1. Department of Environmental Health Sciences and
2. Departments of Epidemiology and Medicine, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
3. Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins University, Baltimore, Maryland, USA
4. Centro de Investigación y de Estudios Avanzados – Instituto Politécnico Nacional (CINVESTAV-IPN), Mérida, Yucatán, México
5. Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México