Stringent tobacco restrictions on teens, such as eliminating access to cigarette machines, seems to influence whether they pick up the habit as adults. Credit: Ben Schumin

States that want to reduce rates of adult smoking may consider implementing stringent tobacco restrictions on teens, suggests a new study by researchers at Washington University School of Medicine in St. Louis.

The researchers discovered that states with more restrictive limits on teens purchasing tobacco also have lower adult rates, especially among women. And compared with states with less restrictive limits, they also tend to have fewer adult .

The study is published online June 13 in the American Journal of Public Health.

"In most states for many years, it has been illegal to sell cigarettes to people under 18, but few provisions are in place to prevent those sales," said the study's first author Richard A. Grucza, PhD, associate professor of psychiatry. "This study shows that more restrictive policies can prevent and be beneficial down the road."

Grucza's team evaluated data from an ongoing survey that monitors smoking behavior in all 50 states.

Studying information gathered from 1998 to 2007 from 105,519 individuals ages 18 to 34, the researchers looked at whether people ever had smoked, whether they currently were smoking, and, if they did smoke, whether they smoked more than 10 cigarettes per day.

They also looked at the smoking restrictions in place in states when the study subjects were 17 years old.

There is a lot of evidence that by making it harder for teenagers to buy tobacco, it's possible to cut smoking rates in teens. But now for the first time, researchers at Washington University School of Medicine in St. Louis have found that state laws and policies that keep teens away from tobacco also appear to reduce smoking rates later on when those teenagers become adults. Credit: Washington University BioMed Radio

"We looked at age 17 because in most states, it was illegal for anyone under 18 to buy ," Grucza said.

But how individual states chose to enforce the laws varied. Grucza's team focused on nine smoking-related policies and found that in states with enforcement policies, not only did 17-year-olds have more difficulty purchasing cigarettes, but that when they reached their 20s or 30s, they were less likely to smoke.

"We estimated that if all states had effective policies in place, it would reduce the prevalence of smoking by about 14 percent and the rates of heavy smoking by 29 percent," he said.

The four most effective restrictions included those on cigarette vending machines, in which the machines either were eliminated or housed in locations inaccessible to those under 18; identification requirements for purchasing cigarettes; restrictions on repackaging cigarettes so that five or 10 could be sold at a time, rather than an entire 20-cigarette pack; and prohibiting distribution of free cigarettes at public events.

Because cigarettes have been regulated by the U.S. Food and Drug Administration (FDA) since 2009, many of the more restrictive policies are in effect nationally, so Grucza's team believes future smoking rates among adults may decline at least partly as a result of those policies.

Interestingly, they found the policies to restrict youth access to tobacco had a big impact on women but didn't seem to influence smoking rates in men.

"We can only speculate about why, but a number of past studies have shown that underage women and girls often have an easier time getting alcohol or tobacco than underage men," Grucza said. "We suspect that policies like those that require checking IDs may have evened things out by making it just as difficult for underage women to buy as it is for underage men."

As more states around the country implement and enforce more restrictive policies, Grucza expects they may further reduce .

"A lot of states still have not adopted all of these policies," he explained. "In 2006, which is the last year for which we have data, only four states required a photo ID, and only 20 states had any kind of identification requirements at all. So there's still a lot of room for improvement."

Grucza said some are considering restricting youth access even more. In New York, there is a proposal to raise the age for tobacco purchases to 21. Meanwhile, in Alabama, Mississippi, Alaska and Utah, the minimum age for purchases already has been raised to 19.

More information: Grucza RA, Plunk AD, Hipp PR, Cavazos-Rehg P, Krauss MJ, Brownson RC, Bierut LJ. Long-term effects of laws governing youth access to tobacco. American Journal of Public Health, First Look vol. 103 (8), June 13, 2013.

Journal information: American Journal of Public Health