Dr. Farsalinos on Vaping: Is It Mostly Harmless?

You probably don’t know his name and may never have read his research, but Dr. Konstantinos Farsalinos is a leading authority on vaping, has been doing research in the field for years, and has co-published over 50 academic, peer-reviewed studies of vaping, some of it looking at possible health issues related to vaping.

This article briefly looks at seven of his papers, which still makes for a pretty lengthy article (3,950 words). If you know people who want an overview of solid recent research on the subject of vaping, this is a great place to dig deep and learn.

I contacted Dr. Farsalinos by email and asked if he could share a representative sampling of his research, and he responded by choosing six research papers published from 2014 to the present plus one that has been accepted for publication but has not yet been published. These are scholarly, thorough, technical, and often lengthy research papers – in other words, heavy slogging.

The best feature of a good research paper is that it begins with an abstract, which is written with less technical language than the rest of the paper. Reading this section is enough to let you know if you want to dig deeper.

Apologies in advance if this gets a bit technical and very long, but there’s a lot to cover here. I have done my best to make this article accessible to everyone by explaining things in plain English as much as possible.

Safety Evaluation and Risk Assessment

The oldest paper is Safety Evaluation and Risk Assessment of Electronic Cigarettes as Tobacco Cigarette Substitutes: A Systematic Review published in 2014. The key sentence from the abstract:

“Currently available evidence indicates that electronic cigarettes are by far a less harmful alternative to smoking and significant health benefits are expected in smokers who switch from tobacco to electronic cigarettes.”

A systematic review is an overview of research in a given area. This paper began with an online search based on certain keywords that identified 354 studies of interest. After removing duplicates and research that didn’t cover safety and risk factors, this was narrowed down to 41 papers. This raised the number of studies being reviewed to 97 published research papers and presentations on health issues related to e-cigarettes.

Dr. Farsalinos and his team specifically wanted to know if e-cigarettes are a safer alternative source of nicotine compared to tobacco cigarettes. One of the earliest observations is that e-cigarettes have been undergoing constant innovation since they were first developed in 2003, so it is important to know if the research uses current, relatively new, or outdated equipment. For instance, the move from silica wicking to cotton makes a difference in the vapor produced, and this is just one of many factors.

Besides the age of the gear being tested, there has been little consistency in how vaping is measured. How long is a puff? How much time is there between puffs? What temperature is being used? And how is the vapor content analyzed and reported?

Nicotine Is Not a Health Problem

The key concept is that “nicotine does not contribute to smoking-related diseases.” Cancer, COPD, and other smoking-related diseases are due to inhaling the smoke of burning tobacco, which has thousands of ingredients including many known to be toxic and/or carcinogenic.

However, “nicotine intake has been demonized” due to its association with smoking and smoking-related diseases, and this attitude colors the public’s response to vaping. Nicotine is addictive, and smokers are already addicted, so the question is whether e-cigarettes are a “cleaner” form of nicotine delivery that helps users reduce their risk of developing smoking-related diseases.

Vaping Is Less Efficient than Smoking

In terms of nicotine delivery, “there is evidence suggesting that nicotine cannot be delivered as fast and effectively from ECs [electronic cigarettes] compared to tobacco cigarettes.” However, and this is beyond the scope of this research paper, vaping delivers nicotine more quickly than a nicotine patch or nicotine gum.

Vaping Is Less Harmful than Smoking

Based on chemical analysis, electronic cigarettes “are far less harmful compared with tobacco cigarettes.” Compared to vaping, cigarettes produce 10 to over 1000 times the level of dangerous chemicals associated with e-cigarettes, each covered in detail in this paper.

In light of this, one research paper “concluded that there was no evidence that vaping produced inhalable exposure to contaminants of aerosol that would warrant health concerns.”

‘Relatively Safe’

Propylene glycol is one of the two main ingredients in e-liquid and has been studied in primates, rats, and dogs, where postmortem examination “found no evidence of toxicity on any organ (including the lungs)”. In fact, “findings from surveys and follow-up studies of vapers have shown that [electronic cigarette] use is relatively safe.”

