A new study takes a different stance on flavored tobacco bans in San Francisco, and a Yale University researcher says flavor-ban policies could force teens to smoke and use combustible cigarettes.

The study, titled "Analysis of Differences in Youth Smoking and Banning the Sale of Flavored Tobacco Products in San Francisco, California," was authored by Dr. Abigail Friedman, assistant professor of public health at the School of Public Health and the Yale Institute for Social and Policy Research.

Friedman is a respected scholar and one of the most prominent scholars in the field of tobacco harm reduction and control.

According to the study's findings, a ban on the sale of flavored tobacco products implemented by the city and county of San Francisco, California, hurt rates of teens switching to smoking or other potentially more harmful forms of nicotine delivery.

"San Francisco's ban on the sale of flavored tobacco products was associated with increased smoking rates among underage high school students compared with other school districts," said Friedman's findings, published in the journal JAMA Pediatrics.

"While the policy applies to all tobacco products, the results may be greater for vaping youth than for smokers due to higher rates of flavored tobacco use among the vaping population."

“This raises concerns that reducing the use of flavored ENDS may incentivize young people who would otherwise replace smoking with e-cigarettes. In fact, the minimum legal age for sale of ENDS is the same as youth smoking An analysis of the relationship between the two also suggests this substitution."

"While smoking and nicotine are inherently unsafe, most of the current evidence suggests that smoking is far more harmful, with nearly one in five adults dying each year from smoking," Friedman told reporters.

"Even well-intentioned, laws that increase youth smoking could pose a threat to public health."