Joint effect of diet and environmental tobacco smoke on risk of lung cancer among nonsmokers. by Brennan, P, Butler, J, Agudo, A, Benhamou, S, Darby, S, Fortes, C, Jöckel, K, Kreuzer, M, Nyberg, F, Pohlabeln, H, Saracci, R, Wichman, H, Boffetta, P