Dr Lynne Dawkins, School of Applied Sciences, London South Bank University (Source: http://www.e-cigarette-summit.com/)
Dr Lynne Dawkins, School of Applied Sciences, London South Bank University (Source: http://www.e-cigarette-summit.com/)

Investigating e-cigarette puffing patterns and user behaviour associated with high and low strength nicotine e-liquids is one of the objectives Lynne Dawkins wants to achieve with this study [1] that will be carried out at London South Bank University. The researcher expects to get insights in how this affects toxicant and carcinogen exposure.

Implications for public health messaging and for regulations on nicotine concentrations in e-liquids will be addressed by this study that aims at understanding the risks compensatory puffing will have. The researchers will not only take into consideration the relative risks but also subjective effects associated with using high and low strength nicotine e-liquid.

Lowering nicotine strength, a choice or a necessity dictated by regulations

The first reason evoked by the researchers was the belief that it is healthier. Other reasons were the desire to wean off nicotine or, due to the EU Tobacco Products Directive, the necessity to downgrade their nicotine strength to remain compliant with the 20 mg/ml nicotine concentrations in e-liquids introduced in May 2016.

“[…] contrary to intuition, use of lower strength nicotine e-liquids might not offer reduced health risk if compensatory puffing behaviour occurs.

Lowering nicotine strength, what do we know about it?

Tobacco smokers, when switching to lower nicotine yield cigarettes, increase puff frequency, duration and volume when switching. Blood nicotine levels are maintained at high levels.

After switching to vaping, smokers typically take shorter puffs and it may take them a week or so to adjust their puffing patterns by a process called “self-titration” of nicotine, a subject that the principal researcher of this study knows very well.

“Self-titration” of nicotine, an inconspicuous mechanism

In a previous article [2], the Dr Dawkins explored the effects of high (24 mg/ml) and low (6 mg/ml) nicotine strength liquid on puffing topography (puff number, puff duration, volume of e-liquid consumed). She found that e-liquid consumption, puff number were higher and puff duration longer in the low nicotine strength condition, a nicotine compensation mechanism that is known as “Self-titration” in tobacco literature but poorly described in e-cigarette studies. No statistically significant differences were observed between conditions in self-reported craving, withdrawal symptoms, satisfaction, hit or adverse effects, which means that compensatory puffing was sufficient to reduce craving and withdrawal discomfort.

She reports doubled the amount of e-liquid consumed during a one-hour ad lib puffing period. However, self-titration was incomplete with significantly higher blood nicotine levels in the high condition.

Changes in puffing patterns and in e-cigarette use

According to her experience, much more than puffing patterns may be affected when switching to lower nicotine strength:

  • Flavoring quality, intensity,
  • PG/VG ratio,
  • Wattage (or voltage),
  • Airflow,
  • Resistance value.

Second and third generation devices offer multiple setting adjustments that may be interesting to survey along with e-liquid consumption.

Exposure to toxicants and carcinogens from e-cigarettes is 9–450 times lower than from tobacco cigarettes, however, vaping is not risk-free and toxicant exposure will be related to the amount of e-liquid consumed.

With longer, more frequent puffs and higher power to allow higher temperatures, the researchers anticipates vegetal glycerine (VG) and propylene glycol  (PG) to undergo decomposition to carbonyl compounds including harmful aldehydes.

When switching to lower nicotine strength, compensatory puffing patterns and changes to device settings may therefore lead to increased toxicant/carcinogen exposure due either to increased liquid consumption, increased temperature or both.

It is therefore questionable whether switching to lower strength nicotine e-liquid mayor may not be the lower risk option vapers are seeking?

What’s new in the experimental settings?

The originality of the experimental setting is its design in two different times: Phase I will serve to record puffing patterns to be as close as possible from reality. Phase II will be dedicated to reproduce those patterns and address toxicological issues.

