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Fortunately, there is a simple way to evaluate this hypothesis, at least on a preliminary basis, prior to waiting for the results of longitudinal studies. Enough youth are experimenting with electronic cigarettes, and the increase in youth e-cigarette use has been dramatic and sustained enough, that if the gateway hypothesis were correct, we would be starting to see an increase in smoking prevalence among youth due to the many new smoking initiates that were converted from e-cigarette experimentation to smoking.

According to a published research and a European Lung Foundation , the European Respiratory Society is opposed to the use of e-cigarettes in any setting in which they are unregulated (which currently includes the United States and most countries).

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