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

**WA SHINGTON, D.C. 20460** 

**OFFICE OF PREVENTION, PESTICIDES AND**  **TOXIC SUBSTANCES** PC Code 129099 DP Barcode D 367105 

### Date August 4, 2009 

### MEMORANDUM **SUBJECT:** Tier I Estimated Environmental Concentrations of Im idacloprid for the

Use in the Human Health Risk Assessment, Registration of a New Product for Seed Treatment, Sepresto 75WS, and New Use on Bulb Vegetables (Crop Group 3) for GAUCHO 550SC **FROM:** José L . Meléndez, Chemist

Environmental Risk Branch V Environmental Fate and Effects Division (7507P) **THROUGH :**  Mah T. Shamim, Branch Chief

Environmental Risk Branch V Environmental Fate and Effects Division (7507P) **TO:** Kable Davis, Risk Manager Reviewer

Venus Eagle, Risk Manager #1 Insecticide

- Rodenticide Branch Registration Division (7505P) **AND:** Jennifer R. Tyler , Risk Assessor

Dana Vogel, Branch Chief Registration A ction B ranch I Health Effects Division (7 509P) This memo presents the Tier I Estimated Surface Drinking Water Concentrations and Estimated Ground Water Concentrations (EDWCs) for Imidacloprid , calculated using the Tier I aquatic models FIRST and SCI

- GROW, respectively , for use in the human health risk assessment. It was found that caneberries and citrus are still the use s with the major exposure , with an application rate of 0.5 lb a.i./A, and the highest percent crop area (PCA=0.87 ), and, therefore, the drinking waters assessment results do not change from the previous ones. The previous Drinking Waters Assessment (DWA) still applies. An electronic cop y of the previous assessment is attached.

### 2

The Estimated Drinking Water Concentrations (EDWCs) for imidacloprid were calculated based on a maximum application rate of 0.5 lb a.i./A/season. The acute drinking water concentration in surface water is 36.0 ppb of imidacloprid , based on applications of the chemical to c itrus . The cancer/chronic surface drinking water concentration is 17.2 ppb (based on applications to c itrus ). The SCI

- GROW generated EDWC is 2.09 ppb of imidacloprid , which is recommended for use, both for acute and chronic exposures. **Table I** provides a summary of the Tier I modeled drinking water concentrations. Should there be a need for additional refinements, the EFED can perform a Tier II aquatic assessment, for surface waters. **Data Gaps and Uncertainties:** The environmental fate database is substantiall y complete. An aerobic aquatic metabolism (Guideline No. 835.4300) study has b een required.
**Table 1. Maximum**  **Tier I Estimated Drinking Water Concentrations (EDWCs) for drinking water risk assessment based on**  **ground application of**  **imidacloprid (for**  **additional details, refer to Attachment A )**  **. DRINKING WATER**  **SOURCE (MODEL USED)**  **U SE (rate modeled)**  **MAXIMUM ESTIMATED DRINKING WATER CONCENTRATION (EDWC) (ppb)**  Groundwater (SCI

- GROW) Citrus ( 0.5 lb a.i./A) Ac ute and chronic 2.09
Surface water (FIRST) Citrus ( 0.5 lb a.i./A) Ac ute 36.0 Citrus ( 0.5 lb a. i./A) Chronic 17.2 

### Use Characterization **Table 2** is a summary

of all agricultural use patterns for imidacloprid in the proposed labels

. Uses were arranged according to crop groups. The uses shaded gray are the proposed new ones under Pesticide Amendment for GAUCHO 550SC (new use added to the label) , or Registration Application for Sepresto 75WS (a proposed new product for seed treatment, containing imidacloprid and clothianidin as active ingredients) . The use information was obtained from the propos ed label s for GAUCHO® 550SC (EPA Reg. No. 264
- 827) and Sepresto 75WS (EPA Reg. No. 264

- XXX, Proposed New Product)

. From **Table 2** it is noted that of the new uses , onl y bulb vegetables (Crop Group 3

- 07, e.g. onion & garlic) could involve the high est use rat e for a single application at 0.5 lb a.i./A, applied foliarl y. This rate was assessed for caneberries, using FIRST , in memo randum dated 4/13/07 from R.D. Parker to J.R. Tyler and B

. Madden (Attachment A) . Therefore, a new assessment is not required.

