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OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

March 15, 2016

PC Code: 035503

MEMORANDUM DP Barcode: 430247

SUBJECT: Registration Review –Preliminary Problem Formulation for Ecological Risk and 

Environmental Fate, Endangered Species, and Drinking Water Assessments for 

Fluometuron

TO: Linsey Walsh, Chemical Review Manager

Tracy Perry, Team Leader

Kelly Sherman, Branch Chief 

Risk Management and Implantation Branch 3 

Pesticide Re-evaluation Division (7508P) 

FROM: Ronald Parker, Ph.D., Senior Environmental Engineer

Christine Hartless, Ph.D., Wildlife Biologist

Environmental Risk Branch 2

Environmental Fate and Effects Division (7507P)

THROUGH: Melissa Panger, Ph.D., Senior Advisor

James Lin, Ph.D., Environmental Engineer

Mary Clock-Rust, Acting RAPL

Brian Anderson, Branch Chief

Environmental Risk Branch 2

Environmental Fate and Effects Division (7507P)

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

formulation (attached) for the ecological risk, environmental fate, endangered species, and 

drinking water assessments to be conducted as part of the registration review of fluometuron (PC 

Code 035503). 

The problem formulation draws on information from both open literature and studies submitted 

by the technical registrants in response to data requirements. This document is intended to 

provide an overview of what is currently known regarding the environmental fate and ecological 

effects associated with fluometuron and outlines uncertainties regarding attributes of the parent 

compound and its transformation products. It describes the preliminary ecological risk 

hypothesis and the processes that will be used during the completion of drinking water and 

ecological risk assessments in support of registration review. This document also recommends 

studies that should be included in a data call-in (DCI) to address uncertainties surrounding the 

environmental fate and potential ecological effects of fluometuron.
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Problem Formulation in Support of the

Registration Review of Fluometuron

Fluometuron (CAS 2164-17-2, PC Code: 035503)

N,N-dimethyl-N′-[3-(trifluoromethyl)phenyl]urea

March 15, 2016

Prepared by:

Ronald D. Parker, Ph.D., Senior Environmental Engineer

Christine Hartless, Ph.D., Wildlife 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:

Melissa Panger, Ph.D., Senior Advisor

James Lin, Ph.D., Environmental Engineer

Brian Anderson, Branch Chief

Environmental Risk Branch II
Page 3 of 43

Table of Contents

1. Executive Summary............................................................................................................... 4

2. Introduction............................................................................................................................ 5

3. Use Characterization.............................................................................................................. 5

4. Conclusions from Previous Risk Assessments...................................................................... 7

4.1 Ecological Risk Assessment ................................................................................................. 7

4.2 Drinking Water Exposure Assessments................................................................................ 7

4.3 Clean Water Act Programs ................................................................................................... 7

5. Environmental Fate and Transport......................................................................................... 8

5.1 Transformation Products..................................................................................................... 10

6. Receptors.............................................................................................................................. 13

7. Exposure Pathways of Concern ........................................................................................... 16

8. Analysis Plan ....................................................................................................................... 17

8.1 Stressors of Concern ........................................................................................................... 17

8.2 Measures of Exposure......................................................................................................... 17

8.3 Measures of Effect .............................................................................................................. 18

9. Endangered Species Assessments........................................................................................ 18

10. Endocrine Disruptor Screening Program............................................................................. 18

11. Preliminary Identification of Data Gaps.............................................................................. 18

11.1 Environmental Fate........................................................................................................... 18

11.2 Effects............................................................................................................................... 19

12. References............................................................................................................................ 24

12.1 Publically Available Literature ......................................................................................... 24

12.2 Submitted Environmental Fate Studies............................................................................. 24

12.3 Submitted Ecological Toxicity Studies............................................................................. 25

Appendix A. SIP Fluometuron Modeling Results........................................................................ 30

Appendix B. STIR Fluometuron Modeling Results ..................................................................... 30

Appendix C. Summary of Fluometuron Environmental Fate Data .............................................. 31

Appendix D. Summary of Fluometuron Ecotoxicity Data ........................................................... 35
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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 fluometuron (PC 035503, CAS 

2164-17-2). Fluometuron is a phenylurea herbicide that was first registered in 1974 for control of 

annual grass and annual broadleaf weeds in cotton and sugarcane, but currently the only Section 3 

use is for cotton. In addition to the cotton use, there is one Section 24(c) special local needs label 

in North Carolina for application to wildflowers for control of annual broadleaf weeds. Its mode 

of action is a combination of (1) inhibition of photosynthesis at the Photosystem II stage and (2) 

bleaching and inhibition of carotenoid biosynthesis (unknown target).

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 fluometuron. This document also identifies 

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

Data needs for ecological effects are:

• Avian acute oral toxicity test (850.2100), one passerine species

• Seedling Emergence and Seedling Growth (850.4100), 10 species conducted with an enduse product.

• Vegetative Vigor (850.4150), 10 species conducted with an end-use product.

• Toxicity data are not available with which to assess acute/chronic exposure to adult 

honey bees or to larval bees. These exposure routes remain significant uncertainties for 

the assessment of the impact of fluometuron on pollinators. Studies recommended at this 

time are:

o Acute oral toxicity to adult honey bees (OECD Guideline 213)

o Acute oral toxicity to larval honey bees (OECD Guideline 237)

o Chronic oral toxicity to adult honey bees (no guideline number)

o Chronic oral toxicity to larval honey bees (no guideline number)

o Field trial of residues in pollen and nectar (no guideline number)

o Semi-field testing for pollinator (OECD Guideline 75)

o Field testing for pollinator (850.3040)

These studies are recommended per the pollinator risk assessment guidance: 

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

honey bee residue on foliage study (850.3030) is not recommended at this time as the 

adult bee contact LD50 was greater than 11 μg a.i./bee.

Data needs for fate and exposure assessment are:

• Aerobic Aquatic Metabolism (835.4100) - There is no aerobic aquatic metabolism study 

available for fluometuron. This is important because fluometuron is stable to both 

hydrolysis and aqueous photolysis, the other two possible methods of degradation in 

surface water.

• Environmental Chemistry Methods in Soil and Water (850.6100) with an Independent 

Laboratory Validation. Independently validated analytical methods are important for 

quantifying environmental residues in offsite soil and water following application.
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Label clarification recommendations are:

• End-use product labels should be modified to include current recommended drift 

reduction language. This includes, but is not limited to, droplet sizes, wind speed, release 

height, boom height, and boom length. 

2. Introduction

Fluometuron ([1,1-dimethyl-3-(alpha, alpha, alpha-trifluoro-mtolyl) urea] is a substituted urea 

herbicide. Its mode of action is a combination of (1) inhibition of photosynthesis at the 

Photosystem II stage and (2) bleaching and inhibition of carotenoid biosynthesis (unknown 

target).

Fluometuron is registered to control large seeded, broadleaf weeds, and annual grasses in cotton. 

Fluometuron is effective in the control of annual grass weeds such as barnyardgrass, crabgrass, 

crowfootgrass, fall panicum, foxtail, goosegrass, ryegrass, and signalgrass. It also controls 

annual broadleaf weeds such as buttonweed, cocklebur, Florida pusley, groundcherry,

jimsonweed, lambsquarters, morningglory, pigweed, prickly sida, purslane, ragweed, sesbania,

sicklepod, smartweed, and tumbleweed.

EFED evaluated the most recent ecological risk assessments and drinking water assessments for 

fluometuron in association with the updated toxicity, exposure, and usage information to 

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

review. In addition, EFED considered the latest Agency science policies and risk assessment 

methodologies for this evaluation. 

3. Use Characterization

The chemical profile produced by Biological and Economic Analysis Division (BEAD), located 

in this docket, lists the use patterns of maximum application rates for the current uses of 

fluometuron. BEAD’s chemical profile includes both a summary of labeled uses and rates as 

well as a summary of available reported usage data. EFED will use application scenarios that 

result in maximum exposure scenarios for a given use for the risk assessment. 

There are currently two registered technical products (USEPA Reg. No.’s 011603-31 and 

082633-19). Currently registered maximum use rates for cotton are provided in Table 1. The use 

profile will be re-evaluated prior to conduct of the risk assessment. The commercial end-use

products for application to cotton include liquid flowables/ emulsifiable concentrates. These 

labels contain soil-type restrictions (e.g., application is not permitted on some soil types and 

maximum single application rates is reduced in some soil types), which will be further evaluated 

at the time of risk assessment. In 2012, EPA required additional restrictions on fluometuron use 

near drinking water wells and on vulnerable soils (e.g., karst topographical features) and 

removed the county-specific prohibitions in Louisiana and Georgia. Some labels have not yet 

been updated to include this recent language and the Agency is currently working with 

registrants to either voluntarily cancel or amend these labels. The timing of applications varies 

among preplant, pre-emergence, and post-emergence crop stages. 
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Table 1. Maximum Use Information for Fluometuron on Cotton

Crop (Application type) Max lb 

ai/A/appl.

Max No. of Applications

per Year

Min Intervals 

(days)

Max lb 

ai/A/yr

Cotton (aerial or ground) 2 2 20 3

In addition to the cotton use, there is one Section 24(c) special local needs label (EPA SLN No. 

NC-120002) for application to wildflowers for control of annual broadleaf weeds. The maximum 

annual and single application rate is 1.0 lb ai/acre. Use of this product is restricted to members of 

the North Carolina Department of Transportation.

A map of estimated annual use for fluometuron during 2012 is presented in Figure 1. The USGS 

Pesticide Usage data extrapolates pesticide usage from survey data to areas where pesticide 

usage information is not available. USGS intends these data to be used for broad-scale 

assessments, such as at the national or regional level. Therefore, EPA’s assessments will use 

these data for qualitative purposes only, in the form of maps, to provide a geographic footprint of 

a pesticide’s use. These data are not suitable for sub-state quantitative analyses. In addition to 

the usage map, Figure 1 contains a chart depicting estimated total annual usage from 1992 to 

2012.

Figure 1. Estimated Agricultural Use for Fluometron

(https://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2012&map=FLUOMETURON&hilo=H)
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4. Conclusions from Previous Risk Assessments

4.1 Ecological Risk Assessment

The most recent, comprehensive assessment conducted for fluometuron is the RED (USEPA, 

2005); major ecological conclusions are listed in Table 2. EFED has not conducted any listed 

species assessments for fluometuron. 

Table 2. Summary of Ecological Risk Concerns Identified for Fluometuron in the 2005 RED 

Assessment

Birds Mammals Terr. Plants Terr. Inverts Fish BCF

Yesa Yes Yes No Yesa No

Aquatic 

Inverts Aquatic Plants Groundwater Contamination Persistence Degrates of Concern

Yesa Yes Yes Yes CGA-41686

a No reproduction data were available to allow for a chronic risk assessment; risk was presumed 

Yes = at least one LOC has been exceeded in previous assessments; No = LOCs have not been exceeded in 

previous assessments

4.2 Drinking Water Exposure Assessments

The most recent drinking water assessment presented EDWCs (Estimated Drinking Water 

Concentrations) based on cotton and considered both parent fluometuron and the major 

degradate, CGA-41686 (desmethyl-fluometuron). For details, see also the following document:

Refined Fluometuron Percent Crop Treated and Percentage of National Soybean, Corn, and

Wheat Crops Rotated with Fluometuron-Treated Cotton dated August 9, 2005, and Addendum to

Refined Fluometuron Percent Crop Treated, dated September 21, 2005.

EFED will update the drinking water assessment based on the most current methods, data, and 

models. 

