1. Department of Epidemiology and Biostatistics School of Public Health Tianjin Medical University Tianjin China
2. Department of Project Office Tianjin Women and Children's Health Center Tianjin China
3. Tianjin Key Laboratory of Environment Nutrition and Public Health Tianjin China
4. Tianjin Center for International Collaborative Research on Environment Nutrition and Public Health Tianjin China
5. Population Cancer Research Program and Department of Pediatrics Dalhousie University Halifax Nova Scotia Canada
6. Chronic Disease Epidemiology Laboratory Pennington Biomedical Research Center Baton Rouge Louisiana USA