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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

PREVENTION, PESTICIDES, AND

TOXIC SUBSTANCES

PC Code: 118203

DP Barcode: 380641 and 381294

MEMORANDUM Friday, April 01, 2011

SUBJECT: 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”.

TO: Kathryn Montague, M.S., Product Manager 23

Herbicide Branch

Registration Division (RD) (7505P)

Dana Vogel, Branch Chief,

Risk Assessment Branch 1,

Health Effects Division (7509P)

FROM: Mohammed Ruhman, Ph.D., Agronomist

Environmental Risk Branch VI

Environmental Fate and Effects Division (7507P)

THROUGH: Mah Shamim, Ph.D., Branch Chief

Environmental Risk Branch VI

Environmental Fate and Effects Division (7507P)

Analysis of the proposed use for this submittal suggests that there is no need for additional 

modeling as it is expected that resultant EDWCs for the use patterns in this submittal would not 

exceed those reported in the earlier submittal referenced below. Therefore, the EDWCs of 173-

180 μg/L for ground water and 24-37 μg/L for surface water may be considered conservatively 

acceptable for the use patterns included in this submittal.

This conclusion is based on analysis of the use pattern for this submittal compared to the use 

patterns considered in the previously estimated drinking water concentrations (EDWCs) for the 

screening drinking water exposure. Previous use patterns and EDWCs were reported in EFED 

Memo entitled: Tiered Drinking Water Exposure Assessment for Saflufenacil: Section 3 New 

Chemical Uses on Agricultural and Non-agricultural Areas, April 15, 2009 (DP Barcode: 
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349860). The referenced EDWCs Memo covered the proposed saflufenacil uses on selected row 

crops, orchard trees, vineyards, tree plantations, and non-agricultural areas. Estimates were based

on modeling of the use pattern on Christmas tree, conifer, and hardwood plantations and nonagricultural areas as it represent the maximum use rate (one aerial application per year at 0.356 

lbs a.i./A). In modeling, the total residues of concern of saflufenacil included saflufenacil parent, 

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

toxicity to saflufenacil parent. EDWCs of the exposure estimates were reported 

Analysis of the application rates for the proposed use patterns for this submittal (a maximum 

seasonal rate of 0.089 lbs a.i/A) suggest that there is no need for additional modeling as it is 

much lower than the rate used previously (0.356 lbs a.i/A) and it is expected to give lower 

EDWCs compared to EDWCs reported for the earlier submittal referenced above (Table 1). 

Therefore, the EDWCs of 173-180 μg/L for ground water and 24-37 μg/L for surface water are

considered conservatively acceptable for the use patterns included in this submittal.

Table 1 Previously calculated 1-in-10-year EDWCs for the proposed saflufenacil uses contained in 

EDWC Memo dated April, 15, 2009 (DP Barcode: 349860)

Source (Tier: Model) Peak Exposure (μg/L) Annual Mean Exposure (μg/L)

Surface water (Tier I: FIRST) 37.3 23.8

Ground water (Tier II: PRZM GW) 180 173

1. INTRODUCTION

Saflufenacil, is a new contact and residual herbicide in the uracil class of compounds that is 

absorbed by roots and foliage, with limited systemic activity, according to the proposed end-use 

product label, BAS 800 04H. The compound belongs to the mode-of-action Group 14/Group E, 

meaning that it inhibits protoporphyrinogen-oxidase (PPO), resulting in an accumulation of 

protoporphyrins that, in the presence of UV light, can be photoactivated into reactive oxygen 

radicals that have the potential to cause oxidative damage to cell membranes. Saflufenacil is 

proposed for use on broadleaf weeds via pre-plant and pre-emergence applications as well as 

desiccant and/or defoliant.

