Researchers are emphasizing the importance of a new government report that they say demonstrates for the first time a causal link between tobacco use in movies and smoking behaviors in the population, Reuters reported Aug. 21.

The monograph from the National Cancer Institute, entitled The Role of the Media in Promoting and Reducing Tobacco Use, states that tobacco promotions and depictions of tobacco use in movies both cause teenagers to start smoking. At least three-quarters of hit movies show scenes of smoking, and the report added that even brief exposures to tobacco promotion have a demonstrated effect on youth attitudes.

Six major film studios announced in July that they would begin placing anti-smoking public service messages on the DVDs of all movies with youth ratings that depict smoking. This effort will not extend to movies shown in theaters.

The report, which looked at more than 1,000 studies related to how the media influences tobacco use, arrives during a period when concern about youth smoking remains intense. More than 4,000 young people a day in the U.S. initiate smoking, and about 90 percent of adult smokers say they began smoking in their teen years.

Health experts appearing at a news conference to unveil the report said a great deal more money should be spent on mass media campaigns to curb youth smoking. They added that partial controls on tobacco company advertising have largely failed because they have simply driven companies to other forms of marketing, such as discount promotions.

"Any promotional technique that lowers the price the kids see when they go to buy a pack of cigarettes is extremely important," said Ronald Davis, M.D., senior scientific editor of the National Cancer Institute report and past president of the American Medical Association (AMA). "Partial advertising bans don't work."