Nearly 40 percent of U.S. adolescents who give cigarette smoking a try do so because they saw it in movies, a study said on Monday.
The study, described as the first national look at the influence of movie smoking on youths, urged Hollywood to cut back on depictions of smoking or shots of cigarette brands.
The industry also should consider adding a mention of smoking to movie rating data that now mention explicit sex, violence and profanity, it said.
Researchers at Dartmouth Medical School asked 6,522 children aged 10 to 14 to identify films they had seen from a list of 50 randomly selected box office hits released in the United States from 1998 to 2000.
Even after considering other factors known to influence smoking, the study found that adolescents with the highest exposure to movie smoking were 2.6 times more likely to try it compared to those with the lowest exposure.
Of every 100 adolescents who tried smoking, 38 did so because they saw smoking portrayed in movies, said the report published in the November issue of "Pediatrics," the journal of the American Academy of Pediatrics.
In the entire sample, about 10 percent had tried smoking, according to the study paid for by the National Cancer Institute.
"Part of the reason that exposure to movie smoking has such a considerable impact on adolescent smoking is because it is a very strong social influence on kids ages 10-14," said James Sargent, a pediatrics professor at the school and lead author of the study.
"Because movie exposure to smoking is so pervasive, its impact on this age group outweighs whether peers or parents smoke or whether the child is involved in other activities, like sports," he added.
The authors said their research confirms findings published last year based on a study of teens living primarily in rural areas of New England.
"This is an extremely powerful confirmatory study that shows that kids react the same way to the movies in other places in the United States as they do in New England," said Sargent. "It means that no child is immune to the influence of smoking in movies."
A U.S. government survey released in March showed 22.3 percent of high school students and 8.1 percent of middle school students said they smoked cigarettes in 2004.