1. Department of Environmental Health and Occupational Medicine, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
2. Department of Occupational Hazard Assessment, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
3. Department of Periodical Press and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
4. Chinese Evidence-Based Medicine Center, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China