Rodenticide Secondar

Exposure and Risk Exposure and Risk

Characterization

Exposure and Risk

Characterization

Presentation to the SAP

November 29th, 2011

Elizabeth Riley, M.S. Elizabeth Riley, M.S.

Environmental Fate and Effects Division

Outline

• Quantitative Approach Quantitative Approach

• Dose-Based RQ Analyses

• Theoretical Exposure• Empirical Exposure

• Dietary RQ Analyses

• Th ti l E Theoretical Exposure• Empirical Exposure

• Opportunity for Lethal Exposure Analy

Opportunity for Lethal Exposure Analy

• Secondary Feeding Studies• Secondary Risk Conclusions Secondary Risk Conclusions
Secondary Exposure an

• Secondary risk is influenced by: Secondary risk is influenced by:

• Toxicity of rodenticides to primary a

secondar

y consumers

• Exposure accumulation and elimin

Exposure accumulation and elimin

of rodenticides in both primary and secondary consumers

• Time to death in primary consumer 
Methodology flow chart: theoretically ba

concentration

Toxicity endpoints Concentration of 

a.i. bait

Half-lif

Scaled toxicity endpoints based

1-day rodenticide intake in 

pre

y via 

Body burdone da

y a

endpoints based

on body weights

p y

allometric food intake equations

y 

day accumscenarios

1 d 

Dose-based exposure RQs based on 1-day accumulation in prey

-day ro

intake in consumeallometri

equation

Dose-based exposure RQs based on multi-day accumulation in prey

# of prey organisms to reach LD50 in secondary consumer
Accumulation of Rodent

• For rodenticides with dela

y y

ed mortalit

y, 

animals may:

• Feed on bait for several days• Accumulate doses that exceed the media

Accumulate doses that exceed the media

dose

• “Accumulation of dose” analysis assess

accumulation potential for the rodenticidaccumulation potential for the rodenticid

the house mouse and Norway rat over t

• Available em

pirical data were used to co

estimated body burdens
Accumulation of Prey Body B

Assumptions

• 100% of 

py y re

y’s diet consists of dr

y bait

• 100% of rodenticide residues in prey are 

bioavailable to the consumer

• Assumed weights for target animals: Assumed weights for target animals:

• house mouse = 23 g• Norwa

y g rat = 485 

g

• Elimination half-lives

• Based on liver for anticoagulants and bloo

plasma for bromethalin plasma for bromethalin

• First order elimination equation
Elimination half-lives used to calculate dose acc

Rodenticide Test Species Compartment Eliminat

hal

f-lif

(days)

Brodifacoum Mouse Liver 307.4

Difethialone Mouse Liver 28.5

Warfarin Mouse Live

r 66.8

Chlorophacinone Mouse Liver 35.4

Diphacinone Pig Liver 5 5.

Bromethalin Rat Blood 5.6
Accumulation Equation for H

Mouse and Norwa

y Ra

t

D

t = (FI * C/(wt(g)/1000)) + d(t-1) 
Window for Accumul

• Time to death: 

• Provides context for dose accumul• Derived from available acute toxici

st di u es
Rodenticide Body Burden in House Mouse 

1000.0

)

W

100.0

mg a.i./kg-bwWoncentration (m Bromethalin (0.01%) B

CD

D

10.0

Rodenticide Co

1.0

1 2

3

4

5

6

R

1 2

3

4

5

6

Days
Rodenticide Body Burden in Norway Rat 

1000.0

)

100.0

(mg a.i/kg-bw Concentration 

10.0

Rodenticide CBromethalin (0.01%) 

1.0

1 2

3

4

5

6

R

1 2

3

4

5

6

Days
Uncertainties

• Elimination half Elimination half

-lives

• Liver half-lives not available for all 

chemicals

• Different study designs may lead to 

lar

ge variation in half-lives reported

• Different species used• De

gree to which liver half-lives 

represent whole body elimination
Rodenticide Intake (mg a.i./kg-bw) in Se

Consumers Based on Consumption o

• Rodenticide intake was based on 

Rodenticide intake was based on 

intake allometric equations and th

concentration of rodenticide in the concentration of rodenticide in the 

species based on:

