Pollutants Without Borders: Tracking Cumulative Exposures to Persistent Pollutants. T. E. McKone, D. Mackay, D. H. Bennett, and R. L. Maddalena; University of California Berkeley, Trent University, and Lawrence Berkeley National Laboratory
Many pesticides, combustion products and chemicals in commerce are subject to long range transport (LRT) which can distribute pollutants across regional, continental or even global scales. LRT is an important chemical attribute for cumulative risk assessment as well as comparative environmental risk assessment and life-cycle assessment (LCA). Although LRT has been well studied for pollutants that are simple gases (i.e., NOx, SOx, CO2 and ozone), the LRT and potential impact of multimedia pollutants remains poorly understood. For these pollutants, LRT is governed by a series of complex exchanges among atmospheric gases and particles and among vegetation, soil surface and water. Many of these substances are toxic and bioaccumulate in food webs. They present a unique policy challenge because the source of the pollutant is often separated geographically and jurisdictionally from the region of impact. In this paper, we describe an iterative approach to develop a continental scale multimedia fate and exposure model. Confronting LRT pollutants involves modeling and collection of the relevant data—two areas that must be well integrated to achieve success. We describe research on a model framework and conceptual continental-scale model for multimedia pollutants—based on principles of mass balance, thermodynamics and mechanisms of airborne transport. The conceptual model is being used to direct the collection of relevant data, to gain insight on the complex source-to-dose relationships that exist for LRT multimedia pollutants, and to identify the best way to reduce uncertainty about potential impacts.
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