OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

March 3, 2016

PC Code: 112001

DP Barcode: 429381

MEMORANDUM

SUBJECT: Bromadiolone: Preliminary Problem Formulation for Environmental Fate, 

Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments 

in Support of Registration Review

FROM: Michael Lowit, Ph.D., Ecologist

Stephen Wente, Ph.D., Biologist

Sujatha Sankula, Ph.D., Branch Chief

Environmental Risk Branch I

Environmental Fate and Effects Division (7507P)

TO: Ricardo Jones, Chemical Review Manager

Tom Moriarty, Team Leader

Neil Anderson, Branch Chief

Risk Management and Implementation Branch I

Pesticide Re-evaluation Division (7508P)

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

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

exposure assessments to be conducted as part of the Registration Review of the rodenticide

bromadiolone (CAS# 28772-56-7). Functioning as the first stage of the risk assessment process 

for registration review, this problem formulation provides an overview of what is currently 

known about the environmental fate and ecological effects associated with bromadiolone and its 

degradates. It also describes the preliminary ecological risk hypothesis and analysis plan for 

evaluating and characterizing risk to non-target species in support of the registration review of 

bromadiolone. This document also recommends studies that should be included in a generic data 

call-in (DCI) to address uncertainties surrounding the environmental fate and potential ecological 

effects of bromadiolone.
2

EFED anticipates that the ecological risk assessment (ERA) will focus primarily on risk to terrestrial 

organisms and that neither an aquatic nor drinking water assessment (DWA) will be conducted because

potential exposure is expected to be minimal.

EFED recommends the following studies to reduce uncertainty in the risk assessment:

• 850.2100: Avian oral toxicity (passerine species) (bromadiolone; TGAI)1

• 850.2300: Avian reproduction (upland game species) (bromadiolone; TGAI)

• 850.2300: Avian reproduction (waterfowl species) (bromadiolone; TGAI)

In addition, non-guideline data on toxicity to terrestrial invertebrates other than the honeybee 

may be useful for reducing uncertainty in the risk assessment.

Toxicity data from other sources (e.g., other anticoagulants) may be used in the absence of data 

for bromadiolone. Use of surrogate data may over or underestimate risk of bromadiolone use.

EFED recommends the following label changes to reduce uncertainty in the risk assessment:

As labeled, sewer use requires securing bait in some manner to minimize chances of removal by 

rats or water. However, labels also state that one method is to place bait on a board supported by 

opposing steps of the ladder. If the board is above the high water mark then this would 

reasonably reduce the likelihood of removal by water; however, if the bait is not physically 

attached in some manner to the board then it is possible that it could be easily knocked off by 

rats or other animals. EFED recommends revising the label to specify that bait must be 

physically secured to the board. 

Other considerations:

Labels do not require use of a bait station in sewers. Although the product is placed below 

ground and contained inside of a sewer (not in contact with the water), there is potential direct 

exposure to non-target animals. Non-target terrestrial animals may be exposed through direct

exposure to bait if they are able to gain access into the sewer. Furthermore, direct exposure may 

occur if the bait becomes unsecured (e.g., chunks of bait blocks could be knocked or broken off 

as bait is eaten), flushed out of the sewer system, and then made more widely available to nontarget animals. If the product becomes unsecured then it is assumed that the bromadiolone is 

more likely to flush out of the sewer rather than substantially dissolve in water, in part because it 

is typically embedded in some sort of waxy material. These direct exposure pathways from 

sewer use (i.e., a non-target animal directly consuming bait inside or outside of the sewer) would 

not be considered complete (except for non-target animals that can gain access to the bait in the 

station) if bait is not only secured within the sewer but also contained in a bait station. In the 

absence of bait stations it will be assumed that a greater number and variety of animals may 

directly consume bromadiolone placed in sewers.

 1 The observation period should be extended beyond that of a standard 850.2100 study (14 days) given that effects 

from bromadiolone poisoning are not immediate (i.e., it should be long enough to capture effects of bromadiolone 

poisoning and continue until evidence of toxicity has subsided).
3

Problem Formulation for the Environmental Fate, 

Ecological Risk, Endangered Species, and Drinking 

Water Exposure Assessments in Support of the 

Registration Review of Bromadiolone

CAS: 28772-56-7

PC Code: 112001

Environmental Fate and Effects Division

Prepared by:

Michael Lowit, Ph.D., Ecologist

Stephen Wente, Ph.D., Biologist

U.S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch I

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Reviewed by:

Brian Anderson, Branch Chief, ERB2

O O

OH OH

Br
4

Table of Contents

1. Purpose........................................................................................................................................ 5

2. Problem Formulation .................................................................................................................. 5

2.1. Nature of Regulatory Action................................................................................................ 5

2.2. Previous Assessments.......................................................................................................... 5

2.2.1. Ecological Risk Assessments........................................................................................ 5

2.2.2. Drinking Water Exposure Assessments........................................................................ 5

2.2.3. Other Actions................................................................................................................ 5

3. Stressor Source and Distribution ................................................................................................ 6

3.1. Mechanism of Action.......................................................................................................... 6

3.2. Overview of Pesticide Use and Usage ................................................................................ 6

3.3. Physical, Chemical, and Environmental Fate Properties of Bromadiolone and its 

Degradates................................................................................................................................... 7

3.4. Monitoring Data.................................................................................................................. 8

3.5. Clean Water Act.................................................................................................................. 8

4. Receptors.................................................................................................................................... 9

4.1. Toxicity of Bromadiolone................................................................................................... 9

4.2. Secondary Toxicity to Birds and Mammals...................................................................... 11

4.3. Incident Databases Review............................................................................................... 12

5. Exposure Pathways of Concern ............................................................................................... 13

6. Analysis Plan ........................................................................................................................... 13

6.1. Stressors of Concern .......................................................................................................... 14

6.2. Measures of Exposure........................................................................................................ 14

6.3. Measures of Effect ............................................................................................................. 15

6.4. Integration of Exposure and Effects .................................................................................. 15

6.5. Endangered Species Assessments...................................................................................... 16

6.6. Endocrine Disruptor Screening.......................................................................................... 17

6.7. Drinking Water Assessment .............................................................................................. 17

6.8. Preliminary Identification of Data Gaps............................................................................ 17

6.8.1. Environmental Fate Data ............................................................................................ 17

6.8.2. Ecological Effects Data............................................................................................... 18

7. References................................................................................................................................ 22

APPENDIX A. Names and Structures of Bromadiolone and its Major and Minor Degradates . 23

APPENDIX B. STIR v.1.0 Inputs and Outputs........................................................................... 25
5

1. Purpose

The purpose of this problem formulation is to provide an understanding of what is known about 

the environmental fate, ecological effects, and currently registered uses of bromadiolone, a 

second-generation anticoagulant rodenticide. This document provides a plan for analyzing data 

relevant to bromadiolone and for conducting environmental fate, ecological risk, endangered 

species, and drinking water exposure assessments for its registered uses. Additionally, this 

problem formulation identifies data gaps, uncertainties, and potential assumptions used to 

address those uncertainties relative to characterizing the potential ecological risk associated with 

the registered uses of bromadiolone.

