23



# Preliminary Ecological Risk Assessment and Endangered Species Effects Determination in Support of the Registration Review

of Polybutene

PC Code 011402

CAS Number 9003

- 2 9

- 6

Prepared by: Nicholas Mastrota, Ph.D. Wildlife Biologist

Environmental Risk Branch 3

Environmental Fate and Effects Division

Reviewed by: Dana Spatz, Branch Chief

Rosanna Louie

- Juzwiak, Risk Assessment Process Leader

February 2 8

, 201 34



### Table of Contents

1. Problem Formulation

................................ ................................ ................................ .. 5

1.1. Stressor Description

................................ ................................ ............................. 5

1.2. Env ironmental Fate Summary

................................ ................................ .............. 5

1.3. Mode of Action

................................ ................................ ................................ .... 6

1.4. Use Characterization

................................ ................................ ............................ 6

1.5. Ass essment Endpoints

................................ ................................ .......................... 7

1.6. Ecosystems Potentially at Risk

................................ ................................ ............ 8

1.7. Risk Hypothesis

................................ ................................ ................................ .... 8

1.8. Results of Previous Assessments

................................ ................................ ......... 9

2. Analysis Plan

................................ ................................ ................................ .............. 9

3. Exposure Assessment

................................ ................................ ................................ 10

3.1. Label Application Rates

................................ ................................ ..................... 10

3.2. Aquatic Exposure

................................ ................................ ............................... 10

3.3. Exposure to Terrestrial Animals

................................ ................................ ........ 11

3.4. Terrestrial Plant Exposure

................................ ................................ .................. 12

4. Effects Assessment

................................ ................................ ................................ ... 12

4.1. Ecoto xicity Data

................................ ................................ ................................ . 12

4.1.1. Terrestrial Organisms

................................ ................................ .................. 12

4.1.2. Aquatic Organisms

................................ ................................ ...................... 13

4.2. ECOTOX Data

................................ ................................ ................................ ... 14

4.3. Ecological Incident Reports

................................ ................................ ............... 14

5. Risk Description

................................ ................................ ................................ ........ 15

5.1. Aquatic Risk

................................ ................................ ................................ ....... 15

5.2. Terrestrial Risk

................................ ................................ ................................ ... 16

5.2.1. Bir ds, Mammals, Reptiles, and Terrestrial

- Phase Amphibians

.................. 16

5.2.2. Terrestrial Invertebrates

................................ ................................ .............. 18

5.2.3. Terrestrial Plants

................................ ................................ ......................... 18

6. Risk to Threatened and Endangered Species

................................ ............................ 18

References

................................ ................................ ................................ ......................... 205

1. Problem Formulation

The problem form ul ation provides a strategic framework for the risk assessment. By identifying the important components of the problem, it focuses the assessment on the most relevant chemical properties, exposure routes

, and endpoints.

1.1. Stressor Description

Polybutene is a homopolymer composed of repeating units of the monomer n

- butene or

iso

- butene. It is a non

- drying, sticky polymer

, registered for use primarily as a nuisance

bird (such as pigeons and starlings) repellent , but is also registered to repel beavers that may gnaw on tree trunks

. It acts as a tactile repellent. When birds land on treated objects or surfaces, they are deterred by the sticky tactile sensation and usually do not return. Polybutene's tacky quality is the source of the repellent action of pesticide products containing this active ingredient. The product therefore differs from typical p esticides in that it is not intended to be ingested by the pest species.

1.2. Environmental Fate Summary

Physical and chemical properties of polybutene are given in Table 1. Polybutene is a highly stable and extremely insoluble inorganic material. Water s olubility is very low (<0.1%). An important physical property in the pesticidal activity of polybutene is its viscosity, which makes it sticky to touch. EPA has not imposed any environmental fate data requirements for the registration of polybutene because its properties and use pattern will result in very limited exposure to the environment beyond the point of application

.

Polybutene is considered to be persistent to abiotic hydrolysis, direct photolysis in water, and microbial degr a dation. Its us e in sealants is a testament of its high stability in the environment. Any aging of polybutene may occur from exposure to the environment for a prolonged period of time, in which photooxidation of the double bond between carbon atoms (

– C=C

– ) may gradually generate epoxides, aldehydes, and carboxylic acids. These

reactions are known to form other polyalkenes (Minerath et al., 2009), but there are no known degradation studies specific for polybutene oligomers. The estimated K

oc of 2.5 x

10 9 L/kg indicates that it absorbs strongly to soil and other surfaces. Therefore, polybutene is not expected to be mobile in the terrestrial environment. Furthermore, because of its extremely low solubility, and application methods that would produce

little

- to

- no spray dr ift, polybutene is not expected to be transported to aquatic environments in significant amounts. Any l eaching to ground water is also expected to be negligible. Therefore, no aquatic exposure or drinking water exposure assessment was conducted when eval uating the pesticidal uses of this chemical.6

Table 1. Physical and Chemical Properties of Polybutene and Its Monomer Butene

Common name Polybutene

Chemical name Polybutene oligomer Pesticide type Pest repellent. Pests include birds and beavers

Chemical class Alkene polymer

CAS number 9003

- 29

- 6 (polybutene)

US. EPA Chemical Code 011402

Monomer n

- butene and iso

- butene Type of polymer Homopolymer; Oligomer Empirical formula of the monomer and of the polymer n

- butene CH 3 CH 2 CH=CH 2

Isobutene H 2 C=C(CH 3 )

CH 2 - C(CH 3 ) 2 ; C 4 H 8 (monomer)

- [

- CH 2 - C(CH 3 ) 2 - ]

n ; (C 4 H 8 )

n (homopolymer)

SMILES Notation C(C=C)C.C(=C \ C) \ C Molecular mass (g/mol) of monomer 56.1063

Molecular mass range (g/mol) of the oligomer 320

- 420 Range of monomer units in the oligomer ~5

- 8 monomer units

Vapor pressure 0.13 torr (mmHg), at 25 ̊ C Henry’s Law Constant (atm

- m 3 /mol) 4.88 x 10 5 (estimated; EPISuite); No experimental data Solubility in water (mg/L) < 0.1 %, negligible

5.07 x 10 - 7 mg/L (estimated; EPISuite); No experimental data) Log K

ow 17.14 (estimated; EPISuite); No experimental data) pK

a /pK

b Not applicable
EPISuite (Estimation Program Interface); EPIWeb 4.0

1.3. Mode of Action

Polybutene acts as a tactile repellent for birds and mammals . The viscosity and sticky property of the substance deter animals from perching, roosting, or walking on treated

surfaces

.

1.4. Use Characterization

Polybutene is used as a repellent to birds from perching on buildings and structures, and to repel beavers from gnawing on trees. Polybutene products may be used on areas of buildings or adjacent structures or plants where birds land or roost (for example, on ledges , window sills , beams , gutters

, trees, shrubs, and vines ), and on the lower trunk

area of trees

. (USEPA, 1995).

Current polybutene registrations are described in Table 2. Tanglefoot Bird Repellent, Hot Foot Bird Repellent, and 4 the Birds Repellent are ready

- to

- use gels which come in tubes for use in caulk guns, and a re applied in beads on horizontal surfaces to repel birds7

from perching . 4 the Birds Transparent Bird Repellent is a liquid that may be painted on or sprayed onto surfaces with a hand or pressure sprayer. This is the only polybutene

containing product re gistered to repel beavers from gnawing on trees. For this use, the product may be applied to the lower trunk of trees up to the height of 2 feet.

Table 2. Current Polybutene Registrations

Product Name (Registrant) EPA Registration

Number (latest label da te) Active Ingredients (% w/w) U se Sites

Tanglefoot Bird Repellent 1621

- 17 93.5 Bird roosting and nesting areas on buildings and structures

Hot Foot Bird Repellent 55943

- 1 93.5 Bird roosting and nesting areas on buildings and structures

4 the Birds Repellent 8254

- 5 93 Bird roosting and nesting areas on buildings and structures

4 the Birds Transparent Bird Repellent Liquid 8254

- 3 49 Bird roosting and nesting areas on buildings, structures, and woody plants

, and lower trunks of trees for repelling beavers.

1.5. Assessment Endpoints

This assessment evaluates the potential for adverse e ffects as a result of polybutene us e per label specifications . As described in the Agency’s Overview Document (U.S. USEPA, 2004), the most sensitive endpoint for each tax on is evaluated. Assessment endpoints are selected based on ecosystems typically at risk from pesticide use and include direct toxic effects on the survival, reproduction, and growth of terrestrial and aquatic life.

For this assessment, exposure to aq uatic organisms, terrestrial invertebrates, and terrestrial plants is assumed to be negligible. Therefore, for these taxa, the EPA has not asked for toxicity data and a quantitative risk assessment was not conducted. The ecological risk assessment is lim ited to evaluating terrestrial vertebrates. For these taxa, available toxicity data for birds ( 2 studies) and mammals ( 3 studies ) are used as assessment endpoints, as described in Table 3.8

Table 3. Summary of Assessment Endpoints and Measures of Ecological Effect for the Assessment of Risk of Polybutene to Terrestrial Wildlife

Assessment Endpoint Measures of Ecological Effect

Terrestrial Environments

Abundance (i.e. survival, reproduction, and growth) of individuals and populations of birds 1 Avian acute oral toxicity: Northern Bobwhite ( Colinus virginianus)

LD 50 > 2150 mg a.i./kg

- bw Avian dietary toxicity: Northern Bobwhite ( Colinus virginianus)

LC 50 > 5000 mg a.i./kg

- diet

Abundance (i.e. survival, reproduction, and growth) of individuals and populations of birds and mammals) Acute oral toxicity: Laboratory Rat LD 50 > 5000 mg a.i./kg

- bw Acute Dermal toxicity:

Rabbit LD 50 > 980 mg a.i./kg

- bw

1 Birds represent surrogates for reptiles and terrestrial

- phase amphibians

1.6. Ecosystems Potentially at Risk

Based upon the label ed uses of polybutene and its properties

, the only ecosystems potentially at risk are the terrestrial ecosystem s where the product is applied. As the treated product is not expected to migrate from the point of use in any significant amount,

risk in the se ecosystems will be limited to organisms that come into contact with the product at the place it is applied. Si nce the product is used primarily on man

- made structures, animals inhabiting urban and residential areas are most likely to be e xposed.

