August 25, 2022

IARC: Firefighters' Occupational Exposures Cause Cancer

The International Agency for Research on Cancer (IARC) in July announced the classification of occupational exposure as a firefighter as a Group 1 carcinogen, the agency’s designation for agents that carry sufficient evidence of carcinogenicity in humans. A working group of 25 international experts convened by IARC concluded that there is sufficient evidence for mesothelioma and bladder cancer associated with firefighters’ occupational exposures. The group also noted limited evidence for firefighting’s association with colon cancer, prostate cancer, testicular cancer, melanoma of the skin, and non-Hodgkin lymphoma.

Firefighters face a variety of occupational exposures, including combustion products from fires like polycyclic aromatic hydrocarbons, volatile organic compounds, metals, and particulates; diesel exhaust; and building materials such as asbestos. Other hazards can include heat stress, shift work, and ultraviolet and other radiation. Exposure to flame retardants in textiles and chemicals in firefighting foams, including synthetic chemicals like per- and polyfluoroalkyl substances (PFAS), is also of concern.

When IARC previously assessed the carcinogenicity of firefighting in 2007, the agency classified it in Group 2B as “possibly carcinogenic to humans.” Since then, new studies examining the association between occupational exposures among firefighters and cancer risk in people have been conducted. IARC’s new evaluation of firefighting considers 52 cohort and case-control studies, 12 case reports, and seven meta-analyses. According to the agency, some of the most informative research included more than 30 non-overlapping cohort studies that followed firefighters for cancer over time in Asia, Europe, North America, and Oceania.

A summary of IARC’s evaluation is available online in The Lancet Oncology. The full article is available free of charge to registered users (registration is also free). Further details are available in an IARC press release (PDF).

IARC’s detailed assessment of the carcinogenicity of firefighting will be published next year in Volume 132 of the IARC Monographs. IARC monographs identify and evaluate substances or agents that can increase carcinogenic risks to humans. IARC is the specialized cancer agency of the World Health Organization.