UC Riverside study links e-cigarette vapor chemicals to lung cell damage and toxicity.
Scientists at the University of California, Riverside, have uncovered new concerns about vaping after finding that heating common heated e-cigarette liquids can create toxic chemicals that harm lung cells. The discovery adds to a growing body of research showing that vaping may be more dangerous than many users realize, even when using low-powered devices often thought to be safer.
The study focused on propylene glycol, a main ingredient in most vaping fluids that helps produce vapor. When this ingredient was heated, researchers found that it broke down into two chemicals — methylglyoxal and acetaldehyde. Both are known toxins, but their effects in vaping had not been fully studied before.
To understand what happens inside the lungs, the research team grew human airway tissue in the lab and exposed it to small amounts of each compound. They found that both chemicals disrupted normal cell function, but methylglyoxal caused much greater harm even at lower levels. It damaged mitochondria, the parts of the cell responsible for producing energy, and weakened the actin cytoskeleton, the structure that helps cells keep their shape and stay strong.
These disruptions are early warning signs of stress and injury in lung tissue. The researchers believe that repeated exposure over time, such as from frequent vaping, could increase the risk of lasting damage or disease. Prue Talbot, a senior professor who led the study, explained that acetaldehyde has long been recognized as harmful because it is also found in cigarette smoke and has been linked to lung disease. But the findings suggest that methylglyoxal may be even more toxic in some cases.
Man Wong, a graduate student and first author on the paper, pointed out something surprising: smaller or lower-powered e-cigarette devices, often marketed as safer options, might actually produce more methylglyoxal than stronger ones. This happens because of how propylene glycol breaks down under certain heating conditions. That means even those who think they’re choosing a less harmful option could be breathing in more of this damaging compound.
The study showed that exposure to these chemicals, even for short periods, changed how cells produced energy and repaired DNA. It also interfered with processes that keep cells healthy and able to recover from stress. Such effects could help explain why some people who vape experience coughing, chest tightness, or other respiratory issues even when they use nicotine-free or flavored products.
The researchers said that understanding how these byproducts form is essential for measuring the true risks of vaping. Because almost all e-cigarette brands use propylene glycol in their fluids, these reactions could occur across nearly every product on the market.
Talbot and Wong worked with colleagues Teresa Martinez and Nathan Hendricks on the project. Their research was supported by grants from the National Institutes of Health, the U.S. Food and Drug Administration’s Center for Tobacco Products, and the university’s Academic Senate.
The findings contribute to a clearer picture of how vaping affects the lungs. While e-cigarettes were once promoted as a safer alternative to smoking, evidence continues to show that heating their ingredients can produce harmful substances that may cause lasting health problems. The study’s authors hope their work will guide future safety testing and help regulators and the public better understand the hidden risks behind the vapor.
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Toxic compounds from heated e-cigarette fluids can damage lung cells
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