Considering that the water solubility of polybutene is negligible, runoff from the treatment site is not expected to r esult in any appreciable movement of residues to aquatic

habitats . Also, since spraying of this viscous substance is not expected to result in appreciable spray drift, aquatic habitats would not be contaminated by spray drift. Therefore, aquatic ecosyste ms are not beli e ved to be at risk from the label ed use of polybutene.

1.7. Risk Hypothesis

For polybutene , the following ecological risk hypothesis is being employed for this risk

assessment:

W hen used in accordance with the label, polybutene may result in adverse effects

on the surviva l of nontarget terrestrial animals because of possible direct ingestion of the product or because of inadvertent entrapment by the products.

Given the properties and use pattern of polybutene , exposure to aquatic animals,

aqu atic plants, and terrestrial plants is believed to be insignificant

.9

1.8. Results of Previous Assessments

Pr evious ecological reviews and risk assessments conducted for polybutene include:

Reregistration Phase IV Review (Memorandum from Fred Betz to Jay Ellenberger

, February 1993 ) Reregistration Eligibility Decision (RED, USEPA December 1994) Registration Review: Problem Formulation for Polybutene. May 19, 2010 (D371745)

The registered uses of polybutene have remained the same throughout the period of these

assessments. In all of these assessments , no risk exceeding the EPA’s level of concern (LOC) was identified with the exception of possible entrapment of small birds. For aquatic risks, these assessments concluded negligible risks to aquatic organisms because

of the tacky composition and insolubility of the end

- use product. For terrestrial risks, these assessments concluded that ingestion of the product by animals was unlikely. Considering the lack of exposure , together with the lack of toxicity observed in avian acute oral and subacute dietary tests, risk from oral ingestion of polybutene was

concluded to be below the EPA’s level of concern. However, all of the assess ments stated that use of the product may pose a risk to small birds, and possibly other small terrestrial animals, because they could become entrapped if they come in contact with the tacky product. This risk was considered greatest for the liquid product because it may be sprayed onto trees, shrubs, bushes, and vines where birds frequently p erch

. Previous risk

assessment s did not assess risk to nontarget plants or terrestrial insects.

The 2010 Problem Formulation cites an incident reported in 2008 in wh ich some cedar waxwings ( a passerine bird species ) were incapacitated or killed after entrapment by the product. An assessment completed in 1993 discusses an earlier bird kill incident in 1990 which involved the entrapment and deaths of 15 birds following a misuse (over

application) of the product. As a result of the earlier incident reports

, the 1994 RED required that polybutene products car ry the following warning statement on the label:

“Small birds may become fatally entrapped by this tacky repellent. To reduce hazards to legally protected species, and to avoid noncompliance with the Federal Migratory bird Treaty Act, follow all instructions in the Direction for Use.”

2. Analysis Plan

Typically, direct and indirect ecological effects are evaluated based on ratios (risk quotients) of the estimated exposure to a designated toxicity endpoint. Terrestrial exposure is typically based on estimated maximum residues on contaminated food items consumed by wildlife , and for terrestrial plant, exposure from runoff and spray drift

. Aquatic exposure is typically based on estimated maximum concentrations in a modeled body of water contaminated by pesticide runoff and/or spray drift. However, due to the

use pattern and physical properties of polybutene, use of polybutene as a pest repellent is10

expected to result in negligible contamination of wildlife food items

, and negligible exposure to nontarget plants and aquatic habitats from runoff and spray d rift. Therefore, no quantitative risk assessment based on the traditional risk quotient method w as conducted. Instead, exposure and potential risk of polybutene to nontarget organisms

w as assessed qualitatively based on evidence of exposure and toxicity ( or lack thereof) and a qualitative assessment of the likelihood of nontarget organisms ingesting or coming into contact with the product. The risk of nontarget organisms becoming physically entangled with the product w as also qualitatively assessed.

