1. Guizhou Provincial Centre for Disease Control and Prevention, Guiyang, Guizhou, China.
2. The Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education School of Public Health, Guizhou Medical University, Guiyang, Guizhou, China.
3. Qiandongnan Centre for Disease Control and Prevention, Kaili, Guizhou, China.
4. National Centre for Food Safety Risk Assessment, Beijing, China.