Quantitative study of aldehyde content in electronic cigarettes

April 17, 2017 by Heather Zeiger report
Credit: CC0 Public Domain

(Phys.org)—Electronic cigarettes have had their share of both detractors and advocates since they hit the market in 2004. Many people believe that they are healthier than cigarettes, but others say that the effects of e-cigarette vapors are largely unknown. Medical organizations have generally taken a cautious approach and do not specifically recommend e-cigarettes for stopping smoking or as a healthier alternative to smoking.

One area of concern is the amount of aldehydes present in e-cigarette smoke. These aldehydes are present in tobacco cigarettes in larger quantities than in e-cigarettes, but the levels in e-cigarettes are still not known. Additionally, the amount that is considered dangerous for cardio vascular disease (CVD) is a topic of debate. Some studies have shown that even small amounts of certain aldehydes can lead to progression of CVD.

Researchers from the University of Louisville's Tobacco Regulation and Addiction Center conducted quantitative analyses of both older (first generation) and newer-model e-cigarette cartridges using a variety of flavors. They used a new method for trapping reactive carbonyls that are then subsequently stabilized using an oximation reaction. They found that newer devices produced more harmful aldehydes than first generation e-cigarettes. Their work appears in ACS Omega.

E-cigarettes cartridges contain battery-powered coils that serve to heat and vaporize e-Liquid. Based on this study, the amount of reactive aldehydes in are largely due to the cartridge's . The higher the battery power, the higher the aldehyde levels. While e-cigarette aerosols contain aldehydes that are known to contribute to CVD, the exact levels have not been definitively determined largely because of the difficulties associated with trapping and studying reactive aldehydes.

New models, or "next-generation," e-cigarettes have a higher battery power than older ones. Furthermore, older models have a fixed battery output (4.6 W) while the next-generation ones have variable output (9.1 W, 11.7 W, 14.7 W, 16.6 W). The authors wanted to look at this next-generation of e-cigarettes to quantitatively determine aldehyde levels as well as determine if e-Liquid flavor makes a difference in aldehyde formation. In order to do this, they took into account the formation of hemiacetals from aldehydes, something that prior studies did not address.

The aldehydes that are of greatest concern are acetaldehyde, acrolein, and formaldehyde. Acrolein, in particular, has been shown to advance CVD, even when a person is exposed to low levels. Formaldehyde has also been associated with CVD in low concentrations.

Credit: ACS

E-Liquids are usually comprised of glycerin and along with a flavor additive. Glycerin, when heated, predominantly forms acrolein and formaldehyde, while propylene glycol predominantly forms acetone and acetaldehyde. Certain flavor additives have shown enhanced aldehyde formation, as well.

Ogunwale et al. used a microreactor-capture approach that they had previously developed to obtain an accurate look at aldehyde levels in vapor. This method employs a 4-(2-aminooxyethyl)-morpholin-4-ium chloride (AMAH) coating on a silicon base. Aldehydes selectively react with AMAH to form an oxime, which is more stable and easier to study than an aldehyde.

Aerosols were generated using a cigarette-smoking robot and were collected in Tedlar bags. The robot allowed for control over puff duration, puff volume, and puff frequency. The aerosols flowed through the microreactors from the bags using an evacuation process and then reacted with AMAH. The AMAH oxime compound was neutralized to form an AMA adduct that was then studied using gas chromatography.

Both the first generation and next generation e-cigarettes produced some amount of acetaldehyde, acrolein, and formaldehyde, but acealdehyde and formaldehyde were in higher concentrations than acrolein. All of the aldehydes were present in lower concentrations than what is found in cigarette smoke using Health Canada Intense Puffing Regime. Notably, the next-generation e-cigarettes, which have a tank-type atomizer, produced higher levels of aldehydes and acetone. The authors attribute this to the higher battery output.

To understand the puffing topology, Ogunwale et al., used 60-mL syringes to manually vary puff duration and volume to more accurately replicate real-life usage. Puffing duration and the particular flavor contributed to the formation of reactive aldehydes, although these factors played a smaller role than battery output in the amount of aldehydes present. If puffing duration was around 4.0 seconds/puff, more aldehydes were present compared to shorter or longer puffing. The average user puffs for 3.5 to 4.3 seconds.

