RESUMO
The Chesapeake Bay Program began more than 20 years ago with assessments of a number of key areas, relying on measurements of habitats, plant and animal populations, and physical and chemical conditions. This approach used wildlife as indicators of Bay "health" and of potential threats to human health. The extent of toxic chemical contamination was one of the assessment endpoints in the original survey. When the initial assessment was completed in 1983, the results of Bay-wide surveys indicated that several specific waterways were contaminated. These waters, the Elizabeth River, Virginia, the James River, Virginia, and Baltimore Harbor, Maryland, were targeted for specific actions to address the problems of historical and ongoing pollution. Over the past 10 years or more, data on some toxic chemical releases into and levels in the environment have been collected, but these data are limited in scope. Furthermore, these data are not used to assess threats to human health or more generally to nonhuman endpoints. New and existing data on environmental levels of chemicals and effects at low concentrations provide evidence that toxic chemicals may threaten both human and nonhuman health in the wider Bay system.