1 Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA. Electronic address: achoi@hsph.harvard.edu.
2 School of Stomatology, China Medical University, Shenyang, China.
3 School of Public Health, China Medical University, Shenyang, China.
4 Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA; Department of Neurology, Children's Hospital, Boston, USA.
5 Mianning Center for Disease Control and Prevention, Xichang, Sichuan, China.
6 Sichuan Center for Disease Control and Prevention, Chengdu, Sichuan, China.
7 Center for Disease Control and Prevention of Liangshan Perfecture, Xichang, Sichuan, China.
8 Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA; Institute of Public Health, University of Southern Denmark, Odense, Denmark.