4.3 Clean Water Act Programs

Fluometuron 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 fluometuron. Aquatic life benchmarks have been established for 

fluometuron and are available at http://www.epa.gov/pesticide-science-and-assessing-pesticiderisks/aquatic-life-benchmarks-pesticide-registration . Any data submitted or otherwise located as 

part of the registration review process may be used to update aquatic life benchmarks if 

applicable.
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5. Environmental Fate and Transport

Tables 3 and 4 summarize the physical properties and environmental fate data of fluometuron 

and its degradates.

Table 3. Chemical Properties and Environmental Fate Parameters of Fluometuron

Parameter Value Description Source

Selected Physical/Chemical Parameters

Vapor pressure (20°C) 5.0 x 10-7 mm Hg Low potential for 

volatilization MRID 00262064

Aqueous solubility (20°C) 90 mg/L Soluble PPDB

Henry’s Law Constant (20°C) 1.45 x 10-10 atmm3

/mole

Low potential for 

volatilization PPDB

Log octanol-to-water partition coefficient 

(log KOW) 3.2 at 20 o

C Moderately hydrophilic MRID 40600608

Table 4. Summary of Environmental Fate Properties of Fluometuron and Major

Degradates

Study Half-lives, Days Degradates MRID Study Status

Fluometuron

Hydrolysis Stable at pH 4, 7 , and 9 @ 

50oC

none 40864401, 

40930601

Acceptable

Direct Aqueous 

Photolysis

Stable none 41065101 Acceptable

Soil Photolysis Stable none 40930602 Acceptable

Aerobic Soil 

Metabolism

181 days (sandy loam) CGA-41686 (parent with 

1 methyl group removed; 

35%, 365 days)

CO2 (maximum 13.3%, 

365 days)

42998702 Acceptable

Anaerobic soil 

Metabolism

378 days (total system) CGA-41686 (parent with 

1 methyl group removed; 

maximum 21%, end of 

study, total system)

42998703 Acceptable

Anaerobic 

Aquatic 

Metabolism

177 days (total system) CGA-41686 (parent with 

1 methyl group removed; 

maximum 7.9%, end of 

study, total system)

43158901 Acceptable

Kd-ads / Kd-des 

(mL/g)

Koc- ads / Koc-des 

(mL/g)

0.08 / 2.93 (sand), 

0.15 / 1.48 (sandy loam), 

0.25 / 4.93 (Sandy clay loam), 

and 1.13 / 4.25 (clay) 

35 /1277 (sand), 

57 /561 (sandy loam), 

54 / 1075 (Sandy clay loam), 

and 80 /300 (clay) 

Not applicable 42643601 Acceptable

Field 

Dissipation

Study

103 days (Georgia Lucy 

Loamy sand)

40459401

40459402

Acceptable
Page 9 of 43

Table 4. Summary of Environmental Fate Properties of Fluometuron and Major

Degradates

Study Half-lives, Days Degradates MRID Study Status

97 days (California Veritas 

Fine sandy loam)

CGA-41686 (desmethyl-fluometuron)

Kd-ads / Kd-des 

(mL/g)

Koc- ads / Koc-des 

(mL/g)

0.16 /3.90 (sand), 0.33 /4.55 

(sandy loam), 0.57 / 6.44 

(Sandy clay loam), and 2.0 

/6.25 (clay) 

69 /1700 (sand), 125 /1719 

(sandy loam), 123 / 1404 

(Sandy clay loam), and 141 

/441 (clay) 

Not applicable 42643604 Acceptable

Fluometuron and its metabolites are both mobile and persistent in the environment. The primary 

route of degradation of fluometuron and its main degradate CGA-41686 (desmethylfluometuron) is microbial metabolism. However, since fluometuron and its degradates are not 

volatile and these degradative processes are not rapid, these compounds will be available for 

leaching to ground water and runoff to surface water in many use conditions. Once in ground 

water or surface water, fluometuron is expected to persist due to its stability to hydrolysis and 

photolysis. 

Parent fluometuron is very stable to abiotic hydrolysis and photolysis in water and on soil. It is 

also stable to aerobic soil metabolism, anaerobic soil metabolism, and anaerobic aquatic 

metabolism, with t1/2's of 181, 378, and 177 days, respectively. CGA-41686 (desmethylfluometuron) is the only major degradate identified in acceptable studies (Table 4). The other 

degradates, CGA-41685 (parent with both methyl groups removed), and CGA-72903 

(decarboxylated, demethylated CGA-41685) were detected in only small amounts (<10% of the 

applied radioactivity) in all metabolism studies.

Adsorption studies using parent compound and the three metabolites showed that fluometuron 

residues are very mobile to mobile in the environment. In the case of CGA-72903, assumed 

values had to be used to calculate desorption values, which were at best questionable. The 

Freundlich Kads values for parent fluometuron were 0.08-1.13, with corresponding Kocads values 

of 35-80 in soils with 0.23-1.4 % OC. The Freundlich Kads values for the metabolites CGA41686, CGA-41685, and CGA-72903 consistently ranged from low values of 0.16-0.23 to higher 

values of 1.89-2.33, with corresponding Kocads 66-164. Adsorption generally increased with 

increasing soil organic carbon and clay content.

Data previously reviewed indicated that fluometuron (1) is stable to hydrolysis; (2) is mobile in 

(European) sand, sandy loam, loam and clay soils with Kd's 0.15 to 2.8 (leaching appeared to 

correlate with percent of soil organic matter present in soil.); and (3) has field dissipation halflife of 97 to 193 days in (CA) fine sandy loam soil and (GA) loamy sand soil (vertical movement 

of residues appeared to correlate with rainfall).
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5.1 Transformation Products

Fluometuron and its metabolites are both mobile and persistent in the environment. The primary 

route of degradation of fluometuron and its main degradate, CGA-41686, is microbial 

metabolism. However, since fluometuron and its degradates are not volatile, and these 

degradative processes are not rapid, these compounds will be available for leaching to 

groundwater and runoff to surface water under many use conditions. Once in groundwater or 

surface water, fluometuron is expected to persist due to its stability to hydrolysis and photolysis.

Fluometuron degradates are detailed in Table 5 below.
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Table 5. Fluometuron and Its Environmental Transformation Products

Code Name/ 

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

Final %AR 

(study length)

PARENT

Fluometuron N,N-dimethyl-N′-[3-

(trifluoromethyl)phenyl]urea

CAS No.: 2164-17-2

Formula: C10H11F3N2O

MW: 232.2 g/mol

 

TRANSFORMATION PRODUCTS

Degradate

CGA-41686

(3-(3-trifluoromethylphenyl)-1-

methylurea

(Fluometuron-Desmethyl)

CAS No.: 3032-40-4

Formula: C9H9F3N2O

MW: 218.18 g/mol

Anaerobic aquatic

(Pond system) 43158901 7.9% (end of study)

7.9% (end of 

study)

Aerobic soil 42998702 35% (365 days) 35% (365 days)

Anaerobic soil 42998703 21% (end of 

study)

21% (end of 

study)

Terrestrial Field Dissipation 40459401

40459402

Degradate

CGA-41685

1-(α,α,α-trifluoro-m-tolyl)urea

Anaerobic aquatic

(Pond system) 43158901 6.2% (6 months)

Aerobic soil 42998702 3.3% (365 days) 3.3 % (365 days)

Anaerobic soil 42998703

< 0.2% (% (all 

sampling 

intervals)

< 0.2% (all 

sampling 

intervals))

Terrestrial Field Dissipation 40459401

40459402

Degradate

CGA-72903 Trifluoromethyl aniline (TFMA)

Anaerobic aquatic

(Pond system) 43158901

(1.7% (all 

sampling 

intervals)

(1.7% (all 

sampling 

intervals)

Aerobic soil 42998702 1.0% (100 days)

Anaerobic soil 42998703

< 0.2% (all 

sampling 

intervals)

< 0.2% (all 

sampling 

intervals)
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Table 5. Fluometuron and Its Environmental Transformation Products

Code Name/ 

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

Final %AR 

(study length)

Terrestrial Field Dissipation 40459401

40459402

CO2 Carbon dioxide O = C = O Aerobic Soil 42998702 13.3% (365 days) 13.3% (365 days)
Page 13 of 43

6. Receptors

Tables 6 and 7 and Appendix D provide a summary of the taxonomic groups tested to 

characterize the potential acute and chronic ecological effects of fluometuron. In addition, the 

tables provide a preliminary overview of the potential acute toxicity of fluometuron by providing 

the acute toxicity classifications. No ecotoxicity data for fluometuron degradates were 

identified. 

Fluometuron is classified as moderately toxic to practically non-toxic to freshwater fish and 

highly toxic to moderately toxic to freshwater invertebrates on an acute exposure basis (Table 

6). In addition, fluometuron is classified as slightly toxic to estuarine/marine fish and 

moderately to slightly toxic to estuarine/marine aquatic invertebrates on an acute exposure basis. 

In the fathead minnow chronic study, the NOAEC was identified at 3.1 mg ai/L while the 

LOAEC (based on reductions in length and dry weight) was identified at 9.1 mg ai/L. No data 

were submitted to evaluate chronic estuarine/marine fish toxicity; however, an Acute-to-Chronic 

Ratio (ACR) was calculated using the fathead minnow acute and chronic data. This ratio was 

applied to the sheepshead minnow acute LC50, resulting in a NOAECACR = 1.8 mg ai/L. In the 

daphnid chronic studies, the NOAEC was identified at 1.73 and 1.32 mg ai/L, respectively. 

However, since the acute midge data were more sensitive than the daphnid data, an ACR was 

also calculated to estimate the chronic NOAECACR = 0.038 for freshwater invertebrates. All 

NOAECACR calculations are provided in Table 6.

Duckweed (Lemna gibba) was sensitive to fluometuron with an IC50 of 0.022 mg a.i./L. Nonvascular aquatic plant sensitivity ranged with IC50’s from 0.05 to 0.5 mg a.i./L. EPA does not 

currently classify toxicity to aquatic plants.

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

Taxonomic 

Group

Study 

Type Tested Species Toxicity Values

(mg a.i./L)

Acute Toxicity 

Classification

Source

(Study Classification)

Comments

Freshwater 

fish1

Acute

Rainbow trout 

(Oncorhynchus

mykiss)

LC50 = 2.96 Moderately toxic

40098001

(Supplemental, raw data 

not found)

Chronic

Fathead minnow 

(Pimephales 

promelas)

NOAEC = 3.1 

LOAEC = 9.1 --

46565702 (Acceptable) 

Reductions in growth 

(length and dry weight)

Freshwater 

invertebrates

Acute

Midge

(Chironomus 

plumosus)

LC50 = 0.22 Highly toxic

40098001

Supplemental (96-hr 

study, not recommended 

species, 4th instar tested)

Chronic Acute-to-Chronic 

Ratio (ACR)

NOAECACR = 

0.038 --

Utilized data from acute 

and chronic daphnid

studies to calculate the 

ACR. Applied the ACR 

to the acute midge 

LC50.

2
Page 14 of 43

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

Taxonomic 

Group

Study 

Type Tested Species Toxicity Values

(mg a.i./L)

Acute Toxicity 

Classification

Source

(Study Classification)

Comments

Estuarine/ 

marine fish

Acute

Sheepshead 

Minnow 

(Cyprinodon 

variegatus)

LC50 = 38 Slightly toxic

42498004 

(Supplemental, 

Undissolved test 

material at all 

concentrations, 

analytical samples not 

centrifuged or filtered)

Chronic Acute-to-Chronic 

Ratio (ACR)

NOAECACR =

1.8 --

Utilized data from acute 

and chronic fathead 

minnow studies to 

calculate the ACR. 

Applied the ACR to the 

acute sheepshead 

minnow LC50.