Finally, Ogunwale et al. used 1H NMR to detect and quantify the presence of hemiacetals formed from aldehydes. They found that hemiacetals did not form in any of the first-generation e-cigarettes flavors, and they did not form in three of the next-generation flavors tested. Only one flavor that was tested formed hemiacetals within a battery output that was within the range of normal use.

This study provides valuable information on the safety of e-cigarettes. In general, the higher the battery output, the higher the levels in the vapor. Certain aldehydes, such as acrolein, acetaldehyde, and formaldehyde, have been shown to contribute to CVD even in low levels. All of the e-cigarettes tested in this study had some amount of these aldehydes present.

Explore further: Hazardous chemicals discovered in flavored e-cigarette vapor

More information: Mumiye A. Ogunwale et al. Aldehyde Detection in Electronic Cigarette Aerosols, ACS Omega (2017). DOI: 10.1021/acsomega.6b00489

Abstract
Acetaldehyde, acrolein, and formaldehyde are the principal toxic aldehydes present in cigarette smoke and contribute to the risk of cardiovascular disease and noncancerous pulmonary disease. The rapid growth of the use of electronic cigarettes (e-cigarettes) has raised concerns over emissions of these harmful aldehydes. This work determines emissions of these aldehydes in both free and bound (aldehyde–hemiacetal) forms and other carbonyls from the use of e-cigarettes. A novel silicon microreactor with a coating phase of 4-(2-aminooxyethyl)-morpholin-4-ium chloride (AMAH) was used to trap carbonyl compounds in the aerosols of e-cigarettes via oximation reactions. AMAH–aldehyde adducts were measured using gas chromatography–mass spectrometry. 1H nuclear magnetic resonance spectroscopy was used to analyze hemiacetals in the aerosols. These aldehydes were detected in the aerosols of all e-cigarettes. Newer-generation e-cigarette devices generated more aldehydes than the first-generation e-cigarettes because of higher battery power output. Formaldehyde–hemiacetal was detected in the aerosols generated from some e-liquids using the newer e-cigarette devices at a battery power output of 11.7 W and above. The emission of these aldehydes from all e-cigarettes, especially higher levels of aldehydes from the newer-generation e-cigarette devices, indicates the risk of using e-cigarettes.

