1

OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

March 6, 2015

PC Code: 121001

DP Barcode: 424581

MEMORANDUM

SUBJECT: EFED Registration Review Problem Formulation for Sethoxydim

FROM: Christina Wendel, Biologist

James Lin, Environmental Engineer 

Environmental Risk Branch 2

Environmental Fate and Effects Division (7507P)

REVIEWED Elyssa Arnold, Biologist

BY: Environmental Risk Branch 2

Environmental Fate and Effects Division (7507P)

THROUGH: Brian Anderson, Branch Chief

Environmental Risk Branch 2

Environmental Fate and Effects Division (7507P)

TO: James Parker, Chemical Review Manager

Neil Anderson, Branch Chief

Risk Management and Implementation Branch 1

Pesticide Re-evaluation Division (7508P)
2

Table of Contents

1. Executive summary................................................................................................................. 3

2. Introduction............................................................................................................................. 4

a. Mode of Action.................................................................................................................... 4

3. Use Characterization............................................................................................................... 4

4. Conclusions from Previous Risk Assessments..................................................................... 11

a. Ecological Risk Assessment .............................................................................................. 11

b. Drinking Water Exposure Assessments............................................................................. 13

c. Clean Water Act Programs ................................................................................................ 13

5. Environmental Fate and Transport........................................................................................ 13

a. Transport and Mobility ...................................................................................................... 13

b. Degradation........................................................................................................................ 14

c. Transformation Products.................................................................................................... 15

6. Receptors............................................................................................................................... 20

a. Effects to Aquatic Organisms............................................................................................ 21

b. Effects to Terrestrial Organisms........................................................................................ 23

c. Ecological Incidents........................................................................................................... 25

7. Exposure Pathways of Concern ............................................................................................ 26

8. Analysis Plan ........................................................................................................................ 26

a. Stressors of Concern .......................................................................................................... 27

b. Measures of Exposure........................................................................................................ 27

c. Measures of Effect ............................................................................................................. 28

d. Endangered Species Assessments...................................................................................... 28

e. Endocrine Disruptor Screening Program........................................................................... 28

9. Preliminary Identification of Data Gaps............................................................................... 28

a. Environmental Fate............................................................................................................ 28

b. Effects................................................................................................................................ 29

10. References.......................................................................................................................... 39

a. Submitted Environmental Fate Studies.............................................................................. 39

b. Submitted Ecological Toxicity Studies.............................................................................. 43

APPENDIX A. SLUA Summary Table for Sethoxydim.............................................................. 50

APPENDIX B. Sethoxydim Ecotoxicity Data.............................................................................. 52

APPENDIX C. Sethoxydim Incidents......................................................................................... 59

APPENDIX D. SIP & STIR Inputs and Outputs for Sethoxydim................................................ 62
3

1. Executive summary

The Environmental Fate and Effects Division (EFED) has completed the preliminary problem 

formulation for the ecological risk, environmental fate, endangered species, and drinking water 

assessments to be conducted as part of the registration review of sethoxydim. The problem 

formulation describes the methods planned to be used during the completion of drinking water 

and ecological risk assessments in support of registration review and provides an overview of the 

environmental fate, ecological effects, potential risks associated with the use, and uncertainties 

unique to the risk assessment of sethoxydim. This document also identifies additional studies that 

would be beneficial to the conduct of an ecological risk assessment.

A number of ecological risk assessments have been conducted on sethoxydim. Conclusions from 

those assessments are that sethoxydim does not result in level-of-concern (LOC) exceedances for 

aquatic animals or aquatic plants. Risks exceeding the LOC were identified for mammals and 

terrestrial monocot plants. There are chronic dose-based LOC exceedances for multiple size 

classes of mammals consuming a variety of dietary items, and exceedances occur even with a 

single application of sethoxydim. Risk exceeding the LOC may affect listed monocot grass 

species at >1000 feet and non-listed monocot grass species at up to 509 feet from fields treated 

with sethoxydim. Risks to bees are uncertain in the absence of data; therefore, EFED 

recommends that additional data be requested to allow for a more comprehensive evaluation of 

potential effects to honey bees. EFED will evaluate those data when they are submitted and will 

work with PRD to address any risks of concern identified by those data. In addition to the need 

for honeybee data, data is needed to evaluate the terminal degradate, sulfone. 

The following are the needed data and major uncertainties for sethoxydim:

Data Needs

 Ecotoxicity Data

o OCSPP 850.1300: Freshwater invertebrate life-cycle toxicity study using TGAI

o OCSPP 850.1350: Saltwater invertebrate life-cycle toxicity study using TGAI

o OCSPP 850.1400: Saltwater fish early life-stage toxicity study using TGAI

o OCSPP 850.2100: Acute Oral Toxicity with passerine species

o OCSPP 850.3030: Honey bee Toxicity of residues on foliage

o OECD TG 213 and Non-guideline special studies: Honey bee adult acute and 

chronic oral toxicity studies

o OECD TG 237 and Non-guideline special studies: Honeybee larval acute and 

chronic oral toxicity studies

o Non-guideline special studies: Field trial measuring residues of sethoxydim in 

pollen and nectar

o Special study OECD TG 75 and OSCPP 850.3040: Semi-field testing for 

pollinators and Field testing for pollinators (both studies that are conditionally 

required based on the results of the Tier I – laboratory based studies listed above; 

if needed these additional field studies will be discussed pending the results of the 

acute and chronic adult and larval oral toxicity studies to honey bees). 
4

o OCSPP 850.4100: Terrestrial plant seedling emergence toxicity study with current 

market TEP (typical end-use product). Additional information is needed to 

determine if the studies were conducted with the current market TEP for 

monocots and dicots. If not, a new Tier II seedling emergence study using the

current market TEP is needed, and an acceptable Tier I test (at least is needed, 

unless a Tier II study is triggered for dicot plant species). 

o OCSPP 850.4150: Terrestrial plant vegetative vigor Tier II toxicity study with

(dicots and one additional species of monocots) to fulfill guideline. The only 

available vegetative vigor data for dicots was conducted with 95.4% a.i., and not 

with TEP stated in the CFR. Therefore, terrestrial plant toxicity with the current 

market TEP is still needed for dicot species. In addition, to fulfill the guideline, 

one additional monocot species is also needed from a different Family (the three 

species tested represent Family Poaceae (grasses) only). 

o Degradate Toxicity – Sulfone (terminal degradate, M2-SO2)

 Non-guideline study: aquatic vascular plant toxicity study with a grass 

species

2. Introduction

Sethoxydim is used post-emergence for selective control of annual and perennial grass weeds in 

broadleaf crops. Two end-use formulations containing sethoxydim are currently registered for 

use in the United States. Sethoxydim was previously assessed at the time of the Reregistration 

Eligibility Decision (RED) in 2005 (USEPA, 2005), and a new use assessment was completed in 

December 2014 (USEPA, 2014). 

a. Mode of Action

Sethoxydim is a member of the cyclohexanedione class of chemicals. The mode of action for 

this herbicide is lipid biosynthesis inhibition. Selectivity is shown to be due to the greater 

susceptibility at acetyl-coenzyme A carboxylase (ACCase) of grassy species. Susceptible grassy 

species are killed by inhibition of the ACCase which is a key enzyme in the lipid biosynthetic 

pathway. 

3. Use Characterization

Sethoxydim is a systemic herbicide which is registered for selective post-emergence control of a 

wide spectrum of annual and perennial grasses. It is applied either by aerial or ground methods 

and is registered for many different agricultural and residential uses throughout the United 

States. Two commercial available formulations are Emulsifiable Concentrate (EC) and Soluble 

Concentrate/Liquid (SC).

Table 1 lists the maximum use patterns for the labeled use sites. The table is the concise version 

based on the Label Use Report Package prepared in support of registration review (October 

2014). 
5

Table 1. Maximum Use Patterns for Current Registered Use Sites of Sethoxydim

Use Site Formulation 

Type1

Max. Rate

(lbs a.i./Acre)

Max. No. of 

Applications 

per Year

Min.

Application

Interval

Application 

Methods Comments

Single C.C.2 Annual

1B. Root 

vegetables 

(except sugar 

beet) subgroup

EC 0.4382 0.4382 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed postemergence

1C. Tuberous 

and corm 

vegetables 

subgroup

EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed postemergence

20A. Rapeseed 

subgroup EC 0.4382 0.8764 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed postemergence

Agricultural

Fallow/Idleland/ 

Conservation 

Reserve

EC 0.4607 1.3821 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence

Alfalfa EC 0.4607 1.1978 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence

Apricot EC 0.4382 0.9214 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Artichoke EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Asparagus EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Avocado EC 0.4607 1.3821 NS NS 14

Ground - Spray;

Band Treatment, 

Spot Treatment, 

Direct Spray

Non-bearing

Beans, 

Dried-Type

EC 0.4607 0.7371

NS NS

14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

SC 0.3931 0.3931 NS Weed Early 

Post-emergence

Beans, 

Succulent 

(Snap)

EC 0.4607 0.7371 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Beets 

(Unspecified) EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Blueberry EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Borage EC 0.4382 0.8764 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence
6

Use Site Formulation 

Type1

Max. Rate

(lbs a.i./Acre)

Max. No. of 

Applications 

per Year

Min.

Application

Interval

Application 

Methods Comments

Single C.C.2 Annual

Brassica

(Head and

Stem) 

Vegetables

EC 0.2764 0.5528 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Buckwheat EC 0.4382 0.8764 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence

Bulb Vegetables EC 0.2764 0.8292 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Caneberries EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Canola/Rape EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence

Carrot 

(Including Tops) EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Celery EC 0.2764 0.5528 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Cherry EC 0.4607 0.9214 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Citrus EC 0.4607 1.8428 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Clover EC 0.4607 1.1978 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence

Corn, Field

EC 0.2764 0.5528

NS NS

14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Burndown 

Treatment

Weed Postemergence

SC 0.3931 0.3931 NS Aerial – Broadcast;

Ground - Broadcast

Corn, Sweet

EC 0.2764 0.5528

NS NS

10

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence

SC 0.3931 0.3931 NS Aerial – Broadcast;

Ground - Broadcast

Cotton 

(Unspecified) EC 0.4607 1.3821 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment

Weed Postemergence
7

Use Site Formulation 

Type1

Max. Rate

(lbs a.i./Acre)

Max. No. of 

Applications 

per Year

Min.

Application

Interval

Application 

Methods Comments

Single C.C.2 Annual

Crambe EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment

Weed Postemergence

Cranberry EC 0.4607 0.8764 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Cucumber EC 0.2629 0.5258 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Cucurbit 

Vegetables EC 0.2764 0.5528 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Date EC 0.4382 1.3146 NS NS 14

Ground – Spray;

Band Treatment, 

Spot Treatment, 

Direct Spray

Non-bearing

Dill EC 0.4382 0.8764 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Endive 

(Escarole) EC 0.5036 NS NS NS NS Ground - Spray Weed Postemergence

Fig EC 0.4607 1.3821 NS NS 14

Ground – Direct 

Spray;

Band Treatment, 

Spot Treatment, 

Spray

Non-bearing

Flax EC 0.2764 0.7371 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence

Forest Plantings

(Reforestation

Programs) (Tree 

Farms, Tree 

Plantation, 

ETC.)

EC

0.4607 NS NS NS

NS

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Before Bud 

Break

SC 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Direct Spray

Weed Postemergence

Fruiting 

Vegetables EC 0.2764 0.8292 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Grapes EC 0.4607 0.9214 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Grasses Grown 

For Seed EC 0.4607 0.9214 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Horseradish EC 0.4607 0.9214 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence
8

Use Site Formulation 

Type1

Max. Rate

(lbs a.i./Acre)

Max. No. of 

Applications 

per Year

Min.

Application

Interval

Application 

Methods Comments

Single C.C.2 Annual

Leafy 

Vegetables EC 0.2764 0.5528 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Lentils EC 0.4607 0.7371 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Lettuce, Head EC 0.5036 NS NS NS NS Ground - Spray Foliar

Melons, 

Cantaloupe EC 0.2764 0.5528 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Mint EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Mint/ 

Peppermint/ 

Spearmint

SC 0.3931 0.3931 NS NS NS Aerial – Broadcast;

Ground - Broadcast

Weed Postemergence

Mustard EC 0.2764 0.5528 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Nectarine EC 0.4607 0.9214 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Nonagricultural

Rights-Of-Way/

Fencerows/

Hedgerows

EC, SC 0.1843 NS NS 1 NS

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment,

Spring,

Weed Postemergence

Nonagricultural

Uncultivated

Areas/Soils

EC 0.4607 1.3821 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Direct Spray

Weed Postemergence

Okra EC 0.2629 0.964 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Olive EC 0.4607 1.3821 NS NS 14

Ground - Band 

Treatment, Spot 

Treatment, Direct 

Spray, Spray

Non-bearing

Orchards 

(Unspecified) EC 0.0921 0.0921 NS NS 14

Ground - Broadcast 

Band Treatment, 

Spot Treatment,

Weed Postemergence

Ornamental 

Lawns and Turf

EC

0.4607 0.9214 NS NS

NS Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment

Seedling Stage, 

Weed Postemergence, 

Established 

Planting

SC 14

Peach EC 0.4382 0.9214 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spray, Spot 

Treatment, Spray

Weed Postemergence
9

Use Site Formulation 

Type1

Max. Rate

(lbs a.i./Acre)

Max. No. of 

Applications 

per Year

Min.

Application

Interval

Application 

Methods Comments

Single C.C.2 Annual

Peanuts 

(Unspecified) EC 0.2764 0.4607 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Peas, Dried 

Type

EC 0.4607 0.7371

NS NS

14

Aerial – Broadcast, 

Spray;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

SC 0.3931 0.3931 NS Aerial – Broadcast;

Ground - Broadcast

Peas, Succulent EC 0.2651 0.7011 NS NS 14 Ground - Spray Weed Postemergence

Pepper EC 0.2764 0.8292 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Pistachio EC 0.4607 1.8428 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spray, Spot 

Treatment, Direct 

Spray

Weed Postemergence

Plum EC 0.4607 1.3821 NS NS 14

Ground - Band 

Treatment, Spot 

Treatment, Direct 

Spray, Spray

Non-bearing

Pome Fruits EC 0.4607 1.3821 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Pomegranate EC 0.4607 1.3821 NS NS 14

Aerial – Broadcast;

Ground - Spray;

Band Treatment, 

Spot Treatment, 

Direct Spray

Non-bearing

Potato, White/ 

Irish (or 

Unspecified)

EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Prune EC 0.4607 1.3821 NS NS 14

Ground - Spray;

Spot Treatment, 

Direct Spray

Non-bearing

Rhubarb EC 0.2764 0.5528 NS NS 14

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Rye EC 0.4382 NS NS NS NS Ground - Broadcast Weed Postemergence

Safflower EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence

Sainfoin EC 0.4607 1.1978 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence

Small Fruits EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment.

Weed Postemergence
10

Use Site Formulation 

Type1

Max. Rate

(lbs a.i./Acre)

Max. No. of 

Applications 

per Year

Min.

Application

Interval

Application 

Methods Comments

Single C.C.2 Annual

Soybeans 

(Unspecified)

EC 0.4607 0.9214

NS NS

14

Aerial – Broadcast, 

Spray;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

SC 0.3931 0.3931 NS Aerial – Broadcast;

Ground - Broadcast

Strawberry EC 0.4607 0.4607 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Sugar Beet EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Sunflower EC 0.4607 0.4607 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment,

Spot Treatment

Weed Postemergence

Sweet Potato EC 0.4607 0.9214 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Tobacco EC 0.2764 0.8292 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment, 

Spray

Weed Postemergence

Tree Nuts EC 0.4607 1.8428 NS NS 14

Ground – Broadcast;

Band Treatment, 

Spot Treatment, 

Direct Spray, Spray

Weed Postemergence

Trefoil EC 0.4607 1.1978 NS NS 14

Aerial – Broadcast;

Ground - Broadcast;

Band Treatment, 

Spot Treatment

Weed Postemergence

NS - Not Specified

1 EC - Emulsifiable Concentrate; SC - Soluble Concentrate/Liquid

2 C.C. – Crop Cycle

To be reflective of the public usage, SLUA (Screening Level Usage Analysis) was performed by 

BEAD based on the data sources from USDA-NASS (United States Department of Agriculture's 

National Agricultural Statistics Service), Private Pesticide Market Research, and California 

Department of Pesticide Regulation (DPR) Pesticide Use Reporting (PUR) database. If future 

risk refinement is needed, the SLUA information will be considered (Appendix A, contains the 

SLUA summary table for sethoxydim).
11

4. Conclusions from Previous Risk Assessments

a. Ecological Risk Assessment 

A number of ecological risk assessments have been conducted on sethoxydim. The conclusions 

from the past assessments are summarized in Figure 1 and Table 2 below. In addition, a 

summary of LOC exceedances are listed in Error! No bookmark name given.below.

Figure 1. Graphic Summary of Potential Risks of Current and Recently Proposed Uses
12

Table 2. Evidence of Risk to Taxonomic Groups from Assessed Sethoxydim Uses

Table 3. LOC Exceedances for Assessed Sethoxydim Uses

Effect

Taxonomic Group

Birds Mammals Terrestrial

Plants

Terrestrial

Inverts Fish Aquatic Inverts

Aquatic 

Plants

Direct Effect LOC Exceedance --

A

√

B

--

C

--

D

-- -- --

Indirect Effect Potential E

√ √ √ √ √ √ √

A Using the new, acceptable, definitive avian reproduction study; no LOCs were exceeded for acute or chronic effects 

to birds (surrogates for terrestrial-phase amphibians and reptiles).

B There are chronic dose-based LOC exceedances for multiple size classes and dietary items. Exceedances occur even 

with a single application. There are no acute or chronic dietary-based LOC exceedances.

C Monocot grass species may show adverse effects above the LOC from sethoxydim exposure at >1000 feet from a 

treated field for listed species and up to 509 feet for non-listed species.

D No toxicity is observed in the acute studies for the adult life-stages of honey bees. However, the toxicity to larval 

life-stages is unknown; therefore, risk is presumed in the absence of acute and chronic oral toxicity data for larvae, 

and chronic oral toxicity data for the adult bees as well. Sethoxydim is systemic in plants so exposure via pollen and 

nectar is possible.

E

Indirect risks to all listed species cannot be ruled out due to adverse effects on terrestrial plant species. 

Conclusion: No Risks of Concern 

Certainty: High

Conclusion: Risks of Concern Identified

Certainty: High

Birds: Using the new, acceptable, definitive avian 

reproduction study, no LOCs were exceeded for 

chronic effects to birds. Sethoxydim is practically 

non-toxic to birds on an acute oral and subacute dietary 

basis, and no mortalities were observed at the highest 

doses tested. Additional information is needed to 

refine risk conclusions for passerine species.

Fish: No acute or chronic LOCs were exceeded for 

freshwater or estuarine/marine fish. 

Aquatic Plants: There were no LOC exceedances for 

aquatic plants.

Terrestrial Plants: Sethoxydim is an herbicide and 

will likely affect exposed sensitive non-target plants, 

particularly monocot grass species (Family Poaceae), 

near application sites. Monocot grass species may 

show adverse effects above the LOC from

sethoxydim exposure at >1000 feet from a treated

field for listed species and up to 509 feet for nonlisted species. No vegetative vigor or seedling 

emergence toxicity data for non-grass monocot 

species or dicot species exposed to sethoxydim 

typical end use-product (TEP, Poast®) have been 

submitted. 