3

Estuarine/

marine 

invertebrates

Acute, 

crustacean

Mysid shrimp

(Americamysis 

bahia)

LC50 = 3.8 Moderately toxic 42568501 (Acceptable)

Acute, 

mollusk

Eastern oyster, 

Crassostrea 

virginica

IC50 = 6.53 Moderately toxic 43848101 (Acceptable)

Chronic Mysid shrimp NOAEC = 1.32 

LOAEC = 2.68 --

48080701 (Acceptable)

Most sensitive 

endpoints: F0 Day 13 

survival (before pairing) 

and F0 male body 

lengths on Day 28

Aquatic 

plants and 

algae

Vascular Duckweed

(Lemna gibba)

IC50 = 0.22

NOAEC = 0.225 --

43421601 

(supplemental, fewer

than recommended 

initial number of fronds)

Nonvascular

Green Algae 

(Selenastrum 

capricornutum)

IC50 = 0.030

NOAEC < 0.007

IC05 = 0.0016

--

42498007

(supplemental, no 

definitive NOAEC)

1 Freshwater fish may be surrogates for aquatic-phase amphibians. 2 NOAECACR = 0.22 mg a.i./L * (1.73 mg a.i./L / 9.9 mg a.i./L) = 0.038 mg a.i./L (Endpoints obtained from MRIDs 

40098001, 46565701, 47978401, and 0024180). 3 NOAECACR = 38 mg a.i./L * (3.1 mg a.i./L / 65 mg a.i./L) = 1.8 mg a.i./L (Endpoints obtained from MRIDs 

42498004, 46565702, and 607401)

Fluometuron is practically non-toxic to birds on an acute oral basis and slightly toxic to birds on 

a dietary basis, and it is slightly toxic to mammals on an acute oral exposure basis (Table 7). 

Mammalian acute inhalation toxicity is low. For birds, number of eggs laid and hatchling 

weights were reduced at 102 mg a.i./kg-diet in the chronic study using mallards (NOAEC = 60.4 

mg a.i./kg-diet). For mammals, no reproductive or growth effects were identified in the 2-

generation rat reproduction study. The most sensitive developmental toxicity study was 

conducted with rabbits, resulting in a NOAEL = 10 mg a.i./kg-bw and LOAEL = 100 mg a.i./kgbw based on increased incidence of stool variations and abortions, reduced food consumption, 

decreased maternal body weight gain. The equivalent NOAEC and LOAEC are 189 and 1890 
Page 15 of 43

mg a.i./kg-diet, respectively (calculation approach provided in Table 7). Acute contact toxicity 

to bees was low. 

Terrestrial plants were sensitive to fluometuron at both the seedling emergence and vegetative 

vigor stages of growth. EFED recommends requesting new terrestrial plant studies conducted 

with an end-use product to reduce uncertainty in estimating the effects of end-use product drift to 

non-target plants. EPA does not currently classify toxicity to terrestrial plants.

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

Fluometuron

Taxonomic 

Group

Study 

Type

Tested Species Toxicity Value Acute Toxicity 

Classification 

Source

(Study Classification)

Comments

Birds1

Acute

Mallard duck 

(Anas 

platyrhynchos)

LD50 = 2974

mg ai/kg-bw 

Practically 

non-toxic 00019221 (Acceptable)

Sub-acute 

dietary

Ring-necked 

pheasant 

(Phasianus 

colchicus)

LC50 = 3150

mg ai/kg-diet Slightly toxic

00019222 (Acceptable)

Sublethal toxic effects 

included huddling, 

lethargy, and reduced 

weight gain.

Chronic Mallard duck 

NOAEC= 60.4 

mg ai/kg diet

LOAEC = 102 

mg ai/kg diet

--

47896201 (Acceptable)

At 102 mg a.i./kg-diet 

(highest tested 

concentration), reduced 

number of eggs laid and 

reduced hatchling weight.

Mammals

Acute Oral Laboratory rat 

(Rattus norvegicus)

LD50 between 

1000 and 1500 

mg a.i./kg

Slightly toxic 41216802 (Acceptable)

Females: 0% mortality at 

1000 mg a.i./kg-bw and 

100% mortality at 1500 

mg a.i./kg-bw and above.

Males LD50 = 3800 mg 

a.i./kg-bwt. 

Acute 

Inhalation Laboratory rat LC50 > 0.6 mg a.i./L

HED Tox 

Category III 40409304 (Acceptable)

Chronic Laboratory rabbit

NOAEL= 10

mg/kg-bw

(NOAEC = 189 

mg a.i./kg-diet)

2

LOAEL= 100

mg/kg-bw

(LOAEC = 1890 

mg a.i./kg-diet)

--

00163774

00147554

42397602

(acceptable) LOAEL 

based on increased 

incidence of stool 

variations and 

abortions, reduced food 

consumption, decreased 

maternal body wt. gain

Insects Acute 

contact

Honey bee 

(Apis mellifera L.)

LC50 > 11 μg 

a.i./bee

Practically 

non-toxic

00006653 and 00028772

Acceptable
Page 16 of 43

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

Fluometuron

Taxonomic 

Group

Study 

Type

Tested Species Toxicity Value Acute Toxicity 

Classification 

Source

(Study Classification)

Comments

Terrestrial 

plants

Seedling 

Emergence

Dicot – Lettuce 

(Lactuca sativa)

IC25 = 0.006 lbs 

ai/acre

NOAEC = 

0.00021 lbs 

ai/acre 

-- 42718802 (Acceptable) 

Technical (97.2%) was 

tested. Dry weight most 

Monocot – Corn sensitive parameter.

(Zea mays)

IC25 = 0.026 lbs 

ai/acre

NOAEC = 

0.0019 lbs ai/acre

--

Vegetative 

vigor

Dicot – Cucumber 

(Cucumis sativus)

IC25 = 0.0008 lb 

ai/acre

NOAEC = 

0.0021 lbs ai/acre 

-- 42718803 (Acceptable) 

Technical (97.2%) was 

tested. Dry weight most 

sensitive parameter. Monocot – Oat 

(Avena sativa)

IC25 = 0.035 lbs 

ae/acre

NOAEC = 0.019 

lbs ai/acre 

--

1 Birds represent surrogates for terrestrial-phase amphibians and reptiles. 2 NOAEC and LOAEC calculated as follows: Female rabbits in study ranged in weight from 3.045 to 4.491 kg; 

average of minimum and maximum weights was used to estimate food consumption (3.768 kg). Daily food 

consumption was estimated using the following allometric equation in USEPA (1993):

 kg-diet/day = 0.067 * (rabbit wt, kg) 0.822 = 0.199 kg-diet/day

Daily consumption of fluometuron at NOAEL: 

 NOAEL * bw = 10 mg ai./kg-bw/day * 3.768 kg = 37.68 mg a.i./day

NOAEC = daily consumption of fluometuron at NOAEL / daily food consumption

 = 37.67 mg a.i./day / 0.199 kg-diet/day = 189 mg a.i./kg-diet

A review of the EIIS database for ecological incidents involving fluometuron was completed on 

January 12, 2016. There were two fluometuron incidents in the database, both involving cotton.

The first incident occurred in Martin County, NC, on 7/15/98 and involved 45 adversely affected 

acres of cotton out of a total acreage of 80. The second incident occurred on 10/14/98 in

Northampton County, NC, and involved a registered use of liquid formulation fluometuron. 

Three out of 26 acres were adversely affected. No additional incidents were identified in the 

Aggregate Incident Database component of the Office of Pesticide Programs Incident Database 

System (OPP IDS) search completed in January 12, 2016.

The Avian Incident Monitoring System (AIMS)1 database will be examined at the time of 

registration review for fluometuron. 

7. Exposure Pathways of Concern

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

spray drift, leaching to ground water, atmospheric deposition, and runoff represent potential 

transport mechanisms to aquatic and terrestrial organisms. Drinking water and inhalation 

exposure pathways for birds and mammals were evaluated using the SIP (Screening Imbibition 

 1 http://www.abcbirds.org/abcprograms/policy/pesticides/aims/aims/index.cfm
Page 17 of 43

Program) and STIR (Screening Tool for Inhalation Risk) screening methods (Appendices 1 and

2). Drinking water alone was not identified as a potential acute concern for birds and mammals; 

however, it was identified as a potential chronic concern for both birds and mammals. Inhalation 

was found to be an exposure pathway of low concern for both birds and mammals. SIP and STIR 

are described in detail at: http://www.epa.gov/pesticide-science-and-assessing-pesticiderisks/models-pesticide-risk-assessment#terrestrial.

8. Analysis Plan

8.1 Stressors of Concern

Fluometuron and its major degradate, desmethyl-fluometuron, are the stressors of concern for 

both the ecological and drinking water risk assessments for registration review. For the 

ecological risk assessment, fluometuron and desmethyl-fluometuron will be assumed to have 

equal toxicity as the chemicals have very similar structures (desmethyl-fluometuron has the same 

structure as fluometuron with the exception of one less methyl group). 

8.2 Measures of Exposure 

8.2.1 Modeling of Exposure 

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

terrestrial organisms as described at http://www.epa.gov/pesticide-science-and-assessingpesticide-risks/models-pesticide-risk-assessment. Both acute and chronic exposure will be 

assessed with modeling inputs based on fluometuron and its major metabolite, desmethylfluometuron, environmental fate and transport properties. The Pesticide in Water Calculator 

(PWC), previously known as the Surface Water Concentration Calculator (SWCC), is currently 

the model typically used to estimate aquatic exposure. T-REX and TerrPlant are currently 

models typically used to estimate terrestrial exposure.

Screening level calculations suggested that drinking water pathway may be significant chronic 

exposures for terrestrial organisms. This exposure pathway may be further considered at the time 

of the risk assessment (Appendix B).

8.2.2 Available Monitoring Data

EFED currently has monitoring data on the concentrations of fluometuron in surface water. The 

US Geological Survey (USGS) National Water Quality Assessment Program (NAWQA)2

analyzed pesticide occurrence and concentrations for major streams, showed fluometuron with a 

maximum concentration of 37.8 μg/L. Even though, the surface water monitoring data collected 

by NAWQA are from sites considered typical for use areas, the frequency of sampling and the 

length of sampling period were not sufficient to represent the temporal and spatial requirements 

for regulatory purposes.

 2 http://waterqualitydata.us/portal/
Page 18 of 43

The US Geological Survey (USGS) National Water Quality Assessment Program (NAWQA)

also analyzed pesticide occurrence and concentrations for major aquifers and shallow ground 

water in agricultural areas showed fluometuron with a maximum concentration of 4.7 μg/L. Even 

though the groundwater monitoring data collected by NAWQA are from sites considered typical 

for use areas, the frequency of sampling and the length of sampling period were not sufficient to 

represent the temporal and spatial requirements for regulatory purposes.

EFED has targeted monitoring data on the concentrations of fluometuron in groundwater. 

According to the USEPA Pesticides in Ground Water Database (USEPA 1992), the 

concentrations of fluometuron in a total of 530 well samples collected in AR, CA, FL, GA, LA, 

MO, and MS, ranged from 0.8 to 5.00 μg/L.

8.3 Measures of Effect 

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

quotients. Any toxicity data identified for the major degradate, desmethyl fluometuron, may also

be used. Additional information submitted by the registrant or found in the 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, 2007), 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.

9. Endangered Species Assessments

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

Agency will evaluate risks to federally 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.

10. Endocrine Disruptor Screening Program

Fluometuron was not included in the first group or the second group of chemicals issued an order 

to conduct Tier 1 EDSP testing. For additional information the EDSP program, visit 

http://www2.epa.gov/endocrine-disruption . 

