Skip to main content

E-cigarette vapor damages the immune system of mice, study finds

E-cigarette vapor damages the immune system of mice, study finds

Share this story

E-cigarettes are being pitched as potentially safer alternatives to traditional tobacco cigarettes, but it's starting to look like they may share some of the same deleterious effects. A new study out of Johns Hopkins University looks at e-cigarettes' effects on mice, and it finds that exposure to their vapor limited of the mice's immune systems and impaired their lungs' ability to fight off viral and bacterial infections. They also found that the vapor contained harmful molecules known as free radicals. The findings were published this week in the journal PLOS One.

"They had more of the virus in their lungs."

The research team exposed the mice to e-cigarette vapor, from the commercial brand Njoy, for two weeks. They attempted to simulate human conditions by measuring the level of nicotine in the mice's blood and matching it with the levels that occur in human smokers. After two weeks of vapor exposure, some mice were exposed to pneumonia, other mice were exposed to the flu, and others were left in fresh air. In both cases with disease exposure, the mice had more trouble fighting back: with pneumonia, the bacteria had an easier time multiplying; with the flu, the mice lost more weight — some even died.

"We saw that they got sicker" after disease exposure, Thomas Sussan, the paper's lead author and an assistant scientist at the Bloomberg School of Public Health, tells The Verge. "They had more of the virus in their lungs, they had more inflammation in their lungs, [and] they were more susceptible to death."

The results suggest something in e-cigarette vapor is inhibiting the immune system within the mice's lungs, the researchers say. Though it's not clear what the cause is, one candidate is the free radicals the researchers detected in the vapor. These molecules are capable of damaging cells and DNA, and they're present in high levels in tobacco smoke. The researchers didn't expect to find them in e-cig vapor because there's no combustion involved, but it appears that just heating up e-cig liquid may be enough. "We were actually surprised that we found quite a bit," Sussan says, "but the levels were considerably lower than what you'd see in cigarette smoke." Far lower — more than 100 times beneath cigarette levels.

But what's impeding the mice's immune systems may be something else entirely. The researchers suggest that the culprit may be related to an additive in e-cig liquid called "propylene glycol," which is also found in fog machines and seems to cause similar lung problems in people who work with them. This study, however, didn't investigate that link. Njoy declined to comment.

"They did work with one particular brand, one particular flavor, one particular level of nicotine," David Peyton, a chemist at Portland State University who was not involved with the study, tells The Verge. "Critically, I would like to see this group follow up with no-nicotine e-cigarette fluid, I would like to see no flavoring at all, I would like to see ... the glycerine alone, and see what effects those have." Though Peyton sees no problems with the study's protocols, its limited scope means that it's a starting point for a lot more research. "As a scientist there are a whole host of question that this study opens up."

The study doesn't say if this is better or worse than cigarette smoke

That type of uncertainty speaks to the general ambiguity in the current debate around e-cigarette safety and regulation. Though it's widely expected that they'll be less harmful than traditional cigarettes, it isn't clear what the risks will be — just because the technology is so new. That's led to much debate over how strictly e-cigarettes should be regulated: loose regulations could mean e-cigs being picked up by non-smokers, exposing them to harm, while strict restrictions could prevent smokers from switching to a less-harmful alternative.

Sussan's team doesn't determine how the effects of e-cigarette vapor compare to the effects of traditional cigarette smoke, but their work does show that similar effects are present. "I can't say that it's better or worse," Sussan says, "but we see that same type of [immune] dysfunction." In particular, the researchers say this may be cause for concern should a smoker who's developed a lung disease attempt to switch to e-cigarettes for safety, as that safety may not actually be there.

Sussan notes that vaping activists often — rightly or otherwise — find fault with research into the effects of e-cigs. He believes that his research group has found a way around this by developing a more-realistic animal model. In fact, Sussan says, their model appears to be the first of its kind, with an animal being exposed to vapor in a way that actually simulates smoking.

"You can't really train mice to vape."

"This type of exposure certainly has precedent in the tobacco research area, so it's got that kind of legitimacy around it," Peyton says. That said, "You can't really train mice to vape," so there are always going to be some differences between this model and a human study. And Peyton thinks that this study may well find itself facing criticism — "and perhaps unfairly so" — simply because it doesn't look at how the effects of e-cigarette vapor compare to the effects of cigarette smoke. "People will push back on it and say, 'you're saying that this is not supporting e-cigarettes as a cessation device,'" he says. "What they've done is compared e-cigarette vaping to non-vaping."

Chances are, we're going to see more use of animal models in the future. The debate around e-cigarettes' health effects isn't going to subside any time soon, and any model that gets results people view as realistic is likely to see some traction. "Clearly this is the first study," Peyton says. "There are a lot more [e-cig] systems that this group can do exactly the same study on but with a whole different series of devices to work on.