Mammals: Chronic dose-based LOC exceedances 

only (all uses; RQs 4.5-1.2); for multiple size classes 

and dietary items. Exceedances occur even with a 

single application. However, there were no acute or 

chronic dietary-based LOC exceedances.

Conclusion: No Risks of Concern

Certainty: Low

Conclusion: Risks of Concern Identified

Certainty: Low

Aquatic Invertebrates: No acute LOCs were exceeded. 

No chronic data is available using TGAI; therefore 

there is the potential for chronic risk. However, 

available chronic data using an EP for estuarine/marine 

invertebrates results in no risks of concern. Because

estuarine/marine invertebrates are more sensitive than 

the surrogate FW invertebrate on an acute basis, 

chronic risks to freshwater invertebrates are also 

unlikely to exceed concern levels. 

Terrestrial Invertebrates: No toxicity is observed in 

the acute studies for the adult life-stages of honey 

bees. However, the toxicity to larval life-stages is 

unknown; therefore, risk is presumed in the absence 

of acute and chronic oral toxicity data for larvae, and 

chronic oral toxicity data for the adult bees as well. 

Sethoxydim is systemic in plants so exposure via 

pollen and nectar is possible.
13

b. Drinking Water Exposure Assessments

The most recent drinking water exposure assessment conducted for sethoxydim was completed 

for the IR-4 petition on fescue, oilseeds, fruits, and vegetables (DP 418281, June 2014). The 

maximum screening exposure estimates for the residues of concern were 79.6 μg/L (1-in-10-year 

peak) and 13.9 μg/L (1-in-10-year annual mean) for surface water and 0.565 μg/L for ground 

water.

c. Clean Water Act Programs

The Clean Water Act requires the Agency to publish water quality criteria that accurately reflect 

the latest scientific knowledge on the kind and extent of all identifiable effects on health and 

welfare that might be expected from the presence of pollutants in any body of water, including 

ground water. While these recommended criteria do not, in themselves, impose any 

requirements, states and authorized tribes can use them to develop water quality standards. An 

Aquatic Life Ambient Water Quality Criteria document has not been published for sethoxydim 

(see url: http://www.epa.gov/waterscience/criteria/).

The Office of Pesticide Programs (OPP) publishes aquatic life benchmarks for freshwater species 

based on toxicity values for the most sensitive species from the most recent risk assessments. 

However, aquatic life benchmarks have not been published for sethoxydim (see url: 

http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm#benchmarks). Any data 

submitted or otherwise located as part of the registration review process may be used to update 

aquatic life benchmarks if applicable.

Sethoxydim is not identified as a cause of impairment for any water bodies listed as impaired 

under section 303(d) of the Clean Water Act, based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=88

5. No Total Maximum Daily Load (TMDL) criteria have been developed for sethoxydim, based 

on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id

=885&p_pollutant_group_name=PESTICIDES.

5. Environmental Fate and Transport

a. Transport and Mobility

Sethoxydim is a highly soluble compound (4700 mg/L in pH 7 water) with a low octanol/water 

partition coefficient (log Kow is 1.65). The calculated bioconcentration factors (BCF) for 

sethoxydim and total residues were 7X, 25X, and 21X for edible, nonedible, and whole fish, 

respectively. Depuration was fast, with a half-life of 3.6 days. For these reasons, 

bioaccumulation is not likely to occur. Also, due to its low vapor pressure (1.6x10-7 mm Hg) and 

Henry's Law Constant (1.47x10-11 atm-m3/mol), sethoxydim is not expected to be volatile under 

field conditions or from water. 
14

Based on batch equilibrium experiments, sethoxydim and its transformation products, M2-SO2, 

M-SO, M-SO2, and M2-SO, were determined to be mobile to very mobile in sterile (autoclaved) 

sand, sandy loam, sandy clay loam, silt loam, and clay loam soils. Freundlich Kd values were 

<1.00 for sethoxydim and its transformation products M-SO and M-SO2. The Freundlich Kd

values for M2-SO and M2-SO2 ranged from 0.06 to 9.12. The only unsterilized soils were used 

on M2-SO2, for the reason that M2-SO2 is thought to be the most stable among test compounds 

and it is the terminal degradate. The Freundlich Kd values of M2-SO2 with non-sterilized soil are 

0.12, 2.89, 0.78, 5.64, and 9.42, respectively for sand, sandy loam, sandy clay loam, silt loam, 

and clay loam.

b. Degradation

Sethoxydim hydrolyzes at moderately rapid rates at low pHs, but is more stable at high pHs. The 

calculated half-lives are 8.7, 155, and 284 days in pH 5, 7, and 8.7 solutions, respectively. The 

major observed hydrolysis transformation product is M2-S or 6-(2-(ethylthio)propyl)-4-oxo-2-

propyl-4,5,6,7-tetrahydrobenzoxazole. In contrast, evaluation of the data of sethoxydim total 

residues shows that they remain stable at all three pHs tested.

Sethoxydim and sethoxydim total residues degrade photolytically in both water and soil. In pH 

8.7 buffered water, the calculated photolysis half-life of sethoxydim is 5.23 days, and the major 

transformation product is M1-S or 2-(1-aminobutylidene)-5-(2-(ethylthio)-propyl)-cyclohex-1,3-

dione. In sandy loam soil irradiated with a xenon light source, the half-life of sethoxydim is 

approximately 1 hour, and the major transformation product is M-SO or 2-(1-ethoxyiminobutyl)-

5-(2-(ethylsulfinyl)propyl)-3-hydroxycyclohex-2-enone. Sethoxydim total residues 

photodegrade slower than parent sethoxydim in soil and water. Using a linear regression 

analysis, EFED calculated a half-life of 19.8 days for the photolysis in water of sethoxydim total 

residues and a half-life of 20 hours in soil.

Under aerobic conditions, parent sethoxydim transformed with short half-lives (<1 day) both in 

soil and aquatic environments. It degraded with a half-life of less than one day in sandy loam 

and sandy clay loam soils. The major transformation product at 2 months was M-SO, and after 

12 months the major product was CO2. Using aerobic clay loam soil:water and aerobic clay 

soil:water systems, it was determined that, under aerobic aquatic conditions, sethoxydim 

transformed with a half-life of <1 day. After 28 days, the major transformation products were 

CO2, M-SO, M2-S, and M-SO2. In contrast to parent sethoxydim, sethoxydim total residues 

were more persistent. The observed half-life was 1 month for sethoxydim total residues in the 

aerobic sandy loam study, and 7 days in the aerobic sandy clay loam study. In an aerobic clay 

loam soil:water system, the calculated half-life for sethoxydim total residues was 38.1 days, 

while in an aerobic clay soil:water system the half-life was 32.9 days.

Under anaerobic conditions, parent sethoxydim is even more persistent than under aerobic 

conditions. It transformed with half-lives of 11 to >60 days under anaerobic soil conditions and 

25-39 days in anaerobic aquatic metabolism studies. M-SO was the major transformation 

product in both studies. It was observed that M2-S, which was a major transformation product in 

the hydrolysis study, was only a minor transformation product in the anaerobic aquatic 

metabolism study. Sethoxydim total residues were more persistent than parent sethoxydim in the 
15

anaerobic studies. A half-life of 91.6 days was observed in the anaerobic soil metabolism study, 

while half-lives of 132-187 days were observed in the anaerobic aquatic metabolism study.

The chemical properties and environmental fate parameters are tabulated in Table 4. 

Table 4. Chemical Properties and Environmental Fate Parameters of Sethoxydim

Parameter Value Source

Selected Physical/Chemical Parameters

Molecular mass (molecular formula) 327 g/mol (C15H23NO2S ) (Calculated)

Vapor pressure (25°C) 1.6 x 10-7torr EFED one-liner

Aqueous solubility (20C) 4700 mg/L EFED one-liner

Henry’s Law Constant (25°C) 1.47 x10-11 atm-m3/mol (Calculated)

Log octanol-to-water partition coefficient (log KOW) 1.65 EFED one-liner

Persistence in Water

Hydrolysis half-life (25C) pH 5: 8.7 day pH 8.6: 284 day

pH 7: 155 day MRID 41475207

Aqueous photolysis half-life (25C) (pH 8.7) 5.23 day MRID 41475208

Persistence in Soil

Aerobic soil metabolism half-life (25°C) < 1 day MRID 41475210

Aerobic aquatic metabolism half-life (25oC) < 1 day MRID 42165604

Anaerobic soil metabolism half-life (25°C) 11.2 day (sandy loam)

> 60 day (sandy clay loam) MRID 41475211

Anaerobic aquatic metabolism half-life (25°C) 25.4 day (sandy loam)

39.9 day (sandy clay loam) MRID 41475211

Mobility

Adsorption coefficients (Kd) (25oC)* 0.12, 0.78, 2.89, 5.64, 9.42 L/kg MRID 41475212

Aquatic Field Dissipation

T1⁄2 (day): 0.53 (Madera, CA), 8.1 (Chico, CA), 8.96 (Rosa, LA), 1.98 (Leland, MS) MRID 42165605

Fish Bioconcentration

BCF: 7X (edible), 25X (nonedible), 21X (whole fish) MRID 42118001

*The only batch equilibrium test with non-sterile soils, conducted on M2-SO2 (the terminal degradate).

c. Transformation Products

The following scheme represents the relationship between parent sethoxydim (M) and its eight 

identified degradates. There are three groups of degradates: a group formed from the parent by 

oxidation of the sulfur atom (M group), the “amines” or M1 group, and the M2 group or 

tetrahydrobenzoxazoles. The first M1 group daughter (M1-S) is formed by cleavage of the 

ethoxyimino group to an amino group, either by hydrolysis or aqueous photolysis. The first 

member of the M2 group (M2-S) is then formed from M1-S by ring closure to produce a 

tetrahydrobenzoxazole ring. Each of the three groups of degradates also has a sulfoxide (-SO) 
16

and a sulfone (-SO2), to round out the total of eight degradates. This reaction dominates in 

aerobic soil metabolism and soil photolysis experiments, especially to form the M-SO and MSO2 degradates.

M Group M1 Group M2 Group

M  M1-S  M2-S

  

M-SO  M1-SO  M2-SO

  

M-SO2  M1-SO2  M2-SO2

The eight degradates include 2 daughter products, which are formed from the parent by a single 

reaction (M1-S and M-SO), 3 granddaughter products that are two reactions removed from the 

parent (M-SO2, M1-SO, and M2-S), 2 great-granddaughters that are three reactions removed 

(M1-SO2 and M2-SO), and one great-great-granddaughter that is four reactions removed (M2-

SO2). It is important to note that M1-SO, M2-SO, M1-SO2, and M2-SO2 may be formed by 

more than one pathway, and that the sulfur oxidation may be reversible under reducing 

conditions.

Chemical names and structures of sethoxydim and its environmental transformation products are 

listed in Table 5.
17

Table 5. Sethoxydim and Its Environmental Transformation Products

Code Name/ 

Synonym Chemical Name Chemical Structure Study Type MRID Maximum %AR (day)

Final %AR 

(study length)

PARENT

Sethoxydim

2-[1-(ethoxyimino)butyl]-5-[2-

(ethylthio)propyl]-3-hydroxy-2-

cyclohexen-1-one

CAS Reg. No. 74051-80-2 

Formula: C15H23NO2S 

MW: 327 g/mol

TRANSFORMATION PRODUCTS

M2-S

6-(2-(ethylthio)propyl)-4-oxo-2-propyl4,5,6,7-tetrahydrobenzoxazole

Formula: C17H29NO3S

MW: 281 g/mol

Hydrolysis 41475207

81.5% (28 d) 

@ pH 5

9.7% (28 d) 

@ pH 7

2.3% (28d) @ 

pH 8.6

81.5% (28 d) 

@ pH 5

9.7% (28 d) 

@ pH 7

2.3% (28d) @ pH 

8.6

Photodegradation on 

soil 41475209 4.25% (0) 0.7% (16 hr)

Photolysis 41475208 5.7% (10 d) 5.7% (10 d)

Aerobic soil 41475210 1.6% (1 d) n.d. (12 m)

Anaerobic soil 41475211 2.6% (31 d) 2.4% (61 d)

Anaerobic soil 41475211 6.1% (31 d) 4.6% (61 d)

M1-S

2-(1-aminobutylidene)-5-(2-(ethylthio)-

propyl)-cyclohex-1,3-dione

Formula: C15H25NO2S

MW: 283 g/mol

Photodegradation on 

soil 41475209 3.2% (0) 0.8% (16 hr)

Photolysis 41475208 29.1% (10 d) 29.1% (10 d)

Aerobic soil 41475210 4.1% (1 d) n.d. (12 m)

Anaerobic soil 41475211 3.7% (0) 1.6% (61 d)

Anaerobic soil 41475211 21.6% (61 d) 21.6% (61 d)
18

Code Name/ 

Synonym Chemical Name Chemical Structure Study Type MRID Maximum %AR (day)

Final %AR 

(study length)

M-SO

2-(1-ethoxyiminobutyl)-5-(2-

(ethylsulfinyl)propyl)-3-hydroxycyclohex2-enone

Formula: C17H29NO4S

MW: 343 g/mol

Hydrolysis 41475207

1.3% (1 d) 

@ pH 5

0.9% (28 d) 

@ pH 7

1.3% (28d) @ 

pH 8.6

0.5% (28 d) 

@ pH 5

0.9 % (28 d) 

@ pH 7

1.3% (28d) @ pH 

8.6

Photodegradation on 

soil 41475209 58.8% (4 hr) 43% (16 hr)

Photolysis 41475208 2% (4 d) 0.8% (10 d)

Aerobic soil 41475210 70.8% (2 d) 0.5% (12 m)

Anaerobic soil 41475211 60.3% (31 d) 51.5% (61 d)

Anaerobic Aquatic 41475211 47.2% (61 d) 47.2% (61 d)

M-SO2

2-(1-ethoxyiminobutyl)-5(2-

(ethylsulfonyl)propyl)-3-hydroxycyclohex2-enone

Formula: C17H29NO5S

MW: 359 g/mol

Aerobic soil 41475210 11.2% (7 d) 0.4% (12 m)

Anaerobic soil 41475211 14% (61 d) 14% (61 d)

Anaerobic Aquatic 41475211 7.1% (61) 7.1% (61 d)

M1-SO

2-(1-aminobutylidene)-5-(2-(ethylsulfinyl)-

propyl)-cyclohex-1,3-dione

Formula: C15H25NO3S

MW: 299 g/mol

Photodegradation on 

soil 41475209 3.6% (16 hr) 3.6% (16 hr)

Photolysis 41475208 4.8% (10 d) 4.8% (10 d)

Aerobic soil 41475210 2.8% (1 d) 0.4% (12 m)

Anaerobic soil 41475211 1.9% (61 d) 1.9% (61 d)

Anaerobic aquatic 41475211 4.1% (61 d) 4.1% (61 d)
19

Code Name/ 

Synonym Chemical Name Chemical Structure Study Type MRID Maximum %AR (day)

Final %AR 

(study length)

M1-SO2

2-(1-aminobutylidene)-5-(2-(ethyltho)-

propyl)-cyclohex-1,3-dione

Formula: C15H25NO3S

MW: 315 g/mol

Aerobic soil 41475210 4.0% (1 d) 0.8% (12 m)

Photolysis 41475208 1.9% (10 d) 1.9% (10 d)

Anaerobic soil 41475211 1.4% (61 d) 1.4% (61 d)

Anaerobic aquatic 41475211 2.7% (61 d) 2.7% (61 d)

M2-SO

6-[2-(Ethylsulfinyl)propyl]-4-oxo-propyl4,5,6,7-tetrahydrobenzoxazole

Formula: C15H23NO3S

MW: 297 g/mol

Hydrolysis 41475207

2.0% (28 d) 

@ pH 5

0.9% (28 d) 

@ pH 7

0.1% (28d) @ 

pH 8.6

2.0% (28 d) 

@ pH 5

0.9 % (28 d) 

@ pH 7

0.1% (28d) @ pH 

8.6

Photodegradation on 

soil 41475209 2.6% (16 hr) 2.6% (16 hr)

Photolysis 41475208 1.5% (10 d) 1.5% (10 d)

Aerobic soil 41475210 9.9% (1 d) 1.2% (12 m)

Anaerobic soil 41475211 2.8% (31 d) 0 (61 d)

Anaerobic aquatic 41475211 3.4% (31d) 1.2% (61d)

M2-SO2

6-[2-(Ethylsulfonyl)propyl]-4-oxo-propyl4,5,6,7-tetrahydrobenzoxazole

Formula: C15H23NO4S

MW: 313 g/mol

Aerobic soil 41475210 15.2% (3 m) 9.0% (12 m)

Anaerobic soil 41475211 4.3% (61 d) 4.3% (61 d)

Anaerobic aquatic 41475211 1.7% (61 d) 1.75 (61 d)

Carbon dioxide

Carbon dioxide

Formula: CO2

MW: 44 g/mol

O O

Aerobic soil 41475210 48.4% (12 m) 48.4% (12 m)
20

6. Receptors

The toxicity endpoints that will be used in risk assessment for aquatic and terrestrial organisms 

exposed to sethoxydim are presented in Table 6 and Table 7 below. A complete list of the 

ecotoxicity data available for sethoxydim can be found in Appendix A.

Sethoxydim TGAI is slightly to practically non-toxic to freshwater and estuarine/marine fish and 

invertebrates on an acute exposure basis. Sethoxydim as the end-use products (EP) are highly to 

moderately toxic to freshwater and estuarine/marine fish and invertebrates on an acute exposure 

basis. Thus suggesting that the end-use product (EP) is more sensitive than the TGAI to aquatic 

taxa on an acute exposure basis. The RED attributed the increase in toxicity to the presence of 

solvent materials in the EP, and not the active ingredient, sethoxydim. Reductions in post-hatch 

survival, standard length, and wet weight, were noted effects resulting from chronic exposure of 

sethoxydim to freshwater fish, and reductions in survival and length were noted effects noted 

effects resulting from chronic exposure of sethoxydim to estuarine/marine invertebrates. There 

were no effects that were noted from chronic exposure of sethoxydim to estuarine/marine fish. 

No freshwater invertebrate toxicity data is available for sethoxydim, only mysid chronic toxicity 

data is available. It should be noted, that only one chronic study, a fathead minnow study, is 

available for the TGAI, all other available chronic toxicity data that is available uses an EP, and 

not necessarily the same EP for the different studies. For aquatic plants, effects were observed in 

the aquatic vascular plant toxicity study with reed mannagrass (Glyceria maxima), but no effects 

were observed in the aquatic non-vascular plant toxicity studies. 

Sethoxydim is practically non-toxic to birds and mammals on an acute exposure basis. Toxicity 

to terrestrial invertebrates has only been assessed for adult honey bees via an acute contact 

exposure, and sethoxydim is classified as practically non-toxic to adult honey bees. There were 

no mortalities that were treatment related in any of the acute or subacute bird studies. Mortality 

and numerous clinical signs of toxicity were noted in the acute mammalian studies for both the 

active ingredient and EP. Reduction in the proportion of the number of hatchlings to live 3-week 

(21-d) viable embryos were the most sensitive endpoints in the new mallard duck reproduction 

study, and there were no effects observed in the bobwhite quail reproduction study.

The mammalian 2-generation reproduction study indicated effects to mammals based on effects 

to the offspring including tail abnormalities in F1a and F1b offspring; malformations described as 

threadlike tail, no anal opening, malformed hindlimb, malpositioned kidneys, cleft lip, cleft 

palate, and microphthalmia. However, no systemic effects to parent animals or reproductive 

effects were observed, and no dose-related gross or microscopic lesions, or developmental 

variations (cannibalism complicated the evaluation) were observed. 

For terrestrial dicotyledonous plant species, there were no responses that were ≥25% for plants 

exposed to sethoxydim at the treatment rates tested (i.e., 0.47 lbs a.i./A (seedling emergence, 

MRID 44204801) or 0.5 lbs a.i./A (vegetative vigor, MRID 41885906)). However, the available 

Tier II vegetative vigor study was conducted with technical grade test material and not a typical 

end-use product (TEP) as described in the CFR, and Agency test guidelines. Additional data is 

needed for dicot plants. For terrestrial monocotyledonous plant species, the most sensitive 

species was ryegrass (Lolium perenne) in all tests conducted. The most sensitive parameter was 
21

phytotoxicity and dry weight in the seedling emergence study (MRID 43614603) and dry weight 

in the vegetative vigor study (MRID 47691704).

a. Effects to Aquatic Organisms

Table 6. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for Sethoxydim

Aquatic Animals

Species

Test 

Substance 

(% a.i.)

Acute Toxicity Chronic Toxicity

96-hr LC50/EC50

(95% CI)

(mg a.i./L)

(Toxicity 

Classification)

48-hr EC50

(95% CI)

(mg a.i./L)

(Toxicity 

Classification)

MRID

(Study 

Classification)

NOAEC/

LOAEC

(mg a.i./L) 

(Endpoints)

MRID

(Study 

Classification)

Rainbow trout 

(Oncorhynchus 

mykiss)

TGAI

97.3%

170 (142-204) 

(nominal)

(practically nontoxic)1

--

00042815

(Acceptable) ND ND

EP

19.3%

1.2 (1.0-1.7) 

(measured)

(moderately toxic)2

--

41885902

(Acceptable) ND ND

Fathead 

minnow 

(Pimephales 

promelas)

TGAI

94.8% -- -- ND

4.86/9.59 

(post-hatch 

survival & 

standard length)3

47691702

(Acceptable)

EP

19.6%

1.58 (1.2-2.08) 

(measured)

(moderately toxic)4

--

47691701

(Acceptable)

0.230/0.474

(standard length, 

wet weight & 

post-hatch 

survival)5

47691703

(Acceptable)

Sheepshead 

Minnow

(Cyprinodon 

variegates)

TGAI

97.8%

>145.8 

(measured)

(practically nontoxic)

--

42315101 

(Acceptable) ND ND

EP

18% 

(Acute), 

40.7% 

(Chronic)

3.5 (2.7-4.5) 

(nominal)

(moderately toxic)6

--

41510602

(Acceptable)

98/>98

(no effects)7

43614601

(Supplemental)

Waterflea

(Daphnia 

magna)

TGAI

97.3% --

78.1 (nominal)

(slightly toxic)8

00042816 

(Acceptable) ND ND

EP

19.3% --

2.6 (2.0-3.3) 

(measured) 

(moderately 

toxic)9

41885903 

(Acceptable) ND ND

Eastern oyster

(Crassostrea 

virginica)

TGAI

94.5% --

>109 

(measured)

(practically 

non-toxic)

42537401

(Acceptable) -- --

EP

20.4% --

0.9 (0.6-1.0)

(nominal)

(highly toxic)10

41607207

(Acceptable) ND ND
22

Aquatic Animals

Species

Test 

Substance 

(% a.i.)

Acute Toxicity Chronic Toxicity

96-hr LC50/EC50

(95% CI)

(mg a.i./L)

(Toxicity 

Classification)

48-hr EC50

(95% CI)

(mg a.i./L)

(Toxicity 

Classification)

MRID

(Study 

Classification)

NOAEC/

LOAEC

(mg a.i./L) 

(Endpoints)

MRID

(Study 

Classification)

Mysid 

(Americamysis 

bahia)

TGAI

97.8%

>141.8

(measured)

(practically nontoxic)

--

42315102 

(Acceptable) ND ND

EP

18% 

(Acute), 

43.1% 

(Chronic)

0.8 (0.7-1.1)

(nominal)

(highly toxic)10

--

41510604

(Acceptable)

6.5/13 

(survival & 

Length)

43614602 

(Supplemental)11

Aquatic Plants

Species Test 

Substance

Endpoint 

(mg a.i./L)

Effect 

(MRID; Study Classification)

Vascular Plants

Reed 

Mannagrass

(Glyceria 

maxima)

EP

19.3%

21-day EC50 = 0.21 

21-d NOAEC = 0.093

Growth rate based on total leaf length

(48000902, Acceptable)12

Non-Vascular Plants

Marine Diatom

(Skeletonema 

costatum)

TGAI 

99.8%

120 hr EC50 > 0.250 

NOAEC = 0.250

No effects

(43626101; Acceptable)

EP = End-Use Product; ND = No data; -- = not applicable

1 Behaviors/sublethal effects noted included being irritated, erratic swimming, dark discolored pigment, and labored respiration.

2 Effects included mortality, dark discoloration, surfacing, fish on bottom of test chamber, vertical orientation, flared gills, loss of 

equilibrium, quiescence, and/or labored respiration observed in all test concentrations. 

3 Post hatch survival and standard length were significantly reduced in the highest test concentration compared to the negative 

control.

4

In the highest test concentration (10.6 mg a.i./L) 100% mortality was observed. Observed sublethal effects included: loss of

equilibrium, discoloration, surfacing and lying on the bottom of the test chamber. Poast® (BAS 562 05 H) was the formulation that 

was tested.

5 Poast® (BAS 562 05 H) was the formulation that was tested. The most sensitive endpoints were standard length and wet weight; 

additionally post-hatch survival was also reduced in the highest treatment level as only one juvenile fish survived to test termination. 

6 There was 100% mortality observed in the test concentrations > 4.5 mg/L. Observed sublethal effects included loss of equilibrium 

and change in behavior (surfacing) during the test. 

7 A formulated product Poast 3.5EC (Reg. # 7679-129) was used; the study was supplemental as a LOAEC was not determined in 

this study.

8 Dose response slope is 4.73725. 

9 There was 100% immobility observed in the two highest test concentrations, 4.6 and 8.9 mg/L after 4 hours. Observed sublethal

effects included daphnids being observed on the bottom of the tank. 

10 There was 100% mortality observed in the test concentrations ≥ 1.1 mg/L, and no sublethal effects were observed in any test 

concentration. 

11 Erratic swimming and/or lethargy were noted in the two highest test concentrations (56 and 113 mg a.i./L) until complete 

mortality occurred on days 4 and 14 for each group, respectively. Other endpoints affected included reproduction (neonates 

produced), and weight (dry and wet). The study was classified as supplemental because it was conducted with an end-use product 

(EP) and not technical grade (TGAI) test material as required by CFR 158.490.

12 The endpoints were based on 21-day results, in addition to the most sensitive endpoint of total leaf length, growth rate based on 

dry weight also showed effects, and the resulting EC50 and NOAEC values were 2.9 and 0.093 mg a.i./L, respectively. The percent 
23

growth inhibition of total leaf length in treated culture as compared to the control ranged from 10 to 95%. Rhizome development 

was affected and plants showed moderate to strong necrotic symptoms. 

b. Effects to Terrestrial Organisms

Table 7. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for Sethoxydim

Terrestrial Animals

Species/

Test substance 

(% a.i.)

Acute Toxicity Chronic Toxicity

48-hr LD50

(μg a.i./bee) 

14-day LD50

(95% CI)

(mg/kg-bw) 

(Toxicity 

Classification)

8-day LC50

(mg a.i./kgdiet (ppm))

(Toxicity 

Classification)

MRID

(Study 

Classification)

NOAEC/LOAEC

(mg a.i./kg-diet 

(ppm)) 

(Endpoints)

MRID

(Study 

Classification)

Bobwhite Quail

(Colinus 

virginianus)/

(TGAI; 97.3%, 

Acute & 96.8% 

Chronic)

-- ND

>56201

(practically 

non-toxic)

00042814 

(Acceptable)

1000/≥1000 

(no effects)

44003401 

(Acceptable)

Mallard Duck

(Anas 

platyrhynchos)/ 

(TGAI; 97.3%, 

Acute; 94.8 & 

96.8% Chronic)

--

>25102

(practically 

non-toxic)

>56201

(practically 

non-toxic)

00042813

(Acceptable) 

& 

00072862 

(Acceptable)

466/953 

(proportion of 

number of 

hatchlings to live 

3-week (21-d) 

viable embryos)3

48000901 

(Acceptable)

Laboratory rat

(Rattus norvegicus)/

(TGAI; 94-99%)

--

2676 (F);

3125 (M)4

(practically 

non-toxic; 

Toxicity 

Category III)

--

00045847 

(Acceptable)

600/30005

(Offspring, 

developmental: tail 

abnormalities in F1a 

and F1b offspring; 

malformations 

described as 

threadlike tail, no 

anal opening,

malformed hindlimb, 

malpositioned 

kidneys, cleft lip,

cleft palate, and 

microphthalmia. No 

systemic or 

reproductive effects 

were observed.)

41510606 

&

43366401

(Acceptable)

Laboratory rat

(EP, 18%) --

4385 (F);

5000 (M)

(practically nontoxic; Toxicity 

Category III)6

--

00046326 

(Acceptable) ND ND

Laboratory rat 

(TGAI; 94-99%) --

Inhalation LC50 = 6.03 mg/L 

(Males) (Toxicity category III)7

00045849

(Acceptable) -- --

Honey Bee

(Apis mellifera)/

(TGAI; 98.9%; 

acute contact)

10

(moderately 

toxic)8

-- --

41510607 

(Acceptable) -- --
24

Terrestrial Animals

Species/

Test substance 

(% a.i.)

Acute Toxicity Chronic Toxicity

48-hr LD50

(μg a.i./bee) 

14-day LD50

(95% CI)

(mg/kg-bw) 

(Toxicity 

Classification)

8-day LC50

(mg a.i./kgdiet (ppm))

(Toxicity 

Classification)

MRID

(Study 

Classification)

NOAEC/LOAEC

(mg a.i./kg-diet 

(ppm)) 

(Endpoints)

MRID

(Study 

Classification)

Terrestrial Plants

Species/

Test substance 

(% a.i.)

Seedling Emergence Vegetative Vigor

MRID Study 

Classification EC25

(lb a.i./acre)

NOAEC

(lb a.i./acre)

EC25

(lb a.i./acre)

NOAEC

(lb a.i./acre)

Monocot: Ryegrass

(Lolium perenne)

(EP, 50.5%, SE; & 

19.6%, VV)

0.078

0.059 

(phytotoxicity, 

dry weight)9

0.0086 0.00276 

(dry weight)10

43614603 (SE)

&

47691704 (VV)

Supplemental

&

Supplemental

Dicots: 

All Dicots

(EP, 50.5%, SE; & 

TGAI, 95.4%, VV)

--

0.47

(no effects)11 --

0.5

(no effects)12

44204801 (SE)

&

41885906 (VV)

Supplemental

&

Supplemental

EP = End-Use Product; ND = No data; -- = not applicable

1 5 days of exposure via the diet, followed by 3 days of observation of chemical free diet.

2 No mortality, or behavioral abnormalities at test concentrations tested; however, there was a reduction in feed consumption at the 

1000 and 1590 mg a.i./kg-bw dose levels.

3 No treatment related mortalities were observed, although one (1) mortality was observed in the 500 ppm a.i. dose level without prior 

clinical signs of toxicity.

4 Signs of toxicity observed included: ataxia, sedation, hypotonia, lacrymation, salivation, tremor, paralysis, fall of body temperature, 

and urine incontinence diarrhea.

5 NOAEC/LOAEC = 30/150 mg/kg-bw/day. No dose-related gross or microscopic lesions, or developmental variations (cannibalism 

complicated the evaluation). No parental toxicity was observed at either the mid or high-dose, and there were problems with the feed 

formulation stability, homogeneity, and dose concentration that made it impossible to ascertain the actual doses used. However, 

additional information was submitted by the registrant, and the highest dose used in the reproduction study was 3000 ppm administered 

in the diet, or approx. 150 mg/kg/day. This is about one-fourth the gavage LEL of 650 mg/kg/day in a rat developmental toxicity study 

(Project No. 92-3826) – a maternally toxic dose that had not effect on reproduction. Taking the differences in dosing regimens and 

durations, HED presented in their September 1994 memo that the 3000 ppm dose was defined as a free-standing NOEL, and the 

reproduction study was upgraded to CORE-minimum. 

6 Signs of toxicity observed included: Dyspnea, apathy, spastic gait, and poor general state were symptoms in all dosage groups. 

Abnormal position, staggering, piloerection, and salivation were observed in the four (4) highest dosage groups; atonia, pain reflex 

absent, narcotic like state, and exciccosis were present in the three (3) highest dosage groups. At necropsy, dead animals showed heard 

dilatation, acute congestive hyperemia with atonic, diarrheaic intestine; and sacrificed animals showed several cases of adhesions of 

forestomach to liver, spleen, peritoneum with thickened forestomach and focal thickenings. 

7 The exposure was 4 hours in duration; no mortalities occurred in any treatment or control groups. Lacrymation and salivation were 

observed at 2 hours, lasting to 4 hours after inhalation exposure in both experimental and vehicle control groups. Body weights in all 

groups decreased at 4 hours, but recovered afterwards, with stunted recovery in experimental animals, and no other toxic effects were 

observed. 

8 Mortality was reported at 24 hours, and not 48 hours. No mortalities were observed for the technical material or acetone control 

groups in the acute contact (topical application) test. Information for other two additional exposure routes bees were exposed to is 

available in this study, they are spray and oral exposure routes. The study reported a total of 10% mortality from spray, and 5% 

mortality was observed from oral exposure, both at 24 hours. 

9 Tier II seed germination and seedling emergence study; ryegrass was the most sensitive monocot species tested. Dicot species were 

not tested in this study, only a Tier I study was completed as discussed.

10 Tier II vegetative vigor study using EP, ryegrass was the most sensitive monocot species tested. Dicot species were not tested in this 

Tier II study with the EP, however, the test material used in the other Tier II vegetative vigor study was TGAI, which is not in 

accordance with Agency test guidelines. 
25

11 Tier I seed germination and seedling emergence study; no effects for all dicots, except, there was a 15% response for phytotoxicity 

for cabbage, which was the only dicot plant species to show any response. 

12 Tier II vegetative vigor study using TGAI, no effects were observed in dicot species; however, since the test material was TGAI and 

not EP, which is not in accordance with Agency test guidelines, the study was classified as supplemental. 

c. Ecological Incidents

The ecological incident information system (EIIS) is an OPP database that houses ecological 

incidents that have been reported to the Agency. When available, EIIS includes date and location 

of an incident, type and magnitude of effects observed in various species, use(s) of pesticides 

known or suspected of contributing to the incident, and results of any chemical residue analysis 

or other analyses conducted during incident investigation. EIIS incidents are categorized 

according to the certainty that the incident resulted from pesticide exposure. The Avian 

Monitoring System (AIMS) is a database administered by the American Bird Conservancy that 

contains publicly available data on reported avian incidents involving pesticides. Many of the 

incidents listed in this database are also in the EIIS. The Aggregate Incident Reports database is 

an Agency database that may contain minor wildlife and plant incidents for chemicals.

Reviews of the Ecological Incident Information System (EIIS, version 2.1.1), the Avian Incident 

Monitoring System (AIMS)1, and the EPA Incident Data System (IDS, Aggregate Incident 

Reports database) were conducted on January 23, 2015. There were four ecological incidents 

reported in EIIS (I000232-001, I011716-002, I018428-016, and I021485-016), summarized in 

Appendix B. Two incidents (I000232-001 and I011716-002) involved fish, and two incidents 

(I021485-016 and I018428-016) involved terrestrial plants. Of the two incidents that involved 

fish, one was identified to be from an accidental misuse of the pesticide (I011716-002), while the 

other incident (I000232-001) was identified to be from a registered use. Both incidents however, 

occurred in the presence of other chemicals that were identified to be the probable cause of the 

incident due to greater toxicity; however sethoxydim was also applied at the same time and was 

therefore listed as a possible cause of each incident. The two incidents on terrestrial plants, also 

involved a registered use (I021485-016), as well as an identified intentional misuse (I018428-

016). The identified registered use incident on terrestrial plants (I021485-016), occurred in the 

presence of additional pesticides, and sethoxydim is listed as a possible cause of the incident. 

The identified intentional misuse (I018428-016) on terrestrial plants indicated that sethoxydim 

was applied at twice the labeled rate, which could have caused the observed damage to the 

watermelon fruit and foliage, but no pesticide residues were detected on the fruit, and 

sethoxydim was listed as a possible cause of the incident. 

There were no reported incidents in the AIMS database for sethoxydim. There were a total of 7

minor incidents in the Aggregate Incident Reports database for sethoxydim. Two minor plant 

incidents were reported in 2000 (010790-00010) for the POAST formulation of sethoxydim; 

three minor plant incidents were reported in 2001 (012391-00017) for the POAST Plus 

formulation of sethoxydim; one minor plant incident was reported in 2002 (013679-00004) for 

the BASF POAST formulation of sethoxydim; and one minor wildlife incident was reported in 

2004 (014757-00010) for the POAST Plus formulation of sethoxydim. The lack of reported 

incidences should not be construed as the absence of incidents. Incident reports for non-target 

organisms typically provide information only on mortality events and plant damage. Sublethal 

 

1 http://www.abcbirds.org/abcprograms/policy/pesticides/aims/aims/index.cfm
26

effects in organisms such as abnormal behavior, reduced growth and/or impaired reproduction 

are rarely reported, except for phytotoxic effects in terrestrial plants. 

7. Exposure Pathways of Concern

The environmental fate properties and use patterns of sethoxydim indicate that direct spray, 

spray drift, and runoff represent potential transport mechanisms to aquatic and terrestrial 

organisms. The conceptual model will consider sethoxydim and its eight degradates as the 

residue of concern.

Drinking water and inhalation exposure pathways were screened using the SIP (Screening 

Imbibition Program, version 1.0) and STIR (Screening Tool for Inhalation Risk, version 1.0) 

screening methods. Drinking water exposure alone was determined be a potential pathway of 

concern for mammalian species on an acute basis, and mammalian and avian species on a 

chronic basis (Tables 8 and 9). Inhalation pathway was determined to be a potential exposure 

pathway of low concern (no LOC exceedances were found for STIR). Outputs for each model 

are located in Appendix C. SIP and STIR are described in detail at: 

http://www.epa.gov/oppefed1/models/terrestrial/index.htm.

Table 8. SIP Mammalian Results 

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 808 808

Adjusted toxicity value (mg/kg-bw) 2058 23

Ratio of exposure to toxicity 0.393 35

Conclusion*

Exposure through 

drinking water alone is a 

potential concern for 

mammals

Exposure through drinking 

water alone is a potential 

concern for mammals

Table 9. SIP Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 3807 3807

Adjusted toxicity value (mg/kg-bw) 198290 23

Ratio of exposure to acute toxicity 0.019 165

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for birds

Exposure through drinking 

water alone is a potential 

concern for birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. Therefore, when 

aggregated with other routes (i.e., diet, inhalation, dermal), pesticide exposure through drinking water may contribute to 

a total exposure that has potential for effects to non-target animals.

8. Analysis Plan

The most recent ecological risk assessment was for an IR-4 petition (D418333, December 2014). 

