1. Department of Epidemiology, College of Public Health, The University of Iowa, Iowa City, Iowa;
2. National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio;
3. Department of Epidemiology and Biostatistics, School of Public Health, State University of New York at Albany, Rensselaer, New York;
4. Stewart Exposure Assessments, LLC, Arlington, Virginia;
5. Birth Defects Epidemiology and Surveillance Branch, Texas Department of State Health Services, Austin, Texas