1. Skin and Allergy Research Unit Division of Dermatology Department of Medicine Faculty of Medicine Chulalongkorn University Bangkok Thailand
2. Center for Excellence in Biostatistics Faculty of Medicine Chulalongkorn University Bangkok Thailand
3. Division of Gastroenterology Department of Medicine Faculty of Medicine Chulalongkorn University Bangkok Thailand
4. Department of Preventive and Social Medicine Faculty of Medicine Chulalongkorn University Bangkok Thailand
5. Division of Toxicology Department of Medicine Faculty of Medicine Chulalongkorn University Bangkok Thailand