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 OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION UNITED ST AT ES ENVIRONMENT AL PROTECTION A GENCY

WA SHINGTON, D.C. 20460



### MEMORANDUM DATE: July

22, 2010 SUBJECT: Estimated Drinking Waters Concentrations (EDWCs) of Triflusulfuron
- methyl

for the Use in the Human Health Risk Assessment : New Use (IR
- 4) of the Chemical on Garden Beets (PC Code 1 29002 ; DP Barcode D3734 94 ) TO: Laura Nollen, Risk Manager Reviewer

Barbara Madden, Review Manager #5 Daniel (Dan) Rosenblatt , Chief Minor Use Team Risk Integration, Minor Use, and Emergency Response Branch Registration Division (7505P) AND : Elizabeth Holman, Chemist, Risk Assessor

Linnea Hansen , Risk Assessor Christina Swartz, Chief Registration Action Branch I I Health Effects Division (7509P) FROM: José L
. Meléndez, Chemist

Environmental Risk Branch V Environmental Fate and Effects Division (7507P) THRU: Mah T. Shamim, Ph.D., Chief

Environmental Risk Branch V Environmental Fate and Effects Division (7507P) This memo presents the s urface and ground Estimated Drinking Water Concentrations (EDWCs) for triflusulfuron
- methyl , calculated using the Tier 2 aquati c model s PRZM/ EXAMS and the Tier 1 aquatic model SCI
- GROW, respectively , for use in the human health risk assessment. The registrant is proposing the use of the chemical on garden beets
. Based on an inspection of the new use of triflusulfuron
- methyl , it was found that sugar beet still represents the scenario with the highest exposure. The previously modeled use cover s the new use. T herefore,

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the drinking waters assessment results do not change from the previous ones
. For electronic copy of the previou s drinking waters assessment refer to DP Barcode D260078 (Attachment A , see page 3 of this document)
. The EDWCs for triflusulfuron
- methyl , calculated using the Tier 2 models PRZM/ EXAMS (surface water) and the Tier 1 model SCI
- GROW (ground water) for use in the human health risk assessment were as follows: In surface waters , the acute value is 0.42 ppb and the chronic value is 0. 005 ppb . The groundwater screening concentration of triflusulfuron
- methyl suitable for both acute and chronic exposures is 0. 50 ppb ( Table 1 ). Should any questions arise, please, contact EFED. Table 1. Estimated Drinking Water Concentrations (EDWCs) for human health risk assessment for aerial application of triflusulfuron - methyl on sugar beets Chemical Ac ute Surface Water

P RZM/EXAMS (ppb) Chronic Surface Water PRZM/EXAMS (ppb) Ac ute and Chronic Ground Water SCI
- GROW (ppb) * Triflusulfuron
methyl 0.42 0.005 0.50 

### Identification of data gaps : Additional aerobic and anaerobic soil studies and aerobic and anaerobic aquatic metabolism studies would decrease substantiall y the uncertainties in the fate database. Use Characterization Table 2 provides a summary of the new use proposed in this action for triflusulfuron
methyl , as well as the approved uses for the chemical
. The use information was obtained from the current and proposed supplemental label for DuPontTM UpBee t® Herbicide (EPA Reg. No. 352
- 569 ). DuPontTM UpBeat ® is a water dispersible granule (dry flowable) formulation, containing 50% active ingredient. Table 2. Summary of use information for triflusulfuron - methyl , based on the proposed label for DuPontTM UpBee t® Herbicide (EPA Reg. No. 352 - 569 ) . The new use is shaded yellow and bolded .

USE SINGLE APP. RATE (lb a.i./A) NUMBER

OF APPS. SEASONAL

APP. RATE (lb a.i./A) INTERVAL

BETWEEN APPS. (days) APP.

METHOD INCORP .

DEPTH ( inches) PHI Garden beets 0.0156 3 0.0469 NS 1 G or A 2 0 2 60 2 Sugar beets (includes those grown for seeds) 0.0156
- 0.0313; 0.00391 3 2
- 3 0.0781 5 G or A 0 60 Belgian Endive/Chicory 0.0156 2
- 3 0.0469 5 G or A2 0 2 60 1 Not specified. Apply at 2 to 4 leaf st age; additional applications at 4 to 6 and 6 to 8 leaf stage s . 2 Per reference to Section 3 label in the Supplemental Label and instructions provided in the package. 3 Microrate applications (make a minimum of 3 applications )
.

