Page 2 of 51 

# Problem Formulation for the Environmental Fate, Ecological Risk, Endangered Species, and Drinking
Water Exposure Assessments in Support of the Registration Review of Dichlobenil

Cl Cl N

CAS Registry Number : 1194

- 65

- 6
PC Code: 027401

Prepared by: Elyssa Gelmann, Biologist Greg Orrick , Environmental Scientist U. S. Environmental Protection Agency Office of Pesticide Programs Environmental Fate and Effects Division
Environmental Risk Branch I I 1200 Pennsylvania Ave., NW
Mail Code 7507P Washington, DC 20460 Reviewed by:
Kristina Garber

, Senior Biologist R. David Jones, Ph.D., Senior Agronomist Brian Anderson, Branch ChiefPage 3 of 51 Table of Contents 1. Purpose

................................ ................................ ................................ ................................ ....... 5 2. Nature of Regulatory Action

................................ ................................ ................................ ...... 5
3. Conclusions from Previous Risk Assessments

................................ ................................ .......... 5 3.1. Ecological Risk Assessments

................................ ................................ .............................. 5 3.2. Drinking Water Exposure Assessments

................................ ................................ .............. 7 3.3. Clean Water Act Programs

................................ ................................ ................................ . 8 3.3.1. Aquatic Life Criteria and Aquatic Life Benchmarks

................................ ................... 8 3.3.2. Impaired Water Bodies

................................ ................................ ................................ 8
4. Stressor Source and Distribution

................................ ................................ ............................... 9
4.1. Mechanism of Action

................................ ................................ ................................ ........ 10
4.2. Overview of Pesticide Usage

................................ ................................ ............................ 10 4.3. Environmental Fate and Transport

................................ ................................ .................... 11 4.3.1. Mobility

................................ ................................ ................................ ...................... 13 4.3.2. Degradation

................................ ................................ ................................ ................ 13 4.3.3. Field Dissipation

................................ ................................ ................................ ........ 13
4.3.4. Transformation Products

................................ ................................ ............................ 14 5. Receptors

................................ ................................ ................................ ................................ .. 17
5.1. Effects to Aquatic Organisms

................................ ................................ ........................... 17
5.1.1. Freshwater Fish

................................ ................................ ................................ ........... 19
5.1.2. Freshwater Invertebrates

................................ ................................ ............................. 19
5.1.3. Estuarine/Marine Fish

................................ ................................ ................................ . 20
5.1.4. Estuarine/Marine Invertebrates

................................ ................................ ................... 20 5.1.3. Aquatic Plants

................................ ................................ ................................ ............. 20 5.2. Effects to Terrestrial Organisms

................................ ................................ ....................... 21
5.2.1. Birds

................................ ................................ ................................ ............................ 22
5.2.2. Mammals

................................ ................................ ................................ ..................... 22
5.2.3. Terrestrial Invertebrates

................................ ................................ .............................. 23
5.2.4. Terrestrial Plants

................................ ................................ ................................ ......... 23 5.3. Ecological Incidents

................................ ................................ ................................ .......... 24 6. Ecosystems Potentially at Risk

................................ ................................ ................................ 25 7. Assessment Endpoints

................................ ................................ ................................ ............. 25 8. Conceptual Model

................................ ................................ ................................ ..................... 25 8.1. Risk Hypothesis

................................ ................................ ................................ ................ 26 8.2. Conceptual Diagram

................................ ................................ ................................ ......... 26 9. Analysis Plan

................................ ................................ ................................ ........................... 29
9.1. Stressors of Concern

................................ ................................ ................................ ......... 30 9.2. Measures of Exposure

................................ ................................ ................................ ....... 30 9.2.1. Aquatic Exposure

................................ ................................ ................................ ........ 31 9.2.2. Terrestrial Exposure

................................ ................................ ................................ .... 32
9.3. Measures of Effect

................................ ................................ ................................ ............ 34 9.4. Integration of Exposure and Effects

................................ ................................ ................. 35
9.4.1. Deterministic and Probabilistic Assessment Methods

................................ ................ 35 9.5. Endangered Species Assessments

................................ ................................ ..................... 36 9.6. Drinking Water Assessment

................................ ................................ ............................. 36 10. Endocrine Disruptor Screening Program

................................ ................................ ............... 37Page 4 of 51 11. Preliminary Identification of Data Gaps

................................ ................................ ................ 38
11.1. Environmental Fate

................................ ................................ ................................ .......... 38
11.2. Effects

................................ ................................ ................................ ............................. 40
12. References

................................ ................................ ................................ .............................. 45 Appendix A. Sample Data Call

- In Table

................................ ................................ ...................... 51

List of Tables

Table 1. Labeled Dichlobenil Use Patterns of Maximum Exposure A

................................ ........... 9 Table 2. Chemical Properties and Environmental Fate Parameters of Dichlobenil

.................... 12 Table 3. Dichlobenil and Its Environmental Degradates

................................ ............................. 15 Table 4. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for
Dichlobenil

................................ ................................ ................................ ................................ .... 17 Table 5. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for BAM

.. 18 Table 6. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for
Dichlobenil

................................ ................................ ................................ ................................ .... 21
Tabl e 7. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for BAM

................................ ................................ ................................ ................................ ....................... 21
Table 8. SIP Avian Results for Dichlobenil

................................ ................................ .................. 33
Table 9. SIP Mammalian Results for Dichlobenil

................................ ................................ ........ 33 Table 10. STIR Avian (0.020 kg) Results for Dichlobenil

................................ ........................... 33
Table 11. STIR Mammalian (0.15 kg) Results for Dichlobenil

................................ ................... 34
Table 12. Submitted Environmental Fate Data for Dichlobenil

................................ ................... 38 Table 13. Submitted Environmental Fate Data for the Dichlobenil Degradate, BAM

................. 39 Table 14. Submitted Aquatic Ecological Effects Data for Dichlobenil

................................ ....... 40
Table 15. Sub mitted Terrestrial Ecological Effects Data for Dichlobenil

................................ ... 42 Table 16. Aquatic Ecological Effects Data for the Dichlobenil Degradat e, BAM

....................... 44 Table 17. Aquatic Ecological Effects Data for the Dichlobenil Degradate, BZZ

........................ 44

List of Figures

Figure 1. Estimated National Usage of Dichlobenil from 1999 to 2004 (USGS, 2012)

.............. 1 1 Figure 2. Conceptual diagram depicting stressors, exposure pathways, and potential effects to aquatic organisms from the supported uses of dichlobenil. Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk.

................................ ...... 27 Figure 3. Conceptual diagram de picting stressors, exposure pathways, and potential effects to terrestrial organisms (terrestrial plants, terrestrial invertebrates, and dietary routes of exposure for terrestrial vertebrates) from the supported uses of dichlobenil.

................................ .............. 28 Figure 4. Conceptual diagram depicting stressors, drinking water and inhalation exposure pathways, and potential effects to ter restrial animals from the supported uses of dichlobenil.

... 29Page 5 of 51 

## 1. P urpose

The purpose of this problem formulation is to provide an understanding of the environm ental fate and ecological effects of the registered uses of dichlobenil

. Dichlobenil is a pre

- emergence and

sewer root

- control be n zonitrile herbicide first registered in 1964 and used on apples, bushberries, caneberries, cherries, cranberries, grapes, pears, rhubarb, tree nuts, plant nurseries, shelterbelts, and a large number of non

- agricultural sites including ornamental areas, non

- crop areas, residential areas including paths, patios, p aved areas, and under paved areas, recreational areas, under pool/pond vinyl liners, drains, drain lines, irrigation supply systems, waste water systems,
sewage systems, sewer lines, and storm sewers.

This document will provide a plan for analyzing data r elevant to dichlobenil and for conducting environmental fate and ecological risk, and endangered species assessments for its registered

uses

. Additionally, this problem formulation is intended to identify data gaps

, uncertainties

, and potential assumptions used to address those uncertainties

, relative to characterizing the ecological risk associated with the registered uses of dichlobenil

.



## 2. Nature of Regulatory Action

The Food Quality Protection Act of 1996 mandated the Unite d States E nvironmental P rotection

A gency (EPA) to implement a new program for assessing the risks of pesticides

, i.e ., registration review ( http://www.epa.gov/oppsrrd1/registration_review/ )

. All pesticides distributed or sold in the United States gene rally must be registered by EPA. The decision to register a pesticide is
based on the consideration of scientific data and other factors showing that it will not cause
unreasonable risks to human health, workers, or the environment when used as dire cted on product labeling. The registration review program is intended to ensure that, as the ability to assess risk evolves and as policies and practices change, all registered pesticides continue to

me et the statutory standard of no unreasonable adverse effects to human health and the
environment . Changes in science, public policy, and pesticide use practices will occur over time. Through the new registration review program, the Agency periodically ree v aluates pesticides to

ensure that as change occurs, products in the marketplace can be used safely.

As par t of the implementation of the new Registration Review program pursuant to Section 3(g) of the Federal Insecticide, Fungicide and Rodenticide Act ( FI FRA )

, the Agency is beginning i t s evaluation to det ermine whether dichlobenil continues to meet the FIFR A standard for registration. This problem formulation for the environmental fate and ecological risk assessment chapter in suppo rt of the registration r eview is intended for the initial docket opening the public phase of the review process

.


## 3. Conclusions from Previous Risk Assessments

3 .1. Ecological Risk Assessments

The Agency has conducted multiple ecological risk assessments on dichlobenil that serve as a basis for this problem formulation , including the Reregistration Eligibility Decision (RED), thePage 6 of 51 P acific salmon and steelhead endangered species assessment, and three new use assessment s

. These assessments are briefly summarized below.

The RED document f or dichlobenil (USEPA, 1998 b ) was issued in October 1998. The major ecological conclusions presented in the RED were as follows:

• Dichlobenil dissipates in the environment (on soil and in surface water) principally by volatilization. However, it is persistent under field conditions that reduce the potential for volatilization ( i.e. , cooler climates). When transformation proceeds through aerobic soil metabolism, the metabolite, 2,6

- dichlorobenzamide (BAM) is generated (13.1% at 50 weeks). Under conditions where dichlobenil does not volatilize there is potential for both dichlobenil and BAM to move to ground water in coarse

- textured soils low in organic

matter. Dichlobenil and its degradate s exceed levels of concern for ground water q uality.

• Except for the acute effects to freshwater mollusks and non

- target plants, the concentrations of dichlobenil granules in the environment are not expected to cause either high acute or chronic levels of risk to non

- target organisms. Restricted use triggers have
been exceeded for birds and freshwater mollusks. Endangered species of birds, mollusks, aquatic invertebrates, fish and plants may be affected from the use of dichlobenil. For fish and aquatic invertebrates, risk is only anticipated at the highest application rate of 20
lb a.i./A. The Agency mandated decreasing the maximum application rate to 10 lb a.i./A.

• Chronic risk to birds was not assessed due to lack of avian reproduction data. These
studies were requested in a Data call

- in

.

• The degradate , BAM, poses minimal acute or chronic risk to aquatic and terrestrial organisms.

• Risks to non

- target organisms from the wettable powder used for under

- the

- pavement and sewage line applications are considered to result in minimal exposure to the
environm ent and therefore minimal risk to non

- target organisms.

• The EECs used for non

- soil

- incorporated uses are summarized in the table below. They can be found on page 64 (aquatic) and page 70 (terrestrial) of the RED.

Application rate (lb a.i./A), non

- soil incorporated Aquatic 1

- in

- 10

- year ( μg/L ) Terrestrial ( mg/sq ft) peak 21

- day mean 56

- day mean

2 95 18 7 21

4 190 36 14 42

6 285 54 29 63

8 380 72 27 83

10

-- -- -- 104

20 951 180 67 208

The Pacific salmon and steelhead endangered species risk assessment was issued on July 31,
2003 (USEPA, 2003). The assessment showed that d ichlobenil was moderately toxic toPage 7 of 51 freshwater fish and estuarine invertebrates, slightly to moderately toxic to freshwat er invertebrates and slightly toxic to estuarine fish. It was also toxic to aquatic vegetation. Acute and chronic risk quotients indicate d no direct risk to endangered fish or aquatic invertebrate populations and low exposure potential to aquatic plants. The assessment concluded that
dichlobenil did not present a direct effect on Pacific salmon and steelhead, indirect effects based on loss of their aquati c invertebrate food supply, o r indirect effects based on loss of aquatic plant

cover. The EECs from the RED were used for this assessment.

In 1997, a new use assessment was conducted for homeowner use of dichlobenil in septic systems (USEPA, 1997). Because of the small scale of the proposed use and the small amount of active ingredient (a.i.) applied ( up to 10 grams a.i. per use), there was no concern of risk to

non

- target or ganisms. The assessment add ed that the larger, currently labeled use in municipal

se wer systems could pose a risk to aquatic plants if treated sewer systems discharge directly into natural water bodies or bypass sewage treatment equipment during periods of peak flow.

A new use assessment for a granular formulation of dichlobenil on rhubarb at 2 lb a.i./A was conducted in 2005 (USEPA, 2005 a ). There was no concern of risk to aquatic animals from
dichlobenil or BAM ; however the assessment noted uncertainty in the chronic risk for freshwater
fish since there was no NOAEC established in the freshwater fish early

- life stage study. T here

was no concern of risk to terrestrial animals from dichlobenil or BAM, however there was uncertainty in the assessment of chronic risk for birds since there was no NOAEC established in the avian reproduction study. A fugacity model indicated that estimated resid ue levels in soil
invertebrates would not result in concern for mammals or birds. There was concern of risk to listed aquatic plants and to both listed and non

- listed non

- target terrestrial plants due to spray
drift and runoff. The assessment noted that there was insufficient data on BAM to establish its potential environmental impacts, insufficient information to establish the aerobic aquatic metabolic degradation rate, and uncertainty in off

- site transport du e to the high volatility of
dichlobenil

. The aquatic 1

- in

- 10

- year peak, 21

- day mean , and 60

- day mean EECs were 26, 10,
and 5. 2 μg/L, respectively . The terrestrial EEC was 21 mg/sq ft.

A new use assessment in 2008 for rhubarb, bushberries, cranberry, and caneberry referred to and
summarized the previously described assessments (USEPA, 2008). The 2005 new use assessment was referenced for the rhubarb use and the RED was referenced for the berry uses.



