1. Epidemiology 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. Department of Ophthalmology, Duke University Medical School, Durham, North Carolina, USA
3. Biostatistics and Computational Biology Branch, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina, USA
4. Westat, Durham, North Carolina, USA
5. Social & Scientific Systems, Inc., Durham, North Carolina, USA
6. Occupational and Environmental Epidemiology Branch, National Cancer Institute, NIH, DHHS, Rockville, Maryland, USA
7. Department of Medicine, Duke University Medical School, Durham, North Carolina, USA