UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D.C., 20460

OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

PC Code: 115001

DP Barcode : D409249
MEMORANDUM Date: August 27

, 201 4

Subject: Registration Review: Draft Ecologica l Risk Assessment and Endangered

Species Effects Determination for Debacarb

To: Roy Johnson, Chemical Review Manager

Jill Bloom , Team Leader Linda Arrington, Branch Chief Risk Management and Implementation Branch V

Pesticide Re

- evaluation Division ( 7508P )

From: Scott Glaberman, Ph.D., Biologist

Environmental Risk Branch IV Environmental Fate and Effects Division (7507P)

Reviewed By: Thomas Steeger, Ph.D., Senior Science Advisor

Jim Carleton, Ph.D., Senior Fate Scientist

Environmental Ris k Branch IV Environmental Fate and Effects Division (7507P)

Approved By : Sarah Winfield, Acting Branch Chief

Environmental Risk Branch IV Environmental Fate and Effects Division (7507P)

The Environmental Fate and Effects Division (EFED) has co mpleted the preliminary ecological

risk assessment and endangered species effects determination for the benzimidazole carbamate fungicide debacarb ( first registered in 1982 )

. The only currently registered use of debacarb is as a tree injection to ornament al trees in which the compound is distributed systemically throughout

the tree

.

Since debacarb is used exclusively as a tree injection and is used to treat a low number of estimated trees per year across the U.S., the potential for exposure to aquatic re ceptors as well as non

- target terrestrial plants is expected to be minimal. Although there is some uncertainty in the potential for exposure to aquatic systems from the shedding of leaves from trees treated with debacarb, EFED believes that potential risk s to these systems may be reduced via use restrictions

.

In terms of potential risks of debacarb to terrestrial animals ( i.e. , birds

, mammals, reptiles,

terrestrial

- phase amphibians, and terrestrial invertebrates ), there is a limited hazard dataset to carry out quantitative risk assessment. However, based on a conservative risk analysi s performed usinga composite dataset of deba carb and carbendazim (a carbamate fungicide with a similar structure ),

usage of debacarb is not expected to result in risks o f conc ern to birds ( or to terrestrial

- phase amphibians and reptiles for which birds serves as a surrogate ) and mammals

.

There is uncertainty surrounding potential risk s of debacarb and its end

- use products to insect pollinators. Debacarb is systemic, and may b e translocated to pollen and nectar of treated trees

, indicating that exposure to honeybees ( Apis mellifera ) or other insect pollinators is possible through ingestion of residues in pollen/nectar

. Since no toxicity data are available for honeybees exposed to debacarb , it is not possible to rule out the potential for risks of concern to insect pollinators

. While a relatively low number of trees are estimated to be treated with debacarb each year across the U.S., the magnitude of this uncertainty, in part, de pends on whether groups of trees
are treated in close proximity to each other, at similar times

, and during parts of the year when residues are more likely to be translocated to pollen or nectar, all of which would be more likely

to result in exposure. It should be noted that data were previously recommended on the fate, uptake, and translocation of debacarb in order to estimate potential exposures to insect pollinators (USEPA, 2008), but were not submitted. It is also important to note that two of the form ulated products containing debacarb ( i.e

., Imisol ® and Abasol ® ) contain the systemic insecticides imidacloprid (CAS No. 138261

- 41

- 3) and avermectin (CAS No. 71751

- 41

- 2)

, respectively, which are highly toxic to honeybees on an acute exposure basis

. The curr ent label for Abasol ® indicates

that the product should only be used as a post

- bloom application, while the label s for Imisol ® and Fungisol ® do not have any application restrictions relative to bloom. EFED believes that use restrictions could potentially r educe the uncertainty and risks associated with the exposure of pollinators to residues in pollen and nectar.

There is also uncertainty surrounding potential risks of debacarb and its end

- products to terrestrial invertebrates in general since some species may consume various edible plant parts containing

translocated residues ( e.g. , leaves, fruit) and since there are no available t oxicity data for debacarb for any species of terrestrial invertebrate

.

Since direct adverse effects are not expected for birds , reptiles, terrestrial

- phase amphibians, mammals, or terrestrial plants, the EPA makes a No Effects (NE) determination for all Federally

listed species within these groups and a No Habitat Modification determination for all designated

critical habitats as sociated with these species for the currently registered uses of debacarb. Risks

to listed aquatic organisms from the use of debacarb may potentially be mitigated via label amendment, but effects and habitat modification determinations cannot be made at th is time. R isks of concern cannot be precluded for listed terrestrial invertebrates , so effects and habitat

modification determinations also cannot be made at this time

.1 REGISTRATION REVIEW

Draft Ecological Risk Assessment and Endangered Species Effects Determination for:

Debacarb ( 2

- EEEBC)

(CAS Reg. No. 62732

- 91

- 6 ; USEPA PC Code # 115001 )

2

- (2

- ethoxyethoxy) ethyl

- 2

- benzimidazole carbamate

Prepared by:
Scott Glaberman , Ph

. D

. , Biologist

Reviewed by: Thomas Steeger, Ph.D., Senior Sci ence Advisor Jim Carleton, Ph.D., Senior Fate Scientist

U. S. Environmental Protection Agency Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch 3 1200 Pennsylvania Ave., NW

Mail Code 7507P Washington, DC 20460

August 27 , 20142 TABLE OF CONTENTS

1. PROBLEM FORMULATION

................................ ................................ ........ 3 Nature of Regulatory Action

................................ ................................ ................................ ....... 3

Previous Assessments

................................ ................................ ................................ ................. 3

2. STRESSOR SOURCE AND D ISTRIBUTION

................................ .............. 3

Pesticidal Mechani sm of Action

................................ ................................ ................................ . 3 Overview of Pesticide Use and Usage

................................ ................................ ........................ 3 Environmental Fate and Transport

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

3. RECEPTORS

................................ ................................ ................................ .... 5 Ecological Effects

................................ ................................ ................................ ....................... 5 Ecological Incidents

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

4. ASSESSMENT ENDPOINTS

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

5. CONCEPTUAL MODEL

................................ ................................ ................ 8 Risk Hypothesis

................................ ................................ ................................ .......................... 9 Conceptual Diagram

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

6. ANALYSIS

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

Stressors of Concern

................................ ................................ ................................ ................. 11 Measures of Exposure

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

Measures of Effect

................................ ................................ ................................ .................... 13 Integration of Exposure and Effects

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

7. RISK CHARACTERI ZATION

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

Risk Estimation

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

8. ENDANGERED SPECIES ASSESSMENT

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

9. ENDOCRINE DISRUPTOR SCREENING PROGRAM

........................... 19

10. REFERENCE S

................................ ................................ ................................ 193

1. PROBLEM FORMULATION

Nature of Regulatory Action

As part of the implementation of the Registration Review program pursuant to Section 3(g) of FIFRA, the Agency is evaluating all curren t and active registrations for debacarb ( 2

- (2

- ethoxyethoxy) ethyl

- 2

- benzimidazole carbamate ) to determine whether it continues to meet the FIFRA standard for registration. The structure of this risk assessment is based on guidance contained in U.S. EPA’s Guidance for Ecological Risk Assessment (USEPA

, 1998 ).