### 3.2. Drinking Water Exposure Assessments

A drinking water exposure assessment for the proposed new use on rhubarb was conducted for dichlobenil in 2005 (USEPA, 2005 b ). Exposure estimates of dichlobenil from currently labeled uses that produce maximum exposure (fruit and nut orchards and non

- crop areas) were 298 μg/L (1

- in

- 10

- year peak), 4.6 μg/L (1

- in

- 10

- year annual mean), and 2.0 μg/L (30

- year mean) for surface water and 9.3 μg/L for ground water.

In 2007, a drinking water exposure assessment was conducted for the dichlobenil degradate of concern, BAM (USEPA, 2007 a ). The assessment mentioned that BAM is also a degradate of the fungicide fluopicolide (PC code 027412). However, exposure estimates were only provided for

BAM resulting from use of dichlobenil . Aggregate exposure from dichlobenil, fluopicolide, andPage 8 of 51 BAM produced from either parent comp ound was not estimated because each compound has different toxicity endpoints

. BAM produced from dichlobenil was assessed separately from BAM produced from fluopicolide because exposure estimates of BAM produced from
dichlobenil were an order of magnitude higher and resulted from use on non

- crop areas, for which fluopicolide is not labeled

. Therefore, e xposure estimates of BAM produced from the currently labeled use of dichlobenil that produces maximum exposure (non

- crop areas) were
used in the human heal th dietary risk assessment for BAM. These exposure estimates were 36 μg/L (1

- in

- 10

- year peak), 15 μg/L (1

- in

- 10

- year annual mean), and 6.9 μg/L (30

- year mean) for surface water and 89 μg/L for ground water (which was lowered to 56 μg/L in the dietary risk assessment due to a reduction in the labeled maximum application rate)

.



### 3.3. Clean Water Act Programs

3.3.1. Aquatic Life Criteria and Aquatic Life Benchmarks

The Clean Water Act requires the Agency to publish water quality criteria that accurately re flect the latest scientific knowledge on the kind and extent of all identifiable effects on health and welfare that might be expected from the presence of pollutants in any body of water, including ground water. While these recommended criteria do not, in themselves, impose any requirements, states and authorized tribes can use them to develop water quality standards. An Aquatic Life Ambient Water Quality Criteria document has not been published for dichlobenil ( see url: http://www.epa.gov/waterscience/criteria/ ).

The Office of Pesticide Programs (OPP) publishes aquatic life benchmarks for freshwater species based on toxicity values for the most sensitive species from the most recent risk assessments.

For dichlobenil , aquatic life benchmarks have been published and are listed in the table below (see url: http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm#benchmarks ).

OPP Aquatic Life Benchmarks (μg/L freshwater)
Fish Invertebrates Nonvascular Plants Vascular Plants
Acute Chronic Acute Chronic Acute Acute 2,465 <330 1,850 560 1,000 30

3.3.2. Impaired Water Bodies

Dichlobenil is not identified as a cause of impairment for any water bodies listed as impaired under section 303(d) of the Clean Water Act, based on information provided at http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=88
5

.

No Total Maximum Daily Load (TMDL) criteria have been developed for dichlobenil , based on information provided at http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id =885&p_pollutant_group_name=PESTICIDES . More infor mation on impaired water bodies and
TMDLs can be found at http://www.epa.gov/owow/tmdl/ . The Agency invites submission of water quality data for this pesticide. To the extent possible, data should conform to th e qualityPage 9 of 51 standards in Appendix A of the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s Registration Review Risk Assessment and Management Process (see: http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm ), in order to ensure they can be used quantitatively or qualitatively in pesticide risk assessments.



## 4. Stressor Source and Distribution

Dichlobenil is a nitrile

, pre

- emergent , nonselective herbicide used to control grasses

, broadlea f
weeds , and root growth . It is registered for use on apples, bushberries, caneberries, cherries, cranberries, grapes, pears , rhubarb , tree nuts, plant nurseries, shelterbelts, and a large number of

non

- agricultural sites including ornamental areas, non

- crop areas, residential areas including paths, patios, paved areas, and under paved areas, recreational areas, under pool/pond vinyl liners, drains, drain lines, irrigation supply systems, waste water systems, sewage systems, sewer lines, and storm sewers . It is formulated in 17 active or pending end

- use products as a granule ( 80% of uses ), liquid microencapsule

, wettable powder , soluble concentrate, and emulsifiable

concentrate

. Treatment equipment include aircraft, backpack sprayers, foam applicator s , foam making generator s , granule applicator s , ground equipment , handgun s , package applicator s , product container s , shaker can s , and spreader s. Table 1 lists the use pattern s of maxim um exposure for the current use s of dichlobenil.

Table 1

. Labeled Dich lobenil U se Patterns of Maximum Exposure A

Use Max. Single App. Rate (lbs a.i./A) Max. No. of App. per

Year Min. Reapp. Interval (d) Max. Annual App. Rate (lbs a.i./A) App. Method

D rains, drain lines, irrigation supply systems, waste water

systems, sewage systems, sewer lines, and storm sewers 25.6 NS NS NS Foam application

Under asphalt, under vinyl pool/pond liners 12 NS NS NS B Soil treatment

Non

- agricultural areas and under containerized nursery
stock 10 NS NS NS Incorporate to a depth of 4

- 6 inches

Non

- agricultural areas,
ornamentals 8.0 NS NS NS Soil treatment

Apples, bushberries, cherries,
grapes, pears, tree nuts 6.1 NS NS NS Soil treatment

Caneberries 4.0 NS NS NS Soil treatment

Cranberries 4.0 NS NS or 21 4.0 Soil treatment

Rhubarb 2.0 NS NS NS Soil treatment

A NS means “not stated”.

B U ses under asphalt and under vinyl pool and pond liners can be assumed to occur only once per site for a period

of multiple years

.Page 10 of 51 

### 4.1. Mechanism of Action

Dichlobenil is a cellulose biosynthesis inhibitor that leads to lack of cell structure integrity in plants and is herbicidally active on the roots and coleoptiles of susceptible weeds. Specifically, dichlobenil inhibits the enzyme cellulose synthase, whic h is involved in the synthesis of components of plant cell walls , preventing germination and meristem growth . The effects include stunted roots and shoots. Dichlobenil acts as a pre

- emergence herbicide, applied after planting but before weeds ge rminate fo r agricultural uses.



### 4.2. Overview of Pesticide Usage

National pesticide usage data from t he U nited States Geological Survey indicate that an average of 29 ,000 pounds of dichlobenil was applied per year to agricultural crops in the United States from 1999 to 2004 (see Figure 1 ; USGS, 2012 ). A Screening Level Usage Analysis conducted by the Agency indicates that usage of d ichlobenil has generally decreased, with an average of
less than 12 ,000 pounds applied annually to agricultural crops from 2000 to 2010 ( year

- specific usage was not provided; USEPA, 2011 ) . The treated fraction of crops was reported to be 5 % or less on average, with a maximum of 10% ( USEPA, 2011 ).

The California Department of Pesticide Regulation reports a general decline of dichlobenil usage
in the state from 80,000 pounds of dichlobenil applied in 2007 to 27,000 pounds applied in 200 9 (CDPR, 2011). A gricultural usage in the state is minimal. Landscape maintenance usage dropped by an order of magnitude (69,000 to 6,000 lbs applied) from 2007 to 2009, while sewage system usage increased from 0 to 12,000 lbs applied during the same time period (CDPR, 20 11).Page 11 of 51 Figure 1

. Estimated National Usage of Dichlobenil from 1999 to 2004 (USGS, 2012 )



### 4.3

. Environmental Fate and Transport

Dichlobenil [ 2,6

- dichlorobenzonitrile; CAS No. 1194

- 65

- 6; PC code 027401] dissipates in the environment (on soil and in surface water) principally by volatilization. However, it is persistent under field conditions that reduce the potential for volatilization ( e.g

. , cooler climates). Dichlobenil photolyzes in shallow, clear s urface waters (half

- life of 10 days)

, but does not photolyze on soil. Under conditions where dichlobenil does not volatilize or photolyze, the compound persists. Dichlobenil slowly degrades in aerobic soil (half

- life of 324 days) to 2,6

- dichlorobenzamide ( i.e. , BAM; 13 % of the applied at 3 50 day s). Biodegradation is negligible in aerobic and anaerobic aquatic systems . D ichlobenil does not bioconcentrate in fish and is not expected to bioaccumulate in aquatic ecosystems . T here is potential for both dichl obenil and
BAM to leach to ground water in vulnerable aquifers, such as those with coarse

- textured soils
low in organic matter. A selection of environmental fate and transport properties of dichlobenil
is summarized in Table 2

.Page 12 of 51 Table 2

. Chemical Properties and Environmental Fate Parameters of Dichlobenil

Parameter Value Source

Selected Physical/Chemical Parameters

Molecular mass (molecular formula) 172.01 g/mol ( C 7 H 3 Cl 2 N ) (Calculated)

Vapor pressure (20 °C) 6 .6 x 10 - 4 torr MRID 40600607

Aqueous solubility (25 ° C) 21 mg/L MRID 4 0600605

Henry’s Law Constant (20 °C) 7.1 x10 - 6 atm

- m 3 /mol (Calculated)

Log octanol

- to

- water partition coefficient (log K OW ) 2.700 MRID 4 0600608

Persistence

Hydrolysis half

- life (22 ° C) pH 5: 2,20 0 d pH 7: 1,80 0 d pH 9: 1,20 0 d MRID 4 0548502/
41012101

Aqueous photolysis half

- life (25 ° C) 10 d MRID 4 1709801

Soil photolysis half

- life (25 ° C) No degradation observed MRID 4 3006801

Aerobic soil metabolism ha lf

- life [dissipation half

- life A ] (24 °C) 324 d [91 d] MRID 41 340601 /
43006803

Anaerobic aquatic metabolism half

- life (20

- 29 ° C) 1,040 d MRID 4 1306001

Aerobic aquatic metabolism half

- life [dissipation half

- life A ] (25 ° C) No degradation observed [ 2. 4 d ] MRID 41149501

Mobility

Freundlich soil

- water partition coefficients (K F ); organic carbon

- normalized
Freundlich coefficients (K FOC ) 0.3, 4.2, 7.4

, 9.6

, 10.5 L/kg;
133 , 1 95

, 262

, 272

, 323 L/kg OC MRID 4 3611101

Maximum volatile concentration (23°C) 313 μg/m 3 (24 hrs posttreatment) (35% volatilized by 4 d posttreatment) MRID 43754001

Field Dissipation

Terrestrial field dissipation half

- life ; leaching depth 24 1 d ( 0

- 3” depth; Woodburn silt loam) ; leached to 50

- 60” depth MRID 41385601

Aquatic field dissipation half

- life 15 d ( pond water), 21 d (top sediment), 32 d (lower sediment) MRID 41780601

69 d (pond water), 39 d (top sediment), variable concentrations (lower sediment) MRID 41877301 /
42191401

Fish Bioconcentration

Fish bioconcentration facto rs (steady

state ) ; depuration rate 32 (edible), 11 0 (inedible), 63 (whole) ; 85% depuration in 1 day MRID 4 0465801/
40465802

A Dissipation half

- lives are shorter because they are corrected for volatilization

.Page 13 of 51 4.3.1. Mobility

Dichlobenil is soluble in water up to 2 1 mg/L (at 25 °C; MRID 40600605 )

. The compound is
semi

- volati le , with a vapor pressure of 6.6 x 10 - 4 torr and a Henry’s Law Constant of 7 .1 x 10 - 6

atm·m 3 /mol at 20 °C (MRID 40600607 )

. The compound was observed to volatilize in multiple submitted laboratory studies , with an evaporation half

- life of 2.4 days in an aerobic aquatic system at 25°C (MRID 41149501) . EpiSUITE (v4. 1 0) estimates a half

- life in air of 1 ,51 0 hours (63 days) for dichlobenil , indicating that the compound may be subjected to long

- range transport.

Dichlobenil is moderately mobile in soil (K FOC range of 133

- 323L/kg OC ; MRID 43611101) . The compound was detected in the field at a s oil depth of 60 inch es (MRID s 435649 01 and

- 02 ).

Dichlobenil’s o ctanol

- water partition coefficient (K OW ) value is 501 (log K OW of 2.700; MRID 40600608)

. EpiSUITE (v4. 1 0) estimates an octanol

- air partition coefficient (K OA ) value for
dichlobenil of 1.7 x 10 6 . With a K OW >100 (501) , a K OA >1 .0 x 10 5 ( 1.7 x 10 6 ) , and a h alf

- l ife
in air predicted to be >48 hrs (1,510 hrs) , dichlobenil has characteristics consistent with compounds that bio accumulate in terrestrial animals. However, fish b iocon centration factors are ≤110 and depuration is rapi d ( 85% depuration in 1 day ; MRIDs 40465801 and

- 02 ), indicating
that bioaccumulation of dichlobenil residues is not a primary concern in aquatic or terrestrial organisms

.

4.3.2. Degradation

Dichlobenil photolyze s in water with a half

- life of 10 days (MRID 41709801 ) , but does not photolyze in soil (MRID 43006801)

. One major degradate, 4

- chloro

- 2(3H)benzoxazolone (BZZ) , was 19 % of the applied and increasing in concentration at 21 days after treatment in the aqueous photolysis study

. In the presence of moisture, dichlobenil does not hydrolyze substantially, with extrapolated hydrolysis half

- lives of 1,200

- 2,200 days at pH 5

- 9 based on a 150

- day study (MRID s 40548502 and 41012101).

Dichlobenil persisted in aerobic soil with a dissipation half

- life of 91 days (at 24°C) and a degradation half

- life (corrected for volatilization) of 324 days (MRID s 41340601 and
43006803 ). BAM was the only major degradate, at 13% of the applie d at 350 days after

treatment.

Dichlobenil was not observed to biodegrade in aerob ic or anaerobic aquatic systems, with the exception that single replicates on two different intervals of the anaerobic aquatic metabolism study (day 217 and 339) contained degradates of dichlobenil totaling 18% and 14% of the applied, respectively (single degradates were no more than 7.2% of the applied)

. However,
dichlobenil dissipated in aerobic aquatic conditions

, with a half

- life of only 2.4 days at 25°C due to volatilization (MRID 41149501).

