2

Problem Formulation for the Environmental Fate,

Ecological Risk, Endangered Species, and Drinking 

Water Exposure Assessments in Support of the 

Registration Review of Bromoxynil and Bromoxynil 

Esters

CAS Registry Numbers: 1689-84-5, 1689-99-2, 3861-41-4

PC Codes: 035301, 035302, 128920

DP Barcode: 406427

Prepared by:

N.E. Federoff, Wildlife Biologist

Elyssa Gelmann, Fate Scientist

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch II

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Reviewed by:

Kristina Garber, Senior Biologist

R. David Jones, Ph.D., Senior Agronomist

Brian Anderson, Branch Chief

January 22, 2013
3

TABLE OF CONTENTS

1. INTRODUCTION .................................................................................................................. 4

2. CONCLUSIONS FROM PREVIOUS ASSESSMENTS....................................................... 4

2.1. Ecological Risk Assessments........................................................................................... 4

2.2. Drinking Water Exposure Assessments........................................................................... 5

2.3. Clean Water Act Programs............................................................................................... 5

3. ENVIRONMENTAL FATE AND TRANSPORT................................................................. 5

3.1. Transformation Products.................................................................................................. 8

4. RECEPTORS........................................................................................................................ 13

4.1. Effects to Terrestrial Species.......................................................................................... 14

4.2. Effects to Aquatic Species.............................................................................................. 16

4.3. Ecological Incidents....................................................................................................... 17

5. EXPOSURE PATHWAYS OF CONCERN ........................................................................ 19

6. ANALYSIS PLAN ............................................................................................................... 20

6.1. Stressors of Concern....................................................................................................... 20

6.2. Measures of Exposure .................................................................................................... 20

6.3. Measures of Effect ......................................................................................................... 22

6.4. Endangered Species Assessments.................................................................................. 22

6.5. Endocrine Disruptor Screening Program ....................................................................... 22

7. PRELIMINARY IDENTIFICATION OF DATA GAPS..................................................... 22

7.1. Environmental Fate ........................................................................................................ 23

7.2. Ecological Effects .......................................................................................................... 27

8. REFERENCES ..................................................................................................................... 30

Appendix A. Submitted Environmental Fate & Ecological Effects Studies ............................... 31

Appendix B. Ecological Effects Data .......................................................................................... 51

Appendix C. ECOSAR Toxicity Estimates................................................................................. 58

Appendix D. SIP and STIR Results............................................................................................. 60
4

1. INTRODUCTION

This problem formulation provides a plan for analyzing data relevant to bromoxynil and 

bromoxynil esters and for conducting environmental fate and ecological risk, endangered 

species, and drinking water assessments for all current, active registrations. Additionally, this 

problem formulation is intended to identify data gaps, uncertainties, and potential assumptions 

used to address those uncertainties, relative to characterizing the ecological risk associated with 

the registered uses of bromoxynil and its esters.

Bromoxynil is a selective contact foliage-applied herbicide used to control a variety of grasses 

and broadleaf weeds. Bromoxynil inhibits photosynthetic electron transport and also uncouples 

oxidative phosphorylation in mitochondria, thereby stopping energy production and negatively 

affecting plant respiration. End use products are formulated with bromoxynil esters, which 

quickly break down to bromoxynil following application.

Bromoxynil was first registered in the United States in 1965 for use as an herbicide to control 

grassy and broadleaf weeds on wheat and barley. Bromoxynil agricultural crop use sites now 

include: vegetable, fruit, and seed crops (e.g., flax, spearmint, peppermint, garlic/onions, sweet 

corn, pop corn); food and feed crops (e.g., alfalfa, fallow land, cotton, grasses); and grain crops 

(e.g., field corn, flax, barley, oats, rye, triticale, wheat, sorghum, proso millet). Non-agricultural

uses include: fencerows, commercial and industrial lawns, conservation reserve program land, 

drainage ditch banks, ornamental herbaceous plants, ornamental (non-residential) lawns, golf 

course turf, grass seed production, sod farms, railroad and roadside rights of way, vacant lots, 

and outdoor industrial areas. Bromoxynil and its esters are formulated as wettable powder,

emulsifiable concentrate, and soluble concentrate. Applications may be made by air, 

chemigation, and ground boom. The maximum single application rates range from 0.09 lb 

ai/acre to 1.8 lb ai/acre with multiple applications allowed, up to 2.5 lb ai/acre per year for some 

crops. There are no residential uses for this herbicide (USEPA, 2012). 

2. CONCLUSIONS FROM PREVIOUS ASSESSMENTS

2.1. Ecological Risk Assessments

In December of 1998, the Agency issued a Reregistration Eligibility Decision (RED) for 

bromoxynil (USEPA, 1998). In November of 2004, the Agency released an analysis of risks to 

endangered and threatened salmon and steelhead from exposure to bromoxynil (USEPA, 2004a).

The assessment concluded that bromoxynil may affect salmon and steelhead food in high-use 

areas and may adversely modify their critical habitat. Most recently, an assessment was 

conducted for a Section 3 New Use registration on grass grown for seed and sorghum in 2010 

(USEPA, 2010b). In the 2010 assessment, data for bromoxynil octanoate were used to assess 

acute exposure and data for bromoxynil were used to assess chronic exposure. The major 

ecological risk conclusions from these assessments are summarized in Table 1. 
5

Table 1. Summary of Taxa at Risk Identified for Bromoxynil in Previous Assessments

Type of 

Risk Birds Mammals TerrestrialInverts

Terrestrial

Plants Fish Aquatic Inverts

Aquatic 

Plants

Acute Yes* Yes* No Yes Yes* Yes Yes*

Chronic Yes Yes NA NA No Yes NA

*Risk to federally listed threatened or endangered species only

NA = Not Applicable

2.2. Drinking Water Exposure Assessments

The most recent drinking water assessment for bromoxynil was completed in 2010 for a new use

on grass grown for seed and sorghum (USEPA, 2010a). The assessment was for a mixture of 

bromoxynil octanoate and bromoxynil heptanoate but all calculations were performed using

bromoxynil fate data due to rapid degradation of both esters to the phenol. The assessment also 

updated drinking water values from a 1997 assessment of bromoxynil use on cotton (USEPA, 

1997). Maximum exposure estimates of bromoxynil were 11.5 μg/L (1-in-10-year peak) and 

0.19 μg/L (1-in-10-year annual mean) from sorghum use for surface water and 3.26 ng/L from 

cotton use for ground water.

The drinking water assessment for the RED relied on monitoring data from the United States 

Geological Survey (USGS) National Water Quality Program (NAQWA), "Pesticides in Ground 

Water Database" (USEPA, 1992), and PRZM-EXAMS modeling for the use of bromoxynil on 

cotton, the use scenario most vulnerable for movement of bromoxynil to surface water (USEPA, 

1998). NAQWA ground water data are available for 1993-1994 and included one detection 

(concentration not specified) of bromoxynil from 2,245 samples. Maximum modeled exposure 

estimates of bromoxynil in surface water were 12.3 μg/L (1-in-10-year peak) and 0.24 μg/L (1-

in-10-year annual mean). Based on fate properties and monitoring data, ground water exposure 

was assumed to be negligible. The analysis resulted in no chronic or acute risk of concern to 

humans when using monitoring data or modeling data for the acute exposure and when using 

monitoring data for the chronic and cancer exposure.

2.3. Clean Water Act Programs

Bromoxynil and its esters are 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 bromoxynil or its esters. Aquatic benchmarks have 

been established for bromoxynil and its esters and are available at 

http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm. Any data submitted or 

otherwise located as part of the registration review process may be used to update aquatic life 

benchmarks if applicable. 

3. ENVIRONMENTAL FATE AND TRANSPORT

Bromoxynil, also referred to as bromoxynil phenol, and two bromoxynil esters, bromoxynil 

octanoate and bromoxynil heptanoate, are all registered with the Agency as active ingredients. 

Details on these three structures can be found in Table 2 below. A third ester, bromoxynil 

butyrate (PC 035303), was previously registered with the Agency but currently has no active 
6

registrations and is therefore not addressed in this document. Fate data are available with which 

to assess bromoxynil and bromoxynil octanoate. The heptanoate ester was registered based on 

bridging of bromoxynil octanoate fate data and therefore no fate data are available for the 

heptanoate ester. Chemical properties for the heptanoate ester, including solubility, vapor 

pressure, and KOW, are assumed to be similar to the octanoate ester (MRID 41324901). 

Chemical properties and environmental fate data for bromoxynil are summarized in Table 3 and 

data for bromoxynil octanoate are summarized in Table 4.

Bromoxynil octanoate readily hydrolyzes to bromoxynil (t1⁄2 = 11.5-28 d at pH 7). Bromoxynil 

octanoate is slightly mobile (Koc = 1,003 L/kgOC) and non-persistent. It dissipates in the 

environment by abiotic hydrolysis, photolytic degradation, and microbially mediated metabolism 

in both the aerobic and anaerobic environments. Bromoxynil octanoate rapidly degrades to 

bromoxynil in aerobic terrestrial and aquatic environments (t1/2 =2 and 0.6 d, respectively). 

Bromoxynil octanoate residues dissipated with half-lives of 1 to 14 days in a terrestrial field 

dissipation study and residues were not detected below 15 cm soil depth. 

There is no evidence that bromoxynil degrades by abiotic hydrolysis at any measured pH (MRID 

41892901). Residues of bromoxynil appear to be moderately mobile with three out of four soilwater partitioning coefficients (Kd) less than three and apparent correlation with the soil organic 

carbon content (KOCs between 100 and 240). Bromoxynil rapidly degrades in aerobic terrestrial 

environments (t1/2 =1.3-2.1 d). Surface water and ground water contamination may occur from 

bromoxynil, the common degradate of the ester formations. 

Table 2. Registered Active Ingredients Addressed in this Problem Formulation

Common 

Name Chemical Name PC Code &CAS No.

Formula & 

MW Structure

Bromoxynil 3,5-dibromo-4-

hydroxybenzonitrile 

035301 

1689-84-5

C7H3Br2NO

276.91 g/mol

Bromoxynil 

octanoate

2,6-dibromo-4-

cyanophenyl 

octanoate

035302 

1689-99-2

C15H17Br2NO2

403.11 g/mol

Bromoxynil 

heptanoate

2,6-dibromo-4-

cyanophenyl 

heptanoate

128920 

56634-95-8

C14H15Br2NO2

389.08 g/mol

Table 3. Chemical Properties and Environmental Fate Parameters of Bromoxynil 

Parameter Value1 Source

Selected Physical/Chemical Parameters

Vapor pressure (20°C) 2.5 x 10-6 torr, volatilization not a major 

source of dissipation

MRID 42130101

Aqueous solubility (25°C) 211 mg/L, high solubility MRID 42087401
7

Parameter Value1 Source

Henry’s Law Constant (20°C) 4.32 x 10-9 atm-m3/mol, unlikely to 

volatilize from water or wet surfaces

(Calculated)

Log octanol-to-water partition coefficient

(log KOW)

1.04, low hydrophobicity MRID 42333601

Log Dissociation constant (pKa) 3.86 MRID 42066401

Persistence

Hydrolysis half-life (23-25°C) stable at pH 5, 7, and 9 MRIDs 00130424 and 

41892901

Soil photolysis half-life (25°C) No substantial degradation via photolysis on 

soil observed

MRID 41920402

Aerobic soil metabolism half-life (21°C) 2.1 d, sandy loam

1.3 d, loam

MRID 00142958

Anaerobic aquatic metabolism half-life 

(20°C)

4.5 d (calculated using degradate data from 

the anaerobic aquatic metabolism study on 

bromoxynil octanoate)

USEPA, 1997

(data from MRID 

41892902/ 42234303)

Mobility

Soil-water distribution coefficient (Kd) 1.40 L/kg, loamy sand

1.60 L/kg, clay loam

2.90 L/kg, loam

12.54 L/kg, sandy loam

Binding correlated with organic carbon 

content 

MRID 00110429

Organic carbon-normalized distribution 

coefficients (KOC)

107.7 L/kgOC, loamy sand

193.3 L/kgOC, loam

228.6 L/kgOC, clay loam

238.9 L/kgOC, sandy loam

Moderately mobile

MRID 00110429

Un-aged soil column leaching sandy loam & loam: 0.1-0.7% in leachate, 

majority in top 8 & 12 cm in soil columns

loamy sand & clay loam: 2.0-6.4% in 

leachate, distributed throughout columns 

MRID 00139590

Aged soil column leaching sandy loam & loam: 0.1-0.3% in leachate, 

majority in top 12 & 6 cm of soil columns

loamy sand & clay loam: 3.8-13.0% in 

leachate, distributed throughout columns

MRID 00139590

1 Half-lives were calculated using the single-first order equation and nonlinear regression, unless otherwise 

specified. 

Table 4. Chemical Properties and Environmental Fate Parameters of Bromoxynil Octanoate1

Parameter Value2 Source

Selected Physical/Chemical Parameters

Vapor pressure (20°C) 1.39 x 10-6 torr, volatilization not a major 

route of dissipation

MRID 41240104 

Aqueous solubility (25°C) 3 mg/L, high solubility

Heptanoate: 1.87 mg/L

MRID 41240103 

MRID 42296401
8

Parameter Value2 Source

Henry’s Law Constant (20°C) 2.46 x 10-7 atm-m3/mol, unlikely to 

volatilize from water or wet surfaces

(Calculated)

Log octanol-to-water partition coefficient

(log KOW)

5.06, high hydrophobicity MRID 00150216

Log Dissociation constant (pKa) 4.28 MRID 44906003

Persistence

Hydrolysis half-life (23-25°C) pH 5: 34.1-43 d

pH 7: 11.5-28 d

pH 9: 1.5-1.7 d

MRIDs 00130424 and 

41892901

Aqueous photolysis half-life (25°C) 4.6 d, pH 5, corrected for dark control MRID 41920401/ 42234301

Soil photolysis half-life (25°C) 55 d, sandy loam, corrected for dark control MRID 41920402

Aerobic soil metabolism half-life (21°C) 2 d, sandy loam MRID 41897701/ 42234302

Aerobic aquatic metabolism half-life 

(25°C)

0.6 d in total system, sandy loam sediment MRID 42364901

Anaerobic aquatic metabolism half-life 

(20°C)

3.7 d in total system, sandy loam sediment MRID 41892902/ 42234303

Mobility

Soil-water distribution coefficient (Kd) 7.0 L/kg, sandy loam MRID 00116557/ 00114338 

Organic carbon-normalized distribution 

coefficients (KOC)

1,003 L/kgOC, sandy loam

Slightly mobile

MRID 00116557/ 0114338

Un-aged soil column leaching sandy loam & loam: 2.7-18.2% in leachate

sand: 52.4-58.9% in leachate 

MRID 42271101

Aged soil column leaching sandy loam & loam: 3.6-26.8% in leachate

sand: 56.0-58.5% in leachate 

MRID 42271101/ 43775001

Field Dissipation

Terrestrial field dissipation half-life; 

leaching depth

14 d (0-6” depth; CA Sorrento silt loam); 

leached to 6”

1 d (0-6” depth; NC Norfolk sandy loam); 

leached to 6”

MRID 41653701/ 43071001

Fish Bioconcentration

Fish bioconcentration factors (steadystate); depuration rate63 (edible), 400 (inedible), 230 (whole); 

85-97% depuration in 14 days; 79% as 

degradate bromoxynil in fish tissue

MRID 42277301a/ 

42277301b

1 In previous assessments, the chemical properties and environmental fate parameters for bromoxynil heptanoate 

were assumed to be the same as those for bromoxynil octanoate.

2 Half-lives were calculated using the single-first order equation and nonlinear regression, unless otherwise 

specified. 

3.1. Transformation Products

Eight major degradates of bromoxynil octanoate, including bromoxynil, were identified in the 

environmental fate studies. Table 5 summarizes the transformation products of bromoxynil 
9

octanoate and their maximum amounts formed. Bromoxynil is a major degradate in hydrolysis, 

soil photolysis, aerobic soil metabolism, and aerobic and anaerobic aquatic metabolism—all 

pathways studied with the exception of aqueous photolysis. 

Two major degradates of bromoxynil were identified in aerobic soil metabolism pathways and 

are summarized in Table 6. 

No degradates of concern were identified in the RED, as the degradates were not considered at 

that time. However, the degradates are now being considered for the registration review risk 

assessment. As discussed in Section 6.1, several aerobic soil and aquatic metabolites will be 

included in the ecological risk assessment unless data are submitted to allow EFED to exclude 

the degradates from the analysis. 
10

Table 5. Bromoxynil Octanoate and Its Major Environmental Degradates

Code Name/ Synonym Chemical Name Chemical Structure Study Type Ref.

(MRID)

Maximum 

%AR (day)

Final %AR 

(study length)1

PARENT

Bromoxynil octanoate 2,6-dibromo-4-

cyanophenyl octanoate 

CAS No.: 1689-99-2

Formula: C15H17Br2NO2

MW: 403.11 g/mol

MAJOR TRANSFORMATION PRODUCTS

Bromoxynil* 3,5-dibromo-4-

hydroxybenzonitrile 

CAS No.: 1689-84-5

Formula: C7H3Br2NO

MW: 276.91 g/mol

Hydrolysis pH 5

41892901

35% (30 d) 35% (30 d)

Hydrolysis pH 7 77% (30 d) 77% (30 d)

Hydrolysis pH 9 76% (30 d) 76% (30 d)

Soil photolysis 41920402 88.4% (21 d) 85.5% (30 d)

Aerobic Soil 

Metabolism: 

Sandy Loam

41897701/

42234302 48.09% (4 d) 6.77% (90 d)

Aerobic Aquatic 

Metabolism 42364901 78.77% (2 d) 4.56% (30 d)

Anaerobic 

Aquatic 

Metabolism

41892902/ 

42234303 48.48% (7 d) n.d. (182 d)

4-hydroxybenzonitrile* CAS No.: 767-00-0

Formula: C7H5NO

MW: 119.12 g/mol

Aerobic Aquatic 

Metabolism 42364901 25.60% (14 d) 3.77 (30 d)

Anaerobic 

Aquatic 

Metabolism

41892902/ 

42234303 46.32% (21 d) 0.14% (182 d)

4-cyano-2-

bromophenyl octanoate

Formula: 

C15H18BrNO2

MW: 324.21 g/mol

Aqueous 

Photolysis 41920401 14.9% (3 d) <0.1% (30 d)

3-bromo-4-

hydroxybenzonitrile*

CAS No.: 2315-86-8

Formula: C7H4BrNO

MW: 198.02 g/mol

Aerobic Aquatic 

Metabolism 42364901 12.10% (7 d) n.d. (30 d)

Anaerobic 

Aquatic 

Metabolism

41892902/ 

42234303 3.65% (28 d) n.d. (182 d)
11

Code Name/ Synonym Chemical Name Chemical Structure Study Type Ref.