2. Problem Formulation

2.1. Nature of Regulatory Action

As part of the implementation of the Registration Review program2 pursuant to Section 3(g) of 

the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the Agency is beginning its 

evaluation of bromadiolone to determine whether it continues to meet the FIFRA standard for 

registration. This problem formulation in support of the Registration Review of bromadiolone 

will be posted in the initial docket which will be open to the public phase of the review process.

2.2. Previous Assessments

2.2.1. Ecological Risk Assessments

Bromadiolone was first registered in the US in 1980 as a rodenticide only for indoor use; it is 

currently registered for indoor uses as well as outdoor uses (above or underground around 

buildings and in sewers). Previous ERAs identified risk concerns for mammals and birds

through both primary (direct consumption of bait) and secondary (consumption of prey that 

have ingested bromadiolone) poisoning (see most recent assessment for a comprehensive 

account of past assessments: USEPA, 2011).

2.2.2. Drinking Water Exposure Assessments

A DWA has not been conducted. EFED anticipates that a DWA will not be performed for the 

Registration Review of bromadiolone because exposure through drinking water is expected to be 

minimal.

2.2.3. Other Actions

Risk mitigation measures were imposed as part of reregistration eligibility of bromadiolone and 

nine other rodenticides (USEPA, 2008). Requirements imposed to mitigate ecological risk 

included (1) minimum package size requirements, (2) sales and distribution restrictions, (3) use 

site restrictions, and (4) the required use of bait stations for all outdoor, above-ground uses.

In 2011, EPA presented to the Science Advisory Panel (SAP) an extensive assessment of the 

potential for primary and secondary exposure to several anticoagulant rodenticides, which were 

 2 http://www2.epa.gov/pesticide-reevaluation/registration-review-process
6

subject to a Notice of Intent to Cancel (NOIC).3

 Although bromadiolone was not one of the 

rodenticides subject to that NOIC, the assessment approach is broadly applicable to 

bromadiolone and other anticoagulant rodenticides.

3. Stressor Source and Distribution

3.1. Mechanism of Action

Bromadiolone is a second-generation anticoagulant rodenticide that acts by reducing the action 

of vitamin-K; thereby, disrupting normal blood-clotting mechanisms and inducing capillary 

damage (Pelfrene, 1991). Death results from hemorrhage, and exposed animals may exhibit 

increasing weakness prior to death. Bromadiolone may provide a lethal dose after a single 

feeding; however, death is usually delayed for a period of days because the animal may have 

vitamin-K reserves. Behavior also may be affected (Cox and Smith, 1992). In general, secondgeneration anticoagulants tend to be more acutely toxic and remain longer in body tissues of 

primary consumers than first-generation anticoagulants (e.g., warfarin, diphacinone, and 

chlorophacinone). 

3.2. Overview of Pesticide Use and Usage

Bromadiolone uses and application rates are reported in the most recent Label Use Information 

System (LUIS) report provided by the Biological and Economic Analysis Division (BEAD) 

(USEPA, 2015). Bromadiolone is labeled for indoor and outdoor use in and around man-made 

structures such as buildings and vehicles. Outdoor baiting must be within 50-100 ft of the 

structure. Furthermore, bait stations are mandatory for all outdoor, above ground uses. Two 

other outdoor uses are permitted and neither one requires use of a bait station: within sewers and 

animal burrows. In burrows, bait must be placed at least 6 inches deep according to some but not 

all labels and no labels require that the burrow be covered or capped. In sewers, the bait is 

securely attached to a structure although placement on a board supported by opposing steps of 

the ladder is also permitted (presumably unsecured). The maximum application rate is 0.00005 

lb ai/manhole for sewer uses and 0.00005 lb ai/placement for all other uses.4 

Bromadiolone products are used to control commensal rodents; that is, house mouse (Mus 

musculus), Norway rat (Rattus norvegicus), and roof rat (Rattus rattus). Some products can also 

be used to control for certain non-commensal rodents: cotton rat (Sigmodon hispidus), eastern 

harvest mouse (Reithrodontomys humulis), golden mouse (Ochrotomys nuttalli), Polynesian rat 

(Rattus exulans), meadow vole (Microtus pennsylvanicus), white-throated woodrat (Neotoma 

albigula), southern plains woodrat (Neotoma micropus), and Mexican woodrat (Neotoma 

mexicana). 

The registration review risk assessment will be based on current label information at the time of 

assessment as provided by BEAD.

 3 http://www.regulations.gov/#!docketBrowser;rpp=50;po=0;D=EPA-HQ-OPP-2011-0718 4 Rates reflect some recent label updates that were not captured in the most recent LUIS report.
7

3.3. Physical, Chemical, and Environmental Fate Properties of Bromadiolone and 

its Degradates

Bromadiolone (3-[3-(4'-bromo[1,1'-biphenyl]-4-yl)-3-hydroxy-1-phenylpropyl]-4-hydroxy-2H1-benzopyran-2-one) is a diastereomeric mixture. It has limited solubility in water (1.21 ppm) 

and is unlikely to volatilize. Select physical and chemical properties are presented in Table 1.

Table 1. Physical and Chemical Properties of Bromadiolone

Property Value Source

Common Name Bromadiolone

CAS Registry No. 28772-56-7 PPDB1

PC Code 112001 PPDB1

Structure MRID 43594301

Chemical Name (CAS) 3-[3-(4'-bromo[1,1'-biphenyl]-4-yl)-3-hydroxy-1-phenylpropyl]-

4-hydroxy-2H-1-benzopyran-2-one

PPDB1

SMILES notation c1cc(Br)ccc1c(cc2)ccc2C(O)CC(c3ccccc3)

C4=C(O)c5ccccc5OC4(=O)

PPDB1

Molecular Formula C30H23BrO4 PPDB1

Molecular Weight 527.40 g/mol PPDB1

Physical State Solid; fine white to off-white powder MRID 46933604

Vapor pressure < 10-7 torr at 25°C MRID 46933604

Henry’s Law constant 5.48 × 10-10 atm m3/mol @ 20°C MRID 46933604

Specific Gravity/ 

Density

0.680 g/ml MRID 46933604

Solubility in water 1.21 ppm @ pH 7 and 25°C MRID 46933604

log Kow 7.0 MRID 46933604

1 PPDB = Pesticide properties database; http://sitem.herts.ac.uk/aeru/ppdb/en/index.htm

Bromadiolone has a half-life of 128 days in soil (MRID 43594301) and can generally be 

considered immobile (MRID 43000702, 42237501, 00161972, 00161973, and 00161988) except 

in soils of low organic matter and clay, such as sand. Bioaccumulation concentration factors 

(BCFs) were l60X for edible tissues, 1658X for non-edible tissues, and 460X for whole fish. 

