For the most part, we know exactly what goes into the production of the liquid used in the majority of electronic cigarettes. E-liquid typically consists of four main ingredients: propylene glycol, vegetable glycerin, nicotine and flavoring. What isn’t exactly clear is what constituents make up the vapor e-cigs produce.

Key Points

• Most e-liquids are made with propylene glycol, vegetable glycerine, USP grade nicotine, GRAS flavoring and, in some cases, distilled water.
• A 2012 study published in the scientific journal Indoor Air found e-cigs vapor contains only 6 out of 20 chemicals found in cigarette smoke.
• VOC levels in vapor were far below safety limits and up to 40 times lower than those of tobacco smoke.
• 2^nd hand nicotine inhalation is not a concern as only trace amounts were detected from vapor directly exhaled into a 10L glass chamber.

Chemical reactions produced by heat as well as components of the atomizer will often produce unexpected results in electronic cigarette vapor. That’s not to say the vapor is bad, it just simply has more than the four ingredients, on average, that make up the liquid that produces it.

Electronic Cigarette Ingredients

Fortunately, an increasing amount of evidence has shown the vapor produced by e-cigs to be far safer than cigarette smoke. Before we dive into what actually makes up the contents of electronic cigarette vapor, let’s break down each of the main ingredients used in the manufacturing of e-cig liquid.

Propylene Glycol

Propylene glycol is an organic compound generally recognized as safe (GRAS) by the FDA. It is used as an humectant, solvent, and preservative in food and tobacco products, and is one of the main ingredients in the liquid used in electronic cigarettes.

It is also used in pharmaceutical and personal care products. Propylene glycol is a solvent in many pharmaceuticals that are insoluble in water. While it won’t produce the amount of vapor that vegetable glycerin will, PG provides much of the throat hit in e-cig vapor that many smokers are accustomed to feeling in that of a cigarette.

Vegetable Glycerin

Like propylene glycol, vegetable glycerin is another base ingredient of e-liquids that produces the vapor of an e-cigarette. Also known as vegetable glycerol, VG is a considerably thicker liquid solution than PG and thus produces more vapor, albeit with a weaker throat hit.

Because of this, it will cause gunk to build up in atomizers, reducing their life span. However, it isn’t as allergenic and doesn’t cause irritation as often as propylene glycol does in sensitive users. Most e-cigarette liquids incorporate a combination of both PG and VG to give vapers a good throat hit as well as vapor production.

Nicotine

Contrary to popular misconception, nicotine is NOT the cancer causing agent found in most tobacco products. It is an addictive stimulant similar to caffeine that is produced from tobacco leaves.

Nicotine can then be used in the manufacturing of various pharmaceutical products like gums, patches and lozenges to help smokers wean off cigarettes. In the case of e-cigs, it is extracted into a liquid form, often combined with different mixes of propylene glycol and vegetable glycerin to dilute its strength.

Distilled Water

Sometimes distilled water is used in place of propylene glycol to thin out mixes that only use vegetable glycerin as a diluent. This is done to decrease the viscosity of the mix to ensure it wicks better in some atomizers and doesn’t gunk up as quick as 100% vegetable glycerin would.

Flavoring

• Malic Acid: Malic acid is an organic compound made from living organisms that is used in fruit flavored e-liquids. It’s what gives green apples and grapes their sour, tarty taste and has been approved as a food additive in the USA, EU, Australia and New Zealand. Malic acid is also added to some cola drinks to lower their pH levels.
• Acetylpyrazine: Acetylpyrazine occurs naturally in peanuts, corn and sesame oil. It is another commonly used food flavoring that is often used in tobacco, chocolate and coffee flavored eliquid.
• Vanillin: As one might expect, vanillin is used in most vanilla and other desert flavored e-liquids. It is the primary component of vanilla bean extract. Vanillin may be extracted from vanilla pods or artificially made from lignin.

So What’s In the E-Cig Vapor?

The nitrosamine argument has been hotly contested for a while now. The electronic cigarette industry doesn’t claim e-cigs to be 100 percent healthy, as nothing we eat, drink or breathe is perfectly safe. We do know that the quantities of impurities found in e-juice are far lower and thus exponentially safer than those in tobacco cigarettes. But what is actually in the vapor and how safe is it?

