Exposure assessment at a complex chemically and radiologically contaminated site

This paper discusses the techniques for conducting an exposure assessment at a Superfund site. The exposure assessment is the potentially most controversial aspect of risk assessment. It requires decision- making based on subjective assumptions, therefore inviting closer scrutiny from regulators. The exposure assessment is subject to this scrutiny because it is used to identify exposure pathways and to estimate contaminant concentrations to which potential receptors may be exposed. The exposure assessment is divided into three parts: characterizing the exposure setting, identifying exposure pathways and quantifying the exposure. The first component of the assessment includes analyses of contaminant and receptor characteristics which are used to identify potential exposure pathways for three periods of institutional control. Exposure concentrations are determined from a combination of characterization data, disposal inventory data and environmental fate and transport modeling data. Specific intake values are then calculated for each of the identified pathways using the exposure concentrations and other pathway-specific intake variables