1. Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, China
2. Changsha Center for Disease Control and Prevention, Changsha, China
3. Changde Center for Disease Control and Prevention, Changde, China
4. Hunan Provincial Center for Disease Control and Prevention, Changsha, China
5. Shanxi Provincial Center for Disease Control and Prevention, Taiyuan, China