U.S.  ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460

OFFICE OF

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

PC Code: 055801

DP Barcodes: 3511118

MEMORANDUM					DATE: April 21 2008

							

	

SUBJECT:	Revised Ecological Risk Assessment for Reregistration
Eligibility Decision (RED) for Naphthalene

FROM:	Stephen Carey, Biologist

		Mark Corbin, Senior Environmental Scientist

		Environmental Risk Branch III

		Environmental Fate and Effects Division (7507P)

TO:		Molly Clayton

		Reregistration Branch 

		Special Review and Reregistration Division (7508P)

REVIEWED 

BY:		Pamela Hurley, Toxicologist

		James Hetrick, Senior Scientist

		Environmental Risk Branch III

		Environmental Fate and Effects Division 7507P

APPROVED 

BY:		Karen Whitby, Branch Chief

		Environmental Risk Branch III

		Environmental Fate and Effects Division 7507P

	The Environmental Fate and Effects Division (EFED) has completed the
environmental fate and ecological risk assessment in support of the
re-registration of the repellent, Naphthalene (CAS Registry Number:
91-20-3); End Use Products - ENOZ® Skat! – white solid
flakes/crystals (granular) containing 99.45% active ingredient (a.i.)
[EPA Reg. No. 1475-146]; Snake-A-Way – white solid flakes/crystals
(granular) containing 7.0% ai [EPA Reg. No. 58630-1]; Shotgun® Rabbit &
Dog Repellent – white solid flakes/crystals (granular) containing
15.0% ai [EPA Reg. No. 4-465]; and Bat-A-Way Bird, Squirrel, Rabbit &
Bat Repellent  - white solid flakes/crystals (granular) containing
99.95% active ingredient [EPA Reg. No. 58630-2], for use to repel
unwanted animal visitors from flowering beds, buildings, and gardens in
non-cropped and domestic outdoor areas. Conclusions regarding the
environmental fate, ecological effects, and ecological risks associated
with the proposed use in residential areas can be found in the Executive
Summary of the attached document.

Data Gaps

Table A.1. identifies the status of environmental fate and transport
study requirements and Table A.2. identifies the status of ecological
effects study requirements.  

Table A.1 Environmental Fate Data Requirements for Naphthalene

Guideline #	Data Requirement	MRID #

	Study Classification	Are more data needed?



161-1	Hydrolysis	Not available	Not available	No.  Published literature
suggests this is an insignificant route of dissipation.



161-2	

Photodegradation in Water 	Not available	Not available	No.  Published
literature suggests this is an insignificant route of dissipation.



161-3	

Photodegradation on Soil	Not available	Not available	No.  Published
literature suggests this is an insignificant route of dissipation and
this is not a model input.



161-4	

Photodegradation in Air	Not available	Not available	No



162-1	

Aerobic Soil Metabolism	Not available	Not available	Yes.  Model
assumptions based on the supplemental data from the open literature. 
Submission of acceptable data can provide for confirmation of
assumptions or inputs for refined modeling.

162-2	Anaerobic Soil

Metabolism	Not available	Not available	No



162-3	

Anaerobic Aquatic Metabolism	Not available	Not available	No



162-4	

Aerobic Aquatic Metabolism	Not available	Not available	Yes. Lack of data
led to the assumption of half life at two times the aerobic soil
metabolism value.  Submission of data can remove uncertainty in this
assumption.



163-1	Soil Column Leaching

(Aged)

Adsorption/Desorption

 (parent)	Not available	Not available	Yes. Supplemental data from open
literature.  Model assumptions were based on these supplemental data. 
Submission of acceptable data can provide for confirmation of
assumptions or inputs for refined modeling.



163-2	

Laboratory Volatility	Not available	Not available	No



163-3	

Field Volatility	Not available	Not available	No



164-1	

Terrestrial Field Dissipation	Not available	Not available	No.  



164-2	

Aquatic Field Dissipation	Not available	Not available	No



164-3	

Forestry Dissipation	Not available	Not available	No



165-4	

Accumulation in Fish	Not available	Not available	No



165-5	

Accumulation in aquatic non-target organism (crayfish)	Not available	Not
available	No



166-1	

Ground Water- small 

scale prospective	Not available	Not available	No



Table A.2 Ecological Effects Data Requirements for Naphthalene



Guideline	

Data Requirement	

Test Material	

MRID	

Study Classification	Are More Data Needed?



71-1	

Avian Oral LD50	

Naphthalene	148176	

Supplemental	Yes. The purity of the active ingredient needs to be
reported to upgrade the study to acceptable from supplemental.



71-2	

Avian Dietary LC50	

Naphthalene	

148175

Not available	

Supplemental

Not available	

Yes. The purity of the active ingredient in the bobwhite quail test
needs to be reported to upgrade the study to acceptable from
supplemental. A subacute dietary study with the mallard duck is required
to determine the toxicity of naphthalene to waterfowl.  Together the
studies would fulfill the 72-1 guideline (subacute avian dietary
toxicity tests with an upland game bird and waterfowl) for an outdoor
noncrop use.



71-4	

Avian Reproduction	

Naphthalene	Not available	Not available	

No



72-1	

Freshwater Fish LC50	

Naphthalene	

45030801

44302701	Supplemental

Acceptable	

No. Even though the study is not repairable, the 72-1 guideline has been
fulfilled for a toxicity test with a warm water and cold water fish. 

No



72-2	

Freshwater Invertebrate Acute LC50	

Naphthalene	

44302702	

Acceptable	

No



72-3(a)	

Estuarine/Marine Fish LC50	

Naphthalene	Not available	Not available	

No



72-3(b)	

Estuarine/Marine Mollusk EC50	

Naphthalene	Not available	Not available	

No



72-3(c)	

Estuarine/Marine Shrimp EC50	

Naphthalene	Not available	Not available	

No



72-4(a)	

Freshwater Fish Early Life-Stage	

Naphthalene	

46220970	

Supplemental	

No. However, the non-guideline study was conducted with salmon fry
instead of eggs.



72-4(b)	

Aquatic Invertebrate Life-Cycle (freshwater)	

Naphthalene	Not available	Not available	No

123-1(a)	Seedling Emergence

(Tier I)	Naphthalene 	Not available	Not available	Yes.  Product labels,
summary reviews of available open literature data, and toxicity tests
with green algae suggest naphthalene is phytotoxic to plants. A Tier I
seedling emergence toxicity test is recommended to determine the
toxicity of naphthalene to terrestrial plants. If plants are sensitive
to naphthalene, there might be direct effects to plants and possible
indirect effects to animal taxa due to loss of cover or food sources.
However, the likelihood for plants to be at risk from naphthalene is low
but cannot be precluded at this time.



123-1(b)	

Vegetative Vigor (Tier I)	

Naphthalene 	Not available	Not available	Yes.  Product labels, summary
reviews of available open literature data, and toxicity tests with green
algae suggest naphthalene is phytotoxic to plants. A Tier I vegetative
vigor toxicity test is recommended to determine the toxicity of
naphthalene to terrestrial plants. If plants are sensitive to
naphthalene, there might be direct effects to plants and possible
indirect effects to animal taxa due to loss of cover or food sources.
However, the likelihood for plants to be at risk from naphthalene is low
but cannot be precluded at this time.



123-2

Aquatic Plant Growth

(Tier I and II)	

Green Algae	

Naphthalene	

Not available	

Not available	

No 

	Duckweed, Lemna gibba	

Naphthalene	Not available	Not available	

Product labels, summary reviews of available open literature data, and
toxicity tests with green algae suggest naphthalene is phytotoxic to
plants. A Tier I aquatic vascular plant toxicity test is recommended to
determine the toxicity of naphthalene to vascular plants. If plants are
sensitive to naphthalene, there might be direct effects to plants and
possible indirect effect to animal taxa due to loss of cover or food
sources. However, the likelihood for plants to be at risk from
naphthalene is low but cannot be precluded at this time.

	

Freshwater Diatom, Navicula	

Naphthalene	Not available	Not available	Reserved. A Tier II toxicity
test with a freshwater diatom is recommended if testing with terrestrial
plants raises any concerns and/or if open literature data with
freshwater diatoms are unavailable. If plants are sensitive to
naphthalene, there might be direct effects to plants and possible
indirect effect to animal taxa due to loss of cover or food sources.
However, the likelihood for plants to be at risk from naphthalene is low
but cannot be precluded at this time. 

	

Marine Diatom	

Naphthalene	Not available	Not available	Reserved. A Tier II toxicity
test with a marine diatom is recommended if testing with terrestrial
plants raises any concerns and/or if open literature data with marine
diatoms are unavailable. If plants are sensitive to naphthalene, there
might be direct effects to plants and possible indirect effect to animal
taxa due to loss of cover or food sources. However, the likelihood for
plants to be at risk from naphthalene is low but cannot be precluded at
this time.

	

Blue-green algae	

Naphthalene	Not available	Not available	Reserved. A Tier II toxicity
test with a blue-green alga is recommended if testing with terrestrial
plants raises any concerns and/or if open literature data with
blue-green algae are unavailable. If plants are sensitive to
naphthalene, there might be direct effects to plants and possible
indirect effect to animal taxa due to loss of cover or food sources.
However, the likelihood for plants to be at risk from naphthalene is low
but cannot be precluded at this time.



141-1	

Honey Bee Acute

Contact LD50	

Naphthalene	

N/A	

N/A	

Naphthalene is volatile. It is uncertain if there is a direct effect to
pollinators visiting flowers and gardens treated with naphthalene or if
there are indirect effects to flowers when bees are prevented from
visiting/pollinating the area. An acute contact test with honeybees is
recommended. 



ECOLOGICAL RISK ASSESSMENT

Re-Registration

Naphthalene

CAS Registry Number: 91-20-3

U.S. EPA Pesticide Code Number: 055801

 

Repellent Proposed for Outdoor Uses on Non-Cropped and Domestic Outdoor
Areas

CAS Name:  Naphthalene

IUPAC Name: Naphthalene

Proposed End-use Products:  “ENOZ® Skat!”, “Snake-A-Way”,
“Shotgun® Rabbit & Dog Repellent”, and “Bat-A-Way Bird, Squirrel,
Rabbit & Bat Repellent” (7.0-99.95% naphthalene as the single active
ingredient in white solid flakes/crystals). 

Assessors:

Stephen Carey, Biologist

Mark Corbin, Senior Environmental Scientist

Secondary Reviewers:

Pamela Hurley, Toxicologist

James Hetrick, Senior Scientist

Branch Chief:

Karen Whitby 

Ecological Risk Branch III

Executive Summary

                  A.    Nature of Chemical Stressor

The Environmental Fate and Effects Division (EFED) have assessed the
potential ecological risks associated with the use of naphthalene. 
Naphthalene is a repellent used to control both indoor and outdoor moth
and mammal infestations.  The labeled indoor uses for naphthalene are
not expected to result in exposure to non-target terrestrial and aquatic
organisms.  Thus, indoor uses (i.e. mothballs) are not considered in
this assessment.  Of the registered uses, four labels currently specify
outdoor use and products are formulated as granular formulations,
technically naphthalene crystals or flakes.  The outdoor labels state
that the products are to be used as repellents for snakes, mammals, and
birds from ornamental plants, gardens, and the perimeters of structural
buildings.  With the exception of statements that the product should be
applied in bands of at least one inch wide (ENOZ Skat!; EPA Reg #
1475-146) and up to 12 inches wide (Snake-A-Way; EPA Reg #58630-1), the
outdoor use labels generally contain a non-specific application
description.  In addition, the existing labels indicate that multiple
applications may be required for effective repellency, but do not limit
the number of applications.  

Conclusions – Exposure Characterization

In order to provide an assessment of potential exposure to non-target
organisms from the terrestrial non-crop use of naphthalene, several
assumptions were made regarding the amount applied per acre and the
total number of applications expected to be used.  According to
information provided by the registrants, naphthalene is typically
applied outdoors with application rates of 10.8 lbs/acre for use as a
rabbit and dog repellent and 0.56 lbs/acre as a snake repellent. 
Typically, naphthalene is applied in bands of 4 to 12 inches in width,
which will limit the total pounds per acre applied.  For the purpose of
this assessment, it is assumed that a single application will represent
a band of 12 inches surrounding a planted bed or the perimeter of a
house/garden.  The registrant also indicates that applications should be
repeated as needed with a typical application interval of 2 to 3 months.
 Given this, it is assumed, for the purpose of this assessment,
naphthalene will be applied up to six times per year.  Since naphthalene
will not be applied to the entire target site but is applied in a band,
an adjustment factor of 4.1% has been applied to GENEEC2 model output to
account for this aspect of the products’ applications. 

Aquatic exposures were estimated using the Tier 1 model, GENEEC2, and
terrestrial exposures were estimated using the Tier 1 model, T-REX v.
1.3.1.  For GENEEC2 and T-REX modelings, granules are used as a
surrogate for flakes or crystals.  

                  C.     Conclusions – Effects Characterization

Based on the data requirements for a terrestrial non-crop/domestic
outdoor use as a repellent, all data except terrestrial and aquatic
vascular plants were submitted and reviewed for the naphthalene risk
assessment using the granular banded application and incidental
ingestion exposure methods. Available acute toxicity data with aquatic
species indicate that naphthalene is moderately toxic to freshwater fish
and invertebrates with LC50 values of 2.0 and 1.6 mg ai/L, respectively.
Toxicity data with aquatic nonvascular plants indicate that naphthalene
is slightly toxic to green algae with EC50 values of 33 and 34 mg/L.
Following chronic exposure, a reduction in survival, feeding behavior,
and growth were observed in Coho salmon; the LOAEC and NOAEC were 0.67
and 0.37 mg ai/L, respectively. The results of an embryo-larval toxicity
test with the Fathead minnow demonstrated adverse effects at a
concentration of 0.85 mg/L, the NOAEC was 0.62 mg/L. Toxicity data were
not available for aquatic vascular plants; consequently, the toxicity of
naphthalene to aquatic vascular plants is unknown.

Available acute toxicity data with terrestrial species indicate that
naphthalene is practically non-toxic to upland game birds (acute oral
LD50 = 2690 mg ai/kg bw; acute dietary LC50 >5620 mg ai/kg diet). Acute
dietary toxicity data with the mallard duck was not available; the
toxicity to waterfowl exposed to granular naphthalene is unknown.
Available acute toxicity data also indicate that naphthalene is
practically non-toxic to mammals (acute oral LD50 = 2649 mg ai/kg bw). 

Two-generation reproductive toxicity studies evaluating reproductive
performance of mammals exposed to naphthalene are not available,
although the occurrence of hemolytic anemia in the neonates of anemic,
naphthalene-exposed mothers demonstrates that naphthalene and/or its
metabolites can cross the placental barrier. Following chronic exposure,
rat studies involving naphthalene exposure during gestation reported
that doses of 150 mg/kg/day and greater were maternally toxic to rats
with a decrease in number of live mouse pups per litter with a dose of
300 mg/kg/day given during gestation. In vitro studies of naphthalene
embryotoxicity in the presence of liver microsomes support the concept
that naphthalene metabolites may be harmful to the developing embryo.
Toxicity data were not available for honeybees and terrestrial plants;
consequently, the toxicity of naphthalene to beneficial insects and
terrestrial plants is unknown.  

No chronic studies with freshwater and marine/estuarine invertebrates
and birds were available. Summary reviews of available open literature
data concerning the toxicity of naphthalene degradation products were
identified; however, those data were unavailable for this assessment. 

                  D.     Potential Risks to Non-target Animals and
Plants

Based on the available ecotoxicity information and the estimated
environmental exposures, naphthalene may pose an acute risk to birds,
mammals, terrestrial-phase amphibians and reptiles.  Acute risk is not
expected for freshwater animals, aquatic-phase amphibians and aquatic
nonvascular plants.  Due to lack of toxicity data, risks to honey bees,
and terrestrial and aquatic vascular plants are unknown. Lack of
toxicity data does not preclude potential risk to these taxa.  Tables 1
and 2 provide summaries for the environmental risk conclusions for
aquatic and terrestrial animals and plants.

TABLE 1.   Summary of Environmental Risk Conclusions for Aquatic
Organisms

Assessment Endpoint	Use Patterns with LOC Exceedances	Summarized Risk
Characterization

Acute Risk to Freshwater Fish and Aquatic-phase Amphibians from Granular
Application	None	At the peak EECs, there are no exceedances of the Acute
Risk, Acute Restricted Use, or Acute Endangered Species LOCs for
freshwater fish. 

EFED currently uses surrogate data (freshwater fish) for aquatic-phase
amphibians. Since the fish risk assessment indicates no acute LOC
exceedances, consequently, there are no risk concerns for aquatic-phase
amphibians.    

Acute Risk to Freshwater Invertebrates from Granular Application	None	At
the peak surface water EECs, there are no exceedances of the Acute Risk,
Acute Restricted Use, or Acute Endangered Species LOCs for freshwater
invertebrates.  

Acute Risk to Estuarine/marine Fish and Invertebrates from Granular
Application	None	At the peak surface water EECs, there are no
exceedances of the Acute Risk, Acute Restricted Use, or Acute Endangered
Species LOCs for estuarine/marine fish and invertebrates.  

