PARENT SESSION
TA6 Long-range transport of pesticides and other pollutants
9:00 AM to 12:30 PM, Tuesday, 08 May 2001
Session Chair: M. Matties
Room 6

(192) Source-to-dose relationships for long-range-transport pollutants.

McKone, Thomas^1,2, Bennett, Deborah², Maddalena, Randy², Bodnar, Agnes^1,2, ^{1 2}

ABSTRACT- Many pesticides, combustion products, and other pollutants are subject to long range transport (LRT). This presentation is about evaluating the health and environmental impacts of LRT pollutants. We start by characterizing the problem of linking human exposure/dose calculations to continental- and global-scale transport processes. Next, we identify and evaluate current and emerging approaches for modeling long-range transport and exposure (LRT&E). Persistence and spatial range are commonly used as surrogate metrics for screening potential exposures to LRT pollutants. However, impact assessment requires a more explicit treatment of the source-to-dose relationships. There are number of source-to-dose metrics available (e.g., maximum dose, average population dose, dose fraction, etc.). An adequate source-to-dose metric must consider multiple routes of exposure; operate at many scales, from indoor environments to global scale; and provide clear distinctions among chemicals and exposure pathways. We found that the dose fraction (Df) obtained from a multimedia transport/exposure model has some clear advantages for assessing LRT&E. For a given scenario, the Df is the mass of chemical taken up by the receptor population divided by the mass of chemical released. Examples of Df assessments are provided for several LRT pollutants--including benzene, polycyclic aromatic hydrocarbon (PAH) compounds, dioxin/furan compounds, and pesticide agents such as hexachlorobenzene, gamma-hexachlorocyclohexane (HCH). These assessments reveal that both the magnitude of the Df and the exposure pathways that contribute to the Df differ significantly for the sample compounds. As a result, although the Df currently lacks precision, it is a useful metric for sorting out chemicals according to their potential for impact.

Key words: long-range transport, multimedia models, dose fraction, impact assessment