### 3

**Tab le**  **2 .**  **Summary use information for**  **im idacloprid**  **, including**  **proposed (shaded**  **gray ) and current (not shaded)**  **uses [labels for GAUCHO® 550SC (EPA Reg. No. 264**  **- 827)**  **and Sep**  **resto 75WS (EPA Reg. No. 264 -** **XXX ,**  **Proposed)] .** 
**PURPOSE/ SOURCE**  **USE a.i. oz** **/ 1000 seed**  **A PP.**  **RATE**

**ma x. lb a.i./**  **A/applic. APP. RATE** 

**lb. a.i./ A** **/season LABELED** 

**METHODS OF APPLICATION**  **4 COMMENTS**  Sepresto 75WS Root & Tuber

veg. (CG 1) 0.00525 0.30 5 0.5 Seed treatment

GAUCHO 550SC Root veg.

(CS G 1B except sugarbeet + kava) N/A 0.38 0 .38 Seed treatment, soil, foliar

GAUCHO 550SC Tuberous & Corm veg. (CS G 1C) N/A 0.38 0.38 Seed treatment, soil, foliar
GAUCHO 550SC Sugarbeet (CA only) N/A 0.18 0.18 Seed treatment, soil Sepresto 75WS Potato Seed pieces N/A 0.09 2 0.09 2 See d treatment 0.35 oz prod/100 lb seed; 7.7 oz prod/A2
GAUCHO 550SC Potato &

Potato Seed Piece Treatment NA 0.31 0.31 Seed treatment, soil, foliar Sepresto 75WS Leafy Greens

veg. (CSG 4A) 0.0094 0.025 6 0.5 Seed treatment

GAUCHO 550SC Leafy veg.

( CSG 4A plus watercress) N/A 0.38 0.38 Seed treatment, soil, foliar Sepresto 75WS Brassica (Cole)

Leafy veg (CG 5) 0.01387 0.038 7 0.5 Seed treatment
GAUCHO 550SC Brassica (Cole)

Leafy veg (CG 5) N/A 0.38 0.38 Seed treatment, soil, foliar Sepresto 75WS Fruiting veg. (CG 8) 0.00581 0.00035 8 0.5 Seed treatment

GAUCHO 550SC Fruitin g veg.

(CG 8 ) (except pepper & okra) N/A 0.38 0.38 Seed treatment, soil, foliar Additional use

for planthouses Pepper & Okra N/A 0.5 0.5 Sepresto 75WS Cucurbit veg. (CG 9) 0.011 0.045 9 0.5 Seed treatment

### 4

**Tab le**  **2 .**  **Summary use information for**  **im idacloprid**  **, including**  **proposed (shaded**  **gray ) and current (not shaded)**  **uses [labels for GAUCHO® 550SC (EPA Reg. No. 264**  **- 827)**  **and Sep**  **resto 75WS (EPA Reg. No. 264 -** **XXX ,**  **Proposed)] .** 
**PURPOSE/ SOURCE**  **USE a.i. oz** **/ 1000 seed**  **A PP.**  **RATE**

**ma x. lb a.i./**  **A/applic. APP. RATE** 

**lb. a.i./ A** **/season LABELED** 

**METHODS OF APPLICATION**  **4 COMMENTS**  GAUCHO 550SC Cucurbit veg. (CG 9) N/A 0.38 0.38 Seed treatment, soil, foliar Addl use for

planthouses Sepresto 75WS Bulb veg. (CG 3) 0.0024 0.064 10 0.5 Seed treatment GAUCHO 550SC Bulb veg. (CG 3

- 07) N/A 0.5 0. 5 Seed treatment, soil, foliar Sepresto 75WS Cereal Grain (CG

15 w/o rice) N/A 0.03 1 0.03 1 Seed treatment 2.0 oz/100 lb seed; 2.6 oz/A 1 GAUCHO 550SC Cotton N/A 0.33 0.5 Seed treatment, soil, foliar Max. 6 applics.

