E-liquid: we pick it up every few weeks (days?...hours?...OK, I’ll just grab some now), we love the amazing taste, the spot-on recreations they emulate, the big clouds they become with the press of a button—but, wait, where does this stuff even come from? What’s even in there, anyway? Great questions! Let’s dive deep into the components of e-liquid, what they do, and how they affect you.
E-liquid, despite all the mystery that has been stirred up around it, remains as simple as it was when it was first created—all that’s needed to produce the goopy liquid we all love are four ingredients: propylene glycol, vegetable glycerin, flavorings, and nicotine(optional).
Propylene Glycol (PG, E1520)
Propylene glycol is a sugar alcohol very common outside of the vaping world. It is easily found in many different application, such as creating theatrical smoke, for carrying medications like asthma aerosols or liquid medications, and keeping cosmetics fresh for longer. PG is completely water-soluble, meaning it’s easily absorbed by the body within 48hrs, and is documented to have very little adverse effect on human health, if any at all.
“No studies were located regarding respiratory, cardiovascular, gastrointestinal, musculoskeletal, hepatic, renal, endocrine, dermal, ocular, or body weight effects [of PG] in humans, or musculoskeletal, dermal, or ocular effects in animals after oral exposure to propylene glycol.” - CDC, 1997
Propylene Glycol is an invaluable addition to e-liquid, providing a stable carrier for both the flavorings and the nicotine in the e-liquid—otherwise, they are both prone to separating and creating “hot spots” of unmixed nicotine or flavor in the liquid—as well as serving as a thinner for overly thick juices. Naturally harsh when vaped alone, PG also provides the “throat hit” that former smokers seek.
Vegetable Glycerin (VG, Glycerol, E422)
Vegetable glycerin, shortened to VG and sometimes referred to as glycerol, is a sugar alcohol that is often substituted for sugar in low carb foods due to its slightly sweet taste and its lack of effect on blood sugar levels, a welcome property for diabetics craving their favorite foods. VG is also found used in a number of other applications, such as icings, toothpaste, and soaps. It’s also commonly used as an emergency skin treatment either solely or as part of a complementing solution due to its hydrating properties.
Vegetable glycerin is non-bioaccumulative, and has a very short half-life of only 30-40 minutes. It is generally regarded as safe by the FDA, as is PG as well.
“Glycerol exhibits low acute and chronic toxicity in humans and experimental animals with no evidence of reproductive, genotoxic/mutagenic, or carcinogenic effects.”
On its own, vegetable glycerin is very thick and viscous—this is used to the advantage of vapers to create nice, thick juices perfect for RTAs and sub-ohm tanks that would otherwise leak more than Edward Snowden with a runny nose. This may be why we’ve seen a shift in e-liquid formulations as of late—while once the dominating solvent in most e-juices, PG has given way to VG in terms of ubiquity and prevalence in e-liquids on the market. VG also gives juices a nice, smooth feel when vaped, as opposed to PG’s harshness.
The flavorings used in e-liquid are often the exact same ones used in a countless number of your favorite foods—that’s how they taste so real! All of these flavors are FDA-approved for consumption, though admittedly, little research has been done as far as the effect they may have when inhaled. However, no adverse effects have yet been reported for short-term use, and the outlook on long-term use is very optimistic.
Oh, nicotine. The chemical the world loves to hate. For all the shade it catches for being associated with those packs of analog sticks we’ve long since dropped, vaping e-juice avoids the combustion process that adds the carcinogenic compounds we should avoid.
Nicotine is an alkaloid found in plants of the Solanaceae family, also known as the nightshades. Obviously, tobacco falls under this category, but did you know that other plants such as tomatoes, eggplants, and potatoes also fall under this family, and as such, also contain nicotine? Yep, they certainly do, although in far lesser amounts than tobacco, which has been carefully groomed over the years to produce very large amounts of nicotine.
- Is it just water vapor?
Mostly, but not completely. The vapor expelled by the heated coil primarily consists of the ingredients of e-liquid. However, as it is inhaled and exhaled, it binds to water vapor molecules in the air and your lungs, creating a 90% water / 10% e-liquid cloud of steam, which adds a great deal of mass to the e-vapor—this is why your coil puts out a lot more vapor if you blow on it as it fires.
- Is there antifreeze in my juice?
Eh, kind of, but not the kind you’re thinking of. Both PG and VG lower the freezing point of water when mixed in and have been used for just that reason in automobiles and other applications for quite a while, but only when the traditional antifreeze chemical, Ethylene Glycol(EG), is too toxic to be used. EG is very, very toxic and has a slightly sweet taste, lending itself to the deaths of many a family pet. However, PG and VG are far, far less toxic and are used to replace the poisonous alternatives.
- Will the vapor condense in my lungs?
That’s a resounding “negatory,” Ghost Rider. All of the ingredients in e-vapor are easily absorbed by the body, especially in the minute amounts they are deposited, mainly because there are no lipids—another word for fats or oils, which are very difficult for the body to absorb and will quickly cause lipid pneumonia if inhaled. By comparison, the mucus-producing glands in your lungs—the goblet cells on the surface epithelium and the seromucous glands underneath—produce about two liters of mucus per day; the vast majority of this is naturally absorbed by the lungs.
- Does it produce carbonyls and aldehydes such as formaldehyde and acrolein?
Nope, at least not when used correctly. These chemicals were first announced as found in e-vapor by a study that has long since been debunked: the researchers used extremely high voltages with an outdated and incompatible atomizer (5V with a CE4 tank...I know, right?), leading to the burning of the wick. The result of this was proclaimed to prove that combustion resultants were also present in everyday e-vapor. However, any vaper worth their salt will tell you that voltages such as those used in the study will immediately lead to a dry hit, which is undoubtedly what the researchers witnessed and recorded. The takeaway? Avoid dry hits (so...just keep doing what you’re doing).
- Is secondhand vapor dangerous?
Not according to current scientific studies. Two separate studies by Lolliard and the NCBI both found that secondhand vape is no more dangerous than ambient air.
- I heard that e-liquid production isn’t even regulated. Does that mean I’ll never really know what I’m getting in my e-liquid?
Mostly a definite no, but it depends on where you source your e-liquid. While amateur e-liquid is relatively common (not to mention easy), companies who mass-produced e-liquids have been self-regulated for a long time, creating several independent organizations devoted to maintaining standards in e-liquid manufacturing facilities all over the country. These groups definitely do their job, but even without them, companies are extremely stringent in their production process, often using pharmaceutical grade mixing environments (ISO-7 clean labs, multi-level sterilization, etc.) and put their reputation on the line so you always know that you’re getting the highest quality e-liquid possible. However, this only goes for US-based e-liquids—internationally sourced liquids aren’t necessarily subject to the same regulation, but what’s good for the goose is good for this gander.
- Does it cause popcorn lung?
Not at all—definitely no more than cigarettes (which don't have any recorded cases either). While as of late, e-liquid manufacturers have done all they can to remove the diacetyl/diketones that are reported to cause popcorn lung (mostly in buttery/custard flavors), it’s impossible to remove ALL of it, as diacetyl is a natural result of the degradation of nicotine as it ages. However, these levels are FAR lower than in cigarette smoke (daily exposure of 9 micrograms in e-liquid vs 6718 micrograms in cigarettes), and research, even the original study vilifying diacetyl, hasn’t been able to prove that e-cigarettes or even cigarettes can cause popcorn lung.