Page 2 of 39

Problem Formulation for the Environmental Fate,

Ecological Risk, Endangered Species, and Drinking 

Water Exposure Assessments in Support of the 

Registration Review of Flucarbazone Sodium

CAS Registry Number: 181274-17-9

PC Code: 114009

Prepared by:

Elyssa Arnold, Biologist

Richard Shamblen, Biologist

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch II

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Reviewed by:

Kristina Garber, Senior Biologist

Greg Orrick, Environmental Scientist

Jean Holmes, DVM, MPH, Risk Assessment Process Leader

Brian Anderson, Branch Chief

October 31, 2013
Page 3 of 39

TABLE OF CONTENTS

1. EXECUTIVE SUMMARY .................................................................................................... 4

2. INTRODUCTION .................................................................................................................. 4

3. USE CHARACTERIZATION................................................................................................ 5

4. CONCLUSIONS FROM PREVIOUS ASSESSMENTS....................................................... 5

4.1. Ecological Risk Assessments........................................................................................... 5

4.2. Drinking Water Exposure Assessments........................................................................... 6

4.3. Clean Water Act Programs............................................................................................... 6

5. ENVIRONMENTAL FATE AND TRANSPORT................................................................. 6

5.1. Transformation Products.................................................................................................. 8

6. RECEPTORS........................................................................................................................ 15

6.1. Effects to Aquatic Organisms ........................................................................................ 15

6.2. Effects to Terrestrial Organisms .................................................................................... 16

6.3. Ecological Incidents....................................................................................................... 18

7. EXPOSURE PATHWAYS OF CONCERN ........................................................................ 20

8. ANALYSIS PLAN ............................................................................................................... 20

8.1. Stressors of Concern....................................................................................................... 20

8.2. Measures of Exposure .................................................................................................... 21

8.3. Measures of Effect ......................................................................................................... 21

8.4. Endangered Species Assessments.................................................................................. 22

8.5. Endocrine Disruptor Screening Program ....................................................................... 22

9. PRELIMINARY IDENTIFICATION OF DATA GAPS..................................................... 22

9.1. Environmental Fate ........................................................................................................ 22

9.2. Effects............................................................................................................................. 24

10. REFERENCES .................................................................................................................. 27

Appendix A. SIP and STIR Results.............................................................................................. 35

Appendix B. ECOSAR Estimates for Flucarbazone Sodium and its Degradates......................... 37
Page 4 of 39

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 flucarbazone sodium (PC 

114009; CAS Registry Number 181274-17-9). The problem formulation describes the methods

planned for the completion of drinking water and ecological risk assessments and provides an 

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

of flucarbazone sodium. The problem formulation also addresses uncertainties unique to risk 

assessment of flucarbazone sodium. This document identifies additional studies that would be 

beneficial to the conduct of an ecological risk assessment. Major findings include:

Environmental fate and transport data gaps:

• 835.4100 Aerobic soil metabolism – Guideline-compliant data are needed for two 

additional soils.

Ecotoxicology data gaps:

• None

2. INTRODUCTION

Flucarbazone sodium is a selective, post-emergent herbicide used to control a variety of grasses 

and broadleaf weeds. Registered uses include wheat, turf, and conifer tree nurseries. 

Flucarbazone sodium (Sodium salt 4,5-dihydro-3-methoxy-4-methyl-5-oxo-N-[2-

trifluoromethoxy)phenyl]solfonyl]-H-1,2,4-triazole-1-carboxamide; CAS No. 181274-17-9; PC 

code 114009) is a sulfonyamino-carbonyl-triazolinone herbicide (Wood, 2007; Ware and 

Whitacre, 2004) that dissociates to an anion (flucarbazone) in the presence of moisture. The 

terms flucarbazone and flucarbazone sodium will be used interchangeably in this document. The 

mode of action for sulfonyamino-carbonyl-triazolinone herbicides is the inhibition of branched 

chain amino acid biosynthesis through the inhibition of an enzyme called acetolactate synthetase 

(ALS) (Ware and Whitacre, 2004). 

There is concern for surface and ground water contamination due to the high solubility, mobility,

and persistence properties of flucarbazone, and its sulfonamide and sulfonic acid degradates. No 

water quality monitoring data for flucarbazone has been identified.

EFED evaluated the most recent ecological risk assessments for flucarbazone sodium in 

association with the most recent toxicity, exposure, and usage information to determine if 

sufficient data are available and if further updates are needed to support registration review. 

Recent risk assessments include a 2009 assessment for the use of flucarbazone sodium on turf 

and conifer tree nurseries (DP 357819). In determining if new data or updated assessments will 

be needed for registration review, EFED considered the latest Agency science policies and risk 

assessment methodologies. 
Page 5 of 39

3. USE CHARACTERIZATION

Flucarbazone sodium was first registered in the United States in 2000 for use as an herbicide on 

wheat. Registered uses now include wheat, turf, and conifer tree nurseries. Between 2004 and 

2011, approximately 30,000 pounds of flucarbazone sodium were applied to wheat annually, 

accounting for an average of five percent and a maximum of 10 percent of the U.S. wheat crop. 

Use was also reported in this time period on fallow land, which is not a registered use of 

flucarbazone sodium (USEPA, 2013). Flucarbazone sodium is formulated as an emulsifiable 

concentrate, suspension concentrate, and water dispersible granules. Products registered for use 

on wheat include co-formulations with the herbicides chlorsulfuron and fluroxypyr 1-

methylheptyl ester. Applications may be made by air or ground boom. The maximum single 

application rate is 0.026 lb acid equivalents (ae)/acre.

Table 1 details the registered use patterns for flucarbazone sodium. EFED will use application 

parameters that result in maximum exposure scenarios for a given use for the registration review 

risk assessment. 

Table 1. Use Site and Application Information for Flucarbazone Sodium

Use Site Formulation 

Type1

Maximum

App. Rate

(lbs ae/Acre)

Maximum

Annual

Rate

Maximum

No. of Apps 

per Year

Minimum

App. Interval

(days)

Application 

Methods

Conifers 

(Plantations/

Nurseries)

EC 0.025 0.025 NS 30 Ground

Grasses Grown 

for Seed2 SC/L 0.026 0.026 1 NS Ground orAerial

Ornamental 

Lawns and Turf3 EC 0.025 0.025 NS 30 Ground

Wheat EC, SC/L, 

WDG 0.026 0.026 1 NS Ground orAerial

Abbreviations: NS - Not Specified; App. - Application 1 EC - Emulsifiable Concentrate; SC/L - Suspension Concentrate/Liquid; WDG - Water Dispersible Granules (dry 

flowable)

2 Special Local Needs registrations for Idaho, Minnesota, Oregon, and Washington only

3 Includes golf course fairways and roughs, seed and sod production fields, commercial and residential sites 

(including homes, schools, playgrounds, parks, recreational areas and sports fields, common areas)

4. CONCLUSIONS FROM PREVIOUS ASSESSMENTS

4.1. Ecological Risk Assessments

The Agency has conducted three ecological risk assessments on flucarbazone sodium that serve 

as a basis for this problem formulation, including an assessment for the initial registration for use 

on wheat (USEPA, 2000a), an assessment for aerial applications to wheat (USEPA, 2004), and 

an assessment for new uses on turf and conifer tree nurseries (USEPA, 2009a). Maximum 

estimated aquatic exposure concentrations in the 2009 assessment for peak, 21-day, and 60-day 

exposures were 0.996, 0.986, and 0.968 μg/L, respectively. The only identified direct risk 

concern in previous assessments was for terrestrial plants. The major ecological risk conclusions 

from these assessments are summarized in Table 2.
Page 6 of 39

Table 2. Summary of Risk Concerns Identified for Flucarbazone Sodium in Previous Assessments

Birds Mammals Terr.

Plants

Terr.

Inverts Fish Bioaccumulation

Aquatic 

Inverts

Aquatic 

Plants

Ground Water 

Contamination Persistence Degradates of Concern

No No Yes No No1 No No1 No No No Yes & 

No2

Abbreviations: Terr. - Terrestrial 1 No data were available for the assessment of risk to estuarine/marine invertebrates or fish. 2 For the ecological risk assessment, no degradates of concern were identified. For the drinking water assessment, 

degradates containing the sulfonamide moiety were of concern. 

4.2. Drinking Water Exposure Assessments

A drinking water exposure assessment for flucarbazone sodium was conducted for the initial 

registration for use on wheat at 0.025 lb ae/acre (USEPA, 2000b). Exposure estimates of 

flucarbazone sodium residues of concern from use on wheat were 1.45 μg/L (1-in-10-year peak), 

and 1.44 μg/L (1-in-10-year annual mean and 30-year mean) for surface water and a maximum 

of 50 μg/L for ground water. The residues of concern included in the calculations were the 

parent and all degradates containing the sulfonamide moiety (i.e., MKH 6562 Sulfonamide) for 

consistency with the animal enforcement analytical method. The new uses on turf and conifer 

tree nurseries registered in 2009 had the same application rate and therefore a new drinking 

water assessment was not conducted for them (USEPA, 2009b). No ground or surface water 

monitoring data were available. 

Due to the persistence of flucarbazone degradates, SCI-GROW was not used to estimate ground 

water exposure for total residues. Instead, the screening value of 50 μg/L was estimated, which 

represents the concentration of flucarbazone residues in the soil pore water of the top 1-foot of 

soil immediately post-application. This value is an upper limit to the amount of chemical that 

could be found in ground water (USEPA, 2000b). 

4.3. Clean Water Act Programs

Flucarbazone sodium is not identified as a cause of impairment for any water bodies listed as 

impaired under section 303(d) of the Clean Water Act. No Total Maximum Daily Load (TMDL) 

criteria have been developed for flucarbazone sodium. Aquatic benchmarks have not been 

established for flucarbazone sodium. Any data submitted or otherwise located as part of the 

registration review process may be used to develop aquatic life benchmarks if applicable. 

5. ENVIRONMENTAL FATE AND TRANSPORT

Table 3 summarizes select chemical properties and environmental fate and transport 

characteristics of flucarbazone sodium. Half-life data are presented for hydrolysis and aqueous 

and soil photolysis studies. Aerobic soil and water and anaerobic aquatic metabolism 

disappearance time (DT50) data were calculated with PestDF using R v.2.14.1 software. Aerobic 

aquatic disappearance rates are classified as provisional while the study (MRID 48648501) is 

under review. As warranted, metabolism rates were adjusted for temperature (25°C) (USEPA, 

2010).
Page 7 of 39

In the presence of moisture, flucarbazone sodium dissociates to an anion (flucarbazone) and 

sodium. As an anion, flucarbazone is very soluble (44 g/L) and not likely to bioaccumulate. 

Because of its low vapor pressure and Henry’s law constant, volatilization from soil or water is 

not expected to be a major route of dissipation.

With half-lives greater than 210 days, flucarbazone sodium is stable to hydrolysis (pH 5, 7, and 

9) and photolysis in both water and soil. However, the herbicide does photolyze in a non-sterile 

pond water environment with a half-life of approximately 61 days. After becoming incorporated 

into soils, aerobic in-situ degradation of the herbicide ranges from 23 days to 224 days, varying 

by soil type. The herbicide disappearance rates ranging from 13 to 32 days on four separate soils 

in field dissipation studies appear to support the laboratory data. These field dissipation halflives were due to both leaching and biodegradation.

In an anaerobic aquatic environment, flucarbazone is moderately persistent with calculated 

metabolism rates of 73 to 657 days. Although classified as “provisional” data while the study is 

under review, the aerobic aquatic disappearance rates range from 54 to 307 days. 

Table 3: Chemical Properties and Environmental Fate Characteristics of Flucarbazone Sodium

Parameter Value1 Description Source

(MRID)

Selected Physical/Chemical Parameters

Molecular Mass 

(Molecular Formula)

418.3 g/mol

(C12 H10 F3 N4 Na O6 S – Na+) -- 44865801

Vapor pressure 

(20°C) <7.5 x 10-12 torr Non-volatile under field conditions 44865801

Aqueous solubility 

(20°C) 44,000 mg/L Soluble 44865801

Henry’s Law Constant 

(20°C)

<9.9 x 10-17 [atm x m3] / 

Mole Essentially non-volatile 44865801

Log octanol-to-water partition 

coefficient (log KOW)

pH 4: -0.89

pH 7: -1.84

pH 9: -1.88

Not likely to 

bioaccumulate 44865801

Acid dissociation constant (pKa) 1.9 Anionic 44865801

Persistence

Hydrolysis: Half-life 

(25±1°C)

pH 5: 520 d

pH 7: 520 d

pH 9: 750 d

Not a major degradation 

pathway 44848851

Aqueous Photolysis: Half-life 

(25±1°C)

Phoenix, AZ:

Sterile Buffer

pH 7: 680 d

Pond Water

pH 7.9: 61 d

Not a major degradation 

pathway

44848902/ 

44865802

Soil Photolysis: Half life

(25±1°C)

Phoenix, AZ:

210 d

Not a major degradation 

pathway 44848901

Aerobic Soil Metabolism: DT50

(21±1°C)

36 d

[27 d]

North Dakota 

Sandy Loam Soil 44848903
Page 8 of 39

Parameter Value1 Description Source

(MRID)

[DT50 adjusted to 25±1°C] 30 d

[23 d] 44848904

296 d

[224 d]

Manitoba

Sandy Loam 44848905

Aerobic Aquatic Metabolism2: DT50

(21±1°C)

[DT50 adjusted to 25±1°C]

71 d

[54 d]

405 d

[307 d]

-- 48648501

Anaerobic Aquatic Metabolism:

DT50

[DT50 adjusted to 25±1°C]

657 d (5°C)

[164 d] -- 44848909

73 d (21°C)

[55 d] -- 44848910

Mobility

Freundlich soil-water partition 

coefficients (KF)

Organic carbon-normalized 

Freundlich coefficients (KFOC)

0.24, 0.57, 0.31, 0.30, 0.02

l/kg

11, 20, 15, 12, 12 l/kg

Mobile 44848912

Field Dissipation

Terrestrial Field Dissipation: 

DT50

Leaching depth

Plot 1:

13 d (0-7.5 cm depth);

Leached to 22.5cm depth Gray Wooded 

loam soil

44848922/ 

Plot 2: 45083705

14 d (0-7.5 cm depth)

Leached to 22.5cm depth

Plot 1:

31 d (0-7.5 cm depth);

Leached to 30.0 cm depth Orthic Dark Brown 

clay loam soil

44848924/ 

Plot 2: 45083703

19 d (0-7.5 cm depth);

Leached to 30.0 cm depth

18 d (0 – 15 cm depth);

Leached to 75.0 cm depth

Timmerman

sandy loam soil 46223703

32 d (0 – 15 cm depth);

Leached to 15.0 cm depth

Tillman fine

sandy loam soil 46223704

Abbreviations: °C - degrees Celsius; DT - disappearance time; l - liters; kg - kilograms 1 Reported values are rounded to 2 significant figures. 2 Study data is classified as provisional while study (MRID 48648501) is in review. The reported half-life data are 

presented in italics and represent two systems evaluated during the study.

5.1. Transformation Products

Table 4 summarizes the transformation products of flucarbazone sodium and the maximum

amounts formed by the degradation pathway. Major (≥10%) degradates of flucarbazone sodium

identified in submitted environmental fate studies include MKH 6562 sulfonamide, MKH 6562 
Page 9 of 39

sulfonic acid, O-desmethyl MKH 6562 NMT, N-methyl-triazolinone (NMT), and carbon 

dioxide. The sulfonamide forms up to 89% of the applied, O-desmethyl MKH 6562 NMT forms 

up to 32% of the applied, and the other major degradates are less prominent. Minor (<%10) 

degradates include MKH 6562 sulfonyl urea, N,O-dimethyltriazoline (NODT), polar acid, and 

unknown or unidentified compounds. 

MKH 6562 sulfonamide and MKH 6562 sulfonic acid are resistant to metabolism. The Odesmethyl flucarbazone degradate rapidly hydrolyzes to NODT, which then degrades rapidly to 

NMT. NMT is either immobilized in the soil or metabolized to CO2 and nitrogen compounds. 

MKH 6562 sulfonamide, MKH 6562 sulfonic acid, and NODT degradates are very mobile in all 

soils.

Because of the high solubility and mobility of flucarbazone sodium and the high mobility and 

persistence of its sulfonamide degradate, both surface and ground water contamination may

occur following flucarbazone sodium application. None of the degradates have been identified 

as ecological residues of concern in previous risk assessments. The previous drinking water 

assessment included the parent and the degradate MKH 6562 sulfonamide as residues of 

concern.
Page 10 of 39

Table 4: Flucarbazone Sodium and Major Environmental Degradates

Code Name/ 

Synonym Chemical Name Chemical 

Structure

Study 

Type

Reference

(MRID)1

Maximum

Percent 

Recovery 2,3

(time period)

Final

Percent 

Recovery2,3

(study length)

PARENT

MKH 6562/

Flucarbazone 

sodium

Name:

Sodium salt of 4,5-dihydro3-methoxy-4-methyl-5-oxoN-[2-[(trifluoromethoxy) 

phenyl] sulfonyl]-1H-1,2,4-

triazole-1-carboxamide

CAS No.:

181274-17-9

Formula:

C12H10F3N4NaO6S

Smiles String:

[Na+].O=S(=O)(/N=C(\[O-

])N1/N=C(/OC)N(C1=O)C)

c2ccccc2OC(F)(F)F

Molecular Weight: 

418.3 g/mol

TRANSFORMATION PRODUCTS
Page 11 of 39

Code Name/ 

Synonym Chemical Name Chemical 

Structure

Study 

Type

Reference

(MRID)

1

Maximum

Percent 

Recovery

2,3

(time period)

Final

Percent 

Recovery

2,3

(study length)

MKH 6562 

Sulfonamide

Name: 2-(Trifluoromethoxy)

-

benzene-sulfonamide-3,4,6-

d3

Formula: C7H6F3NO

3

S

Smiles String:

c1(S(N)(=O)=O)c(OC(F)(F)

F)cccc1

Molecular Weight: 

241.2 g/mol

Hydrolysis:

pH5

pH 7

pH 9

44848851 4.2% (30 d)

3.9% (30 d)

4.0% (30 d)

4.2% (30 d)

3.9% (30 d)

4.0% (30 d)

Aqueous Photolysis:

Sterile – Dark

Sterile – Light

Pond – Dark

Pond - Light

44848902/ 

44865802

2.2% (31.1 d)

5.1% (31.1 d)

2.2% (32.0 d)

24% (32.0 d)

2.2% (31 d)

5.1% (31 d)

2.2% (32 d)

24% (32 d)

Aerobic

Soil

Metabolism

44848903 69% (181 & 272 d) 67% (366 d)

44848905 46% (272 d) 41% (366 d)

Anaerobic

Aquatic

Metabolism

44848909

S 49% (275 d) 68% (365 d)

44848910 89% (367 d)89% (367 d)

Terrestrial

Field

Dissipation

44848922/ 

45083705

35% (59 d)

40% (332 d)

29% (505 d)

30% (505 d)

44848924/ 

45083703

24% (402 d)

21% (28 d)

8% (502 d)

11% (502 d)

44848925

S 7% (14 d) <LOQ (456 d)

44848926

S 33% (28 d) 7% (367 d)

MKH6562

Sulfonic Acid

Name: 2-(Trifluoromethoxy)

-

benzene-sulfonic acid

Formula: C7H5F3O4

S

Smiles String:

O=S(=O)(c1ccccc1OC(F)(F

)F)O

Molecular Weight: 

242.2 g/mol

Hydrolysis:

pH 5

pH7

pH9

44848851 0.6% (0 d)

0.6% (1 d & 14 d)

0.6% (7 d)

0.5% (30 d)

0.5% (30 d)

0.4% (30 d)

Aqueous Photolysis:

Sterile – Dark

Sterile – Light

Pond – Dark

Pond - Light

44848902/ 

44865802

0.8% (13 d)

1.0% (31 d)

1.1% (8 d)

1.3% (32 d)

0.8% (31 d)

1.0% (31 d)

0.8% (32 d)

1.3% (32 d)

Aerobic 

Soil 

Metabolism

44848903 11% (272 d) 10% (366 d)

44848905 6% (366 d) 6% (366 d)

Anaerobic

Aquatic

Metabolism

44848909 NR NR

44848910 NR NR

Terrestrial Field 

Dissipation

44848922/ 

45083705

6% (456 d) <1% (505d)

<LOQ% (-- d) <LOQ (502 d)
Page 12 of 39

Code Name/ 

Synonym Chemical Name Chemical 

Structure

Study 

Type

Reference

(MRID)1

Maximum

Percent 

Recovery 2,3

(time period)

Final

Percent 

Recovery2,3

(study length)

44848924/ 

45083703

11% (91 d) <LOQ (502 d)

8% (91 d) 11% (502 d)

44848925 <LOQ (-- d) <LOQ (456 d)

44848926 6% (63 d) <LOQ (367 d)

O-desmethyl 

MKH 6562

NMT

Name:

4-methyl-3,5-dioxo-N-[[2-

(trifluoromethoxy)phenyl]su

lfonyl]-1,2,4-triazolidine-1-

carboxamide

Formula:

C11H9F3N4O6S

Smiles String:

c1(S(=O)(=O)NC(=O)N2C(

=O)N(C)C(=O)N2)c(OC(F)

(F)F)cccc1

Molecular Weight: 

382.3 g/mol

Aerobic 

Soil 

Metabolism

44848904 15% (2 m) 2.5% (12 m)

Terrestrial

Field

Dissipation

44848922/ 

45083705

30% (10 d)

32% (28 d)

NA (505 d)

NA (505 d)

44848924/ 

45083703

13% (3 d)

10% (3 d)

NA (502 d)

NA (502 d)

44848925 <LOQ <LOQ

44848926 8% (28 d) <LOQ (367 d)

NODT

Name:

N,O-dimethyltriazoline

Formula:

C4H7N3O2

Smiles String:

C1(=O)N(C)C(OC)=NN1

Molecular Weight: 

129.1 g/mol

Aerobic 

Soil

Metabolism

44848904 4.7% (1 m) ND (12 m)
Page 13 of 39

Code Name/ 

Synonym Chemical Name Chemical 

Structure

Study 

Type

Reference

(MRID)1

Maximum

Percent 

Recovery 2,3

(time period)

Final

Percent 

Recovery2,3

(study length)

NMT

Name:

N-methyl-triazolinone

Formula:

C3H5N3O2

Smiles String:

C1(=O)N(C)C(=O)NN1

Molecular Weight: 

115.1 g/mol

Aerobic

Soil

Metabolism

44848904 14% (2 m) 3.9% (12 m)

MKH 6562 

Sulfonyl-urea

Name:

2-Trifluoromethoxybenzenesulfonyl urea

Formula:

C8H7F3N2O4S

Smiles String:

c1(S(=O)(=O)NC(N)=O)c(

OC(F)(F)F)cccc1

Molecular Weight: 

284.2 g/mol

Aerobic 

Soil 

Metabolism

44848903 2% (272 d) 2% (366 d)

44848905 <1% (90 d) 2% (366 d)

CO2

Name:

Carbon dioxide

CAS No:

124-38-9

Smiles String:

C(=O)=O

Molecular Weight:

44.0 g/mol

Aerobic 

Soil 

Metabolism

44848903 4% (272 d) 4% (366 d)

44848904 24% (12 m) 24% (12 m)

44848905 1% (366 d) 1% (366 d)

Anaerobic

Aquatic

Metabolism

44848909 <1% (275 d) <1% (365 d)

44848910 <1% (275 d) <1% (365 d)
Page 14 of 39

Code Name/ 

Synonym Chemical Name Chemical 

Structure

Study 

Type

Reference

(MRID)1

Maximum

Percent 

Recovery 2,3

(time period)

Final

Percent 

Recovery2,3

(study length)

Polar 

Acid -- --

Aqueous Photolysis:

Sterile – Dark

Sterile – Light

Pond – Dark

Pond - Light

44848902/ 

44865802

NR

NR

0.00% (-- d)

5.3% (32 d)

NR

NR

0.00% (-- d)

5.3% (32 d)

Unknown/

Unidentified/ Other -- --

Hydrolysis:

pH 5

pH7

pH9

44848851

0.8% (1 d)

0.7% (7 d)

0.7% (7 d)

0.6% (30 d)

0.7% (30 d)

0.4% (30 d)

Aerobic

Soil

Metabolism

44848903 2% (272 d) 2% (366 d)

44848904 0.4% (2 m) ND (12 m)

44848905 1% (42 d) ND (366 d)

Anaerobic

Aquatic

Metabolism

44848909 <1% (275 d) <1% (365 d)

44848910 <1% (275 d) <1% (365 d)

Abbreviations: d - day; m - month; LOQ - Level of Quantitation; NA - not analyzed; ND - not detected; NR - not reported. 1 When two MRID numbers are separated by “/”, this indicates that the second number is an addendum to the initial study.

2 Values are reported to two significant figures. 3 Bolded values indicate a major degradate was formed.
Page 15 of 39

6. RECEPTORS

Acute (short-term) and chronic (long-term) toxicity information is characterized based on 

registrant-submitted studies and a comprehensive review of the open literature on 

flucarbazone sodium. Reported ecological incidents associated with flucarbazone sodium

are also summarized below.

Table 5 and Table 6 provide summaries of the aquatic and terrestrial taxonomic groups, 

respectively, and surrogate species tested to characterize the potential acute and chronic 

ecological effects of flucarbazone. Toxicity data in these tables were converted from 

measured active ingredient (flucarbazone sodium, 418.28 g/mol) to acid equivalents 

(flucarbazone, 395.29 g/mol) using a molecular weight conversion. Based on the 

available ecotoxicity information, flucarbazone is practically non-toxic to aquatic and 

terrestrial animals on an acute exposure basis and orders of magnitude more toxic to 

vascular plants, which is expected for an herbicide. Relative to vascular aquatic plants, 

non-vascular aquatic plants are orders of magnitude less sensitive, which is consistent 

with the mode of action of this herbicide. Effects to growth and/or reproduction were

also observed in birds, mammals, and fish that were exposed to flucarbazone on a chronic 

basis. 

6.1. Effects to Aquatic Organisms

Table 5. Summary of Aquatic Toxicity Studies for Flucarbazone Sodium

Taxonomic 

Group

Study 

Type

Surrogate Species Toxicity Value

(mg/L measured 

acid equivalent)

Acute 

Toxicity 

Classification 

Source

(MRID)

Freshwater 

fish1

Acute

Rainbow trout

(Oncorhynchus 

mykiss)

LC50 > 91.4 Practically 

nontoxic 44848936

Bluegill sunfish

(Lepomis 

macrochirus)

LC50 > 93.8 Practically 

nontoxic 44848937

Chronic 

(Early 

LifeStage)

Rainbow trout

NOAEC / LOAEC 

= 1.18 / 2.60

Endpoint: 

deformities

-- 44848938

Freshwater 

invertebrates

Acute Daphnia magna EC50 > 103 Practically 

nontoxic 44848934

Chronic Daphnia magna NOAEC / LOAEC 

= 109 / >109 -- 44848935

Estuarine/

marine fish Acute

Sheepshead minnow 

(Cyprinodon 

variegatus)

LC50 = >133 2 Practically 

nontoxic 2 48549305

Estuarine/

marine 

invertebrates

Acute

Eastern oyster 

(Crassostrea 

virginica)

EC50 = >78 2 Practically 

nontoxic 2 48549303
Page 16 of 39

Taxonomic 

Group

Study 

Type

Surrogate Species Toxicity Value

(mg/L measured 

acid equivalent)

Acute 

Toxicity 

Classification 

Source

(MRID)

Acute Mysid shrimp 

(Mysidopsis bahia) LC50 = >113 2 Practically nontoxic 2 48549304

Aquatic 

plants and 

algae

Vascular Duckweed 

(Lemna gibba)

NOAEC = 0.0050

EC50 = 0.0116

Very highly 

toxic 44848950

Nonvascular

Green algae 

(Pseudokirchneriella 

subcapitata)

NOAEC = 2.37

EC50 = 5.26

Moderately 

toxic 44848946

Blue-green algae 

(Anabaena flosaquae)

NOAEC = 5.13

EC50 = 11

Moderately 

toxic 44848947

Freshwater diatom 

(Navicula 

pelliculosa)

NOAEC = 109

EC50 = >109

Practically 

nontoxic 44848948

Marine diatom 

(Skeletonema 

costatum)

NOAEC = 84.3

EC50 = >84.3

Practically 

nontoxic 44848949

1 Freshwater fish may be used as surrogates for aquatic-phase amphibians. 2 Provisional toxicity values and classifications; studies are currently undergoing review.

6.2. Effects to Terrestrial Organisms

Table 6. Summary of Terrestrial Toxicity Studies for Flucarbazone Sodium

Taxonomic 

Group

Study 

Type

Surrogate 

Species

Toxicity Value

(measured acid 

equivalent)

Acute 

Toxicity 

Classification

Source

(MRID)

Birds1

Acute

Bobwhite 

quail

(Colinus 

virginianus)

LD50 >1890 mg/kg Practically 

nontoxic 44848939

Zebra finch 

(Poephila 

guttata)

LD50 >1890 mg/kg 2 Practically 

nontoxic 2 48549306

Sub-acute 

dietary

Bobwhite 

quail LC50 >4391 ppm Practically nontoxic 44848941

Mallard duck

(Anas 

platyrhynchus)

LC50 >4696 ppm Practically 

nontoxic 44848943

Chronic

Bobwhite 

quail

NOAEC / LOAEC = 

1239 / >1239 ppm -- 44848945

Mallard duck

NOAEC / LOAEC = 211

/ 1059 ppm

Endpoints: reduced adult 

body weights, hatching of 

fertile eggs, number of 3-

week embryos per pen

-- 44848944
Page 17 of 39

Taxonomic 

Group

Study 

Type

Surrogate 

Species

Toxicity Value

(measured acid 

equivalent)

Acute 

Toxicity 

Classification

Source

(MRID)

Mammals

Acute Oral

Laboratory rat 

(Rattus 

norvegicus)

LD50 >4725 mg/kg-bw Practically 

nontoxic 44848716

Chronic Laboratory rat 

NOAEC / LOAEC = 

271 / 756 mg/kg-bw/day 

(M)

321 / 937 mg/kg-bw/day 

(F) 

Endpoints: reduced pup 

weights, decreased liver 

weight in male pups, 

marbled liver, air-filled 

stomachs

--

44848745, 

44848746, 

44848747

Insects

Acute 

contact

Honey bee 

(Apis mellifera 

L.)

LD50 = >189 μg/bee Practically 

nontoxic 44848933

Acute oral Honey bee LD50 = >421 μg/bee -- 44848933

Terrestrial 

plants 3

Seedling 

Emergence

Monocot – rye

NOAEC = 0.000624 lb/A

EC25 = 0.000927 lb/A 

Endpoint: seedling dry 

weight

-- 44848929

Dicot – canola

NOAEC = 0.000211 lb/A

EC25 = 0.000455 lb/A 

Endpoint: seedling dry 

weight

-- 44848929

Vegetative

Vigor

Monocot -

onion 

NOAEC = 0.000211 lb/A

EC25 = 0.000379 lb/A 

Endpoint: plant dry 

weight

-- 44848929

Dicot –

buckwheat

NOAEC = 0.000211 lb/A

EC25 = 0.000337 lb/A 

Endpoint: plant dry 

weight

-- 44848929

Abbreviations: F - female; M - male 1 Birds may be used as surrogates for terrestrial-phase amphibians and reptiles. 2 Provisional toxicity values and classifications; studies are currently undergoing review.

3 Note: These endpoints were re-calculated for the most recent risk assessment (USEPA, 2009a).

Degradate Toxicity Data

Data on the toxicity of the flucarbazone sodium degradate MKH 6562 sulfonamide to 

aquatic and terrestrial plants have been submitted to the Agency. The EC50 for duckweed 

(Lemna gibba) was >4.85 mg ai/L in a range-finding study (MRID 44848951). Limit 

tests for seedling emergence and vegetative vigor for the monocot oat and dicots lentil 

and sugar beet resulted in EC25 values of >2.4x10-4 lb ai/A and no signs of phytotoxicity 

for all species and endpoints evaluated (MRIDs 45694901 and 46103701). These data 

suggest that MKH 6562 sulfonamide is less toxic to terrestrial and aquatic vascular plants 

than the parent compound.
Page 18 of 39

6.3. Ecological Incidents

Three databases were searched for ecological incidents possibly associated with 

flucarbazone sodium: the Ecological Incident Information System (EIIS), the aggregate

incident database, and the Avian Monitoring System (AIMS). The 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 AIMS database is administered 

by the American Bird Conservancy and 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 database reports provide counts of ecological incidents 

considered “minor.” These are reported to the Agency quarterly by registrants.