Update February 6th, 1:04PM ET: this article has been updated to note that Njoy declined a request to comment.

Today’s Storystream

Feed refreshed 27 minutes ago Striking out

The Verge
Andrew Webster27 minutes ago
Get ready for some Netflix news.

At 1PM ET today Netflix is streaming its second annual Tudum event, where you can expect to hear news about and see trailers from its biggest franchises, including The Witcher and Bridgerton. I’ll be covering the event live alongside my colleague Charles Pulliam-Moore, and you can also watch along at the link below. There will be lots of expected names during the stream, but I have my fingers crossed for a new season of Hemlock Grove.

Andrew Webster1:05 PM UTC
Looking for something to do this weekend?

Why not hang out on the couch playing video games and watching TV. It’s a good time for it, with intriguing recent releases like Return to Monkey Island, Session: Skate Sim, and the Star Wars spinoff Andor. Or you could check out some of the new anime on Netflix, including Thermae Romae Novae (pictured below), which is my personal favorite time-traveling story about bathing.

A screenshot from the Netflix anime Thermae Romae Novae.
Thermae Romae Novae.
Image: Netflix
Jay PetersSep 23
Twitch’s creators SVP is leaving the company.

Constance Knight, Twitch’s senior vice president of global creators, is leaving for a new opportunity, according to Bloomberg’s Cecilia D’Anastasio. Knight shared her departure with staff on the same day Twitch announced impending cuts to how much its biggest streamers will earn from subscriptions.

Tom WarrenSep 23
Has the Windows 11 2022 Update made your gaming PC stutter?

Nvidia GPU owners have been complaining of stuttering and poor frame rates with the latest Windows 11 update, but thankfully there’s a fix. Nvidia has identified an issue with its GeForce Experience overlay and the Windows 11 2022 Update (22H2). A fix is available in beta from Nvidia’s website.

External Link
If you’re using crash detection on the iPhone 14, invest in a really good phone mount.

Motorcycle owner Douglas Sonders has a cautionary tale in Jalopnik today about the iPhone 14’s new crash detection feature. He was riding his LiveWire One motorcycle down the West Side Highway at about 60 mph when he hit a bump, causing his iPhone 14 Pro Max to fly off its handlebar mount. Soon after, his girlfriend and parents received text messages that he had been in a horrible accident, causing several hours of panic. The phone even called the police, all because it fell off the handlebars. All thanks to crash detection.

Riding a motorcycle is very dangerous, and the last thing anyone needs is to think their loved one was in a horrible crash when they weren’t. This is obviously an edge case, but it makes me wonder what other sort of false positives we see as more phones adopt this technology.

External Link
Ford is running out of its own Blue Oval badges.

Running out of semiconductors is one thing, but running out of your own iconic nameplates is just downright brutal. The Wall Street Journal reports badge and nameplate shortages are impacting the automaker's popular F-series pickup lineup, delaying deliveries and causing general chaos.

Some executives are even proposing a 3D printing workaround, but they didn’t feel like the substitutes would clear the bar. All in all, it's been a dreadful summer of supply chain setbacks for Ford, leading the company to reorganize its org chart to bring some sort of relief.

Spain’s Transports Urbans de Sabadell has La Bussí.

Once again, the US has fallen behind in transportation — call it the Bussí gap. A hole in our infrastructure, if you will.

External Link
Jay PetersSep 23
Doing more with less (extravagant holiday parties).

Sundar Pichai addressed employees’ questions about Google’s spending changes at an all-hands this week, according to CNBC.

“Maybe you were planning on hiring six more people but maybe you are going to have to do with four and how are you going to make that happen?” Pichai sent a memo to workers in July about a hiring slowdown.

In the all-hands, Google’s head of finance also asked staff to try not to go “over the top” for holiday parties.

External Link
Insiders made the most money off of Helium’s “People’s Network.”

Remember Helium, which was touted by The New York Times in an article entitled “Maybe There’s a Use for Crypto After All?” Not only was the company misleading people about who used it — Salesforce and Lime weren’t using it, despite what Helium said on its site — Helium disproportionately enriched insiders, Forbes reports.

James VincentSep 23
Nvidia’s latest AI model generates endless 3D models.

Need to fill your video game, VR world, or project render with 3D chaff? Nvidia’s latest AI model could help. Trained on 2D images, it can churn out customizable 3D objects ready to import and tweak.

The model seems rudimentary (the renders aren’t amazing quality and seem limited in their variety), but generative AI models like this are only going to improve, speeding up work for all sorts of creative types.