The ongoing Los Angeles fires have burned more than 16,000 structures, many of them full of synthetic materials that, when burned, release chemicals toxic to both humans and wildlife.
When things like furniture, electronics, flooring, paint, insulation and water pipes burn, they can release a toxic cocktail of chemicals, such as dioxins, polychlorinated biphenyls (PCBs) and asbestos — all known carcinogens. For humans, such chemical exposure can cause “more diabetes, more heart disease, more high blood pressure,” Dr. David Carpenter, a public health physician at the University at Albany, U.S., told Mongabay by phone. “And same thing goes for wildlife.”
Past studies have found that wildlife exposed to human-made chemicals like dioxins and PCBs develop serious health problems.
Lee Kats, a biology professor at Pepperdine University in California, U.S., said the biggest danger for wildlife in an urban fire is being caught in the plume of toxic smoke. “It could potentially be even lethal if they’re actually receiving the plume directly,” Kats told Mongabay by phone.
Kats, who has been studying the effects of fire on wildlife for more than 30 years, said that in 2018 he noticed something unusual: After that year’s Woolsey Fire — also in L.A., which burned 1,600 structures, one-tenth the number that burned this time around — he observed amphibians including newts and California tree frogs that were “emaciated, clearly operating under stress.”
“They’re clearly not being able to maintain weight,” he said. “Often it translates into some wounds, sores. They’re not injuries. Often cataract like cloudiness on the eyes and, frankly, significant mortality. None of those things are necessarily what you would expect just from a wildfire, like off in the woods.”
Wildfires often damage fish and amphibian habitats, Kats added. When forests burn, ash frequently washes into waterways, and without tree roots to keep soil intact, riverbanks easily erode. Consequently, streams become filled with soil and debris, and pools that are normally about 2 meters (6 feet) deep shrink to just centimeters within a few months.
“What we see historically is, oh, gosh, there’s no place for them [fish and amphibians] to lay their eggs. The adults have done their migration to the creek and they kind of throw their hands up like, ‘Where am I supposed to go? There’s no habitat here,’” Kats said.
That reduced habitat for breeding can lead to a drop in population, he added, “but never after a wildfire [do] these animals look sick.”
Kats cautioned that his observations are correlation, not causation. He hasn’t yet formally studied the Woolsey Fire streams or published his observations.
He said the fundamental problem is that with climate change, “frequency of wildfire is increasing. While many of these organisms are adapted to wildfire, they’re not adapted to it if the wildfires are coming through every six or seven years.”
Banner image of wildlife during a fire in Bitterroot National Forest. Image courtesy of John McColgan via the U.S. House Committee on Natural Resources.