The Chesapeake Bay Program of the U.S. Environmental Protection Agency, with cooperation and input from the states of Maryland and Virginia, has developed and is now implementing a toxicant plan of action for monitoring, analysis, and control of toxic and hazardous substances in the Chesapeake Bay estuarine system. Six tasks have been identified in the initial plan. They include: 1. Baseline monitoring of water, sediment, and biota for toxic pollutants in order to assess the current state of the Chesapeake Bay. 2. A source assessment of toxic substances in order to estimate the inputs of toxic pollutants to the region. 3. Determination of the fate, transport, and transformation of toxic substances by physical and chemical processes through the estuarine environment. 4. Effects studies to determine toxicity values and water quality criteria for substances that may accumulate in the food chain and that adsorb to sediment particles. 5. Intensive investigations of small watersheds with the goal of deriving a materials balance model for toxic inputs to the system. 6. The submission of recommendations for implementation that are based on technical reports to management and regulatory agencies.

Ideally, data generated from samples taken in the environmental compartments, that is, bottom sediments, interstitial water, benthic flora and fauna, fluid mud, suspended sediment, nekton, plankton, and the atmosphere can allow for the development of a toxicological profile at selected sampling stations, as well as supply the first integrated Bay-wide baseline data base for toxic substances.

The source assessment task involves effluent monitoring for toxic pollutants, non-point source watershed monitoring, and the measurement of tributary inputs of potential hazardous substances.

The rationale for a toxicological profile monitoring approach is described along with the toxicant plan of action.