Key Takeaways
- Lipoid pneumonia is a rare condition caused by the inhalation of lipids which is getting more common since people started vaping.
- Vegetable glycerin (VG) and propylene glycol (PG) are alcohols, not lipids, and so cannot cause lipoid pneumonia.
- Despite the name, cannabis oils that have been winterized or dewaxed also cannot cause lipoid pneumonia.
- Both types of vape can be contaminated with lipids and cause lipoid pneumonia as a result. However, lipids are soluble in cannabis oil but not in PG and VG, which makes the latter a slightly safer choice.
- MCT does contain lipids and should never be vaped.
The EVALI outbreak was a big wake-up call about the danger of inhaling lipids, leading to 68 deaths and 2,800 people hospitalized.
EVALI was caused by vitamin E acetate, and while this specific lipid has been rightfully removed from inhalable products, there is still a lot of confusion about what is safe and what is not safe to vape.
Should you be worried about CBD vapes with vegetable glycerin? Is it safe to vape cannabis oils?
We looked into the evidence and spoke to vaping expert, prolific researcher, and physician Dr. Konstantinos Farsalinos to find out what could be dangerous and what isn’t.
What Is Lipoid Pneumonia? The Basics
Lipoid pneumonia is a rare lung condition that usually results from inhaling lipids.
When fats and oils are inhaled and not stopped by a cough reflex, they reach the macrophages in the alveoli but cannot be metabolized, which means they stay there and build up over time.
There are technically two types of lipoid pneumonia:
- Exogenous lipoid pneumonia: Caused by inhalation or aspiration (accidentally inhaling food or liquid instead of swallowing) of lipids.
- Endogenous lipoid pneumonia: Caused by fat and cholesterol being released from the body in response to tissue damage.
For this discussion, the focus is on exogenous lipoid pneumonia. This used to mainly be a risk for children and old people, who would receive mineral oil as a treatment for constipation, and people with neurological conditions causing issues with swallowing (so they may accidentally aspirate).
However, the rise of vaping has made this a more common and pressing issue in the modern day.
Treatment of lipoid pneumonia is unfortunately not standardized, and while there is some suggestion that corticosteroids are effective, more research is needed.
Ultimately most cases are managed as well as possible and people are instructed to stop doing whatever it is that caused them to inhale the lipids.
Cases of Lipoid Pneumonia, Including Some (Supposedly) Caused by Vaping
Research into lipoid pneumonia is fairly limited, but many case reports give an indication of potential sources of risk.
Lipoid Pneumonia from Mineral Oil Constipation Treatment
One case study describes a more typical case prior to the advent of vaping.
A 72-year-old woman with a history of asthma went to the hospital with a (sometimes bloody) cough and shortness of breath. Doctors found no evidence of bacteria, fungi, or other pathogens, but noted lipid-laden macrophages after a lung biopsy.
She later admitted that she took mineral oil every day as a treatment for constipation, and they determined that the reflux of this oil was the cause of the condition. She got better after stopping using the oil. There have also been similar issues associated with “oil pulling” and nasogastric lipid feedings.
Lipoid Pneumonia from Cannabis Oil Vaping
There are many cases of lipoid pneumonia that seem to be caused by cannabis oil vaping.
One example published back in 2000 involved a woman who vaped weed oil between two to ten times per day for ten years, where cannabinoids were extracted and then mixed with petroleum jelly, vitamin E, or other oil-based substances for vaping.
Another case from 2017 (a little before the EVALI outbreak) was judged to be caused by the patient’s vaping, which he described as “pure cannabis oil” extracted with CO2 and without additives.
One paper described 5 other cases and another goes into detail about a previously-healthy 28-year-old who developed lipoid pneumonia after using street-bought THC vape cartridges.
Lipoid Pneumonia from Nicotine Vaping
There are also many cases of lipoid pneumonia that have been linked to nicotine vaping, particularly with vegetable glycerin (VG) which is a near-universal component of e-liquid.
One example from 2018 involved a 34-year-old who complained about shortness of breath and a persistent cough. Upon finding the characteristic lipid-laden marcophages, doctors settled on the VG in her e-cigarette as the likely cause.
Despite the advice of doctors, she continued vaping with VG except using different flavors, and with treatment, she started to improve.
There are other cases supposedly linked to nicotine vaping too.
What’s in Your Vape? An Overview of the Suspects
These cases raise concern about vaping in general, and in particular, suggest that vapes either containing VG or with some kind of cannabis oil are dangerous.
However, the true situation is not quite as simple as many of these researchers have assumed.
Can VG Cause Lipoid Pneumonia?
When we spoke to Dr. Farsalinos, a world-renowned expert on vaping with an extensive selection of published papers on the topic, he was very clear about the suggestions that VG could be responsible:
There is no scientific basis in any claim that VG causes lipoid pneumonia. It is very simple: lipoid pneumonia, as the name suggests, refers to inflammation caused by inhalation of lipids. VG is an alcohol (a polyol, meaning it has 2 OH groups). Therefore, it is scientifically impossible for VG to cause lipoid pneumonia. The only way it could be implicated is if there is contamination with lipids.
In short, VG itself cannot be a cause of lipoid pneumonia.
Vegetable glycerin is more properly called glycerol (with “vegetable” simply referring to the original source), and this is an alcohol, not a lipid.
