	UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, D.C.  20460

	OFFICE OF                    

	PREVENTION, PESTICIDES AND

	TOXIC SUBSTANCES      

	January 10, 2006

Memorandum

Subject:		Response to Comments on EFED's July, 2004 Risk Assessment: 
"Potential Risks of Nine Rodenticides to Birds and Nontarget Mammals:  a
Comparative Approach"

To:				Susan Lewis, Branch Chief

Laura Parsons, Team Leader

Kelly Sherman, Chemical Reviewer		

Reregistration Branch 1

Special Review and Reregistration Division

From:			William Erickson, Ph.D., Biologist

Environmental Risk Branch 2

Environmental Fate and Effects Division

Through:	Thomas Bailey, Ph.D., Branch Chief

Environmental Risk Branch 2

Environmental Fate and Effects Division

EFED has reviewed the comments submitted on the environmental risk
assessment entitled "Potential Risks of Nine Rodenticides to Birds and
Nontarget Mammals:  a Comparative Approach" dated July, 2004.  Comments
were received from more than 150 respondents, including 6 comments that
requested a time extension for responding, and are contained in OPP’s
EDocket OPP-2004-0033.  Respondents included Federal, State and local
agencies; environmental coalitions/organizations; rodenticide
registrants and the Rodenticide Registrants Task Force; pest control
firms and organizations; consultants/advisors; and private citizens, and
the comments are grouped by those categories.  EFED is responding only
to those comments that address the risk assessment.  Some comments
address the comparative analysis modeling conducted by the late D.
Urban.

EFED acknowledges and appreciates the assistance of P. Durkin, Syracuse
Environmental Research Associates, in compiling and summarizing the
comments.

Attachments:

Attachment 1:		EFED’s July 17, 2004 Response to Public Comments on
EFED's Risk Assessment:  "Potential Risks of Nine Rodenticides to Birds
and Nontarget Mammals:  a Comparative Approach", dated December 19, 2002

Attachment 2: 		Field uses of zinc phosphide, diphacinone, and
chlorophacinone.

Attachment 3: 		EFED Response to USDA/APHIS’ “Partner Review
Comments:  Preliminary Analysis of  of Rodenticide Bait Use and
Potential Risks of Nine Rodenticides to Birds and Nontarget Mammals:  A
Comparative Approach (June 9, 2004)”, September 7, 2004

FEDERAL, STATE, AND LOCAL AGENCIES

U. S. Fish and Wildlife Service

Comment:  Based on review of EPA’s comparative risk assessment,
published literature, and wildlife mortality reports, it is the opinion
of the Service that continued use of rodenticides under current
conditions presents a significant level of risk to birds and nontarget
mammals.  Further, the ever-increasing number of mortality events
attributed to second-generation rodenticides indicates that current
restrictions placed on these pesticides (baiting of commensal rodents in
and around buildings, transport vehicles, and inside sewers, and indoor
use only for brodifacoum and difethialone in non-urban areas) is
insufficient to prevent exposure to nontarget organisms at levels
consistent with adverse effects.

Widespread nontarget exposure to anticoagulants cannot be disputed. 
Based on a study of carcasses collected from 1998-2001 in New York
State, including samples asymptomatic of anticoagulant exposure
submitted for West Nile Virus surveillance, Ward Stone, Wildlife
Pathologist for New York State Department of Environmental Conservation,
concluded that anticoagulants were present in the majority of great
homed owls, about half of the red-tailed hawks, and in a substantial
fraction of other raptors in New York State (Stone et al., 2003).
Detection of more than one rodenticide in a number of these carcasses
indicates that a percentage of these birds are acquiring these residues
through multiple exposures.  For smaller species, the picture is less
clear.  Most incident reports tend to focus on large conspicuous species
like predators and scavengers.

Due to their high nonselective toxicity and known involvement in the
mortality of birds and nontarget mammals, the Service recommends the
following mitigative measures to alleviate risk to nontarget organisms:

·	All rodenticides considered in this assessment should be restricted
to use by a certified applicator.

·	Second-generation rodenticides should be limited to use inside
buildings only, except in situations where the benefits to nontarget
organisms outweigh the risks.

·	To reduce risk associated with primary exposure, all rodenticides
considered in this assessment should be made inaccessible to nontarget
organisms by mandating the use of tamper-proof bait stations.

EFED Response:  EFED thanks the Service for their comments. 

New York State Department of Environmental Conservation (NYSDEC)

Comment:  The July 2004 risk assessment clearly and unambiguously shows
that there are distinct differences between the rodenticides and that
brodifacoum is one of the more dangerous ones, which is consistent with
the findings of New York’s Wildlife Pathologist.

EFED Response:  EFED thanks the NYSDEC and commends it and its’
Wildlife Pathologist for providing much of the incident data cited in
the assessment.

Comment:  Kaukeinen et al. (2000) suggest that most incidents probably
result from misuse by non-certified applicators.  However, the potential
for misuse cannot be separated from the inherent toxicity of
brodifacoum, and rodenticides with less toxicity pose lower risks
whether misuse is intentional or unintentional.

EFED Response:  EFED agrees.  The RRTF’s presumption that incidents
occur due to misuse by non-certified applicators seems to be an argument
that the most highly toxic rodenticides shouldn’t be sold over the
counter at outlets such as supermarkets where they can be purchased by
non-certified applicators.  Several other respondents have stated a
similar concern. [see also Attachment 1, Comments 4, 5, 11 and EFED
Responses]

Comment:  Overall, the risk assessment is an excellent study that fairly
evaluated the data available and utilized alternate methods of analysis
(comparative analysis model; lines of evidence approach) to assess the
risks of rodenticides and reach solid, objective, and defensible
conclusions.  The NYSDEC suggests the following mitigation measures: 

·	Segregate indoor, homeowner use products from outdoor products.

·	Make outdoor products restricted use.

·	Construct bait stations out of plastic or metal so they cannot be
easily opened by wildlife.

·	Provide more warnings and instructions to advise how to use the
products more safely

·	Reformulate products to reduce the concentration of active
ingredient.

EFED Response:  EFED appreciates the comments of the NYSDEC. 

California Department of Pesticide Regulation (CDPR)

Comment:  CDPR recommends that the observation period following subacute
exposure be extended to 10 to 14 days.  In addition, NOAEC determination
should include necropsy as well as behavioral observations.

EFED Response:  For the anticoagulant rodenticides, EFED requires that
test animals in subacute (i.e., 5-day dietary exposure) and acute-oral
studies be observed for at least 15 days and even longer if mortality
occurs during the last three observation days.  These requirements are
mentioned in the risk assessment [see test descriptions under "Terms and
Definitions"].  Behavioral observations and signs of toxicity also must
be reported.  EFED agrees that an extended observation period is
critical in these tests, because death can be delayed for up to two
weeks or more after a lethal dose has been ingested via the diet or
gavage.  Adding supplemental Vitamin K to the basal diet also is an
issue that influences toxicity of anticoagulant rodenticides in the
laboratory.  As indicated in the risk assessment, many of the toxicity
values obtained from the open literature (e.g., Godfrey 1986) are
questionable, because the length of the observation period and vitamin
supplementation of the basal diet are not reported.  

Comment:  California data (R. Hosea; DFG) indicates that brodifacoum
poses a significant hazard to nontarget wildlife, particularly in urban
and suburban areas.  We recommend EPA consider restricting brodifacoum
use to PCO’s and/or indoor use only to reduce risk to nontarget birds
and mammals.

EFED Response:  EFED thanks CDPR for these comments. 

Comment:  CDPR recommends that registrants be required to fill the data
gaps (relating to toxicity and kinetics) as a condition of registration.

EFED Response:  EFED agrees that data gaps should be addressed. 
However, whether or not a Data Call-In is issued is decided by SRRD.

Comment:  Recommend that total body burdens rather than blood and liver
levels be used to determine nontarget hazard due to secondary poisoning.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  The risk assessment identifies measures issued by the USFWS to
protect endangered species from rodenticides.  The CDPR, the Department
of Fish and Game (DFG) and the Department of Food and Agriculture (CDFA)
have developed a County Bulletin program, which has been reviewed and
approved by the FSW as an acceptable alternative to the FSW’s
Biological Opinion. 

EFED Response:  California’s County Bulletins do not supersede the
requirements for EPA to address risks to listed (i.e., endangered and
threatened) species from potential pesticide exposure.  As noted in the
risk assessment, the Endangered Species Act (ESA) requires that “A
Federal agency is required to insure that any action they authorize,
fund, or carry out is not likely to jeopardize the continued existence
of a listed species or result in the destruction or adverse modification
of designated critical habitat.”  Possible risks to listed species
will be addressed by OPP in accordance with OPP’s Overview Document 
and, if necessary, in consultation with the U. S. Fish and Wildlife
Service and the National Marine Fisheries Service in compliance with the
ESA.  See also the following comment by CDFG and EFED’s response.

California Department of Fish and Game (DFG)

Comment:  Twenty-six (26) San Joaquin kit foxes Vulpes macrotis mutica,
a state and federally listed endangered species, have been recovered
from the Bakersfield, California, area with residues of brodifacoum.

EFED Response:  First, EFED wishes to acknowledge R. Hosea, DFG, for
providing information on the kit fox incidents as well as many other
rodenticide incidents in California.  EFED agrees that finding
brodifacoum residues in carcasses of the endangered San Joaquin kit fox
is a concern and says the following in the risk assessment:  

"Of particular concern are findings over the past several years that the
listed San Joaquin kit fox is being exposed to rodenticides, especially
brodifacoum.  From 1999 to 2003, liver tissue from 32 dead kit foxes has
been screened for rodenticide residues by the Pesticide Investigations
Unit of the California Department of Fish and Game and by the U. S. Fish
and Wildlife Service (R. Hosea, pers. comm.).  Anticoagulant rodenticide
was detected in the liver of 27 (84%) foxes.  Brodifacoum was detected
in all 27 individuals.  Bromadiolone also was detected along with
brodifacoum in 2 of those foxes, and chlorophacinone and pival were
found with brodifacoum in 1 fox each.  Pival is no longer registered but
may have been used under existing-stocks provisions."  

 As noted in the previous response, OPP is required by the ESA to
address listed species and, as necessary, consult with the Services to
mitigate risks.

Comment:  We urge EPA to consider reproductive effects during the
re-registration process.

EFED Response:  EFED agrees that reproductive effects should be
considered, and we believe that avian reproduction and rat
two-generation reproduction studies would provide useful information for
assessing risks.  Hopefully, OPP will require those studies to reduce
uncertainties in the risk assessment that relate to adverse affects from
sublethal exposure.  [see also Attachment 1, Comments 21 and 22 and EFED
Responses]

Comment:  Establishing a “toxicity threshold value” for post-mortem
liver rodenticide concentrations, as proposed by the Rodenticide
Registrant Task Force, is inappropriate and unreliable.  Over 50% of the
initial concentration of brodifacoum is metabolized and eliminated from
the body within the first few days following exposure, prior to the
death of the animal. Animals are sensitive to a compound over a range of
concentrations.  It is more appropriate to use detected tissue residues
in conjunction with other observed clinical signs of toxicosis to assign
the cause of death.

EFED Response:  EFED agrees.  We discuss the Rodenticide Registrant Task
Force’s (RRTF) concept of a “toxicity threshold value” in the risk
assessment and disagrees with what the RRTF proposes.  Findings from the
field and the incident data discussed in the risk assessment indicate
that the liver is an appropriate organ for detecting exposure of birds
and mammals to anticoagulant rodenticides.  However, establishing a
toxicity threshold of 0.7 ppm for mortality seems to be inappropriate
and is not supported by the available data.   

Comment:  DFG concurs that data are needed to determine the degree that
brodifacoum and other second generation anticoagulant rodenticides
bioaccumulate from repeated sub-lethal exposures. Repeated sub-lethal
exposures may lead to toxicosis and significant tissue or organ damage
and may increase the susceptibility of the animal to other causes of
mortality.

EFED Response:  EFED agrees.  The potential for brodifacoum to
bioaccumulate has been recognized by researchers as well as by the
registrant.  As discussed in the risk assessment, "Eason and Murphy
(2001) emphasize that the risk of brodifacoum is magnified by its
persistence, which could lead to accumulation on repeated exposure.  A
compound that is rapidly metabolized or excreted from a primary consumer
may result in a lesser risk than one that bioaccumulates with repeated
sublethal exposure, even if repeated exposure occurs weeks or even
months after the initial exposure.  Those compounds more rapidly cleared
from the body are less likely to pose such long-term risk."  

In the 1980s, ICI Americas Inc. (now Syngenta Crop Protection) was the
sole registrant of brodifacoum, marketed under the product names Talon
and Havoc.  At that time, product labels contained the telephone number
of ICI’s emergency assistance team and the number for the National
Animal Poison Control Center.  Callers received advice from either
source in the case of ingestion of these products by nontarget animals. 
ICI’s report for 1982-1985 contains information on numerous nontarget
exposures and poisonings, primarily dogs but also cats, chickens, and
several other species, including a horse.  In response to a case in 1983
where Talon was used to control rats, chickens were dying from feeding
on dead rats and possibly bait.  ICI "Advised TALON can accumulate in
body."  In another incident in 1983 in which a kitten had access to bait
and had been bleeding for two days, ICI stated that ". . . repeated
ingestion probably makes it more toxic."

Contra Costa Mosquito and Vector Control District (CA)

Comment:  Our inspectors/technicians find many unsafe applications of
rodenticides by the public.  Over the counter sales of rodenticides
should be required to be accompanied by a tamper proof bait station;
many vendors (e.g., supermarkets) do not stock bait stations.

EFED Response:  We appreciate this information.  It is an issue that has
been emphasized by other respondents and needs to be addressed in
mitigation

City of San Francisco, DEC

Comment:  Evaluating groups of chemical alternatives together will yield
the most accurate comparisons between the chemicals, and such
comparisons are most practical for informing the choices we need to make
in our IPM program.

EFED Response:  EFED agrees and appreciates the comment.

Comment:  An aquatic risk analysis is needed.  The widespread use of
rodenticides in sewers and along creeks provides a plausible pathway for
these chemicals to reach surface waters.

EFED Response:  The current assessment is limited to birds and nontarget
mammals. EFED realizes that there is some potential for rodenticides to
reach aquatic bodies and would appreciate any information that
applicators or other stakeholders could provide regarding exposure and
risks to aquatic organisms.  Possible risks to Federally listed species,
including aquatic species,  will be addressed by OPP in accordance with
OPP’s Overview Document (cited in footnote #4) and, if necessary, in
consultation with the U. S. Fish and Wildlife Service and the National
Marine Fisheries Service.  This analysis should also provide insight
into possible exposure of non-listed species as well.

Comment:  There is need for data on the risks from sub-lethal exposures
to rodenticides by off-target species. EPA correctly states that some
data exist showing adverse effects from sub-lethal exposures to
anticoagulants and that warfarin is a reproductive toxicant.

EFED Response:  EFED agrees and states the following in the risk
assessment:

for birds:  “No guideline data are currently available for any of the
rodenticides.  OPP will be requiring avian reproduction tests with the
mallard and northern bobwhite to fulfill this guideline requirement (40
CFR §158.490 Wildlife and Aquatic Organisms Data Requirements,
Guideline Reference No. 71-4).  EFED notes that there is a published
abstract reporting the deaths of 2 turkey vulture (Cathartes aura)
offspring that were fed brodifacoum-poisoned mice by their parents
(Borst et al. 2000).  The possibility exists that young animals may be
more susceptible to rodenticide poisoning than are adults (see also the
section on "Mammalian reproduction/sublethal effects").  EFED will
assess the potential for adverse reproductive and chronic effects when
the guideline studies become available.”, and

for mammals:  “EFED typically utilizes the rat two-generation
reproduction test to assess reproductive risks to mammals.  This study
(40 CFR §158.340 Toxicology Data Requirements, Guidelines Reference No.
83-4) is required by HED to support registration of pesticides with food
uses or where use of the product is likely to result in human exposure
over a significant portion of the human lifespan.  This study is not
currently available for any of the 9 rodenticides.  HED also requires
other subchronic/chronic studies, but most (e.g., dermal, inhalation,
oncogenicity, neurotoxicity) provide measurement endpoints not relevant
to assessing risk to nontarget mammals other than humans.

Some evidence exists that sublethal doses can have adverse effects.  The
Warfarin RED (EPA 1991a) notes that warfarin is a teratogen, and product
labels are required to warn that "Exposure to warfarin during pregnancy
should be avoided.  Warfarin may cause harm to the fetus, including
possible birth defects."  The Rodenticide Cluster RED (EPA 1998a)
reports developmental toxicity (e.g., vaginal bleeding, hypotonicity) in
rats and rabbits exposed to bromadiolone at about two orders of
magnitude less than the LD50 dose.  In brodifacoum studies, internal
hemorrhage and significantly prolonged prothrombin time of rabbits was
reported for those dosed during gestation at about two orders of
magnitude less than the LD50 dose.  More recently, Munday and Thompson
(2003) detected brodifacoum in two dog pups that died a few hours after
birth.  Of 13 pups from a single litter, eight were born dead or died
within 48 hours of birth.  Three puppies that died shortly after birth
were necropsied.  Two exhibited hemorrhage in the thoracic and
peritoneal cavities, intestinal serosa, and meninges, and brodifacoum
was detected in the liver of both puppies.  The mother did not have any
clinical signs of coagulopathy before or subsequent to whelping, and the
authors suggest that fetuses may be more susceptible to brodifacoum than
are adults.”

There also is the issue of adverse effects resulting from repeat
sublethal doses [see EFED Response to the California Department of Fish
and Game].

RODENTICIDE REGISTRANTS AND RODENTICIDE REGISTRANTS TASK FORCE (RRTF)

Syngenta Crop Protection, Inc.

Comment:  The scientific basis and the methodology behind EPA’s
comparative ecological risk assessment are flawed, and EPA’s benefits
analysis is not adequate.  Syngenta, along with three other rodenticide
manufacturers, has conducted a probabilistic ecological risk assessment
(ERA). This assessment was submitted in September of 2004. We believe
that the agency would benefit greatly from the use of the probabilistic
ERA, as it is a scientifically-based assessment that follows the current
EPA guidelines for ecological risk assessments.

EFED Response:  EFED reviewed and responded to the probabilistic risk
assessment for brodifacoum that was sponsored by Syngenta and three
other registrants (Bell Laboratories, Liphatech, and Reckitt Benckiser).
 That assessment claimed to quantify

secondary risks to birds and mammals while overlooking primary risks to
birds and nontarget mammals.  EFED’s Executive Summary of that review
is presented below.  

"Brodifacoum is a second-generation anticoagulant rodenticide primarily
used to control Norway and roof rats and house mice.  In 1998, EPA
issued a Reregistration Eligibility Decision (RED) for the rodenticide
cluster, which included an assessment of human and ecological risks of
brodifacoum and other rodenticides.  However, the RED noted that EPA had
received recent wildlife incident reports and that the Agency would
continue to evaluate the risks of labeled uses of brodifacoum to
nontarget birds and mammals.   In 2001 (updated in 2004), EPA completed
a comparative assessment of nine rodenticides used in the United States
and concluded that brodifacoum labeled uses pose high potential primary
and secondary risks to birds and nontarget mammals. 

The 1998 RED and 2004 comparative assessment evaluated risks based on a
lines of evidence and comparative-analysis model approach.  In an
attempt to estimate the probability and magnitude of potential
ecological effects of brodifacoum, four rodenticide registrants (Bell
Laboratories, Inc., Liphatech, Reckitt Beneckiser, and Syngenta Crop
Protection) contracted The Cadmus Group, Inc. to conduct a probabilistic
ecological risk assessment.  The Cadmus Group used a dietary dose model
to develop distributions to estimate daily dose to nontarget predator
species as a function of the body weight and food ingestion rate of
animals, the concentration of residue in food, and the fraction of food
in the diet containing brodifacoum.  They also used an uptake-depuration
model “to estimate the cumulative dose over time.”  Effects data
used to develop the distributions were taken from published and
unpublished sources.  Finally, exposure and effects distributions were
combined to estimate the probability of mortality to nontarget predator
organisms.   In their risk assessment, C/BR claimed low secondary risk
of brodifacoum-induced mortality to coyote, red fox, and red-tailed hawk
and inferred the same conclusion to other species of birds and mammals
with similar sensitivity and diet.  They also  claimed that the
secondary risk from brodifacoum was only slightly higher for the kit fox
and great horned owl.  Primary exposure of nontarget organisms was not
addressed nor were risks to scavengers addressed explicitly.  In
characterizing the ecological risk of brodifacoum, C/BR acknowledged
that risk estimates were limited by the lack of data and were subject to
a number of uncertainties and assumptions.

After reviewing the C/BR probabilistic risk assessment of brodifacoum,
EPA has concluded that the probabilistic risk assessment does not
provide sufficient evidence to alter EPA’s risk conclusions in the
deterministic risk assessment.  Similar to EPA’s assessment, the C/BR
assessment identifies information and data gaps that lead to major
uncertainties in quantitatively assessing risks from secondary exposure
to predators.  The uncertainties identified in the C/BR report suggest
that risks could range from a minimal likelihood of mortality to a high
likelihood of significant mortality, depending on the extent to which
predators consume rodenticide-exposed prey.  Data that would help reduce
the uncertainties in the risk assessments include information on local
baiting practices, dietary composition and foraging behavior of birds
and mammals when bait and/or dead and dying animals supplement the
natural food supply, toxicity data for predatory and scavenging species,
concentrations of brodifacoum in target rodents and nontarget birds and
mammals, and information on the retention, storage, and elimination of
brodifacoum in nontarget birds and mammals.  Because data are very
limited for quantifying exposure under expected and typical use
patterns, there is a large amount of uncertainty in the estimation of
risk. As acknowledged in the C/BR assessment, risk depends strongly on
local conditions and the foraging behavior and habitat use of predators
and scavengers.  Because of the spatial and temporal variability in all
of these considerations, it becomes extremely difficult to quantify
exposure and risk on a national scale."

California Department of Food and Agriculture (CDFA)

Comment:  The Revised Comparative Ecological Risk Assessment (RCEA) is
poorly written, the data are used selectively and inappropriately, the
analysis of the data is inaccurate and not reproducible, and the
conclusions biased.

EFED Response:  EFED cannot comment on such vague assertions.  CDFA
needs to be specific when referring to inaccuracies and improper
analysis of data. 

Comment:  The Agency’s risk assumptions are based on a selective and
limited data set and completely ignores field studies, operational
control programs, incident reports, and whole body residue data of
primary consumers.

EFED Response:  That CDFA states that this information is "completely
ignored" is simply wrong.  The available field studies, information from
operational control programs, incident reports, and whole body residue
data of primary consumers are discussed in the assessment.  As stated in
the introduction of the risk assessment, this information is used to
help characterize risks and complies with EPA's "Guidelines for
Ecological Risk Assessment" and recommendations of the Avian Dialogue
Group.

Comment:  Without specifically stating so, the ecological assessment
evaluates the nine rodenticide active ingredients as if they were
identical, interchangeable products, ignoring the fact that there are
dozens of different products on the market with different formulations
and use patterns (e.g., bait sizes, target species, use sites,
application methods).

EFED Response:  As stated  in EFED’s July 17, 2004 “Response to
Public Comments on EFED's Risk Assessment:  "Potential Risks of Nine
Rodenticides to Birds and Nontarget Mammals:  a Comparative Approach",
dated December 19, 2002" (attached), product-specific factors can be
considered when OPP considers mitigation options, providing that the
registrants have provided sufficient information on the various aspects
of individual products that might reduce risk.  As EFED stated in the
Executive Summary of the risk assessment, "specific use information by
formulation, including typical amounts applied by use site, seasonally,
and annually; distances applied from buildings; amounts used in rural
versus urban areas; use by Certified Applicators versus homeowners and
other non-certified applicators; and other such relevant information" is
needed; however, that information has not been provided.    

There are approximately 250 registered rodenticide products.  Most of
those have multiple target species with different baiting practices for
each species, many allow different baiting practices on the same label,
some allow for different baits.  EFED has added an Attachment to the
risk assessment that specifies all field uses, target pests, application
methods, and application rates when they can be determined from product
labels.  That information is also attached to this memorandum
(Attachment 2).  As can be seen from that summary of product labels for
field uses, much relevant information for assessing risks is not
provided on the product labels.  For example, many labels allow various
application methods, from aerial broadcasting to hand-placements of
baits, to application in bait stations, most have multiple target
species, some allow use of different baits, many allow an unlimited
number of applications and specify no application interval.  [see also
Attachment 1, Comment 17 and EFED Response and Attachment 3, EFED
Response to Comment 1 of USDA/APHIS]

Comment:  Lack of Exposure Assessment - it is stated in the RCEA
Executive Summary that “an assumption is made that birds and nontarget
mammals are likely to be exposed to the pesticide via consumption of
contaminated foods, which ingestion of the formulated bait is the route
of exposure”.  Yet the US EPA completely ignores the quantitative
measure of the likelihood of exposure.  The US EPA made no attempt to
quantitatively estimate secondary exposure at all, except to use blood
and liver retention times as potential surrogates.

EFED Response:  The extensive incident database clearly demonstrates
that a wide variety of birds and nontarget mammals are being exposed to
rodenticides by both primary and secondary exposure and probably
tertiary exposure as well for some species.  Such exposure cannot be
overlooked simply because it is difficult to quantify.  EPA’s Risk
Assessment Guidelines note that

". . . quantitation of risks is not always possible.  It is better to
convey conclusions (and associated uncertainties) qualitatively than to
ignore them because they are not easily understood or estimated" (PART
A, page 1, paragraph 3).  

Refining the exposure assessment to establish a quantitative measure of
likelihood of exposure and effects would require a much more extensive
data set than registrants have submitted for their rodenticides and for
the nontarget species potentially at risk.  The Agency provided the
preliminary risk assessment to rodenticide registrants in October, 2001
and posted it in the EDocket on EPA’s website for public comments from
January 29 to May 30, 2003.  No additional data or relevant information
to refine the exposure assessment has been provided by the registrants
or other stakeholders.  The necessary data have been outlined in a
section on "Uncertainty and Data Needs" in the refined assessment. 
EFED’s response to the previous comment also indicates the information
lacking for quantifying an exposure assessment for field products. {see
also Comment 1 and EFED Response in Attachment 1]

As discussed above in EFED’s response to Syngenta, The Cadmus Group,
under contract from Syngenta, Liphatech, HACCO, and Bell Laboratories,
attempted to conduct a probabilistic risk assessment for brodifacoum. 
The purpose was to quantify exposure and secondary risks.  However, due
to lack of data, they were unable to do so and simply made assumptions
about exposure.  They were successful only in demonstrating that a
quantitative exposure assessment is not possible until further data are
generated. 

Comment:  Issues With the Data Used in the Assessment - the studies
incorporated many different species (both as the target and nontarget),
exposure levels, feeding regimens, and even different bait strengths
(including bait strengths not registered for use in the United States).
This is a biased and unscientific use of data.

EFED Response:  The rodenticides have been in the reregistration process
for more than 10 years to date, and registrants have had ample
opportunity to propose any standardized testing for any of the
rodenticides if they believe that is necessary to support their
products.  Standardized studies for each rodenticide would provide
useful comparative information; but, until registrants conduct and
submit such studies, EFED must rely on the best available data.  

