Last September the CDC noted with alarm that the percentage of teenagers who had tried electronic cigarettes doubled between 2011 and 2012. "Many teens who start with e-cigarettes may be condemned to struggling with a lifelong addiction to nicotine and conventional cigarettes," CDC Director Tom Frieden worried. In a Medscape interview a few weeks later, Frieden suggested that fear had already materialized, asserting that "many kids are starting out with e-cigarettes and then going on to smoke conventional cigarettes." Yet the CDC's data, which came from the 2012 National Youth Tobacco Survey (NYTS), did not support that claim. In fact, nine out of 10 high school students who reported vaping in the previous month were already cigarette smokers, suggesting that the increase in e-cigarette consumption might signal successful harm reduction. Last week the CDC reported additional NYTS data that further undermine Frieden's claim, showing that smoking among teenagers fell as vaping rose.

Between 2011 and 2012, when the share of middle school students who reported using e-cigarette in the previous month rose from 0.6 percent to 1.1 percent, the share reporting past-month consumption of conventional cigarettes fell from 4.3 percent to 3.5 percent. Among high school students, past-month e-cigarette use rose from 1.5 percent to 2.8 percent, while past-month consumption of tobacco cigarettes fell from 15.8 percent to 14 percent. Although these trends do not necessarily mean e-cigarettes are responsible for the decline in smoking, the numbers hardly seem consistent with the story Frieden is eager to tell: that the availability of e-cigarettes is leading to more smoking than would otherwise occur.

Since the numbers showing an increase in vaping come from the very same survey as the numbers showing a decrease in smoking, it is puzzling that the CDC decided to highlight the first trend two months before the latter one, especially since the smoking data suggest Frieden's fear, which was repeated and amplified by various activists and politicians pushing for strict e-cigarette regulation, is misplaced. But the omisision is puzzling only if you assume the CDC is mainly interested in the truth, as opposed to scientific-sounding justifications for an irrational anti-vaping prejudice. Boston University public health professor Michael Siegel, who sees e-cigarettes as a valuable harm reduction tool, comments:

This decline in cigarette smoking was not reported in the earlier CDC report on the increase in electronic cigarette use, nor was it mentioned in any of the multitude of interviews or news articles regarding the increase in youth e-cigarette use…. The opportunity to see the data on trends in cigarette smoking would have helped the public to see that there was no scientific support for the CDC's conclusion. I thus find it curious that these important data were not reported until weeks after the media [had] already disseminated the conclusion that e-cigarettes are a dangerous gateway to cigarette smoking. The CDC officials certainly had plenty of opportunity to let the public know that there was no discernible increase in cigarette smoking among youth concomitant with the observed increase in e-cigarette use. It seems to me that this is a critical finding to report. My impression remains that there is, for some reason (perhaps related to ideology), a pre-determined conclusion that e-cigarettes are evil. Instead of fairly reporting all of the evidence, only the evidence that supports the pre-determined conclusions [is] being shared.

Does the gateway effect Frieden fears—a switch from e-cigarettes to conventional cigarettes among people who otherwise would never smoke—show up after high school? Not according to a recent survey of college students, in which only 3.3 percent said e-cigarettes were the first form of nicotine they'd tried. Of those, only one (2.3 percent) later started smoking conventional cigarettes. "It didn't seem as though it really proved to be a gateway to anything," the lead researcher said.

[Thanks to Bill Godshall for the tip.]