With the popularity of CBD e-liquids growing more and more there has been some debate as to whether one of the key ingredients in a majority of CBD liquids, i.e Propylene glycol (PG), is safe for consumption. While the debate is still active there have been many discussions regarding the safety of PG and we're here to provide some more information so you can make an educated decision for yourself.
Propylene glycol is a synthetic organic compound with the chemical formula C3H8O2 and is colorless, clear, and practically odorless. PG can be found in everything from pharmaceuticals to food, cosmetics, and even anti-freeze. But wait! Anti-freeze.. that can't be safe for human consumption. The most logical way to view this concern is to take into consideration that just because PG is present in something such as anti-freeze does not mean it can be considered a dangerous substance off the bat. PG is primarily used in e-liquids because it makes for a great solvent, meaning substances can easily dissolve in it (including CBD!).
There have been several studies on PG inhalation in rats ranging from 4 days to 90+ days, there is also a study that looked at the effect on dogs over the course of 9 months. The results of these studies show that PG does not post a significant threat to animals when inhaled, however, there were some instances which could spark concern. Specifically, rats have sensitive eyes and nostrils, and the irritation from PG led to nosebleeds in one of the studies. There were also small changes in hemoglobin and red blood cell levels in the dogs with the most exposure, in these cases though their levels were still within normal range throughout the duration of the study. Another study examined the effects of PG in high concentration in monkeys and rats. After 18 months their organs were examined and there was no apparent effect of PG. An even more detailed look at their lungs showed no signs of irritation. Simply, based on the studies cited, animal studies show no risk associated with PG inhalation.
While long-term evidence isn’t available, there are studies that address human inhalation of PG specifically via e-liquid. There are other factors at work in these studies too (e.g. flavorings, nicotine and contaminants), but PG always plays a key role.
In general, the studies on vaping agree with what you’d expect based on the existing research on PG. In cell and animal studies, the main short-term effect of PG-based vapor is inflammation. People enrolled in quitting studies often get coughs and dry mouth (as many vapers will have experienced themselves). These usually fade with time. Cell studies show inflammation and some cell death, but the toxic effect of vapor on cells appears to be more related to chemicals other than either PG or VG. Based on what we know, inhaling PG through vaping is just going to be the same as inhaling it any other way.
The evidence on PG is pretty encouraging. Animals seem to tolerate it well, and the effects seen so far in vapers and humans exposed in other situations are mild. Also, most vapers also won’t exceed existing workplace maximums (the limits of exposure established for workplaces regarding various chemicals) for PG exposure. In short, the risk isn’t likely to be particularly big at all. We encourage you to continue staying up to date with the latest studies and use this information to make your own decision regarding the use to e-liquids containing PG, just know that we at The CBD Plug and Green House put our customers' health and safety at the top of our priority list.
All statements above are for scientific reference and is not intended to help treat or cure any disease. These statements have not been assessed by the FDA, although the FDA and CDC reference that PG is safe for oral consumption.