In this issue, Post and colleagues  present findings from a cross-sectional study of 819 Swedish adolescent tobacco users. This paper presents timely results showing that adolescent concurrent use of snus (Swedish smokeless tobacco) and cigarettes (‘dual use’) is associated with earlier initiation of tobacco use, and greater dependence and withdrawal symptoms compared to exclusive cigarette smokers. Furthermore, exclusive snus users experience similar, if not greater, nicotine dependence and withdrawal symptoms compared to cigarette smokers. This topic is of considerable interest for several reasons. For instance, there has been public health debate, sometimes vitriolic, about the risks and benefits of recommending oral tobacco use as a harm reduction tool among smokers who continue to smoke cigarettes, a more toxic product. Most researchers believe that if a smoker switches completely to an oral tobacco product, the consumer is exposed to fewer toxicants and may reduce tobacco-related morbidity and mortality. However, the population impact of advocating for this approach is of significant concern [2–4]. That is, on a population level, more smokers may continue to use a tobacco product who would have otherwise quit; more adolescents and adults may initiate tobacco use thinking that oral products are safe; some individuals who have achieved abstinence may resume tobacco use; and users of oral tobacco products may be less inclined to quit, as demonstrated in this study, because of their belief that they are using a safe or safer product . Another major concern is that oral tobacco products may serve as a stepping-stone or gateway for cigarette smoking.
Some research conducted in Sweden has shown that the normative use of oral tobacco products and the belief that these products are safer than cigarettes did not enhance cigarette smoking nor deter smoking cessation, and in fact may have reduced the prevalence of smoking [6–9]. However, other studies have shown that increased use of smokeless tobacco in the United States and Norway was not associated with reduced prevalence of smoking [10,11]. Several US cohort studies found that young smokeless tobacco users were more likely than non-smokeless tobacco users to become cigarette smokers [12–14], although a recent US cohort study of adolescents found no such association after matching participants on propensity scores . The findings of Timberlake et al. also suggest that smokeless tobacco use would not likely be ‘protective’ against subsequent smoking if initiation of these forms of tobacco use is associated independently with an underlying risk behavior propensity.
Another, and more critical concern, particularly in light of the results from this study, is the manufacturing and marketing of oral tobacco products to cigarette smokers, which essentially promotes dual use of products. The findings from the present study by Post et al. should serve as a warning of the potential harm that may ensue from these recent marketing efforts, where smokers are encouraged to use oral products in situations that do not allow smoking. This marketing effort may be fostering a generation of new tobacco consumers who use multiple tobacco products and will experience more difficulty quitting than if they used one product exclusively.
As is typical of most studies, the results from this study also raise additional questions. For example, are adolescent dual users comprised of a subpopulation of adolescents who tend to have greater proclivity towards abusing multiple drugs (including alcohol), regardless of marketing forces of tobacco companies or cultural views towards smokeless tobacco products? Do exclusive smokeless tobacco users in fact believe that their products are safer and are less inclined to quit? Is there greater nicotine exposure among the dual adolescent user, and what effects does this increased level have on neuroadaptation to nicotine among adolescents? Does dual use suppress cigarette smoking over time and lead to reduced or greater toxicant burden on the body? What is the trajectory of dual users over time?
The results from this study emphasize the need to proceed cautiously in considering the use of non-combustible oral tobacco as a harm reduction tool. Careful thought needs to be given to the environmental context that surrounds the use of reduced risk or harm reduction products and the potential unintended consequences, particularly the negative consequences among our youth.