Among all tobacco users in this study, harm elimination through the cessation of tobacco use following a protracted smoking ban was common, with 23.7% of baseline smokers and 38.9% of baseline smokeless tobacco users abstinent at follow-up. However, harm escalation occurred more frequently than did harm reduction. Overall, tobacco users who began using smokeless tobacco were more than 5 times more likely to demonstrate harm escalation than harm reduction. Harm reduction was more likely among baseline smokers and dual users who had higher family incomes and who believed that switching from cigarettes to smokeless tobacco provides a health benefit. Harm escalation was more prevalent among risk-taking younger men with a longer smoking history and any alcohol intake just prior to basic military training.
Consistent with the findings of other studies of this type, harm elimination following long bouts of forced abstinence was common in our study.19,20
Our data are very similar to those from an analysis of the 2002 and 2003 Tobacco Use Supplement to the Current Population Survey (TUS-CPS).22
In both our study and the TUS-CPS, (1) quitting rates were lower for cigarette smoking than for smokeless tobacco use at the 1-year follow-up, (2) exclusive cigarette use was a more stable pattern of tobacco use than were smokeless tobacco use or dual use, (3) switching from one type of tobacco use to another was infrequent and was more likely to be from smokeless tobacco to cigarettes than from cigarettes to smokeless tobacco, (4) harm reduction (i.e., from smoking or dual use to smokeless tobacco only) was much less common than harm escalation (i.e., from smoking or smokeless tobacco use to dual use). Our finding that dual users were the most likely of the groups to switch tobacco use patterns and the least likely to report nonuse at follow-up was also consistent with previous studies.26,27
Considered together, these data would suggest that in the United States, harm escalation may lower the probability of becoming tobacco abstinent if smokers become dual users. This escalation is a possible unintended consequence of promoting smokeless tobacco as a harm reduction strategy for smokers.
Our observation that harm escalation (i.e., from smoking to dual use) was more likely among men than women is not unexpected. This observation is consistent with the low prevalence of overall smokeless tobacco use among women,29
which is likely related to cultural norms in the United States pertaining to smokeless tobacco use. Even in Sweden, where smokeless tobacco use is prevalent (20% of adult males use smokeless tobacco)30
and holds unique historical and cultural significance, the prevalence of smokeless tobacco use among women is low.20
In a study assessing tobacco quitting or switching in the TUS-CPS, smokeless tobacco use among women was low and no women demonstrated harm reduction.22
Our findings and those of other investigators suggest that a harm reduction strategy using smokeless tobacco would have little or no impact on women in the United States.
A public health policy promoting a harm reduction approach with smokeless tobacco may require a more complete understanding of the demographics, behaviors, and knowledge of individuals who may be vulnerable to harm escalation. We observed that harm escalation was more prevalent among risk-taking younger men who had longer smoking histories and had reported recent alcohol intake just prior to basic military training. In a cross-sectional analysis of the Working Well Trial study population, dual users (of cigarettes and smokeless tobacco) were more likely to be younger, unmarried, and White and to have lower levels of education than were cigarette smokers, but to be similar in age and race/ethnicity to smokeless tobacco users.27
Dual users in the Working Well Trial population also drank more alcohol and were more likely than were cigarette smokers or smokeless tobacco users to live with a smoker. Importantly, dual users were less likely to become tobacco abstinent than were smokers or smokeless tobacco users, and whereas traditional indicators of tobacco dependence (e.g., smokeless tobacco use per day or cigarettes per day) predicted abstinence from smokeless tobacco and cigarettes, those indicators did not predict abstinence from dual use. Random-digit-dialing surveys in Australia, Canada, the United Kingdom, and the United States suggest that smokers in the United States are the least likely to believe that smokeless tobacco is less harmful than are cigarettes.30
Although this belief may indeed reflect a “major failing of public education about the relative harms of tobacco products,”30(p1039)
we submit that any public health campaign must disclose any potential harm escalation associated with dual use.18
We did observe that airmen who believed that smokeless tobacco use was less harmful than cigarettes were more likely to demonstrate harm reduction. In the current environment in the United States, however, our data and that of other investigators suggest that harm escalation is the more probable use pattern among cigarette smokers.
Our study is strengthened by the prospective design, the large sample size, the young age, the ability to observe tobacco reinitiation after a period of forced abstinence in basic military training, and the high representation of minorities and individuals with low incomes. Our study is limited because it uses a military population with only 1 year of follow-up. Furthermore, because our study involved forced tobacco abstinence, our findings may not apply to a population of smokers presenting for treatment. It is also important to note that our study participants were military personnel who tended to be predominantly young, male, from lower-income families, and predominantly racial/ethnic minorities. Whether our findings generalize to a civilian population is unknown and should be the focus of additional research. However, our study results were consistent with results of other studies in the literature that have used civilian samples.
Despite study limitations, we provide important additional information to the debate over a harm reduction approach to smoking that incorporates the use of smokeless tobacco. In our control sample, a significant number of smokers were able to quit, but these smokers were also more likely to demonstrate harm escalation than harm reduction. Future studies should also evaluate the relative health risks of harm escalation versus reduction. Before embarking on a public health education program promoting smokeless tobacco use for smokers, the tobacco control community needs to carefully weigh the likelihood and benefits of switching cigarette smokers to exclusive smokeless tobacco use against the risk of having smokers become dual users and thereby increasing rather than decreasing the adverse health consequences of tobacco use.