(MRID)

Maximum 

%AR (day)

Final %AR 

(study length)1

3,5-dibromo-4-

hydroxybenzoic acid*,2

CAS No.: 3337-62-0

Formula: C7H4Br2O3

MW: 295.91 g/mol

Aerobic Aquatic 

Metabolism 42364901 12.10% (30 d) 12.10% (30 d)

3,5-dibromo-dihydroxycyclohexadienylnitrile

Formula: C7H3Br2NO2

MW: 292.91 g/mol

Hydrolysis pH 5

41892901

10.4% (21 d) 7.0% (30 d)

Hydrolysis pH 7 10.7% (21 d) 6.3% (30 d)

Hydrolysis pH 9 7.9% (1.25 d) 2.4% (5 d)

Phenol CAS No.: 108-95-2

Formula: C6H5OH

MW: 94.11 g/mol

Aqueous 

Photolysis 41920401 57.6% (30 d) 57.6% (30 d)

Phenyl carbamate CAS No.: 622-46-8

Formula: C7H7NO2

MW: 137.14 g/mol

Aqueous 

Photolysis 41920401 29.7% (21 d) 3.6% (30 d)

* Potential degradate of concern 1 n.d. = not detected

2 Degradate of bromoxynil
12

Table 6. Bromoxynil and Its Major Environmental Degradates

Code Name/ Synonym Chemical Name Chemical Structure Study Type Ref.

(MRID)

Maximum 

%AR (day)

Final %AR 

(study length)

PARENT

Bromoxynil 3,5-dibromo-4-

hydroxybenzonitrile 

CAS No.: 1689-84-5

Formula: C7H3Br2NO

MW: 276.91 g/mol

MAJOR TRANSFORMATION PRODUCTS

3,5-dibromo-4-

hydroxybenzamide*

CAS No.: 3037-56-7

Formula: C7H5Br2NO2

MW: 294.93 g/mol

Aerobic Soil 

Metabolism: 

Sandy Loam

00142958

20.9% (3 hr) 1.4% (28 d)

Aerobic Soil 

Metabolism: 

Loam

21.6% (3 hr) 1.0% (28 d)

3,5-dibromo-4-

hydroxybenzoic acid*

CAS No.: 3337-62-0

Formula: C7H4Br2O3

MW: 295.91 g/mol

Aerobic Soil 

Metabolism: 

Sandy Loam 00142958

34.8% (1 d) 0.4% (28 d)

Aerobic Soil 

Metabolism: 

Loam

16.1% (1 d) 0.3% (28 d)

* Potential degradate of concern 
13

4. RECEPTORS

Consistent with the process described in the Agency’s Overview Document (USEPA, 2004b), 

the risk assessment for bromoxynil will rely on a surrogate species approach. Normally the most 

sensitive endpoint for each taxon is used for RQ calculations. For the acute risk assessment here, 

a single “most sensitive endpoint” will be selected from the combined databases of bromoxynil, 

bromoxynil octanoate, and bromoxynil heptanoate. Only bromoxynil toxicity will be used to 

assess chronic risk because the esters are expected to break down quickly to bromoxynil in the 

environment. Table 7 summarizes this approach. Assessment endpoints include direct toxic 

effects on the survival, reproduction, and growth of terrestrial and aquatic life, as well as indirect 

effects, such as reduction in prey base and/or modification of habitat. The evaluated taxa include 

freshwater fish, freshwater aquatic invertebrates, birds, small mammals, terrestrial invertebrates, 

algae, and terrestrial plants. 

Table 7. Relevant Toxicity Data for Assessment of Bromoxynil and Bromoxynil Esters

Chemical Form Terrestrial Animals Terrestrial 

Plants

Aquatic Organisms

Acute Chronic Acute Chronic

Bromoxynil X X X X X

Octanoate ester X -- X X --

Heptanoate ester X -- X X --

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

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

Other sources of information, including use of the acute probit dose response relationship to 

establish the probability of an individual effect and reviews of the Ecological Incident 

Information System (EIIS), are conducted to further refine the characterization of potential 

ecological effects associated with exposure to bromoxynil. A summary of the available 

ecotoxicity and incident information for bromoxynil is provided below. 

Table 8 provides a summary of the most sensitive ecotoxicity endpoints submitted to the 

Agency. A detailed summary of available toxicity data is provided in Appendix B. Ecological 

Effects Data.

Table 8. Measures of Ecological Effects for Bromoxynil and Bromoxynil Esters

Assessment Endpoint Selected Surrogate Species and Measure of Ecological 

Effect Source

Birds

Acute

Bobwhite quail oral LD50 = 148 mg ai/kg-bw octanoate MRID 00248229

Bobwhite quail subacute dietary LC50 = 1150 ppm octanoate MRID 00248229

Chronic Mallard duck NOAEC/LOAEC = 102 ppm/340 ppm 

octanoate

MRID 42004102

Mammals Acute Rat LD50 = 81/93 mg ai/kg bw M/F bromoxynil

Rat LD50 = 400/238 mg ai/kg bw M/F octanoate

MRID 00124758

MRID 00124112

Chronic Rat NOAEL/LOAEL = 1.5/5.0 mg/kg/day bromoxynil MRID 00064815

Freshwater Acute Bluegill sunfish 96-hr LC50 = 0.029 ppm ai 94.8% heptanoate MRID 43059601
14

Assessment Endpoint Selected Surrogate Species and Measure of Ecological 

Effect Source

fish Chronic Fathead minnow NOAEC = 0.018 ppm; LOAEC = 0.039

ppm 97.2% octanoate

MRID 41928301

Freshwater 

invertebrates Acute

Daphnia acute 48-hr EC50 = 0.031 ppm ai 94.8% heptanoate

Daphnia acute 48-hr EC50 = 0.011 ppm ai 36.6% octanoate

MRID 43059602

MRID 00247924

Chronic Daphnia NOAEC = 0.0025 ppm ai; LOAEC = 0.0059 ppm 

ai 97.2% octanoate

Daphnia NOAEC = 0.0026 ppm ai; LOAEC = 0.0053 ppm ai 

60% octanoate

MRID 41928302

MRID 40111001

Estuarine/

marine fish

Acute Sheepshead minnow LC50 = 0.170 ppm ai 97.2% octanoate MRID 42250601

Chronic No data

Estuarine/

marine 

invertebrates

Acute Mysid LC50 = 0.065 ppm ai 94.9% octanoate

Oyster 96-hr EC50 = 0.155 ppm ai 92.4% octanoate

MRID 43487601

MRID 42244501

Chronic No data

Terrestrial 

plants

Survival and 

growth

Seedling emergence: EC25 = 0.014 lbs ai/A dicot lettuce

(shoot weight) and >0.45 lbs ai/A for all monocots tested 

(shoot length) 94.8% heptanoate

Vegetative vigor: EC25 = 0.011 lbs ai/A cabbage (shoot 

weight) and 0.19 lbs ai/A ryegrass (root weight) 94.8% 

heptanoate

Seedling emergence: EC25 = 0.12 lbs ai/A dicot tomato (shoot 

length) and <0.60 lbs ai/A for all monocots tested 

(emergence & shoot length) 33.58% octanoate

Vegetative vigor: EC25 = 0.017 lbs ai/A dicots cabbage & 

tomato (plant dry weight) and 0.37 lbs ai/A monocot onion 

(plant dry weight) 33.58% octanoate

MRID 43059603

MRID 43633701

Insects Acute 

contact

Acute contact LD50 = 14.5 μg/bee octanoate MRID 00018842

Aquatic plants NonvascularFreshwater diatom EC50 = 0.051 ppm ai 97.2% octanoate MRID 41606001

Vascular Lemna gibba EC50 = 0.219 ppm ai 94.8% heptanoate MRID 43059604

LD50 = Lethal dose to 50% of the test population; NOAEC = No observed adverse effect concentration; NOAEL = 

No observed adverse effect level; LC50 = Lethal concentration to 50% of the test population; EC50 = Effect 

concentration to 50% of the test population; IC50= concentration resulting in a 50% inhibition in the test population 

response (e.g., growth)

4.1. Effects to Terrestrial Species

Available terrestrial toxicity data are summarized below. Toxicity reference values are further 

characterized in Table 8 and Appendix B. Ecological Effects Data.
15

Avian 

Bromoxynil, heptanoate, and octanoate are moderately toxic to practically non-toxic to avian 

species on an acute oral basis and slightly toxic to avian species on a subacute dietary basis.

Bromoxynil octanoate can impair the reproduction of birds at dietary concentrations greater than 

102 ppm. Effects included number of eggs laid and set, number of viable embryos, number of 

live 3-week embryos, and lesions of old yolk peritonitis or regressing ovary. Avian reproduction 

studies with bromoxynil and bromoxynil heptanoate have not been submitted. 

Mammals

Bromoxynil, heptanoate, and octanoate are moderately toxic to small mammals on an acute oral 

basis. A rat acute oral LD50 study with bromoxynil resulted in an LD50 of 93 mg/kg for female 

rats and 81 mg/kg for male rats and a study with octanoate resulted in an LD50 of 238 mg/kg for 

female rats and 400 mg/kg for male rats. A study with heptanoate resulted in an LD50 of 292 

mg/kg for female rats and 362 mg/kg for male rats (MRID 41324902).

A three-generation Wistar rat reproduction study with technical grade bromoxynil reported a 

NOAEL of 1.5 mg/kg/day (30 ppm in food) and a LOAEL of 5 mg/kg/day (100 ppm in food) 

based on decreased body weight in F1 and F2 parents. The NOAEL for toxicity in offspring was 

5 mg/kg/day and the LOAEL was 15 mg/kg/day (300 ppm in food) also based on decreased body 

weight, particularly in the F2 generation. No reproductive toxicity was observed at any dose 

level.

A two-generation rat reproduction study (MRID 41149301) with technical grade bromoxynil 

reported a NOAEL of 4 mg/kg/day (50 ppm in food) and a LOAEL of 21 mg/kg/day (250 ppm 

in food) based on decreased body weight gain in F0 and F1 females before mating, during 

gestation and lactation and at study termination. In addition, possibly increased liver weights 

were observed in both male and female adults. The NOAEL and LOAEL for toxicity in 

offspring were the same as for toxicity in the parents, based on decreased body weight gain 

during lactation and delayed eye opening. No reproductive toxicity was observed in this study at 

any dose level. 

Beneficial Insects

A honeybee acute contact study with bromoxynil octanoate showed an LD50 of 14.5 μg ai/bee. 

There is sufficient information to characterize bromoxynil octanoate as practically nontoxic to 

bees. No additional data are available for bromoxynil or bromoxynil heptanoate.

Terrestrial Plants

The most sensitive EC25 values for non-target terrestrial plants are 0.014 lbs ai/A for seedling 

emergence and 0.011 lbs ai/A for vegetative vigor. Both values are for bromoxynil heptanoate 

effects on shoot weight. Data have also been submitted for bromoxynil octanoate, but not for 

bromoxynil. Toxicity data for terrestrial plants is typically requested for end use products and 

bromoxynil is not used in any currently registered end use products. It is expected that the 

bromoxynil esters would degrade to bromoxynil over the course of the submitted terrestrial plant 

studies.
16

4.2. Effects to Aquatic Species

Available aquatic toxicity data are summarized below. Toxicity reference values are further 

characterized in Table 8 and Appendix B. Ecological Effects Data

Fish: Acute Exposure

The results of the 96-hour acute toxicity studies indicate that bromoxynil octanoate and

heptanoate are very highly toxic, and bromoxynil is moderately toxic to freshwater fish. 

Bromoxynil octanoate is highly toxic to estuarine/marine fish on an acute basis. No 

estuarine/marine fish toxicity data are available for bromoxynil or bromoxynil heptanoate.

Fish: Chronic Exposure

The most sensitive chronic freshwater fish study that fulfills the guideline requirement for 

bromoxynil octanoate demonstrates a LOAEC of 18 ppb and a NOAEC of 39 ppb based on 

decreased larval growth, survival and embryo hatching success. No chronic freshwater fish data 

for bromoxynil or bromoxynil heptanoate have been submitted. No chronic data for 

estuarine/marine fish have been submitted for any of the three active ingredients.

The highest 60-day estimated environmental concentration (EEC) for bromoxynil, the value used 

to assess chronic exposure to fish, calculated in previous assessments is 1.50 ppb, or 0.00150

ppm (sorghum use, USEPA, 2010b). The most sensitive 96-hr bromoxynil LC50 for rainbow 

trout is 2.1 ppm (Acc. # 260441). Therefore, the NOAEC for rainbow trout would have to be 3 

orders of magnitude lower than the acute toxicity value to trigger a risk concern, based on a level 

of concern (LOC) of 1 for chronic risk. Table 9 shows ACRs (acute-to-chronic ratios) calculated 

for aquatic invertebrates for bromoxynil octanoate and dichlobenil, another herbicide in the same 

chemical class. Data are not sufficient to calculate ACRs for fish, but based on the ACRs for 

aquatic invertebrates it is unlikely that ACRs for fish would be ≥1,000. In addition, bromoxynil 

is considerably less toxic than the heptanoate and octanoate on an acute basis, and the available 

chronic data on the octanoate does not suggest that LOCs will be exceeded. Thus, we do not 

anticipate a chronic risk concern from fish exposed to bromoxynil.

Aquatic Invertebrates: Acute Exposure

Bromoxynil octanoate and heptanoate are very highly toxic, and bromoxynil is slightly toxic to 

freshwater aquatic invertebrates. Bromoxynil octanoate is highly toxic to oysters and very 

highly toxic to estuarine/marine shrimp on an acute basis. No acute data for estuarine/marine 

invertebrates have been submitted for bromoxynil or bromoxynil heptanoate.

Aquatic Invertebrates: Chronic Exposure

Both chronic aquatic invertebrate studies are supplemental, but taken together they satisfy the

guideline requirement for a life-cycle aquatic invertebrate study for bromoxynil octanoate. The 

results indicate that aquatic invertebrate reproductive impairment may occur at bromoxynil 

octanoate levels greater than 2.5 ppb. No chronic data for estuarine/marine invertebrates have

been submitted for any of the three active ingredients.

Using data from bromoxynil octanoate and dichlobenil, another nitrile herbicide, an ACR can be 

calculated to estimate the chronic toxicity of bromoxynil to aquatic invertebrates. These 
17

calculations, summarized in Table 9, use the most sensitive 48-hr bromoxynil EC50 for 

bromoxynil, which is 15.91 mg/L (MRID 00138087). 

Table 9. Acute to Chronic Ratio Calculations for Bromoxynil Toxicity to Freshwater Invertebrates

Test Substance Daphnia magna

48-hr EC50 (ppm)

Daphnia magna

21-d NOAEC (ppm)

ACR =

48h EC50/21-d NOAEC

Bromoxynil 

Calculated NOAEC 

(15.91 ppm / ACR)

Bromoxynil 

octanoate

0.011 0.0025 4.4 3.62

Dichlobenil 6.21 0.562 11.1 1.43 1 MRID 40775001. Burgess, D. (1987) Acute Flow-Through Toxicity of Dichlobenil to Daphnia magna: Project ID. 

36180. Unpublished study prepared by Analytical Bio-Chemical Laboratories, Inc. 24 p. 2 MRID 40775002, 42224201. Forbis, A. (1988) Chronic Toxicity of Dichlobenil to Daphnia magna Under FlowThrough Test Conditions: Project ID 36181. Unpublished study prepared by Analytical Bio-Chemical Laboratories, 

Inc. 30 p.

The most conservative bromoxynil NOAEC for Daphnia magna is 1.43 ppm, calculated using 

the ACR from dichlobenil. The highest 21-day bromoxynil EEC, the value used to assess 

chronic exposure to aquatic invertebrates, calculated in previous assessments is 3.26 ppb, or 

0.00326 ppm (sorghum use, USEPA, 2010b). Therefore, the NOAEC would have to be 3 orders 

of magnitude lower than the estimated value to trigger a risk concern, based on an LOC of 1 for 

chronic risk. Thus, we do not anticipate a chronic risk concern from aquatic invertebrate 

exposure to bromoxynil.

Aquatic Plants

No aquatic plant studies with bromoxynil have been submitted. Bromoxynil octanoate and 

heptanoate are highly to very highly toxic to algae and diatoms. Bromoxynil heptanoate is 

highly toxic to the vascular aquatic plant Lemna gibba. No data have been submitted with 

bromoxynil octanoate for vascular aquatic plants.

4.3. Ecological Incidents

The Ecological Incident Information System (EIIS) was searched and multiple plant incidents 

involving bromoxynil, bromoxynil octanoate, and bromoxynil heptanoate were reported. No 

incidents were reported in the EIIS for wildlife. No incidents were reported in the Avian 

Monitoring System (AIMS) database, which is administered by the American Bird Conservancy 

and contains publicly available data on reported avian incidents involving pesticides. See Table 

10 below for a list of incidents reported in the EIIS.

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

incidents caused by pesticides for a variety of reasons. Incident reports for non-target organisms 

typically provide information only on mortality events and plant damage. Sub-lethal effects in 

organisms such as abnormal behavior, reduced growth and/or impaired reproduction are rarely 

reported, except for phytotoxic effects in terrestrial plants. An absence of reports does not 

necessarily equate to an absence of incidents given the nature of the incident reporting.

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

bromoxynil octanoate, and bromoxynil heptanoate incidents to the Agency in aggregate reports. 
18

Registrants reported 42 minor plant incidents between 2000 and 2012. Unless additional 

information on these aggregated incidents becomes available, they will be assumed to be 

representative of registered uses of bromoxynil and its esters in the risk assessment.

Table 10. Incidents Reported in EIIS for Bromoxynil and Bromoxynil Esters

Incident # Date County State 

Certainty 

Code1

Legality 

Code2 Formul.

Appl. 

