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Guidance for Selecting Input Parameters for Modeling Pesticide Concentrations in Groundwater Using the Pesticide Root Zone Model - Version 1.0

The Pesticide Root Zone Model Groundwater (PRZM-GW) was developed as a regulatory model to estimate pesticide concentrations in vulnerable groundwater sources as part of a North American Free Trade Agreement (NAFTA) to develop a harmonized groundwater modeling protocol. The Office of Pesticide Programs implemented the use of PRZM-GW as an exposure model in 2012.

More information about PRZM-GW.

EPA's Office of Pesticide Programs (OPP), in coordination with Health Canada’s Pesticide Management Regulatory Agency (PMRA), developed this guidance document to help model users select and prepare the appropriate input values for groundwater aquatic exposure modeling. Using this guidance document should improve the consistency in modeling the fate of pesticides in the environment and ultimately the overall quality of risk assessments.

This document is intended as guidance for model users. If there is a need to deviate from this guidance during risk assessment, the model user should provide adequate justification for model inputs in the assessment. This guidance document reflects the current policy for groundwater modeling for the OPP and the PMRA.

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