Propylene Glycol in E-Cigarettes - Is PG Dangerous to Inhale?
Propylene Glycol (PG) is not dangerous when inhaling in e-cigarettes. PG has been used in many of the most popular foods we eat every day and has been deemed safe by the FDA for decades. A very small number of people may have an allergy to propylene glycol which could cause an allergic reaction. If you have a PG allergy, you may experience light symptoms.
As smokers we are used to inhaling chemicals into our lungs we have no idea about. For many smokers it’s a shock to find out there are over 4000 different chemicals in a single cigarette, including arsenic, cyanide and more. After all as a smoker one of the first things you learn to do is ignore the warnings on the box about your lung health or the chance of lung disease, just to mention one of the many dangers of smoking.
One of the great things about electronic cigarettes then is that there are only 4 ingredients that you are breathing in, with one of them being Propylene Glycol. Unless you have a chemistry degree though you probably don’t know what Propylene Glycol is, and what it does to you.
Today then we are looking into what is Propylene Glycol, what it’s used for and if it is harmful.
WHAT IS PROPYLENE GLYCOL?
Propylene Glycol (PG), is an ingredient that has been around long before electronic cigarettes. If you saw it on it’s own all you would see is an odourless, colourless liquid which in consistency is viscous like honey. It has a slightly sweet flavour and has a neat ability to keep moisture as well.
WHAT IS PROPYLENE GLYCOL USED FOR?
Propylene Glycol has been a common ingredient for years, and can be found in everything from medicine, to food and personal hygiene products. Historically PG has been used as a food additive, in fact some of your favourite food and drink probably has Propylene Glycol in! Everything from ice cream to soft drinks has PG added to it to sweeten the food and make it last longer.
But it’s not just that tub of vanilla ice cream that has been improved by Propylene Glycol, injectable medications, topical creams, and other personal hygiene products all include PG it as well. In the case of all the personal hygiene products and medication Propylene Glycol isn’t added for the flavour, rather because it’s an excellent solvent (things can be dissolved in it), it attracts water, and it has low toxicity and low vapour pressure.
The last use of Propylene Glycol though is perhaps its most common use now, and that is in electronic cigarettes.
WHY IS PROPYLENE GLYCOL USED IN E-CIGS?
Propylene Glycol gets added to electronic cigarettes for a couple of reasons, as a thickening agent, a good solvent to hold the nicotine in and as it is odourless.
The first is pretty obvious, it is used with the other main ingredient in electronic cigarettes, vegetable glycerine (VG) as thickening agent and to hold the flavouring and nicotine in. The PG works well to keep the ingredients of the e-liquid mixed together. Put together PG and VG are great at this job as they vaporise easily and are able to dissolve other substances quickly as well. By adding Propylene Glycol into the mix vape juice makers can thicken the liquid up to where it can be used by electronic cigarettes.
The other benefit of Propylene Glycol is that it is odourless. Unlike other options it doesn’t smell, which is a big deal when talking about a liquid you are going vapourise and put into the air around you!
IS PROPYLENE GLYCOL HARMFUL?
You might have seen stories about E-Cigarettes that say that they are just as bad, or worse, than cigarettes. However E-Cigarettes in general are at least 95% less harmful than cigarettes according to Public Health England! This is based on UK regulated E-Cigarettes, that ban ingredients known to be harmful when inhaled, like diacetyl that is linked to the condition 'popcorn lung'.
That doesn’t stop some people though, and as one of only 4 ingredients in electronic cigarettes Propylene Glycol has generated a lot of myths about how it can harm you.
But you don’t have to believe us when we say that Propylene Glycol is safe , the MHRA and the United State’s FDA approved the use of Propylene Glycol for food and medicine years ago. If it wasn’t safe Propylene Glycol would never have been allowed in your ice cream.
Like anything else you shouldn’t consume it in huge quantities, but unless you are drinking Propylene Glycol that is very unlikely!
IS PROPYLENE GLYCOL TOXIC?
One of the biggest myths is that Propylene Glycol is antifreeze and so therefore it is toxic.
Though this is rooted in fact, the truth has been twisted to sell headlines! Propylene Glycol is included in some antifreeze, however it is not the toxic part of antifreeze, instead it is used along with the toxic ingredients as it is great at dissolving substances together.
In fact the main reason that Propylene Glycol is added to some antifreeze is to make a much less toxic version, as Propylene Glycol is safe compared to the other chemicals that are normally used in antifreeze.
Think of it this way, water gets added to some antifreeze, but that doesn’t make water toxic.
PROPYLENE GLYCOL IS A WIDELY USED SUBSTANCE
As we mentioned before, Propylene Glycol is in thousands of different products ranging from food additives to personal hygiene products and pharmaceuticals.
To give a quick list:
Make-up, shampoo and baby wipes
This is just a small list, but as you can see Propylene Glycol is everywhere, and the reason that it is in so many products is that it has been proven to be safe to eat and use.
HOW MUCH PROPYLENE GLYCOL IS INHALED WHEN VAPING?
Trying to figure out exactly how much Propylene Glycol you are absorbing is extremely difficult, as each vape juice is different. Not only are the propylene glycol and vegetable glycerine levels different between brands but the nicotine levels are too. This isn’t even mentioning how different hardware will affect this as well.
There is one study that might help though. In 2014 a scientist called Burstyn tried to compare the vapour from e-cigarettes to what was considered safe by workplace standards so used the US Threshold Limit Value (TLV) which is 10 mg per cubic metre for any chemical in the air.
The study found that after a full day the PG absorbed could reach 1–6 mg/m, which is just below the maximum safe amount.
This sounds a little worrying, however the amount of e-liquid he vapourised was MASSIVE. His range was from 5 to 25 ml/day with a 50–95 percent propylene glycol in the liquid. To put that in perspective, 1 SMOKO E-Cigarette refill has 1ml of liquid inside, and a 95% PG liquid is almost unheard of.
That would mean in 1 day someone would have to use at least 5 refills which is 750 cigarettes worth of nicotine. This could result in a lot of throat irritation and coughing.
The amount is absurd, but it does show that even if you used the electronic cigarette like crazy, you wouldn’t even get near the safety limit on Propylene Glycol.
As a very rough number then, if you were to take the 1mg/m of Propylene Glycol that was produced in the study and divide it by 5 (as most people go through 1 refill a day) you would get closer to how much Propylene Glycol you inhale when using the vape juice for a full day.
THINGS USERS NEED TO BE AWARE ABOUT PROPYLENE GLYCOL
Although Propylene Glycol has been around for years and proven to be safe, a few cases of allergies have been recorded, but it is extremely rare to find. If you do start getting rashes after you started vaping vape juice then we would recommend moving to a high vg e-liquid instead.
The most common side effects of vaping with PG will normally be it drying out your mouth and giving you a sore throat. This is because Propylene Glycol is great at absorbing moisture.
Most people who started vaping won’t notice any side effects, but if you do then we would suggest drinking more water than usual for the first few weeks of using your electronic cigarette. That way you can give your body time to adjust (and drinking more water is good for you anyway)!
SHOULD BYSTANDERS BE WORRIED?
One of the great benefits of E-Cigarettes is that not only are they 95% less harmful to you, there is no effect on the people around you.
In fact Public Health England, the UK government body which focuses on national health issues, has said that to date there is no evidence whatsoever that 2nd hand vapour is harmful.
The NHS also states on their website that vapour is nothing to worry about, unlike 2nd hand smoke which can have a huge effect on people who breathe it in.
But what about Propylene Glycol? As a part of the E-cigarette vapour what Public Health England and the NHS still applies but especially in the case of PG. There have been studies on the effect of PG on it’s own and multiple studies have shown that it does nothing!
LAB TRIALS AND EXPERIMENTS DONE ON PROPYLENE GLYCOL
As electronic cigarettes haven’t been around for long there haven’t been any long term studies on what Propylene Glycol in e-cigarettes does to people over years of use, however there are a few studies that focused on Propylene Glycol which can be useful.
Most studies are pretty old as they were testing Propylene Glycol to see if it was safe to use in food and personal hygiene products, but they still show that Propylene Glycol is safe to use.
The first of our studies tested Propylene Glycol on animals, including rats and dogs. The studies pumped PG into the animal’s pens and were of varying lengths, from just a few days to over 3 months. When the scientists looked at the lungs (focusing on the epithelial cells) they found that that was “minimal” change, even in the rats that had been exposed to high levels.
This was shown again with the study on the dogs, they did find that there was a slight difference in the blood cells of the dogs who had been exposed to the highest levels of PG, but it was still classified as within normal range.
Finally, an ultra focused examination of the animals’ organs for any abnormalities or lung inflammation showed no differences between those inhaling PG and air.
But what about for longer than 3 months? For this we have to look at another study, and this time the scientists moved up the evolutionary tree and looked at the effect of high concentrations of PG on monkeys and rats.
The monkeys inhaled saturated PG vapour for between 12 and 18 months, and then were examined in close detail to see what had changed. The scientists focused on kidney, blood and lung health.