4.3.3. Field Dissipation

Dich l obenil persisted in the field, dissipating from the top three inches of soil with a half

- li fe of 241 days in a Woodbum silt loam in Oregon (MRID 41385601 ). Dissipation appears to havePage 14 of 51 been due to biodegradation, leaching , and volatilization during the warmer months (the latter w as observed via an increased rate of dissipation in soil)

. Monthly mean t emperatures ranged from

- 3 to 2 8 ° C

. Dichlobenil leached to the 50

- 60

- inch sample depth

, and BAM leached to the deepest sample depth (84

- 96

- inch)

.

Dichlobenil was applied to one

- th ird of a pond in Florida (MRID 41780601) and in Oregon (MRIDs 41877301 and 42191401). Di ssipation half

- lives were 15 days in the pond water, 21 days in the top layer of sediment, and 32 days in the lower layers of sediment at the Florida site.
At the Ore gon site, dissipation half

- lives were 69 days in the pond water and 39 days in the top layer of sediment. Concentrations in the lower sediment layers were too variable to calculate a dissipation half

- life.

4.3.4. Transformation Products

The major organic degradate s of dichlobenil in submitted environmental fate studies were BAM (in aerobic soil) and BZZ (in water under illumination ). A variety of minor degradates were observed in the aqueous photolysis and anaerobic aquatic metabolism studies. Table 3 summarizes the transformation products of dichlobenil and their maximum amounts formed.

BAM (PC code 027402) is also a degradate of the fungicide fluopicolide (PC code 027412). Although BAM has a PC code, it is not a registered pesticide. BAM formed up to 13% of the applied in aerobic soil and was increasing in concentration at study termination. This degradate
was detected in field studies at up to 4.9% of the maximum dichlobenil concentration in soil. Also, BAM leached to the deepest sampling depth (up to 84

- 96

- inches deep) in each terrestrial field dissipation study. Submitted environmental fate studies of BAM indicate that the degradate is stable to hydrolysis, to aqueous photolysis, and to biodegradation in soil (MRIDs 45280303 and 45575901). BAM is also mobile in soil , with Freundlich K OC values in five soils ranging
from 34 to 5 4 L/kg OC (MRID 45539402).

BZZ formed up to 19% of the applied in irradiated water and was increasing in concentration at study termination (MRID 41709801) . Dichlobenil field studies did not analyze for BZZ. Also, environmental fate studies conducted with BZZ have not been submitted. Therefore, the
environmental fate of BZZ is not well understood.Page 15 of 51 Table 3

. Dichlobenil and Its Environmental Degradates

Code Name/ Synonym Chemical Name Chemical Structure Study Type Ref. (MRID) Maximum %AR (day) Final %AR (study length)

PARENT
Dichlobenil 2,6

- dichlorobenzonitrile

CAS No.: 1194

- 65

- 6

Formula: C 7 H 3 Cl 2 N
MW: 172.01 g/mol Cl Cl N

MAJOR TRANSFORMATION PRODUCTS

BAM 2,6

- dichlorobenz amide

Formula: C 7 H 5 Cl 2 N O
MW: 190.03 g/mol Cl Cl O N H 2 Aq photolysis 41709801 3% (15 d) 3% (15 d)

Aerobic soil 41340601/
43006803 13 % (350 d) 13% (350 d)

Anaerobic aquatic 41306001 7.2% A (217 d) n.d. B (370 d)

Terr dissipation 41385601 4.8% C (371 d) 3.4% C (540 d)

Aq dissipation 41877301/
42191401 1.8% D (113 d) <0.1% D (180 d)

BZZ 4

- chloro

2(3H)benzoxazolone

Formula: C 7 H 4 ClN O 2 MW: 169.57 g/mol Cl N H

O O

Aq photolysis 41709801 19 % (21 d) 19 % ( 21 d)Page 16 of 51 Code Name/ Synonym Chemical Name Chemical Structure Study Type Ref. (MRID) Maximum %AR (day) Final %AR (study length)

MIN OR TRANSFORMATION PRODUCTS 2,6

- dichlorobenzoic
acid 2,6

- dichlorobenz oic acid

Formula: C 7 H 4 Cl 2 O 2 MW: 191.01 g/mol Cl Cl O O H Aq photolysis 41709801 4 % (21 d) 4 % (21 d)

Anaerobic aquatic 41306001 1.4% A (217 d) n.d. B (370 d)

2

- chlorobenzonitrile 2

- chlorobenzonitrile

Formula: C 7 H 4 ClN
MW: 137.57 g/mol Cl N Aq photolysis 41709801 2% (21 d) 2% (21 d)

Anaerobic aquatic 41306001 6.4% A (217 d) n.d. B (370 d)

2

- hydroxy benzonitrile 2

- hydroxy benzonitrile

Formula: C 7 H 5 N O
MW: 1 19.12 g/mol O H N

Aq photolysis 41709801 4% (21 d) 4% (21 d)

Carbon dioxide Carbon dioxide

Formula: CO 2 MW: 44.1 g/mol O O Aerobic soil 41340601/
43006803 2.7% (280 d) 2.3% (350 d)

A Degradates were not consistently formed in this study and were not detected at most intervals.

B n.d. means “not detected”.

C Terrestrial f ield study percentages represent the ratio of degradate concentration to the maximum parent concentration , both in t he top layer of soil.

D Aquatic field study percentages represent the ratio of degradate concentration to the maximum parent concentration, both in t he top layer of sediment (BAM was not detected in the water samples )

.Page 17 of 51 

## 5. Receptors

Consistent with the process described in the Overview Document (USEPA

, 2004), the risk
assessment for dichlobenil will rely on a surrogate species approach. Toxicological data generated from surrogate test species, which are intended to be representative of broad taxonomic groups, are used to extra polate to potential effects on a variety of species (receptors) included under these taxonomic groupings.

A cute and chronic toxicity data from studies submitted by pesticide registrants along with the available open literature are used to evaluate the p otential direct and indirect effects of
dichlobenil on aquatic and terrestrial receptors. These include toxicity data on the technical grade active ingredient, degradates, and when available, formulated products. The open
literature studies are identifie d using EPA’s ECOTOXicology database ( ECOTOX ) ( USEPA,
2007 c ), which employs a literature search engine for locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife. The evaluation of both sources of data can also provide insight into the direct and indirect effects of dichlobenil on biotic communities from loss of species that are sensitive to the chemical and from changes in structure and functional
characteristics of the affected communities.

Table 4 and Table 6 provide a summary of the aq uatic and terrestrial taxonomic groups, respectively, and most sensitive surrogate species tested to characterize the potential acute and chronic ecological effects of dichlobenil

. Table 5 and Table 7 provide this same information for the degradate BAM. No toxicity data w ere submitted or identified in the open literature for the degradate BZZ. A structural isomer, c hlorzoxazone

, has similar physical properties to BZZ and is pharmacologically active as a muscle relaxant at doses of 10

- 30 mg/kg/day

. In addition, the
table s provide a preliminary overview of the potential acute toxicity of dichlobenil by providing the acute toxicity classifications. Based on the available ecotoxicity information, the organisms facing the greatest hazard are aquatic and terrestrial plants, followed by m oderate hazard to aquatic fish and invertebrates.



### 5.1. Effects to Aquatic Organisms

Table 4 . Summary of the M ost S ensitive E ndpoints from A quatic T oxicity S tudies for D ichlobeni l

Taxonomic

Group Study Type Surrogate Species Toxicity Value (all units in terms of

measured active ingredient ) MRID and
Classification Acute Toxicity
Classification

Freshwater fish 1 Acute Rainbow Trout ( Oncorhynchus mykiss ) LC 50 = 4.93 mg/L 40098001 Supplemental Moderately
toxic

Chronic (Early
Life

Stage) Rainbow Trout NO A E C = <0.33 mg/L
LO A E C = 0.33 mg/L Endpoint: 34 day length 42224202 Supplemental --

Freshwater
invertebrates Acute Water Flea ( Daphnia magna ) EC 50 = 6.2 mg/L 40775001 Acceptable Moderately
toxicPage 18 of 51 Taxonomic

Group Study Type Surrogate Species Toxicity Value (all units in terms of

measured active ingredient ) MRID and
Classification Acute Toxicity
Classification

Chronic Water Flea NO A E C = 0.56 mg/L
LO A E C = 1.0 mg/L Endpoint: delayed reproduction 40775002,
42224201 Acceptable --

Estuarine/marine
fish Acute Sheepshead Minnow ( Cyprinodon variegat u s ) LC 50 = 12.7 mg/L 43905403 Acceptable Slightly toxic

Estuarine/marine
invertebrates Acute Eastern Oyster ( Crassostrea virginica ) EC 50 = 1.63 mg/L Endpoint: s hell growth 43905404 Acceptable Moderately
toxic

Aquatic plants and algae Vascular Duckweed ( Lemna gibba ) NO A EC = 0.006 mg/L
EC 50 = 0.030 mg/L 40758203 Acceptable --

Non

vascular Green Algae ( Pseudokirchneriella subcapitata ) NO A EC = 0.16 mg/L
EC 50 = 1.5 mg/L 40758201 Acceptable --

1 Freshwater fish may be surrogates for aquatic

- phase amphibians.

Table 5 . Summary of the M ost S ensitive E ndpoints from A quatic T oxicity S tudies for BAM

Taxonomic

Group Study Type Surrogate Species Toxicity Value (all units in terms of

measured active ingredient ) MRID and
Classification Acute Toxicity
Classification

Freshwater fish 1 Acute Bluegill S unfish ( Lepomis
macrochirus ) LC 50 = 120 mg/L 40098001 Supplemental Practically

non

- toxic

Chronic (Early
Life Stage) Rainbow Trout NO A E C = 10 mg/L
LO A E C = 18 mg/L Endpoints: 60 day offspring survival, length, weight 00156312 Supplemental --

Freshwater
invertebrates Acute Water Flea EC 50 = 184 mg/L 46708432 Acceptable Practically

non

- toxic

Chronic Water Flea NO A E C = 320 mg/L LOAEC = >320 mg/L 00156312 Supplemental --

Aquatic plants and algae 2 Non

vascular Estuarine Algae ( Chlorella pyreoidosa ) NO A EC = 10 mg/L
LO A EC = 32 mg/L 00156312 Supplemental --

Non

vascular Freshwater A lgae ( Scenedesmus pannonicus ) EC 50 = 100 mg/L 00156312 Supplemental --

1 Freshwater fish may be surrogates for aquatic

- phase amphibians.

2 Toxicity endpoints presented, i.e.

, NOAEC or EC 50 , are the only ones available from the study.Page 19 of 51 5.1.1. Freshwater Fish

The acute toxicity of technical grade dichlobenil has been tested in five species of freshwater
fish , rainbow trout ( Oncorhychus mykiss ), bluegill sunfish ( Lepomis macrochirus ), fathead minnow ( Pimeph ales promelas ), goldfish ( Carassius auratus auratus ), and green sunfish ( Lepomis cyanellus ). The 96

- hr LC 50 test results for freshwater fish ranged from 4.93 mg/L for rainbow trout (MRID 40098001) to 12.6 mg/L for green sunfish (MRID 40098001). Based on these studies, dichlobenil is classified as moderately toxic to freshwater fish on an acute basis

.

The acute toxicity of BAM has been tested in rainbow trout, bluegill sunfish, and guppy ( Poecilia reticulaia ). The 96

- hr LC 50 values ranged from 120 mg/L for rainbow trout (MRID 40098001) to 275 mg/L for guppy (MRID 00 156312). Based on these studies, BAM is classified as practically non

- toxic to freshwater fish and aquatic

- phase amphibians on an acute basis. On an acute exposure basis, BAM appea rs to be less toxic to fish compared to dichlobenil.

An early

- life stage study with dichlobenil on rainbow trout demonstrated a statistically significant effect on offspring length at 34 days post

- hatch at all concentrations tested (mean
measured values o f 0.33, 0.66, 1.2, 2.4, and 5.1 mg a.i./L) (MRID 42224202). Therefore , the
NO A EC is <0.33 mg/L and the LOEC is 0.33 mg/L. This study is classified as supplemental and does not fulfill the guideline requirement due to the failure to establish a definitive NOAEC.

An early

- life stage study with BAM on rainbow trout demonstrated a NOEC of 10 mg/L and a
LO A EC of 18 mg/L with effects on survival, length, and weight of offspring (MRID 00 156312). On a chronic exposure basis, BAM appears to be less toxic to fish compared to dichlobenil.

5.1. 2 . Freshwater Invertebrates

The acute toxicity of technical grade d ichlobenil has been tested in five species of freshwater
invertebrate s , including: scud ( Gammarus fasciatus ), sowbug ( Asellus brevicaudus ), water flea ( Daphnia magna ), glass shrimp ( Palacmonetes kadiakensis ), and seed shrimp ( Cypridopsis
vidua ) . The 48

- hr EC 50 for these studies ranged from 6.2 mg/L for D

. magna (MRID 40775001) to 34.0 mg/L for the sowbug ( MRID 00500149). Based on these studies, dichlobenil is classified as moderately toxic to freshwater invertebrates on an acute exposure basis

. A study t hat tested a 50% formulation of dichlobenil on five freshwater aquatic invertebrates (MRID 40094602) had similar results; the 48

- hr EC 50 ranged from 3.7 mg/L for a daphnid species ( Daphnia pulex ) to 35.0 mg/L for the sowbug.

The acute toxicity of BAM has also been tested in D

. magna . The 48

- hr EC 50 for BAM was 184 mg/L (MRID 46708432) . BAM is classified as practically non

- toxic to freshwater invertebrates
on an acute basis. On an acute exposure basis, BAM appears to be less toxic to freshwater invertebrates compared to dichlobenil.

A daphnid life

- cycle study with dichlobenil demonstrated delayed reproduction at 1.0 mg/L and no effects were observed at 0.56 mg/L (MRID 40775002, 42224201). A daphnid life

- cycle study with BAM showed no effects at the highest concentration tested, 320 mg/L (MRID 00156312). Therefore, the NO A EC for chronic effects of freshwater i nvertebrate exposure toPage 20 of 51 BAM is 320 mg/L and the LO A EC is >320 mg/L

. On a chronic exposure basis, BAM appears to
be le ss toxic to freshwater invertebrates compared to dichlobenil.