Method Total Magnitude

Agricultural Area

I012366-026 5/19/1998 Wexford MI 2 UN N/R Broadcast 82 acres

I008805-003 5/11/1999 Wabash IL 2 MA EC Broadcast 50% of 1/2 

I012089-004 8/7/2001 Merced CA 2 RU EC Broadcast 33 acres

Alfalfa

I013103-031 6/21/2002 Sherman NE 2 RU WP Broadcast 70 acres

Barley

I014123-022 5/29/2003 Morton NE 2 RU EC Broadcast 90 acres

I014123-016 5/29/2003 Stutsman ND 2 RU EC Broadcast 300 acres

I014123-017 5/29/2003 Morton NE 2 RU EC Broadcast 90 acres

I014216-033 6/2/2003 Wells ND 2 RU EC Unknown 180 acres

I014216-024 6/2/2003 La Moure ND 2 RU EC Broadcast 90 acres

I014216-010 6/2/2003 La Moure ND 2 RU EC Broadcast 90 acres

I014216-031 6/2/2003 Sheridan ND 2 RU EC Unknown 510 acres

I014216-028 6/2/2003 Sheridan ND 2 RU EC Broadcast 1300 acres

I014216-034 6/5/2003 Sheridan ND 2 RU EC Unknown 70% of 230 acres

I014216-030 6/12/2003 Sheridan ND 2 RU EC Unknown 130 acres

I014216-029 6/13/2003 Wells ND 2 RU EC Broadcast 420 acres

I014216-027 6/18/2003 Emmons ND 2 RU EC Broadcast 240 acres

I014216-025 6/18/2003 Emmons ND 2 RU EC Broadcast 360 acres

I015291-004 6/4/2004 Sheridan ND 2 RU EC Unknown 400 acres

I015291-006 6/11/2004 Stutsman ND 2 RU N/R Unknown 240 acres

I016328-032 5/21/2005 Cassia ID 2 RU EC Broadcast 149 acres

I016407-056 6/16/2005 Grant ND 2 M N/R Broadcast 32 acres

Corn

I010390-002 5/17/2000 Montgomery IL 3 RU EC Broadcast 11.3 acres

I010563-052 7/1/2000 Holt MO 2 RU EC Broadcast Unknown

I011723-083 5/21/2001 Macon IL 3 MA EC Broadcast Unknown

I011723-084 6/2/2001 ST Joseph IN 2 RU EC Broadcast Unknown

I011723-085 6/13/2001 Greeley KS 2 RU EC Broadcast ALL

I011723-086 6/14/2001 Decatur IN 2 RU N/R Broadcast ALL

I011723-087 6/21/2001 Miami IN 2 RU N/R Broadcast ALL

Corn, field

I017865-033 7/15/2006 Ogle IL 2 RU EC Broadcast 50 acres

I017865-032 7/15/2006 Ogle IL 2 RU EC Broadcast 62 acres

I012994-001 5/22/2002 Sussex VA 2 MA EC Broadcast 45 acres out of 85

I013430-025 6/21/2002 La Moure ND 2 MA EC Broadcast 

90 acres out of 

130

I013103-030 6/24/2002 Union IN 2 RU EC Broadcast 36 acres

I014216-026 6/12/2003 Emmons ND 2 RU EC Broadcast 160 acres

I014216-015 6/12/2003 Jackson MN 2 MA EC Broadcast 25 acres
19

Incident # Date County State 

Certainty 

Code1

Legality 

Code2 Formul.

Appl. 

Method Total Magnitude

I016595-038 7/14/2005 Scott IA 2 RU EC Broadcast 20 acres

I016662-027 8/26/2005 Washington IA 2 RU EC Broadcast 160 acres

Cotton

I014216-053 6/9/2003 Craighead AR 2 RU EC Band 400 acres

Lentils

I023302-022 8/2/2011 Hill MT 2 RU EC Broadcast 1500 acres

I023302-036 7/18/2011 Sheridan MT 1 RU EC Broadcast 64.8 acres

N/R

I012366-049 9/26/2001 CA 3 MA N/R Unknown 33 acres

I0211411017 6/29/2009 McCone MT 2 U EC Unknown N/R

Oat

I014216-032 6/2/2003 La Moure ND 2 RU EC Unknown 90 acres

I014216-011 6/2/2003 La Moure ND 2 RU EC Broadcast 90 acres

Onion

I014404-025 5/20/1991 Franklin WA 2 M Spray Spray N/R

I013563-003 5/3/1999 Fresno CA 2 MA Spray Unknown Unknown

Wheat

I001664-001 4/11/1994 Umatilla OR 2 MA EC Spray Unknown

I014216-043 6/6/2003 Pondera MT 2 RU EC Broadcast 500 acres

Wheat, spring

I014404-025 6/14/2006 GrandForksND 2 RU N/R Broadcast 60 acres

I013103-029 6/14/2002 Sheridan ND 2 RU N/R Broadcast 320 acres

I013430-022 7/8/2002 Foster ND 2 RU EC Unknown 165 acres

I013430-024 7/24/2002 Wells ND 3 RU EC Broadcast 360 of 670 acres

I013430-023 7/30/2002 Ward ND 3 RU EC Broadcast 200 acres

I014216-019 6/11/2003 Bowman ND 2 RU EC Broadcast 300 acres

I015291-021 6/3/2004 Hettinger ND 2 RU EC Broadcast 120 acres

I015291-022 6/3/2004 Hettinger ND 2 RU EC Unknown 120 acres

I016407-040 6/4/2005 Codington SD 2 RU EC Broadcast 69 acres

I023302-026 8/18/2011 Towner ND 2 RU EC Broadcast 125 of 245 acres

I023302-027 8/22/2011 Otter Tail MN 2 MI EC Broadcast 60 acres

Wheat, winter

I014216-042 6/6/2003 Pondera MT 2 RU EC Broadcast 400 acres 1 Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable. N/R=Not Reported 2 Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse (Intentional), U=Unknown

5. EXPOSURE PATHWAYS OF CONCERN

The environmental fate properties of bromoxynil and bromoxynil esters indicate that direct 

spray, spray drift, and runoff represent potential transport mechanisms of these chemicals to 

aquatic and terrestrial organisms. Drinking water and inhalation exposure pathways were 

screened using the SIP (Screening Imbibition Program) and STIR (Screening Tool for Inhalation 

Risk) screening methods (see Appendix D. SIP and STIR Results for details). Potential 

exposure pathways of concern were found for bromoxynil for drinking water but not for

inhalation. Neither drinking water nor inhalation was found to be a pathway of concern for 
20

bromoxynil octanoate. SIP and STIR are described in detail at:

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

6. ANALYSIS PLAN

6.1. Stressors of Concern

Ecological Risk Assessment

The stressors of ecological concern are bromoxynil octanoate, bromoxynil heptanoate, 

bromoxynil and some bromoxynil degradates. Bromoxynil is not used as an active ingredient in 

any registered products, but is a degradate of concern of the two esters. Bromoxynil and its 

esters have many degradates identified in terrestrial and aquatic studies (see Table 5 and Table 6

for details). No toxicity data are available for these degradates, however ECOSAR analyses 

indicate that they are all likely to have toxicity to aquatic organisms within one order of 

magnitude of their parent compound (see Appendix C. ECOSAR Toxicity Estimates). 

Therefore, the ecological risk assessment will incorporate a total residues of concern approach in 

which degradates are included in half-life calculations and assumed to have the same toxicity as 

their parent compound unless data are submitted that suggest degradates are not of concern. This 

approach will primarily affect the chronic exposure analysis, which will evaluate exposure to 

bromoxynil and its degradates only, and not the bromoxynil esters, which are expected to break

down to bromoxynil rapidly in the environment. The identified degradates that will be included 

in this approach include:

• Aerobic soil metabolites 3,5-dibromo-4-hydroxybenzoic acid and 3,5-dibromo-4-

hydroxybenzamide, and

• Aerobic aquatic metabolites 3,5-dibromo-4-hydroxybenzoic acid, 3-bromo-4-

hydroxybenzonitrile, and 4-hydroxybenzonitrile.

The ecological residues of concern may be re-evaluated pending the receipt and review of 

additional environmental fate and toxicity data for bromoxynil, bromoxynil esters, and their 

degradates. If aquatic toxicity data are provided demonstrating lower toxicity for any of the 

degradates identified above, the TTR approach may be adjusted to exclude these compounds. 

Drinking Water Assessment

The surface and ground water drinking water assessments conducted to support future human 

health risk assessments of bromoxynil and bromoxynil esters will incorporate model estimates of 

bromoxynil, the residue of concern. The drinking water residues of concern may be reevaluated 

pending the receipt and review of additional environmental fate and toxicity data for bromoxynil, 

bromoxynil esters, and their degradates.

6.2. Measures of Exposure

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

terrestrial organisms and to humans via drinking water as described at 

http://www.epa.gov/pesticides/science/models_db.htm. 
21

EFED will use application scenarios that result in maximum exposure scenarios for a given use 

for the risk assessment. Any absence of information on the labels that specifies the maximum 

single application rate, the application interval, the annual maximum rate allowed (lbs a.i./year), 

or application method will result in conservative assumptions as illustrated in the following 

examples:

• A maximum single application rate is specified with a re-application interval of 7 days 

without specifying a maximum annual rate may result in an assumption of 52 

applications with 7-day intervals;

• A label that does not preclude aerial applications will likely result in an assumption of 

aerial pesticide applications;

• A label that does not specify an application interval may result in assumptions of short 

application intervals such as 1- or 3-day intervals.

For the acute exposure analysis, each active ingredient (bromoxynil heptanoate and bromoxynil 

octanoate) will be modeled based on their maximum application rates. For aquatic 

environments, these acute exposure analyses will be conducted for both runoff and spray drift 

scenarios. Runoff analyses will be modeled in PRZM and EXAMS. If bridging of fate data for 

bromoxynil heptanoate to bromoxynil octanoate is determined to be an acceptable strategy, the 

model inputs for these esters will be identical and they will be modeled together. Standard spray 

drift assumptions will be applied for the spray drift analyses. 

Acceptability of the bridging strategy for the two esters will be determined based on hydrolysis 

and aerobic soil metabolism data. No fate data have yet been submitted for bromoxynil 

heptanoate. While the two esters are similar in structure, bromoxynil heptanoate may be more 

persistent than the octanoate form, as esters with side chains with odd numbers of carbon are 

often less metabolically active than compounds with even numbers of carbon of similar chain 

lengths. Therefore, the assumptions that bromoxynil heptanoate is behaving similarly to 

bromoxynil octanoate may not be conservative. Access to data on the rate of degradation of 

bromoxynil heptanoate would be beneficial in ensuring a more accurate depiction of how the 

compound breaks down. Due to toxicity of the esters to animals, understanding the behavior of 

the esters is important and assuming the two esters behave the same may or may not be 

reasonable.

For the chronic aquatic exposure analysis, only bromoxynil will be modeled because the esters 

are expected to break down quickly to bromoxynil in the environment. Alternatively, if 

appropriate tools are available, a formation-decline model may be used to determine more 

precise concentrations of bromoxynil esters, bromoxynil, and other degradates of concern over 

time. 

Screening level calculations have suggested that the drinking water exposure pathway may be 

significant for bromoxynil. This pathway may be further considered at the time of the risk 

assessment. Available monitoring data will be used to qualitatively characterize exposure and 

compare with modeling results. The Agency is aware of monitoring conducted by federal and 

state agencies and this information will be considered in the assessment to the extent that data on 

bromoxynil are available.
22

6.3. Measures of Effect

Toxicity data presented in Section 4 of this problem formulation will be used to calculate risk 

quotients, unless more sensitive reliable data are available at the time the risk assessment is 

conducted. Additional information submitted by the registrant or found in the open literature 

prior to conduct of the risk assessment will 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.

The available acute aquatic toxicity data indicate that bromoxynil octanoate and heptanoate are

orders of magnitude more toxic than bromoxynil to aquatic organisms and therefore the most 

sensitive toxicity data for the esters will be used in the risk assessment. However, due to rapid 

breakdown of the esters in the aquatic environment, bromoxynil will be the primary chronic 

exposure concern and therefore chronic toxicity data for bromoxynil will be used in the risk 

assessment. 

Available terrestrial toxicity data indicates that bromoxynil and its esters have similar toxicity to 

avian species. Therefore, the most sensitive acute endpoint available will be used in the risk 

assessment for terrestrial animals and molecular weight corrections will be made to application 

rates if the bromoxynil form assessed differs from the form tested. As in aquatic environments, 

bromoxynil esters rapidly break down to bromoxynil in terrestrial environments. Therefore, 

bromoxynil toxicity data will be used for the assessment of chronic risk. 

6.4. Endangered Species Assessments

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

Agency will evaluate risks to federally listed threatened and/or endangered (listed) species from 

registered uses of pesticides in registration review. These assessments will be conducted in 

accordance with standard EPA procedures and good scientific judgment. The process for 

evaluating potential risks to listed species is further described at 

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

6.5. Endocrine Disruptor Screening Program

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

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

7. PRELIMINARY IDENTIFICATION OF DATA GAPS

The Agency needs additional environmental fate and ecological effects studies prior to 

conducting the planned assessment. Data gaps, uncertainties and potential paths forward for the 

assessment of bromoxynil are described below. Table 11, Table 12, Table 13, and Table 14
23

identify 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.

7.1. Environmental Fate

Environmental fate data needs for bromoxynil, bromoxynil octanoate, and bromoxynil 

heptanoate are summarized in Table 11, Table 12, and Table 13, respectively. 

Table 11. Submitted Environmental Fate Data for Bromoxynil (PC 035301)

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are 

additional 

data needed 

to conduct 

risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data

835.2120 Hydrolysis 00130424 Acceptable No --

41892901 Acceptable

835.2240 Aqueous 

photolysis

(None) (Not applicable) Yes An aqueous photolysis study is 

required. In the absence of data, the 

Agency will assume that the 

compound is stable to photolysis in 

aqueous systems. The soil photolysis 

study demonstrated that bromoxynil 

does absorb visible light and therefore 

is susceptible to photolysis.

835.2410 Soil photolysis 40131001 Supplemental No MRID 40131001 lacked accounting 

of mass balance as well as 

characterization of the artificial light 

used. However, additional data will 

not change the outcome of the risk 

assessment. MRID 41920402

provides evidence that bromoxynil on 

soil does not undergo substantial 

degradation via photolysis.

835.4100 Aerobic soil 

metabolism

00142958/ 

00139589

Acceptable Yes Studies on 2 additional soils are 

required. In the absence of additional 

data, the Agency will use the upper 

90% confidence bound on the 2 

acceptable values to determine the 

half-life for modeling.

00114342 Invalid

00139587 Invalid

00139588 Invalid

835.4200 Anaerobic soil 

metabolism

00137773 Invalid No Additional data will not change the 

outcome of the risk assessment.

835.4300 Aerobic aquatic 

metabolism

(None) (Not applicable) Yes An aerobic aquatic metabolism study 

is required. In the absence of data, 

the Agency will multiply the aerobic 

soil metabolism half-life used for 

modeling by 2 to determine the 

aerobic aquatic metabolism half-life 

for modeling.

835.4400 Anaerobic aquatic 

metabolism

41892902/ 

42234303

Acceptable No --
24

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are 

additional 

data needed 

to conduct 

risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data

835.1230

835.1240

Adsorption/ 

desorption and 

leaching

00110429 Supplemental No --

00139590 Supplemental

00139590 Supplemental

835.1410 Volatility –

laboratory

(None) (Not applicable) No Volatilization is not expected to be a 

major route of dissipation.

835.6100 Terrestrial field 

dissipation

(None) (Not applicable) No --

Analytical method 

in soil

(None) (Not applicable)

835.6200 Aquatic field 

dissipation

(None) (Not applicable) Yes A chemistry method and successful 

independent validation are needed to 

Analytical method support aquatic toxicity studies.

in water

(None) (Not applicable)

850.1730 Fish 

bioconcentration

(None) (Not applicable) No The KOW indicates that bromoxynil

will not appreciably bioconcentrate in 

aquatic animals.

Table 12. Submitted Environmental Fate Data for Bromoxynil Octanoate (PC 035302)

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are 

additional 

data needed 

to conduct 

risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data

835.2120 Hydrolysis 00130424 Acceptable No --

41892901 Acceptable

00147767 Invalid

00117992 Invalid

00112871 Invalid

835.2240 Aqueous 

photolysis

41920401/ 

42234301

Acceptable No --

00145571 Invalid

00110421 Invalid

835.2410 Soil photolysis 41920402 Acceptable No --

835.4100 Aerobic soil 

metabolism

41897701/

42234302

Acceptable Yes Studies on 3 additional soils are 

required. In the absence of data, the 

Agency will multiply the value from 

MRID 41897701by 3 to determine 

the half-life for modeling.

835.4200 Anaerobic soil 

metabolism

(None) (Not applicable) No Additional data will not change the 

outcome of the risk assessment.

835.4300 Aerobic aquatic 

metabolism

42364901 Acceptable No --

835.4400 Anaerobic aquatic 

metabolism

41892902/ 

42234303

Acceptable No --
25

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are 

additional 

data needed 

to conduct 

risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data

41411001 Invalid

835.1230

835.1240

Adsorption/ 

desorption and 

leaching

00116557/ 

00114338

Supplemental No --

42271101/ 

43775001

Leaching: 

Acceptable 

Koc: 

Supplemental

835.1410 Volatility –

laboratory

(None) (Not applicable) No Volatilization is not expected to be a 

major route of dissipation.

835.6100 Terrestrial field 

dissipation

41653701/ 

43071001

Acceptable No Independent laboratory validation 

(ILV) is not needed to support the 

submitted field studies because they 

were submitted prior to 1996, the year 

the requirement for ILVs was 

introduced.

Analytical method

in soil

(None) (Not applicable)

835.6200 Aquatic field 

dissipation

(None) (Not applicable) Yes A chemistry method and successful 

independent validation are needed to 

Analytical method support aquatic toxicity studies.

in water

(None) (Not applicable)

850.1730 Fish 

bioconcentration

42277301a/ 

42277301b

Acceptable No --

Table 13. Submitted Environmental Fate Data for Bromoxynil Heptanoate (PC 128920)

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are

additional

data needed 

to conduct 

risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data

835.2120 Hydrolysis (None) (Not applicable) Yes A hydrolysis study is required to 

evaluate whether bridging of other 

fate data for bromoxynil heptanoate 

to bromoxynil octanoate is a 

justifiable strategy.

