Toronto, Canada (CTV Network) -- A study out of Montreal's McGill University suggests wildfires may increase a person's risk of developing certain cancers.
The study, published last week in the journal The Lancet Planetary Health, shows those living within 50 kilometers of wildfires over a 10-year period had a 4.9 per cent greater incidence of lung cancer and a 10 per cent higher incidence of brain tumors than those who lived further away.
The research used 20 years of data involving more than two million Canadians, and the study's authors said it is the first to look at how a person's proximity to forest fires may influence their risk of cancer.
"Many of the pollutants emitted by wildfires are known human carcinogens, suggesting that exposure could increase cancer risk in humans," Jill Korsiak, a PhD student who led the analysis, said in a news release on Tuesday.
Since wildfires generally happen in similar regions each year, the researchers say those living in nearby communities may experience chronic exposure to carcinogenic pollutants.
Along with polluting aquatic environments and soil, chemicals such as heavy metals and certain hydrocarbons can remain in the environment for long periods, the researchers said.
They add that wildfires are being increasingly recognized as a global health problem and are expected to become more prevalent, severe and longer lasting due to climate change.
But the researchers stress that more work is needed.
"These findings are relevant on a global scale given the anticipated effects of climate change on wildfire frequency and severity," the authors wrote.
"However, in light of the study limitations, and because this is the first epidemiological study investigating associations between wildfires and cancer risk, we emphasize that a causal effect cannot be ascertained from this single study."
The study used the 1996 Canadian Census Health and Environment Cohort, which tracked incidences of cancer and mortality between 1996 and 2015.
Participants who lived in major Canadian cities or with populations greater than 1.5 million people, recent immigrants and individuals younger than 25 or older than 90 were excluded from the study.
Exposed populations were less likely to live in a census metropolitan area and more likely to live in Western Canada than unexposed individuals.
The study looked for other potential links between wildfire exposure and certain blood cancers such as non-Hodgkin lymphoma, multiple myeloma and leukemia but found no increased incidence.
The researchers also found no clear association between the amount of area burned in a wildfire and incidence of cancer.
They said this may be due to inaccurate estimates of the total area burned in wildfires and factors that could affect the concentration of pollutants in the environment such as vegetation type, fire characteristics and wind patterns.