### Page 1 of 6 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D.C., 20460

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION



### PC Code: 128810 DP Barcodes: 389703, 394475

MEMORANDUM November 28, 2011

SUBJECT: Drinking Water Exposure Assessment for New Uses of Azoxystrobin on Wasabi, Dragon-fruit and Sugarcane, and the Proposed Tolerances for Residues of Azoxystrobin for Use on Onion subgroups, Fruiting Vegetables Subgroups, Small Fruit & Berry Subg roups, Oilseed Subgroups; and the Proposed Increased Tolerance for Tube rous & Corm Vegetables Subgroup.

TO: Meheret Negussie, Risk Assessor Kristin Rury, Risk Assessor Paula Deschamp, Branch Chief Risk Assessment Branch 3 Health Effects Division (7509P) AND Barbara Madden, Risk Manager (RM05) Registration Division (7505P) AND Shaja Joyner, Risk Manager (RM20) Registration Division (7505P)

FROM: Reuben Baris, Environmental Scientist Mark Corbin, Chief Environmental Risk Branch 6 Environmental Fate a nd Effects Division (7507P)

REVIEWED BY: Stephanie Syslo, RAPL Environmental Risk Branch 6 Environmental Fate a nd Effects Division (7507P)

Syngenta Crop Protection has petitioned to include sugarcane as a new use for azoxystrobin (methyl (E)-2- {2-[6-(6-2-cyanophenoxy)pyrimid in-4-yloxy]pheny}-3-methoxyacrylate; PC code 128810; CAS No. ) on sugarcane for two technical (EPA Reg. No. 100-1120 and 100-1220) and two end use products (Abound®: ERA Reg. N o. 100-1098; and Quilt Xcel®: EPA Reg. No. 100-1324) (Tolerance Petition # 1F7891). Additiona lly, the IR-4 has petitioned for tolerances

### Page 2 of 6 for azoxystrobin for the following uses: tuberous and corm vegetables subgroup 1C; bulb onion subgroup 3-07A; green onion subgroup 3-07B; citr us group 10-10; canebe rry subgroup 13-07A; bushberry subgroup 13-07B; small fruit vine climbi ng, except fuzzy kiwifruit subgroup 13-07F; low-growing berry subgroup 13-07 G (except cranberry); low gr owing berry subgroup 13-07H (except strawberry); rapeseed subgroup 20A ; sunflower subgroup 10B, cottonseed subgroup 20C, dragon-fruit, and wasabi for one technical product (EPA Reg. No. 100-1120) and three enduse products (Abound® EPA Reg. No. 100-1098; Graduate A+® EPA Reg. No. 100-1308; Quadris Top® EPA Reg. No. 100-1313; Quilt Xcel® EPA Reg. No. 100-1324; Quilt® EPA Reg. No. 100-1178) (Tolerance Petition # 1E7851). Four end use products (Quilt, Quilt Xcel, Quadris Top, and Graduate A+) are formulated with at le ast one other active ingredient (difenconazole, fludioxonil, or propiconazole). This memorandum only addr esses the contribution of azoxystrobin to estimated drinking water concentrat ions (EDWCs) resulting from applications in compliance with the proposed tolerance petitions and label ammendments. EDWCs for the other a.i.’s will be addressed in separate assessments.

Azoxystrobin is a fungicide in the class of compounds called β -methoxyacrylates, which are derived from the naturally occurrin g strobilurins. The biochemical mo de of action in this class of compounds is the inhibition of electron transp ort. The Health Eff ects Division (HED) has previously determined that the only residue of concern for dietary exposure is parent azoxystrobin. Thus, only the parent was cons idered in this drinking water assessment.

The Environmental Fate and Effects Division (EFE D) estimates drinking water concentrations of a chemical based on the highest ra te of application of the chemi cal on all registered and proposed crops. In the case of azoxystrobin, turf, a previously registered crop, has the highest application rate (0.55 lb a.i./A, 9 applications per year with a 10-day interval between applications) (D278783, D279444, and D279561; memorandum from T. Nguyen to M. Rust, Feb. 4, 2002). Broccoli was also previously a ssessed at a maximum application rate of 0.25 lb a.i./A with a maximum of 6 applications per year at a 7-day interval between applications (D278783, D279444, and D279561; memorandum from T. Nguyen to M. Rust, Feb. 4, 2002). Both assessments were completed using the Tier I screening model FIRST. The proposed rates of application for wasabi and dragon-fruit are equa l to broccoli or lower, therefore the EDWCs reported for broccoli and turf are representa tive of these current actions. EDWCs recommended for use in the human health risk assessment for wasabi and dragon-fruit ar e listed below in Table 1.

