University of Oregon researchers say wildfires can form cancer-causing compounds in the soils they burn on top of.
Researchers collected soil samples from Eight Dollar Mountain in southwest Oregon, an area rich in a typically benign compound called chromium III.
But when the researchers simulated a high-temperature wildfire, they found the chromium III in the samples could transform into chromium VI, a known carcinogen.
UO Earth Sciences professor Matt Polizzotto, the lead on the project, said the compound could then spread through dust or drinking water.
"The chromium VI that is produced is actually quite mobile," he said. “We found that the concentrations of chromium VI in that water that was leaching from the soils did exceed EPA's safe drinking water limits."
Polizzotto said this could pose a significant risk to communities returning to an area after a wildfire.
According to the study, it could take more than two years before the chromium flushes out, and the water bounces back to the Environmental Protection Agency's standards.
"Then the question is 'where does that chromium VI go?'" said Polizzotto. "And will it be harmful after it leaves the soil?"
According to Polizzotto, the goal of this research is to help develop tools to inform residents about the risks. He said the U.S. Forest Service doesn’t currently look for chromium VI after a wildfire.
He said by overlaying existing soil mapping with fire information, researchers could identify which areas of the state need more testing.
"Each wildfire is going to be variable in its temperatures," said Polizzotto. "Some locations of the within a wildfire can be quite hot, exceeding the temperatures that we're observing are required for converting chromium III. And some areas might be at lower temperatures."
Polizzotto said the research is part of a broader effort to learn about the ecological impacts of wildfires, and how they impact the trace metals commonly found in soils.
"We have a lot of lot to do to identify which are the priority pollutants," he said. “Chromium is certainly one. Nickel might be one. There are others as well, and these are things that we really need to think about going forward."
