### UNITED STA **TES ENVIRONMENTA L PROTECTION A** **GENCY** WASHINGTON, DC 20460 OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

### PC Code : 128974 **DP Barcode** : 405093 **Date:** September 14, 2012 **MEMORANDUM Subject:**  Quinclorac : Registration Review Drinking Water Assessment **To:** Elissa Reaves, Branch Chief, RAB4

Health Effects Division (7509P) Wilhelmena Livingston, Chemical Review Manager Risk Management and Implementation Branch IV Pesticide Re - evaluation Division (7508P) **From:** Michael B. Lowit, Ph.D. , Ecologist

Nancy Andrews, Ph.D. , Branch Chief Environmental Risk Branch 1 Environmental Fate and Effects Division (7507P) Office of Pesticide Programs This memorandum summarizes the drinking water assessment (DWA) for the registration review of quinclorac . This assessment considers registered uses identified in the 2007 registration review problem formulation (D P 344485), subsequently assessed new uses, and proposed new uses on rhubarb and low growing berries except strawberry (subgroup 13 - 07H) .

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**1. EXECUTIVE SUMMARY**  Quinclorac (3,7 - dichloro - 8 - quinolinecarboxyl ic acid) is a s ystemic herbicide used to control broadleaf and grass weeds. A Tier II screening - level drinking water assessment (DWA) was conducted for registered uses and proposed new uses . Quinclorac uses include turf grasses, rice, cranberry, aquatic weeds, sorghum, wheat, rangeland/pasture, rights - of - way/fencerow/hedgerow, grass grown for seed , fallow land , and grass forage/fodder/hay . Proposed new uses are rhubarb and low growing berries except strawberry (subgroup 13 - 07H) (see recent DWA; DP 397720) . The low growing berries group includes cranberry, which was assessed previously at the same application rate. A range of application rates and application intervals are permitted for most uses. The assessment is based on maximum application rates and minimum application intervals for each use. Ground and aerial applications are allowed for several uses. Although both ground and aerial applications were modeled, estimated drinking water concentrations (EDWCs ) for aerial applications are presented when ground and aerial application are permitted by a label (EDWCs from aerial applications are higher than those from ground applications ). Noted l abel uncertainties are listed in **Section 3.2.3**  . As expected, in some cases the EDWCs from the current analys is differ from those reported in previous anal ys es. There are several reasons for the difference, including but not limited to the following. As identified in the registration review problem formulation some previous assessments did not reflect the highest application rates and minimum intervals for some uses. S ome uses were previously assessed using the Tier 1 surface -water model GENEEC while the current assessment is performed according to current EFED guidance 1 

### and up - to - date models 2 

### including the Tier II surface water model (PRZM/EXAMS) for applicable uses of quinclorac . Screening - level Tier I modeling was used to estimate surface water concentrations for use on cranberry (provisional cranberry

model) and rice (Tier I rice model) because the current Tier II model is not parameterized for those uses. The Tier I SCI - GROW model was used to estimate groundwater concentrations. As in past assessments, this assessment does not consider quinclorac major degradation products BH 514 - 1 and BH 5 14 2 - OH. Although these degradates were detected in the laboratory studies, they seem to be intermediate degradates (DP 344485 ), and were not found in field dissipation studies at any

significant levels. Furthermore, since quinclorac is persistent and mobile, it is expected to be the predominant residue in ground and surface waters. S urface water EDWCs (acute = **511 μg/L**  and chronic = **511 μg/L**  ) resulting from use on rice supersede previousl y recommended EDWCs. The recommended groundwater EDWC has not changed (**29 μg/L** for acute and chronic exposure ) . Please contact us if refinements are needed. In order to avoid repetition of material previously provided, please refer to the Registration Review Problem Formulation (DP 344485) for detailed information about quinclorac.

1 Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides, Version 2.1, October 22, 2009 2 http://www.epa.gov/oppefed1/models/water

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**2. PROBLEM FORMULATION**  This is a Tier II DWA that uses modeling to estimate the surface water concentrations of quinclorac in drinking water (source water, pre - treatment) resulting from use on vulnerable sites. While Tier IDWAs are designed to screen out chemicals with low p otential risk for posing a drinking water concern, the Tier II assessment provides more site - specific, refined modeling estimates of exposure by

using additional environmental fate parameters, specific soil data, weather information, and management practic es to estimate daily concentrations for an extended period of time (up to 30 years). Screening - level Tier I modeling was used to estimate groundwater concentrations for all uses and surface water concentrations for use on cranberry and rice (the current Tier II model is not parameterized for those uses). **2.1. Mode of Action**  Quinclorac is a quinoline carboxyl ic acid. The mechanism of action is generally similar to the mechanism for the phenoxy herbicides (i.e., mimicry of the plant growth hormone auxin). **2.2. Use**  **Characteristic s**  The DWA is based on quinclorac uses as identified in the 2007 Problem Formulation for Registration Review (see D P 344485 for details) and subsequently assessed new uses . Quinclorac uses identified in the 2007 Problem Formulation were turf grasses, rice, aquatic weeds (experimental use permit) , sorghum, wheat, rights - of -way /fencerow/hedgerow, grass grown for seed , and fallow land. Subsequently proposed uses are rangeland/pasture, grass/fodder/hay, low growing berry except strawberry