• Theoretically based prey concentra• Empirically based prey concentratio

(di d l t ) (discusse

d la

ter

)
Body Weight Scaling of 

100 g bird 1000 g bird 5000 g 

American kestrel Red Tailed Hawk Bald E

National Geographic

U.S

U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service

American kestrel Red

-Tailed Hawk Bald E

50 g mammal 1000 g mammal 3000 g m

Least Weasel Mink Kit F

Wikipedia Wikipedia U.S. Fish and Wildlife Service U.S
Methodology flow chart: theoretically ba

concentration

Toxicity endpoints Concentration of 

a.i. bait

Half-lif

Scaled toxicity endpoints based

1-day rodenticide intake in 

pre

y via 

Body burdone da

y an

endpoints based

on body weights

p y

allometric food intake equations

y 

day accumscenarios

1 d 

Dose-based exposure RQs based on 1-day accumulation in prey

-day ro

intake in consumeallometri

equation

Dose-based exposure RQs based on multi-day accumulation in prey

# of prey organisms to reach LD50 in secondary consumer
Secondary Bird RQs Based on 1-Day Accumul

in House Mouse

BrodDife

Warf

War

ChloDiphBrom

100 g 1000 g 5000 g

RQ

0.0001 0.001 0.01 0.1 1 10 100

Level of Co

1-day accumulation3-day accumulation6-day accumulation
Secondary Bird RQs Based on 3-Day Accumul

in House Mouse

BrodDife

Warf

War

Chlo

DiphBromRQ

0.0001 0.001 0.01 0.1 1 10 100

100 g 1000 g 5000 g

Level of Co

1-day accumulation3-day accumulation6-day accumulation
Secondary Bird RQs Based on 6-Day Accumul

in House Mouse

BrodDife

Warf

Warf

ChloDiphBrom

0.0001 0.001 0.01 0.1 1 10 100

RQ

100 g 1000 g 5000 g

Level of Co

* Not applic

1-day accumulation3-day accumulation6-day accumulation
Secondary Bird RQs Based on 1-Day Accum

in Norwa

y Rat

BrodDifet

Warf

Warf

Chlo

DiphBrom

RQ

0.00001 0.0001 0.001 0.01 0.1 1 10 100

100 g 1000 g 5000 g

Level of Co

1-day accumulation3-day accumulation6-day accumulation
Secondary Bird RQs Based on 3-Day Accum

in Norway Rat

BrodDife

War

War

Chlo

DiphBromRQ

0.00001 0.0001 0.001 0.01 0.1 1 10 100

100 g 1000 g 5000 g

Level of Co

1-day accumulation3-day accumulation6-day accumulation
Secondary Bird RQs Based on 6-Day Accum

in Norway Rat

BrodDife

Warf

War

Chlo

DiphBrom

RQ

0.00001 0.0001 0.001 0.01 0.1 1 10 100

100 g 1000 g 5000 g

Level of Co

* Not applic

1-day accumulation3-day accumulation6-day accumulation
Summary: 1-day and multi-day 

dose-based avian RQs

Chemical

Dose-Based RQs Dietary-Based RQs Opportunity 

1 Day 

Prey

Multi Day 

Prey

Empirical 

Prey

1 Day 

Prey

Empirical 

Prey

1 day 

Prey

Multi Day 

Prey

BirdsBrodifacoumDifethialone Warfarin (0 025%) (0.025%)Warfarin (0.054%)ChlorophacinoneDiphacinoneBromethalin No data No data MammalsBrodifacoumDifethialone No data No data Warfarin

