1. Department of Human Ecology, Graduate School of Medicine; The University of Tokyo; Bunkyo-ku Tokyo, 113-0033 Japan
2. Carolina Population Center; The University of North Carolina at Chapel Hill; Chapel Hill North Carolina 27516
3. Nagasaki Prefectural Institute of Environment and Public Health; Omura-shi Nagasaki, 856-0026 Japan
4. Department of International Health, Institute of Tropical Medicine (NEKKEN), Nagasaki-shi; Nagasaki University; Nagasaki, 852-8523 Japan
5. Fujian Provincial Center for Disease Control and Prevention; Fuzhou Fujian, 350001 China
6. Department of Epidemiology, School of Public Health; Fujian Medical University; Fuzhou Fujian, 350108 China