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## Attachment A . Electronic cop y of previous DWA for Triflusulfuron - methyl

UNITED STATES ENVIRONMENTA L PROTECTION A GENCY

WASHINGTON, D.C. 20460 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES 

### December 20, 1999 DP Barcode: D260078 PC Code: 129002 

### MEMORANDUM Subject: Triflusulfuron
- Meth ylTier II Estimated Environmental Concentrations for Use in

the Human Health Drinking Water Risk Assessment Product: UpBeet Water Dispersible Granule (50% Active); 352
- 569 Registrant: DuPont To: Michael Dohe rty

Registration Action Branch 2 Health Effects Division (7509C) Vickie Walters, Product Manager Herbicide Branch Registration Division (7505C) From: Sid Abel, Environmental Scientist

Fate and Monitoring Branch Environmental Fate and Effects Division ( 7507C) Thru: Bets y Behl, Chief

Fate and Monitoring Branch Environmental Fate and Effects Division (7507C) This memorandum transmits the Tier II Estimated Environmental Concentrations (EECs) for the tolerance reassessment of triflusulfuron
- methyl a pplied to sugarbeets using the Index Reservoir (IR) and Percent Crop Area (PCA) modifications to PRZM and EXAMS. These results do not include EECs for an y of triflusulfuron
- methyl’s known degradates. Should HED determine that there is a need for a separate assessment for toxicologically significant degradates, please contact Sid Abel (305
- 7346) as soon as possible.

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## Summary and Conclusions Triflusulfuron
- methyl may be found in surface water used as a source of drinking water at peak concentrations up to 0.42 μg/Land on a long
- term basis (mean) at 0.005 μg/L from use on sugarbeets in Minnesota. Ground water concentrations, independent of the use area, may be found at up to 0.5 μg/L; peak and mean concentrations. Triflusulfuron
- methyl will not persist i n the environment (accumulate between repeated ye arly applications) due to its short initial half
life (bi
- phasic) and h ydrolytic half
- life at environmental pH’s. The low adsorption coefficients may facilitate triflusulfuron’s leaching to ground water und er favorable conditions (shallow depth to groundwater, coarse soils, or soils with significant preferential flow). Due to triflusulfuron
- methyl’s structure and phy sical properties, it is not likely to be significantly affected b y common treatment methods e mployed at most community water sy stems (Faust, 1998). Triflusulfuron
- methyl is currentl y registered for use on sugarbeets. Estimated environmental concentrations for sugarbeets are provided Table 1. These estimated values are recommended for use in the drinking water assessment. Table 1. Recommended Surface and Ground Water Concentrations ( μg/L) Agricultural Setting Surface Water Concentrations Ground Water Concentrations Sugarbeets Grown in Minnesota Peak Mean 0.50 0.42 0.005 

## Enviro nmental Fate Summary Triflusulfuron - methyl is not a very persistent sulfonylurea herbicide. The principle pathway of dissipation in the environment is through aerobic and anaerobic metabolism and to a lesser degree hydrolysis. Direct photolysis on soil and in water is not a very important pathway, but indirect photolysis may play a minor role in its degradation on soils. Biotically, Triflusulfuron - methyl degradation follows a bi - phasic pattern with an approximate soil half

- life of 6 days initially, foll owed by a secondary half - life of approximately 170 days in aerobically incubated soil. Under anaerobic soil conditions, triflusulfuron - methyl degraded with a half - life of 20 days. Triflusulfuron - methyl is mobile in all soils tested; Kd 

### ’s less than 1.3. However, the parent was not detected below 14 inches in the two field dissipation studies and decreased in concentration over the period of the study indicating biotic degradation. Sorption was not well correlated to organic matter, but was better correla ted to the soil pH. Triflusulfuron - methyl degrades through cleavage of the sulfonylurea bridge to form degradates containing either the triazine or phenyl ring. The principle degradates seen in the laboratory studies is methyl saccharin and various tria zine amines. Methyl saccharin is mo re mobile than the parent with Kd 

### ’s all less than 1.0 (KOC 

### ’s <25). In several of the soils, binding was so low that analysis could not be performed to determine the extent of binding.