3. Exp osure Assessment

3.1. Label Application Rates

In order to estimate potential exposure from a pesticide application, a pesticide product

label typically state s application rates in terms of amount of product per unit area ( e.g. , pounds of product per acre). Unlike typical pesticide labels, t he polybutene product labels

do not specify an application rate, per se

. In an effort to quantify the potential amoun t of active ingredient (a.i.) for a given area, the Biological and Economical Analysis Division (BEAD) es timated the potential amount of a.i. that may be applied, based on product labeling directions. For products applied with a caulk gun ( Tanglefoot Bird Repellent, Hot Foot Bird Repellent, and 4 the Birds Repellent), the application rate wa s estimated to
be approximately 0.05

- 0.06 lb a.i. /linear foot. For use of “ 4 the Birds Transparent Bird Repellent ” on tree trunks to repel beavers, BEAD estimates the application rate to be 0.80

lb ai/ft trunk diameter or 0.124 lb ai/in trunk diameter. For use of “4 the B irds Transparent Bird Repellent” on structures and woody plants to repel birds, no application rate is given; the label only instructs the user to apply to the point of runoff.

3.2. Aquatic Exposure

Polybutene is highly insoluble in water. Water solubility was estimated by EPISuite to

be 5.07 x 10 - 7 mg/L. Therefore, movement of residues from the treatment site to aquatic habitats in runoff is expected to be negligible. Negligible exposure is also expected from spray drift. Only one product (“4 the Birds Transparent Bird Repellent”) may be applied as a spray and thus could conceivably produce spray drift. Although the label instructs the user to coat treated surfaces to the point of run off, given the application methods and

limited areas that would be tre ated, little

- to

- no spray drift exposure is expected far from the site of use. Thus, we conclude that use of this product results in negligible contamination of aquatic habitats by runoff or spray drift.

While the very low solubility of polybutene precludes significant dissolved concentrations in water, acute aquatic toxicity tests show that when significant quantities of polybutene are applied to water, a slick can form on the water’s surface. While not a mechanism of dire ct toxicity, this surface slick can possibly result in depletion of11

dissolved oxygen in the water , thereby causing suffocation

. However, polybutene is very viscous and tacky, and thus material applied to buildings, structures, and woody plants to repel bi rds is expected to remain in place and not wash off into aquatic habitats in appreciable amounts. Given the limited and localized use of polybutene products, this scenario is not considered likely. Therefore, any aquatic exposure is expected to be negligi ble.

3.3. Exposure to Terrestrial Animals

Terrestrial animal d ietary exposure to polybutene is expected to be negligible. Being an inorganic polymer with known repellent properties, animals are not expected to intentionally ingest polybutene at the site of application. Application of th e 4 the Birds Transparent Bird Repellent product to surfaces on buildings and structures where birds may perch is not expected to result in any appreciable contamination of wildlife food

items. Application of th is product to woody plants to repel birds or beavers may result in a small amount of material contaminating potential wildlife food items, such as by inadvertently being applied to leaves or buds, or dripping onto vegetation beneath the treatment site. However, the extent of this contamination is expected to be very small. Additionally, the treatment areas are expected to be very limited, such as applications

made to a small number of woody plants that are located adjacent to homes or buildings, where roosting birds would be considered a nuisance. Contamination of wildlife food items would be limited to these plants and to areas lying beneath these plants. Furthermore, being a repellent, animals are not expected to find these contaminated areas attractive for forag ing. Therefore, inadvertent ingestion of the product by animals, including listed species, is unlikely

. Furthermore, considering the low toxicity of polybutene, it would not be expected to approach toxic levels should exposure occur.

The primary route of exposure to terrestrial animals is physical contact with polybutene

. While the tackiness of the material would generally deter animals, in some cases contact may result in small animals becoming entangled in the material. Wildlife and insects

c ould come into contact with the products by perching or walking on treated surfaces of structures or woody plants. As previously noted, because treatment areas are very small, and the geographic locations of applications are generally remote from listed s pecies locations, exposures to threatened or endangered animal s are unlikely to occur. However, given that the target pest includes nuisance birds, r isks from such physical

contact are assessed qualitatively in this risk assessment.

The label of “4 the B irds Transparent Bird Repellent” (the only product that may be applied to woody plants), carries the following statement:

Do not apply this product directly to trees, bushes or vines that are in bloom or bearing fruit except as indicated on this label for use as a paint on the lower areas of tree trunks to discourage damage (debarking and cutting) by beavers.12

This restriction would reduce the risk of inadvertent contamination of fruit, thereby reducing the risk of dietary exposure to frugivores. The stat ement would also mitigate the risk of physical contact and possible entanglement of wildlife and insects that feed on fruit, as well as hummingbirds, honey bees, and other insect pollinators that feed on nectar and/or pollen.

3.4. Terrestrial Plant Exposure

Based upon the nature of the use and the properties of the compound, minimal exposure

of terrestrial plant s is expected

. N o significant movement or transport of polybutene off

the site of treatment is expected

. E xposure to terrestrial plants is expected to be limited to the plants that are directly treated with the product , or that lie immediately beneath treated plants , and the chance of occurrence of listed plants at the immediate treatment site is extremely small

. Therefore, exposure of pla nts is expected to be low and is not expected to result in adverse effect to listed plants

.

