Guangdong Provincial Center for Disease Control China;
National Institute for Occupational Health and Prevention;
Guangzhou 510300;
Guangdong;
and Poison Control;
Chinese Center for Disease Control and Prevention;
Beijing 100050;
China;
Institute for in vitro Science;
Gaithersburg MD 20878;
Maryland;
USA;
Faculty of Mathematics and Computational Science;
Sun Yat-sen University;
Guangzhou 510275;
Guangdong;
China;