1. Department of Epidemiology, and
2. Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
3. Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
4. Department of Community and Preventative Medicine, Mount Sinai School of Medicine, New York, New York, USA
5. Department of Biostatistics and Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA