The authors performed a meta-analysis of published literature concerning marketing tobacco to children. Previously, DiFranza (one of the authors) has shown that exposure to marketing causes children to initiate tobacco use. Other studies on tobacco addiction indicate that earlier tobacco use initiates more severe and persistent addiction behavior. The researchers' intent was to quantify the causal relationship between "pro-tobacco marketing and media" (consisting of tobacco advertising, promotions or samples, or pro-tobacco depiction in films, TV or videos) and children's attitudes toward use, initiation of use, tobacco use status, or progression to heavier use.

The study consisted of a key word search of several databases to select relevant articles and subsequent analysis using Comprehensive Meta-analysis version 2.2.023. After selection, 51 articles were included; articles had to measure both a tobacco use outcome and exposure to marketing or media. Six tests were applied to evaluate publication bias. Lastly, the authors sorted studies by date to examine whether a 1998 settlement between the tobacco industry and 46 U.S. states banning advertising on billboards and in youth-oriented magazines had had a measurable effect.

Key Findings:

• Exposure to marketing and media (in numerous countries and time periods) more than doubles children's risk of becoming a tobacco user.
• Exposure that does not actively engage the recipient increases odds of tobacco use by approximately 90 percent; when psychological engagement is present, the increase is nearly three-fold; after initiation of use, marketing and media increase progression to heavier use by 42 percent.
• Exposed youth had approximately 50 percent greater odds of holding positive attitudes toward tobacco and twice the odds of initiating use.

This study refutes the tobacco industry's claim that increases in association between exposure and tobacco use is because users attend to marketing more than nonusers. Moreover, recent studies showed no decline in effect indicating that the 1998 settlement has been ineffective in restricting youth exposure. The authors believe that the tobacco industry has strategically evaded the restrictions of the settlement. For example, tobacco use in current movies is now comparable to tobacco use in movies from the 1950s.