1 UNITED STA

TES ENVIRONMENTA L PROTECTION A GENCY WA SHINGTON D.C., 20460 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES

MEMORANDUM Date: 8 / 28 /08 SUBJECT: Drinking Water Exposure Assessment for the Section 3 New Use Registration

of Su lfentrazone on Head/Stem Brassica Subgroup 5A, Leafy Greens Subgroup 5B, Melon Subgroup 9A, Fruiting Vegetable Group 8, Okra, Succulent Pea, Strawberry and Tuberous/Corm Vegetable Subgroup 1C. PC Code No.129081; DP Barcode: D349 322. TO: Daniel Rosenbl att, Risk Manager

Registration Division (7504P) George Kramer, Senior Chemist Dana Vogel , Chief Registration Action Branch 1 Health Effects Division (7509P) FROM: Michael R. Barrett, Chemist

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

Environmental Risk Branch V Environmental Fate and Effects Division (7507 P ) The previous assessment for the multiple uses of Sulfentrazone (D284975, D274982, D285501, D285504, D285739, D256211, D285274 , D284711 and D274569 ; included in this review was a drinking water assessment ) can be used in place of a new assessment for the currently proposed multiple uses of SPARTAN 4F (39.6% AI) and SPARTAN 75DF (75% AI). Application rates (0.1875 to 0.375 lbs ai /A per season) are the same as for previously assessed uses and risks should be similar. Sulfentrazone appears to be persistent and mobile, and has a strong potential to leach into groundwater (this conclusion is reinforced b y completed or nearl y comple ted small

- scale2

prospective ground

- water monitoring studies 1 ) and move offsite to surface water. The following conclusions from the above mentioned drinking water assessment s are still appropriate with the addition of the newl y requested uses on various ve getable crops: Tier I Estimated Drinking Water Concentrations (EDWCs) for sulfentrazone and its major degradate (3

- carboxy lic acid sulfentrazone) were calculated using FIRST (surface water) and SCIGROW (ground water) for use in the human health risk asses sment. EFED believes that the Tier I models used for these crops provide a reasonable worst case scenario and provide estimates suitable for screening purposes. For surface water, the acute (peak) sulfentrazone value is 32.0 ppb and the annual average val ue ranges from 0.5 ppb in alkaline or neutral waters (most common) to 5.1 ppb in acidic waters. The groundwater screening sulfentrazone concentration is 15.7 ppb. For 3

- carboxy lic acid sulfentrazone, the acute peak is 3.8 ppb and the annual average is 2. 7 ppb. For 3

- carbox yl ic acid sulfentrazone in groundwater, the concentration is 10.3 ppb.

- Source: DP Barcode: D284975, “Tier I Estimated Environmental Concentrations of Sulfentrazone and Degradate 3

- Carboxylic Acid Sulfentrazone for Use in the Human Health Risk Assessment”, review document dated 4/17/2003. See also DP Barcode 284975 et al., “EFED Section 3 and IR

- 4 Registration Chapter for Sulfentrazone...”, review document dated 6/16/2003

1 Note that even at sites where sulfentrazone / 3

- carboxylic acid sulfen trazone did not leach all the way to ground water that the limited amount of net recharge of ground water during the course of the studies limited the amount of leaching. Further details on these studies and on other monitoring data for sulfentrazone resid ues are provided in the aforementioned risk assessment documents.3



### APPENDIX I: Tier I Drink ing Water Memorandum (taken from th e original electronic docum ent)

U. S. ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, DC 20460

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES April 17, 2003 DP Barcode: D284975 PC Code 129081 MEMORANDUM SUBJECT: Tier I Estima ted Environmental Concentrations of Sulfentrazone and

Degradate 3

- Carboxy lic Acid Sulfentrazone for Use in the Human Health Risk Assessment FROM: Ronald Parker, Senior Environmental Engineer, Ph.D.

Larry Liu, Environmental Scientist, Ph.D. Environmental Risk Branch V Environmental Fate and Effects Division (7507C) THROUGH: Mah T. Shamim, Ph.D., Chief

Environmental Risk Branch V Environmental Fate and Effects Division (7507C) TO: Joanne Miller, Product Manager

Registration Division and George Kram er

Health Effects Division Summary . This memo presents the Tier I Estimated Drinking Water Concentrations (EDWCs) for the herbicide Sulfentrazone and degradate 3