The authors of the case study referenced above note that it is a polyol, but also point out that it is extracted from palm, soy, or coconut oils triglycerides, and that they were not able to determine which flavorings were present in the e-cigarette used by the patient.
We’ll come back to these issues shortly, but for now, it is clear that VG, in itself, cannot be a cause of lipoid pneumonia.
Can Cannabis Oil Cause Lipoid Pneumonia?
But what about the many cases involving cannabis oil? If this is “oil,” doesn’t this mean the risk is there too?
Dr. Farsalinos pointed out that oil in this case is a slightly misleading term, “As for CBD oils, despite [being] usually called oils, they are not lipids. Thus, they cannot cause lipoid pneumonia, unless again they are contaminated with lipids.”
Terpenes are technically non-saponifiable lipids, and don’t contain fatty acids like more typical lipids do. They are made from isoprene units, and being “non-saponifiable” means that they can’t be broken down by the process used to make glycerol from fats.
As Dr. Farsalinos points out, this means terpenes can’t cause lipoid pneumonia on their own, and any cases involving them are likely due to contamination.
In fact, the processes of dewaxing and winterization are intended to remove lipids from cannabis oils. The amount of plant lipids in a raw extract depends on the extraction method used, but in any case, they should be removed via winterization or dewaxing for any products that are intended to be inhaled. Removing the fats and waxes is generally preferable anyway because they can negatively impact the flavor of the extract.
Can MCT Oil Cause Lipoid Pneumonia?
While most products intended to be vaped don’t use MCT oil, it does happen, and in this case, there is a genuine risk of lipoid pneumonia.
Dr. Farsalinos was clear on this point:
MCT oil is medium chain triglycerides. They should not be inhaled.
MCT oil has been directly linked to lipoid pneumonia in case studies. In the cases discussed in the paper, three infants were being fed coconut oil, which is a common way to treat low weight gain in countries such as the Philippines.
Vaping any products with MCT oil is clearly dangerous, since these cases involved aspiration (accidental inhalation during feeding), while vaping is intentional inhalation and would undoubtedly result in higher exposure.
So Why Are There Cases of Lipoid Pneumonia in Vapers Using VG or Cannabis Oil?
All of this raises many questions about the vaping cases cited above. If VG and cannabis oil are not able to cause lipoid pneumonia in their pure form, how did the patients in those cases get sick?
The big issue is contamination. As Dr. Farsalinos pointed out in both responses, the only way these cases could have occurred is if the products in question actually did contain lipids.
There are many ways this could happen. For the cases with nicotine vapes, usually just containing nicotine, propylene glycol (PG, another alcohol), VG, and flavorings, there are two potential causes.
The most obvious is flavorings added to the liquid, which in some cases are dissolved in (true) oils, but these are generally not used for e-liquids for exactly this reason. However, it’s possible that either homemade e-liquids or those made by less-informed manufacturers do use oil-based flavorings.
While less likely, given that VG is produced by the saponification of fats, it is also possible that impure VG could contain some residual lipids. However, most companies use pharmaceutical-grade VG, which is always over 99% pure (usually more like 99.9%) and will not contain lipids.
The same issue applies to cannabis oil. Winterization and dewaxing are needed to remove the fats present in the plant extract, and if this process is not done or is not done well enough, some lipids may remain in the final product.
In the case from 2000, for example, the description makes it sound like she used home-made cannabis oil, and this likely means the oil wasn’t dewaxed properly and that was the source of the lipids she inhaled.
Contamination Is Usually the Issue, But Where Is It More Likely?
Unfortunately for cannabinoid vapers, contamination is more likely to go unnoticed in cannabis oils than it is in nicotine or VG-based vapes.
Dr. Farsalinos explained, “It is far easier to adulterate CBD or hemp oils with lipids because they are lipid-soluble. Thus, they mix easily. In contrast, it is quite hard to mix lipids with nicotine e-liquids because they are water soluble.”
He used the EVALI outbreak as an example of the problem:
“The whole situation with EVALI, if you remember, was the adulteration of THC oils with vitamin E acetate. Vitamin E acetate is lipid soluble and hydrophobic. It cannot be used to adulterate nicotine e-liquids because it will separate within minutes (think of it like adding water in a bottle with vegetable oil).”
So the advantage of VG (and PG) over cannabis oils as a base for vaping is that if there is contamination, it will be much more obvious before you start to vape it.
This isn’t to say contamination is likely, especially if you buy from reputable companies, but it is always possible.
If there is lipid contamination with VG and PG, it will separate like oil and water and you’ll see it; if there’s lipid contamination with cannabis oils, it will mix and likely not be visible.
Also, as in the EVALI outbreak, any danger is likely to come from unregulated products, especially those bought from dealers or private sellers rather than in a store.
With more oversight and higher-quality manufacturing, lipoid pneumonia is not likely with either form of vaping.
The only thing you should never buy, regardless of the source, is any vaping product that uses MCT oil as a base, or obviously anything with vitamin E acetate.
Bottom Line: How to Vape Cannabinoids as Safely as Possible
Almost nothing is risk-free. But if you’re interested in minimizing the risk when you vape cannabinoids, the safest and most fool-proof approach is to stick to products that use PG and VG as a base, and if not, vaping cannabis oil from a reputable manufacturer with third-party lab testing is unlikely to be risky either.
We probably won’t have another EVALI, but now you understand the basics, staying safe is pretty easy regardless of what’s going on.
References
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