Sixteen percent to 35.8% of bromadiolone residues were retained in fish tissues after depuration. 

Table 2 summarizes the environmental fate data for bromadiolone. Chemical names, structures, 

and formation of major and minor degradates are reported in Appendix A.

O O

OH OH

Br
8

Table 2. Summary of the Environmental Fate Properties of Bromadiolone

Property Value Source

Hydrolysis half-life (days)

pH = 5

pH = 7

pH = 9

384

Stable

Stable

MRID 42237501

Aerobic soil metabolism half-life (days) 128 MRID 43594301

Soil adsorption coefficient 

Kd(ads)

Kd(ads) BBA2.1 = 93.2

Kd(ads) Bruckenberg = 95.7

Kd(ads) Dossenheim = 37.2

MRID 45692901

Laboratory accumulation in bluegill 

sunfish bioaccumulation factor 

(Lepomis macrochirus)

Depuration (%TTR remaining at 14 days)

Edible = 160.7

Non-edible = 1658.4

Whole fish = 459.9

Edible = 35.8%

Non-edible = 16.0%

Whole fish = 27%

MRID 00161965

Major degradates

There are two major degradates identified in the aerobic soil metabolism study (MRID 

43594301). These degradates are metabolite 1 (1,3-diphenyl-5(4’-bromo-biphenyl pentane-1-ol) 

and metabolite 3 (1,3-diphenyl-5(4’-bromo-biphenyl pentane-1,5-diol). Their structures can be 

found in Appendix A. EFED is not aware of any fate or toxicity data for these compounds.

3.4. Monitoring Data

A search of the water quality databases accessible through the Water Quality Portal5 identified 

only 14 samples for bromadiolone. All of the samples were collected by the National Park 

Service Water Resources Division from lakes and streams in the Rocky Mountains area of 

Colorado, Montana, and Wyoming. None of the 14 samples exceeded the detection limit of 50 

ng/L. Available data from sources including federal and state agencies will be considered in the 

ERA. 

Residues have been detected in wildlife. Samples from those organisms were collected for 

research surveys and follow-up to ecological incidents associated with pesticide use (see Section 

4.3).

3.5. Clean Water Act

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

under section 303(d) of the Clean Water Act.6

 In addition, no Total Maximum Daily Loads

 5 http://waterqualitydata.us/portal

6 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885
9

(TMDL) have been developed.7

 The Impaired Waters and TMDL website can be consulted for 

more information.8 Aquatic benchmarks have not been established for bromadiolone.9

4. Receptors

Consistent with the process described in the Overview Document (USEPA, 2004), the risk 

assessment for bromadiolone relies on a surrogate species approach. Toxicological data 

generated from surrogate test species, which are intended to be representative of broad 

taxonomic groups, are used to extrapolate the potential effects on a variety of species (receptors) 

included under these taxonomic groupings.

Acute and chronic toxicity data from studies submitted by pesticide registrants along with the 

available open literature will be used to evaluate the potential direct and indirect effects of 

bromadiolone to aquatic and terrestrial receptors. This includes toxicity on the technical grade 

active ingredient, degradates, and when available, formulated products (e.g., “Six-Pack” studies). 

Open literature studies will be identified through EPA’s ECOTOXicology (ECOTOX) 

database10, which employs a literature search engine for locating chemical toxicity data.

A summary of bromadiolone toxicity data is provided in Table 3 and 4 of Section 4.1. 

Secondary toxicity data are presented in Section 4.2 (Table 5). A review of ecological incidents 

associated with bromadiolone is provided in Section 4.3. The ECOTOX database will be 

searched when the risk assessment for bromadiolone is prepared. At that time, EFED will review 

the endpoints from open literature studies that are more sensitive than those from available 

guideline studies.

4.1. Toxicity of Bromadiolone

Table 3. Summary of Aquatic Taxa Toxicity Endpoints for Bromadiolone

Type of Study Species Toxicity Value MRID

Acute – Freshwater 

Fish

Rainbow trout

(Salmo gairdneri)

96-hr LC50 = 1.4 mg/L (1.1-1.7)1 (nom)

NOAEC ≤ 0.46 mg/L

LOAEC < 0.46 mg/L based on loss of 

equilibrium

Other sublethal effects: lethargy, dark 

coloration, and erratic swimming with 

gyrations

00070140

Bluegill Sunfish

(Lepomis macrochirus)

96-hr LC50 = 3.0 mg/L (2.4-3.7)1 (nom)

NOAEC = 1.3 mg/L

LOAEC = 2.2 mg/L based on mortality

Other sublethal effects: surfacing and dark 

coloration

00070141

 7 http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant 

_group_name=PESTICIDES

8 http://www.epa.gov/tmdl

9 http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/aquatic-life-benchmarks-pesticideregistration/

10 http://cfpub.epa.gov/ecotox/
10

Type of Study Species Toxicity Value MRID

Acute – Freshwater 

Invertebrate

Water flea 

(Daphnia magna)

48-hr EC50 = 0.24 mg/L (0.18-0.30)1

(nom)

NOAEC = 0.088 mg/L

LOAEC = 0.19 mg/L based on mortality

00070685

48-hr EC50 = 2 mg ai/L (1.8-2.6) 1

NOAEC = 1.2 mg ai/L

LOAEC = 1.8 mg ai/L based on mortality

42093302

1 Range is 95% confidence interval.

Nom = nominal concentration

Table 4. Summary of Terrestrial Taxa Toxicity Endpoints for Bromadiolone

Type of Study Species Toxicity Value MRID

Acute – Avian Oral 

Dose

Bobwhite quail

(Colinus virginianus)

LD50 = 170 mg ai/kg-bw (115-261) 1

NOAEL = 50 mg ai/kg-bw

LOAEL = 100 mg ai/kg-bw based on 

mortality

The observation period was 30 days.

001432792

Acute – Avian Dietary

Bobwhite quail

(Colinus virginianus)

LC50 = 37.6 mg ai/kg-diet (8.9-84.5) 1

Slope = 0.83 (0.42-1.23) 1

NOAEC < 10 mg ai/kg-diet

LOAEC ≤ 10 mg ai/kg-diet based on 

mortality

The observation period was 25 days after 

the exposure period.