(sub group 13 - 07H), and rhubarb. Uses and application rates are based on the most recent label data report (label use information system report; LUIS) provided by BEAD (7/26/2012) plus recentl y proposed new uses . Maximum application rates, minimum application intervals, and application methods are indicated in **Table 2**  (except rice and aquatic weeds). Rice is labeled for a maximum single application of 0.5 lb ai/A per season (aerial or ground application). Aquatic weeds are labeled for a maximum of two applic ations per ye ar, with a water concentration of no more than 0.5 mg ai/L. Quinclorac uses not included in the 20 12 LU IS report are reported in **Table 1**  . **Table 1**  **. Maximum Rates for Quinclorac Uses Not Included in the 20 12**  **LUIS Report**

**Use Maximum** 

**Individual Application**  **Rate (lb ai/A)**  **Maximum**

**Annual Number of**  **Applications Minim** **um**

**Application Interval**  **(days) Max** **im um** 

**Annual Rate**  **(lb ai/A) Application** 

**Me thod**  **Proposed New Uses** Lo w growing berry except straw berry (subgroup 13 - 07H) 0.25 2 30* 0.5 Ground spray Rhubarb 0.375 2 30* 0. 7 5 Ground spray * Pre -harvest interval is 60 days for low growing berry (including cranberry) and 30 days for rhubarb.

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**2.3. Monitoring Data**  EFED is not aware of any surface or ground water monitoring data for quinclorac . **3. ANALYSIS**  **3.1. Fate and Transport Characterization**  Vapor pressure (7.5 x 10 - 8 

### mm Hg at 20 o 

### C) and Henry's Law Constant (1.22 to 24.3 x 10 - 15 

### atm.m 3 

### mol - 1 

### ) indicate a low possibility of volatilization from soil and water. Laboratory data indicate that quinclorac is sta ble to hydrol ys is, photolysis in soil and sterile water, aerobic soil metabolism, and aquatic metabolism (aerobic and anaerobic) . Conversely, quinclorac undergoes rapid photolysis in non- sterile rice paddy water, natural river waters, and solutions containing activated sewage sludge (half - lives of 5 - 1 6 days uncorrected for dark controls ). Based on available laboratory

studies, two major (BH 514 - 1 and BH 514 2 - OH; >10% applied) and one minor (BH 514 - HMe - ester; <10% applied) metabolites of quinclorac were i dentified. The adsorption coefficients for quinclorac and its degradation products suggest that leaching could be a route of dissipation. Field studies indicate that quinclorac is moderately persistent to persistent (18 - 176 day

half - lives) in terrestrial environments. The octanol/water partition coefficient (KOW

### ) of 0.266 also suggests that quinclorac has a low potential to bioaccumulate. A detailed assessment of the environmental fate of quinclorac can be found in the new chemical risk assessment (DP 250179+). **3.2. Drinking Water Exposure Modeling**  **3.2.1. Surface Water Modeling**  3.2.1.1 Modeling Input All Uses Except Cranberries and Rice T ier II surface water EDWCs were calculated using PRZM (P esticide Root Z one M odel, v3.12. 3 ; June , 200 6 ) and EXAMS (EXposure Analysis M odeling S ystem, version 2.98.04.06, April 20 05) models in the PE5 shell 3



### . Standard crop scenarios were selected when available and surrogate scenarios (standard and non- standard) were used in the absence of a standard scenario specific to a given use. **Table 2**  lists the input parameters used for the PRZM/EXAMS modeling. A representative PRZM/EXAMS output file is provided in **Appendix A**  . **Table 4**  presents EDWCs of quinclorac in surface water sources from the registered and proposed uses .

3 www.epa.gov/oppefed1/models/water

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**Table 2**  **. PRZM/EXAMS Input Parameter Values**  **Param eter (Units)**  **Input Value and Unit Source/Comments**  Maximum Application Rate Turf grasses 1.4 lb ai/A x 1 0. 76 lb ai/A x 2 Sorghum 0.375 lb ai/A x 2 0.245 lb ai/A x 3 Wheat 0.245 lb ai/A x 3 Rangeland / Pasture 0.75 lb ai/A x 1 Rights of way/Fencerow/Hedgerows 1.5 lb ai/A x 1 0.76 lb ai/A x 2 Grass grown for seed 0.375 lb ai/A x 2 Fallow land 0. 75 lb ai/A x 1 Grass forage/Fodder/Hay 0.375 lb ai/A x 2 Lo w growing berries subgroup 13 - 07H (except cranberry and straw berry) 0.25 lb ai/A x 2 Rhubarb 0.375 lb ai/A x 2 Labels/BEAD 2012 information