835.2240 Aqueous 

photolysis

(None) (Not applicable) Possibly, 

pending 

results of 

bridging 

analysis 

See footnote 1

835.2410 Soil photolysis (None) (Not applicable) Possibly, 

pending 

results of 

bridging 

analysis 

Additional data will not change the 

outcome of the risk assessment.
26

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are

additional

data needed 

to conduct 

risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data

835.4100 Aerobic soil 

metabolism

(None) (Not applicable) Yes An aerobic soil metabolism study is 

required to evaluate whether bridging 

of other fate data for bromoxynil 

heptanoate to bromoxynil octanoate is 

a justifiable strategy. The soil used 

must match a soil used for a 

bromoxynil octanoate aerobic soil 

metabolism study.

835.4200 Anaerobic soil 

metabolism

(None) (Not applicable) No Additional data will not change the 

outcome of the risk assessment.

835.4300 Aerobic aquatic 

metabolism

(None) (Not applicable) Possibly, 

pending 

results of 

bridging 

analysis 

See footnote 1

835.4400 Anaerobic aquatic 

metabolism

(None) (Not applicable) Possibly, 

pending 

results of 

bridging 

analysis 

See footnote 1

835.1230

835.1240

Adsorption/ 

desorption and 

leaching

(None) (Not applicable) Possibly, 

pending 

results of 

bridging 

analysis 

See footnote 1

835.1410 Volatility –

laboratory

(None) (Not applicable) No --

835.6100 Terrestrial field 

dissipation

(None) (Not applicable) No --

Analytical method 

in soil

(None) (Not applicable)

835.6200 Aquatic field 

dissipation

(None) (Not applicable) Yes A chemistry method and successful 

independent validation are needed to 

support aquatic toxicity studies. Analytical method 

in water

(None) (Not applicable)

850.1730 Fish 

bioconcentration

(None) (Not applicable) No --

1 If bridging is determined to be an acceptable strategy based on hydrolysis and aerobic soil metabolism study 

results, the bromoxynil octanoate half lives for aqueous photolysis, aerobic aquatic metabolism, and anaerobic 

aquatic metabolism as well as the bromoxynil Koc values will be used for aquatic modeling of bromoxynil 

heptanoate. If bridging is not determined to be an acceptable strategy, studies using bromoxynil heptanoate will be

needed.
27

7.2. Ecological Effects

The Agency needs additional data to assess acute and chronic hazard of bromoxynil to non-target 

species. In the previous RED assessment, toxicity data for bromoxynil octanoate were used to 

estimate risk (with the exception of vascular aquatic plants, which were assessed using 

bromoxynil heptanoate data). In most cases, bromoxynil octanoate was more toxic to test 

species than bromoxynil heptanoate. 

Terrestrial Toxicity Data Gaps

Since bromoxynil octanoate and heptanoate are moderately acutely toxic to other bird species

and small passerines may be even more susceptible due to their higher metabolic rates, an acute 

toxicity study on bromoxynil octanoate using a passerine species would reduce this uncertainty.

Avian reproduction studies with bromoxynil would reduce uncertainty in the avian risk 

assessment because bromoxynil is expected to be the more stable form of the chemical. Data on 

bromoxynil octanoate suggest that risk exceeds concern levels, and there are no data comparing 

the toxicity of the two available. If these studies are not submitted, the available endpoints from 

the studies using bromoxynil octanoate will be used for risk assessment.

Aquatic Toxicity Data Gaps

Because (1) available aquatic studies demonstrate acute toxicity endpoints of >1 ppm for 

bromoxynil (Appendix B. Ecological Effects Data) (2) chronic aquatic EECs are 3 orders of 

magnitude lower than these toxicity values, and (3) ACRs are not expected to be ≥1,000, chronic 

fish and invertebrate studies using bromoxynil are not needed to conduct the risk assessment. 

The guideline requirements for aquatic plant testing for bromoxynil octanoate are only partially 

fulfilled. Data to fulfill the guideline requirement for Lemna gibba (an aquatic macrophyte) have 

not been submitted. However, because bromoxynil octanoate and heptanoate break down into 

the more soluble bromoxynil in aquatic environments, a full suite of aquatic plant testing with 

bromoxynil should be submitted. 

Table 14 identifies studies by MRID that offer data for each guideline requirement, as well as 

study classifications and whether or not further data are needed in order to support risk 

assessment.

Table 14. Submitted Ecological Toxicity Data for Bromoxynil and Bromoxynil Esters

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies (MRID)

Study 

Classification

Are 

additional 

data needed 

to conduct 

risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data

850.2100 Avian Acute Oral MRID 00248229 Acceptable Yes An acute oral toxicity study using 

bromoxynil octanoate with a 

passerine species is needed (see 

explanation above)
28

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies (MRID)

Study 

Classification

Are 

additional 

data needed 

to conduct 

risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data

850.2200 Avian Subacute

Dietary

MRID 00248229

MRID 00248229

Acceptable

Acceptable

No --

850.2300 Avian 

Reproduction

MRID 42004101

MRID 42004102

Acceptable

Acceptable

Yes Avian reproduction studies with

bromoxynil should be submitted. If 

these studies are not submitted, the 

available endpoints for bromoxynil 

octanoate will be used for risk 

assessment. 

870.3100 Mammal Acute MRID 00124112 Acceptable No --

870.3800 Mammal 

Reproduction

MRID 41149301 Acceptable No --

850.3020 Honey Bee Acute 

Contact

MRID 00018842 Acceptable No --

850.1075 Freshwater Fish 

Acute

MRID 43059601

MRID 00264229

Acceptable

Acceptable

No --

850.1400 Freshwater Fish 

Chronic

MRID 41928301 Acceptable No Data are only available for bromoxynil 

octanoate, which is not expected to be 

long-lived in the environment. 

However, bromoxynil chronic toxicity 

is not expected at levels close to 

EECs. 

850.1010 Freshwater 

Invertebrate 

Acute

MRID 00247924 Acceptable No --

850.1300 Freshwater 

Invertebrate 

Chronic

MRID 41928302 Acceptable No Data are only available for bromoxynil 

octanoate, which is not expected to be 

long-lived in the environment. 

However, bromoxynil chronic toxicity 

is not expected at levels close to 

EECs.

850.1025 Estuarine/Marine

Fish Acute

MRID 42250601 Acceptable No --

850.1400 Estuarine/Marine

Fish Chronic

No data No Bromoxynil chronic toxicity is not 

expected at levels close to EECs.

850.1035 Estuarine/Marine 

Invertebrate 

Acute

MRID 43487601 Acceptable No --

850.1350 Estuarine/Marine

Invertebrate 

Chronic

No data No Bromoxynil chronic toxicity is not 

expected at levels close to EECs.

850.4100

850.4150

Terrestrial plants MRID43633701

MRID 43059603

Acceptable

Acceptable

No --
29

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies (MRID)

Study 

Classification

Are 

additional 

data needed 

to conduct 

risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data

850.4400

850.5400

Aquatic plants MRID 43059604

MRID 43059605

MRID 41606001

MRID 41606004

MRID 41606002

MRID 41606005

Acceptable

Acceptable

Acceptable

Acceptable

Acceptable

Supplemental

Yes Bromoxynil is expected to form 

rapidly in water from the esters. 

Therefore, a full suite of aquatic plant 

studies using bromoxynil should be 

submitted.
30

8. REFERENCES

USEPA. 2012. BEAD Chemical Profile for Registration Review: Bromoxynil and Its Esters 

(035301,035302, 035303, 128920). United States Environmental Protection Agency, Office 

of Pesticide Programs, Biological and Economic Analysis Division. Dated 10/3/2012.

USEPA. 2010a. Drinking water assessment for ground and aerial application of bromoxynil on 

grass grown for seed and ground application of sorghum. DP Barcode 374620. United States 

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

Effects Division. Dated 12/16/2010.

USEPA. 2010b. Ecological Risk Assessment for Aquatic Organisms and Aquatic Plants from the 

Proposed Registration of Bromoxynil for Ground and Aerial Application of Bromoxynil on 

Grass Grown for Seed and Ground Application of Sorghum. DP Barcode 374613. United 

States Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate 

and Effects Division. Dated 10/13/2010.

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

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

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

USEPA. 2004a. Bromoxynil: Analysis of Risks to Endangered and Threatened Salmon and 

Steelhead. United States Environmental Protection Agency, Office of Pesticide Programs, 

Environmental Fate and Effects Division. Dated 11/26/2004. Available at: 

http://www.epa.gov/oppfead1/endanger/litstatus/effects/#bromoxynil.

USEPA. 2004b. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs, United States Environmental Protection Agency (USEPA). Washington, DC: 

Government Printing Office. Available at: http://www.epa.gov/espp/consultation/ecoriskoverview.pdf.

USEPA. 1998. Reregistration Eligibility Decision (RED): Bromoxynil. United States 

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

Office of Pesticide Programs, Environmental Fate and Effects Division, Washington, DC. 

EPA738-R-98-013, December, 1998.

USEPA. 1997. Revised tier 2 EEC’s for bromoxynil octanoate as bromoxynil. United States 

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

Effects Division, Washington, DC. Dated 8/11/1997.

USEPA. 1992. Pesticides in Ground Water Database - A Compilation of Monitoring Studies: 

1971-1991, EPA 734-12-92-001, September, 1992.
31

Appendix A. Submitted Environmental Fate & Ecological Effects Studies

Environmental Fate Studies

MRID Citation

00110421 Collins, R.; Crouch, R.; Hart, M. (1965) Bromoxynil Octanoate, M & B 10731: Soil Persistence 

Studies: Report No. C.237. (Un- published study received Aug 17, 1982 under 359-564; prepared 

by May & Baker, Ltd., Eng., submitted by Rhone-Poulenc Chemical Co., Monmouth Junction, NJ; 

CDL:248115-B)

00110429 Williams, C.; Savage, E. (1982) Bromoxynil: Sorption Study with Four Soils. (Unpublished study 

received Aug 17, 1982 under 359-564; prepared by May & Baker, Ltd., Eng., submitted by 

Rhone-Poulenc Chemical Co., Monmouth Junction, NJ; CDL:248115-J)

00112871 Rowlinson, J. (1968) The Kinetics and Mechanism of the Hydrolysis of Some Esters of Ioxynil 

and Bromoxynil: Report Ref. PRG 143. (Unpublished study received Aug 26, 1982 under 359-

564; prepared by May & Baker Ltd., Eng., submitted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL:248234-A)

00114338 Parkins, M.; Heintzelman, R. (1981) A Comparison of the Adsorption Coefficient of Bromoxynil 

Octanoate and Bromoxynil Butyrate: File No. 30647. (Unpublished study received Sep 10, 1982 

under 264-204; submitted by Union carbide Agricultural Products Co., Inc., Research Triangle 

Park, NC; CDL:248308-C)

00114342 Smith, A. (1971) Degradation of bromoxynil in Regina heavy Clay. Weed Res. 11:276-282. (Also 

In unpublished submission received Sep 10, 1982 under 264-204; submitted by Union Carbide 

Agricultural Products Co., Inc., Research Triangle Park, NC; CDL: 248308-H)

00116557 Parkins, M.; Heintzelman, R. (1982) The Adsorption Coefficient of Bromoxynil Octanoate on 

Sandy Loam Soil: File No. 29831. (Un- published study received Aug 31, 1982 under 264-204; 

submitted by Union Carbide Agricultural Products Co., Inc., Research Triangle Park, NC; 

CDL:248228-B)

00117992 Merricks, D.; Cunningham, W. (1982) Hydrolysis of 14C-Bromoxynil Octanoate: Borriston 

Project No. 2203. Final rept. (Unpublished study received Nov 10, 1982 under 359-564; prepared 

by Borriston Laboratories, Inc., submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; 

CDL:248794-A)

00130424 Huhtanen, K.; Storm, J.; Hientzelman, R. (1983) Hydrolysis of Bromoxynil Octanoate and 

Butyrate in Aqueous Buffered Solutions: Project No. 854R10. (Unpublished study received Jul 1, 

1983 un- der 264-339; submitted by Union Carbide Agricultural Products Co., Inc., Research 

Triangle Park, NC; CDL:251058-A)

00137773 Williams, C.; Savage, E.; Godward, P.; et al. (1984) Bromoxynil: Metabolism in Soil under 

Anaerobic Conditions: Report Ref. AG.TECH.494. (Unpublished study received Mar 28, 1984 

under 264-204; prepared by May & Baker Ltd., Eng., submitted by Union Carbide Agricultural 

Products Co., Inc., Research Triangle Park, NC; CDL:252788-A)

00139587 Savage, E.; Kanji, F.; Hobbs, D. (1983) Bromoxynil: Rate of De- gradation in Four Soils under 

Aerobic Conditions (10 ?degrees| C): Ag.Tech. 308. (Unpublished study received Nov 17, 1983 

under 359-564; prepared by May & Baker, Ltd., Eng., submitted by Rhone-Poulenc, Inc., 

Monmouth Junction, NJ; CDL:252167-A)

00139588 Savage, E.; Smith, B. (1983) Bromoxynil: Rate of Degradation in Four Soils under Aerobic 

Conditions (Ambient Temperature): Ag.Tech. 307. (Unpublished study received Nov 17, 1983 

under 359-564; prepared by May & Baker, Ltd., Eng., submitted by Rhone-Poulenc, Inc., 

Monmouth Junction, NJ; CDL:252168-A)

00139589 Williams, C.; Godward, P.; Thurbon, J.; et al. (1983) Bromoxynil: Metabolism in Sandy-loam and 

Loam Soils under Aerobic Conditions: AG.Tech. 332. (Unpublished study received Nov 17, 1983 

under 359-564; prepared by May & Baker, Ltd., Eng., submitted by Rhone-Poulenc, Inc., 

Monmouth Junction, NJ; CDL:252169-A)

00139590 Williams, C.; Godward, P.; Savage, E. (1983) Bromoxynil: Leaching Study with Four Soils: 

AG.Tech. 334. (Unpublished study received Nov 17, 1983 under 359-564; prepared by May & 

Baker, Ltd., Eng., submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL:252170-A)
32

00142958 Williams, C. (1984) Bromoxynil: Metabolism in Sandy-loam and Loam Soils under Aerobic 

Conditions: Report Ref. AG.TECH.421 Unpublished study prepared by May & Baker Ltd. 221 p.

00145571 Huhtanen, K. (1985) Brominal: Photolytic Degradation of Bromoxynil Octanoate in Buffered 

Aqueous Solution: Project No. 854R10. Unpublished study prepared by Union Carbide 

Agricultural Pro- ducts Company, Inc. 20 p.

00147767 Merricks, D. (1982) Hydrolysis of [Carbon 14]-Bromoxynil Octanoate: Project No. 2203. 

Unpublished study prepared by Borriston Lab- oratories, Inc. 25 p.

00150216 Piznik, M.; Wargo, J. (1985) Determination of the Octanal-water Partition Coefficient of 

Bromoxynil Octanoate: ASD No. 85-124. Unpublished study prepared by Rhone-Poulenc Inc. 17 

p

40131001 Guardigli, A. (1985) The Photolysis of [Carbon 14] Bromoxynil on a Sandy Loam Soil Surface 

Exposed to Simulated Sunlight: Lab Project ID: 85/145. Unpublished study prepared by RhonePoulenc Inc. 64 p.

41240103 Hoffman, M. (1988) Water Solubility Determination of Bromoxynil Octanoic Acid Ester: Project 

ID HLA 6001-190. Unpublished study prepared by Hazleton Laboratories America, Inc. 22 p.

41240104 Hoffman, M. (1988) Vapor Pressure Determination of Bromoxynil Octanoic Acid Ester: Project 

ID HLA 6001-189. Unpublished study prepared by Hazleton Laboratories America, Inc. 22 p.

41324901 Buddle, G.; Mills, E.; Patel, P. et al. (1989) Bromoxynil Heptanoate--Product Chemistry: Lab 

Project Number: D/AG/1290. Unpublished study prepared by Rhone-Poulenc Ag Co. 128 p.

41411001 Gemma, A. (1990) Metabolism of Bromoxynil Octanoate in Soil under Anaerobic Aquatic 

Conditions: Lab Project No. 791 R10: File No. 40718. Unpublished study prepared by RhonePoulenc, Inc. in cooperation with Rhone-Poulenc Ag Co. 62 p.

41653701 Norris, F. (1989) A Small Scale Field Soil Dissipation Study with Bromoxynil (Buctril Herbicide): 

Lab Project Number: EC/P-89-0011 RPT R072-023,027; R150-028,029; R150-30,031. 

Unpublished study prepared by McKenzie Labs, Inc. in cooperation with A & L Eastern Ag Labs, 

Inc. and Rhone-Poulenc Ag, NC. 105 p.

41892901 Das, Y. (1990) Hydrolysis of ?Phenyl(U)-Carbon 14| Bromoxynil Octanoate in Aqueous Solutions 

Buffered at PH 5, 7, and 9: Lab Project Number: 90040: EC-90-107. Unpublished study prepared 

by Innovative Scientific Services, Inc. 100 p.

41892902 Jackson, R.; Hall, B.; Cameron, B. (1991) Carbon 14--Bromoxynil Octanoate: Anaerobic Aquatic 

Metabolism: Lab Project Number: 142241: 7601. Unpublished study prepared by Inveresk 

Research International. 132 p.

41897701 Cameron, B.; Hall, B.; Mackie, J. (1990) Carbon 14-Bromoxynil Octanoate: Metabolism in Soil 

Under Aerobic Conditions: Lab Project Number: 7450. Unpublished study prepared by Inveresk 

Research International. 98 p.

41920401 Das, Y. (1991) Photodegradation of ?Phenyl(U)-Carbon 14| Bromoxynil Octanoate in Aqueous 

Solution Buffered at pH 5 under Artificial Sunlight: Lab Project Number: ISSI 91010: EC-91-145. 

Unpublished study prepared by Innovative Scientific Services, Inc. 11 p.

41920402 Das, Y. (1991) Photodegradation of ?Phenyl(U)-?Carbon-14|| Bromoxynil Octanoate on Soil 

under Artificial Sunlight: Lab Project Number: ISSI 91011: EC-91-147. Unpublished study 

prepared by Innovative Scientific Services, Inc. 133 p.

42066401 South, P.; Schweitzer, M. (1991) Dissociation Constants of Bromoxynil in Water: Lab Project 

Number: SC910121. Unpublished study prepared by Battelle. 32 p.

42087401 Schweitzer, M.; South, P. (1991) Determination of the Solubility of Bromoxynil: Final Report: 

Lab Project Number: SC910123. Unpublished study prepared by Battelle. 36 p.

