Inside E-Cigarette Liquids and Vapor
The liquid or “smoke juice” used in most electronic cigarettes is made up of four main ingredients: propylene glycol, vegetable glycerin, nicotine and added flavoring. These ingredients are almost always listed on the label, but what happens after the liquid is vaporized and inhaled? Although there’s plenty of information about what’s inside e-liquid, research is finally shedding some light on the vapor as well. Studies report what many of us have suspected all along, that it’s significantly less harmful than tobacco smoke and poses virtually no health risks to users or bystanders.
Common E-Liquid Ingredients
The liquid inside an e-cigarette, often referred to as ‘e-liquid’ or ‘smoke juice,’ is the key to delivering nicotine to users (if they so desire). Once heated, it creates a vaporized mist that’s inhaled just like real cigarette smoke. Before we get to the vapor, let’s discuss the main ingredients used in virtually all e-liquid:
Propylene Glycol (PG)
Propylene Glycol is an organic compound created in laboratories and has been approved by the FDA for various purposes. It’s used in theatrical smoke machines, skin and personal care products, pharmaceutical goods and as a food additive in thousands of different products that we consume everyday. In an electronic cigarette, PG is used as an e-liquid base to produce vapor and is known for creating a strong ‘throat hit.’ The liquid is colorless, odorless and tasteless, and it’s been studied extensively for years. Research has confirmed its safety in various forms, including vapor.
Vegetable Glycerin (VG)
Like PG, vegetable glycerin (or vegetable glycerol) is another base ingredient used in electronic cigarettes. VG is derived from vegetable plant oils and is considered 100% natural and safe. Because of it’s thicker properties it tends to produce more vapor, but less throat hit, so many e-cig companies use a combination of PG and VG to produce the most accurate and enjoyable experience.
Nicotine gets a bad rap, and although it can be highly addictive and produce mild side effects, nicotine DOES NOT cause cancer. There are more than 4,000 other chemicals found in cigarette smoke, many of which are cancer-causing carcinogens and the source of most smoking-related diseases. A stimulant similar to caffeine, nicotine is found naturally in tobacco leaves, as well as 66 other plants such as tomatoes, eggplants, potatoes, and more. Not all e-liquid contains nicotine, and it’s level can be customized by the user based up their personal preference.
In some cases, especially when VG is the primary base ingredient, distilled water is added as a diluent to reduce the viscosity of the e-liquid mixture. This helps to prevent build up and ensures smooth and trouble-free e-cig operation.
One of the attractions to e-cigs for many users is the wide array of flavors. Although the actual ingredients vary between manufacturers, flavoring is typically made-up of naturally occurring, FDA-approved, food-grade additives. Examples include:
Acetylpyrazine – A commonly used food flavoring added to coffee, popcorn, potato chips, sesame seed, almonds, wheat bread, cocoa, pork and beef.
Beta-Ionone – A food-grade fragrance found in essential oils used to provide aroma. It’s currently being tested for the treatment of colon cancer.
Dimethylpyrazine – Another commonly used flavoring ingredient found in the food, drug, and perfume industries.
Ethylpyrazine – A flavoring used in food products such as pork and soups.
Linalool – A naturally-occurring chemical found in many flowers and spice plants.
Mallic Acid – An organic compound used in fruit flavored e-liquids. It provides a sour, tarty taste and is also added to some cola drinks to lower their pH levels.
Rose Oil – A natural extract from roses used for it’s scent.
Trimethylpyrazine – An FDA approved flavoring commonly used in caramel, chocolate, cocoa, and coffee.
Vanillin – Used in vanilla and other desert or cereal flavored liquids, like the Fruity Pebbles vape juice. It’s the primary component of vanilla bean extract. Vanillin may be extracted from vanilla pods or artificially made from lignin.
Let’s Talk About the Vapor
Knowing about the different ingredients and what is (or isn’t) in an electronic cigarette may give you peace of mind, but the ingredients are only a small part of the equation. Once the liquid is heated, vaporized and inhaled – it’s qualities change as it enters your lungs and eventually gets released into the atmosphere. Just like every product that we eat, drink or ingest, impurities can be found in electronic cigarettes, but do these impurities have any effect on users? What about others? Do bystanders need to worry about ‘second-hand’ exposure to e-cigarette vapor?
