A series of adverts has recently appeared in newspapers across Europe comparing the risk of lung cancer from passive smoking with a variety of other apparent risks from everyday activities (see fig 1). The implication is that the increased risk of lung cancer among those exposed to other people's tobacco smoke, of around 20%, is minuscule in comparison with the apparent 500% increased risk of lung cancer associated with a diet high in saturated fat, the 180% increase with frequent cooking with rape seed oil, the 60% increase with drinking 1–2 glasses of whole milk per day, or the 70% reduction in risk associated with high fruit diet. The advert, entitled “What risks do you take?” is cleverly tailored to the public's scepticism about the apparent health risks of everyday activities.1 A few weeks after the adverts appeared the main headline in a major British Sunday newspaper was “Beefburgers linked to cancer.”2 The frequent appearance of such news stories, which are then often contradicted or reversed by subsequent reports, leads to distrust in pronouncements from experts—what may be called the “now they're saying” syndrome.

The central message of the advert is that passive smoking is not “really a meaningful health risk to people who have chosen not to smoke.” Readers were asked to write for a copy of a report “Environmental tobacco smoke and lung cancer: an evaluation of the risk,” from a team of authors referred to as “The European Working Group on Environmental Tobacco Smoke and Lung Cancer.”3 The report focused only on the risk of lung cancer, while the adverts referred to an absence of risks of health problems in general with passive smoking. The title of the working group has the ring of authority to it, although …