42130101 Schweitzer, M. (1991) Vapor Pressure of Bromoxynil: Final Report: Lab Project Number: 

SC910122. Unpublished study prepared by Battelle. 37 p.

42234301 Yenne, S. (1992) Photodegradation of Bromoxynil Octanoate in Aqueous Solution Buffered at pH 

5 Under Artificial Sunlight: Addendum to: Lab Project Number: SPY-92-34. Unpublished study 

prepared by Innovative Scientific Services, Inc. 23 p.

42234302 Yenne, S. (1992) Bromoxynil Octanoate Metabolism in Soil Under Aerobic Conditions: 

Addendum to: Lab Project Number: SPY-92-35. Unpublished study prepared by Inveresk 

Research International (Scotland). 6 p.

42234303 Yenne, S. (1992) Bromoxynil Octanoate Anaerobic Aquatic Metabolism: Addendum to: Lab 

Project Number: SPY-92-36. Unpublished study prepared by Inveresk Research International 
33

(Scotland). 4 p.

42271101 Grau, J.; Fitzmaurice, M. (1992) Ring-carbon 14Bromoxynil Octanoate: Leaching Study with 

Four Soils: Lab Project No. P91/046. Unpublished study prepared by Rhone-Poulenc Ag. Ltd. 62 

p.

42277301a Yenne, S.; Macy, L.; Andrawes, N.; et al. (1992) Uptake, Depuration and Bioconcentration of 

?carbon 14|-Bromoxynil Octanoate by Bluegill Sunfish (Lepomis macrochirus): Lab Project 

Number: EC91-144. Unpublished study prepared by ABC Labs., Inc. and Rhone-Poulenc Ag Co. 

624 p.

42277301b Yenne, S.; Macy, L.; Andrawes, N.; et al. (1992) Uptake, Depuration and Bioconcentration of 

?carbon 14|-Bromoxynil Octanoate by Bluegill Sunfish (Lepomis macrochirus): Lab Project 

Number: EC91-144. Unpublished study prepared by ABC Labs., Inc. and Rhone-Poulenc Ag Co. 

624 p.

42333601 Buddle, G.; Patel, P. (1991) 3,5-Dibromo-4-hydroxybenzonitrile, Bromoxynil Phenol Technical: 

Density, pH, Octanol/Water Partition Coefficient and Storage Stability ?Product Chemistry Data|. 

Unpublished study prepared by Rhone-Poulenc Ag Co. 42 p.

42364901 Gorman, M. (1990) Aerobic Aquatic Metabolism of ?carbon 14|-Bromoxynil Octanoate in 

Flooded Sandy Loam Soil:ABC Revised Final Report: Lab Project Number: 38288. Unpublished 

study prepared by Analytical Bio-Chemistry Labs., Inc. 55 p.

43071001 Norris, F. (1993) Storage Stability of Bromoxynil and Bromoxynil Octanoate in Frozen Soil: 

Addendum to MRID 41653701: Lab Project Number: EC-92-205: 41383. Unpublished study 

prepared by McKenzie Laboratories, Inc. 118 p.

43775001 Cooper, J.; Jones, M.; Lowden, P. et al. (1995) Herbicides: Bromoxynil Octanoate: Aged 

Leaching in Four Soils and a Sediment: Addendum to MRID 42271101: Lab Project Number: P 

95/089: DOCMAP 200996: ONG 688. Unpublished study prepared by Rhone-Poulenc Ag. Co. 

303 p.

44906003 Willis, C. (1999) Physical and Chemical Characteristics of Bromoxynil Octanoate Technical: 

Color, Physical State, Odor, Stability, pH, Melting Point, Bulk Density and Dissociation Constant: 

Lab Project Number: 810-61. Unpublished study prepared by Case Consulting Laboratories, Inc. 

11 p.
34

Ecological Effects Studies

035301 Bromoxynil Eco Effects Bibliography

71-1 Avian Single Dose Oral Toxicity

MRID Citation Reference

31491 MCPA/Bromoxynil 

mixture 

Fink, R.; Beavers, J.B.; Joiner, G.; et al. (1979) Final Report: Acute 

Oral LD50--Mallard Duck: Project No. 142-125. (Unpublished study 

received Apr 15, 1980 under 264-339; prepared by Wildlife 

International, Ltd. in cooperation with Washington College, submitted 

by Union Carbide Agricultural Products Co., Ambler, Pa.; CDL:099391-

I) 

78249 Bromoxynil/Diuron 

mixture

Gabriel, K.L. (1970) Acute Oral Toxicity--Bob White Quail. (Unpub 

lished study received Aug 14, 1970 under 264-261; prepared by 

Biosearch, Inc., submitted by Union Carbide Agricultural Products Co., 

Inc., Ambler, Pa.; CDL:100280-H) 

109414 General summary May & Baker Ltd. (1964) Wild Life Studies with Bromoxynil and Its 

Ester: CRC/BJH/2415. (Unpublished study received Jul 28, 1982 under 

359-564; submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; 

CDL:247924-B) 

111898 Bromoxynil/Diuron 

mixture

Gabriel, K. (1970) Acute Oral Toxicity--Bob White Quail: Amchem 69-

386|. (Unpublished study received Aug 14, 1970 under 264- 261; 

prepared by Biosearch, Inc., submitted by Union Carbide Agricultural 

Products Co., Inc., Research Triangle Park, NC; CDL:002230-E) 

147095 2059081 Fletcher, D. (1985) Acute Oral Toxicity Study with Bromoxymil Phenol 

in Bobwhite Quail: BLAL No. 85 QD 51. Unpublished study prepared by 

Bio-Life Assoc., Ltd. 21 p. 

71-2 Avian Dietary Toxicity

MRID Citation Reference

22701 Dicamba/Bromoxy

nil/Dieldrin mixture

Fink, R.; Broughton, W.S., Jr. (1973) Final Report: Eight-Day Dietary 

LDI50--Bobwhite Quail: Project No. 686-133. (Unpublished study 

received Nov 14, 1973 under unknown admin. no.; prepared by Hazleton 

Laboratories, Inc., submitted by Velsicol Chemical Corp., Chicago, Ill.; 

CDL:129206-B) 

23072 Dicamba/Bromoxy

nil/Dieldrin mixture

Fink, R.; Broughton, W.S. (1973) Final Report: Eight-Day Dietary LCI50^-

-Mallard Ducks: Project No. 686-134. (Unpublished study received Nov 

14, 1973 under unknown admin. no.; prepared by Hazelton Laboratories, 

Inc., submitted by Velsicol Chemical Corp., Chicago, Ill.; CDL:129206-C) 

25385 Dicamba DMA 

salt/Bromoxynil/

Fink, R.; Broughton, W.S., Jr. (1973) Eight-Day Dietary LCI50-- Mallard 

Ducks: Banvel 4S + Bromoxynil-MCPA: Final Report: Proj- ect No. 686-
35

Dieldrin mixture 136. (Unpublished study received Feb 18, 1976 under 876-25; prepared 

by Hazleton Laboratories, Inc., submitted by Velsicol Chemical Corp., 

Chicago, Ill.; CDL:225101-C) 

28293 Dicamba/MCPA/

Bromoxynil/

Dieldrin mixture

Fink, R.; Broughton, W.S., Jr. (1973) Final Report: Eight-Day Dietary 

LC50I--Mallard Ducks: Project No. 686-136. (Unpublished study received 

Feb 18, 1976 under 876-25; prepared by Hazleton Laboratories, Inc., 

submitted by Velsicol Chemical Corp., Chi- cago, Ill.; CDL:225100-K) 

31492 MCPA/Bromoxynil/

Bromoxynil 

butyrate/Dieldrin 

mixture

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

Dietary LC50--Mallard Duck: Project No. 142-124. (Unpublished study 

received Apr 15, 1980 under 264-339; prepared by Wildlife International, 

Ltd. in cooperation with Washington College, submitted by Union Carbide 

Agricultural Products Co., Ambler, Pa.; CDL:099391-J) 

52153 2059017

In 035302

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

Dietary LC50--Bobwhite Quail: Project No. 142-123. (Unpublished study 

received Apr 15, 1980 under 264-339; prepared by Wildlife International, 

Ltd. in cooperation with Washington College, submitted by Union Carbide 

Agricultural Products Co., Ambler, Pa.; CDL:099391-K) 

72795 Dicamba/MCPA/

Bromoxynil/

Dieldrin mixture

Fink, R.; Broughton, W.S., Jr. (1973) Final Report: Eight-Day Dietary 

LCI50^--Bobwhite Quail: Project No. 686-135. (Unpublished study 

received Aug 11, 1976 under 876-25; prepared by Environmental 

Sciences Corp. in cooperation with Truslow Farms, submitted by Velsicol 

Chemical Corp., Chicago, Ill.; CDL: 226653-E) 

72796 Dicamba/MCPA/

Bromoxynil/

Dieldrin mixture

Fink, R.; Broughton, W.S., Jr. (1973) Final Report: Eight-Day Dietary 

LCI50^--Mallard Ducks: Project No. 686-136. (Unpub- lished study 

received Aug 11, 1976 under 876-25; prepared by Environmental 

Sciences Corp. in cooperation with Truslow Farms, submitted by Velsicol 

Chemical Corp., Chicago, Ill.; CDL:226653-F) 

147094 2059080 Fletcher, D. (1985) 8-Day Dietary LC50 Study with Bromoxymil Phenol in 

Bobwhite Quail: BLAL No. 85 QC 50. Unpublished study pre- pared by 

Bio-Life Assoc., Ltd. 17 p. 

147096 2059082 Fletcher, D. (1985) 8-Day Dietary LC50 Study with Bromoxymil Phenol in 

Mallard Ducklings: BLAL No. 85 DC 51. Unpublished study pre- pared by 

Bio-Life Assoc., Ltd. 16 p. 

71-3 Wild mammal toxicity

MRID Citation Reference

45204903 Open lit Freemark, K.; Boutin, C. (1994) Impacts of Agricultural Herbicide Use on 

Terrestrial Wildlife: a Review with Special Reference to Canada. Canadian 

Wildlife Service Technical Report Series 196:1-52. 
36

71-4 Avian Reproductive Effects

48033005 Open lit Albers, P.; Hoffman, D. (1984) Evaluation of Potential Embryotoxicity and 

Teratogenicity of 42 Herbicides, Insecticides, and Petroleum 

Contaminants to Mallard Eggs. Archives of Environmental Contamination 

and Toxicology 13: 15-27.

72-1 Acute Toxicity to Freshwater Fish

MRID Citation Reference

111177 or 

17722 or 

111900

Bromoxynil/

Diuron 

mixture

Hutchinson, C. (1970) Acute Toxicity of Amchem 69-386 to Bluegill and 

Rainbow Trout. (Unpublished study received Aug 14, 1970 under 264-261; 

prepared by Bionomics, Inc., submitted by Union Carbide Agricultural 

Products Co., Inc., Research Triangle Park, NC; CDL:002230-I) 

138086 2059078 Surprenant, D.; Sousa, J. (1983) Acute Toxicity of AXF-1240 to Rainbow 

Trout (Salmo gairdneri): Bionomics Study #070-1183-H87- 103; Bionomics 

Report #BW-83-11-1497. (Unpublished study received Jan 10, 1984 under 

264-408; prepared by EG&G Bionomics, submitted by Union Carbide 

Agricultural Products Co., Inc., Research Triangle Park, NC; CDL:072254-A) 

155071 2059084 Surprenant, D. (1985) Acute Toxicity of Bromoxynil Phenol to Bluegill 

(Leopomis macrochirus): Study #565.0285.6110.100: Report #BW-85-10-

1854. Unpublished study prepared by Springborn Bionomics, Inc. 15 p. 

155072 2059085 Surprenant, D. (1985) Acute Toxicity of Bromoxynil Phenol to Rainbow Trout 

(Salmo gairdneri): Study #565.0285.6110.103: Report #BW-85-10-1855. 

Unpublished study prepared by Springborn Bionomics, Inc. 15 p. 

159171 2059086 Surprenant, D. (1983) Acute Toxicity of AXF-1240 to Bluegill (Lepo- mis 

macrochirus): Bionomic Report #BW-83-12-1507. Unpublished study 

prepared by EG&G Bionomics. 11 p. 

40111005 DER not 

located

Bowman, J.; Swigert, J.; Landholt, K.; et al. (1986) Acute Toxicity of ME-4 

Brominal to Channel Catfish (Ictalurus punctatus): Static Acute Toxicity 

Report No. 34494. Unpublished study prepared by Analytical Bio-Chemistry 

Laboratories, Inc. 17 p. 

22700 Dicamba/

Bromoxynil 

mixture

Sleight, B.H., III (1973) Acute Toxicity of Banvel 4S (1 part) + Bromoxynil (12 

parts) to Bluegill (Lepomis macrochirus) and Rainbow Trout (Salmo 

gairdneri): Report No. 040200. (Unpub- lished study received Nov 14, 1973 

under unknown admin. no., prepared by Bionomics, Inc., submitted by 

Velsicol Chemical Corp., Chicago, Ill.; CDL:129206-A) 

34699 Dicamba Sleight, B.H., III (1973) Acute Toxicity of Banvel 4S (1 Part) + Bromoxynil-
37

DEA/MCPA/

Bromoxynil 

mixture

MCPA (8 Parts) to Bluegill (Lepomis macrochirus) and Rainbow Trout (Salmo 

gairdneri). (Unpublished study re- ceived Feb 18, 1976 under 876-25; 

prepared by Bionomics, Inc., submitted by Velsicol Chemical Corp., Chicago, 

Ill.; CDL: 225101-D) 

72-2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

138087 2059079 Surprenant, D.; Hoberg, J. (1983) Acute Toxicity of AXF-1240 to Daphnia 

magna: Bionomics Study #070-1183-H87-110; Bionomics Report #BW83-11-1498. (Unpublished study received Jan 10, 1984 under 264-408; 

prepared by EG&G Bionomics, submitted by Union Carbide Agricultural 

Products Co., Inc., Research Triangle Park, NC; CDL:072254-B) 

155070 2059083 Surprenant, D. (1985) Acute Toxicity of Bromoxynil Phenol to Daphnids 

(Daphnia magna): Study #565-0285-6110-110: Report #BW-85- 9-1840. 

Unpublished study prepared by Springborn Bionomics, Inc. 15 p. 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

MRID Citation Reference

72-6 Simulated or Actual Aquatic Field Testing

MRID Citation Reference

44529001 Registrant 

modeling

Ritter, A.; Williams, W. (1998) Probabilistic Modeling of Bromoxynil 

Octanoate Exposure to Aquatic Nontarget Organisms Associated with Use 

on Cotton and Corn: Lab Project Number: WEI 746.06. Unpublished study 

prepared by Waterborne Environmental, Inc. 35 p. 

122-1 Seed Germination/Seedline Emergence and Vegetable Vigor

MRID Citation Reference

41606006 2059041 in 

035302

Horbeg, J. (1990) Bromoxynil Octanoate--Determination of Effects on 

Seed Germination, Seedling Emergence and Vegetative Vigor of Ten 

Plant Species: Lab Project Number: 90-7-3379: 10566-1089-6144- 610. 

Unpublished study prepared by Springborn Laboratories, Inc. 134 p. 
38

122-2 Aquatic plant growth

MRID Citation Reference

45088212 Open lit Fairchild, J.; Ruessler, D.; Haverland, P. et al. (1996) Comparative 

Sensitivity of Selenastrum capricornutum and Lemna minor to Sixteen 

Herbicides. Archives of Environmental Contamination and Toxicology 

32:353-357. 

47954504 Open lit Ma, J.; Xu, L.; Wang, S.; et al. (2001) Toxicity of 40 Herbicides to the 

Green Alga Chlorella vulgaris. Exotoxicology and Environmental Safety 

51:128-132.

123-2 Aquatic plant growth (these studies are with the octanoate 035302)

MRID Citation Reference

41606001 2059036 in 

035302

Giddings, J. (1990) Bromoxynil Octanoate--Toxicity to the Freshwa- ter 

Diatom Navicula pelliculosa: Lab Project Number: 90-8-3431: 

566.1089.6142.440. Unpublished study prepared by Springborn 

Laboratories, Inc. 50 p. 

41606002 2059037 in 

035302

Giddings, J. (1990) Bromoxynil Octanoate--Toxicity to the Marine Diatom 

Skeletonema costatum: Lab Project Number: 90-8-3440: 10566-1089-

6142-450. Unpublished study prepared by Springborn Laboratories, Inc. 

38 p. 

41606003 PC Code 

035302

Giddings, J. (1990) Bromoxynil Octanoate--Toxicity to the Duckweed 

Lemna gibba G3: Lab Project Number: 90-8-3430: 10566.1089.6144.-

410. Unpublished study prepared by Springborn Laboratories, Inc. 44 p. 

41606004 2059039 in 

035302

Giddings, J. (1990) Bromoxynil Octanoate--Toxicity to the Freshwater 

Green Alga Selenastrum capricornutum: Lab Project Number: 90- 8-3436: 

10566-1089-6142-430. Unpublished study prepared by Springborn 

Laboratories, Inc. 48 p. 

41606005 2059040 in 

035302

Giddings, J. (1990) Bromoxynil Octanoate--Toxicity to the Freshwater 

Bluegreen Alga Anabaena flos-aquae: Lab Project Number: 90-8-3434; 

10566.1089.6142.420. Unpublished study prepared by Springborn 

Laboratories, Inc. 47 p. 

141-1 Acute Toxicity to the Honeybee

9151 2059077 Atkins, E.L., Jr., L.D. Anderson and E.A. Greywood (1969) Effect of 

Pesticides on 

Agriculture: Project No. 1499, Research Report CF-7501. (Unpublished 

Study Received May 8, 1971 under 1F1174, Prepared by Univ. of 

California-Riverside, Dept. of Entomology, Submitted by Ciba 

Agrochemical Co., Summit, NJ. CDL:090973-B)
39

142-3 Simulated or Actual Field Testing

MRID Citation Reference

109414 DER not 

located

May & Baker Ltd. (1964) Wild Life Studies with Bromoxynil and Its Ester: 

CRC/BJH/2415. (Unpublished study received Jul 28, 1982 under 359-564; 

submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL:247924-B) 

Non Guideline

48033013 Open lit EDSP Roncaglioni, A.; Piclin, N.; Pintore, M.; et al. (2008) Binary Classification 

Models for Endocrine Disrupter Effects Mediated Through the Estrogen 

Receptor. SAR and QSAR in Environmental Research 19(7-8): 679-733.