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**Param eter (Units)**  **Input Value and Unit Source/Comments**  Minimum Reapplication Interval 14 days * 21 days (turf grasses and rights of way/fencerow/hedgerows at 0.7647 lb ai/A rate ) 30 days (low

growing berries and rhubarb) Labels/BEAD 2012 information * A minimum interval is not reported for all uses. It was assumed that the minimum interval was 14 days unless indicated otherwise, consistent with the Problem Formulation (2007) and previous assessments. There is a pre -harvest interval of 30 days for rhubarb and 60 days for low

growing berries. Modeling Scenarios Turf grasses FL turf PA turf Sorghum KS sorghum Wheat ND wheat Rangeland / Pasture FL turf PA turf CArangelandhayRLF_v2 Rights of way/Fencerow/Hedgerows CArightofwayRLF_v2 Grass grown for seed ORgrassseed Fallow land FL turf PA turf CArangelandhayRLF_v2 Grass forage/Fodder/Hay FL turf PA turf CArangelandhayRLF_v2 Lo w growing berries subgroup 13 - 07H (except cranberry and straw berry) ORberriesOP Rhubarb CA cole cropRLF_v2 CA lettuce EFED standard PRZM/EXAMS scenarios unless indicated otherwise . There is not a standard scenario for rangeland/pasture, fallow land, or grass forage/ fodder/ hay . S tandard turf scenarios and a non - standard CA range and hay scenario were used as surrogates . In the absence of a standard rights - of - way scenario, a nonstandard CA scenario was used. There is not a scenario specific to low growing berries subgroup 13 - 07H. ORberriesOP was used as a surrogate scenario. There is not a scenario specific to rhubarb. Other leafy vegetable crop scenarios were used a s surrogates (CA cole crop and CA lettuce).

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**Param eter (Units)**  **Input Value and Unit Source/Comments**  Initial Application Dates (dd- mm) Turf grasses FL turf (01 - 01, 01 - 02, 01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11, 01 - 12) PA turf (01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11) Sorghum KS sorghum (20 - 05, postplant; 09 - 04, preplant) Wheat ND wheat (01 - 08, preplant winter wheat; 25 - 03, preplant spring wheat) Rangeland / Pasture FL turf (01 - 01, 01 - 02, 01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11, 01 - 12) PA turf (01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11) CArangelandhayRLF_v2 (01 - 01, 01 - 02, 01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11, 01 - 12) Rights of way/Fencerow/Hedgerows CArightofwayRLF_v2 (01 - 01, 01 - 02, 01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11, 01 - 12) Grass grown for seed ORgrassseed (01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 0 1 - 09, 01 - 10, 01 - 11) Fallow land FL turf (01 - 01, 01 - 02, 01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11, 01 - 12) PA turf (01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11) CArangelandhayRLF_v2 (01 - 01, 01 - 02, 01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11, 01 - 12) Grass forage/Fodder/Hay FL turf (01 - 01, 01 - 02, 01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11, 01 - 12) Based on labels/BEAD 2012 information and PRZM scenarios. Additional sources: Kansas state university research and extension planting guide (www.ksre.ksu.edu/library/crps l2/l818.pdf

), North Dakota State University extension service (www.ag.ndsu.edu) Certain uses do not restrict when application may occur, in those cases it was assumed that application could occur throughout the year (winter mo nths were excluded in certain scenario s depending on geography).

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**Param eter (Units)**  **Input Value and Unit Source/Comments**  PA turf (01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11) CArangelandhayRLF_v2 (01 - 01, 01 - 02, 01 - 03, 01 - 04, 01 - 05, 01 - 06, 01 - 07, 01 - 08, 01 - 09, 01 - 10, 01 - 11, 01 - 12) Lo w growing berries (except cranberry and straw berry) ORberriesOP (01 - 05) Rhubarb CA cole cropRLF_v2 (01 - 01) CA lettuce (13 - 03) Application Method Ground (turf grasses, rights - of way/ fencerow / hedgerows, low growing berries, rhubarb) Aerial (sorghum, wheat, rangeland/pasture, grass grown for seed , fallow

land , grass forage / fodder /hay Foliar (CAM = 2) (turf grasses, sorghum, rangeland/pasture, rights - of way/fencerow/hedgerows, grass grown for seed , grass forage / fodder /hay, low growing berries, rhubarb) Surface (CAM = 1) (sorghum, wheat, fallow land) Labels/BEAD 2012 information Aerial application method was used as input when aerial and ground applications are permitted at the same application rate. Aerial applications result in higher EDWCs. Aerial application is permitted for rights - of

- way/ fencerow/hedgerow but at a lower rate than ground applications . Ground applications resulted in higher EDWCs . Application Efficiency Fraction 0.99 (ground) 0.95 (aerial) EFED guidance 1 Spray Drift Loading Fraction 0.064 (ground) 0.16 (aerial) EFED guidance 1 Incorporation depth (cm) 0 Molecular Weight (g/mole) 242 Product Chemistry Water Solubility (mg/L) 64 Product Chemistry Vapor Pressure (torr) 7.5 × 10 - 8 Product Chemistry KOC (L/kg oc) 36 Mean Value (EFED guidance ) 1 MRID 41063562 Hydrolysis Half

