As promised last week, I waded into the mire of medical research literature, looking for an interesting study I could blog about.
I found a nifty little Korean study, titled "Use of a gas-tight syringe sampling method for the determination of tobacco-specific nitrosamines in E-cigarette aerosols by liquid chromatography-tandem mass spectrometry" (Cho and Shin, 2015).
The abstract contained the sentence that I used to title this post, but of course, you can't just stop there. I decided that, since on the face of it this study supports our position, it is worth examining the study in detail to see what they did and how they did it and whether the results are reliable and relevant.
So, in I went! Below is my summary in plain english.
Vapour draw method
In all other studies on e-cig vapour, researchers use the impinger method. Essentially, the e-cig is attached to an air pump, which is attached to a series of bottles containing a solvent. The vapour is then pumped through the bottles where it interacts with the solvent, absorbing the compounds present in the vapour.
The impinger method is a standard method of aerosol sampling, but when relating to cigarettes, both e- and conventional, it has its drawbacks (groan, the puns just don't stop!). Firstly, the rate at which the compounds are absorbed does not necessarily reflect human lung absorption, and secondly, the method for extracting the vapour creates suction conditions that no normal human being could reasonably produce.
The authors of this study decided to develop their own method to improve the accuracy of their results. In a nutshell, they put a solvent in a big glass syringe, attached the e-cig to it and pulled the plunger.
(© The Royal Society of Chemistry 2015)
What I liked about this is that they only pulled the plunger for five seconds, and they pulled it once then detached the e-cig and shook the solution for almost four minutes. This far more closely resembles an actual human taking a drag on an e-cig than the pump-powered impinger method, and all without overheating the coil.
What I didn't like? Firstly, they state they pulled the plunger at a rate of 600 mL/min, because this was the rate at which the maximum absorption of TSNAs was achieved. Do you draw on your e-cig at the rate of 600 mL/min? Do I? I've got no idea. And because of the variability of each individual style of vaping, we have no idea how closely this resembles an actual human vaping experience. Secondly, did this method accurately correspond to human lung absorption? They didn't say, so we don't know. But - at least they were shooting for method accuracy. So at least we can be confident that someone who drags on their e-cig for five seconds at the rate of 600 mL/min with a lung absorption rate exactly the same as the rate achieved via this method will get exactly the amount of TSNAs from the 50 different e-liquids this study shows.
They used the draw method on three different units: an e-cigarette containing a control liquid that was "spiked" with a known quantity of TSNAs, an e-cigarette containing commercially available e-liquids, and a tobacco cigarette.
The spiked solution was used to see how accurately they could detect the TSNAs, and as it happens the accuracy was between 96-100%. Pretty good I'd say. With this in mind they then went on to compare commercially available e-liquid to good old-fashioned stinkies. So we can at least trust that the comparison results will be highly accurate.
"Liquid chromatography-tandem mass spectrometry".
Yeah. I read this section of the paper and had "blah blah blah jargon jargon jargon" in my head. Putting that in layman's terms will be a stretch! But, as best I understand it myself, they dried out the test solution, smashed protons into it and examined what came out, and were able to infer exact amounts of the TSNAs from this. Sounds crazy, but this is actually a standard method that is highly accurate and reliable, so we'll give the smart people a pass on this one.
This is where I went "hmm" a little bit.
First, they bought two Ruyan V8s from China. These things:
I couldn't find out for sure, but it's possible that these were among the very first e-cigarettes ever invented. I didn't really have an issue with this. In reality, most people who switch from smoking to vaping will start on something like this. These kinds of devices are what Big Tobacco is using to try and take over the market. And these are the units that appear in all the advertising and mass-marketing material. So it makes sense they will use this kind of device, as this is where the greater public attention is focussed.
What I did have an issue with?
"Replacement liquids from 11 different E-cigarette companies were purchased in July and August 2012 from shops in various regions of the Republic of Korea. These shops imported the liquids directly from the manufacturers in China and the liquids were mixtures of solutions containing nicotine and various flavoring agents" (Cho and Shin, 2015).
So, basically, they bowled up to a bunch of e-cig shops in Korea and bought over-the-counter e-liquid originating in China. They didn't mention who the manufacturers were, they didn't check the QC methods or reputations of the manufacturers, and they didn't comment on the exact composition of the "mixtures of solutions".
I know I share this frustration with many experienced vapers. Like me, you only buy your e-liquid from reputable producers, who you know and trust for their quality control. You research your suppliers first; you check how long they have been in business and you read the customer reviews; in short you do some sort of credibility assessment before purchasing their product. Yet the people studying e-cigs seem to grab random e-liquid from the local B&M. Did they speak to the shop owner about the quality of the liquids? We don't know. Do they have any personal knowledge about which manufacturers are good or not? We don't know. Did they examine the nicotine extraction methods used for these liquids? We don't know. Until researchers realise that this is an area representing a high degree of variability, their studies will be limited in their results.
My other gripe with this section: what was the e-liquid nicotine strength? They don't say. What was the strength in mg of the tobacco cigarettes? They don't say. Therefore, did they use e-liquid that could be considered comparable in strength to the tobacco cigarettes? We don't know. To me this is the biggest weakness of the study. Without this crucial piece of information, the result gets thrown into question. Did they use 16mg cigarettes and 3mg/L e-liquid? Did they use 2mg menthol light cigarettes and 24mg/L e-liquid? In my opinion, by leaving this information out, they did not adequately control for questions of bias.
(© The Royal Society of Chemistry 2015)
As the title of this blog post subtly suggests, they determined, to a high degree of accuracy, that vapourised e-liquid only contains 1% of the cancer-causing TSNAs present in tobacco smoke. However, as the above graph shows, there was a high degree of variability between the 50 e-liquid samples. Was this due to their lack of investigation into quality control? Are the different levels a result of differing nicotine strengths? Yet again - we don't know.
Now this is where it can be spun one of two ways.
1. The pro-vape angle
You see? Only 1% of tobacco cigarettes! E-cigs are 100 times less likely to give you cancer! And if you only buy good quality ones the chances are even less! So leave us alone!
2. The anti-vape angle
You see? TSNAs! E-cigs can still give you cancer! And who knows the levels you will get between different e-liquids? So ban them!
The problem with spin is that it is spin. You will likely see argument number 1. popping up in e-cig forums and argument number 2. popping up in alarmist medical literature. Both arguments are spins on the results, and spun research conclusions are not a useful way to support and protect our vaping community and industry - your opponent can always counter the spin.
I have a radical proposition. In order to cut through the noise and clamour, we should take an evidence-based, rational approach to the results of e-cig studies, and be this voice in the vaping community and in society. So let's look at this study with a level head.
In spite of its flaws, this study shows that - depending on the quality of the e-liquid - the risk of cancer from nicotine use is drastically reduced by switching to e-cigarettes. This resonates with our message of harm-reduction - e-cigarettes are a safer alternative to tobacco cigarettes. Don't market them to kids, don't make them trendy and don't advertise them in glossy mags and billboards. But for the love of Pete, let ex-smokers use them in peace.
Reason and evidence are our biggest assets in this argument, so let's use them and not get drawn into the rhetorical waltz!
Cho, Y. and Shin, H. (2015). Use of a gas-tight syringe sampling method for the determination of tobacco-specific nitrosamines in E-cigarette aerosols by liquid chromatography-tandem mass spectrometry. Analytical Methods.