A 2012 study published in the scientific journal Indoor Air compared the vapor of electronic cigarettes to that of conventional tobacco smoke. To determine the impact in an indoor environment, the researchers analyzed the volatile organic compounds (VOCs) released after test subjects either smoked or vaped in an 8 cubic meter steel chamber. They also examined a direct exhale into a 10 liter glass chamber to get a better picture of the contents in the vapor.
In both cases, researchers found significantly less chemicals in e-cigarette vapor than tobacco smoke. Of the twenty VOCs found in tobacco, only six were present in the electronic cigarette vapor and at much lower levels – far below occupational safety limits. The e-cigs had 2.5 to 40 times less butanone, acetic acid, acetone, isoprene, formaldehyde and acetaldehyde. Of the chemicals that were considered toxic, the levels found in e-cigs were in at least a 90 percent safety margin.
No Detectable Second-Hand Exposure
Electronic cigarettes release extremely low levels of toxins into the air, well below occupational safety limits, and further studies have shown second-hand exposure to nicotine in e-cig vapor is virtually nonexistent. Not only are e-cigs safer for users than traditional cigarettes, but there is virtually no risk for second-hand exposure. According to a 2012 study by CleanStream Air:
…we can conclude by saying that it would be more unhealthy to breath air in a big city than staying in the same room with someone who is vaping.
Besides the lack of chemicals found in electronic cigarette vapor, it’s important to note that vapor disperses much more quickly than tobacco smoke, and unlike cigarettes which emit smoke even when they’re not being used, electronic cigarettes only produce vapor when a user activates the device.
Misleading Study on E-Cigs
One of the earliest studies evaluating electronic cigarettes was conducted by the FDA in 2009. This controversial study led to a sudden ban of e-cigarette imports but was quickly overturned just four months later by a U.S. federal court. Although the study was considered inconclusive, it’s widely referenced in the media.
In the study, the FDA evaluated 18 cartridges from two popular e-cigarette brands – Njoy and Smoking Everywhere. The study gave us our first glimpse of what’s inside an electronic cigarette, but it only evaluated samples from two – out of hundreds of different brands. In particular, the agency looked for tobacco-specific nitrosamines (TSNAs) – cancer-causing carcinogens found in virtually all tobacco-based products. It found TSNAs in 5 out of the 18 samples tested, along with traces of diethylene glycol – a highly toxic substance – in one of the cartridges.
One (of many) important facts left out of the FDA report was the amount of TSNAs discovered in the samples. An analysis conducted a week later by Dr. Michael Siegel, Professor in the Department of Community Health Sciences, Boston University School of Public Health, discovered that the average e-cigarette cartridge (1ml of liquid) contained under 8.2 nanograms of TSNAs. In comparison, there are 11,190 nanograms of nitrosamines in a gram of Marlboro tobacco – almost 1,400 times the amount in an electronic cigarette. To provide some reference, In 1981, the National Academy of Sciences estimated that the average person was exposed to 1 microgram of nitrosamines per day, or one millionth (0.000001) of a gram. A nanogram is one BILLIONTH (0.000000001) of a gram!
And regarding the diethylene glycol mentioned during the study, it was found at extremely low levels (under 1%) in just one of the 18 samples. It’s never been discovered in any other electronic study since then, and at these amounts it would take 750,000 e-cigs to receive a lethal dose.
The media often refers to this FDA study and it’s “toxic”, “cancer-causing” findings without any mention of the lack of data or the fact that it was ultimately shown to be inconclusive. And the toxic chemicals found in the report were proven to be insignificant, at levels that are completely harmless to humans.
* See a complete list of electronic cigarette studies →
A Much Safer Alternative
No one in the electronic cigarette industry is claiming that e-cigs are 100% safe and there’s undoubtedly some risk whenever you inhale something other than pure, unpolluted air. But the risks are significantly less than those from smoking tobacco, and the dangers of second-hand vapor are virtually nonexistent.
