1. U.S. Environmental
Protection Agency Office of Research and Development National Exposure
Research Laboratory, Cincinnati, Ohio 45268, United States
2. U.S. Environmental
Protection Agency Office of Water Office of Science and Technology, Washington, D.C. 20460, United States
3. U.S. Environmental
Protection Agency Office of Research and Development, National Health
and Environmental Effects Research Laboratory, Corvallis, Oregon 97333, United States