1. Department of Epidemiology and Health Statistics, School of Public Health and Management, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region, China
2. Department of Science and Education, Qinghai Provincial People’s Hospital, Xining, Qinghai Province, China
3. Key Laboratory of Environmental Factors and Chronic Disease Control, Ningxia Medical College, Yinchuan, Ningxia Hui Autonomous Region, China