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Effectiveness of cigarette warning labels in informing smokers about the risks of smoking: findings from the International Tobacco Control (ITC) Four Country Survey
  1. D Hammond1,
  2. G T Fong2,
  3. A McNeill3,
  4. R Borland4,
  5. K M Cummings5
  1. 1Department of Health Studies and Gerontology, University of Waterloo, Waterloo, Ontario, Canada
  2. 2Department of Psychology, University of Waterloo
  3. 3Division of Public Health & Epidemiology, University College London, London, UK
  4. 4The Cancer Council, Victoria, Melbourne, Australia
  5. 5Department of Health Behavior Roswell Park Cancer Institute, Buffalo, New York, USA
  1. Correspondence to:
 Dr David Hammond
 Department of Health Studies and Gerontology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada; dhammond{at}


Background: Health warnings on cigarette packages are among the most common means of communicating the health risks of smoking. However, few studies have evaluated the impact of package warnings on consumer knowledge about tobacco risks.

Objective: The aim of the current study was to use nationally representative samples of adult smokers from the United States (USA), the United Kingdom (UK), Canada (CAN), and Australia (AUS) from the International Tobacco Control Four Country Survey (ITC-4) to examine variations in smokers’ knowledge about tobacco risks and the impact of package warnings.

Methods: A telephone survey was conducted with 9058 adult smokers from the following countries: USA (n  =  2138), UK (n  =  2401), CAN (n  =  2214) and AUS (n  =  2305). Respondents were asked to state whether they believed smoking caused heart disease, stroke, impotence, lung cancer in smokers, and lung cancer in non-smokers. Respondents were also asked whether the following chemicals are found in cigarette smoke: cyanide, arsenic and carbon monoxide.

Findings: Smokers in the four countries exhibited significant gaps in their knowledge of the risks of smoking. Smokers who noticed the warnings were significantly more likely to endorse health risks, including lung cancer and heart disease. In each instance where labelling policies differed between countries, smokers living in countries with government mandated warnings reported greater health knowledge. For example, in Canada, where package warnings include information about the risks of impotence, smokers were 2.68 (2.41–2.97) times more likely to agree that smoking causes impotence compared to smokers from the other three countries.

Conclusion: Smokers are not fully informed about the risks of smoking. Warnings that are graphic, larger, and more comprehensive in content are more effective in communicating the health risks of smoking.

  • CATI, computer assisted telephone interviewing
  • FCTC, Framework Convention on Tobacco Control
  • ITC-4, International Tobacco Control Four Country Survey
  • warning labels
  • health knowledge
  • smoking behaviour
  • tobacco constituents
  • tobacco control policy

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  • * Note that new UK package warnings (one of 16 text warnings covering 30% of the package) were implemented in January 2003, following Wave 1 of the ITC-4 survey.

  • * Note that carbon monoxide yields are listed on Canadian and Australian package, while one of the four US warning messages mentions carbon monoxide.

  • Competing interests: none declared

  • Contributions of authors: David Hammond conducted the analyses and was the principal author of the manuscript. Geoffrey T Fong, K Michael Cummings, and Ron Borland conceived of the study and each contributed to the writing of the manuscript, along with Ann McNeill.

    Ethics approval: The study protocol was cleared for ethics by the Institutional Review Boards or Research Ethics Boards in each of the countries: the University of Waterloo (Canada), Roswell Park Cancer Institute (USA), the University of Illinois-Chicago (USA), the University of Strathclyde (UK), and The Cancer Council Victoria (Australia).