Presentation to the MPAA, February 23, 2007
Jonathan M. Samet, M.D., M.S.
Professor and Chairman, Department of Epidemiology
Johns Hopkins Bloomberg School of Public Health
615 N. Wolfe St., Suite W6041
Baltimore, MD, 21205
Download Powerpoint: "The health effects of smoking in the US and globally"
This note provides comments concerning my presentation to the MPAA, which provided background for the meeting of Dean Barry Bloom, Dr. Jay Winsten, and myself with the MPAA on February 23, 2007. I was asked to provide comments on the evidence concerning the health effects of active and passive smoking, giving emphasis to the adverse effects on children who smoke, on addiction to nicotine, and on the findings of studies addressing exposure to smoking in movies and smoking by children. My four main points were summarized at the start:
- Addiction to nicotine begins in adolescence.
- Smoking harms children and kills adults.
- Children who see smoking in movies are at increased risk to start smoking.
- Children are a target for the industry worldwide.
The first block of slides uses the reports of the Surgeon General on smoking and health to cover the many adverse health effects of active and passive smoking. The 1994 report covered the adverse health effects on children; its conclusion is clear with regard to the occurrence of respiratory consequences of smoking, even among adolescents. The 2004 and 2006 reports are the source for the reviews of the effects of active and passive smoking, for which there are now far too abundant causal links to disease causation.
The next block of slides briefly covers current patterns of smoking by American youth. The keys points are: smoking begins in the pre-teen and teen years; addiction begins for many during this period; and some risk factors for smoking have been identified.
Subsequent slides introduce exposure to smoking in the movies and risk for smoking. Data from the 2002 National Youth Tobacco Survey are used to show the high prevalence of exposure to smoking in movies and the comparability of exposure to smoking in movies and of exposure to anti-tobacco messages on TV or via radio. The question of assessment of the consequences of exposure to smoking in movies is introduced with the following thought experiment:
Randomize children to watch the same movies with/without smoking; then measure the rate of initiating smoking in the two groups of children.
This experiment, of course, cannot be done but it offers an opportunity to build from an experimental model for establishing causation to consideration of the "messier" approach of observational studies. I offered commentary on the potential sources of bias coming from the observational approach and how investigators had attempted to address them. I reviewed, in particular, the cohort study carried out in Vermont and New Hampshire by Sargent and colleagues. The two slides (19 and 20) presenting the main findings show a dose-response relationship between exposure to smoking in movies and starting to smoke, even with consideration of parental smoking and other factors. Slide 21 contrasts the excess risk from family factors and from smoking in the movies in order to give perspective on the relative, and in fact comparable, risks of these two sets of factors. In my presentation I pointed to the many other studies, mostly cross-sectional, on the topic; and broadly summarized this literature by qualitatively synthesizing the findings as consistent in showing association of indicators of exposure to smoking in movies with smoking among youths.
Slide 22 shows data on the frequency of smoking in movies over the last 50 years (taken from the review paper by Charlesworth et al.) and of smoking among adults nationally. The contrast is evident. To date, emphasis has largely been given to the impact of exposure to smoking on children in the United States. Yet, movies have a global reach and likely have a unfavorable impact throughout the world, and one that may be even more powerful than on U.S. children.
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