The only symptoms associated with using e-cigarettes are mild, including mouth and throat irritation and dry cough. In most cases where these occur, they tend to decline over time.

Not only is vaping relatively safe in comparison to smoking tobacco, there are reports of “clinically significant progressive health improvements already by week two of continuous use of” e-cigarettes instead of tobacco cigarettes, with “no serious adverse events” reported.

Second-Hand Vaping

People who fear the risks involved in vaping, which we now know pale in the face of the risks inherent in smoking, also raised the question about “second-hand” vaping. Because e-cigarettes only produce vapor when the user inhales, and because the level of potentially risky ingredients is minimal, the level of these ingredients in the air after exhalation is at an extremely low level, far lower than what is produced by a single burning cigarette. One paper  in this study concludes that “the risk for bystanders would be literally nonexistent.”

And if not literally nonexistent, “the effects of [electronic cigarette] use on bystanders are minimal compared with conventional cigarettes.”

Is Vaping a Gateway to Smoking?

Based on most studies, vaping seems to serve as a gateway from smoking tobacco, but some are worried that it might also serve as a gateway to smoking tobacco. Studies of adolescent e-cigarette users in several surveys found that most teens who vaped were already smokers and thus already hooked on tobacco.


The research survey concludes that “evidence indicates that [electronic cigarette] use is by far a less harmful alternative to smoking.” The researchers also speak to the restrictive regulation of e-cigarettes:

“In particular, current data on safety evaluation and risk assessment of ECs is sufficient enough to avert restrictive regulatory measures as a consequence of an irrational application of the precautionary principle.”

In other words, “better safe than sorry” doesn’t apply when comparing vaping to smoking tobacco. The researchers conclude that e-cigarettes “represent a historical opportunity to save millions of lives and significantly reduce the burden of smoking-related diseases worldwide.”

Can E-Cigarettes Be Considered Medicine?

This is a relatively short report – just 4-1/2 two-column pages (excluding sources and footnotes) vs. 15 pages for the above paper. The researchers conclude that vaping is not a medication because it does not treat a disease but instead addresses addictive behavior. Further, there are no long term beneficial outcomes from vaping, which is what you would expect from medication. Further, in the few court cases that have attempted to have e-cigarettes classified as medicine, the courts have ruled against it.

Critiquing the US Surgeon General’s Report

Dr. Farsalinos is a researcher committed to discovering the facts and pointing out when so-called “facts” are speculation. There’s a lot of that going around regarding vaping, and it even shows up in the December 2016 report by the US Surgeon General on e-cigarette among youths and young adults.

Just the Facts

In A Critique of the US Surgeon General’s Conclusions Regarding E-cigarette Use Among Youth and Young Adults in the United States of America,  Riccardo Polosa, Christopher Russell, Joel Nitzkin, and Konstantinos Farsalinos debunk many of the claims made by the Surgeon General, undermining the claim that vaping is an emerging public health concern among youth and young adults.

The first claim they examine is that “exposure to nicotine and other chemicals through e-cigarettes pose serious health risks to young people” and the number of young vapers is growing rapidly, making this “a major public health concern.” In reality, the majority of youth who use e-cigarettes vape nicotine-free.

Further, research has found that e-cigarette use among young people is substantially less than the Surgeon General’s report suggests. This is because the surveyed youth are asked if they have ever tried vaping – even a single time puts them in the e-cigarette user category. The Surgeon General should be more interested in how many vape regularly, not the number who have tried it once, and also how often they vape and whether they vape with e-cigarettes containing nicotine. Without that data, there is no evidence that exposure to nicotine through vaping is any kind of health concern.

As far as the numbers growing rapidly, that’s always the case with something new. You start out with nobody vaping, a few vaping, a few more vaping, and so on. Because it is a new phenomenon, it can only grow rapidly from zero to whatever number of users exist.

Few Vape Regularly

The reports that the Surgeon General used do contain information of frequent e-cigarette use in this population, which finds that the number of those who have vaped once in the past 30 days is much lower than the number who have ever vaped. Among middle school students, 13.5% are among the “ever used” population, but only 5.3% have vaped in the past 30 days and just 0.6% have vaped on at least 20 of the past 30 days. Among high schoolers, the numbers are 37.7% “ever used”, 16.0% within 30 days, and 2.5% on 20 of the past 30 days.