- life (days) 0 MRID 40320816 Stable Aqueous Photolysis Half - life (days) 0 MRID 41063560 Stable

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**Param eter (Units)**  **Input Value and Unit Source/Comments**  Aerobic Soil Metabolism (days) 622 MRID 44084503 and 41247301 90 th percentile confidence interval on mean half

- life (168 and 391 days) (EFED guidance) 1 Aerobic Aquatic Metabolism (days) 0 MRID 42294102 and 42294103 Stable Anaerobic Aquatic Metabolism (days) 0 MRID 42294104, 41063561, and 42786401 Stable 1 Input Parameter Guidance Manual, Pesticides (Version 2.1; Oct. 22, 2009) 

### Cranberries The Provisional Cranberry Model (v2, December 8, 2010), a provisional refinement to the Tier I Rice Model (v1.0, May

8, 2007) , was used to calculate EDWCs in surface waters for use of quinclorac on cranberry . Refinements include the addition of simple degradation processes in dry and flooded conditions and a water depth of twelve inches rather than the water depth of four inches used in the rice model. These modifications allow estimation of screening- level peak and annual mean EDWCs of quinclorac residues of concern that may occur in untreated surface water used as drinking water following use on cranberries. The model assumes that degradation on dry cranberry

bog soil occurs predominantly via aerobic microbial metabolism. Additionally, residue degradation in flooded bogs is assumed to occur via aerobic microbi al metabolism in the water column and via anaerobic microbial metabolism in the sediment. Quinclorac use on cranberries is labeled for an annual maximum of two applications of 0. 25 lb ai/A each. The minimum interval between applications is 30 days and the preharvest interval is 60 days . The proposed applications were first aged on dry soils because cranberry

bogs are not ty picall y flooded until the night before harvesting. The resulting residues (in lb ai/A) were then summed and used as input for the fl ooded component of the model to estimate peak and annual mean EDWCs in bog tailwater following harvest. M odel input parameters are listed in **Table 3**  . The equations used in the Provisional Cranberry Model are briefl y described in **Appendix B**  . **Table 4**  presents EDWCs of quinclorac in surface water sources from use on cranberry . **Table 3**  **. Provisional Tier 1 Cranberry Model Input Parameters Input Parameter**  **Value Source**  Application Rate (lb ai/A) 0.25 Labels Applications per Year 2 Labels Organic Carbon Partition Coefficient (KOC) (L/kg OC) 36 MRID 41063562 Average Value (EFED guidance)

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**Input Parameter Value**  **Source** Aerobic Soil Metabolism Half - life (days) 622 MRID 44084503 Upper 90 th percentile confidence interval on the mean of two half

- lives: 168 and 391 days (EFED guidance) Aerobic Aquatic Metabolism Half - life (days) 1295 MRIDs 42294102 and 42294103 Upper 90 th percentile confidence interval on the mean of two half

- lives: 1229 and 393 days (EFED guidance) 1 1 Quinclorac is considered stable to aerobic aquatic metabolism based on the available study results. Half - lives were extrapolated well beyond the study duration (30 days). Those values were used as the basis for representing aerobic aquatic metabolism in the Provisional Cranberry model because a half - life value is required for input. 

### Rice Quinclorac use on rice is labeled for a single maximum application of 0.5 lb ai/A (once per season). The Tier I rice model (v1.0) 4 

### was used to estimate EDWCs for use of quinclorac on rice: C w 

### = m ai ′ 

### / (0.00105 + 0.0000013*Koc 

### ) where C w 

### = EDWC (μg/L), mai ′ 

### = application rate (kg/ha), and Koc 

### = mean organic carbon partition coefficient (L/kgoc 

### ). 3.2.1.2 Surface Water Estimated Drinking Water Concentrations **Table 4**  **. Estimated Drinking Water Concentrations (EDWCs) of Quinclorac in Surface**  **Water Sources**

**Use Scenario**  **Estimated Drinking Water Concentrations from** **Surface Water Sources (μg/L) 1,2,3**  **1 -**  **in -**  **10 year acute**  **1 -**  **in -**  **10 year**

**chronic 30**  **- year** 

**mean** 

### Turf grasses (1.4 lb ai/A x 1) (0.76 lb ai/A x 2) FL turf 4 

### 41.3 28.5 16.8

PA turf 4,5 

### 58.3 37.8 20.0 FL turf 4 

### 43.1 32.8 16.3 PA turf 4,5 

### 74.1 62.0 **23.7** Sorghum (0.375 lb ai/A x 2) (0.245 lb ai/A x 3) KS sorghum (postplant) 6 

### 26.3 10.5 6.9

KS sorghum (postplant/fall) 7 

### 20.5 10.2 6.3 KS sorghum (preplant) 23.6 9.5 6.4 Wheat ND wheat (preplant

spring) 38.7 26.9 16.5 ND wheat (preplant winter) 46.6 28.6 19.3

4 http://www.epa.gov/oppefed1/mode ls/water

### 11 **Use Scenario**  **Estimated Drinking Water Concentrations from** **Surface Water Sources (μg/L) 1,2,3**  **1 -**  **in -**  **10 year acute**  **1 -**  **in -**  **10 year**

