# 1 OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

## UNITED ST **AT ES ENVIRONMENT**  **AL PROTECTION A** **GENCY**

WA SHINGTON, D.C. 20460



# PC Code: 128847 Decision #: 447590 DP Barcode: 395784 **Date:** December 20 , 2011

**MEMORANDUM SUBJECT:**  Revised drinking w ater e xposure a ssessment to establish a tolerance of parent

difenoconazole and its major CGA

- 205375 (M1) metabolite on fruiting vegetables group 8

- 10, low growing berry s ubgroup, 13

- 07G except cranberry , citrus fruit group 10

- 10, pome fruit group , (subgroup 11) , and tuberous and c orm vegetable ( subgroup 1C )

. **TO:** Sidney Jackson, Risk Manager Reviewer Barbara Madden, Risk Manager Registration Division (7505 P ) **FROM:** Faruque Khan, Ph.D., Senior Fate Scientist

Environmental Risk Branch I Environmental Fate and Effects Division (7507P) **APPROVED BY**  **:** Nancy

Andrews , Ph.D., Branch Chief, Sujatha Sankula, Ph.D. Lead Biologist Environmental Risk Branch I Environmental Fate and Effects Division (7507P) This memorandum provides a revised drinking water assessment based on recent recommendation from the Health Effects Division’s Residues of Concern Knowledgebase Sub

committee (ROCKS). The ROCKS recommended to include parent difenoconazole and its major CGA

- 205375 (M1) metabolite for drinking water assessment to establish tolerances for difenoconazole in support of human health risk assessment (US EPA, 2011, D391350)

. This revised drinking water assessment was performed using total residue method (i.e. parent plus CGA 205375) on the requested crops , f ruiting vegetables group 8

- 10, low growing berry sub group ( 13

- 07G) except cranberry , citrus fruit group ( 10

- 10 ) , pome fruit group (subgroup 11) and tuberous and c orm vegetable ( subgroup 1C)

.

# 2

Difenoconazole can be applied as a foliar spray through ground or aerial application on various crops according to the Inspire TM 

# (EPA Reg. No. 100

- 1262) label. Table 1 below provides information of previous actions related to drinking water assessments. Revised drinking water assessment was performed onl y for the scenarios with highest EDWCs for crops listed in Table 1. Table 2 provides information related to modeled scenarios for this assessment. The modeling approach for surface water and ground water are consistent with the earlier approach except the half

- life values for b iotic degradation in the environment

. The percent of CGA

- 205375 formation during biotic metabolism in soil and aquatic environments was included into half

- life calculations (**Appendix A** ) and used in the revised modeling

. Since abiotic (i.e. hydrol ys is and aquatic photol ys is) degradation of difenoconazole is stable, no further half

- life estimation is required. The EDWCs are also based on the maximum proposed application rates ranging from 0.33 to 0.5 lbs/A for aerial application specified in the product label. The EDWCs for the human health risk assessment are presented in Table 2. For surface water, the EDWCs for the crops modeled in this assessment did not exceed the EDWCs for grape reported in the previous drinking water assessment (U.S. EPA 2009a; D 361398 ). The E stimated Drinking Water Co ncentrations (EDWCs) for grape scenario provided the highest exposure in surface water (U.S. EPA 2009; D361398). The reported values for acute , annual mean (chronic) concentration and the highest 30 year annual average concentrations were 15.8 μg/L, 10.4 μg/L , and 7.62 μg/L respectively

. Therefore, the current EDWCs for surface water do not supersede the drinking water concentrations previously estimated for this chemical. Estimated ground water concentration of 1. 30 x 10 - 2 

# μg/Lf or citrus is higher than th e previously

recommended concentration of 1. 28 x 10 - 2 

# μg/Lf or ornamentals (US EPA, 2007; D333319). Therefore, recommended EDWCs for ground water is 1.30x 10 - 2 

# μg/L and this concentration can be considered as both the acute and chronic values.
**Table 1. Li st of previous actions for drinking water assessment**  **DP B**  **arcode s**  **Date Title of Assessment**  333319 and 340041 June 19, 2007 Amended Di fenoconazole (Parent Onl y) Drinking Water Assessment in Support of New Use Registration Action for Fruiting Vegetables 1 

# , Tuberous, Corn 1 

# , Vegetables Subgroup, Pome Fruit, Ornamentals, and Sugar beets. 361398 May

28, 2009 Difenoconazole (Parent Only) Drinking Water Assessment in

Support of New Use Registration Action for Bulb Vegetables, Brassica (Cole) Leafy

Vegetables, Cucurbit Vegetables , Citrus Fruit 1 

# , Grapes, and Tree Nuts. 3 75778 and 380513 Dec 16, 2010 Drinking Water Exposure Assessment to Establish a Tolerance of parent difenoconazole on carrot, chickpeas, soy bean, stone fruits, and strawberry 1



# . 1 

# Scenarios with higher EDWCs were modeled in this revised assessment

# 3

**Table 2**  **. Estimated Drinking Water Concentrations (EDWCs) in Surface**  **W ater and**  **Ground Water R**  **esulting from A** **pplications of D**  **ifenoconazole Drinking Water**  **Source (m odel)**  **Use Scenario**  **(m odeled rate)**  **1**
**- in** 
**- 10 year acute**  **(** 

