A recent report by the National Institute for Occupational Safety and Health examined the relationship between firefighting and the chances of cancer exposure. The results add to the body of evidence linking firefighting and cancer.
The study comprised of almost 20,000 career firefighters with over 1,300 cancer-related deaths and 2,600 cancer incidence cases.
It is widely accepted that firefighters are potentially exposed to human carcinogens, but the risk of cancer is still poorly understood in the fire service, the report said. The study is among the largest assembled and is the first with adequate statistics for detailed examinations of exposure-response characteristics.
Examining exposure risk
The cohort was compromised of male career firefighters from Chicago, Philadelphia and San Francisco who were on active duty at least one day between the years 1950 and 2009.
For mortality analyses, the at-risk period began on the date of hire and ended at the date of death, date last observed or the end of the study. Cancer risks examined included bladder, colorectal, esophageal, lung, prostate, leukemia and non-Hodgkin’s lymphoma.
Death from chronic obstructive pulmonary disease, ischaemic heart disease, cerebrovascular disease and alcohol-related cirrhosis were also included to help illustrate effects from lifestyle-related risk factors.
The number of days worked in a job or location that had potential for occupational exposure was calculated using combinations of job title and location assignments. A second exposure score used firefighter apparatus assignments and annual fire run information to estimate the total number of fire runs made by each firefighter.
The investigation suggested that fire hours, followed by fire runs, correlates with firefighter exposures.
Results
Among the 19,309 male firefighters eligible for the study, there were a total of 1,333 cancer deaths and 2,609 cancer incidence cases.
The firefighters were mostly white and had an average age at hire of about 28 and 21-years-old. About 79 percent of the cohort was still alive at the end of the study.
There were 16,000 combinations of fire department, apparatus and year used to develop fire runs and fire hours for each firefighter, according to the report. The average career cumulative exposures were about 5,700 exposed days, 6,000 fire runs and 1,500 fire hours.
Six percent of members, mostly paramedics, were not exposed during the observation period.
Researchers found slight, but statistically significant positive exposure-responses for lung cancer and leukemia risk.
Significant positive associations between fire hours and lung cancer mortality were evident. A similar relation between leukemia mortality and fire runs was also found.
Negative associations were evident for the exposure of colon and prostate cancers. This suggests that medical screening may prevent firefighters from dying of these cancers.
These findings reinforced the correlation and add to evidence that firefighting causes some cancers. Future studies will continue to explore these findings and will improve the understanding of cancer risks in the fire service.