Some of the available studies were conducted under similar protocols and
with the same test species, and some studies (e.g., Mendenhall and Pank
1980) have tested the same test species under the same test protocol to
compare the hazards of different rodenticides. Other studies have used
different protocols, test species, and sample sizes. What is readily
apparent when examining the variety of data available is that some
rodenticides exhibited mortality and other adverse effects in many or
most test animals in almost every study, despite the differing protocols
and/or test species used in the study.  When looking at an individual
rodenticide, having a variety of studies with a variety of test species
is quite useful and relevant for assessing the hazards of that
rodenticide.  EFED also emphasizes that potential secondary risks are
not based solely on the secondary-hazards studies.  As stated in the
introduction to the comparative risk assessment, assessments of
potential secondary risk are made based on mortality and other adverse
effects reported not only in laboratory studies, but also in field
studies and operational control programs, incident reports,
toxicokinetic data, and residue levels reported in primary consumers. 
[see also Comment 6 and EFED Response in Attachment 1]

Comment:  EPA used non-comparable data for certain blood and liver
retention times in its analysis. Some values used were from studies with
humans, while others were from studies with rats, pigs, and even cattle.
  Metabolism and thus retention times can and do vary significantly
between species, therefore it is inappropriate to base measures of
effect on these factors unless data are from the same species and were
generated under similar testing conditions and protocols.  An even more
significant problem is that half-lives and retention times cannot be
used interchangeably, as was done throughout the US EPA’s analysis.
The half-life for a compound is independent of dose (unless elimination
kinetics are saturated), but the retention time is not.  Therefore, the
study design and dosing regimen will affect the retention time more than
the half-life.  Again, because conditions were not standardized and
comparable in the studies from which retention time data were derived,
this causes a bias in the dataset.  Furthermore, it must be kept in mind
that the retention time will always be longer than half-life for a given
compound, therefore, use of retention times will bias the data set for
certain compounds unless this data is used for all compounds in the
analysis.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  In some cases the US EPA did not have the actual scientific
study (WHO 1995) to evaluate for accuracy and methodology, and simply
cited the data.

EFED Response:  The source of all data is clearly cited in the
assessment.

Comment:  Subchronic mammalian toxicity data were not utilized  despite
the availability of a large set of subchronic mammalian toxicity
studies, including studies on most, if not all, of the nine active
ingredients.  EPA has not utilized (or even discussed) this data in the
RCEA. ... 

EFED Response:  CDFA should be specific about what studies they believe
have been overlooked.  Neither avian or mammalian reproductive data are
available for any of the nine rodenticides, and this is discussed in the
risk assessment.  See also EFED’s Response to California Dept. Fish
and Game Comment. on this topic.

  

Comment:  The US EPA typically uses rat and mouse toxicity data as a
surrogate for wild mammals in its ecological risk assessments, but did
not do so in the RCEA.  CDFA requested that the US EPA use the available
mammalian toxicity data that it has required registrants to generate in
order to improve the risk assessment, but the US EPA ignored this
request.

EFED Response:  The rat (or mouse) acute toxicity data were used to
calculate risk quotients for primary risk to mammals as is done for all
risk assessments conducted by EFED.  

Comment:  The US EPA’s evaluation of primary risks to birds does not
take into account the fact that dyes that are added to the CDFA’s
rodent grain baits in order to deter consumption by birds.  A black dye
is added to the zinc phosphide baits and a blue or red dye is added to
the baits containing chlorophacinone and diphacinone.  There is a large
body of research that shows that these dyes will deter consumption of
grain by birds.

EFED Response:  The literature indicates that many variables likely
influence how food color affects feeding behavior of birds.  Some birds
may prefer some colors over others if given a choice, but this is not
consistent across species and also may depend on other factors of the
food (e.g., size, shape, texture) and its availability.  Even if some
colors are preferred over others or over uncolored food, a sufficient
amount might still be eaten to provide a lethal dose.  For example, in a
laboratory situation a bird might eat 20 red-dyed grains and only 13
green-dyed grains, which may be a significant statistical difference. 
However, if a lethal dose or more of pesticide was contained in only a
single grain or two, there may be no significant biological difference. 


Kalmbach (1943) tested the reaction of captive quail to colored grains
and found that "When naturally colored food was unavailable the majority
of the quail accepted the dyed grain regardless of color." Moran (1999)
offered dyed and undyed wheat and sorghum grains to pigeons and
partridges.  The pigeons preferred undyed wheat grains, but did not
differentiate among dyed or undyed sorghum grains.  Partridges preferred
undyed and black grains to all other colored grains; black color was not
a deterrent.  EFED also notes that sunflower seeds are black, and they
are a common ingredient of bird-seed mixes sold for pet birds.  

Comment:  The US EPA does not differentiate between different types of
grains in its analysis.  Use of “lightly” rolled oats for the bait
minimizes the presence of fine, broken grain particles which are too
small for rodents to manipulate, but may be acceptable to small
seed-eating birds.

EFED Response:  CDFA has provided no data to support the contention that
"lightly" rolled oats are not acceptable to birds.

Comment:  The US EPA’s analyses of primary risks to both birds and
mammals incorrectly assumes that all rodent baits weigh 0.2 g per pellet
or kernel.

EFED Response:  EFED makes no such assumption.  As stated in the risk
assessment and in EFED’s previous “Response to Public Comments”
dated July 17, 2004, EFED assumes that a typical rat-bait pellets weighs
0.2 g based on information provided by Syngenta as cited in the refined
comparative risk assessment.  We did calculate the number of 0.2-g
pellets needed to provide an LD50 dose to a bird or nontarget mammal
weighing 25 g, 100 g, and 1000 g.  However, we realize that some bait
pellets or grains may be smaller or larger than the typical rat-bait
pellet, and some are formulated as meal or wax blocks.  Therefore, we
also calculated the amount of bait that would need to be eaten by a bird
or nontarget mammal to provide an LD50 dose, and we calculated what
percent of the diet that would comprise.  The later calculations are
independent of pellet or grain size.

HACCO

Comment:  EPA’s "comparative analysis modeling" is scientifically
inadequate, inconsistent with Scientific Advisory Panel (SAP)
recommendations (i.e. the SAP recommends using the concept of "hazard"
and not "risk" to characterize what the report is about), and
scientifically unproved. 

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  EPA’s reliance upon an unfounded correlation between
low-level liver residues of rodenticides in animals and animal mortality
(EPA is assuming that because residues were found in roadkill coyote,
the rodenticide caused the death.) is indefensible and indicative only
of exposure, not causality.

EFED Response:  HACCO statement is erroneous and misleading.  Nowhere in
the risk assessment does EFED say “that because residues were found in
roadkill coyote, the rodenticide caused the death.”.  However, the
documented fact that very highly, biologically persistent anticoagulant
rodenticides are being detected in a wide variety of birds and nontarget
mammals is and should be of concern.  Such widespread exposure of
nontarget species is occurring not only in the U.S., but also in other
countries, suggesting that this is no local concern limited to New York
and California.  In the U.S., anticoagulants have been detected in dead
foxes, including numerous endangered kit foxes, mountain lions, bobcats,
coyotes, deer, raccoons, skunks, opossums, squirrels, rabbits,
chipmunks, owls, hawks, eagles, vultures, crows and ravens, geese, and
other birds.  As emphasized by Mineau et al. (see footnote #14), "The
high level of exposure despite stringent labelling requirements raises
serious questions about possible effects and correlates of this
contamination."

Some, but certainly not all, of the dead animals submitted to the New
York State Department of Environmental Conservation and California
Department of Fish and Game were found dead along roadsides.  That
should not be surprising, because, as noted by several researchers,
carcasses of animals that die in the wild are rarely found except along
roadsides where they are more visible than if they die inside burrows,
crevices, or under dense vegetation.

Comment:  EPA’s relative ranking of rodenticides in descending order
of  those purported to pose the greatest risk to birds and nontarget
mammals is misleading and scientifically indefensible because the
ranking is based principally on the relationship of acute toxicity among
the nine rodenticides) does not take into account whether the birds and
nontarget mammals actually are exposed at the levels used in EPA’s
assessment.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

PM Resources

Comment:  EPA compares the nine rodenticides as if all are used in the
same manner and form (e.g., broadcast vs . structural-only use and
pellet forms vs. other forms (i.e, meal, wax, water soluble, etc.).

EFED Response:   EFED realizes differences occur in the baits, target
species, use sites, application rates and methods of the various field
rodenticides (see Attachment 2), and these differences will be
considered qualitatively during mitigation if adequate data exists.  If
PM Resources and other registrants believe that these factors need to be
considered quantitatively, registrants should have provided the
necessary information for EFED to do that.  [see also Comments by CDFA;
and, Attachment 3, EFED Response to Comment 1 by USDA/APHIS ]

Comment:  EPA’s “comparative analysis modeling” is scientifically
inadequate, inconsistent with the Scientific Advisory Panel (SAP)
recommendations (i.e., SAP recommends using the concept of “hazard”
and not “risk” to characterize what the report is about) and
scientifically unproved.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  EPA’s reliance upon an unfounded correlation between
low-level liver residues of rodenticides in animals and animal mortality
(EPA is assuming that because residues were found in roadkill coyote,
the rodenticide caused the death.) is indefensible and indicative only
of exposure, not causality.

EFED Response:  See EFED Response to HACCO regarding this comment.

Comment:  EPA’s relative ranking of rodenticides in descending order
of  those purported to pose the greatest risk to birds and nontarget
mammals is misleading and scientifically indefensible because the
ranking is based principally on the relationship of acute toxicity among
the nine rodenticides) does not take into account whether the birds and
nontarget mammals actually are exposed at the levels used in EPA’s
assessment.

EFED Response:  See EFED Response to HACCO regarding this comment.

Comment:  EPA’s reliance on a dated US Fish and Wildlife Service
Biological Opinion that was neither mentioned nor relied upon in the
1998 Rodenticide Cluster RED is legally flawed and inappropriate. 

EFED Response:  The USFWS Biological Opinion of 1993 is discussed in the
Rodenticide Cluster RED.  Why PM Resources considers that Biological
Opinion to be “legally flawed and inappropriate” is not stated in
their comments and thus serves no useful purpose.  As previously noted,
OPP will be addressing listed species and, as needed, consulting with
the Services to address risks and mitigation for listed species.  [see
also Attachment 3, EFED Response to Comment 2 by USDA/APHIS]

Comment:  EPA’s reliance upon incident data to support claims of risk
to birds and nontarget mammals is unfounded and misleading (i.e., EPA
assumes that any exposure involves an unacceptable risk).

EFED Response:  See EFED response to HACCO.

Liphatech

Comment:  Fails to make any assessment, even qualitatively, of exposure:
 Without a valid assessment of “exposure,” it is not possible to
assess risk (see previous discussion of this topic).

EFED Response:  Liphatech makes a misleading and erroneous statement.  A
discussion of exposure is presented in EFED’s risk assessment,
including uncertainties due to lack of adequate data and identifying
data that would be needed to reduce those uncertainties.  Liphatech is
one of four registrants that sponsored a probabilistic risk assessment
for brodifacoum that purported to quantify exposure and risks to avian
and mammalian predators and scavengers.  That assessment identified some
of the information that would be needed to quantify exposure (e.g.,
baiting practices, foraging behaviour and food habits of birds and
mammals) but overlooked that information, failed to quantify exposure,
and simply relied on assumptions of the registrants that lead to
presumptions of low exposure.  See EFED Response to Syngenta regarding
the purported probabilistic assessment sponsored by Liphatech, Syngenta,
HACCO, and Bell Laboratories.  [see also Attachment 1, Comment 1 and
EFED Response]

Comment:  EPA has not used the exposure data that is available.  EPA
could easily determine that more than 59% of the bait sold by Liphatech
in 2003 was in the “wax block” form.  These “wax block” forms of
bait have minimal attractiveness to birds, and cannot be ingested by the
small birds.  This type of qualitative exposure analysis would have a
significant impact on the CRA’s estimate of primary risk to birds. 
One of the assessment endpoints used, “Inverse of the LD50 for a 100 g
bird (number of bait pellets)” is rendered meaningless when the bait
is not a pellet.

EFED Response:   Simply stating that 59% of Liphatech’s baits are wax
blocks is not very useful.  EFED agrees that wax blocks can help reduce
exposure of seed-eating birds that might be attracted to loose pellets,
and that can be considered as a mitigation proposal.  However, not all
formulations are wax blocks, and many wax blocks are formulated only for
use inside sewers.  EFED concurs that few birds are likely to be feeding
inside sewers.  What about the other 41% of Liphatech’s baits?  What
about in other years?  Prior to issuance of the Rodenticide Cluster RED
in July, 1998, OPP requested information from registrants on the
quantities and relative proportions of various bait formulations,
geographic and seasonal information on use, baiting practices, and other
relevant information, but none of that information was provided.  The
types of information that would be needed to obtain better information
on usage by rodenticide have been identified in the risk assessment. 

Comment:  Uses speculation (pages 30, 81, 86, 105, and 149),
unsubstantiated anecdotal data (such as the Munday and Thompson paper
mentioned on page 30, golden eagle incident on pages 99-100), and
various other unsupported assumptions (pages 10, 90, 91, ) that support
a pre-determined point of view.

EFED Response:  The data from both Munday and Thompson and the golden
eagle incident are not speculation but are published data cited as such
in the risk assessment.  The following abstract is taken directly from
Munday and Thompson (2003):

"Abstract.  Eight out of a litter of 13 puppies were either born dead or
died within 48 hours of birth.  Three puppies that died shortly after
birth were necropsied.  Two puppies had hemorrhage in the thoracic and
peritoneal cavities, intestinal serosa, and meninges.  The third puppy
was smaller than the other two puppies but did not have detectable
hemorrhage.  Brodifacoum, a second-generation coumarin anticoagulant,
was detected in livers from the two puppies with hemorrhage.  The dam
did not have clinical signs of coagulopathy before or subsequent to
whelping.  The owners were confident that the dog had not been exposed
to rodenticide for at least 4 weeks before whelping.  A presumptive
diagnosis of in utero brodifacoum toxicity was made.  To the authors’
knowledge this is the first time a second-generation coumarin
anticoagulant has been detected in the liver of a newborn animal.  This
case is also unique because the dam was unaffected, suggesting that
fetuses are more susceptible to brodifacoum toxicity than adult
animals."

The following information on the golden eagle, presented in the risk
assessment, is taken directly from Hosea et al. (2001):

"The carcass of an adult Golden Eagle was recovered from its breeding
territory in Contra Costra County on March 11, 1999 (DFG case accession
# P-2060A).  The bird had been part of a long term radio telemetry study
of eagles in the area.  Based on telemetry data the breeding territory
consisted mainly of open rangeland and random outbuildings with some
areas of urban development.

The bird was not recovered in the vicinity of power lines and the
feathers did not have the "singed" odor characteristic of accidental
electrocution.  The necropsy indicated no other evidence of physical
trauma.  The animal was skinned to determine the presence of puncture
wounds from conflicts with other eagles or from a gunshot.  The
pericardial sac contained serum and blood.  Approximately 65% of the
surface of the heart muscle was haemorrhagic.  The major vessels
associated with the heart contained unclotted blood.  The lung tissue
was haemorrhagic, bleeding from a cut surface.  The cerebro-spinal fluid
was blood stained, indicating cranial haemorrhage.  These clinical signs
were consistent with previously published symptoms of anticoagulant
toxicosis in raptors (Hegdal et al. 1988, Mendenhall and Pank 1980, 
Newton et al. 1990, Radvanyi et al. 1988).  Liver tissue was analyzed
for residues of anticoagulant rodenticides.  Kidney tissue was also
analyzed for lead concentrations.  Kidney tissue had a lead
concentration of 1.1 ppm, well below the level that would indicate acute
toxicosis (Aiello 1998).  Liver tissue had a brodifacoum concentration
of 0.04 ppm.  The presence of the rodenticide in liver tissue alone does
not support a diagnosis of anticoagulant toxicosis.  However, if
considered in conjunction with the observed clinical signs consistent
with anticoagulant toxicosis, a diagnosis of anticoagulant toxicosis is
supported."

Comment:  Has not been properly peer-reviewed: A “peer review” was
conducted, in a manner that does not comply with EPA’s own guidelines,
on a preliminary draft of the document which was substantially different
from the current CRA, by a small number of persons who appear to share
the bias that appears throughout this CRA document.  Even after this,
the CRA retains important scientific errors that were pointed out by
these reviewers.

EFED Response:  Liphatech is incorrect.  This peer-review issue was
addressed in a letter from Lois Rossi, Director, Special Review and
Reregistration Division, to Lynn L. Bergeson, Bergeson & Campbell, P.C.,
representative for the Rodenticide Registrants Task Force as follows:

"Your May 22, 2002, letter expresses your concerns regarding the January
2001 peer review that was conducted on EPA’s draft preliminary
assessment. Included in your letter are excerpts from EPA’s “Peer
Review Handbook” from which you based your arguments.  In response,
the Agency has summarized and responded to the peer review comments
consistent with guidance provided in the Agency’s Peer Review Handbook
(updated December 2000). The peer review comments and EPA’s responses
are available in the public docket."

The peer reviewers of the risk assessment were Dr. Raymond O'Connor, Dr.
Elwood Hill, and Dr. Charles Eason.  The qualifications of these
reviewers is presented below.  Their qualifications and peer reviews are
available in the public EDocket (OPP-2002-0049).  As noted in the public
docket, many revisions were made to the final risk assessment in
response to the comments and suggestions of the peer reviewers.  For
Liphatech to imply otherwise and to accuse the reviewers of being biased
is simply wrong and inappropriate.

Dr. Elwood Hill has conducted research on wildlife toxicology since 1966
with the National Communicable Disease Center, Patuxent Wildlife
Research Center and as a private contractor.  He has published widely on
the hazards of agricultural pesticides to wildlife, and on development
and validation of wildlife testing protocols.  Dr. Hill has routinely
served as a toxicology consultant to the U.S. Fish and Wildlife Service,
U.S. Environmental Protection Agency, various State environmental
programs, and the private sector.  On many occasions, he has been an ad
hoc member of the U.S. Environmental Protection Agency's Scientific
Advisory Panel (FIFRA) for issues from wildlife testing protocols and
pesticide registration through development of probabilistic risk
assessments.  Dr. Hill is a long-standing member of the Society of
Toxicology, a charter member of the Society of Environmental Toxicology
and Chemistry, a Certified Wildlife Biologist, and has been an Adjunct
Professor at the University of Maryland (Program in Toxicology) and the
University of Nevada (Center for Environmental Sciences and
Engineering).

Dr. Raymond O'Connor has been Professor of Wildlife Ecology at the
University of Maine since 1987.  His research has focused on the ecology
of farmland birds (particularly in relation to pesticide use), on
ecological indicators, on biodiversity modeling, and on the human
dimensions of the environment.  Dr. O’Connor has authored two books
and more than 150 scientific papers and reports.  He has been an invited
member of numerous workshops and working groups, including meetings and
Panels on the environmental risks of pesticides and their assessment
organized by the U.S. Environmental Protection Agency Society, by the
Environmental Toxicology and Chemistry, by National Audubon Society, and
by NAFTA.  He also has served widely as a consultant on bird population
issues, including work for the U.S. Fish and Wildlife Service, U.S. EP,
Canadian Wildlife Service, and for various non-governmental
organizations and commercial firms.

Dr Charles Eason is Toxicologist and Research Team Leader of the Pest
Control and Wildlife Toxicology Team and Environmental Health
Programmes, Landcare Research New Zealand Ltd.  He is co-founder of the
Centre for Environmental Toxicology and team leader of the Pest Control
and Wildlife Toxicology team.  Dr. Eason has more than 10 years
extensive research and practical experience in vertebrate pesticide
toxicology and has published over 100 papers relating to the efficacy,
safety, and comparative risks of vertebrate pesticides.  He has received
numerous awards, honors, and distinctions.  His work includes assessment
of the environmental impact of pesticides and contaminants, using novel
techniques and providing novel improved toxicants, baits, and pest
control strategies, toxicity testing of pesticides to minimize
environmental and nontarget risks.

Comment:  Significant Errors in Table 41: Table 41 (page 82) purports to
show the “measures of effect values” for secondary risk to birds. We
note, however, that two of the three measures of effect use values
derived from mammals, not birds. For the remaining measure of effect
(mean mortality), difethialone is assigned 80% of the value for
brodifacoum because no actual data exists. In the other case where no
data exists (for bromethalin), the table simply notes “No data”.
There is no explanation offered for why these two compounds are treated
differently.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  Significant Errors in Table 42: In Table 42, the “measures
of effect values” for difethialone are identical to those in table 41,
yet the reported “summary value” is completely different. We have
expended considerable time and effort to determine how the “summary
value” can be different, but are unable to do so because the CRA fails
to show any of the calculations used to generate these values.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  Raw data is presented in a biased and misleading manner. 
“Mean % mortality of secondary lab studies” is used as an
“assessment endpoint” and is given the most weight in the analysis
of secondary hazard. This is raw data, taken from many different studies
that were all performed under widely different conditions and protocols,
without any consideration of these wide variations.  The authors and
sponsors of these studies expend much time and effort in design, because
it is so critical to the usefulness of the studies. The CRA ignores the
extensive planning and analysis conducted in the course of this
research; it simply presents the raw data in a manner that best supports
a pre-determined point of view.  Other similar statements on bias
follow.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  Uses inappropriate “measure of effect”: The document even
states (page 5) that one of the chosen “measures of effect” is
“not a direct measure of effect”. We are not aware that there was
any stakeholder input during the planning stages of this CRA, and EPA
has failed to respond to the comments submitted by Liphatech, RRTF and
others on the problems and deficiencies in these “measures of
effect”.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  Uses a method that it specifically states it will not use: The
CRA briefly discusses (page 149) some findings of EPA’s FIFRA Science
Advisory Panel (SAP) concerning comparative assessments such as this
one. It clearly states that a critical concern of the SAP was that
“risk quotients -risk indices that are used to express risk from
pesticides to nontarget organisms, should never be combined
(added);..... following this advice, no risk quotients or indices have
been added together for this analysis”. The CRA then shows how it uses
risk quotients and other risk indices (page 150 and 151) as “measures
of effect”, and then (page 152) how they are added together to create
a “summary value”!

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  In July of 2003, the California Department of Food and
Agriculture submitted an ecological risk assessment on chlorophacinone
and diphacinone baits. This risk assessment was reviewed by the author
of this CRA, yet there is no mention of the document or it’s contents
in the CRA!

EFED Response:  That statement is incorrect.  EFED reviewed the field
study but not the risk assessment.  A risk assessment conducted by a
registrant would be reviewed only if SRRD requested EFED to do so, but
the assessment done by the CDFA was not sent to EFED for review. 
EFED’s risk assessment does cite both the residue data and the field
study conducted by CDFA.   EFED’s review of the field study concluded
the following:

·	the study was designed primarily to assess the efficacy of 0.01% ai
and 0.005% ai chlorophacinone and diphacinone  baits for controlling
ground squirrels; evaluation of nontarget risks was mainly limited to
carcass searches for dead animals on the treatment plots, camera
inspection of carcasses on the ground surface, and, at one site, camera
probes inside squirrel burrows  

·	because ground squirrels apparently moved among the various treatment
plots, as indicated by the fact that 23 individuals that had residue of
both diphacinone and chlorophacinone and because dead squirrels were
found in control plots, differences in carcass residues due to bait
strength (0.005% and 0.01% ai) or application method (spot treatment and
broadcast) cannot be evaluated.

·	more than 40% of camera-monitored carcasses and those collected
during the daily plot searches had been scavenged, and more may have
been removed by predators and scavengers.  The number of scavenged
carcasses clearly indicates that scavengers were attracted to poisoned
ground squirrels

·	although the study authors stated that most squirrels died
underground, only 31 dead ground squirrels were observed in the 654
ground squirrel burrows probed by camera

·	based on carcass searches, sufficient information was obtained to
conclude that some small granivorous mammals (e.g., kangaroo rats, mice)
will be killed when chlorophacinone and diphacinone baits are applied by
ground broadcast or spot-baiting for ground squirrel control; however,
no methods were employed (e.g., mark-recapture, radio-telemetry) to
determine the extent of this mortality.

Rodenticide Registrants Task Force (RRTF)

Comment:  EPA’s approach ignores the role of probability in
determining the frequency and magnitude of potential consumption or
exposure and does not produce a reliable comparison of even
“potential” overall risk.

EFED Response:  Refer to EFED’s Responses to comments from Syngenta,
HACCO, CDFA, PM Resources, and Liphatech where EFED has addressed this
question.  [see also Attachment 1, Comment 1 and EFED Response]

Comment:   The Conclusions in the RCA Are Based on Speculative
Assumptions That Are Contrary to Peer Review Principles and Other
Federal Initiatives To Improve the Quality of Information on Which
Regulatory Agencies Rely... Like the PCA before it, the RCA fails to
consider comprehensively all available evidence regarding the question
of sublethal effects, including information previously submitted by the
RRTF.  Until the speculation and statements of opinion are eliminated
from the RCA, it cannot be considered to present a balanced,
scientifically sound, and defensible analysis of sublethal effects.

EFED Response:  Such vitriolic comments serve no useful purpose.

Comment:  EPA’s Comparative Risk Assessment of Potential Risks to Bird
and Nontarget Mammals Is Critically Flawed and Should Be Withdrawn ...

Measuring exposure by comparing active ingredient percentage results
only in a comparison of hazard, at best;

EFED Response:  The assessment is not limited to comparing active
ingredient percentage, and it is misleading to say so.

EPA’s approach ignores the role of probability in the frequency and
magnitude of potential consumption or exposure;

EFED Response:  Addressed in previous comment. [see also EFED Response
to Syngenta]

EPA relies inappropriately on island restoration and field studies to
characterize exposure from commensal uses;

EFED Response:  EFED disagrees.  These studies demonstrate that exposure
has adverse affects.  As previously discussed, the incident data confirm
that exposure is widespread.  From that, one can conclude that
widespread exposure of nontarget organisms can have adverse affects.

EPA relies inappropriately on irrelevant field studies conducted outside
the United States (e.g., in New Zealand). 

EFED Response:  Much useful information on the risks of rodenticides has
been reported from other countries.  This information is not irrelevant.
 See, for example, EFED’s response to HACCO.

Comment:  ... a peer reviewer of the RCA, who was also a member of the
SAP panel that reviewed the Methodology in 1998, concurs in the SAP’s
criticisms and also agrees that this methodology was inappropriate when
applied to the RCA.  Additionally, the sensitivity analysis conducted by
EPA is wholly inadequate to provide any understanding of the potential
variability inherent in the comparative analysis of nine rodenticides.

EFED Response:  As stated in EFED’s previous “Response to Public
Comments” on July 17, 2004 (see Attachment 1), one of the three expert
peer reviewers raised a concern about use of the comparative analysis
model as presented in an earlier draft of the risk assessment.  D. Urban
made extensive changes in response to that reviewer’s concerns.  As
previously noted (see EFED Response to Liphatech Comment), the three
expert peer reviews and the qualifications of the peer reviewers are
available in the public EDocket.

