The Source to Outcome Approach provides a framework for improving and modernizing human health risk assessments where uncertainty is reduced through integrating hazard and exposure characterization. For non-volatile pesticides, using human-relevant particle size distributions from agricultural spray applications and mixing/loading scenarios more accurately estimates a Human Equivalent Concentration (HEC) for human health risk assessments. Inhalation exposure is typically measured with personal air monitors and environmental sampling without consideration of particle size distributions. Side-by-side air sampling with a Respicon TM particle sampler characterized the size distribution of aerosols captured on personal air monitors (i.e., OVS tubes) during spraying to derive a particle size distribution for respiratory dosimetry modelling. Computational Fluid Dynamic (CFD) models further link this exposure information with target site-specific dosimetry for the rat and human to calculate surface concentrations of deposited aerosol formulations in discrete regions of the respiratory tract. CFD models are especially useful to provide a more accurate reflection of the deposition necessary to initiate the cascade of events resulting from irritant mediated response in the upper respiratory tract. The Source to Outcome Approach is demonstrated, using a specific case study, by integrating exposure characterization and respiratory dosimetry modelling to refine the human health risk assessment of irritant aerosols.

Applying the source to outcome approach for exposure, hazard and risk evaluation of an irritant aerosol

254th National Meeting (2017)

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