For those who are trying to quit or are looking for a safer alternative to smoking, electronic cigarettes can help you avoid hundreds of harmful chemicals and enjoy a variety of other benefits. Critics claim that there hasn’t been enough long-term testing, but common sense tells most users that electronic cigarettes are a much better choice and are worth the significantly reduced risk.
Thank you for publishing the facts – instead of the hype we’re force fed every day…
I believe that we also need more studies on the vapor its self.
It’s good to know how low the actual levels of toxins are that exist in the e-liquid, but I “Believe” that a legitimate scientific study of the actual vapor produced, and blood testing of those who are ingesting it would show an even greater harm reduction than that represented by studies of the liquid being vaped.
Several of the studies that we mentioned above do exactly that – they evaluate the vapor.
But there undoubtedly needs to be more research! Electronic cigarettes have only been around for a few years, so the biggest thing we’re lacking is LONG-TERM STUDIES showing the ongoing impacts of inhaling nicotine vapor. This will take more time and money, but it’s definitely coming. If past studies are any indication, it will continue to support the fact that e-cigs are much safer than tobacco… so bring it on!
So if there is no nicotine in a bottle of e juie then is it illegal for a kid to smoke it… the facts say that its mostly VG and Glycol then a little bit of food flavoring and all of these ingredients are harmless
In most states, minors can no longer purchase e-cigs. It doesn’t matter if they include nicotine or not…
I would like to know if there have any studies done on allergies to either the PG or VG that the vapor juice are made of, last year I had been using vaping juice that was made of the purest ingredients, I ended up with a sever rash on my body that burned and looked like I was burned, so I stop with vaping and doctor put me on steroids and I cleared up. this year I have been using vapor juice again of purest ingredients, and now my eyelids and under my eyes the skin is deep red and burns and it comes and goes, I have no nicotine in the juices this time, I was thinking the nicotine may have given me the rash last year. have you heard of this before. any help would be great I don’t want to pick up cigarettes again.
Thank You Nancy
Propylene glycol (PG) can cause allergic reactions in a small percentage of people. If you’re allergic to PG, I would suggest trying 100% VG. Many companies offer 100% VG e-juice. You could try:
Mt. Baker Vapor
And many more…
its funny how this article is for e cigs and contains studies with actual figures to compare. just read another article saying e cigs are bad cited a study of 30 non smoker smoking an e cig and they could only come up with it restricts your airways. then give plenty of opinions on the chemicals in it (or they falsly say are in it). I was talking to my auto teacher at the college one time who hates any kind of smoker( puts vaporers in the smokers category) he asked what was in it and when propalene glycol came up he said glycol is poisonous that’s what is poisonous in antifreeze and brake fluid. I said ” that is dietholene glycol not propolene glycol and it is in a lot of foods you eat and you don’t know it”. long story short I think a lot of people are just unhappy with themselves and it kill them to see someone enjoying something. or like stated before these coorperations that are loosing money on it are pushing false propaganda.
nice article, but nonetheless, i quit vaping. i got too addicted to it, and my nicotine intake huge. my hands are trembling of nicotine withdrawal, but i try to find new hobbies 😛 will miss smoking and vaping. but my throat can not handle neither.
This is my only concern about vaping. I’ve been a (sometimes *very* heavy) tobacco smoker for more than 45 years – since I was barely 10 years old.
The nicotine addiction is actually not that hard to break. I’ve quit cold-turkey 4 times (once for more than 6 years) with little but a couple of weeks of feeling “edgy and desperate for a smoke”… but the real problem is the establishment of regular, non-stop habits that comes of years spent putting a cigarette in your face every time something happens.
Maybe with vaping, I can go on with the habits and wean myself easily from my present 2-5 cig/day habit… and *then* tackle the associations that go with putting a smoke in my face.
Keep in mind the FDA never does any testing….EVER. FDA approved means nothing. ..and the Pharmaceutical companies are their Clients. Go from there.
I have been vaping off and on over the years and finally in may 2015 I quit smoking. I feel so much better vaping. Everyone wants to bash something that is good. I don’t think vaping is bad for anyone vaping or being around a person vaping. It’s saving my life along with many others’ lives that I’m around.
Thanks to whoever invented vaping.