**chronic 30**  **- year** 

**mean** 

### Rangeland / Pasture FL turf 4 

### 29.3 21.2 14.6 PA turf

4,5 

### 36.6 25.3 16.0 CArangelandhayRLF_v2 4 

### 54.0 36.9 20.5 Rights of way /Fencerow /Hedgerows 1.5 lb ai/A x 1 0.76 lb ai/A x 2 CArightofwayRLF_v2 4 

### 24.7 14.9 8.2

CArightofwayRLF_v2 4 

### 27.7 14.3 8.4 Grass grown for seed4,5 

### ORgrassseed4,5 

### 25.4 15.8 11.0 Fallow land FL turf 4 

### 27.1 19.6 13.7 PA turf

4,5 

### 31.5 21.1 13.6 CArangelandhayRLF_v2 4 

### 39.3 27.2 16.4 Grass forage /Fodder /Hay FL turf 4 

### 26.4 18.5 14.4 PA turf

4,5 

### 27.1 21.4 14.9 CArangelandhayRLF_v2 4 

### 46.8 31.7 20.6 Low growing berry (except cranberry and strawberry) ORberriesOP 3.4 2.0 1.3 Rhubarb CA cole crop RLF_v2 33.8 18.0 11.4

CA lettuce 27.9 18.8 12.9 Cranberry Provisional Cranberry

Model 8 

### 161.9 147.2 -- Rice Tier I Rice Model 9 

### 511.1 **511.1 --**  Aquatic Weeds 10 

### Labeled concentration 500.0 500.0 **--** 1 PCA = 1 (www.epa.gov/oppefed1/models/water ) because this is a national drinking water assessment and quinclorac is registered for non- agricultural, non -turf uses. 2 **BOLD** indicates highest EDWC 3 EDWCs based on aerial applications are presented for uses that permit aerial and ground applications at the same application rate . 4 Highest value of twelve estimates (first application on the first day of each month) because there are no restrictions on when pesticide may be applied. 5 Although permitted, it was assumed that winter applications would be unlikely (December, January, February). 6 Two applications between preemergence and postemergence (up to 12 inches) 7 One application between preemergence and postemergence (up to 12 inches) and one application in the fall prior to the first killing frost 8 Based on a one - year simulation; 1 in 10 year calculation is not applicable. 9 Based on a single, s creening level concentration; 1 in 10 year calculation i s not applicable. 10 Registered as an experimental use permit.

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**3.2.2. Ground Water Modeling**  The model SCI- GROW (v 2.3 ) 5 

### was used to calculate EDWCs in drinking water from shallow ground water sources. **Table 5**  lists model input parameters. An example output is provided in **Appendix C** . **Table 6**  presents EDWCs of quinclorac in groundwater sources from the registered and proposed uses. **Table 5**  **. S CI**  **- GROW Model Input Parameters**  **Input Parameter Value**  **Source** Application Rate (lb ai/A) Variable 1 Labels/BEAD 2012 information Applications per Year Variable 1 Labels/BEAD 2012 information Organic Carbon Partition Coefficient (KOC) (L/kg OC) 38 MRID 41063562 Median Value (EFED guidance) 2 Aerobic Soil Metabolism Half - life (days) 280 MRID 44084503 Mean Value (EFED guidance) 2 1 Modeled rates for each use are presented in **Table 6**  . 2 www.epa.gov/oppefed1/models/water/scigrow _description.htm#instructions 

### Table **6 . Estimated Drinking Water Concentrations (EDWCs) of Quinclorac in Ground**  **Water Sources**

**Use Application Rate**  **Estimated Drinking Water Concentrations from** **Ground Water Sources (μg/L)**  **1 Acute**  **Chronic** 

### Turf grasses 1.4 lb ai/A x 1 2 7 2 7 0.76 lb ai/A x 2 **29 29**  Sorghum 0.375 lb ai/A x 2 and 0.245 lb ai/A x 3 14 14 Wheat 0.245 lb ai/A x 3 14 14 Rangeland / Pasture 0.75 lb ai/A x 1 14 14 Rights of way/Fencerow/Hedgerows 1.5 lb ai/A x 1 **29 29**  0.76 lb ai/A x 2 **29 29**  Grass grown for seed 0.375 lb ai/A x 2 14 14 Fallow land 0.75 lb ai/A x 1 14 14 Grass forage /Fodder /Hay 0.375 lb ai/A x 2 14 14 Low growing berry (except cranberry and strawberry) 0.25 lb ai/A x 2 10 10 Rhubarb 0.375 lb ai/A x 2 14 14 Rice 2



### -- -- -- Cranberry2



### -- -- -- Aquatic Weeds 2



### -- -- -- 1 **BOLD** indicates highest EDWC 2 Groundwater concentrations are not estimated for aquatic uses.

5 http://www.epa.gov/oppefed1/models/water

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**3.2.3. Assumptions and Uncertainties** The following label uncertainties have been identified:

• All labels do not specify a minimum application interval. As in previous assessments and as noted in the registration review problem formulation (DP 344485) , the minimum interval was assumed to be 14 days when an interval was not specified. A shorter interval may increase EDWCs.