001432803

Mallard duck

(Anas platyrhynchos)

LC50 = 158 mg ai/kg-diet (7-762) 1

Slope = 0.46 (0.11-0.81) 1

NOAEC < 19 mg ai/kg-diet

LOAEC ≤ 19 mg ai/kg-diet based on 

mortality, clinical signs of toxicity 

(reduced water consumption, lethargy, and 

mild anorexia) with recovery by day 15, 

and reduced food consumption with 

recovery by day 10.

Other sublethal effects: bloody droppings, 

loss of coordination, and blood filled cysts 

on bill).

The observation period was 25 days after 

the exposure period.

001432783

Acute – Mammalian 

Oral Dose

Laboratory Rat

(Wistar albino)

LD50 = 0.6 mg ai/kg-bw

Sublethal effects were not reported.

The observation period was 14 days.

002417034

Developmental –

Mammalian 10-day 

Oral Dose

Laboratory rat

(Sprague-Dawley)

NOAEL = 0.035 mg ai/kg-bw

LOAEL = 0.070 mg ai/kg-bw based on 

vaginal bleeding, hypotonicity, pale eyes, 

and mortality

921960145

1 Range is 95% confidence interval.
11

2 A TEP (Rat-A-Rest) study with bobwhite quail resulted in inconclusive toxicity (LD50 > 1% product of body 

weight or approximately 0.08675 mg ai/kg-bw) (MRID 00145323). Dose levels were presented in terms of Rat-ARest as a percentage of body weight; thus, the dose level in terms of mg ai/kg bw is based on the average weight of 

all birds at the highest test concentration. 

3 Additional TGAI studies with bobwhite quail and mallard duck with a shorter recovery period (14 days) resulted in 

less sensitive endpoints (Accession # 249995). Another TGAI study (MRID 44000202, un-reviewed) is available 

for mallard duck; however, a cursory review of the data indicates that the observed pattern of mortality is not 

suitable for calculation of a LC50 value. TEP (Rat-A-Rest) studies with bobwhite quail (MRID 00145321) and 

mallard duck (MRID 00145322) resulted in inconclusive toxicity (LC50 > 10 mg ai/kg-diet and LC50 > 20 mg ai/kgbw; respectively).

4 Test material was 1% bromadiolone and 99% corn starch instead of TGAI. Studies with bromadiolone concentrate 

(MRID 41900001) and TGAI (MRID 46993003) did not provide definitive endpoints: LD50 = 0.56-0.84 mg ai/kgbw and LD50 < 5 mg/kg-bw, respectively. 5 A chronic (2-generation reproduction) study is unavailable.

4.2. Secondary Toxicity to Birds and Mammals

Available data for secondary toxicity (consumption of prey that have ingested bromadiolone) to 

birds and mammals are presented in Table 5.

Table 5. Summary of Secondary Exposure Hazards of Bromadiolone to Birds and 

Mammals (Laboratory Studies)

Predator/

Scavenger 

Species

Prey 

Offered

Number of 

Prey 

Offered 

Daily per 

Predator/

Scavenger

Number of Predators 

per Exposure 

Duration

Number of 

Dead 

Predators/

Scavengers

Signs of 

Toxicity in 

Survivors MRID

Barn owl

(Tyto alba)

Rats fed 

choice of 

0.005% bait 

or untreated 

bait for 5 

days.

1-2 1 for 1 day

2 for 3 days

1 for 6 days

2 for 10 days

All observed for 20 

days.

0

0

0

1

None

46750931

40072202

Barn owl

(Tyto alba)

Mice were 

fed 

commercial 

bait (% ai 

was not 

reported) and 

allowed to 

die.

2-3 6 for 1 day

6 for 3 days

6 for 6 days

0

0

0

Increased 

blood 

coagulation 

time, 

returning to 

normal after 

10 days.

48590804

Stone marten

(Martes foina)

Yellownecked field 

mice fed 

0.005% bait 

in excess to 

feed for 4 

days.

4 - 8 2 for 1 day

2 for 4 days

All observed for 3 

weeks.

0

0

Increased 

fragility of 

small blood 

vessels of the 

muscles on 

top of the 

skull for 

individuals

exposed for 

4 days.

48590802
12

Predator/

Scavenger 

Species

Prey 

Offered

Number of 

Prey 

Offered 

Daily per 

Predator/

Scavenger

Number of Predators 

per Exposure 

Duration

Number of 

Dead 

Predators/

Scavengers

Signs of 

Toxicity in 

Survivors MRID

Mongoose

(Herpestes 

auropunctatus)

Black or 

Norway rats 

fed 0.005%

bait for 5 

days.

1 2 for 1 day

2 for 3 days

2 for 5 days

2 for 6 days

All observed until 

death or 10 days.

0

1

2

2

Not reported

00157732

Coyote

(Canis latrans)

Ground

squirrels fed

15 g of

0.01% bait

for 3 days.

1 4 adults for 5 days

3 sub-adults for 5 days

All followed until 

death or 30 days posttreatment.

0

2

2 coyotes 

stopped

feeding for 8 

and 16 days, 

but resumed 

feeding and 

survived 

until the end 

of the study.

00162324

4.3. Incident Databases Review

Reviews were conducted of the Ecological Incident Information System (EIIS, version 2.1.1)11, 

the Agency’s Aggregated Incidents Reports database, and the Avian Incident Monitoring System 

(AIMS)12 on 12/21/2015. Incidents associated with bromadiolone were reported in all three 

databases; however, all of the 27 incidents reported in AIMS were also reported in EIIS.

There were 187 incidents reported in EIIS in association with bromadiolone, all involved either 

birds or mammals. It appears likely that some mortalities were caused by primary exposure to 

bromadiolone bait and others by secondary exposure routes. Among those incidents, 124 were 

classified as possible (50), probable (35), or highly probable (39) in terms of the certainty of the 

association with bromadiolone exposure and the remaining 63 were classified as either unlikely 

or unrelated to bromadiolone exposure. The group of 124 (i.e., higher certainty incidents) 

occurred between 1983 and 2014 (note: dates are not available for all incidents) and among the 

individual incidents, the legality of bromadiolone use was unknown for the majority (100), a 

registered use for 21, and a misuse for only three. The EIIS database also includes reports of

residues in animals. Although some of these residue data were associated with the 187 incidents, 

residue data were also reported for animals that were not dead or moribund at the time of 

sampling (e.g., some samples were collected as part of a long term genetics and population 

study).

Three minor wildlife incidents were reported in the Aggregated Incidents Reports database; two 

occurred in 1998 and the other in 2005.

 11 http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/technical-overview-ecological-riskassessment-risk 12 http://www.abcbirds.org
13

The total number of actual incidents associated with the use of bromadiolone may be higher than 

what is reported to the Agency. Incidents may go unreported for a variety of reasons such as 

affected organisms were not found and effects were not immediately apparent or readily 

attributed to the use of a chemical. As such, the absence of incident reports cannot be construed 

as the absence of incidents and likewise the number of incident reports cannot be assumed to 

fully account for the actual number of incidents.