EIIS returned 23 terrestrial plant incidents attributed to flucarbazone sodium use, 18 

incidents with “probable” certainty and 5 with “possible” certainty (USEPA, 2007a). 

The reported incidents for flucarbazone sodium involved 18 uses that are currently 

registered and two in which the legality of the use was not specified. With the exception 

of the two incidents involving potato crops, all reported incidents were to treated fields. 

Three additional incidents were reported involving use on corn, one of which was 

reported as a registered use and two in which the legality of the use was not specified. 

However, flucarbazone sodium has never been registered for use on corn, so these 

incidents should be considered the result of misuses of the herbicide. See Table 7 for a 

list of the incidents reported in EIIS. As of November 8, 2012, AIMS identified no 

ecological incidents involving flucarbazone sodium. 

Table 7. Incidents Reported in EIIS for Flucarbazone Sodium

Incident # Date County State 

Certainty 

Code1

Legality 

Code2

Formulation3App.

Method Total Magnitude

Crop Treated: Corn

I012211-002 6/20/2001 Fremont ID 2 RU DF N/R

Plant damage to 50% 

of treated corn

I012177-006 9/10/2001 McCone MT 2 UN N/R N/R

Stunted growth in 60% 

of treated corn 

I013425-005 8/23/2002 Roosevelt MT 3 UN WDG Broadcast

Plant damage to 1100 

acres of treated corn

Crop Treated: Wheat

I012211-001 6/21/2001 Washington OR 2 RU DF N/R

Plant damage to 50% 

of treated wheat

I012177-005 9/24/2001 Washington OR 2 RU DF N/R

Stunted growth in 

100% of treated wheat 

I013218-007 6/27/2002 Cavalier ND 2 RU DF Broadcast

Plant damage to 100%

of treated wheat

I013312-006 7/17/2002 Pondera MT 3 RU WDG Broadcast

Plant damage to 72% 

of 200 acres of treated 

wheat

I013218-010 7/17/2002 Chouteau MT 3 RU DF N/R

Plant damage to 100% 

of treated wheat

I013218-011 7/18/2002 Gallatin MT 3 RU DF Broadcast Plant damage to 100%
Page 19 of 39

Incident # Date County State 

Certainty 

Code1

Legality 

Code2

Formulation3App.

Method Total Magnitude

of treated wheat

I013312-007 7/22/2002 Dawson MT 3 RU WDG

Broadcast Plant damage to 200 

acres of treated wheat

I013312-003 7/24/2002 Fremont ID 3 RU WDG

Broadcast Plant damage to 500 

acres of treated wheat

I013312-004 7/31/2002 Dawson MT 3 RU WDG

Broadcast Plant damage to 580 

acres of treated wheat

I013312-005 8/7/2002 Liberty MT 3 RU WDG

Broadcast Plant damage to 645 of 

720 acres of treated 

wheat

I013218-009 8/29/2002 Cavalier ND 3 RU DF

Broadcast Plant damage to 65% 

of crop of treated 

wheat

I013218-008 8/29/2002 Pondera MT 3 RU DF

Broadcast Plant damage to 100%

of treated wheat

I013425-004 9/5/2002 Gallatin MT 3 RU WDG

Broadcast Plant damage to 180 

acres of treated wheat

Crop Treated: Spring Wheat

I013425-003 7/18/2002 Teton MT 3 RU WDG Broadcast

Plant damage to 727 

acres of treated spring 

wheat 

I013425-010 7/22/2002 Power ID 3 RU DF Broadcast

Plant damage to 147 

acres of treated spring 

wheat 

I013425-006 7/26/2002 McLean ND 3 RU DF Broadcast

Plant damage to 145 

acres of treated spring 

wheat 

I013425-007 8/11/2002 Chouteau MT 3 RU DF Broadcast

Plant damage to 160 

acres of treated spring 

wheat 

Crop Treated: Winter Wheat

I013425-008 9/22/2002 Blaine MT 3 RU DF Broadcast

Plant damage to 440 

acres of treated winter 

wheat

Crop Treated: Not Recorded

I013425-009 9/19/2002 Fremont ID 3 UN DF N/R

Plant damage to 30 

acres of potato crop 

from carryover

I013548-015 10/2/2002 Fremont ID 3 UN WDG N/R

Plant damage to 302 

acres of potato crop 

from carryover

Abbreviations: App. - Application 1 Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable. N/R=Not 

Reported

2 Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse (Intentional), 

UN=Unknown 3 WDG=Water Dispersible Granule, DF=Dry Flowable

The number of documented incidents in the EIIS is believed to be a very small fraction of 

total mortality caused by pesticides for a variety of reasons. Incident reports for nontarget organisms typically provide information only on mortality events and plant 

damage. Sub-lethal effects in organisms such as abnormal behavior, reduced growth 

and/or impaired reproduction are rarely reported, except for phytotoxic effects in 
Page 20 of 39

terrestrial plants. An absence of reports does not necessarily equate to an absence of 

incidents given the nature of the incident reporting.

In addition to the incidents recorded in the EIIS, registrants have reported minor 

flucarbazone sodium incidents to the Agency in aggregate reports. Registrants reported 

39 minor plant incidents between 2001 and 2002. All minor incidents occurred with use 

of the water dispersible granule formulation. Thirty-one of the 39 minor incidents 

occurred between July 1 and September 30. Unless additional information on these 

aggregated incidents becomes available, they will be assumed to be representative of 

registered uses of flucarbazone sodium in the risk assessment.

7. EXPOSURE PATHWAYS OF CONCERN

The environmental fate properties of flucarbazone sodium indicate that direct spray, 

spray drift, runoff, and leaching represent potential transport mechanisms of this

chemical to aquatic and terrestrial organisms. Drinking water and inhalation exposure 

pathways were screened for this problem formulation using the SIP (Screening 

Imbibition Program) and STIR (Screening Tool for Inhalation Risk) screening methods

(see Appendix A. SIP and STIR Results for details). Potential exposure pathways of 

concern were found for flucarbazone sodium for drinking water but not for inhalation. 

SIP and STIR are described in detail at:

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

Because flucarbazone sodium is persistent and can leach into ground water, there is a 

potential for adverse effects on terrestrial plants when irrigated with a ground waterderived source, particularly in areas where the soil is permeable and/or ground water is 

shallow.

8. ANALYSIS PLAN

8.1. Stressors of Concern

Ecological Risk Assessment

The stressor of ecological concern is the parent compound only. As described in Section 

6, MKH 6562 sulfonamide toxicity data suggest that the primary degradates of 

flucarbazone sodium do not retain the mode of action of the parent compound. ECOSAR 

estimates for all degradates suggest low toxicity and support the use of the parent 

compound as the sole stressor of concern (see Appendix B. ECOSAR Estimates for 

Flucarbazone Sodium and its Degradates).

Drinking Water Assessment

The drinking water assessments conducted to support future human health risk 

assessments of flucarbazone sodium will incorporate model estimates and available 

monitoring data for flucarbazone sodium residues of concern, which are the parent 
Page 21 of 39

compound and the degradate containing the sulfonamide moiety (USEPA, 2000b), in 

surface and ground waters. Estimates of exposure to the total residues of flucarbazone 

sodium containing the sulfonamide moiety will be calculated for consistency with the 

animal enforcement analytical method. The flucarbazone sodium residues of concern 

may be reevaluated pending receipt and review of additional environmental fate and 

toxicity data for flucarbazone sodium and its degradates. 

8.2. Measures of Exposure 

EFED will use standard available models to evaluate potential exposures to aquatic and 

terrestrial organisms as described at 

http://www.epa.gov/pesticides/science/models_db.htm. 

Screening level calculations have suggested that the drinking water exposure pathway

may be significant for flucarbazone sodium for acute and chronic risk to terrestrial 

wildlife. The acute exposure risk was conservatively estimated using non-definitive 

endpoints for both mammals and birds and, based on the lack of any effects observed in 

the studies, it is unlikely that drinking water exposure to flucarbazone poses a risk to 

terrestrial wildlife on an acute basis. Chronic risk to terrestrial wildlife through the 

drinking water exposure pathway may be further considered at the time of the risk 

assessment. 

Estimated concentrations of mobile and persistent herbicides, such as flucarbazone, in 

irrigation water may be calculated to determine potential risk to irrigated crops. As 

detailed above, the persistence, mobility, and solubility of flucarbazone indicate the 

potential for the chemical to reach ground and surface water. 

No water quality monitoring data have been identified for flucarbazone sodium. A 

preliminary review of four national water monitoring programs was completed for this 

problem formulation, including: 1) the California Department of Pesticide Regulation 

(CDPR) surface water database1 (searched 8/9/2013); 2) the USGS NAWQA surface and 

ground water database2 (searched 8/9/2013); 3) the USEPA STORET Data Warehouse3

(searched 8/9/2013); and, 4) the USDA Pesticide Data Program drinking water 

monitoring survey4 (searched 8/14/2013). If monitoring data become available, they will 

be considered at the time of the assessment.

8.3. Measures of Effect 

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

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

 1 http://www.cdpr.ca.gov/docs/emon/surfwtr/surfcont.htm, 2 http://infotrek.er.usgs.gov/apex/f?p=136:1:0::NO:::

3 http://www.epa.gov/storet/

4 http://www.ams.usda.gov/AMSv1.0/ams.fetchTemplateData.do?template=TemplateG&navID=&rightNav 

1=&topNav=&leftNav=ScienceandLaboratories&page=PDPDownloadData/Reports&resultType=&acct=p

estcddataprg
Page 22 of 39

open literature prior to conduct of the risk assessment will also be considered. The open 

literature studies are identified using EPA’s ECOTOXicology database (ECOTOX) 

(USEPA, 2007b), 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.

8.4. Endangered Species Assessments

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

the Agency will 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.

8.5. Endocrine Disruptor Screening Program

Flucarbazone sodium was not included in the first group of 67 chemicals issued an order 

to conduct Tier 1 EDSP testing nor in the second group of 109 chemicals. For additional 

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

9. PRELIMINARY IDENTIFICATION OF DATA GAPS

9.1. Environmental Fate

Table 8 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 to 

support risk assessment. Aerobic soil metabolism data for two additional soils are 

needed, since only two soils were studied in submitted reports. An additional aerobic 

aquatic metabolism study is also needed if the submitted study is classified as 

unacceptable (MRID 48648501 is currently under review). 

Table 9 summarizes submitted environmental fate studies for flucarbazone sodium

degradates. Additional data on degradates are not needed since these degradates were 

determined to be less toxic than the parent compound to aquatic organisms and sufficient 

data are available for human drinking water assessment.
Page 23 of 39

Table 8. Submitted Environmental Fate Data for Flucarbazone Sodium

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)1

Study 

Classification

Are additional

data needed to 

conduct risk 

assessment?

Justification 

835.2120 Hydrolysis 44848851 Acceptable No --

835.2240 Aqueous 

Photolysis

44848902/

44865802

Acceptable No --

835.2410 Soil

Photolysis

44848901 Supplemental No --

835.4100 Aerobic

Soil 

Metabolism

44848903 Acceptable Yes Guideline-compliant data are 

needed for two additional 

soils.

44848904 Acceptable

44848905 Acceptable

835.4300 Aerobic 

Aquatic 

Metabolism

44848906 Unacceptable ND2 If MRID 48648501 is 

unacceptable upon review, 

then a guideline-compliant 

study of two systems will be 

needed.

44848907 Unacceptable

44848908 Unacceptable

48648501 (In review)

835.4400 Anaerobic 

Aquatic 

Metabolism

44848909 (In review) No --

44848910 Acceptable

44848911 Unacceptable

835.1230/

835.1240

Adsorption/ 

Desorption and 

Leaching

44848912 Acceptable No --

44848918 Acceptable

44848919 Acceptable

44848921 (In review)

835.6100 Terrestrial 

Field Dissipation

44848922/ 

45083705

Acceptable No --

44848923/ 

45083704

Acceptable

44848924/ 

45083703

Acceptable

44848925 Supplemental

44848926 Supplemental

46223703 Acceptable

46223704 Acceptable

Analytical 

Method in Soil3

44848845 & 

44848848

(In review)

46223702

(46926101)

Acceptable

Freezer 

Storage Stability

(in soil)

44848920 (In review)

850.6100 Analytical 

Method in 

Water3

44848850

(46926102)

Acceptable No --

45602401

(46926102)

Acceptable No

1 When two MRID numbers are listed and separated by a “/”, this indicates the second MRID is an 

addendum to the original MRID.

2 ND means “not yet determined; studies are in review.”
Page 24 of 39

3 MRID in parenthesis reflect an independent laboratory validation (ILV).

Table 9. Submitted Environmental Fate Data for Flucarbazone Sodium Degradates

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)1

Degradate Study 

Classification

Are additional 

data needed to 

conduct risk 

assessment?

Justification

835.2120 Hydrolysis 45823001 O-desmethyl (In review) No --

835.4100 Aerobic

Soil 

Metabolism

46083801 Sulfonamide (In review) No --

835.1230

835.1240

Adsorption/ 

Desorption 

and Leaching

44848913 Methyltriazolinone

(NMT)

Unacceptable No --

44848914/ 

45083702

Sulfonamide Acceptable

44848915 Sulfonic Acid Acceptable

44848916/

45083701

Dimethoxytrizo

linone

Acceptable

44848917 Sulfonamide; 

Sulfonic Acid; 

O-desmethyl; 

Dimethoxytrizo

linone

Unacceptable

Analytical 

method 

in 

Soil

44848845/

44848848

Sulfonamide; 

Sulfonic Acid; 

Methoxytrizoli

none (NMT)

(In review) No --

44848847 &

44848927

O-desmethyl (In review)

46223702/

46926101

Sulfonamide; 

Sulfonic Acid; 

Dimethoxytrizo

linone (NODT)

Acceptable

46223701/

46926103

O-desmethyl Acceptable No --

835.7100 Analytical 

Method 

in 

Water2

45602401/

(46926102)

Sulfonamide; 

Sulfonic Acid; 

Dimethoxytrizo

linone (NODT)

(In review)

No --

1 When two MRID numbers are listed and separated by a “/”, this indicates the second MRID is an 

addendum to the original MRID.

2 MRID in parenthesis reflect an independent laboratory validation (ILV).

9.2. Effects

Table 10 and Table 11 identify ecological effects 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. Additional data will be required only 

if one or more of the submitted studies currently undergoing review are classified as 

unacceptable. These studies are indicated in the tables below.
Page 25 of 39

Table 10. Submitted Aquatic Ecological Effects Data for Flucarbazone Sodium

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are additional

data needed to 

conduct risk 

assessment?

Justification

850.1010 Freshwater 

invertebrate 

acute toxicity

44848934 Acceptable No --

850.1025

850.1035

Saltwater 

invertebrate 

acute toxicity 

48549303 (In review) ND1 A new study is needed if the 

studies in review are 

unacceptable. 48549304 (In review)

850.1075 Freshwater 

fish acute 

toxicity 

44848936 Acceptable No --

44848937 Acceptable

850.1075 Saltwater fish 

acute toxicity 

48549305 (In review) ND1 A new study is needed if the 

study in review is unacceptable.

850.1300 Freshwater 

invertebrate 

life cycle 

44848935 Acceptable No --

850.1350 Saltwater 

invertebrates 

life cycle 

(None) (N/A) No No acute effects were seen in 

toxicity studies of flucarbazone 

sodium on freshwater or 

saltwater aquatic invertebrates. 

No chronic effects were seen in 

a toxicity study on freshwater 

invertebrates. Therefore, 

flucarbazone sodium is not 

expected to pose a risk to 

saltwater invertebrates on a 

chronic exposure basis.

850.1400 Freshwater 

fish 

early-life 

stage

44848938 Acceptable No --
Page 26 of 39

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are additional

data needed to 

conduct risk 

assessment?

Justification

850.1400 Saltwater fish 

early-life 

stage 

(None) (N/A) No No acute effects were seen in 

toxicity studies of flucarbazone 

sodium on freshwater or 

saltwater fish. Effects were 

seen in the early-life stage study 

with freshwater fish, however 

the NOAEC was 1.18 mg ae/L, 

over three orders of magnitude 

greater than the 60-day EEC 

calculated in the previous 

assessment. Therefore, 

flucarbazone sodium is not 

expected to pose a risk to 

saltwater fish on a chronic 

exposure basis at 

environmentally relevant 

concentrations.

850.1500 Fish life 

cycle 

(None) (N/A) No --

850.4400 Aquatic plant 

growth:

Tier II 

vascular 

plants

44848950 Acceptable No --

850.4500

(previously 

850.5400)

Aquatic Plant 

Growth:

Tier II algae

44848946 Acceptable No --

44848947 Acceptable 

44848948 Acceptable

44848949 Acceptable 1 ND means “not yet determined; studies are in review.”

Table 11. Submitted Terrestrial Ecological Effects Data for Flucarbazone Sodium

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are additional

data needed to 

conduct risk 

assessment?

Justification 

850.2100 Avian oral 

toxicity

44848939 Acceptable ND1 A new study is needed if the 

study in review is 

unacceptable. 48549306 (In review)

850.2200 Avian dietary 

toxicity 

44848941 Acceptable No --

44848943 Acceptable

850.2300 Avian 

reproduction

44848944 Acceptable No --

44848945 Acceptable
Page 27 of 39

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are additional

data needed to 

conduct risk 

assessment?

Justification 

NonguidelineAvian 

inhalation

(None) (N/A) No Inhalation was not identified 

as a potential exposure 

pathway of concern by the 

screening level model STIR.

850.3020 Honey bee 

acute contact 

toxicity

44848933 Acceptable No --

850.3030 Honey bee 

residue on 

foliage

(None) (N/A) No --

850.3040 Field testing 

for 

pollinators

(None) (N/A) No --

850.4100 Terrestrial 

plant toxicity:

Seedling 

emergence

44848929 Acceptable No --

850.4150 Terrestrial 

plant toxicity:

Vegetative 

vigor

44848929 Acceptable No --

1 ND means “not yet determined; studies are in review.”

10. REFERENCES

USEPA. 2000a. EFED New Chemical Review for Flucarbazone-Sodium. U.S. 

Environmental Protection Agency, Office of Prevention, Pesticides and Toxic 

Substances, Environmental Fate and Effects Division. Sept 13, 2000.

USEPA. 2000b. Values to be used in estimating Drinking Water exposure from residues 

of Flucarbazone sodium (MKH 6562) from use on wheat. U.S. Environmental 

Protection Agency, Office of Prevention, Pesticides and Toxic Substances, 

Environmental Fate and Effects Division. Memorandum to the Health Effects 

Division. Aug 14, 2000.

USEPA. 2004. Flucarbazone-Sodium: 24C Request for Aerial Application. DP Barcode 

251602. U.S. Environmental Protection Agency, Office of Prevention, Pesticides 

and Toxic Substances, Environmental Fate and Effects Division. Memorandum to 

the Registration Division. July 20, 2004.

USEPA. 2006. Standardized Soil Mobility Classification Guidance. U.S. Environmental 

Protection Agency, Office of Prevention, Pesticides and Toxic Substances, 

Environmental Fate and Effects Division. Memorandum to the Environmental 

Fate and Effects Division. April 21, 2006.
Page 28 of 39

USEPA. 2007a. Ecological Incident Information System. 

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

USEPA. 2007b. 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. 2009a. Ecological Risk Assessment for the Proposed Registration of 

Flucarbazone sodium for New Uses on Turf and Conifer Tree Nurseries. U.S. 

Environmental Protection Agency, Office of Prevention, Pesticides and Toxic 

Substances, Environmental Fate and Effects Division. Memorandum to the 

Registration Division. July 22, 2009.

USEPA.2009b. Tier I Drinking Water Assessment for Flucarbazone-Na on turf, tree 

nurseries, and Christmas tree farms. U.S. Environmental Protection Agency, 

Office of Prevention, Pesticides and Toxic Substances, Environmental Fate and 

Effects Division. Memorandum to the Registration Division. Mar 24, 2009.

USEPA. 2009c. Guidance for Selecting Input Parameters in Modeling the Environmental 

Fate and Transport of Pesticides. Version 2.1. U.S. Environmental Protection 

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

Oct. 22, 2009. Online at: 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

USEPA.2010. Guidance for Making Temperature Adjustments to Metabolism Inputs to 

EXAMS and PE5. U.S. Environmental Protection Agency, Office of Prevention, 

Pesticides and Toxic Substances, Environmental Fate and Effects Division. 

Memorandum to the Registration Division. October 18, 2010.

USEPA. 2013. Screening Level Usage Analysis. U.S. Environmental Protection Agency, 

Office of Chemical Safety and Pollution Prevention, Biological and Economic 

Analysis Division. May 7, 2013. 

Ware, G. W. and D. M. Whitacre. 2004. An Introduction to Herbicides. In The 

Pesticide Book, 6th ed; Radcliffe, E. B, Hutchison, W. D. Eds.; MeisterPro 

Information Resources: Willoughby, OH, 2004. Available at 

http://ipmworld.umn.edu/chapters/whitacreherb.htm.

Wood, A. 2007. Compendium of Pesticide Common Names. Available at: 

http://www.alanwood.net/pesticides/index.html.
Page 29 of 39

MRID Citation

Environmental Fate and Product Chemistry Studies

44848845 Peterson, R.; Bethem, R.; Lam, C. et al. (1997) Method Validation for the Analysis of 

Soils for MKH 6562 and Three Metabolite Residues: Lab Project Number: 107530: 

M2112101: BAYKS01E-2. Unpublished study prepared by Alta Analytical Laboratory, 

Inc. 105 p.

