### U. S. ENVIRONMENTAL PROTECTION AGENCY Washington, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES 

### PC Code: 123802 DP Code: 3 73599, 373601

March 2 , 2010

MEMORANDUM SUBJEC T : Drinking Water Assessment for Fomesafen U se on Pepper TO: Michael Walsh

Joanne Miller, PM 23 Registration Division (7505P) FROM: James Lin , Environmental Engineer

Environmental Risk Branch I Environmental Fate and Effects Division (7507P) APPROVED Anita Pease , Acting Branch Chief BY : Environmental Risk Branch I

Environmental Fate and Effects Division (7507P) 

## Summary
This assessment provides estimated drinking water concentrations (EDWC) of the herbicide fomesafen in surface water and in ground water in support of the human health risk assessment for assessing of new use on p epper (

### DP3 73599, 373601 )

. This drinking water exposure memo addresses the human exposure of fomesafen through ingestion of drinking water from the new proposed use. Based on the modeling analys is, the 1

- in

- 10 ye ar fomesafen concentration in surface

- source drinking water is not expected to exceed 25.53 μg/L for peak (acute) and 2.87 μg/Lfor annual average (non

- cancer chronic) exposures . The 30

- ye ar annual average concentration is not expected to exceed 1. 20 μg/L (cancer chronic)

. Therefore, the current EDWCs will not supersede the recommended drinking water values previously performed for this chemical (DP 322213 ) , 

### and the previous drinking water values should be used.2



## Estimated D rink

ing Water Concentrations (D P 322213) Food uses of fomesafen considered in the previous assessment are cotton and soy beans. Environmental fate data indicate fomesafen is very mobile and highly persistent in terrestrial and aquatic environments. Major routes of dissipation from the application site are expected to be runoff and leaching. These data suggest fomesafen occurrence in surface water and groundwater should be anticipated. The 1

- in

- 10 year fomesafen concentration in surface

- source drinking water is not expecte d to exceed 34.8 μg/L for peak and 13.1 μg/L for annual average exposures . The 30

- ye ar annual average concentration is not expected to exceed 6.5 μg/L . Although SCI

- GROW modeling predicts a fomesafen concentration in ground water of 11.2 μg/L, a prospective ground water monitoring study

for soy beans on a vulnerable North Carolina site reported maximum concentrations of fomesafen in ground water of 1 μg/L. EFED recommends using the ground water monitoring concentration of 1 μg/L as the benchmark concentration for fomesafen in ground water source drinking water because it represents actual use conditions of fomesafen on so yb eans on a vulnerable soil. 

## Label Use Info rmation Based on the proposed Reflex ® Herbicide label (EPA Reg. No. 100

- 993) , application rates and intervals for the new use of fomesafen on p epper vary based on geographical regions as shown as Table 1

. Table 1 Label Application Rates and Intervals for Fomesafen Use on P epper 1 

### Region States in Region App Rate (lbs/A) Application Interval
1 AL, AR, FL, GA, LA, MS, MO 2 

### , NC, OK2 

### , SC, TN,

TX2 

### 0. 37 5 1 year
2 DC, DE, IL2 

### , IN2 

### , KY, MD,

OH2 

### , PA3 

### , WV, VA, 0. 37 5 2 year 3 CT, IA, ME, MA, M I3 

### , NH, NJ, NY, PA 3 

### , RI, WI, VT 0. 313 2 year 4 KS 2 

### , MI3 

### , MN2 

### , ND 3 

### , NE2



### SD 3 

### , WI2 

### 0.25 2 year 5 ND 3 

### , MN 3 

### , SD 3 

### 0.1875 2 year 1 

### REFLEX 2.5 Gallon (EPA Reg. No. 100

- 993) 2

### Does not include entire state 3 

### Portions of state are in multiple regions Among the five regions, region 1 allows the highest application amount as it has a higher rate and a shorter application interval. The use on pepper is specified as a preplant non

incorporated pre

- emergence broadcast application.3



## Environmental Fate Summary Major routes of fomesafen dissipation are leaching, runoff, and microbial degradation. Because fomesafen is persistent and mobile in soil, it is expected to move from the application site into groundwater and surface water. Additionally, off

- site movement of fomesafen is expected through spray drift from aerial and ground spray . The high persistence of fomesafen is expected to contribute to year-to

- ye ar accumulation in terrestrial and aquatic environments. Fomesafen is stable to abiotic hydrolys is. It undergoes slow photodegradation in water (t 1/2

### = 49 to 289 days). Fomesafen is persistent (t 1/2

### =9 to 99 weeks) in aerobic soil and aquatic environments. However, it degrades rapidly (t 1/2

### < 20 days) in anaerobic environments. The major degradation product of fomesafen is 5

- (2

- chloro -  ,  , - trifluoro

-p -tolyloxy)

-N

-methylsulphonyl

-panthranilamide (fomesafen amine). A minor degradation product is 5

- (2

- chloro

-  ,  , -trifluoro

-p -tolyloxy) anthranilic acid (fomesafen amino acid). Neither degradate has been identified as a toxicological concern. Fomesafen is expected to be very mobile in soil. Simple partitioning coefficients range from 0.51 in loamy

coarse sand to 2.45 in sandy clay loam soil. Regression analys is indicates fomesafen sorption is not dependent on soil organic matter content. Aged soil column leaching studies indicate degradation products of fomesafen are not mobile in soils; less than 0.06% of applied radioactivity was detected in the leachate samples. Field dissipation studies in NC, IL, MS, AR, AL, TX, LA, SD, MN, K Y, IA and MO indicate fomesafen is moderately persistent to persistent (t 1/2

### = 50 to 150 days ) in surface soils under actual use conditions. Fomesafen was detected at depths up to 30 inches in the soil profile. Fomesafen amine was the only degradation product identified in field dissipation studies. Prospective ground water monitoring in NC indicates fomesafen moved through the soil profile into medium and deep ground water. Fomesafen has a low potential for bioaccumulation in fish tissues. Bioaccumulation factors for fomesafen were 0.7 for whole fish, 0.2 for edible tissues, and 5.2 for nonedible tissue. Bioaccumulated residues were depurated during a 14

- day depuration period.



## Surface Water Assessment The new proposed pepper use of fomesafen was modeled in the Florida scenario in PRZM/EXAMS using index reservoir (IR) scenarios with the default percent crop area (PCA) adjustment factor. The estimated drinking water concentrations in surface water were derived from Tier II PRZM (Pesticide Root Zone Model; Version 3.12.2, May 12, 2005) and EXAMS (Exposure Analys is Modeling System; Version 2.98.04.06, Apr. 25, 2005). PRZM simulate s pesticide transport as a result of runoff, erosion, and off

-target spray drift from an agricultural field. EXAMS estimates environmental fate and transport of pesticides in surface water. Additionally, a graphical interface shell, PE5.pl (dated4



### 7/27/2007), was employed to facilitate the input of use

- specific information in the PRZM input and the EXAMS chemical files (Table 2 ). Linked crop

- specific scenario and meteorological data were used to estimate exposure as a result of fomesafen use on pepper . Simulations were done using the index reservoir in EXAMS, which is a surrogate for a permanent surface water drinking water environment. Weather and agricultural practices were simulated over 30 years to estimate the 1

- in

- 10 ye ar exceedance probability at the site.

Table 2 . Input Parameters for PRZM
-EXAMS Modeling of Fomesafen on Pepper.

Parameter Value Reference Selected Physical/Chemical Properties Molecular Weight (g/mol) 420 EPA 2020220 Water Solubility (mg/L) 1200 (pH 7, 20 o C) MRID 45048207 Vapor pressure (25  C) <7.5 x10

- 7 mmHg (50 o C) HSDB Henry's Law Constant 7.5 x 10

- 13 atm m3 /mol (estimated) HSDB 

### Persistence Hydrolysis t 1/2 @ pH 7 stable Acc No. 071059 Photolysis t 1/2 in Water 289 days in pH 7 buffer solution MRID 40451101 Soil metabolism Aerobic t 1/2 24

