In August 2008, the US National Cancer Institute issued a major scientific report that concluded:

"The total weight of evidence from cross-sectional, longitudinal, and experimental studies indicates a causal relationship between exposure to depictions of smoking in movies and youth smoking initiation."

The NCI reached this conclusion because scientific studies consistently demonstrate that smoking in the movies stimulates kids to smoke. For example, comparing kids’ attitudes towards smoking before and after watching a movie with smoking moves kids' attitudes in a pro-smoking direction.

Such experiments have been complemented with surveys of large numbers of children asking them whether or not they smoke and what movies they have seen or who their favorite stars are that demonstrate, after accounting for other factors that determine smoking such as whether their parents smoke or how the kids are doing in school, the kids who have seen a lot of smoking in the movies or have favorite stars that smoke are more likely to be smokers. These "cross-sectional studies" are a snapshot. While providing strong evidence, by themselves they are not conclusive. For instance, what if teens who smoke simply prefer to watch movies with smoking in them? To be certain of cause-and-effect, researchers need to follow kids over time.

In 2003, researchers from Dartmouth University published a landmark study that followed 2603 adolescents for up to two years and found that, after controlling for the effects of all the other factors they considered, kids who saw the most smoking in movies were nearly three times as likely to have started smoking than kids in the lowest exposure group. As was demonstrated in earlier “snapshot” studies, there is a “dose-response effect:” The more on screen smoking the kids saw, the more likely they were to have started to smoke.

Since then there have been many sudies confirming this dose-reponse effect. Considering all the available studies, smoking in the movies accounts for 44% of the kids who started smoking, a stronger effect than traditional cigarette advertising. (Big Tobacco has understood this fact for decades.)

Applying these results nationwide, allows us to estimate the number of smokers, state-by-state (see table below), aged 12-17 who are smoking because of smoking in the movies, as well as how many will ultimately die prematurely as a result.

What's the cost?

The social cost of these cohorts of new smokers 12-17, recruited by exposure to on-screen smoking, can be estimated:

• Total lifetime costs, medical and other: $268 billion

• Lifetime medical costs only: $11 billion (two-thirds borne by government)

• Medical costs through age 50: $17.6 billion (two-thirds borne by government)

All values in 2011 dollars, discounted present value. For sources, notes and details, click here.

Note 1 | SAMHSA, Office of Applied Studies, National Survey on Drug Use and Health, 2006 and 2007. State Estimates of Substance Use and Mental Health from the 2006-7 National Surveys on Drug Use and Health. Estimated numbers in the population for Tables B.1 to B.24: (Online) Table 14. Cigarette Use in Past Month, by Age Group and State: Estimated Numbers (in Thousands), Annual Averages Based on 2006 and 2007 NSDUHs. Consulted at http://www.oas.samhsa.gov/2k7state/ageTabs.htm on 23 October 2009.

Note 2 | Attributable risk is 0.44 (95% CI 0.34-0.58). Millett C, Glantz SA (2010)  Assigning an 18 rating to movies with tobacco imagery is essential to reduce youth smoking. Thorax (in press). This new estimate uses information from additional studies to update the previous attributable risk of 0.52 (95% CA 0.30-0.67) from Dalton MA, Sargent JD, Beach ML, Titus-Ernstoff L, Gibson JJ, Ahrens MB, Tickle JJ, Heatherton TF (2003) Effect of Viewing Smoking in Movies on Adolescent Smoking Initiation: A Cohort Study. The Lancet 362(9380):281-285. With more data, the margin of error has been reduced from ± 0.18 to ± 0.12.

Note 3 | Tobacco-induced mortality among smokers is 32%. BRFSS Coordinators. Projected Smoking Related Deaths Among Youth — United States. MMWR 1996; 45:971-74.