Wildfire exposure linked to increase cancer risk

A new study from McGill University finds people exposed to wildfire smoke have increased risk of developing cancer.

The study tracked over two-million Canadians over the course of 20 years and found those exposed to wildfire smoke were more likely to develop lung cancer and brain tumors.

“Wildfires tend to happen in the same locations each year, but we know very little about the long-term health effects of these events,” said Scott Weichenthal, an associate professor in the Department of Epidemiology, Biostatistics, and Occupational Health at McGill University.

“Our study shows that living in close proximity to wildfires may increase the risk of certain cancers.”

The study found that people living within 50 kilometres of wildfires over the past 10 years had a 10 per cent higher incident of brain tumors and 4.9 per cent higher incidence of lung cancer when compared to people living further away from fires.

The study noted that wildfires typically occur in similar regions each year, resulting in people living in nearby communities possibly being exposed to carcinogenic wildfire pollutants more regularly.

The researchers note that in addition to having an impact on air quality, wildfires can also pollute aquatic, soil and indoor environments. Though some pollutants return to normal concentrations shortly after the fire stops, other chemicals can persist in the environment for longer periods of time, including heavy metals and hydrocarbons.

“Exposure to harmful environmental pollutants might continue beyond the period of active burning through several routes of exposure,” added Weichenthal.

The report said more research is still needed to understand the mixture of environmental pollutants from wildfires, and work is also needed to develop more long-term estimates of the chronic health effects of wildfires.

The McGill study was first published in The Lancet Planetary Health on May 1, 2022.