1. Department of EpidemiologyCollege of Public Health, University of Iowa Iowa City Iowa
2. Department of Occupational and Environmental HealthUniversity of Iowa Iowa City Iowa
3. Center for Health Effects of Environmental ContaminationUniversity of Iowa Iowa City Iowa
4. Department of Public Health SciencesUniversity of Virginia Charlottesville Virginia
5. Birth Defects Epidemiology and Surveillance BranchTexas Department of State Health Services Austin Texas