SAN FRANSISCO (NewsNation Now) — Public health officials are expressing concern that bans on flavored tobacco products could cause the increase of smoking conventional cigarettes in teens.

The study conducted by Yale School of Public Health, and posted in JAMA Pediatrics, studied the impact among teenagers in San Francisco’s school district after a ban on all flavored tobacco products was approved in 2018.

It found that rates of teenagers smoking conventional cigarettes doubled in San Francisco.

“What this tells us is if they can’t get that product, a good proportion of them are likely to smoke,” said study author Abigail Friedman.

Before the ban, self-reported smoking levels among teenagers in San Francisco and other similar school districts in California were consistent and going down. San Francisco went up after the ban while others continued trending down.

“I did further analysis than even in the paper I looked and found this held, even if you look at the kids who’d never vaped. So this isn’t just driven by kids who are already using e-cigarettes,” explained Friedman.

She added that the trend stayed consistent across demographics and ages. Friedman noted that there some limits to the study including that the ban has only been around for a short time so long-term effects may be different.

When asked what the lesson for lawmakers should be, Freidman said it’s that banning flavored tobacco products might not have the end result public health officials hoped for.

“So I think there’s been a mistake made in the discourse here, there’s a tendency to think that we can either think about kids or we can think about adults with vaping. You know, there is evidence that smokers, some smokers at least, can use e-cigarettes to quit. And there’s a concern about kids taking up e-cigarettes and being exposed that way to tobacco products,” said Friedman.

She suggests lawmakers instead consider fully banning tobacco nationwide to anyone under 21. It would make it harder for those under 18 to access the products and provide less temptation to those attempting to quit.