4. Effects Assessment

4.1. Ecotoxicity Data

4.1.1. Terrestrial Organisms

Table 4 summarizes the available data on the toxicity of polybutene to nontarget organisms. Only acut e and subacute toxicity studies with birds and mammals have been submitted. Based on both acute oral and subacute dietary tests with the northern

bobwhite , polybutene is classified as practically nontoxic to birds. No mortality or signs of toxicity were observed in an acute oral test with birds, although one bird died in a subacute dietary test when given a dietary concentration of 5000 mg/kg diet (0.5%). Acute oral testing with the rat also classifies polybutene as practically nontoxic to

mammals. Admi nistration of a dose of 5000 mg/kg

- bw resulted in no mortality. The only sign of toxicity observed was a dry rale in one rat which lasted for two days. EFED

does not consider this a frank toxic effect.

Acute inhalation testing with a mammal was waived in the Polybutene Reregistration Eligibility Decision (RED) because t he viscosity of polybutene was believed to limit production of respirable particles during spraying. A dermal toxicity test was conducte d with the rabbit using the formulated product “4 the Birds Transparent bird Repellent Liquid” (Reg. No. 8254

- 3, 49% AI) . In this study, the acute dermal LD 50 was determined to be > 2000 mg/kg, which is equivalent to > 980 mg ai/kg. Since the test was co nducted with a product containing 49% AI, the inert ingredients in the formulated product may have contributed to the observed toxicity in this study.

No data have been submitted to the EPA on the chronic toxicity of polybutene to birds or

mammals. Also, no data are available on the toxicity of polybutene to terrestrial plants.13

Table 4. Acute Toxicity of Polybutene to Terrestrial Species.

Taxonomic Group, Study Type Surrogate Species Toxicity ( e xpressed as AI) MRID Study

Classification

Birds 1

Birds, Acut e Oral Northern Bobwhite

( Colinus vi r

ginianus ) L D 50 > 2 15 0 mg/kg bw

No mortality or sublethal

effects observed 42873827 Acceptable

Birds,

Suba cute Dietary Northern Bob white

( Colinus vi r

ginianus ) L C 50 > 5000 mg/kg diet

One death at 5000 mg/kg 41832002 Acceptable

Mammals

Mammals,

Acute Oral Laboratory rat

( Rattus norvegicus ) LD 50 > 5000 mg/kg bw (males

and females ) No mortality. No signs of toxicity except for a dry rale in

one rat 0

- 2 days after dosing with 5000 mg/kg bw. 41772401 Acceptable

Mammals,

Acute Dermal Rabbit LD 50 > 2000 mg/kg 2

LD 50 > 980 mg ai/kg One mortality at 2000 mg/kg.

The rabbit that died exhibited

diarrhea and blanched areas of

the liver 40222701 Acceptable

Mammal,

Acute

Inhalation -- --

-- Waived 3

1. Birds represent surrogates for terrestrial

- phase amphibians and reptiles.

2. Results for a test of “4 the Birds Transparent bird Repellent Liquid” (Reg. No. 8254

- 3, 49% AI)

3. Requirement for an inhalation toxicity study was waiv ed because the viscosity of polybutene was believed to limit production of respirable particles during spraying.

4.1.2. Aquatic Organism s

T he extremely low solubility of polybutene thwarted successful testing of acute toxicity

with freshwater fish and invertebrates. In the limit test with the rainbow trout ( Oncorhynchus mykiss ) (MRID 43382701) , the insoluble test material formed a surface slick in the test vessels throughout the tr ial. At the nominal test concentration of 10,000 mg/L, dissolved oxygen fell below 60% saturation at 72 hours, apparently because the

test material formed a seal between the water surface and the air

. Five of the ten fish exposed at this test level died. After aeration of the test vessels was initiated, all of the remaining fish survived and showed no signs of toxicity, indicating that the mortality was caused by lack of oxygen rather than by toxicity of polybutene. In a n acute toxicity test

with the wa ter flea ( Daphnia magna ) (MRID 43382701), mortality ranged from 20% at a nominal concentration of 100 mg/L to 100% at a nominal concentration of 10,000 mg/L. However, all of the deaths appeared to have occurred from the physical entrapment of organisms to globules of undissolved test material floating on the surface and adhered to the sides of the test vessels. In a separate test of the water soluble fraction, in which undissolved test material was removed, no mortality was observed at any test

concentrat ion. These tests indicate that the presence of significant amounts polybutene in14

water may be harmful to aquatic organisms, not because of toxicity, but because of adverse physical effects ( i

. e. , oxygen depletion).

Additional testing found that the solu bility could not be enhanced by use of solvents. The EPA concluded that appropriate means of increasing the solubility of polybutene ha d been exhausted and that further testing would not be productive. Therefore, requirements for acute toxicity data with fish and aquatic invertebrates were waived for polybutene (USEPA, 1994)

.

