1. Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
2. Channing Laboratory, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
3. Centro de Investigación en Salud Poblacional, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México
4. Department of Neurology, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
5. Department of Biology and Environmental Toxicology, University of California at Santa Cruz, Santa Cruz, California, USA
6. Instituto Nacional de Perinatologia, Mexico City, Mexico