# μg/L **) 1** 
**- in** 
**- 10 year chronic** 

**(** 

# μg/L **) 30** 
**- year**  **average**

**(** 

# μg/L **)** Surface Water 1 

## (PRZM/EXAMS) Fruiting Vegetables :

PA Tomato STD FL Pepper STD ( 0.46 lbs ai/acre ) **10.31** 8.36 6.02

2.85 4.52

2.19
Citrus : FL Citrus STD (0. 5 lbs ai/acre) 8.01 3.30 2.63
Lo w growing berry FL Straw berry STD (0. 46 lbs ai/acre) 9.89 3.56 2.97
Pome Fruits : PA Apple STD ( 0. 33 lbs ai/acre) 7.08 3.99 3.01
Tuberous and c orm vegetable s ME Potato S TD (0. 46 lbs ai/acre) 10.25 **6.62 5.38** 
Groundwater (SCI

- GROW) For Citrus crops



## (4 app. X 0.125 lbs ai/acre) 1.30 x 10 - 2 

## 1.30 x 10 - 2 

## 1.30x 10 - 2 

## Bold text denotes maximum estimated EDWC values for this asse s sment

. All values were adjusted with PCA factor of 0.87. 

# The modeling results of various scenarios for EDWCs are listed in **Appendix B**  **.** Standard percent cropped areas (PCA) were used for all uses as estimates of the extent of watershed on which crops is grown (Effland et al. , 1999). The default agricultural PCA of 0.87 was used for the proposed uses because they are not confined to specific regions of the U.S

. Since there is no modification of input parameters for PRZM/EXAMS and SCI

- GROW models ex cept biotic degradation half

- li fe parameters, detailed description of models can be obtained from the previous assessment for grapes (U

. S

. EPA, 2009 a , D361398). Inputs for PRZM/EXAMS in **Table B** 
**- 1**  and for SCIGROW in **Table B** 
**- 2**  as well as examples output of PRZM/EXAMS and SCI GROW models were provided in the **Appendix B**  **. Tables**  **B**
**- 3**  provides pre - PCA and post

PCA adjusted EDWCs for difenoconazole. **Monitoring Data**
D i fenconazole is not included as one of the analy tes monitored in U.S. surface and groundwater under the USGS’s National Water Quality Assessment (NAWQA) program. **Drinking Water Exposure Modeling** Estimated drinking water concentrations (EDWCs) were generated using EFED’s standard suite of models. The proposed uses from the provided label were assessed.

# 4

**Models** Pesticide Root Zone Model (PRZM v3.12 .2, May 12, 2005 ) and Exposure Analysis Modeling S ys tem (EXAMS v2.98.04.06, April 25, 2005 ) are simulation models coupled with the input PE5.pl shell (PE5, PE Version 5.0, November 15, 2006) to generate EDWCs of difenoconazole residues that may occur in surface water used as drinking water. The PRZM model simulates pesticide movement and transformation on and across the agricultural field resulting from crop application s . The EXAMS model simulates pesticide loading via runoff, erosion, and spray

drif t assuming a standard watershed of 172.8 ha that drains into an adjacent standard drinking water index reservoir of 5.26 ha, an average depth of 2.74 m. A more detailed description of the index reservoir watershed can be found in Jones et al

. , 1998. The coupled PRZM/EXAMS model and users manuals may be downloaded from the U.S. Environmental Protection Agency

(EPA) Water Models web

-page (U.S. EPA, 2010 ). Percent Crop Areas (PCA) that account for the maximum area within a watershed that may be planted with the modeled crop are applied to concentrations predicted by PRZM/EXAMS

. Screening Concentration in Ground Water (SCI

- GROW v2.3, Jul. 29, 2003) is a regression model used as a screening tool to estimate pesticide concentrations found in ground water used as drinking water. SCI

- GROW was developed by fitting a linear model to ground water concentrations with the Relative Index of Leaching Potential (RILP) as the independent variable. Ground water concentrations were taken from 90

- day average high concentr ations from Prospective Ground Water studies. The RILP is a function of aerobic soil metabolism and the soil

- water partition coefficient. The output of SCI

- GROW represents the concentrations of residue s that might be expected in shallow unconfined aquifers under sandy soils, which is representative of the ground water most vulnerable to pesticide contamination and likely to serve as a drinking water source. The SCI

- GROW user’s manual is currentl y under development; however, information concerning the model can be found on the EPA Wat er Models web

-page (USEPA, 2010 ).

# 5

References Effland, W. R., N. C. Thurman, I. Kennedy. 1999. Proposed Methods for Determining Watershed

- derived Percent Crop Areas and Considerations for Appl ying Crop Area Adjustments to Surface Water Screening Models. Presentation to the FIFRA Science Advisory Panel, May 27, 1999. Online at: http://www.epa.gov/scipoly /sap/1999/index.htm Jones, R. D., S. Abel, W. R. Effland, R. Matzner, R. Parker. 1998. An Index Reservoir for Use in Assessing Drinking Water Exposure. Proposed Methods for Basin

- scale Estimation of Pesticide Concentrations in Flowing Water and Reservoirs for Tolerance Reassessment. Presentation to FIFRA Science Advisory Panel, June 29

