### 1 OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

### UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON

, D.C. 20460

October 27, 2014

PC Code: 109601 MEMORANDUM DP Barcode: 421174

SUBJECT: EFED Registration Review Problem Formulation for Dikegulac-sodium

FROM: Elyssa Arnold, Biologist Greg Orrick, Environmental Scientist Environmental Risk Branch 2 Environmental Fate and Effects Division (7507P)

REVIEWED Christine Hartless, Ph.D., Wildlife Biologist BY: R. David Jones, Ph.D., Senior Agronomist Jean Holmes, DVM, MPH, Risk Assessment Process Leader Environmental Risk Branch 2 Environmental Fate and Effects Division (7507P)

THROUGH: Brian Anderson, Branch Chief Environmental Risk Branch 2 Environmental Fate and Effects Division (7507P)

TO: Matthew Manupella, Chemical Review Manager Cathryn Britton, Team Leader Kevin Costello, Branch Chief Risk Management and Implementation Branch 2 Pesticide Re-evaluation Division (7508P) 2014.10.27 12:24:05 -04'00'
Date: 2014.10.27 12:28:55 -04'00'

2014.10.28 11:50:48 -04'00'

ROBERT JONES 2014.10.28 12:56:37 -04'00' Holmes, Jean 2014.10.28 14:42:00 -04'00'

Anderson, Brian 2014.10.28 15:59:03 -04'00'

### 2 

# 

1. Executive summary ............................................................................................................. .... 3 2. Introduction .................................................................................................................. ........... 4

a. Mode of Action ................................................................................................................ .... 4 3. Use Characterization .......................................................................................................... ..... 4 4. Conclusions from Previous Risk Assessments ....................................................................... 5

a. Ecological Risk Assessment ................................................................................................ 5 b. Drinking Water Exposure Assessments ............................................................................... 7

c. Clean Water Act Programs .................................................................................................. 7 5. Environmental Fate and Transport.......................................................................................... 8

a. Transformation Products ...................................................................................................... 9 6. Receptors...................................................................................................................... ......... 12

a. Effects to Aquatic Organisms ............................................................................................ 13 b. Effects to Terrestrial Organisms ........................................................................................ 14

c. Ecological Incidents .......................................................................................................... . 14 7. Exposure Pathways of Concern ............................................................................................ 15 8. Analysis Plan ................................................................................................................. ....... 15

a. Stressors of Concern .......................................................................................................... 15 b. Measures of Exposure ........................................................................................................ 1 6

c. Measures of Effect ............................................................................................................ . 16 d. Endangered Species Assessments ...................................................................................... 16

e. Endocrine Disruptor Screening Program ........................................................................... 16 9. Preliminary Identification of Data Gaps ............................................................................... 17

a. Environmental Fate ............................................................................................................ 17 b. Effects ....................................................................................................................... ......... 18 10. References .................................................................................................................... ...... 23

a. Submitted Environmental Fate Studies .............................................................................. 24 b. Submitted Ecological Toxicity Studies .............................................................................. 24 Appendix A. Dikegulac-sodium Ecotoxicity Data ....................................................................... 27

### 3 

# 1. Executive summary

The Environmental Fate and Effects Division (EFED) has completed the preliminary problem formulation for the ecological risk, environmental fate, endangered species, and drinking water assessments to be conducted as part of the registration review of dikegulac-sodium. The problem formulation describes the methods planned to be used during the completion of drinking water and ecological risk assessments in support of registration review and provides an overview of the environmental fate, ecological effects, potential risks associated with the use, and uncertainties unique to the risk assessment of dikegulac-sodium. This document also identifies additional studies that would be beneficial to the conduct of an ecological risk
assessment.

The dikegulac-sodium Reregistration Eligibility Decision (RED) was completed in 2007. Sincethat time, there have been no substantial changes to the registration or use patterns of dikegulacsodium. The RED concluded that there is risk of adverse effects to terrestrial plants and organisms that depend on them for survival, growth, or reproduction at or near its application site. The conclusions from the RED remain unchanged, and an updated, full ecological risk assessment is not needed for registration review. EFED recommends that additional data be requested to allow for a more comprehensive evaluation of potential effects to honey bees, consistent with Guidance for Assessing Pesticide Risks to Bees (USEPA et al. , 2014). EFED will evaluate those data when they are submitted and will work with Pesticide Re-evaluation Division (PRD) to address any risks of concern identified by those data.

The following are the needed data and uncertainties for dikegulac-sodium:

Data Needs

x Fate Data

o None

x Ecotoxicity Data

o Non-guideline: Honey bee acute oral toxicity

o Non-guideline: Honey bee acute and chronic larval toxicity

o Non-guideline: Honey bee adult chronic 10-day toxicity

Some data gaps are not identified as data needs at this time (see Section 9 for details) due to the limited use patterns and low overall usage of dikegulac-sodium in the United States. If usage of dikegulac-sodium significantly increases in the future, data needs for risk assessment may also change.

Other Major Uncertainties

x Some label directions are ambiguous. The maximum single application rate for ornamental olive, glossy privet, multiflora rose, and Japanese holly is not stated on pages 8-9 of EPA Reg. No. 2217-776. The reapplication interval for greenhouse and nursery ornamentals is not stated on page 11 of EPA Reg. No. 2217-776. The maximum

### 4 application rate of 11 lbs a.i./acre on EPA Reg. No. 2217-932 might be underestimated because the label says “large plants may require higher spray volumes” (p. 4).


# 2. Introduction

Dikegulac-sodium is a plant growth regulator that was first registered in 1978. It is used on ornamentals, nursery crops, and trees to reduce growth, flowering, and/or fruit set. Three end-use formulations containing dikegulac-sodium are currently registered for use in the United States. Dikegulac-sodium was previously assessed at the time of the Reregistration Eligibility Decision (RED) in 2006 (USEPA, 2006b).



## a. Mode of Action

Dikegulac-sodium interferes with terminal growth areas in plants by inhibiting DNA synthesis which is required for new growth. Thus, the dominant growth points (apexes) of treated plants are suppressed, resulting in the breaking of “apical dominance” and the enhancing of the growth of lateral shoots.


# 3. Use Characterization

Dikegulac-sodium is applied as a foliar spray, soil drench, tree trunk injection, or tree trunk spray band. It is used on ornamentals, nursery crops, and trees to reduce growth, flowering, and/or fruit set. Three end-use formulations containing 18.5% dikegulac-sodium are currently registered for use in the United States: Atrinal Plant Growth Regulator SC (EPA Reg. No. 2217-776), Atrinal Nursery and Greenhouse EC (EPA Reg. No. 2217-932), and Pinscher PGR Solution RTU (EPA Reg. No. 69117-7). There is no technical registration in the United States.

Table 1 lists the maximum use patterns for the labeled use sites. Some label directions are ambiguous. The maximum single application rate for ornamental olive, glossy privet, multiflora rose, and Japanese holly is not stated on pages 8-9 of EPA Reg. No. 2217-776. The reapplication interval for greenhouse and nursery ornamentals is not stated on page 11 of EPA Reg. No. 2217- 776. The maximum application rate of 11 lbs a.i./acre on EPA Reg. No. 2217-932 might be underestimated because the label says “large plants may require higher spray volumes” (p. 4).