Participants must be vapers for more than 3 months, at least, and should be using a nicotine strength e-liquid ≥12 mg/ml (1.2 %) with a second or third generation device (open-systems with re-fillable tanks). Current tobacco cigarette users (or a CO reading > 10 ppm) will be discarded from the study.

Phase I will survey biological parameters (saliva and urine samples, exhaled breath for CO) and also record subjective craving (urge to vape), withdrawal symptoms through the use of a specific scale as well as direct (e.g. hit, satisfaction) and adverse (headache, nausea) effects relating to nicotine/e-cigarette use.

The study will be conducted with a third generation device (Joyetech eVic Supreme), Aspire nautilus tank and e-liquid (either 6 mg/ml or 18 mg/ml) and one of four flavours of e-liquid to choose from, based on one popular flavour from different flavour categories (fruit, bakery, menthol, tobacco). They are required to use the same e-liquid throughout the 4 week period of Phase I.


myVapors is a computer user interface compatible with the eVic Supreme that allows visualizing the weekly vapor data, backing up the data of settings in the computer and importing the data into the e-cigarette

eVic Supreme:

  • Output wattage: 30W max.
  • Output voltage: 6V max.
  • Supported atomizer resistance value: 0.5Ω~5Ω.
  • Battery: 2500mAh (SAMSUNG INR 18650-25R)

The e-cigarette will record puff number, puff duration, voltage, wattage and resistance. Self-reporting will be asked to participants for puff velocity or volume. They will also be asked to refrain from using any other e-cigarette device, e-liquid or nicotine containing products like tobacco cigarettes. Weekly appointments with the research team are programmed during which puffing data will be downloaded from the device, the atomizer replaced and ancillary data collected.

Formaldehyde, acetaldehyde, acrolein, acetone, propionic aldehyde, crotonaldehyde, butanal, benzaldehyde, isovaleric aldehyde, valeric aldehyde, m-methylbenzaldehyde, o-methylbenzaldehyde, p-methylbenzaldehyde, hexanal, 2,5-dimethylbenzaldehyde and nicotine levels will be determined in aerosol emissions during Phase II.

A good choice of material

Compared to number of studies on e-cigarettes the choice of the the device, a Nautilus screwed on an eVic Supreme, seems, from experimented vapers’ experience, adequate to cover the most current wattage including those leading to the emission of toxic aldehydes. Its compliance with regular and subohm resistive wires may also provide a larger spectrum to investigate power effects.

A recent study published by British American Tobacco in Scientific Reports describes the technical advance the UK-based Big Tobacco company is taking on e-cigarette puff topography, based on their experience with smoking tobacco. Their machine is capable of recording puff volumes, for example, a value that will be missing in the set of data gathered by the authors.

With their study, the British researchers want to pave the way for future research in this domain. Their target is to ground science on the “safest” way to vape and to identify behaviors that constitute a risk, ultimately to quantify this risk. As a member of the research team for this study M. Goniewicz will certain provide his expertise in aerosol and e-liquid analysis.

In New Zealand, Janet Hoek from the University of Otago has received a 150,000 AUD grant, this year, to initiate a research program and collect behavioural data from e-cigarette users. The convergence between the two programs is the use of High-Tech e-cigarettes to record individual vaping data.

Dr Lynne E. Dawkins’ research funded by Cancer Research UK will be presented at the E-cigarette Summit to be held in London on November 17, 2016.

Additional information on new vaping patterns and risk exposure:

What do scientists think about vaping? – Konstantinos Farsalinos at Vapexpo 2016, Paris

[1] Cox S., Kośmider L., McRobbie H., Goniewicz M., Kimber CF., Doig M., Dawkins LE., 2016. E-cigarette puffing patterns associated with high and low nicotine e-liquid strength: effects on toxicant and carcinogen exposure. BMC Public Health, 16(1), 999.

[2] Dawkins LE., Kimber, CF., Doig, M., Feyerabend, C. Corcoran O., 2016. Self-titration by experienced e-cigarette users: blood nicotine delivery and subjective effects. Psychopharmacology, 1-9.