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23 comments

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pmoglewer
1.8 / 5 (10) Apr 17, 2017
This study, while not laden with confirmation bias as with many past studies, is deeply flawed. First of all, where did you study electrical mechanics? Labeling wattage, a function of power, as "Battery Power" is a rediculous mistake. Battery power, as you are using the term, is not something that exists outside of a closed circuit. Watts are a function of the current acting on a resistor. It's voltage*aperage, and doesn't exist without a closed circuit and resistor.
pmoglewer
1.8 / 5 (10) Apr 17, 2017
As such, the wattage changes with both voltage output and different resistors, both of which have long been user adaptable for years in nicer atomizers and voltage modulators (vaporizers), and really have nothing to do with "battery power" outside of non-regulated, mechanical systems.
pmoglewer
1.9 / 5 (9) Apr 17, 2017
Secondly, I'm assuming, like all flawed studies before this, that you are using the tiny, cylindrical stick vaporizers that use prepackaged, preset resistor cartridges. There's three problems with this: 1. Nobody who actually vapes full-time uses these so called "cigalike" vaporizers anymore. They suck. They suck because they produce chemicals. They produce chemicals because they burn. They burn because:
pmoglewer
1.8 / 5 (10) Apr 17, 2017
2. These old cartridge resistors are, generally, not user refillable or user serviceable. In any modern atomizer worth it's salt, the coils are either user built, sitting in polarized posts above a refillable well allowing the wicking material to constantly be fed enough vaporization medium so as to never dry out and burn, or they're tank-style atomizers where the coils come in replaceable packs and are constantly fed glycerin by a surrounding holding tank. In both situations, the wicking material is never allowed to dry in the same manner as a cartridge ( as long as the user is paying attention), which keeps the entire system cooler, decreasing or even eliminating aldehyde production.
pmoglewer
1.8 / 5 (10) Apr 17, 2017
3. Airflow. Modern atomizers, both tank and dripper style, are designed to provide massive amounts of airflow when compared to cartridge vaporizers. Since aldehyde production is a function of net-heat at the resistor and time of heat exposure, and since increased airflow decreases heat at the resistor regardless of wattage output, aldehyde production in actually modern atomizers is slim to none. When you up the heat, you increase the airflow to insure proper vaporization without burning.
It's simple really. For any scientific study to be accurate, and indeed relevant, you need to be studying the systems people are ACTUALLY USING, in the ways they are actually using them.
pmoglewer
1.8 / 5 (10) Apr 17, 2017
I would love to see a study actually geared towards finding average aldehyde production of a modern 200 Watt modular vaporizer, with a modern tank or dripper atomizer, at differing power outputs with different airflow and air-pressure configurations. This would benefit everyone, as vapers would get a good idea of the limits of safety (as I'm sure above certain wattages airflow and wick saturation become less of a factor and aldehyde production becomes a definite issue), and non-vapors would finnaly be given accurate information about the dangers (or truly, lack thereof) of "second-hand-vapor."
pmoglewer
1.8 / 5 (10) Apr 17, 2017
Also, where is your control variable? Take tests of the baseline aldehyde content in the air and in unheated air that has passed through an unused atomizer. Without this, your results have LITERALLY NO SCIENTIFIC MEANING.
gkam
Apr 17, 2017
This comment has been removed by a moderator.
krundoloss
1.4 / 5 (10) Apr 17, 2017
Every time I see a study like this, it seems obvious that none of the participants actually vape themselves. This brings about a flawed study simply because they would actually puff on the test devices themselves and verify that it is what a normal person would vape. Any vaper that has had a dry hit, probably did not even inhale as they could instantly tell something was off. I want a study like this to use standard tanks and mods with clean simple flavors that use fewer chemicals than "cig-a-like" models. Everyone in the vaping industry does everything they can to make the habit healthier, except perhaps when vapor production is increased. Testing any cig-a-like model with cartridges is not the way to go, as those are starter devices and anyone who appreciates vaping will move on from them quickly. Not to mention they are unreliable, cost much more than other vaping methods, and they are designed first and foremost to mimic a cigarette (smokey flavors, more additives, higher temp).
krundoloss
1 / 5 (3) Apr 17, 2017
Not only that but you have to let your Coils Cool Down, if you keep hitting the device over and over like a robot, it will start to overheat produce chemicals.

I will say though, that it is apparent to me, and I'm sure anyone who vapes with nicotine, that the risk for cardiovascular disease is increased by vaping. It might be healthier than cigarettes, but it is not good for your heart and circulatory system.
TheGhostofOtto1923
3.9 / 5 (7) Apr 17, 2017
Nicotine does not produce any high whatsoever. What smokers experience is relief from withdrawal from their last fix.

IOW smokers only feel normal right after their last dose. They would feel this way all the time if they didnt smoke. They deceive themselves into thinking that the nerves, fatigue, confusion, irritability, and pain associated with withdrawal is how they would normally feel all the time.

Actually they dont think about it much at all they just smoke, and stink, and hack, and wheeze, and sicken, and die.
It might be healthier than cigarettes
-You mean less unhealthy dont you?
Zzzzzzzz
4.4 / 5 (7) Apr 17, 2017
pmoglewer, I used to smoke. I quit doing that 25 years ago. The first and most important thing I get from your posts is that I am very very glad I never was stupid enough to take up "vaping".
davidknaack
5 / 5 (5) Apr 17, 2017
I'm assuming, like all flawed studies before this, that you are using the tiny, cylindrical stick vaporizers that use prepackaged, preset resistor cartridges


Don't assume, go read the paper:

1: first-generation e-cigarette blu with a fixed battery output voltage of 3.7 V (coil resistance 3.0 Ω)
2: KangerTech EVOD2 (coil resistance 1.5 Ω) with iTaste VV V3.0 battery

davidknaack
5 / 5 (1) Apr 17, 2017
3. Airflow.


This paper is a lot better than some of them. The puff size/duration data from "Electronic Cigarette Topography in the Natural Environment" is fantastic when compared to, for example, the ridiculous "Mining data on usage of electronic nicotine delivery systems (ENDS) from YouTube videos" which has been used in other studies.
davidknaack
not rated yet Apr 17, 2017
aldehyde production is a function of net-heat at the resistor and time of heat exposure, and since increased airflow decreases heat at the resistor regardless of wattage output, aldehyde production in actually modern atomizers is slim to none.


