UC Riverside scientists have discovered that heating the main ingredient in most e-cigarette liquids can lead to the formation of two toxic chemicals that harm human lung cells.
These two substances – methylglyoxal and acetaldehyde – may form when liquids containing propylene glycol are heated.
Using human airway tissue grown in the laboratory, scientists exposed cells to realistic levels of each substance and monitored their response. They found that both substances disrupted basic cell functions, but methylglyoxal caused more damage at much lower concentrations. It interfered with mitochondria, the structures responsible for generating energy within cells, and weakened The actin cytoskeleton, which maintains the shape and strength of cells.
For her part, Prue Talbot, a graduate professor and lead author of the study, said, “These changes are signs of stress and injury, and may lead to long-term health problems if repeated while vaping.”
She added that the substance “acetaldehyde” had received greater attention previously, due to its high levels in e-cigarette vapor, and it is a known component linked to lung diseases, but Talbot stressed that “methylglyoxal” may be more toxic, despite appearing in smaller quantities.
Man Wong, a graduate student and lead author of the study, noted that low-power e-cigarette devices, which are believed to be safer, may produce higher levels of methylglyoxal.
He added: “Since almost all e-cigarettes use propylene glycol, understanding how these byproducts are formed and their effect on cells is crucial to assessing long-term health risks.”
The study also showed that short exposure to these chemicals can alter cellular pathways associated with energy production, DNA repair, and the structural integrity of cells. “Our work helps explain how chemicals associated with vaping contribute to lung injuries, and we hope this research will guide future studies and safety evaluations of e-cigarette products,” Wong said.