UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D.C., 20460

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

PC Code: 123009 DP Barcodes: 

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MEMORANDUM

SUBJECT:

TO:

FROM:

THROUGH: Drinking Water Exposure Assessment for a Proposed Increase of the maximum use rate ofTopramezone Frequency Herbicide (EPA Reg. No. 7969-281) for non-cropland 1 uses, and Proposed New Use for Direct Applications to Aquatic Environments (Oasis Aquatic Herbicide, EPA File Symbol No. 7969-GGO)

Charles Smith, Acting Branch Chief, RAB 1**~arah** Levy, Chemist Health Effects Division (7509P)

Kathryn Montague, RM23 Grant Rowland, Risk Manager Reviewer Registration Division (7505P)

James K. Wolf, Ph.D., Environmental. Scientist 

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Rosanna Louie-Juzwiak, RAPL

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James A. Hetrick, Ph.D., Senior

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## ~1.3**·** Dana Spatz, Branch Chief, Environmental Risk**Bran~ ~**  Environmental Fate and Effects Division

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### \'ZA~ BASF has requested to increase application rates for several registered non-cropland terrestrial

uses of topramezone, and a proposed new use for direct applications in water bodies to manage aquatic vegetation. For the terrestrial uses, the registrant is seeking to amend the Frequency herbicide label (EPA Reg.# 7969-281) to increase the maximum use single application rate from 0.022 to 0.0875 pound of active ingredient (lb a.i.)/A) for sequential use, to increase the maximum single application rate to 0.35 lb a.i./A for bare ground, Christmas, conifer and

1 For preemergence and post-emergence weed control in Christmas tree, conifer, and hardwood plantations; field grown

ornamental production; and non-cropland areas such as railroad, utility, highway, and pipeline rights-of-way; highway guardrails, delineators, and sign posts; utility substations, petroleum tank farms

, pumping installations

, farmyards and around farm buildings; fence rows, storage areas, airports, and nonirrigation ditches.

1

### 2 hardwood plantations use, to increase the maximu m annual rate from 0.0875 lb a.i./A to 0.35 lb a.i./A. For the direct aquatic applications, BA SF proposed that a concentration of 50 parts per billion (ppb) be maintained for up to 60 days, wi th the exception of certa in treated water bodies that may be used for sources of potable water with functional potable water intakes must not exceed 45 ppb.

To date, no monitoring data are available for pare nt topramezone. Only parent topramezone is considered in this drinking water assessment becau se the degradation products are not considered in the tolerance expression for topramezone 2 

### . The models used in this assessment include PRZM/EXAMS models for surface water and Tier 1 PRZM-GW and SCI-GROW models for ground water. This assessment is based upon mode l input parameters from a previous drinking water assessment for topramezone (Hetrick and Corbin, 2008 3 

### ). An additional anaerobic aquatic metabolism 4 

### study (MRID 48600413) was submitted since the previous assessment, and was considered in this assessment. Given the proposed duration and concentration for the direct aquatic use, the highest concentration recommended for acute and chronic exposure considerations of drinking water is 45 ppb.

The highest topramezone EDWC is expected to result from the direct aquatic applications. Although the highest proposed conc entration in water is 50 ppb, the proposed use for water bodies with functional potable water intakes cannot exceed 45 ppb; therefore, this is the highest potential concentration recomme nded for drinking water. EDWCs concentrations resulting from terrestrial uses for both surface water and ground water generally occurred when the maximum application rate was applied in a single applic ation. The surface water 1 in 10-year acute (peak) EDWC value is 31.2 μg/L, the chronic (annual mean) value is 12.5 μg/L, and the long term (30- year) mean is 7.2 μg/L, based on the maximum application rate to bare ground. The highest ground water EDWCs were influenced by scenar io, years of application, and length of simulation. The highest daily EDWC in ground water was 15.4 μg/L. The highest simulation average and breakthrough average ground wa ter EDWCs were 11.3 μg/L and 11.4 μg/L, respectively. Whether one 0.35 lb a.i./A application or four 0.0875 lb a.i./A applications were simulated, little difference was noted in EDWCs for a specific scenario.

Use Characterization

Terrestrial Applications

The registrant (BASF) is seeking to amend the Frequency herbicide label (EPA Reg. # 7969- 281) to increase the maximum use single applicat ion rate from 1 to 4 fl oz/A (0.022 to 0.0875 lb active ingredient (a.i.)/A) for sequential use, to increase the permitted maximum single application rate to 16 fl oz/A (0.35 lb a.i./A for bare ground use and conifer/hardwood use,

2 Clock-Rust, M. et al. Memorandum: Topramezone/BAS 670H: Human Health Risk Assessment for New Active

Ingredient. DP Barcode 390075, May 11, 2005.

3 Hetrick, J.A. and M. Corbin. Topramezone Tier 1 and 2 Dr inking Water Assessment DP Ba rcode 356497, September 29, 2008. 4 OCSPP Guideline 835.4400 Anaerobic Aquatic Metabolism of 14 C-BAS 670 H.

### 3 which would also increase the maximum annual ra te from 4 to 16 fl oz/A (0.0875 lb a.i./A to 0.35 lb a.i./A).

Direct Aquatic Applications

BASF is also requesting the first use of topram ezone for direct aquatic applications, including direct foliar applications made to floating, em ergent, and shoreline weeds, which specifies a maximum annual application rate of 16 fluid oun ces (0.35 lb a.i.) per ac re. The proposed Oasis product label (EPA File Symbol 7969-GGO) also incl udes directions for in-w ater applications to control submersed or floating aquatic weeds. De pending on the level of weed establishment and desired control of target weeds, proposed labelin g directions include instructions to maintain a concentration ranging from 10 – 50 ppb throughout the treatment; depending on the target species to control, treatment durations can cont inue for at least 60 days. Depending on the type of weed control or to control more established or mature weeds, application exposures may take as long as four months at effective concentratio ns to achieve the desired control. Treated areas with functional potable water intakes must not exceed concentrations of 45 ppb, or treated potable water sources must be restricted (held) until levels decrease to 45 ppb or less. The proposed new rates are summarized in Table 2. Although reapplication intervals for the sequential use were not specified on the label, the registrant indicated via email (J. Birks, 12/21/12) that the minimum reapp lication interval should be 30 da ys; therefore, all modeling is based on this minimum retreatment interval.