The action was for expansion to new crop groupings and in conjunction with the same 

application rates of the proposed uses, the past risk assessments (D313456, D314420, D312568, 

and D312561), which includes the 2005 RED (D312568, D312561), will be relied upon because 

they adequately describe potential risks from the new proposed uses. The conclusions from the 
27

past assessments including the recently proposed uses (as the latest risk assessment was just 

conducted in December 2014). The assessments concluded that sethoxydim do not result in 

LOC exceedances for aquatic animals or aquatic plants. Both TGAI endpoints corresponding run 

off EECs and spray drift EECs with the TEP endpoints were analyzed separately. Risks 

exceeding the LOC were identified for mammals and terrestrial monocot plants. There are 

chronic dose-based LOC exceedances for multiple size classes of mammals consuming a variety 

of dietary items, and exceedances occur even with a single application of sethoxydim. Risk 

exceeding the LOC may affect listed monocot grass species at >1000 feet and non-listed 

monocot grass species at up to 509 feet from fields treated with sethoxydim. Risks to bees are 

uncertain in the absence of data; therefore, EFED recommends that additional data be requested 

to allow for a more comprehensive evaluation of potential effects to honey bees. EFED will 

evaluate those data when they are submitted and will work with PRD to address any risks of 

concern identified by those data. In addition to the need for honeybee data, there is the need for

data to evaluate the terminal degradate, sulfone. 

a. Stressors of Concern

i. Ecological Risk Assessment

For the sethoxydim ecological risk assessment, the stressors of concern in this assessment are the 

parent compound sethoxydim and its eight degradates. The eight degradates are grouped into 

three sets. These are (1) the sulfoxide (M-SO) and sulfone (M-SO2) of the parent chemical, (2) 

the hydrolysis product M1-S, its sulfoxide (M1-SO), and sulfone (M1-SO2), and (3) the 

hydrolysis/ring closure product (M2-S), and its sulfoxide (M2-SO) and sulfone (M2-SO2). 

ii. Drinking Water 

Sethoxydim and its eight degradates are the residues of concern for the sethoxydim drinking 

water exposure assessment in support of human health dietary risk assessment. The results of the 

recent 2014 drinking water exposure assessment (DP 418281) will be used for registration 

review unless an update is warranted due to new data or assessment methodologies.

b. Measures of Exposure 

Past assessments of sethoxydim EFED have used standard available models to evaluate potential 

exposures to aquatic and terrestrial organisms as described at 

http://www.epa.gov/oppefed1/models/water/index.htm and 

http://www.epa.gov/pesticides/science/models_db.htm. The Surface Water Concentration 

Calculator (SWCC) is currently the model that is typically used to estimate aquatic exposure. TREX, Bee-REX, and TerrPlant are currently the models that are typically used to estimate 

terrestrial exposure.

i. Available Monitoring Data

Sethoxydim is not an analyte in any of the following water monitoring programs: the California 

Department of Pesticide Regulation (CDPR) surface water database -

http://www.cdpr.ca.gov/docs/emon/surfwtr/surfcont.htm, the USGS NAWQA surface and 
28

ground water database - http://cida.usgs.gov/nawqa_queries_public/, and the USEPA STORET 

Data Warehouse - http://www.epa.gov/storet/. Monitoring will be considered in the assessment 

to the extent that any future data on sethoxydim are available.

c. Measures of Effect 

Toxicity data presented in Section 6 of this problem formulation would be used to calculate risk 

quotients. Any additional information submitted by the registrant or found in the open literature 

prior to conduct of the risk assessment would also be considered. The open literature studies are 

identified using EPA’s ECOTOXicology database (ECOTOX) (USEPA, 2007a), which employs 

a literature search engine for locating chemical toxicity data for aquatic life, terrestrial plants, 

and wildlife. The evaluation of both sources of data can also provide insight into the direct and 

indirect effects of pesticides on biotic communities from loss of species that are sensitive to the 

chemicals and from changes in structure and functional characteristics of the affected 

communities.

d. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the 

Agency would evaluate risks to federally listed, threatened and/or endangered (listed) species 

from registered uses of pesticides in registration review. The process for evaluating potential 

risks to listed species is further described at 

http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm. 

e. Endocrine Disruptor Screening Program

Sethoxydim was not included in the first group of 67 chemicals issued an order to conduct Tier 1 

EDSP testing and is not on the second list of chemicals for Tier 1 screening. For additional 

information the EDSP program, visit http://www.epa.gov/endo/.

9. Preliminary Identification of Data Gaps 

a. Environmental Fate

Table 10 identifies environmental fate studies by MRID that offer data for each guideline 

requirement, as well as study classifications and whether or not further data are needed in order 

to support risk assessment.

Table 10. Submitted Environmental Fate Data for Sethoxydim

OCSPP 

Guideline Data Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Sufficient 

for risk 

assessment?

Current Additional Data Need

835.2120 Hydrolysis 41475207 Acceptable Yes None

835.2240 Aqueous photolysis 41475208 Acceptable Yes None

835.2410 Soil photolysis 41475209 Acceptable Yes None
29

OCSPP 

Guideline Data Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Sufficient 

for risk 

assessment?

Current Additional Data Need

835.4100 Aerobic soil 

metabolism 41475210 Acceptable Yes None

835.4200 Anaerobic soil 

metabolism 41475211 Acceptable Yes None

835.4400 Anaerobic aquatic 

metabolism

42165603

42165604 Acceptable Yes None

835.1230

835.1240

Adsorption/ 

desorption and 

leaching

41475212 Acceptable Yes None

835.6100 Terrestrial field 

dissipation

41510608

41510609

41510610

41510611

44311001

44352401

Supplemental Yes

Total sethoxydim residues were 

analyzed, rather than the parent 

compound and its eight degradates. 

Since the total toxic residues approach 

will be used, so need to repeat the 

study. 

835.6200 Aquatic field 

dissipation 42165605 Acceptable Yes None

850.1730 Fish 

bioconcentration 42118001 Acceptable Yes None

b. Effects

Table 11 and 

Table 12 identify ecological effects studies by MRID that offer data for each guideline 

requirement, as well as study classifications and whether further data are needed in order to 

support risk assessment. The rationale for additional non-guideline data requested is presented 

below the tables.

Table 11. Submitted Aquatic Ecological Effects Data for Sethoxydim

OCSPP

Guideline Data Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Sufficient 

for risk 

assessment?

Current Additional Data 

Need

850.1010

Freshwater 

invertebrate 

acute toxicity

00042816 Acceptable

Yes

None; however, additional 

information regarding the TGAI 

study (MRID 00042816) could 

alleviate some uncertainty as 

only nominal concentrations 

were reported. However, the 

sethoxydim formulations are 

more toxic than the active 

ingredient alone.

41885903 Acceptable

850.1025

850.1035

850.1045

850.1055

Saltwater 

invertebrate 

acute toxicity 

42537401 Acceptable

Yes

None. Although the TGAI 

studies (42537401 & 42315102) 

reported mean-measured 

concentrations, the sethoxydim 

formulations are more toxic than 

the active ingredient alone.

41607207 Acceptable

42315102 Acceptable

41510604 Acceptable
30

OCSPP

Guideline Data Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Sufficient 

for risk 

assessment?

Current Additional Data 

Need

850.1075 Freshwater fish acute 

toxicity 

00042815 Acceptable

Yes

None; however, again only 

nominal concentrations were 

reported in the TGAI studies 

(MRID’s 00042815, and 

00072863), additional 

information or new studies 

measuring the test 

concentrations could alleviate 

some uncertainty. However, 

the sethoxydim formulations

are more toxic than the active 

ingredient alone.

41885902 Acceptable

00072863 Acceptable

41885901 Acceptable

47691701 Acceptable

850.1075 Saltwater fish acute 

toxicity 

42315101 Acceptable

Yes

Although the TGAI study 

(42315101) reported measured 

concentrations, the sethoxydim 

formulation is more toxic than 

the active ingredient alone.

41510602 Acceptable

850.1300

Freshwater 

invertebrate 

life cycle 

(None) (Not applicable) No

Only chronic estuarine/marine 

invertebrate toxicity data is 

available, and chronic 

freshwater invertebrate toxicity 

data is required by CFR 

158.630. The study should be 

conducted with the TGAI.

850.1350

Saltwater 

invertebrates 

life cycle 

43614602 Supplemental No

The study was classified as 

supplemental because it was 

conducted with an end-use 

product (EP) and not technical 

grade (TGAI) test material as 

required by CFR 158.630. A 

study should be conducted 

with the TGAI.

850.1400 Freshwater fish 

early-life stage

47691702 Acceptable

Yes None. Study were conducted 

with both the TGAI and EP. 47691703 Acceptable

850.1400 Saltwater fish 

early-life stage 43614601 Supplemental No

The study was supplemental as 

a LOAEC was not determined 

in this study. In addition, the 

study was conducted with an 

end-use product (EP) and not 

technical grade (TGAI) test 

material as required by CFR 

158.630. A study should be 

conducted with the TGAI.

850.1500 Fish life cycle (None) (Not applicable) Yes None

850.4400

Aquatic plant 

Toxicity Test using 

Lemna spp.

43614605 Supplemental Yes

None; an acceptable aquatic 

vascular plant study for a grass 

species was completed using 

Glyceria maxima as the test 

species. This was deemed to 

be an acceptable alternative.
31

OCSPP

Guideline Data Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Sufficient 

for risk 

assessment?

Current Additional Data 

Need

NG

Aquatic vascular 

plant Toxicity Test 

using Glyceria 

maxima

48000902 Acceptable Yes

None; an acceptable aquatic 

vascular plant study for a grass 

species was completed using 

Glyceria maxima as the test 

species. This was deemed to 

be an acceptable alternative.

850.4500 Algal toxicity

43626101 Acceptable Yes

Marine diatom; Skeletonema 

costatum. No effects were 

observed in the study.

43614607 Acceptable Yes

Freshwater green alga; 

Selenastrum capricornutum. No 

effects were observed in the 

study.

43614606 Acceptable Yes

Freshwater diatom; Navicula 

pelliculosa. No effects were 

observed in the study.

850.4550 Cyanobacteria 43614608 Acceptable Yes

Freshwater blue-green alga; 

Anabaena flos-aquae. No effects 

were observed in the study.

Table 12. Submitted Terrestrial Ecological Effects Data for Sethoxydim

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Sufficient 

for risk 

assessment?

Current Additional Data Need

850.2100 Avian oral 

toxicity 00042813 Acceptable No

Yes – a passerine species is needed 

to fulfill guideline requirements. 

Tier 1 EECs from past assessments 

ranged from approximately 19-312

mg/kg, and the acute LD50 was 

>2510 mg/kg-bw and the sub-acute 

LC50 was >5620 mg/kg-diet. The 

passerine LC50 would have to be at 

least 0.53 times (3000/>5620) lower 

than the other avian species to result 

in an acute listed species LOC 

exceedance of 0.1. Based on this, 

there is little margin of safety given 

the lack of acute effects to other 

birds, but additional data would 

likely add to the risk assessment.

850.2200 Avian dietary 

toxicity 

00042814 Acceptable

Yes None

00072862 Acceptable

850.2300 Avian 

reproduction

44003401 Acceptable

Yes None 44003402 Supplemental

48000901 Acceptable
32

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Sufficient 

for risk 

assessment?

Current Additional Data Need

870.1100 Mammalian 

acute oral

00045847 Acceptable

Yes None

00046326 Acceptable

870.1300 Mammalian 

acute inhalation 00045849 Acceptable Yes None

870.3800

Mammalian 2-

generation 

Reproduction

41510606

&

43366401

Acceptable Yes None

850.3020

Honey bee adult 

acute contact 

toxicity

41510607 Acceptable Yes

Mortality was reported at 24 hours, 

and not 48 hours. No mortalities 

were observed for the technical 

material or acetone control in the 

acute contact (topical application) 

test method. 

Special 

study,

OECD 213

Honey bee adult 

acute oral 

toxicity 

(None) (Not applicable) No

An acute oral toxicity study with the 

adult honey bee is still needed.

Information for other exposure 

routes for adult honey bees (oral 

included) was presented in MRID 

41510607. Mortality was observed 

via the oral exposure route at 24 

hours; however, this study was not a 

guideline quality study for oral 

exposure, and a new study is needed.

Special 

Study 

Honey bee adult 

chronic toxicity (None) (Not applicable) No A chronic oral toxicity study with the adult honey bee is needed.

Special 

study,

OECD 237

Honey bee larvae 

acute oral 

toxicity 

(None) (Not applicable) No An acute oral toxicity study with the 

honey bee larvae is needed.

Special 

Study

Honey bee larvae

chronic toxicity (None) (Not applicable) No A repeat dose toxicity study with honey bee larvae is needed.

Special 

Study

Field trial of 

residues in pollen 

and nectar

(None) (Not applicable) No

A field trial measuring the residues 

of sethoxydim in pollen and nectar is 

needed.

850.3030 

Honey bee 

residue on 

foliage

(None) (Not applicable) No Acute contact LD50 = 10 μg/bee; study 

is triggered, LD50 is < 11 μg/bee. 

Special 

Study,

OECD 75

Semi-field 

testing for 

pollinators

(None) (Not applicable) Tiered 

Approach

Results of the Tier I studies could 

trigger the higher Tier studies (Tier 

II and III), see below.

850.3040 Field testing for 

pollinators (None) (Not applicable) Tiered 

approach

Results of the Tier I studies could 

trigger the higher Tier studies (Tier 

II and III), see below.
33

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Sufficient 

for risk 

assessment?

Current Additional Data Need

850.4100 Seedling 

Emergence

44204801 Supplemental

No

Seedling emergence data is needed 

to assess non-target plants to 

Sethoxydim runoff exposure. It 

needs to be confirmed that the 

available seedling emergence 

toxicity data is from a current market 

TEP. The % a.i. is different (50.5% 

vs. 19.3%) than the test material 

used for the latest vegetative vigor 

study (MRID 47691704). 

43614603 Supplemental

850.4150 Vegetative Vigor

41885906 Supplemental

No, not for 

dicot plants

plus 1 nongrass 

monocot 

species

MRID 41885906, a Tier II 

vegetative vigor study was 

conducted with 95.4% a.i., and not 

with TEP as recommended in the 

CFR. Although the second 

submission MRID 47691704 is a 

Tier II study for monocot plants 

using TEP (19.3% a.i.), POAST®

formulation. No acceptable

vegetative vigor study is available 

for dicot plant species. Although 

sethoxydim, based on MOA is 

expected to impact monocot plants 

more than dicot plants, the available 

data does not represent a realistic 

exposure scenario to dicot plants, 

and a vegetative vigor toxicity study 

with the current market TEP is still 

needed for dicot species and one 

non-grass monocot species. 

47691704 Supplemental

Data Gaps

 OCSPP 850.1300: Freshwater invertebrate life-cycle toxicity study using TGAI

 OCSPP 850.1350: Saltwater invertebrate life-cycle toxicity study using TGAI

 OCSPP 850.1400: Saltwater fish early life-stage toxicity study using TGAI

 OCSPP 850.2100: Acute Oral Toxicity with passerine species

 OCSPP 850.3030: Honey bee Toxicity of residues on foliage; the acute contact LD50 = 

10 μg/bee; the study is triggered, if the LD50 is < 11 μg/bee.

 OECD TG 213 and Non-guideline special studies: Honey bee adult acute and chronic 

oral toxicity studies

 OECD TG 237 and Non-guideline special studies: Honeybee larval acute and chronic 

oral toxicity studies

 Non-guideline special studies: Field trial measuring residues of sethoxydim in pollen and 

nectar

 Special study OECD TG 75 and OSCPP 850.3040: Semi-field testing for pollinators and 

Field testing for pollinators (both studies that are conditionally required based on the 

results of the Tier I – laboratory based studies listed above; if needed these additional 
34

field studies will be discussed pending the results of the acute and chronic adult and 

larval oral toxicity studies to honey bees). 

 OCSPP 850.4100: Terrestrial plant seedling emergence toxicity study with current 

market TEP (typical end-use product). Additional information is needed to determine if 

the studies were conducted with the current market TEP for monocots and dicots. If not, 

a new Tier II seedling emergence study using the current market TEP is needed, and an 

acceptable Tier I test (at least is needed, unless a Tier II study is triggered for dicot plant 

species). 

 OCSPP 850.4150: Terrestrial plant vegetative vigor Tier II toxicity study with (dicots and 

one additional species of monocots) to fulfill guideline. The only available vegetative 

vigor data for dicots was conducted with 95.4% a.i., and not with TEP stated in the CFR. 

Therefore, a vegetative vigor toxicity study with the current market TEP is still needed 

for dicot species. In addition, to fulfill the guideline, one additional monocot species is 

also needed from a different Family (the three species tested represent Family Poaceae

(grasses) only).

Table 13. Submitted Aquatic Ecological Effects Data for Sethoxydim Degradate - Sulfone

Degradate Toxicity Data Gap – Sulfone (terminal degradate, M2-SO2)

 Non-guideline study: aquatic vascular plant toxicity study with a grass species

OCSPP

Guideline Data Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Sufficient 

for risk 

assessment?

Current Additional Data 

Need

NG

Aquatic vascular 

plant Toxicity Test 

using Glyceria 

maxima

(None) (Not applicable) No

Based on the available data for 

the parent sethoxydim, 

degradate data is needed for 

the sethoxydim terminal 

degradate – sulfone. Given the 

MOA of sethoxydim, an 

aquatic vascular plant study 

(using a grass species) is 

needed.
35

Honeybee Toxicity

Although sethoxydim is categorized as practically non-toxic to adult honeybees on contact 

exposure basis, and by extension, to other beneficial terrestrial invertebrates on an acute 

exposure basis, there is considerable uncertainty regarding the potential effects of the compound 

on honeybee larval development and survival as well as potential for chronic effects. Therefore, 

additional data on pollinators is needed to fully characterize the risk associated with sethoxydim 

use to all developmental stages of honeybees, as sensitivity may vary according to life-stage and 

length of exposure (adult vs. larval and acute vs. chronic, respectively). Additional information 

is needed, but uncertainty associated with risks to honey bees need to be evaluated with more 

data to different life stages. Sethoxydim is systemic in plants so exposure via pollen and nectar 

is possible; and therefore, residues of pollen and nectar of crops are an additional data need. 

Open literature data is needed to help better characterize some uncertainties regarding potential 

effects to bees and other non-target terrestrial invertebrates. In addition, higher tier effects 

toxicity tests (i.e., semi-field and/or field studies – Tier II and Tier III, respectively) may be 

needed, based on the results of the larval and chronic adult toxicity studies. Higher tier studies 

are recommended if the ratio of the EEC and larval or adult bee acute LD50>0.4 or the ratio of 

the EEC and the chronic NOAEC>1. Incident data and/or compelling open literature studies can 

also be used to support the need for higher tier studies. Should the screening level risk 

assessment identify that there are risk concerns to bees, mitigation measures may need to be 

considered or the registrant may need to conduct Tier II or Tier III effects studies (e.g. OECD 

Guideline 75 and/or 850.3040 guideline studies) that reduce uncertainty by characterizing 

sethoxydim’s effects at the whole-colony level2.

 

2 http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. 
36

Study Title: Honey Bee Adult Acute Oral Toxicity Test; 

Guideline Number: Special Study – OECD 213; 

Test Substance: Sethoxydim – TGAI

Rationale for Requiring the Data

No data are available with which to assess the toxicity of sethoxydim to honey bees on an acute oral 

exposure basis. Based on the registered use patterns, terrestrial invertebrates have the potential to be 

exposed by contacting and consuming sethoxydim residues. Therefore, the acute oral toxicity test is 

needed for EFED’s current screening-level process for assessing potential effects to terrestrial 

invertebrates.

