Regulating e-cigarettes in Australia: implications for tobacco use by young people

In reply:

Mendelsohn raises a number of points regarding our article examining e-cigarette use among youth which we seek to address below.1

First, we concur that prospective cohort studies do not provide unequivocal evidence of causation. To establish causality, randomised controlled trials where individuals are allocated to use e-cigarettes would be required — an unethical proposition. In the absence of randomised controlled trials, meta-analysis of prospective studies is an accepted basis to show links between environmental or behavioural risks and disease. In this instance, the available evidence from prospective studies, while limited, cumulatively shows a positive association between e-cigarette use in youth and tobacco smoking at follow-up, even when adjusting for a range of prognostic factors.2

Second, observations that smoking rates are declining concurrently with rapid increases in e-cigarette use are insufficient to refute a potential gateway effect. As noted, e-cigarette use among non-smokers remains relatively low in most countries. Therefore, at a population level, a potential gateway effect among non-smokers is unlikely to be sufficient in itself to counter the existing decline in cigarette use among youth attributed to the raft of tobacco control policies that have been occurring for over a decade.3

Conversely, despite higher use of e-cigarettes among youth smokers, there have been little accrued cessation benefits for adolescents. That is, the introduction of e-cigarettes has made no clear additional difference to the existing decline among current smokers.4 Modelling of the impact of e-cigarettes, including that cited in the response by Mendelsohn, have been highly contested, given the uncertainty of the evidence regarding their benefits and harms.5

Finally, we do not dismiss the potential benefits of e-cigarettes as a smoking cessation aid, nor do we provide any specific regulatory recommendations. The evidence regarding the effectiveness of e-cigarettes in facilitating cessation is equivocal to date. Governments may well adopt a regulatory approach consistent with that suggested by Mendelsohn. However, there is first a need to present policy makers with evidence that will allow them to weigh the potential benefits of more liberal e-cigarette regulation against potential harms before they do so.