11. Preliminary Identification of Data Gaps 

11.1 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 in order 

to support risk assessment. 
Page 19 of 43

Table 8. Summary of Submitted Environmental Fate Data for Fluometuron

OCSPP 

Guideline Data Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are Additional 

Data Needed to

Conduct Risk 

Assessment?

835.2120 Hydrolysis 40864401 and 

40930601

Acceptable No

835.2240 Aqueous photolysis 41065101 Acceptable No

835.2410 Soil photolysis 40930602 Acceptable No

835.4100 Aerobic soil metabolism 42998702 Acceptable No

835.4200 Anaerobic soil metabolism 42998703 Acceptable No

835.4300 Aerobic aquatic metabolism No available data NA Yes

835.4400 Anaerobic aquatic metabolism 43158901 Acceptable No

835.1230

835.1240

Adsorption/ desorption and 

leaching 42643601 Acceptable No

835.6100 Terrestrial field dissipation 40459401

40459402 Acceptable No

850.1730 Fish bioconcentration 42017304 Acceptable No

850.6100 Analytical method in soil No available data NA Yes Analytical method in water No available data NA

11.2 Effects

Tables 9 and 10 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. 

Although fluometuron is categorized as practically non-toxic to adult honeybees on an acute

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 honeybees is needed to fully characterize the risk associated with fluometuron 

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). It is unknown if 

fluometron 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. Data are needed to help better 

characterize some uncertainties regarding potential effects to bees. 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 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 fluometuron’s effects at the wholecolony level (http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance).

These additional pollinator protection studies are listed in Table 9.
Page 20 of 43

Table 9. Available ecological effects data for terrestrial organisms exposed to fluometuron

and remaining data gaps. 

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment?

Current Additional Data Need

850.2100 Avian oral 

toxicity

160000 Supplemental Yes Data are required for avian acute 

oral with passerine 00019221 Acceptable

850.2200 Avian dietary 

toxicity 

42498001 Acceptable No --

42597401 Acceptable

00019222 Supplemental 

(Japanese quail)

00019222 Supplemental 

(Mallard)

00019222

Acceptable 

(ring-necked 

pheasant)

850.2300 Avian 

reproduction

47984401 Supplemental No --

46565703 Invalid

47896201 Acceptable

NonguidelineAvian inhalation (None) -- No A data gap was not identified as 

inhalation concerns were not raised 

based on the STIR screen.

850.3020 Honey bee acute 

contact toxicity

00006653 and 

00028772

Acceptable No --

850.3030 Honey bee residue 

on foliage

(None) -- No Data are not requested at this time 

as the adult bee contact LD50 was 

greater than 11 μg a.i./bee.

Nonguideline, 

OECD TG 

213

Acute oral toxicity 

to adult honey 

bees

(None) -- Yes Recommend that PRD request data 

per: 

http://www2.epa.gov/pollinatorprotection/pollinator-riskassessment-guidance

Nonguideline, 

OECD TG 

237

Acute oral toxicity 

to larval honey 

bees

(None) -- Yes Recommend that PRD request data 

per: 

http://www2.epa.gov/pollinatorprotection/pollinator-riskassessment-guidance

NonguidelineChronic oral 

toxicity to adult 

honey bees

(None) -- Yes Recommend that PRD request data 

per: 

http://www2.epa.gov/pollinatorprotection/pollinator-riskassessment-guidance

NonguidelineChronic oral 

toxicity to larval 

honey bees

(None) -- Yes Recommend that PRD request data 

per: 

http://www2.epa.gov/pollinatorprotection/pollinator-riskassessment-guidance
Page 21 of 43

Table 9. Available ecological effects data for terrestrial organisms exposed to fluometuron

and remaining data gaps. 

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment?

Current Additional Data Need

NonguidelineField trial of 

residues in pollen 

and nectar

(None) -- Yes Recommend that PRD request data 

per: 

http://www2.epa.gov/pollinatorprotection/pollinator-riskassessment-guidance

Nonguideline, 

OECD 

Guidance 75

Semi-field testing 

for pollinator

(None) -- Yes Recommend that PRD request data 

per: 

http://www2.epa.gov/pollinatorprotection/pollinator-riskassessment-guidance

850.3040 Field testing for 

pollinator

(None) -- Yes Recommend that PRD request data 

per: 

http://www2.epa.gov/pollinatorprotection/pollinator-riskassessment-guidance

850.3100 Earthworm 

Subchronic 

Toxicity Test 

(None) -- No Data have not been submitted to 

fulfill this guideline. A data gap 

was not identified as these data are 

not necessary for risk assessment at 

this time.

850.4100 Seedling 

Emergence and 

Seedling Growth

42718802 Supplemental Yes Submitted study utilized technical 

grade fluometuron, not an end-use 

product. Given the likelihood of 

increased toxicity when exposed to 

the formulated product, and 

exposure to the formulated product 

is likely given drift during 

application, additional data are 

recommended for 10 species

utilizing an end-use product. 

850.4150 Vegetative Vigor 42718802 Supplemental Yes Submitted study utilized technical 

grade fluometuron, not an end-use 

product. Given the likelihood of 

increased toxicity when exposed to 

the formulated product, and 

exposure to the formulated product 

is likely given drift during 

application, additional data are 

recommended for 10 species

utilizing an end-use product.
Page 22 of 43

Table 10. Available ecological effects data for aquatic organisms exposed to fluometuron

and remaining data gaps. 

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed to 

conduct risk 

assessment?

Current Additional Data Need

850.1010 Freshwater 

invertebrate 

acute toxicity

0024180 Acceptable No --

40098001 Acceptable

40098001 Supplemental

40098001 Supplemental

40098001 Supplemental

850.1025

850.1035

850.1045

850.1055 

Saltwater 

invertebrate 

acute toxicity 

42568501 Acceptable No --

42498006 Acceptable

42498005 Supplemental

43848101 Acceptable

42560101 Invalid

850.1075 Freshwater fish 

acute toxicity 

161088 Supplemental No --

42498002 Acceptable

40098001 Acceptable

40098001 Supplemental

42498003 Acceptable

42505001 Acceptable

40098001 Supplemental

40098001 Acceptable

40098001 Supplemental

47607401 Supplemental

40098001 Invalid

40098001 Acceptable

40098001 Supplemental

850.1075 Saltwater fish 

acute toxicity 

42498004 Supplemental No --

42505002 Acceptable

850.1300 Freshwater 

invertebrate 

life cycle 

46565701 and 

47978401

Acceptable No --

850.1350 Saltwater 

invertebrates 

life cycle 

48080701 Acceptable No --

850.1400 Freshwater fish 

early-life stage

46565702 Acceptable No --
Page 23 of 43

Table 10. Available ecological effects data for aquatic organisms exposed to fluometuron

and remaining data gaps. 

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed to 

conduct risk 

assessment?

Current Additional Data Need

850.1400 Saltwater fish 

early-life stage 

(None) -- No Data have not been submitted to 

fulfill this guideline. A data gap 

was not identified as these data are 

not necessary for risk assessment 

at this time as utilized data from 

acute and chronic fathead minnow 

studies to calculate the ACR and 

applied the ACR to the acute 

sheepshead minnow LC50.

850.1500 Fish life cycle (None) -- No Data have not been submitted to 

fulfill this guideline. A data gap 

was not identified as these data are 

not necessary for risk assessment 

at this time.

850.4400 Aquatic plant 

Toxicity Test 

using Lemna spp.

42564102 Supplemental No --

43421601 Supplemental

850.4500 Algal toxicity 43025601 Supplemental No --

42498007 Supplemental

42564101 Supplemental

42568502 Acceptable

850.4550 Cyanobacteria 42568503 Supplemental No --

43421602 Acceptable
Page 24 of 43

12. References

12.1 Publically Available Literature

USEPA. 1992. Pesticides in Ground Water Database- A compilation of Monitoring Studies: 1971 - 1991. Office of 

Prevention, Pesticides, and Toxic Substances, EPA 734-12-92-001.

USEPA. 1993. Wildlife Exposure Factors Handbook (vol. I and II). EPA/600/R-93/187b.

http://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=2799

12.2 Submitted Environmental Fate Studies

161-1: Hydrolysis

Das, Y.T. 1988. Hydrolysis of [Phenyl (U)-

14C]-Fluometuron in Aqueous Solutions Buffered at pH 5, 7, and 9. 

Innovative Scientific Services, Inc., for Ciba Geigy Corporation. Laboratory Study ISSI No. 88020. (40864401) 

Das, Y.T. 1988. A Supplement to Hydrolysis of [Phenyl (U)-

14C]-Fluometuron in Aqueous Solutions Buffered at pH 

5, 7, and 9. Innovative Scientific Services, Inc., for Ciba Geigy Corporation. Laboratory Study ISSI No. 88020. 

(40930601)

161-2: Photolysis in Water

Das, Y.T. 1988. Photodegradation of [Phenyl (U)-

14C]-Fluometuron in Aqueous Solutions Buffered at pH 5, 7, and 

9 under Natural Sunlight. Innovative Scientific Services, Inc., for Ciba Geigy Corporation. Laboratory Study ISSI 

No. 88011. (41065101) 

161-3: Photolysis on soil

Das, Y.T. 1988. Photodegradation of [Phenyl (U)-

14C]-Fluometuron on Soil under Natural Sunlight. Innovative 

Scientific Services, Inc., for Ciba Geigy Corporation. Laboratory Study ISSI No. 88031. (40930602)

162-1: Aerobic soil metabolism

Spare, W.C. 1993a. Aerobic soil metabolism of 14C-fluometuron. Agrisearch Project No. 12196; Ciba-Geigy Study 

No. 112-90. Unpublished study performed by Agrisearch Incorporated, Frederick, MD, and submitted by CibaGeigy Corporation, Greensboro, NC. (42998702)

162-2: Anaerobic soil metabolism

Spare, W.C. 1993b. Anaerobic soil metabolism of 14C-fluometuron. Agrisearch Project No. 12197; Ciba-Geigy 

Study No. 111-90. Unpublished study performed by Agrisearch Incorporated, Frederick, MD, and submitted by 

Ciba-Geigy Corporation, Greensboro, NC. (42998703)

162-3: Anaerobic aquatic metabolism

Spare, W.C. 1994. Anaerobic aquatic metabolism of 14C-fluometuron. Agrisearch Project No. 12204; Ciba-Geigy 

Study No. 44-92. Unpublished study performed by Agrisearch Incorporated, Frederick, MD, and submitted by 

Ciba-Geigy Corporation, Greensboro, NC. (43158901)

163-1: Mobility/ Adsorption/ Desorption

Spare, W.C. 1992d. Adsorption/desorption of 14C-fluometuron. Agrisearch Project No. 12200; Ciba-Geigy Study 

No. 19-92. Unpublished study performed by Agrisearch Incorporated, Frederick, MD, and submitted by Ciba-Geigy 

Corporation, Greensboro, NC. (42643601)

Spare, W.C. 1992c. Adsorption/desorption of 14C-CGA-72903. Agrisearch Project No. 12203; Ciba-Geigy Study 

No. 22-92. Unpublished study performed by Agrisearch Incorporated, Frederick, MD, and submitted by Ciba-Geigy 

Corporation, Agricultural Division, Greensboro, NC. (42643602)
Page 25 of 43

Spare, W.C. 1992a. Adsorption/desorption of 14C-CGA-41685. Agrisearch Project No. 12202; Ciba-Geigy Study 

No. 20-92. Unpublished study performed by Agrisearch Incorporated, Frederick, MD, and submitted by Ciba-Geigy 

Corporation, Agricultural Division, Greensboro, NC. (42643603)

Spare, W.C. 1992b. Adsorption/desorption of 14C-CGA-41686. Agrisearch Project No. 12201; Ciba-Geigy Study 

No. 21-92. Unpublished study performed by Agrisearch Incorporated, Frederick, MD, and submitted by Ciba-Geigy 

Corporation, Agricultural Division, Greensboro, NC. (42643604)

164-1: Terrestrial Field Dissipation

White, S.M. 1987. Field Dissipation Study on Fluometuron for Terrestrial Uses on Cotton, Donalsonville, Georgia. 

