1. Clinical Research Branch, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
2. Social & Scientific Systems, Inc., Durham, North Carolina, USA
3. Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
4. Johns Hopkins Berman Institute of Bioethics, Baltimore, Maryland, USA
5. Department of Sociology, University of Vermont, Burlington, Vermont, USA
6. Office of Research Regulatory Affairs, Children’s National Medical Center, Silver Spring, Maryland, USA
7. Department of Pediatrics, George Washington University, School of Medicine and Health Sciences, Washington, DC, USA
8. Office of the Director, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina, USA