Doctors should state clearly that vaping is much lower risk than smoking, says reportBMJ 2018; 360 doi: https://doi.org/10.1136/bmj.k575 (Published 06 February 2018) Cite this as: BMJ 2018;360:k575
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We fully agree with the view of Jacqui Wise(1) that vaping carries much lower risk than smoking. In addition, from the viewpoint of occupational medicine and toxicology, we would like to refer to further facts not mentioned in the reviewed report that clearly back this perspective based on the example of urinary bladder cancer.
Traditional tobacco smoke contains several thousand constituents and more than 60 carcinogenic substances, according to IARC.(2) Many of them, particularly carcinogenic aromatic amines (AA) like 2-naphthylamine and 4-aminobiphenyl and polycyclic aromatic hydrocarbons (PAHs) are combustion products not detected in vapours of e-cigarettes and only in very small amounts in aerosol of tobacco heating systems (THS).(3,4,5) Thus, we also support the key issue that toxic smoke from combustion processes is the most important factor regarding tobacco associated cancers. However, it should be mentioned that smokeless tobacco use like chewing tobacco is not without cancer risk, as shown by a large Swedish study.(6) Urinary bladder cancer, the 4th leading cancer in men and the 10th leading cancer in women in Western Europe(7), is currently associated with tobacco smoking in about 50% of all cases in males and, according to a recent large study in the US, now also in women.(8) The substances contributing to this disease are carcinogenic AA particularly 2-naphthylamine and 4-aminobiphenyl and PAHs.
It is of utmost importance to stress that tobacco leaves do not contain the aforementioned carcinogenic AA.(9) They are generated by combustion processes of tobacco leaves(9) contributing to bladder cancer in smokers but also by combustion in the absence or near absence of oxygen of other organic material such as coal, responsible for the increased bladder cancer risk of coke oven workers.(10) The same is true for most PAHs. In contrast, carcinogenic nitrosamines are constituents of processed tobacco leaves but do not cause urinary bladder cancer.(5) This is of importance for smokers quitting smoking with the help of e-cigarettes or THSs as they are no longer exposed to significant amounts of AA or PAHs, the most relevant constituents of tobacco smoke in urinary bladder carcinogenesis.
For the motivation of smokers to quit smoking, mention should be made to the observation that quitting smoking is associated with a decline in urinary bladder cancer risk of over 30% after 1-4 years of quitting.(11) Should vaping continue to replace smoking to a greater extent this will most likely lead to a considerable reduction in bladder cancer cases. Furthermore, it is known that different genetic variants and their combinations confer susceptibility of smokers, non-smokers and former smokers to bladder cancer.(12) The most important genetic variants in current smokers are involved in the detoxification of carcinogens in cigarette smoke. Most prominent is the homozygous deletion of the glutathione S-transferase M1 (GSTM1) gene involved in the metabolism combustion products. We predict that the proportion of GSTM1 negative bladder cancer cases will decrease, similar to the reduction of GSTM1 negative bladder cancer cases after the final closure of the combustion products emitting coal, iron and steel industries in Dortmund/Germany.(13) Therefore, the advent of vaping, besides producing substantial health benefits, also represents the chance of a huge ‘intervention study’ for researchers.
Head Clinical Occupational Medicine
Physician, Clinical Occupational Medicine
Jan G. Hengstler
Leibniz Research Centre for Working Environment and Human Factors (IfADo), Ardeystr. 67, 44139 Dortmund, Germany
Correspondence to firstname.lastname@example.org
1. Wise J. Doctors should state clearly that vaping is much lower risk than smoking, says report. BMJ 2018 360:k575.
2. IARC Monographs on the Evaluation of Carcinogenic Risks to Human. IARC Monographs, Volume 83 Tobacco Smoke and Involuntary Smoking. https://monographs.iarc.fr/ENG/Monographs/vol83/mono83.pdf. (accessed 16 February 2018).
3. Margham J, McAdam K, Forster M, et al. Chemical composition of aerosol from an e-cigarette: a quantitative comparison with cigarette smoke. Chem Res Toxicol 2016, 29:1662–78.
4. Hutzler C, Paschke M, Kruschinski S, et al. Chemical hazards present in liquids and vapors of electronic cigarettes. Arch Toxicol 2014; 88:1295-308.
5. Schaller JP, Pijnenburg JP, Ajithkumar A, Tricker AR. Evaluation of the Tobacco Heating System 2.2. Part 3: Influence of the tobacco blend on the formation of harmful and potentially harmful constituents of the Tobacco Heating System 2.2 aerosol. Regul Toxicol Pharmacol 2016;81 Suppl 2:S48-S58.
6. Boffetta P, Aagnes B, Weiderpass E, Andersen A. Smokeless tobacco use and risk of cancer of the pancreas and other organs. Int J Cancer 2005; 114:992-5.