Previous Assessments

Debacarb is registered for use only as a tree injec tion. Given this application method, it has historically been viewed as a “closed system” with minimal likelihood of environmental exposure (USEPA, 2008) . Therefore, there are no previous ecological risk assessments or drinking water
exposure assessments for this chemical.

2. STRESSOR SOURCE AND DISTRIBUTION

Pesticidal Mechanism of Actio n

Debacarb is a fungicide belonging to the benzimidazole carbamate class of pesticides. Benzimidazole toxicity is based on the inhibition of the formation of spindle fibe rs at nuclear

division (mitosis/meiosis) , which results in the inhibition of deoxyribonucleic acid (DNA) replication (Davidse, 1986)

Overview of Pesticide Use and Usage

Debacarb was originally registered for use in the United States in 1982. It is used to prevent and treat certain fungal diseases in ornamental trees. Currently, debacarb is registered for use only as a tree injection application to ornamental trees. There are three active Section 3 products containing deba carb

, i.e

., Imisol ® (Reg. No. 794 6

- 21, Abasol ® (Reg. No. 7946

- 20 ) , and Fungisol ®
(Reg. No. 7946

- 14). All three products are co

- formulated with the fungicide carbendazim (PC 128872; CAS # 10605

- 21

- 7). According to correspondence with the registrant (J.J Mauget) in the 1990s, debacarb and carbendazim are manufactured from benomyl (PC 099101 ; CAS No. 17804

- 35

- 2 ), and it is technically infeasible to separate the two (letter from Donald Diamond, attorney representing J.J. Mauget Co., dated June 10, 1992). It should be noted however, that car bendazim is registered as an active ingredient in other pesticides in which debacarb is not claimed as an active ingredient or impurity. I n addition, Imisol ® is co

- formulated with the insecticide imidacloprid (PC 129099, CAS No. 138264

- 41

- 3) and Abasol ® is co

- formulated with avermectin (PC 122804, CAS No. 71751

- 41

- 2).

Use Rates

All three debacarb

- containing products consist of 4 or 6 mL (product) capsules that are injected

via a closed micro

- injection system consisting of a feeder tube and compressible injector unit (the4

“Mauget System” 1 ). The maximum number of capsules allowed per treatment is determined by the size of the tree as measured by the diameter at breast height (DBH). For trees with 2

- 10 inch DBH, the 4

- mL capsules are prescribed, and for t rees with a DBH greater than or equal to 10 inches, the 6

- mL capsules are prescribed. According to the label, treatments of trees smaller than 2 inches DBH are not allowed. The maximum number of capsules per treatment is determined by dividing the DBH by two. If this results in a fraction, the label instructs the applicator to round down to the nearest whole number. For example, for a tree with a DBH of 16 inches the label allows for the injection of a total of eight 6

- mL capsules per treatment. Repeat treatments are recommended if disease symptoms progress, but are not allowed within 3 months of the first application. The label does not appear to limit the number of applications per year after the required three month interval following the first appli cation. Debacarb comprises 1.7% (w/w) of all three products (approximately 0.1 g a.i. per 6

- mL capsules and 0.07 g a.i. per 4

- mL capsules). Based on label instructions, the amount of debacarb applied to individual trees through injection of capsules

was c alculated for trees of varying DBH values ( Table 1 ). This information is used in later sections of the risk assessment to estimate potential exposure and effects to organisms consuming food

items from trees treated with debacarb

Table 1. Tree size and use parameters

Tree Diameter

at Breast Height (inches) Size of

Capsules (ml) Number of

Capsules per

Tree Total Volume

of Formulation per Tree (ml) Total Grams of

Debacarb per

Tree per Application *

2 4 1 4 0.068

10 4 5 20 0.34

16 6 8 48 0.82

24 6 12 72 1.2

32 6 16 96 1.6

* Total grams ai per tree per application = total volume (ml) per tree * 0.017 (percent a.i. w/w)

Estimated Usage

The registrant estimated the number of trees treated with Fungisol ® across five regions of the

United States based on sales data and reported this information to EPA ( Table 2 ). It should be

noted that information on the estimated number of trees treat ed with t he other two tree injection

end

- us e products was not available at the time of this assessment. However, sales data prov ided to

EPA by the registrant indicate that Fungisol ® is used more than both Imisol ® and Abasol ®

combined ( confidential data, not shown)

.

Table 2 . Estimated number of trees treated with the product, Fungisol ® in various regions

and in total for the United States

U.S. Region Number of trees treated with
Fungisol ® (2011) Number of trees treated with
Fungisol ® (2012)

Northeast 3,293 3,057

Southeast 797 617

Northwest 297 384

Southwest 1,862 2,947

1 An example of the Mauget Syst em can be viewed at: http://www.youtube.com/watch?v=4j1aezoAtbE (last accessed 06/19/2014).5

Midwest 5,152 5,192

Total 11,401 12,197

Environmental Fa te and Transport

Best

- available data defining the physical, chemical, fate and transport characteristics associated

with debacarb are summarized in Table 3 . Since products containing debacarb are used to treat diseases such as canker, wilts, and blight, w hich may occur in tree trunks, limbs, and leaves, the compound is most likely systemic and translocated to different parts of the plant. There are currently no registrant

- submitted data characterizing the fate and transport of debacarb in the

environment

. According to the Registration Memo, all environmental fate data requirements were waived during registration in 1993 . E nvironmental fate data on the uptake and translocation of debacarb in plants was previously recommended (USEPA, 2008), but were not subm itted. Based

on estimations from the Estimation Program Interface Suite 2 ( EPISuite TM ; v3.2 ) , debacarb is soluble, and volatilization and bioaccumulation are not likely. Based on the Biodegradation Probability Program (BIOWIN TM ) component of EPISuite TM , which estimates the probability for the rapid aerobic biodegradation of an organic chemical in the presence of mixed populations of environmental microorganisms , debacarb is not likely to biodegrade quickly , and ultimate biodegradation is expected on the order of week s to months (Howard et al ., 1992)

.

