1. Drug Safety Research and Development, Pfizer Global Research and Development, San Diego, CA 92064, California, USA
2. United States Food and Drug Administration, Center for Drug Evaluation Research, Office of New Drugs, Rockville, Maryland, USA
3. DuPont Company, Experimental Station, Wilmington, Delaware, USA
4. United States Environmental Protection Agency, National Center for Environmental Assessment, Washington, DC, USA
5. WIL-Biotechnics, Inc., Hillsborough, North Carolina, USA
6. ILSI Health and Environmental Sciences Institute, Washington, DC, USA