Tobacco-specific lung carcinogen and exposure to passive smoking

To the Editor: We think that the study by Hecht et al. (Nov. 18 issue)¹ does not provide much support for the existing weak epidemiologic evidence that passive smoking increases the risk of lung cancer. The relative risk associated with passive smoking, as calculated by the U.S. Environmental Protection Agency (EPA) in a meta-analysis of 35 studies, was about 1.4². The authors propose that the tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) are responsible for adenocarcinomas in nonsmokers exposed to environmental tobacco smoke. Since this type of carcinoma is predominant among nonsmokers irrespective of their exposure to such smoke,.