1. Department of Epidemiology, College of Public Health, University of Iowa, Iowa City
2. Department of Nutrition and Food Hygiene, School of Public Health, Medical College, Wuhan University of Science and Technology Wuhan, Hubei, China
3. State Hygienic Laboratory, University of Iowa, Iowa City
4. Department of Pediatrics, New York University School of Medicine, New York
5. Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City