### 5 Table 1. Maximum Use Patterns for Current Uses of Dikegulac-sodium

EPA Reg. No. Use Max. Single App. Rate (lbs a.i./A) Max. Annual App. Rate (lbs a.i./A) App. Interval (d) App. Type Additional App. Directions

2217-932 Greenhouses, lathhouses, shadehouses, nurseries (field and containerized), tree farms 1.4 - 11+ A 22+ B 14

Foliar spray Use with medium
or coarser spray nozzles. Do not apply through any type of irrigation system. 2217-776 Greenhouse and nursery ornamentals 0.36 - 5.7 C 11 D Not stated

Landscape ornamentals (shrubs, hedges, groundcovers, trees) 1.4 – 4.3 E 8.5 B 14
0.04 lbs a.i./ 12” tree DBH F 0.04 lbs a.i./ 12” tree DBH

Not applicable Bark band, soil drench G Ornamental olive, glossy

privet, multiflora rose, Japanese holly Not stated 1 app./yr Foliar spray

Broadleaf trees in rights-ofway, parks, other areas 0.09 lbs a.i./ 16” tree DBH F 0.09 lbs a.i./ 16” tree DBH Tree injection (none reported here) 69117-7 Ornamental trees 0.0016 lbs a.i./ 30” tree CBH H 0.0032 lbs a.i./ 30” tree CBH 4 - 6 months Tree injection A The application rate varies by treated plant species. The rate of 11 lbs a.i./A reflects use of 4 fl oz product per spray gallon applied at the rate of 2 quarts of spray per 100 sq ft. The label statement “large plants may require higher spray volumes” (p. 4) allo ws for application rates greater than 11 lbs a.i./A in some cases. B Two applications are allowed per year for plants with long growing seasons (p. 4). C The application rate varies by treated plant species. The rate of 5.7 lbs a.i./A reflects us e of 4 fl oz product per spray gallon applied at the rate of 1 gallon of spray per 400 sq ft. D The label states “most plants should be treated only once per year,” (p. 11) allowing for two applications to some plants. E The application rate varies by treated plant species. The rate of 4.3 lbs a.i./A reflects us e of 3 fl oz product per spray gallon applied at the rate of 1 gallon of spray per 400 sq ft. The label allows for higher spray volumes for trees (p. 4), which allows for application rates greater th an 4.3 lbs a.i./A for landscapes with trees. F “DBH” is the diameter of the tree trunk(s) at breast height. G Bark bands are applied with compressed air sprayers, backpack sprayers and other pressurized sprayers at low pressure settings. Soil drenches are applied with “equipment capable of d elivering the drench mixture uniformly around the base of the plant” and “all root flares.” H “CBH” is the circumference of the tree trunk(s) at breast height.



### Public usage data were not located. PBI/Gordon Corp. indicated that typical foliar spray application rates are 3-4 lbs a.i./acre, with one application per year (Focus meeting, Jul. 24, 2014).


# 4. Conclusions from Previous Risk Assessments
a. Ecological Risk Assessment

The only full ecological risk assessment previously conducted for dikegulac-sodium was completed for the Reregistration Eligibility Decision (RED) in 2006 (USEPA, 2006b). The RED assessment concluded that registered uses of dikegulac-sodium had the potential for direct adverse effects on listed and non-listed terrestrial plants. While there were no acute risk concerns identified for freshwater aquatic organisms, mammals, birds or reptiles, the lack of chronic toxicity data for birds, fish, and aquatic invertebrates precluded the ability to identify or exclude

### 6 chronic risks for these taxa. A summary of exceedances of the level of concern (LOC) is listed in Table 2

. Figure 1 and Table 3 summarize the potential risks and the supporting evidence.

Aquatic exposure was modeled in the RED using GENEEC. Two applications of 5.68 lb ae/A with a 10 day application interval were modeled. The resulting estimated exposure concentrations (EEC) for the 1-in-10-year peak, 21-day mean, and 60-day mean measures were 663, 663, and 662 ppb ae, respectively.

Table 2. LOC Exceedances for Recently Assessed Proposed Uses

Effect Taxonomic Group

Birds 1 Mammals Terrestrial Plants Terrestrial Inverts Fish 1 Aquatic Inverts 1 Aquatic Plants Direct Effect LOC Exceedance 

### -- -- 
-- -- -- -- Indirect Effect Potential 

###       

1 Risk conclusions reflect acute exposure only. No chronic toxicity data were available with which to assess chronic risk to birds, fish, or aquatic invertebrates.



### Figure 1. Graphic Summary of Potential Risks of Current Uses

### 7 Table 3. Evidence of Risk to Taxonomic Groups from Dikegulac-sodium Uses Predominant Evidence of Negligible Risk Predominant Evidence of Risk Aquatic Plants: All RQs <LOC for listed and non-listed species. Terrestrial Plants: RQs > LOC (up to 2.3) for semiaquatic areas only. Mammals: No toxicity observed in acute studies. Chronic RQs <1.0. 

### Limited Evidence of Negligible Risk Limited Evidence of Risk Fish & Aquatic Invertebrates: No toxicity observed in acute studies with multiple species. Chronic risk is unlikely; toxicity would have to be 1,000 to 10,000 times greater than acute toxicity to trigger risk concerns. Terrestrial Invertebrates: Risk is presumed in the absence of acute and chronic oral toxicity data for adults and larvae. Dikegulac is system ic in plants so exposure via pollen and nectar are possible. Birds: No toxicity observed in acute studies; no chronic toxicity data are available bu t exposure potential is low due to the limited use pattern


## b. Drinking Water Exposure Assessments

The only drinking water exposure assessment previously conducted for dikegulac-sodium was completed for the Reregistration Eligibility Decision (RED) in 2007 (USEPA, 2007a). Maximum screening exposure estimates for the residues of concern were 950 μ g/L (1-in-10-year peak) and 240 μ g/L (1-in-10-year annual mean) for surface water and 4.8 μ g/L for ground water. Significant uncertainty was associated with these values as a result of limited environmental fate data and low annual production values. Actual drinking water exposure was expected to be negligible. 

## c. Clean Water Act Programs

The Clean Water Act requires the Agency to publish water quality criteria that accurately reflect 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. AnAquatic Life Ambient Water Quality Criteria document has not been published for dikegulacsodium (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. However, aquatic life benchmarks have not been published for dikegulac-sodium (see url: http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm#benchmarks ). Any data submitted or otherwise located as part of the registration review process may be used to update aquatic life benchmarks if applicable.

Dikegulac-sodium 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 dikegulac-sodium, based on information provided at

### 8 http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id =885&p_pollutant_group_name=PESTICIDES

. 

# 5. Environmental Fate and Transport

As a sodium salt, dikegulac-sodium will immediately dissociate into dikegulac acid and sodium ions in water (dikegulac-sodium and its acid are collectively referred to as dikegulac). Thus, dikegulac acid is the form that aquatic organisms will be exposed to. The compound is relatively nonvolatile, hydrophilic, and highly mobile in soil. As a hydrophilic compound, dikegulac will not bioaccumulate. Dikegulac (sodium salt plus free acid) biodegrades in soil with a half-life of 16 days and undergoes abiotic hydrolysis only in acidic conditions. The limited set of chemical properties and environmental fate data for dikegulac are listed in Table 4 . (The test compound in each study was dikegulac-sodium. But the parameters represent total dikegulac due to the immediate dissociation of the sodium salt in water.)

Dikegulac and degradates are not expected to move to ground water due to their rate of biodegradation. However, these compounds may move to surface water bodies via spray drift and runoff of dissolved residues.

Table 4. Chemical Properties and Environmental Fate Parameters of Dikegulac A



### Parameter Value Source Selected Physical/Chemical Parameters Molecular mass (molecular formula) 296.25 g/mol (C 12 

### H 17 

### O 7 

### Na) (Calculated) Vapor pressure (25 °C) 3.1 x 10 -12 

### torr Neely and Blau, 1985 * Aqueous solubility (20 q C) 5.9 × 10 5 

### mg/L Budavari et al., 1996 * Henry’s Law Constant (25°C) 2.1 x10 -18 

### atm-m 3 

### /mol (Calculated) Log octanol-to-water partition coefficient (log K O W 

### ) -2.05 Meylan and Howard, 1995 * Dissociation constants (pKa) Not determined None *

Persistence in Water Hydrolysis half-life (25 q C) pH 5: 5.3 d pH 6: 40 d pH 7: stable pH 9: stable MRID 46932401

Persistence in Soil Aerobic soil metabolism half-life (25°C, pH 6.6) 16 d (ND sandy loam) MRID 46932402 Mobility Freundlich organic carbon-normalized coefficients (K FOC 

### ) 2.5, 4.9, 6.2, 6.7 L/kg OC 

### MRID 46939501

Field Dissipation / Fish Bioconcentration (no acceptable data)

A The test compound in each study was dikegulac-sodium. Bu t the parameters represent total dikegulac due to the immediate dissociation of the sodium salt in water. * The asterisked dikegulac-sodium product chemistry studi es were waived. Cited sources are from USEPA, 2006a.

