Feb. 1 (UPI) -- Flavored e-cigarettes contain two chemicals that can impair breathing in smokers, a new study says.
About 90 percent of e-cigarettes contain a flavoring agent called diacetyl and 2,3-pentanedione, both of which cause bronchiolitis obliterans, a debilitating lung disease, according to a study published Friday in Scientific Reports.
"Although chemicals used to flavor e-cigs are frequently used, little has been known about the mechanism of how they impact health. Our new study suggests that these chemicals may be harming cilia--the first line of defense in the lungs--by altering gene expression related to cilia production and function," Quan Lu, associate professor of environmental genetics and pathophysiology at Harvard University and study co-senior author, said in a news release.
Diacetyl is also commonly found in foods like baked goods, butter-flavored microwave popcorn and candy, but are safe in those forms, the researchers say. It's only dangerous when inhaled.
Diacetyl and 2,3-pentanedione were both associated with mutations in gene expression that could damage production and function within the cilia. The cilia help people breathe easily by clearing dirt and mucus away from the airway.
When cilia don't work properly it can lead to diseases like asthma and COPD, the researchers said. That's why the researchers say smoking e-cigarettes, even at low levels, could alter gene expression.
The study's results indicate the latest development in a growing list of concerns that health experts have recently associated to smoking e-cigarettes.
In December, the surgeon general warned people are vaping at epidemic levels.
"E-cigarette users are heating and inhaling flavoring chemicals that were never tested for inhalation safety," Joseph Allen, assistant professor of exposure assessment science at Harvard University and study co-senior author, said. "Although some e-cig manufacturers are stating that they do not use diacetyl or 2,3-pentandione, it begs an important question--what chemicals, then, are they using for flavoring? Further, workers receive warnings about the dangers of inhaling flavoring chemicals. Why aren't e-cig users receiving the same warnings?"