Objectives: This study was undertaken to determine whether exposure at work to environmental tobacco smoke is associated with an increased risk of lung cancer.
Methods: Data from 14 studies providing information on lung cancer and exposure to environmental tobacco smoke at work were examined. Six quality criteria were developed for determining usable data. A meta-analysis was performed to obtain a combined risk for those data that met the quality restrictions.
Results: Five studies met the quality standards. Their combined relative risk was 1.39 (95% confidence interval [CI] = 1.15, 1.68) based on 835 lung cancer cases. In various meta-analyses prepared by tobacco industry employees or consultants, no increase in risk was found. The main reason for this difference is that the earlier analysts failed to find errors in 2 underlying studies that resulted in overweighting of the odds ratios from those studies, both of which were less than unity.
Conclusions: When appropriate cognizance is taken of the quality of data inputs, the increase in lung cancer risk from workplace exposure to environmental tobacco smoke is about the same as that from household exposure.