That greater recognition took place at the 2022 meeting of the International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organization, where a working group of 25 scientists representing eight countries concluded that occupational exposure within the
That greater recognition took place at the 2022 meeting of the International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organization, where a working group of 25 scientists representing eight countries concluded that occupational exposure within the firefighting environment is carcinogenic, upgrading the previous classification from possibly carcinogenic when IARC first reviewed firefighting in 2007. The researchers decided there was sufficient evidence that occupational exposure causes mesothelioma and bladder cancer, while still elevated but more limited evidence that exposure causes colon, prostate and testicular cancers, melanoma of the skin, and non-Hodgkin lymphoma.
Furthermore, the working group found strong evidence that occupational exposures in firefighters led to five key toxic mechanisms known to contribute to cancer, including DNA damage, epigenetic changes, chronic inflammation, oxidative stress, and receptor-mediated effects.
The change in IARC determination was based on many new research studies on exposures, toxic mechanisms, and cancer rates in firefighters. These included exposure and toxic mechanism studies conducted as part of a long-time partnership between the firefighters with the Tucson Fire Department (TFD) and researchers at the University of Arizona Health Sciences, led by TFD Chief Darin Wallentine and Jeff Burgess, MD, MPH, MS, Professor at the University of Arizona Mel and Enid Zuckerman College of Public Health. Burgess was also an invited specialist within the IARC working group.
“Upgrading the classification to carcinogenic has essentially upgraded the quality of life for millions of firefighters throughout the world.” said Wallentine.
“Now we need to work collaboratively with the fire service to find ways to reduce cancer risk.” Burgess stressed.
Discovering Toxic Mechanisms
The TFD-University of Arizona team, working with Jackie Goodrich, PhD, Research Associate Professor at the University of Michigan School of Public Health, conducted groundbreaking research identifying some of the toxic mechanisms of firefighting exposures, particularly the role of epigenetic changes, which increase or decrease gene expression and are essential steps in the development of cancer. Exposures to smoke from fires and other exposures such as per- and polyfluoroalkyl may be altering the epigenome over time, eventually leading to disease development, notably among firefighters.
With the significant new data for firefighters, Burgess noted, “We have known there is a higher incidence of cancer among firefighters, and this research potentially shows us the mechanism through which the exposures that firefighters face leads to increased health risks.”
Epigenetic regulators are modifications to DNA that control whether genes are turned on or off. Epigenetic alterations by exposures reflect subtle biological changes contributing to subsequent disease risk and development, he explained.
Several of the findings, specifically the epigenetic and receptor-mediated mechanisms of cancer, were conducted by the University of Arizona and University of Michigan research team members in collaboration with the TFD led by Wallentine. He is retired from the TFD and now serves as Deputy Fire Chief for the Sarasota County Fire Department in Florida, and currently serves on the Board of Directors for the International Association of Fire Chiefs Safety, Health, and Survival Section with a mission to reduce the number of preventable line-of-duty deaths and injuries in the fire and emergency service.
Wallentine was a member of a three-person team coordinating the collection of biologicals, including u