New Atlas: Wildfire exposure may increase cancer risk, study says

In a first-of-its-kind study examining the relationship between certain cancers and living near wildfires, researchers at McGill University found higher rates of brain and lung cancer in people living within 50 kilometers (31 miles) of wildfires that occurred in the past 10 years, New Atlas reported.

The acute health effects of exposure to wildfires are well known. Air quality has been reported to drop dramatically during wildfires, and higher rates of asthma and cardiovascular disease have been reported. Several adverse pregnancy outcomes are also commonly seen following a large wildfire.

But little is known about the long-term health effects of exposure to these events. The new study fills that knowledge gap by looking at health data from about 2 million people in Canada over a 20-year period.

The study looked at people living within 20 kilometers (12 miles) and 50 kilometers of wildfires, then looked at the incidence of certain cancers over the next 10 years. Compared with people who were not exposed to wildfires, those living within 50 kilometers of wildfires had a 4.9% higher incidence of lung cancer and a 10% higher incidence of brain tumors. These higher cancer rates were similar in both the 20-kilometer radius and the 50-kilometer radius.

"Wildfires tend to occur in the same locations each year, but we know very little about the long-term health effects of these events," said Scott Weichenthal, one of the authors of the new study. "Our research suggests that living near wildfire sites may increase the risk of certain cancers."

The researchers are careful to emphasize that the findings are observational and do not point to a specific cause and effect. Because this is the first study to investigate a potential long-term link between wildfire exposure and cancer risk, more work needs to be done to understand what exactly is driving this association.

Research suggests that wildfires may increase cancer risk in people around them in a variety of ways, beyond exposure to smoke in the days and weeks after a fire. For example, contamination of soil and water has been found in the months and years following a wildfire. This contamination may include heavy metals and other volatile organic compounds.

"Additionally, there is concern that wildfire-derived contaminants may persist in indoor environments for extended periods of time, but few studies have examined this question," the researchers noted in the new study. "One study reported detectable concentrations of char in wipe samples collected from households 3–8 months after a major wildfire event in New Mexico, USA."

The study also has many limitations that need further research to unravel. For example, the study found that the increased cancer risk was similar in people with low and high wildfire exposure.

The characteristics of different wildfire exposures will need to be clarified in further studies, the researchers suggest. Perhaps some wildfires expose populations to more dangerous pollutants. And other questions remain unanswered, such as what are the health effects of a large, single wildfire compared with a population exposed to several smaller wildfires over several years?

Still, the findings are novel, and given that climate change is leading to an increase in wildfire rates around the world, the researchers note that understanding the long-term health effects of these events has a global urgency.

“…Given study limitations and because this is the first epidemiologic study to investigate the relationship between wildfires and cancer risk, we emphasize that causality cannot be determined from this single study,” the researchers reiterated in their conclusion to the study. “Further work is needed to refine exposure metrics used to estimate chronic health effects of wildfires, as well as to replicate across different geographic locations and populations.”

The new study was published in The Lancet Planetary Health.

From cnBeta.COM