### 4 Table 2: New Maximum Single and Seasonal (Annual) Proposed Application (App) Rates for Topramezone

Crop/Site Reference Label Page 1 App Type/ Method Single App Rate (lb a.i./A) Max. Number Of Apps Max. App Rate/ Season (Year) (lb a.i./A) Min. Retreat Interval (days) 2 Noncropland 3 Use Applications (Frequency Label, EPA Reg. No. 7969-281) 5 & 8 Aerial (A)/ Ground

(G) 0.35 30

Bare Ground: Pre-emergent app Early post-emergent app 8 A/G A/G 0.0875-0.35 0.0875-0.35 1 4 -4 5

1 4 -4 5 0.35 0.35 30

Christmas Tree Plantation 8 G 0.0875 4 5 0.35 30

Conifer & Hardwood Plantations: Site Prep. Applications 8 A/G 0.0875 4 2,5 0.35 30

Conifer & Hardwood Plantations: Herbaceous Weed Control 9 A/G 0.0875 4 2,5 0.35 30

Field-Grown Ornamentals 9 A/G 0.0875 4 5 0.35 30

Selective Weeding 10 A/G 0.0875 4 5 0.35 30 Direct Aquatic Applications (Oasis label, EPA File Symbol No. 7969-GGO) Foliar Application to shoreline or floating vegetation, dewatered canals, exposed sediment 4, 11 A/G 0.0875-0.35 0.0875-0.35 1-4 1-4 0.35 0.35 none

In-water applications to water bodies without functional drinking water intakes 4, 9, 11 G 10 – 50 ppb none 50 ppb none

In-water applications to water bodies that may be a potable water source 4, 9, 11 G 10 - 45 ppb none 50 ppb none

1 Draft label 007969-00281.20120509.NVA 2012-04-325-0095 (Submission #: 918739; E-Sub #: 2971).

2 Minimum reapplication interval is 30-day per email communication from J.H. Birk, BASF via K. Montague,

USEPA, 12/21/12 and yearly maximum is 16 fl oz./A/year (0.35 lb a.i./A/year).

3 Non-cropland areas include railroad, utility, highway, and pipeline rights-of- way; highway guardrails, delineators,

and sign posts; utility substations, petroleum tank fa rms, pumping installations, farmyards and around farm buildings; fence rows, storage areas, airports, and nonirrigation ditchbanks.

4 Only one application per season can be made at the maximum single application rate (16 fl. oz/acre = 0.35 lb a.i/A)

More than one sequential applications can be made at a lower single application rates (0.0875 lb a.i./A), the maximum number of applications is not specified (the max application rate cannot exceed 0.35 lb a.i./A/year); the minimum retreatment interval is 30 days.

5 The number of applications is not specified on the proposed label; the number was calculated by dividing the total

seasonal application rate proposed by the single maximum application rate proposed: (16 oz / 4 oz).

### 5 Exposure Characterization

Topramezone is persistent and m obile in terrestrial and aquatic environments. Major routes of dissipation are expected to be anaerobic micr obial-mediated degradation, leaching, surface water runoff, and spray drift. These data suggest a high potential for off-site movement of topramezone into surface and ground water. Degradation pr oducts of topramezone include M670H05, and M670H01, M670H 10, and M670H05 are also persiste nt and mobile. The degradation products are not considered in the drinki ng water assessment because they are not considered residues of concern by the Health Effects Division.

Environmental Fate and Transport Properties

Major routes of dissipation for topramezone ar e anaerobic microbial-mediated degradation, leaching, surface water runoff, and spray drift. Topram ezone is stable in ster ile solutions at pH 4, 5, 7, and 9 at temperatures ranging from 25 to 50°C. In natural water, topramezone has a photodegradation half-life of 72 days. The average aerobic soil meta bolism half-life of five soils was 197.0 days. Topramezone degrades to form M 670H05 (15% of applied parent at 365 days), and M670H01 (> 15% of applied), M670H 10 (> 16% of applied). The degradation product M670H05 is mobile and persistence (t 1/2 

### > 350 days). Structures of these degradation products are shown in Appendix A

. In aerobic aquatic environments , topramezone degraded with to tal system half-lives ranging from 19 to 277 days. Topramezone degraded in aerobic aquatic environments to form M670H01 (<10.3% of applied) degradation product. In anaerobic environments, topramezone degraded with total system half-lives ranging from 13 to 24 days. The major degradation products identified in anaerobic aquatic environments were M670H10 (41% to 48% of applied) minor degradation products and M670H01 ( ≤ 5.3% of applied). Based upon soil organic carbon coefficient, K oc 

### , topramezone would fall into the mobile to moderately mobility class adapted from the FAO by EFED (USEPA, 2006 5 

### ).

Terrestrial field dissipation studies were conduc ted in Indiana, South Dakota, California, and Ontario (Canada). Linear half-lives ranged from 29 to 182 days. There was no evidence of leaching in the terrestrial field dissipation studies.

Modeling

EFED water models 6 

### were used to estimate the drinking water exposure for use in the dietary risk assessment of topramezone. The following is a description of the models used, the selection of the model input parameters, and a characteri zation of the output from these simulations. Representative input and/or output are included in Appendix B

.

5 USEPA, 2006. Standardized Soil Mobility Classificati on Guidance. Memorandum: S. Bradbury, April 21, 2006.

6 PRZM and EXAMS are Tier II models used to estimate e nvironmental exposure concentrations in surface water. A

description of these models and the guidelines for selecting input parameters can be found at http://www.epa.gov/oppefed1/models/water/

### 6 Surface Water: The linked 7 

### Tier 2 PRZM 3.12.2 8 

### / EXAMS 2.98.04.06 9 

### ) models were used to assess potential for contamination of surface dr inking water sources from the proposed rate increases for terrestrial uses of topramezone. On ly the scenarios that resulted in the highest EDWCS from the previous non-cropland assessmen t (D356497) and the Calif ornia right-of-way scenarios were considered in this assessment. Fo r the proposed direct aqua tic applications, EFED assumed that this concentration could be availabl e in surface water sources that may feed into a drinking water intake, based on the proposed con centration of 45 to 50 ppb, and the duration of maintaining the target concentration ( i.e. , for up to 60 days at the higher concentrations, and for up to four months at lower concentrations).

Groundwater: For groundwater assessments, EFED is using both the SCI-GROW 10 

### (v2.3, Jul. 29, 2003) model and PRZM-GW (v1.01 11 

### ). The output of SCI-GROW represents the concentrations of topramezone re sidues that might be expected in shallow, unconfined aquifers under sandy soils. However, SCI-GROW does not c onsider multiple years of application and does not estimate a peak concentration. PRZM-GW can be used for Tier 1 and 2 assessments and additional refinements, provided data are available. Various exposure scenarios ( i.e. , as for surface water) can also be considered. PRZM-GW also allows for modeling multiple years of application. PRZM-GW does not consider dilution within the aquifer and or degradation processes other than aerobic soil metabolism in the upper meter of th e soil, unless data are available for other processes within the vadose zone or within the aquifer.

Model Input Parameters

The environmental fate and other input parame ters used for modeling are summarized in Tables 3, 4, and 5 . Dates of first application consid ered for surface water modeling with PRZM/EXAMS are listed in Table 6 . The date of first application ( Table 7 ) had little influence on the EDWCs (results not shown) estimated for ground water by PRZM-GW. The SCI-GROW model does not consider application date.

Topramezone can be applied by ground and aerial methods. Only aerial spray is considered in this assessment as this method re sults in higher EDWCs. Two rate options were assessed: 1) one application at the maximum rate of 0.35 lb a.i. /A and 2) four applications at the maximum sequential application rate (0.0875 lb a.i./A) with a 30 day reapp lication interval, for a yearly maximum of 0.35 lb a.i./A. For optimal control, t opramezone is applied to meet specific weed growth conditions; therefore, it can be applie d during the period of ac tive weed growth. To address the temporal (seasonal) va riability, a number of initial a pplication dates were considered ( Table 6 ).

7 http://www.epa.gov/oppefed1/models/water/index.htm#przmexamsshell

8 http://www.epa.gov/oppefed1/models/water/index.htm#przm

9 http://www.epa.gov/oppefed1/models/water/index.htm#exams 10 http://www.epa.gov/oppefed1/models/water/#scigrow

11 http://www.epa.gov/oppefed1/models/water/#przm_gw

### 7 Table 3. Topramezone Input Parameters for PRZM and EXAMS – Surface Water

Parameter Value/Selection criteria Source

Maximum Application Rate per Year, lb a.i./A 0.35 lb topramezone/A Proposed label of Topramezone (Frequency herbicide A )

Maximum Single Application Rates (lb a.i./A) 1 application @ 0.35 lb topramezone/A

4 applications @ 0.0875 lb topramezone/A 30-day minimum reapplication interval Proposed label of Topramezone

Application Method and Depth of Incorporation (cm) Ground and Aerial Spray No incorporation (model default 4-cm) Proposed label of Topramezone

Soil Partition Coefficient (K ads ; mL/g) mean K ads = 2.8 (n = 6; 1.40, 2.30, 1.97, 4.87, 2.59, 3.69) 45902425

Aerobic Soil Metabolism Half-life (days) [Linear t1⁄2] 241.28days (90 th percent upper bound of mean) (n=5; 181.3, 182.0, 301.5, 124.5, 195.9) 45902419; 45902421

Spray Drift Fraction (ground spray / aerial) Drinking Water: 0.064/0.16 USEPA, 2009 B

Application Efficiency (ground spray / aerial) 0.99 / 0.95 USEPA, 2009 B

Molecular Weight, Daltons 36 3.39 Physical and Chemical Property

Vapor Pressure 7.5 * 10 -13 torr Physical and Chemical Property

Henry’s Law Constant 2.39 * 10 -17 atm-m -3 mol -1 @ 20 ◦ C Estimated

Solubility in Water at 20 o C Topramezone is a weak acid (pK a 4.6) The solubility of topramezone is pH dependent 15,000 mgL -1 Physical and Chemical Property

Aerobic Aquatic Metabolism Half-life (days) 229.97 days (90 th percent upper bound of mean) (n=4; 18.6, 18.99,203, 277) 47496702

Anaerobic Aquatic Metabolism Halflife (days) 32.81 days 90 th percent upper bound of mean total system (n = 4; 13.4, 18.6 and 47.4, 23.4) 45902423 48600413

Hydrolysis Half-life @ pH 7 (days) Stable 45902416

Aquatic, Direct Photolysis Half-life @ pH 7 0 45902417

A EPA Reg No. 7969-281 (007969-00281.20120509.NVA 2012-04-325-0095) and Correspondence from J.Birks, BASF (Table 1)

B USEPA, 2009. Guidance for Selecting Input Parameters for M odeling the Environmental Fate and Transport of Pesticide.

http://www.epa.gov/oppefed1/models/wat er/input_paramete r_guidance.htm

### 8 Table 4.Input Parameters Used for SCI-GROW – Ground Water



### Parameter Value/Selection criteria Source

Maximum Application Rate per Season, lb a.i./A 0.35 lb topramezone/acre Proposed label of Topramezone 2.8SC

Aerobic Soil Metabolism Half-life (days) [Linear t1⁄2] 197.04 days mean (n=5; 181.3, 182.0, 301.5, 124.5, 195.9) 45902419 45902421

Sorption Koc 105.5 median Koc (38, 284, 53, 120, 91, 303) 45902425

Table 5.Input Parameters Used for PRZM-GW – Ground Water

Parameter Value/Selection criteria Source

Maximum Application Rate per Season, lb a.i./A 4 applications at 0.089 lb a.i./A 1 application at 0.35 lb a.i./A Proposed label of Topramezone 2.8SC

Aerobic Soil Metabolism Half-life (days) [Linear t1⁄2] 241.28days (90 th percent upper bound of mean) (n=5; 181.3, 182.0, 301.5, 124.5, 195.9) 45902419; 45902421

Sorption K ads mean K ads = 2.8 (n = 6; 1.40, 2.30, 1.97, 4.87, 2.59, 3.69) 45902425



### Surface Water Exposure Assessment

By design, all existing PRZM scenarios are intend ed to represent high-end exposure scenarios for the region represented whether it is a nationa l, regional, or local s cenario. Results of the surface water EDWCs are presented in Table 6 . Because this assessm ent is based upon the previous drinking water assessment for th e non-cropland use (DP Barcode 356497), the only scenarios (with aerial applications) considered in this assessment are those with the highest surface water EDWC from the previous drinki ng water assessment. The highest EDWCS were associated with a single maximum rate of 0.35 lb a. i./A compared to four sequential applications of 0.0875 lb a.i./A.

### 9 Table 6. PRZM/EXAMS Estimated Maximum Surface Water EDWCs ( μ g/L) A for the proposed new use rate of topramezone on non-cropland. Scenario 1 st Application Date (mn/day) Number apps/rate (lb a.i./A/app) 1-in 10-year peak Annual mean 30 year mean μg/L TN Nursery 03/05 1 app @ 035 14.715 3.542 1.794 04/05 1 app @ 0.35 14.655 3,442 1.689 05/05 1 app @ 0.35 8.2573 2.063 1.442 06/05 1 app @ 0.35 10.328 2.533 1.499 07/05 1 app @ 0.35 9.0274 2.252 1.612

03/05 4 app @ 0.0875 6.344 2.479 1.624 04/05 4 app @ 0.0875 6.493 2.129 1.566 05/05 4 app @ 0.0875 6.151 2.069 1.558 06/05 4 app @ 0.0875 6.759 2.257 1.749 07/05 4 app @ 0.0875 7.996 2.453 1.864 NJ Nursery 03/05 1 app @ 0.35 14.298 4.577 2.726 04/05 1 app @ 0.35 10.879 3.430 2.154 05/05 1 app @ 0.35 11.494 3.493 2.201 06/05 1 app @ 0.35 8.318 2.625 2.122 07/05 1 app @ 0.35 10.728 3.493 2.534 08/05 1 app @ 0.35 4.888 3.052

03/05 4 app @ 0.0875 7.241 3.176 2.318 04/05 4 app @ 0.0875 6.429 2.842 2.244 05/05 4 app @ 0.0875 8.723 3.041 2.593 06/05 4 app @ 0.0875 7.737 3.388 2.672 07/05 4 app @ 0.0875 8.179 3.667 2.850 08/05 4 app @ 0.0875 8.515 4.436 2.894 MI Nursery 03/05 1 app @ 0.35 7.325 2.685 1.930 04/05 1 app @ 0.35 11.298 3.760 2.613 05/05 1 app @ 0.35 11.455 4.026 2.567 06/05 1 app @ 0.35 8.543 3.158 2.543 07/05 1 app @ 0.35 7.506 2.616 2.361 08/05 1 app @ 0.35 11.312 3.276 2.504

03/05 4 app @ 0.0875 6.529 2.9649 2.354 04/05 4 app @ 0.0875 6.310 3.0694 2.498 05/05 4 app @ 0.0875 6.045 2.8866 2.515 06/05 4 app @ 0.0875 8.975 3,653 2.706 07/05 4 app @ 0.0875 8.143 3.5832 2.612 08/05 4 app @ 0.0875 PA turf 03/05 1 app @ 0.35 4.470 2.558 2.067 04/05 1 app @ 0.35 4.264 2.484 1.975 05/05 1 app @ 0.35 5.394 2.918 2.280 06/05 1 app @ 0.35 5.976 2.981 2.457 07/05 1 app @ 0.35 6.109 3.511 2.462 08/05 1 app @ 0.35 8.380 4.723 3.006 09/05 1 app @ 0.35 11.615 5.755 3.367

### 10 Scenario 1 st Application Date (mn/day) Number apps/rate (lb a.i./A/app) 1-in 10-year peak Annual mean 30 year mean μg/L 03/05 4 app @ 0.0875 3.081 1.934 1.648 04/05 4 app @ 0.0875 3.354 2.081 1.763 05/05 4 app @ 0.0875 4.305 2.645 2.012 06/05 4 app @ 0.0875 4.997 2.955 2.201 07/05 4 app @ 0.0875 5.321 2.974 2.287

Bare Ground CA R-O-W B (Aerial) 1/15 1 app @ 0.35 31.17 12.53 7.02 (Ground) 1/15 1 app @ 0.35 31.05 12.46 6.73 (Aerial) 2/15 1 app @ 0.35 23.81 9.22 4.78 (Ground) 2/15 1 app @ 0.35 23.27 9.02 4.41 (Aerial) 3/15 1 app @ 0.35 16.68 6.79 3.94 (Ground) 3/15 1 app @ 0.35 15.98 6.49 3.53 (Aerial) 4/15 1 app @ 0.35 12.40 4.88 3.01 (Aerial) 5/15 1 app @ 0.35 12.57 4.53 3.38 (Aerial) 6/15 1 app @ 0.35 14.18 4.93 3.62 (Aerial) 7/15 1 app @ 0.35 15.61 5.32 3.91 (Aerial) 8/15 1 app @ 0.35 17.27 5.74 4.24 (Aerial) 9/15 1 app @ 0.35 19.33 6.25 4.69 (Aerial) 10/15 1 app @ 0.35 16.50 7.24 5.08 (Aerial) 11/15 1 app @ 0.35 23.92 7.77 5.89 (Aerial) 12/15 1 app @ 0.35 28.91 11.54 6.93

A – No PCA applied.

B- California Right-of-Way Scenario



### Ground Water Exposure Assessment

The previous drinking water assessment only pr esented SCI-GROW estimates of topramezone concentrations in ground water. PRZM-GW is now used in addition to SCI-GROW to estimate pesticide concentrations in ground water 12 

### . Both PRZM-GW ( Table 8 ) and SCI-GROW ( Table 9 ) are presented for the proposed new applicatio n rates. Simulations were run for 30 and 100 years for the maximum single application rate of 0.35 lb a.i./A a nd for four sequential applications of 0.0875 lb a.i./A follo wing the guidance for using PRZM-GW 13 

### . The highest daily ground water EDWC value was 15.4 μg/L for a vulne rable scenario in Florida. The highest simulation average and breakthrough averag e EDWCs were 11.3 μg/L and 11.4 μg/L, respectively. Whether one 0.35 lb a.i./A application or four 0.0875 lb a.i./A applications were simulated, little difference was noted in EDWCs for a specific scenario.