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The half - life of methyl saccharin is 50 - days under aerobic conditions and further degrades via mineralization. The other major degradates, triazine - am ines, are less mobile than the parent. Among the triazine - am ines, mobility increases with a higher degree of demethylation. The bis - NDM - t riazine amine is the most mobile with Kd 

### ’s up to 3.72 (KOC 

### ’s <220) and the least mobile, triazine - am ine, had Kd 

### ’s up to 10 (KOC 

### ’s <2175). For NDM triazine - am ine, Kd 

### ’s were up to 4.88 (KOC 

### ’s <300). The half - life of triazine amine is approximately 40 days and further degrades by demethylation. Both degradates were detected up to the 36 - inch segment in one or both of the field dissipation studies. Concentrations of methyl saccharin and triazine amine were very similar during the studies and dissipated with very similar patterns. 

## Water Resources Summary: Drinking Water A. Surface Water PRZM/EXAMS modeling using the Index Reservoir (IR) and the Perc ent Crop Area (PCA) adjustment was used to estimate concentrations in surface water used as a source of drinking water. The index reservoir represents a watershed that is more vulnerable than most used as drinking water sources. It was based on characteristics of a real watershed located in western Illinois (Jones, et al. , 1998). The index reservoir defines a standardized watershed which is tailored for each crop simulated b y adding local soils, weather, and cropping practices to represent a vulnerable watershed for that crop. If a community derives its drinking water from a large river, the estimated exposur e using the IR would likely be higher than the actual exposure. Conversel y, a community that derives its drinking water from reservoirs smaller than the IR and/or with minimal outflow would likely get higher drinking water exposure than estimated using th e index reservoir. Also, areas with a more humid climate than the modeled scenario that use a similar reservoir and cropping pattern, would likely have higher pesticide concentrations in their drinking water than predicted. Transport through the reservoi r is represented b y a single steady flow and does not take into account reservoir discharges and withdrawals. This assumption will underestimate removal from the reservoir during wet periods and overestimate removal during dry periods. The index reservoir scenario uses the characteristic of a single soil to represent all soils in the basin. Soils can vary substantially

across even small areas, however, this variation is not reflected in these simulations. The index reservoir scenario does not take int o account pesticide or water input from tile drainage. Areas that are prone to substantial runoff are often tile drained. This may underestimate exposure, particularl y on a chronic basis (the watershed on which the IR is based had no documented tile drai nage). Additionally , EXAMS is unable to easily model spring and fall turnover events which results in complete mixing of a chemical through the water column. Because of this inability , Shipman City L ake has been simulated without stratification. There is data to suggest that Shipman City L ake does stratify

in the deepest parts of the lake at least in some years. This may

result in both an over and underestimation of the concentration in

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drinking water depending upon the time of the ye ar and the depth the drinking water intake is drawing from. A full description of the Index Reservoir and assumptions is provided in the “ Guidance for Use of the Index Reservoir in Drinking W ater Exposure Assessment” available from EFED upon request. Development of a Percent Crop Area (PCA), watershed
- based adjustment factor for the percent of land in production for a specific crop, for sugarbeets has not been performed. The SAP recommended against the use of the PCA for ‘minor’ crops because it believed that the scale of the watershed size used to develop the PCA was too large and the resulting PCAs would likely be highl y inaccurate and not conservative. In the absence of a PCA for sugarbeets, a default PCA of 0.9 is currently being used. This is based on the highest PCA fo r all 8
- digit HUCs in the coterminous U.S. was selected for the default PCA. This value is 90 percent (0.9); representing a basin where 90 percent of the land area is in some form of agricultural production. Tier 2 modeling with the index reservoir and the PCA is intended for use as a screen. That is, the estimated concentration should be higher than most values that occur in areas where a particular crop is grown. A preliminary assessment comparing monitoring data for a few chemicals to estimates made using these methods indicate that IR/PCA estimates may not be consistently

conservative. However, monitoring data at drinking water facilities is sparsely available and we are unable to check the validity for most crops against monitoring data at this tim e. Additional inherent limitations in the data used to develop the PCA include:

• The conversion of county
- level data to watershed
- based percent crop areas assume the distribution of the crops within a county is uniform and homogeneous. Distance between the treated fields and the water body is not taken into account.

