1 Department of Epidemiology, School of Public Health, Zhengzhou University, No. 100 of Science Avenue, Zhengzhou 450001, China. Electronic address: yhy@zzu.edu.cn.
2 Department of Epidemiology, School of Public Health, Zhengzhou University, No. 100 of Science Avenue, Zhengzhou 450001, China.
3 Department of Toxicology, Henan Center for Disease Control and Prevention, Zhengzhou 450016, China.