4 Decision Process
This section is a general guide to determining whether and when a site-specific bioavailability assessment may be appropriate. A simplified flow chart illustrates basic decisions that can be addressed at any time within a cleanup project or risk assessment. Various factors that affect the cost or impact of site-specific bioavailability values are discussed. These factors include the nature and distribution of the contaminants, the soil properties, the exposure pathways, and the site size and volume of contaminated soil. In addition, external factors such as competing regulatory requirements, public perception, or land use issues are also discussed to illustrate how site-specific bioavailability values might be perceived by stakeholders or why these values might not be accepted. This section also provides some general costs for both in vitro and in vivo analysis, along with other nonanalytical costs associated with completing a risk assessment using site-specific bioavailability.