Firefighters from three large cities had higher rates of cancer than the overall U.S. population, according to new research by the National Institute for Occupational Safety and Health.
A combined population of 30,000 firefighters in Chicago, Philadelphia and San Francisco had higher rates of several types of cancers, and of all cancers combined, than the U.S. population as a whole, the NIOSH study found.
The new findings are generally consistent with the results of several previous smaller studies, NIOSH noted.
Because the new study examined a larger population for a longer period of time – six decades – "the results strengthen the scientific evidence for a relation between firefighting and cancer," NIOSH said in a news release.
Reported in the Oct. 14 Occupational and Environmental Medicine journal, the researchers found that:
- Cancers of the respiratory, digestive and urinary systems were the primary drivers of the higher cancer rates 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 that was two times greater than the rate in the U.S. population as a whole. This was the first study to identify an excess of mesothelioma in U.S. firefighters, according to NIOSH. The researchers said the findings likely were associated with exposure to asbestos, a known cause of mesothelioma.
The study analyzed cancers and cancer deaths among 29,993 firefighters from the Chicago, Philadelphia and San Francisco fire departments who were employed since 1950. The research tracked cancer data through 2009.
Firefighters can be exposed to contaminants from fires that are known or suspected to cause cancer. These contaminants include combustion byproducts 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 cancer risk factors, such as smoking, diet and alcohol consumption, NIOSH pointed out.
"In addition, few women and minorities were in the study population, limiting the ability to draw statistical conclusions about their risk for cancer," the agency said.
In a second phase of the study, the researchers will further examine employment records from the three fire departments to gain more insight into occupational exposures, and to look at exposures in relation to cancer incidence and mortality, NIOSH said.