1. Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA;
2. Department of Environmental Health, University of Cincinnati, Cincinnati, Ohio, USA;
3. Harvard School of Public Health, Harvard University, Boston, Massachusetts, USA;
4. Department of Psychology, Children’s Hospital of Philadelphia, and University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA