Should doctors advocate snus and other nicotine replacements? No
BMJ 2008; 336 doi: https://doi.org/10.1136/bmj.39479.491319.AD (Published 14 February 2008) Cite this as: BMJ 2008;336:359
The use of smokeless tobacco products—–notably snus—has suddenly become controversial. Reasons for this include publicity by the tobacco industry,1 the introduction in England of a ban on smoking in public places,2 recent interest by major multinational companies in acquiring manufacturers of smokeless tobacco products,3 and the publication of comprehensive reports by a scientific committee of the European Commission4 and the Royal College of Physicians of London.5
Last October the British American Tobacco Company pressed the European Union to reconsider its 1992 ban on snus,1 from which Sweden secured an exemption when it joined the union. Three weeks later the European Parliament called on the commission “to investigate the health risks associated with the consumption of snus and its impact on the consumption of cigarettes.”6
What is snus?
Snus is the Swedish word for snuff, which was fashionable to inhale before cigarettes superseded it.
BAT describes snus as “A finely ground moist tobacco, either loose or in tiny sachets—a bit like tiny teabags—that are placed under the upper lip and typically held in the mouth for about 30 minutes before being discarded.”1
Health hazards
Epidemiological studies of the effects of snus are often undermined because it is commonly used along with smoked tobacco and alcohol.7 Different lifestyle factors and patterns of use in different countries preclude any Cochrane-style meta-analysis, but the two recent reports summarise the current state of knowledge.4 5
The expert group of the International Agency for Research on Cancer has concluded that smokeless tobacco is carcinogenic to humans,8 and the European Commission report cites studies by the Swedish Institute of Public Health and the Karolinska Institute as evidence that snus is carcinogenic.9
The obvious entry point to research on snus is the oral cavity. Mucosal changes, known as snus induced lesions or leucoplakia, are inevitable and potentially precancerous with a gradient in severity suggesting a dose response.10 Lesions in the local epithelium are reversible on quitting but gingival retractions are not.
In India, a 10 year follow-up study has shown that oral cancers invariably arise from pre-existing leucoplakia.11 In the US, oral cavity cancer was found in patients who were exclusive users of smokeless tobacco and who had no exposure to alcohol.12 Studies in India, Pakistan, and the Sudan reported large increases in the risk for oral cancers related to the use of various smokeless tobacco products,4 and the International Agency for Research on Cancer has stated, “There is sufficient evidence that smokeless tobacco causes oral cancer.”8
There is particularly strong evidence of a causal relation between smokeless tobacco and pancreatic cancer, notably from the Swedish construction workers cohort13 and the Lutheran brotherhood cohort in the US.14
The INTERHEART study covering 52 countries showed an increased risk of cardiovascular disease in all forms of tobacco combined.15 A recent follow-up of a large US cohort showed that compared with men who had never used any tobacco product, men who quit tobacco use entirely or switched to smokeless products had significantly higher relative risks of cardiovascular disease, particularly the switchers.16 The EC report concluded that smokeless tobacco has a significant effect on myocardial infarction.4
A cohort study based on the Swedish Birth Registry showed an increased risk of premature birth and pre-eclampsia among snus users compared with non-users of any tobacco.17
Nicotine exposure
Smokeless tobacco delivers quantities of nicotine comparable to those typically absorbed from cigarette smoke and is addictive, although unarguably less so than smoked tobacco. Nicotine levels obtained from snus are about twice as high as those obtained from nicotine replacement therapy, which does not induce dependence.4 Moreover, at least 60% of people who use snus to quit smoking become chronic snus users.4 However, Action on Smoking and Health asks whether snus is the new way to give up smoking.18 The royal college’s report also envisages “harm reduction” by providing safer sources of nicotine, but within the context of a nicotine regulatory authority.5
Citing various experts, the European report argues, “If snus or other STP can provide some of the smokers who cannot otherwise quit smoking with a less hazardous source of nicotine that is acceptable to them, then the use of snus as a harm reduction option deserves consideration . . . if, on the other hand, the availability of snus has little impact on smoking prevalence but adds further tobacco users to the existing population, as appears to have existed in Norway, there would be no benefit but an adverse impact on public health by allowing snus use.”4 I fear the second outcome. If legalised, snus might be taken up by people, especially the young, who might never have smoked tobacco but who may then progress to doing so.
BAT admits “smokeless does not mean harmless and the best way to avoid the risks associated with consuming tobacco is not to consume it at all.”1 A harm reduction policy could instead lead to harm perpetuation.
The tobacco industry’s constant defence is that tobacco is a legal product. But if we had known before tobacco was ever used, how disastrous it would prove to be, would it not have been banned in all its forms?
Footnotes
Competing interests: AWM chaired a programme development group for NICE on smoking cessation, the conclusions of which will be published on 23 February.