Filmmakers in Hollywood produce hundreds of films each year and audiences around the world watch them. In many films, characters smoke cigarettes and other forms of tobacco. Past studies have documented how young movie fans are influenced by watching those images on the screen: kids who watch many movies where characters smoke are more likely to try smoking themselves.

Dr. James Sargent, a researcher with Dartmouth University Medical School in New Hampshire, says although those research findings are strong and consistent, many people are skeptical when they hear that movies might contribute to adolescent smoking. "How can movies be responsible for a third of adolescent smoking when there's only, you know, 30 seconds to a minute of smoking in every movie? So what we wanted to do with this study was really scale the exposure for people so that they understood how much exposure kids really get when it comes to seeing these actors modeling smoking on the big screen."

Sargent and some international colleagues counted how often images of smoking were seen by adolescents. They watched about 500 popular movies and counted the images of smoking in each. Then they multiplied that number by the number of adolescents estimated to have seen the films. Sargent says it adds up to billions of images of smoking in American films that are seen by kids around the world.

"So it is a big international problem to the extent that American movie companies are exporting smoking in youth-rated movies, the kids in other countries are seeing the smoking, and it's positioning smoking as something they want to do," he concludes.

Sargent says almost nothing else compares with smoking in terms of public health problems around the world. Millions of people die annually of diseases caused by smoking: lung and other cancers, heart disease and respiratory diseases. He says many of those people started smoking as teens.

"We've already shown pretty convincingly that seeing smoking in movies is delivering kids to the tobacco industry," he says, adding that Hollywood has a responsibility to counter that trend. "The movie industry could do something that would eliminate smoking in youth-rated movies, they could rate smoking R (for restricted)." He notes that's what public health activists are trying to get filmmakers to do. He says that action would eliminate 60 percent of the smoking images the kids in his sample had seen.

Sargent's research was published in the most recent issue of the journal Pediatrics.