An ecological risk assessment was conducted for saflufenacil (BAS 800 H) as a new chemical

for use as a herbicide in the following crops cereal small grains, corn, chickpeas, cotton, edible 

beans, edible peas, lentils, lupine, sorghum, soybeans, sunflowers, fruit tree orchards, nut tree 

orchards, vineyards, fallow croplands, and non-agricultural areas including pine plantations, 

rights-of-way, bare ground, and Christmas tree plantations in addition to use as a desiccant 

and/or defoliant on sunflower (Memo and Section 3 New Chemical Environmental Fate and 

Ecological Risk Assessment dated June 16, 2009 (DP Barcode 349855). In addition a Tiered

Drinking Water Exposure Assessment for Saflufenacil (Section 3 New Chemical Uses on 

Agricultural and Non-agricultural Areas was issued April 15, 2009 (DP Barcode: 349860) for 

these same uses.

In 2010, the registrant requested a label amendment for use on citrus and nut trees in addition to 
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proposing a new use on rice as a pre-plant weeds burn-down1. The Environmental Fate and 

Effects Division (EFED) have issued a preliminarily review for that use and responded to both 

proposals in a Memo entitled Preliminary Review of Proposed Label Amendments for 

Saflufenacil dated August 4, 2010 (DP Barcodes 378968 and 379645). For citrus and nut trees, 

EFED recommended the acceptance of the referenced amendment in addition to requesting an 

update to the crop-specific restrictions and limitations on the label with respect to drift for uses 

on citrus and nut trees to reflect those for uses with the proposed application rate of 0.088 lbs 

a.i./A. For this particular amendment, EFED recommended that there is no need for conducting 

ecological risk assessments. In contrast, for the use on rice, EFED recommended conducting an 

ecological risk assessment, a drinking water exposure assessment and requesting aquatic field 

dissipation. Furthermore, clarification was encouraged of the proposed label language for use on 

rice to specify all application restrictions. 

In 2011, the registrant submitted a modified label for rice in addition to a waiver request for 

conducting aquatic field dissipation (AFD) study to support this use. Following the review of the 

new label and waiver request, EFED executed the following:

(1) A drinking water exposure assessment (Saflufenacil Rice revised Drinking Water 

Assessment (DP Barcode 384975, March 03, 2011); and

(2) An ecological risk assessment for the proposed Section 3 New Use for Saflufenacil (Rice, 

Pre-plant Burn-down) (DP Barcode: 387336, March 09, 2011).

In addition, EFED rejected the registrant waiver request for conducting the aquatic field 

dissipation study (AFD, guideline OPPTS 835.6200). An AFD study is requested for two main 

rice producing areas of the country with different water holding periods (Refer to Memo on 

Waiver Request for Aquatic Field Dissipation Study for Saflufenacil (Section 3 New Chemical

Uses in Rice; Pre-plant Burn-down) dated March 03, 2011 (DP Barcode 385078).

This memo contains the findings of a drinking water assessment for the proposed 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”.

Use Summary

Table 1 contains a summary of use patterns for saflufenacil including the 2009 Section 3 crop use 

patterns, the 2010 Labels for new use and amendments, and the Labels for new use and/or amendments 

for this submission. 

Table 1. A summary of all crop use patterns for saflufenacil

 

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For citrus and nut tress: the label amendment was for raising the maximum single application 

rate from 0.045 lbs a.i./A to 0.090. For rice, the new use was for application on drilled or dryseeded rice as pre-plant burn-down at a single/seasonal rate up to 0.045 lbs a.i./A.
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Use

MS Rate 

(lbs a.i/A) 1

MA Rate

(lbs a.i/A) 2 Additional Application Information

(1) 2009 section 3 crop use patterns

Fallow, post-harvest 0.13 0.13 Equipment: ground or aerial.

Field corn a, sweet corn b, 

and popcorn

0.13 0.13

Application timing: 14-30 days prior to planting 

(incorporated or surface) or pre-emergence.

Application rates 15-30 days prior to planting vary by soil 

texture and organic matter (higher rates on finer soils and 

soils with higher organic matter); not so 14 days prior to 

Sorghum planting. Equipment: ground or aerial.

Cotton 0.045 0.045

Application timing: prior to accumulation of 1-inch of 

rainfall or irrigation to occur 21 days prior to planting.

Equipment: ground or aerial.

Legume vegetables c

0.089 0.089

Application timing: pre-plant or pre-emergence (pre-plant 

Soybeans (tolerant) only for lentils). Equipment: ground or aerial.