No data have been submitted on the toxicity of polybutene to aquatic plants. As with fish and aquatic invertebrates, the extremely low solubility of polybutene is believed to make testing of aquatic plant toxicity impractical.

4.2. ECOTOX Data

A search of the aquatic and terrestrial data in the public ECOTOX database ( http://cfpub.epa.gov/ecotox/quick_query.htm ) was conducted in February 2012. This search did not yield any ecotoxicological data on polybutene other than the studies that

ha d been submitted to the EPA and are summarized in Table 4

.

4.3. Ecological Incident Reports

EPA’s Ecological Incident Informat ion System (EIIS) contains a record of two reported

ec ological incident s that are associated with use of polybutene as a repellent in

accordance with the lab el

.

1. Incident I004169

- 042:

The Virginia Department of Game and Inland Fisheries reported on the mo rtality of two house sparrows attributed to the use of 4

- the

- Birds Bird Repellent at a shopping center in Martinsville, Virginia in March, 1991. Beads of product had been applied to an awning at the mall to deter nuisance birds, in accordance to

label directions. One house sparrow was found dead and coated with the sticky product. A second house sparrow was found alive but incapacitated by the coating of product on its feathers. The bird was euthanized by a veterinarian.

2. I ncident I019575

- 001 :

The T anglefoot Company reported that use of the product Ta n glefoot Bird Repellent (97% polybutene, EPA Reg. No. 1621

- 17) resulted in the death of numerous cedar waxwings in early March of 2008 in Richmond, Virginia. The product had been applied to a commercial building to deter roosting of pigeons. There was no evidence that the product was misused. The incident occurred when a flock of cedar waxwings roosted on a treated ledge. The report states that the15 “sticky adhesive came in contact with wings [of the b irds], limiting their ability to fly.” “Approximately 30

- 80” birds were affected, although this count reportedly

includes some bird s that collided with windows, and also some birds that were rehabilitated and released. The exact number of birds that died from direct contact with the bird repellent product is therefore unknown.

One incident was attributed to a misuse of polybutene. The organization Bat Conservation International ( www.batcon.org ) reported on the d eaths of a large number of bats at the campus of the University of Arizona in Tucson in the fall of 1990. The University w as attempting to remove bats, mostly Brazilian free

- tailed bats ( Tadarida

brasiliensis ), that were roosting in expansion joists in th e universit y’s football stadium. An unidentified polybutene bird repellent had been applied. University personnel had also used a fire extinguisher to spray the bats with carbon dioxide to drive them away. Some bats were allegedly killed by the carbon d ioxide, while others were allegedly killed when the polybutene repellent caused the wings of the bats to become permanently stuck to their bodies. Bats are not a registered target pest species for the use of any repellent containing polybutene, and theref ore this use was not a legal use of polybutene.

A search of the American Bird Conservancy’s Avian Incident Management System (AIMS) and the Office of Pesticide Program’s Aggregate Summary database was conducted in February 2012. Neither database contai ned a record of any ecological

incident associated with the use of polybutene.

5. Risk Description

5.1. Aquatic Risk

As discussed in Section 2.2, use of polybutene is generally expected to result in negligible contamination of aquatic habitats. The insolubility of the compound would

prevent more than small traces to be dissolved in water. Considering the low toxicity

o bserved in birds and mammals, and the lack of any know n toxic mode of action to aquatic species, dissolved residues of polybutene are expected to remain far below levels

that might be toxic to aquatic organisms. This conclusion is supported by the findings of acute toxicity testing with the water flea, Daphnia magna (MRID 43382701). When polybutene was mixed with water and then the water soluble fraction was separated from the undissolved test material, no mortality of water fleas occurred when exposed to

nominal concentration s as high as 10,000 mg/L.

Although the very small traces of soluble polybutene are not expected to result in any toxicity, acute toxicity tests indicate that the presence of polybutene in water may cause physical hazards to aquatic or ganisms. In an acute to xicity test with the rainbow trout (MRID 43382702), the insoluble test material formed a surface slick in the test vessels that remained throughout the trials. The surface slick formed a seal between the test solution and the air, causing depletion of dissolved oxygen , and resulting in mortality of

50% of the fish . Introduction of significant quantities of polybutene into a small body of water, such as a small pond, could result in a surface slick and have similar detrimental16

effec ts. In a test with water flea using test solutions containing undissolved test material, mortality occurred when the water fleas became physically entrapped by globules of polybutene. Globules of polybutene in natural aquatic habitats may likewise pose a physical hazard to aquatic invertebrates and possibl y small vertebrates , yet this is considered very unlikely.

