Examining Hazardous Vape Juice Flavorings

On most packages of e-liquid, the ingredient lists are small, just a few ingredients, but then at the end, there’s that little word – flavoring. Whether natural or artificial, this little word, the least prevalent ingredient in any e-liquid may be the most dangerous ingredient of all.

In reality, most flavorings in e-liquid do not cause harm, but there are a select few that, while safe to consume, are not as safe to inhale. While the FDA approves the majority of the flavorings used for consumption, not only do they not often test for inhalation risks but with no regulation for e-cigarettes yet in place there is nothing to stop any company from using any flavoring they so desire. Ethical and responsible companies are going to do everything they can to provide vapers with a quality e-liquid or e-juice. However, even the e-liquid companies cannot make studies materialize that do not exist. As scientists, as vapers just as general humans we have no idea what the potential harm is to inhale many of these so called approved flavorings, let alone what inhalation of the items will be like after vaporized.

E-cigarettes are so new to the market that there is little way to even understand what the risk are of inhaling e-cigarette vapor. While most people were concerned about the effects of inhaling Propylene Glycol (which most tests have proven to be a benign substance to inhale) or the concern about the effects of the nicotine, people have widely skipped over the most potentially hazardous part of the e-cigarette liquid altogether. That little ingredient sometimes identified as no more than just “flavoring.”

There are natural flavorings that a vaper can opt for. For instance, if they prefer a fruity flavor there are plenty of natural extracts that will translate into some of the most popular flavors. Still, even though there is no doubt that inhaling banana extract is pretty benign, we still do not know what the effect is of vaporizing and inhaling substances that were intended for oral consumption.

The best example of the difference in inhaling and consuming a flavoring is well known, especially in the consumer and manufacturing world. Several workers exposed to the flavoring diacetyl, most commonly used in popcorn factories as a butter flavor, began developing lung disease as a result of the inhalation of a substance that was deemed safe to consume orally. This was discovered only after the workers were exposed, leaving plenty of room for concern about what other flavorings can do if inhaled rather than consumed.

Even recently a report was published claiming that a man has contracted, Bronchiolitis Obliterans, what is more commonly known as “popcorn lung” as a result of his e-cigarette use. The report was immediately retracted due to its false diagnosis. However there still appears to be a health related lung reaction, and it seems clear that the flavoring is the culprit.

What We Know About Dangerous E-Liquid Flavoring

There has been some effective research done on flavorings and the potential for harmful flavoring chemicals to be used in several e-liquid products. Konstantinos Farsalinos is a cardiologist and researchers at the Onassis Cardiac Surgery Center in Athens, Greece. He is well-known as an outspoken proponent of e-cigarettes and their ability to help smokers replace their regular cigarettes for electronic ones. With over 438,000 deaths in the US alone being attributed to the use of cigarettes, he believes that e-cigarette have the potential to save lives and help smokers kick their addiction. He was the lead author on a recent study published in the Society for Research on Nicotine and Tobacco that focused on sweetly-flavored e-juices.

Farsalinos and the other researchers analyzed 159 e-liquid flavors from 36 different manufacturers and what they found was surprising to some. Of the flavors tested, around 70% contained the potentially harmful chemicals diacetyl. Many e-liquids also tested positive for acetyl propionyl, which is also potentially harmful to inhale. These numbers are frankly unacceptable. However, it doesn’t present as much as a risk as it initially appears, according to Dr. Farsalinos. Lungs

In his study, he compared exposures from vaping with proposed limits suggested by the National Institute Of Occupational Safety and Health (NIOSH), which were designed to protect Americans exposed to chemicals in the workplace. One of the main points that Farsalinos is quick to point out about e-cigarette flavoring is that in most cases the level of flavoring used is relatively low, though it looks different when analyzed through the NIOSH framework. He believes that the NIOSH limits are “extremely strict.” The levels are determined by allowing no more than one person out of one thousand to suffer lung damage if exposed for a work life of 45 years.

He is not the only one who believes that the risk for dangerous flavoring levels is much lower than represented. A recent study, published last April in Tobacco Control looked at several flavorings and found some that were suspect. However, they also found the amount of flavoring used was much smaller than what we see in tobacco cigarettes. Firstly, the researchers measured the amount of flavor chemicals present in 30 different e-cigarette fluids with different flavors. The flavoring, they found, was a small portion of the total e-liquid itself measuring anywhere from 1 to 4 percent of the e-cigarette liquid composition, equal to about 10 to 40 mg per mL. Small as the amounts may seem, the findings so bring to light concerns about health effects, stating that 6 of the 24 found compounds used to flavor the e-juice were known aldehydes, which are proven to cause respiratory irritation.

The study author, James Pankow, is a professor at Portland State University. He and his co-authors wrote of the results: “The concentrations of some flavor chemicals in e-cigarette fluids are sufficiently high for inhalation exposure by vaping to be of toxicological concern.” Of course, that assertion does not mean that all of these chemicals are definitely toxic, especially at the smaller doses that are found in the e-liquid solution. In fact, when compared with regular cigarettes,  e-cigarette liquid has far less chemical flavorings than traditional cigarettes, with regular cigarettes containing an average of 8% flavoring content, far lower than e-liquids 1 to 4 percent.

