the broadest and most sensitive changes, with several proteins linked to cancer-related pathways, including those associated with small-cell lung cancer. Specifically, the researchers discovered that fighting a fire triggers a synchronized shift in a network of four key proteins (LAMA4, LAMC1, VWF, and B2M). Within 24 hours of exposure, these proteins change in a pattern that closely mirrors early cancer pathways, indicating that toxic smoke may cause immediate cancer-related cellular stress and temporarily weaken the body's natural immune defenses against tumor development.
“ Firefighters put their lives on the line to protect our communities, but they return from the fireground carrying an invisible toxic burden that silently increases their risk of cancer,” said Hwang, who also serves as deputy director of Southwest Center for Occupational and Environmental Health and program director of Industrial Hygiene and Exposure Sciences at the School of Public Health. “Our study shows that we do not have to wait years for chronic illnesses to manifest. The body's proteins react almost immediately. By demonstrating that urine is a remarkably sensitive, noninvasive way to capture these early cellular distress signals, we are opening the door to detecting risk long before a disease develops. This isn't just about collecting data. It is about developing the tools we need to safeguard the health of our first responders–firefighters.”
Researchers hope to take these discoveries from the lab and put them directly to work in the fire service. Hwang says the next step is to expand this research into larger longitudinal studies, such as the Texas Firefighter Cancer Study , to see how these protein patterns behave over time. “Ultimately, we hope to integrate advanced biomarker screening into standard occupational health assessments, like the National Fire Protection Association 1580 guidelines. By establishing routine, molecular-level screening and personalized hydration protocols to help clear these toxins from the kidneys, we can transition firefighter medicine from a reactive model to proactive, precision-based prevention,” she said.
Other authors on the study include Nagib Ahsan, PhD; Zongkai Peng; Amit Singh; Zhibo Yang, PhD; and Chao Xu, PhD, with The University of Oklahoma; Robert J. Agnew, PhD, with Oklahoma State University; and Xin Xu, PhD, with Shanghai University of Sport.
Environment & Health