The same peer reviewer mentioned above also stated the following:  

"The bulk of the material in the document addresses the development of
the weight of evidence argument.  In general this part of the document
is well developed and it is hard to argue with the evident conclusion
about each of the nine chemicals.  These conclusions are largely
implicit in the text since the task of deriving a formal assessment for
each chemical is passed over to the decision support analysis.  The case
about each chemical is thoroughly and logically developed in this part
of the document and the document is commendable in showing how the
Agency staff have been able to develop the weight of evidence approach
as a viable approach to the synthesis of a complex body of evidence.”

Comment:  EPA’s Comparative Analysis Model Is Flawed, and Its Use of
the Modified Simple Multi-Attribute Rating Technique (SMART) Is
Scientifically Indefensible.  Although the “Comparative Analysis
Model” methodology was reviewed by the SAP in 1998, in the ensuing
years EPA has failed to incorporate fundamental changes recommended by
the SAP, resulting in an RCA that is scientifically indefensible. While
EPA incorporated minor adjustments to the methodology by adding a
sensitivity analysis, the RCA still embodies many fundamental errors
identified by the SAP in the preliminary version.  For example, despite
the SAP’s recommendation that risk quotients (RQ) (which the SAP
advised should be called “hazard quotients”) not be added, such
“risk quotients” were included in the RCA.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  The RCA only provides RQ values for acute dietary risk, and
the majority of the analysis is based upon “measures of effect”
(with no measures of exposure) that, for the most part, are not true
measures of effect but measurements of pharmacokinetic and fate
parameters (e.g., half-lives in various tissues). Thus, the RCA provides
even a weaker estimate of risk (more appropriately termed “hazard”)
than the document previously reviewed and strongly criticized by the SAP
as presenting not a risk assessment but a “hazard assessment.” ... 
It is misleading to refer to these rodenticide properties as effects,
however, and inappropriate to rely on these values to rank the risks of
rodenticides.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  The methodology used in the RCA “double-counts” hazards
two separate times.  First, the two measures of effect used in the RCA
to estimate primary risk to birds (dietary RQ and amount of bait needed
to produce an LD50) are not truly independent measures of effect.  Both
are based on the inherent toxicity of the active ingredient and, though
different, are highly correlated. This amounts to “double-counting”
of the same measure of effect, which skews the analysis. The second
“double-counting” in EPA’s methodology occurs when it uses the
same measures of effect for evaluating secondary risks to both birds and
non-target mammals.  Because the values for the blood and liver
retention times are the same for both the bird and nontarget mammal
analyses, this leads to double weighting of these factors when the
overall summary values are calculated. 

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  EPA assigned all measures of effect, except for two, a
“high” degree of importance for the analysis (with a factor of 10
assigned). The two to which EPA assigned “medium” importance
(half-lives in blood and liver with a factor of 2.5 assigned) are
correlated so that “persistence” was also indirectly given a
“high” weighting due to double-counting.  If it is assumed that all
the measures of effect have a “high” degree of importance, there is
no need to weight them at all.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  Attachment C of the RCA provides the method and approach used
for the Comparative Analysis Model, including a table of the input
values.  These data can be used to reconstruct the comparative analysis
conducted by EPA. While Table 6 of Attachment C of the RCA presents the
“Greatest Overall Risk to Birds and Mammals,” supposedly based on
the input values from Table 1, the RRTF was not able to calculate the
same values.  Table 1 below presents the EPA values in the first column
and the RRTF calculations in the second column.  There are only a few
large discrepancies, but with a thoroughly transparent system, the
values calculated by the RRTF should be identical.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban.

Comment:  Another discrepancy in the logic relates to the method
employed when data were missing or limited. EPA assumed that no
calculations could be made in the absence of  data, thus favoring those
chemicals for which there were less data. For example, there were no
data for zinc phosphide on liver and blood retention times, so those
values are zero in EPA’s calculations.

EFED Response:  This comment pertains to the comparative analysis
conducted by the late D. Urban

Comment:  EPA’s “Lines of Evidence” Approach Is Unjustified and
Scientifically Indefensible  – it is inappropriate not to provide
justification for the decisions made in assigning those rankings. 
EPA’s rankings are presented in Table 49 of the RCA without any
discussion of why the primary risk to birds is high for difethialone and
low to moderate for chlorophacinone or why the secondary risk to mammals
is moderate for warfarin but high for diphacinone. These may be the
appropriate rankings, but it is impossible to determine their
suitability without additional details that are lacking.

EFED Response:  The RRTF is not specific as to which “details” are
lacking.  The justification for primary risks to birds and mammals is
based on the risk quotients and whether they exceed the Agency’s
Levels of Concern; the number of pellets (or g food) that provide an
LD50 dose; and any relevant information from pen and field studies
demonstrating exposure and adverse affects.  For example, difethialone
has avian dietary RQs of 50 and 18 for the northern bobwhite and
mallard, respectively.  Avian dietary RQs are 0.9 and 0.3, respectively,
for those species for chlorophacinone.  The LOC is 0.5 for acute risk to
non-listed birds.  Additionally, difehtialone can provide an LD50 dose
to a 25-g bird consuming <2 rat-bait pellets, whereas a 25-g bird would
need to eat 645 pellets of chlorophacinone bait (50 ppm), which is not
physically possible in a single feeding.  The potential for
bioaccumulation of repeat sublethal doses also would be much higher for
difethialone than for chlorophacinone.

Comment:  EPA’S EIIS (Environmental Incident Information System) -
Data Are Misrepresented and Incorrectly Interpreted – The RCA
frequently misconstrues these data, by inferring from the presence of
rodenticide residues at any level -- specifically anticoagulant residues
-- that the anticoagulant is the causative agent in the observed animal
mortality.

EFED Response:  EFED disagrees.  See EFED Response to HACCO on this
subject.  [see also Attachment 1, Comments 2, 10, 13, 15, and 30]

Comment:  EIIS is Inaccurate – Historically, moreover, the summary
numbers for the EIIS have been questionable. A full analysis conducted
in 2001 by the RRTF of the EIIS database and the underlying reports,
primarily from California and New York, showed that the database was
inaccurate and misleading in a number of respects. For example, of 105
incidents then listed in the EIIS, only 68 were unique, while 37 were
redundant reports.  In at least one specific instance, the EIIS data
were plainly misrepresented. That instance involved eight coyotes and
two raccoons that had been live trapped by California Department of Fish
and Game personnel as “healthy” animals and then euthanized as part
of an effort to evaluate the levels of rodenticide exposures in wildlife
and to remove individual animals from some areas. The coyotes and
raccoons in these instances were listed inaccurately in the EIIS
database as if they had been brodifacoum-related  mortalities.

EFED Response:  EFED disagrees.  The EIIS is simply a database
containing all incident information submitted to the Agency.  As we
previously noted, neither the RRTF nor any rodenticide registrant has
been able to identify even a single redundant incident in the risk
assessment, because there are none. All redundant information in the
EIIS was accounted for and removed when the risk assessment was
prepared.

Regarding the coyotes (n=3) and raccoons (n=2) that were live-trapped,
euthanized, and analyzed for rodenticide residues, the RRTF statement is
highly misleading.  The risk assessment does not state that these
coyotes and raccoons were "brodifacoum-related mortalities".  However,
all five animals were exposed to anticoagulant rodenticides, and none
are target species.  The incident report from the California Department
of Fish and Game actually states the following regarding the exposures
of the three coyotes and two raccoons:

"All five of these animals carried residues of brodifacoum.  Four of the
five animals carried multiple residues of anticoagulant rodenticides. 
All of these rodenticides are registered for use to control commensal
rodents and can be purchased "over the counter" by the public." and "The
residue concentrations in these otherwise healthy animals may indicate
background levels carried by urban carnivores in the Los Angeles and
Orange County area.".  

Note that the animals are not described as "healthy" but as "otherwise"
healthy, a notable distinction.  The animals were euthanized, and thus
technically did not die due to anticoagulant exposure.  However, that
does not imply that the exposure might not have caused sublethal or
lethal affects if the animals had not been sacrificed.  Because death is
delayed several days or more after ingestion of a lethal exposure of
anticoagulant rodenticide, the fate of these animals is unknown had they
not been sacrificed.  Therefore, to suggest that this exposure was
insignificant may or may not be correct but certainly is not known.   

Several laboratory studies have noted that exposed test animals did not
exhibit any signs of toxicity until shortly before death.  In an
acute-oral toxicity study, beagles were observed for up to a month after
dosing for signs of toxicity and to calculate an LD50.  Symptoms of
poisoning (subdued behavior, loss of appetite, pale, respiratory
difficulties, hypothermia, blood in feces, minor external hemorrhage)
were observed "only after approximately six days" in those dogs that
died.  Another acute-oral toxicity study with dogs reported that
"Although death occurred more than five days after treatment, most dogs
only showed ill effects within the last day before death and some showed
no effect until immediately before death."  In separate acute oral tests
with rabbits and wallabies,  clinical signs in 62 individuals that died
within 2 to 25 days of dosing were only observed "just before death".

Comment:  EPA Erroneously Looks to Liver Data To Affirm Causality Rather
Than To Confirm Exposure  – The role of anticoagulant residues in the
liver is incorrectly characterized in the body of the RCA by EPA, ...
The concentration of brodifacoum or other anticoagulants can be measured
in a high-affinity, capacity-limited binding site in the livers of
target and non-target vertebrate species and used as a biomarker of
exposure. This binding site in the liver, however, is not the site of
action for these compounds and is not directly  linked to toxicity.  As
previously discussed by the RRTF, the cited 0.7 ppm liver residue figure
does not represent a bright-line value but instead is a general
benchmark between a biomarker of exposure (<0.7 ppm liver) from a
potentially toxic residue (>0.7 ppm).  In the RCA, by contrast, EPA
takes the position that this threshold concept is based only on limited
data, and it offers specific examples of liver residues less than 0.7
ppm that allegedly are associated with actual observed mortality. 
EPA’s position is at odds with the brodifacoum residue data from the
trapped and euthanized coyotes and raccoons described above. 
Brodifacoum liver residues  ranged from trace levels to 0.66 ppm in six
of the eight coyotes and  in both raccoons, and the residues of other
rodenticides also were detected.  N post-mortem pathological lesions
were observed.  These animals clearly were not affected by the
rodenticide residues present.  EPA appears to treat any residue of
anticoagulant as determinative of a causative agent, this is a
mischaracterization of the EIIS database.

EFED Response:  See EFED Response to the previous comment. 

Comment:  EIIS is Not Transparent – The underlying reports from state
agencies are not generally publicly available, and the summary of data
in Attachment D provides little, if any, background information. This
database should be thoroughly reviewed and incidents added since 2001
should be scrutinized with the same rigor as the analysis reported by
the RRTF in 2001.

EFED Response:  According to the previous comment, the RRTF was able to
obtain the EIIS data; to say that the data are “generally publicly
unavailable” is simply incorrect. 

Comment:  EPA Cannot Rely Upon Incident Data Not Included in the EIIS
Database – Data such as those from the American Society for the
Prevention of Cruelty to Animals (ASPCA) involving domestic or companion
animals should be excluded from any quantitative discussion because EPA
has taken them out of context and has not established that they are
relevant to the RCA or to the related assessment process. 

EFED Response:  The previous comment from the RRTF indicated that EFED
should not rely on the EIIS database, which seems to be contradicted by
the current comment.  

Comment:  EPA Failed To Address Key Issues Raised by the RRTF after Its
Errors- Only Review of the PCA

EFED Response:  EFED disagrees.  EFED responded in 2002 to the
errors-only comments of the rodenticide registrants and the RRTF; in
2004 to the public comments, including additional comments of
rodenticide registrants and the RRTF (see attachment); and is responding
here once again.  The previous responses are available in the EDockets
(OPP-2002-0049 and OPP-2004-0033).

Comment:  EPA Failed To Respond Satisfactorily to Public Comments on the
PCA

EFED Response:  See EFED Response to the previous comment.

Comment:  EPA inappropriately infers risk from exposure.

EFED Response:  As stated in the risk assessment, risk is a function of
toxicity and exposure.

Comment:  It is inappropriate to compare different modes of action.

EFED Response:  This comment was addressed in July 17, 2004 “Response
to Public Comments on EFED's Risk Assessment:  "Potential Risks of Nine
Rodenticides to Birds and Nontarget Mammals:  a Comparative Approach",
dated December 19, 2002" (attached)

Comment:  EPA Failed to Respond Satisfactorily to USDA/APHIS Comments on
the RCA

EFED Response:   EFED responded to USDA/APHIS comments during the
"errors-only" comment period, during the public comment period (see
Attachment 1), and again on September 7, 2004 in a 12-page response to
USDA/APHIS’ “Partner Review Comments:  Preliminary Analysis of  of
Rodenticide Bait Use and Potential Risks of Nine Rodenticides to Birds
and Nontarget Mammals:  A Comparative Approach (June 9, 2004)” (see
Attachment 3).  The RRTF needs to be more specific in identifying how
EFED has failed to respond to USDA/APHIS.

ReckittBenckiser

Comment:  EPA Confuses Risks and Hazards – The Agency’s
“comparative” approach provides an analysis based primarily upon
indicators of potential hazard, not risks (although the secondary hazard
indices do include some factors that imply exposure).

EFED Response:  See EFED’s July 17, 2004 Response to Public Comments
(attached).  [see also EFED’s Response to Syngenta above]

Comment:  Multiple Day Ingestion Model Should be Considered.  A single
dose model will tend to indicate that second generation anti-coagulants
are most hazardous because they are designed to kill their target
organisms in a single dose.

EFED Response:  Dietary risk quotients are based on 5 days of feeding. 
Secondary-feeding tests are generally based on multiple-day feedings. 
These are presented and discussed in the risk assessment.

Comment:  Primary Indices Need to Account For Exposure – If one
rodenticide is ten times more toxic to rats than another, all things
being equal, a consumer would use ten times less product.  Thus as
target toxicity increases, the volume of the product used will decrease
and the opportunity for exposure of non-target organisms to the product
decreases. ... At present the PCA assumes that only five times more
warfarin active would be needed because it only takes into account the
percent active ingredient in the formulation, 0.025% vs. 0.005%.
Normalizing using toxicities instead of fraction active ingredient would
mean that the warfarin primary MOEs would be multiplied by a factor of 2
to 180.

EFED Response:  EFED disagrees.  Simply because brodifacoum is more
toxic does not mean that less bait will be eaten than if warfarin was
applied.  Even though the second-generation rodenticides are much more
toxic and persistent than the first-generation anticoagulants, both
groups result in most exposed animals dying after about 4 to 10 days. 
However, they may continue to feed, whether they have ingested a lethal
dose or nor not, regardless of which anticoagulant is applied.  For
example, as discussed in the risk assessment, a rat feeding on
brodifacoum bait may ingest as many as 80 LD50 doses in bait before it
dies (average time to death was 6.5 days). 

In accord with label directions for application of baits of warfarin,
brodifacoum, or other anticoagulants, label directions for Norway and
roof rats specify the following:

"Apply 4-16 oz. of bait (usually at intervals of 15-30 ft.) per
placement.  Maintain an uninterrupted supply of fresh bait for 10 days
or until signs of rat activity cease."

and for the house mouse the following:

"Apply 1/4-1/2 oz. of bait per placement.  Space placements at intervals
of 8-12 ft.  Larger placements (up to 2 oz.) may be needed at points of
very high mouse activity.  Maintain and uninterrupted supply of fresh
bait for 15 days or until signs of mouse activity cease."

Comment:  Secondary Measures of Effect Indices – These secondary MOEs
should not be combined with the primary MOEs without some account for
exposure in the primary MOEs. Including exposure factors for secondary
MOEs, but not including them in the primary MOEs, relatively underweighs
the secondary toxicity measures.

EFED Response:  This comment addresses the comparative analysis modeling
conducted by the late Doug Urban.  

Comment:  Weightings Used Are Scientifically Indefensible – the
secondary toxicity MOEs are underweighted by the current method..  EPA
should produce an uncertainty estimate on the final output, so that
internal and external reviewers and EPA decision makers can tell whether
the predicted differences are significant.

EFED Response:  This comment addresses the comparative analysis modeling
conducted by the late Doug Urban.  

Comment:  Analysis of Certainty is Inadequate – EPA has done a
sensitivity analysis that looks at variation of MOEs by plus or minus
50%. However, real uncertainties associated with the numbers involved in
the MOEs are much greater than this. For instance, the LC50 data has 95%
confidence intervals that span orders of magnitude.  This means some
MOEs are uncertain by factors of ten or more. The uncertainties need to
be analyzed much more carefully by examining the confidence intervals of
the input data.  EPA should produce an uncertainty estimate on the final
output, so that internal and external reviewers and EPA decision makers
can tell whether the predicted differences are significant.

EFED Response:  This comment addresses the comparative analysis modeling
conducted by the late Doug Urban.  

Comment:  Conclusions Regarding Comparative Assessment – EPA’s
comparative analysis model is flawed and use of the modified Simple
Multi-Attribute Ratings Technique (SMART) is inappropriate.

EFED Response:  This comment addresses the comparative analysis modeling
conducted by the late Doug Urban.  

Comment:  The Agency continues to rely heavily on incident data to
determine the likelihood (risk) of adverse effects on birds and
non-target mammals. There is no discussion in the document to provide a
fair, objective presentation of the incident data.  Incident data can be
used to determine if exposure has occurred; however, the reviewers have
neglected to put this information into proper perspective.

EFED Response:  EFED disagrees.  The incident are one piece of the risk
characterization.  As previously noted in EFED’s Response to HACCO,
the incident data confirm that a wide range of nontarget animals,
including endangered species, are being exposed to anticoagulant
rodenticides via primary, secondary, and probably even tertiary
exposure.  The number of incidents reported to date (more than 400 as of
January 2006) clearly is sufficient to demonstrate a high level of known
exposure of birds and nontarget mammals and raises serious questions
about the extent of this contamination and its effects on individuals
and populations. 

Comment:  Comparison of the absolute number of incidents observed for
each product to draw a conclusion about hazard is invalid.  The data
must first be normalized for exposure. Thus, EPA must take into account
the quantity of a product in distribution and use when evaluating the
number of incidents reported. ... The incident data cited in the PCA
(e.g. Table 43), cannot be interpreted properly without taking into
account the differences in market share and packaging. The analysis of
the incident data should at least be normalized for the amount of
product used.

EFED Response:  As stated in the risk assessment, and as emphasized in
comments of the Environmental Coalition below, the absolute number of
incidents is unknown but certainly far exceeds what has been reported. 
Regarding pesticide-related wildlife mortality, Vyas notes that "Data
show that most effects on wildlife are not observed, and much of
observed mortality is not reported."  This is certainly the case for
rodenticides, for which most incidents in the EIIS have been reported by
state agencies in New York and California.  Even reporting from those
two states tends to be sporadic, depending on funding and other
commitments.  Nevertheless, as previously noted, the number of incidents
reported to date is sufficient to demonstrate a high level of known
exposure of birds and nontarget mammals and raises serious questions
about the extent of this contamination and its effects on individuals
and populations.  Also, ss also noted in the risk assessment, more
product information is needed than simply the amount produced.  When and
where is it being used?  Who is using it?  How is it applied and for
what duration?  What is being exposed?

ENVIRONMENTAL GROUPS

Environmental Coalition (Defenders of Wildlife, American Bird
Conservancy, TEDX, Inc., Beyond Pesticides/NCAMP, Northwest Coalition
for Alternatives to Pesticides, Californians for Alternatives to Toxics,
Rachel Carson Council, Inc., Virginia Polytechnic Institute and State
University)

Comment:  The EPA’s chosen strategy of lumping all nine rodenticides
together into a “comparative” risk assessment leaves the Agency
without the ability to deal with one or more of the most egregiously
hazardous rodenticides. ..., close scrutiny of the most hazardous
rodenticides is bypassed and the true hazards of individual rodenticides
can be obfuscated or otherwise overlooked.  

EFED Response:  EFED disagrees.  Each rodenticide is analyzed on its own
just as would be done if only a single rodenticide was being assessed. 

Comment:  There are incredibly few data for toxicological tests that
compare the toxicity and efficacy of these nine products side by side
for a variety of species. This is particularly true for field studies,
and we note that most of the available studies showed that the test
compound did not work well or involved the use of compounds which are
not included in this RED and/or are no longer registered.  Without this
direct comparison available, the EPA is piecing together indirect
comparisons that may or may not be valid.

EFED Response:  The Agency has used the best available data.  

Comment:  The risk assessment fails to consider sublethal effects.

EFED Response:  EFED disagrees.  The available data were considered and
data gaps identified.  [see also EFED Response to Comments above by the
City of San Franciso and Liphatech as well as Attachment 1, Comments 21
and 22 and EFED Responses]

Comment:  There is no consideration of the possible impact of prior
exposure (tissue residues of one or more rodenticides) on subsequent
exposure; there is some data to support the idea that non-target mammals
already exposed to rodenticides have a greater susceptibility to
subsequent exposure to rodenticides (Mosterd and Thijssen 1991). 

EFED Response:  EFED strongly agrees that there is a potential for
bioaccumulation from repeat exposures of the biologically persistent
second-generation anticoagulants; this is discussed in the assessment. 
[see also EFED Response to the California Dept. Fish and Game Comment
above]

Comment:  The EPA relies much too heavily on acute toxicity data for
their comparative risk assessment; this is a problem because there are
many reasons to be wary of acute toxicity studies of rodenticides.

EFED Response:  EFED used the best available data.  Although published
data are cited to help characterize toxicity, EFED only used toxicity
values from EPA guideline studies to calculate risk quotients.  Those
tests require an extended observation period and no supplemental vitamin
K added to the basal diet.  [see also EFED Response to Comment by the
California Dept. Pesticide Regulation] 

Comment:  A significant source of uncertainty in the risk assessment is
the fact that most of the laboratory studies have tested acute effects
in species such as the northern bobwhite, mallard, laughing gull,
ring-necked pheasant and domestic chicken.  However, very little
research has been presented to address either toxicity or exposure to
small birds.  These sources of variation (error?) should be addressed in
the narrative.  We believe that the exclusion of data on small birds
from consideration in either the laboratory studies or the incident data
has significant potential to underestimate the overall risk to birds of
these rodenticides.

EFED Response:  EFED’s guideline test species are the mallard and
northern bobwhite.  Data from those species are extrapolated to a 25-g
bird.  We realize that there are uncertainties in making such
extrapolations, but they are based on the best available data.

Comment:  A weakness pointed out by the peer-reviewers and addressed in
the 2002 document is that missing data and other uncertainties about
toxicity limit the predictive capabilities of the assessment. ... the
use of larger birds as surrogates for smaller birds is unwarranted.

EFED Response:  EFED agrees that data gaps need to be addressed.   See
previous comment regarding use of northern bobwhite and mallard as
surrogates for smaller birds.

Comment:  The large number of incidents that actually found their way
into the EPA EIIS database provides substantial evidence of a much
larger problem as a direct result of the present system of rodenticide
use.

EFED Response:  EFED agrees.  See also comments by the RRTF on
incidents.

Comment:  There is a serious paucity of both sales and usage data for
rodenticides in the United States.

EFED Response:  EFED agrees, and this is discussed in the risk
assessment. 

CONSULTANTS/ADVISORS, PRIVATE CITIZENS, AND OTHERS

Pest Control Services, Inc.

Comment:  Previously a pest-control consultant to The Philadelphia Zoo,
the respondent provides information on an incident that occurred at The
Philadelphia Zoo in 1980 and another in 1991.  Brodifacoum bait was
applied in bait stations for mouse control.  Several birds were killed,
probably by exposure to cockroaches that removed bait from bait
stations.  Residue analysis was conducted on several dead birds.  

EFED Response:  EFED appreciates this information.  The necropsy reports
have been provided by the Director of Pathology, The Philadelphia Zoo,
and added to the EIIS database.

Agricultural Sciences, Inc.

Comment:  Rodenticide usage without doubt impacts nontarget species and
the environment.  Brodifacoum is one of the most toxic materials ever
registered by EPA.  At a very minimum these materials must be taken out
of the general publics hands and only allowed to be used by
professionals with adequate training.

Protect All Children’s Environment

Comment:  Expresses concern about risks to people, and cites personal
illness from rodenticide exposure.

Pest Control Advisor (retired )

Comment:  Must make sure that these materials are safe to man and
nontarget entities.

Private Citizen and Agr. Consultant

Comment:  Emphasizes that zinc phosphide bait is needed for vole control
in alfalfa and hay.

Pest Management Consultant

Comment:  Rodenticides are not an efficient management tool; they are
not necessary, and they can be hazardous.

National Pest Control Association

Comment:  When rodenticides are used by professionals in accordance with
standard procedures they are extremely effective; in 22 years, has never
had a child or pet come into contact with his rodenticide baits

University of Nevada Cooperative Extension

Comment:  Variety of products are needed to maintain production of
quality alfalfa and hay

Pest Management Training & Consulting Center

Comment:  As a pest control consultant in NY and NJ, rely on these
rodenticides to help clients control rodent infestations.

Ohio Pest Control Association

Comment:  States that the current use of labeled rodenticides in tamper
proof industry approved stations is safe as well as effective

Private citizen

Comment:  Should be limited or banned; creating problems all over the
world.

Private citizen

Comment:  Rodenticides do more harm than good; get rid of all
rodenticides.

Private citizen

Comment:  Rodenticides should not be removed from professional use.

Private citizen

Comment:  Rodenticides are too dangerous to nontarget animals, including
humans; reports that rodenticide spread on beach for rats in the Los
Angeles area killed pigeons, gulls, and other birds 

Private citizen

Comment:  Use Prozap to control rodents in alfalfa and hay and believes
that rodenticide use is warranted due to minimal risks to birds and
mammals.

Private citizen

Comment:  Benefits far outweigh risks.

Private citizen

Comment:  Would be a mistake to eliminate rodenticides from the market.

Anonymous

Comment:  Most problems with nontarget species ingesting bait is due to
homeowners.

Anonymous

Comment:  Needs outweigh the risks.

Anonymous

Comment:  Rodenticides are needed for health and safety.

Anonymous

Comment:  Current labeling makes rodenticides safe.

PEST CONTROL FIRMS AND ORGANIZATIONS

The following respondents (many in a form letter) mainly stated that
benefits largely outweigh risks, without providing any specific comments
on the risk assessment or mitigation except as noted.  Many of the
responses were by form letter.

Anonymous

Anonymous (Pest Control Operator)

A. Aguirre (Pest Control Operator)

AA Professional Pest Services

ABS Pest and Lawn Services of DFW, Inc.

Accu Pest, LLC

Acme Exterminating Corp.

Action WDI Specialist, Inc.

Adam’s Pest Control, Inc.

All Pest Control

All Pest Inc.

American Pest Control, Rockville, MD

Comment:  Also state that properly anchored and placed rodent stations
are the best defense

Arrow Pest Control, Inc., Lake Geneva, Wisconsin

Banks Pest Control, Inc.

Banks Pest Control

Comment:  Also state that EPA should consider taking this product out of
the hands of the over the counter users (home owners)

Better Way Pest Control

Big Town Pest Control

Comment:  Also state that homeowners and unlicenced applicators are the
biggest problem; has seen many occasions where home owner has placed
bait in wrong places and it was accessible to animals and children

Blue Chip Exterminating

Border Pest Control, Inc.