12 Brady, D. Approval of PRZM-GW for Use in Drinking Water Exposure Assessments. December 11, 2012.

13 USEPA, 2012. Guidance for Using PRZM-GW in Drinking Water Exposure Assessments; http://www.epa.gov/oppefed1/models/w ater/przm_gw/wqtt_przm_gw_guidance.htm

### 11 Table 7. PRZM-GW Estimated Maximum Ground Water EDWCs ( μ g/L) for the proposed new use rate of topramezone on non-cropland.

Scenario: Date of First Application (mn/day) Years of Simulation Highest Daily Value Simulation Average Post Breakthrough Average Average Simulation Breakthrough Time (days) Max. Single App Rate # apps: 1@ 0.35 lb a.i./A μg/L

Delmarva: 5/05 30 100 0.77 8.59 0.10 4.46 0.10 4.48 238 243

Fl Citrus: 2/05- 30 100 11.0 15.4 3.49 11.3 3.62 11.4 260 260

FL Potato: 1/05 30 100 5.04 5.99 1.99 4.57 2.10 4.64 302 301

GA Coastal Plain: 5/05 30 100 0.138 5.33 0.02 2.68 0.02 2.78 1036 1033

NC East Coastal Plain: 5/05 30 100 0.136 5.15 0.016 2.17 0.018 2.23 1076 1086

WI Central Sands: 7/05 30 100 <0.001 5.39 <0.001 0.826 <0.001 0.846 612 614 Max. Sequential App Rate # apps: 4 @ 0.0.875/30-day μg/L

Delmarva: 5/05 30 100 0.774 8.79 0.10 4.55 0.10 4.58 238 243

Fl Citrus: 2/05- 30 100 10.8 15.1 3.39 11.0 3.51 11.1 260 260

FL Potato: 1/05 30 100 4.85 5.77 1.91 4.39 2.01 4.46 302 301

GA Coastal Plain: 5/05 30 100 0.14 5.41 0.017 2.72 0.019 2.82 1035 1033

NC East Coastal Plain: 5/05 30 100 0.14 5.38 0.017 2.25 0.018 2.32 1076 1086

WI Central Sands: 7/05 30 100 <0.001 5.40 <0.001 0.82 <0.001 0.84 612 614



### The modeling results associated with maximu m allowable rate per year from SCI-GROW is presented in Table 8.

Table 8. SCI-GROW estimated EDWCs ( μ g/L) in the ground water fo r maximum application rate.

Model for Groundwater EEC (μg/L)

SCI-GROW 1.07

### 12 

### APPENDIX A

Structure of Topramezone and Degradation Products

Topramezone M670H05 M670H01

M670H 1

M670H10 S O

N
N OH O S N O

N
N

O O OH O

S N O OH

O O O

S N

N
N

O O OH O

### 13 

### APPENDIX B Representative Model Output Files

Surface Water PE5 PRZM-EXAMS OUTPUT

stored as CAROW1a.out Chemical: topramezone PRZM environment: CArightofwayRLF_V2.t xt modified Wedday, 26 March 2008 at 09:38:28 EXAMS environment: ir298.exv modified Tueday, 26 August 2008 at 05:14:08 Metfile: w23234.dvf modified Tued ay, 26 August 2008 at 05:15:38 Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 13.8 13.61 13.23 12.22 11.38 5.707 1962 20.73 20.55 19.62 17.65 16.15 8.516 1963 31.19 30.83 30.12 27.26 25.2 12.68 1964 25.97 25.65 24.3 21.47 19.65 9.838 1965 8.394 8.281 8.013 7.322 7.004 3.983 1966 15.41 15.2 14.44 12.97 11.92 5.998 1967 48.18 47.55 46.23 41.51 38.02 18.76 1968 24.77 24.43 23.2 21.12 19.54 10.02 1969 31.05 30.79 29.7 26.77 24.56 12.19 1970 21.89 21.62 20.92 18.88 17.31 8.75 1971 9.97 9.834 9.294 8.657 7.969 4.387 1972 6.411 6.324 5.975 5.463 5.056 2.802 1973 32.13 31.69 30.12 27.6 25.38 12.57 1974 9.852 9.728 9.244 8.388 8.062 4.636 1975 18.45 18.24 17.7 16.04 14.73 7.379 1976 10.56 10.41 9.832 8.745 8.01 4.295 1977 7.099 7.002 6.618 5.827 5.305 3.091 1978 17.9 17.65 16.88 15.48 14.56 7.451 1979 17.93 17.73 16.97 15.44 14.15 7.517 1980 16.11 15.89 15.28 13.67 12.51 6.536 1981 23.55 23.31 22.1 19.58 17.93 8.968 1982 12.98 12.81 12.23 11.08 10.17 5.498 1983 25.74 25.53 24.37 21.85 20 9.889 1984 5.274 5.216 4.937 4.565 4.428 2.515 1985 13.17 12.99 12.25 11.64 10.86 5.552 1986 12.17 12.05 11.48 10.39 9.668 5.075 1987 10.89 10.75 10.15 9.054 8.26 4.258 1988 13.33 13.14 12.43 10.95 9.975 5.54 1989 5.802 5.723 5.573 5.317 5.046 2.854 1990 8.277 8.198 7.767 6.851 6.234 3.38