5.1. 3 . Estuarine/Marine Fish

The acute toxicity of technical grade dichlobenil has been tested in one species of estuarine/marine fish, the sheepshead minnow ( Cyprinodon variegat u s ). The 96

- h r LC 50 was 12.7 mg/L in one study (MRID 43905403 ) and 14.0 mg/L in a second study (MRI D 40228401 ). Based on these studies, dichlobenil is classified as slightly toxic to estuarine/marine fish on an acute basis. There are no chronic dichlobenil toxicity studies or acute or chronic BAM toxicity
studies with estuarine/marine fish.

5.1.4 . Estuarine/Marine Invertebrates

The acute toxicity of technical grade dichlobenil has been tested in three species of aquatic
in vertebrates including one mollusk , eastern oyster ( Crassostrea virginica ), and two

crusteacea n s, p ink s hrimp ( Penaeus duorarum ) , and m ysid s hrimp ( Mysidopsis bahia )

. A 96

- hr study with eastern oyster larvae demonstrated an E C 50 of 2.5 mg/L (MRID 40228401 ) wh ereas a 96

- hr study of eastern oyster shell growth demonstrated an EC 50 of 1.63 mg/L (MRID
43905404 ). A 48

- hr study on pink shrimp had an EC 50 of >1.0 mg/L (MRID 40228401 ) and a
96

- hr study on mysid shrimp had an LC 50 of 2.35 mg/L (MRID 43905405 ). Based on these studies, dichlobenil is classified as moderately toxic to estuarine/marine invertebrates on an acute basis. There are no chronic dichlobenil toxicity studies or acute or chronic BAM toxicity studies
with estuarine/marine invertebrates.

5.1 .3

. Aquatic Plants

The toxicity of technical grade dichlobenil was tested on one vascular and eight non

- vascular plants. The NOEC and EC 50 for duckweed ( Lemna gibba ) were 0.006 mg/L and 0.030 mg/L, respectively (MRID 40758203 ). For non

- vascular plants, the NOEC range d from 0.16 to 2.5 mg/L for g reen algae ( Pseudokirchneriella subcapitata ) (MRID 40758201 ) and b lue

- green a lgae ( Anabaena flos

- aquae ) (MRID 40758202 ), respectively. The EC 50 ranged from 1.0 to 60 mg/L
for a f reshwater diatom ( Navicula pellicu losa ) (MRID 40758204 ) and three estuarine algae ( Isochrysis galbana

, Dunaliella tertiolecta

, and Chlorococcum sp. ) (MRID 40228401 ), respectively.

The toxicity of BAM was tested in one estuarine alga e ( Chlorella pyreoidosa )

, one freshwater alga e ( Scenedesmus pannonicus ) (MRID 00 156312 ) , and one freshwater diatom ( Navicula pelliculosa ) (MRID 46708511 ) . The EC 50 for the estuarine alga e was 100 mg/L, no NOEC was provided. The NOEC and LOEC for the freshwater algae were 10 and 32 mg/L, no EC 50 was
pr ovided. No effects were seen in the freshwater diatom study at the highest concentration tested, 10 mg/L. No studies of BAM toxicity to vascular aquatic plants were identified.Page 21 of 51 

### 5.2. Effects to Terrestrial Organisms

Table 6 . Summary of the M ost S ensitive E ndpoints from T errestrial T oxicity S tudies for

D ichlobeni l

Taxonomic

Group Study Type Surrogate Species Toxicity Value (all units in terms of

measured active ingredient) MRID and
Classification Acute Toxicity
Classificat ion

Birds 1 Acute Bobwhite quail ( Colinus virginianus ) LD 50 = 683 mg /kg

- bw 43469801 Acceptable Slightly toxic

Sub

- acute dietary Ring

- necked

p heasant ( Phasianus
colchicus ) LC 50 = 1500 ppm 00022923 Supplemental Slightly toxic

Chronic Bobwhite quail NO A EC = <146 ppm
LO A EC = 146 ppm 45280301 Supplemental --

Mammals Acute Oral Laboratory rat ( Rattus norvegicus ) LD 50 = 4250 mg/kg

- bw 0 0112500 Practically

non

- toxic

Acute
Inhalation Laboratory rat LC 50 = >3.3 mg/L 43335703 Toxicity Category III

Chronic Laboratory rat ( Rattus norvegicus ) NO A EL = 3 mg/kg/day
LO A EL = 15 mg/kg/day Endpoint: reduced pup weight 41257303,
42239101 --

Insects Acute

contact Honey bee ( Apis mellifera L. ) LD 50 = >120 μg/bee 00 0 18842 Acceptable Practically

non

- toxic

Terrestrial plants Seedling Emergence Dicot

– lettuce ( Lactuca sativa ) EC 05 = 0.011 lb/A
EC 25 = 0.023 lb/A Endpoint: shoot dry weight 41280801 Supplemental --

Monocot

– oat ( Avena sativa ) NO A EC = 0.084 lb/A
EC 25 = 0.12 lb/A Endpoint: shoot dry weight 41280801 Supplemental --

1 Birds represent surrogates for terrestrial

- phase amphibians and reptiles.

Table 7 . Summary of the M ost S ensitive E ndpoints from T errestrial T oxicity S tudies for BAM

Taxonomic

Group Study Type Surrogate Species Toxicity Value (a ll units in terms of

measured active ingredient ) MRID and
Classification Acute Toxicity
Classification

Mammals Acute Mouse (female) ( Mus
musculus ) LD 50 = 1144 mg/kg

- bw 42940201 Slightly toxicPage 22 of 51 Taxonomic

Group Study Type Surrogate Species Toxicity Value (a ll units in terms of

measured active ingredient ) MRID and
Classification Acute Toxicity
Classification

Chronic Rabbit ( Oryctolagus
cuniculus ) NO A EL = 10 mg/kg/day
LO A EL = 30 mg/kg/day Endpoint: mortality 43003601,
43265201 --

Terrestrial plants Seedling Emergence 1 Dicot

– pea ( Pisum
sativum ) EC 05 = 3.5 μg/kg soil
EC 25 = >11.64 μg/kg soil Endpoint: survival 46708506 Acceptable --

Monocot

– onion ( Allium cepa ) NOAEC = 0.722 μg/kg soil
EC 25 = 6.3 μg/kg soil Endpoint: shoot dry weight 46708506 Acceptable --

1 The study does not provide sufficient information to convert the toxicity values to lb a.i./A.

5.2 .1. Birds

Acute oral and sub

- acute dietary toxicity data for dichlobenil are available for mallard duck ( Anas platyrhynchos ), bobwhite quail ( Colinus virginianus ) , and r ing

- necked p heasant ( Phasianus colchicus ) and dietary toxicity data are also available for Japanese q uail ( Coturnix japonica ) . Definitive acute oral LD 50 values were 683 mg/kg

- bw for the bobwhite quail (MRID
43469801 ) and 1189 mg/kg

- bw for the ring

- necked pheasant (MRID 00 160000 ). A mallard duck acute oral study showed no effects at the highe st dose tested, 2000 mg/kg

- bw (MRID
00 160000 ). The dietary LC 50 values ranged from 1500 mg/kg

- diet for the ring

- necked pheasant (MRID 000 22923 ) to >5200 mg/kg

- diet for the mallard duck (MRID 40600602 ). Based on these studies, dichlobenil is classified as slightly toxic to birds on acute oral and sub

- acute dietary
bases. No studies on a passerine species have been submitted to U.S. EPA or identified in the open literature. No studies of BAM toxicity to birds were identified.

Two avian reproduction studi es with dichlobenil were submitted to the Agency, one with the mallard duck and a second with the bobwhite quail. The bobwhite quail study failed to
determine a definitive NO A EC, as hatchling weight and adult male body weight were significantly affected a t the lowest concentration tested, 146 ppm (MRID 45280301 ). The mallard duck study found a NO A EC and LO A EC of 289 and 600 ppm, respectively, based on eggs laid, hatchlings, and 14

- day old survivors (MRID 45280302).

5.2

. 2

. Mammals

Acute oral and inhalation and chronic reproductive studies for laboratory rats were study
submitted to the Health Effects Division ( HED ) and used to assess effects to mammalian
wildlife

. The acute oral toxicity of dichlobenil was tested in the labo ratory rat ( Rattus norvegicus ) and the LD 50 was found to be 4250 mg/kg

- bw (MRID 00112500)

. Based on this study, dichlobenil is classified as practically non

- toxic to mammals on an acute basis. The acute oral toxicity of BAM was tested in both the laboratory rat and the mouse ( Mus musculus ). The

LD 50 values ranged from 1144 mg/kg

- bw for the female mouse (MRID 42940201) to 2330 mg/kg

- bw for the female rat (MRID 00111402). Based on these studies, BAM is classified as slightly toxic to mammals on an acute basis.Page 23 of 51 A four hour acute inhalation study with dichlobenil on the laboratory rat was submitted to the agency (MRID 43335703). The study was performed using an 85.3% formulation due to clogging of the apparatus with technical dichlobenil above 0.25 mg/L. The LC 5 0 was >3.3 mg/L. This result would normally place dichlobenil in Toxicity Category IV; however, because the respirable particle size was less than optimal (5.5 μm instead of an optimal size of 4 μm), Toxicity Category III was assigned as an added measure of protection.

Three mammalian reproduction studies with dichlobenil were submitted to the Agency, two with rats and one with rabbits ( Oryctolagus cuniculus ). One rat 2

- gen eration study found a NOEL of 3 mg/kg

- bw /day and a LO A EL of 15 mg/kg/day (60 and 3 50 ppm in diet , respectively) based on reduced pup weight (MRID 41257303, 42239101). The study report indicates that palatability was an issue in the study and that no other endpoints were affected, up to 100 mg/kg/day. The
two other studies were develop mental toxicity gavage studies and reported a NO A EL / LO A EL of 20 / 60 mg/kg/day in the rat (MRID 00147437) and 45 / 135 mg/kg/day in the rabbit (MRID 41257302). Major external, visceral, and skeletal defects were observed in the rabbit and decreased weig ht gain, food consumption, and food efficiency were observed in the rat. A developmental toxicity study using BAM was conducted on the rabbit. The NO A EL was 10 mg/kg/day and the LOEL was 30 mg/kg/day based on mortality following a 6 day exposure (MRID 43 003601, 43265201).

Dichlobenil and BAM toxicity endpoints for mammals are within approximately a factor of two on both acute and chronic exposure bases. BAM was somewhat more toxic to mammals than
dichlobenil on an acute exposure basis but less toxic on a chronic exposure basis. Taking confidence intervals into account, BAM and dichlobenil appear to have similar toxicity to
mammals.

5.2.3. Terrestrial Invertebrates

Toxicity of dichlobenil to terrestrial invertebrates was tes ted by an acute contact study using the honey bee ( Apis mellifera ). This study was acceptable and demonstrated an LD 50 of >120 μg/bee, classifying dichlobenil as practically non

- toxic to terrestrial invertebrates (MRID 00018842). No studies of BAM toxicity to terrestrial invert ebrates were identified.

5.2.4

. Terrestrial Plants

One terrestrial plant study with dichlobenil was submitted to the Agency using six dicots: soybean ( Glycine max ) , lettuce, sugarbeet ( Beta vulgaris ), tomat o ( Solanum esculentum )

, cucumber ( Cucumis sativa ) , and cabbage ( Brassica oleraceae )

, and four monocots : corn ( Zea

mays ) , oat, wheat (Triticum aestivum ) , and onion ( Allium cepa ) (MRID 41280801) . Seedling emergence, seedling germination, and vegetative vigor were tested; however the seedling germination and vegetative vigor studies were classified as invalid. The seedling emergence study was classified as supplemental because the lowest concentration tested was >EC 25 for lettuce and the test compound was the technical active ingredient rather than a form ulated product. The most sensitive dicot tested was lettuce with an EC 05 of 0.011 lb a.i./A. The mostPage 24 of 51 sensitive monocot tested was oat with a NO A EC of 0.084 lb a.i./A. The most sensitive endpoint for both species was the shoot dry weight.

A seedling emergence study with BAM was submitted to the Agency using five dicots: sugarbeet, oilseed rape ( Brassica napus ), cucumber, soybean , and pea, and three monocots: corn, oat, and onion (MRID 46708506). The most sensitive dicot species was pea which resulted in an
EC 25 , EC 05 , and NOAEC values of >11.64, 3.5, and 11.64 μg a.i./kg soil, respectively, based a statistically significant reduction in percent survival. The most sensitive monocot species was
onion which resulted in an EC 25 and NOAEC values of 6.3 an d 0.722 μg a.i./kg soil, respectively, based a statistically significant reduction in dry weight. The study reported all application rates in terms of μg/kg soil soil without providing sufficient information to convert the nominal application rates to lbs a

. i

. /A.



### 5. 3

. Eco logical Incidents

A review of the Agency’s Ecological Incident Information System (EIIS, version 2.1.1), the ‘Aggregate Incident Reports’ (v. 1.0) database, and the American Bird Conservancy’s Avian Monitoring Information System (AIMS) for ecological incidents involving dichlobenil was completed on 19 January 2012

. The incidents identified in these sources and any other known
incidents that occur before the registration review risk assessment i s performed will be included
in the assessment. The search of AIMS identified no ecological incidents involving dichlobenil.

The search of EIIS returned two terrestrial plant incidents in Washington State attributed to dichlobenil use with “possible” c ertainty (USEPA, 2007 b ) . Incident #I009786

- 020 occurred in January 2000 when a registered agricultural use of dichlobenil was applied to kinnikinnick (also known as bearberry) . Thirty

- five plants on the treated field were damaged. Incident #I013587

- 060 occurred in April 1999 when a registered use of dichlobenil was applied to a right

- of

- way. A residential homeowner reported lawn damage as a result of spray drift from this application.

