SAP Minutes No.2015-03 for FIFRA meeting held 9/15-17/2015. A set of scientific issues being considered by the Environmental Protection Agency regarding development of a spatial aquatic model(SAM)for pesticide risk assessment

Authors: JENKINS, FRED - Us Environmental Protection Agency (EPA); LYNN, SCOTT - Us Environmental Protection Agency (EPA); BARR, DANA - Emory University; CAPEL, PAUL - Us Geological Survey (USGS); ENGEL, BERNARD - Purdue University; FLEISHMAN, ERICA - University Of California; INES, AMOR - Michigan State University; JETT, DAVID - National Institute Of Health (INSA); KLAINE, STEVEN - Clemson University; LOU, YUZHOU - California Department Of Pesticide Regulation; MARUYA, KEITH - Southern California Coastal Water Research Project; MCMANAMAN, JAMES - University Of Colorado; Potter, Thomas; RAY, CHITTARANJAN - University Of Nebraska; SCOTT, GEOFFREY - University Of South Carolina

Submitted to: Government Publication/Report
Publication Type: Government Publication
Publication Acceptance Date: 12/17/2015
Publication Date: 12/17/2015
Publication URL: http://www.epa.gov/sap/meeting-materials-september-15-17-2015-scientific-advisory-panel
Citation: Jenkins, F., Lynn, S., Barr, D., Capel, P., Engel, B., Fleishman, E., Ines, A., Jett, D., Klaine, S., Lou, Y., Maruya, K., Mcmanaman, J., Potter, T.L., Ray, C., Scott, G. 2015. SAP Minutes No.2015-03 for FIFRA meeting held 9/15-17/2015. A set of scientific issues being considered by the Environmental Protection Agency regarding development of a spatial aquatic model(SAM)for pesticide risk assessment. Government Publication/Report. http://www.epa.gov/sap/meeting-materials-september-15-17-2015-scientific-advisory-panel.

Interpretive Summary: USEPA convened a panel of fourteen experts to evaluate the strengths and weaknesses of the Spatial Aquatic Model (SAM) for Pesticide Risk Assessment that the agency currently has underdevelopment. SAM is expected to improve on the Agency’s existing aquatic exposure assessments by providing more systematic spatial-and temporal contexts for aquatic exposure assessments for both human health (drinking water) and aquatic organisms. Such context is needed to address common risk management questions regarding the likelihood of the exposure that may exceed toxicity thresholds of concern and, should such exposures occur, how often, how long, and where adverse impacts from pesticides in water overlap with populations at risk. This report summarizes the panel’s evaluation of the agency’s methodology and provides recommendations. The agency will use the report to guide further refinement of SAM and in development of new regulations and procedures to evaluate pesticide aquatic exposure risks.

Technical Abstract: On September 15-17th, 2014, the US Environmental Protection Agency convened a public meeting of the FIFRA Scientific Advisory Panel (SAP) to address scientific issues associated with the agency’s “Development of a Spatial Aquatic Model (SAM) for Pesticide Risk Assessment”. The goal of SAM is to improve on the Agency’s Office of Pesticide Programs (OPP) existing aquatic exposure assessments by providing more systematic spatial- and temporal contexts for aquatic exposure assessments for both human health (drinking water) and aquatic organisms. Much of SAM is based upon OPP’s traditional water quality models (i.e., Surface Water Concentration Calculator [SWCC] comprised of the Pesticide Root Zone Model version 5 [PRZM5] and Variable Volume Water Model [VVWM]). The novel features of SAM are its spatial approach to modeling the fate and transport of pesticides and optimization for speed and processing efficiency. The Panel agreed that SAM appears to be technically and conceptually sound, but as described further development is needed before SAM becomes a fully functional model. Limitations of SAM that were discussed were linked to both surface and subsurface hydrologic processes and how field and watershed scale conservation practices may impact fate and transport. Finally the Panel indicated that there may be different versions and different SAM conceptual models depending on desired model outcomes. It was recommended that the Agency consider creating a “SAM-MAX” version whose goal would be to predict maximum concentration to identify “hotspots”. Another version could be described as SAM-Distribution whose goal it would be to yield concentration predictions that best approximate measured values across a range of concentrations.