While many studies show some short-term effects on various physical functions, we haven’t seen evidence of long-term problems. Those who fear e-cigarettes say it’s just a matter of time before vapor starts causing real health problems, but most objective investigators aren’t convinced.
Toxins, carcinogens, chemicals
There are scary sounding chemicals in e-cig vapor, but they’re in tiny concentrations, far smaller than in tobacco smoke. Plus, you breathe and eat chemicals every day, but most of them don’t affect you.
The Royal College of Physicians agreed. In its comprehensive review of e-cigarette science, the College concluded, “In normal conditions of use, toxin levels in inhaled e-cigarette vapour are probably well below prescribed threshold limit values for occupational exposure, in which case significant long-term harm is unlikely.”
Coffee contains 22 known carcinogens and an addictive stimulant, but most people are quick to accept that the health risks it poses are minimal, because the levels of the toxicants are very low, and concern over a mild stimulant like caffeine would be wasted effort. Lucky for coffee, consuming it doesn’t require doing something that looks like smoking.
In a study at Portland State University about two years ago, a group of researchers found that if you turn up the power on a vape to a level no human could tolerate, an inexpensive clearomizer would produce high levels of formaldehyde. Thinking they had a major scoop, they rushed the information into a letter to the New England Journal of Medicine, which published it. The result? Headlines around the world like “E-cigarette vapor filled with cancer-causing chemicals, researchers say,” and “E-cigarettes can produce more formaldehyde than regular cigarettes, study says.”
Of course, the truth is that if you fire a wick and coil with insufficient liquid at a high temperature, you’ll get a dry hit (sometimes called a dry puff). It is a repulsive experience. And measuring the toxins that result are pointless, since no one could or would keep inhaling when it happens. Responses came quickly — from Dr. Konstantinos Farsalinos and Clive Bates, among others — but no amount of explanation could put the genie back in the bottle.
Because these scientists did an experiment with no knowledge or understanding of the thing they were testing, they got results that bear no resemblance to what an actual vaper would experience. In their rush to grab headlines, they probably caused thousands of smokers to stick with cigarettes rather than give vaping a chance. And that probably makes the Portland State researchers — R. Paul Jensen, Wentai Luo, James F. Pankow, Robert M. Strongin, and David H. Peyton — greater dangers to public health than formaldehyde in vapor ever could be.
Popcorn lung: diacetyl and acetyl propionyl
Popcorn lung! You’ve seen the headlines, and you’ve probably heard of diacetyl, the artificial flavoring that probably caused severe lung damage to several workers at a Missouri microwave popcorn factory in the 1990’s. The scientific name for the condition is even scarier: bronchiolitis obliterans. It causes horrific and irreversible harm that can only be addressed with a lung transplant.
Cigarettes contain diacetyl too, and at much higher levels than e-liquid.
Diacetyl is one of a group of chemicals used in flavorings called diketones. The other common diketone in flavorings is acetyl propionyl. One is probably not safer than the other. Both can cause serious damage if inhaled in large enough quantities. The question is, how much is too much? No one knows for sure. The popcorn workers were inhaling the flavoring in powdered form and in massive quantities. Vapers would be getting far lower doses, and inhaling the chemical dissolved in liquid.
Cigarettes contain diacetyl too, and at much higher levels than e-liquid. So this is another of many risks that vaping detractors like to hype while ignoring the fact that most vapers are using the product to avoid smoking. There has been a lot written on diacetyl and popcorn lung. We’ve done a much deeper dive into the topic, see the link above if you want to know more.
Depending on who you ask, the biggest vaping health risk is the e-liquid we vape containing chemical flavorings. While diacetyl is the most famous, there are lots of other flavorings that may be risks for inhaling. You’ll often see vapers comparing the 5,000 (or 7,000 or 10,000 — the number jumps all over) chemicals in cigarette smoke to the “four ingredients on e-liquid.” That’s a silly comparison.
If there are four ingredients in e-liquid, then there are just two in a cigarette: tobacco and paper. But that’s not how it works. In addition to the obvious chemical ingredients like propylene glycol (PG), vegetable glycerine (VG), and nicotine, e-liquid usually contains food flavorings. And each flavoring itself can contain lots of chemicals. Food flavorings are considered “generally recognized as safe” (GRAS) by the FDA, but that’s for ingestion, not for inhalation. There is little published research on inhaling food flavorings, since the concept began with e-cigarettes just a few years ago.
We just don’t know which, if any, flavorings may be risky to inhale on a long-term basis. In the short term, the downsides include upper airway irritation and scratchy or sore throats in some people. Vapers have debated this topic almost since vaping started, and fingers are often pointed at cinnemaldehyde (cinnamon) and vanillin (vanilla), along with diacetyl and acetyl propionyl, as potential dangers. Again, if you’re smoking cigarettes now, switching to any vapor product is likely to be far safer. If you’re not a smoker, and you’re smart enough to google “the dangers of vaping,” you’re probably not going to start vaping regularly anyway.
This is a potential danger promoted almost exclusively by one man, University of California-San Francisco cardiology professor Stanton Glantz, a 40-year veteran of the crusade against smoking (and now against vaping too). Prof. Glantz has a thing for ultrafine particles in e-cig vapor, and you can measure his influence by watching anti-vaping propaganda campaigns to see if they include particles as a danger.
The bottom line, as summarized neatly by Clive Bates and Carl Phillips, is that comparing the solid particles in combustion products like cigarette smoke and automobile exhaust to the droplets of e-cig vapor (or aerosol, to use its technical name) cannot be done. They don’t behave the same way or contain the same substances. Prof. Glantz almost certainly understands that too.
In 2014, the press in Spain reported that a man contracted lipoid pneumonia from inhaling e-cigarette vapor. Doctors said it was caused by the vegetable glycerine (VG) in the e-liquid. However, that isn’t possible because, as Dr. Farsalinos explained, VG isn’t a lipid (a fat, like actual oils).
Both common vaping glycols are actually from the alcohol family, and are sometimes called sugar alcohols. Despite the name, they don’t cause intoxication, and they don’t contain actual sugar. Neither substance is toxic to ingest or, as far as we know, to inhale. You may see references to e-liquid “containing antifreeze.” That is a ridiculous smear that may come from the fact that in early FDA testing of imported cigalikes, one had a miniscule amount of ethylene glycol, a mildly toxic cousin of propylene glycol (PG). Ethylene glycol is often used in antifreeze.
But sometimes antifreeze makers substitute PG for ethylene glycol to make a “safe for pets” antifreeze. Both substances prevent the radiator from freezing, but if it leaks or spills PG is not dangerous for cats and dogs to drink. PG and VG are also used in fog machines in clubs and concerts.
As far as long-term daily inhalation of PG and VG go, there just isn’t much information. PG is used in nicotine inhalers (but not, as is often claimed, in asthma inhalers), but those aren’t designed to be inhaled hundreds of times a day. There have been multiple animal studies on inhaled PG, and they didn’t produce any remarkable results. Likewise, studies on people exposed to theatrical fog machines are inconclusive.
The best advice for vapers who are concerned about inhaling a lot of PG or VG is from Dr. Farsalinos. To reduce what miniscule risk there may be, he suggests using a higher nicotine level and vaping less. Of course, that is the exact opposite of current vaping trends.