Table 3. General chemical and environmen tal fate properties of debacarb

Chemical/Fate parameter Value Source

Molecular Weight (g/mol) 293.33

Vapor Pressure (torr) 7.8 x 10

- 10 Estimated EPISuite TM v3.2

Octan ol

- water Partition Coefficient (Log K OW ) 1.5 Estimated EPISuite TM v3.2

Water Solubility (mg/L; at 25 °C) 710 Estimated EPISuite TM v3.2

Henry's Law Constant (atm

- m 3 mol

- 1 ) 4.8 x 10

- 16 Estimated EPISuite TM v3.2

Biodegradation (mixed populations of

environmen tal microorganisms) Does not biodegrade quickly Not readily degradable Ultimate biodegradation:

weeks

- months Estimated EPISuite TM v3.2

(BIOWIN v4.10)

3. RECEPTORS

Ecological Effects

There are limited ecological effects data available for debacarb ( Tabl e 4 ). Debacarb is classified as slightly toxic to practically non

- toxic to birds on an acute oral exposure basis (Acc. No. 00046490, 00046491 ) , and practically non

- toxic to birds on a sub

- acute dietary exposure basis (Acc. No. 00072903 )

. In an acute oral toxicity study with mallard ducks ( Anas platyrhynchos ; Acc. No. 00046490 ), some lethargy, loss of coordination, and lower limb weakness was observed in birds at 1,590 and 2,510 mg/kg doses. Debacarb is classified as practically non

- toxic to

2 USEPA. 2013. Estimation Program Interface Suite (EPI Suite). http://www.epa.gov/opptintr/exposure/pubs/episuite.htm

.6

mammals on an acute oral exposure basis (Acc. No. 244391 )

. Acute oral mammalian toxicity data requirements were waived for the combination products Abasol ® and Imisol ® . There are no data

on the chronic effects of debacarb on birds and mammals. Chronic studies do exist f or carbendazim, which is also a benzimidazole fungicide with a similar structure to debacarb ( Appendix A )

. Therefore, data are bridged in this assessment between debacarb and carbendazim

in cases where data are not available for the former.

In a chronic rat study with carbendazim, decreased pup weight s were noted at weaning resulting in a NOAEC and LOAEC of 500 and 5,000 mg/kg

- diet, respe ctively (Acc. No. 0008833 3 )

. It

should also be noted that in an acute oral toxicity test conducted with carbend a zim on rats (Acc. No. 256025) , single doses of 1,000 mg and above resulted in adverse effects to the testes and caused depressed or absent spermatogenesis. In addition, when rats were administered ten doses

of carbendazim over a two

- week period at a single rate o f 5,000 mg/kg

- bw /day, spermatogenesis

ceased with no evidence of recovery (Acc. No. 256025) . Given the structural similarity between debacarb and carbendazim, implications for these potentially reproductively relevant sublethal

effects will be discussed in the Risk Characterization section of this document.

Data on the toxicity of debacarb and i ts formulated products to honey bees ( Apis mellifera ) are not

available . Several honeybee toxicity studies (acute contact, 850.3020; acute oral, non

- guideline;

folia ge residue toxicity, 850.3030; field testing for pollinators, 850.3040) were previously

recommended but were not submitted. It is important to note that two of t he formulated products,

Imisol ® and Abasol ® , contain systemic insecticides that are highly to xi c to honey bees. The Imisol ®
product is co

- formulated with imidacloprid, an insecticide with a 48

- hr acute contact LD 50 value of 0.0039 μg a.i. /bee. The Abasol ® product is co

- formulated with avermectin, an insecticide that is also highly toxic to bees wit h a 48

- hr acute contact LD 50 value of 0.41 μg a.i. /bee. The third formulated product, Fungisol ® , is co

- formulated with carbendazim, a fungicide that is practically

non

- toxic to bees with a 48

- hr acute contact LD 50 value of >50 μg a.i. /bee.

Based on a sea rch of the public version of EPA’s ECOTOX database 3 on June 19 , 2014, no relevant open literature data for terrestrial animals w ere identified for use in this assessment.

There are no submitted toxicity data for effects to terrestrial plants. However, bas ed on the use
patter n , exposure to non

- target terrestrial plants is not considered likely and will not be assessed.

No valid registrant

- submitted aquatic toxicity studies with either plants or animals are available

for debacarb. N o aquatic toxicity studie s were recommended by EFED during the Registration Review Preliminary Problem Formulation (USEPA, 2008) because exposure to aquatic ecosystems was expected to be minimal based on the limited use pattern (ornamental tree injection). The uncertainties surrou nding the assumption of minimal exposure are addressed in the Risk Description section

.

3 http://cfpub.epa.gov/ecotox/7

Table 4

. Summary of most sensitive endpoints from submitted terrestrial toxicity studies

for debacarb

Species (common name) Taxa

Represented End

point Mean

Concentrati on (adjusted for % purity) Test Substance

(% a.i.) Citation

MRID Acute Toxicity

Classification

Rattus norvegicus (Laboratory Rat) Mammals LD 50 13,500 ( 229.5 ) mg ai/ kg

- bw Formulation

( Fungisol ® ; Debacarb: 1.7 ; MBC: 0.3 ) 241406 Moderately

Toxic

LD 50 > 5 ,0 00 (4,000) mg

a

. i

. / kg * 80 † ‡ 244391 Practically non

toxic

NOAEL 500 mg/kg

- diet

25 mg/kg

- bw ( MBC) (decreased weight gain) 50 or 70 0008833 3 N/A

LOAEL 5,000 mg/kg

- diet

250 mg/kg

- bw (MBC)

Anas platyrhynchos (Mallard Duck) Birds LD 50 .>2,51 0 (2,0 08) mg/kg 80 ‡ 00046490 Practically non

toxic

LD 50 ≥ 1,000 (800)

mg/kg 80 ‡ 00046491 Slightly toxic

LC 50 > 5,620 (4,496)

mg/kg

- diet 80 ‡ 00072903 Practically non

toxic

NOAEC 322 (MBC)

( Viable embryos, normal hatchlings, 14 day survivors ) N/A § 4410300 2 N/A

LOAEC 720 (MBC) N/A

Colinus virginianus (Northern

Bobwhite Quail) LC 50 > 5,620 (4,496) mg/kg

- diet 80 ‡ 00046492 Practically non

toxic

NOAEC 3,600 (MBC)
N/A § 44103001 N/A LOAEC >3,600 (MBC)

Apis mellifera (Honey Bee) Insect

Pollinators LD 50 >50 μg/bee (MBC) 99.3 00154695 Practically non

toxic MBC = methyl 2

- benzimidazole carbamate (carbendazim)

* Note: irreversible spermatogenic effects observed in subchronic studies

† Information on percent a.i. was not provided in study report, but was deduced by the risk assessor by matching the test substance lot number (0B07) to other ecological effects studies submitted to EFED with the same lot number for which the percent a.i. was reported. The reported endpoint for this study was 5,000 mg/kg

- b w, and was adjusted to 4,000 mg ai/kg

- bw based on the assumed 80% a.i.