44848847 Morby, R.; McKinney, M.; Lam, C. et al. (1998) Analytical Method for the Determination 

of O-Desmethyl MKH 6562 (Metabolite of MKH 6562) in Soil by High-Performance 

Liquid Chromatography Tandem Mass Spectrometry (HPLC/MS/MS): Lab Project 

Number: 98B38: 107530-2. Unpublished study prepared by Bayer Corp. 43 p.

44848848 Perkins, J.; Anderson, D.; Lowes, S. (1997) Independent Laboratory Validation of

Analytical Method for the Determination of MKH 6562 and Three Metabolite Residues in

Soil: Lab Project Number: AL6562ILV: 107811: M6112102. Unpublished study prepared

by Advance BioAnalytical Services, Inc. and Alta Analytical Laboratory, Inc. 61 p.

44848850 Mattern, G.; Lam, C. (1998) Determination of MKH 6562 in Water by HPLC: Lab Project 

Number: 108125. Unpublished study prepared by Bayer Corp. 14 p.

44848851 Mattern, G.; Green, D. (1995) Aqueous Hydrolysis of (Phenyl-U-(carbon-14)) MKH 6562 

in Sterile Buffer Solutions: Lab Project Number: 106950: M2072401. Unpublished study

prepared by Bayer Corp. 30 p.

44848901 Green, D.; Mattern, G. (1997) Photolysis of (Phenyl-U-(carbon-14)) MKH 6562 in North 

Dakota Sandy Loam: Lab Project Number: 107393: M2082101. Unpublished study 

prepared by Bayer Corporation. 49 p.

44848902 Mattern, G.; Green, D.; Leimkuehler, W. (1996) Aqueous Photolysis of (Phenyl-U-

(carbon-14)) MKH 6562 in Sterile Buffer and Manitoba Pond Water: Lab Project Number: 

106969: M2082401. Unpublished study prepared by Bayer Corporation. 59 p.

44848903 Pangilinan, N.; Smith, D.; Jackson, S. et al. (1997) Aerobic Metabolism of (Phenyl-U-

(carbon-14)) MKH 6562 in North Dakota Sandy Loam: Lab Project Number: M2042102: 

107814. Unpublished study prepared by Bayer Corporation. 64 p.

44848904 Pangilinan, N.; Jackson, S.; Jones, L. et al. (1998) Aerobic Metabolism of (Triazolinone-3-

(carbon-14)) MKH 6562 in North Dakota Sandy Loam: Lab Project Number: M2042103: 

107823. Unpublished study prepared by Bayer Corporation. 72 p.

44848905 Pangilinan, N.; Smith, D.; Jones, L. et al. (1938) Aerobic Metabolism of (Phenyl-UL-

(carbon-14)) MKH 6562 in Manitoba Sandy Loam: Lab Project Number: M2042104:

107815. Unpublished study prepared by Bayer Corporation. 78 p.

44848906 Kelley, I.; McKinney, M.; Bormann, T. (1997) Degradation and Fate of (Phenyl-UL-

(carbon-14)) MKH 6562 in Pond Water: Lab Project Number: M2042402: 107140.

Unpublished study prepared by Bayer Corporation. 51 p.

44848907 Parker, G.; Kelley, I. (1998) Aerobic Aquatic Biotransformation of (Phenyl-UL-(carbon14)) MKH 6562: Lab Project Number: M2042405: 107911. Unpublished study prepared 

by Bayer Corporation. 42 p.

44848908 Kelley, I.; McKinney, M. (1997) Aerobic Aquatic Biotransformation of (Triazolinon-3-

(carbon-14)) MKH 6562: Lab Project Number: M2042403: 107827. Unpublished study

prepared by Bayer Corporation. 43 p.

44848909 Blumhorst, M.; Chopade, H. (1998) Anaerobic Aquatic Metabolism of (Phenyl-UL-

(carbon-14)) MKH 6562 at 5 (degrees) C: Lab Project Number: M2042406: 122S22: 

108313. Unpublished study prepared by EPL Bio-Analytical Services, Inc. 89 p.

44848910 Halarnkar, P.; Irwin, D. (1997) Anaerobic Aquatic Metabolism of (Phenyl-UL-(carbon14)) MKH 6562: Lab Project Number: M2042401: 107742. Unpublished study prepared 

by Bayer Corporation. 49 p.

44848912 Blumhorst, M.; Lin, H. (1995) Soil Adsorption/Desorption of MKH 6562: Lab Project 

Number: M2182101: 122S21: 106976. Unpublished study prepared by EPL BioAnalytical Services, Inc. 90 p.
Page 30 of 39

MRID Citation

44848913 Hein, W.; Yen, P. (1998) Adsorption/Desorption of (Carbon-14)N-Methyltriazolinone, an 

(Carbon-14)MKH 6562 Metabolite, in Four Soil Types: Lab Project Number: M2182102: 

BAC10: 108272. Unpublished study prepared by Staatliche Lehr-und Forschungsanstalt 

fuer Landwirtschaft, Weinbau und Gartenbau. 41 p.

44848914 Hein, W.; Yen, P. (1998) Adsorption/Desorption of (Carbon-14)MKH 6562 Sulfonamide, 

an (Carbon-14)MKH 6562 Metabolite, in Four Soil Types: Lab Project Number: 

M2182103: BAC07: 108273. Unpublished study prepared by Staatliche Lehr-und 

Forschungsanstalt fuer Landwirtschaft, Weinbau und Gartenbau. 55 p.

44848915 Hein, W.; Yen, P. (1998) Adsorption/Desorption of (Carbon-14)MKH 6562 Sulfonic Acid,

an (Carbon-14)MKH 6562 Metabolite, in Four Soil Types: Lab Project Number:

M2182104: BAC08: 108274. Unpublished study prepared by Staatliche Lehr-und

Forschungsanstalt fuer Landwirtschaft, Weinbau und Gartenbau. 26 p.

44848916 Hein, W.; Yen, P. (1998) Adsorption/Desorption of (Carbon-14)N,ODimethyltriazolinone, an (Carbon-14)MKH 6562 Metabolite, in Four Soil Types: Lab 

Project Number: M2182105: BAC09: 108275. Unpublished study prepared by Staatliche 

Lehr-und Forschungsanstalt fuer Landwirtschaft, Weinbau und Gartenbau. 55 p.

44848917 Blumhorst, M.; Yen, P. (1998) Adsorption/Desorption of (carbon-14)MKH 6562

Sulfonamide, (carbon-14)MKH Sulfonic Acid, (carbon-14)N,O-Dimethyltriazolinone,

(carbon-14)-Methyltriazolinone, and (carbon-14)O-Desmethyl MKH 6562 by Soil from

Richland County, ND; and (carbon-14)Methyltriazolinone by Sand: Lab Project Number:

M2182106: 108276: 122S26. Unpublished study prepared by EPL Bio-Analytical 

Services, Inc. 109 p.

44848918 Smith, D.; Pangilinan, N. (1998) Leaching of Aged (Phenyl-UL-(carbon-14))MKH 6562 

Residues Through Tiffany Sandy Loam: Lab Project Number: M2092101: 107816. 

Unpublished study prepared by Bayer Corporation. 61 p.

44848919 Jackson, S.; Pangilinan, N. (1998) Leaching of Aged (Triazolinone-3-(carbon-14))MKH

6562 Residues Through Tiffany Sandy Loam: Lab Project Number: M2092102: 108256.

Unpublished study prepared by Bayer Corporation. 67 p.

44848920 Billesbach, K. (1998) Freezer Storage Stability of (carbon-14)MKH 6562 Sulfonamide, 

and (carbon 14)MKH 6562 Sulfonic Acid in Soil: Lab Project Number: M2132101: 

108138. Unpublished study prepared by Bayer Corporation. 45 p.

44848921 Mattern, G.; Green, D.; Parker, G. (1995) Outdoor Metabolism and Leaching of (PhenylUL-(carbon-14))MKH 6562 in Lysimeters: Lab Project Number: M2042101: 106931.

Unpublished study prepared by Bayer Corporation. 44 p.

44848922 Philpot, J.; Yen, P. (1998) Terrestrial Field Dissipation of MKH 6562 on Bare Loam in

Alberta, 1996: Lab Project Number: M2022103: 108133. Unpublished study prepared by

Ag-Quest (ALTA) Inc. and Bayer Corporation. 201 p.

44848923 Philpot, J.; Yen, P. (1998) Terrestrial Field Dissipation of MKH 6562 on Orthic Brown

Soil in Outlook, Saskatchewan, 1996: Lab Project Number: M2022104: 108134.

Unpublished study prepared by Ag-Quest (ALTA) Inc., and Bayer Corporation. 194 p.

44848924 Philpot, J.; Yen, P. (1998) Terrestrial Field Dissipation of MKH 6562 on Dark Brown Soil 

in Saskatoon, Saskatchewan, 1996: Lab Project Number: M2022105: 108135. 

Unpublished study prepared by Ag-Quest (ALTA) Inc. and Bayer Corporation. 186 p.

44848925 Harbin, A.; Wood, S. (1998) Terrestrial Field Dissipation of MKH 6562 in Washington

Soil, 1996: Lab Project Number: BAYKS01E-4: M2022102: 108255. Unpublished study

prepared by Qualls Agricultural Laboratory and Alta Analytical Laboratory, Inc. 226 p.

44848926 Harbin, A.; Wood, S. (1998) Terrestrial Field Dissipation of MKH 6562 in North Dakota 

Soil, 1996: Lab Project Number: AGV96034: BAYKS01E-3: M2022101. Unpublished 

study prepared by Agvise Laboratories Inc. and Alta Analytical Laboratory, Inc. 186 p.

44848927 Wiedmann, J. (1999) Independent Laboratory Validation of Bayer Method (Report 

Number 107530-2) for the Determination of O-Desmethyl MKH 6562 (Metabolite of 

MKH 6562) in Soil: Lab Project Number: 7672-98-0154-CR-001: M2112103: 108810. 

Unpublished study prepared by Ricerca, Inc. 149 p.
Page 31 of 39

MRID Citation

44865801 Fontaine, L. (1999) Product Chemistry of MKH 6562 Technical: Lab Project Number: 

107273: 108409: 108410. Unpublished study prepared by Bayer Corporation. 102 p.

44865802 Hellpointner, E. (1995) Assessment of the Environmental Half-life of the Direct

Photodegradation of MKH 6562 in Water: Lab Project Number: M143 0710-6: 107\123.

Unpublished study prepared by Bayer Corporation. 18 p.

45083701 Hein, W. (1999) Adsorption/Desorption of (carbon-14)N,O-Dimethyltriazolinone, an 

(carbon-14)MKH 6562 Metabolite, in Four Soil Types: Lab Project Number: M2182105: 

108275-1: BAC09. Unpublished study prepared by Staatliche Lehr-und Forschungsanstalt 

fur Landwirtschaft, Weinbau, und Gartenbau. 21 p.

45083702 Hein, W. (1999) Adsorption/Desorption of (carbon-14)MKH 6562 Sufonamide, an 

(carbon-14)MKH 6562 Metabolite, in Four Soil Types: Lab Project Number: M2182103: 

BAC07: 108273-1. Unpublished study prepared by Staatliche Lehr-und Forschungsanstalt 

fur Landwirtschaft, Weinbau, und Gartenbau. 21 p.

