1. Department of Epidemiology and Biostatistics, College of Public Health, Zhengzhou University, 100 Kexue Avenue, Zhengzhou 450001, China
2. Department of Occupational and Environmental Health Sciences, College of Public Health, Zhengzhou University, Zhengzhou 450001, China
3. School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430074, China