• The PCA’s were generated using 1992 Census of Agriculture. However, recent changes in the agriculture sector from farm bill legislation may significantly

impact the distribution of crops throughout the country . Therefore, the approach assumes that year to - ye ar variation in cropping patterns are minimal, thus, have minimal impacts. The results of the modeling are presented in Table 2 and the pesticide
- specific parameters used to model sugarb eets are provided in Table 3. Appendix A provides the scenario specific inputs for PRZM and EXAMS. A brief description of the modeled site follows. The field used to grow sugarbeets is located in Polk County , Minnesota. The soil is a Bearden silty

clay loam; a fine
- silty , mixed, superactive, frigid Aeric Calciaquolls. The series consists of very

deep, somewhat poorl y drained, moderate to slowl y permeable soil that formed in calcareous silt loam and silty clay loam lacustrine sediments. These soils are o n glacial lake plains and have slopes of 0 to 3 percent. Mean annual precipitation is about 18 inches. The series is of large extent in eastern North Dakota and northwestern

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Minnesota. These soils are nearl y all cropped to small grains and row crops such as sugarbeets. The Bearden soil is characterized as a Hydrologic Group C soil. Table 2. PRZM/EXAMS Estimated Surface Water Concentrations ( μg/L) Agricultural Setting Estimated 1 in 10 Year Peak Estimated 1 in 10 Year Mean Sugarbeets Grown in Minne sota 0.42 0.005

Table 3. Triflusulfuron - methyl Specific PRZM/EXAMS Input Parameters

Input Parameter Input Value Data Source Hydroly sis pH 5: 3.7 day s pH 7: 32 day s pH 9: 36 day s MRID 4249859 Photolysis (soil and water) Stable MRIDs 42991424 ; 42991426 Aerobic Soil Metabolism (T 1/2 

### ) Bi
- Phasic: 6 day s, 170 day s MRID 42496860 Soil Adsorption Coefficient (L/Kg) 0.41 MRID 42496861 Solubility (μg/L) 110 EFED One
- Liner Henry ’s Law Coefficient (atm. m 3 

### /mole 5.9E
- 10 EFED Estimated Vapor Pressure (torr) 1.0E
- 7 EFED One
- Liner Application Rate (kg/ha) 0.035 Label: UpBeet Number of Application and Method 2; aerial Label: UpBeet

B. Ground Water Ground water EEC were modeled using SCI
- GROW, a screening groundwater regression model developed using data from prospective groundwater studies submitted to the OPP in support of registration. SCI
- GROW provides a reasonable high
- end estimate of ground water concentrations of pesticides within a defined set of fate and transport chara cteristics on soils that

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are known to be vulnerable to pesticide leaching (high sand content with shallow depth to groundwater). Table 4 provides the fate inputs and ground water concentration for the application rate and interval listed in Table 3. The estimated EEC is considered representative of both a peak and long
- term average concentration because of the inherent transport nature of ground water (generally slow movement from source of contamination both laterally and horizontally). Table 4. SCI - GR OW Estimated Ground Water Concentrations ( μg/L) Agricultural Setting Fate and Transport Inputs Concentration in Ground Water (μg/L) Aerobic Soil Metabolism (T 1/2 

### ) Soil Adsorption Coefficient (L/Kg) Sugarbeets 170 0.50 0.50


## REFERENCES Faust, S.D. and O.M. Aly. 1998. “Chemistry of Drinking Water Treatment.” 2 nd 

### Edition Revised, CRC Press LL C. July , 1998. Jones, R.D., S.W. Abel, W. Effland, R. Matzner, and R. Parker. 1998. “An Index Reservoir for Use in Assessing Drinking Water Exposures. Chapter IV in Proposed Methods for Basin
Scale Estimation of Pesticide Concentrations in Flowing W ater and Reservoirs for Tolerance Reassessment. , presented to the FIFRA Science Advisory Panel, July

29, 1998. http://www.epa.gov/pesticides/SAP/1998/in dex.htm

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## APPENDIX A

Table A - 1 PRZM 3.12 Climate and time parameters for Minnesota Sugarbeets. Minnesota Potatoes Parameter Value Source Quality Starting Date * January 1, 1948 Ending Date * December 31, 1983 Pan Evaporati on Factor (PFAC) 0.760 PIC good Snowmelt Factor (SFAC) 0.500 cm  K - 1 PIC good Minimum Depth of Evaporation (ANETD) 12.0 cm PIC good

* These values are in the RUN file rather than the INP file.

