Exposure to environmental tobacco smoke and risk of adenocarcinoma of the lung

We conducted a case-control study of adenocarcinoma of the lung and exposur e to environmental tobacco smoke (ETS) in 7 countries. We interviewed 70 ca ses of adenocarcinoma of the lung and 178 population or hospital controls. All subjects had smoked fewer than 400 cigarettes in their lifetimes. Ever exposure to ETS from the parents during childhood was associated with a dec reased risk [odds ratio (OR) 0.6, 95% confidence interval (CI) 0.3-1.2], an d there was a suggestion of a decreasing trend in risk with increasing dura tion of exposure. Ever exposure to ETS from the spouse was not associated w ith an increased risk (OR 1.0, 95% CI 0.5-1.8), while the OR of ever exposu re to ETS at the workplace was 1.5 (95% CI 0.8-3.0). For both exposure sour ces, an increased risk was observed among the highly exposed, and the OR am ong those with the highest duration of exposure to ETS from the spouse or a t the workplace was 1.8 (95% CI 0.5-6.2). A similar risk was estimated for current exposure to ETS from either source. Our results confirm previous re ports of a weak effect of adult ETS exposure on risk of adenocarcinoma of t he lung. Bias and confounding cannot be excluded as explanations for the ap parent decrease in risk from childhood exposure. (C) 1999 Wiley-Liss, Inc.