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Smokeless Tobacco and Snus: The Current Evidence for Health Risks
What is Smokeless Tobacco?
Smokeless tobacco, a leaf tobacco product, provides nicotine to users through absorption across the
membranes of the mouth or nose. Two main forms of smokeless tobacco are used in North America:
chewing tobacco and oral snuff. The predominant form is oral snuff, which is sold in powder form as
dipping snuff or in small pre-measured pouches that are placed in the mouth between the cheek and gum.
Swedish snus is a type of oral snuff (see below).
Smokeless tobacco contains sweeteners, flavourings, abrasives, salt and other chemicals. Over two dozen
cancer-causing agents have been identified in traditional smokeless tobacco. The primary carcinogens are
tobacco-specific nitrosamines (TSNAs)1 but the level of TSNAs is affected by processing, refrigeration
and length of storage.2
Health Effects of Traditional North American Smokeless Tobacco
While health risks for smokeless tobacco are lower than for cigarettes, use of smokeless tobacco has a
number of serious health consequences:
An increased risk of oral cancer (up to 50-fold for cheek and gum cancer among long-term users),
Soft tissue lesions including oral leukoplakias, thickened white patches on the cheek, gums or
tongue that can be precursors to cancer,
Periodontal disease, including receding gums, and loss of tooth structure,
Nicotine addiction,
Possible contribution to the development of cardiovascular disease, peripheral vascular disease,
hypertension, peptic ulcers, and fetal morbidity and mortality.
What is Snus?
Snus is the Swedish word for moist snuff. It is manufactured and mainly consumed in Sweden and
Norway. Snus is subjected to a heating treatment process that sharply reduces microorganism content; no
fermentation has been used in its production since 1981. This processing method and refrigerated storage
reduce the formation of nitrates and nitrosamines, resulting in a product low in TSNAs.2
A Recent Systematic Review on Health Effects of Snus
A review of the health effects of Swedish snus was released in New Zealand in March 2007.3 The review
found that snus use is associated with a lower risk of several types of cancer compared to cigarette
smoking and has no significantly increased risk of cardiovascular disease. However, there are several
limitations to the studies discussed below, and there are many unanswered questions about the long term
safety of snus and the role it might play, if any, in reducing smoking.
Among the studies reviewed, certain types of snus use were linked to significantly higher risks of cancer
and heart disease. For example, one study found a two-fold risk of esophageal cancer with moderately
intense snus use; another found a two-fold risk of ischemic heart disease and cardiovascular disease
among middle-aged men who used snus exclusively. Many other findings relating to oral cancer and
stroke do not show statistical significance, but the substantial Odds Ratios (1.7-1.9) are a cause for
concern and suggest the need for larger studies with longer follow-up.
Limitations of the Evidence
The New Zealand review included only twelve studies of Swedish snus: six on cancer and six on
cardiovascular disease, all case-control studies, except for one retrospective cohort study. Small sample
sizes and failure to adequately control for potential confounders, such as cigarette smoking, alcohol use,
or exposure to second hand smoke, limited the findings of some studies. Not included in this review was
a recent large well-controlled retrospective cohort study of snus users that showed a doubling of risk of
pancreatic cancer, but no increased risk of oral or lung cancer compared to those who had never used
tobacco.4
Discussion
Potential health hazards for smokeless tobacco products clearly exist, more so for traditional smokeless
tobacco products. Although snus contains TSNAs at relatively lower levels than conventional smokeless
tobacco, evidence points to increased risk of some cancers and heart disease. Further, there is no
guarantee that products marketed as snus in North America will continue to be processed or stored in the
same way as in Sweden, which could result in increased levels of TSNAs.
The long-term health effects of snus use starting early in life are also unclear. This has become a concern
as new types of smokeless snus are introduced to North America (e.g., Camel Snus, Marlboro Snus,
Taboka), and some of these products are clearly aimed at youth (e.g., Taboka packaging resembles a cell
phone).
Although smokeless tobacco has lower risks than cigarettes, its potential role in reducing smoking is
unknown. Widespread substitution of smokeless tobacco, particularly snus, for cigarettes would likely
reduce the overall health burden of tobacco among continuing tobacco users. Smokeless tobacco is
already widely available and advertised in Canada, yet regular use remains at less than 1%. Heavy
promotion would be required to persuade current smokers to switch, but might encourage new smokeless
tobacco users. In fact, smokeless tobacco has been marketed as an alternative to smoking in places where
smoking is prohibited rather than as a substitute for cigarettes. Few women use smokeless, so this would
not likely be an option for most. Pharmaceutical quitting aids such as nicotine gum, or the patch, provide
nicotine but contain extremely low or no TSNAs5, 6 and are typically used for short periods, while
smokeless use is not usually temporary. Further research is needed to assess the health hazards of various
smokeless tobacco products, their impact on the uptake of smoking and their utility, if any, as an aid to
quitting.
References
1. International Agency for Research on Cancer. Smokeless tobacco and tobacco-specific nitrosamines. In: IARC Monographs
on the Evaluation of Carcinogenic Risks to Humans (Vol 89) Lyon, France: In press 2006.
2. Savitz DA, Meyer RE, Tanzer JM, Mirvish SS, Lewin F. Public health implications of smokeless tobacco use as a harm
reduction strategy. Am J Public Health 2006;93:1934-9.
3. Broadstock M. Systematic review of the health effects of modified smokeless tobacco products. New Zealand Health
Technology Assessment Report 2007;10(1).
4. Luo J, Ye W, Zendehdel K, et al. Oral use of Swedish moist snuff (snus) and risk for cancer of the mouth, lung, and
pancreas in male construction workers: a retrospective cohort study. Lancet 2007;369:2015-20.
5. Stepanov I, Jensen J, Hatsukami D, Hecht SS. Tobacco-specific nitrosamines in new tobacco products. Nicotine Tob Res
2006;8:309-13.
6. Hatsukami DK, Lemmonds C, Zhang Y, et al. Evaluation of carcinogen exposure in people who used "reduced exposure"
tobacco products. J Natl Cancer Inst 2004;96:844-52.
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