45083703 Mattern, G. (1999) Terrestrial Field Dissipation of MKH 6562 on Dark Brown Soil in 

Saskatoon, Saskatchewan, 1996-Report Addendum 1: Lab Project Number: M2022105: 

108135: 108135-1. Unpublished study prepared by Bayer Corporation. 8 p.

45083704 Mattern, G. (1999) Terrestrial Field Dissipation of MKH 6562 on Orthic Brown Soil in 

Outlook, Saskatchewan, 1996-Report Addendum 1: Lab Project Number: M2022104: 

108134: 108134-1. Unpublished study prepared by Bayer Corporation. 8 p.

45083705 Mattern, G. (1999) Terrestrial Field Dissipation of MKH 6562 on Bare Loam in Alberta, 

1996-Report Addendum 1: Lab Project Number: M2022103: 108133: 108133-1. 

Unpublished study prepared by Bayer Corporation. 8 p.

45602401 Lam, C.; Morby, R.; Leimkuehler, W. (1999) Analytical Method for the Determination of

MKH 6562 and Three Metabolites in Ground Water by High-Performance Liquid

Chromatography Tandem Mass Spectrometry (LC/MS/MS): Lab Project Number: 108919.

Unpublished study prepared by Bayer Corp. 36 p.

45823001 Aga, D.; Smith, D.; Arthur, E. (2002) Hydrolysis of O-desmethyl MKH 6562-

triazolidinine-3,5-(Carbon 14) at pH 3, 5, 7 and 9 in Sterile Aqueous Buffer: Lab Project 

Number: M2072402: 200145. Unpublished study prepared by Bayer Corporation. 57 p.

46083801 Ripperger, R.; Hall, L. (2003) Aerobic Soil Metabolism of (Carbon 14) MKH 6562 

Sulfonamide. Project Number: 200255, M2042105. Unpublished study prepared by Bayer 

Corp. 54 p.

46223701 Lam, C.; Qadri, S. (2003) Analytical Method for the Determination of O-Desmethyl MKH 

6562 (Metabolite of MKH 6562) in Soil by High-Performance Liquid Chromatography 

Tandem Mass Spectrometry (LC-MS/MS). Unpublished study prepared by Bayer Corp. 36 

p.

46223702 Lam, C.; Qadri, S. (2003) Analytical Method for the Determination of MKH 6562 and 

Metabolites NODT, Sulphonic Acid, and Sulphonamide in Soil by High-Performance 

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS). Unpublished study 

prepared by Bayer Corp. 43 p.

46223703 Wood, S. (2004) Terrestrial Field Dissipation of MKH6562 in Washington Soil, 2002. 

Project Number: M2022107, F02502/0001. Unpublished study prepared by Qualls 

Agricultural Laboratories, I, Bayer Corp. and A & L Great Lakes Laboratories. 117 p.

46223704 Wood, S.E. (2004) Terrestrial Field Dissipation of MKH6562 in Oklahoma Soil, 2001. 

Project Number: M2022106, F02500-0001. Unpublished study prepared by South Central 

Ag Research, Bayer Corp. and A & L Great Lakes Laboratories. 111 p.

46926101 Nelson, S. (2006) Independent Laboratory Validation of Method 200748: "Analytical 

Method for the Determination of MKH 6562 and Metabolites NODT, Sulfonic acid, and 

Sulfonamide in Soil by High Performance Liquid Chromatography Tandem Mass 

Spectrometry (LC-MS/MS): Final Report. Project Number: 05ILV01ARY, 

06ARY01/REP, 200748. Unpublished study prepared by ALS Laboratory Group, 

Environmental and Bayer Corp. 172 p.
Page 32 of 39

MRID Citation

46926102 Nelson, S. (2006) Independent Laboratory Validation of Method 108919 - "Analytical 

Method for the Determination of MKH 6562 and Three Metabolites in Ground Water by 

High Performance Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)": 

Final Report. Project Number: 05ILV02ARY, 06ARY02/REP, 108919. Unpublished study 

prepared by ALS Laboratory Group, Environmental and Bayer Corp. 171 p.

46926103 Nelson, S. (2006) Independent Laboratory Validation of Method 200747 - "Analytical

Method for the Determination of O-Desmethyl MKH 6562 (Metabolite of MKH 6562) in

Soil by High Performance Liquid Chromatography Tandem Mass Spectrometry (LCMS/

MS)". Project Number: 05ILV03ARY, 06ARY03/REP, 200747. Unpublished study

prepared by ALS Laboratory Group, Environmental and Bayer Corp. 102 p.

48648501 Stenzel, J.I.; E.C. Schaefer (2011) Flucarbazone: Aerobic Aquatic Metabolism. Project 

Number: 443E/101/OCR. Unpublished study prepared by Wildlife International, Ltd. 

103p.

Ecological Effects Studies

44848716 Krotlinger, F. (1998) MKH 6562: Study for Acute Oral Toxicity in Rats: Lab Project 

Number: 23612: T 9055577: 107197. Unpublished study prepared by Bayer AG. 28 p.

44848745 Eiben, R. (1998) MKH 6562: Two-Generation Study in Wistar-Rats: Lab Project Number: 

27555: T8061038: 108382. Unpublished study prepared by Bayer AG. 976 p.

44848746 Eiben, R. (1998) MKH 6562: Two-Generation Study in Wistar-Rats: Supplemental Report: 

Lab Project Number: 27555 A: T8061038: 108382-1. Unpublished study prepared by 

Bayer AG. 29 p.

44848747 Eiben, R. (1998) MKH 6562: Two-Generation Study in Wistar-Rats: Supplemental Report: 

Lab Project Number: 108382-2: T8061038: 27555 B. Unpublished study prepared by 

Bayer AG. 22 p.

44848928 Bowers, L. (1997) Toxicity of MKH 6562 70 WG to Lemna gibba G3 Under Spray 

Application Conditions: Lab Project Number: M2883702: 107697. Unpublished study 

prepared by Bayer Corporation. 35 p. 

44848929 Hancock, G.; Hansen, C. (1998) Tier 2 Seedling Emergence and Vegetative Vigor: 

Nontarget Phytotoxicity Study Using MKH 6562 70% WG: Lab Project Number: 

M2201602: 108315. Unpublished study prepared by Bayer Corporation. 97 p. 

44848930 Hancock, G.; Hansen, C. (1998) Supplemental Data for Report Number 108315: Tier 2 

Seedling Emergence and Vegetative Vigor: Nontarget Phytotoxicity Study Using MKH 

6562 70% WG: Lab Project Number: M2201602: 108315-1. Unpublished study prepared 

by Bayer Corporation. 28 p. 

44848931 Heimbach, F. (1997) Acute Toxicity of MKH 6562 (tech.) to Earthworms (Eisenia fetida): 

Lab Project Number: E 310 1220-9: 108271: HBF/RG 252. Unpublished study prepared 

by Bayer AG. 19 p. 

44848932 Heimbach, F. (1998) Acute Toxicity of 4-Methylurazole (a Metabolite of MKH 6562) to 

Earthworms (Eisenia fetida): Lab Project Number: E 310 1318-7: 108743: HBF/RG 266. 

Unpublished study prepared by Bayer AG. 21 p. 

44848933 Schmitzer, S. (1998) Laboratory Testing for Toxicity (Acute Contact and Oral LD50) of 

MKH 6562 techn. on Honey Bees (Apis mellifera L.) (Hymnoptera, Apidae): Lab Project 

Number: 4180036: 108537. Unpublished study prepared by Institute for Biological 

Analysis and Consulting IBACON GmbH. 30 p. 

44848934 Bowers, L. (1996) Acute Toxicity of MKH 6562 to the Waterflea (Daphnia magna) Under 

Static Conditions: Lab Project Number: M2820701: 107340. Unpublished study prepared 

by Bayer Corporation. 29 p. 

44848935 Bowers, L. (1996) Chronic Toxicity of MKH 6562 to the Waterflea (Daphnia magna) 

Under Static Renewal Conditions: Lab Project Number: M2840701: 107356. Unpublished 

study prepared by Bayer Corporation. 52 p. 

44848936 Bowers, L. (1995) Acute Toxicity of MKH 6562 Technical to the Rainbow Trout 

(Ocorhynchus mykiss) Under Static-Renewal Conditions: Lab Project Number: 

M2812201: 107143. Unpublished study prepared by Bayer Corporation. 27 p. 
Page 33 of 39

MRID Citation

44848937 Bowers, L. (1995) Acute Toxicity of MKH 6562 Technical to the Bluegill (Lepomis 

machrochirus) Under Static-Renewal Conditions: Lab Project Number: M2810301: 

107136. Unpublished study prepared by Bayer Corporation. 27 p. 

44848938 Hall, A. (1998) Early Life Stage Toxicity of MKH 6562 to the Rainbow Trout 

(Oncorhynchus mykiss) Under Flow-Through Conditions: Lab Project Number: 

M2842201: 107838. Unpublished study prepared by Bayer Corporation. 74 p. 

44848939 Toll, P. (1995) Technical MKH 6562: An Acute Oral LD50 with Northern Bobwhite 

(Colinus viginianus): Lab Project Number: M2711701: 107100. Unpublished study 

prepared by Bayer Corporation. 25 p.

44848940 Hancock, G. (1997) Technical MKH 6562: A Subacute Dietary LC50 with Northern 

Bobwhite: Lab Project Number: M2721701: 107359. Unpublished study prepared by 

Bayer Corporation. 43 p.

44848941 Hancock, G. (1998) Technical MKH 6562: A Subacute Dietary LC50 with Northern 

Bobwhite: Lab Project Number: M2721702: 108461. Unpublished study prepared by 

Bayer Corporation. 47 p. 

44848942 Hancock, G. (1997) Technical MKH 6562: A Subacute Dietary LC50 with Mallard Ducks: 

Lab Project Number: M2720801: 107102. Unpublished study prepared by Bayer 

Corporation. 42 p. 

44848943 Hancock, G. (1998) Technical MKH 6562: A Subacute Dietary LC50 with Mallards: Lab 

Project Number: M2720802: 108460. Unpublished study prepared by Bayer Corporation. 

46 p. 

44848944 Hancock, G. (1998) Effect of Technical MKH 6562 on Mallard Reproduction: Lab Project 

Number: M2740801: 108491. Unpublished study prepared by Bayer Corporation. 106 p. 

44848945 Hancock, G. (1998) Effect of Technical MKH 6562 on Northern Bobwhite Reproduction: 

Lab Project Number: M2741701: 108492. Unpublished study prepared by Bayer 

Corporation. 117 p. 

44848946 Dobbs, M. (1996) Toxicity of MKH 6562 to Freshwater Green Alga Selenastrum 

capricornutum: Lab Project Number: M2883501: 107377. Unpublished study prepared by 

Bayer Corporation. 30 p. 

44848947 Bowers, L. (1998) Toxicity of MKH 6562 to the Blue-Green Alga Anabaena flos-aquae: 

Lab Project Number: M2831401: 107836. Unpublished study prepared by Bayer 

Corporation. 32 p. 

