Keson Theppeang and Brian S. Schwartz are with the Department of Environmental Health Sciences, Division of Occupational and Environmental Health; Thomas A. Glass and Brian S. Schwartz are with the Department of Epidemiology; and Keson Theppeang, Karen Bandeen-Roche, and Charles A. Rohde are with the Department of Biostatistics, all at the Johns Hopkins Bloomberg School of Public Health, Baltimore, MD. Andrew C. Todd is with the Department of Community and Preventive Medicine, Mount Sinai School of...