1. Department of Global and Community Health George Mason University Fairfax Virginia USA
2. Perelman School of Medicine University of Pennsylvania Philadelphia Pennsylvania USA
3. Department of Pediatrics Division of Endocrinology The Children's Hospital of Philadelphia Philadelphia Pennsylvania USA
4. Westat Inc Durham North Carolina USA
5. Department of Radiology The Children's Hospital of Philadelphia Philadelphia Pennsylvania USA
6. Department of Pediatrics Division of Gastroenterology Hepatology and Nutrition The Children's Hospital of Philadelphia Philadelphia Pennsylvania USA
7. Epidemiology Branch National Institute of Environmental Health Sciences National Institutes of Health Research Triangle Park Durham North Carolina USA
8. Biostatistics and Computational Biology Branch National Institute of Environmental Health Sciences National Institutes of Health Research Triangle Park Durham North Carolina USA