March 1, 2024


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New research has found that wildfires can release cancer-causing chemicals from the soil

New research has found that wildfires can release cancer-causing chemicals from the soil

Josh Edelson/AFP/Getty Images/File

A firefighter extinguishes flames as he rushes toward homes during the Creek Fire in the Cascadell Woods area of ​​unincorporated Madera County, California on September 7, 2020.


Scorching heat From forest fires It can turn minerals naturally found in soil into airborne particles that cause cancer, according to a new report.

While a growing body of research has focused on the effects of gases and… Particles carried by forest firesLess attention has been paid to the effect they can have on naturally occurring minerals within soil and plants.

But extreme heat from wildfires can transform one mineral, chromium, from its benign version into toxic airborne particles, putting firefighters and people living nearby at risk, according to the organization. Stady Published in Nature Communications in December.

“In the complex mixture of gases and particles that wildfires release as smoke and leave behind as dust, heavy metals such as chromium have been largely overlooked.” Scott WendorfThe study’s co-author and professor at Stanford’s Doerr School of Sustainability said in a press release.

Chromium is common in soils throughout the western United States, Australia, Brazil, Europe, Indonesia, and South Africa.

Certain natural chemical processes can cause the metal to transform from a benign form, called chromium-3, into a carcinogen called hexavalent chromium, or chromium-6. This toxin – made infamous by the 2000 film “Erin Brockovich” – can cause cancer. Organ damage and other health problems.

Following previous research, from Australia It was published in 2019Finding that extreme wildfire heat could be causing this shift, Stanford University scientists set out to test the theory by collecting chromium-rich soil samples at four ecological reserves in California’s northern Coast Range that were burned by wildfires in 2019 and 2020.

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They tested soil from burned and salvaged areas, separating out the smallest particles most likely to become airborne. In chromium-rich areas where vegetation allowed fires to burn intensely and for a long time, the researchers found that levels of toxic chromium were about seven times higher than in unburned areas.

Even after the fire was fully contained, the study found that communities downwind were still at risk, due to strong winds carrying fine particles of chromium-laden soil.

Much of the health risk usually diminishes after the first heavy rains wash away the minerals, Wendorf said. But it can take weeks or months for rain to fall after a fire, especially as climate change increases the likelihood and frequency of drought.

California, at the time of sampling, had A Historical drought for several years. Without much-needed rainfall to wash away the pollutants, when researchers returned about a year later, they found that toxic chromium was still present in the soil, and continuing to pose health risks to nearby communities.

Tariq Ben Marhania, a climate change epidemiologist at the Scripps Institution of Oceanography, who studies the health effects of wildfire smoke, told CNN that the new findings were “important evidence.”

“This type of interpretation of mineral composition complements what we already know and will certainly help us understand health effects in humans,” said Ben Marahnia, who was not involved in the study.

The research adds to growing evidence of the dangerous effects of wildfire smoke, which also carries fine particulate matter, or PM 2.5, a small but dangerous pollutant. When inhaled, it can travel deep into the lung tissue and can even enter the bloodstream. PM2.5 has been linked to a number of health problems, including asthma, heart disease, chronic bronchitis, and other respiratory diseases.

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“What we see our work really doing is helping amplify knowledge of what kind of toxins can be present in wildfire smoke,” Wendorf told CNN.

Scientists also say other metals such as manganese, nickel and iron nanoparticles could pose similar threats, but more research is needed.

Wildfires serve a vital environmental purpose. They increase soil nutrients and remove decaying matter. Without these fires, overgrown foliage such as grasses and shrubs can set the landscape up for worse.

But as the climate crisis worsens with drought and extreme heat, wildfires are burning longer and expanding larger. a Latest United Nations report He predicted the number of severe wildfires would increase by 30% by 2050, even with more ambitious efforts to cut global-warming pollution.

“The bigger picture is that we know we are going to face more extremes, and in the meantime, we are seeing more frequent fires and more dangerous fires,” Wendorf said. “This is a big and worrying finding because frequent fires mean we are exposed to smoke and dust – which is not a good recipe.”