- carbox yl ic acid sulfentrazone. These estimates are calculated using FIRST (surface water) an d SCI GROW (ground water) for use in the human health risk assessment. EFED believes that the Tier I models used for these crops provide a reasonable worst case scenario and provide estimates suitable for screening purposes. For surface water , the acute ( peak) value is 32.0 ppb and the annual average value ranges from 0.5 ppb in alkaline or neutral waters (most common) to 5.1 ppb in acidic waters. The groundwater screening concentration is 15.7 ppb. For 3 - carboxylic acid sulfentrazone, the degradate of co ncern, the acute peak is 3.8 ppb and the annual average is 2.7 ppb. The4

groundwater concentration is 10.3 ppb. See results in Tables 2 and 3 below. These values generall y r epresent upper
- bound conservative estimates of the total residues concentrations tha t might be found in surface water and groundwater due to the use of Sulfentrazone on sugarcane, cabbage, potatoes, mint or horseradish. These crops were chosen for this assessment because the label permits use of the maximum application rate (0.375 pounds active ingredient per acre) and aerial application. Aerial application has the potential for most spray drift and is not compatible with incorporation which would reduce surface water concentration values. Additional refinements can be developed should the y b e needed by HED. Estimation of Drinking Water Concentrations Tier I Estimated Drinking Water Concentrations (EDWCs) for the herbicide Sulfentrazone and degradate 3

- carbox yl ic acid sulfentrazone were calculated using FIRST (surface water) and SCI GROW ( ground water) for use in the human health risk assessment. Descriptions of the FIRST and SCIGROW screening models are included at the end of this document. Modeling Approach for Parent Sulfentrazone: Sulfentrazone labels indicate that the worst case sce narios are for sugarcane, cabbage, potatoes, mint or horseradish. These crops were chosen for this assessment because the label permits use of the maximum application rate of 0.375 pounds active ingredient per acre and aerial application. Aerial applicati on has the potential for most spray drift and also is not compatible with incorporation of the pesticide into the soil which would reduce surface water concentration values. The assessment uses the default percent cropped area (PCA) of 0.87. L aboratory studies indicate that the main mechanism of degradation is photoly sis. The FI RST model assumes a fairl y cloud y reservoir and so photoly sis takes place only near the surface where exposure to sunlight is greatest. The photolysis half

- life is about 12 hours in acidic waters (pH5) and approximately one hour in the more common neutral (pH7) and alkaline (pH9) waters. Acidic waters where chronic concentrations would potentially be the highest are most commonly found in the northeastern part of the US. Modeling Ap

proach for Degradate 3 - Carboxylic Acid Sulfentrazone: The primary degradate of concern, 3

- carbox yl ic acid sulfentrazone, was also simulated using the screening models, FIRST and SCI GROW. Because there is no environmental fate data for this degradate, it i s assumed to be completel y m obile and persistent. This degradate reaches a maximum of 11% of the applied parent. I t is simulated by multiply ing the label application rate by 11% and setting the Koc to zero and the half

- life to stable. The FIRST results are shown in the output file in Table 2 below. In the SCIGROW modeling, the maximum concentration value exceeds the model limit (which is set at the application rate times 250.) The concentration is therefore set to this limit.(I n this case this is, 0.375 po unds per acre times 11% times 250.) This gives a value of 10.3 ppb. The total value of parent plus degradate is 15.7 plus 10.3 for a total of 26 ppb.5

Groundwater Monitoring for Parent and Degradate SCI GROW results presented are consistent with the fie ld monitoring study which shows a maximum three month average total parent plus degradate value of from13 to 20 ppb. Table 1. Summary of Input Param eters for Tier I Estimated Drinking Water Concentrations (EDWC’s)

Param eter Sulfentrazone Model SCIGR OW Label Application Rate (lb a.i./A) 0.375 Label Max. Seasonal Number of Applications 1 (sugarcane, cabbage, potatoes, mint or horseradish) Mean Aerobic Soil Metab. Half

- life (Days) 545

(MRIDs 41928203, 42932117) Median K OC 43 (MRID 41911604, 43 355903) Model FIRST Upper 90 th Percentile Aerobic Soil Metab.Half

- life (Days) 545 (MRID 41928203, 42932117) Lo west Non

- Sand K oc, (L/kg) 43 (MRID 41911604) Pesticide Wetted In? No Method of Application Aerial Solubility (ppm) 400 (Product Chemistry Su

bm issions) Aerob. Aquatic Metab Half

- life (Days) 1095 (2x Aerob. Aquatic Metab Half

- life) Hy droly sis, Half

- life: pH 7 (Days) Stable (MRID 41928202) Aq ueous Photolysis Half

- life: pH 5 (Days) 0.5 (MRID 43345424, 43588601) Aq ueous Photolysis Half

- l ife: pH 7

- 9 (Day s) 0.042 (MRID 43345424, 43588601) PCA (Sugarcane) 0.87

Background Information on FIRST Model: FIRST is a screening model designed to estimate the pesticide concentrations found in water for use in drinking water assessments. I t p rovides high