- 30, 1998. Online at: http://www.epa.gov/scipoly /sap/1998/index.htm USEPA. 2007. Amended Difenoconazole (Parent Only) Drinking Water Assessment in Support of New Use Registration Action for Fruiting Vegetables, Tuberous, Corn, Vegetables Subgroup, Pome Fruit, Ornamentals, and Sugar beets. U.S. Environmental Protection Agency , Office of Pesticide Programs, Environmental Fate and Effects Division, DWA Memorandum, June 19, 2007. (D333319 and D340041) US EPA, 2009 a . Difenoconazole (Parent Onl y) Drinking Water Assessment in Support of New Use Registration Action for Bulb Vegetable s, Brassica (Cole) Leafy Vegetables, Cucurbit Vegetables, Citrus Fruit, Grapes, and Tree Nuts. May 28, 2009. (D361398) USEPA. 2009b . Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides , Version 2.1

. U.S. Environmental Protection Agency , Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Environmental Fate and Effects Division, October 22, 2009

. USEPA. 2010 . Water Models. U.S. Environmental Protection Agency , Pesticides: Scienc e and Policy

. Online at: http://www.epa.gov/oppefed1/models/water/ US EPA, 2011. Difenoconazole **:** Report of the Residues of Concern Knowledgebase Sub

committee (ROCKS) . DP Code: D39135 0.

# 6 **A PPENDIX A**  **Total Residue Half**

**- life Calculation**  Aerobic Soil Metabolism Chemic al: D ifenoc onaz ole MR ID: 4 6950109 PC : 1 28847 Guideline: 162-1

**Linear half****** **lif e (**  **da ys**  **): 126.0** 

Day s pos ttr eat me nt (% of

appl ied) ln ( %

applied) 0 101. 0 4.6151 0 100. 4 4.6092 3 100. 2 4.6072 7 98.6 4.5911 7 98.6 4.5911 14 95.8 4.5623 28 87.4 4.4705 28 90.8 4.5087 56 77.3 4.3477 56 75.9 4.3294 84 67.8 4.2166 84 70.2 4.2513 100 55.8 4.0218 120 51.7 3.9455 120 56.3 4.0307 190 40.5 3.7013 293 19.6 2.9755 293 19.8 2.9857 Dat a from T

able 3, p. 42o f th e stu dy r eport. Di fenoc onaz ole and M1

y = - 0. 0055x + 4 .6 412 R2 = 0. 9924

2. 9 3. 2 3. 5 3. 8 4. 1 4. 4 4. 7

0 50 10 0 150 200 250 30 0Ln(%applied)

Days Post treatm ent Dissipa tion of d if enocona

zole in ae robic loa m soil (0

- 293 da

ys)

MR ID : 4 6950110 PC: 128847 Gu ideline: 1 62-1

**Line ar**  **ha lf-life**  **(da ys**  **): 113.**  **6**

Day s pos ttre atme nt (% of

applied) ln (%

applied) 0 95. 0 4. 5539 0 93. 9 4. 5422 3 97. 5 4. 5799 7 95. 0 4. 5539 7 90. 6 4. 5065 14 89. 2 4. 4909 28 85. 3 4. 4462 28 81. 9 4. 4055 56 67. 9 4. 2180 56 72. 4 4. 2822 84 63. 3 4. 1479 84 57. 1 4. 0448 100 52. 6 3. 9627 120 44. 1 3. 7865 120 48. 6 3. 8836 135 41. 0 3. 7136 190 32. 6 3. 4843 293 16. 4 2. 7973 293 16. 0 2. 7726 Data fro m Ta ble 3, p . 4 2 of th e study

re port

. Dif enoconaz

ole and M1

y = - 0. 0061x + 4 .5 795 R2= 0 .9 954

2. 5 3. 0 3. 5 4. 0 4. 5 5. 0

0 50 100 150 200 250 300Ln(%applied)

Days Posttreatm ent Dissipation of difenoconazole in aerobic

loam s oil (0

- 293 days)

# 7 Chem ica l: Di fe noconaz ole MR ID : 4 6950111 PC: 1 28847 Gu ideline: 1 62-1 Soil: S chanz

s andy l oam
**Ha lf** **-l ife**  **: (da**  **ys )**  **216. 6** 

(% applied) Ln (%

applied) 0 98. 9 4. 594 0 99. 7 4. 602 14 94. 2 4. 545 14 91. 8 4. 520 28 91. 8 4. 520 56 78. 5 4. 363 84 72. 9 4. 289 120 66. 1 4. 191 120 66. 1 4. 191 175 55. 3 4. 013 228 47. 7 3. 865 Data obtained fro m Ta ble 8, p . 4 0 of th e st udy

report

. Day s Pos ttre at ment Dif

enoconaz

ole and M1 y = - 0. 0032x + 4 .5 826 R2= 0 .9 935

3. 50 3. 75 4. 00 4. 25 4. 50 4. 75 5. 00

0 50 100 150 200 25 0Ln(%ofapplied)

Days posttreat me nt

Dis sipation ofd ifenoc on azol e in aerobic sandy loam s oil (days 0

- 228)

Chemic al : D if

enoc onaz ol e MR ID: 4 6950111 PC : 1 28847 Guideline: 162-1 So il: Pa ppelac ke r sa ndylo am /lo am y sa nd
**Ha lf**  **-l if**  **e ( da**  **ys )**  **247. 6** 

