Conclusions from Ecolog

Risk Assessment for Risk Assessment for

Rodenticides

Risk Assessment for

Rodenticides

Presentation to the SAP

November 29th, 2011

Dr. Edward Odenkirchen Dr. Edward Odenkirchen

Environmental Fate and Effects Division
Lines of evidence

• Toxicity

• Standard test species

• Risks of Mortality to Primary Consumers

• Single and multiple day dose based RQ• Dietary RQs• Days feeding and mass of bait consumed to reach lethal thr

• Risks of Mortality to Secondary Consumers Risks of Mortality to Secondary Consumers

• Single and multiple day oral dose based RQ

• Theoretical prey concentrations• Empirical prey concentrations

• Dietary RQ Dietary RQ• Secondary feeding studies• # prey animals consumed to reach lethal threshold

• Re

p y orted Incidents of Mortalit

y

• Investigation of primary and secondary route association• Investigation of land use association (urban/suburban vs. ru• Survey of exposure data from open literature
RQs and 

Opportunity Incident Data Conclu

Chemical

Primary 

Risk

Secondary 

Risk Primary Secondary

Urban/ Suburban Primary S

Birds

Brodifacoum

Difethialone No data

Warfarin (0.025%)Warfarin (0 054%) Warfarin (0.054%)

Chlorophacinone

Diphacinone

Bromethalin No data No data No data

Mammals

Brodifacoum

Difethialone

Warfarin (0 025%) Warfarin (0.025%) No data No dataWarfarin (0.054%) No data No data

Chlorophacinone

Diphacinone

Bromethalin No data No data

All evidencesuggests risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggests low risk
RQs and 

Opportunity Incident Data Conclu

Chemical

Primary 

Risk

Secondary 

Risk Primary Secondary

Urban/ Suburban Primary S

Birds

Brodifacoum

Difethialone No data

Warfarin (0.025%)Warfarin (0 054%) Warfarin (0.054%)

Chlorophacinone

Diphacinone

Bromethalin No data No data No data

Mammals

Brodifacoum

Difethialone

Warfarin (0 025%) Warfarin (0.025%) No data No dataWarfarin (0.054%) No data No data

Chlorophacinone

Diphacinone

Bromethalin No data No data

All evidencesuggests risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggests low risk
RQs and 

Opportunity Incident Data Conclu

Chemical

Primary 

Risk

Secondary 

Risk Primary Secondary

Urban/ Suburban Primary S

Birds

Brodifacoum

Difethialone No data

Warfarin (0.025%)Warfarin (0 054%) Warfarin (0.054%)

Chlorophacinone

Diphacinone

Bromethalin No data No data No data

Mammals

Brodifacoum

Difethialone

Warfarin (0 025%) Warfarin (0.025%) No data No dataWarfarin (0.054%) No data No data

Chlorophacinone

Diphacinone

Bromethalin No data No data

All evidencesuggests risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggests low risk
RQs and 

Opportunity Incident Data Conclu

Chemical

Primary 

Risk

Secondary 

Risk Primary Secondary

Urban/ Suburban Primary S

Birds

Brodifacoum

Difethialone No data

Warfarin (0.025%)Warfarin (0 054%) Warfarin (0.054%)

Chlorophacinone

Diphacinone

Bromethalin No data No data No data

Mammals

Brodifacoum

Difethialone

Warfarin (0 025%) Warfarin (0.025%) No data No dataWarfarin (0.054%) No data No data

Chlorophacinone

Diphacinone

Bromethalin No data No data

All evidencesuggests risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggests low risk
RQs and 

Opportunity Incident Data Conclu

Chemical

Primary 

Risk

Secondary 

Risk Primary Secondary

Urban/ Suburban Primary S

Birds

Brodifacoum

Difethialone No data

Warfarin (0.025%)Warfarin (0 054%) Warfarin (0.054%)

Chlorophacinone

Diphacinone

Bromethalin No data No data No data

Mammals

Brodifacoum

Difethialone

Warfarin (0 025%) Warfarin (0.025%) No data No dataWarfarin (0.054%) No data No data

Chlorophacinone

Diphacinone

Bromethalin No data No data

All evidencesuggests risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggests low risk
RQs and 

Opportunity Incident Data Conclu

Chemical

Primary 

Risk

Secondary 

Risk Primary Secondary

Urban/ Suburban Primary S

Birds

Brodifacoum

Difethialone No data

Warfarin (0.025%)Warfarin (0 054%) Warfarin (0.054%)

Chlorophacinone

Diphacinone

Bromethalin No data No data No data

Mammals

Brodifacoum

Difethialone

Warfarin (0 025%) Warfarin (0.025%) No data No dataWarfarin (0.054%) No data No data

Chlorophacinone

Diphacinone

Bromethalin No data No data

All evidencesuggests risk

Predominant evidenceof risk

Equivocal evidenceof risk

All evidencesuggests low risk
Conclusions from all Lines 

E id v ence

• Mammals

– B dif d dif hi l 

Brodifacoum an

d difethi

alone pose a greater r

relative to other assessed rodenticides

– Risks are similar across the other assessed 

rodenticides

– Risks to mammals expected since rodenticide

intended to kill rodents

• Birds

– Brodifacoum and difethialone pose a greater r

relative to other assessed rodenticides relative to other assessed rodenticides
Risks and Mitigation

• Assessment of im

pacts of risk 

mitigation measures is not basequantitative estimates of risk reduction

• Common sense rationale:

C th iti ti b Can the mitigation measure 

be 

reasoned to reduce the potentia

wildlif ? ildlife exposure

?
Risks and Mitigation

• Bait station requirement

• All NOIC rodenticides for above ground use• Placement of rodenticide bait in a tamper resistant 

Placement of rodenticide bait in

a tamper resistant 

• Bait is in formulation not expected to be removable 

station

• Exposure reduction effects: Exposure reduction effects:

• Reduction in the size of organisms with access to the 

 Only animals the size of commensal rodents (e.g. no Key 

exposures)

• Reduced opportunity for bait encounters for animals 

to enter the stations(e.g. birds)

• Tier 1 tamper-resistant station are not likely to allow 

access to dogs and wild access to dogs and wild canids (e.g., kit foxes will no

(e.g., kit foxes will no

access)

• Concentrated bait stations represent potential reduct

geographical extent of bait availability.
Risks and Mitigation

• Bait marketing restrictions

• Second generation rodenticides (e.g., Second generation rodenticides (e.g.,

brodifacoum and difethialone)

• Large package sizes

• Sale to professional applicators• Exposure reduction effects:

• R d ti i th R

e

duction in the non-prof i l li 

fessional applic

rodenticide

 Reduction in the geographic extent of roden

application

• Professional applicators likely to use inte

rodent control approaches (i.e., reductio

sh lt i f d d t ) h

eltering, 

foo

d an

d wa

ter resources

)

 Limit the attractiveness of use areas to wildl
Conclusions

• Lines of evidence provide a confiden

picture

• There are risks of primary and secon

There are risks of primary and secon

mortality for the NOIC compounds a

substitutes available on the market substitutes available on the market

• These risks can be managed thro g

These risks can be managed thro

ug

application of common sense mitiga

requirements to limit exposure of wilrequirements to limit exposure of wil

a commensal rodent control environ