Thirty U.S. states and Washington, D.C. have imposed taxes on these products in an effort to curb the use of increasingly popular electronic nicotine delivery systems, such as e-cigarettes, but there is growing evidence that among adults, these taxes will Increase smoking rates, a habit that may have more harmful health effects than nicotine use, according to the National Institutes of Science and Medicine.

Less clear is how the tax affects the habits of 18- to 25-year-olds, who are often grouped with adults in the study. Abigail Friedman, an associate professor at the Yale School of Public Health, said this group is of particular concern because people typically transition from experimental nicotine use to everyday use at these ages.

In a new study published July 19 in the journal Addiction, Friedman and her co-author Michael Pesco of Georgia State University assessed the impact of cigarette and e-cigarette taxes on smoking and vaping in this age group. Effects of nicotine smoking.

Abigail Friedman said anyone contemplating a tax on one tobacco or nicotine product would need to consider the tax rate on all other products.

In this study, the authors compared survey data on youth smoking and vaping between states that did increase taxes on cigarettes and nicotine vaping products with states that did not.

They found that increasing taxes on nicotine vaping products by $1 per milliliter was associated with a 2.5 percentage point decrease in daily vaping rates in this group, but also a 3.7 percentage point increase in recent smoking rates.

Likewise, each dollar increase in cigarette tax was associated with a 2.5 percent decrease in recent smoking and a corresponding increase in daily nicotine product use.

The findings suggest that tax policy needs to be nuanced, Friedman said.

"Anyone contemplating a tax on one tobacco or nicotine product needs to consider the tax rate on all other products," she said. “Because if people are substituting between products and you raise the price of one product, some subsets will move to cheaper options even if they don’t like that product as much. From a public health standpoint, more Cheaper options are also less harmful, which is important.”

Evidence that cigarettes are more deadly than nicotine vaping products suggests that increasing taxes on smoking is worse for public health than increasing taxes on nicotine vaping, the researchers said.

The team also found that this younger cohort responded about three times more to the vaping product tax than was found in a previous study of 18- to 40-year-olds.

“If you paint the entire 18- to 40-year-old age range in big brush, you get very different responses,” she says. "And it makes sense that 18 to 25-year-olds respond faster. That's the peak age range where people transition from trying tobacco products to habitual use. We're seeing much higher absorption rates there than older adults."

Friedman said research in this area tends to divide the population into children and adults, but future research should consider these emerging adults separately, as she said.

"One of the things this research shows is that the divide between children and adults is not clean," she said. "Because 18 to 25 years is a critical transition period from experimenting with tobacco products to regular use, these are important target ages if you want to break off and start habitual smoking and vaping."

This research was supported by Evidence in Action grants from the Robert Wood Johnson Foundation (grant #74869, Friedman), the NIH National Institute on Drug Abuse (grant #R01DA045016, Pesco), and the University of Kentucky Research Institute Free Enterprise Research (Pesko).