### 9 

## a. Transformation Products

Dikegulac-sodium immediately dissociates into dikegulac acid and sodium ions in water. Major degradates of dikegulac acid include monoacetyl dikegulac (MA; forming up to 30% of the applied after 21 days in soil), an acid conjugate of monoacetyl dikegulac (M5; forming up to 37% of the applied after 60 days in soil), and carbon dioxide (forming 39% of the applied after 276 days in soil). Chemical names and structures of dikegulac and its degradates are in Table 5

. Environmental fate studies on the degradates of dikegulac were not located.10 Table 5. Dikegulac-sodium and Its Environmental Transformation Products A
Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID Maximum %AR (day) Final %AR (study length)

PARENTDikegulacsodium IUPAC: Sodium 2,3:4,6-di-Oisopropylidene- Į -L-xylo-2- hexulofuranosonate

CAS: Sodium 2,3:4,6-bis-O-(1- methylethylidene)- Į -L-xylo-2- hexulofuranosonate

CAS No.: 52508-35-7

Formula: C 12 H 17 O 7 Na MW: 296.25 g/mol

SMILES: O=C(O[Na])C(OC(O1)(C)C)(OC(C2OC(O 3)(C)C)C3)C12 Dikegulac acid
Diacetonate of

2-keto-Lgulonic acid IUPAC: 2,3:4,6-di-O-isopropylidene- Į -Lxylo-2-hexulofuranosonic acid

CAS: 2,3:4,6-bis-O-(1-methylethylidene)-

Į -L-xylo-2-hexulofuranosonic acid

CAS No.: 18467-77-1

Formula: C 12 H 18 O 7 MW: 274.27 g/mol

SMILES: O=C(O)C(OC(O1)(C)C)(OC(C2OC(O3)(C )C)C3)C12 O

O O O

O

CH 3

C 3 H O O CH 3 C 3 H

Na

O

O O O

O

CH 3

C 3 H O OH CH 3 C 3 H11 Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID Maximum %AR (day) Final %AR (study length)
TRANSFORMATION PRODUCTS Monoacetyl

dikegulac
MA 2,3-o-isopropylidene-2-keto-L-gulonic acid

Formula: C 10 H 16 O 7 MW: 248.23 g/mol Hydrolysis –pH 5 Hydrolysis –pH 6 Hydrolysis –pH 7 Hydrolysis –pH 9 46932401 97% (30 d) 45% (30 d) 14% (30 d) 12% (0 d) 97% (30 d) 45% (30 d) 14% (30 d) 9.6% (30 d)

Aerobic soil 46932402 30% (21 d) n.d. (276 d)

M5 Not reported (acid conjugate of MA)

Aerobic soil 46932402 37% (60 d) 1.5% (276 d)

2-keto 2-keto-L-gulonic acid

Formula: C 6 H 10 O 7 MW: 194.14 g/mol Hydrolysis –pH 5 Hydrolysis –pH 6 Hydrolysis –pH 7 Hydrolysis –pH 9 46932401 3.1% (21 d) 2.4% (4 hr) 1.3% (1 d) 1.5% (30 d) 2.9% (30 d) 2.0% (30 d) n.d. (30 d) 1.5% (30 d)

Aerobic soil 46932402 7.0% (190 d) 6.8% (276 d)

Unextracted residues Not applicable Not applicable Aerobic soil 46932402 21% (120 d) 20% (276 d)

Carbon dioxide Carbon dioxide

Formula: CO 2 MW: 44.1 g/mol O O Hydrolysis 46932401 n.a.

Aerobic soil 46932402 39% (276 d) 39% (276 d)

A n.a. means “not analyzed.” n.d. means “not detected.” O

O O O

HO O OH CH 3 C 3 H

O

OH O O

HO O OH CH 3 C 3 H

O

OH OH HO

O OH O OH

### 12 

# 6. Receptors

The toxicity endpoints that would be used in risk assessment for aquatic and terrestrial organisms exposed to dikegulac-sodium are presented in Table 6 and Table 7 below. A complete list of the ecotoxicity data available for dikegulac-sodium can be found in Appendix A . The toxicity endpoints are presented in units of acid equivalents (ae) of dikegulac.

Dikegulac-sodium is practically non-toxic on an acute basis to all animals tested, including freshwater fish, freshwater aquatic invertebrates, estuarine/marine aquatic invertebrates, birds, mammals, and terrestrial invertebrates. No mortality was observed in any of the acute toxicity studies with the exception of the brown shrimp. No acute toxicity data are available for estuarine/marine fish. Toxicity to terrestrial invertebrates has been assessed only for adult honey bees via an acute contact exposure.

No chronic toxicity data for dikegulac-sodium are available for birds, fish, or aquatic invertebrates. For mammals, no multi-generation reproductive studies have been submitted to the Agency, but developmental toxicity studies are available. A developmental toxicity study on rabbits (MRID 43064618) was conducted with oral exposures of 0, 200, 700, and 2000 mg a.i./kg-bw/day. At 2000 mg a.i./kg-bw, there was a 92% decrease in maternal weight gain during dosing compared to the control and diarrhea was observed. No fetal parameters including litter size, litter weight or viability were affected.

Aquatic plant toxicity data demonstrate that dikegulac-sodium is moderately toxic to vascular aquatic plants and much less toxic to non-vascular aquatic plants. Toxicity to terrestrial plants is evident, as expected based on the mode of action. There is no difference in sensitivity of monocots versus dicots due to the mode of action. Therefore, the most sensitive species was chosen from each study to represent both monocots and dicots. Plant height was the most sensitive endpoint in both the seedling emergence and vegetative vigor studies. The vegetative vigor study represented a more sensitive exposure route, with toxicity endpoints approximately ten times lower than those from the seedling emergence study.

### 13 

## a. Effects to Aquatic Organisms

Table 6. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for Dikegulac-sodium
Taxonomic

Group Study Type Surrogate Species Toxicity Value (mg/L measured ae) Acute Toxicity Classification MRID (Study Classification)
Freshwater fish & Aquatic-phase amphibians Acute Rainbow trout 1 ( Oncorhynchus mykiss ) 96-h LC 50 >121 Practically nontoxic 46547301 (Acceptable)

Freshwater invertebrates Acute Daphnia magna 2 96-h EC 50 >10,000 Practically nontoxic 45631702 (Supplemental 3 )
Marine/estuarine invertebrates Acute Brown shrimp ( Crangon crangon) 48-h EC 50 = 8,783 Practically nontoxic 45631702 (Supplemental 3 ) Aquatic plants Vascular Duckweed ( Lemna gibba ) 7-d EC 50 = 9.6 NOAEC = 3.5 Moderately toxic 46547307 (Supplemental 4 )Nonvascular Green algae ( Pseudokirchneriella subcapita ) 96-h EC 50 = 100 NOAEC = 27 Practically nontoxic 46547308 (Acceptable)

Blue-green algae ( Anabaena flos-aquae ) 96-h EC 50 > 120 NOAEC = 15 Practically nontoxic 46547309 (Acceptable) Freshwater diatom ( Navicula pelliculosa ) 96-h EC 50 >112 NOAEC = 112 Practically nontoxic 46547310 (Acceptable) Marine diatom ( Skeletonema costatum ) 96-h EC 50 > 106 NOAEC = 26 Practically nontoxic 46547311 (Supplemental 5 ) NA: Not Applicable

1 No mortality or clinical signs of toxicity were observed. Ad ditional acceptable acute toxi city studies showed no mortality or clinical signs of toxicity in the rain bow trout (MRID 00059584) or bluegill sunfish ( Lepomis macrochirus ) (MRID 00059583) up to 10,000 mg/L ae.

2 No mortality was observed. Daphnids showed signs of stress at the highest concentration tested (10,000 ppm).

3 Static test with no measured conc entrations. Purity not reported.

4 Study classified as supplemental because it was a static test.

5 Study classified as supplemental because initial cell density was 77,000 cells/ml. OCSPP guide line 850.4500 recommends an initial density of 10,000 cells/ml.