(0.025%)Warfarin (0.054%)Chlorophacinone

DiphacinoneBromethalin No data No data No data

All evidence suggest risk Predominant evidence of risk Equivocal evidence of risk All evidence suggest low risk
Secondary Mammal RQs Based on 1-Day Accu

in House Mouse

BrodDife

War

War

ChloDiphBrom

50 g 1000 g 3000 g

RQ

0.1 1 10 100

Level of Co

50

g 1000

g 3000

g

1-day accumulation3-day accumulation6-day accumulation
Secondary Mammal RQs Based on 3-Day Accu

in House Mouse

BrodDife

War

War

Chlo

DiphBromRQ

0.1 1 10 100

50 g 1000 g 3000 g

Level of Co

50

g 1000

g 3000

g

1-day accumulation3-day accumulation6-day accumulation
Secondary Mammal RQs Based on 6-Day Accu

in House Mouse

BrodDife

Warf

War

ChloDiphBromRQ

0.1 1 10 100

50 g 1000 g 3000 g

Level of Co

* Not applic

50

g 1000

g 3000

g

1-day accumulation3-day accumulation6-day accumulation
Secondary Mammal RQs Based on 1-Day Accu

in Norway Rat

BrodDife

Warf

War

ChloDiphBromRQ

0.01 0.1 1 10 100

50 g 1000 g 3000 g

Level of Co

50

g 1000

g 3000

g

1-day accumulation3-day accumulation6-day accumulation
Secondary Mammal RQs Based on 3-Day Accu

in Norway Rat

BrodDife

Warf

War

Chlo

DiphBromRQ

0.01 0.1 1 10 100

50 g 1000 g 3000 g

Level of Co

50

g 1000

g 3000

g

1-day accumulation3-day accumulation6-day accumulation
Secondary Mammal RQs Based on 6-Day Accu

in Norway Rat

BrodDife

Warf

War

Chlo

DiphBromRQ

0.01 0.1 1 10 100

50 g 1000 g 3000 g

Level of Co

* Not applic

50

g 1000

g 3000

g

1-day accumulation3-day accumulation6-day accumulation
Summary: all 1-day and multi-day dose-ba

Chemical

Dose-Based RQs Dietary-Based RQs Opportunity 

1 Day 

Prey

Multi Day 

Prey

Empirical 

Prey

1 Day 

Prey

Empirical 

Prey

1 day 

Prey

Multi Day 

Prey

BirdsBrodifacoumDifethialone Warfarin (0.025%)Warfarin (0.054%)ChlorophacinoneDiphacinoneBromethalin No data No data MammalsBrodifacoumDifethialone No data No data Warfarin

(0.025%)Warfarin (0.054%)Chlorophacinone

DiphacinoneBromethalin No data No data No data

All evidence suggest risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggest low risk
RQS BASED ON RQS BASED ON

THEORETICAL BODY 

BURDENS IDENTIFY RISKRQS BASED ON

THEORETICAL BODY 

BURDENS IDENTIFY RISK BURDENS BURDENS IDENTIFY IDENTIFY RISK... 

... HOW DO EMPIRICAL DA

HOW DO EMPIRICAL DA

COMPAR

... HOW DO EMPIRICAL DA

COMPAR
Methodology flow chart: empirically bas

concentration

Measured bod

Toxicity endpoints

Measured bodburden in pre

1 d d i 

Scaled toxicity endpoints based 

-day ro

dentic

intake in seconconsumer via allometric foo

on body weights

Dose-based RQs

intake equatio
Mean Measured Rodenticide Residues in 

Consumers

B 

ro 

Dif

Wa

Ch

DipB 

0.1 1 10 100 1000

Bro

mg a.