Because the product is not mobile, use of polybutene as a bird repellent on buildings, structures, and branches of woody plants is not expected to result in significant amounts of material reaching water. Use as a repellent for beavers, however, could potentially

result in unintentional introduction of polybutene in to aquatic hab itats. The beaver repellent use involves painting or spraying the product to the lower section of tree trunks, from ground level to 2 feet high. As beavers are aquatic mammals, these applications would be made to trees that are near the banks of ponds, streams, and rivers. A r ise in the

water level to a level that submerges the treated section of the tree trunks could cause the applied product to come into direct contact with the water, possibly resulting in a surface slick. Such water rises may occur from flooding due to heavy rain, or flooding resulting from dam building by the beavers. While this risk is uncertain, given the limited and localized use of polybutene products, this scenario is considered un likely and any aquatic exposure is expected to be negligible.

5.2. Terrestrial Risk

5.2.1. Birds, Mammals, Reptiles, and Terrestrial

- Phase Amphibians

Use of polybutene in registered repellent products is not expected to result in toxic effects to terrestrial wildlife. Acute toxicity tests show that polybutene has very low toxicity to birds and mammals. As described in Section 2.3, registered use is not expected to result in contamination of wildlife food items, and animals are not expected to intentionally ingest the tacky inorganic product. Therefore, exposu re and risk from ingestion is believed to be negligible. Exposure to wildlife will likely be limited mainly to dermal exposure from contact with treated surfaces. A dermal toxicity test with “4 the Birds Transparent bird Repellent Liquid” (Reg. No. 8254

- 3, 49% AI) found low toxicity, with

an LD 50 of greater than 2000 mg product/kg bodyweight. As there was one mortality at the 2000 mg/kg dose, however, some dermal toxicity with heavy exposure is possible.

Of greater concern than toxicity is potential r isk of physical impairment of wildlife that may result from contact with this very tacky substance. Larger animals will not likely be significantly impacted, but ecological incidents have shown that small birds may be killed or incapacitated if they come into contact with the product. Small birds that get significant amounts of the products on their wings may be unable to fly. While

entrapment as a result of labeled use has only been observed in small birds, entrapment

could occur with other small verteb rates that may climb on woody vegetation or buildings, such as small lizards, newts, and toads. Based on the physical properties of polybutene, and the application areas, e ntrapment of insects and other terrestrial arthropods is also possible

. The risk of entrapment or entanglement of small mammals is

uncertain.17

P olybutene product labels contain warnings that serve to mitigate entanglement and entrapment of nontarget bird species. All products contain the following statement in the

Environmen tal Hazards section of the label:

Small birds may be fatally trapped by this tacky repellent. To reduce hazards to legally protected species, and to avoid noncompliance with Federal Migratory Bird Treaty Act, follow all instructio n s on the Directions F or U se

.

Some products contain additional label statements to protect birds. These are listed in

Table 5.

Table 5. Label Statement on Polybutene Product Labels for Protection of Nontarget Birds

Product Name EPA Registration

Number Warning Statements

Tanglefoot Bird Repellent 1621

- 17 Do not apply where repellent may entangle desirable bird species, on feeders or on vegetation/structures supporting feeders.

Hot Foot Bird Repellent 55943

- 1 Do not apply on location where desirable birds might become entangled in the repellent.

4

- the

- Birds Repellent 8254

- 5 Do not apply on locations where desirable birds may become entangled by the repellent.

4

- the

- Birds Transparent Bird Repellent Liquid 8254

- 3 Do not apply at locations where birds protected by

the Federal Migratory Bird Treaty Act might become entangled in the repellent.

Or NOTE: Do not apply at locations where the user has concern that desirable birds may become entangled in the repellent.

Do not apply this product directly to trees, bushes

or vi nes that are in bloom or bearing fruit except as indicated on the label for use as a point on the lower areas of tree trunks to discourage damage (debarking and cutting) by beavers.

These label statements are beneficial in informing users of the risk of entanglement of

small birds. The statement on 4

- the

- Birds Transparent Bird Repellent Liquid to not apply to blooming or fruit bearing woody plants would mitigate risk to birds by avoiding use on woody plants that would be attractive to fruit

- eating wildli fe and to nect a r

- feeding birds (e.g., hummingbirds).

In conclusion, use of polybutene is not expected to result in any significant risk to terrestrial wildlife through any toxic mode of action, but may pose some limited risk to small wildlife species that may become entangled or entrapped in the product. The fact that only two incidents of wildlife mortality from labeled use of polybutene have been reported over the several decades these products have been registered suggest s that mortality events are rar e occurrences

. Of the two incidents that were associated with registered use, one (I004169

- 042) involved the mortality of a couple of house sparrows, a very abundant and invasive species. Only one incident has been reported that was not

associated with a misuse and involved mortality of birds protected by the Migratory Bird18

Treaty Act. This incident (I019575

- 001) occurred when a large flock of cedar waxwings happened to reside on a commercial building treated with polybutene , and an unknown

number of bir ds died from entanglement with the product . Such events are considered

rare . In addition, it should be noted that use of this nontoxic repellent likely poses much less risk to nontarget species than use of chemical poisons for excluding pest birds, and

t hus may be s afer than alternative products.

