Toxic Salton Sea dust inflames lungs and disrupts gut microbes in mice

What did the mice show?

The study builds on earlier work by Maltz and colleagues showing that the microbial community in our lungs reflects what we encounter in the environment. The new results connect the lungs to the gut.

"The dust closest to the sea caused inflammatory responses in the lung, and since there is a gut-lung axis, it caused opposing effects in the gut microbiome," Maltz said. Dust from near the shore decreased microbial diversity in the mice's guts while increasing it in their lungs, alongside a rise in certain microbes from the sea itself.

Topacio said the findings are distinctive because they position the gut-lung axis — the two-way communication between these organs — as a driver of the body-wide consequences of environmental exposure. "Here, we showed first how much the lung microbiome is impacted by toxic dust exposure, then subsequently, how fecal microbiome diversity is also significantly reflective of systemic dysbiosis," she said. In plain terms: the damage didn't stay in the lungs.

Why doesn't standard asthma treatment work?

The added lung microbes were largely gram-negative bacteria carrying an endotoxin called lipopolysaccharide, or LPS. That toxin provoked a nonallergic asthma in the mice driven by neutrophils, a class of immune cells, rather than the eosinophils seen in allergic responses.

That distinction matters. Neutrophilic asthma can be more severe and responds poorly to common treatments such as corticosteroid inhalers. Maltz says asthma rates in children near the sea are high and fall off with distance from the shore, and the area has high rates of misdiagnosed allergic asthma. The team has submitted a grant proposal to the National Institutes of Environmental Health Sciences, led by Ann Cheney, now a professor at UC Riverside, to study the asthma phenotype in local children.

"This is all happening because this polluted sea is eliciting a different type of nonallergic, neutrophilic asthma," Maltz said.

What happens next?

Because medicine offers little for nonallergic asthma, researchers are working with doctors and community health practitioners on bilingual fact sheets covering lifestyle changes, breathing exercises and air purifiers. They're also collecting household dust; Maltz is testing whether it carries the same LPS found outdoors. Many homes are manufactured structures poorly sealed against dust, and many families are immigrant and migrant farmworkers, some speaking Purépecha or only Spanish.

Complicating matters, the region sits on one of the largest known lithium deposits, earmarked for California's Lithium Valley Vision. "There is potential for mitigation, but instead there is a push for more mining and more environmental disturbance at the sea due to critical minerals," Maltz said, describing a snowball effect as the sea keeps shrinking.

She sees the work as collaborative problem-solving with residents. "I am excited to work with the families to teach them about what is in the dust and translate the science into useful facts and interpretations that they can understand to enact positive change."