-25  C (days) loamy sand (Frensham) 187. 6 and 630 sandy loam/loam (18 acres) 57 and 693 Calcareous silty clay loam (Gore) 349.3 and 527.1 silty clay loam (Wisborough green) 207 upper 90 th percentile of mean= 428.8 days mean=387.84 days and SD=242.90 days Acc No. 071059 and 00135660

Aquatic metabolism Aerobic t 1/2 (days) loamy sand (Frensham) 139.3 sandy loam/loam (18 acres) 60.9 Calcareous silty clay loam (Gore) 92.4 silty clay loam (Wisborough green) 115.5 upper 90 th percentile of mean= 115.71 days mean=102.02 days and SD=33.44 days Acc No. 72158

Aquatic metabolism Anaerobic t 1/2 Silt loam soil from Illinois half

- life in the total system: 4.0 days Loam soil from Mississippi half

- life in the total system: 3.6 days Sand soil from North Carolina half

- life in the total system: 5.1 days MRID 478653085 

### Parameter Value Reference

upper 90 th percentil e of mean= 5.08 days mean= 4.233 days and SD= 0.777 days 

### Mobility/Adsorption
-Desorption
Mobility

- Adsorption/Desorption Aged (Guideline 163

- 1) Blount silt loam
- 0.68. This value represents the lowest non

- sand Kd . The Koc partition model was not used because there was no correlation between SOC and Kf . Acc No 259413

Application Parameters Application Efficiency Aerial (0.95); Ground (0.99) Input Guidance Document Spray Drift Amount Aerial (0.15); Ground (0.064)



### The application rate used is the recommended maximum label application rate. The standard scenarios were developed b y EFED to represent nationwide crop coverage and high

- end vulnerability sites to runoff and erosion and, therefore, pesticide transport. The application information used in the PRZM/EXAMS modeling is provided in Table 3

.
Table 3 . Standard EFED modeling scenario for fomesafen pepper use PRZM Crop Scenario Application Date dd
- mm Maximum Single Application Rate (lb ai/A) Pepper Florida Pepper 2 0

- 0 8 0.375 / year 

### The modeling results of estimated drinking water concentrations (EDWC) are listed in Table s 4 (before PCA adjustment) and 5 (after PCA adjustment). The default PCA value of 0 .87 is adjusted for pepper use . The complete PE5 outputs are included in the Appendix

.
Table 4 . Estimated Drinking Water Concentrations before Percent Crop Area (PCA) Adjustment

PRZM Crop Scenario 1 in 10 year annual peak concentration (acute) 1 in 10 year annual

mean concentration (non

- cancer chronic) 3 0 year annual mean

concentration (cancer chronic). Pepper (unit: μg/L; ppb) Florida Pepper: aerial 29.349 3.294 1.376 Florida Pepper: ground 29.253 3.257 1.2596



### Table 5 . Estimated Drinking Water Concentrations after Percent Crop Area (PCA) Adjustment PRZM

Crop Scenario 1 in 10 year annual peak concentrati on (acute) 1 in 10 year annual

mean concentration (non

- cancer chronic) 30 year annual mean

concentration (cancer chronic). Pepper (unit: μg/L; ppb) Florida Pepper: aerial 25.534 2.866 1.197 Florida Pepper: ground 25.450 2.834 1.095 

### The aerial application has the higher estimated drinking water concentrations. The 1 in 10 year annual peak concentration of 25.53 μg/L should be used to assess acute concerns ; the 1 in 10 year annual mean concentration of 2.87 μg/L should be used for non- cancer chronic assessment; and the 3 0 year annual mean concentration of 1.20 μg/L should be used for assessing cancer chronic concerns .7 