Of course putting the focus on the bigger numbers creates a greater sense of urgency and makes the issue seem more like a major health concern than looking at the number of middle school and high school students who vape regularly.

Further, the vaping rate among those who have never smoked was extremely low. Less than 2% fall into this category, while about 15% of smokers had tried vaping. Although some who have never smoked are experimenting with vaping, it’s a very small number.

Most Who Vape Don’t Use Nicotine

Another significant factor is that data points to the majority of US youth who use or have tried vaping have used e-cigarettes with no nicotine. Between 50% and 70% have never tried vaping with nicotine, which is the focus of the Surgeon General’s panic.

While it could potentially happen that youth who vape with nicotine but have never smoked would take up tobacco cigarettes to get a stronger nicotine hit, there doesn’t appear to be any evidence that this is actually happening in significant numbers. The report states, “There was no evidence that adolescents . . . were smoking cigarettes regularly as a follow-up.”

The Danger of Restricting Vaping

Perhaps the most interesting revelation in this paper is the report that two separate studies have found that imposing age restrictions on vaping has resulted in a higher smoking rate among adolescents than in areas without the restrictions. This points to vaping actually having a prevention role toward taking up smoking cigarettes. In fact, the rising rate of vaping among youth coincides with “the sharpest decline in youth smoking rates in many decades.”

I’d say, “Stick than in your pipe and smoke it,” but that seems totally inappropriate for the subject matter. If the low number of youth who are vaping are avoiding nicotine and cigarettes, it sounds like we have a win-win situation that the Surgeon General should be celebrating. Instead we get a report filled with panic.


One of the most ludicrous things to happen to vaping is calling certain flavors “kid friendly” – as though adults shouldn’t be attracted to the flavors they enjoyed in their youth. As this report says, “It should be expected that good flavors will attract consumers of all ages.”

The ban on certain flavors, let alone any flavors (which has happened in some markets), should be balanced against the benefits of smokers who turn to vaping. Instead of worrying about youth wanting to vape “kid friendly” flavors, which they would do nicotine-free for the most part, the focus should be on the health benefits of vaping vs. smoking tobacco.

Health Effects

And this is where the Surgeon General’s house of cards comes tumbling down:

“The Surgeon General’s document is clear that there are no existing youth-related health outcomes of exposure to nicotine in e-cigarette aerosol emissions…”

In the end, public health policy should target real public health issues, not imaginary ones. As the above quote indicates, there is no evidence of youth-related health outcomes due to vaping.

Aldehyde Levels in E-cigarette Aerosol

This is one very technical paper that was published in Food and Chemical Toxicology. Aldehydes are chemicals such as formaldehyde, acetaldehyde, and acrolein, which can be produced when heating mixtures of propylene glycol and glycerol, the two primary ingredients in e-liquid. These aldedhydes are produced in high quantities by burning tobacco, and e-cigarettes have much lower levels of these.

However, a 2015 study reported that electronic cigarettes can produced higher levels of formaldehyde than tobacco cigarettes, which generated a lot of interest. Farsalinos et al decided to see if the data from that report could be reproduced.

The original study used an older style “top-coil” atomizer with silica wicks at higher than normal power levels, which would lead to dry puffs, and therefore is not the kind of experience a vaper would put up with. Further, the atomizer used was already prone to dry puffs even at low power levels. This was not a realistic trial.

The authors of this paper were unable to duplicate the high formaldehyde levels in the original report despite using the same atomizer and e-liquid. One key principle of science is that results must be reproducible; if not, it’s bad science. In fact, Farsalinos et al found the level of formaldehyde produced by the same device and liquid was less than 10% of the reported numbers.

Testing the same e-liquid in a modern device dropped those numbers below the 5% mark, and tests with unflavored liquid produced even lower numbers.