(% a pplied)

Ln (% a pplied) 0 96. 7 4. 572 0 98. 8 4. 593 14 96. 4 4. 569 14 92. 8 4. 530 28 92. 6 4. 528 56 79. 1 4. 371 84 76. 1 4. 332 120 64. 6 4. 168 120 67. 3 4. 209 175 54. 9 4. 006 228 57. 0 4. 043 Dat a were obt ai ned fr

om T able 9, p. 4 1 of the stu dy report

. Posttr eat ment Di fe noc onaz ol e

y = - 0. 0028x + 4. 5694 R2= 0 .9 424

3. 50 3. 75 4. 00 4. 25 4. 50 4. 75 5. 00

0 50 10 0 15 0 200 250Ln(%ofapplied)

Days pos ttreatme nt Di ssipa tion o f di fe no co nazo lei n aero bi c sa nd y l oa m/la om y sa nd s oi l

(d ay s 0

- 228)

# 8

Chemic al: D if

enoc onaz ole MR ID: 4 6950111 PC : 1 28847 Guideline: 1 62-1 So il: Sen oz an si lty cla y l oam **Ha lf**  **-l if**  **e (da**  **ys )**  **223. 6** 

(% applied) Ln (%

appl ied) 0 97. 9 4. 584 0 98. 0 4. 585 14 91. 8 4. 520 14 92. 9 4. 532 28 84. 7 4. 439 56 79. 9 4. 381 84 74. 6 4. 312 120 69. 0 4. 234 120 64. 0 4. 159 175 55. 5 4. 016 228 47. 4 3. 859 Dat a were obt ained from T able 10, p . 4 2 of th e stu dy r eport

. Day s Po sttr eat me nt Di fe noc onaz ole and M1

y = - 0. 0031x + 4.56 75 R2= 0 .9 907

3. 50 3. 75 4. 00 4. 25 4. 50 4. 75 5. 00

0 50 10 0 150 20 0 250Ln(%ofapplied)

**Day s**  **pos ttreatmen**  **t Di**  **ssi pa**  **tion of** 

**d ifenoc**  **ona zole**  **i n**  **aero bic**  **s ilty**  **cl ay** 

**l oa**  **m so**  **il (day** 

**s 0**  **- 228)** 

Chem ical: D if

enoc onaz ole MR ID: 4 6950112 & 1 3 PCC ode: 1 28847 Guideline: 162-1 Linear half

-lif e (day s) : 693. 1 Day s pos ttreat ment % a pplied Ln (% applied) 0 96. 8 4.5726 0 98. 3 4.5880 3 73. 6 4.2986 3 96. 9 4.5737 7 93. 4 4.5369 7 95. 6 4.5602 15 96. 0 4.5643 15 95. 6 4.5602 30 98. 5 4.5901 30 95. 0 4.5539 58 90. 4 4.5042 58 89. 1 4.4898 99 86. 0 4.4543 99 83. 1 4.4200 120 83. 7 4.4272 120 83. 6 4.4260 150 82. 9 4.4176 150 82. 8 4.4164 181 79. 9 4.3808 181 83. 1 4.4200 269 74. 8 4.3148 269 72. 2 4.2794 360 66. 8 4.2017 360 71. 1 4.2641 Dat a obt ained from T

able 8, p. 43of th e stu dy r eport

. Di fe noc onaz ole and M1

y = - 0. 001x + 4 .5 667 R2 = 0 .9 541

4. 15 4. 20 4. 25 4. 30 4. 35 4. 40 4. 45 4. 50 4. 55 4. 60 4. 65

0 100 200 300 400Ln(%ofapplied)

Days post tre at me nt 

### Dissipa tion of d if enocona

zole in ae robic lo amy

s an d soil

# 9

**Table B** 
**- 1.**  **Estimated h**  **alf**
**- lives**  **in aerobic**  **s oil**  MRID # Half

- life (days) 46950109 126.0 46950110 113.6 46950111 216.6 46950111 247.6 46950111 223.6 46950112

- 46950113 693.1 46950114

- 46950115 770.2 **Half**
**- life (90**  **th** 

## Percentile): 489.6 Chemic al: D if

enoc onaz ole MRI D: 4 6950114 & 15 PCC ode: 1 28847 Guideline: 1 62-1 Linear half-life (d ay s) : 770. 2 Day s pos ttreat ment

% a ppl ied Ln (% a pplied) 0 97. 0 4. 5747 0 97. 7 4. 5819 3 94. 6 4. 5497 3 95. 1 4. 5549 7 93. 9 4. 5422 7 92. 8 4. 5304 15 71. 9 4. 2753 15 92. 8 4. 5304 27 94. 2 4. 5454 27 91. 9 4. 5207 58 92. 2 4. 5240 58 92. 7 4. 5294 90 85. 4 4. 4473 90 86. 1 4. 4555 127 82. 5 4. 4128 127 82. 2 4. 4092 150 77. 7 4. 3529 150 77. 8 4. 3541 178 77. 5 4. 3503 178 81. 7 4. 4031 272 78. 0 4. 3567 272 74. 8 4. 3148 372 67. 4 4. 2106 372 68. 9 4. 2327 Dat a obt ai ned from T

able 8, p. 43 of

th e stu dy report

. Di fenoc onaz ole and M1

y = - 0. 0009x + 4.5 493 R2= 0 .9 319

4. 15 4. 20 4. 25 4. 30 4. 35 4. 40 4. 45 4. 50 4. 55 4. 60 4. 65

0 10 0 20 0 30 0 40 0**L n** **( %** **o f** **a p** **p l** **i e** **d )** 

**Day s**  **pos ttreatmen**  **t** Dissipat ion of difenocon azol e in aerobic l oam y sand so il

# 10

Aerobic Aquatic Metabolism (Total System)