48176001 Open lit EDSP Bauer, E.; Bitsch, N.; Brunn, H.; et al. (2002) Development of an ImmunoImmobilized Androgen Receptor Assay (IRA) and its Application for the 

Characterization of the Receptor Binding Affinity of Different Pesticides. 

Chemosphere 46: 1107-1115.

17713 Efficacy McKinley, J.; McLane, S.R. (1970) Summary: Bromoxynil/Diuron Weed 

Control in Wheat. (Unpublished study received Aug 14, 1970 un- der 264-

261; submitted by Union Carbide Agricultural Products Co., Ambler, Pa.; 

CDL:100280-A) 

109414 General 

summary

May & Baker Ltd. (1964) Wild Life Studies with Bromoxynil and Its Ester: 

CRC/BJH/2415. (Unpublished study received Jul 28, 1982 under 359-564; 

submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL:247924-B) 

111172 2059085 Union Carbide Agricultural Products Co., Inc. (1970) Toxicity Summary for 

(69-386) Bromoxynil/Diuron. Summary of studies 002230-D through 

002230-I. (Unpublished study received Aug 14, 1970 under 264-261; 

CDL:002230-C) 

17717 General 

summary

Union Carbide Agricultural Products Company (19??) Toxicity Summary for 

(69-386): Bromoxynil/Diuron. Summary of studies 100280-G through 

100280-L. (Unpublished study received Aug 14, 1970 under 264-261; 

CDL:100280-F) 
40

035302 Bromoxynil Octanoate Eco Effects Bibliography

71-1 Avian Single Dose Oral Toxicity

MRID Citation Reference

31487 2059015 Fink, R.; Beavers, J.B.; Brown, R. (1979) Final Report: Acute Oral 

LD50--Mallard Duck: Project No. 142-122. (Unpublished study received 

Apr 17, 1980 under 264-339; prepared by Wildlife International, Ltd. in 

cooperation with Washington College, submitted by Union Carbide 

Agricultural Products Co., Ambler, Pa.; CDL: 099393-I) 

109414 Summary of 

studies

May & Baker Ltd. (1964) Wild Life Studies with Bromoxynil and Its Ester: 

CRC/BJH/2415. (Unpublished study received Jul 28, 1982 under 359-

564; submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; 

CDL:247924-B) 

114101 2059025 Fletcher, D. (1981) Report to Union Carbide Agricultural Products 

Company: Acute Oral Toxicity Study with Bromoxynil Octanoate, 

Technical, in Bobwhite Quail: BLAL No. 81 QD 6. (Unpublished study 

received Aug 31, 1982 under 264-204; prepared by Bio-Life Assoc., 

Ltd., submitted by Union Carbide Agricultural Products Co., Inc., 

Research Triangle Park, NC; CDL:248229-B) 

114102 2059026 Fletcher, D. (1981) Report to Union Carbide Agricultural Products 

Company: Acute Oral Toxicity Study with Bromoxynil Octanoate, 

Technical, in Mallard Ducks: BLAL No. 81 DD 4. (Unpublished study 

received Aug 31, 1982 under 264-204; prepared by Bio-Life Assoc., 

Ltd., submitted by Union Carbide Agricultural Products Co., Inc., 

Research Triangle Park, NC; CDL:248229-C) 

92013002 Registrant 

summary

Gregg, B. (1990) Rhone-Poulenc Ag Company Phase 3 Summary of 

MRID 00114101. Acute Oral Toxicity with Bromoxynil Octanoate, 

Technical, in Bobwhite Quail: Project 81 QD 6. Prepared by Bio-Life 

Associates, Ltd. 23 p. 

92013003 Registrant 

summary

Gregg, B. (1990) Rhone-Poulenc Ag Company Phase 3 Summary of 

MRID 00114102. Acute Oral Toxicity Study with Bromoxynil Octanoate, 

Technical, in Mallard Ducks: Project 81 DD 4. Prepared by Bio-Life 

Associates, Ltd. 22 p. 

109415 2059021 Harper, K.H. and H.B. Ginn (1965) The Acute Toxicity to Pheasant 

Chicks of Technical Grade M&B 10731 and NPH 1320 Formulation of 

M&R 10731, Huntingdon Research Centre 1339/65/257 (9/19/65). 

Submitted on 9/7/66. PP# 0F0994 Part C Tab IV. (Acc 247924)

71-2 Avian Dietary Toxicity

MRID Citation Reference

61189 DER not Harper, K.H.; Ginn, H.B. (1965) Toxicity of Technical Grade M & B 
41

located 10731 and NPH 1320 Formulation of M & B 10731 to (a) the Japa- nese

Quail (Coturnix japonica) and (b) the Mallard (Anas platyrhyncha): 

1250/65/167. (Unpublished study received Jun 24, 1965 under unknown 

admin. no.; prepared by Huntingdon Re- search Centre, England, 

submitted by CDL:107617-L) 

109416 2059022 Harper, K.; Ginn, H. (1965) Toxicity of Technical Grade M & B 10731 

and NPH 1320 formulation of M & B 10731 to (a) the Japanese Quail 

(Coturnix japonica) (b) the Mallard (Anas platyrhyncha): 1250/65/167. 

(Unpublished study received Jul 28, 1982 under 359-564; prepared by 

Huntingdon Research Centre, Eng., submitted by Rhone-Poulenc, Inc., 

Monmouth Junction, NJ; CDL:247924-D) 

114105 2059027 Fletcher, D. (1981) Report to Union Carbide Agricultural Products 

Company: 8-day Dietary LC50 Study with Bromoxynil Octanoate in 

Bobwhite Quail: BLAL No. 81 QC 9. (Unpublished study received Aug 

31, 1982 under 264-204; prepared by Bio-Life Assoc., Ltd., submitted by 

Union Carbide Agricultural Products Co., Inc., Re- search Triangle Park, 

NC; CDL:248229-F) 

114106 2059028 Fletcher, D. (1981) Report to Union Carbide Agricultural Products 

Company: 8-day Dietary LC50 Study with Bromoxynil Octanoate in 

Mallard Ducklings: BLAL No. 81 DC 9. (Unpublished study re- ceived 

Aug 31, 1982 under 264-204; prepared by Bio-Life Assoc., Ltd., 

submitted by Union Carbide Agricultural Products Co., Inc., Research 

Triangle Park, NC; CDL:248229-G) 

92013004 Registrant 

summary

Gregg, B. (1990) Rhone-Poulenc Ag Company Phase 3 Summary of 

MRID 00114105. Eight-day Dietary LC50 Study with Bromoxynil 

Octanoate in Bobwhite Quail: Project 81 QC 9. Prepared by Bio-Life 

Associates, Ltd. 21 p. 

92013005 Registrant 

summary

Gregg, B. (1990) Rhone-Poulenc Ag Company Phase 3 Summary of 

MRID 00114106. Eight-day LC50 Study with Bromoxynil Octanoate in 

Mallard Ducklings: Project 81 DC 9. Prepared by Bio-Life Associates, 

Ltd. 22 p. 

031472 2059014 Beavers, J. (1979) Eight-Day Dietary LC50 Mallard Duck AFX-1050. 

Final Report Received 4/17/80 under 264-GGO. Unpublished Report 

Prepared by Wildlife Corporation, South Charleston, W.VA. (In Acc 

#099393).

52153 2059017 Beavers, J. (1979) Eight-Day Dietary LC50 Bobwhite Quail –AFX-1050, 

Final Report Received 4/17/80 under 264-GGO. Unpublished Report 

Prepared by Wildlife International, Ltd., for Union Carbide Corporation, 

South Charleston, W.Va. (Acc. #099393).

61198 2059020 Heywood, B.J. (1964) (Merge) Wildlife Studies with Bromoxynil and its 

Esters, May and Baker Ltd. CRC/BJH/2415 (10/64). Submitted on 

3/15/64. PP# 7F0536 Part I Tab V. Acc 247924).
42

71-4 Avian Reproduction

MRID Citation Reference

42004101 2059044 Beavers, J.; Sipler, O.; Smith, G.; et al (1991) Bromoxynil Octano- ate: OneGeneration Reproduction Study with the Bobwhite (Colin- us virginianus): 

Lab Project Number: 171-123. Unpublished study prepared by Wildlife 

International Ltd. 244 p. 

42004102 2059045 Beavers, J.; Sipler, O.; Smith, G.; et al (1991) Bromoxynil Octano- ate: OneGeneration Reproduction Study with the Mallard (Anas platyhynchos): Lab 

Project Number: 171-124. Unpublished study prepared by Wildlife Int. Ltd. 

241 p. 

42475801 Addendum to 

42004101

Beavers, J. (1992) Bromoxynil Octanoate: A One-Generation Reproduction 

Study with the Bobwhite (Colinus viriginianus) An Addendum: Lab Project 

Number: JBB/ch/CHW5/MIHAICH. Unpublished study prepared by Wildlife 

International Ltd. 8 p. 

72-1 Acute Toxicity to Freshwater Fish

MRID Citation Reference

109414 Mixture tests with 

MCPA, Dinoseb, 

and 

pentachlorophenol,

May & Baker Ltd. (1964) Wild Life Studies with Bromoxynil and Its Ester: 

CRC/BJH/2415. (Unpublished study received Jul 28, 1982 under 359-

564; submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; 

CDL:247924-B) 

109418 or 

111189

2059024 Harper, K.; Ball, I. (1965) The Acute Toxicity of Herbicide M & B 10731 

to (c) the Goldfish (Carassius auratus): 1125/65/42. (Un- published 

study received Jul 28, 1982 under 359-564; prepared by Huntingdon 

Research Centre, Eng., submitted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL:247924-G) 

114107 2059029 LeBlanc, G.; Sousa, J. (1981) Acute Toxicity of Bromoxynil Octano- ate 

to Bluegill ...: Report #BW-81-12-1063. (Unpublished study received 

Aug 31, 1982 under 264-204; prepared by EG & G, Bio- nomics, 

submitted by Union Carbide Agricultural Products Co., Inc., Research 

Triangle Park, NC; CDL:248229-H) 

114108 2059030 LeBlanc, G.; Sousa, J. (1981) Acute Toxicity of Bromoxynil Octano- ate 

to Rainbow Trout ...: Report #BW-81-12-1064. (Unpublished study 

received Aug 31, 1982 under 264-204; prepared by EG & G, Bionomics, 

submitted by Union Carbide Agricultural Products Co., Inc., Research 

Triangle Park, NC; CDL:248229-I) 

159178 2059032 Seminara, J. (1979) The Acute Toxicity of AXF 1053 to the Bluegill

Sunfish, Lepomis macrochirus Rafinesque: UCES Project No. 11504-

26-03. Unpublished study prepared by Union Carbide Corporation 

Environmental Services. 8 p. 

159179 2059033 Seminara, J. (1979) The Acute Toxicity of AXF 1053 to the Rainbow 
43

Trout Salmo gairdneri Richardson: UCES Project No. 11504-26-04. 

Unpublished study prepared by Union Carbide Corporation Environmental Services. 8 p. 

40074009 Mixture test Drottar, K. (1986) Acute Toxicity of HOE 023408 5H EC32 A101 to 

Bluegill Sunfish (Lepomis macrochirus): ESE No. 86-350-0300- 2130. 

Unpublished study prepared by Environmental Science & Engineering, 

Inc. 42 p. MCPA/Bromoxynil octo/bromoxynil butyrate/diclofop-methyl

40074010 Mixture test Ward, G. (1986) Acute Toxicity of HOE 203408 5H EC32 A101 to 

Rainbow Trout (Salmo gairdneri): ESE No. 86-350-0200-2130. 

Unpublished study prepared by Environmental Science & Engineering, 

Inc. 41 p. MCPA/Bromoxynil octo/bromoxynil butyrate/diclofop-methyl

92013006 Registrant 

summary

Gregg, B. (1990) Rhone-Poulenc Ag Company Phase 3 Summary of 

MRID 00114107. Bromoxynil Octanoate - Acute Toxicity Test-Bluegill: 

Project BW-81-12-1063. Prepared by EG & G Bionomics. 17 p. 

92013007 Registrant 

summary

Gregg, B. (1990) Rhone-Poulenc Ag Company Phase 3 Summary of 

MRID 00114108. Bromoxynil Octanoate - Acute Toxicity Test-Rainbow 

Trout: Project BW-81-12-1064. Prepared by EG & G Bionomics. 17 p. 

72-2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

109417 2059023 Harper, K.; Ball, I. (1964) The Acute Toxicity of NPH 1320 Formula- tion of M 

& B 10731 to (a) Daphnia (Crustacea cladocera): 1093/ 65/9. (Unpublished 

study received Jul 28, 1982 under 359-564; prepared by Huntingdon 

Research Centre, Eng., submitted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL:247924-E) 

114109 2059031 LeBlanc, G.; Surprenant, D. (1981) Acute Toxicity of Bromoxynil Octanoate 

to the Water Flea ...: Report #BW-81-12-1071. (Unpub- lished study received 

Aug 31, 1982 under 264-204; prepared by EG & G, Bionomics, submitted by 

Union Carbide Agricultural Products Co., Inc., Research Triangle Park, NC; 

CDL:248229-J) 

40074011 Mixture test Ward, G. (1986) Acute Toxicity of HOE 023408 5H EC32 A101 to Waterfleas (Daphnia magna): ESE No. 86-350-0100-2130. Unpublished study 

prepared by Environmental Sciences & Engineering Inc. 36 p. 

MCPA/Bromoxynil octo/bromoxynil butyrate/diclofop-methyl mixture

92013008 Registrant 

summary

Gregg, B. (1990) Rhone-Poulenc Ag Company Phase 3 Summary of MRID 

00114109. Bromoxynil Octanoate - Acute Toxicity Test-Daphnia magna: 

Project BW-81-12-1071. Prepared by EG & G Bionomics. 17 p. 

61185 DDT / 

Bromoxynil 

octanoate

Harper, K.H.; Ball, I.R. (1964) The Acute Toxicity of NPH 1320 Formulation of 

M & B 10731 to (a) Daphnia (Crustacea clado cera ): 1093/65/9. 

(Unpublished study received Jun 24, 1965 under unknown admin. no.; 

prepared by Huntingdon Research Centre, England, submitted by 

CDL:107617-H) 
44

72-3 Acute Toxicity to Estuarine/Marine Organisms

MRID Citation Reference

42244501 2059046

2059627

Dionne, E. (1992) Bromoxynil Octanoate: Acute Toxicity to Eastern Oyster 

under Flow-Thru Conditions: Lab Project Number: 92-2-4106: 

10566.0191.6179.504. Unpublished study prepared by Springborn Labs, Inc. 

55 p. 

42250601 2059047

2059627

2059628

Machado, M. (1992) Bromoxynil Octanoate Technical--Acute Toxicity to 

Sheepshead Minnow (Cyprinodon variegatus) under Flow-through 

Conditions: Lab Project Number: 91-7-3853. Unpublished study prepared by 

Springborn Laboratories, Inc. 56 p. 

42250602 2059048

2059629

Machado, M. (1992) Bromoxynil Octanoate Technical--Acute Toxicity to 

Mysid Shrimp (Mysidopsis bahia) under Flow-through Conditions: Lab Project 

Number: 91-7-3861. Unpublished study prepared by Springborn 

Laboratories, Inc. 54 p. 

43487601 2059631 Machado, M. (1994) Bromoxynil Octanoate Technical--Acute Toxicity to 

Mysids (Mysidopsis bahia) Under Flow-through Conditions: Final Report: Lab 

Project Number: 94-10-5502: 10566.0894.6344.515. Unpublished study 

prepared by Springborn Labs, Inc. 70 p. 

43842301 Response to 

Review of 

MRID 

43487601

Suprenant, D. (1995) DER Response to Review of MRID 43487601: 

Bromoxynil Octaoate (sic)--Acute Toxicity to Mysids (Mysidopsis bahia) 

Under Flow Through Conditions. Unpublished study prepared by Springborn 

Labs, Inc. 6 p. 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

MRID Citation Reference

61186 2059018 Harper, K.H.; Ball, I.R. (1965) The Acute Toxicity of NPH 1320 Formulation of 

M & B 10731 to (b) the Rainbow Trout (Salmo gairdnerii Richardson): 

1234/65/151. (Unpublished study re- ceived Jun 24, 1965 under unknown 

admin. no.; prepared by Hunt- ingdon Research Centre, England, submitted 

by CDL:107617-I) 

61187 DDT/Bromox

ynil

Harper, K.H.; Ball, I.R. (1965) The Acute Toxicity of Herbicide M & B 10731 

to (c) the Goldfish (Carassius auratus): 1125/ 65/42. (Unpublished study 

received Jun 24, 1965 under unknown admin. no.; prepared by Huntingdon 

Research Centre, England, submitted by CDL:107617-J) 

61188 2059019 Harper, K.H.; Ball, I.R. (1965) The Acute Toxicity of Herbicide M & B 10731 

to (d) the Catfish (Ictalurus nebulosus): 1237/ 65/154. (Unpublished study 

received Jun 24, 1965 under unknown admin. no.; prepared by Huntingdon 

Rsearch Centre, England, submitted by CDL:107617-K) 

40111001 2059034 Surprenant, D.; Bentley, R.; Hoberg, J. et al. (1986) The Chronic Toxicity of 

Bromoxynil Octanoate to Daphnia magna under Flow- through Conditions: 

Report No. BW 86-9-2159: Study No. 565-1084- 6106-130. Unpublished 

study prepared by Springborn Bionomics, Inc. 38 p. 
45

40111003 2059035 Surprenant, D. (1987) The Toxicity of Bromoxynil Octanoate to Fathead 

Minnow (Pimephales promelas) Embryos and Larvae: Report #BW-87-2-

2016: Study #565-1084-6106-120. Unpublished study prepared by 

Springborn Bionomics, Inc. 40 p. 

41928301 2059042

2059625

Sousa, J. (1991) Bromoxynil Octanoate: Toxicity to Fathead Minnow 

(Pimephales promelas) Embryos and Larvae: Final Report: Lab Pro- ject 

Number: 10566. 0990. 6167. 120: 91-4-3719. Unpublished study prepared by 

Springborn Laboratories, Inc. 68 p. 

41928302 2059043

2059626

Putt, A. (1991) Bromoxynil Octanoate: Chronic Toxicity to Daphnids (Daphnia 

magna) Under Flow-Through Conditions: Lab Project Numb- er: 10566. 