The Agency finalized its framework to assess risk to pollinators (USEPA, 2014). EPA now requires 

these studies for all use sites where potential exposure to pollinators may occur. Registrants may 

request a waiver of the studies if use practices significantly restrict exposure of the pesticide to bees.

The Agency does not have a guideline for the acute oral honey bee study; however, the OECD 213 

guideline may be useful in protocol development. 

Practical Utility of the Data

How will the data be used and how could the data impact the Agency’s future decisionmaking? 

Data will be used to assess hazard and characterize risk to non-target listed and non-listed terrestrial 

invertebrate species. See Guidance for Assessing Pesticide Risks to Bees (USEPA, 2014) for 

additional details. 

If future endangered species risk assessments are performed without these data, the Agency would 

have to assume that sethoxydim "may affect" endangered terrestrial insects directly (and endangered 

species from other taxa indirectly), and use of sethoxydim might need to be restricted in areas where 

endangered species could be exposed. The lack of these data will limit the flexibility the Agency and 

registrants have in coming into compliance with the Endangered Species Act and could result in use 

restrictions for sethoxydim which are unnecessarily severe. In addition, the lack of these data may 

result in an uncertain assumed risk and potential mitigation of sethoxydim formulations under 

FIFRA.
37

Study Title: Honey Bee Adult Chronic Oral Toxicity Study; 

Guideline Number: Special Study – Non-guideline; 

Test Substance: Sethoxydim – TGAI

Rationale for Requiring the Data

No data have been submitted on the chronic toxicity of sethoxydim to adult honey bees. A study is 

needed to determine the chronic toxicity of the compound to adult honey bees, including mortality 

and sub-lethal effects. This study is part of EFED’s current screening-level process for determining 

potential effects to terrestrial invertebrates. Therefore, a non-guideline honeybee larval toxicity study 

is recommended. Although EPA has not developed a guideline for this study and OECD has yet to 

finalize test guidance for chronic studies, efforts are currently underway to develop standardized 

guidelines for assessing effects from chronic (10-day) exposures to adult bees in the laboratory. The 

registrant should submit a proposed protocol for review and approval by EFED prior to initiation of 

the study. 

The Agency finalized its framework to assess risk to pollinators (USEPA, 2014). EPA now requires 

this study for all use sites where potential exposure to pollinators may occur. Registrants may 

request a waiver of the study if use practices significantly restrict exposure of the pesticide to bees.

Practical Utility of the Data

How will the data be used and how could the data impact the Agency’s future decisionmaking? 

The 10-day toxicity study with young adult bees provides no-observed adverse effect level (NOAEL) 

and lowest-observed adverse effect level (LOAEL) for assessing chronic effects. Data obtained from 

this study will be used in estimating chronic risk to individual adult bees. Risk estimates based on 

these data will be considered along with other lines of evidence to determine whether higher-tier 

studies are needed at the whole colony level.

These data are needed for the registration review risk assessment and for future endangered species 

assessments. The data would allow the Agency better characterize the potential for risk to insects 

(including beneficial pollinators) from the use of sethoxydim. This data may help the Agency 

determine whether any mitigations are needed. If the registration review and any future endangered 

species risk assessments are performed without these data, the Agency would have to assume that 

sethoxydim "may affect" insects, including bees and beneficial pollinators, directly (and endangered 

species from other taxa indirectly), and uses of sethoxydim might need to be restricted in areas where 

pollinators could be exposed.
38

Study Title: Honey Bee Acute and Chronic Larvae Oral Toxicity Study; 

Guideline Number: Special Study – OECD 237 and Non-Guideline; 

Test Substance: Sethoxydim – TGAI

Rationale for Requiring the Data

No data have been submitted on the toxicity of sethoxydim to honey bee larvae. Larval toxicity 

study are needed to determine the toxicity of the compound to developing brood (i.e., larvae and 

pupae), including mortality and adult emergence. This study is part of EFED’s current screeninglevel process for determining potential effects to terrestrial invertebrates. Although EPA has not 

developed a guideline for this study, the 21-day larval toxicity study currently under development by 

OECD provides both acute and chronic oral toxicity data on developing bee brood and (when this 

guidance is finalized) may be used to satisfy the requirement for both acute and chronic oral toxicity 

to honey bee larvae. Registrants are at liberty though to submit a separate acute (single dose) larval 

toxicity study following OECD TG 237 as well as the 21-day repeat dose chronic toxicity study. For 

the chronic toxicity study though, since no guideline is available, it is recommended that the 

registrant should submit a proposed protocol for review and approval by EFED prior to initiation of 

the study.

The Agency finalized its framework to assess risk to pollinators (USEPA, 2014). EPA now requires 

these studies for all use sites where potential exposure to pollinators may occur. Registrants may 

request a waiver of the studies if use practices significantly restrict exposure of the pesticide to bees.

Practical Utility of the Data

How will the data be used and how could the data impact the Agency’s future decisionmaking? 

The 21-day larval toxicity study under development by OECD provides both acute and chronic 

toxicity data on developing bee brood and will yield a median lethal dose (LD50) for assessing acute 

toxicity during the early part of the study as well as a 21-day no-observed adverse effect level 

(NOAEL) and lowest-observed adverse effect level (LOAEL) for assessing chronic effects. Effects 

on survival and development (adult bee emergence) from repeat exposures to the active ingredient 

will be used in estimating chronic risk to individual brood. Risk estimates based on these data will be 

considered along with other lines of evidence to determine whether higher-tier studies are needed at 

the whole colony level.

Data will be used to assess risk to non-target listed and non-listed terrestrial invertebrate species. This 

study would allow the Agency to refine the screening-level hazard assessment for beneficial 

terrestrial invertebrates. The effects data will be used to determine the potential for adverse effects on 

beneficial terrestrial invertebrates through direct effects on larval bees. See Guidance for Assessing 

Pesticide Risks to Bees (USEPA, 2014) for additional details.

These data are needed for the registration review risk assessment and for future endangered species 

assessments. The data would allow the Agency better characterize the potential for risk to insects 

(including beneficial pollinators) from the use of sethoxydim. This data may help the Agency 

determine whether any mitigations are needed. If the registration review and any future endangered 

species risk assessments are performed without these data, the Agency would have to assume that 

sethoxydim "may affect" insects, including bees and beneficial pollinators, directly (and endangered 

species from other taxa indirectly), and uses of sethoxydim might need to be restricted in areas where 

pollinators could be exposed.
39

10. References 

United States Environmental Protection Agency (USEPA). 2004. Overview of the Ecological 

Risk Assessment Process in the Office of Pesticide Programs. U.S. Environmental 

Protection Agency, Office of Pesticide Programs, Environmental Fate and Effects 

Division. Available at http://www.epa.gov/espp/consultation/ecorisk-overview.pdf

USEPA. 2005. Memorandum “EFED’s Reregistration Eligibility Decision Chapter for 

Sethoxydim (Chemical #121001, DP Barcode D312568, D312561).” April 4, 2005. 

Office of Pesticide Programs, U.S. Environmental Protection Agency, Washington D.C.

USEPA. 2006. Memorandum “EFED Risk Assessment for New Uses of Sethoxydim on 

Buckwheat, Okra, Dill, Borage, Root Vegetables, and Turnip Greens.” (DP313456 & 

314420). June 26, 2006). Office of Pesticide Programs, U.S. Environmental Protection 

Agency, Washington D.C.

USEPA. 2007a. ECOTOXicology Database. Office of Research and Development National 

Health and Environmental Effects Research Laboratory’s (NHEERL’s) Mid-Continent 

Ecology Division (MED). http://cfpub.epa.gov/ecotox/

USEPA. 2014a. Guidance for Assessing Pesticide Risks to Bees. U.S. Environmental Protection 

Agency, Office of Pesticide Programs; Health Canada Pest Management Regulatory 

Agency; and California Department of Pesticide Regulation. Jun. 23, 2014. Available at 

http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. 

USEPA. 2014b. Wendel, C. and J. Lin. Sethoxydim: Section 3 New Use Risk Assessment for

IR-4 Petition on Fescue, Oilseeds, Fruits, and Vegetables DP barcode 418333. U.S. 

Environmental Protection Agency, Office of Chemical Safety and Pollution Prevention, 

Environmental Fate and Effects Division. Memorandum to the Registration Division. 

Dec. 19, 2014.

a. Submitted Environmental Fate Studies

MRID Citation Reference

00042821 Nippon Soda Company, Limited (1980) Photodegradation of NP-55 by Sunlight. 

(Unpublished study received Aug 4, 1980 under 0G2396; submitted by BASF Wyandotte 

Corp., Parsippany, N.J.; CDL: 099539-N) 

00047649 Nippon Soda, Limited (1979) Photodegradation of NP-55: RD-7930. (Unpublished study 

received Aug 4, 1980 under 0G2396; submitted by BASF Wyandotte Corp., Parsippany, 

N.J.; CDL:099535-F) 

00130712 BASF Wyandotte Corp. (1983) The Significance of Hydroxylated Residues of Poast 

Herbicide. Interim rept. (Unpublished study received Jul 22, 1983 under 7969-58; 

CDL:251045-A) 
40

MRID Citation Reference

41475207 Soeda, Y.; Shiotani, H. (1988) Sethoxydim--Hydrolysis: Final Report: Lab Project 

Number: NISSO EC-121/BASF 88/5040. Unpublished study prepared by Nippon Soda 

Co., Ltd., Environmental Toxicology Lab. 29 p. 

92166033 Soeda, Y. (1990) BASF Corporation Phase 3 Summary of MRID 41475207. Sethoxydim 

- Hydrolysis: Project EC-121; REG DOC #BASF 90/6040. Prepared by NIPPON SOAD 

CO. LTD. 11 p. 

00042819 Nippon Soda Company, Limited (1979) Hydrolysis of NP-55. (Unpublished study 

received Aug 4, 1980 under 0G2396; submitted by BASF Wyandotte Corp., Parsippany, 

N.J.; CDL:099539-L)

41475208 Soeda, Y.; Shiotani, H. (1988) Sethoxydim: Photodegradation in Water: Final Report: 

Lab Project Number: NISSO EC-125: BASF 88/ 5047. Unpublished study prepared by 

Nippon Soda Co., Ltd., Environmental Toxicology Lab. 35 p. 

92166034 Soeda, Y. (1990) BASF Corporation Phase 3 Summary of MRID 41475208. Sethoxydim 

- Photodegradation in Water: Project EC-125; REG DOC #BASF 90/6041. Prepared by 

NIPPON SODA CO. LTD. 13 p. 

00100540 Huber, R. (1981) Investigations on the Photolytic Degradation of BAS 9052 H (NP 55) 

on Soil: Lab. Communication No. 903. (Unpublished study received Apr 15, 1982 under 

7969-58; prepared by BASF, AG, submitted by BASF Wyandotte Corp., Parsippany, 

N.J.; CDL:070822-E) 

41475209 Soeda, Y.; Shiotani, H. (1988) Sethoxydim: Photodegradation on Soil: Final Report: Lab 

Project Number: NISSO EC-142: BASF 88/51 06. Unpublished study prepared by 

Nippon Soda Co., Ltd., Environmental Toxicology Laboratory. 37 p. 

92166035 Soeda, Y. (1990) BASF Corporation Phase 3 Summary of MRID 41475209. Sethoxydim 

- Photodegradation on Soil: Project EC-142; REG DOC #BASF 90/6042. Prepared by 

NIPPON SODA CO. LTD. 14 p. 

00042480

00100541

Nippon Soda Company, Limited (1980) Photolysis of NP-55 under Anaerobic and 

Aerobic Conditions. (Unpublished study including published data, received Aug 4, 1980 

under 0G2396; submitted by BASF Wyandotte Corp., Parsippany, N.J.; CDL:099539-M)

Redeker, J.; Hamm, R. (1981) Degradation of BAS 9052 H (NP 55) in a Loamy Sand 

under Aerobic, Anaerobic and Sterile-aerobic Conditions: Report No. 1804. (Unpublished 

study received Apr 15, 1982 under 7969-58; prepared by BASF, AG, submitted by BASF 

Wyandotte Corp., Parsippany, N.J.; CDL:070822-F) 

41475210 Shiotani, H. (1989) Sethoxydim: Aerobic Soil Metabolism: Final Report: Lab Project 

Number: NISSO EC-175: BASF 89/5135. Unpublished study prepared by Nippon Soda 

Co., Ltd., Environmental Toxicology Lab. 57 p. 

92166036 Soeda, Y. (1990) BASF Corporation Phase 3 Summary of MRID 41475210. Sethoxydim 

- Aerobic Soil Metabolism: Project EC-175; REG DOC #BASF 90/6043. Prepared by 

NIPPON SODA CO. LTD. 13 p. 

41475211 Soeda, Y.; Shiotani, H. (1989) Sethoxydim: Anaerobic Soil Meta- bolism: Final Report: 

Lab Project Number: NISSO EC-158: BASF 89/ 5000. Unpublished study prepared by 

Nippon Soda Co., Ltd., Environmental Toxicology Lab. 45 p. 
41

MRID Citation Reference

92166037 Soeda, Y. (1990) BASF Corporation Phase 3 Summary of MRID 41475211. Sethoxydim 

- Anaerobic Soil Metabolism: Project EC-158; REG DOC #BASF 90/6044. Prepared by 

NIPPON SODA CO. LTD. 14 p. 

42165603 Shiotani, H. (1991) Sethoxydim: Anaerobic Aquatic Metabolism: Lab Project Number: 

91/5113. Unpublished study prepared by Nippon Soda Co., Ltd. 78 p.

42165604 Shiotani, H. (1991) Sethoxydim: Aerobic Aquatic Metabolism: Lab Project Number: 

89/5194. Unpublished study prepared by Nippon Soda Co., Ltd. 74 p.

00042823 Huber, R. (1980) Investigations into the Aerobic Soil Metabolism of Bas 9052 H/NP 55: 

Laboratory Report No. 1692. (Unpublished study received Aug 4, 1980 under 0G2396; 

prepared by BASF, AG, West Germany, submitted by BASF Wyandotte Corp., 

Parsippany, N.J.; CDL:099539-P) 

00100542 Dams, W. (1981) Adsorption Behaviour of Active Ingredients of Plant Protection 

Products in the System Soil / Water. (Unpublished study received Apr 15, 1982 under 

7969-58; prepared by BASF, AG, submitted by BASF Wyandotte Corp., Parsippany, 

N.J.; CDL:070822-G) 

41475212 Soeda, Y.; Shiotani, H. (1988) Sethoxydim: Batch Equilibrium (Adsorption/ Desorption): 

Final Report: Lab Project Number: NISSO EC-149: BASF 88/5120. Unpublished study 

prepared by Nippon Soda Co., Ltd., Environmental Toxicology Lab. 64 p. 

92166038 Soeda, Y. (1990) BASF Corporation Phase 3 Summary of MRID 41475212. Sethoxydim 

- Batch Equilibrium (Adsorption/Desorption): Project EC- 149; REG DOC #BASF 

90/6045. Prepared by NIPPON SODA CO. LTD. 13 p. 

41510608 Single, Y.; Burkey, J. (1989) Poast Herbicide Field Soil Dissipation Study for Forage 

Crop Use in California--Soil Analyses: Lab Project Number: A8944: BASF 89-5145. 

Unpublished study prepared by Nippon Soda Co., Ltd. in cooperation with BASF. 55 p.

41510609 Single, Y.; Burkey, J. (1989) Poast Herbicide Field Soil Dissipation Study for Row Crop 

Use in California--Soil Analyses: Lab Project Number: A8943: BASF 89-5156. 

Unpublished study prepared by Nippon Soda Co., Ltd. in cooperation with BASF. 57 p. 

41510610 Rotondaro, A. (1989) Sethoxydim Row Crop Use: Terrestrial Field Dissipation: Lab 

Project Number: RCN NO. 88063: PROTOCOL NO. M8714: BASF 89-5147. 

Unpublished study prepared by Pan-Agricultural Labs., Inc. 232 p. 

41510611 Rotondaro, A. (1989) Sethoxydim Forage Crop Use: Terrestrial Field Dissipation: Lab 

Project Number: RCN NO. 88064: M8713: EF-88-28: 89-5160. Unpublished study 

prepared by Pan-Agricultural Labs., Inc. 186 p. 

44311001 Burkey, J. (1997) Freezer Storage Stability of Sethoxydim Residues in Soil: Amendment 

to Final Report: Lab Project Number: 97/5287: A892141: A8921. Unpublished study 

prepared by BASF Corp. 42 p. 

44352401 Beutel, P.; Huber, R. (1982) Investigation of Freezer Storage Stability of BAS 9052H and 

Metabolites in Soil Comparing (carbon 14)-Results Obtained with BASF Total Method 

No. 181: Lab Project Number: 82/10029: 1823. Unpublished study prepared by BASF 

Aktiengesellschaft. 28 p. 
42

MRID Citation Reference

92166039 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 00100543 and 

Related MRIDs 41510608, 41510609, 41510610. Poast Herbicide - Terrestrial Field 

Dissipation Studies in: California, Minnesota, Illinois and Mississippi: REG DOC #BASF 

90/6046. Prepared by BASF RESEARCH STATION. 23 p.

42165605 Eubanks, M. (1991) Poast Herbicide (Sethoxydim) Aquatic Dissipation Study: Lab 

Project Number: 91/5153. Unpublished study prepared by BASF Corp. Chemicals 

Division and Others. 535 p.

00042825

92166040

Nippon Soda Company, Ltd.

Looper, G.; Winkler, V. (1990) BASF Corporation Phase 3 Summary of MRID 00042825 

and Related MRIDs 41510612. Sethoxydim: Confined Rotational Crops: REG DOC 

#BASF 90/6070 and #81/5053. Prepared by NIPPON SODA CO. LTD. 27 p.

41510612 Clark, J.; Adamson, S. (1981) Uptake of BAS 9052-|Carbon 14| (NP-55) Residues by 

Rotational Crops Under Field Conditions: Lab Project Number: PM-33: 81-5053. 

Unpublished study prepared by BASF Corp. 20 p. 

00087573 Clark, J.R.; Adamsbaum, S.N. (1981) Uptake of BAS 9052H-^14IC (NP-55) Residues by 

Rotational Crops under Field Conditions: Laboratory Report No. PM-33. (Unpublished 

study received Dec 2, 1981 under 7969-EX-14; submitted by BASF Wyandotte Corp., 

Parsippany, N.J.; CDL:246346-A). 

42118001

A-B

McKenna, E. (1991) Bioaccumulation and Metabolism of |carbon 14|- Sethoxydim in 

Bluegill Sunfish: Lab Project No: M9018: M9121. Unpublished study prepared by BASF 

Corp. 112 p. 

00100537 Vilkas, A.G.; Kuc, W.J. (1981) 14C-BAS 9052: Bluegill Sunfish, Lepomis macrochirus 

Rafinesque; Bioconcentration Study: UCCES Project No. 11507-81. (Unpublished study 

received Apr 15, 1982 under 7969-58; prepared by Union Carbide Corp. Environmental 

Services, submitted by BASF Wyandotte Corp., Parsippany, N.J.; CDL:070822-B).

00100538 Vilkas, A.G.; Kuc, W.J. (1981) 14C-BAS 9052: Channel Catfish, Ictalurus punctatus 

(Rafinesque), Bioconcentration Study: UCCES Project No. 11507-82. (Unpublished 

study received Apr 15, 1982 under 7969-58; prepared by Union Carbide Corp. 

Environmental Services, submitted by BASF Wyandotte Corp., Parsippany, N.J.; 

CDL:070822-C).