### 14 Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 48.18 47.55 46.23 41.51 38.02 18.76 0.0645161290322581 32.13 31.69 30.12 27.6 25.38 12.68 0.0967741935483871 31.19 30.83 30.12 27.26 25.2 12.57 0.129032258064516 31.05 30.79 29.7 26.77 24.56 12.19 0.161290322580645 25.97 25.65 24.37 21.85 20 10.02 0.193548387096774 25.74 25.53 24.3 21.47 19.65 9.889 0.225806451612903 24.77 24.43 23.2 21.12 19.54 9.838 0.258064516129032 23.55 23.31 22.1 19.58 17.93 8.968 0.290322580645161 21.89 21.62 20.92 18.88 17.31 8.75 0.32258064516129 20.73 20.55 19.62 17.65 16.15 8.516 0.354838709677419 18.45 18.24 17.7 16.04 14.73 7.517 0.387096774193548 17.93 17.73 16.97 15.48 14.56 7.451 0.419354838709677 17.9 17.65 16.88 15.44 14.15 7.379 0.451612903225806 16.11 15.89 15.28 13.67 12.51 6.536 0.483870967741936 15.41 15.2 14.44 12.97 11.92 5.998 0.516129032258065 13.8 13.61 13.23 12.22 11.38 5.707 0.548387096774194 13.33 13.14 12.43 11.64 10.86 5.552 0.580645161290323 13.17 12.99 12.25 11.08 10.17 5.54 0.612903225806452 12.98 12.81 12.23 10.95 9.975 5.498 0.645161290322581 12.17 12.05 11.48 10.39 9.668 5.075 0.67741935483871 10.89 10.75 10.15 9.054 8.26 4.636 0.709677419354839 10.56 10.41 9.832 8.745 8.062 4.387 0.741935483870968 9.97 9.834 9.294 8.657 8.01 4.295 0.774193548387097 9.852 9.728 9.244 8.388 7.969 4.258 0.806451612903226 8.394 8.281 8.013 7.322 7.004 3.983 0.838709677419355 8.277 8.198 7.767 6.851 6.234 3.38 0.870967741935484 7.099 7.002 6.618 5.827 5.305 3.091 0.903225806451613 6.411 6.324 5.975 5.463 5.056 2.854 0.935483870967742 5.802 5.723 5.573 5.317 5.046 2.802 0.967741935483871 5.274 5.216 4.937 4.565 4.428 2.515

0.1 31.176 30.826 30.078 27.211 25.136 12.532 Average of yearly averages: 7.02116666666666

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run: Output File: CAROW1a Metfile: w23234.dvf PRZM scenario: CArightofwayRLF_V2.txt EXAMS environment file: ir298.exv Chemical Name: topramezone Description Variable Name Value Units Comments

### 15 Molecular weight mwt 363.39 g/mol Henry's Law Const. henry 2.39E-17 atm-m^3/mol Vapor Pressure vapr 7.5E-13 torr Solubility sol 15000 mg/L Kd Kd 2.8 mg/L Koc Koc mg/L Photolysis half-life kdp 0 days Half-life Aerobic Aquatic Metabolism kbacw 229.97 days Halfife Anaerobic Aquatic Metabolis m kbacs 32.81 days Halfife Aerobic Soil Metabolism asm 241.28 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI cm Application Rate: TAPP 0.392 kg/ha Application Efficiency: APPEFF 0.95 fraction Spray Drift DRFT 0.16 fraction of application rate applied to pond Application Date Date 15-1 dd/ mm or dd/mmm or dd-mm or dd-mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Reservoir Flag for runoff calc. RUNOFF total none, m onthly or total(aver age of entire run)

Surface Water PRZM INPUT FILE

"CarightofwayRLF_V2.txt, 3/25/2008" "Central/Coastal California; MLRA 14,15; Metfil e: W23234.dvf" *** Record 3: 0.77 0 0 17.5 1 1 *** Record 6 -- ERFLAG 4 *** Record 7: 0.28 1.1 1 172.8 2 5 600 *** Record 8 1 *** Record 9 1 0.1 15 10 3 92 92 92 0 15 *** Record 9a-e 1 24 0109 1609 0110 1610 0111 1611 0112 1612 0101 1601 0102 1602 0103 1603 0104 1604 .004 .004 .004 .004 .004 .004 .004 .004 .004 .004 .004 .004 .004 .004 .004 .004 .110 .110 .110 .110 .110 .110 .110 .110 .110 .110 .110 .110 .110 .110 .110 .110

### 16 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 0105 1605 0106 1606 0107 1607 0108 1608 .004 .004 .004 .004 .004 .004 .004 .004 .110 .110 .110 .110 .110 .110 .110 .110 92 92 92 92 92 92 92 92 *** Record 10 -- NCPDS, the number of cropping periods 30 *** Record 11 010961 011161 021161 1 010962 011162 021162 1 010963 011163 021163 1 010964 011164 021164 1 010965 011165 021165 1 010966 011166 021166 1 010967 011167 021167 1 010968 011168 021168 1 010969 011169 021169 1 010970 011170 021170 1 010971 011171 021171 1 010972 011172 021172 1 010973 011173 021173 1 010974 011174 021174 1 010975 011175 021175 1 010976 011176 021176 1 010977 011177 021177 1 010978 011178 021178 1 010979 011179 021179 1 010980 011180 021180 1 010981 011181 021181 1 010982 011182 021182 1 010983 011183 021183 1 010984 011184 021184 1 010985 011185 021185 1 010986 011186 021186 1 010987 011187 021187 1 010988 011188 021188 1 010989 011189 021189 1 010990 011190 021190 1 *** Record 12 -- PTITLE topramazone - 1 applications @ 0.392 kg/ha *** Record 13 30 1 0 0 *** Record 15 -- PSTNAM topramazone *** Record 16 150161 0 2 0.0 0.392 .95 .16