Sugarcane in the U.S. is grown in unique hydrolog ic environments, particularly in Florida where sugarcane crops are grown near the Florida Ever glades where channelized flow, sheet flow, and groundwater/surface water interactions are common occurrences. Although the application rate for sugarcane is lower than what was previously assessed for cole crops, herbs, and other uses, the unique hydrologic environment may contribute to higher concentrations in drinking water. Sugarcane was modeled separately from the a bove uses using the Tier II linked PRZM and EXAMS models to estimate the azoxystrobin concentrations in surface water used for drinking water resulting from applications to sugarcane. The highest EDWCs in surface water drinking water from the use of azoxystrobin on suga rcane are 70.7, 12.1, and 7.3 μg/L, for the peak, annual mean and overall (30-year) mean concentrations, respectiv ely (Table 1). The EDWCs for

### Page 3 of 6 sugarcane are lower than those estimated for applications to tu rf (173 μg/L), but higher than the EDWCs for other agricultural crops (e.g., broccoli).

Table 1. Estimated Drinking Water Con centrations (EDWC) of azoxystrobin residues in surface water. Simulations used the highest rate proposed.

Scenario

Model (application rate lb a.i./A, frequency, interval) Surface Water 1-in-10 year Azoxystrobin Concentration ( μ g/L) Comments/Reference

Peak Annual Mean 30-Year Mean

Turf FIRST (0.55, 9x, 10-d) 173 33 -- D278783, D279444, and D279561 Broccoli FIRST (0.25, 6x, 7-d) 54 10 -- D278783, D279444, and D279561

Sugarcane PRZM/EXAMS (0.20, 4x, 14-d) 71 12 7 Tier II PRZM/EXAMS model runs. Model inputs, as well as output file are included in the attachment. Bolded values are recomme nded for use in the human health risk assessment.

### Page 4 of 6 Attachment

PRZM inputs Table 2. Summary of environmental fate parameters for azoxystrobin and values used for modeling.

Parameter Range Value Used in Model Source Solubility in water 6.7 mg/L 6.7 mg/L D218292 Vapor Pressure 8.2 x 10 -13 torr 8.2 x 10 -13 torr D218292

Hydrolysis t 1⁄2 (at 25  C) stable at pHs 5, 7, 9 0 days MRID 43678172 EFED. 2009

Aquatic Photolysis t 1⁄2 t 1⁄2 = 11 and 17 days 23.23 days (90 th percent upper confidence bound on mean) MRID 43678173

Soil Photolysis DT 50 = 11 days

t 1⁄2 = 17.6 to 28.4 days. Not currently used in PRZM MRID 43678174

Aerobic Soil Metabolism

t 1⁄2 72, 85, 164 days mean = 107 days std = 49.79 days median = 85 days (PRZM/EXAMS) 90 percent upper bound on mean = 161.2 days MRID 43678175

Aerobic Aquatic Metabolism t 1⁄2 none available 2 x aerobic soil metabolism 2 x 161.2 = 322.2 days EFED. 2009

Anaerobic Aquatic Metabolism, t 1⁄2 50 to 59 days (soil-water system) 62.3 days 90 % upper bound MRID 43678175 (Supplemental)

Sorption K f 1.5, 2.9, 4.0, 6.2, 9.5, 15, and 23 mL/g; mean – 8.87 mL/g (PRZM-EXAMS) 8.87 mL/g MRID 43678178 MRID 43678181 EFED. 2009 Spray Drift PRZM variable 0.064 (DRFT) EFED. 2009 Application Efficiency PRZM variable 0.99 (APPEFF) EFED. 2009 Foliar Wash-Off PRZM variable 0.5 (FEXTRC) EFED. 2009 Foliar Dissipation Not applicable 0 (PKDKRT) EFED. 2009 CAM (chemical application method) 2 – interception on crop canopy (PRZM variable) Foliar spray Label

DEPI (depth of soil incorporation) Default by model Default by model -- EFED. 2009. USEPA 2009. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides. U.S. Environmental Protecti on Agency, Office of Preventio n, Pesticides and Toxic Substances, Office of Pesticide Progra ms, Environmental Fate and Effects Division, Oct. 22, 2009. Online at: http://www.epa.gov/oppefed1/models/w ater/input_parameter_guidance.htm

.

SUGARCANE Output

stored as sugarcane.out Chemical: azoxystrobin PRZM environment: FLsugarcan eSTD.txt modified Tueday, 29 May 2007 at 12:53:56 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 Da y 60 Day 90 Day Yearly

