1. Mitsukaido Laboratories, Institute of Environmental Toxicology, 4321 Uchimoriya-Cho, Mitsukaido-Shi, Ibaraki-Ken, 303, Japan
2. The National Toxicology Program, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, North Carolina 27709 USA
3. Analytical Sciences Inc., 100 Capitol Drive, Durham, North Carolina 27713 USA
4. Miami Valley Laboratories, The Proctor & Gamble Company, P.O. Box 398707, Cincinnati, Ohio 45239 USA