41475213 Akesson, N. (1982) Poast Simulated Field Drift Trials: Final Report: Lab Project 

Number: UC DAVIS RPT. NO. 1: BASF 85/5046. Unpublished study prepared by Univ. 

of California, Davis, Dept. of Agric. Engineering. 59 p.

41475213 Akesson, N. (1982) Poast Simulated Field Drift Trials: Final Report: Lab Project 

Number: UC DAVIS RPT. NO. 1: BASF 85/5046. Unpublished study prepared by Univ. 

of California, Davis, Dept. of Agric. Engineering. 59 p. 

92166050 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 41475213. 

Sethoxydim - Simulated Field Trials in California: BASF DOC No. 85/5046, BASF 

90/6048. Prepared by UNIV. OF CALIFORNIA, DEPT. OF AGR. ENGINEERING. 

17p. 
43

MRID Citation Reference

100543 Craven, D.A. (1982) Determination of BAS 9052 H and Its Metabolite Residues in Soil 

Samples: Report No. CR-5; BWC Project No. IX- 2-G-229. (Unpublished study, 

including analytical method no. 31, received Apr 15, 1982 under 7969-58; prepared by 

Craven Laboratories, Inc., submitted by BASF Wyandotte Corp., Parsippany, N.J.; 

CDL:070822-H).

100544 Nippon Soda Company, Limited (1981) Octanol / Water Partition Co- efficient of NP-55 

Related Compounds. (Unpublished study received Apr 15, 1982 under 7969-58; 

submitted by BASF Corp., Parsippany, N.J.; CDL:070822-I).

40195103 Paulick, R. (1987) Freezer Storage Stability of Sethoxydim Metabolites MSO and 5-OHMSO2 in Potatoes: BASF Doc. No. 87/5008: Rept. No. A8705. Unpublished study 

prepared by Craven Laboratories, Inc. 30 p. 

b. Submitted Ecological Toxicity Studies

MRID Citation Reference

00042813 Fink, R.; Beavers, J.B.; Grimes, J.; et al. (1979) Final Report: Acute Oral LD50-Mallard

Duck: Project No. 147-120. (Unpublished study received Aug 4, 1980 under 0G2396; 

prepared by Wildlife International, Ltd. and Washington College, submitted by BASF 

Wyandotte Corp., Parsippany, N.J.; CDL:099539-D). 

92166002 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 00042813. Sethoxydim 

- Avian Acute LD 50 Test - Mallard Duck: Project 147- 120. Prepared by WILDLIFE 

INTERNATIONAL LTD. 16 p.

00042814 Fink, R.; Beavers, J.B.; Grimes, J.; et al. (1979) Final Report: Eight-Day Dietary LC50-

Bobwhite Quail: Project No. 147-118. (Unpublished study received Aug 4, 1980 under 

0G2396; prepared by Wildlife International, Ltd. and Washington College, submit- ted by 

BASF Wyandotte Corp., Parsippany, N.J.; CDL:099539-E). 

00072862 Fink, R.; Beavers, J.B.; Grimes, J.; et al. (1979) Final Report: Eight-Day Dietary LC50-

Mallard Duck: Project No. 147-119. (Un- published study received Aug 4, 1980 under 

0G2396; prepared by Wildlife International, Ltd. and Washington College, submitted by 

BASF Wyandotte Corp., Parsippany, N.J.; CDL:099539-F). 

92166003 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 00042814 and Related 

MRIDs 00072862. Sethoxydim - Avian Acute Dietary LC50 Test Mallard Duck and 

Bobwhite Quail: Project 147-118 and Project 147-119; REG DOC #BASF 90/6002. 

Prepared by WILDLIFE INTERNATIONAL LTD. 16 p.

00162823 Beavers, J. (1986) Pyridate Technical: A Pilot Reproduction Study with the Bobwhite 

(Colinus virginianus): Final Report: Wildlife International Ltd. Project No. 217-105. 

Unpublished study pre- pared by Wildlife International Ltd. 27 p. 

44003401 Munk, R. (1996) Sethoxydim: One-Generation Reproduction Study on the Bobwhite Quail 

(Colinus virginianus) by Administration in the Diet: Lab Project Number: 96/10152: 

08B0155/926020: PCP03583. Unpublished study prepared by BASF Aktiengesellschaft. 

382p.
44

MRID Citation Reference

44003402 Beavers, J.; Chafey, K.; Mitchell, L. et al. (1996) Sethoxydim: A Reproduction Study with 

the Mallard: Lab Project Number: 96/10105: 147-168: 72W0155/929040. Unpublished 

study prepared by Wildlife Int'l. Ltd. 153 p. 

48000901 Zok, S. (2009) BAS 562 H (Sethoxydim) - 1-Generation Reproduction Study on the Mallard 

Duck (Anas platyrhynchus) by Administration in the Diet. Project Number: 

72W0530/085045, 302019, 2009/1100351. Unpublished study prepared by BASF SE: 

Experimental Toxicology and Ecology. 403 p.

41885901 Bowman, J.; Howell, R. (1991) Acute Toxicity of Poast Herbicide (BAS 9052 06 H) to 

Blugeill (Lepomis macrochirus): Lab Project Number: 90/5135. Unpublished study prepared 

by ABC Laboratories, Inc. 28 p. 

41885902 Bowman, J.; Howell, R. (1991) Acute Toxicity of Poast Herbicide (BAS 9052 06 H) to 

Rainbow Trout (Oncorhynchus mykiss): Lab Project Number: 90/5136. Unpublished study 

prepared by ABC Laboratories, Inc. 28 p. 

92166004 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 00072863. Sethoxydim 

Acute Toxicity Test for Freshwater Fish - Bluegill Sunfish: UCCES Project No. 11506-17-

24; REG DOC BASF 90/6003. Prepared by UNION CARBIDE CORP. 11p. 

00042815 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Bas 9052 H Technical (97.3%) to 

the Rainbow Trout, Salmo gairdneri Richardson: UCES Project No. 11507-17-25. 

(Unpublished study received Aug 4, 1980 under 0G2396; prepared by Union Carbide Corp., 

submitted by BASF Wyandotte Corp., Parsippany, N.J.; CDL:099539-H).

92166005 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 00042815. Sethoxydim 

Acute Toxicity for Freshwater Fish - Rainbow Trout UCCES Project No. 11506-17-25; 

REG DOC #BASF 90/6004. Prepared by UNION CARBIDE CORP. 12 p.

47691701 Aufderheide, J. (2009) BAS 562 05 H (POAST): Acute Toxicity Test to the Fathead 

Minnow, Pimephales promelas, Determined Under Flow-Through Test Conditions. Project 

Number: 64117, 356157, 2009/7000068. Unpublished study prepared by ABC Laboratories, 

Inc. 46 p.

00072863 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Tech BAS 9052 Lot PN-10-1 to the 

Bluegill Sunfish, Lepomis macrochirus Rafinesque: UCES Project No. 11506-17-24. 

(Unpublished study received Aug 4, 1980 under 0G2396; prepared by Union Carbide Corp., 

submitted by BASF Wyandotte Corp., Parsippany, N.J.; CDL: 099539-G).

41885903 Blasberg, J.; Hicks, S.; Howell, R. (1991) Acute Toxicity of Poast Herbicide to Daphnia 

magna: Lab Project Number: 90/5137. Unpublished study prepared by ABC Laboratories, 

Inc. 29 p. 

00042816 Vilkas, A.G.; Morrissey, A.E. (1979) The Acute Toxicity of Bas 9052 H Technical (97.3%) 

Lot No. 23-9051-TA to the Water Flea Daphnia magna Straus: UCES Project No. 11506-17-

23. (Unpublished study received Aug 4, 1980 under 0G2396; prepared by Union Carbide 

Corp., submitted by BASF Wyandotte Corp., Parsippany, N.J.; CDL:099539-I).
45

MRID Citation Reference

92166006 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 00042816. Sethoxydim

Acute Toxicity Test for Freshwater Invertebrates - Water Flea: UCCES Project No. 11506-

17-23; BASF DOC # 90/6005. Prepared by UNION CARBIDE CORP. 11 p.

41510602 Ward, T.; Boeri, R. (1989) Static Acute Toxicity of Poast Herbicide to the Sheepshead 

Minnow, Cyprinodon variegatus: Lab Project Number: 8902-B: BASF 89-5162. 

Unpublished study prepared by EnviroSystems. 28 p.

41510603 Ward, T.; Boeri, R. (1989) Static Acute Toxicity of Poast Herbicide to the Blue Crab, 

Callinectes sapidus: Lab Project Number: 8903-B: BASF 89-5163. Unpublished study 

prepared by EnviroSystems. 28 p.

41510604 Ward, T.; Boeri, R. (1989) Static Acute Toxicity of Poast Herbicide to the Mysid, 

Mysidopsis bahia: Lab Project Number: 8901-B: BASF 89-5164. Unpublished study 

prepared by EnviroSystems. 28 p.

41607207 Ward, T.; Boeri, R. (1990) Static Acute Toxicity of Poast Herbicide (...) to Bivalve Mollusc 

Embryos and Larvae: Lab Project Number: 90/5045. Unpublished study prepared by 

EnviroSystem Div., Resource Analysts, Inc. 22 p. 

42315101 Ward, T.; Boeri, R. (1992) Static Acute Toxicity of Sethoxydim (BAS 9052 H) to the 

Sheepshead Minnow, Cyprinodon variegatus: Lab Project Number: 91129-B: 39624. 

Unpublished study prepared by Resource Analysts, Inc. and ABC Laboratories. 43 p.

42315102 Ward, T.; Boeri, R. (1992) Static Acute Toxicity of Sethoxydim (BAS 9052 H) to the 

Mysid, Mysidopsis bahia: Lab Project Number: 91127-B: 39623. Unpublished study 

prepared by Resource Analysts, Inc. and ABC Laboratories. 43 p.

42537401 Lintott, D. (1992) Sethoxydim-Technical (BAS 562 H): Acute Toxicity to Embryos and 

Larvae of the Eastern Oyster, Crassostrea virginica under Static Test Conditions: Lab 

Project Number: 92/5157: 92079: J9203014. Unpublished study prepared by Toxikon 

Environmental Sciences and BASF. 45 p. 

92166007 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 41510602. Poast 

Herbicide - Acute Toxicity Test for Estuarine Fish - Sheepshead Minnow: Project No. 8902-

B; REG DOC #BASF 90/6006. Prepared by ENVIROSYSTEMS DIV., RESOURCE 

ANALYSTS INC. 13 p. 

92166008 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 41510603. Poast 

Herbicide - Acute Toxicity Test for Estuarine Species - Blue Crab: Project No. 8903-B; 

REG DOC #BASF 90/6007. Prepared by ENVIROSYSTEMS DIV. RESOURCE 

ANALYSTS. 13 p. 

92166009 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 41510604. Poast 

Herbicide - Acute Toxicity Test for Shrimp - Mysid: Project No. 8901-B; REG DOC 

#BASF 90/6008. Prepared by ENVIROSYSTEMS DIV. RESOURCES ANALYSTS, INC. 

13 p.
46

MRID Citation Reference

43614601 Graves, W.; Mank, M.; Swigert, J.; et al. (1995) Sethoxydim: An Early Life-Stage Toxicity 

Test with the Sheepshead Minnow (Cyprinodon variegatus): Lab Project Number: 95/5014: 

147A-123: A008.068. Unpublished study prepared by Wildlife International Ltd. and 

Huntingdon Analytical Services. 107 p. 

43614602 Boeri, R.; Kowalski, P.; Ward, T.; et al. (1995) Chronic Toxicity of Sethoxydim to the 

Mysid, Mysidopsis bahia: Lab Project Number: 95/5030: A008.059: 485-BA. Unpublished 

study prepared by T.R. Wilbury Labs, Inc. and Huntingdon Analytical Services. 95 p. 

47691702 Aufderheide, J. (2009) BAS 562 H: Early Life-Stage Toxicity Test with the Fathead 

Minnow, Pimephales promelas, Under Flow-Through Test Conditions. Project Number: 

64012, 302018, 2009/7000078. Unpublished study prepared by ABC Laboratories, Inc. 69 p.

47691703 Aufderheide,J. (2009) BAS 562 05 H (POAST): Early Life-Stage Toxicity Test with the 

Fathead Minnow, Pimephales promelas, Under Flow-Through Conditions. Project Number: 

64010, 346309, 2009/7000077. Unpublished study prepared by ABC Laboratories, Inc. 83 p.

44204801 Maggi, V.; Jackson, S. (1994) Tier I: Determination of the Phytotoxic Effects of Poast on 

Seed Germination/Seedling Emergence of Nontarget Plants: Final Report: Lab Project 

Number: ER93043: 94/5191: CAR 166-93. Unpublished study prepared by California 

Agricultural Research, Inc. 122 p.

41400103 Hughes, J. (1980) Toxicity of BAS 9052 O H (Poast) to Duckweed: Lab Project Number: 

85/5052. Unpublished study prepared by Union Carbide Corp. Environmental Services. 33p. 

41400104 Hughes, J. (1981) Toxicity of BAS 9052 O H (Poast) to Algae and Duckweed: Lab Project 

Number: 85/5051. Unpublished study pre- pared by Union Carbide Corp., Environmental 

Services. 10 p. 

41400105 Hughes, J. (1981) Toxicity of BAS 9052 O H (Poast) to Skeletonema costatum: Lab Project 

Number: 85/5054. Unpublished study prepared by Union Carbide Corp. Environmental 

Services. 26 p. 

41400106 Hughes, J. (1980) Toxicity of BAS 9052 O H (Poast) to Selenastrum capricornutum: Lab 

Project Number: 85/5056. Unpublished study prepared by Union Carbide Corp. 

Environmental Services. 26 p. 

41400107 Hughes, J. (1981) Toxicity of BAS 9052 O H (Poast) to Navicula seminulum Grun: Lab 

Project Number: 85/5053. Unpublished study prepared by Union Carbide Corp. 

Environmental Services. 27 p. 

41400108 Hughes, J. (1981) Toxicity of BAS 9052 O H (Poast) to Anabaena flos-aquae: Lab Project 

Number: 85/5055. Unpublished study pre- pared by Union Carbide Corp. Environmental 

Services. 27 p.

41400101 Krieg, K. (1980) Seed Germination Tests for BAS 9052 O H (Poast): Tier 2: Lab Project 

Number: 85/5049. Unpublished study prepared by BASF Aktiengesellschaft, Agricultural 

Research Station. 18 p. 
47

MRID Citation Reference

41400102 Ludwig, J. (1980) Poast Phytotoxicity Studies: Lab Project Number: 85/5047. Unpublished 

study prepared by BASF Wyandotte Corp., Agricultural Research Farm. 23 p. 

41885906 Chetram, R. (1991) Tier 2 Vegetative Vigor Nontarget Phytotoxicity Study Using 

Sethoxydim (BAS 9052 H Tech.a.i): Lab Project Number: 90/5138. Unpublished study 

prepared by Pan-Agricultural Labs, Inc. 150 p. 

43614603 Maggi, V.; Jackson, S. (1994) Determination of the Phytotoxic Effects of Poast on Seed 

Germination/Seedling Emergence of Nontarget Gramineae Plants: Final Report: Lab Project 

Number: 94/5190: CAR 168-93: 93095. Unpublished study prepared by California 

Agricultural Research, Inc. 118 p. 

43614604 Jackson, S.; Maggi, V. (1994) Determination of the Phytotoxic Effects of Poast on 

Vegetative Vigor of Nontarget Gramineae Plants: Final Report: Lab Project Number: 

95/5029: CAR 175-94: ER95003. Unpublished study prepared by California Agricultural 

Research, Inc. 131 p. 

92166030 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 41400101. Sethoxydim 

Seed Germination/Seedling Emergence Nontarget Phytotoxicity Study: Project 85/5049; 

REG DOC #BASF 90/6037. Prepared by BASF AKTIENGESELLSCHAFT. 14 p. 

47691704 Bergfield, A. (2009) BAS 562 05 H (POAST): Effects on the Vegetative Vigor of NonTarget Terrestrial Plants (Tier II). Project Number: 64011, 302015, 2009/7000073. 

Unpublished study prepared by ABC Laboratories, Inc. 64 p.

43614605 Thompson, S.; Swigert, J.; Jackson, S. (1994) Sethoxydim 99.8% Tech: A Tier II 14-Day 

Toxicity Test with Duckweed (Lemna gibba): Lab Project Number: 94/5067: 147A-109A: 

A008.047. Unpublished study prepared by Wildlife International Ltd. and Huntingdon 

Analytical Services. 63 p. 

43614606 Thompson, S.; Swigert, J.; Jackson, S. (1994) Sethoxydim 99.8% Tech: A Tier II 5-Day 

Toxicity Test with the Freshwater Diatom (Navicula pelliculosa): Lab Project Number: 

94/5068: 147A-110: ER94015. Unpublished study prepared by Wildlife International Ltd. 

and Huntingdon Analytical Services. 60 p. 

43614607 Thompson, S.; Roberts, C.; Swigert, J.; et al. (1994) Sethoxydim 99.8% Tech: A Tier II 5-

Day Toxicity Test with the Freshwater Alga (Selenastrum capricornutum): Lab Project 

Number: 94/5069: 147A-112: A008.049. Unpublished study prepared by Wildlife 

International Ltd. and Huntingdon Analytical Services. 59 p. 

43614608 Thompson, S.; Swigert, J.; Jackson, S. (1994) Sethoxydim 99.8% Tech: A Tier II 5-Day 

Toxicity Test with the Freshwater Alga (Anabaena flos-aquae): Lab Project Number: 

94/5071: 147A-111B: A008.050. Unpublished study prepared by Wildlife International Ltd. 

and Huntingdon Analytical Services. 60 p.

43626101 Thompson, S.; Swigert, J. (1994) Sethoxydim 99.8% Tech: A Tier II 5-Day Toxicity Test 

with the Marine Diatom (Skeletonema costatum): Lab Project Number: 147A-108: 93129: 

ER 94016. Unpublished study prepared by Wildlife International Ltd. and Huntingdon 

Analytical Services. 59 p. 
48

MRID Citation Reference

48000902 Knauert, S. 2009. Effect of BAS 562 05 H on growth of the aquatic plant Glyceria maxima 

(including Amendment No. 1). Unpublished study performed by BASF SE, BASF 

Agricultural Center Limburgerhof, Crop Protection Division, Ecology and Environmental 

Analytics, Limburgerhof, Germany. Study Identification No. 302016. Study sponsored by 

BASF Corporation, Research Triangle Park, North Carolina. Study completed October 1, 

2009. Amendment No. 1 completed February 17, 2010.

92166031 Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 41400103 and Related 

MRIDs 41400104, 41400105, 41400106, 41400107, 41400108. Poast Herbicide - Growth 

and Reproduction of Aquatic Plants - Duckweed, Green Alga, Blue-green Alga, Marine 

Diatom and Freshwater Diatom: Projects 11507-83-01, 11507-83-02, 11507-83-03, 11507-

83-04 11507-83-05; REG DOC #BASF 90/6038. Prepared by UNION CARBIDE CORP. 

16p.

41510607 Nippon Soda Co., Ltd. (1981) Effects of NP-55 on Honey Bees: Lab Project Number: BASF 

81/9013. Unpublished study prepared by Nippon Soda Co., Ltd. 9 p. 

92166032 Soeda, Y. (1990) BASF Corporation Phase 3 Summary of MRID 41510607. Sethoxydim -

Effects on Honey Bees: Project RD-8164; REG DOC #BASF 90/6039. Prepared by 

NIPPON SODA CO. LTD. 11 p. 