Risk to Aquatic Vascular Plants from Granular Application	No information
available	No aquatic vascular plant (e.g., duckweed) toxicity studies
were submitted; therefore, risk to aquatic vascular plants receiving
runoff from granular naphthalene is unknown. Label and summary reviews
of open literature data suggest possible phytotoxicity to plants.

Risk to Aquatic Nonvascular Plants from Granular Application	None	At the
peak surface water EECs, there are no exceedances of the Acute Risk or
Acute Endangered Species LOCs for green algae.  



TABLE 2.  Summary of Environmental Risk Conclusions for Terrestrial
Organisms

Risk Conclusion	Use Patterns with LOC Exceedances	Summarized Risk
Characterization

Acute Risk to Birds (including terrestrial-phase amphibians and
reptiles) from Granular Application	Terrestrial non-crop use 

(10.8 lbs ai/A x 6 appls with 60 day reapplication interval)

Terrestrial non-crop use

 (0.56 lb ai/A x 6 appls with 60 day reapplication interval)	Using the
LD50/ft2 exposure method for assessing risk from granular banded
applications, Acute, Acute Restricted use, and Endangered Species LOCs
are exceeded for 20, 100, and 1000 g birds using the dose-based LD50
value.  Although there is exceedance of LOCs from the LD50/ft2 analysis,
the potential for risk to birds is based on the assumption that birds
are feeding exclusively within the 12-inch-wide banded application
around the house or garden perimeters. The likelihood for risk to birds
is low because: 1) It is anticipated that birds may likely be repelled
away from the treated band; 2) It is unlikely birds will obtain all
dietary items from within the treated band; and, 3) The EECs calculated
in the T-REX analysis may be overestimated (e.g., a minimum row [banded]
length of 209 feet long around gardens and houses is unlikely).     

Using the LD50/ft2 exposure method for assessing risk from granular
banded applications, the Acute, Acute Restricted Use and Acute
Endangered Species LOCs are exceeded for 20 and 100 g birds using the
dose-based LD50 value. Acute Restricted Use and Acute Endangered Species
LOCs are exceeded for 1000 g birds using the dose-based LD50 value.
Although there is exceedance of LOCs from the LD50/ft2 analysis, the
potential for risk to birds is based on the assumption that birds are
feeding exclusively within the 12-inch-wide banded application around
the perimeter of a house or garden. The likelihood for risk to birds is
low because: 1) It is anticipated that birds may likely be repelled away
from the treated band; 2) It is unlikely birds will obtain all dietary
items from within the treated band; and, 3) The EECs calculated in the
T-REX analysis may be overestimated (e.g., a minimum row [banded] length
of 209 feet long around gardens and houses is unlikely).     

Acute Risk to Mammals from Granular Application	Terrestrial non-crop use

(both 10.8 and 0.56 lb ai/A)	Using the LD50/ft2 exposure method for
assessing risk from granular applications, the Acute, Acute Restricted
Use and Acute Endangered Species LOCs are exceeded for 15, 35, and 1000
g mammals ingesting naphthalene granules at both application rates. 
Although there is exceedance of LOCs from the LD50/ft2 analysis, the
potential for risk to mammals is based on the assumption that mammals
are feeding exclusively within the 12-inch-wide banded application
around the house or garden perimeters. The likelihood for risk to
mammals is low because: 1) It is anticipated that mammals will likely be
repelled away from the treated band; 2) It is unlikely mammals will
obtain all dietary items from within the treated band; and, 3) The EECs
calculated in the T-REX analysis is overestimated, since a row (banded)
length of 209 feet long around garden and houses is unlikely.     

Risk to Non-target Beneficial Insects from Granular Application	No
information available	No honeybee data were provided; risk to honeybees
visiting treated areas is unknown. In addition, it is unknown if plants
will be indirectly affected from the absence of pollinators visiting the
area. 

Risk to Terrestrial Plants from Granular Application	No information
available	No terrestrial plant toxicity studies were submitted; risk to
terrestrial plants receiving runoff from granular naphthalene is low but
cannot be precluded at this time. Labels and a summary review of open
literature data suggest possible phytotoxicity to plants.   

Risk to Terrestrial Animals from Incidental Ingestion of Granules
Terrestrial non-crop use

(both 10.8 and 0.56 lbs ai/A x 6 appls with 60 day reapplication
interval)	To exceed the endangered species LOC, only 1/10th and nine
naphthalene granules ingested are needed for a 20-g and 1000-g species,
respectively, to pose a risk from incidental ingestion. To exceed the
acute restricted use LOC, ½ and 46 naphthalene granules ingested are
needed for a 20-g and 1000-g species, respectively, to pose a risk from
incidental ingestion.  To exceed the acute risk LOC, 1 and 92
naphthalene granules ingested are needed for a 20-g and 1000-g species,
respectively, to be potentially at risk from incidental ingestion.  



                  

E.      Conclusions – Endangered Species

Direct effects LOCs were exceeded for birds, terrestrial-phase
amphibians, reptiles and mammals. Therefore, there is potential for
indirect effects to all terrestrial animal and plant taxa that depend on
those animals as pollinators or seed dispersers, mammal or reptile
burrows for habitat, feeding, or cover requirements, and for survival,
growth, or reproduction. In addition, no terrestrial plant toxicity data
are available; if plants are found to be sensitive to naphthalene, there
might be direct effects to plants and possible indirect effect to animal
taxa due to loss of cover or food sources. The animal and plant species
that reside in those areas, and the basis for the designation, are in
Appendices H and I and are summarized in Table 3, below.

Table 3.  Listed taxonomic groups potentially at risk associated with
direct or indirect effects due to applications of naphthalene on areas
where ornamental plants, flowering beds and gardens are grown nationwide

Listed Taxon	Direct Effects	Basis for Direct Effects Concern	Indirect
Effects	Basis for Indirect Effects Concern

Terrestrial and Semi-Aquatic Plants – monocots and dicots	Yes	Since
the product labels state, “Do not apply the product directly to
foliage or stems,” this statement indicates that there is a
possibility of phytotoxicity. In addition, a summary review of open
literature data suggests naphthalene is selectively phytotoxic to
plants. However, toxicity data are not available for terrestrial plants
exposed to naphthalene. If plants are sensitive to naphthalene, there
might be direct effects to plants. The likelihood for plants to be at
risk from naphthalene is low but cannot be precluded at this time. 	Yes
Potential concerns for monocots and dicots that depend on birds,
reptiles, terrestrial-phase amphibians and mammals as pollinators or
seed dispersers. If pollinators such as honeybees, beneficial insects,
and birds/mammals are repelled from naphthalene, there might be indirect
effects to plants due to loss of pollinators for flower fertilization.

Honeybees	Yes	No data on honeybees are available. Since naphthalene is
volatile, it is uncertain if honeybees will be impacted from pollinating
the treated areas or if flowers will be indirectly affected from the
absence of pollinators. The likelihood of direct effects to honeybees is
low but cannot be precluded at this time.	Yes	Potential concerns for
honeybees that depend on mammal or reptile burrows for habitat, feeding,
or cover requirements.

Birds and Reptiles1	Yes	The endangered species LOC is exceeded for both
high and low application rates.	Yes	Potential concerns for birds and
reptiles that eat mammals as a food resource. 

Terrestrial-phase Amphibians1	Yes	The endangered species LOC is exceeded
for both high and low application rates.	Yes	Potential concerns for
terrestrial-phase amphibians that eat birds, reptiles and mammals as a
food source or depend on mammal or reptile burrows for habitat and
shelter.

Mammals

	Yes	The endangered species LOC is exceeded for both high and low
application rates. 	Yes	Potential concerns for mammals that eat birds,
reptiles and terrestrial-phase amphibians and depend on reptile burrows
for habitat and shelter.

Aquatic Vascular Plants	Yes	Since the product labels state, “Do not
apply the product directly to foliage or stems,” this statement
indicates that there is a possibility of phytotoxicity. In addition, a
summary review of open literature data suggests naphthalene is
selectively phytotoxic to plants. However, toxicity data are not
available for aquatic plants exposed to naphthalene. If plants are
sensitive to naphthalene, there might be direct effects to plants. The
likelihood for plants to be at risk from naphthalene is low but cannot
be precluded at this time.	Yes	Potential concerns for aquatic vascular
plants that depend on birds, reptiles, terrestrial-phase amphibians and
mammals as pollinators or seed dispersers. If pollinators such as
honeybees, beneficial insects, and birds/mammals are repelled by
naphthalene, there might be indirect effects to plants due to loss of
pollinators for flower fertilization.

Freshwater Invertebrates, Fish and Aquatic-phase Amphibians2	No	No LOC
exceedances	Yes	If plants are directly or indirectly affected from
exposure to naphthalene, freshwater fish and amphibians may be
indirectly affected due to loss of cover or food sources. 

Estuarine/marine Fish and Invertebrates	No	No LOC exceedances	Yes	If
plants are directly or indirectly affected from exposure to naphthalene,
estuarine/marine fish and invertebrates may be indirectly affected due
to loss of cover or food. 

Aquatic Nonvascular  Plants – algae and diatoms	No	No LOC exceedances
Yes	Potential concerns for aquatic nonvascular plants that depend on
birds, reptiles, terrestrial-phase amphibians and mammals as pollinators
and seed dispersers. If pollinators such as honeybees, beneficial
insects, and birds/mammals are repelled by naphthalene, there might be
indirect effects to plants due to loss of pollinators for flower
fertilization.

Birds are used as surrogate species for terrestrial-phase amphibians and
reptiles; therefore, potential direct and indirect effects to endangered
avian, terrestrial-phase amphibians and reptilian species are considered
equivalent.

 Fish are used as a surrogate for aquatic phase amphibians; therefore,
potential direct and indirect effects to endangered fish and
aquatic-phase amphibian species are considered equivalent.



                  F.       Identification of Uncertainties and Their
Impact on the Risk Assessment

There are a number of areas of uncertainty in the terrestrial and
aquatic species risk assessments that could potentially cause an
underestimate or overestimate of risk. First, this assessment accounts
only for exposure to non-target animals and plants to naphthalene, but
not to its degradation products. The risks could be underestimated if
degradates also exhibit toxicity under the conditions of use as stated
on the labels. Summary reviews of available open literature data
concerning the toxicity of naphthalene degradation products were
searched; however, those data were unavailable for this assessment.
Second, the risk assessments only consider the most sensitive species
tested and only considers a subset of possible use scenarios. Third, for
screening terrestrial risk assessments, a generic bird or mammal is
assumed to occupy the treated site, and to consume 100% of its diet as
the pesticide. The actual habitat requirements of any particular
terrestrial species are not considered, and it is assumed that species
occupy, exclusively and permanently, the treated area being modeled. 
This assumption leads to a maximum level of exposure in the risk
assessment. Since naphthalene is a repellent used to control unwanted
species from habiting the treated area, the risk estimations for birds,
terrestrial-phase amphibians, reptiles, and mammals exposed to
naphthalene granules may be overestimated. Fourth, the aquatic exposure
assessment relies on GENEEC2 to provide screening level estimates of
exposure using a limited data set of environmental fate data.  In
general, GENEEC2 provides high end exposure estimates that likely
over-estimate exposure in aquatic systems.  The potential impacts of
uncertainties are detailed in section III.D of this document. 

Additional uncertainty results from lack of information and/or data in
several components of this ecological risk assessment, as follows:

- The T-REX model is designed to calculate risk indices from pesticide
applications on an entire one-acre agricultural field by broadcast
spray/granular application or by rows/bands. Since naphthalene is
proposed for an application of a 12-inch-wide band around the perimeter
of a flowering bed, house, or garden to repel unwanted species, T-REX
assumptions may over-estimate the risk indices for birds,
terrestrial-phase amphibians, reptiles, and mammals exposed to
naphthalene flakes. Even though there is an exceedance of the levels of
concern for acute risk to those species, the exceedance is based on the
assumption that the species occupy, exclusively and permanently, the
12-inch-wide band around the perimeter of a house or garden. To the
extent that a repelled species does not reside exclusively and
permanently within the 12-inch banded area(s), exposure will be less and
risk will presumably be less.   

- No data are available for honeybees to assess the risk to pollinators
visiting flowering beds or gardens. Naphthalene is volatile, and it is
unknown if honeybees will be discouraged from pollinating the treated
area or if plants will be indirectly affected from the absence of
pollinators visiting the area.

 

- There are a number of uncertainties associated with the environmental
fate data.  No acceptable environmental fate studies have been submitted
to support this risk assessment.  A single summary review of available
open literature data was provided for aerobic soil metabolism and
adsorption/desorption.  However, these data have not been fully reviewed
and are used as supplemental information for risk assessment purposes. 
No additional data for other important environmental fate processes
(hydrolysis, photolysis, aerobic aquatic metabolism) have been
submitted, although some open literature data is available from other
sources (US NPS, 1997) although much of this data is limited and has not
been thoroughly reviewed.   Where data are missing, an assumption of
stability has been incorporated into the exposure modeling which likely
over-estimates predicted exposures, particularly aqueous photolysis
which has been shown to be rapid in some studies.  In addition,
volatility is unaccounted for in Tier I modeling conducted for this
assessment.  It is uncertain whether the aerobic soil metabolism data
includes losses due to volatility (which would be expected in an open
system) and thus it is uncertain whether the lack of accounting for
volatility in the modeling results in an over-estimation of exposure.
There is some suggestion from the open literature that naphthalene
degrades rapidly in aerobic aquatic conditions but these data are
suspect as they may represent lumped dissipation processes and not true
degradation (US NPS, 1997).

- No terrestrial or aquatic vascular plant studies are available. While
the product labels state specifically for terrestrial non-crop/domestic
outdoor uses, “Do not apply the product directly to foliage or
stems,” this statement indicates that there is a possibility of
phytotoxicity; in addition, a summary review of open literature data
suggest that naphthalene is selectively phytotoxic to plants.  If plants
are sensitive to naphthalene, there might be direct affects to plants
and possible indirect affects to animal taxa due to loss of cover or
food sources. The likelihood of risk to plants may be low but cannot be
precluded at this time.

- No preliminary analysis was performed for non-food uses of naphthalene
because the LOCATES tool does not include county-level location
information for the proposed non-food use of naphthalene. Consequently,
based on the information available at this step in the assessment
process, it is presumed that all listed animal species are potentially
directly affected from the broad range of naphthalene proposed uses
which include areas around houses, cabins, trailers, garages, utility
houses, barns, woodpiles, sand piles, trash cans, flower beds, plants
(ornamentals, roses, spring bulbs), around the periphery of gardens, and
garbage bags placed near residences and other buildings, streets or
alleys for garbage collection. Additional analysis of listed animal
locations, refinement of the action area associated with naphthalene
regulatory decisions, and the biology of the potentially affected
species would be needed before an effects determination can be made for
any of the co-located species identified by this assessment.

- Currently, the T-REX model does not have the capability to estimate
chronic exposure to terrestrial animals from banded granular
applications. 

