Youth who watch a lot of movies with cigarette-smoking characters - whether the films are rated R or PG-13 - are more likely to start smoking themselves, researchers suggest in a new study out Monday.

The report’s lead author said the finding supports the idea that it’s the smoking itself - and not the sex, profanity or violence that may go along with it in certain films - that influences youth to take up the habit.

“Movie smoking seems to be just as impactful if it’s packaged in a PG-13 movie as opposed to an R movie,” said Dr. James Sargent, from the Geisel School of Medicine at Dartmouth in Lebanon, New Hampshire.

“I really think it’s a ‘cool’ factor. The more they see it, the more they start to see ways that (smoking) might make them seem more movie-star,” he told Reuters Health - even if the effect is subconscious.

Sargent and his colleagues counted how many times a character was seen smoking in each of over 500 box-office hits from recent years. Then, they asked 6,500 U.S. kids ages 10 to 14 which of a random selection of 50 of those movies they’d watched.

The average “dose” of movie smoking was 275 scenes from films rated PG-13 and 93 scenes from R movies, the researchers reported in Pediatrics.

And in three subsequent interviews with the same kids, those who had watched smoking-heavy movies were more likely to pick up the habit themselves. For each extra 500 smoking shots reported in their initial survey, youth were 33 to 49 percent more likely to try cigarettes over the next two years.

The effect of on-screen smoking was not significantly different for PG-13 and R films. And because kids tend to see more PG-13 flicks, Sargent’s team calculated that if smoking automatically earned an R rating, the number of youngsters who try cigarettes would drop by 18 percent.

“At this point, it is established that exposure to smoking in movies is a potent risk factor for actually taking up smoking, especially when the exposures are early,” Dr. Brian Primack, head of the Program for Research on Media and Health at the University of Pittsburgh School of Medicine, told Reuters Health in an email.

“This study goes a step further and suggests that taking smoking out of all PG-13 movies could have a palpable effect on the impact of smoking in the U.S.,” he added.

Still, another researcher not involved in the new study said he’s not sure if eliminating smoking from all non-R movies “is the magic answer.”

Matthew Farrelly, who studies smoking at the scientific institute RTI in Research Triangle Park, North Carolina, said the study is a step in the right direction. But he wasn’t sure the researchers could totally discount the influence of violence and profanity in movies on kids’ decision to try smoking just by looking at ratings.

“I’m hoping that someone can disentangle smoking in the movies from other content that might appeal to youth to really firm up this relationship,” he said.

A link between seeing on-screen smoking and trying cigarettes “makes sense,” Farrelly told Reuters Health. “I just think the relationship has been vastly overstated.”

The researchers agreed, however, that the new findings mean parents should be paying attention to what their kids are seeing in movie theaters and on TV.

“It’s a good reminder that parents have to be very involved in kids’ media consumption, and it comes in lots of ways these days,” Farrelly said.

“Parents have to treat their kids’ media diet the same way they treat their food diet,” Sargent said. That means paying attention to movie ratings and possibly setting TV controls to block out age-inappropriate material, he added.

Sargent recommended youth watch no more than two movies a week and called for “no R-rated movies until kids are well into adolescence.”

In another study published in the same journal, Sargent and a second team of researchers found kids’ opinions on smoking didn’t change when they watched a short family movie or cartoon featuring a smoking character. That report involved 206 eight- to 11-year-olds in the Netherlands.

He and his colleagues said one movie might not be enough to change kids’ minds about smoking - or seeing a one-dimensional cartoon character taking a drag might not have the same effect as watching characters in more mature movies lighting up.

SOURCE: Pediatrics, online July 9, 2012.