The number of documented incidents in EIIS is believed to be a very small fraction of total mortality caused by pesticides for a variety of reasons. Incident reports for non

- target organisms typically provide information only on mortality events and plant damage. Sub

- lethal effects in organisms such as abnormal behavior, reduced growth and/or impaired reproduction are rarely reported, except for phyto toxic effects in terrestrial plants. An absence of reports does not necessarily equate to an absence of incidents given the nature of the incident reporting.

In addition to the incidents recorded in EIIS and AIMS

, i ncidents have been reported to the Agen cy in aggregated incident reports. Pesticide registrants report certain types of incidents to the Agency as aggregate counts of incidents occurring per product per quarter. Ecological incidents reported in aggregate reports include those categorized as ‘ minor fish and wildlife’ (W

B), ‘minor plant’ (P

- B), and ‘other non

- target’ (ONT) incidents. ‘Other non

- target’ incidents include reports of adverse effects to insects and other terrestrial invertebrates. For dichlobenil

, registrants reported 9 minor pla nt incidents between 1995 and 2005 , and no fish and wildlife or
other non

- target incidents. Unless additional information on these aggregated incidents becomes available, they will be assumed to be representative of registered uses of dichlobenil in the r isk

assessment.Page 25 of 51 

## 6. Ecosystems Potentially at Risk

The ecosystems potentially at risk are often extensive in scope; therefore, it may not be possible to identify specific ecosystems during the development of a nation

- wide ecological risk

assessment. Howev er, in general terms, terrestrial ecosystems potentially at risk could include the treated field and immediately adjacent areas that may receive drift or runoff. Areas adjacent to the treated field could include cultivated fields, fencerows and hedgerows, meadows, fallow fields or grasslands, woodlands, riparian habitats, and other uncultivated areas.

Aquatic ecosystems potentially at risk include water bodies adjacent to, or down stream from, the treated site and might include impounded bodies such as pon ds, lakes and reservoirs, or flowing waterways such as streams or rivers including all adjacent off

- channel habitats that are permanently or intermittently connected to flowing waters. For uses in coastal areas, aquatic habitat also includes marine ecosyst ems, including estuaries, embayments, and near shore
environments.



## 7 . Assessment Endpoints

Assessment endpoints represent the actual environmental value that is to be protected, defined by an ecological entity (species, community, or other entity) and its attribute or characteristics ( US EPA

, 1998 a ). For dichlobenil , the ecological entities include the following: birds, reptiles,
terrestrial

- phase amphibians, mammals, freshwater fish , freshwater aquatic

- phase amphibians and invertebrates, estuarine/mari ne fish and invertebrates, terrestrial plants, insects, aquatic plants, and algae. The attributes for each of these entities include growth, reproduction, and
survival.



## 8. Conceptual Model

For a pesticide 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 comple te, 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 dichlobenil provides a written description and visual representatio n of the predicted relati onships between dichlobenil , potential routes of exposure, and the predicted effects for the assessment endpoint. A conceptual model consists of two major components: risk hypothes i s and a conceptual diagram ( US EPA

, 1998 a ).Page 26 of 51 

### 8.1. Risk Hypothesi s

A r isk hypothes i s descri bes the predicted relationship among the stressor, exposure, and assessment endpoint response along with the rationale for their selection. For dichlobenil , th e following ecologi cal risk hypothesis is being employed for this national

- level ecological risk

assessment:

Dichlobenil, when used in accordance with current labels, can result in off

- site movement of the compound via runoff, leaching to ground water, spray drift and

atmos pheric transport leading to exposure of non

- target plants and animals. Direct applications to and atmospheric deposition to foliar surfaces may serve as a major source of dichlobenil exposure to wildlife. Exposure in these environmental compartments will result in adverse effects upon the survival, growth, and reproduction of non

- target terrestrial and aquatic organisms. These

non

- target organisms include federally

- listed threatened and endangered species.



### 8.2. Conceptual Diagram

The environmental fate properties of dichlobenil indicate that direct spray, spray drift

, leaching to ground water, atmospheric deposition , and runoff represent potential transport mechanisms of
dichlobenil to aquatic and terrestrial organisms. These transport mechanisms ( e.g

. , sources) are depicted in the conceptual model s below ( Figure 2

, Figure 3 , and Figure 4 ) and result in the
movement of dichlobenil into aquatic (water and sediment) and terrestrial (soil and foliage)
habitats. Use of dichlobenil in sewer drain and storm drain systems will also be assessed. The movement away from the site of application represents exposure pathways for a broad range of
bi ological receptors of concern (non

- target animals) and the potential attribute changes

, i.e.

, effects such as reduced survival, growth and reproduction, in the receptors due to dichlobenil

exposure.Page 27 of 51 Figure 2 . Conceptual diagr am depicting stressors, exposure pathways, and potential effects to aquatic organisms from the supported uses of dichlobenil . Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk.Page 28 of 51 Figure 3 . Conceptual diagram depicting stressors, exposure pathways, and potential effects to

terrestr ial organisms (terrestrial plants, terrestrial invertebrates, and dietary routes of exposure for terrestrial vertebrates) from the supported uses of dichlobenil

.Page 29 of 51 Figure 4 . Conceptual diagram depicting stressors, drinking water and inhalation exposure pathways, and potential effects to terrestrial animals from the supported uses of dichlobenil.

As indicated in Figure 2

, Figure 3 , and Figure 4 above, the possible exposure mechanisms considered are direct application, spray drift, leaching to ground water, atmospheric trans port, and runoff. In addition to exposure via ingestion of food items, d rinking water and inhalation exposure pathways are considered for terrestrial vertebrates as well as ingestion of residues in dew by terrestrial invertebrates . EFED acknowledges the potential for a dermal exposure pathway, however at the present time, the Agency does not have a method to quantify these levels of exposure, and data are limited to quantify the contribution of such exposures to the toxic burden an organism experiences. Dermal exposure is not expected to be of concern for dichlobenil based on mammalian dermal toxicity and irritation data and the predominant use of granular formulations.



## 9. Analysis Plan

In registration review, pesticide ecological risk assessments will follow the Agency’s Guidelines for Ecological Risk Assessment in compliance with the Overview Document (USEPA, 2004) and in accordance with Section 7 of the Endangered Species Act. In orde r to address the risk hypothesis, the potential for adverse effects on the environment is estimated. T he use, environmental fate, an d ecological effects of dichlobenil are characterized and integrated to
assess the risks. This is accomplished using a ris k quotient (ratio of exposure concentration toPage 30 of 51 effects concentration) approach. Although risk is often defined as the likelihood and magnitude of adverse ecological effects, the risk quotient

- based approach does not provide a quantitative
estimate of like lihood and/or magnitude of an adverse effect. However, as outlined in the Overview Document (USEPA

, 2004) , the likelihood of effects to individual organisms from particular uses of dichlobenil is estimated using the probit dose

- response slope and either t he level of concern (discussed below) or actual calculated risk quotient value.

This analysis plan will be revisited and may be revised depending upon a full review of the data available in the open literature and the information submitted by the public in response to the opening of the Registration Review docket.



### 9.1. Stressor s of Concern

The stressors of ecologic al concern for terrestrial organism s are dichlobenil and its main degradate BAM. Submitted studies indicate that BAM toxicity to mammals is similar to that of dichlobenil. More specifically, BAM is slightly more acutely toxic and slightly less toxic on a chronic basis to mammals than dichlobenil. BAM is assumed to have similar toxicity to other
terrestrial animals in the absence of data. Due to the difference in measurement units, assumptions will be made in the risk assessment to compare toxicity of dichlobenil and BAM to terrestrial plants.

The stressor s of concern for aquatic organisms are dichlobenil and, pending results of requested ecotoxicity studies, the aquatic degradate BZZ . Submitted data indicate that BAM is orders of magnitude less toxic to fish, aquatic invertebrates, and aquatic plants than dichlobenil (see
Section 5. 1 )

. If BZZ is found to be of similarly low toxicity, the stressor of concern for aquatic organisms will be dichlobenil alone.

Evaluation of pesticide mixtures is beyond the scope of this assessment because of the myriad factors that cannot be quantified based on the available data. Those factors include identification of other possible co

- contaminants and their concentrations, differences in the pattern and duration of exposure among contaminants, and the differential effects of other physical/chemical
characteristics of the r eceiving waters ( e.g. organic matter present in sediment and suspended water). Evaluation of factors that could influence additivity/synergism is beyond the scope of this assessment and the capabilities of the available data to allow for an evaluation. H owever, it is acknowledged that not considering mixtures could over

- or under

- estimate risks depending on the type of interaction and factors discussed above. The assessment will

, however, analyze the toxicity of formulated products (including formulation s involving more than one active ingredient) and will determine whether formulated products are more toxic than the technical grade active ingredient data used for assessing both direct and indirect risks.



### 9.2. Measures of Exposure

T o estimate risks of dichlobenil exposures in aquatic and terrestrial environments, all exposure modeling and resulting risk conclusions will be based on maximum application rates and
methods cited in Table 1 and will be estimated for each use of dichlobenil. Measures of exposure are based on aquatic and terrestrial models that predict estimated envir onmentalPage 31 of 51 c oncentrations (EEC ) of dichlobenil . The models used to predict aquatic EECs are the Pesticide Root Zone Model coupled with the Exposure Analysis Model ing System (PRZM/EXAMS)

, the provisional Tier II f looded a griculture m odel, PFAM , and the Down

- the

- Drain component of E

FAST

. Additional exposure models may be used to assess use in drains, drain lines, irrigation supply systems, waste water systems, sewage systems, sewer lines, and storm sewers if they are
available. The model used to predict ter restrial EECs on food items is the Terrestrial Residue Exposure ( T

- REX ) . The model used to derive EECs relevant to terrestrial and wetland plants is
TerrPlant. These models are parameterized using relevant reviewed environmental fate data from registrant submissions and the literature; model input values will be consistent with the most recent version of the input parameter guidance ( Version 2 .1 ; USEPA

, 2009 ).

9.2.1. Aquatic Exposure

PRZM ( v 3.12.2; 5/15/2005 ) and EXAMS ( v 2.98.4. 6; 4/25/2005 ) are simulation models coupled
with the linkage program shell PE (v 5 .0; 11/15/06), which incorporates the standard scenarios developed by EFED. The models generate daily exposures and calculate 1

- in

- 10

- year EECs of
dichlobenil that may occur in surface water bodies adjacent to application sites

. PRZM simulates pesticide fate and transport as a result of leaching, direct spray drift, runoff and erosion from an agricultural field. EXAMS estimates environmental fate and transport of pesticides in a
surface wate r body for a 30

- year period. The combined model is designed to estimate pesticide concentrations found in water (standard pond) at the edge of the treated field. As such, it provides high

- end values of the pesticide concentrations that might be found in ecologically sensitive environments following pesticide application. The location of the field is specific to the crop being simulated using site

- specific information on the soils, weather, cropping, and management factors associated with the scenario. Th e crop/location scenario is intended to represent a high

- end exposure site on which the crop is normally grown. Based on historical rainfall patterns, the receiving water body receives multiple runoff events during the years simulated. Weather and agricu ltural practices are simulated for 30 years so that the 10

- year exceedance probability at the site can be estimated. The simulation is generated using 30 years of meteorological data, encompassing the years from 1961 to 1990. Additional information on
the se models can be found at: http://www.epa.gov/oppefed1/models/water/index.htm

.

The standard scenario s used for ecological pesticide assessments assume application to a 10

- hectare agricultur al field that drains into an adjacent 1

- hectare water body that is 2 meters deep (20,000 m 3 volume) with no outlet. PRZM/EXAMS is used to estimate screening

- level exposure of aquatic organisms to dichlobenil . The measure of exposure for aquatic species i s the 1

- in

- 10

- year return peak or rolling m ean concentration. The 1

- in

- 10

- year peak is used for estimating acute exposures of direct effects to aquatic organisms. The 1

- in

- 10

- year 60

- day mean is used for assessing chronic exposure to fish and aquatic

- phase amphibians. The 1

- in

- 10

- year 21

- day mean is used for assessing chronic exposure to aquatic invertebrate s.

The provisional Tier II Pesticides in Floode d Applications Model (PFAM v0.70 ; pre

- release) simulates pesticide transformation on and di ssipation from flooded agricultural sites, such as rice paddies , following pesticide use. This model will be used to estimate exposure from the use of
dichlobenil on cranberries. Up to 11 applications and up to 11 man ually controlled changes in paddy wat er level can be modeled per year of simulation. A Variable Volume Water ModelPage 32 of 51 (VVWM) post

- processing model i s used to simulate pesticide loading via released paddy water into a water body, the parameters of which are under development. Simulations a re ru n using 30 years of location

- specific rainfall data. Peak and maximum mean exposure estimates that are expected once every ten years a re generated based on daily values produced during the simulation. PFAM, its associated post

- processor, and associated d ocumentation are available on

line at: http://sites.google.com/site/pfamodel/

.

The E

- FAST model includes a D own

- the

- Drain component that e stimate s screening aquatic concentrations of compounds that are disposed of or used to treat sewage drains. This model will be used to estimate aquatic exposure from the following uses: drains, drain lines, irrigation supply systems, waste water systems, sewage systems, sewer lines, and storm sewers. Exposure
is esti mated in water bodies receiving outflow from sewage treatment facilities. E

- FAST and
associated documentation are available on

- line at: http://www.epa.gov/oppt/exposure/pubs/efast.htm

. If avai lable, additional exposure models may
be used to assess these uses as well.

Pending results of aquatic toxicity studies on the aquatic degradate BZZ, th is degradate will be
included with dichlobenil in the residues of concern modeled for aquatic exposure

.

9.2.2. Terrestrial Exposure

Ex posure estimates for terrestrial animals assumed to be in the target area or in an area exposed to spray drift are derived using the T

- REX model (version 1.4.1 ; 10/09/2008). This model incorporates the Kenega nom ograph, as modified by Fletcher et al. (1994), which is based on a large set of field residue data. The upper limit values from the nomograph represent the upper bound of residue values from actual field measurements (Hoerger and Kenega, 1972). The
Fletc her et al. (1994) modifications to the Kenega nomograph are based on measured field residues from 249 published research papers, including information on 118 species of plants, 121 pesticides, and 17 chemical classes. Because dichlobenil and the degradate BAM have similar toxicity to terrestrial organisms, a total toxic residues approach will be used fo r terrestrial modeling.