### 17 150162 0 2 0.0 0.392 .95 .16 150163 0 2 0.0 0.392 .95 .16 150164 0 2 0.0 0.392 .95 .16 150165 0 2 0.0 0.392 .95 .16 150166 0 2 0.0 0.392 .95 .16 150167 0 2 0.0 0.392 .95 .16 150168 0 2 0.0 0.392 .95 .16 150169 0 2 0.0 0.392 .95 .16 150170 0 2 0.0 0.392 .95 .16 150171 0 2 0.0 0.392 .95 .16 150172 0 2 0.0 0.392 .95 .16 150173 0 2 0.0 0.392 .95 .16 150174 0 2 0.0 0.392 .95 .16 150175 0 2 0.0 0.392 .95 .16 150176 0 2 0.0 0.392 .95 .16 150177 0 2 0.0 0.392 .95 .16 150178 0 2 0.0 0.392 .95 .16 150179 0 2 0.0 0.392 .95 .16 150180 0 2 0.0 0.392 .95 .16 150181 0 2 0.0 0.392 .95 .16 150182 0 2 0.0 0.392 .95 .16 150183 0 2 0.0 0.392 .95 .16 150184 0 2 0.0 0.392 .95 .16 150185 0 2 0.0 0.392 .95 .16 150186 0 2 0.0 0.392 .95 .16 150187 0 2 0.0 0.392 .95 .16 150188 0 2 0.0 0.392 .95 .16 150189 0 2 0.0 0.392 .95 .16 150190 0 2 0.0 0.392 .95 .16 *** Record 17 0 1 0 *** Record 18 0 0 0.5 *** Record 19 -- STITLE "Gaviota Sandy Loam, 5-15% slopes, hydrologic group D" *** Record 20 51 0 0 0 0 0 0 0 0 0 *** Record 26 0 0 0 *** Record 33 3 1 10 1.55 0.173 0 0 0 0.0028730.002873 0 0.1 0.173 0.087 0.44 2.8 2 23 1.55 0.173 0 0 0 0.0028730.002873 0

### 18 1 0.173 0.087 0.44 2.8 3 18 1.55 0.136 0 0 0 0.0028730.002873 0 3 0.136 0.066 0.15 2.8 ***Record 40 0 YEAR 10 YEAR 10 YEAR 10 1 1 1 ----- 7 YEAR PRCP TCUM 0 0 RUNF TCUM 0 0 INFL TCUM 1 1 ESLS TCUM 0 0 1.0E3 RFLX TCUM 0 0 1.0E5 EFLX TCUM 0 0 1.0E5 RZFX TCUM 0 0 1.0E5

PRZM-GW INPUT FILE.

1/29/2013 10:08:30 AM; Topramezone ; Florida Citrus - FL Central Ridge, Polk County - (Tampa) Met File (12842.dvf ) - Astatula sand, hrgb A User Interface Version: PRZM-GW (Version 1.01) ***Record 3 0.78 0 0 33 1 1 ***Record 6 0 ***Record 8 1 ***Record 9 1 0.25 200 60 1 10 10 10 0 100 ***Record 10 99 ***Record 11 0101 1 0102 1 3112 1 1 0101 2 0102 2 3112 2 1 0101 3 0102 3 3112 3 1 0101 4 0102 4 3112 4 1 0101 5 0102 5 3112 5 1 0101 6 0102 6 3112 6 1 0101 7 0102 7 3112 7 1 0101 8 0102 8 3112 8 1 0101 9 0102 9 3112 9 1 010110 010210 311210 1 010111 010211 311211 1

### 19 010112 010212 311212 1 010113 010213 311213 1 010114 010214 311214 1 010115 010215 311215 1 010116 010216 311216 1 010117 010217 311217 1 010118 010218 311218 1 010119 010219 311219 1 010120 010220 311220 1 010121 010221 311221 1 010122 010222 311222 1 010123 010223 311223 1 010124 010224 311224 1 010125 010225 311225 1 010126 010226 311226 1 010127 010227 311227 1 010128 010228 311228 1 010129 010229 311229 1 010130 010230 311230 1 010131 010231 311231 1 010132 010232 311232 1 010133 010233 311233 1 010134 010234 311234 1 010135 010235 311235 1 010136 010236 311236 1 010137 010237 311237 1 010138 010238 311238 1 010139 010239 311239 1 010140 010240 311240 1 010141 010241 311241 1 010142 010242 311242 1 010143 010243 311243 1 010144 010244 311244 1 010145 010245 311245 1 010146 010246 311246 1 010147 010247 311247 1 010148 010248 311248 1 010149 010249 311249 1 010150 010250 311250 1 010151 010251 311251 1 010152 010252 311252 1 010153 010253 311253 1 010154 010254 311254 1 010155 010255 311255 1 010156 010256 311256 1 010157 010257 311257 1

### 20 010158 010258 311258 1 010159 010259 311259 1 010160 010260 311260 1 010161 010261 311261 1 010162 010262 311262 1 010163 010263 311263 1 010164 010264 311264 1 010165 010265 311265 1 010166 010266 311266 1 010167 010267 311267 1 010168 010268 311268 1 010169 010269 311269 1 010170 010270 311270 1 010171 010271 311271 1 010172 010272 311272 1 010173 010273 311273 1 010174 010274 311274 1 010175 010275 311275 1 010176 010276 311276 1 010177 010277 311277 1 010178 010278 311278 1 010179 010279 311279 1 010180 010280 311280 1 010181 010281 311281 1 010182 010282 311282 1 010183 010283 311283 1 010184 010284 311284 1 010185 010285 311285 1 010186 010286 311286 1 010187 010287 311287 1 010188 010288 311288 1 010189 010289 311289 1 010190 010290 311290 1 010191 010291 311291 1 010192 010292 311292 1 010193 010293 311293 1 010194 010294 311294 1 010195 010295 311295 1 010196 010296 311296 1 010197 010297 311297 1 010198 010298 311298 1 010199 010299 311299 1 ***Record 12 Place Holder ***Record 13 99 1 0 0

