Within the past six years, Californians have witnessed a troublesome trend in wildfires. Not only are wildfires larger, more frequent and more severe than in prior years, but they’re also increasingly closer to home, crossing into a boundary known as the wildland-urban interface. This boundary, where wilderness meets civilization, is of special interest to research scientists.

“When wildfires cross this kind of invisible boundary, they start to consume the built environment, all the synthetic materials in homes, in cars, in infrastructure, and that changes the emissions landscape,” said Keith Bein, an associate professional researcher with the UC Davis Air Quality Research Center. “That changes what those emissions are composed of, and that changes their impact on toxicity and thus public health.”

UC Davis Comprehensive Cancer Center is funding two pilot studies designed to investigate how wildfire smoke changes the air that Californians breathe and the water they drink. Researchers conducting these studies also are investigating how those changes affect the risk for developing and surviving cancer.

One study is being led by Bein and another by cancer center Associate Director of Population Sciences Shehnaz K. Hussain.

“A lot of material in buildings and structures is going into the atmosphere, the air and the water,” Hussain said. “Some of the elements in wildland-urban interface smoke have not been studied, so we just don’t know what kind of risks for cancer these exposures are going to pose.”

Pilot study #1: Sampling smoke

“One of the ways to study wildfire smoke, especially the health effects, is to go out to the fire and collect samples of air pollution,” Bein said. “So, when a fire pops up, I want to be there to collect samples in close proximity to where those emissions are occurring.”

And for the past handful of years, that’s exactly what Bein has been doing: collecting air samples from wildfire events, including the 2018 Camp Fire and its connected airsheds, or regional air supplies.

“Not only are wildfires happening every summer, but they’re also happening multiple times every summer,” Bein said. “These kinds of repeated exposure scenarios may lead to diseases like cancer.”

In the pilot study, Bein and his colleagues will analyze his wildfire smoke samples to better understand how chemical compounds can trigger cancer development. Specifically, the team is investigating the aryl hydrocarbon receptor (AhR) signaling pathway. Dysfunction of this pathway is one of the main cascading events that leads to the development and progression of lymphoma.

To study this, Bein and his team will use their lab to re-create atmospheric conditions of previous fires, like the Camp Fire. And that’s where Bein’s wildfire smoke samples come into play. He and his colleagues plan to re-aerosolize those samples and expose cellular and animal models to them.

“We’re going to try to mimic what actually happened during the Camp Fire to the people in the Bay Area who got the biggest exposure from that fire,” Bein said. “We’re going to try to re-create that in a mouse model and see if they develop lymphoma.”

The hope is that by re-creating such conditions, the team can determine whether — and how — wildfire smoke leads to lymphoma development at the molecular level.

Pilot study #2: Soot in the soil

In the second pilot study, Hussain will compare air quality data with the California Cancer Registry to study how increased exposure to wildfire smoke affects cancer risk, development and treatment response.

Public air quality monitors, including those that PurpleAir manufactures, allow continuous, real-time monitoring of particulate air pollution. That’s become particularly handy for researchers who wish to conduct longitudinal studies of wildfire smoke risk.

“The idea is to compare people with cancer diagnoses in high wildfire smoke exposure areas to people with cancer diagnoses in low-exposure areas throughout the state and see if there are any differences in how they do,” Hussain said.

She and her colleagues are not only interested in how wildfire smoke affects the air, but they also want to understand how it’s changing California’s groundwater — a much more difficult prospect to document.

“A lot of our region here in Northern California relies on well water, which is not monitored,” Hussain said, noting that particulates from wildfire smoke can penetrate into the soil and seep into groundwater. “There’s no law in California to monitor the composition of heavy metals and other things in well water.”

To rectify this deficiency, Hussain and her team are seeking the public’s assistance in building a groundwater quality database.

“Through a citizen science approach, we want to get people to contribute samples from their wells and get a baseline database,” Hussain said. “In the future, we’re hoping to study wildfire events that are in proximity or upstream of water from those people who are participating in our study, and then study changes that may be occurring in the water due to wildfire events.”

For Hussain, this confluence of rich data and subject-area expertise puts UC Davis at the forefront of research into public health and wildfire smoke.

“Pulling all of these people together is really a no brainer,” Hussain said. “It’s the best example of team science that we can do here at UC Davis.”