摘要：Objectives. We evaluated changing patterns of tobacco use following a period of forced tobacco abstinence in a US military cohort to determine rates of harm elimination (e.g., tobacco cessation), harm reduction (e.g., from smoking to smokeless tobacco use), and harm escalation (e.g., from smoking to dual use or from smokeless tobacco use to smoking or dual use). Methods. Participants were 5225 Air Force airmen assigned to the health education control condition in a smoking cessation and prevention trial. Tobacco use was assessed by self-report at baseline and 12 months. Results. Among 114 baseline smokers initiating smokeless tobacco use after basic military training, most demonstrated harm escalation (87%), which was 5.4 times more likely to occur than was harm reduction (e.g., smoking to smokeless tobacco use). Harm reduction was predicted, in part, by higher family income and belief that switching from cigarettes to smokeless tobacco is beneficial to health. Harm escalation predictors included younger age, alcohol use, longer smoking history, and risk-taking. Conclusions. When considering a harm reduction strategy with smokeless tobacco, the tobacco control community should balance anticipated benefits of harm reduction with the risk of harm escalation and the potential for adversely affecting public health. Cigarette smoking is the number 1 preventable cause of death and disability in the United States. 1 , 2 Although a vast array of smoking cessation strategies exist, 3 nearly 20% of the US population are current smokers. 4 Impeding efforts for a tobacco-free society are the facts that nicotine is highly addictive 5 and, at any given time, only about 20% of smokers are ready, willing, or able to make a serious attempt to stop smoking. 6 Although research efforts are under way to evaluate the efficacy of approaches for smokers not ready or able to quit (e.g., motivational interviewing), 7 no method has demonstrated success. An alternative approach to providing treatment to smokers unable to quit is to “reduce the harm” associated with cigarette smoking. 8 Proposed harm reduction strategies have included risk factor modification (e.g., dietary intake and physical activity) and chemoprevention strategies (e.g., antioxidants). 9 However, the most controversial method of harm reduction is encouraging smokers to switch from cigarette smoking to other forms of tobacco, such as smokeless tobacco, 10 , 11 a known human carcinogen. 12 , 13 Although switching from cigarettes to smokeless tobacco reduces risk related to heart disease and lung cancer, 14 , 15 critics of this strategy suggest that harm reduction may be associated with unintended consequences. A recent review by Tomar et al. concluded that the effectiveness of smokeless tobacco as a smoking-cessation strategy remains unknown and that available evidence suggests that smokeless tobacco use may be a gateway to smoking initiation in the United States. 16 Furthermore, promoting smokeless tobacco for harm reduction has the potential to increase harm by opening the door to dual use of cigarettes and ST, with the latter used in venues where smoking is prohibited; this could undermine cessation attempts. 16 , 17 In the INTERHEART study, an international case–control study, dual use (i.e., concomitant use of cigarettes and smokeless tobacco) was associated with higher odds for acute myocardial infarction than was cigarette smoking alone. 18 Finally, it is important to point out that, although switching from cigarette smoking to smokeless tobacco is safer than smoking cigarettes, smokeless tobacco is still far from safe. 12 , 13 Proponents of harm reduction claim that for cigarette smokers who find complete smoking cessation an unobtainable goal, reducing harm through use of alternative nicotine sources with fewer health risks is better than continuing to smoke. These advocates often cite Sweden's promotion of the smokeless product “snus” as an example of effective harm reduction. 19 Swedish snus use has been linked to a decrease in smoking prevalence and a net population health benefit. 20 , 21 However, available data suggest that the Swedish and US populations behave differently. 22 Specifically, both US male and female smokers have higher quit rates than in Sweden despite the higher rate of snus use in Sweden. Analysis of data in populations with high rates of tobacco use (both cigarettes and smokeless tobacco), such as the US military, 23 may provide additional information regarding the behavior of US tobacco users. We explored tobacco use patterns in a large military cohort from basic military training to 12-month follow-up. During basic military training, all tobacco use is forbidden (a well-enforced prohibition) for a 6-week period; therefore, smokers and smokeless tobacco users undergo forced tobacco abstinence. We assessed the extent to which cigarette smokers in this population switched to smokeless tobacco (e.g., harm reduction) following the smoking ban during basic military training. 12 , 13 , 24 We also explored the extent to which smokers increased their potential risk by switching to dual tobacco use (e.g., harm escalation).