Carbonyl Emissions from E-Cigarettes

Carbonyls are a class of organic chemical in which carbon and oxygen share a double-bond. Aldehydes, discussed in the first paper discussed here, are one type of carbonyl, along with ketones, amides, and others. Carbonyl produced by burning tobacco is a substantial health risk, so it’s important to know how carbonyl emissions from e-cigarettes compare with tobacco so we can assess risk.

Tobacco is addictive primarily due to the nicotine it contains, and one method of harm reduction has been snus, a moist powder tobacco product placed behind the upper lip. Snus is very popular in Sweden, with the result that the level of smoking-related mortality in Sweden is the lowest in Europe.

Electronic cigarettes are a tobacco-free alternative to tobacco cigarettes that are considered to provide harm reduction relative to smoking. Although there is no burning tobacco in e-cigs, it is important to know if they produce carbonyls and at what level. This paper examines 32 published studies on the topic.

There were many different methodologies used, which points to the need to establish consistent research standards that comport to real world use of e-cigarettes so studies can be more readily compared with each other. In general, these studies found a significantly lower level of carbonyls present in vapor vs. tobacco smoke.

One thing that the researchers point out is that “a standardized puff duration is not appropriate for testing all available e-cigarette products” because some devices produce vapor at higher volume than others.

Are E-cigarettes a New Health Hazard?

Vaping is one of the most controversial publish health issues of our day. How effective is it in helping smokers quit tobacco? And is there any health risk associated with e-cigarettes?

There is no debate over one thing, though: E-cigarettes are far less dangerous than tobacco cigarettes. That’s the whole point of harm reduction, but then comes the next question: What are the risks, if any,  involved with vaping?

Almost all of the dangers from tobacco cigarettes are due to burning tobacco. Smokeless tobacco products are one harm-reduction option, and electronic cigarettes are another. As the paper states, “The intended role (from a public health perspective) of e-cigarettes is to be used as smoking substitutes.” Unlike nicotine gum, a nicotine patch, or smokeless tobacco, vaping has many aspects that mimic smoking, which is why it has become the most popular tool smokers use to cut back and give up tobacco cigarettes.

One potential risk of vaping is that a small number adolescents are taking it up, and there are worries that it could become a gateway to smoking cigarettes later in life. That would be a horrible outcome. While a small percentage of youths who vape do take up smoking, most youths who vape use nicotine-free flavors, which would not set them up to take up smoking as a stronger source of nicotine. Other adolescents take up vaping as a way to get the tobacco “monkey” off their back. Further research must be done, but overall the incidence of vaping leading to smoking seems to be very low.

The Ingredients in E-juice

The biggest factor that makes cigarettes a danger comes from burning tobacco, which contains thousands of chemicals. By contrast, e-liquids generally have four components.

  • Propylene glycol (PG) was discovered in 1858, and the FDA recognized it as safe for use in food products in 1982.
  • Glycerol (VG) was discovered in 1783 and was approved for use in food products in 1959.
  • Nicotine is addictive but is not considered dangerous except in the highest doses, far higher than you would ever find in tobacco or e-juice.
  • For the most part, flavorings used in manufacturing e-liquid are ones used in food products.

The issue is that while three of these ingredients have be approved for use in food products, the long-term impact of inhaling these substances is unknown. Some would use this uncertainty to raise fear and ban vaping; others would use this uncertainty to support vaping until such time as any of these ingredients can be shown to create harm when inhaled, which may take decades of research to establish.

Inconsistent Research

Vaping research is still in its infancy, and those studying e-cigarettes have done so in dozens of different ways. Some use outdated devices. Some generate dry puffs. Some run the vaporizer at an unrealistic voltage. Some use long puffs while others use shorter puffs. Some have a long time between puss and others a short time. And so on.

Not only that, but the methods used to collect the vapor, measure the vapor, and report their findings are also not standardized. Some look at the volume of the vapor cloud. Some look at the amount of liquid used.  All of this makes it very difficult to compare research results.

Without consistent standards, it is impossible to know what real risks, if any, are related to vaping, and long-term health studies will have to wait until there are enough long-term vapers to study. And even then, since most are former smokers, the question remains whether health issues are due to years of smoking or years of vaping.

