1. Division of Field Studies and Engineering National Institute for Occupational Safety and Health Cincinnati Ohio USA
2. Department of Epidemiology and Environmental Health, College of Public Health University of Kentucky Lexington Kentucky USA
3. Department of Epidemiology, Gillings School of Global Public Health University of North Carolina Chapel Hill North Carolina USA
4. Department of Biosystems and Agricultural Engineering, College of Agriculture, Food and Environment University of Kentucky Lexington Kentucky USA
5. Arkansas Center for Birth Defects Research and Prevention University of Arkansas for Medical Sciences Little Rock Arkansas USA
6. Division of Birth Defects and Infant Disorders National Center on Birth Defects and Developmental Disabilities Atlanta Georgia USA