PUBLIC AGENDA

FIFRA SCIENTIFIC ADVISORY PANEL (SAP)

OPEN MEETING

October 25-26, 2011

FIFRA SAP WEB SITE http://www.epa.gov/scipoly/sap/

OPP Docket Telephone: (703) 305-5805

Docket Number: EPA-HQ- OPP-2011-0582

U.S. Environmental Protection Agency

Conference Center Lobby Level

One Potomac Yard (South Bldg.)

2777 S. Crystal Drive, Arlington, VA 22202

The Two-dimensional Exposure Rainfall-Runoff Assessment (TERRA) Watershed Model 

and its Use in the FIFRA Ecological Risk Assessment for Antimicrobial Uses of Copper

Please note that all times are approximate (see note at end of Agenda).

Tuesday, October 25, 2011

9:00 A.M. Opening of Meeting and Administrative Procedures

Dr. Fred Jenkins, Designated Federal Official, Office of Science Coordination and 

Policy (OSCP, EPA)

9:05 A.M. Introduction and Identification of Panel Members

Dr. Kenneth Portier, Chair, FIFRA Scientific Advisory Panel

9:15 A.M. Welcome and Opening Remarks

Dr. Steven Bradbury, Director, Office of Pesticide Programs (OPP, EPA) 

9:30 A.M. Introduction to the Office of Pesticide Program’s Environmental Exposure 

Modeling and Assessment

Dr. James Hetrick and Dr. Siroos Mostaghimi (OPP, EPA)

10:30 A.M. Break

10:40 A.M. Overview of the Two-dimensional Exposure Rainfall-Runoff Assessment 

(TERRA) Model

Dr. Mark Velleux, American Chemical Council (ACC)

12:10 P.M. Lunch
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1:10 P.M. Overview of the Two-dimensional Exposure Rainfall-Runoff Assessment 

(TERRA) Model (Cont’d)

1:30 P.M. TERRA Model as Applied to the Antimicrobial Copper Risk Assessment

Dr. Mark Velleux (ACC)

2:50 P.M. Break

3:05 P.M. EPA’s Review of TERRA Model as Applied to the Antimicrobial Copper 

Risk Assessment

Dr. Stephen Wente (OPP, EPA)

3:30 P.M. Public Comment

4:30 P.M. Presentation of Charge Questions

Donna Randall (OPP, EPA)

Discussion of Charge Questions

Charge Question 1

The three most prevalent antimicrobial uses of copper include antifoulant paints, roofing shingles

and wood preservatives. The Antimicrobials Division used a basic field scale modeling

approach, including maximum use rates, realistic heavy rainfall events, the assumption of high

leaching rates, and storm-water conveyance via impervious surfaces, to estimate potential high

end aquatic exposure from copper’s use as an antimicrobial pesticide in roofing shingles and

treated wood. The American Chemistry Council (ACC) has proposed the TERRA Model as an

alternative and more refined way to assess aquatic exposure due to the two major urban

antimicrobial uses of copper, in wood preservatives and in roofing shingles, on a watershed scale

level.

a) What does the Panel believe are the advantages and/or limitations of assessing

antimicrobial uses of copper from roofing shingles and wood preservatives with TERRA, a

spatially-explicit, watershed scale model? Are there other models that the Panel feels

should be considered for use by OPP in estimating exposure to copper from its use as an

antimicrobial pesticide, specifically in roofing shingles and wood preservative?

b) In the opinion of the Panel, what attributes of an urban watershed model are the most

critical and why does the Panel regard these attributes as critical? Does the TERRA model

possess these attributes?

5:30 P.M. ADJOURN
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Wednesday, October 26, 2011

9:00 A.M. Opening of Meeting and Administrative Procedures

Dr. Fred Jenkins, Designated Federal Official, Office of Science Coordination and 

Policy, EPA

9:05 A.M. Introduction and Identification of Panel Members

Dr. Kenneth Portier, Chair, FIFRA Scientific Advisory Panel

9:15 A.M. Discussion of Charge Questions

Charge Question 1 (Cont’d)

c) Please discuss whether TERRA has the modeling capabilities necessary for it to be applied

to other urban metal exposure assessments for antimicrobial pesticides as well as what

modifications, if any, would be needed to assess exposure to other metals used as

pesticides.

d) In the opinion of the Panel what further development and/or assessment is necessary to

prepare the TERRA model for use as an exposure assessment tool by the EPA?

11:00 A.M. Break

11:10 A.M. Discussion of Charge Questions (Cont’d)

Charge Question 2

EPA employs a tiered strategy to assess aquatic exposure. The first tier facilitates the rapid

screening of pesticide uses for potential risk issues, while the second tier refines exposure

estimates by utilizing a field scale model and site specific properties. This process is designed to

incorporate additional data (e.g., site specific properties) for each progressive tier. EPA has

historically employed field scale models to assess aquatic exposure in support of national

pesticide registrations. The TERRA model, unlike other models used by OPP, is a fully

distributed, spatially-explicit watershed model. It has model capabilities of distributing

differences in hydrology, meteorology, soil properties, and pesticide uses across a watershed.

These model capabilities require consideration in terms of the proper scale of the exposure

assessment.

a) Are the appropriate pathways (e.g. engineered water conveyance structures) for modeling

urban antimicrobial uses of copper within the Goodwin Creek scenario currently included

in the framework of the TERRA model? What, if any, additional pathways are necessary

to appropriately estimate exposure concentrations?
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12:00 P.M. Lunch

1:00 P.M. Discussion of Charge Questions (Cont’d)

Charge Question 2 (Cont’d)

b) What are the most important attributes to consider when selecting and designing an urban

watershed modeling scenario? In the opinion of the Panel, where does the Goodwin

Creek watershed fall within a distribution of the nation’s urban watersheds? Also, given

that the model does not account for storm drains, how does this compare to watersheds

nationwide?

1:45 P.M. Discussion of Charge Questions (Cont’d)

Charge Question 3

Watershed-scale models require calibration to account for complex watershed-dependent

hydrology and environmental fate processes. Model calibrations have been conducted by

altering saturated hydraulic conductivity, Mannings N, soil erodibility factors, land cover factors,

and chemical partitioning coefficients. In contrast, the OPP field-scale models such as

PRZM/EXAMS are not calibrated for site-specific hydrology, etc.

The TERRA model utilizes a simulated urban watershed that was calibrated to the hydrology and

sediment loads of Goodwin Creek. Because the Goodwin Creek watershed is a predominately

pastured/forested watershed, the EPA has concerns that the calibration processes may not

adequately represent urban hydrologic and chemical transport processes.

a) Please discuss the implications of watershed land use patterns on model calibration.

What types of impacts could these have on the estimated exposure concentrations of

copper?

3:15 P.M. Break

3:30 P.M. Discussion of Charge Questions (Cont’d)

Charge Question 3 (Cont’d)

b) Please indicate any unique calibration issues that should be considered when simulating

an urban, residential watershed.

5:00 P.M. ADJOURN

Please be advised that agenda times are approximate; when the discussion for one topic is completed, 

discussions for the next topic will begin. For further information, please contact the Designated Federal 

Official for this meeting, Dr. Fred Jenkins, via telephone: (202) 564-3327; fax: (202) 564-8382; or email: 

jenkins.fred@epa.gov.
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