### Page 5 of 6 1961 17.25 16.43 14.75 11.83 9.227 2.278 1962 7.581 7.246 6.182 4.723 4.089 2.806 1963 31.55 30.07 26.84 23.85 20.65 7.336 1964 58.28 56.32 48. 47 38.15 31.52 12.19 1965 79.5 76.86 65.73 52.08 40.72 14.26 1966 29.84 28.58 24.97 19.39 16.59 8.235 1967 21.95 20.93 17.67 14.92 12.56 5.693 1968 24.93 23.77 21.65 17.47 14.95 6.053 1969 30.04 28.64 25.65 22.01 17.55 8.246 1970 17.39 16.65 14.22 11.81 10.72 4.397 1971 49.38 47.07 39.55 27.69 19.96 6.585 1972 58.87 56.09 46.74 31.61 21.45 8.227 1973 19.36 18.53 16.68 12.8 10.57 5.532 1974 27.33 26.11 22.69 17.45 16.68 8.442 1975 14.19 13.58 11.36 7.987 6.421 3.651 1976 24.32 23.2 19.41 14.61 11.49 5.008 1977 35.92 34.29 31.87 21.89 15.23 7.211 1978 53.23 51.12 44. 93 33.82 25.03 10.08 1979 25 24.29 20.53 14.6 11.7 6.545 1980 18.81 18.24 15.22 11.66 9.178 5.341 1981 42.13 40.18 33.51 22.93 15.78 5.894 1982 72.03 68.67 62. 93 47.99 34.95 14.78 1983 27.29 26.37 24.17 20.76 17.18 9.147 1984 104 99.45 83.27 51.3 34.78 11.49 1985 41.58 39.8 33.35 23.43 19.27 7.503 1986 38 36.25 30.47 25.79 20.5 9.674 1987 45.58 43.51 39.76 30.52 22.26 9.039 1988 20.42 19.48 16.59 12 10.08 5.605 1989 9.945 9.549 8.399 6.373 5.799 3.63 1990 8.56 8.177 7.185 5.334 4.725 3.044

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 104 99.45 83.27 52.08 40.72 14.78 0.0645161290322581 79.5 76.86 65.73 51.3 34.95 14.26 0.0967741935483871 72.03 68.67 62.93 47.99 34.78 12.19 0.129032258064516 58.87 56.32 48.47 38.15 31.52 11.49 0.161290322580645 58.28 56.09 46.74 33.82 25.03 10.08 0.193548387096774 53.23 51.12 44.93 31.61 22.26 9.674 0.225806451612903 49.38 47.07 39.76 30.52 21.45 9.147 0.258064516129032 45.58 43.51 39.55 27.69 20.65 9.039 0.290322580645161 42.13 40.18 33.51 25.79 20.5 8.442 0.32258064516129 41.58 39.8 33.35 23.85 19.96 8.246 0.354838709677419 38 36.25 31.87 23.43 19.27 8.235 0.387096774193548 35.92 34.29 30.47 22.93 17.55 8.227 0.419354838709677 31.55 30.07 26.84 22.01 17.18 7.503 0.451612903225806 30.04 28.64 25.65 21.89 16.68 7.336 0.483870967741936 29.84 28.58 24.97 20.76 16.59 7.211 0.516129032258065 27.33 26.37 24.17 19.39 15.78 6.585 0.548387096774194 27.29 26.11 22.69 17.47 15.23 6.545 0.580645161290323 25 24.29 21.65 17.45 14.95 6.053 0.612903225806452 24.93 23.77 20.53 14.92 12.56 5.894 0.645161290322581 24.32 23.2 19.41 14.61 11.7 5.693 0.67741935483871 21.95 20.93 17.67 14.6 11.49 5.605 0.709677419354839 20.42 19.48 16.68 12.8 10.72 5.532 0.741935483870968 19.36 18.53 16.59 12 10.57 5.341

### Page 6 of 6 0.774193548387097 18.81 18.24 15.22 11.83 10.08 5.008 0.806451612903226 17.39 16.65 14.75 11.81 9.227 4.397 0.838709677419355 17.25 16.43 14.22 11.66 9.178 3.651 0.870967741935484 14.19 13.58 11.36 7.987 6.421 3.63 0.903225806451613 9.945 9.549 8.399 6.373 5.799 3.044 0.935483870967742 8.56 8.177 7.185 5.334 4.725 2.806 0.967741935483871 7.581 7.246 6.182 4.723 4.089 2.278

0.1 70.714 67.435 61. 484 47.006 34.454 12.12 Average of yearly averages: 7.26406666666667

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run: Output File: sugarcane Metfile: w12844.dvf PRZM scenario: FLsugarcaneSTD.txt EXAMS environment file: ir298.exv Chemical Name: azoxystrobin Description Variable Name Value Units Comments Molecular weight mwt 403.3 g/mol Henry's Law Const. henry atm-m^3/mol Vapor Pressure vapr 8.0e-13 torr Solubility sol 6.7 mg/L Kd Kd 8.87 mg/L Koc Koc mg/L Photolysis half-life kdp 23.23 days Half-life Aerobic Aquatic Metabolism kbacw 322.2 days Halfife Anaerobic Aquatic Metabolism kbacs days Halfife Aerobic Soil Metabolism as m 161.2 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI cm Application Rate: TAPP 0.227 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.064 fraction of application rate applied to pond Application Date Date 01-10 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval 14 days Set to 0 or delete line for single app. app. rate 1 apprate 0.227 kg/ha Interval 2 interval 14 days Set to 0 or delete line for single app. app. rate 2 apprate 0.227 kg/ha Interval 3 interval 14 days Set to 0 or delete line for single app. app. rate 3 apprate 0.227 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)