• Most labels specify

application on rice as a seasonal maximum application instead of an annual maximum . It was assumed that there is a limit of one crop cycle per year ; that is, the seasonal maximum is equivalent to the annual maximum . Multiple crop seasons may increase EDWCs given the persistence of quinclorac .

• One label (registration 279 - 3355) for various turf grass uses does not state a maximum number of applications or an annual maximum application rate per acre. EFED assumed that the annual maximum was 1.4 lb ai/A/year. EDWCs would be higher if the label intended for more than one application at this rate.

• Certain uses do not restrict when application may occur. A range of application dates were modeled in those cases. These values may be refined if the label language is updated to be more restrictive in terms of timing of application.

• There are inconsistencies between and within the submitted Quinclorac 4L AG label and the supplemental label information sheets for proposed use on rhubarb and low growing berry (except strawberry) subgroup 13 - 07H. Specific inconsistencies include:

- The labels alternate between referring to the product as Quinstar 4L Herbicide and QUINCLORAC 4L AG.

- It was assumed that “Restrictions and Limitations - Cranberry” applies to all low growing berries in sub - group 13 - 07H (except strawberry).

- The maximum annual application rate for cranberry (and other low growing berries) is specified as 16.8 fl oz/A on one label and as 16 fl oz/A on the other label. It was assumed that the maximum annual application rate is 16.8 fl oz/A ( i.e. , 0.5 lb ai/A) given that up to two applications of 8.4 fl oz/A are allowed per ye ar.

- The maximum annual application rate for rhubarb is specified as “xx” fl oz/A on one label and as 25.2 fl oz/A on the other. It was assumed that the maximum annual application rate is 25.2 fl oz/A ( i.e. , 0. 75 lb ai/A) given that up to two applications of 12.6 fl oz/A are allowed per year.

### 14 **APPENDIX A**  **PRZM/EXAMS Modeling Output** stored as ca lett.out Chemical: Quinclorac PRZM environment: CAlettuceSTD.txt modified Tueday, 26 August 2008 at 06:16:36 EXAMS environment: ir298.exv modified Tueday, 26 August 2008 at 06:14:08 Metfile: w23273.dvf modified Tued ay, 26 August 2008 at 06:15:40 Water segment concentrations (ppb) Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 21.06 20.96 20.45 14.35 9.946 3.265 1962 19.15 19.04 18.56 17.54 17.02 13.37 1963 28.11 27.94 27.46 26.09 25.13 18.11 1964 21.37 21.27 20.82 19.73 17.1 14.63 1965 17.84 17.74 17.32 16.42 15.99 13.92 1966 12.83 12.76 12.46 11.82 11.56 9.969 1967 13.89 13.81 13.48 12.81 12.33 9.959 1968 28.57 28.39 27.77 26.44 23.94 14.3 1969 24.46 24.32 23.89 22.82 21.95 18.96 1970 20.2 20.08 19.77 15.01 14.5 1 2.52 1971 21.9 21.77 21.24 20.11 19.3 16.3 1972 17.04 16.96 16.64 16.07 14.94 10.83 1973 23.49 23.4 22.86 22.18 21.39 16.33 1974 26.87 26.75 26.09 22.25 18.3 13.22 1975 24.83 24.68 24.08 22.79 22.07 16.83 1976 20.64 20.55 20.15 19.51 19.1 13.67 1977 35.75 35.61 34.78 32.89 31.55 23.09 1978 22.97 22.83 22.28 21.08 20.3 17.08 1979 16.64 16.55 16.17 15.34 15.08 13.17 1980 13.35 13.27 12.95 10.22 10.01 9.069 1981 16.95 16.87 16.47 16.14 15.6 12.76 1982 15.78 15.68 15.31 15.1 14.65 11.47 1983 11.73 11.67 11.38 1 0.82 10.4 8.32 1984 7.157 7.117 6.949 6.652 6.538 5.659 1985 12.17 12.09 11.88 10.8 8.786 5.804 1986 26.92 26.76 26.07 25.33 24.46 19.58 1987 21.46 21.35 20.85 19.78 19.28 15.36 1988 25.32 25.17 24.56 23.34 22.41 15.74 1989 12.52 12.46 12.18 11.57 11.33 9. 403 1990 7.398 7.356 7.185 6.917 6.841 5.947 Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 35.75 35.61 34.78 32.89 31.55 23.09 0.0645161290322581 28.57 28.39 27.77 26.44 25.13 19.58 0.0967741935483871 28.11 27.94 27.46 26.09 24.46 18.96 0.129032258064516 26.92 26.76 26.09 25.33 23.94 18.11 0.161290322580645 26.87 26.75 26.07 23.34 22.41 17.08 0.193548387096774 25.32 25.17 24.56 22.82 22.07 16.83 0.225806451612903 24.83 24.68 24.08 22.79 21.95 16.33 0.258064516129032 24.4 6 24.32 23.89 22.25 21.39 16.3 0.290322580645161 23.49 23.4 22.86 22.18 20.3 15.74 0.32258064516129 22.97 22.83 22.28 21.08 19.3 15.36 0.354838709677419 21.9 21.77 21.24 20.11 19.28 14.63 0.387096774193548 21.46 21.35 20.85 19.78 19.1 14.3