44848948 Hall, A. (1998) Toxicity of MKH 6562 to the Freshwater Diatom Navicula pelliculosa: 

Lab Project Number: M2883401: 107743. Unpublished study prepared by Bayer 

Corporation. 32 p. 

44848949 Bowers, L.; Lam, C. (1998) Toxicity of MKH 6562 Technical to the Marine Diatom 

Skeletonema costatum: Lab Project Number: M2883601: 108452. Unpublished study 

prepared by Bayer Corporation. 33 p. 

44848950 Bowers, L.; Lam, C. (1998) Toxicity of MKH 6562 Technical to Lemna gibba G3: Lab 

Project Number: M2883701: 107917. Unpublished study prepared by Bayer Corporation. 

34 p. 

44848951 Hall, A.; Lam, C. (1999) Toxicity of MKH 6562 Sulfonamide, a Metabolite of MKH 6562, 

to Lemna gibba G3: Lab Project Number: 96-B-158: 108933. Unpublished study prepared 

by Bayer Corporation. 28 p. 

45694901 Bowers, L. (2000) Tier 1 Seedling Emergence and Vegetative Vigor Nontarget 

Phytotoxicity Study Using MKH 6562 Sulfonamide (a Metabolite of MKH 6562): Lab 

Project Number: M2451301: M2451302: 109475. Unpublished study prepared by Bayer 

Corporation. 79 p.

46103701a Bowers, L.M. 2005. Tier 1 Seedling Emergence and Vegetative Vigor Nontarget 

Phytotoxicity Study Using MKH 6562 sulfonamide (a metabolite of MKH 6562) on Lentil, 

Oat, and Sugarbeet. Unpublished study performed and sponsored by Bayer CropScience, 

Stillwell, Kansas, and Research Triangle Park, North Carolina, respectively. Report no.: 

200711. Study completed October 9, 2003. 
Page 34 of 39

MRID Citation

46103701b Bowers, L.M. 2005. Tier 1 Seedling Emergence and Vegetative Vigor Nontarget 

Phytotoxicity Study Using MKH 6562 sulfonamide (a metabolite of MKH 6562) on Lentil, 

Oat, and Sugarbeet. Unpublished study performed and sponsored by Bayer CropScience, 

Stillwell, Kansas, and Research Triangle Park, North Carolina, respectively. Report no.: 

200711. Study completed October 9, 2003. 

48549303 Minderhout, T.; Krueger, H.; Kendall, T. (2011) Flucarbazone: A 96-Hour Shell 

Deposition Test with the Eastern Oyster (Crassostrea virginica). Project Number: 

443A/145, 443A/145/OCR. Unpublished study prepared by Wildlife International, Ltd. 

58p.

48549304 Minderhout, T.; Kendall, T.; Krueger, H. (2011) Flucarbazone: A 96-Hour Flow-through 

Acute Toxicity Test with the Saltwater Mysid (Americamysis bahia). Project Number: 

443A/143, 443A/143/OCR. Unpublished study prepared by Wildlife International, Inc. 

58p.

48549305 Minderhout, T. ; Kendall, T. ; Krueger, H. (2011) Flucarbazone: A 96-Hour Flow-through 

Acute Toxicity Test with the Sheepshead Minnow (Cyprinodon variegatus). Project 

Number: 443A/144, 443A/144/OCR. Unpublished study prepared by Wildlife 

International, Ltd. 56p.

48549306 Hubbard, P.; Beavers, J. (2011) Flucarbazone: An Acute Oral Toxicity Study with the 

Zebra Finch (Poephila guttata). Project Number: 443/132, 443/132/OCR. Unpublished 

study prepared by Wildlife International, Ltd. 33p.
Page 35 of 39

Appendix A. SIP and STIR Results

SIP

The Screening Imbibition Program (SIP version 1.0; 6/15/2010) was used to calculate an 

upper bound estimate of exposure via drinking water using the solubility of flucarbazone 

sodium (44,000 mg/L). The most sensitive acute and chronic avian toxicity endpoints 

(bobwhite quail LD50 >2,000 mg/kg-bw and mallard duck NOAEC = 223 mg/kg-diet, 

respectively) and the most sensitive acute and chronic mammalian toxicity endpoints (rat, 

LD50 >5,000 mg/kg-bw and NOAEL = 287 mg/kg-bw/day, respectively) for flucarbazone 

sodium were used. The non-definitive acute endpoints result in conservative estimates of 

LC50s here. Drinking water exposure to flucarbazone sodium was determined to be a 

pathway of concern for both avian and mammalian species (LOC exceedances are 

expected). Results are presented in the tables below. 

SIP Avian Results for Flucarbazone Sodium

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 35,640 35,640

Adjusted toxicity value (mg/kg-bw) 1,440 11.1

Ratio of exposure to toxicity 24.7 3220

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for birds

Exposure through drinking 

water alone is a potential 

concern for birds

SIP Mammalian Results for Flucarbazone Sodium

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 7,570 7,570

Adjusted toxicity value (mg/kg-bw) 3,850 220

Ratio of exposure to acute toxicity 1.97 34.3

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for mammals

Exposure through drinking 

water alone is a potential 

concern for mammals

*Conclusions are 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.

STIR

The Screening Tool for Inhalation Risk (STIR version 1.0; 11/23/2010) was used to 

calculate upper bound estimates of flucarbazone sodium exposures via inhalation. The 

exposure pathways assessed include both droplet inhalation and vapor phase inhalation. 

Model inputs for flucarbazone sodium included molecular weight (418.28 g/mole), vapor 

pressure (<1.00x10-9 mmHg), highest application rate (0.025 lb ae/A), most sensitive 

acute avian toxicity endpoint (bobwhite quail, LD50 >2,000 mg/kg-bw), and most 

sensitive acute oral and inhalation mammalian toxicity endpoints (rat, LD50 >5,000

mg/kg-bw and 4 hr inhalation LC50 >5.13 mg/L, respectively). The non-definitive acute 

and inhalation endpoints and vapor pressure result in conservative estimates of LC50s 

here. Neither droplet nor vapor inhalation were determined to be potential pathways of 

concern for avian or mammalian species.
Page 36 of 39

STIR Avian (0.020 kg) Results for Flucarbazone Sodium

Maximum Vapor Concentration in Air at Saturation (mg/m3) 2.25E-05

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.83E-06

Adjusted Inhalation LD50 1.14E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 2.47E-07 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 2.40E-03

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 2.10E-04 Exposure not Likely Significant

STIR Mammalian (0.15 kg) Results for Flucarbazone Sodium

Maximum Vapor Concentration in Air at Saturation (mg/m3) 2.25E-05

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.56E-06

Adjusted Inhalation LD50 3.05E+02

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.16E-08 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 3.02E-03

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 9.88E-06 Exposure not Likely Significant
Page 37 of 39

Appendix B. ECOSAR Estimates for Flucarbazone Sodium and its Degradates

Chemical Taxa ECOSAR estimate 

(ppm ai)

ECOSAR class

Flucarbazone Sodium 

(parent)

Log Kow = -1.84

Water solubility = 44 

g/L

FW Fish acute 5190* Ester

FW Fish chronic 800

Daphnid acute 15500*

Daphnid chronic 28300*

SW fish acute 9730*

SW fish chronic 755

Mysid acute 51300*

Mysid chronic 3.93x109*

Green algae acute 960

Earthworm acute 64900*

FW Fish acute 64 Hydrazine

FW Fish chronic 9.7 (ACR)

Daphnid acute 660

Daphnid chronic 86 (ACR)

Green algae acute 12

Green algae chronic 2.4

FW Fish acute 32500* Amide

FW Fish chronic 7.3

Daphnid acute 1.72x105*

Daphnid chronic 1020

SW fish acute 27700*

Mysid acute 600

Green algae acute 490

Green algae chronic 110

MKH 6562 

Sulfonamide

Log Kow = 1.42 

(estimated)

Water solubility = 1.6 

g/ L (estimated)

FW fish acute 188 Amides

FW fish chronic 0.23

Daphnid acute 271

Daphnid chronic 10

SW fish acute 165

Mysid acute 8.7

Green algae acute 5.2

Green algae chronic 3.8

MKH6562 Sulfonic 

Acid

Log Kow = -0.118 

(estimated)

Water solubility = 33 

g/ L (estimated)

FW fish acute 1.59x105* Neutral OrganicsFW fish 14-day 1.50 x10 acid 5

*

FW fish chronic 12300

Daphnid acute 74400*

Daphnid chronic 4200

SW fish acute 1.98 x105*

SW fish chronic 5880

Mysid acute 6.17 x105*

Mysid chronic 99900*

Green algae acute 51500*

Green algae chronic 4170

Earthworm acute 6980

O-Desmethyl MKH 

6562 NMT

Log Kow = 2.83

FW fish acute 1.85 Hydrazines

FW fish chronic 0.080 (ACR)

Daphnid acute 6.83

Daphnid chronic 0.396 (ACR)

Green algae acute 0.538
Page 38 of 39

Water solubility = 15 

mg/L

Green algae chronic 0.183

FW fish acute 16.2* Carbonyl Ureas

FW fish chronic 0.115

Daphnid acute 1.93

Daphnid chronic 0.256

SW fish acute 14.1

SW fish chronic 0.898

Mysid acute 1.19

Green algae acute 0.029

Green algae chronic 0.008

NODT

Log Kow = -1.25

Water solubility = 53 

g/L

FW fish acute 1360 Esters

FW fish chronic 202

Daphnid acute 3990

Daphnid chronic 6930

SW fish acute 2520

SW fish chronic 201

Mysid acute 12200

Mysid chronic 6.71x108*

Green algae acute 2840

Green algae chronic 254

Earthworm acute 18700

FW fish acute 87100* Hydrazines

FW fish chronic 5980

Daphnid acute 24900

Daphnid chronic 1550

Green algae acute 22700

Green algae chronic 1060

NMT

Log Kow = -0.22

Water solubility = 7.8 

g/L

FW fish acute 6.90 Hydrazines

FW fish chronic 0.736 (ACR)

Daphnid acute 53.5

Daphnid chronic 5.58 (ACR)

Green algae acute 1.48

Green algae chronic 0.341

FW fish acute 243 Carbonyl Ureas

FW fish chronic 1.75

Daphnid acute 650

Daphnid chronic 7.45

SW fish acute 212

SW fish chronic 4.68

Mysid acute 4540

Green algae acute 0.009

Green algae chronic 0.002

MKH 6562 Sulfonylurea

Log Kow = 0.97

Water solubility = 2.3 

g/L

FW fish acute 1980 Neutral Organics

FW fish 14-day 1970

FW fish chronic 173

Daphnid acute 1020

Daphnid chronic 76.4

SW fish acute 2480*

SW fish chronic 143

Mysid acute 3710*

Mysid chronic 436

Green algae acute 794

Green algae chronic 109
Page 39 of 39

Earthworm acute 633

*Estimated toxicity value is greater than the limit of solubility

ACR – estimate calculated using acute-to-chronic ratios