risk-driven approach for subsurface site characterization

We present a probabilistic framework to addressing adverse human health effects due to groundwater contamination. One of the main challenges in health risk assessment is in relating it to subsurface data acquisition and to improvement in our understanding of human physiological responses to contamination. In this paper we propose to investigate this problem through an approach that integrates flow, transport and human health risk models with hydrogeological characterization. A human health risk cumulative distribution function is analytically developed to account for both uncertainty and variability in hydrogeological as well as human physiological parameters. With our proposed approach, we investigate under which conditions the reduction of uncertainties from flow physics, human physiology and exposure related parameters might contribute to a better understanding of human health risk assessment. Results indicate that the human health risk cumulative distribution function becomes less sensitive to uncertainty in physiological parameters at lower risk values associated with longer traveltimes. We also present a graphical tool that allows to investigate the relative impact of hydrogeological and physiological parameters in human health risk. A metric α that relates hydrogeological uncertainty to physiological uncertainty was developed to help decision makers set priorities in data acquisition. Other results show that the worth of hydrogeological characterization in human health risk depends on the time the contaminant plume takes to cross the control plane and on the exposure duration of the population to certain chemicals.