### Appendix stored as frflpdwa.out Chemical: Fomesafen PRZM environment: FLp eppersSTD.txt modified Thuday, 24 May 2007 at 09:44:22 EXAMS environment: ir298.exv modified Tueday, 26 August 2008 at 05:14:08 Metfile: w12844.dvf modified Tueday, 26 August 2008 at 05:14:22 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Da y 90 Day Yearly 1961 6.432 6.115 4.997 3.413 2.653 0.7136 1962 5.081 4.832 3.954 2.807 2.204 0.6318 1963 9.879 9.391 7.947 5.392 4.171 1.154 1964 29.92 28.45 23.31 15.58 12.06 3.325 1965 2.658 2.527 2.06 1.383 1.069 0.4647 1966 14.91 14.19 12.38 8.47 2 6.569 1.787 1967 2.639 2.514 2.16 1.513 1.177 0.4084 1968 7.881 7.602 6.291 4.719 3.734 1.029 1969 6.786 6.458 5.457 3.819 2.988 0.8661 1970 13.64 12.97 10.58 7.066 5.467 1.516 1971 7.031 6.824 5.768 3.987 3.125 0.9179 1972 5.502 5.285 4.378 2.942 2.267 0.6455 1973 3.152 3.004 2.813 2.005 1.559 0.4464 1974 5.754 5.482 4.548 3.126 2.435 0.6757 1975 4.053 3.865 3.432 2.365 1.833 0.5246 1976 3.421 3.258 2.926 2.313 1.836 0.5224 1977 7.529 7.16 6.392 4.376 3.41 0.9471 1978 3.662 3.509 2.916 2.239 1.79 0.535 1979 6.78 6.452 5.369 3.644 2.962 0.8417 1980 39.62 37.68 31.34 21.05 16.25 4.405 1981 24.21 23.02 19.72 13.37 10.33 3.016 1982 3.988 3.793 3.122 2.147 1.66 0.5832 1983 4.413 4.194 3.529 2.462 1.919 0.5384 1984 18.6 17.9 15.49 10.56 8.175 2.219 1985 7.165 6.874 5.716 3.884 3.058 0.9352 1986 5.706 5.425 4.619 3.314 2.575 0.7341 1987 3.081 2.962 2.496 2.077 1.655 0.483 1988 81.19 77.2 62.89 41.6 31.98 8.55 1989 8.825 8.388 7.167 4.949 3.833 1.411 1990 3.137 2.982 2.622 1.954 1.526 0.459 8
Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 81.19 77.2 62.89 41.6 31.98 8.55 0.0645161290322581 39.62 37.68 31.34 21.05 16.25 4.405 0.0967741935483871 29.92 28.45 23.31 15.58 12.06 3.325 0.12903225806 4516 24.21 23.02 19.72 13.37 10.33 3.016 0.161290322580645 18.6 17.9 15.49 10.56 8.175 2.219 0.193548387096774 14.91 14.19 12.38 8.472 6.569 1.787 0.225806451612903 13.64 12.97 10.58 7.066 5.467 1.516 0.258064516129032 9.879 9.391 7.947 5.392 4.171 1.4 11 0.290322580645161 8.825 8.388 7.167 4.949 3.833 1.1548

0.32258064516129 7.881 7.602 6.392 4.719 3.734 1.029 0.354838709677419 7.529 7.16 6.291 4.376 3.41 0.9471 0.387096774193548 7.165 6.874 5.768 3.987 3.125 0.9352 0.419354838709677 7.031 6.824 5.7 16 3.884 3.058 0.9179 0.451612903225806 6.786 6.458 5.457 3.819 2.988 0.8661 0.483870967741936 6.78 6.452 5.369 3.644 2.962 0.8417 0.516129032258065 6.432 6.115 4.997 3.413 2.653 0.7341 0.548387096774194 5.754 5.482 4.619 3.314 2.575 0.7136 0.58064516 1290323 5.706 5.425 4.548 3.126 2.435 0.6757 0.612903225806452 5.502 5.285 4.378 2.942 2.267 0.6455 0.645161290322581 5.081 4.832 3.954 2.807 2.204 0.6318 0.67741935483871 4.413 4.194 3.529 2.462 1.919 0.5832 0.709677419354839 4.053 3.865 3.432 2.365 1 .836 0.5384 0.741935483870968 3.988 3.793 3.122 2.313 1.833 0.535 0.774193548387097 3.662 3.509 2.926 2.239 1.79 0.5246 0.806451612903226 3.421 3.258 2.916 2.147 1.66 0.5224 0.838709677419355 3.152 3.004 2.813 2.077 1.655 0.483 0.870967741935484 3.137 2.982 2.622 2.005 1.559 0.4647 0.903225806451613 3.081 2.962 2.496 1.954 1.526 0.4598 0.935483870967742 2.658 2.527 2.16 1.513 1.177 0.4464 0.967741935483871 2.639 2.514 2.06 1.383 1.069 0.4084
0.1 29.349 27.907 22.951 15.359 11.887 3.2941 Average of yearly averages: 1.37622 Inputs generated by pe5.pl