### 14 

## b. Effects to Terrestrial Organisms

Table 7. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for Dikegulac-sodium

Taxonomic

Group Study Type Species Toxicity Value (measured ae) Acute Toxicity Classification MRID (Study Classification) Birds, Reptiles, &Terrestrialphase amphibians Acute Bobwhite quail ( Colinus virginianus ) LD 50 > 2083 mg/kgbw 1 Practically nontoxic 46547302 (Acceptable)

Sub-acute dietary Bobwhite quail LC 50 > 5460 mg/kgdiet 1 Practically nontoxic 46547303 (Acceptable) Mammals Acute oral Laboratory rat ( Rattus norvegicus ) LD 50 >4,612 mg/kgbw (M&F) 2,3 Practically nontoxic 44093901 (Acceptable)

Acute inhalation Laboratory rat LC 50 > 2.09 mg/L 4 Toxicity category IV 44093903 (Acceptable) Developmental Rabbit NOAEL = 646 LOAEL = 1845

mg/kg-bw 2,5 NA 43064618 (Acceptable)

Terrestrial invertebrates Acute contact Honey bee ( Apis mellifera ) LD 50 > 81 ug/bee 4 Practically nontoxic 44093910 (Acceptable) Terrestrial plants Seedling Emergence Radish ( Raphanus sativus ) EC 25 = 3.2 lbs/A NOAEC = 1.2 lbs/A NA 46547305 (Acceptable) Vegetative Vigor Bean ( Phaseolus vulgaris ) EC 25 = 0.61 lbs/A NOAEC = 0.20 lbs/A NA 46547306 (Acceptable)

NA: Not Applicable

1 No observed mortality, treatment-relate d clinical signs of toxicity or effect s on food consumption or body weight.

2 Nominal concentrations, no measured concentrations available.

3 No mortality was observed. Increased activity was observe d in one female on day 2 following dosing and staining around the mouth was observed in one female on day 0. No treatment-related effect on body weight was observed during the study, and no significant findi ngs were observed upon necropsy. 4 No mortality was observed.

5 Endpoints affected: maternal weight gain (92% decrease compared to controls) and diarrhea. No fetal parameters including litter size, litter weight or viability were affecte d. Concentrations tested: 0, 184, 646, 1845 mg ae/kg/day. 

## c. Ecological Incidents

The ecological incident information system (EIIS) is an OPP database that houses ecological incidents that have been reported to the Agency. When available, EIIS includes date and location of an incident, type and magnitude of effects observed in various species, use(s) of pesticides known or suspected of contributing to the incident, and results of any chemical residue analysis or other analyses conducted during incident investigation. EIIS incidents are categorized according to the certainty that the incident resulted from pesticide exposure. The Avian Monitoring System (AIMS) is a database administered by the American Bird Conservancy that contains publicly available data on reported avian incidents involving pesticides. Many of the incidents listed in this database are also in the EIIS.

As of July 7, 2014, there were no ecological incidents reported in EIIS or AIMS for dikegulacsodium. There were also no minor incidents reported in aggregate incident reports. An absence

### 15 of reports does not necessarily equate to an absence of incidents given the nature of incident reporting. 

# 7. Exposure Pathways of Concern

The environmental fate properties and use patterns of dikegulac-sodium indicate that direct spray, spray drift, and runoff represent potential transport mechanisms to aquatic and terrestrial organisms. However, use patterns of dikegulac-sodium are limited and overall usage is low and spread across a broad geographic area, according to confidential sales data provided to EPA by the registrants (Focus meeting, Jul. 24, 2014). Therefore, exposure in both aquatic and terrestrial environments is expected to be limited.

Drinking water and inhalation exposure pathways are typically considered using the SIP (Screening Imbibition Program) and STIR (Screening Tool for Inhalation Risk) screening methods. However, due to the non-definitive acute toxicity endpoints for mammals and birds and the lack of chronic toxicity data for birds, quantitative use of these tools is not appropriate for dikegulac-sodium. Based on the use patterns, usage data, and lack of observed toxic effects in the available studies (see Section 6), exposure via inhalation and drinking water are not expected to be pathways of concern for either mammals or birds. SIP and STIR are described in detail at: http://www.epa.gov/oppefed1/models/terrestrial/index.htm

. 

# 8. Analysis Plan

The dikegulac-sodium RED was completed in 2006. Since that time, there have been no substantial changes to the registration or use patterns of dikegulac-sodium. The RED concluded that there is risk of adverse effects to terrestrial plants and organisms that depend on them for survival, growth, or reproduction at or near its application site. The conclusions from the RED remain unchanged, and an updated, full ecological risk assessment is not needed for registration review. EFED recommends that additional data be requested to allow for a more comprehensive evaluation of potential effects to honey bees. EFED will evaluate those data when they are submitted and will work with PRD to address any risks of concern identified by those data.



## a. Stressors of Concern

i. Ecological Risk Assessment

Dikegulac-sodium, its free acid, MA, and M5 are the residues of concern for terrestrial and aquatic organisms. Due to structural similarity and lack of toxicity data, the residues of concern are assumed to have equivalent toxicity.

ii. Drinking Water

There are no stressors of concern for the human health risk assessment of dikegulac-sodium. The Health Effects Division (HED) did not find any toxicity effects that warranted selection of endpoints [email from Donna Davis (HED) to Greg Orrick (EFED) and 15 other recipients, dated

### 16 Jul. 31, 2014]. Therefore, a quantitative human health risk assessment and an associated drinking water exposure assessment will not be conducted for Registration Review.


## b. Measures of Exposure

If conducting an assessment, EFED would use standard available models to evaluate potential exposures to aquatic and terrestrial organisms as described at http://www.epa.gov/oppefed1/models/water/index.htm and http://www.epa.gov/pesticides/science/models_db.htm . GENEEC or the Surface Water Concentration Calculator (SWCC) are currently the model typically used to estimate aquatic exposure. T-REX, Bee-REX, and TerrPlant are currently models typically used to estimate terrestrial exposure. The limited use patterns of dikegulac-sodium and low usage in the United States would be taken into account when estimating exposure. If usage significantly increases, then this consideration would also change.

i. Available Monitoring Data

The Agency is not aware of monitoring conducted by federal and state agencies for dikegulac, as of Aug. 1, 2014. Monitoring would be considered in the assessment to the extent that data on dikegulac are available.



## c. Measures of Effect

Toxicity data presented in Section 6 of this problem formulation would be used to calculate risk quotients. Any additional information submitted by the registrant or found in the open literature prior to conduct of the risk assessment would also be considered. The open literature studies are identified using EPA’s ECOTOXicology database (ECOTOX) (USEPA, 2007b), 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 pesticides on biotic communitie s from loss of species that are sensitive to the chemicals and from changes in structure and functional characteristics of the affected communities. 

## d. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the Agency would evaluate risks to federally listed threatened and/or endangered (listed) species from registered uses of pesticides in registration review. The process for evaluating potential risks to listed species is further described at http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm

. 

## e. Endocrine Disruptor Screening Program

Dikegulac-sodium was not included in the first group of 67 chemicals issued an order to conduct Tier 1 EDSP testing and is not on the second list of chemicals for Tier 1 screening. For additional information the EDSP program, visit http://www.epa.gov/endo/

.

### 17 

# 9. Preliminary Identification of Data Gaps

a. Environmental Fate

Table 8 identifies environmental fate 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. Additional environmental fate studies and analytical methods are not needed due to the low risks from aquatic exposure.

Table 8. Submitted Environmental Fate Data for Dikegulac-sodium

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

835.2120 Hydrolysis 56146 Pre-GLP * Yes None 67144 Pre-GLP * 46932401 Acceptable 835.2240 Aqueous photolysis 49723 Pre-GLP * Yes None: dikegulac is not expected to photolyze 835.2410 Soil photolysis (None) (Not applicable) Yes None: dikegulac is not expected to photolyze 835.4100 Aerobic soil metabolism 46932402 Supplemental Yes None: a study of three additional soils is not needed due to the limited use pattern and low toxicity to aquatic organisms 835.4200 Anaerobic soil metabolism (None) (Not applicable) Yes None

835.4300 Aerobic aquatic metabolism (None) (Not applicable) Yes None: a study is not needed due to the limited use pattern and low toxicity to aquatic organisms 835.4400 Anaerobic aquatic metabolism (None) (Not applicable) Yes None: a study is not needed due to the limited use pattern and low toxicity to aquatic organisms 835.1230 835.1240 Adsorption/ desorption and leaching 49725 Pre-GLP * Yes None 46939501 Acceptable

835.6100 Terrestrial field dissipation 49727 Pre-GLP * Yes None: a study is not needed due to the limited use pattern and low toxicity to aquatic organisms 56147 Pre-GLP * 67149 Pre-GLP * 850.1730 Fish bioconcentration (None) (Not applicable) Yes None: hydrophilic compounds do not bioaccumulate 850.6100 Analytical method in soil 49724 Pre-GLP * Yes Analytical methods are not needed to address low risks. Analytical method in water (None) (Not applicable) * “Pre-GLP” means that the study predates the 40 CFR Part 160 regulations and is not likely to be acceptable according to current guideline standards.

