(CNN) An already dangerous profession may be more high-risk than expected.
Florida firefighters have a slightly increased risk for developing skin cancer, according to a study published Wednesday in the journal JAMA Dermatology.
The increased risk seen in that state raises questions about skin cancer rates among firefighters across the nation. So far, though, only Florida has been studied.
"Not sure we can extrapolate the Florida experience to the national level. We are not there yet," said Alberto J. Caban-Martinez, an author of the new study and an assistant professor of public health sciences at the University of Miami Miller School of Medicine. He and his colleagues continue to research the issue in the hopes of answering this and other questions.
Caban-Martinez and his colleagues created the Firefighter Cancer Initiative to learn more about what previous studies have shown: that firefighters have more risk for certain types of cancer than the general population.
"What is it about their work environment that could be increasing their risk?" Caban-Martinez asked.
The new study is based on one project within the initiative: The Annual Cancer Survey, a 127-item cancer questionnaire. A total of 2,399 Florida firefighters completed the survey, answering questions about risk factors for cancer and their behavior. On average, the respondents were nearly 42 years old and had been on the job for about 15 years.
Overall, 109 of the firefighter respondents reported skin cancer: Seventeen had melanoma, the most dangerous form, which is likely to grow and spread; 84 had non-melanoma, the most common and most easily treated type of skin cancer; and 18 had some unknown skin cancer type.
The frequency of melanoma was 0.7% among the firefighters surveyed and 0.01% among the general Florida population, the researchers found.
The firefighters were also diagnosed at much younger ages than usual, according to the study. The average age at diagnosis for melanoma was about 42 among the firefighters, versus 64 for the general US population.
Surprised by these findings, Caban-Martinez and his team became curious about what could be increasing the firefighters' risk for cancer.
"They do wear protective gear while they're out battling fires, but we've noticed that there are gaps in their gear coverage around the waist, around the wrists, around the neck," Caban-Martinez said, adding that those gaps may be where soot enters and changes some of their skin cells.
During the Industrial Revolution, chimney sweeps who cleaned away soot inside smokestacks developed scrotal cancer more frequently than the general population, he said. Today, soot is a well-researched carcinogen.
"The soot as they're sweating dripped everything into their groin area, and it would concentrate there, and hygiene at the time was not as good, so they would developed scrotal cancer," Caban-Martinez explained.
This relates to contemporary firefighters, he said, citing those now working on the California wildfires.
"All these firefighters are working extended shifts, and they're tired and exhausted, so decontamination procedures probably go out the window just because they got to get to the next fire," Caban-Martinez said. Firefighters sometimes just throw their equipment into the truck and then soot contaminates the fire station, leading to exposure and ultimately skin cancer, he said. This could explain the higher skin cancer incidence among the Florida firefighters.
Another potential explanation: Florida is a sunny state, and ultraviolet light may be synergistic with the carcinogenic chemicals, he said. Or some firefighters may be exposed to harmful substances when working a second job in, say, construction or landscaping.
The research team now wants to find out why and how firefighters are developing skin cancer at higher rates than the general population.
"We need to get down to the biology of it," Caban-Martinez said. "Figure out how to prevent them from getting it."