Persistent Organic Pollutants and Population Based Human Exposure. D. H. Bennett, T. E. McKone, and W. E. Kastenberg, Lawrence Berkeley National Laboratory and University of California
Many persistent organic pollutants travel long distances in the environment, exposing more people to the chemical, increasing the potential of an adverse effect resulting from the chemical exposure. Thus, an approach for evaluating potential impacts of a chemical release into the environment that accounts for area impacted by the chemical release and hence, the number of people exposed to the chemical is desirable. Such an approach should incorporate the appropriate modeling scale for each chemical. We determine the modeling scale (i.e. local, regional, or global scale) analytically from a moving Lagrangian air cell and non-moving compartments. The concentration is reduced with distance based on degradation in air, transfer to and subsequent degradation in vegetation, surface water, and soil. From the spatially dependent multimedia concentrations, the exposure to an individual is estimated, incorporating multiple exposure pathways. Five conceptual models are presented and compared for evaluating the population based human exposure. Each model incorporates different modeling scales and population density. We evaluate the differences between calculation methods and compare these differences to other sources of uncertainties in the calculations and evaluate the relative differences between the models as the characteristic travel distance increases. The measure of population based human exposure can be used by decision-makers in several environmental analyses.
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