### 18 

## b. Effects

Table 9 and Table 10 identify ecological 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 non-guideline data requested is presented below the tables.

Table 9. Submitted Aquatic Ecological Effects Data for Dikegulac-sodium

OCSPP Guideline Data Requirement Submitted Studies (MRID) Study Classifications Sufficient for risk assessment? Current Additional Data Need 1

850.1010 Freshwater invertebrate acute toxicity 45631702 Supplemental Yes None

850.1025 850.1035 850.1045 850.1055 Saltwater invertebrate acute toxicity 45631702 Supplemental Yes None

850.1075 Freshwater fish acute toxicity 46547301 Acceptable Yes None 45631702 Supplemental 00059584 Acceptable 00059583 Acceptable 00059586 Supplemental
00059585 Invalid
850.1075 Saltwater fish acute toxicity (None) (Not applicable) Yes None: EPA would use the estuarine/marine invertebrate data to represent all estuarine/marine taxa.
850.1300 Freshwater invertebrate life cycle (None) (Not applicable) Yes None: chronic toxicity would need to be at least 10,000 times greater than the acute toxicity to freshwater invertebrates to trigger a risk concern.
850.1350 Saltwater invertebrates life cycle (None) (Not applicable) Yes None: chronic toxicity would need to be at least 1,000 times greater than the acute toxicity to saltwater invertebrates to trigger a risk concern.
850.1400 Freshwater fish early-life stage (None) (Not applicable) Yes None: chronic toxicity would need to be at least 10,000 times greater than the acute toxicity to freshwater fish to trigger a risk concern.

### 19 OCSPP Guideline Data Requirement Submitted Studies (MRID) Study Classifications Sufficient for risk assessment? Current Additional Data Need 1

850.1400 Saltwater fish early-life stage (None) (Not applicable) Yes None: chronic toxicity would need to be at least 1,000 times greater than the acute toxicity to saltwater invertebrates to trigger a risk concern. 850.1500 Fish life cycle (None) (Not applicable) Yes None: chronic toxicity would need to be at least 10,000 times greater than the acute toxicity to freshwater fish to trigger a risk concern.
850.1735 Whole sediment 10-d freshwater invertebrate (None) (Not applicable) Yes None: dikegulac-sodium is not expected to partition to sediment.
850.1740 Whole sediment 10-d estuarine/marine invertebrate (None) (Not applicable) Yes None: dikegulac-sodium is not expected to partition to sediment. 850.4400 Aquatic plant Toxicity Test using Lemna spp. 46547307 Supplemental Yes None

850.4500 Algal toxicity 46547308 Acceptable Yes None 46547310 Acceptable Yes None 46547311 Supplemental Yes None 850.4550 Cyanobacteria 46547309 Acceptable Yes None

1 Statements regarding the toxicity values required for risk to rise above levels of concern are based on EECs calculated for the RED (see Section 4).



### Table 10. Submitted Terrestrial Ecological Effects Data for Dikegulac-sodium

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

850.2100 Avian oral toxicity 46547302 Acceptable Yes None: no data are available for a passerine species, however because no mortality or clinical signs of toxicity wereobserved in any acute or subacute avian study and because usage of dikegulac-sodium is low, a study is not needed for risk assessment. 00073618 Acceptable

850.2200 Avian dietary toxicity 46547303 Acceptable Yes None 00059581 Supplemental 00059582 Supplemental 850.2300 Avian reproduction (None) (Not applicable) Yes None: no sublethal toxicity observed in acute studies, exposure potential is low due to the limited use pattern

### 20 OCSPP Guideline Data Requirement Submitted Studies (MRID) Study Classifications Sufficient for risk assessment? Current Additional Data Need

Nonguideline Avian inhalation (None) (Not applicable) Yes None

850.3020 Honey bee acute contact toxicity 44093910 Acceptable Yes None

Nonguideline Honey bee acute oral toxicity (None) (Not applicable) No An acute oral toxicity study with the adult honey bee is needed.

Nonguideline Honey bee larval chronic toxicity (None) (Not applicable) No A repeat dose larval toxicity study with the honey bee is needed.

Nonguideline Honey bee adult chronic 10d toxicity (None) (Not applicable) No A chronic 10 day oral toxicity study with the adult honey bee is needed. 850.3030 Honey bee residue on foliage (None) (Not applicable) Yes None

850.3040 Field testing for pollinators (None) (Not applicable) Yes None

850.4100 Seedling Emergence 46547305 Acceptable Yes None 850.4150 Vegetative Vigor 46547306 Acceptable Yes None



### Study Title: Honey Bee Acute Oral Toxicity Test Guideline Number: Non-guideline Test Substance: Dikegulac-sodium—TGAI Rationale for Requiring the Data This study is needed to evaluate potential effects to adult honey bees from acute oral exposure to technical grade active ingredient (TGAI). Dikegulac-sodium uses include applications to flowering ornamental plants via ground spray. Target plants may be visited by pollinators, and spray drift may land on blooming non-target plants and result in residues in pollen and nectar (which could then be transported to the hive). Dikegulac-sodium is systemic and may move into pollen and/or nectar in a plant. Residues can in turn be brought back to bee colonies where in-hive bees including young adult and developing brood ( i.e. , eggs, larvae and pupae) may be exposed. Therefore, exposure at all bee life stages would be expected.

The Agency guidance for assessing the risk of pesticides to bees (USEPA et al. , 2014) requires this study for all use sites where potential exposure to pollinators may occur. Although EPA has not developed a guideline for this study, the Organization for Economic Cooperation and Development (OECD) has developed a formal test guideline for an acute oral toxicity study with adult honey bees (OECD TG213) that may be used to assess the acute oral toxicity for adult bees.

### 21 Practical Utility of the DataHow will the data be used and how could the data impact the Agency’s future decisionmaking?

The acute oral toxicity data are used in conjunction with acute contact data obtained through OCSPP 850.3020 to estimate the acute toxicity of technical grade active ingredient (TGAI) to individual young adult honey bees. The studies also provide slopes for the dose-response curves that can in turn be used for estimating the likelihood of individual effects, and sublethal effects observed in the study will be used to further characterize effects observed following a single exposure to TGAI. Data obtained from this study will be used in estimating acute risk to individual adult bees. Risk estimates based on these data will be considered along with other lines of evidence to determine whether higher-tier studies are needed at the whole colony level.

These data are needed for risk assessments written in support of Registration Review risk assessment as well as for future endangered species assessments. The data would allow the Agency to better characterize the potential for risk to insects (including beneficial pollinators) from the use of dikegulac-sodium. These data may help the Agency determine whether any mitigations are needed. If the Registration Review and any future endangered species risk assessments are performed without these data, the Agency would have to assume that dikegulac-sodium "may affect" insects, including bees and beneficial pollinators, directly (and endangered species from other taxa indirectly), and uses of dikegulac-sodium might need to be restricted in areas where pollinators could be exposed.

Study Title: Larval Honey Bee Acute and Chronic Oral Toxicity Guideline Number: Non-guideline Test Substance: Dikegulac-sodium—TGAI Rationale for Requiring the Data These studies are needed to evaluate the potential effects of technical grade active ingredient (TGAI) on honey bee larvae from repeat exposure. Dikegulac-sodium uses include applications to flowering ornamental plants via ground spray. Target plants may be visited by pollinators, and spray drift may land on blooming non-target plants and result in residues in pollen and nectar (which could then be transported to the hive). Dikegulac-sodium is systemic and may move into pollen and/or nectar in a plant. Residues can in turn be brought back to bee colonies where in-hive bees including young adult and developing brood ( i.e. , eggs, larvae and pupae) may be exposed. Therefore, exposure at all bee life stages may occur.

The Agency guidance for assessing the risk of pesticides to bees (USEPA et al. , 2014) requires this study for all use sites where potential exposure to pollinators may occur. Although EPA has not developed a guideline for this study, the 21-day larval toxicity study currently under development by OECD provides a draft guidance protocol for potentially assessing both the acute and chronic toxicity to developing brood (larvae and pupae) from repeat exposure to pesticides. Until a guideline is finalized, protocols should be submitted to the Agency for review before study initiation. Registrants may choose to submit a separate acute (single dose) larval toxicity study following OECD TG 237 as well as the 21-day repeat dose chronic toxicity study.