TABLE OF CONTENTS

PROBLEM
FORMULATION…………………...………………………………
…………1

	A.  STRESSOR SOURCE AND
DISTRIBUTION…………………………...…………....1 

		1. Mode of
Action…………………………………………………………
………………….1

		2. Chemical Identification of
Naphthalene…………………………………………………1

		3. Overview of Pesticide
Usage…………………………………………………………
……2

	B. 
RECEPTORS………………………………………………………
…..………………...2

		1.  Aquatic
Effects………………………………………………………
…………………….3

		2.  Terrestrial
Effects………………………………………………………
…………...……4

		3.  Ecosystems at
Risk…………………………………………………………
……………..4

	C.  ASSESSMENT
ENDPOINTS……………………………………………………...
……4

	D.  CONCEPTUAL
MODEL...................................................................
.......................…...5

		1.  Risk
Hypotheses……………………………………………………
……………………...6

		2.  Conceptual Model
Diagram.......................……………………………………
…………6

	E.  ANALYSIS
PLAN…………………………………………....……………
……...……...8

	F.  DATA
GAPS....................................................................
...................................................9

II.
ANALYSIS................................................................
.............................................................11

	A.  USE
CHARACTERIZATION........................................................
................................11

	B.  EXPOSURE
CHARACTERIZATION........................................................
..................11

		1.  Environmental Fate and
Transportation..........................................................
..............11

		2.  Aquatic Exposure
Modeling................................................................
.............................12

		3.  Terrestrial Exposure
Modeling................................................................
........................13

	C.  ECOLOGICAL EFFECTS
CHARACTERIZATION.................................................15

		1.  Aquatic
Effects.................................................................
.................................................16

		2.  Terrestrial
Effects.................................................................
............................................17

III. RISK
CHARACTERIZATION........................................................
...................................18

	A.  RISKS TO NON-TARGET AQUATIC ORGANISMS AND
PLANTS.....................18

	B.  RISKS TO NON-TARGET TERRESTRIAL ANIMALS AND
PLANTS.................19

	C.  RISK
DESCRIPTION.............................................................
........................................21

		1.  Risks to Non-target Aquatic Organisms and
Plants......................................................21

			a. Fish and Aquatic
Invertebrates...........................................................
...................21

			b. Aquatic-phase
Amphibians..............................................................
.......................22

			c. Aquatic
Plants..................................................................
.........................................22

		2.  Risks to Non-target Terrestrial Animals and
Plants.....................................................22

			a.
Birds...................................................................
........................................................23

			b. Terrestrial-phase Amphibians and
Reptiles..........................................................25

			c.
Mammals.................................................................
..................................................26

			d. Beneficial
Insects.................................................................
.....................................26

			e. Terrestrial
Plants..................................................................
....................................26

		3.  Review of Incident
Data....................................................................
...............................26

		4.  Endocrine
Effect..................................................................
....................................27

		5.  Federally Threatened and Endangered (Listed) Species
Concerns.............................27

			a. Action
Area....................................................................
...........................................27

			b. Taxonomic Groups Potentially at
Risk..................................................................28

			c. Indirect Effect
Analysis................................................................
............................29

			d. Critical
Habitat.................................................................
.......................................30

			e. Direct Effect Co-occurrence
Analysis................................................................
.....30

			f. Indirect Effect Co-occurrence
Analysis................................................................
..31

D.  ASSUMPTIONS, UNCERTAINTIES, STRENGTHS AND LIMITATIONS OF THE
NAPHTHALENE
ASSESSMENT..............................................................
..........33

IV.	 LITERATURE
CITED...................................................................
.....................................37

Appendices

Appendix A.  Environmental Fate Studies

Appendix B.  Names and Chemical Structures of Naphthalene and Major
Transformation                                     		  Products

Appendix C.  Aquatic Exposure Model and Results (GENEEC2 ver. 2.0)

Appendix D.  Terrestrial Birds and Mammals Exposure Model and Results
(TREX ver. 1.3.1)

Appendix E.  Ecological Effects Studies

Appendix F.  Environmental Fate and Ecotoxicity Bibliography 

Appendix G.  Direct Effects Endangered Species Analysis for Non-Crop
Uses 

Appendix H.  Indirect Effects Endangered Species Analysis for Non-Crop
Uses 

Tables

Table I-1. Chemical Identification for the Active Ingredient Naphthalene

Table I-2. Overview of Naphthalene Outdoor Uses

Table I-3. Taxonomic Groups and Test Species Evaluated for Ecological
Effects in the Screening Level Risk Assessment for Naphthalene.

Table I-4. Summary of Assessment and Measurement Endpoints for
Naphthalene as a Non-Food Use

Table II-1. Naphthalene Application Information

Table II-2. Summary of GENEEC2 Environmental Fate Data Used for Aquatic
Exposure Inputs for Naphthalene

Table II-3. Results of GENEEC2 Modeling for Naphthalene Use on
Ornamentals

Table II-4. Input Parameters for T-REX Analysis

Table II-5. Terrestrial EECs (mg ai/ft2) on Avian and Mammalian Exposed
to Granules Following Label-specified Application of Naphthalene at 10.8
lb ai/A; Determined using the TREX model.

Table II-6. Terrestrial EECs (mg ai/ft2) on Avian and Mammalian Exposed
to Granules Following Label-specified Application of Naphthalene at 10.8
lb ai/A; Determined using the TREX model.

Table II-7. Toxicity of Naphthalene to Aquatic Organisms and Plants

Table II-8. Toxicity of Naphthalene to Terrestrial Animals and Plants

Table III-1. Risks to Aquatic Animals and Plants for Naphthalene Use on
Ornamentals; 6 applications, 60 days apart at a rate of 10.8 lbs a.i./A

Table III-2. Granular RQs (LD50/ft2) from Direct Ingestion of Flakes at
10.8 lb ai/A - EEC/Toxicity (adjusted mg/ft2 / adjusted LD50)

Table III-3. Granular RQs (LD50/ft2) from Direct Ingestion of Flakes at
10.8 lb ai/A - EEC/Toxicity (adjusted mg/ft2 / adjusted LD50)

Table III-4. Table III-6.  Comparison of Avian Acute Toxicity Values
with Predicted EECs on Granule Consumption

Table III-5.  Estimates of the Number of Granules, and Minimum Foraged
Area Needed for a 20g, 100g, and 1000g Bird to Achieve the EEC that
would Trigger an Exceedance of the Adjusted LD50, Acute Risk LOC (0.5),
and Endangered Species Risk (0.5) Levels of Concern (LOCs) Based on an
Application Rate of 10.8 lb/A

Table III-6.  Estimates of the Number of Granules, and Minimum Foraged
Area Needed for a 20g, 100g, and 1000g Bird to Achieve the EEC that
would Trigger an Exceedance of the Adjusted LD50, Acute Risk LOC (0.5),
and Endangered Species Risk (0.5) Levels of Concern (LOCs) Based on an
Application Rate of 0.56 lb/A

Table III-7. Probit Dose Response Relationship Analysis

Table III-8. Number of Listed Species Located in Non-Food Areas in the
United States of America

Table III-9.  Listed Taxonomic Groups Potentially at Risk Associated
with Direct or Indirect Effects due to Applications of Naphthalene on
Areas where Ornamental Plants, Flowering Beds and Gardens are Grown
Nationwide.

I.  PROBLEM FORMULATION

The purpose of this ecological risk assessment (ERA) is to assist the
Agency in evaluating the actions needed, if any, to address the
ecological risks in terrestrial and aquatic environmental settings
associated with the reregistration of the repellent, the active
ingredient, naphthalene, that is used to repel animals from ornamental
plants, gardens and the perimeters of buildings. 

	A.  Stressor Source and Distribution

The primary chemical stressor is naphthalene, formulated to repel
snakes, mammals, and birds from ornamental plants, gardens, and the
perimeters of structural buildings. Naphthalene (not to be confused with
  HYPERLINK "http://en.wikipedia.org/wiki/Naphtha" \o "Naphtha"  naphtha
) (also known as naphthalin, naphthaline, tar camphor, white tar,
albocarbon, or naphthene), is a crystalline,   HYPERLINK
"http://en.wikipedia.org/wiki/Aromaticity" \o "Aromaticity"  aromatic ,
white, solid   HYPERLINK "http://en.wikipedia.org/wiki/Hydrocarbon" \o
"Hydrocarbon"  hydrocarbon , best known as the primary ingredient of  
HYPERLINK "http://en.wikipedia.org/wiki/Mothball" \o "Mothball" 
mothballs . Naphthalene is volatile, forming a flammable   HYPERLINK
"http://en.wikipedia.org/wiki/Vapor" \o "Vapor"  vapor . Its   HYPERLINK
"http://en.wikipedia.org/wiki/Molecule" \o "Molecule"  molecules 
consist of two fused   HYPERLINK "http://en.wikipedia.org/wiki/Benzene"
\o "Benzene"  benzene  rings. It is manufactured from   HYPERLINK
"http://en.wikipedia.org/wiki/Coal_tar" \o "Coal tar"  coal tar , and
converted to   HYPERLINK
"http://en.wikipedia.org/wiki/Phthalic_anhydride" \o "Phthalic
anhydride"  phthalic anhydride  for the manufacture of   HYPERLINK
"http://en.wikipedia.org/wiki/Plastic" \o "Plastic"  plastics ,  
HYPERLINK "http://en.wikipedia.org/wiki/Dye" \o "Dye"  dyes  and  
HYPERLINK "http://en.wikipedia.org/wiki/Solvent" \o "Solvent"  solvents
. It is also used as an   HYPERLINK
"http://en.wikipedia.org/wiki/Antiseptic" \o "Antiseptic"  antiseptic 
and   HYPERLINK "http://en.wikipedia.org/wiki/Insecticide" \o
"Insecticide"  insecticide , especially in mothballs (for indoor uses)
and flakes (for outdoor uses). Naphthalene (C10H8) is known among
polycyclic aromatic hydrocarbon class of chemicals as a “benzenoid” 
 HYPERLINK
"http://en.wikipedia.org/wiki/Polycyclic_aromatic_hydrocarbon" \o
"Polycyclic aromatic hydrocarbon"  polycyclic aromatic hydrocarbon 
(PAH), an alternant PAH., 

Mode of Action 

The toxicological mode of action of naphthalene is poorly understood;
however, published literature indicates that exposure to naphthalene may
induce cataracts, histological changes associated with pneumotoxicity,
glutathione depletion, lipid peroxidation, DNA fragmentation and the
production of the active oxygen species as superoxide anion and hydroxyl
radical.  Toxic manifestations of naphthalene are associated with its
oxidative metabolism to various products including quinones,
specifically the naphthoquinone metabolite. The ability to protect
against the toxic effects of naphthalene by using various antioxidants
and free radical scavengers has been demonstrated.  

The repellent mode of action of naphthalene is to keep unwanted animals
away from visiting the areas of interest.  It is unclear if it is the
odor of the volatilizing naphthalene that repels the organisms.

Chemical Identification of Naphthalene

Table I-1 presents the names and codes used to identify naphthalene in
this assessment.



 



Overview of Pesticide Usage

The proposed end-use products for terrestrial non-crop and domestic
outdoor uses are “ENOZ® Skat!”, “Snake-A-Way”, “Shotgun®
Rabbit & Dog Repellent” and “Bat-A-Way Bird, Squirrel, Rabbit & Bat
Repellent” with naphthalene as the active ingredient in white solid
crystals/flakes. The proposed uses are summarized in Table I-2. The
products are labeled as a repellent for rabbits, rattlesnakes (Genus
crotalus), checkered garter (Thamnophis marcianus), house mice (Mus
musclus), Norway rats (Rattus norvegicua), roof rats (R. rattus), tree
squirrels, bats, starlings, pigeons, and/or house sparrows from
ornamentals, gardens, planting beds and areas around buildings. 

Table I-2. Overview of Naphthalene Outdoor Uses

Use grouping	Representative Use

Terrestrial Non-food + Domestic Outdoor (residential)	Areas around
houses, cabins, trailers, garages, utility houses, barns, woodpiles,
sand piles, trash cans, flower beds, plants (ornamentals, roses, spring
bulbs), around the periphery of gardens, garbage bags placed near
residences and other buildings, streets or alleys for garbage
collection. 



The labels state that the products may be applied as bands around the
plants or periphery of gardens and buildings to reduce the frequency of
visits by animals. However, the bandwidth of the bands is dependant on
the product formulation and label statements. The four products
identified above are for terrestrial non-crop or domestic outdoor uses
only, even though there are other naphthalene products for indoor uses.
The proposed application rates range from a maximum of 10.8 lbs/acre to
a minimum of 0.56 lbs/acre for naphthalene uses on terrestrial non-food
or domestic outdoor sites, with up to six applications per year with
60-day reapplication intervals. 

Receptors

For the screening level risk assessment on naphthalene and its
transformation products, toxicological data generated on representative
test species belonging to broad taxonomic groups are summarized, then
utilized in an assessment of risk for each group. These data are
obtained from registrant-submitted studies and published literature.
Table I-3 lists the taxonomic groups and representative test species
used for evaluation of potential ecological effects on terrestrial
non-food and domestic outdoor uses. Within each of these very broad
taxonomic groups, an acute endpoint is selected from the available
toxicity data for use in risk estimation. 

Table I-3.  Taxonomic Groups and Test Species Evaluated for Ecological
Effects in the Screening Level Risk Assessment for Naphthalene.



Taxonomic group	

Example(s) of representative species



Birds, Terrestrial-phase Amphibians and Reptilesa	

Mallard duck (Anas platyrhynchos)

Bobwhite quail (Colinus virginianus)



Mammals	

Laboratory rat (Rattus norvegicus)



Freshwater fish and Aquatic-phase Amphibiansb	

Bluegill sunfish (Lepomis macrochirus)

Rainbow trout (Oncorhynchus mykiss)

Coho salmon (Oncorhynchus kisutch)



Freshwater invertebrates	

Water flea (Daphnia magna)

Estuarine/marine fish	Fathead minnow (Pimephales promelas)

Estuarine/marine invertebrates	Pacific oyster (Crassostrea gigas)

Grass shrimp (Palaemonetes pugio)



Terrestrial plantsc	

Monocots – No data

Dicots – No data



Aquatic vascular plants 

Aquatic non-vascular plants	

Duckweed – No data

Green algae (Chlorella vulgaris)



aBirds are used as surrogates for amphibians (terrestrial phase) and
reptiles.

bFreshwater fish are used as surrogates for amphibians (aquatic phase).

cFour species of two families of monocots, of which one is corn; six
species of at least four dicot families, of which one is soybeans.



No ecological effects data on terrestrial and aquatic vascular plants,
or honeybees are available. The potential risks to terrestrial and
aquatic vascular plants, and honeybees from exposure to naphthalene are
unknown. 

A complete discussion of all toxicity data available for this risk
assessment and the resulting measurement endpoints selected for each
taxonomic group are included in the Ecological Effects Characterization
section and Appendix E. 

Aquatic Effects:

For naphthalene, effects on aquatic organisms are estimated from acute
laboratory studies either submitted to the Agency or found in the open
literature (i.e., ECOTOX). Acute data are available for freshwater fish,
rainbow trout (Oncorhynchus mykiss) and bluegill sunfish (Lepomis
macrochirus); freshwater invertebrates, water flea (Daphnia magna);
estuarine/marine fish, Fathead minnow (Pimephales promelas); and
estuarine/marine invertebrates, Pacific oyster (Crassostrea gigas) and
Grass shrimp (Palemonetes pugio). These freshwater fish species also act
as surrogates for aquatic-phase amphibians. Data is available for
aquatic non vascular plants with one green algae species (Chlorella
vulgaris). None is available for aquatic vascular plants.

Data were available to evaluate chronic effects of naphthalene on
aquatic animals are an Early Life-Stage study with Coho salmon
(Oncorhynchus kisutch) and Fathead minnow embryo-larval test to observe
the chronic effect to freshwater and marine/estuarine fish. 

Terrestrial Effects:

The effect of naphthalene on birds is estimated from acute and subacute
studies on the upland game bird, northern bobwhite quail (Colinus
virginianus). No studies are available for waterfowl. The bird studies
also act as surrogates for reptiles and terrestrial-phase amphibians.
Effects on mammals are estimated from acute data in rats reviewed by the
Health Effects Division (HED) and effects on mammals from chronic data
in rats from available open literature data. 

Ecosystem at Risk

The terrestrial ecosystems potentially at risk include the treated area
where the granules are applied in bands. For Tier I assessment purposes,
risk will be assessed to terrestrial animals assumed to exclusively
occur in the treated area directly exposed to naphthalene granules. 

The use of naphthalene, as stated in the proposed label, could result in
exposure to aquatic and terrestrial animals inhabiting flowing,
non-flowing or transient freshwater water bodies. For Tier I assessment
purposes, risk will be assessed to aquatic animals assumed to occur in
small, static ponds receiving runoff from adjacent treated areas. 

Assessment Endpoints

A summary of the assessment and measurement endpoints selected to
characterize potential ecological risks associated with exposure to
naphthalene is provided in Table I-4.

This ecological risk assessment considers the labeled maximum and
minimum application rates, maximum number of applications and minimum
reapplication intervals between applications for representative uses to
estimate exposure concentrations. This assessment is not intended to
represent a site or a time-specified analysis. Instead, this assessment
is intended to represent high-end exposures at a national level.
Likewise, the most sensitive toxicity endpoints are used from surrogate
test species to estimate treatment-related direct effects on acute
mortality/immobilization assessment endpoints. Toxicity tests are
intended to determine effects of outdoor use exposure on birds,
terrestrial-phase amphibians, reptiles, mammals, fish, aquatic-phase
amphibians, aquatic invertebrates, and plants. These tests include
short-term acute and subacute studies and are typically arranged in a
hierarchical or tiered system that progresses from basic laboratory
tests to applied field studies. The toxicity studies are used to
evaluate the potential of a pesticide to cause adverse effects, to
determine whether further testing is required, and to determine the need
for precautionary label statements to minimize the potential adverse
effects to non-target animals and plants  (40 CFR 158.202, 2002).

Table I-4.  Summary of Assessment and Measurement Endpoints for
Naphthalene as a Non-Food Use



Assessment Endpoint	

Measures of Effect



1.  Abundance (i.e., survival) of birds.   Birds are surrogate for
reptiles and terrestrial phase amphibians.	

1a. Bobwhite quail acute oral LD50.

1b. Bobwhite quail subacute dietary LC50.

1c. Mallard duck subacute dietary LC50.*

1d. Avian reproduction NOAEC*

* Currently, no subacute dietary toxicity study with mallard ducks or a
reproduction study have been submitted for naphthalene or found in open
literature. 



2.  Abundance (i.e., survival) of mammals.	

2a. Laboratory rat acute oral LD50.



3.  Survival and reproduction of individuals and communities of
freshwater fish and invertebrates.  Fish are surrogate for aquatic phase
amphibians.	

3a. Rainbow trout, bluegill sunfish acute LC50.

3b. Coho salmon chronic (early-life) NOAEC. 

3c. Water flea acute EC50.



4. Survival and reproduction of individuals and communities of
estuarine/marine fish and invertebrates.	4a. Fathead minnow acute LC50.

4b. Pacific oyster and Grass shrimp acute EC50.

4c. Fathead minnow chronic NOAEC.



5.  Perpetuation of individuals and populations of non-target
terrestrial and semi-aquatic species (crops and non-crop plant species).


5a. Monocot and dicot seedling emergence and vegetative vigor endpoints
are not available.*

*Currently, no Tier I terrestrial plants toxicity studies have been
submitted or found in open literature for naphthalene.



6.  Survival of beneficial insect populations.	

6a. Honeybee acute contact LD50 is not available.*

*Currently, no honeybee toxicity study has been submitted or found in
open literature.



7.  Maintenance and growth of individuals and populations of aquatic
plants from standing crop or biomass.	

7a. Alga EC50 and NOAEC values

7b. Vascular plant (i.e., duckweed) EC50 and NOAEC values for growth
rate and biomass measurements are not available.*

*Currently, no Tier I aquatic vascular plant toxicity studies have been
submitted or found in open literature.



LD50 = Lethal dose to 50% of the test population.

NOAEC = No-observed-adverse-effect concentration.

LOAEC = Lowest-observed-adverse-effect concentration.

LC50 = Lethal concentration to 50% of the test population.

EC50/EC25 = Effect concentration to 50/25% of the test population.



Conceptual Model

Naphthalene is insoluble and has high potential to volatilize from soil,
so exposure from inhalation is possible. Potentially, soil particulates
containing naphthalene could be transported away from the treatment site
by wind erosion. Naphthalene is not likely to leach to groundwater due
to this use pattern but is expected to be transported via runoff to
surface water bodies.  The low Koc would suggest that naphthalene could
leach to groundwater.  However, for this assessment groundwater is not
considered as a major route of exposure for aquatic organisms.  This
assumption is supported by the fact that in the USGS NAWQA groundwater
data, a total of 6,977 groundwater samples were analyzed for naphthalene
with only 37 positive detections, suggesting that leaching is not likely
significant.  Modeling with the SciGrow groundwater model suggests
estimated concentrations are below those estimated for surface water and
below those seen in the USGS NAWQA data.  Naphthalene does not
bioaccumulate in aquatic animals. With limited data available for
naphthalene, only potential risks from exposure to parent naphthalene
were quantified. It is uncertain if the transformation products are of
toxicological concern. 

The initial emphasis of the risk assessment primarily addresses possible
risks to aquatic vascular and non-vascular plants, fish, aquatic-phase
amphibians and invertebrates and to terrestrial non-target plants,
birds, reptiles, terrestrial-phase amphibians and mammals. Risk was
evaluated for exposure of these organisms to naphthalene through
ingestion of granules and water bodies receiving runoff following
application. 

Risk Hypothesis

The use of naphthalene as a repellent in terrestrial non-crop and
domestic outdoor sites will result in either direct or indirect adverse
effects to terrestrial and aquatic animals and plants. Based on the
information, persistence, mode of action, direct toxicity and potential
indirect effects, EFED assumes that naphthalene has the potential to
cause reduced survival, and growth and reproduction impairment to both
terrestrial and aquatic animals and plants as a result of the labeled
uses of the pesticides. 

Conceptual Model Diagram

 

		

	E.  Analysis Plan

Naphthalene is registered for use as an insect, invertebrate and mammal
repellent for both indoor and outdoor uses.  Naphthalene has a number of
non-pesticidal uses (principally as a constituent of various petroleum
products), which are not considered in this assessment.  Indoor
pesticidal uses are principally as mothballs and are not considered
likely to result in exposure to non-target organisms (other than humans)
and are therefore not considered in the ecological risk assessment. 
Currently, four registered products included outdoor uses for treatment
of ornamentals, planting beds, and gardens to repel animals. Outdoor
pesticidal uses are principally as flakes or crystals. Information on
application and on the extent of expected outdoor use was provided at
the registrant SMART meeting on March 28, 2007.  Based on this
information the exposure assessment will consider two exposure
scenarios.  The first is a high use rate at 10.8 lbs/acre with six
applications per year for repelling rabbits and dogs.  The second is a
low use rate scenario with an application rate of 0.56 lbs/acre with six
applications per year for repelling snakes.  Aquatic exposure estimates
were generated for each scenario using the Tier I exposure model,
GENEEC2, which assumes an area is 100% treated.  

Given the limited use of this compound and the fact that it is applied
in a band around ornamentals, planting beds and gardens as a repellent,
an adjustment to the modeled EEC was made.  The percent of lot treated
was derived from the United States 2000 Census data
[http://www.census.gov/main/www/cen2000.html], which indicated that a
typical lot size is ¼ acre (10,890 square feet) with a typical house
having a footprint of 1000 square feet.  If it is assumed that the house
is symmetrical, then the perimeter would be 126.4 ft (31.6 ft on each
side).  If it is further assumed that the ornamental beds will be
present in a 10 foot band around the house, then the perimeter would be
206.4 ft.  If a typical application band is 1 foot (12 inches), then the
treated area would be 206.4 square feet.  If it is additionally assumed
that a garden will typically be present, then an additional calculation
was made to account for the potential treatment to the perimeter of the
garden.  In this case, it is assumed that a garden would be 20 feet by
100 feet for a perimeter of 240 feet.  An assumption of a one-foot band
of naphthalene around this garden yields a total treated area of 240
square feet.  Adding these together and dividing by the total ¼ acre
lot area yields a percent lot treated of 4.1%.  The resultant GENEEC2
has been adjusted by this factor.  

Ecological risk will be assessed to determine the potential for acute
effects (i.e., lethality) to mammals, birds, fish or invertebrates using
screening-level risk assessment models.  Risk will be assessed on the
treated site for birds and mammals and in an adjacent pond for
freshwater fish and invertebrates.  Ecotoxicity data on sublethal (e.g.,
reproductive, growth) effects were not available, so chronic risk is not
addressed in this assessment.

Risk to aquatic animals will be assessed using GENEEC2, a Tier 1 model
that estimates concentrations in a 1-hectare, 2-meter-deep water body
adjacent to the 10-hectare treated site that drains into the water body.
 Since granular applications are assumed, this water body is also
assumed to receive no drift from the treated site. 

Terrestrial exposures from granular applications (mg ai/square foot) for
birds, terrestrial-phase amphibians, reptiles and mammals will be
estimated using the Tier 1 model, T-REX Version 1.3.1 (T-REX, 2007). In
addition, a banded granular application assumes that 100% of the
granules are unincorporated on the ground. Risk to terrestrial animals
from exposure to granules will be based on LD50/ft2 values. The LD50/ft2
values are calculated using a toxicity value (adjusted LD50 of the
assessed animal and its weight classes) and the EEC (mg ai/ft2) and are
directly compared with Agency’s levels of concern (LOCs). Since
naphthalene is used only for granular applications, exposures to animals
from foraging on food items with naphthalene residues (short and tall
grass, broadleaves, seeds) are not estimated in this assessment. Details
of the TREX model and EEC/RQ calculations are presented in Appendix D. 

	F.  Data Gaps  

For environmental fate there are no acceptable fate studies.  However, a
single supplemental study has been provided which summarizes open
literature data on adsorption/desorption and aerobic soil metabolism
data.  Other fate parameters needed to conduct this assessment have
either been extrapolated from the open literature data (aerobic aquatic
metabolism half life) or conservatively assumed to be stable (photolysis
and hydrolysis).  The lack of these data provides uncertainty to this
assessment (Table I-5).  Elimination of this uncertainty would require
submission of additional data for these fate processes. 

Table I-5. Environmental Fate Data Requirements for Naphthalene



Guideline  #	

Data Gap	

Value of Additional Testing



162-1	

Aerobic Soil Metabolism	Low.  Supplemental data from open literature. 
Model assumptions were based on these supplemental data.  Submission of
acceptable data can provide for confirmation of assumptions or inputs
for refined modeling.



163-1	

Adsorption Desorption	Low.  Supplemental data from open literature. 
Model assumptions were based on these supplemental data.  Submission of
acceptable data can provide for confirmation of assumptions or inputs
for refined modeling.



162-4	

Aerobic Aquatic Metabolism	Medium.  Lack of date led to assumption of
half life at two times the aerobic soil metabolism value.  Submission of
data can remove uncertainty in this assumption.



Several ecotoxicity data gaps for naphthalene were also identified
during problem formulation (Table I-6).

Table I-6. Ecological Toxicity Data Requirements for Naphthalene

Guideline #	Data Gap	Value of Additional Testing

71-2	Avian subacute dietary LC50

(mallard duck)	High – No study with mallard duck is available. Study
is required to evaluate the toxicity to waterfowl.  In the dietary study
with upland game bird (bobwhite quail), body weight decreased while feed
consumption increased when compared to controls. 

122-1	Tier I Nontarget Terrestrial Plant Phytotoxicity: Seedling
emergence and Vegetative vigor 	Low to Medium – No studies are
available. Since the product labels state specifically for terrestrial
non-crop/domestic outdoor uses, “Do not apply the product directly to
foliage or stems,” this statement indicates that there is a
possibility of phytotoxicity; in addition, summary reviews of open
literature data indicate naphthalene is phytotoxic to plants. If plants
are sensitive to naphthalene, there might be direct effects to plants
and possible indirect effects to animal taxa due to loss of cover or
food sources. The likelihood for risks to plants is low but cannot be
precluded at this time.

122-2	Tier I Nontarget Aquatic Plant Growth	Low to Medium - No studies
are available. Since the product labels state specifically for
terrestrial non-crop/domestic outdoor uses, “Do not apply the product
directly to foliage or stems,” this statement indicates that there is
a possibility of phytotoxicity; in addition, summary reviews of open
literature data indicate naphthalene is phytotoxic to plants. If plants
are sensitive to naphthalene, there might be direct effects to plants
and possible indirect effects to animal taxa due to loss of cover or
food sources. The likelihood for risks to plants is low but cannot be
precluded at this time.

141-1	Acute honey bee contact LD50	Low – No study is available. It is
uncertain how pollinators will react to naphthalene when actively
visiting gardens and flowers where naphthalene is applied frequently.
Also, since naphthalene is volatile, it is uncertain how naphthalene
fumes will impact honeybees. If honeybees are sensitive to naphthalene,
there might be indirect effects to plants due to loss of pollinators.
The likelihood for risks to honeybees is low but cannot be precluded at
this time. 

 

II. ANALYSIS  

Use Characterization

Information provided by the registrant indicates that a significant
proportion of naphthalene use is on ornamentals, planting beds, and
gardens.  Generally, naphthalene is applied for outdoor use as flakes in
bands surrounding the site to be protected.  Typically, these bands do
not exceed 12 inches in width and are replenished as needed (typically,
every two to three months).  The use patterns assessed in the exposure
assessment are summarized in Table II-1.

Table II-1 Naphthalene Application Information A

Crop	Formulation	Method of Application	Maximum Application Rate

(lbs/acre)	Maximum Seasonal Rate	Minimum Application Interval 

Ornamentals for rabbit & dog repellent	Granules	Ground	10.8	64.8	2
months

Ornamentals for snake repellent	Granules	Ground	0.56	3.36	2 months

A Based on information provided at SMART Meeting on March 28, 2007

B.  Exposure Characterization

1.  Environmental Fate and Transport 

Several environmental fate studies (aerobic soil and aqueous photolysis)
were submitted but deemed to be unacceptable for risk assessment
purposes due to poor material balances, inadequate sample intervals, and
issues with volatile trapping and therefore have not been used in this
assessment.  A single overview of open literature data (MRID 45346801)
provided supplemental data on the adsorption/desorption and aerobic soil
metabolism properties of naphthalene.  Possible degradation processes
affecting naphthalene (and PAH’s in general) include photo-oxidation
and microbial degradation.  

For sorption a total of 13 open literature studies were submitted and
summarized and indicated that the solubility of naphthalene ranged from
30 to 31.7 mg/L and that the Koc ranged from 200 to 1470 for a variety
of soils from North America, Europe and China. The study author
concluded from this review that naphthalene was bound relatively rapidly
to soils with a sustained desorption over days to weeks.  For
biodegradation a total of 15 open literature studies were submitted and
reviewed and found that naphthalene degraded with aerobic soil
metabolism half-lives between 3.5 and 40 days with no appreciable
degradation under anaerobic conditions.  Possible dissipation processes
affecting naphthalene (and PAH’s in general) include volatilization,
bioaccumulation, adsorption, and leaching.  

Additional open literature data (US NPS, 1997, US HHS, 2005) describes
both aerobic soil degradation and adsorption values that are consistent
with values described above, although under certain conditions
degradation from soil may be somewhat longer.  In addition, these data
suggest that naphthalene degrades rapidly by aqueous photolysis.  The
data (US HHS, 2005) also suggest that under certain conditions
naphthalene dissipates rapidly from open water systems although it is
unclear whether the dissipation observed was due to degradation or
lumped dissipation processes including transport out of the systems by
flowing water.  The additional data suggest that up to 30% of loss from
soil can occur due to volatilization and also suggest that once in air,
naphthalene should degrade rapidly (US NPS, 1997).  Once in air,
naphthalene tends to dissipate rapidly (US HHS, 2005).  Finally, these
data suggest that naphthalene is relatively stable under anaerobic
conditions (US NPS, 1997).

A number of transformation products were identified in the various open
literature studies.  The study author proposed a degradation pathway for
naphthalene, which ultimately resulted in catechol.  Transitional
transformation products included
cis-1,2-dihydroxy-1,2-dihydronapthalene, 1,2-dihydroxy-napthalene,
2-hydroxchromene-2-carboxylate (HCCA),
trans-o-hydroxy-benzylidenpyruvate (tHBPA), salicyladehyde, and
salicylate.  There are no registrant submitted environmental fate data
on these degradation products that would allow for an approximation of
environmental fate inputs, the available open literature data is sparse,
and there is no available toxicity data for these compounds.  Therefore,
these degradates have not been quantitatively assessed in the exposure
assessment.

A copy of the submitted summary along with the metabolic pathway,
transformation product structures, results from individual studies, and
bibliography of open literature data is presented in Appendix G.

		2.  Aquatic Exposure Modeling

EFED normally relies on an integrated approach for conducting exposure
assessments that relies on an analysis of both monitoring data and
modeling.  In the case of naphthalene, no monitoring data are available.
 Therefore, this assessment relies solely on modeling.     

EFED uses a tiered system of pesticide exposure modeling to assess risk
of a pesticide to the environment.  Each of the tiers is designed to
screen out pesticides by requiring higher, more complex levels of
investigation only for those that have not passed the next lower tier. 
In this case, EFED has conducted a Tier I aquatic exposure assessment
relying on GENEEC2.  GENEEC (GENeric Estimated Environmental
Concentration, version 2) is a program to calculate acute as well as
longer-term estimated environmental concentration (EEC) values. It
considers reduction in dissolved pesticide concentration due to
adsorption of pesticide to soil or sediment, incorporation, degradation
in soil before washoff to a water body, direct deposition of spray drift
into the water body, and degradation of the pesticide within the water
body. 

  SEQ CHAPTER \h \r 1   SEQ CHAPTER \h \r 1 The appropriate GENEEC2
input parameters were selected from the environmental fate data
submitted by the registrant and in accordance with US EPA-OPP EFED water
model parameter selection guidelines, Guidance for Selecting Input
Parameters in Modeling the Environmental Fate and Transport of
Pesticides, Version 2.3, February 28, 2002.  These parameters are
summarized in Table II-2.  Results of GENEEC2 modeling are presented in
Table II-3 and Appendix C.  



Table II-2 Summary of GENEEC2 environmental fate data used for aquatic
exposure inputs for naphthalene

Fate Property	Value	MRID (or source)

Solubility in Water	32 mg/L	Product Chemistry

Photolysis in Water	stable	Assumed

Aerobic Soil Metabolism Half-lives	32.6 days (90th % of 9 values)	MRID
45346801

Hydrolysis	stable	Assumed

Aerobic Aquatic Metabolism (water column)	65.2 days 	Twice the aerobic
soil metabolism rate constant

Koc	131 (lowest non-sand Koc)	MRID 45346801

Application Efficiency	99 % for ground*	default value

Spray Drift Fraction	1 % for ground	default value

* – Although not specified on labels it is assumed that only ground
applications would be used.

Two scenarios were modeled to represent a high naphthalene use scenario
and at low use scenarios.  The high use scenario was modeled at 10.8
lbs/acre with six applications per year, while the low use scenario was
modeled at 0.56 lbs/acre with six applications per year.  The
application method was modeled as ground application with a granular
formulation.  The results of the Tier I modeling is summarized in Table
II-3.  

Table II-3  Results of GENEEC2 Modeling for Naphthalene Use on
Ornamentals*

Use Site	Application Rate (lbs/acre)	Number of Applications

(interval)	Peak EEC (ppb)	4 day EEC (ppb)	21 day EEC (ppb)	60-day EEC
(ppb)	90-day EEC (ppb)

Ornamentals for rabbit & dog repellent	10.8	6

(2 months)	26.9	26.6	25.2	22.4	20.5

Ornamentals for snake repellent	0.56	6

(2 months)	1.4	1.4	1.3	1.2	1.1

* Note these EECs are adjusted by 4.1% to account for the fact that the
product is only applied in a band around ornamental, planting beds, and
gardens

Unaccounted for in this exposure assessment is the fact that naphthalene
is volatile.  No product chemistry data were available but an estimate
of the vapor pressure was made using EpiSuite.  EpiSuite reported an
experimentally derived value for vapor pressure of 8.5 x10-2 mm Hg
(which is consistent with the registrant reported value of 10.5 Pa, or
7.8 x 10-2 mm Hg) suggesting that naphthalene is volatile.  Given the
volatility of this compound and the fact that the Tier I model used to
estimate exposure does not account for volatility as a route of
dissipation it is likely that the exposure estimates derived above are
over-predictions of potential exposure.  However, it is unknown from the
open literature data used in this assessment whether the systems were
closed or flow-through.  If the aerobic metabolism data (and hence the
half-life used in this assessment) were flow-through, then the
degradation reported would include volatilization as a process.  The
impact of volatility on this assessment is uncertain. 

Given the mobile nature of this compound, it is possible that
naphthalene may leach to groundwater.  A cursory review of USGS NAWQA
groundwater data indicates that of 6,977 samples only 37 detections of
naphthalene were found.  While the maximum concentration detected was 70
ppb, there are a number of possible sources of naphthalene contamination
of groundwater, including many with significantly higher use (e.g.,
industrial, jet fuel).  Thus it appears that leaching is not likely a
significant route of exposure for the pesticidal use of naphthalene.  A
quick check of groundwater leaching potential using SciGrow yields an
estimated concentration in groundwater of 16.3 ppb at the highest
application rate (10.8 lbs/acre x 6 applications) and 0.84 ppb at the
lowest rate (0.56 lbs/acre x 6 applications).  These values are below
the surface water concentrations predicted by GENEEC2, are lower than
the NAWQA values described above, and assume a much broader area of
application than anticipated for this use pattern (bands surrounding
gardens and planting beds).  Given the lines of evidence described, it
is expected that as an exposure route for ecological risk assessment
,naphthalene in groundwater resulting from pesticidal use is minimal.  

		3. Terrestrial Exposure Modeling

Naphthalene when applied outdoors is formulated as a granular
formulation, technically as flakes or crystals. For T-REX modeling,
granules are used as a surrogate for flakes or crystals.  

Terrestrial exposures for naphthalene are estimated using the conceptual
approach given in the Tier-1 model, T-REX Version 1.3.1.  A default
foliar half-life of 35 days was assumed. The LD50/ft2 is used to
estimate risk for granular formulations through row and banded
applications.      SEQ CHAPTER \h \r 1   SEQ CHAPTER \h \r 1 The
appropriate T-REX input parameters were selected from the product
labels. For the method of application using granules (flakes), one row
length of 209 ft with row spacing of 2,500 inches, 1-foot bandwidth and
0% incorporation was assumed. For minimum foraging area estimates need
to exceed the levels of concerns, a maximum mass of 38 mg naphthalene
per flake is used. These parameters are summarized in Table II-4.  

Table II-4. Input Parameters for T-REX Analysis

Application Type	Formulation	Input	Guidance

	Comments

Rows/Band 	Granular	No. of Row, Length, and Spacing	Row spacing is the
amount of space (inches) between crop rows and is obtained from the
product label. 	Only one row was assumed. A minimum row length of 209
foot with row spacing of 2,500 inches was used assuming application
occurs on one side of an one-acre field. 



Band width	Bandwidth is the width of the applied pesticide row (inches)
and is obtained from the product label.  	A foot bandwidth was obtained
from labels. 



% incorporated	Value depends on the method of application:  

T-Banded – covered with specified amount of soil: 99% In-furrow,
drill, or shanked-in: 99%

Side-dress, banded, mix, or lightly incorporate with soil: 85%

Broadcast, mix, or lightly incorporated: 85%

Side-dress, banded, unincorporated: 0%

Broadcast, aerial broadcast, unincorporated: 0%	0% incorporated was
obtained from labels. 



Weight of granule	Data is obtained from registrant. 	38 mg (from SMART
meeting)



The T-REX model does not allow for multiple applications at different
rates so the terrestrial exposures for this risk assessment were
estimated assuming six ground applications at 10.8 lbs/acre with a
reapplication interval of 60 days. A second lower use rate scenario was
modeled assuming six ground applications at 0.56 lbs/acre. Results of
T-REX modeling are presented in Tables II-5 and II-6.  

Table II-5 Terrestrial EECs (mg ai/ft2) on avian and mammalian ingesting
granules following label-specified application of naphthalene at 10.8 lb
ai/A; determined using the TREX model

Intermediate Calculations

# rows acre-1:	1.00

row length (ft):	208.71

lb ai/1000 ft row:	51.65

bandwidth (ft):	1.00

mg ai/ft2 (EEC):	23429.24

exposed EEC (mg ai/ft2):	23429.24



Table II-6 Terrestrial EECs (mg ai/ft2) on avian and mammalian ingesting
granules following label-specified application of naphthalene at 0.56 lb
ai/A; determined using the TREX model

Intermediate Calculations

# rows acre-1:	1.00

row length (ft):	208.71

lb ai/1000 ft row:	51.65

bandwidth (ft):	1.00

mg ai/ft2 (EEC):	1214.85

exposed EEC (mg ai/ft2):	1214.85



	C.  Ecological Effects Characterization

Summaries of the available ecotoxicity studies can be found in Appendix
E.  

Following implementation of the Overview document (USEPA, 2004a), EFED
has begun incorporating data from open literature into ecological risk
assessments (USEPA, 2004b). Toxicity data from open literature are
identified via the ECOTOX search engine and maintained by EPA/ORD. Open
literature data presented in this risk assessment were obtained from the
data provided to EFED by ORD on 11/6/2006. In order to be included in
the ECOTOX database, papers must meet the following minimum criteria:

	1.	the toxic effects are related to a single chemical exposure;

	2.	the toxic effects are on an aquatic or terrestrial plant or animal
species;

	3.	there is a biological effect on live, whole organisms;

	4.	a concurrent environmental chemical concentration/dose or
application rate is 			reported; and

	5.	there is an explicit duration of exposure

Data that passes the ECOTOX screen is evaluated along with the
registrant-submitted data, and may be incorporated qualitatively or
quantitatively into the risk assessment. In general, effects data in the
open literature that are less than or more conservative than the
registrant-submitted data are considered. The degree to which open
literature data is quantitatively or qualitatively characterized is
dependent on whether the information is relevant to the assessment
endpoints (i.e., maintenance of survival, reproduction, and growth)
identified in the problem formulation. For example, endpoints such as
behavior modifications are likely to be qualitatively evaluated, because
it is unclear whether such modifications cause a reduction in species
survival, reproduction, and/or growth. Specific open literature data
that are considered include the following:

	1.	the endpoint is more sensitive than those identified in the
registrant data;

	2.	the data is for under represented taxa (i.e., amphibians); and

	3.	the data includes endpoints not normally evaluated in registrant
studies, but 			ecologically relevant

An examination of the studies found in the open literature (ECOTOX) did
not provide any lower endpoints than the studies submitted by the
Registrant; however, several open literature studies with other taxa
groups were available for this assessment. Acute studies with the
Fathead minnow, Pacific oyster, and Grass shrimp were available to
observe the effect of naphthalene to estuarine/marine fish and
invertebrates. A Freshwater Fish Early Life-Stage study with Coho salmon
and embryo-larval test with fathead minnow were available to observe the
effect to fish from long-term exposure. For toxicity effects to aquatic
plants, several green algae studies were available. Studies with soil
invertebrates were available to observe the effect to terrestrial
invertebrates. A summarized table of toxicity endpoints selected for
aquatic and terrestrial risk assessment can be found in Tables II-7 and
II-8, respectively.

 

1.  Aquatic Effects

With the exception of the Pacific oyster, available freshwater and
estuarine/marine fish and invertebrate acute toxicity data suggest that
naphthalene is moderately toxic to aquatic animals (Table II-7). Chronic
freshwater fish reproduction data indicates that survival and growth
were affected; the NOAEC was determined to be 0.37 mg/L. For
estuarine/marine fish, a chronic embryo-larval test indicates adverse
effects at 0.85 mg/L; the NOAEC was determined to be 0.62 mg/L. Aquatic
plant growth studies with green algae were less sensitive than animals
with concentrations of 33 and 34 mg/L, which categorizes naphthalene as
slight toxic to green alga.  No toxicity study with aquatic vascular
plants is available for this ecological risk assessment.  

Table II-7. Toxicity of Naphthalene to Aquatic Organisms and Plants tc
"Table #. Acute 96-hour toxicity of flumetsulam to freshwater animals "
\f D  

Taxon	Test Organism	Endpoint	Value*

(mg a.i./L)	Ecotoxicity Category	MRID

Classification

Freshwater Fish	Rainbow trout

Onchorhynchus mykiss	96-hr LC50

NOAEC (mortality)

NOAEC (sublethal)	2.0

0.86

0.86	moderately toxic	45030801

supplemental

	Bluegill sunfish

Lepomis macrochirus	96-hr LC50

NOAEC (mortality)

NOAEC (sublethal)	3.2

1.4

1.4	moderately toxic	44302701

acceptable

	Coho salmon

Oncorhynchus kisutch	40D NOAEC

40D LOAEC	0.37

0.67	None	127330

supplemental

Freshwater Invertebrate	Water flea

Daphnia magna	48-hr EC50

NOAEC (mortality)

NOAEC (sublethal)	1.6

0.48

>8.8	moderately toxic	44302702

acceptable

Estuarine/

marine 

Fish	Fathead minnow

Pimephales promelas	96-hr LC50

NOAEC (mortality)

NOAEC (sublethal)	6.6

NR

NR	moderately toxic	DeGraeve, et al. 1980



Chronic NOAEC

Chronic LOAEC	0.62

NR	None	DeGraeve, et al. 1980

Estuarine / 

marine

Invertebrates	Pacific oyster

Crassostrea gigas	96-hr EC50

NOAEC (mortality)

NOAEC (sublethal)	199

NR

NR	practically nontoxic	LeGore, 1974

	Grass shrimp

Palaemonetes pugio	96-hr LC50

NOAEC (mortality)

NOAEC (sublethal)	2.35

NR

NR	moderately toxic	Tatem, 1976

Vascular Plant	Duckweed

Lemna gibba	7-day EC50

NOAEC	No data	No data	No data

Non-vascular Plant	Green algae

Chlorella vulgaris	48-hr EC50

NOAEC         LOAEC	33

NR

NR	slightly toxic	Kauss & Hutchinson, 1975

*Bolded values indicate toxicity thresholds used to calculate risk
quotients.

NR – not reported

Available avian acute toxicity data suggest that naphthalene is
practically non-toxic to upland game bird species both on acute oral and
dietary basis (Table II-8). No subacute dietary study with the mallard
duck was available; consequently, it is unknown how toxic naphthalene is
to waterfowl species.  Naphthalene is practically non-toxic to mammals
on an acute oral basis. 

                        2. Terrestrial Effects 

 

Table II-8 Toxicity of Naphthalene to Terrestrial Animals and Plants tc
"Table #. Acute 96-hour toxicity of flumetsulam to freshwater animals "
\f D  

Taxon	Test Organism	Test Type	Endpoint	Valuea	Ecotoxicity Category	MRID
Classification

Bird	Bobwhite quail

Colinus virginianus	Acute Oral	LD50	2690 mg/kg bw	practically nontoxic
148176

acceptable



Subacute Dietary	LC50	>5620 mg/kg diet	practically nontoxic	148175

acceptable

	Mallard duck

Anas platyrhynchos	Subacute Dietary	LC50	No data	Not available	Not
available

Mammal	Rat

Rattus norvegicus	Acute Oral	LD50	2649 mg/kg bw	practically nontoxic
148174



Beneficial insects	Honey bee

Apis mellifera	Acute Contact	LD50	No data	Not available	Not available

Soil Invertebrates	Folsomia candida	Chronic Effects on Soil
Invertebrates (reproduction and survival)	NOAEC

LOAEC	88 µmol/kg soil

409 µmol/kg soil	None	S.T.J. Droge et al

	Enchytaeus crypticus

NOAEC

LOAEC	220 µmol/kg soil

2045 µmol/kg soil	None	S.T.J. Droge et al

Terrestrial plants	Monocots and dicots	Seedling emergence and Vegetative
vigor	EC25

NOAEC

LOAEC	No data	Not available	Not available

a Bolded values indicate toxicity thresholds used to calculate risk
quotients.

No terrestrial plant seedling emergence or vegetative vigor studies are
available for this ecological risk assessment.  However, the labels
state specifically, “Do not apply the product directly to foliage or
stems.”  This statement indicates that there is a possibility of
phytotoxicity and open literature data suggest naphthalene is
selectively phytotoxic to plants (Spencer, E. Y. Guide to the Chemicals
Used in Crop Protection, 7th edition, publication 1093).  Until
terrestrial plant studies are available, it is uncertain which plant
species is selectively affected when exposed to naphthalene. In
addition, no beneficial insect studies are available; it is uncertain
how pollinators will react to naphthalene when visiting ornamental
flowers and gardens. 

III. RISK CHARACTERIZATION tc "III.          Risk Characterization" 

Risk characterization integrates EECs and toxicity estimates and
evaluates the likelihood of adverse ecological effects to non-target
species.  In a deterministic approach, an exposure estimate is divided
by a single point estimate of toxicity to calculate a risk index (RQ or
LD50/ft2).  The RQ (for aquatic animals) or LD50/ft2 (for terrestrial
animals) is then compared to Agency’s levels of concern (LOCs) that
serve as criteria for categorizing potential risk to non-target species.

A.  Risks to Non-target Aquatic Organisms and Plants

Based on the available ecotoxicity information and the modeled aquatic
exposures (from the GENEEC2 model), it appears that naphthalene poses
minimal acute risk to aquatic animals and aquatic nonvascular plants
(i.e., fish, aquatic-phase amphibians, invertebrates, and alga) when
used at six applications, 60 days apart, at a rate of 10.8 lbs/acre
(Table III-1). Therefore, minimal acute risk also is expected from
minimum use rate of 0.56 lbs/acre for freshwater animals, because EECs
resulting from the lower use rate scenario to those aquatic species are
lower than the maximum use rate scenario. Risks to aquatic vascular
plants are also unknown due to lack of ecotoxicity data. 

Table III-1. Risks to Aquatic Animals and Plants for Naphthalene Use on
Ornamentals;

6 applications, 60 days apart at a rate of 10.8 lbs a.i./A 

Taxon	Species	Toxicity Endpoint 	EEC (µg/L)	RQ1	LOCs Exceeded2

Freshwater Fish	Rainbow trout

Onchorhynchus mykiss	96-hr LC50 = 2.0 mg/L

(or 2000 µg/L)	26.9 (peak)	0.013	None

	Coho salmon 

Oncorhynchus kisutch	40-day NOAEC = 0.37 mg/L

(or 370 µg/L)	22.4 (60D)	0.06	None

Freshwater Invertebrate	Water flea          Daphnia magna	48-hr LC50 =
1.6 mg/L

(or 1600 µg/L)	26.9 (peak)	0.017	None

Marine/estuarine Fish	Fathead minnow

Pimephales promelas	LC50 = 6.6 mg/L

(or 6600 µg/L)	26.9 (peak)	<0.01	None



NOAEC = 0.62 mg/L

(or 620 µg/L)	22.4 (60D)	0.04	None

Marine/estuarine Invertebrate	Grass shrimp

Palaemonetes pugio	LC50 = 2.35 mg/L

(or 2350 µg/L)	26.9 (peak)	0.01	None

Vascular Plant	Duckweed

Lemna gibba	No data	26.9 (peak)	Not available

Freshwater Non-Vascular Plant	Green Algae            Chlorella vulgaris
EC50 = 33 mg/L

(or 33000 µg/L)	26.9 (peak)	<0.01	None

1 Acute Risk Quotients are calculated using the following formula:
EEC/LC50; Chronic Risk Quotients are calculated using EEC/NOAEC.

2 Acute LOC for aquatic animals >0.05 for endangered species, >0.1 for
restricted use and >0.5 for non-listed species; LOC for aquatic plants  
        >1; Chronic LOC for aquatic animals >1.



B.  Risks to Non-target Terrestrial Animals and Plants

       Birds, reptiles and terrestrial-phase amphibians

Based on the available terrestrial ecotoxicity information and the
predicted direct ingestion exposures (from the T-REX model); naphthalene
appears to pose acute risk to birds, terrestrial-phase amphibians and
reptiles. For granular uses at the maximum application rate of 10.8
lbs/acre (Table III-2), the T-REX model indicates that the acute risk,
restricted use and endangered species LOCs are exceeded for all bird
weight classes. At 0.56 lbs/acre, only the restricted use and endangered
species LOCs are exceeded for the 1000-g bird weight class exposed to
naphthalene granules; all LOCs are exceeded for the 20- and 100-gram
weight classes. A definitive acute dietary LC50 was not established for
the bobwhite quail (i.e., LC50 > 5620 mg/kg-diet), and the TREX model
only allow dose-based RQs for granular applications; thus, acute dietary
risk quotients were not calculated and excluded from assessment at this
time.

