Welcome to week 4 of the Knowledge is Power blog series. This week we will be going over the basic ingredients included in e-liquid, also known as e-juice or just vape juice. It’s always a good idea to know what you’re putting into your body, whether it be ingestion, injection, or inhalation. An ironic statement considering no one really knows everything that’s used in cigarettes, yet I’m sure the majority of us went right on inhaling that, even though we knew it was incredibly unhealthy.
The Food and Drug Administration (FDA) website1 states “consumers currently don’t know how much nicotine or other potentially harmful chemicals are being inhaled during use [of e-cigarettes].” Though the FDA says consumers don’t know what they are inhaling, a vast majority of e-cig companies are upfront and transparent about the ingredients that are in e-juices. So, let’s look at what’s actually being inhaled during use of e-cigarettes. E-juice contains only 4 ingredients, Propylene Glycol (PG), Vegetable Glycerin (VG), nicotine, and flavoring. PG and VG are both on the FDA’s list of substances that are Generally Regarded as Safe (GRAS), meaning the FDA3 has reviewed possible toxicology and safety issues regarding these substances and have considered them generally safe for use. In order to truly understand, let’s take a closer look at each of these ingredients in more detail.
The first ingredient we will be discussing is PG. The Dow Chemical Company 2 describes PG as “a clear, colorless liquid with the consistency of syrup. It is practically odorless and tasteless, is an excellent solvent for many organic compounds, and is ideal for a wide array of applications.” In e-cigs, PG allows atomization (conversion from liquid to vapor) to take place at significantly lower temperatures than required for an analog cigarette, and will also help deliver the nicotine when the vapor is inhaled. Propylene glycol has been used for over 50 years in a large variety of applications, including pharmaceutical aerosol applications. The Journal of Pharmacology 4 conducted a study to determine the safety of employing the vapors of PG in atmospheres inhabited by human beings. They were exposed continuously to high concentrations of these vapors for periods of 12 – 18 months in a study titled, Tests for the Chronic Toxicity of PG and published their results stating “the absence of any observed ill effects in patients exposed to PG vapors for months at a time provide assurance that air containing these vapors is completely harmless.” Which tells us that even inhalation of PG vapor has caused no harm to the subjects in this study. the US Environmental Protection Agency (EPA)5 has also published on their website the statement, “Upon reviewing the available toxicity information, the Agency has concluded that there are no endpoints of concern for oral, dermal, or inhalation exposure to propylene glycol.” Which seems pretty self explanatory; they found no toxic concerns regarding the inhalation of PG. The last study I’m going to share today is actually from the Journal of Aerosol Medicine 6, who conducted a study to determine if there was potential toxicity of aerosolized medications (that utilize PG as their solvent) mixed with PG and given by inhalation. Their study results state “There was no systemic toxicity or clinically limiting local respiratory toxicity associated with inhalation exposure to medication inhalation solution at exposures up to 2.7 times the maximum human exposure. These studies demonstrate the safety of aerosolized medication in propylene glycol.” In a nutshell, all of these independent agencies have studied the inhalation of PG vapor to determine if it was toxic or if it was safe for humans. They all concluded that inhaling PG was non-toxic and showed no concerns regarding its safety.
Second, we will take a look at Vegetable Glycerin (VG, and also sometimes referred to as Glycerine, or Glycerol). VG is a carbohydrate made from plant oils. CanadaVapes 7 explains the use of VG in e-cigs as “the ingredient that produces the smoke like vapor when the e-cigarette is exhaled. VG typically produces more vapor production than PG, but has a reduced throat hit. It is also slightly thicker and slightly sweeter than PG.” So, now that we know what it is, and how it’s used in e-juice, let’s look at it’s safety. VG is included in the list of products generally regarded as safe by the FDA3, which, as stated earlier means the FDA has found no toxicity concerns regarding the use of VG. Additionally ACI Science 8 published a Glycerine Overview where they concluded “The non-toxicity of glycerine has been established through generations of safe use and by supporting data. Glycerine occurs naturally in foods, and when metabolized, yields roughly the same caloric food value as glucose or starch. Glycerine imparts a desirable degree of sweetness without clashing with the other flavor elements.” In addition, Livestrong.com 9 published an article titled Side Effects of VG which states “Vegetable glycerine, also called glycerol, is used in various applications throughout the food-processing and pharmaceutical industries for its potential health benefits.” Because the use of VG is seen more in food processing and cosmetic applications, there is less data available concerning, specifically, the inhalation of VG vapor. Although there is less data, there is no reason to automatically call it unsafe. It is a naturally derived organic compound (meaning it is comprised of only hydrogen, oxygen, and carbon molecules), and has medical uses (in topical treatments and cough mixtures) that have been tested, and proved safe for years. More information on the common uses of VG can be found on Wikipedia12. Again, it appears that the general consensus is that VG is also safe.
Now, for nicotine. As we discussed last week. Nicotine in e-juice is relatively safe. For a more detailed overview of the safety concerns regarding nicotine please see our blog Nicotine – Deadly Poison or Promising Medicine10. Though we know from our previous blog that nicotine is relatively safe, the FDA1 has also stated in the past that ‘consumers don’t know how much nicotine is being inhaled during use.” This is similar to their statement regarding consumers not knowing the ingredients in their e-juice, and again, a majority of e-cig companies are transparent about the levels of nicotine in all of their e-juice. Consumers are absolutely able to choose their levels of nicotine, but many wonder when they first start out what level of nicotine strength is the right one to use. Realistically, there is no right or wrong answer to that question. Nicotine strength in vape juice is strictly a personal preference. However, if you’re unsure of what might work for you, here is a general idea of how to understand how nicotine strength in e-juices compares to nicotine in traditional cigarettes:
- 0 mg/ml means no nicotine, for someone who wants the vaping experience without the nicotine.
- 3 mg/ml – 6 mg/ml is generally for those who smoke less than half a pack a day or smoke ultra-light cigarettes.
- 12 mg/ml is generally used by those who smoke less than a pack a day of full flavor, or about a pack a day of lights.
- 18 mg/ml is generally used by those who smoke approximately a pack of full flavor cigarettes a day.
- 24 mg/ml + is generally used by heavy smokers who used full flavor and smoked more than a pack and a half a day.
Keep in mind, this guide is very subjective, and when deciding on the proper level of nicotine it’s always a good idea to do a little bit of experimentation of your own.
The final ingredient we will be looking at is the flavoring. Each individual e-juice has it’s own unique blend of natural and/or artificial flavors. All flavorings are food grade and generally regarded as safe by the FDA.
As always, I strongly encourage all of you to read the references listed below, research and educate yourselves. Based on the information I have found as outlined above, the research shows there is no evidence to support concerns regarding the safety of the ingredients used in e-juice. Let us know what you think of the blog, and any additional information you find. Be sure to come back next week when we look at Diacetyl and E-Juice. Till then, Vape on!
Written by: Michelle Harnden
- The Dow Chemical Company “Propylene Glycol”
- FDA GRAS list
- The Journal of Pharmacology ‘ Tests fo the Chronic toxicity of PG’
- Journal of Aerosol Medicine Preclinical Safety Evaluation of Inhaled Cyclosporine in Propylene Glycol
- CanadaVapes Vegetable Glycerin Safety
- ACI Science Glycerine Overview
- Livestrong.Com Side Effects of Vegetable Glycerine
- Nicotine – Deadly Poison or Promising Medicine
- Wisegeek “What is Diacetyl”
- Wikipedia “Glycerol [Vegetable Glycerin]
You may also like our article about Nic Salts!