And even after taking account of alcohol use and smoking among their peers, both of which are known to influence initiation of smoking, these teenagers were still 32 per cent more likely to have tried a cigarette themselves.
The findings have prompted calls for film makers, regulators and politicians to review their policies on film classification for movies which glamorise smoking.
The UK Centre for Tobacco Control Studies wants such films to fall under the same stringent rules applied to films showing violence and sex, arguing that children need to be protected from potentially harmful imagery.
The University of Bristol study was led by Dr Andrea Waylen, Dr Sam Leary and Professor Andrew Ness in partnership with Dartmouth Medical School in the US.
Research in the US has shown that films depict smoking as an attractive behaviour rather than associating it with negative outcomes, such as ill health, making it similar to aspirational tobacco advertising imagery which is banned in the UK.
Adolescents in the US with high exposure to films showing smoking are two to three times more likely to start smoking than others, even after other factors such as alcohol use and peer pressure are taken into account.
The study, using data collected from the Children of the 90s project, looked at 5,166 15-year-olds and asked whether they had seen 50 films which were randomly selected from 366 box office hits released between 2001 and 2005 and compared these findings with whether they had ever tried a cigarette or were current smokers.
Dr Waylen, from the School of Oral and Dental Sciences, said: “More than half the films shown in the UK that contain smoking are rated UK15 or below, so children and young teenagers are clearly exposed.
“Our results confirm an association between this exposure and youth smoking in this country, indicating that raising the certification to 18 in the UK is likely to lower smoking rates among youth.
“Given that smoking depictions in films are not consistent with the ban on smoking in public places in the UK and that the relationship may be causal, a precautionary principle should be pursued. Films ought to be rated by exposure to smoking in the same way that they are currently rated by level of violence. Smoking and its adverse consequences are certainly a larger public health problem. Such a policy would also make the movie ratings system consistent with the ban on tobacco advertising in all other media.”
The study’s results are cited by the UK Centre for Tobacco Control Studies in an article published in Thorax, a International Journal of Respiratory Medicine published by the British Medical Journal.
Its authors, Dr Ailsa Lyons and Professor John Britton, detail their efforts to persuade the national regulator, the British Board of Film Classification (BBFC), and the government’s Department for Culture Media and Sport (DCMS) to reclassify films depicting smoking.
In response to the allegation that current practice in film classification is failing to protect children from “this potential harmful imagery”, the BBFC told the authors that their guidelines were “proportionate; take due account of the available evidence of harm; and reflect the clear wishes of the public”.