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The defence of the indefensible – the 20mg/ml limit imposed by the TPD can only cost lives.

21, Jun, 2016



It has been suggested that the limit imposed by the TPD will not make any material negative difference, and may have positive outcomes. However there are number of reasons why this goes beyond being implausible, and into positively impossible.

This is a brief look at the costs, and benefits of mandated maximum nicotine levels.

Opportunity cost

We already know that many smokers find the transition to vaping difficult. There are a number of studies into this, but one of the most recent was a survey by ASH[A], which looked at the reasons people stop using ecigs:

20% of those who discontinued use did so because “They didn’t help me deal with cravings for smoking”. We don’t have any data on what nicotine levels these people were using, but it is implausible to suggest that this proportion can be reduced by capping the maximum nicotine level at 20mg/ml. (This proportion is also unlikely to benefit from the almost total prohibition on advertising of e-cigs that contain nicotine, since they are more likely to be exposed to advertising for nicotine free products). We could also expect an increase in the 4% who felt that they were “using them too often compared with smoking”, which was highlighted by ASH for reasons relating to safety (much more on this later).

We also have data that indicates that inexperienced users are unable to take in as much nicotine as more experienced ones. Farsalinos et al[B] gave smokers a reasonably advanced device filled with 18mg/ml liquid, along with minimal instruction, and compared nicotine levels after use with those of experienced vapers:

The difference between naïve and experienced users was statistically significant, with experienced users having higher levels:

“At all time-points besides baseline, the difference in plasma nicotine levels between the two groups was statistically significant (P = 0.002 at 5 min, P < 0.001 at all other time-points), with vapers consistently having higher plasma nicotine levels.”

This further increases the risk of failure, since those most at risk of relapse or abandoning a switch attempt are also those least able to self-titrate their nicotine levels to a satisfactory level.

Further adding to the difficulties faced by those intent on switching , recent research by Dawkins et al[C] examined the effect of reduced nicotine levels on nicotine delivery in experienced users:

Despite an increase in both the number and duration of puffs, leading to a doubling of liquid consumption, even experienced users were unable to self-titrate to similar levels. As indicated by Dawkins et al:

“Self-titration is well documented in the tobacco literature.”

Notable examples include this 1979 BMJ article[D], which unusually is open access, and this analysis[E] from data from the Scottish Heart Health study in 1993, and particularly noteworthy is this 2004 Japanese study from Nakazawa et al[F] which concluded:

“Smokers consuming low-yield nicotine cigarettes did not reduce actual intake of nicotine to the level that might be expected, especially for those heavily dependent on nicotine.”

It has been suggested that since only 9% of users utilise levels over 20mg/ml[G], that this is not a cause for concern. However, not only is 9% of the estimated 2.8 million users in the UK a substantial number of people – 250,000, we also have pretty good data that users tend to start with higher nicotine strengths, and voluntarily reduce them.  As far back as 2013, Farsalinos et al[H] studied a group of vapers who had managed a complete switch to vaping from smoked tobacco.  They found a slight increase in nicotine use between initial trial, and point of smoking cessation:

However they also then found that levels currently used were much more diverse, and generally lower:

This would very strongly suggest that the opportunity cost of imposing lower nicotine levels is actually significantly higher than the 9% a facile examination of the data would suggest.

Bottom line

From this data, we can fairly safely conclude that reducing the nicotine levels of vaping products will result in lower nicotine levels in all users, and that inexperienced ones are likely to be disproportionally affected. Given that cigarettes are an extremely efficient nicotine delivery system, it is utterly implausible to suggest that reducing the nicotine delivery from e-cigs will help them compete with tobacco cigarettes as a nicotine delivery method. There is, however, a slight silver lining to this from an industry perspective – lower nicotine levels are likely to result in increased consumption, and therefore sales, of e-liquid.


Enhanced risk

The Dawkins et al study found that:

Not surprisingly, as nicotine concentration was reduced, the amount of liquid consumed per hour increased, via a change in use topography.

There are a divergent range of views on the safety of vaping. However, simple logic tells us that whatever the risks are, they will be directly related to the amount of liquid atomised and inhaled.

If, as some suggest, the risks are significant, then they could and should be minimised by encouraging people to use higher nicotine strengths, and to thereby reduce the volume of liquid they consume. Even if we assume (as well we might, given the data available) that the risks are very low, they will still be increased by an increase in liquid consumption.

Even in cigarette smoking, higher nicotine levels are associated with lower toxicant exposure. Returning to the Scottish Heart Health Study, it found that:

“CO-E [Carbon monoxide in exhaled breath] is found to increase positively with CO and tar yield, but inversely with nicotine yield. Thiocyanate increases positively with CO, is not significantly affected by tar, but increases inversely with nicotine.”

“We conclude that smokers appear to self-titrate their consumption of nicotine by more aggressive smoking of lower-strength cigarettes.”

(A separate analysis[I] of this data also provided real world data to support the idea, relatively novel at the time, that machine measured tar yields did not reflect actual user exposure.)

As if this clear logical progression of the poorly quantified risks of vaping was not enough, Professor Dawkins was part of a study to examine if the compensatory puffing identified in the examination of self-titration affected emissions of carbonyls, which are one of the better quantified elements of risk. This study, by Kimber and Kosmider, is so far unpublished, but was presented at a recent conference[J]. The puffing topography for both the 6mg/ml and 24mg/ml use conditions were applied:

Despite the liquid consumption being doubled during compensatory puffing, the emissions were (slightly) more than doubled:


This led the study authors to conclude that:

“The smoking machine, programmed with a more intensive puffing regimen to reflect compensation by experienced vapers on lower nicotine concentration liquid, resulted in higher aerosol levels of formaldehyde, acetaldehyde and acetone. Our findings suggest, vapers making a sudden switch to much lower nicotine concentration liquid (either due to the EU-TPD implementation or personal choice) may inadvertently increase their exposure to carbonyl compounds through compensatory puffing behaviour.”

Bottom line

It seems safe to conclude that compensatory puffing and increased liquid consumption will increase both the known, and unknown, risks of vaping. Regardless of what the risks of vaping are, compelling a reduction in nicotine levels will increase risk.


Reduced poisoning risk

During the TPD process, much was made of the potential for accidental deaths to arise due to the levels of nicotine found in e-liquid. During the process, the European Commission committed to provide a report on the dangers associated with refillable products, which was published on the date the TPD was implemented[K].

The first item covered in the report was accidental ingestion of e-liquid. The report states:

“Refillable e-cigarettes and refill containers are, in most cases, open systems that allow direct access to nicotine-containing liquids. Nicotine is an alkaloid found in tobacco plants. It is a stimulant that acts on the parasympathetic  nervous system  and  is  the  primary  cause  of  addiction  to  tobacco  products.  A highly  addictive  drug,  nicotine  is  also  acutely  toxic  (lethal)  by  all  routes of  exposure  in  high  enough doses.”

They then examined data from the EU on accidental exposures to nicotine. (Rather oddly, this did not include UK data, which was also available.)

They took particular care to note that:

“There have been media reports of lethal poisonings of young children in the US and Israel from e-liquids.”

The second item covered was dermal contact with nicotine solutions. They note that:

“There  is  a  risk  when  opening  or  refilling  that  e-liquid  from  refillable  e-cigarettes  is  spilled  and  comes  into  contact  with  the  skin.”

They estimate that 10% of the identified exposures relate to dermal contact.

Not surprisingly, they note that, for both dermal and oral exposure, the TPD mandated limit would reduce risk:

“In addition to these precautionary requirements, it is also important that other requirements are set for e-cigarettes; such as those laid down in Article  20(3)  paragraphs  (a)  and  (b)  that  ensure  that  e-liquid containers do not contain excessive levels of nicotine (which could be lethal to children and adults).”

On the face of it, this would seem quite sensible. However, consider for a moment that there have been ‘media reports’ of two accidental poisonings globally. Two deaths, no matter how tragic, across the global population do not seem to be an indication that a significant risk exists.  By way of contrast, in the UK alone, in 2013 (the most recent year for which ONS statistics appear to be available) 235 deaths were caused by “Accidental poisoning by and exposure to alcohol”[L]. This would seem to only be plausible where high concentrations of ethanol were involved, but I am unaware of any similar work by the Commission to mandate a safe concentration of ethanol in alcoholic beverages. Two reported deaths (only one of which has been confirmed) globally is a terrible measure for justifying an intervention.

There have been, so far as we are able to determine, no deaths at all relating to accidental dermal exposures.

Then we also need to consider that while there have been two accidental deaths reported globally, there have been none at all in the EU, which is the area where this mandated limit will apply. Currently, concentrations of 7.2% are widely available in the EU (although not in all Member States)

No other benefits (other than, as briefly mentioned earlier, increased sales of refills) occur to us.


The mandated limit will:

Increase the number of people who fail to switch, resulting in an unknown, but greater than zero, number of avoidable deaths. Given that smoking is estimated to result in the premature death of 1 in 2 smokers, this is likely to be a very significant number.

Increase the risk of vaping by an unknown amount, resulting in an unknown, but greater than zero, number of avoidable deaths. This is unlikely to be a significant number, but there is some uncertainty, especially if some of the worst (both in terms of reliability and relative risk) estimates are correct. Even allowing for this, it will be dwarfed by the number of failed switchers for the foreseeable future.

Not reduce the number of deaths occurring in the EU due to accidental oral or dermal exposure, since it is already zero. (It cannot reduce the number of global deaths, since these have all occurred under different regulatory systems). It may prevent an increase in the number of deaths, but given the currently available strengths, and number of users, it is implausible to think that the number will ever be significant.

The only way in which this limit can reduce the overall number of avoidable deaths is if e-cigarette use does not offer any health gains compared with continuing to smoke.

On this basis, it is utterly inexplicable why anyone within Public Health would seek to defend this limit.

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