By James Dunworth and Paul Bergen
There has been plenty of concern about nitrosamine levels in the e-liquid in e-cigarettes, and whether it has the potential to cause harm. However, when bearing in mind the question of harm from vaping, it's important to compare the levels of any harmful substance to those of cigarettes - as vaping is a form of harm reduction, not harm elimination.
In this post we'll look at the background to the concerns, and what research is telling us about the levels of nitrosamines in e-liquid and vape devices.
Shortly after, headlines across the world stated that electronic cigarettes were as bad as cigarettes - despite the fact that:
- the nitrosamines found were below recommended guidelines
- nitrosamines were also at levels 14,000 times lower than those found in Marlboro cigarettes
- nitrosamines were not detected in the vapour of e-cigarettes, only in the ingredients
- none of the other 56 known carcinogens in tobacco smoke were found in electronic cigarettes
A Little Bit about Nitrosamines
Nitrosamines are a chemical compound. In sufficient quantity these can be carcinogenic.
You’ll already be regularly exposed to nitrosamines and the nitrates that cause them through the food and drink you consume - even drinking water contains nitrates. As you can’t eliminate nitrosamines altogether, governments set maximum allowable amounts.
In the US, the maximum allowed amount in is 60 parts per billion, and in the UK it is 30 parts per billion. (Source: http://www.robac.co.uk/DOC/Nitrosamines_solutions.pdf).
High levels of tobacco specific nitrosamines are found in tobacco cigarettes, and they are one of many known carcinogens in tobacco smoke. (In contrast to electronic cigarette vapour, we still don’t know all the chemicals contained in cigarette smoke, so there may well be more carcinogens we don’t know about.)
Nitrosamines in tobacco cigarettes v. nitrosamines in vape devices
According to studies conducted, most e-cigarettes don’t even seem to contain nitrosamines. In a survey of 16 electronic cigarette studies, Cahn and Siegel (2011) found that just two studies detected trace levels of nitrosamines in the ingredients (but not the vapour) produced by electronic cigarettes. The maximum level of nitrosamines found were 8.2ng/g. Each ng is equal to one billionth of a gram, so the maximum concentration of nitrosamines found was 8.2 parts per billion or 8.2/1,000,000,000.
Cahn and Siegel reported that the nitrosamines in electronic cigarettes were:
...orders of magnitude lower than TSNA levels in regular cigarettes.... electronic cigarettes contain only 0.07–0.2 per cent of the TSNAs present in cigarettes, a 500-fold to 1400-fold reduction in concentration.
An analysis by Professor Siegel came to a similar conclusion, arguing that Marlboro cigarettes contain levels of nitrosamines of 11,190 per billion compared to just over 8 per billion for vaping devices.
That’s at similar level to approved nicotine patches, which weigh in at 8 parts per billion. These have not been linked to cancer. Nitrosamines have also been found at low levels in Scandinavian smokeless tobacco, but a 2009 systematic review by Lee and Hamling couldn't find any link between Scandinavian Snus and cancer. (There did seem to be a link between US tobacco snuff use and oropharyngeal cancer, but as the authors say modern smokeless tobacco products are much safer than older ones.)
Nitrosamines in vapour
But that’s not all. The FDA only tested the contents of e-cigarettes for nitrosamines, not the vapor that smokers inhale. There have been at least two studies which have tested e-cigarette vapour for nitrosamines.
Following the FDA study, Electronic Cigarette company NJOY commissioned independent lab Analyze to test electronic cigarette vapour. The lab found just one nitrosamine present in the vapour - but the nitrosamine was not a toxic one.
The Professor in charge concluded:
Based on my review of scientific literature, NAT is not toxic and not carcinogenic, and based on the vapor analysis, it is my conclusion that TSNAs do not pose a health risk to the users of the electronic cigarettes distributed by NJOY
A 2012 air quality study by McAuley et al comparing vaping to smoking found no traces of nitrosamines. In the words of the authors:
The study indicates no apparent risk to human health from e-cigarette emissions based on the compounds analyzed.
More recent analyses have stated that while there may be nitrosamines in vapour, they are at very low levels. For example, a UK government commissioned report found that in some cases vapour contains nitrosamines - but at levels much lower than in cigarettes.
What does this mean for vapers?
Nitrosamines in vapour are concerning. However, they are at very low levels when compared to vaping. As technology continues to improve, these levels are likely to fall further.
That doesn't mean that vaping is 100% safe, even with the very best devices and e-liquid. There is likely to be at least some harm from long term vaping, and you should never start vaping if you are not a smoker. (As vapers, it is important that we further minimise risk by ensuring that we buy quality devices and e-liquid from reputed manufacturers, and avoid buying illegal e-liquids which will not have undergone the emissions testing required by the UK government.)
However, if you are a smoker and you can't or don't want to quit nicotine use, vaping is likely to be a far less harmful way to use nicotine than combustible tobacco use.
As Professor John Britton, chair of the Tobacco Advisory Group of the Royal College of Physicians, said:
If all the smokers in Britain stopped smoking cigarettes and started smoking e-cigarettes we would save 5 million deaths in people who are alive today. It's a massive potential public health prize.
- Those Evil Nitrosamines (Anti-THR Lies Blog)
- Diethylene Glycol in Electronic Cigarettes - What They Never Told You
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