The granular characterization module of T

- REX will also be used as the majority of dichlobenil products are granular formulations. Terrestrial animals may be exposed to granular pesticides by intentionally or inadvertently ingesting granules when foraging for food or grit. They also may be exposed by other routes, such as by walking on exposed granules or drinking water
contaminated by granules. According to the RED (p. 69 ), the registrant provided the following information as inputs for the granular characterization : “ T he smaller granule of the 4% granule formula (4G) (16/30 size), contains approximately 0.0216 mg a

. i

. /granule; the larger granule of the 4G (8/30 size), contains approximately 0.1528 mg a

. i

. /granule. According to information provided by Uniroyal and PBI Gordon, the large granule of the 4G is applied by air, the smaller granule of the 4G is applied by ground equipment or air. The 10% a

. i

. granule (10G) is 8/16 mesh size and contains approximately 0.3276 mg a

. i

. /granule. ” These values will be used in the assessment unless updated information is provided by the registrants.Page 33 of 51 The Scre ening Imbibition Program (SIP version 1.0 ; 6/ 15 / 2010) was used to calculate an upper
bound estimate of dichlobenil exposure via drinking water using dichlobenil’s solubility ( 21 ppm), the most sensitive acute and chronic avia n toxicity endpoints (bobwhite q uail

, LD 50 = 683 mg/kg

- bw and NOAEC = 146 ppm, respectively) and the most sensitive acute and chronic mammalian toxicity endpoints ( r at

, LD 50 = 4250 mg/kg

- bw and NOAEL = 3 mg/kg

- bw, respectively). Drinking water exposure alone was determined to be a pote ntial pathway of
concern for avian and mammalian species on a chronic basis

. Results for avian and mammalian species are presented in Table 8 and Table 9 , respectively.

Table 8 . SIP A vian R esults for D ichlobenil

Parameter Acute Chronic Upper bound exposure (mg/kg

- bw) 17.0100 17.0100 Adjusted toxicity value (mg/kg

- bw) 492.0534 14.3380 Ratio of exposure to acute toxicity 0.0346 1.1864

Conclusion* Drinking water exposure alone is NOT a potential
concern for birds Exposure through drinking water alone is a potential
concern for birds

Table 9 . SIP M ammalian R esults for D ichlobenil

Parameter Acute Chronic Upper bound exposure (mg/kg

- bw) 3.6120 3.6120 Adjusted toxicity value (mg/kg

- bw) 3268.9324 2.3075 Ratio of exposure to toxicity 0.0011 1.5653

Conclusion* Drinking water exposure alone is NOT a potential

concern for mammals Exposure through drinking water alone is a potential

concern for mammals *Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. Therefore, when aggregated with other routes ( i.e. , diet, inhalation, dermal), pesticide exposure through drinking water may contribute to a total exposure that has potential for effects to non

- target animals.

The Screening Tool for Inhalation Risk (STIR version 1.0; 11/23/2010) was used to calculate an upper bound estimate of dichlobenil exposure via inhalation using dichlobenil’s molecular weight (172 g/mole), vapor pressure (5.0 x 10 - 4 torr ), highest granular application rate (10 lb a.i./A), most sensitive acute avia n toxicity endpoint (bobwhite q uail

, LD 50 = 683 mg/kg

- bw ), and most sensitive acute oral and inhalation mammalian toxicity endpoints (rat, LD 50 = 4250 mg/kg

bw and 4 hr LC 50 >3.3 mg/L, respectively). The non

- definitive mammalian i nhalation endpoint
results in a conservative estimate of the LC 50 here. Inhalation alone was determined to be a potential pathway of concern for avian but not for mammalian species. This is based only on vapor inhalation, as droplet inhalation was not as sessed for granular applications. Results for avian and mammalian species are presented in Table 10 and Tabl e 11 , respectively.

Table 10 . STIR A vian (0.020 kg) R esults for Dichlobenil

Maximum Vapor Concentration in Air at Saturation (mg/m 3 ) 4.63E+00

Maximum 1

- hour Vapor Inhalation Dose (mg/kg) 5.82E

- 01

Adjusted Inhalation LD 50 2.96E+00

Ratio of Vapor Dose to Adjusted Inhalation LD 50 1.97E

- 01 Proceed to RefinementsPage 34 of 51 Table 11 . STIR M ammalian (0.15 kg) Results for Dichlobenil

Maximum Vapor Concentration in Air at Saturation (mg/m 3 ) 4.63E+00

Maximum 1

- hour Vapor Inhalation Dose (mg/kg) 7.31E

- 01

Adjusted Inhalation LD 50 1.96E+02

Ratio of Vapor Dose to Adjusted Inhalation LD 50 3.72E

- 03 Exposure not Likely Significant

The drinking water and inhalation pathway s will be explored further with the development of
SIP v.2.0 and STIR v.2.0 in the Ecological Risk Assessment. Detailed information about SIP
v.1.0 and STIR v.1.0, as well as copies of the tool s , can be found on the EPA’s websi te at http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial

.

EECs for terrestrial plants inhabiting dry and wetland areas are derived using TerrPlant (version 1.2.2; 12/26/2006). This model uses estimates of pesticides in runoff and in spray drift to calculate EECs. EECs are based upon solubility, application rate and minimum incorporation depth.

Available monitoring data will be u sed to qualitatively characterize exposure and compare with modeling results. The Agency is aware of monitoring conducted by Federal and state agencies and this route of exposure will be considered in the assessment to the extent that data on
dichlobenil are available.

Two spray drift models, AgDisp (version 8.13; dated 12/14/2004) and AgDRIFT (version 2.01; dated 5/24/2001) will be used to assess exposures of terrestrial plants to dichlobenil deposited in terrestrial habitats by spray drift. AgDRIFT assesses risk out to 2,640 ft from the application site and AgDisp is then used if the risk extends beyond that range. Spray drift may occur during application of the liquid microencapsule formulation of dichlobenil that is applied via aerial

spra y to agricultural and non

- agricultural areas . Spray drift is not a concern for the granular
formulations.



### 9.3. Measures of Effect

Ecological effect data are used as measures of direct and indirect effects to biological receptors.

Data are obtained from registrant

- submitted studies or from literature studies identified by
ECOTOX. The ECOTOX database i s searched in order to provide more ecological effects data to bridge existing data gaps. The most recent dichlobenil update in ECOTOX was in March
2004. ECOTOX is a source for locating single chemical toxicity data and potential chemical mixture toxicity data for aquatic life, terrestrial plants, and wildlife. ECOTOX was created and is maintained by the US EPA, Office of Research and Development, and the National Health and Environmental Effects Research Laboratory's Mid

- Continent Ecology Division ( USEPA, 2007 c ).

Information on the potential effects of dichlobenil on non

- target animals is also collected from the Ecological Incident Information System (EI IS; USEPA

, 2007 b ). The EIIS is a database containing adverse effect (typically mortality) reports on non

- target organisms where such effects have been associated with the use of pesticides.Page 35 of 51 Where available, sub

- lethal effects observed in both registrant

- submitted and open literature studies will be evaluated qualitatively. Such effects have included behavioral changes ( e.g. , lethargy, changes in coloration and olfaction). Quantitative assessments of risks, though, are limited to those endpoin ts 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 assumption that toxicity of dichlobenil to birds is similar to t errestrial

- phase amphibians and reptiles. The same assumption is made for fish and aquatic

- phase amphibians.

The acute measures of effect used for animals in this screening

- level assessment are the LD 50 , LC 50 and EC 50 . LD stands for "Lethal Dose", and LD 50 is the amount of a material, given all at once, that is estimated to cause the death of 50% of the test organisms. LC stands for “Lethal
Concentration” and LC 50 is the concentration of a chemical that is estimated to kill 50% of the test organisms. EC stands for “Effective Concentration” and the EC 50 is the concentration of a chemical that is estimated to produce a specific effect in 50% of the test organisms. Endpoints for chronic measures of exposure for listed and non

- listed animals are the NOAEL /NOAEC and
NOEC. NOAEL stands for “No Observed

- Adverse

- Effect

- Level” and refers to the highest tested dose of a substance that has been reported to have no harmful (adverse) effects on test organisms. The NOAEC ( i.e. , “No

- Observed

- Adverse

- Effect

- Concentr ation”) is the highest test concentration at which none of the observed effects were statistically different from the control.
The NOEC is the No

- Observed

- Effects

- Concentration. For non

- listed plants, only acute exposures are assessed ( i.e. , EC 25 for terrestrial plants and EC 50 for aquatic plants); for listed plants, either the NOAEC or EC 05 is used.



### 9.4. Integration of Exposure and Effects

Risk characterization is the integration of exposure and ecological effects characterization to determine the po tential ecologic al r isk from the use s of dichlobenil listed in Table 1 and the
likelihood of direct and indirect effects to non

- target organisms in aquatic and terrestrial habitats. The exposure and toxicity effects data are integrated in order to evaluate the risks of adverse ecological effects on non

- target species. For the assessment of dichlobenil risks, the risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are divided by acute and chronic toxicity values. The result ing RQs are then compared to the Agency’s LOCs (USEPA

, 2004). These criteria ar e us ed to indicate when uses of dichlobenil , as directed on the label, have the potential to cause adverse direct or indirect effects to non

- target organisms

. As noted previou sly, where data are lac king on the toxicity of dichlobenil , risk will be presumed.

9.4.1. Deterministic and Probabilistic Assessment Methods

The quantitative assessment of risk will primarily depend on the deterministic point

- estimate based approach described in the risk assessment. An effort will be made to further qualitatively describe risk using probabilistic tools that the Agency has developed , provided sufficient data are
available . These tools have been reviewed by FIFRA Scient ific Advisory Panels and have beenPage 36 of 51 deemed as appropriate means of refining assessments where deterministic approaches have
identified risks.



### 9.5. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the Agency will evaluate risks to federally listed threatened and/or endangered (listed) species from registered uses of dichlobenil . This assessment will be conducted in accordance with the Overview Document (USEPA

, 2004), provisions of the ESA, a nd the Services’ Endangered Species Consultation Handbook (USFWS/NMFS

, 1998).

The assessment of effects associated with the registration of dichlobenil is based on an action area. The action area is considered to be the area directly or indirectly affect ed by the federal action, as indicated by the exceedance of Agency LOCs used to evaluate direct or indirect effects. The Agency’s approach to defining the action area under the provisions of the Overview Document (USEPA

, 2004) considers the results of the risk assessment process to establish boundaries for that action area with the understanding that exposures below the Agency’s
defined LOCs constitute a no

- effect threshold. For the purposes of this assessment, attention will be focused on the footprint of the action ( i.e ., the area where dichlobenil application occurs), plus all areas where offsite transport may result in potential exposure that exceeds the Agency’s LOCs. Specific measures of ecological effect that defi ne the action area for listed species include any direct and indirect effects and/or potential modification of its critical habitat, including reduction in survival, growth, and reproduction as well as the full suite of sub

- lethal
effects available in the effects literature. Therefore, the action area extends to a point where environmental exposures are below any measured lethal or sub

- lethal effect threshold for any biological entity at the whole organism, organ, tissue, and/or cellular level of organizati on. In situations where it is not possible to determine the threshold for an observed effect, the action
area is not spatially limited and is assumed to be the entire United States.



### 9.6. Drinking Water Assessment

D rinking water exposure assessment s will be conducted to support future human health risk
assessments of dichlobenil . The drinking water assessment s will incorporate model estimates of
dichlobenil residues of concern, which are parent compound

, BAM , and BZZ ( USEPA, 1998 b ; DP barcode 399718, USE PA

, 2012 )

, in surface and ground waters . The dichlobenil residues of concern may be reevaluated pending receipt and review of additional environmental fate and toxicity data for dichlobenil and its degradates. BAM will be assessed alone because the

compo und has toxicity endpoints that are different from those of dichlobenil and fluopicolide. In the absence of toxicity data, BZZ is assumed to have similar toxicity to dichlobenil. Therefore, BZZ and dichlobenil will be assessed together using a total resi dues of concern approach.

Concentrations in surface waters will be estimated using PRZM/EXAMS and PFAM (see
Section 9.2.1 ). Ground water estimates of concentrations will be estimated using the Tier I model Screening Concentration in Ground Water (SCI

- GROW v2.3, Jul. 29, 2003) and/or

PRZM

- GW (under evaluation) according to current guidance . The drinking water assessment sPage 37 of 51 will a lso include a summary of available surface and ground water monitoring data

. States are encouraged to submit monitoring data for review.



## 10. Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess pote ntial 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 st udies include endpoints which may be susceptible to endocrine influence, including effects on endocrine target organ histopathology, organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, and sex ratios in offspr ing. 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 recent registration decision , 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), dichlobenil is subject to the endocrine screening part of the Endocrine Disruptor Screening Prog ram (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 effect produced by a “naturally occurring estrogen, or other such endo crine 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 assays 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 systems will proceed to the next stage of the EDSP where EPA
will de termine 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, and
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. Dichlobenil was included on that list and has been issued an order to conduct the Tier 1 testing. Once all required Tier 1 and Tier 2 data have been received and reviewed, the endpoints and safety factors used for risk

assessmen t purposes will be examined and a new risk assessment performed if necessary. For further information on the status of the EDSP, the policies and procedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 screening battery, ple ase visit our
website: http://www.epa.gov/endo/

.Page 38 of 51 

## 11 . Preliminary Identification of Data Gaps

11.1. Environmental Fate

Table 12 and Table 13 identify environmental fa te studies by MRID that offer data for each guideline requirement, as well as study classifications and whether or not further data are needed in order to support risk assessment.