‡ Based on the data review for MRID 0046491, the use of 80% debacarb active ingredient as technical is due to the inability to separate deb acar b, carbendazim, and 2

- amino

- benzimidazole in the production process. Apparently, the technical product used for these tests was produced solely for testing purposes.

§ Endpoints based on measured MBC in diet for test with benomyl8

Ecological Incidents

Reviews of the Ecological Incident Informa tion System (EIIS, version 2.1), the Avian Incident Monitoring System (AIMS) 4

, and the Incident Data System (IDS) were conducted on June 19

, 2014

. There were no reported ecological incidents associated with debacarb ; however, as with other chemicals, given th e limited reporting of incidents, the absence of incident reports cannot be

construed as the absence of incidents.

4. ASSESSMENT ENDPOINTS

Based on current registered use patterns, the ecological entities that are relevant to debacarb in this

assessment inclu de birds, mammals, and insect pollinators that feed on translocated residues of debacarb in fruit, seeds, foliage, and pollen. The attributes for each of these entities may include growth, reproduction, and survival. A summary of the terrestrial toxicolog ical endpoints for

debacarb can be found in Table 3 of the Ecologic al Effects section

. In cases where no guideline toxicity data were available for debacarb, data were bridged from carbendazim, a carbamate fungicide with a similar molecular structure to d ebacarb.

For aquatic organisms, no valid registrant

- submitted aquatic toxicity studies with either plants or animals are available for debacarb and were not recommended by EFED during the Registration Review Preliminary Problem Formulation (USEPA, 2008) because exposure to aquatic ecosystems was expected to be minimal based on the limited use pattern (ornamental tree injection). Therefore, specific assessment endpoints for aquatic organisms are not considered in

this assessment.

5. CONCEPTUAL MODEL

For a p esticide to pose an ecological risk, it must reach ecological receptors in biologically significant concentrations. An exposure pathway is the means by which a pesticide moves in the environment from a source to an ecological receptor. For an ecological pathway to be complete, it must have a source, a release mechanism, an environmental transport medium, a point of exposure for ecological receptors, and a feasible route of exposure.

The conceptual model for debacarb provides a written description and vis ual representation of the predicted relationships between debacarb, potential routes of exposure, and the predicted effects for the assessment endpoint. A conceptual model consists of two major components: risk hypothesis and a conceptual diagram (USEPA 19 98).

Based on the use pattern and mode of action, risk s to birds, mammals and terrestrial invertebrates, including insect pol l inators

, are possible

. Because of the potential risk from direct effects to the se taxa, potential concerns exist for indirect ef fects for food, habitat, and/or pollination

. This forms the basis of the risk hypothesis and conceptual diagram discussed below.

In this assessment, the potential for exposure and risk to plants from debacarb is considered to be

minimal based on the lim ited tree injection use pattern

. The potential for exposure and risk to

4 http://www.abcbirds.o rg/abcprograms/policy/toxins/aims/aims/login.cfm?CFID=113048231&CFTOKEN=92434829

aquatic organisms is considered uncertain since leaves shed from trees treated with debacarb could potentially enter aquatic systems; however, EFED believes that potential risks to the se systems may be reduced via use restrictions. Therefore, risk s to plants and aquatic organisms are

not con sidered in the risk hypothesis.

Risk Hypothesis

A risk hypothesis describes the predicted relationship among the stressor, exposure, and

assessmen t endpoint response along with the rationale for their selection. For debacarb, the following ecological risk hypothesis is being employed for this ecological risk assessment:

Based on the application method, mode of action, fate and transport, and the s ensitivity of

non

- target terrestrial species, debacarb has the potential to reduce survival, reproduction, and/or growth in non

- target terrestrial animals including birds, mammals, and invertebrates, including insect pollinators

, when used in accordance wi th the current label

. These non

- target organisms include f ederally listed threatened and endangered species as

well as non

- listed species.

Conceptual Diagram

Given the specificity of the tree injection use pattern, the only viab le transport mechanism co nsists of translocation/uptake to various parts of treated trees, including foliage, fruit, se eds, and pollen

. The transport mechanism ( i.e ., source) is depicted in the conceptual model below ( Figure 1 ) along with the receptors of concern and the potentia l attribute changes in the receptors due to exposures of debacarb. The conceptual model also depicts the potential for debacarb residues in leaves, fruits, and seeds to drop into adjacent water bodies; however, exposures to aquatic receptors via this path way are expected to be minimal given the limited tree injection use pattern. However, the uncertainty surrounding this assumption is discussed in the Risk Description.10

Figure 1 . Conceptual model for debacarb effects on terrestr ial organisms

. Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk. 

### Stressor

Source

Receptors

Attribute Change Debacarb applied to use site (tree injection)

Direct application

Individual organisms

Reduced survival Reduced growth Reduced reproduction Terrestrial food items (var ious parts of tree, including fruit, seeds, foliage, nectar, pollen)

Mammals 

### Exposure

Media

Direct Contact/

Ingestion Ingestion Ingestion Translocation/uptake

Birds Terrestrial

insects Aquatic Organisms Shedding

leaves11

6. ANALYSIS

In order to address the risk hypothesis, the potential for adverse effects to non

- target organisms is

estimated. The use, environmental fate, and e cological effects of debacarb are characterized and integrated to assess risk by using a risk quotient (ratio of exposure concentration to effects concentration) approach when possible

. When a risk quotient approach is not possible, risks are assessed qual itatively.

Stressors of Concern

Due to the limited use pattern, there are no environmental fate data for debacarb. The route of exposure to terrestrial organisms is through uptake and translocation of debacarb to various parts of treated trees, includin g foliage, fruit, seeds, nectar, and pollen which can in turn be used as food items by other organisms. There are no data on the rate of translocation or decay of debacarb in ornamental trees nor have transformation products been identified. Biodegradati on modeling suggests that debacarb is not likely to biodegrade quickly , and ultimate biodegradation is expected on the order of week to months. As such, the focus of this assessment is expected to be the parent, debacarb, with the assumption that it does not degrade appreciably in trees. Additionally, formulated products containing avermectin (Abasol ® ) and imidicloprid (Imisol ® ) will be considered with respect to potential adverse effects on insect pollinators.