Bruce Pest Control, Lakeland, FL

Carl’s Pest Control

Cayce Exterminating Company Inc.

Central Oregon Hay Growers’ Association

Catseye Pest Control, Inc., Minden, NV

Catseye Pest Control, Inc., Lenox, MA

Catseye Pest Control, Inc., East Schodack, NY

Coby Termite & Pest Control

Columbus Pest Control, Inc.

Crane Pest Control

Critter Control of Kansas City

Danny Myers

Edwards Pest Control Services, Inc.

Eradico Pest Control

Eradico Services, Inc.

Fisher Pest Control

Fowler Pest Control

General Pest Control Co.

Comment:  Also state that baits should be applied in bait stations

Getem Termite & Pest Control

Golden Glove Pest Control

Gunter Pest Management, Inc.

Harry Connoyer

Hassman Termite and Pest Control Inc.

Hometeam Pest Control

Insecta X, LLC Termite and Pest Solutions

Insects Limited, Inc.

Jackie Dendy Cross Pest Control of Tampa

Jackson Pest Control

J.C. Ehrlich Co., Inc.

Jepsen Pest Control, Inc.

Jack Frost 

John Frost

Kennedy Pest Control Inc.

Key Pest Control Company, Inc.

King Exterminating Co.

Kil-More Pest Management

Lone Star State Pest Control

McCloud Services

McKinney Independent School District (Pest Control Operator)

McKinzie Pest Control 

North Jersey Exterminating Company

Olson’s Pest Technicians 

Organization of Kittitas Valley Timothy Hay Growers and Suppliers

Orkin, Inc.

Orkin Pest Control, Zionsville, IN

Comment:  Also state that rodenticides need to be monitored closer than
they have been

PARATEX Pied Piper Pest Control

PB Pest Management

PESCO Pest Control Services, Inc., Indianapolis

Pest Control 258

Pest Express, Inc.

Pest Management Training & Consulting Center

Pioneer Pest Control, Inc.

Powers Pest Management

Presto-X-Company, mason City, IA 

Ron’s Termite & Pest Control, Inc.

Rose Pest Solutions

Rose Pest Solutions, Clinton Twp., MI

Southern NH Pest Control, Nashua, NH

Stubbs Pest Control, Amarillo, TX

Target Pest Control, LLC

Terminix - Chicago Branch

Valley Pest Control

Ventura Pest Control, Inc.

Varment Guard Environmental Services, Inc.

Comment:  Also state that no beneficial nontarget organisms have ever
been exposed except due to misuse and that EPA should enforce labels
rather than have more restrictive labeling

Weatern Exterminator Co.

ATTACHMENT 1

	UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, D.C.  20460

	OFFICE OF                    

	PREVENTION, PESTICIDES AND

	TOXIC SUBSTANCES      

	July 17, 2004

Memorandum

Subject:		Response to Public Comments on EFED's Risk Assessment: 
"Potential Risks of Nine Rodenticides to Birds and Nontarget Mammals:  a
Comparative Approach", dated December 19, 2002

To:				Laura Parsons, Team Leader

Susan Lewis, Branch Chief

Reregistration Branch 1

Special Review and Reregistration Division

From:			William Erickson, Biologist

Environmental Risk Branch 2

Environmental Fate and Effects Division

Through:	Tom Bailey, Branch Chief

Environmental Risk Branch 2/Environmental Fate and Effects Division

EFED has reviewed the public comments submitted on the environmental
risk assessment entitled "Potential Risks of Nine Rodenticides to Birds
and Nontarget Mammals:  a Comparative Approach" dated December 19, 2002.
 Comments were received from 26 respondents, including the Rodenticide
Registrants Task Force (RRTF), individual rodenticide registrants, user
groups, state agencies, environmental organizations, and a private
citizen.  Comments addressed data and methodologies, processes,
benefits, the lack of an open public process, mitigation issues, and
others.  EFED is responding to those comments relative to the data and
methodologies used in the risk assessment.  Some comments are raised by
more than one respondent, and these comments were grouped together in
this response.  A numbered list of respondents has been provided to
match their respondents with their comments.  Many of the comments by
the RRTF and individual registrants simply reiterate their "errors-only"
comments provided after the risk

assessment was provided to the registrants in October of 2001.  The
comparative risk assessment,

external peer reviews of the assessment by three qualified experts,
errors comments of the RRTF and individual registrants, and EFED’s
response to those errors comments are available in the Rodenticides
EDocket:  http://www.epa.gov/oppsrrd1/rodenticidecluster/index.htm

Respondents:

  1.  California Department of Fish and Game (CDFG)

  2.  New York State Department of Environmental Conservation (NYSDEC)

  3.  California Environmental Protection Agency, Dept. Pesticide
Regulation (DPR)

  4.  Natural Resources Defense Council (NRDC)

  5.  Defenders of Wildlife, American Bird Conservancy, Rachel Carson
Council, 

       Northwest Coalition for Alternatives to Pesticides, and Steve
Sheffield 

  6.  Sierra Foothills Audubon Society (SFAC)

  7.  Grassroots Coalition

  8.  Beyond Pesticides

  9.  Private citizen 

10.  Rodenticide Registrants Task Force (RRTF)

11.  Syngenta

12.  Reckitt Benckiser

13.  LiphaTech

14.  Hacco, Inc.

15.  Bell Laboratories, Inc.

16.  United States Department of Agriculture, Animal and Plant Health
Inspection Service

       (USDA/APHIS)

17.  The Zinc Phosphide Consortium (TZPC)

18.  California Department of Food and Agriculture (CDFA)

19.  Dodson Bros. Pest Control

20.  J.C. Ehrlich Co., Inc.

21.  County of Kings Department of Agricultural Commissioner

22.  Alameda County Health Care Services

23.  County of Fresno Department of Agriculture

24.  American Farm Bureau Federation, American Institute of Baking,
National Food Processors

       Association, North American Millers Association, Association of
Structural Pest Control

       Regulatory Officials, ConAgra Flour Milling Company, and National
Pest Management

       Association

25.  Organization of Kittitas County Timothy Hay Growers & Suppliers

26.  McCloud Services

Comment 1:  The assessment is not an ecological risk assessment, only an
assessment or ranking of hazards. A risk assessment must quantify
exposure.  EPA’s Risk Assessment Guidelines define ecological risk
assessment as "a process that evaluates the likelihood that adverse
ecological effects may occur or are occurring as a result of exposure to
one or more stressors." 

[10, 11, 12, 13, 14, 15, 18, 21, 23, 24]

EFED Response to Comment 1:  EFED’s risk assessment is in accord with
the Agency's Guidelines for Ecological Risk Assessment.  Registrants are
correct in noting that the Guidelines state that "Ecological risk
assessment is a process that evaluates the likelihood that adverse
ecological effects may occur or are occurring as a result of exposure to
one or more stressors"( PART A, page 1, paragraph 1).  However, the
Guidelines go on to state that "Descriptions of the likelihood of
adverse effects may range from qualitative judgments to quantitative
probabilities.  Although risk assessments may include quantitative risk
estimates, quantitation of risks is not always possible.  It is better
to convey conclusions (and associated uncertainties) qualitatively than
to ignore them because they are not easily understood or estimated"
(PART A, page 1, paragraph 3).  Refining the exposure assessment to
establish a quantitative measure of likelihood of exposure and effects
would require a much more extensive data set than registrants have
submitted for their rodenticides and for the nontarget species
potentially at risk.  The Agency provided the preliminary risk
assessment to rodenticide registrants in October, 2001 and posted it in
the EDocket on EPA’s website for public comments from January 29 to
May 30, 2003.  No additional data or relevant information to refine the
exposure assessment has been provided by the registrants or other
stakeholders.  The necessary data have been outlined in a section on
"Uncertainty and Data Needs" in the refined assessment.  Nevertheless,
despite the lack of quantifiable data, the existence of substantial
incident data along with liver-residue analysis confirms that birds and
nontarget mammals are being exposed and adversely affected by
applications of rodenticide baits.  The fact that numerous species of
birds and mammals, including predators and scavengers, have been found
exposed to these baits indicates that both primary and secondary
exposures are occurring.

EFED’s risk conclusions are based on analyses of the available data by
a "lines-of-evidence" approach and comparative-analysis modeling. 
Quantitative estimates of risk are used in both; however, the
“lines-of evidence” assessment includes qualitative assessments of
secondary risk based on mortality and other adverse effects reported in
laboratory and field studies, operational control programs, and incident
reports, as well as toxicokinetic data and residue levels reported in
primary consumers.  This approach is in concert with the Guidelines,
which clearly state that professional judgement or other qualitative
evaluation techniques are appropriate for ranking risks using categories
such as low, medium, and high when exposure and effects data are limited
or are not easily expressed in quantitative terms.  A
"lines-of-evidence" approach also has been advocated by the Avian
Effects Dialogue Group for helping to interpret a wide variety of
information. 

EFED also notes that the methodology used is similar to that used in the
Agency’s "Comparative Analysis of Acute Risk From Granular Pesticides"
(EPA 1992) and “A Comparative Analysis of Ecological Risks from
Pesticides and Their Use: Background, Methodology, Case Study” (EPA
1998); both were reviewed by a FIFRA Scientific Review Panel. 
Concerning the latter analysis, the Panel noted the many scientific
uncertainties in the method, yet agreed that it was a useful screening
tool that provides a rough estimate of relative risk.  The Panel made a
number of helpful suggestions to improve the utility of the method, most
of which are included in the risk assessment.  

Comment 2:  It cannot be emphasized enough that the number of nontarget
rodenticide poisoning cases documented to date are indicative of a much
larger problem.  In suburban areas, people are not likely to pick up a
dead animal and send it to a wildlife pathologist to find out why it
died.  In rural areas, birds and animals that succumb to rodenticide
poisoning are simply not likely to be observed or detected.  Small birds
especially are not likely to be well represented in incident data.  Bell
Laboratories, Inc., however, disagrees with the conclusion that many
incident victims are not found.  [2, 5, 15]   

EFED Response to Comment 2:  EFED agrees with comments asserting that
the number of incidents reported is likely only a small portion of
nontarget exposure.  In the "Incident Data:  Birds and Nontarget
Mammals" section of the comparative risk assessment, we note that most
rodenticide incidents likely go undetected except in those rare
instances when a predator carcass happens to be exposed in an open area
(e.g., roadside) where it is observed by someone willing to take the
time and effort to report it to the proper authorities.  In many
situations, carcasses might not be detected, death may be attributed to
natural mortality, or an incident may not be reported for a variety of
reasons, including ignorance, apathy, or failure of authorities to
investigate and confirm the cause of death.  Even if a carcass is found,
a proper evaluation of rodenticide exposure requires necropsy of a dead
animal by a wildlife pathologist.  Liver tissue be extracted, frozen,
and shipped to an analytical laboratory for analysis by high performance
liquid chromatography.  Because so few anticoagulant screens are
conducted, exposure of birds to anticoagulants is likely much more
widespread than the number of incidents suggests.  Most of the incidents
in the EIIS database occurred in New York and California, where state
agencies have taken the time, effort, and expense of screening the liver
of dead animals suspected to have been killed by rodenticides.  Few
other states appear to do so, although Wisconsin has reported several
raptor incidents.

It is inconceivable that New York, California, and Wisconsin are the
only states with nontarget exposure, even though they represent over 95%
of the avian exposure cases.  Rather, we believe this distribution,
coupled with active programs in these states, affirms EFED’s
assessment that smaller birds and nontarget mammals are less likely to
be detected and reported to authorities than are larger individuals,
such as raptors and canids, and they likely are substantially under
represented in the incident database.  The difficulty in finding animal
carcasses, even if systematic searches are conducted, has been discussed
by the Avian Effects Dialogue Group.  It is important to note that,
regardless of the spatial distribution, the incident data available
(more than 300 rodenticide cases) do indicate that a wide variety of
birds and nontarget mammals are being exposed to rodenticides,
especially brodifacoum.  As indicated by the RQ determinations for a
25-g bird in the comparative risk assessment, small birds are
potentially at risk if they eat even a single bait pellet of
brodifacoum, difethialone, or zinc phosphide. Taken together, we believe
these factors make a compelling case for substantial occurrence.

Comment 3:  The RRTF has provided data on over-the-counter sales of
rodenticides to the general public.  The Agency hasn’t made use of
production data.  Many states collect detailed information on use of
field rodenticides labeled restricted use.  [10, 11, 13, 14, 16, 17]

EFED Response to Comment 3:  Adequate information quantifying usage of
rodenticide baits is lacking.  EPA obtains data on the amount of each
product produced annually, but production data provide no information on
when, where, or how the product is used and thus provide little relevant
information for assessing exposure and risk.  The RRTF (Kaukeinen et al.
2000) provided some limited information on the pounds of active
ingredient produced or imported in 1996 and 1997 and the number of
container/placement units for 4 of the 9 rodenticides.  Usage of the
other 5 rodenticides was not addressed.  One problem with the
information provided is that the RRTF does not distinguish between
"containers" and "placement units", although they may differ
substantially.  According to product labels for brodifacoum and
bromadiolone, a placement unit is 3 to 16 oz of bait for rats and 0.25
to 0.50 oz of bait for mice.  However, according to rodenticide product
catalogs, containers (e.g., 10-lb and 25-lb pails; pails containing up
to 80 50-g packs) may contain many placement units.  Differences in size
among containers and between containers and placement units likely
explains the discrepancies in the data provided by the RRTF.  For
example, both brodifacoum and bromadiolone are formulated as 0.005% ai
food baits solely for commensal rat and mouse control.  The data
provided by the RRTF for 1996 indicate that 395 lb ai of brodifacoum was
formulated into more than 40 million "container/placement units" (i.e.,
3 oz bait per container/placement unit), whereas 233 lb ai of
bromadiolone was formulated into few more than 275,000
container/placement units (i.e., 271 oz bait per container/placement
unit).  Such differences also occur for 1997 and for chlorophacinone and
diphacinone (see Table 2 in the refined comparative risk assessment). 
Thus, these data provide little useful information for use in the risk
assessment.  Refining the exposure assessment would necessitate much
better information for each rodenticide, including the amount of bait
applied annually and seasonally; geographically by state or region; in
field settings versus in and around buildings; in urban versus suburban
and rural locales; indoor versus outdoor placements;  applications for
rats versus those for mice; use by the general public versus that by
Certified Applicators; proportion of bait placements made in
tamper-resistant bait stations; and, for chlorophacinone and
diphacinone, use of 0.005% versus 0.01% ai baits.

Regarding state reporting of rodenticide usage, registrants and other
stakeholders had the opportunity to provide any such data they believed
would have been useful for the risk assessment [see also EFED Response
to Comment 1].  Few states actually have any such reporting to our
knowledge, and even the most comprehensive state reports typically only
provide the amount of rodenticide applied per crop without providing any
information of the target pest, seasonal use, application method (e.g.,
broadcast versus bait station), or other such relevant factors. 
Moreover, homeowners and non-certified applicators do not report
pesticide use.  We also note that many of the Special Local Needs field
products for chlorophacinone and diphacinone have not been labeled
restricted use.  Therefore, any reporting to date would not reflect use
of non-restricted field products and thus could be misleading and
inconclusive.  The Rodenticide Cluster RED is requiring that all field
baits be labeled as restricted use, and labels are currently being
revised.  However, even for those states that may report use of
restricted-use products, there is a lag time in collecting, analyzing,
and reporting annual data, and it may be several years before such data
become available.

Comment 4:  The greatest risk to nontarget wildlife is posed by
rodenticides available over-the-counter for essentially unregulated
homeowner use.  Rodenticides should be classified as restricted use
pesticides.  [1, 5]

EFED Response to Comment 4:  This issue will be addressed during the
mitigation phase.

Comment 5:  Rodenticide products should be clearly segregated into
indoor and outdoor use categories.  Outdoor uses of any kind should be
limited to specific situations where use is highly controlled and
closely monitored.  Other countries (e.g., United Kingdom, New Zealand)
have recently placed restrictions on the use of brodifacoum for both
field and homeowner use.

[1, 2, 3, 5]

EFED Response to Comment 5:  This issue will be addressed during the
mitigation phase.

Comment 6:  The Agency shouldn't draw any conclusions on secondary
risks, because studies were of widely differing types, dose regimes,
sample sizes, etc.  [11, 12]

EFED Response to Comment 6:  The rodenticides have been in the
reregistration process for more than 10 years to date, and registrants
have had ample opportunity to propose any standardized testing for any
of the rodenticides.  None have done so.  Standardized studies for each
rodenticide would provide useful comparative information; but, until
registrants conduct and submit such studies, EFED must rely on the
available data.  Some of the available studies were conducted under
similar protocols and with the same test species, and some studies
(e.g., Mendenhall and Pank 1980) have tested the same test species under
the same test protocol to compare the hazards of different rodenticides.
 Other studies have used different protocols, test species, and sample
sizes.  What is readily apparent when examining the variety of data
available is that some rodenticides (e.g., brodifacoum) exhibited
mortality and other adverse effects in many or most test animals in
almost every study, despite the differing protocols and/or test species
used in the study.  When looking at an individual rodenticide, having a
variety of studies with a variety of test species is quite useful and
relevant for assessing the hazards of that rodenticide.

EFED also emphasizes that potential secondary risks are not based solely
on the secondary-hazards studies.  As stated in the introduction to the
comparative risk assessment, assessments of potential secondary risk are
made based on mortality and other adverse effects reported not only in
laboratory studies, but also in field studies and operational control
programs, incident reports, toxicokinetic data, and residue levels
reported in primary consumers.

Comment 7:  Syngenta questions why the Agency wants additional toxicity
data with predators and scavengers and asks "Are not these the organisms
the Agency is trying to protect?" [11]  

EFED Response to Comment 7:  As noted in EFED’s Response to Comment 6,
the Agency has attempted to use the available information as much as
possible throughout the assessment.  For some rodenticides, there may be
insufficient information.  For brodifacoum, some hazards information
exists in the literature, and we have not asked Syngenta or other
brodifacoum registrants for additional hazards studies at this time. 
However, if registrants believe that a standardized study is necessary
to compare risks among rodenticides, or that available data are lacking,
then additional testing would be needed.  

Comment 8:  EPA inappropriately infers risk from exposure.  [10]

EFED Response to Comment 8:  Risk is a function of both toxicity and
exposure, as we have clearly stated in the introduction of the
comparative risk assessment.  For primary risks, a risk quotient (RQ) is
compared to a Level of Concern (LOC).  If an RQ is below the LOC,
minimal risk is presumed.  For example, a presumption of minimal acute
primary risk to birds was made for the first-generation anticoagulants,
because a small bird could eat many bait pellets and be at little risk
of mortality.  In this case, we inferred minimal risk from exposure.

Comment 9:  The RRTF states that one peer reviewer found the comparative
model to be inappropriate.  [10]

EFED Response to Comment 9:  One of the three expert peer reviewers
raised a concern about use of the comparative analysis model as
presented in an earlier draft of the risk assessment.  EFED has made
extensive changes in response to that reviewer’s concerns.  We also
note that the same reviewer also stated that: “The bulk of the
material in the document addresses the development of the weight of
evidence argument.  In general this part of the document is
well-developed and it is hard to argue with the evident conclusion about
each of the nine chemicals.  These conclusions are largely implicit in
the text since the task of deriving a formal assessment for each
chemical is passed over to the decision support analysis.  The case
about each chemical is thoroughly and logically developed in this part
of the document and the document is commendable in showing how the
Agency staff have been able to develop the weight of evidence approach
as a viable approach to the synthesis of a complex body of evidence.” 


Comment 10:  EPA suggests in the risk assessment that risk may be
inferred by the existence of incidents.  This is inappropriate,
scientifically indefensible, and bad science.  Elsewhere in their
comments, the RRTF states that secondary risk is derived solely from
hazards tests.  [10] 

EFED Response to Comment 10:  Rodenticides are very highly toxic to
mammals, including nontarget species, and some also are very highly
toxic to birds, which are nontarget species.  That is confirmed by the
primary- and secondary-hazards testing that has been conducted and by
findings from field, pen, and operational control programs in which
nontarget organisms have been killed.  Baits are formulated to kill
rodents and other mammals (jackrabbits, mongoose, moles, shrews), and
registrants have provided no documentation that baits are selective to
the target species.  Therefore, exposure to rodenticide baits does
involve a degree of risk, although the degree varies among the
rodenticides.  The existence of substantial incident data (more than 300
documented cases) along with liver residues provides important support
for the assumption that nontarget birds and mammals are exposed and at
risk from the use of at least some rodenticides.  Death has been
attributed to brodifacoum exposure in some individuals having
liver-residue levels as low as 0.007 to 0.077 ppm.  These incidents
refute the RRTF’s contention that liver-residue levels less than an
arbitrary "toxicity threshold" of 0.7 ppm for mortality.  The incidents
are discussed in more detail in the section entitled "Incident Data: 
Birds and Nontarget Mammals" in the comparative risk assessment. 

Comment 11:  When homeowners or applicators are using rodenticides
according to label directions, they are placing them in inaccessible
areas in and around structures or in tamper-resistant bait stations that
greatly limits risk and selectivity of these products.  Incident data
include dissimilar practices and cannot be directly compared.  [11]

EFED Response to Comment 11:  Documentation of how homeowners are
applying bait and complying with label directions is lacking.  The RRTF
(Kaukeinen et al. 2000, Anonymous 2001 - see footnotes 4 and 11) argues
that many of the documented nontarget incidents are due to misuse, in
which case applicators are not baiting according to label directions.  A
major concern is that most outlets selling rodenticide baits over the
counter (e.g, grocery stores, hardware stores) do not sell bait
stations, and most homeowners would not know where to find and purchase
tamper-resistant bait stations even if they were willing to do so.  EFED
also questions how outdoor applications for rats and mice can be made in
areas accessible only to the target species, and product labels provide
no advice on how to do so.  Even if properly secured, tamper-resistant
bait stations are used, they do not prevent small animals from entering
the stations and obtaining bait, nor does the use of bait stations
preclude secondary exposure of predators and scavengers.  The incident
data cited in the risk assessment indicate that nontarget animals are
being exposed, and the Animal Poison Control Center reports 2334 cases
with rodenticides, particularly brodifacoum (1161 cases), between
November 2001 and June 2003.  Most pet cases involved exposure of dogs. 
These data seem to indicate that exposure is occurring and raise the
question whether the rodenticide baits, as currently used, can continue
to be used without resulting in nontarget exposure of pets and wildlife.

Comment 12:  How was the weight-of-evidence assessment performed? [19,
21, 23]

EFED Response to Comment 12:  As stated in the introduction of the
comparative risk assessment, risk conclusions are based on two analyses
of the available data.  One is a comparative ranking of the potential
risk based on a comparative-analysis model, and the other is a tabular
comparative rating of potential risk based on a “lines-of-evidence”
approach.  Quantitative estimates of risk are used in both; however, the
“lines-of evidence” assessment includes qualitative assessments of
secondary risk based on mortality and other adverse effects reported in
laboratory and field studies, operational control programs, and incident
reports, as well as toxicokinetic data and residue levels reported in
primary consumers.  The potential-risk rankings are in accord with the
EPA’s Risk Assessment Guidelines, which deem professional judgement or
other qualitative evaluation techniques as being appropriate for ranking
risks according to categories such as low, medium, and high when
exposure and effects data are limited or are not easily expressed in
quantitative terms. [see also EFED Response to Comments 1 and 13]

Comment 13:  The NYSDEC states that the weight-of-evidence (i.e.,
lines-of-evidence) methodology used in the risk assessment provides an
objective assessment of the various rodenticides.  They believe that
brodifacoum presents the greatest potential for risk to nontarget birds
and mammals, which is consistent with the incident findings of the New
York State Wildlife Pathologist.  [2]

EFED Response to Comment 13:   We agree, and we thank the NYSDEC for
providing incident reports for EFED’s Ecological Incidents Information
System (EIIS).  We also note that the California Department of Pesticide
Regulation and the California Department of Fish and Game stated in
their comments that they agree with most of the conclusions in the
comparative risk assessment as well, particularly for those rodenticides
used for commensal control.  We also thank the CDFG for providing
incident reports from California.

Comment 14:  EPA wrongly assumes that all rodenticide baits weigh 0.2 g
per pellet.  [10, 21, 23]

EFED Response to Comment 14:  EPA assumes that a typical rat-bait
pellets weighs 0.2 g, based on information provided by Syngenta as cited
in the refined comparative risk assessment.  No other information on
pellet or whole-grain size was provided by registrants or other
stakeholders during the "errors-only" and "public comment" periods [see
also EFED Response to Comment 1].  We did calculate the number of 0.2-g
pellets needed to provide an LD50 dose to a bird or nontarget mammal
weighing 25 g, 100 g, and 1000 g.  However, we realize that some bait
pellets or grains may be smaller or larger than the typical rat-bait
pellet, and some are formulated as meal or wax blocks.  Therefore, we
also calculated the amount of bait that would need to be eaten by a bird
or nontarget mammal to provide an LD50 dose, and we calculated what
percent of the diet that would comprise.  The later calculations are
independent of pellet or grain size. 

Comment 15:  The American Society for Prevention of Cruelty to Animals
(ASPCA) Poison Control Center has many incidents for pets exposed to
rodenticides, especially brodifacoum.  EPA should obtain this
information.  [5]

EFED Response to Comment 15:  EFED is aware that the ASPCA Animal Poison
Control Center has reported 2334 cases involving 2685 animals from
November 01, 2001 to June 16, 2003 (S. Hansen pers comm. to W.
Erickson).  The number of cases were 1161 for brodifacoum, 511 for
bromadiolone, 218 for zinc phosphide, 206 for diphacinone, 66 for
bromethalin, 48 each for difethialone and warfarin, 42 for
chlorophacinone, and 34 for cholecalciferol.  Although adverse effects
to pets and other domestic animals are addressed by OPP’s Health
Effects Division, we believe that these data augment the wildlife
incident data in demonstrating that nontarget animals are being exposed
to rodenticide baits.

Comment  16:  Label language needs to be more precise regarding where
and how rodenticides are placed in order to avoid confusion.  The label
should indicate potential adverse effects.  People using rodenticides
around their homes need to be aware of how their local domestic-life and
wildlife could be harmed or killed as secondary nontarget species.  [7]

EFED Response to Comment 16:  We appreciate the comments of the
Grassroots Coalition regarding the need to improve label language to
warn of potential nontarget risks.  Label directions and precautionary
measures will be dealt with during the mitigation phase.

Comment 17:  The risk assessment does not consider individual products. 
Product characteristics such as pellet or grain size, color,
stabilizers, waxes, and others offer some degree of selectivity.  [13,
16, 17, 18, 21, 23]

EFED Response to Comment 17:  Reregistration is an assessment of the
active ingredient.  Various properties of individual products that might
reduce risks will be considered when mitigation issues are addressed,
providing that registrants have provided appropriate data to support any
claims of selectivity.  Mitigation issues such as mandatory use of bait
stations can also be addressed during this next phase of review.