0990. 6166. 130: 91-4-3718. Unpublished study prep- ared by Springborn 

Laboratories, Inc. 73 p. 

42265801 Response to 

EPA 

Comments

Suprenant, D. (1992) Response to EPA Comments Regarding the Early Life 

Stage Exposure (Fathead Minnow)--MRID 41928301 and Life Cycle 

Exposure (Daphnids)--MRID 41928302 to Bromoxynil Octanoate. 

Unpublished study prepared by Springborn Laboratories, Inc. 51 p. 

92013009 Registrant 

summary

Gregg, B. (1990) Rhone-Poulenc Ag Company Phase 3 Summary of MRID 

40111003. Bromoxynil Octanoate - Toxicity to Embryos and Larvae -

Fathead: Minnow (Pimephales promelas): Project BW-87-2-2016. Prepared 

by Springborn Bionomics, Inc. 19 p. 

92013010 Registrant 

summary

Gregg, B. (1990) Rhone-Poulenc Ag Company Phase 3 Summary of MRID 

40111001. Bromoxynil Octanoate - Chronic Toxicity under Flow-through 

Conditions - Daphnia magna: Project BW-86-9-2159. Prepared by 

Springborn Bionomics, Inc. 18 p. 

122-1 Seed Germination/Seedline Emergence and Vegetable Vigor

MRID Citation Reference

41606006 2059041 Horbeg, J. (1990) Bromoxynil Octanoate--Determination of Effects on Seed 

Germination, Seedling Emergence and Vegetative Vigor of Ten Plant 

Species: Lab Project Number: 90-7-3379: 10566-1089-6144- 610. 

Unpublished study prepared by Springborn Laboratories, Inc. 134 p. 

43273801 2059049 Hoberg, J. (1994) Bromoxynil Octanoate--Determination of Effects on Seed 

Germination of Ten Plant Species: Final Report: Lab Project Number: 94-4-

5225: 10566.0394.6339.610. Unpublished study prepared by Springborn 

Lab., Inc. 72 p. 

123-1 Seed germination/seedling emergence and vegitative vigor

MRID Citation Reference

43170901 Supplemental 

data

Hoberg, J. (1994) Supplement to (Bromoxynil Octanoate)--Determination of 

Effects on Seed Germination, Seedling Emergence and Vegetative Vigor of 

Ten Plant Species: Lab Project Number: 90-7-3379: 10566-1089-6144-610. 

Unpublished study prepared by Springborn Labs., Inc. 23 p. 
46

43273801 2059049 Hoberg, J. (1994) Bromoxynil Octanoate--Determination of Effects on Seed 

Germination of Ten Plant Species: Final Report: Lab Project Number: 94-4-

5225: 10566.0394.6339.610. Unpublished study prepared by Springborn 

Lab., Inc. 72 p. 

43633701 2059050

2079285

Hoberg, J. (1995) Buctril--Determination of Effects on Seedling Emergence 

and Vegetative Vigor of Ten Plant Species: Final Report: Lab Project 

Number: 95-4-5778: 10566.0395.6354.610. Unpublished study prepared by 

Springborn Labs, Inc. 271 p. 

46801936 Pyrasulfotole 

mixture testcontract draft 

available

Pallett, K.; Gosch, H. (2006) Non-Target Terrestrial Plants: Seedling 

Emergence and Seedling Growth Test (Tier 2): AE 0317309 + Mefenpyr diethyl + Bromoxynil. Project Number: SE/05/001, EBAIX028. Unpublished 

study prepared by Bayer Cropscience Gmbh. 86 p. SEE PC Code 000692

46801937 Pyrasulfotole 

mixture testContract draft 

available

Pallett, K.; Gosch, H. (2006) Non-Target Terrestrial Plants: Vegetative 

Vigour Test (Tier 2): AE 0317309 + Mefenpyr di-ethyl + Bromoxynil. Project 

Number: VV/05/002, EBAIX029. Unpublished study prepared by Bayer 

Cropscience Gmbh. 78 p. SEE PC Code 000692

123-2 Aquatic plant growth

MRID Citation Reference

41606001 2059036 Giddings, J. (1990) Bromoxynil Octanoate--Toxicity to the Freshwa- ter 

Diatom Navicula pelliculosa: Lab Project Number: 90-8-3431: 

566.1089.6142.440. Unpublished study prepared by Springborn 

Laboratories, Inc. 50 p. 

41606002 2059037 Giddings, J. (1990) Bromoxynil Octanoate--Toxicity to the Marine Diatom 

Skeletonema costatum: Lab Project Number: 90-8-3440: 10566-1089-6142-

450. Unpublished study prepared by Springborn Laboratories, Inc. 38 p. 

41606003 2059038 Giddings, J. (1990) Bromoxynil Octanoate--Toxicity to the Duckweed Lemna 

gibba G3: Lab Project Number: 90-8-3430: 10566.1089.6144.- 410. 

Unpublished study prepared by Springborn Laboratories, Inc. 44 p. 

41606004 2059039 Giddings, J. (1990) Bromoxynil Octanoate--Toxicity to the Freshwater Green 

Alga Selenastrum capricornutum: Lab Project Number: 90- 8-3436: 10566-

1089-6142-430. Unpublished study prepared by Springborn Laboratories, 

Inc. 48 p. 

41606005 2059040 Giddings, J. (1990) Bromoxynil Octanoate--Toxicity to the Freshwater 

Bluegreen Alga Anabaena flos-aquae: Lab Project Number: 90-8-3434; 

10566.1089.6142.420. Unpublished study prepared by Springborn 

Laboratories, Inc. 47 p. 

42574601 2059630 Hoberg, J. (1992) Bromoxynil Octanoate--Toxicity to the Duckweed Lemna 

gibba: Final Report: Lab Project Number: 91-10-3968: 

10566.0891.6142.410. Unpublished study prepared by Springborn Labs., 

Inc. 56 p. 

42925101 Addendum to 

MRID No. 

42574601

Surprenant, D. (1993) Bromoxynil Oxtanoate--Toxicity to the Duckweed 

Lemna gibba. Addendum to MRID No. 42574601: Lab Project Number: 91-

10-3968. Unpublished study prepared by Springborn Labs., Inc. 6 p. 
47

142-3 Simulated or Actual Field Testing

MRID Citation Reference

109414 Summary of 

studies

May & Baker Ltd. (1964) Wild Life Studies with Bromoxynil and Its Ester: 

CRC/BJH/2415. (Unpublished study received Jul 28, 1982 under 359-564; 

submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL:247924-B) 

NON Guideline

46367 2059016 Biggs, R., S. Heath, K. Rivett, J. Johnston and N. Woolf (1964?) (Merge) 

Bromoxynil and Bromoxynil Octanoate, Toxicological Studies. May and 

Baker Ltd., AD/54/Biochem/301 (10/64), Submitted on 3/15/64. PP#7F0536 

Part I Tab IV. (247924).

61198 2059020 Heywood, B.J. (1964) (Merge) Wildlife Studies with Bromoxynil and its 

Esters, May and Baker Ltd. CRC/BJH/2415 (10/64). Submitted on 3/15/64. 

PP# 7F0536 Part I Tab V. Acc 247924).
48

128920 Bromoxynil Heptanoate Eco Effects Bibliography

71-1 Avian Single Dose Oral Toxicity

MRID Citation Reference

43030001 2071557 Campbell, S.; Beavers, J. (1993) Bromoxynil Heptanoate: An Acute Oral 

Toxicity Study with the Northern Bobwhite: Lab Project Number: 171-

134. Unpublished study prepared by Wildlife International Ltd. 21 p. 

71-2 Avian Dietary Toxicity

MRID Citation Reference

43030002 2071558 Campbell, S.; Beavers, J. (1993) Bromoxynil Heptanoate: A Dietary 

LC50 Study with the Northern Bobwhite: Lab Project Number: 171-133. 

Unpublished study prepared by Wildlife International Ltd. 43 p. 

72-1 Acute Toxicity to Freshwater Fish

MRID Citation Reference

43059601 2071559 Bettencourt, M. (1993) Bromoxynil Heptanoate-Acute Toxicity to Bluegill 

Sunfish (Lepomis macrochirus) Under Flow-Through Conditions: Lab 

Project Number: 93-10-5006: 10566.0693. 6303.105. Unpublished study 

prepared by Springborn Labs., Inc., Environmental Sciences Div. 72 p. 

72-2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

43059602 2071560 Putt, A. (1993) Bromoxynil Heptanoate-Acute Toxicity to Daphnids 

(Daphnia magna) Under Flow-Through Conditions: Lab Project Number: 

93-11-5050: 10566.0693.6304.115. Unpublished study prepared by 

Springborn Labs., Inc., Environmental Sciences Div. 74 p. 

122-1 Seed Germination/Seedline Emergence and Vegetable Vigor

MRID Citation Reference
49

43059603 2071561 SE

2071562 VVg

Hoberg, J. (1993) Bromoxynil Heptanoate-Determination of Effects on 

Seed Germination, Seedling Emergence and Vegetative Vigor of Ten 

Plant Species: Lab Project Number: 93-10-5003: 10566.0493.6287.610. 

Unpublished study prepared by Springborn Labs., Inc., Environmental 

Sciences Div. 217 p. 

122-2 Aquatic plant growth

MRID Citation Reference

43059604 2071563 Hoberg, J. (1993) Bromoxynil Heptanoate-Toxicity to Duckweed, Lemna 

gibba: Lab Project Number: 93-11-5040: 10566.0693.6301. 410. 

Unpublished study prepared by Springborn Labs., Inc., Environmental 

Sciences Div. 68 p. 

43059605 2071564 Hoberg, J. (1993) Bromoxynil Heptanoate-Toxicity to the Freshwater 

Alga, Selenastrum capricornutum: Lab Project Number: 93-11-5035: 

10566.0693.6302.430. Unpublished study prepared by Springborn 

Labs., Inc., Environmental Sciences Div. 66 p. 

123-1 Seed germination/seedling emergence and vegitative vigor

MRID Citation Reference

43059603 2071561 SE

2071562 VVg

Hoberg, J. (1993) Bromoxynil Heptanoate-Determination of Effects on 

Seed Germination, Seedling Emergence and Vegetative Vigor of Ten 

Plant Species: Lab Project Number: 93-10-5003: 10566.0493.6287.610. 

Unpublished study prepared by Springborn Labs., Inc., Environmental 

Sciences Div. 217 p. 

46801936 Mixture –

2065162 in 

PC Code 

000692

Pallett, K.; Gosch, H. (2006) Non-Target Terrestrial Plants: Seedling 

Emergence and Seedling Growth Test (Tier 2): AE 0317309 + Mefenpyr 

di-ethyl + Bromoxynil. Project Number: SE/05/001, EBAIX028. 

Unpublished study prepared by Bayer Cropscience Gmbh. 86 p.

46801937 mixture Pallett, K.; Gosch, H. (2006) Non-Target Terrestrial Plants: Vegetative 

Vigour Test (Tier 2): AE 0317309 + Mefenpyr di-ethyl + Bromoxynil. 

Project Number: VV/05/002, EBAIX029. Unpublished study prepared by 

Bayer Cropscience Gmbh. 78 p.

123-2 Aquatic plant growth

MRID Citation Reference

43059604 2071563 Hoberg, J. (1993) Bromoxynil Heptanoate-Toxicity to Duckweed, Lemna 

gibba: Lab Project Number: 93-11-5040: 10566.0693.6301. 410. 

Unpublished study prepared by Springborn Labs., Inc., Environmental 

Sciences Div. 68 p. 
50

43059605 2071564 Hoberg, J. (1993) Bromoxynil Heptanoate-Toxicity to the Freshwater 

Alga, Selenastrum capricornutum: Lab Project Number: 93-11-5035: 

10566.0693.6302.430. Unpublished study prepared by Springborn 

Labs., Inc., Environmental Sciences Div. 66 p. 
51

Appendix B. Ecological Effects Data 

Toxicity testing reported in this section does not represent all species of birds, mammals, or 

aquatic organisms. Only a few surrogate species for both freshwater fish and birds are used to 

represent all freshwater fish (2000+) and bird (680+) species in the United States. Mammalian 

acute studies are usually limited to Norway or New Zealand rat or the house mouse. 

Estuarine/marine testing is usually limited to a crustacean, a mollusk, and a fish. Also, neither 

reptiles nor amphibians are tested. The risk assessment assumes that avian and reptilian 

toxicities are similar. The same assumption is used for fish and amphibians in the aquatic 

environment. The following information was taken from previous assessments and updated if 

recent studies were submitted.

Toxicity to Terrestrial Organisms

Avian

Avian Acute Oral Toxicity Findings

Species % A.I. 

derivative

LD50 (mg 

ai/kg)

MRID or Acc. No.

Author, Yr

Toxicity Category

Fulfills Guideline 

Requirement

 Bobwhite Quail 87.3 

octanoate

148 Acc. # 248229

Fletcher, 1981

moderately toxic Yes 

Bobwhite Quail 89.3

phenol

193 Acc. # 258887

Fletcher, 1985

moderately toxic Yes

Bobwhite Quail 94.8

heptanoate

359 43030001

Campbell, 1993

moderately toxic Yes

Bobwhite Quail 93.0

butyrate

420 Acc. # 248229

Fletcher, 1991 moderately toxic Yes

Mallard Duck 93.0

butyrate

1230 Acc. # 114104

Fletcher, 1982 slightly toxic Yes

Mallard Duck 87.3 

octanoate

2050 Acc.# 248229

Fletcher, 1981

practically nontoxicYes

Avian Subacute Dietary Toxicity Findings

Species

% A.I.

derivative

 LC50 

 (ppm ai)

MRID or Acc. No.

Author, Year Toxicity Category

Fulfills Guideline 

Requirement

Bobwhite Quail 94.8

heptanoate

4530 43030002

Campbell, 1993

slightly toxic Yes

Bobwhite Quail 87.3

octanoate

1150 Acc.# 248229

Fletcher, 1982

slightly toxic Yes

Bobwhite Quail 89.3

phenol

1790 Acc. # 258886

Fletcher, 1985

slightly toxic Yes
52

Bobwhite Quail 93

butyrate 3159 Acc. # 107853

Beavers, 1977

slightly toxic Yes

Mallard Duck 87.3

octanoate

1880 Acc.# 248229

Fletcher, 1981

slightly toxic Yes

Mallard Duck 89.3

phenol

1230 Acc. # 258888

Fletcher, 1985

slightly toxic Yes

Mallard Duck 93

butyrate

2736 Acc. # 104737

Beavers, 1977 slightly toxic Yes

Ring-necked Pheasant technical

octanoate

4400 Acc.# 247924

Harper, 1965

slightly toxic Yes

Ring-necked Pheasant 36.6

octanoate

1830 Acc.# 247924

Harper, 1965

slightly toxic Yes

Avian Reproduction Findings

Species % A.I. NOAEL 

ppm

LOAEL 

ppm 

Endpoints affected MRID No.

Author, Year

Fulfills 

Guideline 

Requirement

Northern 

Bobwhite 

97.2

octanoate

371 NA None 42004101,42475801

Beavers, 1991

Yes1

Mallard 

Duck

97.2

octanoate

102 340 number of eggs laid and set, 

number of viable embryos, 

number of live 3-week embryos, 

and lesions of old yolk 

peritonitis or regressing ovary 

42004102

Beavers, 1991

Yes

1 This study fulfills the guideline requirement even though it is classified as supplemental.

These results indicate that bromoxynil (phenol), heptanoate, octanoate and butyrate are 

moderately toxic to practically non-toxic to avian species on an acute oral basis and slightly toxic 

to avian species on a subacute dietary basis. The results of the reproduction studies indicate that 

bromoxynil octanoate can impair the reproduction of birds at dietary concentrations greater than 

102 ppm. 

Mammalian

Data from available mammalian studies which are used for human health risk assessment will be 

used to estimate toxicity to wild mammalian species. A rat acute oral LD50 study with 

bromoxynil (81-1, MRID# 124758) resulted in an LD50 of 81 mg/kg for female rats and 93 

mg/kg for male rats while a study with bromoxynil octanoate (81-1, MRID# 124112) resulted in 

an LD50 of 238 mg/kg for female rats and 400 mg/kg for male rats. These results indicate that 

bromoxynil and octanoate is moderately toxic to small mammals on an acute oral basis. 

A two-generation rat reproduction study with the technical grade of bromoxynil octanoate (97.8 - 

98.1% a.i.) (83-4, MRID 41149301) reported a reproductive NOAEL of 250 ppm and a systemic 

LOAEL greater than 250 ppm based on reduced body weight gain in females. 
53

Beneficial Insects

A honey bee acute contact LD50 study was submitted for bromoxynil octanoate due to its 

extensive use on cotton and other agricultural sites. A honeybee acute contact study using 

several pesticides was submitted. This study revealed that bromoxynil octanoate (formulation 

not identified) is practically nontoxic to honeybees with an LD50 of 14.5 μg ai/bee (00018842). 

There is sufficient information to characterize bromoxynil octanoate as practically non-toxic to 

bees. 

Toxicity to Terrestrial Plants

Terrestrial plant testing (seedling emergence and vegetative vigor) is required for all herbicides. 

For the seedling emergence and vegetative vigor testing, the following plant species and groups 

should be tested: (1) six species of at least four dicotyledonous families, one species of which is 

soybean (Glycine max), and the second of which is a root crop, and (2) four species of at least 

two monocotyledonous families, one of which is corn (Zea mays).

Tier II toxicity data on the TEP material for the most sensitive species is listed below:

Study Type % AI Species EC25

(lb ai/A)

Most Sensitive 

Endpoint

MRID #

Author, Year

Fulfills Guideline 

Requirements

Germination 97.6

octanoate

dicot -- tomato >0.45 germination, radicle 

length

43273801

Hoberg, 1994

Yes

all monocots tested >0.45 germination, radicle 

length

Seedling 

Emergence

94.8

heptanoate

dicot -- lettuce 0.014 shoot length 43059603

Hoberg, 1993

Yes

all monocots tested >0.45 shoot length

Vegetative 

Vigor

94.8

heptanoate

cabbage 0.011 shoot weight 43059603

Hoberg, 1993

Yes

ryegrass 0.19 root weight

Seedling 

Emergence

33.58

octanoate

(Buctril)

dicot --tomato 0.12 shoot length 43633701

Hoberg, 1995

Yes

all monocots tested > 0.60 emergence, shoot length

Vegetative 

Vigor

33.58

octanoate

(Buctril)

dicot--tomato, cabbage 0.017 plant dry weight 43633701

Hoberg, 1995

Yes

monocot--onion 0.37 plant dry weight

The results indicate that non-target terrestrial plants may be affected from runoff if the soil 

residues exceed an equivalent of 0.12 lb ai/A and from drift, if the drift residues exceed 0.017 lb 

ai/A. (MRID 43633701)

Toxicity to Aquatic Organisms

Freshwater Fish Acute

Two freshwater fish toxicity studies using the technical grade of the active ingredient are 
54

required to establish the toxicity of a pesticide to freshwater fish. One study should use a 

coldwater species (preferably the rainbow trout), and the other should use a warmwater species 

(preferably the bluegill sunfish). Results of these tests are tabulated below.

