Department of Global Health, School of Health Sciences, Wuhan University, 115# Donghu Road, Wuhan, China; Global Health Institute, Wuhan University, 115# Donghu Road, Wuhan, China. Environmental Health Laboratory, Department of Public Health Sciences, University Hawaii at Manoa, 1960, East West Rd, Biomed Bldg, D105, Honolulu, USA. Department of Global Health, School of Health Sciences, Wuhan University, 115# Donghu Road, Wuhan, China; Global Health Institute, Wuhan University, 115# Donghu Road, Wuhan, China. Electronic address: xianghao@whu.edu.cn.