1. Department of Epidemiology; Graduate School of Public Health; University of Pittsburgh; Pittsburgh PA
2. Department of Pharmaceutical Science; School of Pharmacy; University of Pittsburgh; Pittsburgh PA
3. Department of Obstetrics, Gynecology, and Reproductive Sciences; School of Medicine; University of Pittsburgh; Pittsburgh PA
4. Departments of Pediatrics and Epidemiology, Biostatistics and Occupation Health; McGill University; Montreal QC Canada
5. Department of Pathology; University of Pittsburgh; Pittsburgh PA