Freshwater Fish Acute Toxicity Findings for Bromoxynil Octanoate

Species % A.I. 

derivatives

LC50

(ppb a.i.)

MRID No.

Author,Year

Toxicity 

Category

Fulfills Guideline 

Requirement

Rainbow Trout 36.6

octanoate

50 Acc. # 247924

Harper, 1965

very highly toxic Yes

Rainbow Trout 93

butyrate

29 Acc. # 104736

Kuc, 1977

very highly toxic Yes

Rainbow Trout 87.3

octanoate

100 Acc. # 264229

Sousa, 1981

highly toxic Yes

Rainbow Trout 21.5

phenol

3870 Acc. # 072254 

Hoberg, 1983

moderately toxic Yes

Rainbow Trout 95 

phenol

2100 Acc. # 260441

Nicholson, 1985

moderately toxic Yes

Bluegill Sunfish 94.8

heptanoate

29 43059601 

Bettencourt, 1993

very highly toxic Yes

Bluegill Sunfish 87.3

octanoate

53 Acc. # 248229

Sousa, 1981

very highly toxic Yes

Bluegill Sunfish 93

butyrate

45 Acc. # 104736

Kuc, 1977

very highly toxic Yes

Bluegill Sunfish 95

phenol

4000 Acc. # 260441

Nicholson, 1985

moderately toxic Yes

Bluegill Sunfish 21.5

phenol

4945 Acc. # 072336

Sousa, 1983

moderately toxic Yes

Catfish

(Ictalurus nebulosus)

36.6

octanoate

23 Acc. # 247924

Harper and Ball, 1965

very highly toxic No, supplemental

Goldfish 36.6

octanoate

170 Acc. # 247924

Harper and Ball, 1965

highly toxic No, supplemental

The results of the 96-hour acute toxicity studies indicate that bromoxynil octanoate, bromoxynil 

heptanoate and bromoxynil butyrate are very highly toxic, and bromoxynil phenol is moderately 

toxic to freshwater fish. (Accession # 247924, 072336, 260441, 248229, 072254, 264229, 

247924)

Freshwater Fish Chronic

Data from fish early life-stage tests are required because bromoxynil octanoate is very highly 

toxic to freshwater fish on an acute basis (acute LC50s range 23 - 100 ppb). Results of this test 

are tabulated below.
55

Fish Early Life-Stage Toxicity Findings

Species % A.I. NOAEL 

(ppb)

LOAEL 

(ppb)

MATC 

(ppb)

MRID No.

Author/Year

Endpoint Affected Fulfills 

Guideline 

Requirement

Fathead 

minnow

97.2 

octanoate

18 39 26 41928301

Sousa, 1991

decreased larval growth, 

survival and embryo 

hatching success

Yes, 

supplemental

Fathead 

minnow

63 

octanoate

9 18 12 40111003 

Suprenant, 1987

decreased larval survival No

Fathead 

minnow

74.27

butyrate

2.5 4.4 >2.5<4.4 40111004

Suprenant, 1986

decrease in larval total 

length

Yes

This chronic fish study is supplemental, but taken in conjunction with the previous early lifestage fish study conducted in 1987 (MRID 4111003) they satisfy the guideline requirement (72-

4(a)). The results indicate that reproductive effects of bromoxynil octanoate to freshwater fish 

may occur at levels greater than 9 ppb. (MRID 41928301 and 40111003). Bromoxynil butyrate 

deceased larval growth through reduction in total length. (MRID 40111004).

Freshwater Invertebrates Acute

A freshwater aquatic invertebrate toxicity test using the technical grade of the active ingredient is 

required to assess the toxicity of a pesticide to freshwater invertebrates. The preferred test 

organism is Daphnia magna, but early instar amphipods, stoneflies, mayflies, or midges may 

also be used. Results of this test are tabulated below.

Freshwater Invertebrate Toxicity Findings 

Species % A.I. EC50

(ppb ai)

MRID NO.

Author,Year

Toxicity Category Fulfills Guideline 

Requirement

Daphnia magna

(daphnid)

87.3

octanoate

96 Acc. # 248229

Suprenant, 1981

very highly toxic Yes

Daphnia pulex

(daphnid)

36.6

octanoate

11 Acc. # 247924

Harper, 1964

very highly toxic Yes

Daphnia magna

(daphnid)

94.8

heptanoate

31 43059602

Putt, 1993

very highly toxic Yes

Daphnia magna

(daphnid)

93

butyrate

200 Acc. # 114110

Suprenant, 1981

highly toxic Yes

Daphnia magna

(daphnid)

95

phenol

19,220 Acc. # 260441

Nicholson, 1985

slightly toxic Yes

Daphnia magna

(daphnid)

21.5

phenol

15,910 00138087

Hoberg, 1983

slightly toxic Yes
56

The results indicate that bromoxynil octanoate and heptanoate are very highly toxic and 

bromoxynil phenol is slightly toxic to aquatic invertebrates. (ACC #’s 247924, 260441, 248229

& MRID 00138087). Bromoxynil butyrate is highly toxic to daphnid (ACC # 114110).

Freshwater Invertebrates Chronic

Data from an aquatic invertebrate life-cycle test using Daphnia magna are required because 

bromoxynil octanoate is very highly toxic to Daphnia magna (EC50 of 11-96 ppb), is registered 

for uses that involve multiple applications, and has a half-life of greater than 4 days. Results of 

this test are tabulated below.

Aquatic Invertebrate Life-Cycle Toxicity Findings

Species % A.I. NOAEL ppb 

ai 

LOAEL 

ppb ai

MATC ppb 

ai

MRID No.

Author/Year

Endpoint 

Affected

Fulfills 

Guideline 

Requirement

Daphnia magna

(daphnid)

97.2

octanoate

2.5 5.9 3.8 41928302

Putt, 1991

reproduction 

and growth

Yes

Daphnia magna 

(daphnid)

60

octanoate

2.6 5.3 3.7 40111001

Suprenant, 1986

survival Yes

Daphnia magna 

(daphnid)

74.27

butyrate

>26<60

Geometric 

mean = 29

40111002

Suprenant, 1986

No

Both aquatic invertebrate studies are supplemental individually, but taken together they satisfy 

the guideline requirement for a life-cycle aquatic invertebrate study. The results indicate that 

aquatic invertebrate reproductive impairment may occur at bromoxynil octanoate levels greater 

than 2.5 ppb. (MRID 41928302 and 40111001)

Estuarine and Marine Organisms

Acute toxicity testing with estuarine and marine organisms (fish, shrimp and oyster embryolarvae or shell deposition) using the technical grade of the active ingredient is required for 

bromoxynil octanoate because of aerial application and because it has use patterns associated 

with estuarine and marine environments. Results of these tests are tabulated below.

Estuarine/Marine Acute Toxicity Findings

Species % A.I. LC50 or EC50

(ppb ai)

MRID No. 

Author/Year

Toxicity Category Fulfills Guideline 

Requirement

Eastern oyster

(shell deposition)

92.4

octanoate

155 42244501

Dionne, 1992

highly toxic Yes

Mysid 94.9

octanoate

65 43487601

Machado, 1994

very highly toxic Yes

Sheepshead minnow 97.2

octanoate

170 42250601

Machado, 1992

highly toxic Yes
57

The results indicate that bromoxynil octanoate is highly toxic to estuarine/marine fish and very 

highly toxic to estuarine/marine shrimp on an acute basis. (MRID 42244501, 42250601 &

43487601). 

Chronic testing with bromoxynil octanoate or phenol for estuarine/marine organisms (72-4) has 

not been submitted and is requested.

Aquatic plants

Currently, aquatic plant testing is required for all herbicides. The following species should be 

tested: Selenastrum capricornutum, Lemna gibba, Skeletonema costatum, Anabaena flos-aquae, 

and a freshwater diatom. 

Tier II toxicity data on the technical material is listed below:

Nontarget Aquatic Plant Toxicity Findings 

Species % A.I. EC50

(ppb ai)

MRID NO.

Author/year

Fulfills

Guideline

Requirement

Lemna gibba 94.8

heptanoate

219 43059604

Hoberg, 1993

Yes

Selenastrum capricornutum (green algae) 94.8

heptanoate

80 43059605

Hoberg, 1993

Yes

Navicula pelliculosa (Freshwater diatom) 97.2

octanoate

51 41606001

Giddings, 1990

Yes

Selenastrum capricornutum (green algae) 97.2

octanoate

210 41606004

Giddings, 1990

Yes

Skeletonema costatum (marine diatom) 97.2

octanoate

140 41606002

Giddings, 1990

Yes

Anabaena flos-aquae (blue-green algae) 97.2

octanoate

> 63 41606005

Giddings, 1990

No, Supplemental

The results indicate that algae and diatoms are sensitive to bromoxynil octanoate and heptanoate. 

The guideline requirements for Tier 2 aquatic plant testing for bromoxynil octanoate (GLN 123-

2) are only partially fulfilled. Acceptable data have not been submitted for Anabaena flos-aquae

and Lemna gibba. Data must be submitted to fulfill the guideline requirement for Anabaena flosaquae (blue-green algae) and Lemna gibba an aquatic macrophyte. (MRID 4160601, 41606002, 

41606004 & 41606005). 
58

Appendix C. ECOSAR Toxicity Estimates

Chemical Taxa Measured Tox 

Value (ppm)

ECOSAR estimate 

(ppm)

ECOSAR class

Bromoxynil phenol FW fish acute 2.1 258* Phenols

FW fish chronic -- 22.6

FW invert acute 15.9 50.7

FW invert chronic -- 9.7

SW fish acute -- 139

Green algae acute -- 256*

Green algae chronic -- 122

Lemna -- 234*

Bromoxynil octanoate FW fish acute 0.023 0.880 Esters 

FW fish chronic 0.009 0.035

FW invert acute 0.011 1.32

FW invert chronic 0.0025 0.374

SW fish acute 0.170 1.11

SW fish chronic -- 0.276

Mysid acute 0.065 0.242

Mysid chronic -- 0.035

Green algae acute 0.210 0.346

Green algae chronic -- 0.239

Bromoxynil 

heptanoate

FW fish acute 0.029 0.558 Esters

FW fish chronic -- 0.021

FW invert acute 0.031 0.809

FW invert chronic -- 0.210

SW fish acute -- 0.691

SW fish chronic -- 0.182

Mysid acute -- 0.129

Mysid chronic -- 0.010

Green algae acute 0.080 0.202

Green algae chronic -- 0.155

Lemna 0.219 --

Bromoxynil butyrate FW fish acute 0.029 3.61* Esters

FW fish chronic 0.0025 0.182

FW invert acute 0.200 6.12*

FW invert chronic 0.026 2.43*

SW fish acute -- 4.89*

SW fish chronic -- 0.986

Mysid acute -- 1.89*

Mysid chronic -- 2.89*

Green algae acute -- 1.93*

Green algae chronic -- 0.916

3,5-dibromo-4-

hydroxybenzamide

FW fish acute -- 47.9 Phenols

FW fish chronic -- 4.87

FW invert acute -- 14.7

FW invert chronic -- 2.79

SW fish acute -- 21.4

Green algae acute -- 67.3

Green algae chronic -- 31.6

Lemna -- 34.0

FW fish acute -- 82.8 Amides

FW fish chronic -- 0.145
59

FW invert acute -- 89.6

FW invert chronic -- 5.15

SW fish acute -- 73.1

Mysid acute -- 4.68

Green algae acute -- 2.63

Green algae chronic -- 2.51

FW fish acute -- 10.7 Phenol Amines

FW fish chronic -- 0.511

FW invert acute -- 1.43

FW invert chronic -- 0.338

Green algae acute -- 3.91

Green algae chronic -- 0.837

3,5-dibromo-4-

hydroxybenzoic acid

FW fish acute -- 65.8 Phenols-acid

FW fish chronic -- 7.89

FW invert acute -- 33.4

FW invert chronic -- 6.35

SW fish acute -- 23.9

Green algae acute -- 137*

Green algae chronic -- 63.5

Lemna -- 35.2

3,5-dibromo-

dihydroxy-

cyclohexadienylnitrile

FW fish acute -- 3.16 Poly phenols

FW fish chronic -- 1.46

FW invert acute -- 15.5

FW invert chronic -- 5.41

Green algae acute -- 2.48

Green algae chronic -- 0.394

3-bromo-4-

hydroxybenzonitrile

FW fish acute -- 14.3 Phenols

FW fish chronic -- 1.56

FW invert acute -- 5.39

FW invert chronic -- 1.03

SW fish acute -- 5.89

Green algae acute -- 23.6

Green algae chronic -- 11.0

Lemna -- 9.05

4-cyano-2-

bromophenyl 

octanoate

FW fish acute -- 0.268* Esters

FW fish chronic -- 0.009

FW invert acute -- 0.371*

FW invert chronic -- 0.085

SW fish acute -- 0.323*

SW fish chronic -- 0.092

Mysid acute -- 0.049

Mysid chronic -- 0.0016

Green algae acute -- 0.087

Green algae chronic -- 0.076

4-hydroxybenzonitrile FW fish acute -- 40.9 Phenols

FW fish chronic -- 3.90

FW invert acute -- 10.4

FW invert chronic -- 1.97

SW fish acute -- 19.8

Green algae acute -- 49.5

Green algae chronic -- 23.4

Lemna -- 32.2

*Above solubility limit
60

Appendix D. SIP and STIR Results

SIP

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

bound estimate of exposure via drinking water using the solubility of both bromoxynil octanoate 

(3 ppm) and bromoxynil (211 ppm). The most sensitive acute and chronic avian toxicity 

endpoints (bobwhite quail, LD50 = 148 mg/kg-bw and NOAEC = 102 ppm, respectively) and the 

most sensitive acute and chronic mammalian toxicity endpoints (rat, LD50 = 81 mg/kg-bw and 

NOAEL = 1.5 mg/kg/day, respectively) for bromoxynil or bromoxynil octanoate were used. 

Modeling potential exposure to bromoxynil and estimating the resulting risk using bromoxynil 

octanoate toxicity data and vice versa is a valid approach because terrestrial toxicity is similar for 

bromoxynil and its esters. Drinking water exposure to bromoxynil octanoate was not determined 

to be a pathway of concern for avian or mammalian species (no LOC exceedances are expected). 

However, this pathway is a potential concern for exposure to the more soluble bromoxynil for 

both avian and mammalian species. Results are presented in the tables below. 

SIP Avian Results for Bromoxynil Octanoate

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 2.43 2.43

Adjusted toxicity value (mg/kg-bw) 106.6 5.06

Ratio of exposure to acute toxicity 0.0228 0.480

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for birds

Drinking water exposure 

alone is NOT a potential 

concern for birds

SIP Mammalian Results for Bromoxynil Octanoate

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 0.516 0.516

Adjusted toxicity value (mg/kg-bw) 62.3 1.15

Ratio of exposure to toxicity 0.0083 0.447

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Drinking water exposure 

alone is NOT a potential 

concern for mammals

SIP Avian Results for Bromoxynil 

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 171 171

Adjusted toxicity value (mg/kg-bw) 107 5.06

Ratio of exposure to acute toxicity 1.60 33.8

Conclusion*

Drinking water exposure 

alone IS a potential concern 

for birds

Drinking water exposure 

alone IS a potential concern 

for birds

SIP Mammalian Results for Bromoxynil

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 36.3 36.3

Adjusted toxicity value (mg/kg-bw) 62.3 1.15

Ratio of exposure to toxicity 0.583 31.5
61

Conclusion*

Drinking water exposure 

alone IS a potential concern 

for mammals

Drinking water exposure 

alone IS a potential concern 

for mammals

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

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

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

STIR

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

upper bound estimates of bromoxynil octanoate and bromoxynil exposures via inhalation. The 

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

inputs for bromoxynil octanoate and bromoxynil included molecular weight (403.11 and 276.91 

g/mole, respectively), vapor pressure (1.39x10-6 and 2.5 x10-6 torr, respectively), highest 

application rate (1.8 lb a.i./A and 1.2 lb a.i./A, respectively, converted to lb of bromoxynil on a 

molecular weight basis), most sensitive acute avian toxicity endpoint (bobwhite quail, LD50 = 

148 mg/kg-bw), and most sensitive acute oral and inhalation mammalian toxicity endpoints (rat, 

LD50 = 81 mg/kg-bw and 4 hr inhalation LC50 = 0.72 and 0.15 mg/L, respectively). Neither 

droplet nor vapor inhalation were determined to be potential pathways of concern for avian or 

mammalian species.

STIR Avian (0.020 kg) Results for Bromoxynil Octanoate

Maximum Vapor Concentration in Air at Saturation (mg/m3) 3.02E-02

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.79E-03

Adjusted Inhalation LD50 7.34E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 5.17E-04 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 1.90E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 2.59E-02 Exposure not Likely Significant

STIR Mammalian (0.15 kg) Results for Bromoxynil Octanoate

Maximum Vapor Concentration in Air at Saturation (mg/m3) 3.02E-02

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 4.76E-03

Adjusted Inhalation LD50 4.29E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.11E-04 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 2.39E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 5.58E-03 Exposure not Likely Significant

STIR Avian (0.020 kg) Results for Bromoxynil 

Maximum Vapor Concentration in Air at Saturation (mg/m3) 3.73E-02

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 4.68E-03

Adjusted Inhalation LD50 1.53E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 3.06E-03 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 1.27E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 8.30E-02 Exposure not Likely Significant

STIR Mammalian (0.15 kg) Results for Bromoxynil

Maximum Vapor Concentration in Air at Saturation (mg/m3) 3.73E-02
62

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 5.89E-03

Adjusted Inhalation LD50 8.93E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 6.59E-04 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 1.59E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 1.78E-02 Exposure not Likely Significant