Nicotine in electronic cigarettes: what are the health risks?
Some electronic cigarette clearomizers contain nicotine. Does the nicotine found in e-cigarettes lead to/sustain addiction or does it have the same effect as nicotine substitutes? Does the presence of nicotine have harmful consequences for the user or for those around them? These questions are still under discussion but initial studies are able to provide some answers.
The presence of nicotine in electronic cigarettes
Electronic cigarettes release nicotine in aerosol form in order to recreate the same experience as when smoking a real cigarette, which is why the FDA considers them to be inhalers. The nicotine content is indicated on the cartridge label either by volume (ml), by mg contained in the cartridge, or by mg/ml (or in %) in the e-liquid. You can find e-cigarette cartridges with different levels of nicotine: weak (6-8 mg/ml), medium (10-14 mg/ml), high (16-18 mg/ml), very high (24-36 mg/ml). The most recent e-cigarettes present nicotine levels which are more often than not close to the amount indicated and most of them use pharmaceutical-quality nicotine.
The European Union recently issued a new regulation which establishes a maximum nicotine level of 20 mg/ml in liquids used for electronic cigarettes. It should also be noted that the new generation of electronic cigarettes have more powerful atomizers which allow for a more efficient distribution of nicotine, which again raises the question of possible addiction to electronic cigarettes.
E-cigarettes with nicotine: risk of addiction?
One of the key questions regarding electronic cigarettes containing nicotine, is whether they can in fact create addiction.
We know that nicotine inhaled through smoking can be heavily addictive if it’s delivered in a shot (fast arrival in the brain) as is the case with cigarettes (nicotine is carried to the brain in less than 10 seconds). As far as e-cigarettes are concerned, we presume that they have a higher addictive potential than nicotine substitutes but we still don’t know whether the nicotine reaches the brain as quickly as with traditional cigarettes. Studies show that the way into the bloodstream is slower with electronic cigarettes than with classic cigarettes, even if the nicotine content is identical (1, 2, 3). A very recent study concluded that electronic cigarettes, even those known as new generation, carry considerably lower concentrations of nicotine into the bloodstream than in the case of traditional cigarettes; you would need 35 minutes of vaping to get similar levels of nicotine into the blood as to that obtained when smoking a cigarette. (4)
However, other studies (5, 6) have noted an increase in nicotine levels in the blood of regular e-cigarette users in less than 5 minutes after the first puff. Dawkins et al reported an increase of 0.74 mg/ml in blood nicotine levels, 10 minutes after 10 puffs on an electronic cigarette. (7) The Vansickel study from 2013, made with current e-cigarettes, found a nicotine level of 11 mg/ml in the blood after 5 minutes, close to the level found with classic cigarettes. (8) Another study carried out in 2013 by Flouris, focused on 15 smokers who alternated cigarettes and e-cigarettes on different days, showed the same levels of cotinine (metabolite of nicotine). (9) These differing results can probably be partly explained by the fact that a number of factors affect the amount of nicotine released by an electronic cigarette: the initial dose of nicotine, the efficiency of the vaporization process which determines the quantity of nicotine and the way the smoker draws on the e-cigarette (10). A recent study has actually shown, for example, that some experienced users of electronic cigarettes seem to be able to absorb as much nicotine from these products as smokers do from their cigarettes. (11)
If these recent studies provide evidence that the nicotine in e-cigarettes is released in a shot, there is a real risk that the explosion in the use of electronic cigarette will increase the amount of nicotine addiction, in particular in young people who are attracted by the different flavours available with e-cigarettes. The anti-smoking associations also fear that electronic cigarettes with nicotine could instigate nicotine addiction in young people.
Electronic cigarettes with nicotine: a health risk?
We are not in a position today, to declare that electronic cigarettes don’t present a health risk. Nicotine coming from smokeless tobacco products is known to produce endolethial dysfunction (in the blood vessels) and systemic inflammation. (12) Cases of thrombogenesis as well as other metabolic effects have also been shown. (13)
There is also the question of knowing whether passive vaping presents risks. Anyone in the same room as a vaper is exposed to chemical products in gas form (nicotine and other gases). A recent study by Flouris has shown that the level of cotinine (metabolite of nicotine) in the blood is identical, whether it’s caused by cigarette smoke or e-cigarette vapour. (14) We don’t yet know the consequences of this kind of exposure on health: research is needed to evaluate the health effects from this kind of passive nicotine exposure, in particular concerning groups at risk (children, pregnant women, people suffering from vascular and cardiovascular disease). However, one study has shown that non-smokers who inhale nicotine (0-64 mg/ml) presented more coughing and obstruction of the respiratory tract, relative to the dose they’re exposed to.
E-liquids containing nicotine can, after all, present a risk of nicotine intoxication. A 5 ml refill can contain 20 mg/ml of nicotine whilst we know that the lethal dose of nicotine has been estimated at 10 mg for a child and between 30 and 60 mg for an adult. So, accidental contact with the skin or accidental absorption by a child or pet could have very serious consequences. Thus, a level of 10 mg of nicotine could be fatal for a child (16).