Ciba Geigy Corporation, Greensboro, NC. (40459401)

White, S.M. 1987. Field Dissipation Study on Fluometuron for Terrestrial Uses on Cotton, Ripton, California. 

Performed by Landis Associates, Inc., Valdosta, Georgia. Submitted by Ciba Geigy Corporation, Greensboro, NC. 

(40459402)

165-4: Bioacccumulation in Fish

Shortelle, A.B., C.V. Manning, and G.C. Ward. 1990. 14C-Fluometuron: Accumulation and Depuration of 14CResidues by Bluegill Lepomis macrochirus. Performed by Hunter/ESE, P.O. Box 1703, Gainesville, Florida. 

Laboratory Project ID #88311-0200-2130. Completed 2/9/90. Submitted by Ciba-Geigy Corporation, Agricultural 

Division, Greensboro, N.C. (42017304)

Cruz, S.M. 1992. Bioacccumulation of 14C-Fluometuron in Bluegill Sunfish: Response to the January 10, 1992 

EPA Review of Fluometuron Environmental Fate Studies. Performed by Ciba Geigy Corporation, Greensboro, NC. 

(42413502)

166-1,2: Ground Water Monitoring

Demartinis J. 1991. Small-Scale Retrospective Ground Water Monitoring Study for CotoranTM-Final Report, 

Volumes 1 and 2. Ciba Geigy, Greensboro, NC. (41931501)

12.3 Submitted Ecological Toxicity Studies

Guideline: 850.1010 Daphnid acute toxicity test

MRID: 24180 Citation: Vilkas, A.G. (1977) The Acute Toxicity of Technical Fluometuron to the Water 

Flea,~Daphnia magna~ Straus: UCES Proj. # 11506- 04-07. (Unpublished study received June 22, 1978 under 100-

561; prepared by Union Carbide Environmental Services, submitted by Ciba-Geigy Corp., Greensboro, N.C.; 

CDL:234176-E) 

MRID: 40098001 Mayer, F.; Ellersieck, M. (1986) Manual of Acute Toxicity: Interpretation and Data Base for 410 

Chemicals and 66 Species of Freshwater Animals. US Fish & Wildlife Service, Resource Publication 160. 579 p. 

Guideline: 850.1025 Oyster Acute – Shell deposition

MRID: 42498005 Dionne, E. (1992) Fluometuron: Acute Toxicity to Eastern Oyster (Crassotrea virginica) Under 

Flow-Through Conditions: Lab Project Number: 1781.0292.6298.504: 92-6-4275. unpublished study prepared by 

Springborn Laboratories Inc. 59 p. 

MRID: 42560101 Lintott, D.; Ward, G. (1992) Fluometuron: Acute Effect on New Shell Growth of the Eastern 

Oyster, Crassostrea virginica: Lab Project Number: J9201011E. Unpublished study prepared by Toxikon 

Environmental Sciences. 27 p.

MRID: 43075902 Peters, G. (1993) Response to Review of Fluometuron Estuarine/Marine Mollusk Toxicity Test. 

Unpublished study prepared by Ciba-Geigy Corp. 6 p. 

MRID: 43848101 Cunningham, F.; Davis, J. (1995) Fluometuron: Acute Effects on New Shell Growth of the 

Eastern Oyster (Crassostrea virginica): Lab Project Number: J9501009: J9201001B. Unpublished study prepared by 

Toxikon Environmental Sciences. 46 p. 
Page 26 of 43

Guideline: 850.1035 Mysid acute toxicity test 

MRID: 42568501 Lintott, D. (1992) Fluometuron: Acute Toxicity to the Mysid, Mysidopsis bahia, under Flowthrough Test Conditions: Lab Project Number: J9201001C. Unpublished study prepared by Toxikon Environmental 

Sciences. 24 p. 

MRID: 42498006 Machado, M. (1992) Fluometuron: Acute Toxicity to Mysid Shrimp (Mysidopsis bahia) Under 

Flow-Through Conditions: Lab Project Number: 92-6-4301: 1781.0292.6297.515. Unpublished study prepared by 

Springborn Laboratories Inc. 63 p. 

Guideline: 850.1075 Fish acute toxicity test, freshwater and marine

MRID: 68507 Hughes, J.S.; Davis, J.T. (1964?) Effects of Selected Herbicides on Bluegill Sunfish. (Louisiana, 

Wild Life and Fisheries Commis- sion; unpublished study; CDL:231131-A) 

MRID: 19220 Bathe, R.; Ullmann, L.; Sachsse, K. (1972) Determination of the Toxicity of Pesticides to Fish. 

(Unpublished study received Jun 22, 1978 under 100-561; prepared by Ciba-Geigy, AG, submitted by Ciba-Geigy 

Corp., Greensboro, N.C.; CDL:234176-B) 

MRID: 109024 Bathe, R.; Ullmann, L.; Sachsse, K.; et al. (1975) Relationship between Toxicity to Fish and to 

Mammals: A Comparative Study under Defined Laboratory Conditions. (Unpublished paper pre- sented at the 17th 

Meeting of the European Society of Toxicol- ogy; Jun 16-18, 1975, Montpellier, Fr.; unpublished study re- ceived 

Oct 11, 1977 under 100-524; prepared by Ciba-Geigy, Ltd., Switz., submitted by Ciba-Geigy Corp., Greensboro, 

NC; CDL: 232008-B) 

MRID: 161088 Swigert, J.; Bowman, J. (1986) Acute Toxicity of Fluometuron to Bluegill Sunfish (Lepomis 

macrochirus): Static Acute Toxicity Report #34522. Unpublished study prepared by Analytical Bio-Chemistry 

Laboratories, Inc. 14 p. 

MRID: 40098001 Mayer, F.; Ellersieck, M. (1986) Manual of Acute Toxicity: Interpretation and Data Base for 410 

Chemicals and 66 Species of Freshwater Animals. US Fish & Wildlife Service, Resource Publication 160. 579 p. 

MRID: 42498002 Machado, M. (1992) Fluometuron: Acute Toxicity to Bluegill Sunfish (Lepomis macrochirus) 

Under Flow-Through Conditions: Lab Project Number: 92-7-4327: 1781.0292.6300.105. Unpublished study 

prepared by Springborn Laboratories Inc. 70 p. 

MRID: 42498003 Machado, M. (1992) Fluometuron: Acute Toxicity to Rainbow Trout (Oncorhynchus mykiss) 

Under Flow-Through Conditions: Lab Project Number: 92-6-4297: 1781.0292.6299.108. Unpublished study 

prepared by Springborn Laboratories Inc. 67 p. 

MRID: 42505001 McElwee, C.; Lintott, D. (1992) Fluometuron: Acute Toxicity to Rainbow Trout, Oncorhynchus 

mykiss, under Static Test Conditions: Lab Project Number: J9208001. Unpublished study prepared by Toxikon 

Environmental Sciences. 24 p. 

MRID 47607401 Soucy, K. (2008) Acute Toxicity to Fathead Minnow (Pimephales promelas) Under Static 

Conditions, following OPPTS Draft Guidelines: (Fluometuron). Project Number: 13929/6101, 

032708/OPPTS/ST/FHM/. Unpublished study prepared by Springborn Smithers Laboratories. 53 p.

MRID: 42498004 Machado, M. (1992) Fluometuron: Acute Toxicity to Sheepshead Minnow (Cyprinodon 

variegatus) Under Flow-Through Conditions: Lab Project Number: 92-6-4304: 1781.0292.6301.505. Unpublished 

study prepared by Springborn Laboratories Inc. 67 p. 

MRID: 42505002 Lintott, D. (1992) Fluometuron: Acute Toxicity to Sheepshead Minnow, Cyprinodon variegatus, 

under Static Test Conditions: Lab Project Number: J9206006. Unpublished study prepared by Toxikon 

Environmental Sciences. 23 p. 

MRID: 43075901 Peters, G. (1993) Response to Review of Fluometuron Estuarine/Marine Fish Toxicity Test. 

Unpublished study prepared by Ciba-Geigy Corp. 6 p. 
Page 27 of 43

Guideline: 850.1300 Daphnid chronic toxicity test

MRID: 46565701 Firth, K. (2002) Fluometuron Technical: Prolonged Toxicity to Daphnia magna. Project 

Number: AGM/159/023724, 90005120. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 47 p.

MRID: 47978401 Citation: Jenkins, C. (2010) Fluometuron Technical: Prolonged Toxicity to Daphnia magna. 

Project Number: AGM0159/023724. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 3 p.

Guideline: 850.1350 Mysid chronic toxicity test

MRID: 48080701 Hicks, S. (2010) Fluometuron: Life-Cycle Toxicity Test of the Saltwater Mysid, Americamysis 

bahia, Conducted Under Flow-Through Conditions. Project Number: 65181, 90012757. Unpublished study 

prepared by ABC Laboratories, Inc. 81 p.

Guideline: 850.1400 Fish early-life stage toxicity test

MRID: 46565702 Albuquerque, R. (2003) Fluometuron Technical: Fish Early Life Stage Toxicity Test for Fathead 

Minnow. Project Number: AGM/158, AGM/158/023687, 90005271. Unpublished study prepared by Huntingdon 

Life Sciences, Ltd. 58 p.

MRID: 18645 Lawrence, J.M. (1964) The Effect of C-2059, Tenoran, C-3126, and C-3095 on Fathead Minnows. 

(Unpublished study received Oct 8, 1964 under 100-548; prepared by Auburn Univ., submitted by Ciba- Geigy 

Corp., Greensboro, N.C.; CDL:023178-L) 

MRID: 18646 Takeda Chemical Ind., Limited (1963) Test on Fish Toxicity of C- 1936, C-1983, and C-2059. 

(Unpublished study received Oct 8, 1964 under 100-548; submitted by Ciba-Geigy Corp., Greensboro, N.C.; 

CDL:023177-L) 

MRID: 19162 Lawrence, J.M. (1964) The Effect of C-2059, Tenoran, C-3126, and C-3095 on Fathead Minnows: 

Research Report CF-70. (Unpublished study received Oct 8, 1964 under 100-549; prepared by Auburn Univ., 

submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL: 007070-S) 

Guideline: 850.2100 Avian Single Dose Oral Toxicity

MRID: 19221 Beavers, J.B.; Brown, R.; Fink, R. (1977) Final Report: Acute Oral LD50--Mallard Duck: Project 

No. 108-133. (Unpublished study re- ceived Jun 22, 1978 under 100-561; prepared by Wildlife Interna- tional, Ltd. 

in cooperation with Washington College, submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL:234176-C) 

Guideline: 850.2200 Avian Dietary Toxicity

MRID: 19222 Robinson, D.; Shillam, K.W.G. (1970) Acute Toxicity of Fluometuron to the Japanese Quail, RingNecked Pheasant and Mallard Duck. (Unpublished study received Jun 22, 1968 under 100-561; prepared by 

Huntingdon Research Centre, submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL:234176-D) 

MRID: 42498001 Campbell, S.; Lynn, S. (1992) Fluometuron: A Dietary LC50 Study with the Northern Bobwhite: 

Lab Project Number: 108-353. Unpublished study prepared by Wildlife International Ltd. 39 p. 

