Abstract

Recent field data have shown that toxicity to sediment- and soil-dwelling organisms is not related to the concentration of total extractable PAHs determined using EPA standard methods. Instead, toxic-ity is correlated to the concentration of bioavailable PAHs, as estimated using two new analytical methods, i.e. solid phase microextraction (SPME) of sediment pore water and supercritical fluid (carbon dioxide) extraction (SFE) of sediments. Using chemical measurements of availability, it is now possible to better predict the exposure and toxicity of PAHs, and perhaps other hydrophobic organics, such as PCBs, to ecological receptors in soils and sediments. These bioavailability data can be incorporated into predictions of risk and subsequent remedial decisions. A multi-industry sediment bioavailability program has been initiated to demonstrate the application of these new analytical tools to predict the bioavailability of hydrophobic organic compounds. At the heart of the program is a series of North American case studies that are being conducted by a multi-industry consortium in collaboration with various state and federal regulatory agencies. The goal of these case studies is to generate a chemical and biological database that will serve as the basis for development of regulatory guidance for sediment and soil management. This guidance will incorporate the use of site-specific measures of bioavailability and toxicity for establishing remedial goals and management strategies. The following paper provides a brief overview of five presentations (Ghosh et al., Haw-thorne et al., Jonker et al., Kreitinger et al. and Neuhauser et al.) being given at the MGP 2006 Sym-posium, and describes the path forward for executing a national program to develop federal and state regulatory acceptance of this technical approach.

Key words: bioavailability, polycyclic aromatic hydrocarbons, remediation goals, toxicity