Nearly 2,000 unknown chemicals found in vape liquids and e-cig aerosols


A first-of-its-kind study from researchers at Johns Hopkins University has found traces of hundreds of unknown chemicals in electronic cigarette vaping liquid and aerosols. The study details a huge array of unidentified chemicals, plus a handful of known and potentially harmful compounds.

“Existing research that compared e-cigarettes with normal cigarettes found that cigarette contaminants are much lower in e-cigarettes,” explains senior author on the study, Carsten Prasse. “The problem is that e-cigarette aerosols contain other completely uncharacterized chemicals that might have health risks that we don’t yet know about. More and more young people are using these e-cigarettes and they need to know what they’re being exposed to.”

The research is the first to conduct a thorough non-targeted analysis of all potential compounds present in vape liquids and aerosols using liquid chromatography/high-resolution mass spectrometry. Four popular tobacco-flavored vape liquids were tested, alongside testing of aerosols generated by four common electronic cigarette devices (one tank, one disposable, and two pods).

Almost 2,000 different chemical compounds were identified in the study and most of those compounds were unidentified. Six potentially harmful compounds were detected, out of the chemicals the researchers were able to identify. These included a pair of flavorings linked to respiratory irritation, three industrial chemicals, a pesticide, and perhaps most unusual – caffeine.

Mina Tehrani, lead author on the study, says two of the four vape liquids contained caffeine. Flavors such as coffee or chocolate are known to contain traces of caffeine but only tobacco vape liquids were tested so Tehrani was surprised by this finding.

“That might be giving smokers an extra kick that is not disclosed,” says Tehrani. “We wonder if they are adding it intentionally.”

Another unexpected finding in the study was the detection of condensed hydrocarbon-like compounds in the vape aerosols. These compounds are typically produced during combustion, but were still produced during the vaping process.

A similar recent Australian study using gas chromatography/mass spectrometry to analyze the chemical composition of 65 vape liquids found every sample studied contained at least one kind of potentially harmful chemical. These included benzaldehyde, an airway irritant and trans-cinnamaldehyde, an immunosuppressive agent. The Australian research also found traces of nicotine in six of the vape liquids tested, despite them being clearly advertised as nicotine-free.

These studies are certainly not the first to find potentially harmful chemicals in electronic cigarette liquids. But it is important to note these studies are designed to look for any traces of chemicals. They are not investigating whether the chemicals directly cause harm in the context of vaping, or whether they are present in large enough quantities to hypothetically cause harm in the first place.

Instead, Prasse says the research affirms just how little we know about the chemicals being used in electronic cigarettes. While his study makes no comparison between harm caused by vaping and smoking cigarettes, Prasse does stress electronic cigarettes should not be considered a “healthy” alternative to traditional smoking.

“People just need to know that they’re inhaling a very complex mixture of chemicals when they vape. And for a lot of these compounds we have no idea what they actually are,” says Prasse. “I have a problem with how vaping is being marketed as more healthy than smoking cigarettes. In my opinion we are just not at the point when we can really say that.”

The new study was published in the journal Chemical Research in Toxicology.

Source: Johns Hopkins University, 11 October 2021