Comment 18:  The available mammalian toxicity data are not sufficient to
present a full mortality danger to the various mammalian species.  The
Agency should require a mammalian acute dietary test.  [2, 5]

EFED Response to Comment 18:  EFED agrees that additional
mammalian-toxicity information would help reduce the uncertainty
associated with risk estimation.  While EFED can request a wild mammal
toxicity test, EFED has not previously required this test for
rodenticides.  Rodenticides are formulated and proven to be toxic to
small mammals, and there is no evidence that they are selective to the
target species.  However, we will consider the value of a wild-mammal
toxicity test when determining what additional data would be useful for
reducing uncertainties in the assessment. 

We have recently located reports of rat dietary tests conducted at
EPA’s former toxicology laboratory in Beltsville, MD, where McCann et
al.(1981) developed a short-term dietary LC50 test for small mammals. 
They exposed immature albino Norway rats (Wistar strain) to dry diet
offered ad libitum and treated with one of 17 chemicals pesticides,
mostly organophosphate and carbamate pesticides.  The tests consisted of
a 5-day acclimation period, a 5-day exposure period, and a
post-treatment observation period lasting at least 9 days.  Following
submission of the paper for publication, testing continued and included
brodifacoum, bromadialone, chlorphacinone, diphacinone, and warfarin. 
Results of the rodenticide testing were not published, but EFED now has
the test reports and has incorporated these data in the risk assessment.


Comment 19:  The CDFA notes that uncertainties in the assessment can be
addressed by requiring new data where necessary.  Such data should
include residue data to evaluate secondary exposure, mammalian
subchronic toxicity data to evaluate secondary exposure risks to
nontarget mammals, and use of avian subacute toxicity or avian
reproduction data to evaluate secondary exposure risks to birds. [18]

EFED Response to Comment 19:  We agree that additional data would reduce
uncertainties in the risk assessment, especially to assess sublethal
(e.g., reproductive) effects and to quantify exposure.  However, we
disagree that avian and mammalian reproduction data can be used to
assess secondary risk.  Reproduction data are used to assess chronic
risk, not secondary risk.  The available secondary-hazards data are
presented in the comparative risk assessment.  Additional data on
potential for secondary exposure would help refine the assessment, and
we would have incorporated any relevant information if registrants or
other stakeholders had made any available. [see also EFED Response to
Comment 1]

Comment 20:  The Agency should consider factors such as diet and food
preferences, proximity of habitat to use areas, home range, etc. in
assessing risks.  [18]

EFED Response to Comment 20:  The Agency has received no such data from
the rodenticide registrants or other stakeholders [see also EFED
Response to Comment 1].  As noted in the comparative risk assessment,
there are many factors that influence which nontarget animals might be
exposed to rodenticide baits.  They include the species found in and
around treatment areas, species’ food habits and foraging behavior,
home range, propensity to feed in and near human buildings, bait
availability (e.g., quantity, how applied, where applied, when applied),
and other such factors.  However, there is no doubt that many birds and
nontarget mammals are attracted to and will consume grain-based foods. 
Additionally, many nontarget predators and scavengers feed on rats, mice
or other target species.  They are not likely to avoid feeding on rats,
mice, voles, ground squirrels, or other animals that have eaten bait. 

Comment 21:  EPA has not utilized the large set of subchronic/chronic
mammalian toxicity studies that are available for most, if not all, of
the rodenticides. [16, 17, 18] 

EFED Response to Comment 21:  EFED utilizes the rat two-generation
reproduction test to assess chronic risks to mammals.  This study is
required by OPP’s Health Effects Division (HED) to support pesticides
with food uses or where use of the product is likely to result in human
exposure over a significant portion of the human lifespan.  This study
is not currently available for any of the rodenticides.  HED requires
numerous other subchronic/chronic studies (e.g., dermal, inhalation,
oncogenicity, neurotoxicity) to assess risks to humans, but these
generally are not relevant to assessing risk to mammalian wildlife.  For
assessing chronic risk to birds, EFED uses avian reproduction studies
with the northern bobwhite and mallard.  The avian reproduction studies
have previously been required by the Agency on a case-by-case basis, but
the updated guideline requirements soon to be published will require
these studies for all pesticides having outdoor uses.  EFED can better
assess the potential for adverse reproductive effects when these data
become available.  [see also EFED Response to Comment 22]

Comment 22:  The RRTF disagrees that sublethal doses can have adverse
effects.  Bell Laboratories, Inc. states that EPA’s present
infatuation with the concept of ‘sub-lethal effects’ of
anticoagulants is an attempt to find a problem where none exists.  [10,
15]

EFED Response to Comment 22:  EFED disagrees with these comments. 
Despite the lack of reproductive data for birds and mammals [see EFED
Response to Comment 21], evidence exists that sublethal doses can have
adverse effects.  For example, poisoning symptoms (e.g., bleeding,
delayed blood-coagulation times) have been reported in birds and mammals
that survived exposure in some of the secondary-hazard studies discussed
in the comparative risk assessment (see secondary-hazards tables for
birds and mammals).  The Warfarin RED notes that warfarin is a
teratogen, and product labels are required to warn "Exposure to warfarin
during pregnancy should be avoided.  Warfarin may cause harm to the
fetus, including possible birth defects."  The Rodenticide Cluster RED
reports developmental toxicity (e.g., vaginal bleeding, hypotonicity) in
rats and rabbits exposed to bromadiolone at about two orders of
magnitude less than the LD50 dose.  In brodifacoum studies, internal
hemorrhage and significantly prolonged prothrombin time of rabbits was
reported for those dosed, during gestation, at about two orders of
magnitude less than the LD50 dose.  A recently published article
reported that brodifacoum was detected in two dog pups that died a few
hours after birth (Munday and Thompson 2003).  Of 13 pups in a single
litter, eight were born dead or died within 48 hours of birth.  Three
puppies that died shortly after birth were necropsied.  Two exhibited
hemorrhage in the thoracic and peritoneal cavities, intestinal serosa,
and meninges, and brodifacoum was detected in the liver of both puppies.
 The mother did not have clinical signs of coagulopathy before or
subsequent to whelping, and the authors suggest that fetuses may be more
susceptible to brodifacoum than are adult animals.  EFED believes that
reproductive studies are needed to further clarify possible adverse
reproductive effects of the nine rodenticides and to assess the possible
significance of sublethal doses in primary exposure.

The Avian Effects Dialogue Group (see footnote 2) also discussed the
issue of sublethal effects of pesticides on birds.  The Group notes that
". . . effects that are sublethal under the controlled environmental
conditions of a laboratory might result in decreased survival or
reproduction in the field."  The Group also discussed several of the
factors that may result in sublethal effects becoming lethal under field
conditions or which may lead to a reduction in reproductive success. 
Such factors include physiological parameters, environmental conditions,
synergisms with other chemicals, formulation type, and route of
exposure.

Comment 23:  It is inappropriate to compare different modes of action. 
[11]

EFED Response to Comment 23:  EFED compares the potential nontarget
risks of the nine rodenticides.  Six of the rodenticides are
anticoagulants and three are not.  However, all nine rodenticides are
registered for control of commensal rats and mice in and around
buildings.  Therefore, it is appropriate to compare all nine, because
they are alternatives for one another for control of commensal rats and
mice in and around buildings.  

Comment 24:  Using rat toxicity data is not appropriate for 1-kg
mammals, such as canine or feline, because rodenticides are more toxic
to rodents than to other mammals.  [11, 13]

EFED Response to Comment 24:   There is no scientific basis for that
statement.  As can be seen from the toxicity tables in the comparative
risk assessment, rodenticides are not necessarily more toxic to rats and
mice or other rodents than to other mammals.  Brodifacoum, for example,
is very highly toxic to the rabbit (LD50 = 0.29 mg/kg), possum (LD50 =
0.17 mg/kg), dog (LD50 = 0.25-1.0 mg/kg), and pig (LD50 <2.0 mg/kg), and
diphacinone is very highly toxic to the mongoose (LD50 = 0.2 mg/kg) and
coyote (LD50 = 0.6 mg/kg).  We have followed EFED policy in using rat or
mouse toxicity data to extrapolate to a 1-kg mammal and, based on the
available toxicity data, believe it is appropriate in the comparative
risk assessment.  

Comment 25:  Information from field studies is irrelevant to use of
rodenticides for commensal uses.  [11]

EFED Response to Comment 25:  Field studies are useful in demonstrating
that exposure to rodenticide baits or consumption of target or nontarget
animals poisoned from eating bait can have adverse effects to nontarget
birds and mammals.  More emphasis could be placed on information from
commensal studies if registrants were to conduct such studies for each
of the nine rodenticides and using focal species that feed on rats
and/or mice.  One commensal study was undertaken with potential exposure
of barn owls to brodifacoum-poisoned rats and mice on farms in New
Jersey.  That study provided a wealth of information on barn owl
biology, but found that the owls fed predominantly on voles, not rats
and mice.  Other avian and mammalian predators and scavengers, as well
as avian and mammalian primary consumers, need to be addressed in
commensal settings.

Comment 26:  Syngenta questions why EFED cited residues in a possum
"when the issue is with birds".  [11]

EFED Response to Comment 26:  The Agency’s issue of residue levels and
risks to nontarget animals is not limited to birds but also includes
nontarget mammals.

Comment 27:  EPA has not used residue data to quantify secondary
exposure.  [18, 21, 23] 

EFED Response to Comment 27:  Residue data alone do not quantify
exposure.  However, the presence of residue in animals that have eaten
bait does confirm exposure and potential risk.  [see also EFED Response
to Comment 1]

Comment 28:  The greatest risk to nontarget wildlife is from
over-the-counter rodenticides available for unregulated homeowner use. 
[1]

EFED Response to Comment 28:  This is an issue that will be addressed
during the mitigation phase of reregistration.

Comment 29:  The 2000 draft of the comparative risk assessment contains
important statements about birds and mammals that are omitted from the
version released to the public.  [5] 

EFED Response to Comment 29:  The initial version of the Agency's
comparative risk assessment contained information related to possible
risk mitigation.  OPP management decided that those issues would best be
addressed during the mitigation phase of reregistration and not in the
risk assessment. 

Comment 30:  The true impacts of brodifacoum on birds of prey are
understated.  [6]

EFED Response to Comment 30:  As stated in the comparative risk
assessment, EFED believes that brodifacoum poses a potentially high risk
to birds of prey exposed to primary consumers of brodifacoum bait.  The
incident data confirm that birds of prey, especially owls (e.g., great
horned owl), hawks (e.g., red-tailed hawk), and eagles (e.g., golden
eagle), are being exposed to brodifacoum, and the toxicity data
demonstrate that brodifacoum is very highly toxic to birds. Thus,
preliminary information on both exposure and hazard indicate potential
risk to birds of prey, as do the available incident data. 

Comment 31:  The RRTF disputes long-term bioaccumulation, because
binding sites in the liver are limited.  [10]

EFED Response to Comment 31:  The RRTF has not provided any
documentation to support this assertion.  Moreover, as we note in the
"Incident Data:  Birds and Nontarget Mammals" section of the comparative
risk assessment, retention and accumulation of anticoagulants is not
limited to the liver but occurs in other organs and tissues as well. 
Concentrations in the liver are often, but not always, higher than in
other tissues.  However, because the liver comprises only about 4 to 7%
of the weight of a rat or mouse (Newton et al. 1990, Howald et al.
1999), most residue actually may accumulate in other parts of the
carcass.  For example, Newton et al. (1990) reported a much higher mean
residue concentration in liver (2.13 + 0.33 ppm) than in the remainder
of the carcass (0.36 + 0.05 ppm) of 10 mice fed brodifacoum bait. 
However, the mean total amount of residue in the carcass (without the
liver) was 11.85 + 1.54 ppm versus only 3.51 + 0.66 ppm in the liver. 
The section of the comparative risk assessment entitled "Comparative
Toxicokinetics:  Absorption, Metabolism and Excretion of Anticoagulants"
also discusses some of the residue levels detected in various organs and
tissues of exposed animals.

Comment 32:  Regarding diphacinone, the RRTF and HACCO, Inc. note that
residue data in ground squirrels (EPA MRID nos 435346-01 and -02) were
not included in the risk assessment, and the "wrong" rat LD50 is used. 
Also, they believe that EFED should accept a secondary-hazards test with
the rat (Bullard et al. 1976) to fulfill a data requirement (70-A-SS)
for a secondary-poisoning test with a mammalian predator or scavenger.
[10, 14]

EFED Response to Comment 32:  Based on the EPA MRID numbers provided by
the registrant, EFED has obtained copies of the efficacy field tests in
which residues were determined in ground squirrels.  We have included
those data in the refined risk assessment.  Regarding the rat LD50, the
existence of a "core" study does not mean that the results from other
scientifically sound studies, albeit ones which deviated in minor ways
from Agency guidelines, should be ignored.  In a preliminary risk
assessment, the Agency typically uses the toxicity values for the most
sensitive organisms tested in scientifically sound studies in the
assessment of risk.  A refined assessment will attempt to address the
magnitude and likelihood of the risk based on a distribution of
available data, if sufficient data exist to make such an analysis.

The Rodenticide Cluster RED issued in July, 1998, required secondary
toxicity studies with a mammalian predator and an avian predator to
support reregistration of 0.005% ai and 0.01% ai diphacinone baits. 
More than five years have passed without diphacinone registrants
providing the required data.  The Bullard et al. (1976) study does not
fulfill this data requirement for several reasons.  Because the rat is a
target species for all diphacinone products with commensal uses, it
isn't considered to be of ecological or regulatory relevance for
fulfilling a data requirement for a nontarget species.  Moreover, the
rats were fed only liver tissue from cattle sublethally dosed with
diphenadione.  Cattle are not a target species, they were only
sublethally dosed, and only liver tissue was fed to the rats.  At this
time, a more appropriate question is why haven’t diphacinone
registrants addressed the outstanding data requirements rather than
attempting to cite inadequate and inappropriate data.

Comment 33:  Syngenta asks why the Agency assumes that incidents with
avian and mammalian predators and scavengers are the result of secondary
exposure.  "The incident data is principally based upon carcass
autopsies and thus cannot determine the route of exposure.  It is
unknown."  [11]

EFED Response to Comment 33:  For predator and scavengers, EFED simply
states that poisoning was likely due to secondary exposure based on the
species involved and their food habits.  We acknowledge that tertiary
exposure likely occurs as well.  However, it seems highly unlikely that
species such as the great horned owl, red-tailed hawk, golden eagle, or
weasels would consume bait, and registrants have provided no information
that primary exposure is important for these species.  Nevertheless, we
realize that some omnivores may eat bait as well as poisoned animals,
and the actual routes of exposure may be unknown for some species.  For
example, we do know that dogs will consume rodenticide baits [see also
EFED Response to Comment 15], and it is feasible that wild canids (e.g.,
coyote, kit fox, red fox) may do so in addition to capturing and feeding
on dead and dying rodents and nontarget birds and mammals that have
eaten bait.  

Comment 34.  Syngenta claims that dog LD50 values are incomplete for
brodifacoum, and that the Agency has been given other publications with
more robust LD50 values than the 0.25 to 1 mg/kg value cited in the
comparative assessment.  They state that the definitive dog LD50 of 3.56
mg/kg was established in New Zealand (M.E.R. Godfrey, 1981, New Zealand
J. Expt. Agriculture 9:147-149).  [11]

EFED Response to Comment 34:  EFED has utilized the toxicity data
submitted by registrants to support the registration of brodifacoum. 
Those data are submitted to OPP’s Health Effects Division (HED) and
are provided in HED’s "Tox Oneliners’ database.  For brodifacoum,
the database contains only one acute-oral toxicity study with the dog,
and EFED has cited that value in the comparative risk assessment.  The
database does contain results of a dog study from New Zealand in 1981
(EPA MRID No. 251781), but that was an antidote study in which the dosed
dogs also were treated with vitamin K.  To use an LD50 derived from an
antidote study would be misleading and inappropriate.  

Comment 35:  Zinc phosphide liberates phosphine, not phosgene as stated
in two instances in the risk assessment.  [15]

EFED Response to Comment 35:  This has been corrected in the refined
risk assessment.

Comment 36:  Data in Diaz and Whitacre (1976) indicate that elimination
of diphacinone in the rat is rapid and similar to chlorophacinone. 
These data were not included in Table 37 or in

EPA’s analysis, which relied only on elimination data for blood and
liver.  [10]

EFED Response to Comment 36:  These data are discussed in the risk
assessment.  The tabulated data are half-lives and retention times
(days).  Those values are not obtainable from Diaz and Whitacre (1976);
as stated in the risk assessment, nearly a third of the dose
administered was not recovered in the study, which limits its
usefulness.

Comment 37:  The risk assessment states that difethialone is expected to
pose similar risks to brodifacoum due to their very similar chemical
structures. It does not, however, make this conclusion for diphacinone
and chlorophacinone, which also differ by only one atom in their
structures.  Rather, in some areas, it reaches relatively different
conclusions about these two compounds. How can these dissimilar
conclusions be justified?  [15]

EFED response to Comment 37:  This comment is somewhat misleading.  The
risk assessment actually says the conclusions of comparable risks for
brodifacoum and difethialone are assumed based not only on very similar
chemical structures but also on nearly identical acute-toxicity profiles
and physical/chemical properties (see "Attachment A:  Chemical
Structures and Selected Physical/Chemical Properties of the
Rodenticides" and the toxicity tables in the comparative risk
assessment).  In contrast, although chlorophacinone and diphacinone have
similar chemical structures, they differ to a greater extent in their
toxicity and physical/chemical structures.  Additionally, some
secondary-hazards data are available for both chlorophacinone and
diphacinone, whereas secondary-hazards data have not been submitted for
difethialone.  

A more relevant question is why hasn’t LiphaTech, Inc. submitted
secondary-hazards data for difethialone.  EFED is aware that a paper
involving difethialone secondary-hazards information for birds and
mammals was presented at a symposium, although the performing laboratory
(National Wildlife Research Center) declined to provide any additional
details on the study when they were contacted.  Subsequently, at a
meeting with OPP in September of 2001, LiphaTech, Inc. stated that they
had contracted the study and would submit it for review.  They have not
done so, even though submission of adverse-effects data is required
under FIFRA 6a(2) reporting.

Comment 38:  APHIS and TZPC question why EFED hasn’t used use
information they provided to an EFED reviewer at a meeting in 1996. 
[16, 17]

EFED response to Comment 38:  EFED welcomed any relevant use data for
zinc phosphide and the other rodenticides.  We are not aware of the
information referred to, which apparently was use information from the
early to mid-1990s, and there is no such information in EFED’s zinc
phosphide chemical file.  However, we do question whether use data from
more than 10 years ago would be relevant at this time.  APHIS and the
ZPC had ample opportunity to provide up-to-date usage data during the
comment periods.  [see also EFED Response to Comment 3]

ATTACHMENT 2

Field and Other Outdoor Uses of Zinc Phosphide, Diphacinone, and
Chlorophacinone for Control of Rodents and Other Mammalian Pests

Note:  The tabulated information is based on a review of registered
product labels current as of May 2005.  Several labels were not
available for review; thus, the information may not be complete. 
However, EFED believes that the majority of uses and target species have
been captured in this table.  Due to the variety of target species and
use sites, the tables are arranged differently for zinc phosphide and
diphacinone and chlorophacinone, but each table provides information on
use sites, target species, application methods, application rates and
intervals if specified on product labels, and whether prebaiting is
required for zinc phosphide uses.  Only the common names of target
species are presented in the tables; the scientific names are listed
after the last table.

Zinc Phosphide:

Many zinc phosphide baits are formulated as 2% ai (20,000 ppm) grain
(corn, oats, wheat, barley, rye, millet, milo) baits or grain-based
pellets.  Other baits include 3.25 % ai meat-based baits (ground meat,
canned dog or cat food, or dry meat-based pet food), 3.25% ai
sunflower-seed baits, and 1% ai baits made with fruit (grapes, mulberry,
apricots, figs, apples, pears), nuts (unspecified types), vegetables
(carrots, sweet potato, potato, cabbage), or fresh vegetation (alfalfa,
dandelions, beet tops).  A 1% ai grain bait is registered for use only
in California.  Prebaiting with untreated bait for 2-3 days prior to
bait application is recommended, but not required, for some uses as
noted in the table.



Zinc Phosphide registered field/outdoor uses



Use site/

Target spp.	

Application methods

(grain or pelleted bait unless otherwise specified)	

Single

appl. rate 

(lb bait/acre)	

No.

appl.	

Pre-bait?



Around Buildings:



White-footed

   mouse

Voles 

[also includes commensal rats and mice]	

Hand Baiting and/or Bait Stations;

Baits include:  

  · Meats (ground meat, canned or

    dry dog or cat food)

  · Gains (wheat, oats, barley, rye,

     milo, or millet) 

  · Fruits (grapes, mulberry, apricots,

    figs, apples, pears)

  · Sunflower seeds

  · Nuts

  · Vegetables (carrots, sweet

     potato, cabbage, potato) 

  · Greens (alfalfa, dandelions, 

     beet tops)	

not specified	

unlimited	

no



Orchards (dormant season only) and/or Groves:



White-footed

   mouse

Voles

Ground squirrels

  (CA only)

	

Aerial or Ground Broadcast

Machine Baiting   

Bait Stations 

Hand Baiting  

note: includes sunflower-seed baits	

6-10 

3-6 

not specified

2-3 or not

   specified

	

unlimited	

no



Ground squirrels	

Ground Broadcast

Hand Baiting

note: includes fruit and vegetable baits	

6 

not specified	

>30-day int.

unlimited	

yes



Woodrats	

Hand Baiting	

not specified	

unlimited	

no



Cotton rat

Voles

Ground squirrels	

Hand Baiting 

(CA only)	

not specified	

unlimited	

yes



Commensal rats

	

Hand Baiting   

(CA only)	

not specified	

every 3 mo.	

yes



Vineyards:



White-footed

   mouse

Voles	

Aerial or Ground Broadcast

Trail Builder (mechanical)

Hand Baiting

note:  includes fruit and sunflower- seed baits	

6-10 

2-3 

3-5	

unlimited	

no



Ground squirrels	

Ground Broadcast

Hand Baiting

note: includes fruit and vegetable baits	

6 

not specified	

>30-day int. 	

yes



Voles

Native mice	

Ground Broadcast	

6-10	

unlimited	

no



Ground squirrels

	

Ground Broadcast

Hand Baiting

(CA only)	

6-10	

unlimited	

yes



Ground squirrels

Voles

Cotton rat	

Hand Baiting

(CA only)	

not specified	

unlimited	

yes



Commensal rats	

Hand Baiting	

not specified	

every 3 mo.	

yes



Rangeland (including adjacent timber areas in MT and WY only):



Ground squirrels	

Hand Baiting	

not specified	

unlimited	

yes



Ground squirrels

  	

Aerial or Ground Broadcast

Hand Baiting

(CA only)	

6-10

not specified	

1

1	

yes



Voles	

Aerial or Ground Broadcast

(CA only)	

6	

1	

yes



Voles

White-footed

   mouse

	

Aerial or Ground Broadcast

Trail Builder

Hand Baiting	

6-10 

not specified

not specified	

unlimited	

no

	

Trail Builder (mechanical)

Hand Baiting 	

2-3 

3-5 	

unlimited	

no



Woodrats 

Kangaroo rats	

Hand Baiting	

not specified	

unlimited	

no



Woodchuck

Marmot

Black-tailed

   jackrabbit	

Hand baiting	

not specified	

unlimited	

yes



Moles

Pocket gophers	

Burrow Builder (mechanical)	

2-3 	

unlimited

	

no





Commensal rats 	

Hand Baiting

(CA only)	

not specified	

every 3 mo.	

yes



Rangeland and Pastures in ND, SD, NE, KS, OK, TX, NM, AZ, CO, MT, UT,
NV, and WY:



Prairie dogs	

Hand Baiting

note: treatments can be made only from July to February	

not specified	

1	

yes



Ground squirrels	

Aerial or Ground Broadcast 

(MT only)

Hand Baiting  

(MT and WY only)	

<6	

unlimited	

yes



Reforestation areas and/or Forest areas:



Voles

White-footed

   mouse	

Aerial or Ground Broadcast

Trail Builder (mechanical)

Hand Baiting 	

6-10 

2-3 or ns

3-5 or ns	

unlimited	

no



Pocket

   gophers	

Burrow Builder (mechanical)

Hand Baiting 	

1-3

not specified	

unlimited	

no



Noncrop Rights-of-way: 



Ground squirrels	

Hand Baiting	

not specified	

unlimited	

yes



Voles	

Aerial or Ground Broadcast	

6-10	

unlimited	

yes



Voles	

Ground Broadcast	

<6	

1	

yes



Ground squirrels	

Ground Broadcast

Hand Baiting  

note: includes fruit and vegetable baits	

6 	

>30-day int.	

yes



Woodrats

Kangaroo rats 

Ground squirrels

Voles

Cotton rat	

Hand Baiting	

not specified	

unlimited	

no



Commensal rats 	

Hand Baiting

(CA only)	

not specified	

every 3 mo.	

yes



Pocket

   gophers	

Burrow Builder (mechanical) 

Hand Baiting	

1-3

not specified	

unlimited	

no



Sugarcane Fields:



Commensal rats

Native rats	

Aerial or Ground Broadcast	

5	

4	

yes



Noncrop areas:



Voles

White-footed

   mouse	

Ground Broadcast

Trail Builder (mechanical) 

Hand Baiting	

6-10 

2-3

3-5	

unlimited	

yes



Woodchuck

Marmot

Black-tailed

   jackrabbit

Kangaroo rats

Ground squirrels

Voles

Moles	

Hand baiting	

not specified	

unlimited	

yes



Ground squirrels	

Aerial or Ground Broadcast

(MT only)	

<6	

unlimited	

yes



Pocket

   gophers	

Burrow Builder (mechanical) 

Hand Baiting 	

2-3 

not specified	

unlimited	

no



Sugar beets (CA only):



Voles	

Aerial or Ground Broadcast

note: aerial allowed only for overwintered beets	

5-10	

2 

(30 day int.)	

yes



Macadamia Nut Orchards and Noncrop Sites Adjacent to Orchards (HI):



Commensal rats 	

Aerial or Ground Broadcast

Bait Stations

Burrow Treatment 	

5 

not specified 

not specified 	

4	

no



Pastures:



Voles

White-footed

   mouse	

Aerial or Ground Broadcast

Trail Builder (mechanical)  

Hand Baiting	

6-10 

2-3 

3-5 	

unlimited	

no



Ground squirrels	

Ground Broadcast

Hand Baiting 	

6

not specified	

>30-day int.	

yes



Woodchuck

Marmot

Black-tailed

   jackrabbit

Woodrats

Ground squirrels	

Hand baiting	

not specified	

unlimited	

yes



Tree farms:



Woodrats 

Kangaroo rats 	

Hand Baiting	

not specified	

unlimited	

no



Nurseries, and/or Ornamentals, Highway medians, Plantings of nonbearing
fruit trees, Conifer/Christmas trees:



Voles

Ground squirrels	

Hand Baiting 	

not specified	

unlimited	

yes



Voles	

Ground Broadcast

Hand Baiting	

6-10 

2-3 	

unlimited	

no



Voles

White-footed

   mouse	

Aerial or Ground Broadcast

Trail Builder (mechanical)  