Small grains d0.13 0.13

Application timing: pre-plant or pre-emergence (dormant or 

during and/or after spring green up for winter wheat at 0.045 

lbs a.i./A). Equipment: ground or aerial.

Sunflower 0.045 0.089

Maximum number of applications per year: 2 (interval not 

stated). Application timing: at least 7 days prior to harvest 

(for desiccation). Equipment: ground or aerial.

Clearfield® corn 0.023 0.023 Maximum annual app. rate from all sources: 0.134 lbs 

saflufenacil/A for Clearfield® corn; 0.089 lbs saflufenacil/A 

for legume vegetables and soybeans. Application timing: 

pre-plant or pre-emergence (pre-emergence only for 

Clearfield® corn). Equipment: ground or aerial.

Legume vegetables (per 

region) e

0.017

(Southern peas 

only: 0.023)

0.017

(Southern peas

only: 0.023)

Soybeans 0.023 0.023

Field corn a, sweet corn b, 

and popcorn

0.11 0.11

Maximum annual app. rate from all sources: 0.134 lbs 

saflufenacil/A. Application timing: 14-30 days prior to 

planting (incorporated or surface) or pre-emergence.

Application rates 15-30 days prior to planting vary by soil 

texture and organic matter (higher rates on finer soils and 

soils with higher organic matter); not so 14 days prior to 

Grain sorghum planting. Equipment: ground, aerial, or chemigation.

Citrus fruit, pome fruit, 

stone fruit, tree nuts 0.045 0.135

Maximum number of applications per year: 3 (at least 21 

days apart). Application timing: post-emergence. Equipment: 

Grape vines 0.022 0.066 ground.

Christmas tree plantations

0.356 0.356

Application timing: post-emergence for Christmas tree 

plantations; pre-plant for conifer and hardwood plantations; 

no directions for non-agricultural areas. Equipment: ground 

or aerial.

Conifer and hardwood 

plantations

Non-agricultural areas

(2) 2010 Labels for new use and amendments

Rice 0.045 0.045

Only one Pre-plant weed burn-down application in dry or 

drained rice field at least 15 days before planting and 45 

days before permanent flood is established with many crop 

specific restrictions and limitations (refer to supplemental 

label)

Citrus fruit, pome fruit, 

stone fruit, tree nuts 0.090 0.270

Same as above, only the maximum single application rate 

was raised to 0.090 lb a.i/A instead of 0.045 lb a.i./A

(3) Labels for new use and/or amendments for this submission

Oilseed canola subgroup 

20 A f

0.045 0.045

One or sequential ground or aerial application (total 

maximum of 0.045 lb a.i./A). Timing for: Flax: when 70-

80% of bolls turn brown, Canola and others: when seeds in 

the middle pods started to turn in color. Not to be applied for 
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Use

MS Rate 

(lbs a.i/A) 1

MA Rate

(lbs a.i/A) 2 Additional Application Information

oilseed crops grown for seed.

Selected edible beans, 

broad beans, garbanzo 

beans, guar, lablab beans 

and lentils

0.045 0.045

One or sequential ground or aerial application (total 

maximum of 0.045 lb a.i./A). Timing for: Dry edible beans: 

when 80% of pods turn yellow/brown, Vine type beans and 

lentils: when no more than 30% of the leaves are still green, 

Bush type beans: when no more than 40% of the leaves are 

still green. Not to be applied on dry edible beans grown for 

seed.

Important Note: Previous section 3 new use, allow for one 

application of 0.089 lb a.i/A pre-plant or pre-emergence for 

selected edible beans, and lentils (pre-plant only for lentils) 

and according to this supplemental label the Maximum rate 

should be as per the main label. Therefore, if this application 

is to be executed pre-plant applications should be reduces to 

a total maximum of 0.044 lb a.i./A (0.089-0.045).

Dry peas including field 

peas an pigeon peas

0.045 0.045

One or sequential ground or aerial application (total 

maximum of 0.045 lb a.i./A). Timing for: Dry edible peas: 

when 80% of pods turn yellow/brown, Vine type peas: when 

no more than 30% of the leaves are still green, Bush type 

peas: when no more than 40% of the leaves are still green. 