Measures of Exposure

The route of exposur e to terrestrial organisms is through uptake and translocation of debacarb to foliage/fruit/ seeds/nectar/ pollen which can be used as food items. Biodegradation modeling suggests that debacarb is not likely to biodegrade quickly , and ultimate biodegradatio n is expected on the order of week to months. No environmental fate data pertaining to the amount and rate of

translocation and /or decay of debacarb in trees following application are available to facilitate estimation of potential residues in foliage/fru it/seeds/nectar/pollen which can be used as food items for terrestrial organisms. Therefore, as a conservative screening approach, it will be assumed that the total amount of debacarb applied to the target tree will be evenly distributed throughout the

fol iage ( i.e. , leaves) , and that terrestrial animals feed exclusively on foliage (a surrogate for other

non

- woody food items such as fruit) from trees treated with debacarb.

For estimating residues of debacarb in foliage , both hardwood (typically deciduous) and softwood (typically evergreen) trees are considered , since debacarb may be applied to both types of trees. Leaf biomass (dry weight) for hardwoods and softwoods were estimated using equations described

in Jenkins et al . 2004 an d parameter values from Sollins ( 1973 ), as follows:

Estimate b iomass of foliage for hardwood an d softwood trees:

General hardwood equation for dry weight (Sollins et al ., 1973)

ln leaf biomass (kg) =

- 3.862 + 1.74*(ln(dbh [ in cm ] ))

General softwood equation for dry weight (So llins et al ., 1973): ln leaf biomass (kg) =

- 2.907 + 1.674*(ln(dbh [ in cm ] ))12

Reverse natural log (ln) of leaf biomass: Leaf bio mass = e ln leaf biomass

The correction for bias when converting from ln to arithmetic units = 1.34 (Sollins et al., 1973) : Leaf biomass (corrected) = (uncorrected weight)*1.34

For leaves, 85 percent (mean) of the wet weight is water (USEPA, 1993); therefore, the general equation to convert leaf dry weight into wet weight is: Leaf wet weight = (100% total leaf wei ght) *(kg of leaf dry weight)/ (% leaf dry weight)

Table 5 summarizes the estimated dry and wet leaf biomasses for trees of varying DBH values.

Table 5

. Summary of Leaf Biomass for Different Tree Diameters

Tree Diameter at Breast Height (inches) Hardwood Trees So ftwood Trees

Dry Weight

Leaf Biomass (kg) Wet Weight

Leaf Biomass (kg) Dry Weight

Leaf Biomass (kg) Wet Weight Leaf

Biomass (kg)

2 0.48 3.18 1.11 7.42

10 7.84 52.26 16.46 109.70

16 17.76 118.40 36.14 240.94

24 35.96 239.74 71.25 474.99

32 59.32 395. 49 115.32 768.83

For simplicity, i t is conservatively assumed that the entire application of debacarb will accumulate in the leaves (a surrogate for other non

- woody food items such as seeds) of the tree. To determine the dietary concentration ( i.e.

, EEC ) of debacarb in the leaves of hardwoods and softwoods, the

total debacarb application amount per tree is divide d by the total leaf biomass (based on wet weight) of the tree . Results are presented in Table 6 . For example

, for a hardwood tree of 2 inch

DBH

, 68 mg a

. i

. /tree ( from Table 1 ) is applied to the tree and is divided by 3.18 kg foliage wet weight (from Table 5 )

, resulting in a concentration of 21.4 mg a

. i

. /kg

- leaves . The resulting EECs are used as an estimate of the dietary concentration of debacarb in bird and mammal food items.

Table 6

. Summary of EECs (unadjusted) for Debacarb Residues in Tree Foliage for

Different Tree Diameters

Tree Diameter at Breast Height (inches) Concentration (mg a

. i

. /kg

- leaves)

Hardwood Trees Softwood Trees

2 21.41 9.1 7

10 6.51 3.10

16 6.93 3.40

24 5.01 2.53

32 4.05 2.08

In order to obtain dose

- based exposure estimates for birds and mammals, the dietary EECs must be adjusted for mammal and bird body weight s ( Table 7 and 8 )

. EFED’s terrestrial exposure13

model, T

- RE X 5

, uses three size classes for mammals: 15, 35, and 1000 g , and three size classes

for birds: 2 0, 100, and 1000 g . According to the T

- REX User’s Manual 6 , a 15

- g mammal consumes 95 percent of its body weight daily, a 35

- g mammal consumes 66 percent of it s body weight daily,

and a 1000

- g mammal consumes 15 percent of its body weight daily. A 20

- g bird consumes 114 percent of its body weight daily, a 100

- g bird consumes 65 percent of its body weight daily, and a 1000 g bird consumes 29 percent of its body w eight daily

.

Consequently, the general equa tion for determining the debacarb dose per day is: EEC mg a

. i

. /kg

- bw = (dietary concentration mg a

. i

. /kg

- diet)*(body weight consumption kg

- diet/kg

- bw).

For example, for a 15

- g mammal feeding on a 2 DBH hardwood t ree, EEC = 21.4 mg a

. i

. /kg

diet)*(0.95 kg

- diet/kg

- bw) = 20.34 mg a

. i

. /kg

- bw

.

The estimated exposure values presented in Tables 7 and 8 will be combined with available toxicity data for mammals and birds for RQ calculations in this assessment.