- Novemeber 2006
Data used for this run: Output File: frflpdwa Metfile: w12844.dvf PRZM scenario: FLpeppersSTD.txt EXAMS environment file: ir298.exv Chemical Name: Fomesafen Description Va riable Name Value Units Comments Molecular weight mwt 420 g/mol Henry's Law Const. henry 7.5e

- 13 atm
- m^3/mol Vapor Pressure vapr 7.5e

- 7 torr Solubility sol 1200 mg/L Kd Kd 0.68 mg/L Koc Koc mg/L Photolysis half

- life kdp 289 days Half

- life Aerobic Aquatic Metabolism kbacw 115.71 days Halfife Anaerobic Aquatic Metabolism kbacs 5.08 days Halfife Aerobic Soil Metabolism asm 428.8 days Halfife Hydrolysis: pH 7 0 days Half

- life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate : TAPP 0.42 kg/ha Application Efficiency: APPEFF 0.95 fraction Spray Drift DRFT 0.16 fraction of application rate applied to pond Application Date Date 20

- 08 dd/mm or dd/mmm or dd

- mm or dd

- mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT9 FEXTRC 0.5 Flag for Index Res. Run IR Reservoir Flag for runoff calc. RUNOFF total none, monthly or total(average of entire run)
stored as frflpdwg.out Chemical: Fomesafen PRZM environment: FLpeppersSTD.txt modified Thuday, 24 May 2007 at 09:44:22 EXAMS environment: ir298.exv modified Tueday, 26 August 2008 at 05:14:08 Metfile: w12844.dvf modified Tueday, 26 August 2008 at 05:14:22 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 5.206 4.95 4.048 2.757 2.141 0.5767 1962 4.01 3.813 3.113 2.123 1.671 0.4831 1963 8.759 8.326 7.062 4.806 3.72 1.026 1964 29.87 28.4 23.27 15.56 12.02 3.29 1965 1.465 1.402 1.173 0.812 0.6343 0.3092 1966 14.19 13.5 11.74 8.052 6.237 1.685 1967 1.214 1.155 1.024 0.7555 0.5924 0.2473 19 68 7.049 6.786 5.623 4.139 3.262 0.8949 1969 5.61 5.339 4.549 3.19 2.483 0.7249 1970 12.71 12.09 9.86 6.592 5.083 1.404 1971 6.009 5.858 4.961 3.376 2.631 0.781 1972 4.199 4.048 3.374 2.261 1.744 0.5008 1973 2.09 1.994 1.74 1.275 0.9979 0.2902 1974 4 .538 4.326 3.609 2.454 1.913 0.5295 1975 2.716 2.584 2.352 1.648 1.28 0.3702 1976 2.507 2.388 2.034 1.59 1.279 0.3665 1977 6.35 6.06 5.5 3.761 2.924 0.8097 1978 2.764 2.631 2.196 1.516 1.235 0.3806 1979 5.959 5.67 4.735 3.182 2.46 0.7012 1980 39.87 3 7.92 31.56 21.21 16.37 4.415 1981 23.7 22.54 19.36 13.14 10.15 2.967 1982 2.659 2.529 2.093 1.425 1.105 0.4327 1983 3.214 3.054 2.577 1.755 1.375 0.3859 1984 17.92 17.19 14.94 10.21 7.902 2.135 1985 6.149 5.91 4.933 3.315 2.562 0.7998 1986 4.371 4.15 6 3.593 2.644 2.061 0.5915 1987 2.196 2.122 1.808 1.359 1.104 0.3299 1988 83.04 78.96 64.32 42.54 32.71 8.738 1989 7.699 7.318 6.283 4.349 3.373 1.297 1990 1.906 1.812 1.543 1.227 0.969 0.3057
Sorted results Prob. Peak 96 hr 21 Day 60 D ay 90 Day Yearly 0.032258064516129 83.04 78.96 64.32 42.54 32.71 8.738 0.0645161290322581 39.87 37.92 31.56 21.21 16.37 4.415 0.0967741935483871 29.87 28.4 23.27 15.56 12.02 3.29 0.129032258064516 23.7 22.54 19.36 13.14 10.15 2.967 0.161290322580645 1 7.92 17.19 14.94 10.21 7.902 2.135 0.193548387096774 14.19 13.5 11.74 8.052 6.237 1.68510

