1. Xiangya School of Public Health, Central South University, Changsha, Hunan, China
2. Hunan Provincial Key Laboratory of Clinical Epidemiology, Central South University, Changsha, Hunan, China
3. Institute of Children Health, Hunan Children’s Hospital, Changsha, Hunan, China
4. Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang, Hunan, China