Chem ical: D if

enoconaz ole (CGA- 169374) PC: 128847 MR ID : 4 6950116 Gu ideline: 1 62-4 **Ae ro**  **bic m**  **et ab**  **olis m o** 

**f [ch**  **lor ophe**  **nyl- U-**  **14 C]**  **dif en**  **oc ona**  **zole in tw**  **o Sw is**  **s water-sed**  **imen t**  **sy st** **ems. Ha**  **lf -life**  **de te**  **rmi na**  **ti on**  **Rive r**  **water- san**  **dy loa m**  **sed im**  **en t:** **tota l s**  **ys tem.**  **Ha lf** **-life (da**  **ys )**  **495. 1**  **(0 -**  **to 1**  **83-d ay**  **da ta)**  Day s Pos ttreatme nt (% of A pplied) Ln (% a pplied) 0 91. 5 4. 52 1 93. 3 4. 54 3 92. 8 4. 53 7 93. 1 4. 53 14 91. 2 4. 51 22 97. 3 4. 58 32 89. 7 4. 50 59 85. 1 4. 44 90 81. 1 4. 40 127 80. 6 4. 39 183 72. 7 4. 29 Res ults from Ta ble 9, p . 3 8 of th e s tu dy repor t. Dif enoconaz ole and M1

y = - 0. 0014x + 4 .5 411 R2= 0.9 129



### 4. 0 4. 1 4. 2 4. 3 4. 4 4. 5 4. 6 4. 7 4. 8 4. 9 5. 0

0 25 50 75 100 125 150 175**L n** **( %** **o f** **a p** **p l** **i e** **d )** 



### Days **postt reatm**  **ent**

**Di ssi**  **pa ti**  **on of** 

**d if**  **enoconaz ol**  **e (CGA** **** **169374) in**  **aerobic Sw**  **is s**  **ri ver**  **water -** **sandy lo**  **am :**  **to tal** 

**system**

Chem ical: D if

enoconaz

ole (CGA- 169374) PC : 1 28847 MR ID : 4 6950116 Gu ideline: 1 62-4 **Ae robic**  **m etab**  **olis m**  **of [c hlor**  **ophe nyl-U-**  **14 C]**  **dife noc**  **ona zole**  **in tw o S**  **wi ss**  **wat er-sed**  **im en**  **t s ys**  **tems. Ha**  **lf -life**  **de termi**  **na tion**  **Pond w ater-si**  **lty**

**c la**  **y loa m**  **sed im**  **en t:** **tota l s**  **ys tem.**  **Ha lf**  **-life (da**  **ys )**  **407. 7**  Day s Pos ttr eatme nt (% of Ap plied) Ln (% applied) 0 98. 1 4. 585987 1 96. 7 4. 571613 3 98. 1 4. 585987 7 98. 7 4. 592085 14 92. 3 4. 525044 22 100. 0 4. 60517 32 96. 4 4. 568506 59 87. 5 4. 471639 90 80. 8 4. 391977 127 71. 0 4. 26268 183 77. 4 4. 348987 Res ults from Ta ble 7, p . 3 6 of th e st udy

re port

. Dif enoc onaz

oleA nd M1

y = - 0. 0017x + 4 .5 86 R2 = 0. 8148

4. 0 4. 1 4. 2 4. 3 4. 4 4. 5 4. 6 4. 7 4. 8 4. 9 5. 0

0 25 50 75 10 0 12 5 15 0 17 5Ln(%ofapplied)

Da ys posttreat ment Di ssi pa ti on o f di fe no co nazo le (CGA

- 169374) in aero bi c Sw is s pon d wat er -silty cla y lo am: to ta l syste m

# 11

**Table B** 
**- 2**  **. Estimated**  **h alf** 
**- lives**  **in aerobic aquatic system** MRID # Half

- life (days) 469501 16 495.1 4695011 6 407.7 4695011 7 and 4695011 8 630.1 **Half**
**- life (90**  **th** 

## Percentile): **632.9** Chem ical: D if

enoconaz ole (CGA- 169374) PC: 1 28847 MR ID : 4 6950117/

46950118 Gu ideline: 1 62-4 **Ae ro**  **bic m**  **et ab** **olis m**  **of**

**[tria zo**  **lyl- 3,**  **5- 14** **C] dife**  **noc ona**  **zole in C**  **al ifor**  **nia r**  **ive r**  **wat er-l**  **oa my**  **s an**  **d s ed**  **im en** **t. Ha**  **lf -life dete**  **rmi na**  **ti on/w**  **at er-sed**  **im en**  **t tota l s**  **ys te**  **m Ha**  **lf -life (day** 

**s) 630.**  **1**

Day s Pos ttre at me nt (% o f A pplied) Ln (%

applied) 0 85. 05 4. 44 0 86. 08 4. 46 2 94.27 4. 55 5 88.77 4. 49 7 90.35 4. 50 14 88.49 4. 48 28 94.78 4. 55 47 85.86 4. 45 70 82.58 4. 41 84 79.91 4. 38 98 78.99 4. 37 112 81. 53 4. 40 Res ult s im por te d from **Paren t** w orks heet

.

