Canadians who live near wildfire sites have higher risk of cancer, recent study shows

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Canadians who live in wildfire zones, such as southeastern British Columbia, face a higher risk of getting cancer compared to those who don't, a study from McGill University has found.

In an article published this month in the scientific journal Lancet Planet Health, researchers say they examined around 20 years of health data — from 1996 to 2015 — of over two million people across the country.

They found that people who lived within 50 kilometres of a wildfire in the past 10 years were 10 per cent more likely to develop brain tumours, and five per cent more likely to have lung cancer, compared to people living further away.

The study did not analyze data of people who lived in major cities with a population more than 1.5 million. It also excluded new immigrants and people younger than 25 or older than 90.

Climate change exacerbates wildfires

Scientists have said they expect climate change to exacerbate wildfires and the associated health risks of air and water pollution.

In 2018, for instance, the U.S.'s Centers for Disease Control and Prevention said they discovered that drinking water in Paradise, Calif., was contaminated with benzene, a cancer-causing chemical, after a wildfire in the area that year. 

Because wildfires typically occur in similar regions each year, people who live in nearby communities might inhale or drink carcinogenic wildfire pollutants on a chronic basis, said the researchers at McGill. 

"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 at McGill University and the lead author of the research article, said in a written statement.

When more than 200 wildfires were raging across the B.C. Interior last summer, some scientists recommended wearing an N95 mask to fend off smoke during outdoor activities.

McGill University epidemiology professor Scott Weichenthal, who co-wrote the article, said although masks do a great job of filtering out airborne contaminants, carcinogens could also pollute other things.

"They also can contaminate things like water and soil," he told host Chris Walker on CBC's Daybreak South. "There might be other routes of exposure to harmful environmental chemicals."

Weichenthal says his research team plans to conduct a follow-up study on how chemical mixtures from wildfires vary throughout the fire season.