Formaldehyde release in e-cigarette vapor

The New York Times story explained in detail

 

Dr Farsalinos

A study to be published in Nicotine and Tobacco Research was featured in the New York Times and has generated a lot of interest. The article mentioned that e-cigarette vapor can be the source of carcinogens, depending on the heating process.

The article is true and expected. We know that thermal degradation can lead to the release of toxic chemicals. And we know that formaldehyde, acetaldehyde and acrolein have been found in vapor. There is nothing new to it. However, this study found that levels may approach those present in tobacco cigarettes. Of course there some inaccuracies in the NYT article, such as that nicotine gets overheated (which means nothing).

Herein, I present with more detail the results of this study. Researchers used an EGO Twist battery (variable voltage) and a top-coil clearomizer (with unknown resistance, thus unknown wattage delivery). At 3.2 and 4.0 volts, formaldehyde levels were 13-807 times lower compared to tobacco cigarettes!! At 4.8 volts, formaldehyde levels were increased by up to 200 times, and reached to levels similar to tobacco cigarettes.

The main criticism to this study is that in my opinion it is highly unlikely that a top-coil atomizer like the one used in this study would be used at 4.8 volts. At a resistance of 2.2 Ohms that would represent 10.4 watts of energy delivery to the atomizer. I tried 10 watts with an EVIC battery in a Vivi Nova top-coil atomizer (for a clinical study i perfomed few months ago), and many vapers were unable to use it due to the dry puff phenomenon. Unfortunately, the researchers did not measure and could not provide any information about the resistance of the atomizers, thus it is unknown how much energy was delivered to the atomizer. In my opinion, this is crucial. Moreover, it is very important to examine new-generation (rebuildable or bottom coil) atomizers at similar conditions, since it is more likely for vapers to use such advanced atomizers for high-wattage vaping. I am certain that, due to better liquid resupply to the resistance and wick, the results will be much more favorable.

Another important point is that, although formaldehyde levels can be similar to tobacco, several other toxic chemicals are completely absent from e-cigarette vapor. For example, acrolein was completely absent although they used liquids with glycerol as the main ingredient. In fact, glycerin-based liquids had much lower formaldehyde levels in vapor compared to PG or PG/VG liquids, suggesting that they are much safer to use. As a general remark, finding few chemicals at similar levels does not mean that the risk is equivalent to tobacco cigarettes. Of course, all this information was not presented in the NYT article.

Concerning the remarks about dripping, we should admit that dripping does not allow the user to see how much liquid is present in the atomizer. The same happens with cartomizers. We currently do not know whether the elevation in formaldehyde levels happens just at the time of dry puff phenomenon, or it happens earlier (before being detected by the vaper). Clearomizer-type atomizers (also called tank systems) seem to be the future in e-cigarette use, giving consumers the ability to know when they need to resupply the atomizer with liquid.

 


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+1 #51 Dr Farsalinos 2014-07-28 23:29
You are right, it is unclear how they found PEG. Based on the way they mention it, it seems that it was through the label.
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+1 #50 john r walker 2014-07-28 23:18
Actually the paper states that the liquids were grouped as : " Based on the labeling information, we grouped the products into VG based (only VG; A1–A3), VG:PG based (both VG and PG mixed in various ratios; A4–A6), and PG based (only PG; A7–A10). "
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0 #49 Dr Farsalinos 2014-07-28 22:48
The paper mentions that they did perform chemical analysis.
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0 #48 john r walker 2014-07-28 22:38
Dr Farsalinos
The studies chart http://ntr.oxfordjournals.org/content/early/2014/05/14/ntr.ntu078/T1.expansion.html for the 13 liquids tested states : "Ingredients (as listed on labels)".

Did the researchers do a chemical analysis of A6 ?

The make up of the liquid that performed so well in a fairly extreme test is of interest.
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0 #47 John r walker 2014-07-28 20:38
The researchers conducted a analysis of the liquids ? A6 definitely had PEG?
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0 #46 Dr Farsalinos 2014-07-28 09:14
I don't think we can find any photo of the label. And i am not sure that the manufacturer may know better than the analytical chemistry result...
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+1 #45 john r walker 2014-07-28 04:45
Dr Farsalinos
The best performing of the 13 liquids used in the trial was "(A6)" . The manufacturer of this commercial e-liquid has informed me that the liquid (if it is theirs ) is a PG/ VG , and 'herbal extracts' and nicotine. And that the liquid definitely did not contain any PEG at all.

The manufacture was wondering if there was a picture of the lable on the actual bottle of "sunny banana" e-liquid that was the e-liquid ( A6) in the trial?
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0 #44 john r walker 2014-07-22 22:41
Quoting Dr Farsalinos:
It seems that most of the problem originated from PG, not VG. Since there was no acrolein, you are right that the temperatures did not elevate to very high levels..


Yes, PEG (which performed very well ) is stable to about 300C.

A aspect of the test that could have been most unrealistic could be this : the ecigs were kept constantly horizontal and therefore there would be much less turbulence and mixing, of the small portion of the liquid in close contact with the heating element, than if the ecig was waving around in a hand .
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0 #43 john r walker 2014-07-22 06:30
Sorry electrics is really not my area.
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+3 #42 Dr Farsalinos 2014-07-22 06:07
I think it is more appropriate to refer to wattage instead of voltage....
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