### 22 Practical Utility of the DataHow will the data be used and how could the data impact the Agency’s future decisionmaking?

The 21-day toxicity study provides data on the effects of technical grade active ingredient (TGAI) on developing bees from acute (short-term) and chronic (longer term) exposure and will be used for estimating risk to individual (solitary) bees as well as bee colonies (social bees). Risk estimates based on these data will be considered along with other lines of evidence to determine whether higher-tier studies are needed at the whole colony level.

These data are needed for risk assessments written in support of Registration Review as well as for future endangered species assessments. These data would allow the Agency to better characterize the potential for risk to insects (i ncluding beneficial pollinators) from the use of dikegulac-sodium. These data may help the Agency determine whether any mitigations are needed. If the Registration Review and any fu ture endangered species risk assessments are performed without these data, the Agency would have to assume that dikegulac-sodium "may affect" insects, including bees and beneficial pollinators, directly (and endangered species from other taxa indirectly), and uses of dikegulac-sodium might need to be restricted in areas where pollinators could be exposed.

Study Title: Adult Honey Bee Chronic Oral Toxicity Guideline Number: Non-guideline Test Substance: Dikegulac-sodium—TGAI Rationale for Requiring the Data This study is needed to evaluate the potential effects of technical grade active ingredient (TGAI) on young adult honey bees from repeat exposure. Dikegulac-sodium uses include applications to flowering ornamental plants via ground spray. Target plants may be visited by pollinators, and spray drift may land on blooming non-target plants and result in residues in pollen and nectar (which could then be transported to the hive). Dikegulac-sodium is systemic and may move into pollen and/or nectar in a plant. Residues can in turn be brought back to bee colonies where in-hive bees including young adult and developing brood ( i.e. , eggs, larvae and pupae) may be exposed. Therefore, exposure at all bee life stages may occur.

The Agency guidance for assessing the risk of pesticides to bees (USEPA et al. , 2014) requires this study for all use sites where potential exposure to pollinators may occur. Although EPA has not developed a guideline for this study and OECD has yet to finalize test guidance for chronic studies, efforts are currently underway to develop standardized guidelines for assessing effects from chronic (10-day) exposures to adult bees in the laboratory. Until a guideline is finalized, a protocol should be submitted to the Agency for review before study initiation. Practical Utility of the DataHow will the data be used and how could the data impact the Agency’s future decisionmaking?

The 10-day toxicity study with young adult bees provides data that will be used in estimating chronic risk to individual adult bees. Risk estimates based on these data will be considered along

### 23 with other lines of evidence to determine whether higher-tier studies are needed at the whole colony level.

These data are needed for risk assessments written in support of Registration Review as well as for future endangered species assessments. These data would allow the Agency to better characterize the potential for risk to insects (i ncluding beneficial pollinators) from the use of dikegulac-sodium. These data may help the Agency determine whether any mitigation is needed. If the Registration Review and any fu ture endangered species risk assessments are performed without these data, the Agency would have to assume that dikegulac-sodium "may affect" insects, including bees and beneficial pollinators, directly (and endangered species from other taxa indirectly), and uses of dikegulac-sodium might need to be restricted in areas where pollinators could be exposed.



# 10. References

Budavari, S., M. O’Neil, A. Smith, P. Heckelman, and J. Obenchain. 1996. The Merck Index, 12th edition. Merck & Co., Inc., Whitehouse Station, NJ.

Meylan, W.M. and P.H. Howard. 1995. Atom/fragment contribution method for estimating octanol–water partition coefficients. J. Pharm. Sci.
, 84 : 83–92. doi: 10.1002/jps.2600840120

Neely, W.B. and G.E. Blau. 1985. Environmental Exposure from Chemicals, Vols. I and II. CRC Press Inc., Boca Raton, FL.

United States Environmental Protection Agency (USEPA). 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs . U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate and Effects Division. Available at http://www.epa.gov/espp/consultation/ecorisk-overview.pdf

USEPA. 2006a. Barnes, Y., J. Facey, R. Griffen, and S. Recore. Dikegulac Sodium: Human Health Considerations for the Reregistration Eligibility Decision. DP barcode 317256. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances, Health Effects Division. Memorandum to the Special Review and Reregistration Division. Oct. 31, 2006.

USEPA. 2006b. Eckel, W., M. Davey, and J. Martinez. EFED Risk Assessment for the Reregistration of Dikegulac-Sodium. DP barcode 317851. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances, Environmental Fate and Effects Division. Memorandum to the Special Review and Reregistration Division. Oct. 6, 2006.

USEPA. 2007a. Eckel, W. Drinking Water Assessment for Dikegulac-sodium Reregistration Eligibility Decision (RED). DP barcode 322063. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances, Environmental Fate and Effects Division. Memorandum to the Special Review and Reregistration Division. Feb. 9, 2007.

### 24 USEPA. 2007b. ECOTOXicology Database. Office of Research and Development National Health and Environmental Effects Research Laboratory’s (NHEERL’s) Mid-Continent Ecology Division (MED). http://cfpub.epa.gov/ecotox/

USEPA, PMRA, and CDPR, 2014. Guidance for Assessing Pesticide Risks to Bees. Office of Pesticide Programs, USEPA, Washington D.C. Health Canada Pest Management Regulatory Agency, Ottawa, ON, Canada. California Department of Pesticide Regulation, Sacramento, CA. June 23, 2014.



## a. Submitted Environmental Fate Studies

MRID Citation Reference
46932401 Wisocky, M. (2006) Hydrolysis of [14-Carbon] Dikegulac in Buffered Water at pH 5, 6, 7 and 9. Project Number: XBL/03002, RPT01 447. Unpublished study prepared by Xenobiotic, Inc. 261 p.
46932402 Wisocky, M. (2 006) Aerobic Soil Metabolism of [14- Carbon] Dikegulac. Project Number: XBL/03001, RPT01572. Unpublished study prepared by Xenobiotic, Inc. 309 p.
46939501 Wisocky, M. (2006) Adsorption and Desorption of (Carbon 14) Dikegulac in Four US Soils. Project Number: XBL/03003, RPT01612. Unpublished study prepared by Xenobiotic, Inc. 239 p.


## b. Submitted Ecological Toxicity Studies

MRID Citation Reference
00059581 Ross, D.B.; Bur roughs, S.J.E.; Roberts, N.L. (1974) The Acute Toxicity (LCI50^) of RO/7-6145 to the Japanese Quail: HLR/13/74911. (Unpublished study received Aug 1, 19 75 under 35977-EX-1; pre- pared by Huntingdon Research Centre, En gland, submitted by Hoffman-Laroche, Inc., Nutley, N.J.; CDL:223552-BW)
00059582 Ross, D.B.; Burroughs, S.J.; Roberts, N.L. (1 975) The Sub-acute Toxicity (LCI50^) of RO 7-6145 to the Chicken: HLR26/75343. (Unpublished study received Aug 1, 1975 under 35977-EX-1; prepared by Huntingdon Research Centre, England, submitted by Hoffman-Laroche, Inc., Nutley, N.J.; CDL:223552-BX)
00059583 Moore, G.E. (19 74) The Acute Toxicity of RO07-6145 to the Bluegill Sunfish,~Lepomis macrochirus~: Report No. 746-122. (Unpub- lished study received Aug 1, 1975 under 35977-EX-1; prepared by Huntingdon Research Centre, England, subm itted by Hoffman- Laroche, Inc., Nutley, N.J.; CDL:223552-BY)
00059584 Fraser, W.D.; Jenkins, G. (1974) The Acute To xicity of RO-07-6145 (Technical) to Rainbow Trout (~Salmo gairdneri~): HLR/8/7475 8. (Unpublished study received Aug 1, 1975 under 35977-EX-1; pre- pared by Huntingdon Research Centre, En gland, submitted by Hoffman-Laroche, Inc., Nutley, N.J.; CDL:223552-BZ)
00059585 Fraser, W.D.; Jenkins, G. (1974) The Acute To xicity of RO-07-6145 (Technical) to Harlequin Fish (~Rasbora heteromorpha~): HLR/ 12/74773. (Unpublished study received Aug 1, 1975 under 35977- EX-1; prepared by Huntingdon Research Centre, England, submitted by Hoffman-Laroche, Inc., Nutley, N.J.; CDL:223552-CA)
00059586 Fraser, W.D.; Jenkins, G. (1974) The Acute Toxicity of RO-07-6145 (Technical) to Goldfish (~Carassius auratus~): HLR/11/74759. (Unpublished study received Aug 1, 1975 under 35977-EX-1; pre- pared by Huntingdon Research Centre, En gland, submitted by Hoffman-Laroche, Inc., Nutley, N.J.; CDL:223552-CB)