Hand Baiting 	

6-10 

2-3 

3-5 	

unlimited	

no



Ground squirrels	

Ground Broadcast

Hand Baiting	

6 

not specified	

>30-day int.

unlimited	

yes



Voles

White-footed

   mouse	

Ground Broadcast 

Trail Builder (mechanical)  

Hand Baiting 	

6-10

2-3 

3-5	

unlimited	

yes



Commensal rats 	

Hand Baiting

(CA only)	

not specified	

every 3 mo.	

yes



Pocket gophers	

Burrow Builder (mechanical)  

Hand Baiting	

2-3 

not specified	

unlimited	

no



Ground squirrels

Voles

Cotton rat

Norway rat

Roof rat	

Hand Baiting	

not specified	

unlimited	

yes



Berry production (blueberry, blackberry, gooseberry, boysenberry,
raspberry, strawberry):



Voles

White-footed

   mouse	

Ground Broadcast 

Trail Builder (mechanical)

Hand baiting 	

6-10 

3-4 

3-5 	

unlimited 	

no



Croplands:



Pocket gophers	

Burrow Builder (mechanical)

Hand Baiting 	

1-3 

not specified	

unlimited	

no



Moles

Pocket gophers	

Hand Baiting 	

not specified	

unlimited	

no



Ground squirrels	

Hand Baiting

(MT only)	

<6	

unlimited	

yes



Corn Fields (no-till and minimum -tillage operations in OH only):



Voles

House mouse	

Aerial or Ground Broadcast

Planter Application	

6-10

4-6	

1-2

1	

no



Alfalfa and/or Timothy Hay Fields:



Meadow voles 	

Aerial or Ground Broadcast

(after cuttings)

(CA only)	

6-10	

2

(30-day int.)	

yes



Meadow vole	

Bait Stations 	

not specified	

unlimited	

no



Pocket gophers	

Burrow Builder (mechanical) 

Hand baiting 	

2-3 

not specified	

unlimited	

no



Ground squirrels	

Hand Baiting

(MT only)	

<6	

unlimited	

yes



Uncultivated Agricultural Areas (CA only):



Voles	

Aerial or Ground Broadcast	

6-10	

unlimited	

yes



Commensal rats	

Hand Baiting	

not specified	

unlimited 	

yes



Waterways (streams, lakes, canals, ponds, bayous), Croplands, Turf:



Muskrat  

Nutria	

Baiting on anchored rafts

(4' x 4' or 6" x 6")	

not specified	

>30-day int.	

yes



Rights-of-way:



Voles

White-footed

   mouse	

Ground Broadcast

Trail Builder (mechanical) 

Hand Baiting 	

3-10 

2-3

3-5 	

unlimited	

yes



Ground squirrels	

Ground Broadcast

Hand Baiting  	

6 	

>30-day int.	

yes



Ground squirrels

Woodrats

Voles

Cotton rat	

Hand Baiting

(CA only)	

not specified	

unlimited	

yes



Voles 	

Aerial or Ground Broadcast

(CA only)	

6-10	

unlimited	

yes



Commensal rats 	

Hand Baiting

(CA only)	

not specified	

every 3 mo. or not spec.	

yes



Along fence rows:



Ground squirrels	

Ground Broadcast

Hand Baiting 	

6 

not specified	

>30-day int.	

yes



Crop rights-of-way and/or Noncrop borders :



Ground squirrels	

Ground Broadcast

Hand Baiting	

6 

not specified	

>30-day int.	

yes



Voles	

Aerial or Ground Broadcast

(CA only)	

6-10	

unlimited	

yes



Commensal rats 	

Hand Baiting

(CA only)	

not specified	

every 3 mo.	

yes



Recreational Areas (e.g., campgrounds):



Voles 	

Aerial or Ground Broadcast

(CA only)	

6-10	

unlimited	

yes



Commensal rats	

Hand Baiting 

(late spring and summer only)	

not specified	

unlimited 	

yes



Areas inhabited by Cotton Rats and “Field Mice”:



Cotton rat

Voles

White-footed

   mouse	

Ground Broadcast

Hand Baiting 	

6-10

2-3 	

unlimited	

no



Rural Noncrop Sites Surrounding Residential and Resort Areas (HI only):



Roof rat

Polynesian rat

House mouse	

Aerial or Ground Broadcast	

5	

4	

no



Lawns, Golf Courses, Others (e.g., parks, turf and grass fields): 



Moles

Pocket gophers	

Burrow Builder (mechanical)

Hand Baiting	

1-3

not specified	

unlimited	

no



Voles

White-footed

   mouse	

Ground Broadcast

Trail Builder (mechanical)

Hand Baiting	

6-10 

2-3  

3-5	

unlimited	

yes



Ground squirrels	

Ground Broadcast

Hand Baiting

note: includes fruit and vegetable baits	

6 

not specified	

>30-day int.	

yes



Cotton rat

Voles

Ground squirrels	

Hand Baiting

(CA only)	

not specified	

unlimited	

yes



Grasses Grown for Seed (OR only):



Voles

Deer mouse

House mouse

Ground squirrels	

Ground Broadcast

Hand Baiting

note: limitations exist on timing and extent of area that can be treated
at any one time	

6-10 

2-3 	

4 

(per treated area)	

no



Cottonwood/Hybrid Poplar Plantations (OR only) and Adjacent Noncrop
Areas (WA only):



Voles	

Aerial or Ground Broadcast	

5-10	

unlimited	

no



Sugar Maple Orchards (VT only):



Red squirrel

Chipmunk

Deer mouse	

Bait Stations

(November 1 to May 31 only)	

1.5	

7	

yes



Diphacinone:

Most diphacinone baits are 50 ppm ai grain-based pellets or treated
grains, but California also has 100 ppm ai baits for some uses as
indicated in the table below.  As of May 2005, 46 Special Local Needs
(SLNs) registrations exist for 25 states and the Virgin Islands.  Seven
national registration (section 3's) products include the "wet areas"
labeling for field control of commensal rats and mice.

Diphacinone registered field/outdoor uses



State	

Use sites	

Target spp.	

Bait/Application methods



National registrations (§3's):



All	

Wet or damp areas, such as:

  Riverbanks

  Gullies

  Irrigation ditches

  Garbage dumps

  Landfills

	

Rats:

  Norway

  Roof

House mouse	

50 ppm grain-based "cakes" or blocks (including some peanut-flavored
products); for rats, apply 4-16 ounces at 15- to 30-ft intervals; for
mice, apply 1-oz. pieces at 8- to 12-ft intervals; for rats and mice,
maintain an uninterrupted supply of fresh bait for at least 10-15 days
or until signs of activity cease



All	

Wet or damp areas, including:

  Riverbanks

  Gullies

  Irrigation ditches

  Railroad tracks

  In and around rat holes

  Along fences

  Garbage dumps

  Landfills	

Rats:

  Norway

  Roof

House mouse	

50 ppm food bait; for rats, apply 2-8 bait packs per bait placement and
maintain uninterrupted supply of bait for at least 10 days; for mice,
open bait pack and apply 1/4-1/2 oz. bait at 8- to 12-ft intervals and
maintain uninterrupted supply of bait for at least 15 days



All except as noted

	

River banks

Irrigation ditches

Gullies

Railroad tracks

Fences

Sanitary landfills

	

Rats:

  Norway

  Roof

House mouse	

a ‘restricted-use’ 50 ppm food bait; for rats apply 4-16 oz. bait at
15- to 30-ft intervals and maintain an uninterrupted supply of bait for
at least 10 days or until signs of activity cease; for mice, apply 1/4
to ½ oz. of bait at 8- to 12-ft intervals and maintain an uninterrupted
supply of bait for at least 15 days or until signs of activity cease;
outdoor placements other than around buildings must be made in
tamper-resistant bait stations or deeply into rat burrows

	

Fruit tree orchards 

(bearing and nonbearing, including apples, pears, peaches, nectarines)
in the following states:  CT, GA, ID, MA, MI, MO, MT, NC, NH, OH, OR,
PA, SC, UT, VA, VT, WA, WV

Nut orchards (pecans, almonds, walnuts, filberts/hazelnuts) in the
following states:  ID, OH, MT, OR, WA

Christmas tree farms, Commercial nurseries, and Tree plantations in the
following states:  GA, MI, MO, NC, SC, WA	

Voles:

  Meadow

  Pine	

50 ppm ‘restricted use’ bait applied after fall harvest; broadcast
bait uniformly at 20 lb bait/acre for pine voles and 10 lb bait/acre for
meadow voles with commercially-made seed or fertilizer spreader or
(except in CT, GA, MA, MO, NC, NH, SC) by aerial application;
alternatively, handbaiting can be done at 10 lb bait/acre by placing
bait in active holes, trails, or runways at each tree site; for all
methods, a second application can be made after 1-2 months



All	

Rangeland

Forest areas

Grain fields 

Alfalfa crops

Vegetable crops

Golf courses

Parks

Nurseries

Around homes	

Pocket gophers:

  Valley 

  Northern 

  Mazama

  Townsend’s

  Giant 

  Sierra 

  Plains	

50 ppm grain bait applied manually into underground gopher burrows



All	

Levees

Ditch banks

Around farm buildings

Fence lines

Orchards

Crop areas

Noncrop areas	

California ground squirrel	

50 ppm oat bait applied in bait stations 20- to 100-feet apart; use 2-4
lb bait per station and maintain an uninterrupted supply of bait for at
least 30 days or until all signs of feeding have stopped



All	

Lawns

Turf

Golf courses

Other non-food grassy

  areas	

Moles:

  Eastern

  Star-nosed 

  Hairy-tailed

  Coast

  Broad-footed 

  Townsend	

50 ppm gel bait injected into active burrow systems through probe or
shovel hole; make 6 ½ oz. placements per burrow system



State registrations (Special Local Need, §24c’s):



AK	

Alaska Maritime National Wildlife Refuge islands	

Rats:

  Norway 

  Black 	

50 ppm fish-flavored grain bait applied in bait stations or placed in
burrow openings; use restricted to Certified Applicators or persons
under their direct supervision



AZ	

Levee and ditch banks

Fence lines 

Around farm buildings

Orchards

Other crop  areas

Other noncrop areas	

California ground squirrel	

50 ppm grain/nut bait applied in bait stations (2-4 lb bait per station)
spaced at 20- to 100-ft. intervals; maintain an uninterrupted supply of
bait for at least 15 days or until all signs of feeding cease; use
restricted to Certified Applicators or persons under their direct
supervision



CA

	

Levee and ditch banks

Fence lines 

Around farm buildings

Orchards

Other crop  areas

Other noncrop areas	

California ground squirrel	

50 ppm grain/nut bait applied in bait stations (2-4 lb bait per station)
spaced at 20- to 100-ft. intervals; maintain an uninterrupted supply of
bait for at least 15 days or until all signs of feeding cease; use
restricted to Certified Applicators or persons under their direct
supervision

	

Vineyards

Orchards

Groves

Rangelands

Noncrop borders

Fallow lands

Fence rows

Rights-of-way adjacent

  to canal banks, ditch

  banks, highways,

  levees, railroad lines,

  and utilities

Campgrounds

Recreational areas

Horticultural nurseries

Plantations of forest

  trees

Around livestock pens	

Ground squirrels:

  California

  Belding’s	

100 ppm bait:

ground (mechanical spreader) or aerial broadcast bait at 10 lb
bait/acre; make a second application after 4 days

50 ppm bait:

apply in bait stations (1-5 lb per station) spaced at 20- to 100-ft
intervals and replenish as needed; or, scatter bait near active burrows
and runways, making a second application after 4 days but applying no
more than 10 lb bait/acre per treatment

	

Campgrounds

Recreational areas

Noncrop borders

Fallow lands

Fence rows

Rights-of-way adjacent

  to canal banks, ditch

  banks, highways,

  levees, railroad lines,

  and utilities

Horticultural nurseries

Plantations of forest trees	

Golden-mantled ground squirrels

Chipmunks

	

50 ppm bait applied at 4-16 oz. per station in bait stations spaced at
20- to 50-ft intervals and replenished as needed



	

Vineyards

Orchards

Groves

Rangelands

Forage crops

Grain and edible seed crops

Oil crops

Fiber crops

Fruits

Vegetables

Noncrop areas

Fallow lands

Rights-of-way adjacent

 to canal banks, ditch

  banks, highways,

  levees, railroad lines,

  and utilities

Campgrounds

Recreational areas

Horticultural nurseries	

Pocket gophers

	

100 ppm bait applied directly into underground gopher tunnels

	

Crop areas

Noncrop areas



50 ppm food bait applied by hand or mechanical ‘burrow builder’ into
underground burrow sustems; use restricted to Certified Applicators or
persons under their direct supervision

	

Vineyards

Orchards

Groves

Rangelands

Fruit-tree plantations

Noncrop borders

Fallow lands

Rights-of-way adjacent

  to canal banks, ditch

  banks, highways,

  levees, railroad lines,

  and utilities

Campgrounds

Recreational areas

Horticultural nurseries

Plantations of forest

  trees

Reforestation areas	

Deer mice 

	

100 ppm bait:

ground (mechanical spreader) or aerial broadcast bait at 2-6 lb
bait/acre; make a second application after 4 days

50 ppm bait:

scatter bait near burrow openings or where activity detected; make a
second application after 4 days; do not apply more than 6 lb bait/acre
per treatment

	

Unspecified sites	

Ground squirrels:

  California

  Belding’s	

100 ppm bait scattered by hand near active burrows or runways; retreat
every other day for 3 to 4 applications

	

Vineyards

Orchards

Groves

Rangelands

Noncrop borders

Fallow lands

Fence rows

Rights-of-way adjacent

  to canal banks, ditch

  banks, highways,

  levees, railroad lines,

  and utilities

Campgrounds

Recreational areas

Horticultural nurseries

Plantations of forest

  trees	

Voles:

  California

  Montane

	

100 ppm bait:

ground (mechanical spreader) or aerial broadcast bait at 6-10 lb
bait/acre; make a second application after 4 days

50 ppm bait:

scatter bait near burrow openings or where activity detected; make a
second application after 4 days; do not apply more than 10 lb bait/acre
per treatment

	

In and around cabins

Citrus tree plantations

Conifer plantations	

Woodrats	

50 ppm bait applied  in bait stations 

	

None specified	

Woodrats

Roof rat	

50 ppm bait block placed in trees near damage areas

	

Natural and man-made waterways and wetlands adjacent to agricultural
crops, rangelands, noncrop borders, uncultivated agricultural areas, and
rishts-of-way	

Muskrat	

50 ppm bait applied in floating bait stations on anchored rafts;
replenish bait as needed

	

Ditches

Waterways	

Muskrat

	

50 ppm bait block placed near burrows, runways, or where activity seen

	

Infested ditch banks

Lumber and rubbish

  piles

	

Norway rat

Roof rat

House mouse	

50 ppm bait block placed in areas where they feed, drink, or frequent

	

Borders of agricultural

  crops

Rangelands

Fallow lands

Fence rows

Rights-of-way adjacent

  to canal banks, ditch

  banks, highways,

  levees, railroad lines,

  and utilities

Campgrounds

Recreational areas

Horticultural nurseries

Plantations of forest

  trees

Airports	

Jackrabbit

	

50 ppm bait applied  in covered self-dispensing feeders or enclosed
nursery flats near runways or resting or feeding areas; replenish bait
as needed



CT	

Fruit-tree orchards	

Voles:

  Meadow

  Pine 	

50 ppm pelleted bait ground-broadcast at 10 and 20 lb per infested acre
for meadow voles and pine voles, respectively; or, hand-baited at 10
lb/acre in active burrows or runways; may reapply once after 1-2 months
by either method



FL	

Ditch banks

Levees

Fence rows 

Tall grass

Other noncrop areas

  adjacent to fields	

Rats:

  Norway

  Roof

  Cotton

Florida water rat

Mice	

50 ppm fish-flavored pelleted bait applied in bait boxes  no more than
20 to 30 feet apart



HI	

Forests

Offshore islands

Other noncrop outdoor

  areas

Macadamia nut orchards	

Mongoose 

Rats:

  Norway

  Roof

  Polynesian

House mouse	

50 ppm fish- or molasses/peanut butter flavored bait blocks applied in
bait stations; 2 of 5 products are for use only by Certified Applicators
or persons under their direct supervision



ID

	

Field perimeters of

  small-grain crops

Orchards (tree fruits and

  nuts)	

Voles	

50 ppm pelleted bait applied in bait stations around grain crops; for
orchards, broadcast 10 lb per acre by air or ground or apply in tunnels;
a second application can be made after 20-40 days

	

Levees

ditch banks

Around farm buildings

Fence lines

Orchards

Other crop and noncrop

  areas	

Ground squirrels:

  California

  Columbian

  Townsend

  Washington	

50 ppm food bait applied in bait stations at 20- to 100-foot intervals



MA	

Orchards (tree fruits)	

Voles:

  Meadow

  Pine	

50 ppm pelleted bait applied at 10 lb bait/acre by ground broadcast for
meadow voles and by in-tunnel application for pine voles; for either
species, a second application can be made after 20-40 days



MI	

Orchards (tree fruits)

Christmas tree

  plantations	

Meadow vole	

50 ppm fish-flavored pelleted bait broadcast by air or ground or
hand-baited at 10 lb bait per acre; a second application can be made
after 1-2 months



MO	

Orchards

Christmas tree

  plantations

Commercial nurseries

Tree plantations	

Voles:

  Meadow

  Pine

  Prairie	

50 ppm fish-flavored bait ground broadcast at 20 lb bait/acre for pine
voles and 10 lb bait/acre for meadow and prairie voles or handbaited at
10 lb bait/acre; may reapply once after 1-2 months by either method



MT	

Levees

Ditch banks

Fencelines

Orchards

Other crop areas

Other noncrop areas

Around farm buildings	

Ground squirrels	

50 ppm fish-flavored bait; apply 2-4 lb bait per bait station with
stations placed at 20- to 100-foot intervals; bait stations may be
maintained on a permanent basis to prevent reinfestation



NC	

Orchards

Christmas tree farms

Commercial nurseries

Tree plantations	

Voles:

  Meadow

  Pine	

50 ppm pelleted bait ground broadcast at 20 lb bait/acre for pine voles
and 10 lb bait/acre for meadow voles or handbaited at 10 lb bait/acre;
may reapply once after 1-2 months by either method



NH	

Tree fruits	

Voles:

  Meadow

  Pine	

50 ppm pelleted bait applied at 10 lb bait/acre by ground broadcast for
meadow voles and by in-tunnel application for pine voles; for either
species, a second application can be made after 20-40 days



NV	

Levees

Ditch banks

Around farm buildings

Fence lines

Orchards

Other crop areas

Other noncrop areas	

California ground squirrel	

50 ppm fish-flavored bait or grain/nut bait applied in bait stations
(2-4 lb bait per station) spaced at 20- to 100-foot intervals; maintain
baiting for at least 15-30 days or until activity ceases



OH	

Orchards (tree fruits)	

Voles:

  Meadow

  Pine	

50 ppm fish-flavored bait ground broadcast at 20 lb bait/acre for pine
voles and 10 lb bait/acre for meadow voles or handbaited at 10 lb
bait/acre; may reapply once after 1-2 months by either method



OR	

Orchards (tree fruits and

  nuts)	

Voles	

50 ppm pelleted bait applied at 10 lb bait/acre by aerial or ground
broadcast for surface-foraging voles and by in-tunnel application for
subsurface root-feeding voles; for either method, a second application
can be made after 20-40 days

	

Levees

Ditch banks

Around farm buildings

Fence lines

Golf course

Nurseries

Orchards

Other crop and noncrop

  areas

Residential yards and

  gardens	

Ground squirrels:

  California

  Townsends	

50 ppm grain/nut bait applied in bait stations (2-4 lb bait per station)
spaced at 20- to 100-foot intervals; maintain an uninterrupted bait
supply for up to 15 days or until feeding activity ceases



PA	

Orchards (apples, pears,

  peaches, nectarines)	

Voles:

  Meadow

  Pine	

50 ppm bait applied by aerial or ground broadcast or handbaited at 10 lb
bait/acre; second application allowed after 1-2 months



SC	

Orchards

Christmas tree farms

Commercial nurseries

Tree plantations	

Voles:

  Meadow

  Pine	

50 ppm bait ground broadcast at 20 lb bait/acre for pine voles and 10 lb
bait/acre for meadow voles or handbaited at 10 lb bait/acre; may reapply
once after 1-2 months by either method



UT	

Orchards	

Voles	

50 ppm pelleted bait



VA	

Orchards (apples, pears,

  peaches, nectarines)	

Voles:

  Meadow

  Pine	

50 ppm bait applied by aerial or ground broadcast or handbaited at 10 lb
bait/acre; second application allowed after 1-2 months



VT	

Orchards (tree fruits)	

Voles:

  Meadow

  Pine	

50 ppm fish-flavored pelleted bait applied at 10 lb bait/acre by aerial
or ground broadcast for meadow voles and by in-tunnel, handbait, or
bait-station application for pine voles; for either method, a second
application can be made after 20-40 days



WA	

Small grains for seed

  production	

Meadow vole	

50 ppm bait for aerial or ground broadcast at 10 lb bait/acre; 3
applications allowed at 20- to 40-day intervals

	

Orchards (tree fruits and

  nuts)	

Meadow vole	

50 ppm bait for aerial or ground broadcast at up to 20 lb bait/acre per
application; 2 applications allowed at 20- to 40-day intervals

	

Levees

Ditch banks

Around farm buildings

Fence lines

Orchards

Other crop and noncrop

  areas	

Ground squirrels:

  California

  Columbian 

  Townsend

  Washington 	

50 ppm fish-flavored bait applied in bait stations at 20- to 100-foot
intervals



WV	

Orchards (tree fruits)	

Voles:

  Meadow

  Pine	

50 ppm fish-flavored pelleted bait applied at 10 lb bait/acre by aerial
or ground broadcast for meadow voles and by in-tunnel, handbait, or
bait-station application for pine voles; for all methods, a second
application can be made after 20-40 days



WY	

Levees

Ditch banks

Around farm buildings

Fence lines

Orchards

Other crop and noncrop

  areas	

Ground squirrels	

50 ppm fish-flavored bait applied in bait stations at 20- to 100-foot
intervals



Virgin

Islands	

Forests

Offshore islands

Noncrop outdoor areas	

Mongoose 

Rats:

  Norway

  Roof

  Polynesian

House mouse	

50 ppm molasses/peanut butter flavored bait blocks applied in bait
stations (4-16 ounces bait per station) at 75- to 150-foot intervals;
product is for use by or in cooperation with government conservation
agencies only



Chlorophacinone:

Most chlorophacinone baits are 50 ppm ai grain-based pellets or treated
grains, but California also has 100 ppm ai baits for some uses as
indicated in the table below.  As of May 2005, there are 21 SLNs in 18
states.

Chlorophacinone registered field/outdoor uses



State	

Use sites	

Target spp.	

Bait/Application methods



National registrations (§3's):



All	

Lawns

Golf courses

Other turf areas	

Moles:

  Eastern

  Star-nosed

  Scapanus spp.	