5.2.2. Terrestrial Invertebrates

Because of the risk of entrapment or entanglement, use of polybutene products may pose

a hazard to terrestrial invertebrates, including honey bees and insect pollinators

, if they were to land on a treated surface. However, since invertebrates are not expected to be attracted to typical use sites, such as ledges of buildings, few individuals are expected to be impacted. Only one product, 4

- the

- Birds Transparent Bird Repel lent Liquid , may be used on woody plants. The label statement on this product that prohibits use on woody plants while they are in bloom is expected to effectively mitigate risk of this use to terrestrial invertebrates which feed on nectar and pollen

.

5.2.3. Terrestrial Plants

As described in S ection 2.4, exposure to terrestrial plants is expected to be limited to the woody plants that are treated directly. No evidence exists that this treatment does any harm to the plants that are treated. To date, no such incidents have been reported. Therefore, use of polybutene is not believed to pose any significant risk to terrestrial plants.

6. Risk to Threatened and Endangered Species

C onsidering the low toxicity, non

- toxic mode of action, use pattern and the extremely low water solubility of polybutene, and that aquatic exposure from use of polybutene is expected to be negligibl e
, EFED concludes that the currently registered use s of polybutene as bird and beaver repellents are not reasonabl y expected to cause effects to federally listed threatened and endangered species. Adverse effects to listed plants are not reasonably expected to occur because exposure to plants is expected be limited to the

immediate treatment site , and the chance of o ccurrence of listed plants at the immediate

treatment site is extremely small. Furthermore, exposure of plants to a small amount of synthetic polymer is not expected to result in any adverse effect. For terrestrial animals

, exposure from dermal absorptio n or inadvertent ingestion of the product by listed species is expected to be unlikely, and considering the low toxicity of polybutene, it would not be expected to approach levels that would cause toxicity even if it did occur

. Concerning physical entangl ement with the product

, numerous factors make this very unlikely to

occur to threatened or endangered animal species. These factors are enumerated below.19

1. Treated area is very small relative to the range of species

Polybutene repellent products are designed for treatment of small areas. The package containers contain only enough product for treating a relatively small area. For example, one tube of Tanglefoot®, applied onto a 6

- ft ledge according to directions, would treat only an area of 2.5 ft 2

. Typical use would involve application only to horizontal ledges of buildings and other elevated perching sites immediately adjacent to buildings. Expense and labor of application would likely prohibit persons from treating large areas with this product.

These small use sites of polybutene repell e nt would be widely dispersed across the landscape. They would comprise only a tiny proportion of the home range of a species. Therefore, the likelihood of any particular threatened or endangered animal

encounteri ng a treated surface would be very small.

2. Most use is expected to occur outside of areas inhabited by listed species

Polybutene repellents are registered for repelling nuisance commensal bird (pigeons, house sparrows, and starlings). These species occur mainly in highly developed urban and suburban areas with high human populations. In contrast, listed species generally occur in areas with little human disturbance. Furthermore, except for the

“4

- the

- birds Transparent Liquid,” labels of products allow us e only on buildings and

man

- made structures. Most listed species generally do not routinely alight or climb

on man

- made structures. For example, endangered butterfly species are not likely to use ledges of buildings. Only “4

- the

- birds Transparent Liquid ” may be applied to woody plants for repelling birds and for controlling beaver damage, and the extent of sales of that particular product is very small.

3. Polybutene is an effective physical repellent

Polybutene is an effective tactile animal repellent. Therefore, in case s when animals do encounter a surface treated with the product, they would likely be immediately repelled and move away from the site. There generally would not be food resources associated with treated sites, such as building ledges, to motivate it to use the site. Therefore, listed species that do encounter treated surfaces would be expected to leave the site and avoid the area, thereby preventing further contact.

Because of these mitigating factors

, the EPA concludes that there is no reasonable expectation for any registered use of polybutene repellents to caus e direct or indirect

adverse effects to threatened and endangered species. A “no effect” determination is made for all federally listed species.20

References

Minerath, E.C., M.P. Schultz, and M.J. Elrod. 2009. Kinetics of the reactions of isoprene

- derived epoxides in model tropospheric aerosol solutions. Environ. Sci.

Technol. 43(21):8311

- 81393.

USEPA. 1995. Reregistration Eligibility Decision : Polybuten e. U.S. Environmental Protection Agency. EPA

- 738

- R

- 95

- 0 07 . Washington, DC. Available at: http://www.epa.gov/oppsrrd1/REDs/4076.pdf

USEPA. 199 5 . R.E.D. F acts: Polybutene

. U.S. Environmental Protection Agency. EPA

738

- F

- 9 5

- 0 80 . Washington, DC. Availab le at: http://www.epa.gov/oppsrrd1/REDs/factsheets/4076fact.pdf

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs . United States Environmental Protection Agency (USEPA).

Environmental Fate and Effects Div ision. Office of Pesticide Programs.

Available at http://www.epa.gov/espp/consultation/ecorisk

- overview.pdf