The lead author of the study, Stanton Glantz, PhD, professor of medicine and director of the UCSF Center for Tobacco Control Research and Education, said that previous studies conducted around the world found that watching on-screen smoking was associated with recruitment of adolescent smokers.
However, this is the first time that smoking among young adults has been linked with their exposure to on-screen smoking scenes. "Ages 18 to 25 are critical years, when one-third of smokers start and others who began smoking as adolescents either stop smoking or become regular smokers," Glantz said.
The research team conducted a test wherein they found a "dose-response relationship" between exposure to smoking on-screen and the likelihood of having smoked in the past 30 days in a sample of 1,528 young adults.
The study showed that young adults who had a lot of exposure to on screen smoking have a 77 percent greater chance of having smoked at least once in the last 30 days (a measure of smoking initiation) and an 86 percent increased chance of being regular established smokers compared to young adults who saw little smoking in movies.
"Established smokers" are defined as those who have smoked 100 cigarettes or more and currently smoke. Of the study group, 24.7 were smokers, comparable to estimates of the Centers for Disease Control and Prevention of 25.3 percent for this population.
The survey format was similar to the studies of adolescents, with participants receiving a list of 60 motion pictures, selected at random from the top grossing 500 movies released during 2000-2004, and asked to identify the movies they had seen. Each participant was then placed in a quartile of exposure based on the sum of tobacco occurrences that had been viewed.
The findings of the research showed a direct effect between exposure and current smoking. It was found that two factors mediated the association between exposure to film smoking and established smoking: positive expectations about smoking and exposure to friends and relatives who smoke.
"The main effect is to recruit new smokers from among young adults. Movies encourage them to experiment, and once they start experimenting with cigarettes other factors take hold. Movies create the expectation that smoking will turn out okay," Glantz noted.
Glantz emphasized that the effect demonstrated in young adults is smaller than effects shown in adolescents, but comparable to other environmental risk factors for smoking initiation in young adults. Glantz said, it has been estimated that awarding R-ratings on future tobacco imagery to eliminate smoking from youth-rated films would reduce teen exposure to the imagery by half and prevent about 200,000 youth a year from starting to smoke.
He added that the results of the new study indicate that young adults are also being recruited to smoke through their exposure to movie smoking, and a substantial reduction in smoking content has the potential to avert even more tobacco deaths.
The study findings are published in the November issue of the American Journal of Preventive Medicine.