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

Abstract

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.