18A.3 Health effects of various forms of smokeless tobacco

The health effects of using smokeless tobacco, and the wider public health impact, are a source of debate among the tobacco control community and healthcare professionals. Many smokeless tobacco products contain high concentrations of nicotine and deliver comparable daily systemic doses to those obtained from cigarette smoking, therefore use of smokeless tobacco can be as addictive as smoking cigarettes. Treatment of addiction to smokeless tobacco has proven difficult, with clinical trials of pharmacotherapies often suggesting ineffectiveness;¹ though, a trial of varenicline in smokeless tobacco users has shown promise, with participants reporting high cessation rates.²

Smokeless tobacco also contains a number of known carcinogens, with levels varying based on product characteristics including tobacco type, additives, alkalinity, and processing methods. Exclusive smokeless tobacco users can be exposed to even higher levels of nicotine and toxicants than exclusive cigarette smokers.³ Plant materials such as areca nut or tonka bean, along with other additives, are frequently present in smokeless tobacco products and may also be carcinogenic and have other detrimental health outcomes.⁴

A 2014 report by the National Cancer Institute and Centers for Disease Control and Prevention summarised the available evidence on the health effects of use of smokeless tobacco, drawing the following conclusions:

• The associations between smokeless tobacco use and adverse health effects differ by type of product.
• Smokeless tobacco products cause addiction, precancerous oral lesions, and cancer of the oral cavity, oesophagus, and pancreas, as well as adverse reproductive developmental effects including stillbirth, pre-term birth, and low birth weight.
• The evidence suggests that some, but not all, smokeless tobacco products are associated with increased risk of fatal ischemic heart disease, fatal stroke, and type 2 diabetes; more studies are needed to clarify any causal associations.
• There is insufficient evidence to assess whether smokeless tobacco products are associated with increased risks of lung cancer, cervical cancer, and hypertension.⁴

A 2016 systematic review and meta-analysis similarly concluded that there is an association between ever use of smokeless tobacco and risk of fatal ischaemic heart disease and stroke.⁵ Another 2016 systematic review and meta-analysis—this time exclusively of studies in India, which faces the largest burden of smokeless tobacco-attributable health effects—found significant associations between smokeless tobacco use and oral, pharyngeal, laryngeal, oesophageal, and stomach cancers.⁶ It has been estimated that globally in 2010, smokeless tobacco use led to 1.7 million years of healthy life lost and 62,283 deaths due to cancers of mouth, pharynx and oesophagus, as well as 4.7 million years of healthy life lost and 204,309 deaths from ischaemic heart disease. Over 85 % of this burden was in South-East Asia.⁷

The smokeless tobacco products that are most relevant to the harm reduction debate are those that have been produced to be relatively low in toxins, such as carcinogenic nitrosamines.^8-12 For example, studies of health effects of using Swedish snus—a product with relatively low nitrosamine levels—have found an increased risk of pancreatic and, possibly, esophageal cancer but not of oral or other cancers.1 This risk of pancreatic cancer associated with use of smokeless tobacco is significantly lower than that associated with cigarette smoking.¹³ Similarly, most studies in Sweden show little or no increased risk of cardiovascular disease in snus users^14, 15 and markedly lower rates of lung cancer as a total population compared with other countries. These findings have often formed the basis of arguments for the wider availability of snus as a method of harm reduction; i.e., as a substitute for cigarettes for smokers who are unable to stop using nicotine.¹  

It is also important to note that—in comparison with the extensive research linking smoking with adverse health outcomes—evidence on the health effects of smokeless tobacco is far less comprehensive. Information on dose–response relationships, prevalence estimates, and confounding variables is often sparse, while the novelty of some products may not allow for a full understanding of long-term risks. Comprehensive monitoring of use of smokeless tobacco and its short- and long-term effects on health outcomes are required, particularly in regions with high prevalence.⁴

