Firefighters are at a far higher risk of developing certain cancers than people in many other professions, US research suggests.
Exposure to chemicals may add to firefighters' risk
A University of Cincinnati team said exposure to substances such as benzene, chloroform and soot posed a threat.
Rates of testicular cancer were 100% higher and prostate cancer 28% higher among firefighters, their analysis of 32 US and European studies suggested.
UK experts said it emphasised the need for monitoring of workplace chemicals.
The US researchers looked at studies covering 110,000 firefighters, which compared cancer rates in that profession with the general population or other professions, the Journal of Occupational and Environmental Medicine reported.
In addition to the 100% increase in testicular cancer cases among firefighters, the researchers also discovered a 50% increase in non-Hodgkin's lymphoma and multiple myeloma.
The researchers say firefighters are exposed to many compounds designated as carcinogens, or cancer-causing agents, by the International Agency for Research on Cancer - including benzene, chloroform, soot, styrene and formaldehyde.
These can be inhaled or absorbed through the skin at the scene of a fire.
Dr Grace LeMasters, who led the research, said firefighters' protective equipment was "heavy, cumbersome and uncomfortable to wear and they don't like it.
"So as soon as they come out of the fire, they take it off.
"But there's a lot of soot and chemicals in there which they are being exposed to."
James Lockey, professor of environmental health and pulmonary medicine at the university, also worked on the research and said: "There's a critical and immediate need for additional protective equipment to help firefighters avoid inhalation and skin exposures to known and suspected occupational carcinogen.
"In addition, firefighters should meticulously wash their entire body to remove soot and other residues from fires to avoid skin exposure."
Henry Scowcroft, science information officer at Cancer Research UK, said: "This research highlights the need to constantly monitor and assess people's workplace exposure to cancer-causing chemicals, so that firefighters and other at-risk groups are properly protected whilst carrying out their jobs.
"Scientists estimate that occupational exposure to harmful chemicals is responsible for about 2% of cancer deaths in the UK.
"It is important to remember that this affects only a small number of people in very specific jobs."