Smokeless tobacco, such as snuff or chewing tobacco, has been suggested as a potential aid to harm reduction or smoking cessation. Smokeless tobacco products contain nitrosamines and other carcinogens, and are known to produce oral and pancreatic cancer (IARC, 2007). Smokeless tobacco products are addicting. At this time smokeless tobacco is not recommended as an aid to smoking cessation.

Smokeless tobacco, such as snuff or chewing tobacco, has been suggested as a potential aid to harm reduction or smoking cessation. Smokeless tobacco products contain nitrosamines and other carcinogens, and are known to produce oral and pancreatic cancer (IARC, 2007). Smokeless tobacco products are addicting. At this time smokeless tobacco is not recommended as an aid to smoking cessation.

Strength of evidence: A

Commentary and supporting evidence
Smokeless tobacco, such as snuff or chewing tobacco, has been suggested as a potential aid to harm reduction or smoking cessation, but this view is not consensual (Gartner et al., 2007; Hatsukami et al., 2007; Kozlowski et al., 2007; Martinet et al., 2007; Mendoza-Baumgart et al., 2007; RCP, 2007; Stead & Lancaster, 2007; Tomar et al., 2007).

The US Surgeon General and the International Agency for Research on Cancer have concluded that smokeless tobacco, and especially snuff-dipping, induces gingival recession, pre-cancerous lesions of the oral cavity, oral cavity and pancreatic cancer (IARC, 1998; 2007; US. Surgeon General, 1986).

Smokeless tobacco products contain carcinogens, such as nitrosamines, formaldehyde, crotonaldehyde, benzo[a]pyrene and other polycyclic aromatic hydrocarbons, and polonium-210 (Hecht, 1998; Stepanov et al., 2007). Among these, the tobacco-specific nitrosamines N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are clearly the most prevalent, strong carcinogens in smokeless tobacco, and are likely to play a significant role in oral and pancreatic cancer induction by these products. Levels of NNN plus NNK in smokeless tobacco products sold in the US average 2-5 µg/g dry weight of tobacco and are far greater than nitrosamine levels in any other consumer product (Hecht, 1998; Hoffmann et al., 1995; Stepanov et al., 2007). However, the composition of smokeless tobacco products varies from country to country. In some countries, smokeless tobacco use appears to have a different toxicity profile than in other countries. Amounts of NNN plus NNK in some Swedish snuff products are lower than those sold in the US, but the levels of these carcinogens are not insignificant (Osterdahl, 1991; Stepanov et al., 2006, 2007). Studies of cancer incidence among Swedish snuff users find a 2-fold increase risk of pancreatic cancer, but no increased risk of other cancers.

Most studies find no increased risk of cardiovascular disease in Swedish snus users. The use of snus among Swedish women during pregnancy has been associated with an increased risk of pre-term delivery, low birth weight and pre-eclampsia (England et al., 2003). Controlled trials demonstrating the efficacy of smokeless tobacco to aid in cessation are lacking. In view of these facts, smokeless tobacco must be considered unsafe and cannot be recommended as an aid to smoking cessation. 

1. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. IARC Monographs Vol. 89. Smokeless Tobacco and Some Tobacco-specific N-Nitrosamines. 2007. ISBN 978 92 832 1289 8.
2. Gartner CE, Hall WD, Vos T, Bertram MY, Wallace AL, Lim SS. Assessment of Swedish snus for tobacco harm reduction: an epidemiological modelling study. Lancet, 2007; 369: 2010-2014.
3. Hatsukami DK, Ebbert JO, Feuer RM, Stepanov I, Hecht SS. Changing smokeless tobacco products new tobacco-delivery systems. Am J Prev Med, 2007; 33(6 Suppl): S368-S78.
4. Kozlowski LT. Effect of smokeless tobacco product marketing and use on population harm from tobacco use policy perspective for tobacco-risk reduction. Am J Prev Med, 2007; 33(6 Suppl): S379-S386.
5. Martinet Y, Bohadana A, Fagerström K. Introducing oral tobacco for tobacco harm reduction: what are the main obstacles? Harm Reduct J, 2007; 4: 17.
6. Mendoza-Baumgart MI, Tulunay OE, Hecht SS, Zhang Y, Murphy S, Le C, Jensen J, Hatsukami DK. Pilot study on lower nitrosamine smokeless tobacco products compared with medicinal nicotine. Nicotine Tob Res, 2007; 9: 1309-1323.
7. Royal College of Physicians. Harm reduction in nicotine addiction. Helping people who can't quit. A report by the Tobacco Advisory Group of the Royal College of Physicians; 2007.
8. Stead LF, Lancaster T. Interventions to reduce harm from continued tobacco use. Cochrane Database Syst Rev, 2007; (3): CD005231.
9. Tomar SL. Epidemiologic perspectives on smokeless tobacco marketing and population harm. Am J Prev Med, 2007; 33(6 Suppl): S387-S397.
10. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. IARC Monographs Vol. 37. Tobacco Habits other than Smoking; Betel-Quid and Areca-Nut Chewing; and some Related Nitrosamines. 1998. ISBN 92 832 1537 0.
11. U.S. Department of Health and Human Services. The Health Consequences of Using Smokeless Tobacco. A report of the Surgeon General. U.S. Department of Health and Human Services, Public Health Services, Office on smoking and health. NIH Publication No. 86-2874 , 1986.
12. Hecht SS. Biochemistry, biology, and carcinogenicity of tobacco-specific N-nitrosamines. Chem Res Toxicol, 1998; 11: 559-603.
13. Stepanov I, Jensen J, Hatsukami D, Hecht SS. New and traditional smokeless tobacco: comparison of toxicant and carcinogen levels. Nicotine Tob Res, submitted, 2007.
14. Hoffmann D, Djordjevic MV, Fan J, Zang E, Glynn T, Connolly GN. Five leading U.S. commercial brands of moist snuff in 1994 – Assessment of carcinogenic N-nitrosamines. J Natl Cancer Inst, 1995; 87: 1862-1869.
15. Osterdahl B-G. Occurrence of and exposure to N-nitrosamines in Sweden: a review. In Relevance to Human Cancer of N-Nitroso Compounds, Tobacco Smoke, and Mycotoxins, 1991; pp.235-237. Edited by IK O'Neill, JS Chen and H Bartsch. (not available on-line)
16. Stepanov I, Jensen J, Hatsukami D, Hecht SS. Tobacco-specific nitrosamines in new tobacco products. Nicotine Tobacco Res, 2006; 8: 309-313.
17. England LJ, Levine RJ, Mills JL, Klebanoff MA, Yu KF, Cnattingius S. Adverse pregnancy outcomes in snuff users. Am J Obstet Gynecol, 2003; 189: 939-943.