Got a source? I think you're right on the deficiencies in these studies, but I'd like to read some better studies that support your claim.

Hopefully someone will directly measure coil power, temperature, air flow, and outlet temp produced by experienced users, then reproduce those factors to separately measure vape components from dozens of common flavoring components. Likely some are safe, some are not.
cortezz
1 / 5 (1) Apr 18, 2017
Nicotine does not produce any high whatsoever. What smokers experience is relief from withdrawal from their last fix.

It does. As an experienced non-tobacco smoker, I can tell you that everytime I smoke a cig being drunk etc. I really do feel the high. It's even better high if you take the nicotine in snus form. First time I tried snus, I was so drunk that I almost passed out from the nicotine.
TheGhostofOtto1923
3 / 5 (2) Apr 18, 2017
As an experienced non-tobacco smoker, I can tell you that everytime I smoke a cig being drunk etc. I really do feel the high. It's even better high if you take the nicotine in snus form. First time I tried snus, I was so drunk that I almost passed out from the nicotine
No it doesnt. If it did it would come with restrictions on driving, operating heavy machinery, combining with other drugs, etc.

Nicotine is the only drug that does nothing other than to treat its own withdrawal symptoms. Its also an effective bug killer.

So what about your thrilling passing-out experience? Are you in the business of selling this shit? Perhaps you really enjoy od-ing on poison?

Try huffing - its much cheaper.
cortezz
3 / 5 (2) Apr 18, 2017
As an experienced non-tobacco smoker, I can tell you that everytime I smoke a cig being drunk etc. I really do feel the high. It's even better high if you take the nicotine in snus form. First time I tried snus, I was so drunk that I almost passed out from the nicotine
No it doesnt. If it did it would come with restrictions on driving, operating heavy machinery, combining with other drugs, etc.

It doesn't produce a long "high". Things can get little shaky for few minutes but that's it. I know part of the "high" comes from oxygen deprivation but nicotine clearly does something because the effect also comes from snus.

No, I would not sell it as a drug but I enjoy the feels. It's similar kind of enjoyment I get from the burning of strong alcohol or from eating chili.
TheGhostofOtto1923
1 / 5 (1) Apr 18, 2017
You should try huffing nitrogen then.
krundoloss
5 / 5 (1) Apr 19, 2017
Hey Ghost, Nicotine is a real drug with real effects.

-Nicotine travels through the body in the bloodstream and heads straight for the brain, arriving in 7 to 15 seconds.
-In the brain, nicotine boosts the "reward center," releasing chemicals that cause a pleasant, happy feeling.
-Adrenaline is then released, increasing heart rate and blood pressure, and making breathing rapid and shallow.

Source: https://www.ucanq...eEffects
cortezz
1 / 5 (1) Apr 19, 2017
You should try huffing nitrogen then.

I don't know about pure nitrogen but N2O is good enough!
TheGhostofOtto1923
not rated yet Apr 19, 2017
Nicotine is a real drug with real effects
The tobacco industry spent lots of money to convince addicts that their product wasnt addictive. Once it became clear that it was, they spent lots of money to convince addicts it was a recreational drug. They commissioned studies from the same sorts of researchers who helped them prove the original hypothesis. Why would you believe either?
Nicotine travels through the body in the bloodstream and heads straight for the brain, arriving in 7 to 15 seconds
So does DMSO. So what?
In the brain, nicotine boosts the "reward center," releasing chemicals that cause a pleasant, happy feeling
'People cannot tell the difference between pleasure and relief from pain.' - Epicurus
-Adrenaline is then released, increasing heart rate and blood pressure, and making breathing rapid and shallow
Exercise and scary things both release adrenaline etc. Would you call them drugs?

Like I say its all hype meant to sell a product.
TheGhostofOtto1923
not rated yet Apr 19, 2017
Ask any smoker if tobacco makes them high. If they are being honest they will tell you no. They will tell you how they originally felt before they were hooked though; nauseous, dizzy, short of breath. These are symptoms that people like cortezz seem to enjoy, but bread mold will do the same thing.
making breathing rapid and shallow
-So does emphysema. Haha.

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