- end values on the concentrations that might be found in a small drinking water reservoir due to the use of pesticide. Like GENEEC, the model previously used for Tier I screening level, FIRST is a single

- event model (one run

- off6

event), but ca n account for spray drift from multiple applications. FIRST takes into consideration the so called Index Drinking Water Reservoir b y r epresenting a larger field and pond than the standard GENEEC scenario. The FI RST scenario includes a 427 acres field imm ediately adjacent to a 13 acres reservoir, 9 feet deep, with continuous flow (two turnovers per year). The pond receives a spray drift event from each application plus one runoff event. The runoff event moves a maximum of 8% of the applied pesticide int o the pond. This amount can be reduced due to degradation on field and the effect of binding to soil. Spray drift is equal to 6.4% of the applied concentration from the ground spray application and 16% for aerial applications. FIRST also makes adjustmen ts for the percent crop area. While FI RST assumes that the entire watershed would not be treated, the use of a PCA is still a screen because it represents the highest percentage of crop cover of an y l arge watershed in the US, and it assumes that the entire crop is being treated. Various other conservative assumptions of FIRST include the use of a small drinking water reservoir surrounded b y a runoff

- prone watershed, the use of the maximum use rate, no buffer zone, and a single large rainfall. Background I

nformation on SCIGROW: SCI GROW provides a groundwater screening exposure value to be used in determining the potential risk to human health from drinking water contaminated with the pesticide. Since the SCI GROW concentrations are likel y t o be approached in only a very small percentage of drinking water sources, i.e., highly vulnerable aquifers, it is not appropriate to use SCI GROW for national or regional exposure estimates. SCI GROW estimates likely groundwater concentrations if the pesticide is used at the maximum allowable rate in areas where groundwater is exceptionally vulnerable to contamination. I n most cases, a large majority of the use area will have groundwater that is less vulnerable to contamination than the areas used to derive the SCIGROW es timate.7

Table 2. FIRST Modeling Inputs and Results: FIRST Output File
RUN No. 1 FOR SULFENTRAZONE ON SUGARCANE * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL S OLUBIL APPL TYPE %CROPPED INCORP ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) AREA (IN)

-------------------------------------------------------------------- .375( .375) 1 1 43.0 400.0 AERIAL(16.0) 87.0 .0

FIE LD AND RESERVOIR HALFLIFE VALUES (DAYS)

-------------------------------------------------------------------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.

- EFF) (RESER.) (RESER.)

-------------------------------------------------------------------- 545.00 2 N/A .50

- 62.00 1090.00 58.66 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.0 AUG 1, 2001

---------------------------------- ---------------------------------- PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

--------------------------------------------------------------------

32.169 5.058

RUN No. 2 FOR SULFENTRAZONE ON SUGARCANE * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP ONE(MULT) INTERVAL Koc (PPM) (%DRIFT) AREA (IN)

-------------------------------------------------------------------- .375( .375) 1 1 43.0 400.0 AERIAL(16.0) 87.0 .0 FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

-------- ------------------------------------------------------------ METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.

- EFF) (RESER.) (RESER.)

----------------------------------------------- --------------------- 545.00 2 N/A .04

- 5.17 1090.00 5.14 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.0 AUG 1, 2001

-------------------------------------------------------------------- PEAK DAY ( ACUTE) ANNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

--------------------------------------------------------------------

31.548 .494 RUN No. 1 FOR 3

- carboxyli c acid ON SUGARCANE * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) AREA (I N)8

-------------------------------------------------------------------- .041( .041) 1 1 .0 400.0 GRANUL( .0) 87.0 .0 FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

------------------------------------------------------------- ------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.

- EFF) (RESER.) (RESER.)

-------------------------------------------------------------------- .00 2 N/ A .00

- .00 .00 .00 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.0 AUG 1, 2001

-------------------------------------------------------------------- PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

--------------------------------------------------------------------

3.765 2.700
Table 3. SCIGROW Modeling Input and Results SCIGROW VERSION 2.2: NOVEMBER 1, 2001 RUN No. 1 FOR SULFENTRAZONE ** INPUT VALUES **

-------------------------------------------------------- APP RATE APPS/ TOTAL/ S OIL AEROBIC SOIL METAB (LBS/AC) YEAR SEASON KOC HALFLIFE (DAYS)

-------------------------------------------------------- .375 1 .375 43.0 545.00 GROUND
- WATER SCREENING CONCENTRATION (IN UG/L

- PPB)

-------------------------------------------------------- 15.701670

--------------------------------------------------------9