MRID: 42597401 Pedersen, C.; Mumper, J. (1992) Fluometuron Technical: 8-day Acute Dietary LC50 Study in 

Bobwhite Quail: Lab Project Number: 130-001-01. Unpublished study prepared by Bio-Life Associates, Ltd. 67 p. 

Guideline: 850.2300 Avian reproduction test

MRID: 46565703 Mitterer, K. (2003) Study on Reproduction in Birds (Bobwhite Quail) with Fluometuron by Oral 

Administration via the Diet. Project Number: 90003450, 14750/01. Unpublished study prepared by Laboratorium 

fuer Pharmakologie und Tox. 279 p.

MRID: 47896201 Frey, L.; Martin, K.; Beavers, J.; et al. (2009) Fluometuron: A Reproduction Study with the 

Mallard: Final Report. Project Number: 234/111. Unpublished study prepared by Wildlife International, Ltd. 153 

p.
Page 28 of 43

MRID: 47984401 Leuschner, J. (2010) Study on Reproduction in Birds (Bobwhite Quail) with Fluometuron by 

Oral Administration via the Diet. Project Number: 14750/01/AMENDMENT/NO/1. Unpublished study prepared 

by Laboratorium fuer Pharmakologie und Tox. 291 p.

Guideline: 850.4100 Seedling emergence 

MRID: 43530301 Kranzfelder, J. (1995) Fluometuron: Seed Germination/Seedling Emergence: Lab Project 

Number: J9403004A: J9201001H. Unpublished study prepared by Toxikon Environmental Sciences. 99 p. 

MRID: 42695801 Kegley, M. (1993) Fluometuron: Seed Germination/Seedling Emergence: Lab Project Number: 

J9201001F. Unpublished study prepared by Toxikon Environmental Sciences. 30 p. 

MRID: 42718801 Chetram, R. (1993) Tier 2 Seed Germination Nontarget Phytotoxicity Study Using Fluometuron: 

Lab Project Number: 92060. Unpublished study prepared by Pan Agricultural Labs, Inc. 111 p. 

MRID: 42718802 Chetram, R. (1993) Tier 2 Seedling Emergence Nontarget Phytotoxicity Study Using 

Fluometuron: Lab Project Number: 92061. Unpublished study prepared by Pan-Agricultural Labs, Inc. 283 p. 

Guideline: 850.4150 Vegetable Vigor

MRID: 42795001 Kegley, M. (1993) Fluometuron: Vegetative Vigor: Lab Project Number: J9201001G. 

Unpublished study prepared by Toxicon Environmental Sciences. 29 p. 

MRID: 43530302 Kranzfelder, J. (1995) Fluometuron: Vegetative Vigor: Lab Project Number: J9403004B: 

J9201001H. Unpublished study prepared by Toxikon Environmental Sciences. 65 p. 

MRID: 42718803 Chetram, R. (1993) Tier 2 Vegetative Vigor Nontarget Phytotoxicity Study Using Fluometuron: 

Lab Project Number: 92062. Unpublished study prepared by Pan-Agricultural Labs, Inc. 287 p. 

Guideline: 850.4400 Aquatic plant growth using Lemna spp.

MRID: 43421601 Jones, F. (1994) Fluometuron: Acute Toxicity to Duckweed, Lemna gibba G3, under Static Test 

Conditions: Lab Project Number: J9403004D. Unpublished study prepared by Toxikon Environmental Sciences. 

26 p. 

MRID: 42564102 Ward, G.; Lintott, D. (1992) Fluometuron: Acute Toxicity to Duckweed, Lemna gibba G3, under 

Static Test Conditions: Lab Project Number: J9201001K. Unpublished study prepared by Toxikon Environmental 

Sciences. 27 p. 

Guideline: 850.4500 Aquatic plant growth using algae

MRID: 42498007 Hoberg, J. (1992) Toxicity to the Freshwater Green Alga, (Selenastrum capricornutum): Lab 

Project Number: 92-5-4273: 1781.0292.6296.430. Unpublished study prepared by Springborn Laboratories Inc. 61 

p. 

MRID: 43075903 Peters, G. (1993) Response to Review of Fluometuron Aquatic Plant Growth Test. Unpublished 

study prepared by Ciba-Geigy Corp. 10 p. 

MRID: 42564101 Ward, G.; Lintott, D. (1992) Fluometuron: Acute Toxicity to the Saltwater Diatom, Skeletonema 

costatum under Static Test Conditions: Lab Project Number: J9201001M. Unpublished study prepared by Toxikon 

Environmental Sciences. 29 p. 

MRID: 42568502 Lintott, D. (1992) Fluometuron: Acute Toxicity to the Freshwater Diatom, Nitzschia palea, 

under Static Test Conditions: Lab Project Number: J92010010. Unpublished study prepared by Toxikon 

Environmental Sciences. 30 p. 

MRID: 43025601 Ward, G.; Lintott, D. (1992) Fluometuron: Acute Toxicity to the Freshwater Green Alga, 

Selenastrum capricornutum, Under Static Test Conditions: Lab Project Number: J9201001L. Unpublished study 

prepared by Toxikon Environmental Sciences. 30 p. 

Guideline: 850.4500 Aquatic plant growth using cyanobacteria
Page 29 of 43

MRID: 43421602 Jones, F. (1994) Fluometuron: Acute Toxicity to Freshwater Blue-Green Alga, Anabaena flosaguae, under Static Test Conditions: Lab Project Number: J9403004C. Unpublished study prepared by Toxikon 

Environmental Sciences. 25 p. 

MRID: 42564103 Juarovisech, K.; Lintott, D. (1992) Fluometuron: Acute Toxicity to the Freshwater Blue-Green 

Alga, Anabaena flos-aquae, under Static Test Conditions: Lab Project Number: J9201001N. Unpublished study 

prepared by Toxikon Environmental Sciences. 29 p. 

MRID: 42568503 Juarovisech, K.; Lintott, D. (1992) Fluometuron: Acute Toxicity to the Freshwater Blue-green 

Alga, Anabaena Flos-aquae, under Static Test Conditions: Lab Project Number: J9201001N. Unpublished study 

prepared by Toxikon Environmental Sciences. 29 p. 
Page 30 of 43

Appendix A. SIP Fluometuron Modeling Results

Table 1. Inputs

Parameter Value

Chemical name fluometuron

Solubility (in water at 25oC; mg/L) 90

Mammalian LD50 (mg/kg-bw) 1000

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg-bw) 10

Mammalian test species Other - rabbit

Body weight (g) of "other" mammalian species 3768

Avian LD50 (mg/kg-bw) 2974

Avian test species mallard duck

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 60.4

Bobwhite quail NOAEC (mg/kg-diet) 0

NOAEC (mg/kg-diet) for other bird species 0

Body weight (g) of other avian species

NOAEC (mg/kg-diet) for 2nd other bird species 0

Body weight (g) of 2nd other avian species

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 15.4800 15.4800

Adjusted toxicity value (mg/kg-bw) 769.1606 13.9325

Ratio of exposure to toxicity 0.0201 1.111

Conclusion*

Drinking water exposure alone 

is NOT 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) 72.9000 72.9000

Adjusted toxicity value (mg/kg-bw) 1544.1764 2.9966

Ratio of exposure to acute toxicity 0.0472 24.3276

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.

Appendix B. STIR Fluometuron Modeling Results

This tool is designed to provide the risk assessor with a rapid method for determining the potential
Page 31 of 43

significance of the inhalation exposure route to birds and mammals in a risk assessment.

Input

Application and Chemical Information

Enter Chemical Name fluometuron

Enter Chemical Use herbicide

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) 232

Enter Chemical Vapor Pressure (mmHg) 5.00E-07

Enter Application Rate (lb a.i./acre) 2

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 2974

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 1.58

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 1000

Enter Lowest Rat Inhalation LC50 (mg/L) 0.6

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) 6.24E-03

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 7.85E-04

Adjusted Inhalation LD50 7.17E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.09E-04 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 1.92E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 2.68E-02 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 6.24E-03

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 9.86E-04

Adjusted Inhalation LD50 3.57E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 2.76E-05 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 2.42E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 6.76E-03 Exposure not Likely Significant

Appendix C. Summary of Fluometuron Environmental Fate

Data
Page 32 of 43

161-1: Hydrolysis: Fluometuron is stable to hydrolysis at pH 5, 7 and 9 aqueous buffer solutions 

incubated at 25oC. This data requirement is fulfilled (GLN 161-1, MRID's 40864401, 40930601).

161-2: Photolysis in Water: Fluometuron is stable to aqueous photolysis in pH 5, 7, and 9 buffer

solutions at 25 oC irradiated with natural sunlight and in dark controls This data requirement is 

fulfilled (GLN 161-2); MRID's 41065101).

161-3: Photolysis on soil: Fluometuron is stable to photolysis on sandy loam soil irradiated with 

natural sunlight and in dark controls. This data requirement is fulfilled (GLN 161-3, MRID 

40930602).

162-1: Aerobic soil metabolism: Fluometuron slowly degraded with a calculated half-life of 181 

days in aerobic sandy loam soil. The identified major degradate was CGA-41686 (parent with 1 

methyl group removed). The minor degradates were CGA-41685 (parent with 2 methyl groups 

removed) and CGA-72903 (decarboxlated, demethylated parent compound). This data 

requirement is fulfilled (GLN 162-1, MRID 42998702).

162-2: Anaerobic soil metabolism: Fluometuron slowly degraded in anaerobic soil with a 

calculated half-life of 378 days following 30 days of aerobic incubation plus 60 days of anaerobic 

incubation. The identified major degradate was CGA-41686 (parent with 1 methyl group 

removed). The minor degradates were CGA-41685 (parent with 2 methyl groups removed) and 

CGA-72903 (decarboxlated, demethylated parent compound). This data requirement is fulfilled 

(GLN 162-2, MRID 42998703).

162-3: Anaerobic aquatic metabolism: Fluometuron slowly degraded with a half-life of 177 

days following 365 days of anaerobic incubation plus nitrogen atmosphere. The identified major 

degradate was CGA-41686 (parent with 1 methyl group removed). There were several minor 

degradates that ranged in concentration from <1.7 to 6.2 % of applied. This data requirement is 

fulfilled (GLN 162-3, MRID 43158901).

Leaching-adsorption-desorption (163-1)

Unaged Batch Equilibrium of Parent Fluometuron

Parent fluometuron is very mobile in Sassafras sand (Maryland, 0.23 % OC), Hesperia sandy

loam (California, 0.26 % OC), Sesquatchie sandy clay loam (Maryland, 0.45 % OC), and

Sharkey clay (Mississippi, 1.40 % OC) soils with Freundlich Kads values of 0.08, 0.15, 0.25, and

1.13, respectively. Freundlich Kdes values were 2.93, 1.48, 4.93, and 4.25, respectively. Kocads

were 35, 57, 54, and 80 and Kocdes values were 1277, 561, 1075, and 300, respectively. The N

values were 1.15, 1.16, 1.15, and 1.08 for adsorption and 1.00, 1.19, 0.99, and 1.08 for desorption, 

respectively. The unaged portion of the data requirement is fulfilled (GLN 163-1, MRID 

42643601).