      Mammals

The acute LD50/ft2s to terrestrial mammals, as a result of the assessed
uses of naphthalene at 10.8 (Table III-2) and 0.56 lbs/acre (Table
III-3), exceed the LOCs for acute risk, restricted use and endangered
species. 

Table III-2 Granular LD50/ft2 (RQs) from Direct Ingestion of Flakes at
10.8 lb ai/A -

EEC/Toxicity (adjusted mg/ft2 / adjusted LD50)A

Taxa	Weight Class	 

LD50/ft2	LOCs Exceeded B

Avian	20 g	604.48*	Acute Risk, Restricted Use, Endangered Species

	100 g	94.97*	Acute Risk, Restricted Use, Endangered Species

	1000 g	6.72*	Acute Risk, Restricted Use, Endangered Species

Mammal	15 g	268.18*	Acute Risk, Restricted Use, Endangered Species

	35 g	142.05*	Acute Risk, Restricted Use, Endangered Species

	1000 g	11.49*	Acute Risk, Restricted Use, Endangered Species

A Bird LD50 = 2690 mg/kg, Mammal LD50 = 2649 mg/kg; mg/ft2 = 23429.24

* Exceed acute risk, restricted use, and endangered species LOCs of 0.5,
0.2 and 0.1, respectively.

B Acute LOC for terrestrial animals: >0.1 for endangered species, >0.2
for restricted use and >0.5 for acute risk



Table III-3 Granular RQs (LD50/ft2) from Direct Ingestion of Flakes at
0.56 lb ai/A -

EEC/Toxicity (adjusted mg/ft2 / adjusted LD50)A

Taxa	Weight Class	 

LD50/ft2	LOCs Exceeded B

Avian	20 g	31.34*	Acute Risk, Restricted Use, Endangered Species

	100 g	4.92*	Acute Risk, Restricted Use, Endangered Species

	1000 g	0.35^	Restricted Use, Endangered Species

Mammal	15 g	13.91*	Acute Risk, Restricted Use, Endangered Species

	35 g	7.37*	Acute Risk, Restricted Use, Endangered Species

	1000 g	0.60*	Acute Risk, Restricted Use, Endangered Species

A LD50 = 2690 mg/kg, Mammal LD50 = 2649 mg/kg; mg/ft2 = 1214.85

* Exceed acute risk, restricted use, and endangered species LOCs of 0.5,
0.2 and 0.1, respectively.

^ Exceed acute restricted use and endangered species LOCs of 0.2 and
0.1, respectively.

B Acute LOC for terrestrial animals: >0.1 for endangered species, >0.2
for restricted use and >0.5 for acute risk



	Beneficial insects

No honeybee toxicity studies are available; consequently, it is
uncertain if honeybees will be impacted when pollinating in the treated
area. 

	Terrestrial plants

No seedling emergence or vegetative vigor studies are available;
consequently, it is uncertain if terrestrial plants will be affected in
the treated area. 

		  Risk Description

Risks to Non-target Aquatic Organisms and Plants

In the conceptual model, surface runoff/erosion to adjacent bodies of
water was predicted as the most likely sources of exposure of
naphthalene to non-target aquatic animals and plants.  Risks to aquatic
organisms (i.e. fish, invertebrates, and plants) were assessed based on
modeled estimated environmental concentrations (EECs) and available
toxicity data.  Aquatic EECs for the ecological exposure to naphthalene
were estimated using GENEEC2 employing the standard ecological water
body (Table II-2) and a percent area treated of 4.1% (Section 1.E).

The risk hypothesis stated that the use of naphthalene has the potential
to cause adverse effects to aquatic animals and plants.  For direct
acute risk to freshwater and estuarine/marine animals and algae and
direct risk following chronic exposure to freshwater and
estuarine/marine fish, this assessment refutes this hypothesis.  Risk of
direct effects to aquatic animals and algae are below the Agency’s
LOC, but risk is unknown for aquatic vascular plants.  Therefore,
potential risk of indirect effects cannot be precluded for aquatic
animals and plants until data on aquatic vascular plants are provided. 

a.         Fish and Aquatic Invertebrates

Available acute toxicity data for aquatic species indicate that
naphthalene is moderately toxic to freshwater and estuarine/marine fish
and invertebrates.  A comparison of the GENEEC peak EEC of naphthalene
in surface water of 26.9 µg/L to toxicity values for fish and
invertebrates indicates that the toxicity values (between 1600 - 6600
µg ai/L) were 59 to 245-fold higher than the highest estimated EEC. 
Therefore, it is concluded that the acute risk to freshwater and
estuarine/marine animals is expected to be minimal.

The chronic risk quotients calculated (freshwater and estuarine/marine
fish) is less than the chronic LOC of 1.0 for the proposed uses.  For
outdoor uses, the GENEEC2 60-day EEC was 22.4 µg/L.  The NOAECs from
chronic toxicity studies with the freshwater and marine/estuarine fish
were 0.37 mg/L (370 µg/L) and 0.62 mg/L (620 µg/L). A comparison of
the EEC with the NOAECs resulted in risk quotients that are several
orders of magnitude below the LOC of 1.0.  Therefore, potential risk to
fish following chronic exposure is lower than the chronic level of
concern for aquatic animals.

Consequently, the risks for acute and chronic adverse effects related to
reproduction, growth, and survival are lower than the Agency’s concern
level for freshwater and estuarine/marine fish and invertebrates
inhabiting surface waters adjacent to naphthalene treated site.
Nevertheless, freshwater animals are as sensitive as estuarine/marine
animals to naphthalene. 

b.         Aquatic-phase Amphibians

EFED currently uses surrogate data (fish) to estimate potential risks to
non-target aquatic phase amphibians. Risks to fish species were
discussed above. No aquatic-phase amphibian toxicity data was submitted
or was located in the open literature. Therefore, based on conclusions
for fish, risk to aquatic phase amphibians is also expected to be lower
than the Agency’s concern level.  

c.         Aquatic Plants  

EFED currently uses aquatic plant data to estimate potential risks to
non-target aquatic plants from surface water runoff. Available open
literature toxicity data with green algae indicate naphthalene is
slightly toxic to aquatic nonvascular plants with EC50 values of 33 and
34 mg/L. No aquatic vascular plant toxicity data with duckweed was
submitted or located in the open literature. Therefore, it is uncertain
if aquatic vascular plants inhabiting surface waters adjacent to a
treated area would be at risk for adverse effects to growth and
development as a result of naphthalene outdoor uses.  In addition to the
uncertainty, the proposed labels state that the products should not be
applied directly to foliage or stems.  This statement and summary
reviews of open literature data indicate that there is a possibility of
phytotoxicity to plants.  

	2.          Risks to Non-target Terrestrial Animals and Plants

In the conceptual model, animals exposed to naphthalene granules as
surrogate for flakes or crystals and wind erosion of soil particles are
the most likely sources of naphthalene exposure to non-target
terrestrial animals and plants. While terrestrial organisms may also be
exposed by other routes, such as incidental ingestion of contaminated
soil, dermal contact with treated granular surfaces and soil during
activities in the treated areas, and preening activities, the primary
route of exposure to naphthalene granules in this assessment will be via
the oral route. 

Acute risks to terrestrial animals (i.e. birds, terrestrial-phase
amphibians, reptiles and mammals) and plants (i.e. dicots and monocots)
were assessed based on modeled EECs and available toxicity data. As part
of the terrestrial assessment, exposure concentrations of naphthalene
granules to non-target terrestrial animals were modeled according to
labeled maximum and minimum application rates.  For terrestrial birds,
terrestrial-phase amphibians, reptiles and mammals, estimates of upper
bound levels of naphthalene granules, which may expose wildlife, were
determined using the Fletcher nomogram followed by a first order decline
model TREX 1.3.1 (Details in appendix D).   No terrestrial plant data
were available; therefore, no risk assessment was conducted for
terrestrial plants.

The risk hypothesis stated that the use of naphthalene has the potential
to cause adverse effects to terrestrial animals and plants.  The risk
hypothesis is confirmed for birds, terrestrial-phase amphibians,
reptiles and mammals, and for adverse effects to non-target terrestrial
animals and plants via indirect effects resulting from potential effects
to birds, terrestrial-phase amphibians, reptiles and mammals. However,
for terrestrial plants, due to lack of data, it is uncertain if
terrestrial plants inhabiting areas adjacent to a treated area would be
at risk for adverse effects to growth and development from naphthalene
uses. Furthermore, as stated previously, the proposed labels state that
the products should not be applied directly to foliage or stems.  This
statement indicates that there is a possibility of phytotoxicity.

a.    Birds

Naphthalene is categorized as practically nontoxic to upland game birds
(Northern bobwhite quail) on an acute oral (2690 mg/kg bw) and subacute
dietary (>5620 mg/kg diet) basis. No acute studies with the mallard duck
are available; therefore, it is uncertain if naphthalene is toxic to
waterfowl even though naphthalene is not toxic to upland game birds. In
the oral study, sublethal effects of ruffled appearance, depression,
reduced reaction to external stimuli, loss of coordination, lower limb
weakness prostrate posture, lethargy and loss of righting reflex were
more pronounced at the beginning of the test; at test termination, all
surviving birds appeared normal. Based on LD50/ft2 exposure method and
an avian oral LD50 of 2690 mg/kg bw, the Acute Risk, Acute Restricted
Use, and Endangered Species LOCs were exceeded for all weight classes
birds exposed to naphthalene granules at the maximum application rate of
10.8 lb/A (see Table III-2). At the minimum application rate of 0.56
lb/A (Table III-3), the Acute Risk, Acute Restricted Use and Endangered
Species LOCs were exceeded for all weight classes birds, except for 1000
g birds which only the Acute Restricted Use and Endangered Species LOCs
are exceeded. 

LD50 (mg/kg-bw) values from acceptable or supplemental toxicity studies
that are then adjusted for the size of the animal tested compared with
the size of the animal being assessed (e.g., 20-gram bird). For the use
of naphthalene on ornamentals, flowering beds and perimeter of
buildings, the highest EEC is 23429.24 mg ai/sq. ft.  The adjusted LD50
for a 20 g bird would be 1937.96 mg ai/kg-bw. The LD50/sq ft for a 20 g
bird would be 604.48. The result Table III-4 summarizes this comparison.
See Appendix D for T-REX modeling calculations and results following the
application of 10.8 and 0.56 lbs/A for birds. 



Table III-4.    Comparison of Avian Acute Toxicity Values with Predicted
EECs on Granule Consumption

Application Rate	Weight class (g)	Naphthalene Estimates



Predicted EEC 

(mg ai/sq ft)	Adjusted LD50 a

(mg ai/kg-bw)

10.8 lbs/A	

20	

23429.24	

1937.96

	

100	

23429.24	

2467.11

	

1000	

23429.24	

3484.89



0.56 lbs/A	

20	

1214.85	

1937.96







100

1000	1214.85

1214.85	2467.11

3484.89

 a LD50 = 2690 mg/kg-bw



To better characterize the risks to birds, this screening risk
assessment also estimates the minimum foraging area (square feet) needed
to allow for direct ingestion of sufficient mass of naphthalene to
achieve a dose that exceeds the adjusted LD50 by assuming that a bird
consumes 100%, 50% or 10% of the available granules depending on
bird’s weight class. In order to derive a first approximation of acute
exposure and risk to granular naphthalene for birds that may directly
consume granules, the TREX model takes into account that naphthalene
granules do not repel but attract birds and that 100% of avian diet is
comprised of naphthalene granules.  By comparing this estimated
concentration at 10.8 lb/A to the corresponding acute oral toxicity
reference value for birds (LD50 = 2690 mg/kg-bw for birds (MRID
148176)); acute LD50/ft2s were calculated and compared to the Agency’s
LOCs.  Subsequently, the LD50/ft2 for birds, in general, resulting from
exposure to 10.8 lb/A granular naphthalene was 8.7; the Agency’s LOCs
for acute risk (0.5), acute restricted use (LOC 0.2), and acute
endangered species (LOC 0.1) were all exceeded. The LD50/ft2 for birds,
in general, resulting from exposure to 0.56 lb/A granular naphthalene
was 0.45; the Agency’s LOCs for acute restricted use and endangered
species were exceeded. 

Although it seems unreasonable to assume that naphthalene granules may
be consumed by birds since it is not formulated as an attractant but as
a repellent to terrestrial animals and is comprised of granules with a
strong odor of coal tar, it is uncertain if the repellent nature of the
compound will be sufficient to keep birds away. The reason of the
uncertainty is based on the acute dietary study (MRID 148175) of
naphthalene to 13-day old bobwhite quails, the 5-day LC50 was >5620
mg/kg-diet but the NOAEC was 1000 mg/kg-diet due to reductions in
percentage of body weight while food consumption of treated birds were
higher (9-15 g/bird/day) than the control birds (8.6 g/bird/day). 
Nevertheless, the TREX model assumes birds are exclusively attracted to
naphthalene and their diets are 100% granules, which represents a
conservative scenario due to species-specific feeding habits and dietary
requirements. Therefore, EFED has taken further steps to characterize
the potential for acute risk to avian species by evaluating how much
area would need to be foraged to achieve the amount of naphthalene
granules necessary to trigger the Agency’s Levels of Concern (LOCs).
Table III-5 calculates the number of granules and minimum foraging area
needed to exceed Agency’s LOCs at 10.8 lb/A granular naphthalene.

Table III-5.  Estimates of the number of granules, and minimum area
foraged needed for a 20g, 100g, and 1000g bird to achieve the EEC that
would trigger an exceedance of the adjusted LD50, acute risk LOC (0.5),
and endangered species risk (0.5) levels of concern (LOCs) based on an
application rate of 10.8 lb/A

	Bird Size (grams)

	20	100	1000

No. of Consumed Granules Required to Reach the Specified LOC	Adjusted
LD50	1	7	92

	Acute Risk LOC (0.5)	0.51	4	46

	Endangered Species LOC (0.1)	0.1	0.65	10

Area of Field to be Foraged (square feet) to Achieve the Endangered
Species LOC Based on Application Rate of 10.8 lb/A.*	Assuming a 100%
Feeding Efficiency	0.03	0.22	3.1

	Assuming a 50% Feeding Efficiency	0.07	0.44	6.2

	Assuming a 10% Feeding Efficiency	0.34	2.19	31

* Immediate EEC = 112.46 mg/square feet (excluding row spacing,
bandwidth, and # of rows input parameters)



For instance, it was estimated that a 20-g bird would need to consume
0.1 granules to exceed the endangered species LOC.  Based on the maximum
application rate of 10.8 lb/A, this number of granules could be gleaned
from 0.03, 0.07, or 0.34 square feet (within the treated band) when
assuming a 100%, 50%, or 10% feeding efficiency, respectively.  To
achieve an EEC equivalent dose that would result in an exceedance of the
endangered species LOC, a 1000g bird would have to consume 10 granules.
It was estimated that this number of granules could be consumed in an
area of 3.1, 6.2, or 31 square feet when assuming a 100%, 50%, or 10%
feeding efficiency, respectively.

Table III-6 calculates the number of granules and minimum foraging area
needed to exceed Agency’s LOCs at the minimum application rate of 0.56
lb/A granular naphthalene.

Table III-6.  Estimates of the number of granules, and minimum area
foraged needed for a 20g, 100g, and 1000g bird to achieve the EEC that
would trigger an exceedance of the adjusted LD50, acute risk LOC (0.5),
and endangered species risk (0.5) levels of concern (LOCs) based on an
application rate of 0.56 lb/A

	Bird Size (grams)

	20	100	1000

No. of Consumed Granules Required to Reach the Specified LOC	Adjusted
LD50	1	7	92

	Acute Risk LOC (0.5)	0.51	4	46

	Endangered Species LOC (0.1)	0.1	0.65	10

Area of Field to be Foraged (square feet) to Achieve the Endangered
Species LOC Based on Application Rate of 0.56 lb/A.*	Assuming a 100%
Feeding Efficiency	0.66	4.2	60

	Assuming a 50% Feeding Efficiency	1.3	8.5	120

	Assuming a 10% Feeding Efficiency	6.7	42.3	598

* Immediate EEC = 5.83 mg/square feet (excluding row spacing, bandwidth,
and # of rows input parameters)



For this screening risk assessment purposes, it is assumed that birds
occupy, exclusively and permanently, the treated area being modeled.
This assumption leads to a maximum level of exposure in the risk
characterization. To the extent that a bird does not reside exclusively
and permanently in the treated areas ingesting naphthalene granules as
their only food source, exposure will be much less and presumably
substantially less. Naphthalene is manufactured as a repellent, so it is
likely that birds will avoid consumption of the naphthalene
flakes/crystals; however, incidental ingestion of naphthalene granules
may be the most likely route of exposure. 