5. Exposure Pathways of Concern

There is potential for exposure to non-target animals primarily through two different pathways: 

(1) animals may directly consume bait (i.e., primary exposure) or (2) animals may consume prey 

that have ingested bait (i.e., secondary exposure). It is assumed that exposure may occur from 

both pathways for all outdoor uses (above ground bait stations, burrow, and sewer).

Furthermore, it is assumed that indoor uses of bromadiolone may result in outdoor exposure 

through secondary poisoning (i.e., prey mammals obtain exposure indoors and then travel 

outdoors). Aquatic exposure (i.e., uptake of dissolved bromadiolone from water) is assumed to 

be negligible.

13

Screening Imbibition Program

The Screening Imbibition Program (SIP v.1.0)14 is typically used in the Problem Formulation 

stage of Registration Review to calculate an upper-bound estimate of bird and mammal exposure 

to a pesticide in drinking water. Aquatic exposure to bromadiolone is assumed to be negligible; 

therefore, the screen was not performed.

Screening Tool for Inhalation Risk 

The Screening Tool for Inhalation Risk (STIR v.1.0)14 was used to provide an upper-bound 

estimate of exposure of birds and mammals to bromadiolone through inhalation of vapor (droplet 

inhalation is not applicable to bait uses). The screening suggests that bromadiolone exposure is 

not likely significant enough for an inhalation risk concern. Appendix B provides model results.

6. Analysis Plan

In order to address the risk hypothesis, the potential for adverse effects on the environment is 

estimated. The use, environmental fate, and ecological effects of bromadiolone will be 

characterized and integrated to assess risk. This will be accomplished using a risk quotient (RQ; 

ratio of exposure concentration to effects concentration) approach. Although risk is often 

defined as the likelihood and magnitude of adverse ecological effects, the risk quotient-based 

approach does not provide a quantitative estimate of likelihood or magnitude of an adverse 

effect. However, as outlined in the Overview Document (USEPA, 2004), the likelihood of 

effects to individual organisms from particular uses of bromadiolone will be estimated using the 

 13 The product is not intended to be placed into or come into contact with the sewer water. The concern for sewer 

use is both in the sewer (i.e., non-target organisms may visit sewers) and below the sewer discharge (e.g., chunks of 

bait blocks could be knocked or broken off as bait is eaten, discharged with stormwater or sewage overflow, and 

then consumed by non-target organisms) since the product is not required to be confined in a secured bait station. 14 http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/models-pesticide-risk-assessment
14

probit dose-response slope and either the level of concern or actual calculated risk quotient 

value.

This analysis plan will be revisited and may be revised depending upon a full review of the data 

available in the open literature and the information submitted by the public in response to the 

opening of the Registration Review docket.

6.1. Stressors of Concern

Ecological Risk Assessment

Bromadiolone will be considered the stressor of concern in the ERA.

Two major degradates (forming > 10% of applied bromadiolone) were identified in the aerobic 

soil metabolism study (metabolite 1; 1,3-diphenyl-5(4’-bromo-biphenyl pentane-1-ol and 

metabolite 3; 1,3-diphenyl-5(4’-bromo-biphenyl pentane-1,5-diol). Risk from exposure to these 

degradates is not considered a concern because the main risk concern is expected to be attributed 

to primary exposure from direct consumption of bait products and secondary exposure from 

consumption of prey that ingested bait. Furthermore, contamination of soil and water from use 

of bait products is expected to be minimal. Therefore, the degradation products are not 

considered stressors of concern for the risk assessment.

Drinking Water Assessment

Drinking water degradates of concern have not been identified. EFED does not anticipate 

conducting a drinking water assessment because exposure is expected to be minimal.

6.2. Measures of Exposure

Outdoor uses of bromadiolone will be modeled using the maximum concentrations of 

bromadiolone in bait and maximum residues in animals that ingested bromadiolone. 

The most current models and methodologies will be used at the time of the risk assessment.

Aquatic Exposure 

Potential for aquatic exposure is assumed negligible based on the use patterns; therefore, EFED 

does not anticipate conducting an aquatic risk assessment.

Terrestrial Exposure

There is potential for exposure to non-target animals primarily through two different pathways: 

(1) animals may directly consume bait (i.e., primary exposure) or (2) animals may consume prey 

that have ingested bait (i.e., secondary exposure). EFED does not currently have specific models 

for these exposure pathways; nonetheless, exposure can be estimated from product information, 

empirical residue data, and assumptions about the non-target animals. 
15

Exposure from primary consumption will be estimated on both a dose and dietary basis using the 

concentration of bromadiolone in the formulated bait (dietary and dose concentrations) and 

information about the body weight and food consumption rates of the non-target animal (dose 

concentration). 

Secondary exposure will be estimated in a similar way (dose and dietary-based concentrations); 

however, residues in the prey will be used instead of bait concentrations. One approach is to use 

empirical bromadiolone residue data. Three studies are available that measured residues in 

tissues of animals that ingested bromadiolone (MRID 48590803, 48590801, and 

00162324/00162325); the highest whole-body average residue was 1.83 ± 0.96 mg ai/kg-carcass. 

Those studies as well as any in the open literature will be considered when estimating potential 

secondary exposure. 

Primary and secondary exposure will be estimated for single feedings and for multiple feedings 

over a period of consecutive days. This is because bromadiolone may provide a lethal dose after 

a single feeding; however, death is usually delayed for a period of days. Therefore, animals may 

continue to consume bait for several days before dying and may potentially receive a total dose 

that exceeds the lethal dose. Furthermore, repeated sublethal exposure may result in the 

accumulation of a lethal dose given that bromadiolone is expected to accumulate and be retained 

for a period of time in the liver. Single feeding and multiple feeding exposure estimates will be 

estimated in a similar way except that multiple feeding exposure estimates will incorporate

bromadiolone elimination using the longest available half-life value in liver (MRID 4259680115). 

The risk assessment may further characterize risk using any additional half-life data that are 

available.

Exposure to terrestrial plants is possible but unlikely and considered negligible given the use 

pattern (above-ground outdoor use contained in a bait box, below-ground outdoor use in 

burrows, and sewers).

6.3. Measures of Effect

Toxicity effects data will be used as measures of direct and indirect effects to biological 

receptors (USEPA, 2004). As discussed previously, data will be obtained from registrantsubmitted studies and from literature studies identified in ECOTOX.

Quantitative assessment of risks will be based on study endpoints that can be directly linked to 

the Agency’s assessment endpoints of impaired survival, growth, and reproduction. Sub-lethal 

effects (e.g., lethargy and changes in coloration) will be evaluated qualitatively. Available 

incident data will be used to further characterize risk.