Table 7

. Summary of Mammalian Body Weight

- Adjusted EECs for Different Tree

Diameters

Tree Diameter at Breast Height (inches) Hardwood Trees Softwood Trees

Dietary

Concentrations (mg/kg

- diet) Dose

- Based

Concentrations (mg/kg

- bw) Dietary

Concentrations (mg/kg

- diet ) Dose

- Based Concentrations (mg/kg

- bw)

15g 35g 1000g 15g 35g 1000g

2 21.41 20.34 14.13 3.21 9.17 8.71 6.05 1.38

10 6.51 6.18 4.29 0.98 3.10 2.94 2.05 0.46

16 6.93 6.58 4.57 1.04 3.40 3.23 2.25 0.51

24 5.01 4.76 3.30 0.75 2.53 2.40 1.67 0.38

32 4.0 5 3.84 2.67 0.61 2.08 1.98 1.37 0.31

Table 8

. Summary of Avian Body Weight

- Adjusted EECs for Different Tree Diameters

Tree Diameter at Breast Height (inches) Hardwood Trees Softwood Trees

Dietary

Concentrations (mg/kg

- diet) Dose

- Based

Concentrations (m g/kg

- bw) Dietary

Concentrations (mg/kg

- diet) Dose

- Based Concentrations (mg/kg

- bw)

20 g 100 g 1000g 2 0g 100 g 1000g

2 21.41 24.40 13.91 6.21 9.17 10.45 5.96 2.66

10 6.51 7.42 4.23 1.89 3.10 3.53 2.01 0.90

16 6.93 7.90 4.50 2.01 3.40 3.88 2.21 0.99

24 5 .01 5.71 3.25 1.45 2.53 2.88 1.64 0.73

32 4.05 4.61 2.63 1.17 2.08 2.37 1.35 0.60

Measures of Effect

Where available, sublethal effects observed in both registrant

- submitted and open literature studies

are evaluated qualitatively. In the available deb a carb toxicity studies, s uch effects include

5 http://www.epa.gov/oppefed1/models/terrestrial/

6 http://www.epa.gov/oppefed1/models /terrestrial/trex/t_rex_user_guide.htm14

lethargy, lo ss of coordination, lower limb weakness, and slight reduction in body weight gain (not statistically evaluated) , as well as decreased or absent spermatogenesis (based on carbend a zim)

. Quantitative assessments of risks, though, are limited to those endpoints that can be directly linked to the Agency’s assessment endpoints of impaired survival, growth and reproduction.

The assessment of risk for direct effects to non

- target organisms makes the assump tion that in the absence of data to the contrary, toxicity of debacarb to birds is similar to that for terrestrial

- phase amphibians and reptiles. However, the appropriateness of birds as surrogates for these other groups is discussed in the Risk Descriptio n. The acute measures of effect used for animals in this screening

- level assessment are the acute LD 50 and LC 50 . Endpoints for chronic measures of exposure for listed and non

- listed animals are the NOAEL and/ or NOAEC.

Integration of Exposure and Effec ts

Risk characterization is the integration of exposure and ecological effects characterization to determine the potential ecological risk from the use of deb a c ar b for tree injections

, and the

likelihood of direct and /or indirect eff ects to non

- target org anisms in terrestrial habitats. For terrestrial organisms, t he exposure and toxicity data are integrated in order to evaluate the

likelihood of adverse ecological effects to non

- target species from exposure, i.e , risk . For the

assessment of debacarb expos ure and potential risks associated with the tree injection use , the risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are divided by the acute and chronic toxicity values (if available) . The resulting RQ value s are then compared to the Agency’s LOC value s (USEPA

, 2004) (see Table 9 )

. These criteria are used , in addition to other available data ( e.g ., incident data), to indicate when debacarb’s uses, as directed on the label, have the potential to cause adverse direc t or indirect effects to non

- target organisms.

TABLE 9

. Agency Levels of Concern (LOC) for Birds and Mammals

Risk Description RQ

Acute Potential for acute risk to non

- target organisms

which may war rant regulatory action in addition

to restricted use classification acute RQ > 0.5

Acute Listed Species Listed species may be potentially affected by

use acute RQ > 0.1

Chronic Potential for chronic risk may warrant

regulatory action, listed species may potentially be affected through chronic exposure chronic RQ > 115

7. RISK CHARACTERIZATIO N

Risk Estimation

Mammals

The only available mammalian acute oral toxicity study for debacarb technical is non

- definitive

and resulted in an LD 50 >4,000 mg a

. i

. / kg

- bw

. In addition, an acute oral mammalian study is available for the Fungiso l ® end

- product ( LD 50 = 229.5 mg a

. i

. /kg

- bw )

. For screening

- level
assessment purposes, RQs were calculated based on the LD 50 for Fungisol ® ( 229.5 mg a

. i

. /kg

- bw )

since it is more sensit ive than the technical

. Since chronic toxicity data were not available for debacarb, chronic RQs for debacarb were calculated based on a NOAEC of 500 mg/kg

- diet (35 mg/kg

- bw), which was the lowest rat two

- generation toxicity endpoint value for carbendazim. In

order to calculate acute and chronic dose

- based RQs for mammals, LD 50 and NOAEC values were corrected using a scaling factor of 1.15 (from Mineau et al ., 1996) as implemented in T

- REX 7

, resulting in LD 50 values of 504

, 408 , and 177 mg a.i. /kg

- bw for 15

- , 35

- , and 1000

- g sized

mammals , respectively, for the Fungisol ® end

- product

, and NOAEC va lues of 55, 44, and 19 mg

a.i. /kg

- bw

.

A cu te dose

- based screening

- level RQs for Fungisol ® are presented in Table 10 and are below the

acute risk LOC of 0. 1 for liste d mammals. C hronic RQs are presented in Table 11 and do not
exceed the chronic risk LOC o f 1 for mammals

.

Table 10 . Acute Risk Estimates for Mammals

Tree Diameter at Breast Height (inches) Acute Dose

- Based RQs

Hardwood Trees Softwood Trees

15g 35 g 100 0g 15g 35 g 1000g

2 0.04 0.03 0.02 0.02 0.01 0.01

10 0.01 0.01 0.01 0.01 0.01 < 0.0 1

16 0.01 0.01 0.01 0.01 0.01 < 0.0 1

24 0.01 0.01 < 0.0 1 < 0.0 1 < 0.0 1 < 0.0 1

32 0.01 0.01 < 0.0 1 < 0.0 1 < 0.0 1 < 0.0 1

Table 11

. C hronic Risk Estimates for Mammals

Tree Diameter at Breast Height (inches) Chronic Dose

- Based RQs Chronic Dietary

- Based RQs

Hardwood Trees Softwood Trees Hardwood

Trees Softwood

Trees 15 g 35 g 1000g 15 g 35 g 1000g

2 0.37 0.32 0.17 0.16 0.14 0.07 0.04 0.02

10 0.11 0.10 0.05 0.05 0.05 0.02 0.01 0.01

16 0.12 0.10 0.05 0.06 0.05 0.03 0.01 0.01

24 0.09 0.07 0.04 0.04 0.04 0.02 0.01 0.01

32 0.07 0.06 0.03 0.04 0.03 0.02 0.01 <0.01

7 http://www.epa.gov/oppefed1/models/terrestrial/16

Birds

The only available avian acute oral toxicity study for debacarb is non

- definitive and resulted in an

LD 50 >8 00 mg a

. i

. / kg

- bw. Both available avian subacute dietary toxicity studies for debacarb are

also non

- definitive and resulted in an LC 50 >4,496 mg a

. i

. / kg

- diet for bobwhite quail ( Colinus virginianus ) and mallard duck ( Anas platyrhynchos )