Dif enoconaz ole and M1 

### y = - 0. 0011x + 4. 4996 R2 = 0. 5807

4. 35 4. 40 4. 45 4. 50 4. 55 4. 60

0 20 40 60 80 100 120**L N** **( %** **o f** **A p** **p l** **i e** **d )** 



### Days **(Post**
**- trea** **tmen t)** 

# 12

Anaerobic Aquatic Metabolism

Chemic al: D if

enoc onaz ole (CGA -169374) PC : 1 28847 MR ID: 4 6950119/46950120 Guideline: 1 62-3 **An aer** **obic met** **ab ol**  **is m of**  **[ tri**  **azoly l-** **3, 5-** 

**14 C]d**  **if en**  **ocona zole**  **in C alif**  **ornia r**  **iv er** 

**wat er**  **-s an**  **d se**  **di ment** 
**. Ha**  **lf -l**  **if e d**  **et er**  **mina ti**  **on/t ot** **al s ys**  **te m**  **Ha lf** **-l if**  **e ( da**  **ys )**  **495.1 (0-h**  **our to**  **350-da y da**  **ta )** 

Day s Posttreat ment (% of Applied) Ln (% a pplied)

0. 00 96. 50 4. 569543008 0. 00 86. 02 4. 454579827 0. 04 88. 42 4. 482098188 0. 04 90. 42 4. 504465482 7 96. 35 4. 567987395 7 93. 31 4. 535927283 15 96. 34 4. 567883601 15 100. 66 4. 611748501 22 96. 93 4. 573989069 22 98. 03 4. 585273554 29 98. 19 4. 586904377 29 97. 10 4. 575741375 57 95. 96 4. 563931438 57 86. 87 4. 464412748 85 90. 00 4.49980967 85 96. 20 4. 566429358 119 92. 72 4. 529584199 119 97. 11 4. 575854654 147 100. 10 4. 606169686 147 87. 26 4. 468892168 175 86. 80 4. 463606622 175 101. 75 4. 622518824 245 70. 07 4. 249494742 245 69. 70 4. 244200318 302 64. 70 4. 169761202 302 71. 63 4. 271513981 350 50. 77 3. 927305629 350 47. 50 3. 860729711 Res ult s imp ort ed from **Pr ofile**  work sh eet

. Difenoc onaz ol e and M1



### y = - 0.0014x + 4. 6124 R2 = 0.6915

3. 0 3. 3 3. 5 3. 8 4. 0 4. 3 4. 5 4. 8 5. 0

0 25 50 75 100 125 150 175 200 225 250 275 300 325 350**L n** **( %** **o f** **a p** **p l** **i e** **d )** 

**Days posttreatm**  **ent Dissipation**  **of [**  **14 C]difenoconazole**  **(CGA -**  **169374) in**  **anaer obic Califor** **ni a r** **iver**

**w ater**  **- sand:**  **total sy** 

**stem**

# 13 **APPENDIX B**

**The input parameters used for PRZM/EXAMS modeling.**
**Table B** 
**- 1**  **. PRZM/EXAMS Chemical Specific Input Parameters for Difenoconazole**  **Parameter Input Value and Unit**  **Source /Comments**  Maximum application rate Fruiting vegetable: 0. 46 lbs ai/A Citurs: 0.5 lbs ai/A Lo w growing berry: 0. 46 lbs ai/A Pome fruit: 0.33 ai/A Tuberous & crom vegetable: 0. 46 lbs Product Inspire TM 

## (EPA Reg. No. 100

- 1262 )

Maximum number of applications 4 (except Pome fruit) 5 pome fruit Product Label as above Method of application (CAM = 2) Foliar spray

- Aerial Product Label as above Minimum interval between applications 7 days Product Label as above Application efficiency 0.95 (aerial Application) EFED Model Input Guidance, Version 2.1 (200 9b ) a 

## Spray drift 0.16 (Aerial Application) EFED Model Input Guidance, Version 2.1 (200 9b ) Partition coefficient Kocb 

## 5381 mL/ g MRID s: 42245135 and 469501 21 Application date PA Tomato: June 30 FL Pepper: November 15 FL Straw berry: February 15 FL Citrus : June 08 PA Apple : June 30 ME Potato : June 20 Application dates were assumed 7

- 14 days before harvest based on crop profile and label instructions:

Henry’s Law constant 8.9 x 10 - 12 

## atm x m3 

## /mol MRID 46 515901 Hydroly sis Stable MRID 42245127 Aerobic soil metabolism (t 1/2 

## ) c 

## 489.6 days MRID s.: 4695010 9

- 12 and 469501 14 Aerobic aquatic metabolism (t 1/2 

## ) d 

## 632.9 days MRIDs.: 469501 16 & 469501 17 Ana erobic aquatic metabolism (t 1/2 

## ) e 

## 1485.3 days MRID 4 69501 19 Aquatic photolysis t 1/2 

## (days) f 

## Stable MRID 46950105 Vapor pressure 2.5 x 10 - 10 

## mm Hg ( 25 o 

## C) MRID 46 515901 Solubility in water 15 mg/L (25 o 

## C) MRID 46515901 Molecular Weight 406.27 MRID 46950104 Percent cropped area 0.87 U.S. EPA 2003

a 

## Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides (Version 2.1; Oct. 22, 2009 b ) b 