Mean residue value select
Comparison of Theoretical and Em

Body-burden values 

(m

g a.i./kg

Comparison of Theoretical and Em

Body-burden values 

(g g m

g a.i./kg

Rodenticide

mg 

a.i./kg 

bait

Theoretical Empirical

Species Concentration (1 - 6 Species Mean 

bait day feeding) Concentration C

Brodifacoum 50 Norway Rat 2.1 – 12.5 Rat 6.98 

Difethialone 25 Norway Rat 1.0 – 5.9 Rat 3.1 Warfarin 200 House 

Mouse

31.7 – 185.1 Mouse 2.95 

Chlorophacin 50 House 7.9

– 45.2 Vole 1.58 

one

50

Mouse

7.9 45.2 Vole 1.58 

Diphacinone 50 Norway Rat 2.1 – 9.4 Ground Squirrel 1.4 
Secondary Bird Acute RQs: Empirica

pre

y concentration analysis

Secondary Bird Acute RQs: Empirica

py y re

y concentration analysis

BroDif

Wa

ChlDipBro

0.00001 0.0001 0.001 0.01 0.1 1 10 100

100 g 1000 g 5000 g

Level of Co

1-day accumulation 6-day accumulation 3-day accumulation Empirical
Secondary Bird Acute RQs: Empirica

pre

y concentration analysis

Secondary Bird Acute RQs: Empirica

py y re

y concentration analysis

BroDif

Wa

ChlDipBro

0.00001 0.0001 0.001 0.01 0.1 1 10 100

100 g 1000 g 5000 g

Level of Co

1-day accumulation 6-day accumulation 3-day accumulation Empirical

* No empiri
Secondary Mammal Acute RQs: Em

based 

pre

y concentration anal

Secondary Mammal Acute RQs: Em

based 

py 

re

y concentration anal

BroDif

Wa

ChlDipBro

0.01 0.1 1 10 100

Level of Co

50 g 1000 g 3000 g

1-day accumulation 6-day accumulation 3-day accumulation Empirical
Secondary Mammal Acute RQs: Em

based 

pre

y concentration anal

Secondary Mammal Acute RQs: Em

based 

py 

re

y concentration anal

BroDif

Wa

ChlDipBro

0.01 0.1 1 10 100

Level of Co

50 g 1000 g 3000 g

1-day accumulation 6-day accumulation 3-day accumulation Empirical

* No empiri
Uncertainties

• Whole carcass residue data Whole carcass residue data

• Difficult to quantify exposure in fi

st di u es

• No data available for bromethalin
Summary: all dose-based RQs

Chemical

Dose-Based RQs Dietary-Based RQs Opportunity 

1 Day 

Prey

Multi Day 

Prey

Empirical 

Prey

1 Day 

Prey

Empirical 

Prey

1 day 

Prey

Multi Day 

Prey

BirdsBrodifacoumDifethialone Warfarin (0 025%) (0.025%)Warfarin (0.054%)ChlorophacinoneDiphacinoneBromethalin No data No data MammalsBrodifacoumDifethialone No data No data Warfarin

(0.025%)Warfarin (0.054%)Chlorophacinone

DiphacinoneBromethalin No data No data No data

All evidence suggest risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggest low risk
SINGLE DAY ANALYSES DO N

SINGLE DAY ANALYSES DO N

ALLOW FOR ACCUMULATION 

THE SECONDARY CONSUMERSINGLE DAY ANALYSES DO N

ALLOW FOR ACCUMULATION 

THE SECONDARY CONSUMER THE SECONDARY SECONDARY CONSUMER CONSUMER

... IS THERE A WAY TO EMPIRIC

ACCOUNT FOR 
Dietary-Based RQ Metho

1. Estimate rodenticide concentratio

primary consumers 

• Theoretical analysis: single day 

accumul ti i a on scenario

• Empirical analysis: mean measure

whole

-carcass residues carcass residues

2. Compare the estimated concentr

Compare the estimated concentr

in primary consumers to un-adjusLC50 toxicity values
Secondary Bird Dietary RQs

Birds

Chemical

Theoretical

Consuming Empirical

House Mouse

Consuming 

Norway Rat

Brodifacoum Brodifacoum 17 8. * 4 71 . * 5 25 . *Difethialone 20.7* 5.48* 5.54*Warfarin (0.025%) 0.19 0.05 < 0.01Warfarin (0.054%) 0.41 0.11Chlorophacinone 0.32 0.09 0.02Diphacinone 0.02 <0.01 < 0.01Bromethalin 0.20 0.05 No dataBolded (*) RQs exceed acute risk LOC (0.5).
Secondary Mammal Dietary R

