1. Tobacco and Volatiles Branch, Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
2. Center for Tobacco Products, Food and Drug Administration, Silver Spring, MD, USA
3. Metabolic Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
4. Digestive Oncology Research Center, Digestive Diseases Research Institute, Tehran University of Medical Sciences, Tehran
5. Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY, USA
6. Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy