November 5, 2013: Study of Cancer among Firefighters
Posted On: Nov 05, 2013
Study of Cancer among Firefighters
A U.S. Fire Administration (USFA) and National Institute for Occupational Safety and Health (NIOSH) research project to clarify the relationship between firefighter occupational exposures and cancer.
After examining mortality patterns and cancer incidence among a group of 29,993 U.S. career firefighters employed between 1950–2009 in the cities of San Francisco, Chicago and Philadelphia, the researchers found that:
Cancers of the respiratory, digestive, and urinary systems accounted mostly for the higher rates of cancer seen in the study population. The higher rates suggest that firefighters are more likely to develop those cancers.
The population of firefighters in the study had a rate of mesothelioma two times greater than the rate in the U.S. population as a whole. This was the first study ever to identify an excess of mesothelioma in U.S. firefighters. The researchers said it was likely that the findings were associated with exposure to asbestos, a known cause of mesothelioma.
The study analyzed cancers and cancer deaths through 2009 among 29,993 firefighters from the Chicago, Philadelphia and San Francisco fire departments who were employed since 1950.
Firefighters can be exposed to contaminants from fires that are known or suspected to cause cancer. These contaminants include combustion by-products such as benzene and formaldehyde, and materials in debris such as asbestos from older structures.
The findings of the new study do not address other factors that can influence risk for cancer, such as smoking, diet and alcohol consumption. In addition, few women and minorities were in the study population, limiting the ability to draw statistical conclusions about their risk for cancer.
USFA and NIOSH partnered on a study to examine the potential for increased risk of cancer among firefighters due to exposures from smoke, soot and other contaminants in the line of duty. This was a formal epidemiological study with medical oversight.
The primary objective of the project was to clarify the relationship between firefighter occupational exposures and cancer. The project improves upon previously published firefighter studies by significantly increasing the study group size and person-years at risk, and using a more detailed exposure surrogate metric in both the mortality and incidence analyses than are found in most previous studies. These improvements increase the precision of disease risk estimates.
This NIOSH study supported by USFA was intended to fill gaps in current knowledge and inform ongoing efforts to further characterize the cancer risk associated with certain exposures. By analyzing deaths and cancer cases among firefighters, NIOSH attempted to determine whether:
More cancers than expected occurred among the group.
Cancers are definitively associated with exposures to the contaminants to which firefighters may have been exposed.
In collaboration with the National Cancer Institute and the University of California at Davis – Department of Public Health Sciences, NIOSH researchers found that a combined population of almost 30,000 firefighters from three large cities had higher rates of several types of cancers, and of all cancers combined, than the U.S. population as a whole.
These findings are generally consistent with the results of several previous, smaller studies. Because this new study had a larger study population followed for a longer period of time, the results strengthen the scientific evidence for a relation between firefighting and cancer.
Next Study Phase
In a second phase of the study, the researchers will further examine employment records from the same three fire departments to derive information on occupational exposures, and to look at exposures in relation to cancer incidence and mortality. Those findings, when completed, will be published in a future article.