A 2012 study published in the scientific journal Indoor Air compared the vapor of electronic cigarettes to that of conventional cigarette smoke. The German researchers analyzed volatile organic compounds after test subjects either smoked or vaped in an 8 cubic meter steel chamber. One 0mg and two 18mg nicotine liquids in apple and tobacco flavor were used during the experiment, along with a regular cigarette.

Out of 20 of the chemicals found in the tobacco, only six of which were present in the electronic cigarette vapor and at much lower concentration levels. Those chemicals included butanone, acetic acid, acetone, isoprene, formaldehyde and acetaldehyde.

Image by Elaine Keller

As the table above shows, the concentrations of the six VOCs found in the e-cig vapor were at levels far below the occupational safety limit. For comparison, levels found in cigarette smoke were anywhere from 2.5 to 40 times higher.

However, the researchers also examined the vapor contents of a direct exhale into a 10 liter glass chamber to get a clearer picture of what vapers actually inhale. Of the nine chemicals found in the chamber, five are not considered toxic for inhalation at any level. The other four were found to have at least a 90 percent safety margin.

Image by Elaine Keller

Another not of importance was the amount of nicotine found in the e-cigarette vapor. While it wasn’t detected in the 8 meter steel room, nicotine was found in the much smaller glass chamber but only at very low levels. According to Allvoices, bystanders would have to directly inhale the same amount of vapor that the user inhales for 300 puffs in order to receive as much nicotine as that of a piece of Nicorette gum contains.

Conclusion

In addition to knowing what the majority of manufacturers use to create their e-liquids, we also have scientific evidence of what typical electronic cigarette vapor contains. Some of the chemicals found are indeed toxic, but only at levels far lower than those detected in cigarette smoke. Next time your local politician goes on a misinformed tirade about the lack of knowledge for electronic cigarettes, just refer them to this evidence. The Indoor Air study further backs the fact that not only do we know what’s in e-cigarettes, but vapor they produce is far safer than cigarette smoke and is not a threat to bystanders.

Further reading:

Characteristics of Tested E-Cigarettes – Indoor Air

What’s in an E-Cigarette?

Levels of Carcinogens and Toxicants in Electronic Cigarette Vapor – Tobacco Control

Emission of Organic Compounds in E-Cigs is Lower than Cigarettes – Dr. Siegel

Part 9. Nicotine is Poisonous and Causes Cancer

As vapers, the vast majority of us are addicted to nicotine. E-cigarettes can realistically be thought of as nicotine delivery devices, providing hordes of ex-smokers with the drug they crave without the vast quantities of harmful chemicals you find in tobacco smoke. Many people who argue against e-cigs are incensed by the technology because vapers are still addicted to nicotine, but these arguments inherently side-step the entire purpose of the technology: it’s a harm reduction device.

This means that yes, addiction to nicotine does often persist in vapers, but what damage does addiction really do if the chemical itself is relatively innocuous? Would anybody look down on somebody who drinks a few cups of coffee a day? Well, they probably have a mild caffeine addiction, and caffeine is a drug, so why is it any different?

It’s clear that the opposition to e-cigarettes on the basis that they allow addiction to continue leaves several fundamental questions unaddressed. To work out whether vapers are the degenerate drug addicts they’re often perceived to be or whether they’re more accurately comparable with chronic coffee-drinkers (who can enjoy their drug of choice at minimal risk to themselves), we need to look at the research on nicotine itself. It’s no angel – since around 50 to 60mg will kill you (as long as you consume it within half an hour) – but with the average e-cig cartridge or liquid containing around 18mg per ml and lasting for the majority of a day, it’s clear that overdose isn’t a legitimate concern for e-cig users. In fact, when scientists start to look at amounts somebody could realistically consume, there are a surprising amount of potential benefits of nicotine and not too many downsides.

Here are 10 studies that will change the way you look at nicotine forever…

1: Pure Nicotine Inhalation Doesn’t Cause Cancer

The most notable thing about e-cigarettes for scientists and doctors looking at e-cigarettes is that unlike in tobacco analogues, the nicotine consumed is in pure form. To investigate the effect of this, scientists subjected lab rats to pure nicotine in twice the quantities consumed by even heavy smokers. As if this wasn’t enough, they did it for 20 hours per day, five days per week, for two years.