00042817 Nippon Soda Company, Limited (1980) The Influence of NP-55 on Honey Bees. Prelim. 

rept. (Unpublished study received Aug 4, 1980 under 0G2396; submitted by BASF 

Wyandotte Corp., Parsippany, N.J.; CDL:099539-J).

00042812 Clark, J.R. (1980) Wildlife Toxicology: Impact of Bas 9052 O H on Fish, Wildlife, and 

Bees. Summary of studies 099539-D through 099539-J. (Unpublished study received Aug 4, 

1980 under 0G2396; submitted by BASF Wyandotte Corp., Parsippany, N.J.; CDL: 099539-

C). 

00100536 BASF Wyandotte Corporation (1982) Nontarget Hazard Assessment: Impact of Poast on 

Fish, Wildlife and Bees. Summary of studies 070822-B and 070822-C. (Unpublished study 

received Apr 15, 1982 under 7969-58; CDL: 070822-A). 

48033008 Kojima, H.; Katsura, E.; Takeuchi, S.; et al. (2004) Screening for Estrogen and Androgen 

Receptor Activities in 200 Pesticides by In Vitro Reporter Gene Assays Using Chinese 

Hamster Ovary Cells. Environmental Health Perspectives 112(5): 524-531.

00045847 Nishibe, T.; Souma, S. (1979) Acute Oral Toxicity of NP-55 in Rats. (Unpublished study 

received Aug 4, 1980 under 0G2396; prepared by Nippon Soda Co., Ltd., Japan, submitted 

by BASF Wyandotte Corp., Parsippany, N.J.; CDL:099536-C).

00046326 Gelbke,?; Jackh,?; Freisberg,?. (1980) Report on the Study of the Acute Oral Toxicity of Bas 

9052 O H in the Rat. (Translation from German; unpublished study received Sep 18, 1980 

under 7969-EX-14; prepared by BASF, AG, submitted by BASF Wyandotte Corp., 

Parsippany, N.J.; CDL:243319-A).
49

MRID Citation Reference

00045849 Nishibe, T.; Nukui, T. (1979) Acute Inhalation Toxicity Study of NP-55 on Rat. 

(Unpublished study received Aug 4, 1980 under 0G2396; prepared by Nippon Soda Co., 

Ltd., Japan, submitted by BASF Wyandotte Parsippany, N.J.; CDL:099536-E).

41510606 Marroquin, F. (1983) Two Generation Reproduction Study of NP-55 in Rats: Lab Project 

Number: 449-009: BASF 84-0068. Unpublished study prepared by International Research 

and Development Corp. 377 p.

43366401 Grossi, I. (1994) Determination of Homogeneity and Stability of NP-55 (Sethoxydim) in 

Dietary Mixtures: Lab Project Number: 449/021: 94/5111. Unpublished study prepared by

International Research and Development Corp. 75 p.
50

APPENDIX A. SLUA Summary Table for Sethoxydim

Date: May 19, 2014

Screening Level Estimates of Agricultural Uses of Sethoxydim (121001)

Sorted Alphabetically

(Reporting Timeframe: 2004-2012)

Crop

lbs. A.I.

Percent Crop Treated

Average Maximum

1 Alfalfa 10,000 <1 <2.5

2 Almonds 3,000 <2.5 5

3 Apples <500 <1 <2.5

4 Apricots <500 <2.5 10

5 Artichokes <500 <2.5 <2.5

6 Asparagus 1,000 5 10

7 Beans, Green 6,000 10 15

8 Blueberries 2,000 5 10

9 Broccoli 1,000 <2.5 5

10 Brussels Sprouts* <500 N/A N/A

11 Cabbage 1,000 5 10

12 Caneberries <500 5 10

13 Canola 1,000 <2.5 <2.5

14 Cantaloupes 2,000 5 25

15 Carrots <500 <2.5 5

16 Cauliflower <500 5 10

17 Celery <500 <2.5 <2.5

18 Cherries <500 <2.5 <2.5

19 Corn 3,000 <1 <2.5

20 Cotton 4,000 <1 <2.5

21 Cucumbers 1,000 5 10

22 Dry Beans/Peas 100,000 30 35

23 Eggplant <500 5 10

24 Fallow <500 <1 <2.5

25 Garlic <500 <2.5 5

26 Grapefruit <500 <2.5 <2.5

27 Grapes 4,000 <2.5 5

28 Hazelnuts <500 <2.5 <2.5

29 Lettuce 1,000 <2.5 10

30 Oats <500 <1 <2.5
51

Crop

lbs. A.I.

Percent Crop Treated

Average Maximum

31 Onions 3,000 5 15

32 Oranges 8,000 <2.5 5

33 Peaches <500 <1 <2.5

34 Peanuts 10,000 5 10

35 Pears <500 <2.5 <2.5

36 Peas, Green 3,000 5 15

37 Pecans 1,000 <2.5 <2.5

38 Peppers 1,000 5 15

39 Pistachios <500 <1 <2.5

40 Plums/Prunes <500 <1 <2.5

41 Potatoes 4,000 <2.5 5

42 Pumpkins 1,000 5 10

43 Soybeans 30,000 <1 <2.5

44 Spinach <500 <2.5 <2.5

45 Squash 1,000 5 10

46 Strawberries <500 <2.5 10

47 Sugar Beets 6,000 <2.5 5

48 Sunflowers 9,000 5 10

49 Sweet Corn 2,000 <2.5 5

50 Tobacco 2,000 5 10

51 Tomatoes 2,000 <2.5 5

52 Walnuts 1,000 <2.5 5

53 Watermelons 4,000 10 20

54 Wheat 1,000 <1 <2.5

All numbers rounded.

<500: indicates less than 500 pounds of active ingredient.

 <2.5: indicates less than 2.5 percent of crop is treated.

* CA data only; 80% or more of U.S. acres are in California

SLUA data sources include: 

USDA-NASS (United States Department of Agriculture's National Agricultural Statistics Service) 

Private Pesticide Market Research

California Department of Pesticide Regulation (DPR) Pesticide Use Reporting (PUR) database

These results reflect amalgamated data developed by the Agency and are releasable to the public.
52

APPENDIX B. Sethoxydim Ecotoxicity Data

Toxicity to Terrestrial Organisms

Avian Toxicity 

Table B-1. Acute Oral Toxicity of Sethoxydim to Birds

Species % ai LD50

(mg a.i./kg-bw)

Toxicity 

Category

MRID No.

Author, Year

Study

Classification

Mallard duck

(Anas platyrhynchos)

97.3 >25101 Practically 

non-toxic

00042813

Fink, 1979 Acceptable

1 No mortality, or behavioral abnormalities at test concentrations tested. There was a reduction in feed consumption at the 

1000 and 1590 mg a.i./kg-bw dose levels.

Table B-2. Subacute Dietary Toxicity of Sethoxydim to Birds

Species % ai LC50

(ppm a.i.)1

Toxicity 

Category

MRID No.

Author, Year

Study 

Classification

Northern bobwhite quail

(Colinus virginianus)

97.3 >56202 Practically 

non-toxic

00042814

Fink, 1979 Acceptable

Mallard duck

(Anas platyrhynchos)

97.3 >56203 Practically 

non-toxic

00072862

Fink, 1979 Acceptable

1 Test organisms observed an additional three days while on untreated food.

2 There were no mortalities in any treatment concentrations that were tested; however, there were four mortalities (8%) in 

the control. The mortalities in the control were believed to be due to toe picking. Two other groups also showed evidence 

of toe and nostril picking, which may have affected the average body weight gain observed. All other birds were normal in 

both appearance and behavior during the test period. 

3 No mortality or overt toxicity occurred in any concentration that was tested, including the control.

Table B-3. Chronic Toxicity of Sethoxydim to Birds

Species % ai NOAEC/LOAEC

(ppm a.i.) Endpoints MRID No.Author, Year

Study 

Classification

Bobwhite Quail

(Colinus virginianus)

96.8 1000/≥10001 No treatment related effects 44003401

Munk, 1996 Acceptable

Mallard duck 

(Anas platyrhynchos)

96.8 <100/1002 Number of normal 

hatchlings

44003402

Beavers, 1996 Supplemental

Mallard duck 94.8 466/9533

Proportion of number of 

hatchlings to live 3-week 

(21-d) viable embryos

48000901

Zok, 2009 Acceptable

1 No treatment related mortalities or signs of overt toxicity were observed at any test concentration when compared to the control 

group. Adult females from all three test concentrations laid fewer eggs than the control birds; however, this difference was not 

considered treatment related since the response was not dose dependent. 

2 No NOAEC was observed as there were significant reductions in the number of normal hatchlings at the 100 and 500 ppm 

concentrations and a 30% reduction in normal hatchlings at the 1000 ppm level when compared to the control were observed. 

The 100 ppm was the lowest test concentration that was tested. 

3 No treatment related mortalities were observed, although one (1) mortality was observed in the 500 ppm a.i. dose level without 

prior clinical signs of toxicity.
53

Mammalian Toxicity 

Table B-4. Acute and Chronic Toxicity of Sethoxydim to Mammals

Species % ai Test 

Type Toxicity Value Most SensitiveEndpoints

MRID No.

Author, Year

Study 

Classification

Laboratory rat 

(Rattus norvegicus)

(Sprague-Dawley)

94-99 Acute 

Oral

LD50 = 2676 (F);

3125 (M)

mg a.i./kg-bw1

Mortality

00045847

Nishibe & 

Souma, 1979

Acceptable

Laboratory rat 

(Sprague-Dawley) 18 Acute Oral

LD50 = 4385 (F);

5000 (M)

mg a.i./kg-bw2

Mortality and clinical signs 

of toxicity2

00046326

Gelbke, et al., 

1980

Acceptable

Laboratory rat 

(Sprague-Dawley)

94-99 Acute 

Inhal.

LC50 (4 hrs) = 6.03 

(M); 6.28 (F) mg/L3

No mortality, some clinical 

signs of toxicity were 

observed3

00045849

Nishibe & 

Nukui, 1979

Acceptable

Laboratory rat 

(Charles River CD)

94-99 2-gen 

repro.

NOAEC/LOAEC = 

600/3000 ppm

(30/150 mg/kg/day)4

Offspring, developmental: tail 

abnormalities in F1a and F1b

offspring; malformations 

described as threadlike tail, no 

anal opening, malformed 

hindlimb, malpositioned 

kidneys, cleft lip, cleft palate, 

and microphthalma. No 

Systemic or Reproductive 

effects observed.

4

41510606 

&

43366401

Marroquin, 

1983

&

Grossi,

1994

 Acceptable

1 Signs of toxicity observed included: ataxia, sedation, hypotonia, lacrymation, salivation, tremor, paralysis, fall of body temperature, 

and urine incontinence diarrhea.

2 Signs of toxicity observed included: Dyspnea, apathy, spastic gait, and poor general state were symptoms in all dosage groups. 

Abnormal position, staggering, piloerection, and salivation were observed in the four (4) highest dosage groups; atonia, pain reflex 

absent, narcotic like state, and exciccosis were present in the three (3) highest dosage groups. At necropsy, dead animals showed heard 

dilatation, acute congestive hyperemia with atonic, diarrheaic intestine; and sacrificed animals showed several cases of adhesions of 

forestomach to liver, spleen, peritoneum with thickened forestomach and focal thickenings. 

3 The exposure was 4 hours in duration. No mortalities occurred in any treatment or control groups. Lacrymation and salivation were 

observed at 2 hours, lasting to 4 hours after inhalation exposure in both experimental and vehicle control groups. Body weights in all 

groups decreased at 4 hours, but recovered afterwards, with stunted recovery in experimental animals. No other toxic effects were 

observed. 

4 No dose-related gross or microscopic lesions, or developmental variations (cannibalism complicated the evaluation). No parental 

toxicity was observed at either the mid or high-dose, and there were problems with the feed formulation stability, homogeneity, and 

dose concentration that made it impossible to ascertain the actual doses used. However, additional information was submitted by the 

registrant, and the highest dose used in the reproduction study was 3000 ppm administered in the diet, or approx. 150 mg/kg/day. This 

is about one-fourth the gavage LEL of 650 mg/kg/day in a rat developmental toxicity study (Project No. 92-3826) – a maternally toxic 

dose that had not effect on reproduction. Taking the differences in dosing regimens and durations, HED presented in their September 

1994 memo that the 3000 ppm dose was defined as a free-standing NOEL, and the reproduction study was upgraded to COREminimum. 

Terrestrial Invertebrate Toxicity

Table B-5. Acute Contact Toxicity of Sethoxydim to Terrestrial Invertebrates

Species % ai LD50

(μg/bee)1 Toxicity Category MRID No.Author, Year

Study 

Classification

Honey bee 

(Apis mellifera)

98.9 10 Moderately toxic 41510607

Nippon Soda Co., 1981 Acceptable

1 Mortality was reported at 24 hours, and not 48 hours. No mortalities were observed for the technical material or acetone control in 

the acute contact (topical application) test method. Information for other exposure routes for adult honey bees is available, as the 

study conducted exposure to adult bees via spray and oral exposure routes 10% mortality was observed via the spray exposure route, 

and 5% mortality was observed via the oral exposure route at 24 hours, respectively, but are not a guideline quality study. MRID 

00042817 for honey bees are preliminary trials for this study.
54

Toxicity to Terrestrial Plants

Table B-6. Non-target Terrestrial Plant Seedling Emergence Toxicity (Tier I)

Species % ai Dose

(lbs a.i./A)

% Response and 

Endpoint Affected

MRID No.

Author, Year

Study 

Classification

Monocot- Corn 50.5 0.47 15 (phytotoxicity)

44204801

Maggi, 1993 Supplemental

Monocot- Ryegrass 50.5 0.47 44 (emergence)

62.5 (phytotoxicity)

Monocot- Onion 50.5 0.47 0 (no effect)

Monocot- Oat 50.5 0.47 15 (phytotoxicity)

Dicot-Root Crop- Radish 50.5 0.47 0 (no effect)

Dicot- Soybean 50.5 0.47 0 (no effect)

Dicot- Cabbage 50.5 0.47 15 (phytotoxicity)

Dicot- Tomato 50.5 0.47 0 (no effect)

Dicot- Cucumber 50.5 0.47 0 (no effect)

Dicot- Lettuce 50.5 0.47 0 (no effect)

Table B-7. Non-target Terrestrial Plant Seed Germination/Seedling Emergence Toxicity (Tier II)1

Species % ai EC25/NOAEC (lbs a.i./A)

Endpoint Affected

MRID No.

Author/Year

Study 

Classification

Monocot- Corn 50.5 0.418/0.235

Dry weight

43614603

Maggi, 1994 Monocot- Oat 50.5 Supplemental 0.280/0.059Dry weight

Monocot- Ryegrass 50.5 0.078/0.059

Phytotoxicity, dry weight

1 For Tier II seed germination and seedling emergence, ryegrass is most sensitive monocot species tested. Dicot species 

were not tested. Endpoints were updated using a continuous program, Nuthatch in 2005; most sensitive species was 

ryegrass EC25 = 0.078 lb a.i./A (0.021- 0.28); EC50 = 0.16 lb a.i./A (0.033-0.044); NOAEC = 0.059 lb a.i./A (based on 

Williams test); slope = 2.21, std. err. 0.873.

Table B-8. Non-target Terrestrial Plant Vegetative Vigor Toxicity (Tier II)

Species % ai % Response and Endpoint 

Affected

MRID No.

Author/Year

Study 

Classification

Monocot- Ryegrass 95.4 0.029/0.0381 weight

41885906

Chetram, 1991

Supplemental

Monocot- Onion 95.4 NOAEC = 0.5

Dicot-Root Crop- Carrot 95.4 NOAEC = 0.5

Dicot- Soybean 95.4 NOAEC = 0.5

Dicot- Lettuce 95.4 NOAEC = 0.5

Dicot- Tomato 95.4 NOAEC = 0.5

Dicot- Cabbage 95.4 NOAEC = 0.5

Dicot- Cucumber 95.4 NOAEC = 0.5

1 EC25 = 0.029 lb a.i./A (0.023- 0.037); EC50 = 0.038 lb a.i./A (0.033-0.044); NOAEC = 0.025 lb a.i./A based on Williams test; 

Slope = 5.75, std. err. = 1.21
55

Table B-9. Summary of New Vegetative Vigor Toxicity Data, Tier II parameters by species– monocot 

species only1

Species Endpoint NOAEC

(lbs a.i./A)

EC05

(lbs a.i./A)

EC25

(lbs a.i./A)

EC50

(lbs a.i./A) Slope

Corn

(Zea mays)

Dry weight (g) 0.0133 0.0079 0.019 0.036 2.52

Shoot Length (mm) 0.0133 0.021 0.039 0.060 3.63

Survival 0.0384 0.046 0.070 0.093 5.42

Oat

(Avena sativa)

Dry weight (g) 0.0303 0.015 0.044 0.095 2.02

Shoot Length (mm) 0.0303 0.022 0.070 0.16 1.94

Survival 0.0649 0.084 0.18 0.30 2.99

Ryegrass

(Lolium perenne)

Dry weight (g) 0.00276 0.0025 0.0086 0.020 1.80

Shoot Length (mm) 0.0061 0.0028 0.013 0.038 1.46

Survival 0.0303 0.029 0.057 0.090 3.31

1 MRID 47691704, Bergfield 2008; Supplemental; Poast® (BAS 562 05 H) was the formulation that was tested.

Guidelines call for the vegetative vigor and seedling emergence studies to be conducted with the TEP. 

The vegetative vigor study was supplemental since it was not tested with TEP. No valid Tier II seedling 

emergence plant study was submitted. Seedling emergence data is needed to assess non-target plants to 

Sethoxydim runoff exposure. 

Toxicity to Aquatic Organisms

Aquatic Vertebrate Toxicity

Table B-10. Acute Toxicity of Sethoxydim to Freshwater Fish

Species % ai

96-hour LC50

(ppm a.i.)

Toxicity 

Category

MRID No.

Author, Year

Study 

Classification

Rainbow trout,

(Oncorhynchus mykiss)

97.3 170 (a.i. nominal)

1 Practically 

non-toxic

00042815

Seminara et al., 1979 Acceptable

Rainbow trout 19.3 1.2 (a.i. measured)

6.2 (product)2

Moderately 

toxic

41885902

Bowman & Howell, 1991 Acceptable

Bluegill sunfish, 

(Lepomis macrochirus)

97.3 265 (a.i. nominal)3 Practically 

non-toxic

00072863

Seminara et al., 1980 Acceptable

Bluegill sunfish 19.3 1.6 (a.i. measured)

8.3 (product)4

Moderately 

toxic

41885901

Bowman & Howell, 1991 Acceptable

Fathead minnow

(Pimephales promelas)

19.6 1.58 (a.i. measured)5 Moderately

toxic

47691701

Aufderheide, 2009 Acceptable

1 Test concentrations were reported as nominal of test material, the active ingredient. Behaviors/sublethal effects noted included 

being irritated (three highest test concentrations – 56, 100 and 180 mg/L), erratic swimming, dark discolored pigment, and 

labored respiration in the highest test concentration (180 mg/L).

2 Effects included mortality, dark discoloration, surfacing, fish on bottom of test chamber, vertical orientation, flared gills, loss of 

equilibrium, quiescence, and/or labored respiration observed in all test concentrations, except the lowest. Mortality was 100% 

within 48 and 24 hours, respectively in the 1.7 and 2.7 mg/L test concentrations (the two highest test concentrations). If the test 

concentration was converted to total product LC50 = 6.2 mg product/L (reported in RED); however, the DER reports the endpoint 

as mean-measured concentrations and that the nominal concentrations were adjusted for purity; 95% CI = 1.0-1.7 mg/L; NOEC = 

0.21 mg/L; slope = 16).

