The two-dimensional exposure rainfall-runoff assessment (TERRA)watershed model and its use in the FIFRA ecological risk assessment for antimicrobial uses of copper. FIFRA Scientific Advisory Panel Meeting; October 25-26.

Authors: JENKINS, FRED - Us Environmental Protection Agency (EPA); PORTIER, KENNETH - American Cancer Society; CHAMBERS, JANICE - Mississippi State University; SCHLENK, DANIEL - University Of California; KLAINE, STEPHEN - Clemson University; SANDY, MARTHA - California Environmental Protection Agency; ABBOTT, LINDA - Economic Research Serivce (ERS, USDA); CHU, XUEFENG - North Dakota State University; COUPE, RICHARD - Us Geological Survey (USGS); ENGEL, BERNARD - Purdue University; HUDSON, ROBERT - University Of Illinois; KENNEDY, IAN - Health Canada; LUO, YUZHOU - California Environmental Protection Agency; Potter, Thomas

Submitted to: Environmental Protection Agency
Publication Type: Government Publication
Publication Acceptance Date: 11/1/2011
Publication Date: 1/25/2012
Citation: Jenkins, F., Portier, K., Chambers, J., Schlenk, D., Klaine, S., Sandy, M., Abbott, L., Chu, X., Coupe, R.H., Engel, B.A., Hudson, R.J., Kennedy, I.A., Luo, Y., Potter, T.L. 2012. The two-dimensional exposure rainfall-runoff assessment (TERRA)watershed model and its use in the FIFRA ecological risk assessment for antimicrobial uses of copper. FIFRA Scientific Advisory Panel Meeting; October 25-26.. Environmental Protection Agency. http://www.epa.gov/scipoly/sap/meetings/2011/102511minutes.pdf.

Interpretive Summary: The US Environmental Protection Agency relies on simulation models to evaluate potential human and ecological exposures to pesticide active ingredients during their normal and or proposed use. Model outputs guide significant regulatory decisions regarding the legal status of pesticides in all States and territories of the USA. Models are an essential part of the risk assessment process because they allow the Agency to perform nationwide environmental exposure assessments in the absence of nationwide spatially explicit monitoring data for each chemical. The Two-dimensional Exposure Rainfall-Runoff Assessment (TERRA) Watershed Model has been proposed by the American Chemistry Council (ACC) as a refined model for estimating environmental exposure from the use of copper as an antimicrobial pesticide. A panel of experts was convened by the agency to consider strengths and limitations of this model relative to evaluating copper fate and transport in urbanized watersheds. The purpose of the Scientific Advisory Panel consultation was to obtain an independent evaluation of the TERRA watershed-scale model and to gain advice on the application of TERRA as a regulatory model, specifically as applied to the antimicrobial copper risk assessment. Findings are summarized in this report.

Technical Abstract: The USEPA Office of Pesticide Programs (OPP) presented preliminary risk assessments of the two antimicrobial uses of copper during a public hearing held October 25-26, 2011 in Arlington, VA to a Scientific Advisory Panel convened the by the agency. In addition presentations were made on use of the Two-dimensional Exposure Rainfall-Runoff Assessment (TERRA) Watershed Model proposed by the American Chemistry Council (ACC) as a refined model for estimating environmental exposure from the use of copper as an antimicrobial pesticide. The TERRA Model uses a generalized watershed rainfall-runoff, sediment transport, and contaminant transport modeling framework. It is a spatially distributed watershed model which allows for multiple use patterns of antimicrobial copper to be simulated simultaneously across a watershed, thereby providing a cumulative aqueous exposure profile from antimicrobial uses of copper at any point in the watershed. There was agreement among the Panel that an essential requirement for water quality model calibration and validation is a dataset that includes hydrologic, sediment, and water quality measurements spanning at least several years. In the case of the simulated urban watershed scenario described, TERRA calibration and validation were not possible since there are no measured hydrologic, sediment, or copper transport measurements available for this watershed simply because the watershed does not exist. Numerous recommendations were made which should enhance TERRA applications for copper fate and transport modeling in urbanized watersheds.