Good News

Researchers have discovered that giving up tobacco cigarettes in favor of vaping can have health impacts in some areas as soon as two weeks after making the switch. It appears that the benefits of quitting smoking are the same whether one quits “cold turkey” or uses vaping to cut out tobacco use.

There is no way of knowing what risks may be entailed from vaping, and it is unlikely that vaping is absolutely safe, but it appears to be relatively safe in and of itself – let alone being generally found to be 95% less hazardous than smoking (Public Health England).

Population studies have found that vaping is very popular as a smoking cessation tool with a much higher percentage of smokers kicking the tobacco habit by vaping than by using nicotine gum or patches, which have about a 7% success rate after one year.


Toward the end of this research paper, the authors state:

“…continuous monitoring is needed and it remains to be seen whether e-cigarettes represent a source of harm. At the same time, however, the possibility that e-cigarettes might have a primary preventive role, promoting a decline in tobacco cigarette use, should also be considered and research shold also focus on this issue.”

Do Flavorings Contribute to Aldehyde Emissions?

The last paper was an attempt to replicate a study that seemed to find uncharacteristically high levels of formaldehyde, acetaldehyde, and acrolein, especially in flavored e-liquid. These compounds are generated as thermal degradation products, and in attempting to replicate the previous research using the same flavors and device, the issue of dry puffs was a factor. In other words, the original research was not a real world situation; in the real world, vapers do not continue to inhale dry puffs because of their unpleasant flavor.

The original study used a Kangertech eVOD Glass bottom dual-coil atomizer with 1.5 Ohm resistance. This is an older variable-voltge model that uses a silica wick and is considered outdated, but to replicate results, you have to replicate the original setup. Voltage was set at 4.0 V (10.7 W) and testing confirmed that this did not result in dry puffs.

The new research also tested similar flavors using a newer generation atomizer using the same standards as the initial comparison test.

Much Lower Adlehyde Emissions

By not overheating the liquid and thus avoiding dry puffs, the emission levels of aldehydes were far lower than in the original research, and there was minimal difference between the flavored and unflavored e-liquid except for a coffee-flavored liquid. The level of aldehydes measured using the same atomizer and flavored e-juice as the original study was “substantially lower” when the equipment was set up so it would not generate dry puffs. Formaldehyde levels were over 100-fold lower, acetaldehyed levels over 120 -fold lower, and acrolein 9-fold to 30-fold lower than reported in the original research.

Using a different brand of e-liquid, one readily available in Greece where the research was done, and a newer atomizer, even lower levels of aldehydes were measured. Formaldehyde levels were over 650-fold lower, acetaldehyde 350- to 673-fold lower, and acrolein 139- to 292-fold lower.

How Dangerous Are These Levels?

The next thing the research team did was compare the levels of aldehydes generated to commonly measured indoor levels of these chemicals. Spending 24 hours indoors typically results in exposure to 1,000 µg of formaldehyde, and the highest level e-cigarette (at 5 g/day) produced 311 µg. For acetaldehyde, commonly measured indoor levels are 200-400 µg per day vs. 130 µg for the flavor with the highest level of acetaldehyde. And for acrolein, a typical workplace exposure would be 1,685 µg over an 8-hour shift. By comparison, the e-liquid with the highest measured level of acrolein produce 97 µg.

Overall, the exposure level for these three aldehydes received from vaping is much lower than what one would receive spending a day at home or an 8-hour shift in the workplace.


In The Hitchhiker’s Guide to the Galaxy, the original entry for Earth was a single word: harmless. The updated version of the book doubled the size of that entry to “mostly harmless” – which seems to be what researchers are finding.

Not only is vaping substantially less dangerous than smoking tobacco, when compared to typical everyday exposure at home or in the workplace, vaping appears to fall well within the “safe” guidelines and typical levels for formaldehyde, acetaldehyde, and acrolein.

There is still a lot more research to be done regarding potential health issues related to vaping, and while researchers aren’t yet ready to proclaim vaping “mostly harmless”, that looks like a distinct possibility.

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