Multimedia Environmental Pollutant Assessment System Research Articles

Comparative study of multimedia models applied to the risk assessment of soil and groundwater contamination sites in Taiwan

The purpose of this study was to explore the applicability of two popular multimedia risk assessment models to three different soil and groundwater contamination sites in Taiwan. The Multimedia Environmental Pollutant Assessment System (MEPAS) and the Multimedia Contaminant Fate, Transport, and Exposure Model (MMSOILS) were selected because of their wide application and use. Three soil and groundwater contamination sites in Taiwan were employed as illustrative examples in the comparison of these two risk assessment models. Three exposure pathways were investigated, categorized as oral ingestion, dermal absorption, and inhalation. The results show that MEPAS and MMSOILS calculated similar cancer risks and hazard quotients in general, but were different by two orders of magnitude in cancer risk estimates for sites contaminated by volatile organic compounds (VOC). Using MMSOILS may not be appropriate for risk assessment of such sites, as it does not account for indoor inhalation as a potential exposure pathway in its risk calculations. Water ingestion, dermal absorption when showering and indoor inhalation were the three most predominant contributing exposure pathways for risk development among sites contaminated by VOCs. On the other hand, crop and meat ingestion were more important exposure pathways in the context of sites with non-VOC pollutants, because these hydrophobic contaminants may be bio-accumulative in plants and animals, and consequently enter the human body via food chains.

Commentary on Fate and Exposure Models: Description of the Multimedia Environmental Pollutant Assessment System (MEPAS®) Version 3.2, with Application to a Hypothetical Soil Contamination Scenario

(1998). Commentary on Fate and Exposure Models: Description of the Multimedia Environmental Pollutant Assessment System (MEPAS®) Version 3.2, with Application to a Hypothetical Soil Contamination Scenario. Journal of Soil Contamination: Vol. 7, No. 3, pp. 283-300.

Risk computation for environmental restoration activities

Environmental restoration activities planned by the U.S. Department of Energy (DOE) and other agencies will require consideration of long-term environmental and public health risks. These restoration activities will require risk computations capabilities in support of baseline, reme- diation, and residual risk assessments. During the initial stages of problem characterization, risk screening approaches are useful; then, as more data become available, more detailed risk evaluations are appropriate. While a wide variety of models address specific site characteristics, transport media, and impact type, only a few models address the broad range of long-term public health issues encountered in environmental resto- ration activities. One such model, the Multimedia Environmental Pollutant Assessment System (MEPAS®) (© Battelle Memorial Institute, 1989, 1993), integrates radioactive and hazardous materials risk computations for major exposure routes via air, surface water, groundwater, and over- land flow transport. By considering a broad range of potential environmental issues, models such as MEPAS can be used to help prioritize potential environmental problems. An illustrative application is described involving relative risk-based evaluation of the mixed waste in underground tanks. The results provide an indication of (1) the relative importance of each of the constituents from a public-health standpoint, and (2) the sensitivity of those rankings to important input parameters.

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...