1. Wadsworth Center, New York State Department of Health, Albany, New York 12201, United States
2. Department of Pathology and Laboratory Medicine, University of Vermont, Burlington, Vermont 05405, United States
3. The Burlington HC Research Group, Inc., Jericho, Vermont 05465, United States
4. Experimental Pathology Laboratories, Sterling, Virginia 20167, United States
5. National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, United States
6. Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario K1A 0K9, Canada