1. Birth Defects Registry, Bureau of Environmental and Occupational Epidemiology New York State Department of Health Albany New York USA
2. Department of Epidemiology and Biostatistics, School of Public Health University at Albany Rensselaer New York USA
3. Department of Epidemiology, School of Public Health Boston University Boston Massachusetts USA
4. Department of Epidemiology, College of Public Health University of Iowa Iowa City Iowa USA