After the year and a half was up the monkey’s organs were examined and there was no effect from the PG. A detailed look at their lung function found no sign of lung inflammation from breathing the vapour.
The only major findings were that the female rats gained weight, and the monkey’s faces got dryer.
Simply put then, all the animal studies showed there was no risk from inhaling PG, even in high concentrations.
These studies and more are the reason that the FDA in the USA marked PG as “generally recognized as safe” in 1973 and has kept that designation for the last 47 years,
That is all well and good for monkeys and rats, but what about humans?
As we said at the beginning there haven’t been any long term studies on the side effects of PG from E-Cigarettes, simply because vaping hasn’t been around long.
But as Propylene Glycol is included in medicines there have been a few studies conducted on vapourised PG, all of which supported the animal studies in showing the PG at most is an irritant at worst.
As Propylene Glycol is in medicines and is an anti-bacterial, a few studies have looked into its usefulness in that area. Perhaps the best study was the one performed at a children’s ward. In this study the scientists pumped vaporised PG into the ward to see what effect and side effects there were. After only a few days the PG had reduced infections, and had no reported negative effects.
The best we can do for longer term side effects from Propylene Glycol though are studies on fog machines. Though it might sound odd at first, fog machines use Propylene Glycol to help create the fog, and so the studies on how the vapour made by fog machines effects people is actually pretty useful.
One study looked at over 100 people who worked near fog machines and found very similar results as the animal studies. The actors and technicians who worked closest to the fog machines experienced dry mouths and in a few cases lung inflammation and sore throats.
Another study which focused on 439 actors over 2 years found much the same thing, some experienced dry mouth and for those who were closest to the machine reported inflammation of the vocal cords.
With both of these studies it was found that once the technicians and actors stopped breathing in the fog the symptoms went away.
Because of this the National Institute for Occupational Safety and Health (NIOSH) also looked into this in the 1990s. They agreed with the results from the two studies above and concluded that while PG has no long term side effects to lung health, it can be classed as an irritant if exposed to too much. Of course the amount of vapour made from a fog machine is vastly more than an electronic cigarette!
This is in line with the studies like the workplace one done by Burstyn we mentioned earlier. After all no-one can use an e-cigarette enough to replicate a fog machine, but even if you scaled up the vapour to a fog machine level (which Burstyn almost did), the vapour would still be considered mostly safe and an irritant at most.
INTERACTIONS OF PROPYLENE GLYCOL AND OTHER SUBSTANCES
One of biggest issues with PG that hasn’t been mentioned yet is the link to formaldehyde. While it is true that as a chemical if you heat Propylene Glycol up too high it can turn into formaldehyde, the heat you would need is extreme.
The likelihood of cooking you PG in the e-liquid enough to even begin worrying about this is tiny though, as you would first have to essentially cook your vape juice for much longer than normal, and even if you did that the taste would stop you. Unsurprisingly formaldehyde tastes disgusting!
To put this another way it would be like saying that steak cooked long enough can cause cancer because it can become charcoal. While true anyone who cooks steak long enough for this to happen has done something very wrong.
We have talked about this before but it is yet another reason that when you are buying an E-Cigarette it is better to get a fixed voltage e-cigarette with a low voltage than one that can go up to 20 or 30 volts.
PROPYLENE GLYCOL IN E-CIGARETTES - IS PG DANGEROUS - CONCLUSION
To conclude then, the evidence is pretty encouraging. From all the studies it can be seen that Propylene Glycol doesn’t really affect you.
At worst Propylene Glycol is an irritant that might dry your throat out if you puff away for too long. And even this doesn’t happen to most people, as it is only a minority that even experience this mild effect. If you drink plenty of water for the first few weeks of using your electronic cigarette you will quickly adapt to it and be able to puff away happily.
The only serious side effects it can have are if you buy yourself a huge, extremely powerful vapouriser that can get into voltages that would not be pleasant for even the most hardcore users.
However if you want to make 100% sure that the Propylene Glycol is as safe as it can be, make sure to get a fixed, low voltage device like our E-Cigarette starter kit and there will be no problems.
And this is just comparing Propylene Glycol to fresh air. If we were to start comparing it to cigarette smoke the issues of dry throat would pale in comparison to heart disease, lung disease, strokes, cancer and more.
There are huge benefits to switching from tobacco to e-cigarettes, and as we said once before in the article E-cigarettes (including PG) are at least 95% less harmful than cigarettes. So if you are thinking about making the switch and are worried about Propylene Glycol, make sure you have a glass of water near you and you will be good to go.