Table A - 2. Erosion and landscape parame ters for Minnesota Sugarbeets. Minnesota Potatoes Parameter Value Source Quality USLE K Factor (USLEK) 0.28 tons EI - 1* PIC good USLE LS Factor (USLELS) 0.12 PIC fair USLE P Factor (USLEP) 0.50 ** fair Field Area (AFIELD) 1 72.8 ha Index Reservoir good NRCS Hyetograph (IREG) 3 good Slope (SLP) 3.0% Official Soil Description*** fair Hydraulic Length (HL) 464 m Index Reservoir good * EI = 100 ft
- tons * in/ acre*hr ** P Factor represent compromise for 1 year of conventional tillage and two years of no till. *** OSD located at http://www.statlab.iastate.edu/soild/osd.

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Table A - 3. PRZM 3.1 crop parameters for Minnesota Sugarbeets. Minnesota Potatoes Parameter Value Source Quality Initial Cro p (INICRP) 1 PIC good Initial Surface Condition (ISCOND) 3 PIC fair Number of Different Crops (NDC) 1 ** fair
- good Number of Cropping Periods (NCPDS) 36 Standard Maximum rainfall interception storage of crop (CINTCP) 0.10 PIC fai r Maximum Active Root Depth (AMXDR) 20 cm PIC fair Maximum Canopy Coverage (COVMAX) 80 PIC fair Soil Surface Condition After Harvest (ICNAH) 3 PIC fair Date of Crop Emergence (EMD, EMM, IYREM) 05/16 fair
- good Date of Crop Matur ity (MAD, MAM, IYRMAT) 10/06 fair
- good Date of Crop Harvest (HAD, HAM,IYRHAR) 10/16 fair
- good Maximum Dry Weight (WFMAX) 0.0 PIC fair SCS Curve Number (CN) 82
- 91 PIC fair Manning’s N Value (MNGN) 0.020 PRZM Manual good USLE C Factor (USLEC) 0.18
- 0.43 PIC fair ** P Factor represent compromise for 1 year of conventional tillage and two years of no till.

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Table A - 4. PRZM 3.1 soil parameters for Bearden silty clay used for sugarbeets in Polk County, Minnesota.

Parameter Value Source Quality Total Soil Depth (CORED) 100 cm PIC good Number of Horizons (NHORIZ) 4 PIC good

First, Second, Third, and Fourth Soil Horizons (HORIZN = 1, 2, 3, 4) Horizon Thickness (THKNS) 10 cm (HORIZN = 1) 08 cm (HORIZN = 2 ) 54 cm (HORIZN = 3) 28 cm (HORIZN = 4) PIC good
Bulk Density (BD) 1.40 g  cm- 3 (HORIZN = 1, 2) 1.50 g  cm- 3 (HORIZN = 3) 1.80 g  cm- 3 (HORIZN = 4) PIC good Initial Water Content (THETO) 0.377 cm3

- H 2 O  cm 3

- soil (HORIZN = 1, 2) 0.292 cm3

- H 2 O  cm 3

- soil (HORIZN = 3) 0.285 cm3

- H 2 O  cm 3

- soil (HORIZN = 4) PIC good

Com partment Thickness (DPN) 0.1 cm (HORIZN = 1) 1.0 cm (HORIZN = 2) 2.0 cm (HORIZN = 3, 4) standard Field Capacity (THEFC) 0.377 cm3

- H 2 O  cm 3

- soil (HORIZN = 1, 2) 0.2292cm3

- H 2 O  c m 3

- soil (HORIZN = 3) 0.285 cm3

- H 2 O  cm 3

- soil (HORIZN = 4) PIC good

Wilting Point 0.207 cm3

- H 2 O  cm 3

- soil (HORIZN = 1, 2) 0.132 cm3

- H 2 O  cm 3

- soil (HORIZN = 3) 0.125 cm3

- H 2 O  cm 3

- soil (HORIZN = 4) PIC good

Organic Carbon Content 1.16% (HORIZN = 1, 2, 3) 0.174% (HORIZN = 4) PIC good

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 Table A - 5. PRZM 3.1 model state flags for modeled scenario.