Mammals

Chemical

Theoretical

Consuming Empirical

House Mouse

Consuming 

Norway Rat

Brodifacoum Brodifacoum 44 7. * 11 2. * 13 17 . *Difethialone No data No data No dataWarfarin (0.025%) 26.6* 7.05* 0.67*

Warfarin (0.054%) 57.5* 15.2*

Chlorophacinone 20.42* 5.41* 1.39*Diphacinone 10.1* 2.68* 0.61*Bromethalin No data No data No dataBolded (*) RQs exceed acute risk LOC (0.5).
Summary: all RQ analyses

Chemical

Dose-Based RQs Dietary-Based RQs Opportunity 

1 Day 

Prey

Multi Day 

Prey

Empirical 

Prey

1 Day 

Prey

Empirical 

Prey

1 day 

Prey

Multi Day 

Prey

BirdsBrodifacoumDifethialone Warfarin (0.025%)Warfarin (0.054%)ChlorophacinoneDiphacinoneBromethalin No data No data No data No data MammalsBrodifacoumDifethialone No data No data Warfarin (0.025%)Warfarin (0.054%)ChlorophacinoneDi h i p

hacinone

Bromethalin No data No data No data

All evidence suggest risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggest low risk
NOW THAT WE HAVE NOW THAT WE HAVE

IDENTIFIED AREAS OF RIS

NOW THAT WE HAVE

IDENTIFIED AREAS OF RIS

... HOW PLAUSIBLE AR

E 

RISK CONCLUSIO
Methodology flow chart: relative opportu

lethal exposure

Toxicity endpoints Concentration of 

a.i. bait

Half-lif

Scaled toxicity endpoints based

1-day rodenticide intake in 

pre

y via 

Body burdone da

y an

endpoints based

on body weights

p y

allometric food intake equations

y 

day accumscenarios

1 d 

Dose-based exposure RQs based on one-day accumulation in prey

-day ro

intake in consumeallometri

equation

Dose-based exposure RQs based on multi-day accumulation in prey

# of prey organisms to reach LD50 in secondary consumer
IS THIS REASONABLY EXPECTED TO O

100 g bird consuming house mouse: 1-day accu

BrodDife

Warf

Warf

ChloDiphBrom

# of m

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00
IS THIS REASONABLY EXPECTED TO O

1000 g bird consuming house mouse: 1-day acc

BrodDife

Warf

Warf

ChloDiphBrom

# of m

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00
IS THIS REASONABLY EXPECTED TO O

5000 g bird consuming house mouse: 1-day acc

BrodDife

Warf

Warf

ChloDiphBrom

# of m

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00
IS THIS REASONABLY EXPECTED TO O

100 g bird consuming house mouse: 6-day accu

BrodDife

Warf

War

ChloDiphBrom

# of m

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00
IS THIS REASONABLY EXPECTED TO O

1000 g bird consuming house mouse: 6-day acc

BrodDife

Warf

War

ChloDiphBrom

# of m

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00
IS THIS REASONABLY EXPECTED TO O

5000 g bird consuming house mouse: 6-day acc

BrodDife

Warf

War

ChloDiphBrom

# of m

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00
IS THIS REASONABLY EXPECTED TO O

100 g bird consuming Norway rat: 1-day accum

BrodDife

War

War

ChloDiphBrom

# of ra

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00
IS THIS REASONABLY EXPECTED TO O

