Popcorn Lung and Vaping
The relationship between vaping and popcorn lung can seem complicated, with contrasting opinions everywhere you look. In this article, we aim to provide you with a definitive review of the relationship between the two, and the facts behind the myths associated with this topic.
What is Popcorn Lung?
Popcorn lung is the common name for a disease called bronchiolitis obliterans. It’s a currently incurable condition that causes damage to the smallest parts of your lungs, called the bronchioles and alveoli. These parts of your lungs are where oxygen is collected from the air, and carbon dioxide is released from your blood as you breathe. Popcorn lung occurs when scar tissue builds up within these tiny passageways, making it hard to breathe and expel air.
Popcorn lung is a highly destructive condition that is irreversible and extremely damaging to the lung tissue. Symptoms can appear over weeks, or appear very suddenly, including dry cough, wheezing, shortness of breath, and an FEV1 (forced expiratory volume in 1 second) 80% lower than that of an equivalent, unaffected person .
Generally, several tests are required to diagnose popcorn lung. The only way to fully diagnose this condition is by assessing several lung biopsy samples, as chest X-rays and CT scans will come back as normal. This can lead to frequent misdiagnosis of popcorn lung as emphysema, a similar disease more commonly associated with smoking [2,3].
Currently, popcorn lung has no cure and is irreversible. The only treatment for severe cases of popcorn lung is a lung transplant. This is not often a suitable solution, however, as popcorn lung is an inherent risk and side effect of lung transplantation. Early diagnosis and intervention is currently the best and only way to prevent popcorn lung .
What Causes Popcorn Lung?
Generally, popcorn lung is a very rare disorder. It is caused by exposure to toxic fumes that irritate the lung tissue, or following a lung transplant, due to the development of scar tissue. Up to 75% of people who have had a lung transplant will develop popcorn lung as their body struggles to accept the new organ .
Notable to vapers, and a leading cause of popcorn lung, is diacetyl. A buttery-tasting flavouring, diacetyl is added to foods such as popcorn, and is found naturally at low levels in dairy, beer, and fruits. It is widely considered safe to consume and is FDA-approved. As a food-grade flavouring, diacetyl is used to create popcorn flavour e-juice for e-cigarettes. There was very little concern for the use of diacetyl as a food or e-juice flavouring, until a damning report showed that workers in a microwave popcorn factory who were inhaling large volumes of diacetyl powder developed serious cases of popcorn lung .
Inhaling large quantities of diacetyl powder caused an incredibly damaging and dramatic effect to these individuals over a very short period of time, which was shocking due to the current scientific opinion that diacetyl was not harmful to humans. Small volumes of diacetyl are used in many popular e-juice flavourings, leading to media claims that vaping was particularly dangerous and could lead to popcorn lung.
Although there are several ways that we can dismiss these claims as jumping to conclusions, the vaping community also has a lot to learn from this story. The lack of concrete evidence on either side of the popcorn lung/vaping debate highlights a controversial issue surrounding e-cigarette use – that food-grade flavourings do not require any further research to be used in e-juices. Digestion of food involves acid breakdown, enzyme attack, and kidney and liver processing, whereas vapor by the lungs goes directly in the bloodstream. This means we do not really know the effects that inhaled flavourings are having on our lungs and body.
Popcorn lung remains a popular topic amongst vapers. Let’s take a look at some of the facts it in the next section.
Vaping and Popcorn Lung
Following the disastrous cases of popcorn lung in factory workers, the U.S. National Institute for Occupational Safety and Health proposed a safe short term exposure limit to diacetyl of 25 parts per billion (ppb), and long term exposure of 5 ppb (eight hours per day) . In a popcorn-flavoured e-juice, the user can expect to inhale vapour containing roughly 90 ppb of diacetyl . The safe exposure limits mentioned above are designed for workers experiencing constant inhalation of diacetyl through the act of breathing, with indefinite occupational exposure. So take these exposure limits with a pinch of salt – they may be highly conservative when compared to vaping, where individual puffs are taken frequently, but not for every breath. The workers that initially developed popcorn lung were exposed to around 370 ppb diacetyl for several hours, every day .
Second-hand exposure to diacetyl seems to be less of a concern. An unnamed American vape shop tested areas where staff experienced high levels of second-hand vapour following concerns about diacetyl exposure, and results showed levels were far below safe exposure limits, at 0.3 ppb .
Another important fact to consider is that the diacetyl content in tobacco smoke is around 750 times higher than in e-juice. There is, on average, 335 micrograms of diacetyl per cigarette, compared to 9 micrograms of diacetyl in an entire 2ml e-cigarette cartridge [7, 8]. So if you rely on vaping as a way to quit smoking, you will be exposing yourself to far lower levels of diacetyl than if you continued to smoke.
The American Lung Association strongly opposes diacetyl use in e-juice, and states that vaping with diacetyl will cause popcorn lung . This statement is at best unfounded, and at worst, based on uneducated assumption and shock-value media reports. Considering the high diacetyl levels found in tobacco, it is interesting to find that there have been no reported cases of popcorn lung caused by smoking or vaping. This suggests that the level of diacetyl found in tobacco could just not be high enough to cause popcorn lung. On the other hand, popcorn lung is so hard to diagnose, it may be going undiagnosed in a proportion of smokers, and symptoms put down to other smoking-related diseases like COPD .
Prevention in Vaping
Preventing any risk of popcorn lung is very simple. If you want to continue vaping and want to reduce the risks associated with popcorn lung, check the diacetyl (and aldehyde) content in your e-juice before you purchase. Reliable e-juice suppliers will display the diacetyl content of their flavourings, so you can buy diacetyl-free or low-diacetyl e-juices. Other preventative measures include reducing your occupational exposure to harmful fumes.
Popcorn lung is a proven occupational risk of working and inhaling with high levels of toxic fumes and powders, that has been causally linked to vaping. At the moment, the risks of getting popcorn lung from vaping seem limited, but not to be ignored. Vaping with diacetyl-containing e-juices has not yet been proven to cause, or be safe from causing popcorn lung. If you are a heavy vaper, we would recommend choosing diacetyl-free e-juices, until more research can confirm the relationship between diacetyl in e-juices and popcorn lung. Going diacetyl-free is the easiest way to reduce your risk and continue vaping. The difficulty in diagnosing this condition could be an alternative explanation as to why we see it so rarely in smokers. Until there is more evidence, we suggest to always check the dose of diacetyl in your e-juice.
1. Centers for Disease Control and Prevention (2002). Fixed obstructive lung disease in workers at a microwave popcorn factory (7th ed.). [accessed 20/10/18] 2. The National Institute for Occupational Safety and Health (NIOSH) information on FLAVORINGS-RELATED LUNG DISEASE. [accessed 20/10/2018] https://www.cdc.gov/niosh/topics/flavorings
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A proposal for a safe exposure level for diacetyl
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8. Allen JG, Flanigan SS, LeBlanc M, Vallarino J, MacNaughton P, Stewart JH, Christiani DC. 2016. Flavoring chemicals in e-cigarettes: diacetyl, 2,3-pentanedione, and acetoin in a sample of 51 products, including fruit-, candy-, and cocktail-flavored e-cigarettes. Environ Health Perspect 124:733–739; [accessed 20/10/18]
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1. Yale Rosen, Cryptogenic organizing pneumonia (COP)-bronchiolitis obliterans.
2. Mbq, CT slide of biopsy-proven bronchiolitis obliterans organizing pneumonia, taken in Oct. 2010