For a smoker to consume this much nicotine, he or she would have to chain-smoke, but with two cigarettes in their mouth at any one time, and only sleep four hours per night to accommodate their goliath habit. At the end of the study, the heavily nicotine-addicted rats didn’t have more tumors or die more frequently than the “control” group of rats (who breathed ordinary air). In fact, the only difference between the two groups was that the nicotine-consuming rats lost a little weight. This study is one important piece of evidence that shows that the other chemicals in tobacco smoke cause cancer, not nicotine.

2: Nicotine Aids Weight Loss

So, why did the rat equivalents of chain-vapers end up weighing less than their ordinary counterparts? To find out the answer, a group of scientists fed one group of mice a high-fat diet and another group the standard chow diet and investigated the effects of nicotine vs. an inactive saline solution. The researchers found that the mice dosed with nicotine weighed less overall after seven weeks, and the effect was more pronounced in those on the high fat diet. In addition, the mice consuming nicotine took on fewer calories – which accounted for all of the weight loss in the ones on an ordinary diet and two thirds of it for those on the high-fat diet. It was also found that nicotine was particularly effective against belly-fat.

As an additional test, the scientists then gave the mice a drug to block the nicotine receptor (preventing the drug from taking an effect) and tried again, so that if something other than nicotine was causing the effect they would notice. The weight loss was no longer observed, thus demonstrating that it was as result of the nicotine.

3: Nicotine May Improve Cognitive Impairment

Mild cognitive impairment might not sound like much of a big deal, but it’s actually an important indicator and a significant symptom of Alzheimer’s disease and numerous types of dementia. However, nicotine had been reputed to have a positive impact on the symptoms, so a six-month pilot trial was conducted to determine if there was any truth to the claim. The study used nicotine patches (at a dose of 15mg per day), allocating them at random to half of the participants (who all suffered from mild cognitive impairment and were non-smokers) and giving the other half fake (placebo) patches.

Aside from the treatment being evidently safe after the six-month period, they found that the nicotine-consuming participants improved on tests of mental processing, attention and memory (the main outcomes they were looking for). There was no improvement on the clinician rated global impression scale (essentially doctors’ assessments of the condition), but the study supplied strong evidence of an overall benefit. The authors suggested more studies to further investigate the potential of nicotine for Alzheimer’s and dementia sufferers.

4: Nicotine Stimulates Blood Vessel Formation

Here, another important piece of information is provided about the link between nicotine and cancer. Researchers from Stanford University investigated the effect of nicotine on the process of new blood vessel growth in mice (known as angiogenesis) and on the growth of tumors. After subjecting mice to the amount of nicotine consumed by a 20-per day smoker, they found some surprising benefits. For mice whose hind legs had been (purposefully) deprived of oxygen, the researchers found that nicotine notably increased the rate of new blood vessel growth, which gives it huge treatment potential for people suffering tissue damage as a result of a stroke or heart attack. The effect is assumed to be related to nicotine binding to a specific receptor found throughout the blood vessels, triggering the release of chemicals which stimulate angiogenesis.

A related effect was also confirmed, however. Since tumors rely on blood vessels for growth (due to regular deliveries of oxygen and nutrients), nicotine has the knock-on effect of speeding up the growth of tumors. It’s important to distinguish this from causing cancer – the effect was only observed with mice which already had cancer – nicotine still did not cause the cancer. However, the take-away warning is extremely valuable: vaping is not a good idea if you have cancer, but only because nicotine stimulates angiogenesis. What is otherwise a benefit is turned into a negative by the presence of a tumor.

5: Nicotine Protects Against Ulcerative Colitis

As you may have noticed, there are numerous potential benefits to nicotine, and researchers have looked into its effect in a wide range of conditions. Ulcerative colitis is a bowel disease – similar to Crohn’s disease – and there have been suggestions that smoking actually protects against it. A researcher set out to review the existing evidence on the subject, and found that nicotine (in patch or other forms) does appear to have a notable benefit for people suffering from the condition.

Research shows that smokers have a greatly reduced chance of developing ulcerative colitis, and even that people who start smoking when they have the condition tend to get better. Obviously smoking is not a good thing, so several clinical trials were conducted (often using patches) to determine whether nicotine was the active component. The review of multiple studies concludes that nicotine is the therapeutic ingredient, and when given in addition to existing medicines for the condition, results in significant improvements compared to the medicine alone. In fact, the study suggests that it could even serve as a back-up treatment when corticosteroids can’t be used.

