The following three words form a kind of ominous trio: e-cigarettes – diacetyl – popcorn lungs. We would like to anticipate that in this article we are only comparing the latest findings with critical studies in order to take away the uncertainty of many vapers. Many e-cigarette users are tired of the myth of a connection between these three terms, while others remain confused. Because on December 9th, 2015, Stern.de published an article “Dangerous chemicals found in e-cigarettes”. On December 11, 2015, BILD followed suit and published the article “E-cigarettes give you popcorn lungs”. The papers were reacting to a study by Harvard researchers, which led to the conclusion that vaping e-cigarette liquids could lead to popcorn lung (bronchitis obliterans) due to the diacetyl it allegedly contained. And this despite the fact that the study published by the Harvard School of Public Health uses the subjunctive throughout and there is no proven connection between diacetyl and the respiratory disease.
The problem is not the study, but the reporting
There is nothing left of this in the response of the media landscape to the study. From then on, the buzzwords were “toxic” or “seriously hazardous to health”. On the one hand, this ignores the fact that out of 7,000 liquids available in the USA, only 51 were tested and, on the other hand, that 33 of the 51 tested liquids were completely free of diacetyl or only minimally contaminated with approx. 2.3 micrograms (µg). And that was foreseeable, since no diacetyl should actually be found in high-quality liquids. Most European manufacturers have been doing without it for a long time. The remaining 18 liquids had an average content of around 9 µg. Now it is a matter of understanding whether this value is at all hazardous to health and then putting it in relation. Basically, the media coverage unjustifiably challenges the statement that the mist produced by vaping is significantly less harmful than the tobacco smoke of a conventional cigarette. But why, when the amount of diacetyl contained in a tobacco cigarette is 750 times greater than that in the 18 (out of 51) e-liquids tested? Just one of many inconsistencies and confusions that the study brings with it. This fact was revealed by a differentiated analysis of the Harvard study by Prof. Michael Siegel from Boston University on Health. A quote from a scientist on the subject is also very informative. With this statement, Prof. Jean-Francois Etter from the University of Geneva comments on the prospects if people believe such well-directed but poorly researched reporting.
We do not wish to present this quote as fact here. However, it shows very well how sharply respected scientists criticize the claims about a connection between vaping and popcorn lung.
What is a popcorn lung anyway?
The first thing that strikes you is that the increasing awareness of the term “popcorn lung” is closely linked to the increasing popularity of e-cigarettes. But the term actually comes from a completely different context, as the name suggests: the production of microwave popcorn. Because this contains diacetyl, the organic chemical compound of ketones and diketones, which results in an intense taste and smell of butter and is part of the natural butter aroma. Therefore, it is naturally used for popcorn production. When it was discovered around 2005 that workers in microwave popcorn factories were suffering from bronchiolitis obliterans (BO), the real name of the “popcorn lung”, it was given the name “Popcorn Worker’s Lung”. We will clarify later whether this is justified. The colloquial term for the respiratory disease has very little to do with the vapor of electronic cigarettes. But despite the rather funny name, it is a very serious disease. This leads to permanent inflammation of the bronchi, with no prospect of complete healing. The consequences are severe breathing problems, rarely even respiratory arrest. It is all the more fatal that critics and scientists take advantage of this serious illness to give the use of e-cigarettes an unjustified bland aftertaste. Because neither do all liquids contain diacetyl at all, nor is the concentration in those that contain it hazardous to health.
E-cigarette & tobacco cigarette – the comparison
As already mentioned, by no means all liquids contain the butter flavor diacetyl, while those that do contain an average of 9 µg. Is this value now dangerous? Only a comparison between e-cigarette vapor and tobacco cigarette smoke can make this clear. Because the butter flavor is also contained in conventional cigarettes. We already mentioned that the concentration in a single tobacco cigarette is around 750 times higher than in some liquids at approx. 301 to 433 µg. In figures, this means that a smoker who consumes a pack of cigarettes per day consumes 6020 to 8660 µg of diacetyl. When consuming an average daily amount of liquid, you only consume about 9 µg, provided that the liquid used contains the aroma at all. The most polluted liquid tested as part of the study was the flavor “peach schnapps” with a content of approx. 230 µg. Even that is still relatively little compared to tobacco cigarettes. The first question that arises is why more smokers don’t get popcorn lung disease, even though the concentration is many times higher.
The answer is actually quite simple: because according to the latest scientific knowledge, there is no connection between the amounts of diacetyl found in some e-liquids and the onset of bronchiolitis obliterans! Incidentally, this also refers to the suspected connections between the production of microwave popcorn and the sick workers and tobacco cigarettes. According to these findings, even the liquid that is by far the most “polluted” with 230 micrograms does not pose a direct risk to health.
What are “too high” doses of diacetyl and do they inevitably lead to popcorn lung?
According to a well summarized and well-founded analysis and opinion on the Harvard study, it is 2,864 µg from which the risk of developing popcorn lung is increased. This value is based on an analysis and calculation of the lowest value to which a popcorn factory worker with confirmed BO was exposed.
Example relevant to the topic: A smoker who has switched to smoking and previously inhaled the smoke from a pack of around 20 cigarettes per day absorbed around 6,020 to 8,660 µg of diacetyl per day. As an e-cigarette user, this value is reduced to around 9 µg per day. And this value comes from the official Harvard study. The former smoker and today’s vaper now takes in up to 962 times less diacetyl per day than before. The average value of 9 µg per liquid determined in the study by Joseph G. Allen and colleagues is certainly not what could be described as a “risk factor”.
Since we now know that a smoker absorbs around 6,020 to 8,660 micrograms of diacetyl per day and the lowest value for a sick person was around 2,900 micrograms, the question arises whether smokers shouldn’t be more afraid of popcorn – lung disease. No, they shouldn’t.
This is proven by a study and analysis of the connections between diacetyl, acetylpropionyl and BO. The researchers found no connection between the ingredients and the disease.
Another study even goes so far as to question or rule out the original connections between microwave popcorn and BO. This is the study “Evaluation of pulmonary function within a cohort of flavorings workers”. Another study from 2014 by B. Starek-Swiechowicz and A. Starek sees diacetyl as one of many possible factors for the outbreak of BO. However, not at the concentrations detected and generally not in the form of processed products.
All in all, one can finally say that the partially determined diacetyl concentration is far too low to pose a danger to vapers. For European users there is the additional security that most manufacturers do not use diacetyl or related substances. There is a long list of serious possible diseases associated with tobacco. But despite the 750-fold concentration of diacetyl, popcorn lungs are nowhere on this list either. Could this fact be a reference to the sponsors of the Harvard study? Of course we cannot and will not answer that for you.