Exposure to sweltering air pollution caused by frequent wildfires may put people at a much higher risk of brain tumors and lung cancer, according to a new study published in the journal Planetary Health Lancet. As the climate crisis rapidly escalates, recurring wildfires could become more severe and even last longer.
Researchers have analyzed that forest fires emit pollutants into the air which also end up in water and soil and are also known as ‘human carcinogens’. This includes polycyclic aromatic hydrocarbons, benzene, formaldehyde, phenols and heavy metals. The problem, the researchers noted, is that in North America, wildfires tend to occur in the same areas every year. This puts nearby communities in close contact with carcinogenic pollutants from wildfires for long durations. Especially pollutants like heavy metals and polycyclic aromatic hydrocarbons that seep into soil and water.
In the Lancet study, researchers looked at the long-term impacts of wildfire pollutants on residents who were chronically exposed to them. The team included participants from the Canadian Census Health and Environment Cohort which assessed the cancer outcomes and mortality of 3.6 million people from 1996 to 2015. Participant residential postal codes were available in the data, through to tax records. This allowed researchers to assign wildfire exposures based on people’s zip codes.
They then excluded people under the age of 25, those residing in urban areas with populations over 1.5 million, and people who had recently immigrated to Canada. The analyzes ultimately included more than 2 million people who were followed for a median of 20 years. Of this total, there were approximately 43,000 lung cancer events and 3,700 brain tumor events.
Based on this, the researchers observed that people living within 50 kilometers of wildfires for the past decade reported a 10% and 4.9% higher incidence of brain tumors and lung cancer, respectively, compared to those who do not live near forest fires. areas.
“Environmental concentrations of pollutants emitted from wildfires depend on a range of different factors, including the type of vegetation and the characteristics of the fire,” the researchers wrote. “Because other external factors such as wind patterns play a large role in determining where pollutants move and settle, a larger area burned might not directly translate to greater risk. raised.”
The researchers noted that in addition to high levels of air pollution during wildfires, these extreme weather events can also contaminate water and soil. “Many heavy metals sequestered in soils and vegetation become more mobile and bioavailable after wildfires due to increased soil erosion and ash dispersal,” the researchers added.
This allows heavy metals to deposit in nearby water bodies and also contaminate watersheds. Heavy metals are known to accumulate in fish and other marine animals that humans regularly consume.
“In addition, violations of exposure limits for nitrates, disinfection byproducts, and arsenic in surface and ground waters have been observed in areas affected by wildfires,” the researchers warned. .
For example, in California, drinking water has been severely contaminated with benzene and volatile organic compounds following several wildfires. The researchers pointed out that this was partly due to the melting of the plastic water pipes.