By Dr Farsalinos
A new study evaluating passive vaping has recently been published in the journal Environmental Research. The study evaluated nicotine levels in the house of vapers and smokers (compared to non-smokers), and measured salivary and urinary cotinine levels in non-smokers who were exposed to tobacco and electronic cigarette use at their homes. The main finding of the study was that “passive vaping” results in nicotine absorption from non-smokers non-vapers, at similar levels as those exposed to smoke from tobacco cigarettes. Those exposed to more than 7 tobacco cigarettes per day had higher cotinine levels (thus, more nicotine was absorbed through passive exposure).
First of all, there is no surprise that nicotine is released to the environment. Since there is a lot of vapor exhaled, and considering that nicotine absorption is lower compared to smoking, nicotine is probably exhaled by the user (I say probably, because we need more evidence to be certain about that). However, we should assess the health implications of exposure to nicotine at such levels.
Does it mean that passive vaping may lead to nicotine dependence?
Does it mean that nicotine is absorbed to such levels that it may cause harm to bystanders?
The answer to both questions is NO. Passive exposure to electronic cigarette resulted in median salivary cotinine levels of 0.24ng/ml, while in the control group (no exposure to tobacco or electronic cigarette) it was 0.05ng/ml. In smokers, levels of salivary cotinine exceed 300ng/ml, especially in smokers of >20 cigarettes per day. Therefore, the level of cotinine in “passive vapers” is approximately 1200 times lower than active smokers. The same research group measured cotinine levels in smokers few years ago, finding 146ng/ml in smokers of 15 cigarettes per day. This is 610 times higher than the levels in “passive vapers”. Since cotinine is directly associated with the total amount of daily nicotine intake, and assuming that smokers of 15 cigarettes per day get 15mg of nicotine and show 146ng/ml cotinine levels, we can calculate that passive vaping leads to daily nicotine intake of 0.025mg. Such a levels is not only harmless but has absolutely no biological effect, even according to the strictest regulatory definitions.
The European Food Safety Authority (EFSA) has defined the Lowest Observed Adverse Effect Level (LOAEL) of nicotine. This limit has a TOXICOLOGICAL ENDPOINT OF HEART RATE ACCELERATION, which is wrong because heart rate acceleration does not imply any long-term adverse effect. According to the definition, NOAEL (which is a much lower level compared to LOAEL) is defined as: ““An exposure level at which there are no statistically or biologically significant increases in the frequency or severity of adverse effects between the exposed population and its appropriate control. Some effects may be produced at this level, but they are not considered as adverse, nor precursors to adverse effects”. Thus, the definition by EFSA it is not in reality a LOAEL (or even a NOAEL), but much lower than that. The level set by EFSA was 0.008mg/kg body weight for ingestion, derived from calculations of intravenous nicotine injections, which found that administering 0.0035mg/kg body weight produced an acute acceleration in heart rate. For an average 75kg human, that is 0.26mg (10 times higher than the calculated 0.025mg/day intake from passive e-cigarette exposure).
In conclusion, the levels of nicotine absorbed from “passive vaping” are not only harmless but do not even produce any biological effect (not even heart rate acceleration). Considering the possibility that allowing e-cigarette use in public places may motivate smokers to switch to e-cigarette use, there is no scientific basis for any bans on e-cigarette use in public places.