### 21 ***Record 15 Place Holder ***Record 16 5 2 1 0 1 4 0.392 1 0 5 2 2 0 1 4 0.392 1 0 5 2 3 0 1 4 0.392 1 0 5 2 4 0 1 4 0.392 1 0 5 2 5 0 1 4 0.392 1 0 5 2 6 0 1 4 0.392 1 0 5 2 7 0 1 4 0.392 1 0 5 2 8 0 1 4 0.392 1 0 5 2 9 0 1 4 0.392 1 0 5 210 0 1 4 0.392 1 0 5 211 0 1 4 0.392 1 0 5 212 0 1 4 0.392 1 0 5 213 0 1 4 0.392 1 0 5 214 0 1 4 0.392 1 0 5 215 0 1 4 0.392 1 0 5 216 0 1 4 0.392 1 0 5 217 0 1 4 0.392 1 0 5 218 0 1 4 0.392 1 0 5 219 0 1 4 0.392 1 0 5 220 0 1 4 0.392 1 0 5 221 0 1 4 0.392 1 0 5 222 0 1 4 0.392 1 0 5 223 0 1 4 0.392 1 0 5 224 0 1 4 0.392 1 0 5 225 0 1 4 0.392 1 0 5 226 0 1 4 0.392 1 0 5 227 0 1 4 0.392 1 0 5 228 0 1 4 0.392 1 0 5 229 0 1 4 0.392 1 0 5 230 0 1 4 0.392 1 0 5 231 0 1 4 0.392 1 0 5 232 0 1 4 0.392 1 0 5 233 0 1 4 0.392 1 0 5 234 0 1 4 0.392 1 0 5 235 0 1 4 0.392 1 0 5 236 0 1 4 0.392 1 0 5 237 0 1 4 0.392 1 0 5 238 0 1 4 0.392 1 0 5 239 0 1 4 0.392 1 0 5 240 0 1 4 0.392 1 0 5 241 0 1 4 0.392 1 0 5 242 0 1 4 0.392 1 0 5 243 0 1 4 0.392 1 0

### 22 5 244 0 1 4 0.392 1 0 5 245 0 1 4 0.392 1 0 5 246 0 1 4 0.392 1 0 5 247 0 1 4 0.392 1 0 5 248 0 1 4 0.392 1 0 5 249 0 1 4 0.392 1 0 5 250 0 1 4 0.392 1 0 5 251 0 1 4 0.392 1 0 5 252 0 1 4 0.392 1 0 5 253 0 1 4 0.392 1 0 5 254 0 1 4 0.392 1 0 5 255 0 1 4 0.392 1 0 5 256 0 1 4 0.392 1 0 5 257 0 1 4 0.392 1 0 5 258 0 1 4 0.392 1 0 5 259 0 1 4 0.392 1 0 5 260 0 1 4 0.392 1 0 5 261 0 1 4 0.392 1 0 5 262 0 1 4 0.392 1 0 5 263 0 1 4 0.392 1 0 5 264 0 1 4 0.392 1 0 5 265 0 1 4 0.392 1 0 5 266 0 1 4 0.392 1 0 5 267 0 1 4 0.392 1 0 5 268 0 1 4 0.392 1 0 5 269 0 1 4 0.392 1 0 5 270 0 1 4 0.392 1 0 5 271 0 1 4 0.392 1 0 5 272 0 1 4 0.392 1 0 5 273 0 1 4 0.392 1 0 5 274 0 1 4 0.392 1 0 5 275 0 1 4 0.392 1 0 5 276 0 1 4 0.392 1 0 5 277 0 1 4 0.392 1 0 5 278 0 1 4 0.392 1 0 5 279 0 1 4 0.392 1 0 5 280 0 1 4 0.392 1 0 5 281 0 1 4 0.392 1 0 5 282 0 1 4 0.392 1 0 5 283 0 1 4 0.392 1 0 5 284 0 1 4 0.392 1 0 5 285 0 1 4 0.392 1 0 5 286 0 1 4 0.392 1 0 5 287 0 1 4 0.392 1 0 5 288 0 1 4 0.392 1 0 5 289 0 1 4 0.392 1 0

### 23 5 290 0 1 4 0.392 1 0 5 291 0 1 4 0.392 1 0 5 292 0 1 4 0.392 1 0 5 293 0 1 4 0.392 1 0 5 294 0 1 4 0.392 1 0 5 295 0 1 4 0.392 1 0 5 296 0 1 4 0.392 1 0 5 297 0 1 4 0.392 1 0 5 298 0 1 4 0.392 1 0 5 299 0 1 4 0.392 1 0 ***Record 17 0 3 0 ***Record 19 Place Holder ***Record 20 400 0 0 0 0 0 2 1 1 0 ***Record 26 0 0 0 ***Record 27 4 0.1 0.90 7.0 ***Record 31 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.97 10.0 ***Record 32 21 21 21 21 21 21 21 21 21 21 21 21 ***Record 32A 2.00 25.0 ***Record 33 8 *** Record 34,36,37 Horizon 1 1 10 1.35 0.11 0 0 0 0.00287 0.00287 0 1 0.11 0.014 0.144 2.8 21 96 2.4 0 0 *** Record 34,36,37 Horizon 2 2 10 1.58 0.1 0 0 0 0.00271 0.00271 0 5 0.1 0.016 0.144 2.8 21 95 2.8 0 0 *** Record 34,36,37 Horizon 3 3 20 1.58 0.1 0 0 0 0.00223 0.00223 0 20 0.1 0.016 1.44 2.8 21 95 2.8 0 0 *** Record 34,36,37 Horizon 4 4 20 1.45 0.2 0 0 0 0.0016 0.0016 0

### 24 20 0.2 0.015 0.144 2.8 21 95 2.8 0 0 *** Record 34,36,37 Horizon 5 5 20 1.5 0.1 0 0 0 0.0009570.000957 0 20 0.1 0.015 0.144 2.8 21 95 2.8 0 0 *** Record 34,36,37 Horizon 6 6 20 1.5 0.24 0 0 0 0.0003190.000319 0 20 0.24 0.015 0.144 2.8 21 95 2.8 0 0 *** Record 34,36,37 Horizon 7 7 200 1.59 0.10 0 0 0 0 0 0 50 0.10 0.014 0.144 2.8 21 96 2.8 0 0 *** Record 34,36,37 Horizon 8 8 100 1.58 0.3997 0 0 0 0 0 0 50 0.3997 0.001 0.144 2.8 21 87 11 0 0 *** Record 40 0 *** Record 42 YEAR 10 YEAR 10 YEAR 10 0 *** Record 45 3 YEAR *** Record 46 DCON1 TAVE 21 22 1.0E3 INFL TCUM 21 21 0.0261 IRRG TSER

### 25 PRZM-GW OUTPUT

Highest Daily Value (ppb): 15.4 Simulation Average Value (ppb): 11.3 Average Breakthrough Time (days): 260.3456 Throughputs: 138.9 Post-Breakthrough Average (ppb): 11.4

Topramezone Simulation 1 application @ 0.35 lb ai/acre per year, 100 year simulation