1000 g bird consuming Norway rat: 1-day accu

BrodDife

War

War

ChloDiphBrom

# of ra

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00
IS THIS REASONABLY EXPECTED TO O

5000 g bird consuming Norway rat: 1-day accu

BrodDife

War

War

ChloDiphBrom

# of ra

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00
IS THIS REASONABLY EXPECTED TO O

100 g bird consuming Norway rat: 6-day accum

BrodDifet

Warf

Warf

Chlo

DiphBrom

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00

# of rat
IS THIS REASONABLY EXPECTED TO O

1000 g bird consuming Norway rat: 6-day accu

BrodDifet

Warf

Warf

Chlo

DiphBrom

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00

# of rat
IS THIS REASONABLY EXPECTED TO O

5000 g bird consuming Norway rat: 6-day accu

BrodDifet

Warf

Warf

Chlo

DiphBrom

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00

# of rat
IS THIS REASONABLY EXPECTED TO O

50 g mammal consuming house mouse: 1-day ac

BrodDifet

Warf

Warf

Chlo

DiphBrom

# of mi

0.01 0.10 1.00 10.00 100.00
IS THIS REASONABLY EXPECTED TO O

1000 g mammal consuming house mouse: 1-day a

BrodDifet

Warf

Warf

Chlo

DiphBrom

# of mi

0.01 0.10 1.00 10.00 100.00
IS THIS REASONABLY EXPECTED TO O

3000 g mammal consuming house mouse: 1-day a

BrodDifet

Warf

Warf

Chlo

DiphBrom

0.01 0.10 1.00 10.00 100.00

# of mi
IS THIS REASONABLY EXPECTED TO O

50 g mammal consuming house mouse: 6-day ac

BrodDifet

Warf

Warf

Chlo

DiphBrom

# of mi

0.01 0.10 1.00 10.00 100.00
IS THIS REASONABLY EXPECTED TO O

1000 g mammal consuming house mouse: 6-day a

BrodDifet

Warf

Warf

Chlo

DiphBrom

# of mi

0.01 0.10 1.00 10.00 100.00
IS THIS REASONABLY EXPECTED TO O

3000 g mammal consuming house mouse: 6-day a

BrodDifet

Warf

Warf

Chlo

DiphBrom

# of mi

0.01 0.10 1.00 10.00 100.00
IS THIS REASONABLY EXPECTED TO O

50 g mammal consuming Norway rat: 1-day accu

BrodDife

War

War

Chlo

DiphBrom

# of ra

0.00 0.01 0.10 1.00 10.00 100.00
IS THIS REASONABLY EXPECTED TO O

1000 g mammal consuming Norway rat: 1-day acc

BrodDife

War

War

Chlo

DiphBrom

# of ra

0.00 0.01 0.10 1.00 10.00 100.00
IS THIS REASONABLY EXPECTED TO O

3000 g mammal consuming Norway rat: 1-day acc

BrodDife

War

War

Chlo

DiphBrom

# of ra

0.00 0.01 0.10 1.00 10.00 100.00
IS THIS REASONABLY EXPECTED TO O

50 g mammal consuming Norway rat: 6-day accu

BrodDife

Warf

Warf

ChloDiphBrom

# of rat

0.00 0.01 0.10 1.00 10.00 100.00
IS THIS REASONABLY EXPECTED TO O

1000 g mammal consuming Norway rat: 6-day acc

BrodDife

Warf

Warf

ChloDiphBrom

# of rat

0.00 0.01 0.10 1.00 10.00 100.00
IS THIS REASONABLY EXPECTED TO O

3000 g mammal consuming Norway rat: 6-day acc

BrodDife

Warf

Warf

ChloDiphBrom

# of rat

0.00 0.01 0.10 1.00 10.00 100.00
Summary: opportunity to f

Chemical

Dose-Based RQs Dietary-Based RQs Opportunity 

1 Day 

Prey

Multi Day 

Prey

Empirical 

Prey

1 Day 

Prey

Empirical 

Prey

1 day 

Prey

Multi Day 

Prey

BirdsBrodifacoumDifethialone Warfarin (0.025%)Warfarin (0.054%)ChlorophacinoneDiphacinoneBromethalin No data No data No data No data MammalsBrodifacoumDifethialone No data No data Warfarin (0.025%)Warfarin (0.054%)ChlorophacinoneDiphacinoneBromethalin No data No data No data

