The International Agency for Research on Cancer 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. The number of firefighters worldwide exceeds 15 million, according to IARC. 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. IARC noted that firefighters often rely on personal protective equipment such as self-contained breathing apparatus but that “dermal absorption of chemicals can occur even in firefighters wearing PPE due to limitations of its design, fit, maintenance, or decontamination.” 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. There are approximately 1.1 million firefighters in the United States, according to NIOSH. An agency study completed in 2015 of nearly 30,000 firefighters found higher rates of several types of cancers than in the U.S. population as a whole. The rate of mesothelioma among the study population was twice as high as in the general population, likely due to firefighters’ occupational exposure to asbestos. The study also found higher incidence of cancers of the respiratory, digestive, and urinary systems among firefighters. Within the study cohort, the amount of time spent at fires correlated to increased chance of lung cancer diagnoses, and the chance of death from leukemia increased with the number of fire runs. In 2018, Congress passed legislation requiring the establishment of a National Firefighter Cancer Registry to monitor incidence of cancer among firefighters. The voluntary registry is being established by NIOSH and was expected to begin accepting registrations in autumn of this year. For more information, visit the NIOSH website. NIOSH resources related to firefighters and cancer are also available from the agency. 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 series.

A new project proposed by NIOSH would evaluate sleep and fatigue among oil and gas extraction workers and examine these and other factors’ relationship to risks in the industry. Researchers plan to measure sleep and alertness among workers; gather information related to demographics, working hours, commute times, and sleep quality; and interview workers, supervisors, subject matter experts, and others regarding the challenges related to fatigue management. According to NIOSH, worker fatigue is commonly associated with nonstandard work schedules, stress, physically and mentally demanding tasks, and working in hot environments. Fatigue can result in slower reaction times, affect cognition and sleep, and contribute to numerous negative health effects, including cancer, cardiovascular disease, and psychological disorders. Investigations have found that worker fatigue has been a contributing factor to high-profile disasters, including the Three Mile Island nuclear meltdown and Exxon Valdez oil tanker accidents. For more information, read the Federal Register notice.

Concerns regarding the user instructions for several filtering facepiece respirators (FFRs) manufactured by NIOSH approval holders prompted the agency to publish a notice stressing that agency-approved respirators cannot be altered to improve fit. According to the notice, NIOSH has identified some statements instructing users to modify FFRs—for example, by tying knots in the headbands to create a tighter fit. The agency cautions users that some FFRs with instructions containing similar statements were distributed when NIOSH failed to identify the concern before issuing approvals. NIOSH says that it is notifying approval holders to correct their user instructions as issues are identified. NIOSH’s notice reminds those who are required to use respiratory protection in occupational settings that if a user cannot achieve a proper fit, the respirator configuration should not be modified in any way. Instead, another product should be selected for use, the agency says.