Thousands of unknown chemicals and substances found in electronic cigarettes



Vaping aerosols contain thousands of chemicals and unknown substances undisclosed by manufacturers, including industrial chemicals and caffeine, researchers at Johns Hopkins University have found.

The study is the first to apply an advanced fingerprinting technique used to identify chemicals in food and wastewater to vaping liquids and aerosols. The results, which have just been published in the journal Chemical research in toxicology, suggest that vapers are using a product whose risks have not yet been fully determined and could be exposed to chemicals with adverse health effects.

Existing research comparing electronic cigarettes to normal cigarettes has found that cigarette contaminants are much lower in electronic cigarettes. The problem is, e-cigarette aerosols contain other completely uncharacterized chemicals that could pose 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 are exposed to. “

Carsten Prasse, senior author, assistant professor of environmental health and engineering at Johns Hopkins

Previous studies on electronic cigarettes have specifically looked for evidence of dangerous chemicals found in traditional cigarettes. But here, the researchers performed an untargeted analysis to explore the full spectrum of chemicals in both the vaping liquid and aerosols.

Using a chemical fingerprinting technique based on high resolution liquid chromatography / mass spectrometry, never used on vape samples but previously used to identify organic compounds in wastewater, food and blood, l The team tested four popular products: Mi-Salt, Vuse, Juul and Bleu. While it’s possible to buy vaping products in hundreds of flavors, here for consistency they only tested tobacco flavored liquids.

They found thousands of unknown chemicals in the e-liquid, and the number of compounds dramatically increased in the aerosol. Additionally, they detected hydrocarbon-like compounds, typically associated with combustion, which the manufacturers say does not occur during vaping. In traditional cigarettes, the condensed hydrocarbons generated during combustion are toxic.

“One of the main ways that electronic cigarettes have been marketed is that they operate at temperatures below combustion, which would make them safer than traditional smoking,” said lead author Mina Tehrani, postdoctoral fellow at the Johns Hopkins Bloomberg School of Public Health. “Our study shows that this new fingerprinting approach can be applied to assess whether combustion-like processes are underway.”

The team found nearly 2,000 chemicals, the vast majority of which are not identified. Of those the team was able to identify, six substances were potentially harmful, including three chemicals never before found in e-cigarettes. Tehrani was particularly surprised to find the caffeine stimulating in two of the four products. Caffeine has already been detected in e-cigarettes, but only in caffeine-focused flavors like coffee and chocolate.

“It could give smokers an extra kick that is not disclosed,” she said. “We wonder if they are adding it intentionally.”

Besides caffeine, the team found three industrial chemicals, one pesticide, and two flavorings linked to possible toxic effects and respiratory irritation.

Prasse said he became interested in studying vaping products after his cousin, a former smoker, started vaping, insisting he was healthy. He intends to send this paper to this cousin.

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

Co-author Ana M. Rule, an expert on metal exposure from vaping at the Johns Hopkins Bloomberg School of Public Health, says many young people who vape have never smoked. a risk.

“There are millions of middle and high school students who vape who wouldn’t otherwise think about smoking,” she says. “For them, there is no reduction in risk, only increased risk.”

Authors also include Matthew N. Newmeyer, Johns Hopkins Bloomberg School of Public Health Postdoctoral Fellow.

The work was supported by National Institute of Environmental Health Sciences grants R01ES030025 and T32ES007141, and by the National Center for Advancing Translational Sciences and the NIH Roadmap for Medical Research Grant UL1 TR003098.


Journal reference:

Tehran, MW, et al. (2021) Characterization of the chemical landscape in commercial e-cigarette liquids and aerosols by liquid chromatography – high resolution mass spectrometry. Chemical research in toxicology.



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