All evidencesuggest risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggest low risk
Alternate Assumpti

• Alternate assumptions that may alt

Alternate assumptions that may alt

these conclusions include:

• Potential for increased sensitivity in s

Potential for increased sensitivity in s

species of secondary consumers

• Potential that heavy rodent control in 

Potential that heavy rodent control in 

areas may lead to more than a chancencounte

r

• Accumulation in secondary consume

over time
SECONDARY FEEDING SECONDARY FEEDING

STUDIES PROVIDE AN 

ADDITIONAL LINE OFSECONDARY FEEDING

STUDIES PROVIDE AN 

ADDITIONAL LINE OF ADDITIONAL LINE OF

EVIDENCE... 

ADDITIONAL LINE OF

EVIDENCE... 

... DO THEY SUPPORT 

RISK CONCLUSI
Purpose

• Secondary p studies provide:

• useful information on the potential 

effects from rodenticide exposure tmay occur under field conditions

• an empirical confirmation of estima

prey concentration and subsequenanalyses
Uncertainties

• Small N size• Different study designs• Difficult to 

q yp uantif

y ex

posure

• Difficult to determine the sensitivity o

exposed animals

• No bird or mammal data available 

fo

difethialone 

• No bird data available for bromethal

No bird data available for bromethal
Types of Studies Ava

• Secondar

y y toxicit

y studies are availa

for several species of predator and scavenger birds and mammals, suc

• Raptors passeriforms charadriiforms Raptors, passeriforms, charadriiforms• Canids, mustelids, procyonids

• Birds and mammals were fed: 

• Rats, , mice voles fed on rodenticide ba• Spiked meat
Secondary feeding study mortality occu

(# of available studies)

Chemical Birds Mamma

Brodifacoum Yes (12) Yes (4)

Difethialone No data No data

Warfarin Yes (4) Yes (7)

Chlorophacinone No (8) Yes (8) Yes (8)

Diphacinone Yes (3) Yes (3)

Bromethalin No data No (1)
Summary: secondary feeding s

Chemical

Dose-Based RQs Dietary-Based RQs Opportunity 

1 Day 

Prey

Multi Day 

Prey

Empirical 

Prey

1 Day 

Prey

Empirical 

Prey

1 day 

Prey

Multi Day 

Prey

Bi dr

d

s

BrodifacoumDifethialone Warfarin (0.025%)Warfarin (0.054%)ChlorophacinoneDiphacinoneBromethalin No data No data MammalsBrodifacoumDifethialone No data No data Warfarin

(0.025%)Warfarin (0.054%)Chlorophacinone

DiphacinoneBromethalin No data No data No data

All evidencesuggest risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggest low risk
Secondary Risk Conclus

Chemical

Dose-Based RQs Dietary-Based RQs

Opportunity

Second

Feedi

Studi

Theoretical 

Prey

Empirical 

Prey

Theoretical 

Prey

Empirical 

Prey

BirdsBrodifacoumDifethialone No datWarfarin (0 025%) (0.025%)Warfarin (0.054%)ChlorophacinoneDiphacinoneBromethalin No data No data No datMammalsBrodifacoumDifethialone No data No data No datWfi ar ar n (0.025%)Warfarin (0.054%)Chloro

phacinone

DiphacinoneBromethalin No data No data No data

All evidencesuggest risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggest low risk