Terrestrial-phase Amphibians and Reptiles

EFED currently uses data on surrogate species (birds) to assess
non-target terrestrial-phase amphibians and reptiles. Based on the
evaluation of potential risks to birds, potential risks to reptiles and
terrestrial-phase amphibians are also higher than the Agency’s levels
of concern. Again, to the extent that a terrestrial-phase amphibian or
reptile does not reside exclusively and permanently in the treated areas
ingesting naphthalene crystals or flakes, exposure will be much less.
Naphthalene is a repellent and it is manufactured to ensure that
reptiles will avoid the naphthalene flakes (e.g., Snake-A-Way). 

Mammals

Based on LD50/ft2 exposure method and mammal oral LD50 of 2649 mg/kg-bw,
the Acute Risk, Acute Restricted Use and Endangered Species Risk LOC
were exceeded for all weight classes (15-, 35- and 1000 g) mammals
exposed to naphthalene granules at both maximum and minimum application
rates (Tables III-2 and III-3). Mammalian species would be at risk to
adverse effects from granular application of naphthalene. Currently,
T-REX does not have the capacity to estimate the minimum foraging area
needed to allow for direct ingestion of sufficient mass of naphthalene
to achieve a dose that exceeds the LOC for mammals.

Beneficial Insects 

No honeybee contact study has been submitted; therefore, the potential
risks to beneficial insects are unknown. 

Terrestrial Plants

EFED currently uses terrestrial plant data to estimate potential risks
to non-target terrestrial plants from surface water runoff. No
terrestrial plant studies have been submitted or located in published
literature; therefore, the potential risks to terrestrial plants are
unknown. Therefore, it is uncertain if terrestrial plants inhabiting
areas adjacent to a treated area would be at risk for adverse effects to
growth and development as a result of naphthalene uses. Furthermore, as
stated previously, the proposed labels state that the products should
not be applied directly to foliage or stems.  This statement indicates
that there is a possibility of phytotoxicity; in addition, open
literature suggests that naphthalene is selectively phytotoxic to
plants. 

                        3.         Review of Incident Data

The National Pesticide Information Center (NPIC) prepares summaries of
information provided by individuals who have contacted the NPIC for
information or to report a pesticide incident. None of this information
has been verified or substantiated by independent investigations of NPIC
staff, laboratory analysis, or any other means. Thus, if a person
alleges/reports a pesticide incident, it will likely be recorded by
NPIC. NPIC qualifies the information by assigning a Certainty Index
(CI), which is an indication of the degree of certainty that the
purported incident was related to a pesticide exposure. CIs, range from
1 = “definite” to 5 = “unrelated”. NPIC makes no claims or
guarantees as to the accuracy of the CI or other information presented
in its reports, other than that NPIC has done its best to accurately
document/record the information provided to NPIC.

FIFRA 6(a)(2) incident data add lines of evidence to provide evidence
that the risk predictions from the screening level assessment are
substantiated with actual effects in the field. One incident resulting
from naphthalene use has been recorded in the Ecological Incident
Information System (EIIS) as of May 31, 2007. The incident reported
includes possible impact to fish. 

Formulation	Crop	Date and Location	Species Affected	Number Found	Residue
and ChE

Analysis	Miscellaneous, App. Rate, Method, etc.	Citation

Unknown	N/A	May 2003, Craven Co., NC	Unknown fish	2,000	No	Treated
directly	IO14123-006



	4. 	Endocrine Effects

One summarized study (Milton Fingerman, 1996) confirmed naphthalene is
an endocrine disrupter. When elevated in water to 10 mg/L, naphthalene
caused crawfish ovaries to shrink, resulting in fewer eggs and smaller
offspring. However, the open literature data was unavailable for review
for this assessment. 

	5.	Federal Threatened and Endangered (Listed) Species Concerns

Acute endangered species and chronic risk LOCs are considered in this
screening-level risk assessment of pesticide risks to listed species.
Endangered species acute LOCs are a fraction of the non-endangered
species LOCs or, in the case of endangered plants, RQs are derived using
lower toxicity endpoints than non-endangered plants. Therefore, concerns
regarding listed species within a taxonomic group are triggered in
exposure situations where restricted use or acute risk LOCs are
triggered for the same taxonomic group. The risk assessment also
includes an evaluation of the potential probability of individual
effects for exposures that may occur at the established endangered
species LOC in both the risk characterization and the endangered species
sections. This probability is calculated using the established
dose/response relationship and assumes a probit (probability unit)
dose/response relationship. This analysis is presented below. 

			

			a. 	Action Area

For listed species assessment purposes, the action area is considered to
be the area potentially affected directly or indirectly by the Federal
action and not merely the immediate area involved in the action. At the
initial screening-level, the risk assessment considers broadly described
taxonomic groups and so conservatively assumes that listed species
within those broad groups are co-located with the pesticide treatment
area. This means that terrestrial plants and wildlife are assumed to be
located on the treated site and aquatic animals are assumed to be
located in a surface water body adjacent to the treated site. The
assessment also assumes that the listed species are directly ingesting
the granules or exposed to the wind-borne granules located on an assumed
area that has the relatively highest potential exposure to the
pesticide. Section I.A.3 of this risk assessment presents the pesticide
use sites that are used to establish initial collocation of species with
treatment areas.

If the assumptions associated with the screening-level action area
result in RQs that are below the listed species LOCs, a “no effect”
determination conclusion is made with respect to listed species in that
taxa, and no further refinement of the action area is necessary.
Furthermore, RQs below the listed species LOCs for a given taxonomic
group indicate no concern for indirect effects upon listed species that
depend upon the taxonomic group covered by the RQ as a resource.
However, in situations where the screening assumptions lead to RQs in
excess of the listed species LOCs for a given taxonomic group, a
potential for a “may affect” conclusion exists and may be associated
with direct effects on listed species belonging to that taxonomic group
or may extend to indirect effects upon listed species that depend upon
that taxonomic group as a resource. In such cases, additional
information on the biology of listed species, the locations of these
species, and the locations of use sites and could be considered along
with available information on the fate and transport properties of the
pesticide to determine the extent to which screening assumptions
regarding an action area apply to a particular listed species. These
subsequent refinement steps could consider how this information would
impact the action area for a particular listed species and may
potentially include areas of exposure that are downwind and downstream
of the pesticide use site. 

	b.	Taxonomic Groups Potentially at Risk

 The preliminary risk assessment for endangered species indicates that
naphthalene exceeds the Endangered Species LOCs for the specified use
scenario for the following taxonomic groups:

Birds (all weight classes), reptiles and terrestrial-phase amphibians
ingesting granules in the treated area at both high and low application
rates.

Mammals (all weight classes) ingesting granules in the treated area at
both high and low application rates. 

With limited data available, no LOCs were exceeded for freshwater fish,
aquatic-phase amphibians and invertebrates. Data for estuarine/marine
species, beneficial insects and terrestrial/aquatic plants are not
available; it is uncertain if these species would be potentially at risk
when exposed to naphthalene.

				(1)	Discussion of Risk Indices

For a screening-level risk assessment, EFED determines what endangered
species may be affected by performing a screening level assessment. If
the RQs and LD50/ft2s from this assessment do not exceed the listed
species LOCs, endangered species may not be affected. However, the
Agency’s LOC for endangered and threatened birds, reptiles,
terrestrial-phase amphibians and mammals is exceeded for the use of
naphthalene as outlined in previous sections. Should estimated exposure
levels occur in proximity to listed resources, the available screening
level information suggests a potential concern for direct effects on
listed species within these taxonomic groups listed above associated
with the use of naphthalene as described in Section I.A.3

				(2)	Probit Dose Response Relationship	

A probit dose response analysis was performed for toxicity studies for
which slopes with 95% confidence intervals were available; these include
freshwater invertebrate (daphnid), freshwater fish (rainbow trout), and
birds (bobwhite quail).    SEQ CHAPTER \h \r 1 The probit slope response
relationship is evaluated to calculate the chance of an individual event
corresponding to the listed species acute LOCs. To accomplish this
interpretation, the Agency would use (1) the slope of the dose response
relationship available from the toxicity study used to establish the
acute toxicity measurement endpoints for each animal taxonomic group; 
(2) an assumption of a probit dose response relationship; (3) a mean
estimate of slope consistent with current Agency statistical procedures;
and (4) a lower limit to the estimate of individual effect chance based
on what could be calculated by Excel spreadsheet "Normdist" function. 
In cases where dose-response curves are unavailable, event probabilities
are calculated for the listed species LOC based on a default slope
assumption of 4.5 as per original Agency assumptions of typical slope
cited in Urban and Cook (1986).

Probability of an individual effect was estimated at the acute
endangered species LOC for aquatic and terrestrial animals (Table
III-7). Plants are not included in the probability analysis. This
analysis is presented in the following table.

Table III-7 Probit Dose Response Relationship Analysis

Taxa	Probit Slope (95% confidence intervals)	Endangered Species LOC
Estimated Probability of an Individual Effect at the Endangered Species
LOC	Comment

Birds, Reptiles and Terrestrial-phase Amphibians	2.13 (0.486-3.78)

MRID 148176	0.1	1 in 6E1

(1 in 3.19 to 1 in 1.28E4)	None

Mammals	4.5 (2-9)	0.1	1 in 2.9E5

(1 in 44 to 1 in 9E18)	Data insufficient to allow for probit slope
derivation; therefore, the default slope of 4.5 with lower and upper
bounds of 2 – 9 was used.

Fish and Aquatic-phase Amphibians	12.9 (7.8 – 18)

MRID 46030801	0.05	1 in 6E62

(1 in 5.9E23 to 1 in 7E120)	None

Aquatic Invertebrates	5.9 (1.4-10.3)

MRID 44302702	0.05	1 in 1.2E14

(1 in 29 – 1 in 3.3E40)	None



				(3)	Data Related to Under-represented Taxa

Data are not available to evaluate effects to under-represented taxa.

				(4)	Implications of Sublethal Effects

The only sublethal effect observed in the acute terrestrial animal
studies is a decrease in body weight in the bobwhite quail acute oral
study with a NOAEC of 1000 mg/kg-bw. No sublethal effects were reported
in any of the acute studies conducted with aquatic species.

Indirect Effect Analysis

The endangered species LOC for non-target animals was exceeded for
birds, reptiles, terrestrial-phase amphibians and mammals located in the
treated areas ingesting granules for the scenarios analyzed. The
guideline survival studies indicate direct adverse effects to 20-, 100-,
and 1000-gram birds, reptiles, terrestrial-phase amphibians and 15-,
35-, and 1000-gram mammals. 

Adverse effects to birds, reptiles, terrestrial-phase amphibians and
mammals may be sufficient to prevent the animals from competing
successfully with other animals for resources and water. Endangered
species may be especially impacted by exposure to naphthalene because of
the impact of the loss of a few individuals to the population. There is
a potential concern for listed species with either broad or narrow
dependencies on impacted bird, reptile, terrestrial-phase amphibian and
mammal species/populations/communities for habitat, feeding, burrowing
or cover requirements.

Critical Habitat

In the evaluation of pesticide effects on designated critical habitat,
consideration is given to the physical and biological features
(constituent elements) of a critical habitat identified by the U.S. Fish
and Wildlife and National Marine Fisheries Services as essential to the
conservation of a listed species and which may require special
management considerations or protection. The evaluation of impacts for a
screening level pesticide risk assessment focuses on the biological
features that are constituent elements and is accomplished using the
screening-level taxonomic analysis (risk indices, RQs or LD50/ft2s) and
listed species levels of concern (LOCs) that are used to evaluate direct
and indirect effects to listed species.

The screening-level risk assessment has identified potential concerns
for indirect effects on listed species for those animals and plants
dependant upon birds, reptiles, terrestrial-phase amphibians and
mammals. In light of the potential for indirect effects, the next step
for EPA and the Services is to identify which listed species and
critical habitat are potentially implicated. Analytically, the
identification of such species and critical habitat can occur in either
of two ways. First, the agencies could determine whether the action area
overlaps critical habitat or the occupied range of any listed species.
If so, EPA would examine whether the pesticide’s potential impacts on
non-endangered species would affect the listed species indirectly or
directly affect a constituent element of the critical habitat.
Alternatively, the agencies could determine which listed species depend
on biological resources, or have constituent elements that fall into,
the taxa that may be directly or indirectly impacted by the pesticide.
Then EPA would determine whether use of the pesticide overlaps the
critical habitat or the occupied range of those listed species. At
present, the information reviewed by EPA does not permit use of either
analytical approach to make a definitive identification of species that
are potentially impacted indirectly or critical habitats that is
potentially impacted directly by the use of the pesticide. EPA and the
Service(s) are working together to conduct the necessary analysis. 

This screening-level risk assessment for critical habitat provides a
listing of potential biological features that, if they are constituent
elements of one or more critical habitats, would be of potential
concern. These correspond to the taxa identified above as being of
potential concern for indirect effects and include the following: birds,
reptiles, terrestrial-phase amphibians and mammals. This list should
serve as an initial step in problem formulation for further assessment
of critical habitat impacts outlined above, should additional work be
necessary.

Direct Effect Co-occurrence Analysis

Because the Endangered Species LOC for birds, reptiles,
terrestrial-phase amphibians and mammals is exceeded for the proposed
use of naphthalene, LOCATES was run for all listed birds, reptiles,
terrestrial-phase amphibians and mammals to determine the potential for
co-occurrence of listed animal species location with areas of expected
pesticide use. However, no preliminary analysis was performed for
non-food uses of naphthalene because the LOCATES tool does not include
county-level location information for the proposed non-food use of
naphthalene. The animal taxa that reside in those areas, and the basis
for the designation, are in Appendix G. Consequently, based on the
information available at this step in the assessment process, it is
presumed that all listed animal species are potentially directly
affected from the broad range of naphthalene proposed uses which include
areas around houses, cabins, trailers, garages, utility houses, barns,
woodpiles, sand piles, trash cans, flower beds, plants (ornamentals,
roses, spring bulbs), around the periphery of gardens, and garbage bags
placed near residences and other buildings, streets or alleys for
garbage collection. Additional analysis of listed animal locations,
refinement of the action area associated with naphthalene regulatory
decisions, and the biology of the potentially affected species would be
needed before an effects determination can be made for any of the
co-located species identified by this assessment.

LOCATES listed 500 endangered/threatened birds, reptiles,
terrestrial-phase amphibians, and mammals found nationwide.
Consequently, based on the information available, it is presumed listed
species reside in areas of expected pesticide use (Table III-8).

Table III-8. Number of Listed Species Located in Non-Food Areas in the
United States of America

Non-food Use	Affected Counties	Affected States	No. of Species

Ornamentals, gardens, and the perimeters of structural buildings	All	50	

500

 

Indirect Effect Co-occurrence Analysis

The screening-level risk indices for birds, reptiles, terrestrial-phase
amphibians and mammals exceed the LOC for endangered species. In
accordance with established procedures such findings suggest a potential
concern for indirect effects to listed animal and plant species with
both narrow (i.e., species that are obligates or have very specific
habitat or feeding requirements) and general dependencies (i.e., cover
type requirements) on plants or animals as a resource or important
habitat component. LOCATES was used to preliminarily identify listed
animal and plant species that are located within the counties in USA
where naphthalene could be used. This analysis considered all animal and
plant taxonomic groups (i.e., conifers/cycads, monocots, dicots, ferns,
lichens, insects and arachnids) that eat birds or mammals, plants that
requires birds or mammals as pollinators or seed dispersers, or species
that require reptile or mammal burrows for shelter or breeding habitats.
However, no preliminary analysis was available for non-food use of
naphthalene because the LOCATES tool does not include county-level
location information for the proposed non-food use of naphthalene.
Consequently, based on the information available at this step in the
assessment process, it is presumed that these animal and plant species
are potentially indirectly affected from the broad range of naphthalene
uses which include areas around houses, cabins, trailers, garages,
utility houses, barns, woodpiles, sand piles, trash cans, flower beds,
plants (ornamentals, roses, spring bulbs), around the periphery of
gardens, and garbage bags placed near residences and other buildings,
streets or alleys for garbage collection. The animal and plant species
that reside in those areas, and the basis for the designation, are in
Appendix H and are summarized in Table III-9, below. Such potential
concerns are limited by the true potential for exposures of critical
animal and plant species resources to modeled naphthalene levels and the
relationship between ‘directly effected’ listed species and
‘indirectly effected’ listed species. Consequently, additional
analysis of listed species locations, refinement of the action area
associated with naphthalene regulatory decisions, and the biology of the
potentially affected species would be needed before an effects
determination can be made for any of the co-located species identified
by this assessment for potential indirect effects. 