The researchers calculated their toxicological concern level based on what a typical person would be exposed to in an average day of vaping (about 5 mL of liquid). At this amount, they compared levels of these chemicals to what is considered the workplace limit, and several brands tested did have higher levels, and that could be a concern if one of those chemicals is diacetyl or one of its other potentially hazardous chemical counterparts. The workplace limits used in this study were established for factory workers in candy or other edible product factories. However, the standards may not immediately reflect a situation even comparable to e-cigarette use. However, in a research field as new as e-cigarettes, workplace standards provide one of the only standing frameworks we have that help us to understand inhalation risks.

Also using workplace standards as a measurement tool, Farsalino’s study purports that vapers should be able to withstand approximately 86 micrograms of diacetyl a day from vaping and still not exceed NIOSH’s recommended safeguards. At this level, several, but not all, of the e-liquids tested exceeded the daily limit for a medium to heavy smoker.

Still, with many e-liquids that were reviewed exceeding the daily limit, and definitely surpassing the amount of ejuice in a standard sized 3ml vape tank, it should be noted that workplace exposure would be significantly different than vaping. The tests that determine workplace exposure wouldn’t be considering the heavy exposure that can come with vaping as opposed to causal breathing. For instance, some critics believe that there would be a difference between inhaling the workplace limit in around 500 breaths as with vaping, versus thousands of breaths over the course of an 8 hour work day. The truth is new studies need to be performed to calculate the risk with specific attention to vaping in mind.

What is even scarier, is that the industry testing that is in place may be insufficient to detect levels of diacetyl and another butter type flavoring, 2,3-pentanedione, according to an informal report by the Milwaukee Journal Sentinel. They only surveyed 5 e-liquids, but found diacetyl in all of their samples, leading them to question the overall safety of the e-liquid and industry testing. They believe, “The method typically used to analyze e-liquids for the industry is not sensitive enough to detect levels that could be harmful. As a result, e-liquid makers across the country claim their formulas are diacetyl free when sometimes they are not.”

Even with some question on whether or not diacetyl is included when a diacetyl free label is present, many companies are taking extra precautions to make sure that these potentially hazardous flavorings are not included in their e-liquid solutions. Several companies now hire independent laboratories to ensure safety, and there are also many other ways to help keep you safe in a world of unknown e-liquid flavorings.

How to Pick a Safe E-liquid

You can always steer toward natural and organic flavorings. Several e-liquid companies offer all naturally flavored e-juices that get their flavor from organic extracts. While we don’t know the effects of inhaling natural extracts either, they are obviously safer than chemically made flavorings. As mentioned before, several e-liquid companies are now also selling products with diacetyl-free assurances or labels to help users make safe e-liquid purchasing choices. The use of e-liquid bottlesindependent researchers to verify their labels as well will hopefully put to rest concerns about the e-cigarette industry testing standards.

If you’re still harboring concerns, you can also avoid any e-liquid that has any buttery type flavors, even cream-based flavors could be potential carriers of diacetyl flavoring. Baked goods flavors are a great example. While most companies, especially ones in the USA, will avoid using the harmful chemical flavoring, you can never be too certain when you may encounter a counterfeit brand or sub-par e-liquid company. If you are still worried, it might be best to avoid these flavor notes altogether.

Also, buy USA made e-juice when possible, of course, there are several reputable European companies as well. Either way, know your e-liquid company and make sure they are a safe and recognizable brand.

The Future of E-Liquid Flavoring

The flavoring is the biggest variable in the e-liquid, if not the e-cigarette, world. There is so much that is unknown, but hopefully, that won’t be for too long. The rules that the FDA have proposed to regulate e-cigarettes have been sent to Washington D.C. for final approval, and when that action takes places the landscape of the e-cigarette world may appear a lot different than what we see today. Ingredient lists will be a major change in the e-cigarette world, but it is still unclear whether or not e-liquid manufacturers would still have to specify the exact flavoring ingredients used, as even in some food products the word packet “artificial flavoring” seems to suffice. Still, many e-liquid manufacturers are clear that they pledge to keep harmful flavoring chemicals away from their e-liquids and their users.

Just as Dr. Farsalinos and his colleagues stated, keeping these harmful flavorings away from users is an avoidable risk, one that we can but hope will soon become a distant memory. In the meantime, buying from reputable companies and researching your brands could be the only thing keeping those harmful chemicals at bay. Without harmful flavoring chemicals, the e-cigarette is even more clearly the healthier option for those looking to replace their harmful smokes with a safer alternative.




  1. E-liquid Flavors keeps harmful flavoring chemicals away from this. Also no matter the E-liquids are quiet safer then nicotine included in Cigarettes. So a best solution to quit smoking is E-cig.

  2. “Also, buy USA made when possible, of course, there are several reputable European companies as well. Either way, know your e-liquid company and make sure they are a safe and recognizable brand.”
    What? u forgot about that big ‘ol country North of you?

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