### 2 surface water and ground water for use in all other crops. It is important to note that t he modeled total residues of concern of saflufenacil include d saflufenacil parent

, M01, M02, M07, M08, M15, M22, and Product 8, all of which are assumed to have similar toxicity to saflufenacil parent.

The above stated values represent upper

- bound estimates of total concentrations that might be found in surface water and ground water due to the use of saflufenacil as a herbicide on the
current /proposed use patterns. If more informat ion or refinement is needed, please call Mohammed A. Ruhman at (703) 605

- 0644 or email: ruhman.mohammed@epa.gov



## I. BACKGROUND

Four drinking water exposure assessments were conducted :

The 1 st 

### Assessment 1 

### : A sur face/ground drinking water exposure assessment for s ection 3 new chemical uses on agricultural and non

- agricultural areas ( DP Barcode: 349860 dated April 15, 2009 ): This assessment reported the modeled EDWCs for the stressor (i.e., residues of concern) in drinking water resulting labeled uses at that time

. This assessment was based on labeled uses on C hristmas trees; citrus; conifer and hardwood plantations; c orn (field, sw eet, and pop); cotton, f

allow and post

- harvest applications; grape vines; legume vege tables; non

- agricultural areas; pome fruits; small grains; sorghum; soybeans and s unflower

. The maximum label rate consisting from a single application rate of 0.356 lb a.i/A for use on C hristmas trees; citrus; conifer and hardwood plantations ; and non

- agr icultural areas. Tier 1 FIRST modeling for surface water and older version of PRZM

- GW for ground water were used . In this respect it is noted that input parameters for the current PRZM

- GW were changed following this assessment

.

The 2 nd 

### Assessment 2 

### : A s urface d rinking water exposure a ssessment for section 3 new chemical use on rice “Pre

- plant burn

- down” ( DP Barcode: 384975 dated March

, 03 , 20 11 ) This assessment was based o n pre

- plant/pre

- flood use on rice at a rate of 0.0445 lb a.i/A with specific

use re strictions. Tier 1 Rice Model (ver. 2) was used in modeling which allows aerobic soil degradation of the pre

- flood applied chemical in addition to partitioning and degradation in the rice paddy for the left over chemical residues.

The 3 rd 

### Assessment 3 

### : A Tier II Drinking Water Exposure Assessment for Saflufenacil (Section 3 New Chemical Uses as a harvest aid on dry edible beans, dry peas, soybean, oilseeds “sunflower subgroup 20B”, oilseeds “cotton subgroup 20C”, and oilseeds canola “subgroup 20A”

.

1 The 1 st Assessment: Tiered Drinking Water Exposure Assessment for Saflufenacil (Section 3 New Chemical Uses on Agr icultural and Non

- agricultural Areas; DP Barcode: 349860 dated April 15, 2009.

2 The 2 nd Assessment: 

### Tier II Drinking Water Exposure Assessment for Saflufenacil (Section 3 New Chemical Uses on Rice (Pre

- plant Bum

- down) ; DP Barcode: 3 84975 0 dated March 3

, 20 11

. 3 The 3 rd Assessment: Tier II Drinking Water Exposure Assessment for Saflufenacil (Section 3 New Chemical Uses as a harvest aid on dry edible beans, dry peas, soybean, oilseeds “sunflower subgroup 20B”, oilseeds “cotton subgroup 20C”, and oilseeds ca nola “subgroup 20A”; DP Barcodes: 380641 and 381294 dated April 1 , 2011.