### 25 MRID Citation Reference
00065378 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1976) The Effect of Contact with ACR 1139A and ACR 4031 on the Hatchability of Fertile Quail Eggs: HLR/38/76480. (Unpublished study received on unknown date under 35977-EX-1; prepared by Hun tingdon Research Centre, England, submitted by Hoffman-Laroche, Inc., Nutley, N.J.; CDL:229051-E)
00073618 Ross, D.B.; Bur roughs, S.J.E.; Roberts, N.L. (1974) The Acute Toxicity of RO/7-6145 to the Mallard Duck: HLR14/74653. (Unpublished study received Aug 1, 1975 under 35977-EX-1; prepared by Huntingdon Research Centre, England, su bmitted by Hoffman- Laroche, Inc., Nutley, N.J.; CDL:223552-BV)
00073618 Ross, D.B.; Bur roughs, S.J.E.; Roberts, N.L. (1974) The Acute Toxicity of RO/7-6145 to the Mallard Duck: HLR14/74653. (Unpublished study received Aug 1, 1975 under 35977-EX-1; prepared by Huntingdon Research Centre, England, subm itted by Hoffman- Laroche, Inc., Nutley, N.J.; CDL:223552-BV)
43064617 Backes, G. (1977) Embryotoxicity Studies in the Rat Following Oral Adminis tration of Ro 07- 6145/001. Unpublished study prepare d by Roche Corporate Lab. 177 p.
43064618 Backes, G. (1977) Embryotoxicity Studies in the Rabb it Following Oral Administration of Ro 07- 6145/001. Unpublished study prepared by Roche Corporate Lab. 96 p.
44093901 Douds, D. (1995) An Acute Oral Toxicity St udy (Limit Test) in Rats with Dikegulac Sodium: Final Report: Lab Project Number: 3229.102: EPA/AO-1-2/9 4. Unpublished study prepared by Springborn Labs, Inc. 37 p.
44093903 Douds, D. (1995) An Acute Whole-Body I nhalation Toxicity Study (L imit Test) in Rats with Dikegulac Sodium: Final Report: Lab Project Number: 3229.104: EPA/AI-1-2/94. Unpublished study prepared by Springborn Labs, Inc. 59 p.
44093910 Palmer, S.; Beavers, J. (1996) Dikegulac Sodi um: An Acute Contact Toxic ity Study with the Honey Bee: Final Report: Lab Project Number: 281-113 : 281/030895/BLD.NC/CHP86. Unpublished study prepared by Wildlife International Ltd. 29 p.
45631702a Fraser, W.D. and Jenkins, G. (1975) The Ac ute Toxicity ofRO-07-6145 to the black carp (Cyprinus carpio). Unpublished study performed by Huntingt on Research Center, Ca mbridgeshire, England. Laboratory Study No. Not report ed. Sponsor not reported.
45631702b Fraser, W.D. and Pell, L.B. (1977) The Acute Toxicity of RO-76145.001 to the Brown Shrimp (Crangon crangon) . Unpublished study performed by Huntington Research Center, Cambridgeshire, England. Laboratory Study No. Not reported. St udy sponsored by Hoffman La Rouche Ltd.
45631702c Leblanc, G.A. 1977 . Acute Toxicity of RO 7- 6145/001to the water flea ( Daphnia magna)

. Unpublished study perfor med by EG & G, Bionomics, Aquatic Toxicology Laboratory, Wareham, Massachusetts. Laboratory Study No. Not reported . Study sponsored by Hoffman-LaRoche, Inc., Nutley, New Jersey.
46547301 Palmer, S.; Kendall, T.; Kr ueger, H. (2004) Dikegulac: A 96-H our Static-Renewal Acute Toxicity Test with the Rainbow Trout (Oncorhynchus mykiss ): Final Report. Project Number: 281A/127A. Unpublished study prepared by W ildlife International, Ltd. 56 p.
46547302 Gallagher, S.; Beavers, J. (2004) Dikegulac: An Acute Oral To xicity Study with the Northern Bobwhite. Project Number: 281/114. Unpublished st udy prepared by Wildlife International, Ltd. 38
p. 46547303 Gallagher, S.; Martin, K.; Be avers, J. (2004) Dikegulac: A Diet ary LC50 Study with the Northern Bobwhite. Project Number: 281/115. Unpublished st udy prepared by Wildlife International, Ltd. 47
p.

### 26 MRID Citation Reference
46547305 Brignole, A. ; Porch, J.; Krueger, H.; et. al. (2004) Dikegulac: A Toxicity Test to Determine the Effects of the Test Substance on Seedling Emergence of Ten Species of Plants: Final Report. Project Number: 281/116. Unpublished study prepared by Wildlife International, Ltd. 99 p.
46547306 Brignole, A. ; Porch, J.; Krueger, H.; et. al. (2004) Dikegulac: A Toxicity Test to Determine the Effects of the Test Substance on Vegetative Vigor of Ten Species of Plants: Final Report. Project Number: 281/117. Unpublished study prepared by Wildlife International, Ltd. 167 p.
46547307 Desjardins, D.; Kendall, T.; Krueger, H. (2004 ) Dikegulac: A 7-Day Toxicity Test with Duckweed (lemna gibba G3): Final Report. Project Number: 281A/132. Unpublished study prepared by Wildlife International, Ltd. 59 p.
46547308 Desjardins, D.; Kendall, T.; Krueger, H. (2 005) Dikegulac: A 96-Hour Toxicity Test with the Freshwater Alga (Selenastrum capricornutum): Final Report. Project Number: 281A/128. Unpublished study prepared by W ildlife International, Ltd. 67 p.
46547309 Desjardins, D.; Kendall, T.; Krueger, H. (2 004) Dikegulac: A 96-Hour Toxicity Test with the Freshwater Alga (Anabaena flos-aquae): Final Report. Project Number: 281A/129. Unpublished study prepared by Wildlife International, Ltd. 56 p.
46547310 Desjardins, D.; Kendall, T.; Krueger, H. (2 005) Dikegulac: A 96-Hour Toxicity Test with the Freshwater Diatom (navicula pellicu losa): Final Report. Project Number: 281A/131. Unpublished study prepared by Wildlife International, Ltd. 56 p.
46547311 Desjardins, D.; Kendall, T.; Krueger, H. (2004) Dikegulac: A 96-Hour Toxicity Test with the Marine Diatom (Skeletonema costatum): Final Report . Project Number: 281A/130. Unpublished study prepared by Wildlife In ternational, Ltd. 54 p.

### 27 

# Appendix A. Dikegulac-sodium Ecotoxicity Data

Toxicity to Terrestrial Animals

Avian Toxicity

Table A-1. Acute Oral Toxicity of Dikegulac-sodium to Birds
Species % ai LD 50 (mg ae/kg-bw) Toxicity Category MRID Author, Year Study Classification Northern bobwhite quail (Colinus virginianus) 96.9 > 2083 1 Practically non-toxic 46547302 Gallagher, et. al., 2004 Acceptable

Mallard duck (Anas platyrhynchos) 20 >3891 1 Practically non-toxic 00073618 Ross, et. al., 1974 Acceptable

1 No mortality of toxicity occurred at the highest concentration tested.

Table A-2. Subacute Dietary Toxicity of Dikegulac-sodium to Birds
Species % ai LC 50 (ppm ae) Toxicity Category MRID Author, Year Study Classification Northern bobwhite quail 98.9 >5460 1 Practically non-toxic 46547303 Gallagher, et. al., 2004 Acceptable

Mallard duck 20 >50,000 Practically non-toxic 00073618 Ross, et. al., 1974 Acceptable

Japanese quail (Coturnix japonica) 20 >50,000 1 Practically non-toxic 00059581 Ross, et. al., 1974 Supplemental 2

Chicken ( Gallus gallus domesticus ) 20 >50,000 1 Practically non-toxic 00059582 Ross, et. al., 1974 Supplemental 2

1 No mortality at highest concentration tested.

2 Supplemental due to non-standard species and lack of raw data.

Avian Chronic Toxicity 

### No reproduction studies are available for avian species.

Mammalian Toxicity

Table A-3. Mammalian Toxicity of Dikegulac-sodium
Species % ai Test Type Toxicity Value (mg ai/kg-bw) Most Sensitive Endpoints MRID Laboratory rat ( Rattus norvegicus ) 100 Acute Oral LD 50 >5000 1 No mortality or other signs of toxicity were noted at the highest concentration tested. 44093901

Rabbit 2 ( Oryctolagus cuniculus ) 93 - 97 Developmental Toxicity NOAEL = 700 LOAEL = 2000 Maternal lack of weight gain (92% decrease compared to controls), diarrhea 43064618

Laboratory rat (abino) 93 - 97 Developmental Toxicity NOAEL = 700 LOAEL = 2000 Light sedation 43064617

1 Male and female. Equivalent to >4612 mg ae/kg-bw.

2 No fetal parameters including litter size, litter weight or viability were affected. Nominal concentrations tested: 0, 200, 70 0, 2000 mg a.i./kg/day (0, 184, 646, 1845 mg ae/kg/day). No measured concentrations provided. 