. Since RQs cannot be calc ulated based on

non

- definitive endpoints, f or screening

- level assessment purposes, acute dose

- and dietary

- based

EECs were compare d to the highest doses and concentrations tested in available acute oral ( 8 00

mg a

. i

. /kg

- bw ) and acute dietary ( 4,496 mg a

. i

. / kg

- diet ) studies , respectively

. However, in order to compare avian acute oral toxicity data to acute dose

- based EECs, the highest concentration tested (800 mg a.i./kg

- bw) was first corrected for food consumption rate using a scaling factor of 1.15, result ing in values of 415, 529, and 747 mg/kg

- bw for 20

- , 100

- , and 1000

- g sized birds, respectively. To calculate chronic RQ values, the lowest toxicity value for carbendazim (NOAEC=322 mg/kg

- diet, mallard duck) was used.

Acute dose

- and dietary

- based EECs ar e at least 10 times lower than the highest doses and concentrations tested in available acute oral and acute dietary studies , respectively, for birds

. Therefore, there do not appear to be acute risks of concern to listed or non

- listed birds. In addition, n o chronic RQs exceed the chronic LOC o f 1 for birds ( Table 1 2 )

.

Table 12 . C hronic Risk Estimates for Birds

Tree Diameter at Breast Height (inches) Chronic Dietary

- Based RQs

Hardwood

Trees Softwood

Trees

2 0.07 0.03

10 0.02 0.01

16 0.02 0.01

24 0.02 0.01

32 0.01 0.01

Insect Pollinators

RQs were not calculated for insect pollinators since no definitive toxicity data for honeybees are

available for debacarb or carbend a zim . Potential risks to insect pollinators are further discussed in

the Risk Description section

.

Risk Description

Based on information provided by the registrant, the number of trees treated with products containing debacarb in the U.S. is estimated to be in the thousands to tens of thousands ( Table 2 )

. Since the total number of trees in the U

. S

. has been estimated in the hundreds of billions 8 , the proportion of trees treated with debacarb nationwide is extremely small

. Therefore, the potential for exposure of non

- target organisms to debacarb is expected to be low

. However, it is possible

that a large number of trees may be treated in a given area at a given time , which could potentially

lead to increased exposure. This uncertainty was considered to be greater for terrestrial animals

8 http://www.fia.fs.fed.us/tools

- data/maps/2007/descr/livetredbh1.asp17

because they could feed directly on contaminate d food items, and was dealt with quantitatively in

this assessment by assuming that birds and mammals forage exclusively on trees treated with

debacarb. For aquatic organisms, this uncertainty is considered qualitatively along with other lines

of evidence indicating low potential for exposure to aquatic systems

.

Terrestrial Organisms

A conservative screen ing

- level risk analysis was performed in this assessment in which terrestrial vertebrates were assumed to feed 100 percent of their diet on the foliage of trees treated with

debacarb. As mentioned above, g iven the low number of trees estimated to have been treated with Fungisol ® in 2011 and 2012, this is a very conservative assumption ( Table 2 )

. Further conservatism was built into this analysis in the sen se that the entire tree injection of debacarb was assumed to migrate to the tree foliage, which was used as a surrogate for dietary items upon which birds and mammals feed ( i.e. , fruits, nuts, seeds). The latter assumption was made because

environmental fa te data on the uptake and translocation of debacarb in plants was requested but

not submitted

. However, give n that the target pests indicated on the product labels ( e.g. , various types of plant canker) can also affect the bark and other woody or stem porti ons of the plant , it is unlikely that debacarb moves entirely into the foliage or else in would not be effective

. Based on this conservative screening

- level analysis, no risks of concern were identified for mammals or

birds

, including reptiles a nd terrestr ial

- phase amphibians for which birds serve as surrogates

. Although significant acute sublethal effects on spermatogenesis were observed in rats at single

oral doses of carbendazim starting at 1,000 mg/kg

- bw

, conservative exposure estimates for

residues in food items are well below the doses at which this effect was observed . R isk conclusions for birds and mammals were based partly on chronic toxicity data from carbendazim, which was used to bridge data since it has a similar molecular structure to debacarb; therefore , the absence of chronic toxicity data for debacarb is considered an uncertainty.

Since debacarb is systemic, there is potential for exposure to insect pollinators from residues translocated to pollen and nectar of treated trees . No definitive t oxicity data are available for honeybees exposed to debacarb. Therefore, RQs could not be calculated to evaluate risk to insect pollinators in this assessment. While there is acute toxicity data for carbendazim indicating that the compound is practically n on

- toxic to honeybees on a contact exposure basis ( Table 3 ), this type of data does not account for potential toxicity through the oral exposure route

, i.e ., ingestion of residues through pollen and nectar

. Therefore, the absence of toxicity data for debac arb to honeybees via the oral exposure route is considered an uncertainty in this assessment. While a relatively low number of trees are estimated to be treated with debacarb each year across the U.S., the magnitude of this uncertainty, in part, depends on whether groups of trees are treated in close proximity to each other, at the same time, and during parts of the year when residues are more likely to be translocated to pollen or nectar, all of which would be more likely to result in increased

exposure

. I n addition, based on biodegradation modeling , deb a carb is likely to be persistent

, increasing the potential window of exposure. It is also important to note that two of the formulated products, Imisol ® and Abasol ® , contain systemic insecticides that are hi ghly toxic to honeybees

. The Imisol ® product is co

- formulated with imidacloprid, an insecticide with an acute contact LD 50 value of 0.0039 μg/bee. The Abasol ® product is co

- formulated with avermectin, an insecticide that is also highly toxic to bees with an acute contact LD 50 value of 0.41 μg/bee. The current label

for Abasol ® indicates that it should only be used as a post

- bloom application, while the label s for18

Imisol ® and Fungisol ® do not have any application restrictions relative to bloom. Based on t hese uncertainties, potential risks of concern to honeybees cannot be precluded.