Table 12

. Submitted Environmental Fate Data for Dichlobenil

OCSPP
Guideline Data Requirement Submitted
Studies (MRID) Study
Classifications Sufficient
for
EFED? Current Additional Data Need

835.2120 Hydrolysis 40548502/
41012101 Acceptable Yes

--

835.2240 Aqueous photolysis 40490001/
40490002 Unacceptable Yes

--

41709801 Acceptable

835.2410 Soil photolysis 41119001 Unacceptable Yes

-- 43006801 Supplemental

835.4100 Aerobic soil
metabolism 153745 Unacceptable No A guideline

- compliant study of t hree
additional soils is needed. 41340601/
43006803 Acceptable

835.4200 Anaerobic soil
metabolism (None) (Not applicable ) Yes

--

835.4300 Aerobic aquatic
metabolism 41 149501 Acceptable Yes

--

835.4400 Anaerobic aquatic
metabolism 41306001 Acceptable Yes

--

835.1230
835.1240 Adsorption/ desorption and leaching 151561 Unacceptable Yes

-- 40600604 Unacceptable

4 1709802 A cceptable

43611101 A cceptable

835.1410 Volatility

– laboratory 43754001 Acceptable Yes

--

835.6100 Terrestrial field dissipation 41149502/
41280802 Unacceptable Yes Analytical methods MRID 49725 and 41149502 are upgradeable if validated by independent laboratories

. However, independent laboratory validation is not needed to support the submitted field studies because they were submitted prio r to 1996. 41170801 Unacceptable

41385601 Acceptable

43564901/
43522701 Supplemental

Analytical
method in soil 49725 Upgradeable

41149502 UpgradeablePage 39 of 51 OCSPP
Guideline Data Requirement Submitted
Studies (MRID) Study
Classifications Sufficient
for
EFED? Current Additional Data Need

835.6200 Aquatic field dissipation 41780601 Acceptable No Analytical methods MRID 38630, 4 24 92

, 44712701, and 45321801 are upgradeable
if validated by independent laborator ie s. A successful independent validation of
MRID 45321801 is needed. 41877301 /
42191401 Acceptable

Analytical
method in water 38630 Upgradeable

42492 Upgradeable

44712701 Upgradeable

45321801 Upgradeable

165

- 4 (850.1730) Fish
bioconcentration 41780601 Upgradeable Yes A dditional data are not need ed because
dichlobenil ’s K OW and fish BCF values
indicate that the compound will not bioconcentrate in aquatic animals. 42191401 Upgradeable

40465801/
404658 02 Supplemental

Non

guideline Analytical
method in mud 42495 Upgradeable (Not applicable) Analytical methods MRID 42488, 42495, 43924401, and 43924402 are upgradeable
if validated by independent laborator i es

. Analytical
method in fish 42488 Upgradeable

Analytical
method in
salt wate r 43924401 Upgradeable

43924402 Upgradeable

Table 13

. Submitted Environmental Fate Data for the Dichlobenil Degradate , BAM

OCSPP
Guideline Data Requirement Submitted
Studies (MRID) Study
Classifications Sufficient
for
EFED? Current Additional Data Need

835.2240 Aqueous photolysis 45280303 Acceptable Yes

--

835.4100 Aerobic soil
metabolism 45575901 Acceptable Yes MRID 45575901 was conducted with only two soils. However, additional data are not needed because they are not expected to substantially change the study results.

835.4300 Aerobic aquatic
metabolism 45539401 Unacceptable No A guideline

- compliant study that confirms microbial activity throughout the study is
needed.

835.123 0 Adsorption/ desorption 45539402 Acceptable Yes

--

Non

guideline Analytical
method in mud 42496 Upgradeable No Analytical methods MRID 4 24 9 6, 42489, 42494, 44712701, and 45321801 are upgradeable if validated by independent laboratories. A successful independent
validation of MRID 45321801 is needed. Analytical
method in fish 42489 Upgradeable

Analytical
method in wate r 42494 Upgradeable

44712701 Upgradeable

45321801 Upgradeable

Environmental fate data for BZZ have not been submitted. Because BZZ is a residue of concern in drinking water exposure assessments, an adsorption/desorption study is needed.

T o clarify, t h e following environmental fate data are needed for dichlobenil exposure

assessment:Page 40 of 51 Aerobic Soil Metabolism Study: Guid eline 835.410 0 A guideline

- compliant aerobic soil metabolism study of three soils is needed for dichlobenil

. These study data are useful for aquatic exposure modeling.

Aerobic Aquatic Metabolism Study: Guideline 835.4300 A guideline

- compliant aerobic aquatic metabolism study of two s ystems is needed for BAM. Microbial activity should be confirmed throughout the study. This study is important because BAM is a residue of concern in drinking water assessments for dichlobenil and fluopicolide.

Adsorption/Desorption Study: Guideline 835.1230 A guideline

- compliant batch equilibrium study of five soils is needed for B ZZ

. This study is important because BZZ is a residue of concern in drinking water assessments for dichlobenil.

Independent Laborat ory Validation : Part of Guideline 835. 62 00 Independent laboratory validation (ILV) is needed for the most recently submitted environmental chemistry method (ECM) in water, MRID 45321801. If independently validated, the level of quantitation (LOQ) for dic hlobenil and BAM (0.1 0 μ g/L) will be less than toxicological levels of concern for each compound. Without independent validation, there is uncertainty in the reported LOQ and whether the actual LOQ is less than toxicological levels of concern.



### 11. 2. Effects

Table 14 and Table 15 identify ecolog ical effects studies by MRID that offer data for each guideline requirement, as well as study classifications and whether or not further data are needed in order to support risk assessment. Rationale for the additional data requested is presented
below th e tables.

For the major degradate BAM, acute and chronic toxicity data are available for mammals, freshwater fish, and freshwater invertebrates and toxicity data is also available for terrestrial plants and for vascular and non

- vascular aquatic plants. T his data is nearly sufficient for the registration review risk assessment for dichlobenil , with one exception. Table 17 identifies an activated sludg e respiration inhibition study that is needed for the effects assessment. A rationale for this request is presented below the table and in Appendix A

.

For the major aquatic degradate BZZ, no toxicity data are available. Table 17 identifies ecological effects studies that are needed for the effects assessment and rationale for these requests is presented below the table.

Table 14

. Submitted A quatic E cological E ffects D ata for D ichlobenil

OCSPP
Guideline Data Requirement Submitted
Studies (MRID) Study
Classifications Sufficient
for
EFED? Current Additional Data Need

850.1010 Freshwater
invertebrate acute toxicity 00500149 Supplemental Yes

--

40094602 Supplemental

40775001 AcceptablePage 41 of 51 OCSPP
Guideline Data Requirement Submitted
Studies (MRID) Study
Classifications Sufficient
for
EFED? Current Additional Data Need

850.1025
850.1035
850.1045
850.1055 Saltwater
invertebrate acute toxicity 40228401 Supplemental Yes

--

43905404 Acceptable

43905405 Acceptable

850.1075 Freshwater fish acute toxicity 00115756 Supplemental Yes

--

43846901 Acceptable

40098001 Supplemental

850.1075 Saltwater fish acute toxicity 40228401 Supplemental Yes

--

43905403 Acceptable

850.1300 Freshwater
invertebrate life cycle 40775002/
42224201 Acceptable Yes

--

850.1350 Saltwater
invertebrates life cycle (None) (N/A) No A guideline compliant saltwater invertebrate life cycle test is needed.

850.1400 Freshwater fish early

- life stage 42224202 Supplementa l No A new guideline compliant study is
needed to establish a definitive chronic
NOAEC for freshwater fish.

850.1400 Saltwater fish early

- life stage (None) (N/A) Yes

--

850.1500 Fish life cycle (None) (N/A) Yes

--

850.4400 Aquatic plant

g rowth:
Tier II vascular plants 40758203 Acceptable Yes

--

850.5400 Aquatic Plant
Growth: Tier II algae 40228401 Supplemental Yes

--

40758201 Acceptable

40758202 Acceptable

40758204 Acceptable

40758205 Acceptable

850.3300 A ctivated sludge respiration
inhibition (None) (N/A) No A study is needed to assess impacts to
wastewater treatment facilities.

T he following aquatic toxicity data are needed for dichlobenil ecological effects assessment:

Aquatic Invertebrate Life Cycle Test (Saltwater) : Guideline 850.1350 Data regarding the chronic toxicity of dichlobenil TGAI to marine/estuarine invertebrates have not been submitted to the Agency. Acute toxicity data for marine/estuarine invertebrates are conditionally required under 40 CFR Part 158 ( 2010) data requirements for pesticides with outdoor uses. Dichlobenil may enter estuarine/marine systems through runoff from treated areas.
The estimated 21

- day EEC in water from the RED is >0.01 of the acute EC 50 value for EasternPage 42 of 51 oyster shell growth and the freshwater invertebrate life cycle study indicates that dichlobenil may affect reproductive physiology. Therefore, these data are necessary to determine if chronic exposure to dichlobenil TGAI may adversely affect the survival, growth, or reproduction of
marine/estuarine invertebrates.

Fish Early

- Life Stage Test (Freshwater) : Guideline 850.1400
Fish early

- life stage data are required for one freshwater fish species. If the test species is not one for which an acute toxicity value is currently available, a 96

- hr LC 50 value on that species must also be provided. For dichlobenil, 96

- hr LC 50 values are available for the rainbow trout, bluegill sunfish, fathead minnow, goldfish, and green sunfish. One early

- life stage test with the rainbow trout was submitted to the agency previously (MRID 40825101 / 42224202 ). This study does not fulfill the guideline requirement due to the failure to establish a NOAEC. Statistically significant reductions in length were seen at 34 days post

- h atch in all concentrations tested. While this effect was not statistically significant at the two lowest concentrations at 60 days post

hatch, the effect remained evident in the data and may have been biologically significant. Additionally, a transitory effect may have biological consequences of concern. Therefore, these data are necessary to determine the dichlobenil NOAEC and LOAEC for survival, growth, and reproduction of freshwater fish.

Activated Sludge Respiration I nhibition : Guideline 850. 3300 Data regarding the impact of dichlobenil TGAI to activated sludge are needed to assess impacts to wastewater treatment facilities (and, potentially, secondary impacts to aquatic organisms downstream from such facilities).

Table 15

. Submitted Terrestrial E cological E ffects D ata for D ichlobenil

OCSPP
Guideline Data Requirement Submitted
Studies (MRID) Study
Classifications Sufficient
for
EFED? Current Additional Data Need

850.2100 Avian oral toxicity 00160000 Supplemental No Acute oral toxicity data are necessary for a passerine species. 43469801 Acceptable

850.2200 Avian dietary toxicity 00022923 Supplemental Yes

--

40600602 Acceptable

40600603 Acceptable

850.2300 Avian reproduction 45280301 Supplemental No A new guideline compliant study is
needed to establish a definitive chronic
NOAEC for an upland game species. 45280302 Acceptable

Non

guideline Avian
inhalation (None) (N/A) Yes An avian inhalation study is not requested due to the long terrestrial field dissipation half

- lives, which indicate that the potential volatilization rate is not realized in the field, and the low screening RQ from the STIR model (0.2).

850.3020 Honey bee

acute contact toxicity 00018842 Acceptable Yes

--Page 43 of 51 OCSPP
Guideline Data Requirement Submitted
Studies (MRID) Study
Classifications Sufficient
for
EFED? Current Additional Data Need

850.3030 Honey bee
residue on foliage (None) (N/A) Yes

--

850.3040 Field testing for pollinators (None) (N/A) Yes

--

850.4100 Terrestrial

p lant toxicity: Tier II seedling

emergence 41280801 Supplemental Yes

--

850.4150 Terrestrial

p lant toxicity:
Tier II vegetative vigor 41280801 Invalid No A guideline compliant vegetative vigor study is needed.

T he following terrestrial toxicity data are needed for dichlobenil ecological effects assessment:

Avian A cute O ral T oxicity T est ( Passerine S pecies): Guideline 850.2100 Acute avian oral toxicity data are required for either one waterfowl or one upland game species and one passerine species under the 40 CFR Part 158 (2010) data requirements for conventional pesticides with outdoor uses. Submitted acute oral avian effects data show LD 50 s of 683 mg a.i./kg

- bw for the bobwhite quail (MRID 43469801), 1189 mg a.i./kg

- bw for the ring

- necked pheasant, and >2,000 mg a.i./kg

- bw for the mallard duck (MRID 00160000). Because passerine species have higher metabolic rates due to their smaller sizes than either waterfowl or upland game bird species and because they may utilize different metabolic pathways, they may be more
or less sensitive to dichlobenil. The RED assessment demonstrated LOC exceedance from ingestion of dichlobenil granules to listed and non

- listed birds based on the bobwhite quail LD 50

. A passerine study protocol should be submitted for review by the Agency prior to initiation of the study.

Avian R eproduction : Guideline 850.2300 Avian reproduction data are required for one waterfowl and one upland game species for all outdoor use pesticides. These data were requested in the RED and subsequently submitted to the Agency. The study using the mallard duck was found to be an acceptab le study. The study using the bobwhite quail was found to be supplemental and does not fulfill the guideline requirement due to the failure to establish a definitive NOAEC value. Reproductive effects were observed at the lowest concentration tested, 146 ppm (MRID 45280301 ). Therefore, an acceptable avian reproduction study for one upland game species, preferably the bobwhite quail, is necessary to determine the dichlobenil NOAEC and LOAEC for survival, growth, and reproduction of this species.

Terrestri al Plant Toxicity (Vegetative Vigor) : Guideline 850.4150 Acceptable d ata regarding the toxicity of dichlobenil to terrestrial plants have not been submitted to the Agency. These data are required under the 40 CFR Part 158 (20 1 0) data requirements for
pest icides with outdoor uses. At the time of the RED, the Agency did not request a newPage 44 of 51 vegetative vigor study because vegetative vigor studies are not generally required for granular formulations. However, since 2007 dichlobenil has had a liquid microencapsu le formulation registered that is applied via aerial spray. Vegetative vigor data are necessary to determine
whether the outdoor use of the microencapsulated formulation of dichlobenil could adversely
affect vegetative vigor of non

- target plant species in the terrestrial environment. If a Tier I study exhibits a ≥25% effect, or if a NOAEC cannot be established when conducted as a limit test, a Tier II study is required.

Table 16

. A quatic E cological E ffects D ata for the Dichlobenil Degradate , BAM

OCSPP
Guideline Data Requirement Submitted
Studies (MRID) Study
Classifications Sufficient
for
EFED? Current Additional Data Need

850.3300 A ctivated sludge respiration
inhibition (None) (N/A) No A study is needed to assess impacts to
wastewater treatment facilities.