### 15

0.41935483870967 7 21.37 21.27 20.82 19.73 18.3 13.92 0.451612903225806 21.06 20.96 20.45 19.51 17.1 13.67 0.483870967741936 20.64 20.55 20.15 17.54 17.02 13.37 0.516129032258065 20.2 20.08 19.77 16.42 15.99 13.22 0.548387096774194 19.15 19.04 18.56 16.14 15.6 13.17 0.5806 45161290323 17.84 17.74 17.32 16.07 15.08 12.76 0.612903225806452 17.04 16.96 16.64 15.34 14.94 12.52 0.645161290322581 16.95 16.87 16.47 15.1 14.65 11.47 0.67741935483871 16.64 16.55 16.17 15.01 14.5 10.83 0.709677419354839 15.78 15.68 15.31 14.35 12.33 9 .969 0.741935483870968 13.89 13.81 13.48 12.81 11.56 9.959 0.774193548387097 13.35 13.27 12.95 11.82 11.33 9.403 0.806451612903226 12.83 12.76 12.46 11.57 10.4 9.069 0.838709677419355 12.52 12.46 12.18 10.82 10.01 8.32 0.870967741935484 12.17 12.09 11.88 10.8 9.946 5.947 0.903225806451613 11.73 11.67 11.38 10.22 8.786 5.804 0.935483870967742 7.398 7.356 7.185 6.917 6.841 5.659 0.967741935483871 7.157 7.117 6.949 6.652 6.538 3.265 0.1 27.991 27.822 27.323 26.014 24.408 18.875 Average of yearly average s: 12.9545 Inputs generated by pe5.pl - Novemeber 2006 Data used for this run: Output File: ca lett Metfile: w23273.dvf PRZM scenario: CAlettuceSTD.txt EXAMS environment file: ir298.exv Chemical Name: Quinclorac Description Variable Name Value Units Comm ents Molecular weight mwt 242 g/mol Henry's Law Const. henry atm - m^3/mol Vapor Pressure vapr 7.5e - 8 torr Solubility sol 64 mg/L Kd Kd mg/L Koc Koc 36 mg/L Photolysis half - life kdp 0 days Half - life Aerobic Aquatic Metabolism kbacw 0 days Halfife Anaerobic Aquatic Metabolism kbacs 0 days Halfife Aerobic Soil Metabolism asm 622 days Halfife Hydrolysis: pH 7 0 days Half - life Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI cm Application Rate: TAPP 0.42 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.064 fraction of application rate applied to pond Application Date Date 13 - 03 dd/mm or dd/mmm or dd - mm or dd - mmm Interval 1 interval 30 days Set to 0 or delete line for single app. app. rate 1 apprate .42 kg/ha Record 17: FI LTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Reservoir Flag for runoff calc. RUNOFF total none, monthly or total(average of entire run)

### 16 **Appendix B**  **I . Provisional Cranberry Model Equations**  The Provisional Cranberry Model is a refinement of the Tier I Rice Model v1.0 (Equations 1 and 2), which is a simple equilibrium partitioning equation that calculates a single, screening - level concentration in rice paddy water and released tailwater based on a compound’s application rate and soil mobility . **Equations 1 -** **2: Tier I Rice Model v1.0 (USEPA, 2007b).** 

#   d b sed sed w ai w 

## K d d m C 

 3 2 0 

## 10

' 10

 

##    (1) and, if appropriate: OC d 

## K K 01 . 0  (2) where, C w0 

### = initial water concentration [μg/L] m ai 

### ' = mass applied per unit area [kg/ha] Kd 

### = water- sediment partitioning coefficient [L/kg] KOC 

### = organic carbon partitioning coefficient [L/kg] dw 

### = water column depth = 0.10 m dsed 

### = sediment depth = 0.01 m θ sed 

### = porosity

of sediment = 0.509 ρ b 

### = bulk density

of sediment = 1300 kg/m 3 

### First, the Tier I Rice Model was provisionally modified (Equation 3) to include as inputs degradation rate constants in order to estimate single, screening - level concentrations in paddy water or tailwater at a given time after application. **Equation 3: Provisional Modified Rice Model (Jones, 2006).**      

##     t K d d k

K d k d k d w w d b sed sed w d b sed sed sed w 

## e C C         

  



  

##   3 3 3 2 1 10 10 0     

### (3) where, C w 

### = water concentration [μg/L] t = interval since last application [d] k 1 

### = upper 90 th 

### percentile rate constant in water column [1/d] k2 

### = upper 90 th 

### percentile rate constant in pore water [1/d] k3 

### = upper 90 th 

### percentile rate constant for adsorbed residues [1/d] Then, the Provisional Modified Rice Model water column depth was lengthened to a depth that is used to flood cranberry bogs ( i.e. , 12 inches ; Cape Cod Cranberry Growers Association, 2001 ). i.e. , dw 