7. IARC International Agency for Research on Cancer. Cancer Today http://gco.iarc.fr/today/online-analysis-multi-bars?mode=cancer&mode_pop... (accessed 16 February 2018).
8. Freedman ND, Silverman DT, Hollenbeck AR, et al. Association between smoking and risk of bladder cancer among men and women. JAMA 2011; 306:737-45. Erratum in: JAMA 2011; 306:2220.
9. Rodgman A, Perfetti TA. The Chemical Components of Tobacco and Tobacco Smoke. Boca Raton, FL: Second Edition, CRC Press 2013.
10. Golka K, Wiese A, Assennato G, Bolt HM. Occupational exposure and urological cancer. World J Urol 2004; 21:382-91.
11. Brennan P, Bogillot O, Cordier S, et al. Cigarette smoking and bladder cancer in men: a pooled analysis of 11 case-control studies. Int J Cancer 2000; 86:289-94.
12. Selinski S, Blaszkewicz M, Ickstadt K, et al. Identification and replication of the interplay of four genetic high-risk variants for urinary bladder cancer. Carcinogenesis 2017; 38:1167-79.
13. Ovsiannikov D, Selinski S, Lehmann ML, et al. Polymorphic enzymes, urinary bladder cancer risk, and structural change in the local industry. J Toxicol Environ Health A 2012; 75:557-65.
Competing interests: No competing interests
We read with interest the Public Health England (PHE) commissioned report on e-cigarettes1 highlighted in your news article2 and were struck by its relatively permissive stance on key health issues when compared to the contemporaneous US report3.
The PHE review recommends that “e-cigarette use, alone or in combination with licensed medication and behavioural support from a Stop Smoking Service, appear to be helpful in the short term”1. In contrast, the US review has said that “there is insufficient evidence from randomized controlled trials about the effectiveness of e-cigarettes as cessation aids compared with no treatment or… smoking cessation treatments” 3. Furthermore, while the PHE review says that “e-cigarettes are attracting very few young people who have never smoked into regular use”1, the US report concludes that “there is substantial evidence that e-cigarette use increases risk of ever using combustible tobacco cigarettes among youth and young adults”3.
Both reports corroborate the purported overall reduction in harm afforded by e-cigarettes compared to conventional tobacco cigarettes1,3. However, while the US reviewers suggest, with a notable degree of caution, that “there is no available evidence whether or not e-cigarette use is associated with clinical cardiovascular outcomes… and respiratory diseases in humans” 3, the UK reviewers confidently conclude, in the absence of long-term follow-up data, that these putative risks are likely to be “substantially below” those of smoking1. Moreover, the US review asserts that “there is no available evidence whether or not e-cigarette use is associated with intermediate cancer endpoints in humans”3. Yet the UK reviewers promote the finding that “the cancer potencies of e-cigarettes” are “largely under 0.5% of the risk of smoking”1,4.
Who should be believed? We respectfully submit that this disparity of opinion, existing as it does amongst tobacco experts, reflects the wider degree of uncertainty that currently surrounds the long-term health risks of e-cigarettes. We therefore find it astonishing that PHE, a body whose raison d’être is “to protect and improve the nation's health and wellbeing”5, should endorse e-cigarette use at the population level. At a time when 112 out of 135 Acute NHS Trusts are in financial deficit6, a decision for the NHS to invest in e-cigarettes on the basis of, at best, an embryonic and inconclusive evidence base appears all the more perplexing. Finally, the UK report repeats the now widely publicised argument that “vaping is at least 95% less harmful than smoking” and includes the caveat that “this does not mean e-cigarettes are safe”1. For the aforementioned reasons, we believe that the PHE report represents an unwarrantedly premature, evidence-deficient endorsement of e-cigarettes to the smoking public.
1. McNeill A, Brose LS, Calder R, Bauld L & Robson D (2018). Evidence review of e-cigarettes and heated tobacco products 2018. A report commissioned by Public Health England. London: Public Health England.
2. Wise J. Doctors should state clearly that vaping is much lower risk than smoking, says report, BMJ 2018; 360 doi: https://doi.org/10.1136/bmj.k575
3. National Academies of Sciences, Engineering, and Medicine. 2018. Public health consequences of e-cigarettes. Washington, DC: The National Academies Press. doi:https://doi.org/10.17226/24952
4. Stephens WE. Comparing the cancer potencies of emissions from vapourised nicotine products including e-cigarettes with those of tobacco smoke. Tobacco Control 2018;27:10-17.
5. Public Health England Website. Available at: https://www.gov.uk/government/organisations/public-health-england/about. [Accessed 13 February 2018].
6. Quarterly performance of the NHS provider sector: quarter 2 2017/18. NHS Improvement. Available at: https://improvement.nhs.uk/resources/quarterly-performance-nhs-provider-... [Accessed 14 February 2018]
Competing interests: No competing interests