Overview of the Multimedia Environmental Pollutant Assessment System (MEPAS)

ABSTRACT The Multimedia Environmental Pollutant Assessment System (MEPAS) is a physics-based risk computation code that integrates source-term, transport, and exposure models. Developed by Pacific Northwest Laboratory(a) for screening and ranking of environmental problems, MEPAS is designed for site-specific assessments using readily available information to estimate potential health impacts. Risk values are computed for chemical and radioactive carcinogens; while hazard quotients, based on reference doses, are computed for noncarcinogens. This system has wide applicability to a range of environmental problems using air, groundwater, surface-water, overland, and exposure models. Whenever available and appropriate, U.S. Environmental Protection Agency guidance and models were used to facilitate compatibility and acceptance. Although based on relatively standard transport and exposure computation approaches, the unique feature of MEPAS is that these approaches are integrated into a single system. The use of...