The more movie scenes of smoking they watch, the more likely Mexican-American youths are to experiment with smoking, researchers at The University of Texas M. D. Anderson Cancer Center and Dartmouth College report in the December issue of Cancer Epidemiology, Biomarkers and Prevention.
The three-year prospective study of 1,286 Mexican-American adolescents showed the percentage of new experimenters increased from about 5 percent among those with little or no exposure to nearly 30 percent for those who saw up to 600 smoking scenes. The effect was dose-dependent, with experimentation linearly correlated with movie exposure.
For youths born in Mexico, the "dose" of smoking scenes was the strongest independent predictor of experimentation, overshadowing other known risk factors such as having friends who smoke and at least one school detention.
"Parents need to limit their adolescents' access to R-rated movies, which research has shown have the most depictions of smoking," said lead author Anna Wilkinson, Ph.D., assistant professor in M. D. Anderson's Department of Epidemiology in the Division of Cancer Prevention and Population Sciences.
"Movies that include smoking scenes should be rated R, to reflect their potential harm," she said. The World Health Organization Framework Convention on Tobacco Control includes guidelines for restricting access by using a country's movie ratings system.
Study participants, who were ages 11 to 13 at the start, indicated whether they had seen a sample of 50 movies selected a random from 250 movies that had been previously analyzed for their smoking content.
While previous research indicated that exposure to smoking in movies increases risk in other groups, the team's study was the first among people of Mexican origin, the most rapidly growing subgroup of Hispanics in the United States.
At the onset of the study, 10 percent of the adolescents indicated they had already tried smoking. Another 17 percent experimented over the three-year course of the project. The most powerful response was found among those who were born in Mexico, with fewer than 10 percent of experimenters among those with little or no exposure, on up to 39 percent of those exposed to up to 600 images. For U.S.-born study participants, the effect leveled off at 25 percent among those who had seen at least 400 images.
Gender, age and peer smoking were the most important predictors of experimentation for the U.S.-born adolescents.
"We suspect the greater impact among Mexican-born might occur because movie-viewing is part of the socialization process for those not born here," Wilkinson said.
The longitudinal study was made possible by the Mexican-American Cohort Study, an effort that has recruited more than 12,000 families to better understand factors that influence Mexican-American health. The cohort is funded by Texas Tobacco Settlement funds and M. D. Anderson.
This research was funded by a grant from the National Cancer Institute.
Co-authors with Wilkinson are senior author James Sargent, M.D., of Dartmouth Medical School, and Margaret Spitz, M.D., Alexander Prokhorov, M.D., Ph.D., Melissa Bondy, Ph.D., and Sanjay Shete, Ph.D., all of M. D. Anderson's Department of Epidemiology.
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