6.4. Integration of Exposure and Effects

The exposure and effects data will be integrated in order to evaluate potential adverse ecological 

effects on non-target species. The risk quotient method will be used to compare exposure and 

measured toxicity values. EECs will be divided by acute and chronic toxicity values. The 

 15 The available study showed a bi-exponential decline of bromadiolone residues in the liver. The t1/2 = 17 days for 

the first 28 days after dosing and the t1/2 = 318 days including the period following the first 28 days after dosing.
16

resulting RQs will be compared to the Agency’s Levels of Concern (LOC) (USEPA, 2004). 

Additional metrics may be used to characterize the likelihood of mortality to non-target 

organisms.

6.5. Endangered Species Assessments

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

evaluate risks to federally listed threatened and endangered (listed) species from registered uses 

of pesticides in accordance with the Joint Interim Approaches developed to implement the 

recommendations of the April 2013 National Academy of Sciences (NAS) report, Assessing 

Risks to Endangered and Threatened Species from Pesticides. The NAS report16 outlines 

recommendations on specific scientific and technical issues related to the development of 

pesticide risk assessments that EPA and the Services (U.S. Fish and Wildlife Service and 

National Marine Fisheries) must conduct in connection with their obligations under the ESA and 

FIFRA. EPA will address concerns specific to bromadiolone in connection with the 

development of its final registration review decision for bromadiolone. 

In November 2013, EPA, the Services, and USDA released a white paper containing a summary 

of their joint Interim Approaches for assessing risks to listed species from pesticides. These 

Interim Approaches were developed jointly by the agencies in response to the NAS 

recommendations, and reflect a common approach to risk assessment shared by the agencies as a 

way of addressing scientific differences between the EPA and the Services. Details of the joint 

Interim Approaches are contained in the November 1, 2013 white paper, Interim Approaches for 

National-Level Pesticide Endangered Species Act Assessments Based on the Recommendations 

of the National Academy of Sciences April 2013 Report. 17

Given that the agencies are continuing to develop and work toward implementation of the 

Interim Approaches to assess the potential risks of pesticides to listed species and their 

designated critical habitat, this ecological problem formulation supporting the Preliminary Work 

Plan for bromadiolone does not describe the specific ESA analysis, including effects 

determinations for specific listed species or designated critical habitat, to be conducted during 

registration review. While the agencies continue to develop a common method for ESA analysis, 

the planned risk assessment for the registration review of bromadiolone will describe the level of 

ESA analysis completed for this particular registration review case. This assessment will allow 

EPA to focus its future evaluations on the types of species where the potential for effects exists, 

once the scientific methods being developed by the agencies have been fully vetted. Once the 

agencies have fully developed and implemented the scientific methods necessary to complete 

risk assessments for listed species and their designated critical habitats, these methods will be 

applied to subsequent analyses of bromadiolone as part of completing this registration review.

 16 http://www.nap.edu/catalog/18344/assessing-risks-to-endangered-and-threatened-species-from-pesticides 17 http://www2.epa.gov/endangered-species/interim-approaches-pesticide-endangered-species-act-assessmentsbased-nas-report
17

6.6. Endocrine Disruptor Screening

As required by Federal Food, Drug and Cosmetic Act (FFDCA) section 408(p), bromadiolone is 

subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP).

18 

Bromadiolone was not in the first group of pesticide active ingredients screened under the EDSP.

6.7. Drinking Water Assessment

A drinking water assessment will not be performed for the Registration Review of bromadiolone 

because exposure through drinking water is expected to be minimal. There has never been a

drinking water assessment performed for bromadiolone.

6.8. Preliminary Identification of Data Gaps

Available studies submitted to fulfill environmental fate and ecological effects guideline 

requirements, as well as outstanding data gaps for bromadiolone are defined in Sections 6.8.1 

and 6.8.2, respectively. Studies are identified that offer data for each guideline requirement, as 

well as study classifications and whether or not further data are needed in order to support the 

risk assessment.

6.8.1. Environmental Fate Data

Environmental fate data gaps for bromadiolone are indicated in the table below (Table 6). There 

are many data gaps identified, but the exposure modeling envisioned for the ecological risk 

assessment would not benefit from requesting additional data at this time. 

Table 6. Environmental Fate Data and Data Gaps for Bromadiolone

Guideline Description MRID Classification Data Gap? Comments

835.2120 Hydrolysis 42237501 Acceptable No 1 Studies are not recommended at 

this time because aquatic 

exposure is assumed negligible.

2 Studies are not recommended at 

this time because terrestrial 

exposure estimates are assumed 

to be either non-degraded bait, 

measured residues in tissues of 

animals that ingested 

bromadiolone, or estimated 

residues in tissues of animals that 

ingested bromadiolone. In the 

case of estimated residues, halflives in liver will be used to 

account for degradation.

835.2240 Aqueous 

photolysis

- - Yes1

835.2410 Soil photolysis - - Yes2

835.4100 Aerobic soil 

metabolism

43594301 Acceptable for 

the one soil 

assessed. A 

total of four 

soils are 

needed to 

satisfy the data 

requirement

Yes1,2

835.4200 Anaerobic soil 

metabolism

- - Yes2

835.4300 Aerobic aquatic 

metabolism

- - Yes1

835.4400 Anaerobic 

aquatic 

metabolism

- - Yes1

 18 http://www2.epa.gov/endocrine-disruption
18

Guideline Description MRID Classification Data Gap? Comments

835.1230

835.1240

Adsorption/ 

desorption and 

leaching

- - Yes1

835.6100 Terrestrial field 

dissipation

- - Yes2

835.6200 Aquatic field 

dissipation

- - Yes1

850.6100 Analytical 

method in soil

- - Yes2

Analytical 

method in water

- - Yes1

850.1730 Fish 

bioconcentration

00161965 Supplemental No

BOLD = Recommended Studies

6.8.2. Ecological Effects Data

Data gaps for bromadiolone remain (Tables 7, 8, and 9); however, some of these studies are 

anticipated to have little impact on the risk assessment and are not recommended for a DCI. 

EFED recommends requesting the following studies to reduce uncertainty in the risk assessment:

• 850.2100: Avian oral toxicity (passerine species) (bromadiolone; TGAI)19

• 850.2300: Avian reproduction (upland game species) (bromadiolone; TGAI)

• 850.2300: Avian reproduction (waterfowl species) (bromadiolone; TGAI)

In addition, non-guideline data on toxicity to terrestrial invertebrates other than the honeybee 

may be useful for reducing uncertainty in the risk assessment.

