"Movies seen at the youngest ages" -- mostly rated "G," "PG," or PG-13" -- "had as much influence over later smoking behavior as the movies that children had seen recently," according to researcher Linda Titus-Ernstoff of Dartmouth Medical School, summarizing the findings of a new study.

HealthDay News reported Jan. 8 that Titus-Ernstoff studied a group of 2,200 youths ages 9-12, comparing smoking prevalence over time with their viewing of movies that researchers had assessed for "smoking occurrences." They concluded that up to 35 percent of smoking initiations were the result of exposure to smoking in movies, with children exposed to cinema smoking at a young age as likely to start smoking as children exposed only at a later age.

Titus-Ernstoff described the relationship between movie smoking scenes and youth smoking as "causal," adding, "It is quite improbable that the association we see is due to some other influence, some other characteristic inherent in children or parental behavior. The relationship is clearly between movie-smoking and smoking initiation."

"Our finding is that the vast majority of smoking in movies that children are exposed to comes from movies that are youth-rated," she added. "So even if parents are doing a good job protecting their children from 'R'-rated movies, they still need to pay attention to the 'G,' 'PG,' and 'PG-13' movies. ... "I think [parents] tend to worry more about sex, violence and bad language. But bad language never killed anybody."

The study was published in the January 2008 issue of the journal Pediatrics.