Relevant news and research

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References 

1. Benowitz N. Smokeless tobacco as a nicotine delivery device: harm or harm reduction? Clinical Pharmacology & Therapeutics, 2011; 90(4):491–3. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21934719

2. Fagerstrom K, Gilljam H, Metcalfe M, Tonstad S, and Messig M. Stopping smokeless tobacco with varenicline: randomised double blind placebo controlled trial. British Medical Journal, 2010; 341(c6549). Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2997603/

3. Rostron BL, Chang CM, van Bemmel DM, Xia Y, and Blount BC. Nicotine and toxicant exposure among US Smokeless tobacco users: Results from 1999 to 2012 national health and nutrition examination survey data. Cancer Epidemiology, Biomarkers & Prevention, 2015. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26582044

4. National Cancer Institute and Centers for Disease Control and Prevention, Smokeless tobacco and public health: a global perspective. NIH publication no. 14-7983. Bethesda, MD: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention and National Institutes of Health, National Cancer Institute; 2014. Available from: http://nccd.cdc.gov/gtssdata/Ancillary/Publications.aspx

5. Vidyasagaran AL, Siddiqi K, and Kanaan M. Use of smokeless tobacco and risk of cardiovascular disease: A systematic review and meta-analysis. European Journal of Preventive Cardiology, 2016. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27256827

6. Sinha DN, Abdulkader RS, and Gupta PC. Smokeless tobacco-associated cancers: A systematic review and meta-analysis of Indian studies. International Journal of Cancer, 2016; 138(6):1368–79. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26443187

7. Siddiqi K, Shah S, Abbas SM, Vidyasagaran A, Jawad M, et al. Global burden of disease due to smokeless tobacco consumption in adults: Analysis of data from 113 countries. BMC Medicine, 2015; 13:194. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26278072

8. Hatsukami DK, Ebbert JO, Feuer RM, Stepanov I, and Hecht SS. Changing smokeless tobacco products: new tobacco delivery systems. American Journal of Preventive Medicine, 2007; 33(suppl. 6 ):S368-S78. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18021912

9. Stepanov I, Jensen J, Hatsukami D, and Hecht SS. Tobacco-specific nitrosamines in new tobacco products. Nicotine & Tobacco Research, 2006; 8(2):309-13. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16766423

10. Hecht SS, Stepanov I, and Hatsukami DK. Major tobacco companies have technology to reduce carcinogen levels but do not apply it to popular smokeless tobacco products [Letter]. Tobacco Control, 2010; 20(6):443. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20930058

11. Stepanov I, Jensen J, Hatsukami D, and Hecht S. New and traditional smokeless tobacco: Comparison of toxicant and carcinogen levels. Nicotine & Tobacco Research, 2008; 10(12):1773–82. Available from: www.ncbi.nlm.nih.gov/pubmed/19023828

12. Stepanov I, Villalta P, Knezevich A, Jensen J, Hatsukami D, et al. Analysis of 23 polycyclic aromatic hydrocarbons in smokeless tobacco by gas chromatography-mass spectrometry. Chemical Research in Toxicology, 2010; 23(1):66-73. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19860436

13. Boffetta P, Hecht S, Gray N, Gupta P, and Straif K. Smokeless tobacco and cancer. The Lancet Oncology, 2008; 9(7):667–75. Available from: http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045%2808%2970173-6/fulltext

14. Boffetta P and Straif K. Use of smokeless tobacco and risk of myocardial infarction and stroke: Systematic review with meta-analysis. British Medical Journal (Clinical Research ed), 2009; 339:b3060. Available from: http://www.ncbi.nlm.nih.gov/entrez/pubmed19690343

15. Hansson J, Galanti MR, Hergens MP, Fredlund P, Ahlbom A, et al. Snus (Swedish smokeless tobacco) use and risk of stroke: Pooled analyses of incidence and survival. Journal of Internal Medicine, 2014; 276(1):87–95. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24548296