The debate over the safety of e-cigarettes is shifting to the genetic level. A growing body of research suggests that flavorings and device types may affect how human cells respond.
Researchers at the Keck School of Medicine of the University of Southern California (USC) published their findings in the international journal Frontiers in Oncology after analyzing changes in gene activity among e-cigarette users. The study involved 83 people, including e-cigarette users, conventional cigarette smokers, and non-smokers.
In the e-cigarette group, thousands of genes involved in cancer, heart disease, and lung disease were found to be either overactivated or reduced in function. The Daily Mail reported on the study on local time June 2.
◆ Flavoring, not frequency, was the key variable
The study focused on what causes these changes. The answer was not how often people use e-cigarettes. The type of flavoring and the device used to inhale it were more decisive.
The differences by flavor were striking. Fruit-flavored products were associated with about 31% of all gene changes. Mixed flavors, which combine two or more flavors, accounted for as much as 64.3%. Dessert-style sweet flavors accounted for just 2.9%, while mint and menthol were only 0.9%.
Device type also mattered. More pronounced changes were observed among users of so-called “mods,” high-powered rechargeable e-cigarettes.
Professor Ahmad Beheshtiania, who led the study, said the key question was whether the biological changes were caused by vaping itself or by product characteristics. The main takeaway from the findings is that flavoring ingredients and device design have a significant impact.
◆ There is no safe cigarette
The analysis was conducted using oral epithelial cells collected from participants and RNA sequencing technology, which reads gene activity all at once.
The gene responses of e-cigarette users were broader than those of conventional cigarette smokers, meaning it is harder to predict their health effects.
The impact was not limited to cancer. Further review also found changes in biological pathways linked to endocrine, digestive, and nervous system diseases. Among them, the association with cancer-related pathways was the strongest.
The researchers drew a careful line, saying the results alone cannot prove that e-cigarettes directly cause cancer or chronic disease. Because the sample was limited and the study was not a long-term follow-up, further verification is needed.
Even so, it is too early to call them safe. Experts note that while e-cigarettes may be less harmful than conventional cigarettes, they are not harmless products. Heating e-liquid can produce potentially harmful substances such as formaldehyde, which may cause cell damage and inflammation.
The research team is continuing follow-up studies to determine which ingredients in the liquid trigger gene changes. The study leaves behind a broader challenge: safety assessments of e-cigarettes must become more precise, down to the ingredient and device level.