1. Department of Epidemiology and Biostatistics, Michigan State University College of Human Medicine, East Lansing, Michigan, USA
2. Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
3. Social & Scientific Systems, DLH Holdings Corporation, Durham, North Carolina, USA
4. Department of Neurology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
5. Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, USA
6. Department of Medicine, University of Washington, Seattle, Washington, USA
7. Department of Epidemiology, University of Washington, Seattle, Washington, USA