1. Gerontology Department of Xiangya Hospital, Central South University, Changsha, Xiangya road 238, Hunan Province 410078, P. R. China
2. Department of Radiology, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Taiping road 27, Beijing, 100088, P. R. China
3. Department of Chronic and Non-communicable Diseases Control, City Center for Disease Control and Prevention, Jingyi Road 58, Urumqi, 830026, P. R. China
4. Department of Occupational and Environmental Health, Xiangya School of Public Heath, Central South University, Xiangya Road 238, Changsha, Hunan Province 410078, P. R. China