Toxicity data from other sources (e.g., other anticoagulants) may be used in the absence of data 

for bromadiolone. Use of surrogate data may over or underestimate risk of bromadiolone use.

Table 7. Ecological Effects Data Requirements (TGAI) for Aquatic Organisms Exposed to 

Bromadiolone and Data GapsA

Guideline Description MRID Classification Data 

Gap? Comments

850.1075

Acute freshwater fish 

toxicity

(cold water species)

00070140 Acceptable1 No

1 In some cases an older 

classification scheme was 

reported in the DER. 

Studies classified as “core” 

are equivalent to 

“acceptable”.

2 Studies are not 

recommended at this time 

Acute freshwater fish 

toxicity

(warm water species)

00070141 Acceptable1 No

Acute estuarine/

marine fish toxicity - - Yes2

 19 The observation period should be extended beyond that of a standard 850.2100 study (14 days) given that effects 

from bromadiolone poisoning are not immediate (i.e., it should be long enough to capture effects of bromadiolone 

poisoning and continue until evidence of toxicity has subsided).
19

Guideline Description MRID Classification Data 

Gap? Comments

850.1010 Acute toxicity to 

freshwater invertebrates

00070685

42093302

Acceptable1

Acceptable1 No

because potential exposure 

is assumed negligible based 

on the use pattern. 

850.1025 Acute estuarine/

marine mollusk toxicity - - Yes2

850.1035

Acute estuarine/

marine invertebrate 

toxicity

- - Yes2

850.1300 Freshwater invertebrate 

life cycle - - Yes2

850.1350 Saltwater invertebrate 

life cycle - - Yes2

850.1400

Freshwater fish early 

life stage - - Yes2

Saltwater fish early life 

stage - - Yes2

850.1500

Freshwater fish life 

cycle - - No

Saltwater fish life cycle - - No

850.1735

Whole sediment acute 

toxicity, freshwater 

invertebrates

- - No

850.1740

Whole sediment 

chronic toxicity, marine 

invertebrates

- - Yes2

-

Whole sediment 

chronic toxicity, 

freshwater invertebrates

- - Yes2

-

Whole sediment 

chronic toxicity, 

marine-estuarine 

invertebrates

- - Yes2

850.5400A

Aquatic plant growth

(freshwater green alga) - - Yes2

Aquatic plant growth 

(freshwater diatom) - - Yes2

Aquatic plant growth 

(saltwater diatom) - - Yes2

850.5400A Aquatic plant growth 

(Cyanobacteria) - - Yes2
20

Guideline Description MRID Classification Data 

Gap? Comments

850.4400A Aquatic plant growth 

(vascular plants) - - Yes2

AAs of July 2012 the new guideline numbers are 850.4500 (Algal toxicity) and 850.4550 (Cyanobacteria toxicity)

BOLD = Recommended Studies

Table 8. Ecological Effects Data Requirements (TGAI) for Terrestrial Animals Exposed to 

Bromadiolone and Data GapsA

Guideline Description MRID Classification Data 

Gap?

Comments

850.2100

Avian acute oral 

toxicity

(upland game or 

waterfowl species)

00143279

44000201

Acceptable1

In Review No

1 In some cases an 

older classification 

scheme was reported 

in the DER. Studies 

classified as “core” are 

equivalent to 

“acceptable”.

2 Additional studies 

are available with less 

sensitive endpoints 

(Accession #249995; 

supplemental for 

bobwhite quail and 

acceptable for mallard 

duck). Another study 

(MRID 44000202, unreviewed) is available 

for mallard duck; 

however, a cursory 

review of the data 

indicates that the 

observed pattern of 

mortality is not 

suitable for calculation 

of a LC50 value.

3 Studies are not 

recommended at this 

time because potential 

exposure is considered 

negligible for insect 

pollinators given the 

use pattern (sewers, 

above ground outdoors 

contained in bait 

boxes, and below 

ground outdoors).

Avian acute oral 

toxicity (passerine 

species)

- - Yes

850.2200

Avian dietary 

toxicity (upland 

game species)

001432802 Acceptable1 No

Avian dietary 

toxicity 

(waterfowl 

species)

001432782 Acceptable1 No

850.2300

Avian 

reproduction 

(upland game 

species)

- - Yes

850.2300

Avian 

reproduction 

(waterfowl 

species)

- - Yes

850.3020

Adult honeybee 

acute contact 

toxicity 

(Tier 1)

- - Yes3

Non-guideline

Adult honeybee 

acute oral toxicity 

(Tier 1)

- - Yes3,4

Non-guideline

Adult honeybee 

chronic oral 

toxicity (Tier 1)

- - Yes3,4

Non-guideline

Larval honeybee 

acute and chronic 

oral toxicity 

(Tier 1)

- - Yes3
21

Guideline Description MRID Classification Data 

Gap?

Comments

Non-guideline 

Residue in pollen 

and nectar 

(recommendation 

pending risks 

identified in Tier I 

studies) (Tier II)

- - Yes3

4 Non-guideline data 

on toxicity to 

terrestrial invertebrates 

other than the 

honeybee may be 

useful for reducing 

uncertainty in the risk 

assessment. There is 

evidence to suggest 

that toxicity may occur 

and that the exposure 

pathway for exposure 

is complete for certain 

types of invertebrates. 

Evidence has been 

documented of 

terrestrial invertebrates 

consuming bait 

containing an 

anticoagulant 

rodenticide and 

excreting it (Fisher et

al., 2007; HernandezMoreno et al., 2013). 

Furthermore a recent 

study demonstrated 

bromadiolone toxicity 

to earthworms (Liu et 

al., 2015). 

Non-guideline 

Semi-field testing 

for pollinators 

(tunnel and 

feeding studies) 

(recommendation 

pending risks 

identified in Tier I 

studies) (Tier II)

- - Yes3

850.3040

Full-field testing 

for pollinators 

(recommendation 

pending risk 

identified in Tier 

II studies) 

(Tier III) - - Yes3

A In some cases invalid studies were submitted [avian oral toxicity (Accession # 232566 and MRID 

00150982/40101801); avian dietary toxicity with an upland game species (MRID 00088019 and 40101801) and a 

waterfowl species (MRID 00088020)] but valid studies are also available.

BOLD = Recommended Studies

Table 9. Ecological Effects Data Requirements (TEP) for Plants Exposed to Bromadiolone

and Data Gaps

Guideline Description MRID Classification Data 

Gap? Comments

850.4100A

Terrestrial plant 

toxicity (Tier I or Tier 

II seedling emergence)

- - Yes1

1 Studies are not recommended at 

this time because potential 

exposure is assumed negligible 

based on the use pattern. 

850.4150B

Terrestrial plant 

toxicity (Tier I or Tier 

II vegetative vigor)

- - Yes1

A As of July 2012 the Final Guideline 850.4100 contains both Tier I and Tier II test guidance.

