Science | Smokefree movies? It's all about the evidence

The evidence is conclusive. Smoking in movies kills in real life.

The evidence is sufficient to conclude that there is a causal relationship between depictions of smoking in the movies and the initiation of smoking among young people. — US Surgeon General, 2012

Giving an R rating to future movies with smoking would be expected to reduce the number of teen smokers by nearly 1 in 5 (18%) and prevent one million deaths from smoking among children alive today. — US Centers for Disease Control and Prevention, 2014

The Surgeon General, like the US National Cancer Institute and World Health Organization, concluded that on-screen smoking harms large numbers of kids only after reviewing decades of evidence — all types of evidence.

Population surveys | Cross-sectional surveys have asked thousands of adolescents whether or not they smoke, what movies they have seen, and who are their favorite movie stars.

After accounting for other factors associated with teens' starting to smoke, such as their school performance and whether their parents smoke, the surveys found that teens who have seen a lot of smoking in the movies or whose favorite stars smoke are more likely to be smokers.

Longitudinal studies | An acknowledged limitation of cross-sectional surveys is that they are a snapshot in time: they can only document an association between two variables, in this case exposure to on-screen smoking and teens' starting to smoke. Longitudinal studies follow people over time, show what occurs before-and-after, and can illuminate causal relationships.

In 2003, Dartmouth researchers published a landmark longitudinal study that followed more than 2,600 adolescents for up to two years. After controlling for other factors bearing on smoking initiation, they found that the more smoking in movies kids saw, the more likely they were to start to smoke: a dose-response effect. Kids who saw the most smoking in movies were nearly three times more likely to start smoking than kids who saw the least.

In the decade since those 2003 results from young teens in New England, studies from a dozen other countries have confirmed the dose-response effect. 

Experimental evidence | In addition to these real-world studies, a variety of controlled experiments have helped explain how exposure to on-screen smoking leads kids to smoke. These studies have consistently demonstrated that exposure to smoking in movies shifts kids' attitudes in a pro-smoking direction and immediately stimulates urges to smoke. There is even a study that identifies what part of the brain is activated by viewing images of smoking.

Based on US population and longitudinal studies through 2012, it's now estimated that exposure to on-screen smoking accounts for 37 percent of US smokers younger than eighteen. That’s a bigger effect than conventional cigarette advertising. The US Surgeon General (2014) has concluded that R-rating future movies with smoking would reduce the youth smoking rate in the United States by 18 percent.

Historical evidence | Once-secret tobacco industry files, discovered during lawsuits, trace how tobacco companies collaborated with the US film industry for decades to push smoking and promote tobacco brands. Tobacco firms invested millions of dollars in cross-promotion and product placement, based on their own conclusion that movies are powerful marketing tools.

The business collaborations described in these tobacco industry files have guided the development of policies to end the film industry's usefulness to the global tobacco industry.

Monitoring tobacco content on screen | Finally, two decades of data on the presence of tobacco in mainstream films — right up to last Saturday night — allow researchers to track kids' exposure. We can all use this real-time data to hold particular media companies, producers, and others in the film industry accountable for keeping kids safe.

The decision to include smoking in movies ultimately rests with the people who create the movies and the studios that pay for their production and distribution; any effort to affect when smoking is portrayed in movies and other entertainment media is logically focused on the production studios rather than on the tobacco industry. — US Surgeon General, 2012