Batch Equilibrium of Three Metabolites

The primary degradate (CGA-41686) was very mobile in Sassafras sand (Maryland, 0.23 %

OC), Hesperia sandy loam (California, 0.26 % OC), Sesquatchie sandy clay loam (Maryland,

0.45 % OC), and Sharkey clay (Mississippi, 1.40 % OC) soils with Freundlich Kads values of
Page 33 of 43

0.16, 0.33, 0.57, and 2.00, respectively. Freundlich Kdes values were 3.90, 4.55, 6.44, and 6.25,

respectively. Kocads were 69, 125, 123, and 141 and Kocdes values were 1700, 1719, 1404, and

441, respectively. The N values were 1.14, 1.11, 1.21, and 1.14 for adsorption and 1.05, 1.02,

1.03, 1.10 for desorption, respectively. The aged portion of the data requirement is fulfilled

(163-1, MRID 42643604).

CGA-41685 (parent with both methyl groups removed) was very mobile in Sassafras sand

(Maryland, 0.23 % OC), Hesperia sandy loam (California, 0.26 % OC), Sesquatchie sandy clay

loam (Maryland, 0.45 % OC), and Sharkey clay (Mississippi, 1.40 % OC) soils with Freundlich

Kads values of 0.20, 0.27, 0.48, and 1.89, respectively. Freundlich Kdes values were 2.56, 2.38,

3.33, and 6.78, respectively. Kocads were 88, 101, 104, and 133 and Kocdes values were 1119, 

900, 725, and 478, respectively. The N values were 1.13, 1.06, 1.26, and 1.15 for adsorption and

1.15, 1.14, 1.32, 1.11 for desorption, respectively. The aged portion of the data requirement is

fulfilled (163-1, MRID 42643603).

CGA-72903 (decarboxylated parent fluometuron) was very mobile in Sassafras sand (Maryland,

0.23 % OC), Hesperia sandy loam (California, 0.26 % OC), Sesquatchie sandy clay loam

(Maryland, 0.45 % OC), and Sharkey clay (Mississippi, 1.40 % OC) soils with Freundlich Kads

values of 0.23, 0.23, 0.30, and 2.33, respectively. Freundlich Kdes values were <30, 6.77, <30,

and 20.68, respectively. Kocads were 102, 87, 66, and 164 and Kocdes values were <13,100, 

2559, <6536, and 1459, respectively. The N values were 1.28, 1.40, 1.65, and 1.21 for adsorption 

and 1.0 (assumed), 1.63, 1.0 (assumed), and 1.33 for desorption, respectively. The aged portion of

the data requirement is fulfilled (163-1, MRID 42643602).

Terrestrial Field Dissipation (164-1); MRID 40459401, 40459402, 41931501, 5/9/88. The

calculated half-lives of fluometuron were 103 days in Georgia Lucy loamy sand (0.9 % OM) and 

97 days in Veritas fine sandy loam (1.3 % OM). Even with below average rainfall, detectable 

levels of parent fluometuron and the primary degradate CGA-41686 reached 24 inches of depth.

Bioaccumulation in Fish (165-4); MRID 42017304, reviewed on 9/14/87, and MRID

42413502. The calculated bioconcentration factors were 6.88x for edible, 861.5x for non-edible,

and 51.7x for whole fish. Dealkylated fluometuron and hydroxylated and conjugated metabolites

were present in fish.

Small-Scale Retrospective (166-2); MRID 41931501, 10/2/91. Fluometuron and its main

metabolite CGA-41686 were repeatedly found in shallow ground water monitoring wells (<5 feet 

in depth), piezometers, and loamy sand/sandy loam (maximum of 1.6 % OM) soil samples in 

North Carolina. Maximum concentrations of parent fluometuron were 99 ppb in ground water, 23 

ppb in piezometers, and 19 ppb in soil (12-24 inch depth). Maximum concentrations of CGA41686 were 34 ppb in ground water, 21 ppb in piezometers, and 21 ppb in soil (12-24 inch depth). 

In Mississippi, there were no detections in ground water above the detection limit of 0.1 ppb. 

Fluometuron and its main metabolite CGA-41686 were found in lysimeters at low levels with

maximum concentrations of 0.7 and 1.7 ppb, respectively. CGA-41686 was found in very fine 

sandy loam soil (0.8 % OM) down to the 24-36 inch soil depth at 13 ppb.
Page 34 of 43
Page 35 of 43

Appendix D. Summary of Fluometuron Ecotoxicity Data

Acute Toxicity of Fluometuron to Freshwater Fish

Species % ai

96-hr LC50 

(95%CI)

(mg a.i./L)

Toxicity 

Category Comments MRIDStudy Classification

Bluegill sunfish 

(Lepomis

macrochirus)

97.2 >100 Practically 

non-toxic

Uncertainties since 

precipitate at all test 

concentrations (12.5 to 

100 mg a.i./L), nominal 

concentrations reported

161088 Supplemental 

(precipitate at all test 

concentrations)

97.2 48 (41, 57)

slope = 5.7

Slightly 

toxic

Slight precipitate in 

mixing chamber, none in 

test aquaria, test 

concentrations were 

measured

42498002 Acceptable

96.2 42.5 Slightly 

toxic Nominal concentrations 40098001 acceptable

80 

(WP) 13.5 Slightly toxic

Nominal concentrations, 

precipitate at test 

concentration of 100 mg 

a.i./L

40098001

Supplemental (end-use 

product, precipitate 

noted)

Rainbow trout 

(Oncorhynchus

mykiss)

97.2 30 (26, 34)

Slope = 10.0

Slightly 

toxic

Slight precipitate in 

mixing chamber and 

highest test concentration, 

test concentrations were 

measured

42498003 Acceptable

97.5 26 (19, 37) Slightly 

toxic No precipitate noted 42505001 Acceptable

98.7 2.96 Moderately 

toxic Nominal concentrations 40098001 Supplemental (raw data not found)

96.2 14.5 Slightly 

toxic Nominal concentrations 40098001 Supplemental

80 

(WP) 4.3 Moderately toxic Nominal concentrations

40098001

Supplemental (end-use 

product)

Fathead minnow 

(Pimephales 

promelas)

97.8

65 (49, 95)

Binomial 

method

Slightly 

toxic

Precipitate at highest test 

concentration; solutions 

were not centrifuged or 

filtered prior to chemical 

analysis

47607401

Supplemental 

(precipitate at highest 

test concentration)

Channel catfish

Ictalurus 

punctatus

-- -- --

Water temperature at 

18oC; 850.1075 guideline 

temp is 22o ± 2.0 

40098001

(invalid, water temp 

below recommended)

96.2 22.5 Slightly 

toxic Nominal concentrations 40098001supplemental

80 

(WP) 11.5 Slightly toxic Nominal concentrations

40098001 Supplemental 

(end-use product, raw 

data not found)
Page 36 of 43

Acute Toxicity of Fluometuron to Estuarine/Marine Fish 

Species/Static

or Flow-through

% ai LC50 (mg 

a.i./L)

Toxicity 

Category

MRID Study Classification

Sheepshead minnow

(Cyprinodon 

variegatus)

97.2 38 Slightly toxic 42498004 (Supplemental; 

undissolved test material at all 

concentrations, analytical samples 

not centrifuged or filtered, 

measured concentrations were 97 

to 121% of nominal)

97.5 55.3 Slightly toxic 42505002 (Acceptable)

Acute Toxicity of Fluometuron to Freshwater Invertebrates

Species % ai EC50 (95% CI)

(mg a.i./L)

Toxicity 

Category

Comments MRID

Study 

Classification

Daphnid 

(Daphnia 

magna)

Tech 9.9 mg a.i./L

(8.3, 11.9)

Moderately 

toxic

Nominal concentrations; 

48-hr study

0024180

Acceptable

96.2 >1.0 Moderately 

toxic

Nominal concentrations; 

1/10 mortalities at 1.0 mg 

a.i./L; 96-hr study

40098001

supplemental

80 

(WP)

>1.0 Moderately 

toxic

Nominal concentrations; 

3/10 mortalities at 1.0 mg 

a.i./L; 96-hr study

40098001

Supplemental 

(end-use product)

Midge

(Chironomus 

plumosus)

96.2 0.22 Highly toxic Nominal concentrations; 

96-hr study

40098001

Supplemental (not 

recommended 

species)

80 

(WP)

>1.0 Moderately 

toxic

Nominal concentrations; 

96-hr study

40098001

Supplemental (not 

recommended 

species, end-use 

product)

Acute Toxicity of Fluometuron to Estuarine/Marine Invertebrates

Species % ai. Toxicity Endpoint Toxicity 

Category

MRID

Study Classification

Mysid (Americamysis 

bahia)

97.5 LC50 = 3.8 mg a.i./L Moderately 

toxic

42568501 (Acceptable)

97.2 LC50 = 6.8 mg a.i./L Moderately 

toxic

42498006 (Acceptable)

Oyster Shell

Deposition: Mollusk, 

Crassostrea virginica

97.2 IC50 = 22 mg a.i./L Slightly toxic 42498005 (Supplemental, 

average control shell 

deposition less than 2 mm)

97.6 IC50 = 6.53 mg a.i./L Moderately 

toxic

43848101

(Acceptable)

-- -- -- 42560101 (Invalid; Low 

flow rate, lack of food, 

dissolved oxygen <60% 

throughout study)
Page 37 of 43

Chronic Toxicity of Fluometuron to Aquatic Animals

Species % a.i. Endpoints

(mg ai/L) Effects MRID (Study Classification)

Fathead minnow 

(Pimephales 

promelas)

98.3% NOAEC = 3.1

LOAEC = 9.1

Reductions in growth (length 

and dry weight)

46565702 (Acceptable)

-- -- --

18645 (Invalid, study 

not conducted under 

Agency guidelines)

-- -- --

18646 (Invalid, study 

not conducted under 

Agency guidelines)

-- -- --

19162 (Invalid, study 

not conducted under 

Agency guidelines)

Water flea

(Daphnia magna) 98.3% NOAEC = 1.73LOAEC = 2.52

Reduced number of young per 

reproductive day.

46565701 and 47978401 

(Acceptable)

Mysid 

(Americamysis 

bahia)

98.4% NOAEC = 1.32

LOAEC = 2.68

Most sensitive endpoints: 

F0 Day 13 survival (before 

pairing) and F0 male body 

lengths on Day 28

48080701 (Acceptable)

Acute Oral Toxicity of Fluometuron to Birds

Species % ai LD50

(95% confidence 

interval)

(mg a.i./kg-bwt)

Toxicity 

Category

Comments MRID

Study 

Classification

Mallard duck

(Anas 

platyrhynchos)

80% TEP >2000 Practically nontoxicNo mortalities, 

only 3 birds used. 

Toxic signs were 

ataxia, wing drop 

or cross over back, 

etc; persisted for a 

week.

160000

Supplemental

Mallard duck

(Anas 

platyrhynchos)

Technical 

(purity not 

specified)

2974

(2060, 4269)

Practically nontoxic00019221

Acceptable
Page 38 of 43

Subacute Dietary Toxicity of Fluometuron to Birds

Species % ai 5-Day LC50

(95% confidence 

interval)

(mg a.i./kg-diet)

Toxicity 

Category

Comments MRID

Study 

Classification

Northern 

bobwhite quail

(Colinus 

virginianus)

97.8 >5620 Practically 

non-toxic

One mortality at 3160 

mg a.i./kg-diet. Sublethal toxic effects at 

≥ 1000 mg a.i./kg-diet 

(wing droop, lethargy, 

reduced weight gain)

42498001

Acceptable

97.5 >3474 Slightly 

toxic

One mortality at 3474 

mg a.i./kg-diet.

42597401

Acceptable

Japanese quail 

(Coturnix 

japonica)

Technical 

(purity not 

specified)

4620

(3250, 6550)

Slightly 

toxic

Sublethal toxic effects 

included huddling, 

lethargy, and reduced 

weight gain.