B As of July 2012 the Final Guideline 850.4150 contains both Tier I and Tier II test guidance.

BOLD = Recommended Studies
22

7. References

Cox, P. and R.H. Smith. 1992. Rodenticide Ecotoxicology: Pre-lethal Effects of Anticoagulants 

on Rat Behavior. Proceedings of the Vertebrate Pest Conference 15:165-170.

Fisher, P., Spurr, E., Ogilvie, S., and Eason, C. 2007. Bait Consumption and Residual 

Concentrations of Diphacinone in the Wellington Tree Weta (Hemideina crassidens) 

(Orthoptera: Anostostomatidae). New Zealand Journal of Ecology 31(1): 104-110.

Hernandez-Moreno, D., de la Casa-Resino, I., Lopez-Beceiro, A., Fidalgo, L., Soler, F., PerezLopez, M. 2013. Secondary Poisoning of Non-target Animals in an Ornithological Zoo in 

Galicia (NW Spain) with Anticoagulant Rodenticides: A Case Report. Veterinarni 

Medicina, 58(10): 553–559.

Liu, J., Xiong, K., Ye, X., Zhang, J., Yang, Y., Ji, L. 2015. Toxicity and Bioaccumulation of 

Bromadiolone to Earthworm (Eisenia fetida). Chemosphere. 135: 250–256.

Pelfrene, A.F. 1991. Synthetic Organic Rodenticides. Handbook of Pesticide Toxicology, vol. 3: 

Classes of Pesticides, pages 1271-1316. Academic Press, Inc.

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

Programs. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and 

Toxic Substances, Office of Pesticide Programs, Washington DC. January 23, 2004.

USEPA. 2008. Risk Mitigation Decision for Ten Rodenticides. U.S. Environmental Protection 

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

Programs, Washington DC. May 28, 2008.

USEPA. 2011. Risks of Bromadiolone Use to the Federally Threatened Alameda Whipsnake 

(Masticophis lateralis euryxanthus), the Federally Endangered Salt Marsh Harvest Mouse 

(Reithrodontomys raviventris), and the Federally Endangered San Joaquin Kit Fox 

(Vulpes macrotis mutica). Office of Pesticide Programs, U. S. Environmental Protection 

Agency.

USEPA. 2015. Bromadiolone (112001) Label Data Report. Office of Pesticide Programs, 

Biological and Economic Analysis Division. April 14, 2015.
23

APPENDIX A. Names and Structures of Bromadiolone and its Major and 

Minor Degradates

Table A-1

Code Name 

(Synonym) Chemical Name Chemical Structure

Study 

Type MRID

Maximum 

%AR 

(day)

Final %AR 

(study 

length)

PARENT

Bromadiolone

CAS Name:

3-[3-(4'-bromo[1,1'-

biphenyl]-4-yl)-3-

hydroxy-1-

phenylpropyl]-4-

hydroxy-2H-1-

benzopyran-2-one

CAS Number: 

28772-56-7

Formula: C30H23BrO4

MW: 527.42

SMILES: 

c1cc(Br)

ccc1c(cc2)ccc2C(O)

CC(c3ccccc3)C4=C

(O)c5ccccc5OC4

(=O)

Hydrolysis 

pH 5

42237501

NA

91.5 (30)

Hydrolysis 

pH 7 100 (30)

Hydrolysis 

pH 9 100 (30)

Aqueous 

photolysis 00161970 Invalid

Soil 

photolysis 00161971 Invalid

Aerobic 

soil 

metabolism

00161969 Invalid

43594301 64 (365)

Anaerobic 

soil 

metabolism

00161969 Invalid

MAJOR (>10%) TRANSFORMATION PRODUCTS

Bromadiolone 

Ketone

Formula: C30H21BrO4

MW: 525.40

SMILES:

C1(O)c2c(cccc2)

OC(=O)C=1C

(c1ccccc1)CC(=O)

c1ccc(-c2ccc(Br)

cc2)cc1

Aerobic 

soil 

metabolism

43594301 30.7 (7) 4.9 (365)

Metabolite 1

Formula: C29H25BrO

MW: 469.43

SMILES:

c1(-c2ccc(CCC

(c3ccccc3)C=C(O)

c3ccccc3)cc2)ccc

(Br)cc1

Aerobic 

soil 

metabolism

43594301 19.3 (120) 14.9 (365)

Metabolite 3

Formula: C29H25BrO2

MW: 485.42

SMILES:

c1(-c2ccc(C(O)CC

(c3ccccc3)C=C(O)

c3ccccc3)cc2)ccc

(Br)cc1

Aerobic 

soil 

metabolism

43594301 25.7 (270) 24.4 (365)

O O

OH OH

Br

O O

OH O

Br

OH

Br

Br

O O

H

H
24

Code Name 

(Synonym) Chemical Name Chemical Structure

Study 

Type MRID

Maximum 

%AR 

(day)

Final %AR 

(study 

length)

MINOR (<10%) TRANSFORMATION PRODUCTS

Metabolite 2 Unknown Unknown

Aerobic 

soil 

metabolism

43594301 3.0 (60) <DL (365)

Metabolite 4 Unknown Unknown

Aerobic 

soil 

metabolism

43594301 6.4 (120) 4.4 (365)

DL = detection limit
25

APPENDIX B. STIR v.1.0 Inputs and Outputs

 

Table B-1. Input

Application and Chemical Information

Enter Chemical Name Bromadiolone

Enter Chemical Use bait

Is the Application a Spray? (enter y or n) n

If Spray What Type (enter ground or air) not applicable

Enter Chemical Molecular Weight (g/mole) 527.4

Enter Chemical Vapor Pressure (mmHg) 1.00E-08

Enter Application Rate (lb ai/acre) N/A1

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg-bw) 170

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 0.178

Mammal

Enter Lowest Rat Oral LD50 (mg/kg-bw) 0.6

Enter Lowest Rat Inhalation LC50 (mg/L) 0.000432

Duration of Rat Inhalation Study (hr) 4

Enter Rat Weight (kg) 0.35 1 N/A = not applicable. Only vapor dose is applicable to bait applications and application rate does not impact 

estimates of vapor dose.

 2 MRID 41976901

 Table B-2. Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 2.84E-04

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.57E-05

Adjusted Inhalation LD50 4.90E-01

Ratio of Vapor Dose to Adjusted Inhalation LD50 7.29E-05 Exposure not Likely Significant

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

not 

applicable

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50

not 

applicable Not applicable

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 2.84E-04

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 4.48E-05

Adjusted Inhalation LD50 2.56E-02

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.75E-03 Exposure not Likely Significant

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

not 

applicable

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50

not 

applicable Not applicable