Little research so far on long-term effects

Wildland firefighters face many risks on the job — working near flames in thick smoke with heavy machinery and sharp tools — but there has been relatively little research into the long-term health impacts of their work.

A new law creating a voluntary nationwide registry of cancers in firefighters acknowledges this gap. “Firefighting is one of the most hazardous yet least studied occupations in terms of exposure effects and the relationship to occupational disease,” according to the Firefighter Cancer Registry Act, which was signed by Pres. Trump in July.


Although smoke is an inevitable fact of life for firefighters, there hasn’t been enough research to determine whether firefighters suffer long-term effects from exposure. Some research suggests that smoke exposure can have permanent impacts, but other studies found that most firefighters recover quickly.

A few recent studies found an association between smoke exposure from a wildland fire, primarily fine particulate matter, and cardiovascular disease. But “the health effects of acute exposures beyond susceptible populations and the effects of chronic exposures experienced by the wildland firefighter are largely unknown,” said the researchers.

Moreover, wildland firefighters are exposed to different substances than municipal firefighters, who have been studied more extensively. Because these work environments are so different, research on structure firefighters may not be applicable to wildland crews, according to research published last year in the journal Toxicology.

Respiratory problems are estimated to affect 5 to 10 percent of wildland firefighters, according to a study by the National Institute for Occupational Safety and Health (NIOSH). Depending on the chemical make-up and size of smoke particles, health effects can vary, but all have the potential to damage DNA, researchers found.

Smoke from forest fires contains particulates that can temporarily reduce pulmonary function, according to a 1994 study by the U.S. Forest Service. With adequate recovery time, a healthy respiratory system can cleanse itself. People with asthma or other conditions may lose some of the body’s ability to protect the lungs, they said.

Conditions exacerbate risks

Not only do firefighters perform arduous physical work, but they often work on steep terrain in intense heat while wearing fire-resistant clothing that is anything but lightweight and breathable.

Still, studies haven’t found severe heat-related illnesses, especially when firefighters are fit and hydrated, according to the Forest Service.

Fatigue is an important factor in accidents among fire crews, who work long hours in demanding conditions. Those risks are exacerbated by the difficulty of getting adequate rest in a tent at fire camp. In fact, incident management teams sometimes put night crews up in motels so they can get adequate rest.

Randall Brooks, a professor at the University of Idaho, studied prolonged exertion and lack of sleep on firefighters’ reaction time and found a marked effect on alertness. In a survey of more than 400 wildland firefighters, Brooks found that the main contributors to accidents were inadequate sleep and mental and physical fatigue.

In some cases, reaction times were reduced so dramatically that it was analogous to being impaired by alcohol when driving, Brooks found. With longer fire seasons — an average 30 days longer than they were 30 years ago — these impacts are magnified, he said.

Firefighters are advised to consume at least 6,000 calories a day to have adequate energy. Although the U.S. Forest Service takes this into account when preparing food for fire crews, smokejumpers and other specialized crews who stay overnight near a fire tend to eat pre-packaged snacks rather than a complete meal. Researchers found that, despite considerable physical exertion, these firefighters lost muscle mass and gained fat over the summer.

Everyday risks

Many health issues faced by firefighters are fairly ordinary. Firefighters combating the Crescent Mountain and McLeod fires this summer suffered allergic reactions to bee stings, slips and falls on the fire line and in camp, and bouts of “camp crud,” said Kimberly Nelson, a public information officer with the Northern Rockies National Incident Management Team.

The most serious injury for the Northern Rockies team was a firefighter who was injured when a large snag rolled on top of him, said Nelson. The firefighter was medevac’d to the hospital and treated for a collapsed lung, broken ribs and other minor injuries. Another firefighter sustained a laceration from a firefighting tool.

Although fire crews travel on steep and remote roads to reach fires, the biggest risks come from driving on regular highways, where fire crews transport oversized equipment in heavier-than-normal traffic, said Nelson.

Firefighters often work at night to take advantage of cooler temperatures and higher humidity, but working in the dark with a headlamp presents its own risks, said Nelson. Fire crews also have more interactions with wildlife at night. Crews on the Crescent Mountain and McLeod fires have encountered bears and cougars, but the animals typically run off when they see firefighters, said Nelson.

Cancer registry

Researchers hope the new cancer registry will provide additional data about whether exposure to chemicals or other substances during firefighting contributes to an increased risk of cancer.

Studies suggest that firefighters — both wildland and structure firefighters — may have higher rates of some types of cancer. Anecdotal information indicates they may have higher rates of disease in general.

Sen. Maria Cantwell (D-Washington) recently secured $1 million to begin development of the cancer database. The information will supplement an existing database of firefighter injuries, although the focus of that registry is primarily on municipal firefighters,

NIOSH has been gathering data since 2010 to better understand the potential link between firefighting and cancer. The NIOSH findings, from studies of firefighters in three large urban fire departments, suggest that firefighters may be at higher risk of digestive, oral, respiratory and urinary-system cancers.

Many cancers in structure firefighters could be connected with exposure to substances like asbestos, according to NIOSH. Whether these findings also apply to wildland firefighters is one thing researchers hope to learn from the registry, which will collect data about a larger and more diverse pool of firefighters.

While the incidence of cancer in firefighters may be higher than in the general population, their overall mortality rate — from all causes of death — was not elevated, said NIOSH.

Other risks

Firefighting can affect the reproductive system of both women and men. Exposure to toxic chemicals and heat can pose a threat to an individual’s ability to conceive or bear a healthy child, according to researchers.

While there has been research linking cigarette smoke to low birth weights, there is little data about the risks of toxic chemicals in wildland-fire smoke. In fact, researchers are more concerned about exposure to extreme heat, which has been linked to male infertility and to a higher chance of offspring with birth defects for women.

Firefighters are at risk for a serious and sometimes fatal condition called rhabdomyolysis (often called rhabdo), in which muscle tissue breaks down from heat exposure and prolonged exertion.