Ecological Risk Assessm

of Rodenticides: of Rodenticides:

Analysis Plan

Presentation to the SAP

November 29th, 2011

Edward Odenkirchen, Ph.D. , Ph.D.

Environmental Fate and Effects Division
Purpose of the Evaluation

• Provide information on the ecological risks ass

with the rodenticide active ingredients in produ

are the subject of the Notice of Intent to Canceare the subject of the Notice of Intent to Cance

• Update existing data sets 

• Toxicity data• Body burden information Body burden information• Incident information

• Conduct deterministic risk assessments using update

information and most recent methods information and most recent methods

• Analysis of incident data with respect to

• Expected route of exposure• Land use characteristics Land use characteristics

• Evaluation of all lines of evidence for consisten

risk conclusions

• Consider risk conclusions as they relate to miti

Consider risk conclusions as they relate to miti

measures in the Risk Mitigation Decision (RMD
Rodenticides Evaluated

• 4 active ingredients under the NOIC

• 3 anticoagulants:

• Brodifacoum*• Difethialone*• Warfarin**

• 1 neurotoxin 1 neurotoxin

• Bromethalin

 Has conforming and non-conforming labels

• 2 likely replacement active ingredients that have conf

labels (both anticoagulants)

• Chlorophacinone**

• Diphacinone**

*Known as a Known as

a

“second generation second generation

” anticoagulant anticoagulant

**Known as a “first generation” anticoagulant
Taxonomic Groups Potentially 

• RMD focused on steps to mitigat

RMD focused on steps to mitigat

concerns for terrestrial wildlife ris

• Results of 

previous assessment 

• Multiple lines of evidence (high tox

bioaccumulation exposure potentibioaccumulation, exposure potenti

incidents) suggest that primary risk 

concern is for terrestrial animals (i concern is for terrestrial animals (i

birds and mammals)
Measures of Risk

• Deterministic Risk Quotients (RQ)

Exposure estimate/toxicity endpoint = RQ

• E E ti t Exposure 

E

stima

tes

• Primary: Direct consumption of bait• Secondary: Consumption of prey contaminated through direc

consumption of bait

• Utilize peer-reviewed exposure calculations (Wildlife Exposu

Handbook, EPA 1993)

• Effects endpoints

• Acute lethal endpoints Acute lethal endpoints

• Dose-based• Dietary-based

• Efforts to standardize analysis • Body weight scaling to account for interspecies differences (v

Body weight scaling to account for interspecies differences (v

methods)

• Interpretative Method

• RQ compared to non-listed species Level of Concern (LOC=
Characterization and Comp

of Risks Across Chemic

• Primary Exposure

• Amount of bait required to reach med

l th l d leth

al dose

• Number of days of feeding required t

median lethal dose median lethal dose

• Secondary Exposure

• Number of target animals required to 

Number of target animals required to 

median lethal dose

• Results of secondar

y g feedin

g studies
Assessment Methods - Inc

• Document incidents of ex

posure an

mortalities 

•

p y yp rimar

y and secondar

y ex

posure

• mammals and birds

• Document location of incidents Document location of incidents

• Related to urban/suburban areas tha

re

present use sites for commensal ro

control products

• Concurrence with other lines of evid
Risk and Mitigation Meas

• Conclusions are qualitative Conclusions are qualitative

• Bait station/solid bait requireme• Limitation of application distanc

structure

• Point of sale and material mass 

limitations to home-owner use
Organization of Presentati

• Toxicity Data• Primary Deterministic Risk Assessment• Secondary Deterministic Risk Assessment• Incident Data Incident Data• Conclusions based on all lines of evidence• Discussion of risk conclusions and risk mitiga

measures