### There was a positive correlation between the KF 

### values v s . organic matter content; therefore, the average Koc 

### was used as an parameter. c 

### The 90% of the UCL of the mean metabolism half

- life

. d 

### The 90% of the UCL of the mean metabolism half

- life of all available half

- lives but those obtained for high test rate.
e 

### At proposed application rate only one half

- life was available, the half

- life was multiplied by three (i.e., 3 x 495.1 days). f 

### The maximum value available.

# 14

**An example (PA Tomato STD) input**  **and output of PRZM/EXAMS**  **modeling .** 

stored as PATomato.out Chemical: Difenoconazole PRZM environm ent: PAtomato STD.txt modified Tueday, 29 May 2007 at 13:01:58

EXAMS environm ent: ir298.exv modified Tueday, 26 August 2008 at 05:14:08

Metfile: w14751.d vf modified Tueday, 26 August 2008 at 05:15:00
Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 4.28 3.90 3.16 2.66 2.37 0.98 1962 4.35 4.13 3.51 3.30 3.23 2.33 1963 5.04 4.81 4.28 3.99 3.64 3.03 1964 5.45 5.21 4.87 4.30 4.18 3.73 1965 5.24 5.06 4.75 4.56 4.37 3.93 1966 10.76 10.05 8.10 6.42 6.02 4.44 1967 8.90 8.54 7.57 6.57 6.21 5.30 1968 10.27 9.70 8.09 6.73 6.42 5.35 1969 16.70 15.53 13.14 9.85 8.89 6.31 1970 8.30 8.08 7.78 7.34 6.99 6.49 1971 11.91 11.24 9.44 8.18 7.62 6.40 1972 10.28 9.76 8.80 7.81 7.45 6.66 1973 11.34 10.77 9.19 7.88 7.50 6.67 1974 9.85 9.55 8.70 8.24 7.89 6.94 1975 16.48 15.38 12.43 9.83 9.04 7.05 1976 10.46 10.05 9.10 8.11 7.83 7.22 1977 7.58 7.39 7.08 6.86 6.81 6.43 1978 7.40 7.18 6.99 6.45 6.18 5.76 1979 7.57 7.32 6.83 6.38 6.11 5.69 1980 7.24 6.95 6.18 5.92 5.47 5.11 1981 7.57 7.25 6.77 6.07 5.77 5.25 1982 6.27 6.10 5.91 5.54 5.44 4.93 1983 7.18 6.90 6.21 5.49 5.22 4.77 1984 6.34 6.14 5.87 5.36 5.17 4.89 1985 6.16 5.93 5.30 4.90 4.88 4.53 1986 8.58 8.17 7.09 6.29 5.87 4.89 1987 8.12 7.78 7.01 6.14 6.00 5.10

# 15

1988 8.28 7.89 6.82 5.92 5.64 5.10 1989 7.56 7.27 6.78 6.29 6.04 5.24 1990 7.75 7.46 6.63 6.22 6.02 5.49
Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.03 16.70 15.53 13.14 9.85 9.04 7.22 0.06 16.48 15.38 12.43 9.83 8.89 7.05 0.10 11.91 11.24 9.44 8.24 7.89 6.94 0.13 11.34 10.77 9.19 8.18 7.83 6.67 0.16 10.76 10.05 9.10 8.11 7.62 6.66 0.19 10.46 10.05 8.80 7.88 7.50 6.49 0.23 10.28 9.76 8.70 7.81 7.45 6.43 0.26 10.27 9.70 8.10 7.34 6.99 6.40 0.29 9.85 9.55 8.09 6.86 6.81 6.31 0.32 8.90 8.54 7.78 6.73 6.42 5.76 0.35 8.58 8.17 7.57 6.57 6.21 5.69 0.39 8.30 8.08 7.09 6.45 6.18 5.49 0.42 8.28 7.89 7.08 6.42 6.11 5.35 0.45 8.12 7.78 7.01 6.38 6.04 5.30 0.48 7.75 7.46 6.99 6.29 6.02 5.25 0.52 7.58 7.39 6.83 6.29 6.02 5.24 0.55 7.57 7.32 6.82 6.22 6.00 5.11 0.58 7.57 7.27 6.78 6.14 5.87 5.10 0.61 7.56 7.25 6.77 6.07 5.77 5.10 0.65 7.40 7.18 6.63 5.92 5.64 4.93 0.68 7.24 6.95 6.21 5.92 5.47 4.89 0.71 7.18 6.90 6.18 5.54 5.44 4.89 0.74 6.34 6.14 5.91 5.49 5.22 4.77 0.77 6.27 6.10 5.87 5.36 5.17 4.53 0.81 6.16 5.93 5.30 4.90 4.88 4.44 0.84 5.45 5.21 4.87 4.56 4.37 3.93 0.87 5.24 5.06 4.75 4.30 4.18 3.73 0.90 5.04 4.81 4.28 3.99 3.64 3.03 0.94 4.35 4.13 3.51 3.30 3.23 2.33 0.97 4.28 3.90 3.16 2.66 2.37 0.98

