Harvard researchers have found that the majority of e-liquids or “e-juice,” — the flavored nicotine liquids used in vaping products — contain diacetyl, a flavoring chemical known to cause debilitating respiratory disease. Many of the vape flavor samples also contained two other chemicals linked to respiratory hazards.
For the study, published online Dec. 8 in Environmental Health Perspectives, researchers at the T.H. Chan School of Public Health tested 51 types of e-juice with a lab-built device that replicated a smoker drawing from a vaping device.
Analyses of the steam collected showed that 47 of the 51 liquids contained one or more of the three toxic chemicals. Diacetyl levels registered above the laboratory limit in 39 of the flavors tested. Acetoin was found in 46 of the flavors tested and 2,3-pentanedione was found in 23. Both Acetoin and 2,3-pentanedione are flavoring compounds recognized by federal health authorities and the Flavor and Extract Manufacturers Association as respiratory hazards in the workplace.
When inhaled, diacetyl promotes the development of bronchiolitis obliterans, a disease known as “popcorn lung” because it was first recognized in the 2000s in workers who inhaled artificial butter flavor in microwave popcorn-producing factories.
“Recognition of the hazards associated with inhaling flavoring chemicals started with ‘Popcorn Lung’ over a decade ago. However, diacetyl and other related flavoring chemicals are used in many other flavors beyond butter-flavored popcorn, including fruit flavors, alcohol flavors, and, we learned in our study, candy flavored [e-juice],” lead author Joseph Allen, assistant professor of exposure assessment science, told the Harvard T.H. Chan School of Public Health.
The school also noted that the nicotine-imbued e-juice is available in flavors such as cotton candy, cupcake, and various fruity flavors that appeal to juveniles.
Despite the findings, little is known about the adverse health effects that vapers may be experiencing, because the devices and the liquids that go in them are not regulated by U.S. Food and Drug Administration (FDA) or any other regulatory authority. Other studies have found the unregulated e-juice also contains formaldehyde and other cancer-causing agents.
More than 7,000 varieties of e-juice flavors are available to U.S. consumers. Although very little is known about the potential health effects vaping e-juice has on users, the popularity of the devices continues to soar. The FDA has proposed a rule that would include vaping products in its regulatory oversight of tobacco and other products containing nicotine.