3 Test concentrations were reported as nominal of technical material, active ingredient. In the highest test concentration (560 

mg/L) 100% mortality was observed. In the second highest test concentration, 320 mg/L, observed behaviors/sublethal effects

included: quiescent, surfacing, sounding, dark discolored pigment, slow respiration, slurping air, irregular and labored respiration. 

4 Effects observed included mortality, dark discoloration, surfacing, fish on bottom of test chamber, twitching, loss of equilibrium, 

vertical orientation, excitable, and/or labored respiration, observed in all but the lowest test concentration. If the test 

concentration was converted to total product LC50 = 8.3 mg product/L (reported in RED); however, the DER reports the endpoint 

as mean-measured concentrations and that the nominal concentrations were adjusted for purity; 95% CI = 0.91-2.3 mg/L; NOEC 

= 0.18 mg/L; slope = 12).

5

In the highest test concentration (10.6 mg a.i./L) 100% mortality was observed. In the remaining second and third highest test 
56

concentrations (6.10 and 3.57 mg a.i/L, respectively) observed sublethal effects included: loss of equilibrium, discoloration, 

surfacing and lying on the bottom of the test chamber. Adjusted for purity (95% CI = 1.20-2.08 mg a.i./L; NOAEC = 0.41 mg 

a.i./L); equivalent to 8.04 mg formulation/L (95% CI = 6.1-10.6 mg formulation L; NOAEC = 2.09 mg formulation/L) – not 

adjusted for purity. Poast® (BAS 562 05 H) was the formulation that was tested.

Table B-11. Chronic Toxicity of Sethoxydim to Freshwater Fish

Species % ai

NOAEC/LOAEC

(ppm a.i.) Endpoints MRID No.Author, Year

Study 

Classification

Fathead minnow

(Pimephales promelas)

94.8 4.86/9.591 Post-hatch survival & 

standard length

47691702

Aufderheide, 2009 Acceptable

Fathead minnow 19.6 0.230/0.4742

Standard length, wet 

weight & post-hatch 

survival

47691703

Aufderheide, 2009 Acceptable

1 Time-weighted average (TWA) test concentrations were used. Post hatch survival and standard length were significantly 

reduced in the highest test concentration compared to the negative control. 

2 Time-weighted average (TWA) test concentrations were used; Poast® (BAS 562 05 H) was the formulation that was tested. The 

most sensitive endpoints were standard length and wet weight; additionally post-hatch survival was also reduced in the highest 

treatment level as only one juvenile fish survived to test termination. Based on this, the highest treatment level was excluded 

from the statistical analysis on the effect on growth of juvenile fish due to the treatment-related effect on survival. Significant 

reductions on both length and wet weight were present in the second highest test concentration 0.474 mg a.i./L level compared to 

the negative control; whereas the 0.934 mg a.i./L level was excluded from growth analysis due to the significant effect on 

survival.

Table B-12. Acute Toxicity of Sethoxydim to Estuarine/Marine Fish

Species % ai

96-hour LC50

(ppm a.i.)

Toxicity 

Category

MRID No.

Author, Year

Study 

Classification

Sheepshead minnow

(Cyprinodon variegatus)

97.8 >145.8 

(measured)

Practically 

non-toxic

42315101

Ward & Boeri, 1992 Acceptable

Sheepshead minnow 18.0 3.5 (a.i., nominal)

19.4 (product, nominal)

Moderately to 

Slightly toxic

41510602

Ward & Boeri, 1989 Acceptable

1 There was 100% mortality observed in the test concentrations > 4.5 mg/L. Sublethal effects observed included loss of 

equilibrium and change in behavior (surfacing) during the test. If the concentration was converted to total product 96h LC50

= 19.4 mg product/L (reported in RED); however, the DER reports the endpoint as “nominal concentrations of the active 

ingredient;” 95% CI = 2.7-4.5 mg a.i./L nominal; NOEC = 2.7 mg a.i./L; based on survival).

Table B-13. Chronic Toxicity of Sethoxydim to Estuarine/Marine Fish1

Species % ai

NOAEC/LOAEC

(ppm a.i.) Endpoints MRID No.Author, Year

Study 

Classification

Sheepshead minnow

(Cyprinodon variegatus)

40.7 98/>98 No effects 43614601

Graves et al., 1995 Supplemental

1A formulated product Poast 3.5EC (Reg. # 7679-129) was used; the study was supplemental as a LOAEC was not determined 

in this study. 

Aquatic Invertebrate Toxicity

Table B-14. Acute Toxicity of Sethoxydim to Freshwater Aquatic Invertebrates

Species % ai 48-hour EC50

(ppm a.i.)

Toxicity 

Category

MRID No.

Author, Year

Study 

Classification

Waterflea 

(Daphnia magna)

97.3 78.1 (nominal)1 Slightly toxic 00042816

Morrissey et al., 1979 Acceptable

Waterflea 19.3 2.6 (a.i., mean-measured)

13.5 (product, measured)2

Moderately 

to Slightly 

toxic

41885903

Blasberg et al., 1991 Acceptable

1 Dose response slope is 4.73725

2 There was 100% immobility observed in the two highest test concentrations, 4.6 and 8.9 mg/L after 4 hours. In the mid test 

concentration, 2.4 mg/L, immobility and daphnids were observed on the bottom. If endpoint was converted to total product EC50 = 
57

13.5 mg product/L (reported in RED); however, the DER reports the endpoint as measured concentrations; 95% CI = 2.0-3.3 mg/L 

– mean-measured; NOEC = 1.1 mg/L; slope = 7.4).

Freshwater Aquatic Invertebrates Chronic Toxicity

No chronic freshwater aquatic invertebrate studies are available for sethoxydim. 

Table B-15. Acute Toxicity of Sethoxydim to Estuarine/Marine Aquatic Invertebrates

Species % ai 48/96-hour EC/LC50

(ppm a.i.) Toxicity Category MRID No.Author, Year

Study 

Classification

Eastern oyster

(embryo-larvae)

(Crassostrea virginica)

94.5 >109

(mean-measured)

Practically nontoxic42537401 

Lintott, 1992 Acceptable

Eastern oyster 20.4 0.9 (a.i., nominal)

4.4 (product, nominal)1

Highly toxic to

Moderately toxic

41607207

Ward & Boeri, 1990 Acceptable

Mysid

(Americamysis bahia)

97.8 >141.8 

(mean-measured)

Practically nontoxic42315102

Ward & Boeri, 1992 Acceptable

Mysid 18.0 0.8 (a.i., nominal)

4.4 (product, nominal)

Highly toxic to

Moderately toxic

41510604

Ward & Boeri, 1989 Acceptable

1

If the concentration was converted to total product 48h EC50 = 4.4 mg product/L (reported in RED); however, the DER reports 

the endpoint as “nominal concentrations of the active ingredient;” 95% CI = 0.6-1.0 mg a.i./L nominal).

2 There was 100% mortality observed in the test concentrations ≥ 1.1 mg/L, and no sublethal effects were observed in any test 

concentration. If the concentration was converted to total product 96h LC50 = 4.4 mg product/L (reported in RED); however, the 

DER reports the endpoint as “nominal concentrations of the active ingredient;” 95% CI = 0.7-1.1 mg a.i./L nominal; NOEC = 0.7 

mg a.i./L; based on survival).

Table B-16. Chronic Toxicity of Sethoxydim Estuarine/Marine Aquatic Invertebrates

Species % ai 21-d NOAEC/LOAEC

(ppm a.i.) Endpoints MRID No.Author, Year

Study 

Classification

Mysid

(Americamysis bahia)

43.1 15.1/30.2 (product)

6.5/13 ppm a.i.

Survival & 

Length1

43614602

Boeri et al., 1995 Supplemental

1 Erratic swimming and/or lethargy were noted in the two highest test concentrations (56 and 113 mg a.i./L) until complete 

mortality occurred on days 4 and 14 for each group, respectively. Other endpoints affected included reproduction (neonates 

produced), and weight (dry and wet). The study was classified as supplemental because it was conducted with an end-use 

product (EP) and not technical grade (TGAI) test material as required by CFR 158.490. 

Aquatic Plant Toxicity

Table B-17. Toxicity of Sethoxydim to Aquatic Plants 

Species % ai EC50

(mg a.i./L)

NOAEC

(mg a.i./L) Endpoints MRID No.Author, Year

Study 

Classification

Vascular Plants

Duckweed 

(Lemna gibba)

99.8 14d EC50 

>0.281

14d NOAEC 

= 0.281

No significant 

effects1

43614605

Thompson et al., 1994 Acceptable

Reed Mannagrass

(Glyceria maxima)

19.3 21d EC50 = 

0.21

21d NOAEC

= 0.093

Growth rate 

based on total 

leaf length2

48000902

Knauert, 2009 Acceptable

Non-Vascular Plants

Green algae 

(Selenastrum capricornutum)

99.8 120 hr EC50

>0.302

120 hr 

NOAEC = 

0.302

No effects 43614607

Thompson et al., 1994 Acceptable

Marine diatom

(Skeletonema costatum)

99.8 120 hr EC50

>0.250

120 hr 

NOAEC = 

0.250

No effects 43626101

Thompson et al., 1994 Acceptable
58

Species % ai EC50

(mg a.i./L)

NOAEC

(mg a.i./L) Endpoints MRID No.Author, Year

Study 

Classification

Freshwater diatom

(Navicula pelliculosa)

99.8 120 hr EC50

>0.266

120 hr 

NOAEC = 

0.266

No effects 43614606

Thompson et al., 1994 Acceptable

Blue-green algae

(Anabaena flos-aquae)

99.8 120 hr EC50

>0.303

120 hr 

NOAEC = 

0.303

No significant 

effects3

43614608

Thompson et al., 1994 Acceptable

1 Some necrosis, chlorosis, and dead plants were noted in the control and treatment groups. However, a clear dose response was not 

noted for any one symptom. 

2 The endpoints were based on 21-day results, in addition to the most sensitive endpoint of total leaf length, growth rate based on 

dry weight also showed effects, and the resulting EC50 and NOAEC values were 2.9 and 0.093 mg a.i./L, respectively. The percent 

growth inhibition of total leaf length in treated culture as compared to the control ranged from 10 to 95%. Rhizome development 

was affected and plants showed moderate to strong necrotic symptoms. 

3 Replicate C of the 0.039 mg a.i./L treatment group had 95% less cells than the other two replicates. The results of this replicate 

were not included in the analysis.
59

APPENDIX C. Sethoxydim Incidents

A search for ecological incidents related to sethoxydim use, conducted on January 23, 2015, yielded four (4) incidents; two (2) involving 

aquatic animals and two (2) terrestrial plants, which are summarized below.

Table C-1. Sethoxydim Incidents, as Reported in the EIIS Database

Incident ID # State, County Magnitude Year Description Legality Certainty

I011716-002 AZ, Maricopa Unknown 2001

A crop-dusting plane by pilot John Pew, misdirected spray 

suffocated dozens of White Amur grass carp (Ctenpharyngondon 

idella). The pilot was to spray Thiodan and Checkmate over a cotton 

field to kill the common whitefly, The fish kill cost the Salt River 

Project (SRP) $4,000 to replace the fish, but, the pilot was fined 

$113 plus $182 for spraying the house.

Endosulfan is much more toxic to fish than is sethoxydim and was 

likely the primary cause of the fish mortality. It is possible, however, 

that sethoxydim also contributed to the toxicity to the fish.

Misuse 

(Accidental) Possible

I000232-001 USA 300 1992

According to the report a pond collected water from a large 

watershed that drained 104 acres of farmland where cotton (40 yards 

away) and peanuts (60 yards away) were being grown. The cotton 

had been treated with Pix (growth regulator) and the peanuts had 

been treated with Poast-Plus Herbicide and Lorsban 15G Granular 

Insecticide 8-10 days prior to an alleged fish kill (Bluegill and 

Crappie). Two inches of rain fell one hour after the Lorsban 

application. It was believed that chlorpyrifos was responsible for the 

observed incident. Four pond water samples were collected and 

analyzed for chlorpyrifos one week after the fish kill was reported. 

Presence of chlorpyrifos was revealed. The product label states that 

drift or runoff from treatment areas may be hazardous to aquatic 

organisms in neighboring aquatic sites. 

While chlorpyrifos is probably the primary cause of this fish kill, It 

is also possible that mepiquat chloride and sethoxydim contributed 

to the toxicity observed in this incident.

Registered Use Possible

I021485-016 ID, Cassia 100%

(193 acres) 2009

An application of the products Huskie (a.i. pyrasulfotole, 

bromoxynil octanoate and bromoxynil heptanoate) and Hi Yield (a.i. 

sethoxydim) onto 193 acres of winter wheat in Cassia County, ID 

allegedly stunted the crop.

Registered Use Possible

I018428-016 CA, Tulare 20% of crop 

yield 2006

An aerial application of the product (Poast) resulted in damage to 

watermelon fruits and foliage. The application was made at twice the 

label rate. Application rate was listed as 51.2 oz/A.

Misuse 

(Intentional) Possible
60

Uncertainties Related to the Use of Incident Information from the Ecological Incident Information System 

Incident data are used in risk assessments to provide evidence that the risk predictions from the screening level assessment are supported 

by actual effects in the field. Incident reports submitted to EPA since approximately 1994 have been tracked by assignment of incident 

numbers in an Incident Data System (IDS), microfiched, and then entered to a second database, the Ecological Incident Information 

System (EIIS). Additionally, there is an on-going effort to enter information to EIIS on incident reports received prior to establishment 

of current databases. Incident reports are not received in a consistent format (e.g., states and various labs usually have their own 

formats), may involve multiple incidents involving multiple chemicals in one report, and may report on only part of a given incident 

investigation (e.g., residues). 

Incidents entered into EIIS are categorized into one of several certainty levels regarding the likelihood that a particular pesticide is 

associated with the incident: highly probable, probable, possible, unlikely, or unrelated. In brief, “highly probable” incidents usually 

require carcass residues and/or clear circumstances regarding the exposure. “Probable” incidents include those where residues were not 

available and/or circumstances were less clear than for “highly probable.” “Possible” incidents include those where multiple chemicals 

may have been involved and it is not clear what the contribution was of a given chemical. The “unlikely” category is used, for example, 

where a given chemical is practically nontoxic to the category of organism killed and/or the chemical was tested for but not detected in 

samples. “Unrelated” incidents are those that have been confirmed to be not pesticide-related.

Incidents entered into the EIIS are also categorized as to use/misuse. Unless specifically confirmed by a state or federal agency to be 

misuse, or there was very clear misuse such as intentional baiting to kill wildlife, incidents are not typically considered misuse. 

The number of documented kills in EIIS is believed to be a small fraction of total mortality caused by pesticides. Mortality incidents 

must be seen, reported, investigated, and have investigation reports submitted to EPA to have the potential for entry into the database. 

Incidents often are not seen, due to scavenger removal of carcasses, decay in the field, or simply because carcasses may be hard to see on 

many sites and/or few people are systematically looking. Poisoned animals may also move off-site to less conspicuous areas before 

dying. Incidents may not get reported to appropriate authorities capable of investigating the incident for a variety of reasons including 

the finder may not know of the importance of reporting incidents, may not know who to call, may not feel they have the time or desire to 

call, or may hesitate to call because of their own involvement in the kill. Incidents reported may not get investigated if resources are 

limited or may not get investigated thoroughly, with residue analyses, for example. Also, if kills are not reported and investigated 

promptly, there will be little chance of documenting the cause, since tissues and residues may deteriorate quickly. Reports of 

investigated incidents often do not get submitted to EPA, since reporting by states is voluntary. 

Furthermore, the database relies heavily on registrant-submitted incident reports, and registrants are currently only required to submit 

detailed information on ‘major’ ecological incidents, while ‘minor’ incidents are reported aggregately. 
61

Based on the 40 CFR (§159.184 Toxic or adverse effect incident reports), an ecological incident is considered ‘major’ if any of the 

following criteria are met:

Fish or wildlife:

(A) Involves any incident caused by a pesticide currently in Formal Review for ecological concerns. 

(B) Fish: Affected 1,000 or more individuals of a schooling species or 50 or more individuals of a non-schooling species. 

(C) Birds: Affected 200 or more individuals of a flocking species, or 50 or more individuals of a songbird species, or 5 or more 

individuals of a predatory species. 

(D) Mammals, reptiles, amphibians: Affected 50 or more individuals of a relatively common or herding species or 5 or more 

individuals of a rare or solitary species. 

(E) Involves effects to, or illegal pesticide treatment (misuse) of a substantial tract of habitat (greater than or equal to 10 acres, 

terrestrial or aquatic). 

Plants: 

(A) The effect is alleged to have occurred on more than 45 percent of the acreage exposed to the pesticide.

All other ecological incidents are considered ‘minor’ and only need to be aggregately reported. ‘Minor’ incidents reported by the 

registrants are not included in the EIIS database. Therefore, for example, an incident could affect 900 fish, 150 birds, 45 mammals, and 

40% of an exposed crop and not be included in the EIIS database [unless is it reported by a non-registrant (e.g., an incident submitted by 

a state agency – which are not systematically collected)]. Therefore, because the number of documented kills in EIIS is believed to be a 

small fraction of total mortality caused by pesticides, absence of reports does not necessarily provide evidence of an absence of incidents. 
62

APPENDIX D. SIP & STIR Inputs and Outputs for Sethoxydim

SIP Inputs/Outputs

Table 1. Inputs

Parameter Value

Chemical name Sethoxydim

Solubility (in water at 25oC; mg/L) 4700

Mammalian LD50 (mg/kg-bw) 2676

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg-bw) 30

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Avian LD50 (mg/kg-bw) 2510

Avian test species mallard duck

Body weight (g) of "other" avian species

Mineau scaling factor

Mallard NOAEC (mg/kg-diet) 466

Bobwhite quail NOAEC (mg/kg-diet) 1000

NOAEC (mg/kg-diet) for other bird species

Body weight (g) of other avian species

NOAEC (mg/kg-diet) for 2nd other bird species

Body weight (g) of 2nd other avian species

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 808.4000 808.4000

Adjusted toxicity value (mg/kg-bw) 2058.2737 23.0748

Ratio of exposure to toxicity 0.3928 35.0339

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for mammals

Exposure through drinking 

water alone is a potential 

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 3807.0000 3807.0000

Adjusted toxicity value (mg/kg-bw) 198290.0000 23.1195

Ratio of exposure to acute toxicity 0.0192 164.6665

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for birds

Exposure through drinking 

water alone is a potential 

concern for birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. Therefore, 

when aggregated with other routes (i.e ., diet, inhalation, dermal), pesticide exposure through drinking water 

may contribute to a total exposure that has potential for effects to non-target animals.
63

STIR Inputs/Outputs

Input

Application and Chemical Information

Enter Chemical Name Sethoxydim

Enter Chemical Use Broadleaf crops

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) air

Enter Chemical Molecular Weight (g/mole) 327

Enter Chemical Vapor Pressure (mmHg) 1.60E-07

Enter Application Rate (lb a.i./acre) 0.5

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 2510

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 1.58

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 2676

Enter Lowest Rat Inhalation LC50 (mg/L) 6.03

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.35

Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 2.82E-03

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.54E-04

Adjusted Inhalation LD50 2.27E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.56E-05 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 4.80E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 2.11E-03 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 2.82E-03

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 4.45E-04

Adjusted Inhalation LD50 3.59E+02

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.24E-06 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 6.04E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 1.68E-04 Exposure not Likely Significant

**NOTE**: When entering values, press the "Enter" key 

in order to update linked cells.