0.10 11.85 11.19 9.41 8.23 7.89 6.91 Average of yearly averages: 5.20

Inputs generated by pe5.pl

- Novemeber 2006
Data used for this run:

# 16

Output File: PATomato Metfile: w14751.dvf PRZM scenario: PAtomatoSTD.txt
EXAMS environm ent file: ir298.exv

Chemical Name: Difenoconazole Descriptio n Variable

Name Value Units Comment s Molecular weight mwt 406.27 g/mol Henry's Law Const. henry 8.90E

- 12 atm

- m^3/mol

Vapor Pressure vapr 2.50E

- 10 torr Solubility sol 15 mg/L Kd Kd mg/L Koc Koc 5381 mg/L Photolysis half

- life kdp 0 days Half

- life
Aerobic Aquatic Metabolis m kbacw 632.9 days Halfife

Anaerobic Aquatic Metabolis m kbacs 1485.3 days Halfife

Aerobic Soil Metabolis m asm 489.6 days Halfife

Hydrolysis : pH 7 0 days Half

- life
Method: CAM 2 integer See PRZM manual Incorporat ion Depth: DEPI cm Applicatio n Rate: TAPP 0.128 kg/ha Applicatio n Efficiency: APPEFF 0.95 fraction

Spray Drift DRFT 0.16 fraction of application rate applied to pond Applicatio n Date Date 30

- 06 dd/mm or dd/mmm or dd

- mm or dd

- mmm Interval 1 interval 7 days Set to 0 or delete line for single app. app. rate apprate kg/ha

# 17

1 Interval 2 interval 7 days Set to 0 or delete line for single app. app. rate 2 apprate kg/ha
Interval 3 interval 7 days Set to 0 or delete line for single app. app. rate 3 apprate kg/ha
Record 17: FILTRA

IPSCND 1 UPTKF Record 18: PLVKRT

PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Reservoir
Flag for runoff calc. RUNOFF total none, monthly or total(average of entire run)

# 18

**The input parameters used for SCI**
**- GROW**  **mo deling**  **. Table**  **B**
**- 2. SCI** 
**- GROW Input Parameters for Difenoconazole Applied on**  **Multiple Crops**  **at the Maximum Label Application Rate. Model**  **Input Variable Input Values**  Koc 

## ( the lowest value of all available Koc 

## s, MRIDs: 42245135 and 46950121 ) 1 

## 3471 ml/g Application Rate 0.125 lb. a.i./acre Number of Applications 4 Aerobic Soil Metabolism half

- life 2 

## 223.6 days Hydroly sis Stable
1 

### The Koc shows greater than three

- folds variation, thus, the lowest value was uses per guidance as of Oct . 2 2 , 200 9 (USEPA 2009b)

. 2 

### Median of seven values.



# I **nput and output of**  **SCIGROW modeling**  **.**
SCIGROW VERSION 2.3 ENVIRONMENTAL FATE AND EFFECTS DIVISION OFFICE OF PESTICIDE PROGRAMS U.S. ENVIRONMENTAL PROTECTION AGENCY

SCREENING MODEL FOR AQUATIC PESTICIDE EXPOSURE SciGrow version 2.3 chemical: Difenoconazole time is 12/19/2011 8:36:36

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

------------------------------------------------------------------------ 0.125 4.0 0.500 3.47E+03 223.6

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

groundwater screening cond (ppb) = 1.30E

- 02 ************************************************************************

# 19

**Table B** 
**- 3 Estimated drinking water concentrations before**  **and after percent**  **crop area (PCA) adjustment**



# N **on -** **Adjusted EDWCs Scenarios**  **Peak 96 hr**  **21 Day 60 Day**  **90 Day Yearly**  **Average Annual** 

**Average** PA Tomato 11.85 11.19 9.41 8.23 7.89 6.91 5.20 FL Pepper 9.61 8.62 6.22 4.74 4.32 3.28 2.51 FL Citrus 9.21 8.45 7.10 5.46 5.01 3.80 3.02 FL Straw berry 11.37 10.37 7.81 5.87 5.38 4.09 3.42 PA Apple 8.13 7.70 6.53 5.62 5.40 4.59 3.46 ME Potato 11.78 11.42 10.22 9.13 8.72 7.61 6.18



# PCA Adjusted EDWCs **Scenarios Peak**  **96 hr 21 Day**  **60 Day 90 Day**  **Yearly Average**  **Annual**

**Average** PA Tomato **10.31 1**  

## 9.74 8.19 7.16 6.86 6.02 4.52 FL Pepper 8.36 7.50 5.41 4.12 3.76 2.85 2.19 FL Citrus 8.01 7.35 6.18 4.75 4.36 3.30 2.63 FL Straw berry 9.89 9.02 6.80 5.11 4.68 3.56 2.97 PA Apple 7.08 6.70 5.69 4.89 4.70 3.99 3.01 

## ME Potato 10.25 9.93 8.89 7.95 7.59 **6.62 5.38**  1 

## Bolded values are the highest concentrations observed in modeled scenarios