### 3 The 4 th 

### Assessment (Attached) : A surface drinking water exposure a ssessment for the proposed new use pattern on r ice (EPA Reg. No. 7969

- 278) 4 

### and the new master label for saflufenacil formulations (EPA R eg. No. 7969

- 323 ) 5



### . This assessment was b ased on these two labels which included the following changes : (a) A maximum application rate for all crops, including rice, is 0.134 lb a.i/A instead of the previous maximum rate of 0.356 lb a.i/A ; (b) T he aerobic soil half life and partitioning coefficient (K oc 

### ) were entered a s per guidance
to the current version of PRZM

- GW (refer to referenced document for these changes) (c) New c rop

- specific use restrictions/limitations for rice (refer to referenced document for these changes)



## II. CURRENT ASSESSMENT

This current assessment is for the new use patterns on Barley, Wheat and Triticale; Perennial forage grasses (grown in pastures and range land or in field grown for forage, silage and hay; and on Olive Trees. Important application parameters for the new use labels are summarized in Tabl e 1

.

Table 1 New use patterns for saflufenacil herbicide for broadleaf weed control ( MSR = Maximum single application rate in lbs a.i/A; MNOA = Maximum number of applications; MA or SR = Maximum annual or seasonal application rate in lbs a.i/A; and MAI= M ini mum application intervals in days ; AP= Application procedure= G= ground and A= aerial) Crop Application Types Purpose MSR MNOA MA or SR MAI AP Notes Barely, Wheat and Triticale D esiccation Harvest aid/ weed control 0.022

or 0.045 One or Two 0.045 N/A or N/ S 1 G or A EPA Reg. No. 7969

- 278

Cool and Warm Season Perennial Forage Grasses in pastures, rangeland, and forage, silage and hay fields Burn

- down to established stands of both types grasses during the dormant period Burn

down and residual weed control 0 .090 One or Two 0.090 14 G or A EPA Reg. No. 7969

- 278 & EPA Reg. No. 7969

- 297 Application timing as follows: * For cool & warm dormant grasses: early spring, fall (post

harvest) or during winter * For cool grasses: during the active growing period * For warm growing grasses: during the active growing period (after green

- up in early spring) Post

- emergence burn

down to established cool
season grasses In season weed control 0.045 One or Two 0.045 14 G or A Post

- emergence burn

down to established warm

s eason grasses In season weed control 0.045 One or Two 0.045 14 G or A

Split application program to established stands of both types grasses D ormant stage weed control 0.090 One or Two 0.090 14 G or A In season weed control 0.045 One or Two 0.045 14 G or A Total for Cool and Warm Season Grasses 0.134 Two 0.134 14

4 EPA Reg. No. 7969

- 278 (Sharpen ® Powered by KIXOR ® Herbicide) : A supplemental Label For broadleaf weed control in rice production.
5 EPA Reg. No. 7969

- 323 (KIXOR ® Herbicide): A broa d leaf herbicide for use in field and row agricultural crops, bearing and nonbearing tree and vine crops, and in non

- crop.

### 4 Crop Application Types Purpose MSR MNOA MA or SR MAI AP Notes
or four

Cool and Warm Grass Grown for Seeds Burn

- down To newly planted seeds for both types of grasses Burn

down weed control 0.022

or 0.045 One or Two 0.045 N/A or N/S 1 G or A Apply after 1 st tiller in cool season grasses and after the 1 st rhizome in warm
season grasses Pre

- plant/Pre

- plant incorporated Or
preemergence Weed control 0.090 One or Two 0.090 14 (Assume d) G or A Should target emerged weeds not the tree and prevent drift f rom reaching the trees. No applications are permitted during the bloom stage (flowering to start of fruiting) Split application program Weed control 0.134 Two or four 0.134 14 (Assume d) G or A

Olive Trees Postemergence

- directed weed control Weed
contr ol 0.022 One to Four 0.090 21 G

1 N/A or N/S= Not applicable (only one application) or Not specified and is assumed to be 7 days because the chemical is used f or d esiccation at the crop maturation stage which is a short period of time.



### Data for the new use patterns ( Table 1 ) indicates that the maximum application rate needed for Tier 1 FIRST modeling i s 0.134 lbs a.i/A . Therefore, surface water EDWCs for the new uses will be the same EDWCs obtained in the attached EFED last assessment. The same conclusi on applies for EDWCs for ground water modeled by PRZM

- GW. It is thus concluded that the attached assessment can cover all of the new uses.