100 ppm food bait applied manually in moles’ deep tunnels or
subsurface runways; several treatments may be necessary



All	

Lawns

Golf courses

Rangeland

Alfalfa fields

Noncrop areas	

Pocket gophers

	

50 ppm food bait manually inserted into underground burrow systems in
2-3 locations per burrow system; maintain a constant supply of bait for
as long as gopher activity occurs



State registrations (Special Local Need, §24c’s):



CA	

Vineyards (dormant season)

Orchards and Groves (dormant season)

Rangelands

Noncrop borders

Fallow fields

Fence rows

Rights-of-way (adjacent to canal banks, ditch banks, highways, levees,
railroad lines, utilities)

Campgrounds

Recreational areas

Horticultural nurseries

Plantations of forest trees

In and around livestock buildings (e.g., cattle barns, poultry houses)

Livestock pens	

Ground squirrels:

  California

  Belding’s

	

100 ppm grain bait:

broadcast bait by ground (mechanical spreader) or air at rate of 10 lb
bait/acre; make a second application after 4 days 

50 ppm grain bait:

all sites:  apply 1-5 lb bait per bait station, with stations spaced at
20- to 100-ft intervals near active burrows and runways; replenish bait
as needed for up to 4 weeks

note:  according to OPP/RD, these directions allow 605 lb or more of
bait per acre per treatment 

orchards and groves:  as above or scatter 0.1-lb bait over 40-50 sq.
feet near active burrows and runways; make a second application after 4
days; do not exceed 10 lb bait/acre per treatment





Deer mice	

100 ppm grain bait:

broadcast bait by ground (mechanical spreader) or air at rate of 2-6 lb
bait/acre; make a second application after 4 days 

50 ppm grain bait:

scatter 1 tsp. bait (1/12 ounce) over a 30-sq-ft area near burrow
openings or where activity detected; make a second application after 4
days; do not exceed 6 lb bait.acre per treatment 





Voles:

  California

  Montane	

100 ppm grain bait:

broadcast bait by ground (mechanical spreader) or air at rate of 6-10 lb
bait/acre; make a second application after 4 days 

50 ppm grain bait:

scatter 1-2 tbsp. bait (1/4-1/2 ounce) near active burrow openings or in
runways; make a second application after 4 days; do not exceed 10 lb
bait.acre per treatment 

	

Campgrounds

Recreational areas

Noncrop borders

Fallow lands

Fence rows

Rights-of-way (adjacent to canal banks, ditch banks, highways, levees,
railroad lines, utilities)

Horticultural nurseries

Plantations of forest trees	

Golden-mantled ground squirrel

Chipmunks	

50 ppm grain bait applied in bait stations at 20- to 50-ft intervals
near active burrows and runways; replenish bait as needed for up to 4
weeks

	

Artichoke fields	

California vole	

100 ppm artichoke-bract baits scattered near burrow openings and
runways; 2 additional applications are allowed at 21-day intervals

	

Natural and man-made waterways and wetlands adjacent to agricultural
crops, rangelands, noncrop borders, uncultivated agricultural areas, and
rights-of-way	

Muskrat	

1-5 lb bait per covered or enclosed bait station secured to small raft
anchored or secured to bottom or bank; replenish bait as needed

	

Borders of agricultural crops

Rangelands

Fallow areas

Fence rows

Rights-of-way (adjacent to canal banks, ditch banks, highways, levees,
railroad lines, utilities)

Horticultural nurseries

Plantations of forest trees

Campgrounds

Recreational areas	

Black-tailed jackrabbit

	

apply bait in self-dispensing feeders or enclosed nursery flats near
runways or nesting or feeding areas; replenish bait as needed

	

Orchards

Groves

Vineyards

Forage crops

Grain and edible seed crops

Oil crops

Fiber crops

Fruits

Vegetables

Rangeland

Noncrop areas

Fallow lands

Campgrounds

Recreational areas

Horticultural nurseries

Rights-of-way adjacent to canal banks, ditch banks, highways, levees,
railroad lines, and utilities	

Pocket gophers

	

100 ppm grain bait applied directly into underground tunnels



ID

	

Forest plantations	

Meadow vole	

Apply bait in spots for 5-7 consecutive days but not to exceed 10 lb
bait/acre; a second application is allowed

	

Orchards	

Voles:

  Meadow

  Mountain	

Ground broadcast bait at 10 lb bait/acre or handbait in active burrows
or runways; a second application is allowed after 1-2 months



KS	

Rangeland

Noncrop areas	

Prairie dog

	

50 ppm bait applied at least six inches down prairie dog burrows;
applied between October 1 and March 15



MD	

Orchards	

Meadow vole	

Aerial or ground broadcast at 10 lb bait/acre; a second application is
allowed after 1-2 months





Pine vole	

Handbait at up to 10 lb bait/acre in active holes or runs; a second
application is allowed after 1-2 months



MI	

Orchards	

Voles:

  Meadow

  Pine 	

Ground broadcast bait (50 ppm) at 10 and 20 lb bait/acre for meadow and
pine voles, respectively, or handbait in active burrows and runways at
10 lb bait/acre; a second application is allowed after 1-2 months for
either method



MO	

Orchards	

Voles:

  Meadow

  Pine 	

Handbait at up to 10 lb bait/acre in active holes or runs; a second
application is allowed after 1-2 months



MT	

Noncrop areas

Rangeland

Pasture

Alfalfa 

Wheat

Oats

Barley	

Ground squirrels:

  Columbian 

  Richardson’s	

Scatter 50 ppm oat bait on bare ground by burrows; apply second
application after 4 days



NC	

Orchards

Commercial nurseries

Christmas tree farms

Tree plantations	

Voles:

  Meadow

  Pine 	

Ground broadcast bait (50 ppm) at 10 and 20 lb bait/acre for meadow and
pine voles, respectively, or handbait in active burrows and runways at
10 lb bait/acre; a second application is allowed after 1-2 months for
either method



NV	

Levees

Ditch banks

Fence lines

Around farm buildings

Orchards

Other crop and noncrop areas	

Ground squirrels	

Apply 2-4 lb of 50 ppm grain/nut bait in bait stations placed at 20- to
100-foot intervals



NY	

Orchards	

Voles:

  Meadow

  Pine 	

Handbait at up to 10 lb bait/acre in active holes or runs; a second
application is allowed after 1-2 months



OH	

Orchards

Ornamentals

Forestry nurseries	

Voles:

  Meadow

  Pine 	

Ground broadcast bait (50 ppm) at 10 and 20 lb bait/acre for meadow and
pine voles, respectively, or handbait in active burrows and runways at
10 lb bait/acre; a second application is allowed after 1-2 months for
either method



OR	

Orchards	

Voles:

  Meadow

  Pine 	

Ground broadcast bait (50 ppm) at 10 and 20 lb bait/acre for meadow and
pine voles, respectively, or handbait in active burrows and runways at
10 lb bait/acre; a second application is allowed after 1-2 months for
either method



PA	

Orchards	

Voles:

  Meadow

  Pine 	

Ground broadcast bait (50 ppm) at 10 and 20 lb bait/acre for meadow and
pine voles, respectively, or handbait in active burrows and runways at
10 lb bait/acre; a second application is allowed after 1-2 months for
either method



SC	

Orchards	

Voles:

  Meadow

  Pine 	

Handbait at up to 10 lb bait/acre in active holes or runs; a second
application is allowed after 1-2 months



VA

	

Orchards

	

Voles:

  Meadow

  Pine 	

Handbait at up to 10 lb bait/acre in active holes or runs; a second
application is allowed after 1-2 months





Meadow vole	

Ground broadcast at 10 lb bait/acre; a second application is allowed
after 1-2 months



VT	

Orchards	

Voles:

  Meadow

  Pine 	

Handbait at up to 10 lb bait/acre in active holes or runs; a second
application is allowed after 1-2 months



WA	

Orchards (apple, apricot, cherry, nectarine, peach, pear, prune, plum)	

Voles	

Aerial or ground broadcast at 10 lb bait/acre;  a second application is
allowed after 1-2 months



WV	

Orchards	

Meadow vole	

Aerial or ground broadcast at 10 lb bait/acre; a second application is
allowed after 1-2 months





Pine vole	

Handbait at up to 10 lb bait/acre in active holes or runs; a second
application is allowed after 1-2 months



Target Species for Registered Field/Outdoor Uses

Rodents:

   Commensal rats and mice:

Norway rat (Rattus norvegicus)

Roof rat (R. rattus)

Polynesian rat (R. exulans)

House mouse (Mus musculus)

   Ground squirrels: 

California ground squirrel (Spermophilis beecheyi)

Belding’s ground squirrel (S. beldingi)

Columbian ground squirrel (S. columbianus)

Franklin’s ground squirrel (S. franklini)

Golden-mantled ground squirrel (S. lateralis)

Rock squirrel (Spermophilus variegatus)

Townsend’s ground squirrel (S. townsendii)

Richardson’s ground squirrel (S. richardsoni)

Round-tailed ground squirrel (S. tereticaudus)

Thirteen-lined ground squirrel (S. tridecemlineatus)

Unita ground squirrel (S. armatus)

Idaho ground squirrel (S. brunneus)

Wyoming ground squirrel (S. elegans)

Washington ground squirrel (S. washingtoni)

Antelope ground squirrel (Ammospermophilus leucurus)

   Prairie dogs:

White-tailed prairie dog (Cynomys leucurus)

Black-tailed prairie dog (C. ludovicianus)

Gunnison’s prairie dog (C. gunnisoni)

   Marmots:

Yellow-bellied marmot (Marmota flaviventris)

Woodchuck (M. monax)

   Voles:

Meadow vole (Microtus pennsylvanicus)

Pine vole (M. pinetorum)

Prairie vole (M. ochrogaster)

Mountain vole (M. montanus)

California vole (M. californicus)

Townsend’s vole (M. townsendii)

Oregon vole (?)

   Woodrats:

Easter woodrat (Neotoma floridana) 

Southern plains woodrat (N. micropus)

Whitethroat woodrat (N. albiqula)

Desert woodrat (N. lepida)

Mexican woodrat (N. mexicana)

Dusky-footed woodrat (N. fuscipes)

Bushytail woodrat (N. cinerea)

   Kangaroo rats:

Ord’s kangaroo rat (Dipodomys ordii)

Merriam’s kangaroo rat (D. merriami)

Banner-tailed kangaroo rat (D. spectabilis)

   Pocket gophers:

Botta’s (Valley) pocket gopher (Thomomys bottae)

Camas pocket gopher (T. bulbivorus)

Wyoming pocket gopher (T. clusius)

Idaho pocket gopher (T. idahoensis)

Mountain (Sierra) pocket gopher (T. monticola)

Northern pocket gopher (T. talpoides)

Townsend’s pocket gopher (T. townsendii)

Mazama pocket gopher (T. mazama)

Giant pocket gopher (T. bulbivorus)

Southern pocket gopher (T. umbrinus)

Desert pocket gopher (Geomys arenarius)

Plains pocket gopher (G. bursarius)

Texas pocket gopher (G. personatus)

Southeastern pocket gopher (G. pinetis)

Yellow-faced pocket gopher (Pappogeomys castanops)

   Native mice and rats:

White-footed mouse (Peromyscus leucopus)

Deer mouse (P. manniculatus)

Oldfield mouse (P. polionotus)

Jumping mice (Zapus spp.)

Cotton rat (Sigmodon hispidus) 

Rice rat (Oryzomys palustris)

Florida water rat (Neofiber alleni)

   Others:

Muskrat (Ondatra zibethicus)

Nutria (Myocastor coypus)

Red squirrel (Tamiasciurus hudsonicus)

Eastern chipmunk (Tamias striatus)

Lagomorphs:

Black-tailed jackrabbit (Lepus californicus)

Insectivores:

Eastern mole (Scalopus aquaticus)

Broad-footed mole (Scapanus latimanus)

Coast mole (S. orarius)

Townsend’s mole (S. townsendii)

Star-nosed mole (Condylura cristata)

Hairy-tailed mole (Parascalops breweri)

Carnivores:

Mongoose (Herpestes auropunctatus)

ATTACHMENT 3

        UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, D.C.  20460

	OFFICE OF                

	PREVENTION, PESTICIDES AND

	TOXIC SUBSTANCES      

	September 7, 2004

Memorandum

Subject:	EFED Response to USDA/APHIS’ “Partner Review Comments: 
Preliminary Analysis of  of Rodenticide Bait Use and Potential Risks of
Nine Rodenticides to Birds and Nontarget Mammals:  A Comparative
Approach (June 9, 2004)”

To:		Laura Parsons, Team Leader

Kelly White

Reregistration Branch 1

Special Review and Reregistration Division

From:		William Erickson, Biologist

Environmental Risk Branch 2

Environmental Fate and Effects Division

Through:	Tom Bailey, Branch Chief

Environmental Risk Branch 2

Environmental Fate and Effects Division

Attached are EFED’s comments on APHIS’ review of the comparative
rodenticide risk assessment dated June 9, 2004.  We have inserted
EFED’s response after each APHIS comment that  pertains to the
comparative risk assessment (comment 6 relates to BEAD’s benefits
assessment).  Some of these issues were addressed in EFED’s response
to registrants’ comments during the 30-day “errors-only” comment
period in 2001 and comments submitted during the 120-day
“public-comments” period from January to May of 2003.  The present
submission also includes a copy of APHIS’ comments from March 31,
2003, and they request that comments 2, 4, 5, 6, 7, 8, and 9 be
addressed.  EFED addressed those comments in our July 17, 2004
“Response to Public Comments on EFED's Risk Assessment:  "Potential
Risks of Nine Rodenticides to Birds and Nontarget Mammals:  a
Comparative Approach", dated December 19, 2002", and we reiterate our
response to those comments as well.  We have also attached a table of
many zinc phosphide use sites, methods of application, application rates
and number of applications permitted, although many product labels do
not provide that information.  A list of the names of more than 70
target species also is included.  [included in Attachment 2]

APHIS’ comments and EFED’s response to those comments are provided
below.  The full text of APHIS’ comments are in the EDocket.

APHIS comments dated August 4, 2004: 

1)	APHIS would like to reiterate a serious concern regarding the both
the previous and the current drafts of the document we reviewed.  This
document is not, as stated, “an assessment of potential risk”.  This
draft successfully addresses the hazard aspect of risk.  However, the
exposure component of risk is not adequately considered.  No attempt has
been made to address the exposure scenarios that necessarily include
application methods, timing, rates, etc.  This, therefore, is not a risk
assessment.  Presumably EPA’s overall goal is to mitigate potential
risk to non-target birds and mammals.  Hazard or toxicity of a chemical
is constant.  It is only by addressing exposure that risk can be
mitigated.  Thus exposure cannot be ignored.

EFED Response to Comment 1:  EFED is surprised that APHIS continues to
insist that there is no exposure of zinc phosphide baits to birds and
nontarget mammals.  Baits can be formulated with whole grains (wheat,
barley, oats, corn, milo, millets), grain-based pellets, fruits (grapes,
mulberry, apples, pears, apricots, figs), nuts, sunflower seeds,
vegetables (carrots, sweet potato, potato, cabbage), fresh vegetation
(alfalfa, dandelions, beet tops), and meat-based products (ground meat,
canned or dry meat-based cat or dog foods).  Many of these foods are
likely to be highly attractive to granivorous, frugivorous, omnivorous,
and even carnivorous birds and mammals.  Zinc phosphide is registered
for controlling more than 70 mammalian species, mostly a variety of
rodents, but also lagomorphs (jackrabbits) and insectivores (moles). 
Zinc phosphide baits are applied (often by multiple aerial,
ground-machine (e.g., cyclone spreader), or hand broadcasts) to a wide
variety of treatment sites, ranging from in and around buildings to
rangeland and pastures, rights-of-way, orchards and groves, vineyards,
uncultivated areas, croplands, waterways, lawns and golf courses, 
nurseries, ornamentals, forestry, and numerous other sites.  A list of
treatment sites, application methods, bait formulations, and target
species is attached.  It should be noted that for many uses, both for
commensal and field uses, product labels do not specify either an
application rate (lb/acre) nor put any limitations on the number of
applications that can be made, other than a few uses with seasonal
restrictions.  Repeat applications are likely to increase the likelihood
of exposure of nontarget organisms.

The issue of quantifying exposure is addressed in the revised
comparative risk assessment and in EFED’s Reponse to Public Comments
dated July 17, 2004 and is worth repeating here:

EFED’s risk assessment is in accord with the Agency's Guidelines for
Ecological Risk Assessment [Guidelines for Ecological Risk Assessment. 
EPA/630/R-95/002F, April 1998, Final.  171 pp. 
http://www.epa.gov/ncea/ecorsk.htm].  Registrants are correct in noting
that the Guidelines state that "Ecological risk assessment is a process
that evaluates the likelihood that adverse ecological effects may occur
or are occurring as a result of exposure to one or more stressors"( PART
A, page 1, paragraph 1).  However, the Guidelines go on to state that
"Descriptions of the likelihood of adverse effects may range from
qualitative judgments to quantitative probabilities.  Although risk
assessments may include quantitative risk estimates, quantitation of
risks is not always possible.  It is better to convey conclusions (and
associated uncertainties) qualitatively than to ignore them because they
are not easily understood or estimated" (PART A, page 1, paragraph 3). 
Refining the exposure assessment to establish a quantitative measure of
likelihood of exposure and effects would require a much more extensive
data set than registrants have submitted for their rodenticides and for
the nontarget species potentially at risk.  The Agency provided the
preliminary risk assessment to rodenticide registrants in October, 2001
and posted it in the EDocket on EPA’s website for public comments from
January 29 to May 30, 2003.  No additional data or relevant information
to refine the exposure assessment has been provided by the registrants
or other stakeholders.  The necessary data have been outlined in a
section on "Uncertainty and Data Needs" in the refined assessment. 
Nevertheless, despite the lack of quantifiable data, the existence of
substantial incident data along with liver-residue analysis confirms
that birds and nontarget mammals are being exposed and adversely
affected by applications of rodenticide baits.  The fact that numerous
species of birds and mammals, including predators and scavengers, have
been found exposed to these baits indicates that both primary and
secondary exposures are occurring.

EFED’s risk conclusions are based on analyses of the available data by
a "lines-of-evidence" approach and comparative-analysis modeling. 
Quantitative estimates of risk are used in both; however, the
“lines-of evidence” assessment includes qualitative assessments of
secondary risk based on mortality and other adverse effects reported in
laboratory and field studies, operational control programs, and incident
reports, as well as toxicokinetic data and residue levels reported in
primary consumers.  This approach is in concert with the Guidelines,
which clearly state that professional judgement or other qualitative
evaluation techniques are appropriate for ranking risks using categories
such as low, medium, and high when exposure and effects data are limited
or are not easily expressed in quantitative terms.  A
"lines-of-evidence" approach also has been advocated by the Avian
Effects Dialogue Group for helping to interpret the variety of
information collected during field studies [see Rymph, B. (ed.).  1994. 
Assessing Pesticide Impacts on Birds:  Final Report of the Avian Effects
Dialogue Group, 1988-1993.  RESOLVE Center for Environmental Dispute
Resolution, Washington, DC.  156 pp].  Regarding the lines-of-evidence
analysis, one of the expert external peer reviewers stated that “The
bulk of the material in the document addresses the development of the
weight of evidence argument.  In general this part of the document is
well-developed and it is hard to argue with the evident conclusion about
each of the nine chemicals.  These conclusions are largely implicit in
the text since the task of deriving a formal assessment for each
chemical is passed over to the decision support analysis.  The case
about each chemical is thoroughly and logically developed in this part
of the document and the document is commendable in showing how the
Agency staff have been able to develop the weight of evidence approach
as a viable approach to the synthesis of a complex body of evidence.” 
The three expert peer reviews are available in the Rodenticide Cluster
EDocket, www.epa.gov/oppsrrd1/rodenticidecluster/index.htm]

EFED also notes that the methodology used is similar to that used in the
Agency’s "Comparative Analysis of Acute Risk From Granular Pesticides"
(EPA 1992) and “A Comparative Analysis of Ecological Risks from
Pesticides and Their Use: Background, Methodology, Case Study” (EPA
1998); both were reviewed by a FIFRA Scientific Review Panel. 
Concerning the latter analysis, the Panel noted the many scientific
uncertainties in the method, yet agreed that it was a useful screening
tool that provides a rough estimate of relative risk.  The Panel made a
number of helpful suggestions to improve the utility of the method, most
of which are included in the risk assessment.  





2)	EPA’s Section 7 consultation with the U.S. Fish and Wildlife
Service (FWS) is a beneficial addition.  The FWS has not only identified
those threatened and endangered species that may be impacted, but also
included recommendations for mitigation of potential adverse effects. 
The mitigation measures are in the form of buffer zones that prevent or
reduce possible exposure.

EFED Response to Comment 2:   OPP’s Endangered Species Protection
Program will be addressing endangered species issues and, if necessary,
reinitiating consultation with the U. S. Fish and Wildlife Service for
the nine rodenticides addressed in their 1993 Biological Opinion [USFWS
Biological Opinion:  Effects of 16 Vertebrate Control Agents On
Threatened and Endangered Species.  March, 1993.  168 pp.] 



3)	The inclusion of all available incident data is appropriate for a
discussion of risk.  However, EPA has not adequately discussed the new
data provided by the American Society for the Prevention of Cruelty to
Animals (ASPCA) Poison Control Center.  The text assumes the poisonings
are a result of rodenticide application.  Does the ASPCA track the
mechanism of exposure in their database?  The incidents may be due to
exposure during normal labeled use, poisoning from accidental ingestion
of stored rodenticides, or from the too common problem of intentional
and illegal poisoning of dogs and other canines.  We suggest EPA review
their agency enforcement data to evaluate the severity of illegal canine
poisoning using pesticides.  EPA appears again to be ignoring the
exposure aspect of risk.  If the exposure data are not available, which
is often the case in other poison control center databases, EPA needs to
acknowledge the lack of data.

EFED Response to Comment 3:  EFED does not conduct risk assessments for
pets and domestic animals.  Those issues are addressed by OPP’s Health
Effects Division, and they likely would be willing accept any relevant
data that APHIS could provide.  ASPCA did provide EFED with the number
of incidents reported in their database during an 18-month period. 
Mostly these were incidents with dogs.  Because there is a substantial
cost in obtaining the individual incident reports, EFED could not obtain
them, nor has any registrant provided them to EFED.  However, the fact
that there were more than 2300 incidents reported for rodenticides
indicates that dogs and other pets are being exposed to rodenticide
baits.  Whether this exposure is due to intentional or inadvertent
misuse or improper storage is unclear, but a combination of these means
of exposure seems likely.  Possibly label warnings and application
directions are not adequate to prevent exposure.  That is an issue that
can be addressed during the mitigation phase.

We do note that at least one of APHIS’ zinc phosphide products (EPA
Registration No. 56228-6 - Zinc Phosphide Concentrate “For the control
of voles, house mice, white-footed mice, norway rats, roof rats,
polynesian rats, rice rats, Florida water rats, cotton rats, pocket
gophers, muskrats, nutria, prairie dogs, wood rats, ground squirrels,
marmots and woodchucks, and black-tailed jackrabbits . . .”) states
that “Dogs, cats and other nontarget animals may actively search for
bait, especially when meat-based baits are used.”  Thus, it would seem
inappropriate to imply that all exposure of dogs is due to intentional
misuse or improper storage of baits.  We also note other warnings on the
labels of zinc phosphide baits.  For example, EPA Reg. No. 56228-6 is a
Restricted Use Pesticide “Due to hazards to nontarget species”,
which implies that nontarget animals might be exposed to baits.  This
and other labels also state that “This product is toxic to wildlife
and fish.  Birds and other wildlife feeding in treated areas may be
killed.”  Labels also have a section entitled “Endangered Species
Considerations” that requires applicators to determine if endangered
species are present in the treatment area.  We assume that this warning
relates to bait application in the field, not solely to misuse or
storage situations.  That APHIS includes such warnings and precautions
on their product labels indicates that they are indeed aware that there
is a potential risk to nontarget organisms.





 4)	The current comparative risk model can provide some useful
information.  However, there are several characteristics of zinc
phosphide which demonstrate that assumptions in the model need to be
adjusted:

     a)	The model may not be as useful for comparison of pesticides
having different mechanisms of action, particularly if that mechanism
influences the quantity of active ingredient consumed, which translates
to different levels of exposure.  Zinc phosphide, once ingested,
produces phosphine gas (the toxic agent) in the stomach.  This mechanism
is rapid (hours) compared to anti-coagulants (days).  Generally rodents
will continue to consume anti-coagulants for several days, whereas
rodents will quickly stop consuming bait treated with zinc phosphide in
part due to rapid onset of toxicosis.  In addition, zinc phosphide has a
disagreeable taste leading to bait shyness.  In either case, the
relatively high concentration of a rodenticide in bait is not equivalent
to exposure, because animals do not consume equal amounts of bait. 
These differences in exposure are not incorporated into the model.

EFED Response to Comment 4a:  EFED agrees that the amount of bait eaten
over a several-day period does have consequences for risk.  For example,
second-generation anticoagulants can provide a lethal dose to a primary
consumer in a single feeding, but death is delayed and the animal may
continue feeding and accumulating residue for several or more days.  In
contrast, zinc phosphide kills quickly.  Because residues do not
accumulate to any significant extent in consumers of zinc phosphide
bait, EFED made a presumption of minimal secondary risks to avian and
mammalian predators and scavengers.  That presumption is supported by
studies in which poisoned rodents have been fed to avian and mammalian
predators and/or scavengers and observed for adverse effects.  However,
for primary consumers, the issue is not the total quantity of bait that
might be eaten but rather if the amount of bait that might be eaten will
provide a lethal dose or have other adverse effects (e.g.,
reproductive).  Zinc phosphide grain baits are formulated mostly at 2%
ai (1% for fruits, nuts, vegetables and 3% for meats), versus the 0.005%
ai baits for the second-generation anticoagulants.  Because they are
formulated at such higher concentrations of active ingredient, very
little bait needs to be eaten to provide an LD50 dose.  As tabulated in
the comparative risk assessment (see Table 28 in the revised
assessment), a 25-g bird needs to eat only about 0.02 g of a 2% ai zinc
phosphide bait  to ingest an LD50 dose, and that accounts for only about
0.3% of the amount of food it will eat in a day.  Because a bird is
likely to eat a pellet or treated grain whole, rather than chewing it,
it will ingest multiple LD50 doses.  A small mammal might chew only a
piece of a pellet or grain, but a 25-g nontarget mammal needs to eat
only about 0.03 g of bait to ingest an LD50 dose (see Table 31).  Even
if bait shyness is a factor, an animal is likely to consume multiple
LD50 doses before avoiding any additional bait.  As already noted, zinc
phosphide baits are targeted for control of more than 70 mammalian
species, and APHIS has provided no data demonstrating that baits are
selective to these target species and won’t be eaten by nontarget
species. [see also EDED Response to Comment 4c]





b)	Another indication that the model may need an adjustment is that the
model results are inconsistent with EPA’s own incident data for zinc
phosphide.  The EIIS data suggest that birds may be at far greater risk
than mammals, as indicated by the relative number of animals in each
class reported in the database.  But the model predicts the exact
opposite.  There are many times more incidents and numbers of birds than
mammals in the data.  As with the ASPCA data (as it is reported in the
risk document), the EIIS data may not reflect exposure.  In addition,
reporting may be incomplete and not indicative of actual incidents.  For
example, small mammals may be in burrows and not visible.  However, the
observation that the model and the incident data do not support each
other should raise questions.

EFED Response to Comment 4b:  There are no inconsistencies between the
incident database and EFED’s risk conclusions, but we agree with APHIS
that the incidents do indicate that birds that eat zinc phosphide baits
are at risk.  The incident database is not comprehensive and contains
only incidents that have been reported to the Agency (see section
entitled “Incident Data:  Birds and Nontarget Mammals” in the
comparative risk assessment).  The fact that there are more bird
incidents than mammal incidents is not surprising.  Larger birds such as
geese, ducks, and wild turkeys are much more likely to be found,
analyzed, and reported to local, state, or federal authorities than are
small mammals.  As APHIS notes, small mammals may die in burrows (or
other hiding places such as crevices and dense vegetation) where they
would be inconspicuous and easily overlooked.  The fact that they are
not represented in the incident database is not surprising, but it does
not mean they are not at risk.  We remind APHIS that zinc phosphide is a
rodenticide and is registered for lethal control of more than 70
mammalian species.  





c)	There is also inconsistency between the model results for zinc
phosphide and EPA’s own concern regarding the efficacy of the USDA
registered products.  EPA has conducted label reviews of 2% zinc
phosphide bait products.  In the most recent review (April 5, 2004) EPA
expressed concern about mediocre performance.  Bait shyness by rodents
is an issue with zinc phosphide.  Again, this relates to exposure.  If
the exposure is relatively low, the corresponding risk is low.  And
again, the model predicts high risk to mammals.

EFED Response to Comment 4c:  We are surprised that APHIS seems to be
arguing that their products are not efficacious.  Agency
efficacy-testing guidelines require that 70% control must be achieved in
field tests and 90% mortality obtained in laboratory tests.  Many zinc
phosphide products have met those standards and are currently
registered.  However, it is inappropriate to compare efficacy against
target species to risks to nontarget species.  Efficacy would be
mediocre if only 60% or 65% of the target species were killed in a field
trial.  Yet, 60 or 65% mortality of one or more nontarget species could
be devastating to that species. 





 5)	USDA/APHIS provided a number of comments on the December 19, 2002
draft in a letter to EPA dated March 31, 2003.   The majority of these
comments have not yet been addressed.  A copy of the March 31, 2003
letter is attached for your reference.  Please direct your attention to
comments numbered 2, 4, 5, 6, 7, 8 and 9.

EFED Response to Comment 5:  EFED has responded to those comments that
relate to EFED issues.  OPP management determined that the Responses to
Public Comments would be issued when the revised comparative risk
assessment and BEAD’s benefits assessment are issued.  APHIS’
comments have been addressed in that response.  However, we will respond
to APHIS’ comments 2, 4, 5, 6, 7, 8, and 9 as requested (see below).





Synopsis of APHIS comments from March 31, 2003:

Comment 2:  APHIS agrees that technical materials can be toxic to birds
and mammals but argues that end-use products offer some degree of
selectivity due their unique formulations and application directions. 
“End-use products are formulated with many different carriers,
strengths and can be applied under a wide range of use patterns and
methods (Broadcast, underground, bait stations, indoors, outdoors,
etc.).  These factors afford some level of selectivity for primary risk.
 These factors should be considered and assessed prior to imposing
mitigation measures.”  APHIS goes on to state that “The development
of zinc phosphide into effective products included the use of many
different grains, stickers, flavors, stabilizers, dyes, etc.  Today,
manufacturers have settled on a few formulations.  These formulations
have been selected because of the high degree of acceptance by target
species, but also because they present less hazard to nontarget species
than other formulations.”  APHIS adds that a submission by Eisemann et
al. (1999) entitled “A literature review (1942-1998):  Efficacy of
zinc phosphide for controlling Norway rats, roof rats, house mice,
Peromyscus sp., prairie dog, and ground squirrels”  (MRID No.
449066-01) has been submitted to the Agency, and it included a hard copy
of 103 manuscripts that reinforces the point that site-specific risk
assessments should be performed prior to imposing any mitigation
measures.

