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expert reaction to conference talk on tobacco products, e-cigarettes, and exposure to carcinogens, being presented at the International Association for Dental Research (IADR) conference

Scientists present an abstract that discusses e-cigarettes and tobacco product use linked to increased risk of oral cancer at the International Association for Dental Research (IADR).


Dr Richard Holliday, NIHR Doctoral Research Fellow, Centre for Oral Health Research, Newcastle University, said:

“This study is being presented on Saturday (28th July 2018) as a poster at the International Association for Dental Research Conference 2018.  The poster abstract describes a study of over 6,000 people who provided urine samples which were tested for the presence of known carcinogens (NNN and NNAL).  The findings describe that e-cigarette users had considerably lower levels of the two carcinogens assessed, compared to current tobacco users (any type).  For example, NNAL was reported to have levels of 869-pg/ml in smokeless tobacco users, 286-pg/ml in tobacco smokers and 4-pg/ml in e-cigarette users.  This is in keeping with much of the current guidance that e-cigarettes are considerably less harmful than tobacco smoking.

“The findings also describe that e-cigarette users who continuing to smoke tobacco (i.e. dual users), had similar levels of carcinogen exposure to tobacco smokers who did not use e-cigarettes.

“The abstract conclusion uses the terminology ‘non-cigarette tobacco users’ which includes both smokeless tobacco users (who showed the highest carcinogen exposure) and e-cigarette users (who showed the lowest carcinogen exposure) and it would have been more appropriate to differentiate these in the conclusion.

“Although carcinogens could be detected in the urine of smokers, the statement (in the title of the press release) that e-cigarette use is linked to oral cancer is not supported by the data presented in this poster abstract.

“I look forward to viewing the full conference poster.”


Prof Paul Aveyard, Professor of Behavioural Medicine, University of Oxford, said:

“This abstract takes its data from a well-conducted national health survey in the US, which has measured exposure to carcinogens (cancer-causing chemicals) in urine.  The study showed that people who used tobacco, whether or oral or smoked tobacco, had high levels of carcinogens, while people who used e-cigarettes without tobacco had very low levels, so this is very reassuring news for people who vape.  However, people who smoked as well as vaped had similar levels of carcinogens to people who just smoked.

“Without access to the peer review paper, it is difficult to put this result in context.  People were classed as a vaper if they had used an e-cigarette once in the past 30 days and this level of vaping, merely trying an e-cigarette, is unlikely to reduce exposure to tobacco carcinogens.  It could be that using an e-cigarette reduces exposure to carcinogens because the nicotine in the e-cigarette partly suppresses the need to smoke.  If heavier smokers were more likely to try vaping, which seems likely, then this could explain this pattern.  We have seen this kind of result in other research, which showed that people who switched from smoking to smoking and vaping reduced their exposure to carcinogen.  When this paper is published properly, we will be able to evaluate it properly.  However, for now we can conclude that stopping smoking and carrying on vaping leads to substantial reductions in exposure to cancer causing chemicals.”


Prof Peter Hajek, Director of the Tobacco Dependence Research Unit, Queen Mary University of London, said:

“The headline of this peculiar press release directly contradicts the actual study findings.  The study did not find levels of carcinogens in vapers that would indicate cancer risk (e.g. 4-pg/mg of NNL compared to 869-pg/ml in smokers; the value for non-smokers is not provided but it is likely to be similar to vapers).  The headline should have been ‘Tobacco products BUT NOT E-CIGARETTES linked to cancer risk’.”


Dr Ed Stephens, Senior Research Fellow, University of St Andrews, said:

“It is misleading to entitle the press release ‘E-cigarettes and tobacco product use linked to increased risk of oral cancer’, it should at least be qualified “Combined e-cigarettes and tobacco product use…”.

“The abstract states that “72% of e-cigarette users also use combustible tobacco and such dual users are exposed high levels of TSNAs”.  The press release acknowledges that “Exclusive e-cigarette users were exposed to lower NNN and NNAL levels than other product users, despite comparable nicotine exposure”.  It follows therefore that 28% of the e-cigarette users surveyed do no use tobacco products and can acquire the same levels of nicotine to satisfy their requirements at much lower levels of TSNA exposure than smokers, and consequently their risk of oral cancer is much lower.

“In brief, the failure to headline the story with “combined” or “dual” use of e-cigs with tobacco could misrepresent the authors’ findings and imply that vaping alone carries a risk of oral cancer comparable to smoking.  The data do not support that conclusion, rather they show quite clearly that vapers who do not smoke have a very much lower risk of oral cancer from TSNAs than those who combine vaping with smoking.  The message for smokers who take up vaping for health reasons is quite clear – quit smoking altogether as quickly as possible.”


* Abstract title: ‘Nicotine and Carcinogen Exposure by Tobacco Product Type and Dual-Use’ by Benjamin Chaffee et al.  This is a conference talk and poster that will be discussed at the 96th General Session of the International Association for Dental Research (IADR) conference on Saturday 28 July 2018.  There is no paper as this is not published work.


Declared interests

Dr Richard Holliday: “I have no conflict of interest to report.”

Prof Paul Aveyard: “No conflicts.”

Prof Peter Hajek: “None.”

Dr Ed Stephens: “I have no interests to declare.”


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