Studies have shown that firefighters are at an increased risk for brain cancer, compared to the usual control group – police officers, who are often under comparable stress.
Of 14 studies on the mortality of firefighters, 11 found excess risk for brain cancer.
One study of 5,414 Toronto firefighters found 14 deaths from brain or nervous system cancers among the 777 firefighters who died during the period of the study. The study referred to this as a statistically significant finding. (In 1994, brain cancer was the cause of death in 2.6 per cent of those Canadian males who died).
Earlier studies of firefighter mortality that did not identify brain cancer as a cause of death were done before the widespread introduction of plastics in the 1950s.
There are two types of brain tumours. Gliomas are primary tumours that arise in the brain. Secondary tumours are cancers that travel from another part of the body.
General causes for primary brain cancer can include a prior head injury, infections, exposure to chemical toxins such as insecticides and fungicides and exposure to radiation such as microwave or radio
Possible causative agents for brain cancer in firefighters include vinyl chloride, acrylonitrile and formaldehyde.
Studies show an elevated (but so far not statistically significant) risk of lymphatic and haemotopoietic cancers for most firefighters. There is, however, a statistically significant risk for firefighters with more than 30 years of service.
Lymphatic and haemotopoietic cancers are cancers of the various types of "blood-borne" cells. They include cancers of white blood cells, and those found in the spleen, liver, lymph nodes and bone marrow. The best known of these cancers is leukemia, which creates "abnormal populations" of white blood cells.
Possible causative agents for those cancers in firefighters include benzene, soots, PAH, vinyl chloride and acrylontrile.
There are mixed results on studies of colon cancer and firefighters. Three studies showed a link between firefighters and colon cancer. Five showed a possible link. Four found the increase in risk was not statistically significant and seven found no increase or even fewer deaths than the general population. The Ontario firefighters report concludes that there is a probable connection between firefighting and colon cancer
If there is a link, possible causes are diesel exhaust and asbestos.
There are also mixed results of studies linking bladder cancer and firefighting. Three studies found an increased risk. One found a possible link and five found that the increase in risk was not statistically
significant. The Ontario report found a probable connection between firefighting and bladder cancer.
If there is a link, possible causes are diesel exhaust and formaldehyde.
Studies of the link between kidney cancer and firefighting also show mixed results. Two studies found a risk, and three found links that were not statistically significant. Two found a possible link and four found no increase or a decreased risk. The Ontario report found a probable link between firefighting and cancer even though the evidence was inconsistent.
If there is a link, possible causes are polycyclic aromatic hydrocarbons.