Monday, June 10, 2013

German Cancer Research Center Corrects Inaccurate Statement About Glycerine Causing Lipoid Pneumonia

In response to my blog post revealing an inaccurate statement in the German Cancer Research Center's report on electronic cigarettes, the Center has corrected the statement.

The original statement was: "Glycerine may cause lipoid pneumonia on inhalation." As I pointed out, this is not possible, because glycerine is an alcohol and lipoid pneumonia is associated with the aspiration of oils.

In response, the Center corrected this statement in its online version of the report to read: "Inhaled glycerine-based oils may cause lipoid pneumonia."

The Center also let me know that the incorrect statement was a mistake, rather than a deliberate attempt to mislead readers.

The Rest of the Story

I applaud the German Cancer Research Center for correcting this inaccurate statement. As I pointed out, the statement was particularly damaging, because it gave the impression that glycerin, which is widely used in almost every brand of electronic cigarettes, can potentially cause this serious adverse outcome. The effect could have been to discourage smokers from trying electronic cigarettes and potentially, to encourage governments to ban the product. So I thank the German Cancer Research Center for correcting this important mistake.

However, there is still a problem with the Center's conclusion, in my opinion. I simply do not think that a single case report is enough to justify a conclusion that electronic cigarettes pose any significant risk of lipoid pneumonia, especially when even this single case report was unable to document that the case was attributable to the use of an electronic cigarette.

To be very clear, I have no problem with the Center stating that there was a published case report in which the authors attributed a case of lipoid pneumonia to the use of an electronic cigarette. However, the report goes beyond this. It also includes a bullet point - which is essentially a summary or conclusion statement - that asserts to readers that electronic cigarettes can cause lipoid pneumonia because of the presence of "glycerine-based oils."

First, I believe it is misleading to use the term "glycerine-based" oils. By including the term "glycerine," I'm afraid that many readers will misinterpret the assertion to mean that glycerine itself may cause lipoid pneumonia. Why even include the word "glycerine"? Almost all oils are "glycerine-based" so the term is redundant and unnecessary. It creates confusion between the real potential cause - the possible presence of oils in some electronic cigarette brands - and the substance present in almost all electronic cigarettes which does not cause lipoid pneumonia: glycerine.

Second, I do not believe this conclusion is scientifically justified. It is based on just a single case report and if you carefully consider the details of the case report, it becomes clear that this report cannot definitively attribute the case to oils inhaled from an electronic cigarette.

The report does not document the specific brand of electronic cigarette used, nor does it document the ingredients of that electronic cigarette. Thus, it is not even clear whether the electronic cigarette brand contained oils as an ingredient or not. The author of the paper is not able to provide that information, so it is premature and inappropriate - I believe - to draw the conclusion that the case was attributable to something that we don't even know for sure was present in that particular brand of electronic cigarettes.

According to the paper: "Recent evaluation of the nicotine solution and vapor content of e-cigarettes found primary components of propylene glycol, glycerin, and nicotine. Other chemicals identified in trace amounts include N-nitrosamines, diethylene glycol, polycyclic aromatic hydrocarbons, anabasine, myosmine, and β-nicotyrine. ... Vegetable glycerin is often added to the nicotine solutions used in e-cigarettes to make the visual smoke when the solution is vaporized."

None of the chemicals mentioned in this case report could cause lipoid pneumonia. While I am not arguing that it is impossible that the presence of oils in some electronic cigarette brands could hypothetically cause lipoid pneumonia if aspirated, it seems clear that this report fails to even document that there were oils present in the specific brand of electronic cigarettes used by the patient.

In the absence of such documentation, I don't see how the report can definitively attribute the lipoid pneumonia to the use of electronic cigarettes.

There is even a third possibility. The patient in question reported that her home was fumigated with chemicals two weeks prior to her presentation in the hospital. Exposure to fumigation chemicals has been associated with the development of lipoid pneumonia, possibly because some of the fumigation chemicals used are oils or oil-based.

Again, I have no problem with the report speculating that the use of an electronic cigarette that may have used an e-liquid that contained oils could potentially have caused lipoid pneumonia in this particular patient. However, I do not believe this justifies a conclusion that electronic cigarettes cause lipoid pneumonia and I think that the use of the term "glycerine-based oils" is misleading.

Nevertheless, I applaud the German Cancer Research Center for correcting the mistake about the potential cause of lipoid pneumonia in a patient who used electronic cigarettes.

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