1. School of Public Health, North China University of Science and Technology, 063210 Caofeidian District, Tangshan, P.R. China
2. Department of Safety Management and Quality Control, North China University of Science and Technology Affiliated Hospital, 063000 Tangshan, P.R. China
3. Personnel Department, North China University of Science and Technology, 063210 Caofeidian District, Tangshan, P.R. China
4. Beijing Sihuan Pharmaceutical Co. Ltd., 101113 Beijing, P.R. China