0.225806451612903 12.71 12.09 9.86 6.592 5.083 1.404 0.258064516129032 8.759 8.326 7.062 4.806 3.72 1.297 0.290322580645161 7.699 7.318 6.283 4.349 3.373 1.026 0.3 2258064516129 7.049 6.786 5.623 4.139 3.262 0.8949 0.354838709677419 6.35 6.06 5.5 3.761 2.924 0.8097 0.387096774193548 6.149 5.91 4.961 3.376 2.631 0.7998 0.419354838709677 6.009 5.858 4.933 3.315 2.562 0.781 0.451612903225806 5.959 5.67 4.735 3.19 2. 483 0.7249 0.483870967741936 5.61 5.339 4.549 3.182 2.46 0.7012 0.516129032258065 5.206 4.95 4.048 2.757 2.141 0.5915 0.548387096774194 4.538 4.326 3.609 2.644 2.061 0.5767 0.580645161290323 4.371 4.156 3.593 2.454 1.913 0.5295 0.612903225806452 4.199 4.048 3.374 2.261 1.744 0.5008 0.645161290322581 4.01 3.813 3.113 2.123 1.671 0.4831 0.67741935483871 3.214 3.054 2.577 1.755 1.375 0.4327 0.709677419354839 2.764 2.631 2.352 1.648 1.28 0.3859 0.741935483870968 2.716 2.584 2.196 1.59 1.279 0.3806 0.774193548387097 2.659 2.529 2.093 1.516 1.235 0.3702 0.806451612903226 2.507 2.388 2.034 1.425 1.105 0.3665 0.838709677419355 2.196 2.122 1.808 1.359 1.104 0.3299 0.870967741935484 2.09 1.994 1.74 1.275 0.9979 0.3092 0.903225806451613 1.906 1.812 1 .543 1.227 0.969 0.3057 0.935483870967742 1.465 1.402 1.173 0.812 0.6343 0.2902 0.967741935483871 1.214 1.155 1.024 0.7555 0.5924 0.2473
0.1 29.253 27.814 22.879 15.318 11.833 3.2577 Average of yearly averages: 1.25894333333333 Inputs gen erated by pe5.pl

- Novemeber 2006
Data used for this run: Output File: frflpdwg Metfile: w12844.dvf PRZM scenario: FLpeppersSTD.txt EXAMS environment file: ir298.exv Chemical Name: Fomesafen Description Variable Name Value Units Comments Molecular weight mwt 420 g/mol Henry's Law Const. henry 7.5e

- 13 atm
- m^3/mol Vapor Pressure vapr 7.5e

- 7 torr Solubility sol 1200 mg/L Kd Kd 0.68 mg/L Koc Koc mg/L Photolysis half

- life kdp 289 days Half

- life Aerobic Aquatic Metabolism kbacw 115.71 days Halfife Anaerobic Aqu atic Metabolism kbacs 5.08 days Halfife Aerobic Soil Metabolism asm 428.8 days Halfife Hydrolysis: pH 7 0 days Half

- life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 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 20

- 08 dd/mm or dd/mmm or dd

- mm or dd

- mmm Record 17: FILTRA11 IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Reservoi r Flag for runoff calc. RUNOFF total none, monthly or total(average of entire run)