Welcome back to the Vapour Mythbusting Power Hour, part 3. If you haven’t read our first part, (toxic metals in vape coils???) or our second part, (formaldehyde production in eliquid???), then go do so. It’s informative and it really helps out our SEO.

Today we’re going to take on the oft-cited claim that children are taking to e-cigarettes like moths to non-combusting low-ohm vapour-producing bug zappers. You know the one: it’s a growth on the back of the monster of moral decay that you believe is coming for you, if you’re the kind of person who spend too much time loitering in bus stations.

But while our previous two busted myths were deflated by pointing out the ways in which lab use doesn’t always mimic real human use, the data science behind these claims is a little trickier to untangle, and makes gratuitous use of words like ‘but’ and ‘however’.

Let’s dig in.1

The science

A variety of surveys have been conducted within the past few years measuring youth e-cigarette use across the United Kingdom, querying thousands of children between the ages of 11-16.

The results were heartening: only between 7-18% of 11-16 year olds had ever tried an e-cigarette, and regular use (defined in most of the surveys as ‘weekly’ use) ranged only from 1-3% of 11-16 year olds. And rates of regular use haven’t proven to have risen over the course of the years that the surveys were run.

The numbers are even more encouraging among young people who have never smoked. In fact, only half a percent of young people who have never used tobacco, use e-cigarettes regularly.

Among young people who smoke, however, e-cigarette use is quite high—as many as 91% of youth smokers have tried an e-cigarette. But maybe that’s a good thing? Is it indicative of a surge in e-cigarettes as a stop smoking method among the young?

A little more science

Well, maybe. It’s not clear. And the waters are about to get a bit murkier.

Two studies that measured e-cigarette and tobacco use among youth across two years—that is, one survey was taken, and then a follow-up survey was taken a year later—found that e-cigarette use at baseline correlated positively with tobacco use at follow-up. Both studies conducted statistical modelling to try to control for environmental factors that might encourage those who have tried e-cigarettes to use tobacco (e.g. having friends or family who smoke). Still…

The fully adjusted model showed that having tried an EC at baseline was significantly associated with trying cigarettes in the following year.

That is, e-cigarettes seem to be making kids start smoking.

Not so fast

There’s some trouble with interpreting the results this way.

The measurements were taken of young people who have ever used an e-cigarette and who have ever used tobacco. It’s possible that one of the young people surveyed had used an e-cigarette precisely once, and then within the following year had tried tobacco again precisely once. Read in this way, it doesn’t seem likely that this young person was encouraged to start smoking after using an e-cigarette—they just sound like they’re experimenting.3

This hypothesis is supported by what’s called a ‘common liability’ theory, laid out by a UK study from 2018 (and another from the United States) that sought to assess the relationship between 1) e-cigarette use and starting smoking, and 2) tobacco use and starting vaping.

The study similarly found that e-cigarette use the first year correlated with tobacco use on follow-up. But it also found that tobacco use the first year correlated with e-cigarette use on follow-up. This is what ‘common liability’ is: either one correlates with the other.

This theory might go some of the way to explaining why e-cigarette and tobacco use are correlated: some young people are just inclined to try both.

More confounding evidence

Of course, the biggest problem with the narrative that e-cigarettes encourage young people to start smoking is that even while e-cigarette experimentation continues, the rates of youth smoking is (and has been for decades) in decline. If the rise of e-cigarettes was encouraging young people to start smoking tobacco, wouldn’t we have seen the youth tobacco use rate of decline slow down, or reverse?

And yet we haven’t.

Myth busted?

Well, not quite. Like in many instances of e-cigarette use, the story here needs a little more context, which means that studies need some more time to see how everything pans out.

‘Common liability’ is an explanation for some of the results we’ve seen. It’s not the be-all-end-all of the conversation, but it’s an important piece of the puzzle.

In the meantime, it’s clear that e-cigarettes aren’t drawing young people who have never smoked into using tobacco, and indeed, aren’t slowing or reversing long-term trends in youth tobacco use.

1 For reference, the studies we’re looking at here are the four included in the recent Public Health England evidence review:2 The Youth Tobacco Policy Survey, the ASH Smokefree Great Britain – Youth, the Schools Health Research Network Wales, and the Scottish Schools Adolescent Lifestyle and Substance Use Survey.

2 I know you’re sick of hearing about it, but it’s a real trove of serious, government-funded, unbiased research, and we’re not done digging through it. Deal with it.

3 Which is what people at that age do anyway.