California wildfires could be transforming natural metals into cancer-causing compounds

Wildfires in parts of the U.S. West may be transforming a benign form of chromium into its cancer-causing counterpart — potentially endangering first responders and surrounding communities, a new study has found.

The research, published Tuesday in the journal Nature Communications, identified high levels of the hazardous metal hexavalent chromium, or chromium-6, at specific types of burn sites along California’s North Coast.

Also known as “the Erin Brockovich chemical,” chromium-6 emerged in the public eye in the 1990s after Brockovich — then a legal aid — found that it was contaminating drinking water and sickening residents of Hinkley, Calif.

This toxic compound, which raises cancer risk when inhaled or ingested, was not present at the sites of interest for the study before they burned.

Rather, soils and plants at these locations were rich in naturally-occurring trivalent chromium — chromium-3 — an essential nutrient that helps the human body break down glucose.

While chromium-6 can also exist naturally in the environment, this toxic form of the metal more often contaminates communities via runoff and wastewater from industrial processes.

Wildfire smoke plumes are known to transport dangerous pollutants such as aerosols, gases and fine particulate matter, but the researchers wondered whether the same could be said for heavy metals, and what the risk might be to firefighters and those who reside downwind.

“In the complex mixture of gasses and particles that wildfires spew out as smoke and leave behind as dust, heavy metals such as chromium have largely been overlooked,” senior author Scott Fendorf, a professor at Stanford University’s Doerr School of Sustainability, said in a statement.

Laboratory experiments conducted by Australian researchers in 2019 had already shown that chromium-6 could form rapidly from chromium-3 in surface soils set ablaze.

This transformation occurs through a process known as oxidation — or in this scenario, a reaction between chromium and atmospheric oxygen in which electrons are lost.

Because that process is slow at low temperatures, it “effectively doesn’t happen,” Fendorf, who is also a senior fellow at the Stanford Woods Institute for the Environment, told The Hill.

“But when you start heating the samples up through in this case wildfires, that causes that reaction to occur,” he said. “And so, you’ve transformed from the benign to the really toxic form.”

With that in mind, Fendorf and his colleagues decided to test the theory that wildfires could leave soils contaminated with chromium-6 in their stead.

The scientists focused their attention on California’s North Coast, where they identified four recently burned ecological preserves that contain […]

Full article: thehill.com