 EFED Response to Comment 2:  APHIS has provided no information that
anything in product formulations deters nontarget species or is highly
specific to the target species.  The label for Zinc Phosphide
Concentrate (EPA Registration No. 56228-6) provides mixing instructions
for a variety of baits.  Meat-based baits are made solely with a meat
base (ground meat, canned dog or cat food, or dry meat-based pet food)
mixed with zinc phosphide concentrate.  Sunflower-seed baits are made by
mixing sunflower seeds, zinc phosphide concentrate, and mineral oil. 
Fruit and vegetable baits are made by mixing a fruit (grapes, mulberry,
apricots, figs, apples, pears), nut (unspecified), vegetable (carrots,
sweet potato, potato, cabbage), or vegetation (alfalfa, dandelions, beet
tops) with zinc phosphide concentrate and vegetable oil.  Granted, not
all nontarget species will eat meat or vegetables, but they are likely
to be attractive to many species.  Adding vegetable oil might actually
enhance their attractiveness to some nontarget species.  

Regarding application methods, EFED recognizes that there are many
application methods (see EFED attachment).  Some methods, such as
underground baiting for pocket gophers and moles, likely does minimize
exposure of surface-feeding birds and mammals.  However, the suggestion
that broadcasting bait by aircraft, ground-driven machines, or by hand
is selective to the target species is not supported by any data and
seems highly improbable; in fact, broadcasting seems a highly
unselective method of applying bait.  Many of the aerial broadcast
application rates are higher than those for ground broadcast (machine or
by hand) or when hand baited.  That higher rate would seem to suggest
that aerial broadcast may, in fact, be less selective.  

APHIS is inconsistent in comments about the efficacy of zinc phosphide
baits.  In the comment above APHIS states that “These formulations
have been selected because of the high degree of acceptance by target
species”, yet in their comments of June 9, 2004 state that “EPA has
conducted label reviews of 2% zinc phosphide bait products.  In the most
recent review (April 5, 2004) EPA expressed concern about mediocre
performance.”  How does a high degree of acceptance by target species
lead to mediocre performance?

APHIS’ submission submitted under MRID No. 449066-01 is an efficacy
submission.  Efficacy studies are reviewed by OPP’s Registration
Division.  Such studies conducted with the target species, under Agency
efficacy testing guidelines, and they are not adverse-effects studies. 
That efficacy submission referred to contains 103 documents encompassing
more than 1600 pages.  If APHIS believes that there is any relevant
information for assessing nontarget risks, the appropriate documents
should be cited and brought to EFED’s attention. 





Comment 4:  APHIS believes that pen studies conducted by Ramey  et al.
(1994) and Ramey et al. (1998) are not discussed in enough detail in the
comparative risk assessment.

EFED Response to Comment 4:  The Ramey et al. (1994) study conducted in
alfalfa enclosures does demonstrate that pheasants may eat zinc
phosphide bait and that they may be killed if they do so.  Quail also
were present but did not eat bait.  The fact that the quail presumably
found alternative food suggests that pheasants could have done so as
well and were not forced to eat the bait.  The study does clearly
indicate that birds can be killed if they eat zinc phosphide bait.  That
doesn’t mean that every bird in every zinc phosphide treatment site
will eat bait and die, but it does suggest that under some situations
some birds may eat bait and be at risk.  Whether nontarget animals eat
bait in any particular situation likely depends on many factors,
including food preferences and the availability of alternative foods. 
Bait may be more readily eaten if natural foods are scarce and that can
vary annually, geographically, seasonally, and even weekly and daily. 
Can one argue that because the quail didn’t eat bait in the alfalfa
enclosure that they will never do so under any circumstance?  On the
other hand, because pheasants ate bait and died in the enclosures does
not mean that every pheasant on every zinc phosphide treatment area will
eat bait and die.  However, it does suggest that some birds will eat
bait and are at risk if they do so.

The Ramey et al. (1998) study was conducted with pheasants in alfalfa
fields in the Sacramento Valley of California.  Zinc phosphide was
applied between alfalfa cuttings, at which time pheasants were not
utilizing the fields.  Therefore, pheasants were not exposed.  Based on
that study, EPA registered this use of zinc phosphide.  But does this
mean there is no risk to zinc phosphide?  The study did not address
geographical differences in pheasant behavior and diets, nor did it
address any possible annual differences at the study sites.  Pheasants
in the highland alfalfa-growing areas in California might behave
differently, and so might those in Minnesota alfalfa fields.  The study
also did not address risks to other species that might have been
exposed.  The researchers did conduct transects across treated fields. 
However, searches were done using ATVs, and small birds and nontarget
mammal carcasses, especially those inside burrows or dying off the
fields, might have been overlooked.  Therefore, while this was a well
conducted study on the risks of pheasants in treated alfalfa fields in
central California, there are many uncertainties in extrapolating these
results to other areas and possibly even other years.

 



Comment 5:  APHIS questions why EFED hasn’t used zinc phosphide use
information they provided to an EFED reviewer at a meeting in 1996. 

EFED Response to Comment 5:  EFED welcomes any relevant use data for
zinc phosphide and the other rodenticides.  The Agency provided the
preliminary risk assessment to rodenticide registrants in October, 2001
and posted it in the EDocket on EPA’s website for public comments from
January 29 to May 30, 2003.  No additional data or relevant information
to refine the exposure assessment has been provided by the registrants
or other stakeholders.   We are not aware of the information APHIS said
was provided in a handout at a meeting in 1996 - it is not in EFED’s
file for zinc phosphide nor does the zinc phosphide chemical reviewer
have any recollection of receiving that information.  However, we have
tabulated current zinc phosphide uses, target species, and application
methods (see attachment and responses to previous comments).  This
information is current, whereas information from the early 1990's may be
outdated for some uses.  Regarding production data, EPA does 

obtain data on the amount of each product produced annually.  However,
many zinc phosphide products have many use sites and target species on
individual product labels (e.g., APHIS product 56228-6).  Production
data provide no information on when, where, or how the product was used
and thus provide little relevant information for assessing exposure and
risk. 

Some of those same problems apply to the Pesticide Use Reporting by the
California Department of Pesticide Regulation
(http://www.cdpr.ca.gov/docs/pur/purmain.htm).  The annual reporting
only provides the amount of rodenticide applied per crop without
providing any information of the target pest, seasonal use, application
method (e.g., broadcast versus bait station), or other such relevant
factors.  Moreover, homeowners and non-certified applicators do not
report pesticide use, and noncrop uses are poorly represented or lumped
together. 





Comment 6:  Very few incidents have been reported during the past 60
years of zinc phosphide use.  The Agency should compare the number of
incidents with the use information discussed under Comment 5.

EFED Response to Comment 6:  The fact that few incidents have been
reported could be due to a variety of reasons.  One is that few
incidents occur.  However, it could also be that incidents occur but are
not detected or reported.  That most reported incidents for rodenticides
involve anticoagulants is not surprising, because anticoagulants are
stored in body tissues and can be detected by analyzing liver tissue. 
Confirmation of zinc phosphide poisoning is much more difficult, because
the phosphine gas is liberated and not stored in the body.  It is
generally detected by the presence of dyed bait in the crop, stomach, or
alimentary canal.  The presence of an acetylene odor also is diagnostic
of zinc phosphide toxicity but can be detected only if intact carcasses
are sent to an examining laboratory soon after death (Michigan Wildlife
Diseases Manual:  Zinc Phosphide 
www.dnr.state.mi.us/wildlife/division/RoseLake).  Neither the incident
information nor the use information is adequate to make a comparison of
the number of incidents per application or any other such criteria. 
EFED has addressed this issue in the “Target species, use sites, and
rodenticide usage” section of the revised comparative risk assessment
and in EFED’s July 17, 2004 “Response to Public Comments on EFED's
Risk Assessment:  "Potential Risks of Nine Rodenticides to Birds and
Nontarget Mammals:  a Comparative Approach", dated December 19, 2002".





Comment 7:  The value of carcass searches during efficacy field studies
has been undervalued.  Data collected during systematic onsite searches
is stronger than that collected by accidental discovery.

EFED Response to Comment 7:  As noted in EFED’s Response to Comment 2,
efficacy studies are designed to address effectiveness of the bait and
application method in controlling the target species.  Efficacy tests
are not designed to assess risks to nontarget species, and they rarely
do so other than occassionally searching for carcasses along transects
on treatment plots.  However, in terms of the impact of a bait on
nontarget organisms, simply walking transects across treated areas can
be misleading.  As APHIS astutely pointed out in Comment 4b, “For
example, small mammals may be in burrows and not visible.”, and small
birds may fly offsite before dying.  A good effects study needs to
assess nontarget population levels before and after control by means
such as mark-recapture or radio telemetry.  APHIS argues in Comment 1
that exposure has not adequately been assessed, but how does walking
transects adequately address exposure?  It doesn’t and can be
misleading.  For example, the search efficiency of the individuals doing
the transect searches must be determined but ususally isn’t, nor are
those individuals inside burrows accounted for.  EFED has provided
guidance for conducting field trials to assess nontarget exposure (Fite
et al. 1988:  Guidance Document for Conducting Terrestrial Field
Studies, EPA 540/09-88-109), including design considerations, addressing
search efficiency, and methods appropriate for assessing nontarget
impacts.  We also encourage APHIS to discuss study protocols with EFED
prior to initiating a field study.





Comment 8:  Prior to requiring avian production data, APHIS suggests
that EFED examine chronic data collected by other OPP divisions.  APHIS
also cites four chronic or subchronic rat studies that were submitted to
the Agency.

EFED Response to Comment 8: EFED will look at those studies to determine
if there are any relevant information for mammals.  EFED typically
utilizes the rat two-generation reproduction test (40 CFR §158.340,
Toxicology Data Requirements, Guidelines Reference No. 83-4
"Reproduction, 2-generation") to assess chronic risks to mammals.  This
study is required by OPP’s Health Effects Division (HED) to support
pesticides with food uses or where use of the product is likely to
result in human exposure over a significant portion of the human
lifespan.  This study is not currently available for zinc phosphide or
for any of the other rodenticides.  Most other subchronic/chronic
studies (e.g., neurotoxicity, dermal, inhalation, oncogenicity) required
by HED are not relevant to assessing risk to nontarget mammals from food
baits.  For birds, EFED uses avian reproduction studies with the
northern bobwhite and mallard (40 CFR §158.490, Wildlife and Aquatic
Organisms Data Requirements, Guidelines Reference No. 71-4 "Avian
reproduction" ).  The avian reproduction studies have previously been
required by the Agency on a case-by-case basis, but the updated
guideline requirements soon to be published will require these studies
for all pesticides having outdoor uses.  EFED can better assess the
potential for adverse reproductive effects when these data become
available.





Comment 9:  APHIS states that rodents are hesitant to accept zinc
phosphide treated grains.  Baiting efficacy is greatly improved when
treated sites are first prebaited with untreated grain.  Aversive
properties can be assumed to extend to other mammals and should be
considered.

EFED Response to Comment 9:  The argument that bait aversion can be
reduced by prebaiting, at least for some species, may be correct and is
not disputed by EFED.  However, we note that nontarget mammals also
would be prebaited and thus more likely to accept bait as well.  Product
labels recommend prebaiting for some species but not others (see
attachment), suggesting that zinc phosphide treated grains may not be
aversive to some species.  What about birds?  What about baits other
than grains (meat-based baits, nuts, sunflower seeds, fruits,
vegetables, vegetation)?  The fact that there are at least 70 mammalian
species listed as target species for zinc phosphide baits indicates that
many mammals will eat bait.  Moreover, as previously discussed, very
little bait needs to be eaten to provide an LD50 dose to a small mammal
or small bird.





 Stone, W.B., J.C. Okonlewski, and J.R. Stedelin.  2003.  Anticoagulant
rodenticides and raptors:  recent findings from New York, 1998-2001. 
Bull. Environ. Contam. Toxicol. 70:34-40

 Kaukeinen, D.E., C.W. Spraggins, and J.F. Hobson.  2000.  Risk-benefit
considerations in evaluating commensal anticoagulant rodenticide impacts
to wildlife.  Proc. Vertebr. Pest Conf. 19:245-256.  Rodenticide
Registrants Task Force presentation.

 Godfrey, M.E.R.  1986.  An evaluation of the acute-oral toxicity of
brodifacoum to birds.  Proc. Vertebr. Pest Conf. 12:78-81

 USEPA.  2004.  Overview of the Ecological Risk Assessment Process in
the Office of Pesticide Programs, U. S. Environmental Protection Agency:
 Endangered and Threatened Species Effects Determinations.  Office of
Prevention, Pesticides and Toxic Substances, Office of Pesticide
Programs, Washington, D.C.

 40 CFR §158.490 Wildlife and Aquatic Organisms Data Requirements,
Guideline Reference No. 71-4

 40 CFR §158.340 Toxicology Data Requirements, Guidelines Reference No.
83-4

 Eason, C.T. and E. Murphy.  2001.  Recognising and reducing secondary
and tertiary risks associated with brodifacoum.  Pages 157-163 in J. J.
Johnston (ed.), Pesticides and Wildlife.  American Chemical Society
Symposium Series 771

 ICI Americas Inc.  1986.  Emergency Call Reports for ICI Americas’
Rodenticides Talon and Havoc 1982-1985.  15 pp.  EPA Accession No.
262910

 Giddings, J. and W. Warren-Hicks.  2004.  A Probabilistic Assessment of
the Risk of Brodifacoum to Non-target Predators and Scavengers.  
Conducted by The Cadmus Group, Inc., Chapel Hill, NC.  Submitted to EPA
by Syngenta Crop Protection, Inc., Greensboro, NC.

 "OPP Evaluation of Cadmus/Brodifacoum Registrants (C/BR) Probabilistic
Risk Assessment Model for Brodifacoum", August 24, 2005, was supported
by the following two reviews: 

Goodrum, P., M. E. Dakins, M. Mastriano, and P. Durkin.  2005.  Peer
Review of Brodifacoum (PP581) Assessment WA 2-10, Syracuse Environmental
Research Associates, Inc., Fayetteville, New York

P. Durkin.  2005.  An Exploratory Physiologically Based Pharmacokinetic
Model for Brodifacoum, Attachment to: Peer Review of Brodifacoum (PP581)
Assessment WA 2-10, SERA TR-46-2-10-1e, Syracuse Environmental Research
Associates, Inc., Fayetteville, New York.

 CDFA is a registrant of zinc phosphide, chlorophacinone, and
diphacinone products for use in California

 EPA. 1998. Guidelines for Ecological Risk Assessment.
EPA/630/R-95/002F, April

1998, Final. 171 pp. http://www.epa.gov/ncea/ecorsk.htm

 Rymph, B.  (ed.).  1994.  Assessing Pesticide Impacts on Birds:  Final
Report of the Avian Effects Dialogue Group, 1988-1993.  RESOLVE Center
for Environmental Dispute Resolution, Washington, DC.  156 pp.

 Mendenhall, V.M. and L.F. Pank.  1980.  Secondary poisoning of owls by
anticoagulant rodenticides.  Wildl. Soc. Bull. 8:311-315

 Kalmbach, E.R.  1943.  Birds, rodents and colored lethal baits.  Trans
N. Amer. Wildl. Conf. 8:408-416

 Moran, S.  1999.  Rejection of dyed field rodent baits by feral pigeons
and chukar partridges.  Phytoparasitica 27:9-17

 Stone, W.B., J.C. Okonlewski, and J.R. Stedelin.  2003.  Anticoagulant
rodenticides and raptors:  recent findings from New York, 1998-2001. 
Bull. Environ. Contam. Toxicol. 70:34-40.

Stone, W.B., J.C. Okonlewski, and J.R. Stedelin.  1999.  Poisoning of
wildlife with anticoagulant rodenticides in New York.  J. Wildl.
Diseases 35:187-193.

Hosea, R.C.  2000.  Exposure of non-target wildlife to anticoagulant
rodenticides in California.  Proc. Vertebr. Pest Conf. 19:236-244.

Riley, S. P. D., R.M. Sauvajot, T.K. Fuller, E.C. York, D.A. Kamradt, C.
Bromley, and

R.K.Wayne.  2003.  Effects of urbanization and habitat fragmentation on
bobcats and

coyotes in southern California.  Conservation Biol.17:566-576.

 Mineau, P., P.A. Martin, L.K. Wilson, J. Duffe, J.R. Stedelin, and B.
Puschner.  2003.  Extensive exposure of Canadian birds of prey to the
second-generation anticoagulant rodenticides brodifacoum and
bromadiolone.  Presented at the Symposium Wildlife Toxicology and
Persistence of Pollutants and Contaminants, 3rd International Wildlife
Management Congress, Christchurch, New Zealand.

McDonald, R.A., S. Harris, G. Turnbull, P. Brown, and M. Fletcher. 
1998.  Anticoagulant rodenticides in stoats (Mustela erminea) and
weasels (Mustela nivalis) in England.  Environ. Pollution 103:17-23.

Shore, R.F., J.D.S. Birks, A. Afsar, C.L. Wienburg, and A.C. Kitchener. 
2003.  Spatial and temporal analysis of second-generation anticoagulant
rodenticide residues in polecats (Mustela putorius) from throughout
their range in Britain, 1992-1999.  Environ. Pollution 122:183-193.

Burn, A.J., I. Carter, and R.F. Shore.  2002.  The threats to birds of
prey in the UK from second-generation rodenticides.  Aspects Appl. Biol.
67:203-212.

Carter, I. and A. Burn.  2000.  Problems with rodenticides: the threat
to red kites and other wildlife.  British Wildl., February, 2000, pp.
192-197.

 McDonald, R.A., S. Harris, G. Turnbull, P. Brown, and M. Fletcher. 
1998.  Anticoagulant rodenticides in stoats (Mustela erminea) and
weasels (Mustela nivalis) in England.  Environ. Pollution 103:17-23.

Shore, R.F., J.D.S. Birks, A. Afsar, C.L. Wienburg, and A.C. Kitchener. 
2003.  Spatial and temporal analysis of second-generation anticoagulant
rodenticide residues in polecats (Mustela putorius) from throughout
their range in Britain, 1992-1999.  Environ. Pollution 122:183-193.

Newton, I., R.F. Shore, I. Wyllie, J.D.S. Birks, and L. Dale.  1999. 
Empirical evidence of side-effects of rodenticides on some predatory
birds and mammals.  Pages 347-367 in D.P. Cowan and C.J. Feare (eds),
Advances in Vertebrate Pest Management.  Filander Verlag, Fürth.

Carter, I. and A. Burn.  2000.  Problems with rodenticides: the threat
to red kites and other wildlife.  British Wildl., February, pp. 192-197

 Munday, J.S. and L.J. Thompson.  2003.  Brodifacoum toxicosis in two
neonatal puppies.  Vet. Pathol. 40:216-219

 Hosea, R.C., B.J. Finlayson, and E.E. Littrell.  2001.  Forensic
investigative techniques to identify impacts (primary and secondary)
from three groups of pesticides on raptors in California.  Pages 38-51
in J. J. Johnston (ed.), Pesticides and Wildlife.  American Chemical
Society Symposium Series 771

 Goodall, M.J., T.M. Primus, and J.J. Johnston.  2002.  Determination of
chlorophacinone and diphacinone residues in California ground squirrels
and non-target animals.  Unpubl. report QA 976, National Wildlife
Research Center, Fort Collins, CO, submitted to EPA by the California
Department of Food and Agriculture, Sacramento.  119 pp.

  Salmon, T.P., D.A. Whissom, and W.P. Gorenzel.  2002.  Field efficacy
studies comparing 0.005% and 0.01% diphacinone and chlorophacinone baits
for controlling California ground squirrels (Spermophilus beecheyi). 
Unpubl. report submitted to EPA by the California Department of Food and
Agriculture, Sacramento.  131 pp.

 Because the study report (Salmon et al. 2002) states that "We saw no
evidence of squirrels traveling between plots during the 24-day period
of our trials on each site.", EFED asked CDFA how they accounted for the
fact that some squirrels had residues of both rodenticides.  CDFA’s
letter of November 6, 2003 indicates that observations of ground
squirrels were not continuous during the study and that "Squirrel
movement between site plots is considered a natural behavioral
occurrence within squirrel populations."  The presence of residue of
both rodenticides in individual ground squirrels also could result from
contamination of bait-mixing or application equipment if the same
equipment was used for both rodenticides.  However, the presence of dead
ground squirrels in 5 of the 8 control plots (Salmon et al. 2002)
suggests that movement among plots, as suggested by CDFA, was the most
likely reason.

 Parkinson, G.R.  1976.  WBA 8119:  Acute Oral Toxicity.  Report No.
CTL/P/216 (revised).  EPA MRID No. 00087134

 Godfrey, M.E.R., T.C. Reid, and H.J.F. McAllum.  1981.  The acute oral
toxicity of the anticoagulant brodifacoum to dogs.  New Zealand J.
Exper. Agric. 9:147-149 

 Godfrey, M.E.R., T.C. Reid, and H.J.F. McAllum.  1981.  The oral
toxicity of brodifacoum to rabbits.  New Zealand J. Exper. Agric.
9:23-25.

 Godfrey, M.E.R.  1984.  Acute toxicity of brodifacoum to wallabies
(Macropus rufogriseus).  New Zealand J. Exper. Agric. 12:63-64.

 Vyas, N.B.  1999.  Factors influencing estimation of pesticide-related
wildlife mortality.  Toxicol. Industrial Health 15:186-191.

 EPA.  1998.  Guidelines for Ecological Risk Assessment. 
EPA/630/R-95/002F, April 1998, Final.  171 pp. 
http://www.epa.gov/ncea/ecorsk.htm

 

 Rymph, B. (ed.).  1994.  Assessing Pesticide Impacts on Birds:  Final
Report of the Avian Effects Dialogue Group, 1988-1993.  RESOLVE Center
for Environmental Dispute Resolution, Washington, DC.  156 pp.

 See December 8-9, 1998 http://www.epa.gov/scipoly/sap/1998/index.htm

 Kaukeinen, D.E., C.W. Spraggins, and J.F. Hobson.  2000.  Risk-benefit
considerations in evaluating commensal anticoagulant rodenticide impacts
to wildlife.  Proc. Vertebr. Pest Conf. 19:245-256

 www.belllabs.com/cgi/products.cgi

 www.hacco.com/2004_Catalog/RodenticideCatalog_2004.pdf

 e.g., California Department of Pesticide Regulation, Pesticide Use
Reporting, http://www.cdpr.ca.gov/docs/pur/purmain.htm

 Mendenhall, V.M. and L.F. Pank.  1980.  Secondary poisoning of owls by
anticoagulant rodenticides.  Wildl. Soc. Bull. 8:311-315

 the expert peer reviews are available in the Rodenticide Cluster
EDocket, www.epa.gov/oppsrrd1/rodenticidecluster/index.htm 

 e. g., barn owl (0.007 ppm brodifacoum) and red-tailed hawk (0.077 ppm
brodifacoum) - Final Report, Diagnostic Services Section, Southeastern
Cooperative Wildlife Disease Study, College of Veterinary Medicine, The
University of Georgia, Athens, Georgia (Case No. CC246-03, January 5,
2003) and Golden eagle (0.04 ppm brodifacoum) - Hosea et al. (2001,
Forensic investigative techniques to identify impacts (primary and
secondary) from three groups of pesticides on raptors in California. 
Pages 38-51 in J. J. Johnston (ed.), Pesticides and Wildlife.  American
Chemical Society Symposium Series 771

  Anonymous.  2001.  Analysis of the supporting data for EPA’s EIIS
database with respect to rodenticides.  Unpubl. report prepared for the
Rodenticide Registrants Task Force to EPA by Arcadis Geraghty and
Miller, Millersville, MD.  29 pp. and Kaukeinen et al. (2000) [cited in
footnote 4 for Comment 3]

 S. Hansen (Senior Vice President, Animal Poison Control Center, Urbana,
IL) pers. comm. to W. Erickson, EFED

 Stone, W.B., J.C. Okonlewski, and J.R. Stedelin.  1999.  Poisoning of
wildlife with anticoagulant rodenticides in New York.  J. Wildl.
Diseases 35:187-193 and

  Stone, W.B., J.C. Okonlewski, and J.R. Stedelin.  2003.  Anticoagulant
rodenticides and raptors:  recent findings from New York, 1998-2001. 
Bull. Environ. Contam. Toxicol. 70:34-40

 40 CFR §158.490, Wildlife and Aquatic Organisms Data Requirements,
Guidelines Reference No.71-3 "Wild mammal toxicity"

 McCann, J.A., W. Teeters, D.J. Urban and N. Cook. 1981.  A short-term
dietary toxicity test on small mammals.  Pages 132-142 in D.W. Lamb and
E.E. Kenaga (eds):  Avian and Mammalian Wildlife Toxicology: Second
Conference, ASTM STP 757, American Society for Testing Materials.

 40 CFR §158.340, Toxicology Data Requirements, Guidelines Reference
No. 83-4 "Reproduction, 2-generation"

 40 CFR §158.490, Wildlife and Aquatic Organisms Data Requirements,
Guidelines Reference No. 71-4 "Avian reproduction" 

 Warfarin and its Sodium Salt.  Reregistration Eligibility Document. 
1991.  SRRD/OPP/EPA. 
http://www.epa.gov/pesticides/reregistration/status.htm

 Reregistration Eligibility Decision (RED):  Rodenticide Cluster.  1998.
EPA738-R-98-007.  307 pp. 
http://www.epa.gov/pesticides/reregistration/status.htm 

 Munday, J. S. and L. J. Thompson. 2003. Brodifacoum Toxicosis in two
neonatal puppies. Vet. Pathol. 40: 216-219

 Hegdal, P.L. and R. W. Blaskiewicz.  1984.  Evaluation of the potential
hazard to barn owls of talon (brodifacoum bait) used to control rats and
house mice.  Environ. Toxicol. Chem. 3:167-179

 Newton, I., I. Wyllie, and P. Freestone.  1990.  Rodenticides in
British barn owls.  Environmental Pollution 68:101-117

 Howald, G.R., P. Mineau, J.E. Elliott, and K.M. Cheng.  1999. 
Brodifacoum poisoning of avian scavengers during rat control on a
seabird colony.  Ecotoxicol. 8:431-447

 Bullard, R.W., R.D. Thompson, and G. Holgvin. 1976:  Diphenadione
(diphacinone) residue in tissue of cattle.  J. Agric. Food Chem.
24:261–263.

 e. g., Marsh, R.E.  1985.  Are anticoagulant rodenticides a problem for
household pets?  Pest Control 53(8):20-22,24 and 53(9):26-28,31

 Diaz, L.I. and D.M. Whitacre.  1976.  Excretion and retention of
14C-diphacinone in rats.  Unpubl. report, submitted by Velsicol Chemical
Corporation.  8 pp

 Goldade, D.A., P.J. Savarie, J.C. Hurley, S.A. Gaddis, and J.J.
Johnson.  2001.  Design of a laboratory secondary hazard study.  Pages
146-156 in J. J. Johnston (ed.), Pesticides and Wildlife.  American
Chemical Society Symposium Series 771

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