The Evolution and Future of Environmental Fugacity Models

Abstract

In this chapter we first review the concept of fugacity as a thermodynamic equilibrium criterion applied to chemical fate in environmental systems. We then discuss the evolution of fugacity-based models applied to the multimedia environmental distribution of chemicals and more specifically to bioaccumulation and food web models. It is shown that the combination of multimedia and bioaccumulation models can provide a comprehensive assessment of chemical fate, transport, and exposure to both humans and wildlife. A logical next step is to incorporate toxicity information to assess the likelihood of risk in the expectation that most regulatory effort will be focused on those chemicals that pose the highest risk. This capability already exists for many well-studied chemicals but we argue that there is a compelling incentive to extend this capability to other more challenging chemicals and environmental situations and indeed to all chemicals of commerce. Finally, we argue that deriving the full benefits of these applications of the fugacity concept to chemical fate and risk assessment requires continued effort to develop quantitative structure–activity relationships (QSARs) that can predict relevant chemical properties and programs to validate these models by reconciliation between modeled and monitoring data.