I agree with you on some instances scott that they dont do studies on certain seemingless harmful things before approval, but something as habitual, popular, and highly controversial as vaping will be studied carefully ti avoid certain backlash and scrutiny towards the FDA.
I just got out of hospital, having Iscemic Colitis. My illness was caused by smoking for almost 40 years. My surgeon thought it was FANTASTIC I had been able to kick my nicotine habit. He advised me to try to get down to 0% nicotine. So I am trying! Thanks for the enlightening post. I hope all my family and friends will get off my back to quit vaping! I like it!!!
Thanks for the clear information, but I am curious about health risks with the more powerful batteries and heat of newer ecig on the market. Does tempature change the chemical make up of vapor
There has been at least one study (don’t have a link right now) where they did find higher levels of chemicals when e-liquid was vaped at higher temperatures in higher voltage / wattage mods. And many of the misleading studies being published by the media (showing high levels of chemicals) got their results by running e-cigs to the point of burning the coils – something vapers would never do because it tastes so horrible! In either case, the levels were still much lower than traditional tobacco smoke.
Many believe these higher levels are due to wicking material being burnt when it becomes too hot, which makes the latest advancement in e-cig technology (temperature control) so exciting. Temperature control basically limits how much heat the coil can generate, and in turn prevents the device from burning the wick. Many of the newest devices on the market now include this feature.
But it’s still too early to say whether or not this actually makes vaping safer, or if there’s anything to worry about when vaping at higher power and temperature levels. More research will certainly be necessary, but I don’t think that there’s any question that vaping is safer than smoking. And if you’re not getting a nasty burnt flavor, you’re probably alright…
Really should have a talk with the Montana quit line and their commercial scare tactics, claiming that e-vapor contains such chemicals as ,arsenic, formaldehyde, and heavy metals like tin, saying it can cause dangerous second hand effects. This is some great information, thanks a lot!
I was a smoker for a long time.I came down with bladder cancer.The number one cause was smoking cigarettes.I swished to vapor,and so far im cancer free.I still have to go byopsy’s every 3 month’s for a year.Im very satisfied with the vapor.I use carolina sunset 2.4,and they satisfy me.Im still getting the nicotine,but not the bad stuff,in the cigarette.
Nicotine does cause cancer. Even it is vaped in an e cig there is a carcinogen called benzoapyrine. This article is false! Nicotine does cause cancer! As well as heart disease because it constricts your blood vessels. Whoever wrote this article needs to do more research.
Benzoapyrine (properly spelled benzopyrene) is found in tobacco smoke, but NOT in nicotine. If you did YOUR research you would have found that all of the studies (completed decades ago) that discovered this carcinogen used tobacco smoke to produce the results – not pure nicotine. Pure nicotine IS NOT carcinogenic and does not contain carcinogenic compounds.
Here is some research in case you’re interested:
If you want to go down that slippery slope then we can say that the hydrolizing of glucose during the redox reaction associated with mitochondrial oxidative phosphorylation (or in laments terms, simple aerobic sugar metabolism during cellular respiration) causes free radical compounds that can inadvertently cause potential mutagenic genomic processes over time. Thus increasing the probability for cancer. Don’t try to make assumptive correlations when they are so indirect, it’s foolish. Do YOUR homework…. Coming from someone who had their Masters in Biochemistry and has personally run both liquid and atomized vaping liquid through a gas chromatographer and analyzed the results first hand.
I am a non smoker. Was sitting in car on road in town centre with window open. Someone passed and smoke came into car. I started coughing and got a vile taste in my mouth for ages. The smell was stinking as staid up my nostrals for ages. People should not be allowed to use these vapours in public places. I do not believe these are not harmful to either the smoker or the person that gets the smoke whether they want it or not and many people using these are selfish and do not have any consideration for others who do not have this disgusting habit
We definitely agree that people should be considerate when using vapor products, but do you really expect someone to quit using their e-cigarette in their own car? And you may not “believe” that these products are safe to you as a bystander, but the evidence is OVERWHELMINGLY CLEAR. Numerous studies (conducted by various organizations) have shown that secondhand vapor is harmless. This article was written 4 years ago, you can find a long list of additional studies that support e-cigarette safety here:
Thanks for the terrific article