How the tobacco industry responded to an influential study of the health effects of secondhand smoke

In 1981 an influential Japanese study showed an association between passive smoking and lung cancer. This article documents the tobacco industry's attempts to refute this study by producing a credible alternative study In 1981 Japanese investigator Takeshi Hirayama published a cohort study examining the association of passive smoking and lung cancer among non-smoking wives of smokers in Japan.1 The study concluded that wives of heavy smokers had up to twice the risk of developing lung cancer as wives of non-smokers and that the risk was dose related. The Hirayama study was influential because it launched an extraordinary amount of critical debate 2 3 and has been one of the most frequently cited studies in regulatory proceedings, 4 5 risk assessments,6 and the media.7 The tobacco industry has used a variety of tactics to maintain scientific debate about whether secondhand smoke has any harmful effects. 5 6 8–14 We identify and analyse internal tobacco industry documents that describe the industry's response to the Hirayama study. #### Summary points The tobacco industry generated a study, the “Japanese spousal study,” in an attempt to refute the findings of a 1981 cohort study showing an association between secondhand exposure to tobacco smoke and lung cancer Internal tobacco industry documents describe how the tobacco industry considered multiple strategies to conceal its involvement in the Japanese spousal study The tobacco industry considered funding the study through the Center for Indoor Air Research, a research organisation supported by the tobacco industry, in order to hide industry involvement The parties involved in conducting the study included a tobacco industry scientist, a tobacco industry consultant, an industry law firm, and two Japanese investigators. The consultant was the sole author of the final publication We retrieved documents from the Legacy Tobacco Documents Library (www.legacy.library.ucsf.edu/) and tobacco industry websites …