00019222

Supplemental

Mallard duck Technical 

(purity not 

specified)

4500

(3400, 5960)

Slightly 

toxic

Sublethal toxic effects 

included huddling, 

lethargy, and reduced 

weight gain.

00019222

Acceptable

Ring-necked 

pheasant 

(Phasianus 

colchicus)

Technical 

(purity not 

specified)

3150

(1750, 5670)

Slightly 

toxic

Sublethal toxic effects 

included huddling, 

lethargy, and reduced 

weight gain.

00019222

Acceptable
Page 39 of 43

Chronic Toxicity of Fluometron to Birds

Species % A.I. Toxicity 

Endpoints

Affected Endpoints MRID and Status

Bobwhite quail 98.7%

NOAEC = 477 

mg ai/kg diet 

LOAEC > 477 mg 

ai/kg diet 

No statistically significant 

reductions in endpoints at 

any test concentration. 

47984401

Supplemental (concentrations in 

diet were increased three-fold 

five weeks into the study, from 

14.7, 50. and 146 mg a.i./kg-diet 

to 43, 150, and 477 mg ai.i/kgdiet)

Bobwhite quail --- --- ---

46565703

Invalid (non-reproducing pairs 

were removed data analysis)

Mallard duck 97.8%

NOAEC: 60.4 

mg ai/kg diet

LOAEC: 102 mg 

ai/kg diet 

At 102 mg a.i./kg-diet 

(highest tested 

concentration), reduced 

number of eggs laid and 

reduced hatchling weight. 

47896201

Acceptable

Acute Oral Toxicity of Fluometuron to Mammals

Species % ai LD50 (95% CI)

(mg a.i./kg-bw)

Toxicity 

Category

Comments MRID

Study 

Classification

Laboratory 

rat 

(Rattus 

norvegicus)

80% LD50 between 1000 

and 1500 mg a.i./kgbw

Slightly 

toxic

Female: 0% mortality at 

1000 mg a.i./kg-bw and 

100% mortality at 1500 mg 

a.i./kg-bw and above.

Male LD50 = 3880 mg 

a.i./kg-bwt (3020, 4980)

41216802 

(Acceptable)

Laboratory 

rat 

80% LD50 = 5223 (4111, 

6636)

Practically 

non-toxic

Males and females 

combined

40409302 

(Acceptable)

Laboratory 

rat 

80% LD50 = 3949 (male)

LD50 = 3209 (female)

Practically 

non-toxic

00142844

(Acceptable)

Acute Inhalation Toxicity of Fluometuron to Mammals

Species % ai LC50

(mg a.i./L)

HED Toxicity 

Category

MRID

Study Classification

Laboratory rat 80% LC50 > 0.6 III 40409304 (Acceptable)

Laboratory rat 80% LC50 > 2.25 III 41216804 (Acceptable)

Laboratory rat 80% LC50 > 6.16 III 00145431 (Acceptable)
Page 40 of 43

Chronic Toxicity of Fluometuron to Mammals

Species/

Guideline

Toxicity

Value

Affected

Endpoints

Study 

Classification

Laboratory rat

Developmental 

Toxicity 

870.3700

NOAEL = 10 

mg/kg/day

LOAEL = 100 

mg/kg/day

Doses tested: 0, 10, 100, 1000 mg/kg/day from 

days 6 thru 15 of presumed gestation.

Maternal NOAEL= 10 mg/kg; 

Maternal LOAEL= 100 mg/kg, based on the 

reduction of food consumption and on the increased 

darkened spleen.

Developmental NOAEL= 10 mg/kg

Developmental LOAEL= 100 mg/kg, based on an 

increased delayed urinary system development 

(shortened renal papillae). Females at 1000 

mg/kg/day also exhibited: reduced body weight, 

reduced viability, lethargy & salivation. Fetal 

abnormalities at 1000 mg/kg/day included reduced 

fetal weight, increased resorptions & 

postimplantation loss, and skeletal abnormalities.

00163710

42397601

(acceptable)

Rabbit

Developmental 

Toxicity 

870.3700

NOAEL = 10 

mg/kg/day

LOAEL = 100 

mg/kg/day

NOAEC = 189 mg 

a.i./kg-diet a

LOAEC = 1890 mg 

a.i./kg-diet

Doses tested 0, 1, 10, 100 mg/kg on days 7-19 of 

gestation, inclusively.

Maternal toxicity NOAEL= 10 mg/kg

Maternal toxicity LOAEL= 100 mg/kg, based on 

increased incidence of stool variations and 

abortions, reduced food consumption, decreased 

maternal body wt. gain.

Developmental toxicity NOAEL= 100 mg/kg 

(HDT) No developmental toxicity was observed.

00163774

00147554

42397602

(acceptable)

Laboratory rat. 

2-Generation

Reproduction. 

870.3800

NOAEL= 0.5 mg/kg 

(10 ppm)

LOAEL= 15 mg/kg 

(300 ppm)

Doses tested: 10, 300, 1000 ppm (0, 0.5, 15, 50 

mg/kg) 

Systemic (Maternal &Paternal) NOAEL= 0.5 

mg/kg (10 ppm)

Systemic LOAEL= 15 mg/kg (300 ppm), based on 

spleen effects (extramedullary hematopoiesis, and 

an increase in hemosiderin-laden macrophages).

Reproductive NOAEL= Study not rigorous enough 

to base a conclusion on whether fluometuron has 

the potential to affect reproductive performance.

RfD Committee concluded study is adequate for 

risk assessment purposes. (TXR 010710b)

00163773

(acceptable)

a NOAEC and LOAEC calculated as follows: Female rabbits in study ranged in weight from 3.045 to 4.491 kg; 

average of minimum and maximum weights was used to estimate food consumption (3.768 kg). Daily food 

consumption was estimated using the following allometric equation in USEPA (1993):

 kg-diet/day = 0.067 * (rabbit wt, kg) 0.822 = 0.199 kg-diet/day

Daily consumption of fluometuron at NOAEL: 

 NOAEL * bw = 10 mg ai./kg-bw/day * 3.768 kg = 37.68 mg a.i./day

NOAEC = daily consumption of fluometuron at NOAEL / daily food consumption

 = 37.67 mg a.i./day / 0.199 kg-diet/day = 189 mg a.i./kg-diet b Ghali, G. (1993). Fluometuron: RfD/Peer Review Report, dated December 9, 1993; TXR No. 010710
Page 41 of 43

Acute Contact Toxicity of Fluometuron to Nontarget Insects 

Species % ai LD50 NOEC Toxicity 

Category

MRID

Study Classification

Honey bee

(Apis mellifera)

NA LD50 > 11 μg 

a.i./bee

3.80 % mortality 

at 193.38 μg 

a.i./bee

Practically 

non-toxic

00006653 and 00028772

Acceptable

Toxicity of Fluometuron to Nontarget Terrestrial Plants (Seedling Emergence, Tier II) a

Species

Plant Height Dry Weight Survival

NOAEC

(lbs a.i./A)

IC25

(lbs a.i./A)

NOAEC

(lbs a.i./A)

IC25

(lbs a.i./A)

NOAEC

(lbs a.i./A)

EC25

(lbs a.i./A)

Monocot

Corn (Zea mays) 0.019 0.47 0.019 0.026 1.5 2.5

Onion (Allium cepa) 0.019 0.11 0.019 0.031 0.17 0.15

Ryegrass (Lolium perenne) 0.019 0.071 0.019 0.042 0.51 0.45

Oat (Avena sativa) 0.019 0.10 0.019 0.038 0.17 0.34

Dicot

Cucumber (Cucumis sativus) 0.019 0.046 0.0063 0.020 0.064 0.076

Cabbage (Brassica oleracea) 0.006 0.012 0.019 0.038 0.019 >0.019

Lettuce (Lactuca sativa) 0.019 0.041 0.0021 0.006 0.019 0.031

Radish (Raphanus sativus) 0.057 0.010 0.019 0.045 0.11 0.21

Soybean (Glycine max) 0.17 0.24 0.019 0.069 1.5 >1.5

Tomato (Solanum lycopersicum) 0.019 0.090 0.019 0.033 0.17 0.16

a MRID 42718802. Test material was the technical, 97.2% a.i. Study classified as Supplemental.
Page 42 of 43

Toxicity of Fluometuron to Nontarget Terrestrial Plants (Vegetative Vigor, Tier II) a

Species

Plant Height Dry Weight Survival

NOAEC

(lbs a.i./A)

EC25

(lbs a.i./A)

NOAEC

(lbs a.i./A)

EC25

(lbs a.i./A)

NOAEC

(lbs a.i./A)

EC25

(lbs a.i./A)

Monocot

Corn (Zea mays) 0.057 0.29 0.057 0.086 0.51 1.3

Onion (Allium cepa) 0.019 0.10 0.019 0.056 0.51 0.43*

Ryegrass (Lolium perenne) 0.057 0.11 0.019 0.051 0.51 0.43*

Oat (Avena sativa) 0.019 0.078 0.019 0.035 0.17 0.12*

Dicot

Cucumber (Cucumis sativus) 0.019 0.087 0.0021 0.0088 0.057 0.10

Cabbage (Brassica oleracea) 0.019 0.065 0.0063 0.010 0.019 >0.019

Lettuce (Lactuca sativa) 0.0063 0.087 0.0063 0.014 0.0063 0.11

Radish (Raphanus sativus) 0.019 0.26 0.019 0.014 0.019 0.39

Soybean (Glycine max) 0.019 0.072 0.019 0.31 0.17 0.29

Tomato (Solanum lycopersicum) 0.019 0.086 0.019 0.026 0.17 0.12*

a MRID 42718803. Test material was the technical, 97.2% a.i. Study classified as Supplemental.

* Estimated EC25 endpoint was less than the NOAEC. Reviewer did not re-calculate as survival was not the most 

sensitive endpoint.
Page 43 of 43

Toxicity of Fluometuron to Aquatic Plants

Species % a.i. Endpoint 

(mg ai/L) Effects MRID (Study Classification)

Duckweed

(Lemna gibba)

97.5

IC50 = 0.59

NOAEC not 

determined

Frond number was 

measured endpoint 

(14-day test)

42564102 (supplemental, 

solvent effect, no definitive 

NOAEC)

96.4

IC50 = 0.22

NOAEC = 0.115

Frond number was 

measured endpoint

(14-day test)

43421601 (supplemental, 

fewer than recommended 

initial number of fronds)

Green algae

(Selenastrum 

capricornatum)

97.5 IC50 = 0.306

NOAEC = 0.180

Cell density was 

measured endpoint 

(120 hour test)

43025601 (supplemental, 

solvent effect)

97.2

IC50 = 0.030

NOAEC < 0.007

IC05 = 0.0016

Cell density was 

measured endpoint 

(120 hour test)

42498007 (supplemental, no 

definitive NOAEC)

Freshwater 

diatom, 

Nitzschia palea

97.5 IC50 = 0.312

NOAEC = 0.107

Cell density was 

measured endpoint 

(120 hour test)

42568502 (acceptable)

Marine diatom,

Skeletonema 

costatum

93.4 IC50 = 0.62

NOAEC = 0.41

Cell density

was measured endpoint 

(96 hour test)

42564101 (supplemental, 

solvent effect)

Cyanobacteria, 

Anabaena flosaquae

97.5

IC50 = 0.29

NOAEC = 0.22

Cell density was 

measured endpoint 

(120 hour test)

42568503* (supplemental, 

solvent effect)

97.5 IC50 = 0.13

NOAEC = 0.07

Cell density was 

measured endpoint 

(120 hour test)

43421602 (acceptable)

* Please refer to the DER for MRID 42568503. Same study also submitted to the Agency and reviewed as MRID 

42564103; however, the DER for MRID 42564103 contains errors.