1. School of Public Health, Xi’an Jiaotong University Health Science Center, Key Laboratory of Trace Elements and Endemic Diseases, Collaborative Innovation Center of Endemic Disease and Health Promotion for Silk Road Region, Xi’an 710061, China
2. School of Nursing, Lanzhou University, Lanzhou 730000, China
3. Department of Integrative Medical Biology, University of Umeå, 901 87 Umeå, Sweden