a.i./ season GAUCHO 550SC Peanut N/A 0 .38 0.38 Seed treatment, soil, foliar GAUCHO 550SC Tobacco N/A NS 0.5 Soil, foliar Max. 1.2 oz prod/ 1000 plants GAUCHO 550SC Greenhouse veg. ( cucumber & tomato ) N/A NA NA 3 Foliar 0.6 oz product/ 1000 plants GAUCHO 550SC Globe Artichoke N/A 0.5 0.5 See d treatment, soil, foliar GAUCHO 550SC Herbs (CS 19A) N/A 0.38 0.38 Seed treatment, soil, foliar GAUCHO 550SC Leafy Petiole

veg. (CSG 4B) N/A 0.38 0.38 Seed treatment, soil, foliar
GAUCHO 550SC Legume veg.

(CG 6 except dry soybean N/A 0.38 0.38 Se ed treatment, soil, foliar

GAUCHO 550SC Straw berry N/A 0.5 0.5 Soil, foliar Do not use both app. methods in the same season. Use Post
- Harvest N/A 0.38 0.38 Soil, foliar

### 5

**Tab le**  **2 .**  **Summary use information for**  **im idacloprid**  **, including**  **proposed (shaded**  **gray ) and current (not shaded)**  **uses [labels for GAUCHO® 550SC (EPA Reg. No. 264**  **- 827)**  **and Sep**  **resto 75WS (EPA Reg. No. 264 -** **XXX ,**  **Proposed)] .** 
**PURPOSE/ SOURCE**  **USE a.i. oz** **/ 1000 seed**  **A PP.**  **RATE**

**ma x. lb a.i./**  **A/applic. APP. RATE** 

**lb. a.i./ A** **/season LABELED** 

**METHODS OF APPLICATION**  **4 COMMENTS**  NA = Not Available; N/A = Not Applicable; NS = Not Specified; For GAUCHO 550SC, s eed treatment is in the field at planting or shortly thereafter. 1. Seeding rate 131 lb seeds/A for wheat (representative crop); Source: http://www.uky.edu/Ag/Wheat/seedrate.html 2. Seeding rate 1 600
- 2200 lb seeds/A Source: http://aggie

- horticulture.tamu.edu/extension/vegetable/cropguides/potato.html 3. Greenhouse uses are not assessed by EFED. 4. General instructions for GAUCHO 550SC: Aerial applications of GAUCHO 550SC are not allowed. The product may be applied with ground equipment or via chemigation. Applications of GAUCHO 550SC should direct product into the seed or root zone of crop. Broadcast foliar applications are only recommended to seedling flats or trays, or where product is intended to be washed from foliage to soil prior to drying on foliage. 5. Carrots, representative crop, source for approximate seeding rate: http://pmep.cce.cornell.edu/piap/carrot96/agpractices.html

- and http://aggie

horticulture.tamu.edu/extension/v egetable/cropguides/carrot.html (23000 seeds/oz and 2

- 2.5 lb seeds/A => 920,000 seed s/A; app rate for carrots 0.00525 oz/1000 seeds => 0.30 lb a.i./A) 6. Lettuce, representative crop, source of approximate seeding rate: http://www.ipmcenters.org/cropprofiles/CP_form.cfm (ultimately, 43000 plants/A => 0.025 lb a.i./A 7. Same source as above (6) . In CA about 44,000 plants cabbage /A => 0.0038 lb a.i./A 8. Same source as above (6) : In F L, maximum plant density of tomatoes is around 4,840/A ; for tomatoes, the max. application rate is 0.00116 oz a.i./1000 seed => 0.00035 lb a.i./A (note, transplants are not considered) 9. Same source as above (6) , in FL, cucumbers maximum plant population is 21,780/A => 0.0 15 lb a.i./A 10. Onions, representative crop, source for approximate seeding rate: http://www.ag.ndsu.edu/pubs/alt

- ag/onions.htm (8000 seeds/oz and 2

- 4 lb/A => 512000 see ds/A; app. rate for onions 0.0020 oz a.i/1000 seeds . => 0.064 lb a.i./A)