1. Environmental Health Laboratory, California Department of Public Health, 850 Marina Bay Pkwy, Richmond, California 94804, United States
2. Office of Water, AAAS Science & Technology Policy Fellow, Program Participant in the U.S. Environmental Protection Agency, Washington, District of Columbia 20460, United States
3. Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, Ohio 45220, United States
4. U.S. Environmental Protection Agency, Region 9, San Francisco, California 94105, United States