T he following aquatic toxicity data are needed for dichlobenil ecological effects assessment:

Activated Sludge Respiration I nhibition : Guideline 850. 33 00 Data regarding the impact of the major aquatic dichlobenil degradate BAM to activated sludge are needed to assess impacts to wastewater treatment facilities (and, potentially, secondary impacts to aquatic organisms downstream from such facilities). A sample Data Call

- In (DCI) table is provided in Appendix A

.

Tab le 17

. A quatic E cological E ffects D ata for the Dichlobenil Degradate , BZZ

OCSPP
Guideline Data Requirement Submitted
Studies (MRID) Study
Classifications Sufficient
for
EFED? Current Additional Data Need

850.1075 Freshwater fish acute toxicity (None) (N/A) No A guideline compliant freshwater fish acute toxicity study is needed.

850.4400 Aquatic plant

g rowth:
Tier II vascular plants (None) (N/A) No A guideline compliant vascular aquatic plant study is needed.

T he following aquatic toxicity data are needed for dichlobenil ecological effects assessment:

Fish Acute Toxicity Test (Freshwater): Guideline 850.1075 Data regarding the acute toxicity of major aquatic dichlobenil degradate BZZ to aquatic organisms have n ot been submitted to the Agency. Acute toxicity data for the freshwater fish
rainbow trout ( Oncorhychus mykiss ), the most acutely sensitive freshwater aquatic animal to the parent, dichlobenil, are needed to determine if exposure to the degradate may adve rsely affect the
survival of freshwater animals. High application rates and a lack of reliable toxicity estimates
from ECOSAR , the Agency’s Ecological S tructure Activity Relationships program, result in the need for empirical data.Page 45 of 51 Vascular Aquatic Plant Toxicity Test: Guideline 850.4400 Data regarding the acute toxicity of aquatic dichlobenil degradate BZZ to aquatic plants have not been submitted to the Agency. Toxicity data for duckweed ( Lemna gibba )

, the most sensitive aquatic plant to the parent, di chlobenil, are needed to determine if exposure to the degradate may adversely affect the survival or growth of freshwater plants

. High application rates and a lack of reliable toxicity estimates from ECOSAR, the Agency’s Ecological S tructure Activity
Rela tionships program, result in the need for empirical data.



## 12 . References

MRID Citation
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40465802 Forbis, A. (19 86) Uptake, Depuration and Bioconcentration of 14 C

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40600607 Jager, H.; Harteveld, J. (1987) The Vapour Pressure of 2,6

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40 600608 Thus, J. (1984) Determination by HPLC of the Log P Value of Dichlobenil and its Main
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41012101 Pouwelse, A. (1983) Stability and Solubility of Dichlobenil in Wa ter Additional Data to Report 56630/207/87 (MRID No. 40548502): Project ID: 82

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41149501 Gohdes, M. (1989) Aerobic Aquatic Metabolism of ?Carbon 14| Dichlo

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41306001 Saxena, A. (1 989) Anaerobic Aquatic Metabolism of 14 C

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41340601 Walstra, P.; Groeneveld, A.; VanderLaan

- Straathof, J.; et al. (1989) Aerobic Soil M etabolism of Dichlobenil in Sandy Loam: Project Number: C

- 201

- 62

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41385601 Hughes, D. (1990) Determination of Dichlobenil and 2,6

- Dichlorobenzamide in Soil from a Hillsboro, Oregon Field Trial: Lab Project Number: HLA 6012

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41709801 Boelhouwers, E.; Jo ustra, K.; Klein, G. et al. (1989) Photodegradation of [ 14 C]Dichlobenil in Water: Lab Project Number: C.201.62.010. Unpublished study prepared by Duphar B.V. 74 p.

41780601 Jacobson, B.; Judy, D.; Whithaus, M. (1991) Combined Aquatic Field Dissipation an d Bioaccumulation Study on Aquatic Non

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41877301 Jacobson, B.; Judy, D.; Whithaus, M. (1991) Combined Aquatic Field Dissipation and Bioaccumulation Study on Aquatic Non

- Target Organisms for Casoron 10G in Oregon: Lab Project Number: 36832: 56635/01/91: C 201 60 006. Unpublished study prepared by Analyti cal
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Non

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43006 801 Kabler, K.; Carpenter, M. (1993) Photodegradation Study of 14 C

- Dichlobenil on Soil Surface: Amended Final Report: Lab Project Number: 37135: CA

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43006803 Judy, D. (1993) A C omparison of the Udenhout Soil from the Netherlands with Soil Types from the United States: Final Report: Lab Project Number: 41226: 56835/50/93. Unpublished study prepared by ABC Labs, Inc. 22 p.

43522701 Pouwelse, A.; van Loo, T. (1991) 2,6

- Dichloroben zonitrile and 2,6

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43564901 Pouwelse, A.; van Loo, T. (1991) 2,6

- Dichlorobenzonitrile and 2,6

- Dichlorobenzamide Residues in Soil from 4 Terrestrial Field Dissipation Trials with Casoron G (Germany 1989/1990): Lab Project Number: C/201/60/0 08: 56630/87/91. Unpublished study prepared by Duphar B.V. Analytical Development Dept. 76 p.

43754001 Van der Laan

- Straathof, J. (1995) Determination of the Volatility of Dichlobenil from Casoron G

4 Under Laboratory (Simulated Field) Conditions: Lab Pr oject Number: C.201.62.020: 56834/13/95. Unpublished study prepared by Solvay Duphar B.V. 33 p.

45280303 Reynolds, J. (2000) Photolysis of [ 14 C] 2,6

- Dichlobenzamide in Water Buffered at pH 5: Lab Project Number: XBL00041: RPT00626: 2000

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45539401 Whitright, R. (2001) Aerobic Aquatic Metabolism of [ 14 C] 2,6

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45539402 Dzialo, D. (2001) Adsorption/Desorption of [ 14 C] 2,6

- Dichlobenzamide: Lab Project Number: 00

- 1561: 00

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45575901 Griffen, D.S. (2002) Aerobic Soil Metabolism of 14 C

- 2,6

- Dichlorobenzamide ( BAM): Study No.
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43611101 Thus, J.; van der Laan

- Straathof, J. (1995) Adsorption/Desorption Test with Dichlobenil in Four Different Agricultural Soils and One Hydrosoil: Lab Project Number: C/201/62/019: 56835/53/94. Unpublished study prepared by Solvay Duphar B.V. Environmental Re search Dept. 51 p. Ecological Effects Studies

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- B.
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00112500 International Bio

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- B)

00147437 Koeter, H. (1984) Oral Embryotoxicity/Teratogenicity Study with Dichlobenil in Rats: Final Report: Report No. V 84.026/231045. Unpubl ished study prepared by Netherlands Organization for Applied Scientific Research. 109 p.

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40094602 Johnson, W.; Finley, M. (1980) Handbook of Acute Toxicity of Chemicals to Fish and Aquatic
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40098001 Mayer, F.; Ellersieck, M. (1986) Manual of Acute Toxicity: Interpretation and Data Base for 410 Chemicals and 66 Species of Freshwater Animals. US Fish & Wildlife Service, Re source Publication 160. 579 p.

40228401 Mayer, F. (1986) Acute Toxicity Handbook of Chemicals to Estuarine Organisms: EPA/600/X

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40600601 Roberts, N.; Hakin, B. (1987) T he Acute Oral Toxicity (LD50) of Dichlobenil to the Mallard Duck: PDR 474/871611. Unpublished study prepared by Huntingdon Research Centre Ltd. 24 p.

40600602 Roberts, N.; Hakin, B. (1987) The Dietary Toxicity (LC50) of Dichlobenil to the Mallard Duck:

PD R 475/871500. Unpublished study prepared by Huntingdon Research Centre Ltd. 18 p.

40758201 Giddings, J. (1988) Toxicity of Dichlobenil to the Freshwater Green Alga: Laboratory Project ID
11493

- 0787

- 6107

- 550. Unpublished study prepared by Springborn Life S ciences, Inc. 31 p.

40758202 Giddings, J. (1988) Toxicity of Dichlobenil to the Blue

- green Alga: Anabaena flos

- aguae: Laboratory Project ID 11493

- 0787

- 6107

- 550. Unpublished study prepared by Springborn Life Sciences, Inc. 28 p.

40758203 Giddings, J. (1987) Toxicity of Dichlobenil to the Freshwater Plant: Lemna gibba G3: Laboratory Project ID 11493

- 0787

- 6108

- 550. Unpublished study prepared by Springborn Life Sciences, Inc. 22 p.

40758204 Giddings, J. (1988) Toxicity of Dichlobenil to the Freshwater Di atom: Navicula pelliculosa: Laboratory Project ID 11493

- 0787

- 6107

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40775001 Burgess, D. (1987) Acute Flow

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40775002/
42224201 Forbis, A. (1988) Chronic Toxicity of Dichlobenil to Daphnia magna Under Flow

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41257302 Barker, L. (1989) Dichlbenil: Oral (Gavage) Teratology Study in the Rabbit (Experiment II): Repeat Study: Laboratory Project ID 5942

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41257303 Leeming, N. (1989) Dichlobenil: 2 Generation Oral (Dietary Administration) Reproduction Study in the Rat: Laboratory Project ID 5798

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p. 41280801 Eussen, J. (1989) The Effect of Dichlobenil on Seed Germination, Seedling Emergence and Vegetative Vigor of Non

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42224202 Dykstr a, A. (1992) Early Life

- stage Toxicity of Dichlobenil to Rainbow Trout (Salmo Gairdner)
in a Flow

- Through System

— Raw Data: Lab Project Number: 36182. Unpublished study prepared by Analytical Bio

- Chemistry Laboratories, Inc. 905 p.

42239101 Barker, L. (199 2) Dichlobenil: 2 Generation Oral (Dietary Administration) Reproduction Study in
the Rat: Addendum 1

-- Pathology Report: Lab Project Number: 5798

- 65/18,A

- 1. Unpublished study prepared by Hazleton, Harrogate (UK). 18 p.

42940201 Koopman, T. (1981) Acute Ora l Toxicity Study with 2,6

- Dichlorobenzamide in Mice: Lab Project Number: DT 30/81: 56645/37/81. Unpublished study prepared by Duphar, B.V. 17 p.

43003601/
43265201 McIntyre, M. (1986) 2,6

- Dichlorobenzamide: Oral (Gavage) Teratology Study in the Rabbit:

La boratory Project ID 5308

- 65/9. Unpublished study prepared by Hazleton Laboratories Europe Ltd. 106 p.

43335703 Cracknell, S. (1994) Casoron W

- 85: Acute Inhalation Toxicity in the Rat: Final Report: Lab Project Number: SVP/008: 93/SVP008/1088: 56345/12/94. Unpublished study prepared by
Pharmaco

- LSR Ltd. 67 p.

43469801 Johnson, I. (1994) Dichlobenil Technical: Acute Oral Toxicity Study in the Bobwhite Quail: Final Report: Lab Project Numbers: SVP/007: 94/SVP007/0412: 56345/52/94. Unpublished study prepared by Pharmaco LSR, Ltd. 39 p.Page 48 of 51 MRID Citation
43905403 Dunham, M.; Davis, J. (1995) Dichlobenil Technical: Acute Toxicity to Sheepshead Minnow (Cyprinodon variegatus) Under Flow

- Through Conditions: Lab Project Number: J9505004D: J9505004A. Unpublished study prepared by Tox ikon Environmental Sciences. 53 p.

43905404 Dunham, M.; Davis, J. (1995) Dichlobenil Technical: Acute Effect on New Shell Growth of the Eastern Oyster (Crassostrea virginica): Lab Project Number: J9505004E: J9505004A. Unpublished study prepared by Toxikon Environmental Sciences. 55 p.

43905405 Dunham, M.; Davis, J. (1995) Dichlobenil Technical: Acute Toxicity to the Mysid (Mysidopsis bahia) Under Flow

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## Appendix A. Sample Data Call

- In Table

The followi ng proposed Data Call

- in table includes a rationale for requiring the activated sludge respiration inhibition data requested in this problem formulation, an explanation of the utility of the data, and an explanation for how the data might impact risk assessment, following the format provided by the Pesticide Re

- evaluation Division.

Guideline Number: 850. 3300 Study Title: Activated Sludge Respiration I nhibition Rationale for Requiring the Data
The Agency ha s a limited understanding of the impact of dichlobenil and its major degradate BAM on wastewater treatment facilities following the use of dichlobenil in wastewater collection systems

. Depending on how quickly and to what extent dichlobenil, BAM, or both compounds inhibit activated sludge respiration

, u se of dichlobenil in wastewater collection systems may or may not pose potential interference with wastewater treatment facilities (and potential secondary impacts to aquatic organ isms downstream from such facilities)

.

In order to better understand the impact of dichlobenil and its major degradate BAM on wastewater treatment facilities following the use of dichlobenil in wastewater collection systems , the Agency is requiring an act ivated sludge respiration inhibition study of dichlobenil TGAI and of its major degradate

BAM

. Practical Utility of the Data
How will the data be used? Submission of an acceptable activated sludge respiration inhibition study will facilitate a better understanding of whether dichlobenil use in wastewater collection systems may impact wastewater
treatment facilities . If data indicate that dichlobenil, BAM, or both compounds inhibit activated sludge respiration at concentr ations relevant to wastewater treatment facilities , then the Agency could potentially determine that dichlobenil use in wastewater collection systems may impact wastewater treatment facilities and may result in secondary impacts to aquatic organisms downst ream from such
facilities . If data indicate that dichlobenil, BAM, or both compounds do not inhibit activated sludge respiration at concentrations relevant to wastewater treatment facilities , then the Agency could potentially determine that use of dichlob enil in wastewater collection systems is not expected to impact
wastewater treatment facilities.

How could the data change the Agency’s decision, or impact the Agency’s future decision

making? In the absence of adequate activated sludge respiration inhibition data, dichlobenil use in wastewater collection systems will be assumed to pose a potential hazard to wastewater treatment facilities and to aquatic organisms downstream from such facilities . If the required data indicate that dichlobenil and

BA M do not inhibit activated sludge respiration at concentrations relevant to wastewater treatment
facilities , then risk assessment conclusions and associated labeled use precautions and/or restrictions could change.