Parameter Value Pan Factor Flag (IPEIND) 0 Foliar Application Model Flag (CAM) 2 Bulk Density Flag (BDFLAG) 0 Water Content Flag (THFLAG) 0 Kd Flag (KDFLAG) 0 Drainage model flag (HSWZT) 0 Method of characteristics flag (MOC) 0 Irrigation Flag (IRFLAG) 0 Soil Temperature Flag (ITFLAG) 0 Thermal Conductivity Flag (IDFLAG) 0 Biodegradation Flag (BIOFLAG) 0 Erosion Calcu lation Flag (ERFLAG) 4

Table A - 6. EXAMS II geometry for Index Reservoir. Littoral Benthic Source Area (AREA) 52,609 m 2 52,609 m 2 Jones et al., 1998 Depth (DEPTH) 2.74 m 0.05 m Jones et al., 1998 Volume (VOL) 144,000 m3 2630 m3 

### Jones et al., 1998 Length (LENG) 640 m 640 m estimated from map Width (WIDTH) 82.2 m 82.2 m estimated from map Stream Flow (STFLO) Minnesota

Reservoir 12.25 m3  h - 1 0 m3  h - 1 see guidance† †Guidance for Use of the Index Reservoir in Drinking Water Exposure Assessments, Jones, et al. November 16, 1999.

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 Table A - 7. EXAMS II dispersive transport parameters between benthic and littoral layers in the Index Reservoir. Parameter Path 1 * Source Turbulent Cross
- section (XSTUR) 52609 m 2 Burns, 1997 Characteristic Length (CHARL) 1.395 m Burns, 1997 Dispersion Coefficient for Eddy Diffusivity (DSP) ** 3.0 x 10 - 5 standard pond

* JTURB(1) = 1, ITURB(1) = 2; ** each monthly parameter set to this value.

Table A - 8. EXAMS I I sediment properties for the Index Reservoir.

Parameter Littoral Benthic Source Suspended Sediment (SUSED) 30 mg L - 1 standard pond Bulk Density (BULKD) 1.85 g cm- 3 standard pond Per cent Water in Benthic Sediments (PCTWA) 137% stand ard pond Fraction of Organic Matter (FROC) 0.04 0.04 standard pond

Table A - 9. EXAMS II external environmental and location parameters for the Index Reservoir. Parameter Value Source Precipitation (RAIN) 0 mm

 mo nth - 1 Atmospheric Turbulence (ATURB) 2.00 km standard pond Evaporation Rate (EVAP) 0 mm

 mo nth - 1 Wind Speed (WIND) 1 m  sec - 1 standard pond Air Mass Type (AMASS) Rural (R) Elevation (ELEV) 54.9 m USGS map Latitude (LAT) 39.12 o N USGS map Longitude (L ONG) 90.05 o W USGS map

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Table A - 10. EXAMS II biological characterization parameters for the Index Reservoir.

Parameter Limnic Benthic Source Bacterial Plankton Population Density (BACPL) 1 cfu  cm- 3 see text Benthic Bacteria Population Density (BNBAC) 37 cfu  (100 g) - 1 see text Bacterial Plankton Biomass (PLMAS) 0.40 mg  L - 1 standard pond Benthic Bacteria Biomass (BNMAS) 6.0x10 - 3 g  m- 2 standard pond

Table A - 11. EXAMS water quality parameters for the Index Reservoi r.

Parameter Value Source Optical path length distribution factor (DFAC) 1.19 Standard pond Dissolved organic carbon (DOC) 5 mg  L - 1 standard pond chlorophylls and pheophytins (CHL) 5x10 - 3 mg  L - 1 standard pond pH (PH) 7 standard pond pOH (POH) 7 standard pond

Table A - 12. EXAMS mean monthly water tem peratures (TCEL) for the Index Reservoir. Month Tem

perature (Celsius) January 0 February 1.09 March 6.26 April 13.21 May 18.61 June 23.73 July 26.09 August 25.04 September 20.91 October 14.5 November 7.04 December 0.99