6: Nicotine Doesn’t Cause Serious Side Effects

Thanks to the prevalence of nicotine replacement therapies (NRTs – like patches and gums) as quit-smoking aids, there have been many clinical trials conducted on their impact on both smoking cessation and adverse health effects. A systematic review of the available evidence on the topic (looking at over 2,700 smokers in total) found that whilst NRTs have modest success rates (at best), the side-effects from consuming pure nicotine are minimal. The pooled evidence-base showed that those taking pure nicotine (in one form or another) didn’t suffer significantly more adverse effects than those taking a placebo. The only difference was that nausea was more common amongst the nicotine-consuming group, with 8.7 percent of them experiencing it in comparison to 5.3 percent of those on the placebo.

7: Nicotine Doesn’t Increase Cardiovascular Risk

Heart complications have long been associated with smoking, but a group of researchers correctly pointed out that tobacco smoke is a cacophony of things, not just nicotine. To test if it was the nicotine or the other chemicals, they reviewed studies which looked at the effect of nicotine (in the form of NRT) on people at particular risk for “acute cardiovascular events” (like heart attacks). The evidence showed that nicotine itself did not increase the frequency of cardiovascular events in the trials. This was assumed to be because other chemicals in tobacco smoke lead to the thickening of the blood (which raises the likelihood of heart problems) and nicotine does not. The researchers conclude that “The risks of NRT for smokers, even for those with underlying cardiovascular disease, are small and are substantially outweighed by the potential benefits of smoking cessation.”

8: Nicotine Doesn’t Cause Cancer

Although other research quoted above has addressed the commonly-held misconception that nicotine causes cancer, there has been plenty of research conducted on the topic. One particularly notable one involved a direct comparison between smoking and pure nicotine in over 3,000 participants, by looking at the numbers of them who went on to develop lung cancer. Unsurprisingly, they found that smoking was definitively linked to the risk of developing lung cancer. They also found that the use of pure nicotine did not increase the risk, providing yet more evidence that nicotine itself does not increase the risk of cancer, just the multitude of carcinogens in tobacco smoke.

9: Nicotine Could Help with Depression

The link between smoking and depression is well-known, but in 2006 a group of researchers looked at the impact nicotine itself has on the condition. This is a bold move in itself, since most people would assume that if anything, the psycho-active drug central to smoking should make things worse. However, the study found that when non-smokers who scored high on the depression scale were randomly assigned either a nicotine patch or an inactive placebo patch for four weeks, the ones who received nicotine had significantly decreased depression scores after eight days. After that point, the assigned dosage decreased to just 3.5mg per day, and the positive effect disappeared. Since their mood wasn’t observed to improve just after the dosage, it indicates there is a deeper underlying mechanism involved than simply the pleasurable effects of nicotine. The suggested mechanism of action has also been confirmed in animal tests.

10: Improvements in Focus and Working Memory

If you were to basically classify nicotine in terms of a type of drug, it’s a stimulant, like caffeine. This means that like other drugs in this class, it should have the effect of increasing alertness. To test this, some researchers recruited one group of smokers and another of non-smokers, assigning them two different sets of “searching” tasks (like scanning a page of text for pertinent information) of increasing difficulty. These were used to test the effects of nicotine on attention and “working memory” (which is basically equivalent to short-term memory).

The smokers were given one task when they hadn’t smoked for two hours, and then another (of equivalent difficulty) after having a cigarette. The second round of tests was more difficult to account for their familiarity with the task. In both tests, the nicotine consumption enabled better performance on the tasks. At first – when the task was new – the smokers (after a cigarette) spent much less time re-examining something they’d already looked at (indicating a short-term memory improvement). On the second nicotine-fuelled attempt they “changed strategy,” enabling them to increase the proportion of things they looked at which were relevant (indicative of greater focus on the problem). This test may have used cigarettes – but with e-cigs the same benefits come without the well-documented risks of smoking.

Image credit: StreetFly JZ

Additional Resources on Nicotine

• Nicotine: Tobacco Addition, Abuse, Effects of Cigarette Smoking – MedicineNet
• How Can Nicotine be Good for me? – Discovery Health
• How much nicotine kills a human?  – University of Graz (Recent study, published on October 4, 2013)
• General information about Nicotine – Inchem
• Nicotine shows potential medical benefits – Duke University Medical Center
• Are e-cigs really as addictive as heroin? And just how addictive is nicotine when removed from tobacco? – Ashtray Blog
• Nicotine Facts – everything you need to know