Biological Systems and Engineering Division Lawrence Berkeley National Laboratory Berkeley CA 94720 USA;
Department of Gastroenterology Nanjing Drum Tower Hospital Nanjing University Medical School Nanjing Jiangsu 210008 China;
Department of Obstetrics and Gynecology Peking University Third Hospital Beijing 100191 China;
Tobacco; Thirdhand smoke; Tobacco-specific nitrosamines; Genotoxicity; Carcinogenesis;