	

Table III-9.  Listed taxonomic groups potentially at risk associated
with direct or indirect effects due to applications of naphthalene on
areas where ornamental plants, flowering beds and gardens are grown
nationwide

Listed Taxon	Direct Effects	Basis for Direct Effects Concern	Indirect
Effects	Basis for Indirect Effects Concern

Terrestrial and Semi-Aquatic Plants – monocots and dicots	Yes	Since
the product labels state, “Do not apply the product directly to
foliage or stems,” this statement indicates that there is a
possibility of phytotoxicity. In addition, open literature suggests
naphthalene is selectively phytotoxic to plants. However, toxicity data
are not available for terrestrial plants exposed to naphthalene. If
plants are sensitive to naphthalene, there might be direct effects to
plants. However, the likelihood for plants to be at risk from
naphthalene is low but cannot be precluded at this time. 	Yes	Potential
concerns for monocots and dicots that depend on birds, reptiles,
terrestrial-phase amphibians and mammals as pollinators or seed
dispersers. If pollinators such as honeybees, beneficial insects, and
birds/mammals are repelled from naphthalene, there might be indirect
effects to plants due to loss of pollinators for flower fertilization.

Honeybees	No	No data on honeybees are available. Naphthalene is
volatile, so it is uncertain if honeybees will be impacted from
pollinating the treated areas or if flowers will be indirectly affected
from the absent of pollinators. The likelihood of direct effect to
honeybees is low but cannot be precluded at this time.	Yes	Potential
concerns for honeybees that depend on mammal or reptile burrows for
habitat, feeding, or cover requirements.

Birds and Reptiles1	Yes	The endangered species LOC is exceeded for both
high and low application rates.	Yes	Potential concerns for birds and
reptiles that eat mammals as a food resource. 

Terrestrial-phase Amphibians1	Yes	The endangered species LOC is exceeded
for both high and low application rates.	Yes	Potential concerns for
terrestrial-phase amphibians that eat birds, reptiles and mammals as a
food source or use mammals and depend on reptile burrows for habitat and
shelter.

Mammals

	Yes	The endangered species LOC is exceeded for both high and low
application rates.  	Yes	Potential concerns for mammals that eat birds,
reptiles and terrestrial-phase amphibians and depend on reptile burrows
for habitat and shelter.

Aquatic Vascular Plants	Yes	Since the product labels state, “Do not
apply the product directly to foliage or stems,” this statement
indicates that there is a possibility of phytotoxicity. In addition,
open literature suggests naphthalene is selectively phytotoxic to
plants. However, toxicity data are not available for aquatic plants
exposed to naphthalene. If plants are sensitive to naphthalene, there
might be direct effects to plants. However, the likelihood for plants to
be at risk from naphthalene is low but cannot be precluded at this time.
Yes	Potential concerns for aquatic vascular plants that depend on birds,
reptiles, terrestrial-phase amphibians and mammals as pollinators or
seed dispersers. If pollinators such as honeybees, beneficial insects,
and birds/mammals are repelled from naphthalene, there might be indirect
effects to plants due to loss of pollinators for flower fertilization.

Freshwater Invertebrates, Fish and Aquatic-phase Amphibians2,3	No	No LOC
exceedances	Yes	If plants are directly or indirectly affected from
exposure to naphthalene, freshwater fish and amphibians may be
indirectly affected due to loss of cover or food sources. 

Estuarine/marine Fish and Invertebrates	No	No LOC exceedances	Yes	If
plants are directly or indirectly affected from exposure to naphthalene,
estuarine/marine fish and invertebrates may be indirectly affected due
to loss of cover or food. 

Aquatic Nonvascular  Plants – algae and diatoms	No	No LOC exceedances
Yes	Potential concerns for aquatic nonvascular plants that depend on
birds, reptiles, terrestrial-phase amphibians and mammals as pollinators
and seed dispersers. If pollinators such as honeybees, beneficial
insects, and birds/mammals are repelled from naphthalene, there might be
indirect effects to plants due to loss of pollinators for flower
fertilization.

1     Birds are used as surrogate species for terrestrial-phase
amphibians and reptiles; therefore, potential direct and indirect
effects to endangered avian, terrestrial-phase amphibians and reptilian
species are considered equivalent.

2      Fish are used as a surrogate for aquatic phase amphibians;
therefore, potential direct and indirect effects to endangered fish and
aquatic-phase amphibian species are considered equivalent.



D.   Assumptions, Uncertainties, Strengths and Limitations of the
Naphthalene Assessment.

Maximum use scenario

This screening-level risk assessment relies on labeled statements of the
maximum rate of naphthalene applications, the maximum number of
applications, and the shortest interval between applications. Together,
these assumptions constitute a maximum use scenario and can overestimate
risk. However, the maximum use scenario must be considered because it is
a reflection of the allowable use of naphthalene. The frequency at which
actual uses approach these maximums is dependent on the number and
timing of applications, and market forces. In addition, rates of
application less than the maximum rate are also considered.

Lack of data on degradates

There are several areas of uncertainty in the terrestrial and the
aquatic species risk assessments that could potentially cause an
underestimation of risk. First, this assessment accounts only for
exposure of non-target species to naphthalene, but not to its
degradates. The risks presented in this assessment could be
underestimated if degradates also exhibit toxicity under the conditions
of use proposed on the label.  Review of available open literature data
concerning the fate and toxicity of the transformation products of
naphthalene was limited to which degradates were observed but did not
provide information on the conditions under which degradates were
formed, the timing of formation, and what amounts were observed, and how
quickly (if at all) the degradates degraded.

Uncertainties with GENEEC 2 model

Extrapolating the risk conclusions from the standard pond scenario
modeled by GENEEC2 may either underestimate or overestimate the
potential risks. Major uncertainties with the standard runoff scenario
are associated with the physical construct of the watershed and
representation of vulnerable aquatic environments for different
geographic regions. The physicochemical properties (pH, redox
conditions, etc.) of the standard farm pond are based on a Georgia farm
pond. These properties are likely to be regionally specific because of
local hydrogeological conditions. Any alteration in water quality
parameters may impact the environmental behavior of the pesticide,
depending upon the specific properties of a given chemical (for example,
pH and dependant hydrolysis). The farm pond represents a well-mixed,
static water body. Because the farm pond is a static water body (no flow
through), it does not account for pesticide removal through flow through
or accidental water releases. However, the lack of water flow in the
farm pond provides an environmental condition for accumulation of
persistent pesticides. The assumption of uniform mixing does not account
for stratification due to thermoclines (e.g., seasonal stratification in
deep water bodies). Additionally, the physical construct of the standard
runoff scenario assumes a watershed:pond area ratio of 10 to 1. This
ratio is recommended to maintain a sustainable pond in the Southeastern
United States. The use of higher watershed:pond ratios (As recommended
for sustainable ponds in drier regions of the United States) may lead to
higher pesticide concentrations when compared to the standard
watershed:pond ratio.

Location of wildlife species

For screening terrestrial risk assessments for listed species, a generic
bird or mammal is assumed to occupy either the treated field or adjacent
areas receiving or ingesting pesticide at a rate commensurate with the
treatment rate on the field. Model predictions suggest that this
assumption leads to an overestimation of exposure to species that do not
occupy the treated field or do not ingest naphthalene granules
(crystals/flakes). The actual habitat requirements of any particular
terrestrial species are not considered, and it is assumed that species
occupy, exclusively and permanently, the treatment area being modeled.
This assumption leads to a maximum level of exposure in the risk
characterization. To the extent that a species does not reside
exclusively and permanently in treated areas, exposure will be less, and
presumably less. As for the case with naphthalene used as a repellent to
keep species away from treated areas, it is likely that terrestrial
species will not occupy the treatment area permanently or attempt to
ingest naphthalene granules. However, incidental ingestion of the
naphthalene granules is likely.

Routes of exposure

Screening-level risk assessments for granular applications of pesticides
consider dietary exposure alone. Other routes of exposure, not
considered in this assessment, are discussed below:

Incidental soil ingestion exposure

This risk assessment does not consider incidental soil ingestion;
however, since naphthalene repels unwanted species to the treated sites,
incidental soil ingestion may not need to be considered. 

Inhalation exposure

The screening risk assessment does not consider inhalation exposure.
Such exposure may occur through two potential sources: (1) vapor phase
pesticide volatilizing from treated surfaces and (2) airborne
particulate (soil, vegetative material, and pesticide
dusts/crystals/flakes).

Theoretically, inhalation of pesticide active ingredient in the vapor
phase may be another source of exposure for some pesticides under some
exposure situations. However, considering its moderate vapor pressure
value (8.5 x10-2 mm Hg), it is uncertain that naphthalene will exist in
the gaseous phase at any considerable amount to cause any adverse
effects via inhalation.

The impact from exposure to dusts/flakes/crystals contaminated with the
pesticide cannot be assessed generically as partitioning issues related
to application site soils and chemical properties render the exposure
potential from this route highly situation specific. 

Dermal exposure

The screening assessment does not consider dermal exposure, except as it
is indirectly included in calculations of risk indices based on lethal
doses per unit of pesticide treated area. Dermal exposure may occur
through three potential sources: (1) direct application of
flakes/crystals to terrestrial wildlife in the treated area, (2)
incidental contact with contaminated vegetation, or (3) contact with
contaminated water or soil. 

The available measured data related to wildlife dermal contact with
pesticides are extremely limited. The Agency is actively pursuing
modeling techniques to account for dermal exposure via direct
application of granules and by incidental contact with vegetation. 

Dietary Intake – The Differences between Laboratory and Field
Conditions

The acute and chronic characterization of risk rely on comparisons of
wildlife dietary residues with LC50 or NOAEC values expressed in
concentrations of pesticides in laboratory feed. These comparisons
assume that ingestion of granules in the field occurs at rates
commensurate with those in the laboratory. Although the screening
assessment process adjusts dry-weight estimates of food intake to
reflect the increased mass in fresh weight wildlife food intake
estimates, it does not allow for gross energy and assimilative
efficiency differences between wildlife food items and laboratory feed.

On gross energy content alone, direct comparison of a laboratory dietary
concentration- based effects threshold to a fresh-weight pesticide
residue estimate would result in an underestimation of field exposure by
food consumption by a factor of 1.25 – 2.5 for most food items. Only
for seeds would the direct comparison of dietary threshold to residue
estimate lead to an overestimate of exposure.

Differences in assimilative efficiency between laboratory and wild diets
suggest that current screening assessment methods do not account for a
potentially important aspect of food requirements. Depending upon
species and dietary matrix, bird assimilation of wild diet energy ranges
from 23 – 80%, and mammal’s assimilation ranges from 41 - 85% (U.S.
Environmental Protection Agency, 1993). If it is assumed that laboratory
chow is formulated to maximize assimilative efficiency (e.g., a value of
85%), a potential for underestimation of exposure may exist by assuming
that consumption of food in the wild is comparable with consumption
during laboratory testing. In the screening process, exposure may be
underestimated because metabolic rates are not related to food
consumption. 

Finally, the screening procedure does not account for situations where
the feeding rate may be above or below requirements to meet free-living
metabolic requirements. Gorging behavior is a possibility under some
specific wildlife scenarios (e.g., bird migration) where the food intake
rate may be greatly increased. Kirkwood (1983) has suggested that an
upper-bound limit to this behavior might be the typical intake rate
multiplied by a factor of 5.

In contrast is the potential for avoidance, operationally defined as
animals responding to the presence of noxious chemicals in their food by
reducing consumption of treated dietary elements. This response is seen
in nature where herbivores avoid plant secondary compounds or in this
case, avoid chemicals that specifically repel unwanted species visiting
the treated site.

Use of the most sensitive species tested

A small number of surrogate species were used in this screening level
risk assessment. It is not possible to determine whether the species
tested are more or less sensitive than species that may be exposed to
naphthalene. Also, it was assumed that fish are approximately as
sensitive as aquatic-phase amphibians and that bird are approximately as
sensitive as terrestrial-phase amphibians and reptiles. However, no data
are available to support these conclusions.

Lack of field studies

Although not required, field studies would assist in determining the
actual extent of potential indirect effects to plants that depends on
mammals and birds as pollinators and to animals that depends on reptile
or mammal burrows for shelter and habitat.

Age class and sensitivity of effect thresholds

It is generally recognized that test organism age may have a significant
impact on the observed sensitivity to a toxicant.

The screening risk assessment acute toxicity data for fish are collected
on juvenile fish between 0.1 and 5 grams. Aquatic invertebrate acute
testing is performed on recommended immature age classes (e.g., first
instar for daphnids, second instar for amphipods, stoneflies and
mayflies, and third instar for midges). 

Acute dietary testing with birds is performed on juveniles, with mallard
being 5-10 days old and bobwhite quail 10-14 days old.

Testing of juveniles may overestimate toxicity at older age classes for
pesticidal active ingredients because younger age classes may not have
the enzymatic systems associated with detoxifying xenobiotics. The
screening risk assessment has no current provisions for a generally
applied method that accounts for this uncertainty. In so far as the
available toxicity data may provide ranges of sensitivity information
with respect to age class, the risk assessment uses the most sensitive
life-stage information as the conservative screening endpoint.

Acute and Chronic LOCs

The risk characterization section of this assessment includes an
evaluation of the potential for individual effects at an exposure level
equivalent to the LOC. This evaluation is based on the median lethal
dose estimate and dose/response relationship established for the effects
study corresponding to each taxonomic group for which the LOCs are
exceeded. The dose-response curve representing a given taxa is generated
from one study using one species. It is likely that the resulting
dose-response relationship does not represent the response of all
species within a taxa. 

The risk estimates are based on acute and chronic effects in the
laboratory; therefore, these risk estimates do not directly take into
account uncertainties such as laboratory-to-field sensitivity
differences. These include uncertainty regarding the error introduced
when extrapolating from laboratory to field effects at a given
concentration. For example, mortality in the field could be greater in
populations previously stressed by other pesticide exposures,
temperature stress, habitat loss, predation, or competition for limited
resources. Field mortality and reduction in growth and reproduction
could be lower if the laboratory population were to represent an
unusually sensitive species. 

IV. LITERATURES CITED

U.S. EPA.  2004a. 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.  January 23, 2004.

U.S. EPA. 2004b. Interim Guidance of the Evaluation Criteria for
Ecological Toxicity Data in the Open Literature. Phases I and II.
Procedures for Identifying, Selecting and Acquiring Toxicity Data
Published in the Open Literature for Use in Ecological Risk Assessments.
Office of Pesticide Programs. July 16, 2004. 

U.S. EPA. 2000. Wildlife Exposure Factors Handbook.  Office of Research
and Development, Washington, D.C. EPA/600/R-93/187. December 1993.

U.S. Department of Health and Human Services, 2005.  Toxicological
Profile for Naphthalene, 1-Methylnaphthalene, and 2-Methylnaphthalene.
Public Health Service, Agency for Toxic Substances and Disease Registry.
 August 2005.

U.S. National Park Service, 1997. Environmental Contaminants
Encyclopedia – Naphthalene Entry.  Water Resources Divisions, Water
Operations Branch, Ft Collins, Colorado.  July 1, 1997.

Hoerger, F., and E.E. Kenaga. 1972. Pesticide residues on plants:
Correlation of representative data as a basis for estimation of their
magnitude in the environment. In F. Coulston and F. Korte, eds.,
Environmental Quality and Safety: Chemistry, Toxicology, and Technology,
Georg Thieme Publ, Stuttgart, West Germany, pp. 9-28. Support Document #
14.

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature
review and evaluation of the EPA food-chain (Kenaga) nomogram, and
instrument for estimating pesticide residues on plants. Environ. Tox.
Chem. 13:1383-1391.

 www.epa.gov/waterscience/pc/ambientwqc/naphthalene80.pdf

 http://www.atsdr.cdc.gov/toxprofiles/tp67.pdf

   HYPERLINK "http://en.wikipedia.org/wiki/Naphthalene" 
http://en.wikipedia.org/wiki/Naphthalene 

   HYPERLINK
"http://en.wikipedia.org/wiki/Polycyclic_aromatic_hydrocarbons" 
http://en.wikipedia.org/wiki/Polycyclic_aromatic_hydrocarbons 

   HYPERLINK "http://cat.inist.fr/?aModele=afficheN&cpsidt=13944427" 
http://cat.inist.fr/?aModele=afficheN&cpsidt=13944427  and              
                                                       HYPERLINK
"http://cat.inist.fr/?aModele=afficheN&cpsidt=1407090" 
http://cat.inist.fr/?aModele=afficheN&cpsidt=1407090 

 Information obtained from Naphthalene SMART meeting, March 28, 2007.

 mg ai/ft2 = application rate x % active ingredient x 453,590 mg/lb  x %
incorporation

		no. of rows/acre x row length x bandwidth  

 See   HYPERLINK "http://www.epa.gov/oppefed1/models/water/index.htm" 
http://www.epa.gov/oppefed1/models/water/index.htm  for more details.

 T-REX, 2005. See   HYPERLINK
"http://www.epa.gov/oppefed1/models/terrestrial/" 
http://www.epa.gov/oppefed1/models/terrestrial/  for more information

 The exact mass of naphthalene per flakes was not provided; however,
information obtained from Naphthalene SMART meeting, March 28, 2007 was
used to estimate the weight.

 LD50 ft-2 = EEC (mg a.i./ft2) / (Adj. LD50 x bw (kg) of assessed
animal) = (23429 mg ai/sq ft) / (1937 mg/kg bw x .02 kg) = 604

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