Not to be applied on dry peas grown for seed.

Important Note: Previous section 3 new use, allow for one 

application of 0.089 lb a.i/A pre-plant or pre-emergence for 

selected edible beans, and lentils (pre-plant only for lentils) 

and according to this supplemental label the Maximum rate 

should be as per the main label. Therefore, if this application 

is to be executed pre-plant applications should be reduces to 

a total maximum of 0.044 lb a.i./A (0.089-0.045).

Soybeans

0.045 0.045

One or sequential ground or aerial application (total 

maximum of 0.045 lb a.i./A). Timing for: at reaching 

physiological maturity depending on the variety. Not to be 

applied on crop grown for seed.

Important Note: Previous section 3 new use, allow for one 

application of 0.089 lb a.i/A pre-plant or pre-emergence for 

soybeans and according to this supplemental label the 

Maximum rate should be as per the main label. Therefore, if 

this application is to be executed pre-plant applications 

should be reduces to a total maximum of 0.044 lb a.i./A 

(0.089-0.045).

Oilseed sunflower 

subgroup 20B g

0.045 0.089

One or two sequential ground or aerial application (total 

maximum of 0.045 lb a.i./A). Timing for: at reaching 

physiological maturity depending on the crop. Not to be 

applied on crop grown for seed.

Important Note: Previous section 3 includes this use for as 

“sunflower crop”. It appears that the intension for this 

supplemental label is to include other crops in the oilseed 

sunflower subgroup 20B.

Oilseed cottonseed f 

0.045 0.045

One or sequential ground or aerial application (total 

maximum of 0.045 lb a.i./A). Timing for: at reaching 

physiological maturity depending on environmental 

conditions. Not to be applied on crop grown for seed.

Important Note: Previous section 3 new use, allow for one 
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Use

MS Rate 

(lbs a.i/A) 1

MA Rate

(lbs a.i/A) 2 Additional Application Information

application of 0.045 lb a.i/A pre-plant or pre-emergence for 

cotton and according to this supplemental label the 

Maximum rate should be as per the main label. Therefore, if 

this application is to be executed pre-plant applications may 

not be executed (a total maximum of 0.00 lb a.i./A (0.045-

0.045).

1 MS Rate= Maximum Single Application Rate

2 MA Rate= Maximum Annual Application Rate

a Field corn includes conventional or herbicide-tolerant field corn grown for grain, seed, or silage.

b Sweet corn does not include sweet corn grown for seed.

c Legume vegetables include chickpeas, selected edible beans, selected edible peas, and lentils.

d Small grains include wheat, barley, canaryseed, oats, millet, rye, and triticale.

e Legume vegetables (per region) includes lentils, white lupins, chickpeas, dry edible peas, English peas, and Southern peas 

in the states east of and including North Dakota, South Dakota, Wyoming, Colorado, and New Mexico, except the states east 

of and including Vermont, Massachusetts, and Connecticut; succulent peas, dry edible peas, lentils, and chickpeas in Idaho, 

Montana, Nevada, Oregon, Utah, and Washington; and chickpeas in Arizona and California.

f Oilseed canola (rapeseed) include canola (rapeseed) subgroup 20A including borage, crambe, cuphea, echium, flax, 

camelina, juncea, and mustard

g Oil seeds sunflower subgroup 20B including calendula, castor oil plant, Chinese tallow tree, euphorbia, evening primrose, 

jojoba, niger seed, rose hip, safflower, Stokes’ aster, sunflower, tallowwood, tea oil plant, and Veronica.

As shown in Table 1, the single and seasonal rate, for all the crops, in this submittal is 0.045 lbs 

a.i/A (one application/season) except for sunflower which has a seasonal rate of 0.089 (two 

applications/season). The range of these rates (0.045 to 0.089 lbs a.i/A) are much below the rate 

used for modeling in earlier submittal of 0.356 lbs a.i./A (Maximum seasonal rate for Christmas 

tree, conifer, and hardwood plantations and non-agricultural areas). Therefore, EDWCs exposure 

values calculated for the 2009 assessment (DP Barcode: 349860) may be used in the assessment 

for this submittal.