Chengdu Municipal Center for Disease Control and Prevention, Chengdu, Sichuan, China.
Ke-Jian Liu
Dept. of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
Long-Ju Ran
Chengdu Municipal Center for Disease Control and Prevention, Chengdu, Sichuan, China.
Xing-Ping Pan
Chengdu Municipal Center for Disease Control and Prevention, Chengdu, Sichuan, China.
