E-Cigarettes May or May Not Be a Gateway Drug. (But Probably Not.)

Are e-cigarettes a gateway drug to traditional cigarettes? There’s a new study out that suggests they might be:

The study focused on ninth-graders at 10 public schools in Los Angeles who had tried e-cigarettes before the fall of 2013. Researchers surveyed those students in the spring of 2014 and fall of 2014, and discovered that they were about 2½ times as likely as their peers to have smoked traditional cigarettes.

This is a classic case of correlation which may or may not also be causation (something the authors acknowledge). Did more of the e-cigarette kids take up smoking because e-cigarettes gave them a taste for it? Or do the kids who are most likely to take up smoking in the first place simply start with e-cigarettes? There’s no way to tell just from this study.

That’s not to say it’s worthless, though. If the study found no correlation, then you could be pretty sure that e-cigarettes don’t lead to cigarette smoking. That would be worth knowing. But since it did find a correlation, we need more research to know if there’s causation here.

One way to get a tentative read on this is to look at total cigarette smoking among teens. If it’s up, then e-cigarettes might be leading more kids to cigarettes. If it’s not up, then e-cigarettes are probably just temporarily replacing cigarettes for kids who were going to take up smoking anyway. So which is it?

As it happens, we know the answer to this: cigarette smoking has plunged among teenagers over the past four years. On the other hand, total cigarette use among teens (cigarettes + e-cigarettes) has gone up. The cigarette plunge makes it unlikely that e-cigarettes are a gateway to traditional cigarettes. But the increase in total cigarette use suggests that e-cigarettes really are creating a new market. It’s complicated.