Introduction: The popularity of electronic cigarettes (e-cigarettes) among adolescents is growing worldwide. A more accurate model than the much discussed but inadequate Gateway Hypothesis is needed to explain some adolescents’ initial preference for e-cigarettes over tobacco cigarettes, as well as any transition from e-cigarettes to tobacco smoking. Our aim was to summarize the diffuse fear that adolescents will be indirectly encouraged to begin smoking tobacco via the use of e-cigarettes and to systematize the disparate causal hypotheses used thus far in relevant literature. Methods: We summarized the vague and fragmented hypotheses formulated thus far in literature on both trajectories from abstinence to e-cigarette use and from there to tobacco smoking into a set of empirically testable hypotheses and organized them into a comprehensive model. Results: Our results indicate that the perceived health risks, specific product characteristics (such as taste, price and inconspicuous use), and higher levels of acceptance among peers and others potentially make e-cigarettes initially more attractive to adolescents than tobacco cigarettes. Later, increasing familiarity with nicotine could lead to the reevaluation of both electronic and tobacco cigarettes and subsequently to a potential transition to tobacco smoking. The suggested “catalyst model” takes variations in the nicotine content of e-cigarettes as well as the dual use of different substances into account. Conclusion: Our model provides causal hypotheses for the initiation of e-cigarette use and for the potential transition to tobacco smoking which, after being tested in empirical studies, could lead to the formulation of concrete recommendations for healthcare intervention and prevention measures. Implications: We developed a model that provides causal hypotheses for the initiation of e-cigarette use and for the potential transition to tobacco smoking.

In comparison with men, women have a healthier lifestyle, are more rarely overweight, have less stressful occupations, or are not employed outside the home. The “gender pain bias” is the fact that women nevertheless have a higher prevalence of back pain. This paper looks at the possible underlying reasons for this as yet unexplained gender difference, using Stokols' socioecological health model as a basis. The first National Health Survey for the Federal Republic of Germany was carried out from October 1997 to March 1999. It comprised a representative total sample of 5315 persons between the ages of 20 and 64. The participants took part in a medical examination and answered a self-report form. χ2 test and logistic regression analyses were used to investigate correlations between self-reported low back pain and gender-specific biopsychobehavioral and sociophysical environmental factors. Seven-day back pain prevalence in the Federal Republic of Germany is 32% for men and 40% for women. Prevalences are significantly higher for overweight subjects, persons with a marked somatization tendency or a low level of social support, physically inactive individuals, smokers, elderly subjects, the nonemployed, “blue collar workers” and lower socioeconomic groups. From a multivariate perspective, however, none of these factors reduces (and hence sufficiently explains) the gender difference. Factoring in the gender-specific somatization tendency reduces the odds ratios of women versus men from 1.42 to 1.23. In view of the gender difference in pain prevalence, which remains stable despite a multivariate perspective, there is clearly a need for more research into the reasons underlying the gender difference. We believe that future studies should look at rarely investigated constructs such as “sex role expectancies,” “anxiety,” “ethnicity,” and “family history” and take anatomic differences in muscle strength into account.