### = water column depth = 0.305 m

### 17

In order to model degradation prior to the flood at harvest, the application rates for n number of pre -harvest applications were independently degraded over the interim until flooding and then summed (Equation 4). **Equation 4: Degradation in a Dry Bog.** 

# 

 

##   n t

k n ai ai n



## e m m 1 4



## ' ' (4) where, m ai 

### ' = mass per unit area at flood [kg/ha] m ai 

### ' n 

### = mass applied per unit area on the nth 

### application [kg/ha] k4 

### = upper 90 th 

### perc entile rate constant on dry bog [1/d] tn 

### = interval from the nth 

### application to harvest [d] n = number of pre -harvest applications The following four equations and parameter sets constitute the Provisional Cranberry Model (Equations 1 - 4). **Equations 1 -** **4: Provisional Cranberry Model.**  

#   d b sed sed w ai w 

## K d d m C 

 3 2 0 

## 10

' 10

 

##    (1) and, if appropriate: OC d 

## K K 01 . 0  (2) where, C w0 

### = initial water concentration [μg/L] Kd 

### = water- sediment partitioning coefficient [L/kg] KOC 

### = organic carbon partitioning coefficient [L/kg] dw 

### = water column depth = 0.305 m dsed 

### = sediment depth = 0.01 m θ sed 

### = porosity

of sediment = 0.509 ρ b 

### = bulk density

of sediment = 1300 kg/m 3 

### and, lastly :     

##     t K d d k

K d k d k d w w d b sed sed w d b sed sed sed w 

## e C C         

  



  

##   3 3 3 2 1 10 10 0     

### (3) where, C w 

### = water concentration [μg/L] t = interval since flood [d] k 1 

### = upper 90 th 

### percentile rate constant in water column [1/d] k2 

### = upper 90 th 

### percentile rate constant in pore water [1/d] k3 

### = upper 90 th 

### percentile rate constant for adsorbed residues [1/d]

### 18

**II .**  **Output of Provisional Cranberry Model Pr** **ovi si**  **onal C**  **ran berry Mo**  **del v** **2. 0** 

Equ ation : EEC= (Ap p rat e * 100 / (dw + ( ds ed * (θ+ ( ρ* Kd / 1 000))))) * exp (-day * k AAM )

*W at er co lumn dept h is 1 2 inc hes ( 0. 305 m)to1 8 inc hes ( 0. 457 m) . 

### Ap **pl ic**  **ati on**  **In put** **s Ap**  **p. ra te**  **( lbs** 

**/A )**  **Da ys** 

**pre -fl**  **ood Ap**  **p. ra te**  **a t**  **fl ood (**  **lb s/** **A) 0.**  **25 90**  0. 23 **0. 25**  **60** 0. 23 0. 00 **Tota l re**  **si due**  **s pe**  **r a re**  **a at f** **lo od (**  **lbs**

**/A ):**  **0. 46**  

### In **put s**  **Pa ra**  **me te**  **r Valu**  **e** Ko c ( L/ kg ) **36** If no Ko c, e nt er Kd ( L/ kg ) AAM t1 /2( d) **1295** ASM t1 /2( d) **622** 

### Model**P arameters**  **Pa ra**  **me te**  **r Valu**  **e** Wa te r co lumn dept h (m) 0. 305 Se dimentd ept h (m ) 0. 01 Organicf

rac tion of se di ment 0. 01 Se dimentb ul k d ens it y ( kg /m3 ) 1300 Se dimentp oros ity 0. 509 

### Cal **cul ated**  **Par ameters**  **Pa ra**  **me te**  **r Valu**  **e** Kd i nput( L/ kg ) 0. 36 AAM rat e co ns ta nt 0. 000535249 ASM rat e co ns ta nt 0. 00111 Ap p. r at e (k g/ ha) 0. 515630335 

### DW **EECs 100%**  **PC A**  **Ho lding Time**  **Peak An**  **nua l M**  **ean Pe**  **ak An**  **nua l Mea**  **n** 3-d Ta il 163. 55 148. 60 155. 37 141. 17 **21-d Ta**  **il 161.**  **98 147.**  **18 153.**  **88 139.**  **82 95%**  **PC A** 

### 19 **APPENDIX C** SCIGROW VERSION 2.3 ENVIRONMENTAL FATE AND EFFECTS DIVISION OFFICE OF PESTICIDE PROGRAMS U.S. ENVIRONMENTAL PROTECTION AGENCY

SCREENING MODEL FOR AQUAT IC PESTICIDE EXPOSURE

SciGrow version 2.3 chemical:quinclorac time is 5/ 8/2012 10:49: 5

- ----------------------------------------------------------------------- Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

-------------------------------------------- ---------------------------- 0.375 2.0 0.750 3.80E+01 280.0

------------------------------------------------------------------------ groundwater screening cond (ppb) = 1.43E+01 *********************************************** *************************