1. U.S. Environmental Protection Agency/National Health and Environmental Effects Research Laboratory/Toxicity Assessment Division, Research Triangle Park, North Carolina 27711 United States
2. CB&I Federal Services, Cincinnati, Ohio 45212 United States
3. U.S. Geological Survey/Leetown Science Center, Kearneysville, West Virginia 25430 United States
4. U.S. Environmental Protection Agency/National Risk Management Research Laboratory/Water Supply and Water Resources Division, Cincinnati, Ohio 45220 United States
5. U.S. Geological Survey/South Atlantic Water Science Center, Columbia, South Carolina 29210 United States