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PhD in science and journalist for the Vaping Post. Specialised in scientific topics.
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Norbert Zillatron
Norbert Zillatron
5 years ago

Sometimes cause and effect are the other way round!

I know a lot of vapers who reduce the nictine level because they like to vape more, but then the nicotine just gets too much for their liking. So they reduce the concentration.

So they don’t vape more to compensate a lack of nicotine.

Jérôme Harlay
Jérôme Harlay
Reply to  Norbert Zillatron
5 years ago

Yes, that’s true. And those people are probably not dependent on nicotine, they just appreciate vaping for what it is, and maybe also a little bit the hit that creates nicotine in their brain.

J. van Essen
J. van Essen
5 years ago

I am convinced that people reducing the nicotine level are automatically vaping more liquid to keep their nicotine intake at the same level. My personal experiences during the past 2 1/2 years confirm this pattern. It seems totally intuitive to me that a daily dose of 3 ml at 20mg nic has less impact and less risks than 10 ml liquid at 6mg, or 20ml at 3mg..

However it is obvious to me these researchers lack any experience with vaping and vaping lifestyle, themselves. While each tobacco cigarette has the same awful taste, it is unheard of to expect vapers to vape the same liquid for four weeks straight without using any other flavour or another device. Poor testbunnies who have to vape a whole week on one single aspire coil. Especially if they were heavy smokers using their vaping device a lot.
This would be enough for me to give up vaping before the 4 weeks were over..

There’s a reason starterkits used to contain two batteries and two
clearomizers: backup and/or to switch to a different flavour, during the
day. Within a few weeks most starters have multiple clearomizers for
different liquids.

The idea of subohming with a Nautilus is just ridiculous.
This clearomizer lacks the airflow required for subohming and prevent a subohm coil from overheating. It’s a decent atty for people new to vaping, but to be used in a very limited range of scenarios. There’s no fun in vaping the same boring liquid all the time. There’s no fun in dryhits. There’s no fun in vaping a coil for a week when that device is your sole atty. Overheated and gunked up coils will no doubt show more undesirable results than real life scenarios would.

This research completely ignores the pleasure principle, and expect people to behave like programmable robots.. programmed to fail.
While I applaud more research in this area, the scenario and conditions for this research are flawed by design.

Robert Noel Jr.
Robert Noel Jr.
5 years ago

When I switched to vaping I started at 18 mg and was vaping 8-12 mls a day. Now I’m down to 6mg and vaping 3-4 mls a day. This has been over 10 months of slowly lowering the mg in my ejuice. I am aiming to be down to 0mg by next fall. I also use dessert & fruit flavored ejuices. I use ceramic coils & kanthal coils tanks.

Jérôme Harlay
Jérôme Harlay
Reply to  Robert Noel Jr.
5 years ago

This is wise. What appears to be important for safety concerns with regard to aerosol composition is to keep the daily volume of e-liquid in the range of 3-4 ml, as you do. If you feel that you need more liquid, try to play with nicotine strength rather than simply refill more often.

The pleasure aspect must be decoupled from nicotine starvation according to tobacco experts. And in a logical way the vaper who does no longer need nicotine is the one who could stop vaping. However, vaping cessation has only been addressed by a few research studies and this idea generally hurts the opinion. Probably because vapers believe that since vaping is safer than smoking, they can continue ab lib without hurting their body as much as if they continued smoking. Would you stop vaping after a while, Robert, if you reached 0 mg?

Robert Noel Jr.
Robert Noel Jr.
Reply to  Jérôme Harlay
5 years ago

That is what I myself is working towards, we are now at 3ml nicotine in our e juice.

5 years ago

I vape 0 MG because I enjoy vaping. If I am around smokers or other vapers I vape more. If I am by myself I barely touch the device. The only time I have an urge to vape is when I am by someone smoking, otherwise it is just pure pleasure.