Potential risk s of concern to other terrestrial invertebrate species also cannot be precluded since some species may consume various edible plant parts containing translocat ed residues ( e.g. , leaves, fruit) and since there are no available toxicity data for debacarb for any terrestrial invertebrate species

Aquatic Organisms

T he potential for exposure to aquatic organisms from residues of debacarb in leaves, fruits, and

see ds of treated trees that fall into adjacent water bodies was previously acknowledge d , but was not considered to be a significant route of exposure in the Preliminary Problem Formulation for Registration Review (USEPA, 2008). Therefore, environmental fate a nd aquatic toxicity studies

for debacarb were not previously recommended to evaluate exposure and effects to aquatic organisms for the tree injection use.

The major uncertainty concerning the potential for debacarb to reach aquatic environments is that

t he chemical could migrate to portions of treated trees ( e.g. , leaves) that may be subsequently shed; if treated trees are located in close proximity to aquatic systems, the shed material could end up in water bodies and result in exposure of aquatic organi sms to debacarb.

There are several reasons why debacarb is not expected to enter water bodies in sufficient amounts

that would lead to risks of concern. First, the low number of trees treated per year nationwide suggests that the amount of loading of fol iage containing debacarb residues into any specific aquatic system is likely to be small . An exception would be if many trees were treated in the same

location at around the same time of year

. Second, it is uncertain whether a large proportion of the

debac arb residues would migrate to the foliage, where it would be available to be transported to aquatic system via shedding of leaves . T he target pests indicated on debacarb product labels (e.g., various types of plant canker) appear also to affect the bark o r other woody or stem portions of the plant ; t herefore, in order to be effective, a portion of debacarb residues would have to reside in these portions of the plant

, not in the foliage

. Finally, substantial amounts of foliage containing debacarb are only l ikely to end up in a water body if the treated trees are in close proximity to

water bodies. Therefore, EFED believes that potential risk s to aquatic organisms may be reduced

via use restrictions

.

8. ENDANGERED SPECIES A SSESSMENT

Since direct adverse effect s are not expected for birds, reptiles, terrestrial

- phase amphibians, mammals, or terrestrial plants, the EPA makes a No Effects (NE) determination for all Federally

listed species within these groups and a No Habitat Modification determination for all des ignated critical habitats associated with these species for the currently registered uses of debacarb. Risks

to listed aquatic organisms from the use of debacarb may potentially be mitigated via label amendment, but effects and habitat modification determi nations cannot be made at this time. R isks of concern cannot be precluded for listed terrestrial invertebrates , so effects and habitat

modification determinations also cannot be made at this time

.19

9. ENDOCRINE DISRUPTOR SCREENING PROGRAM

As required by FIF RA and FFDCA, EPA reviews numerous studies to assess potential adverse outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, reproductive, and general or systemic toxicity. These studies include endpoints which may be susceptible to endocrine influence, including effects on endocrine target organ histopathology, organ weights, estrus cyclicity, sexual maturation, fertility, pre gnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess growth, developmental and reproductive effects in different taxonomic groups. As part of its most r ecent registration decision for debacarb , EPA reviewed these data and selected the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. However, as required by FFDCA section 408(p), debacarb is subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determine whether certain substances (including pesticide active and other ingredients) may have an effect in humans or wildlife similar to an eff ect produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator may designate.” The EDSP employs a two

- tiered approach to making the statutorily required determinations. Tier 1 consists of a battery of 11 screening as says to identify the potential of a chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal

s ystems will proceed to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 testing is designed to identify any

adverse endocrine

- related effects caused by the substance, a nd establish a dose

- response relationship between the dose and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 2009 and February 2010, EPA issued test orders/data call

- ins for the first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals identified for EDSP screening was published on June 14, 2013 9 and includes some pesticides scheduled for registration review and chem icals found in water

. Neither of these lists should be construed as a list of known or likely endocrine disruptors.

For further information on the status of the EDSP, the policies and procedures, the lists of chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our

website. 10

10. REFERENCES

Davidse, L. C. 1986. Benzimidazole fungicide mechanism of action and biological impact. Ann. Rev. Phytopa thology 24: 43

- 65.

9 See http://www.regulations.gov/#!documentDetail;D=EPA

- HQ

- OPPT

- 2009

- 0477

- 0074 for the final second list of

chemicals.

10 http://www.epa.gov/endo/20

Jenkins, J., D. Chojinacky, L. Heath, and R. Birdsey. 2003. Comprehensive database of diameter

based biomass regressions for North American tree species. General Technical Report NE

319, Forest Service, United States Department of Ag riculture.

Howard, P.H., Boethling, R.S., Stiteler, W.M., Meylan, W.M., Hueber, A.E., Beauman, J.A., and M.E. Larosche. 1992. Predictive model for aerobic biodegradability developed from a file of evaluated biodegradation data. Environ. Toxicol. Che m. 11: 593

- 603.

Sollins , P., D. E. Reichle, J. S. Olson. 1973. Organic matter budget and model for a southern
Appalachian Lirodendron forest. Publication EDFB

- IBP

- 73

- 2. Oak Ridge, TN: Oak Ridge
National Laboratory.

USEPA . 1998. Guidelines for Ecol ogical Risk Assessment. Risk Assessment Forum, Office of Research and Development, Washington, D.C. EPA/630/R

- 95/002F. April 1998. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=30759

USEPA . 1993. Wildlife Exposure Handbook, Volume I of II. Of fice of Research and Development, Washington, DC. EPA/600/R

- 93/187a.

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic

Su bstances, Office of Pesticide Programs, Washington DC. January 23, 2004.

USEPA, 2008. Registration Review: Preliminary Problem Formulation for Ecological Risk, Environmental Fate, Endangered Species, and Drinking Water Assessments for Debacarb (2

- EEEBC). DP Barcode 357028.21

Appendix A. Physicochemical Comparison of Debacarb and Carbendazim

P roperty Debacarb Carbendazim *

Chemical

Structure

Chemical Group Benzimidazole Benzimidazole

CAS Number 17804

- 35

- 2 Molecular Weight (g/mol) 293.33 191.18 g M ole

- 1

Log K OW 1.5 (estimated) 1.52 Water solubility at

25 ○ C (mg L

- 1 ) 710 (estimated) 8

Vapor pressure (Torr) 7.8 x 10

- 10 (estimated) 7.5 x 10

- 10

Henry’s Law Constant (atm cu

m 3 mole

- 1 ) 4.8 x 10

- 16 (estimated) 2.4 x 10

- 11

* Data for carbendazim is derived from Table 3 of “ USEPA 2014. Preliminary Problem Formul ation for the Environmental Fate, Ecological Risk, Endangered Species, and Human Health Drinking Water Exposure Assessments in Support of the Registration Review of Thiophanate Methyl and Carbendazim (D413077 and D413078) ”