1. Atlantic Ecology Division, National Health and Environmental Effects Research Laboratory (NHEERL), Office of Research and Development (ORD), U.S. Environmental Protection Agency (U.S. EPA); Narragansett Rhode Island 02882 USA
2. Ecosystems Research Division, National Exposure Research Laboratory (NERL), ORD, U.S. EPA; Athens Georgia 30605 USA
3. Toxicity Assessment Division, NHEERL, ORD, U.S. EPA; Research Triangle Park North Carolina 27711 USA