### No mammalian reproductive study was available so results from development toxicity studies are reported. The rat developmental study was not considered to be significant for ecological based risk.

### 28 Terrestrial Invertebrate Toxicity

Table A-4. Nontarget Insect Acute Co ntact Toxicity of Dikegulac-sodium
Species % ai LD 50 ( μ g/bee) Toxicity Category MRID No. Author, Year Study Classification Honey bee (Apis mellifera) 15.0 LD 50 >81 Practically non-toxic 44093910 Palmer et. al., 1996 Acceptable



### Toxicity to Aquatic Animals

Aquatic Vertebrate Toxicity

Table A-5. Freshwater Fish Acute Toxicity of Dikegulac-sodium
Species % ai 96-hour LC 50 (ppm ae) Toxicity Category MRID No. Author, Year Study Classification Rainbow trout, ( Oncorhychus mykiss ) 86.4 >121 1 Practically non-toxic 46547301 Kendall et. al., 2004 Acceptable

Rainbow trout, 90.0 >10,000 1 Practically non-toxic 00059584 Fraser, et. al., 1974 Acceptable

Bluegill sunfish, ( Lepomis macrochirus ) 90.0 >10,000 1 Practically non-toxic 00059583 Moore, 1974 Acceptable

Goldfish ( Carassius auratus ) 90.0 > 5,000 1 Practically non-toxic 00059586 Fraser, et. al., 1974 Supplemental 2

1 No mortality or other signs of toxicity at the highest treatment level were noted.

2 Gold fish is not a preferred species

Freshwater Fish Chronic Toxicity 

### No fish early-life stage or fish life cycle studies are available for dikegulac-sodium.

Aquatic Invertebrate Toxicity

Table A-6. Acute Toxicity of Dikegulac-sodium to Freshwater Invertebrates

Species % ai 48-hour LC 50 (ppm ae) Toxicity Category MRID No. Author, Year Study Classification Waterflea ( Daphnia magna ) Tech. > 10,000 1 Practically non-toxic 45631702 Mileson, 2002 Supplemental

1 There was no mortality at the highest treatment concentration (10,000 ppm) but signs of stress were exhibited at that concentr ation in which the organisms remained on the surface during the test. The NOEC is 3200 ppm and LOEL is 10,000 ppm. The study is supplemental due t o lack of raw data. This study was conducted by LeBlanc, 1977 but is found within MRID 45631702.
Table A-7. Acute Toxicity of Dikegulac-sodium to Estuarine/Marine Invertebrates
Species % ai 48-hour LC 50 (ppm ae) Toxicity Category MRID No. Author, Year Study Classification Brown shrimp 1 ( Crangon crangon) (static) Tech. 8,783 Practically non-toxic 45631702 Mileson, 2002 Supplemental

1 100% mortality was observed at the 20,000 ppm concentration dose. Th e study is supplemental due to lack of raw data. This stud y was conducted by Fraser, 1977 but is found within MRID 45631702.

Aquatic Invertebrate Chronic Toxicity 

### No chronic aquatic invertebrate studies are available for dikegulac-sodium.

### 29 Toxicity to Plants

Terrestrial Plant Toxicity

Table A-8. Summary of Effects of Dikegulac-sodium (Atrimmec, 18.5% a.i.) on Vegetative Vigor (Tier II)

Species NOAEC, and EC 25 (lbs ae/A)

Plant Height Dry Weight Survival

NOAEC EC 25 NOAEC EC 25 NOAEC EC 25

Corn (Zea mays) 0.5 2.8 0.5 2.0 1.5 >1.5

Onion (Allium cepa) 1.6 >4.9 1.6 >4.9 1.6 >4.9

Perennial Ryegrass (Lolium perenne) 1.3 >4.5 0.5 1.7 1.3 >4.5

Wheat (Triticum aestivum) 1.3 3.3 1.3 1.9 1.3 >1.3

Bean (Phaseolus vulgaris) 1 0.2 0.61 0.5 1.3 4.3 >4.3

Cabbage (Brassica oleracea) 1.6 3.7 1.6 2.1 4.9 >4.9

Lettuce (Lactuca sativa) 1.5 2.2 0.5 1.0 1.5 >1.5

Radish (Raphanus sativus) 1.6 >4.9 1.6 2.1 4.9 >4.9

Soybean (Glycine max) 1.5 3.0 0.5 2.3 4.3 >4.3

Tomato (Solanum lycopersicum) 0.5 1.3 0.2 0.72 4.9 >4.9 MRID 46547306: Brignole, Andrew, J. R. Porch, H. O. Krueger and K. H. Martin. 2004.

1 Bean is the most sensitive species tested. Bold text denotes the most sensitive value.
Table A-9. Summary of Effects of Dikegulac-sodium (Atrimmec, 18.5% a.i.) on Seedling Emergence

Species NOAEC, and EC 25 (lbs ae/A)

Seedling Height Seedling Weight Emergence

NOAEC EC 25 NOAEC EC 25 NOAEC EC 25

Tier II

Corn 4.6 >4.6 4. 6 >4.6 4.6 >4.6

Onion 1 4.6 >4.6 4.6 ND <0.29 1 0.50
Cabbage 2.3 4.7 2.3 4.7 4.5 >4.5

Radish 2 1.2 3.2 2.3 3.4 1.2 20

Tomato 2.3 4.8 2.3 4.1 4.5 >4.5

Tier I

Perennial Ryegrass 4.6 >4.6 4.6 >4.6 4.6 >4.6

Wheat 4.6 >4.6 4. 6 >4.6 4.6 >4.6

Bean 4.6 >4.6 <4.6 >4.6 4.6 >4.6

Lettuce <4.6 >4.6 <4.6 >4.6 <4.6 >4.6

Soybean 4.6 >4.6 4.6 >4.6 4.6 >4.6 MRID 46547305: Brignole, Andrew, J. R. Porch, H. O. Krueger and K. H. Martin. 2004. ND: Not Determined

1 Onion EC 05 or NOAEC cannot be determined due to the non-linear distribution of the data; the onion values may not be reliable.

2 Radish is the most sensitive species tested. Bold text denotes the most sensitive value.

### 30 Aquatic Plant Toxicity

Table A-10. Toxicity of Dikegulac- sodium to Aquatic Plants (Tier II)
Species % ai EC 50 (ppm ae) EC 05 or NOAEC (ppm ae) MRID No. Author (Year) Study Classification Duckweed ( Lemna gibba ) 96.9 9.6 1 3.5 46547307 Desjardins et. al., 2004 Supplemental 3

Green algae ( Selenastrum capricornutum ) 96.9 100 2 27 46547308 Desjardins et. al., 2004 Acceptable

Blue-green cyanobacteria ( Anabaena flos-aquae ) 96.9 >120 2 15 46547309 Desjardins et. al., 2004 Acceptable

Freshwater diatom ( Navicula pelliculosa ) 96.9 >112 2 112 46547310 Desjardins et. al., 2004 Acceptable

Marine diatom ( Skeletonema costatum ) 96.9 >106 2 26 46547311 Desjardins et. al., 2004 Supplemental 4

1 Based on frond numbers.

2 Based on cell density.

3 The duckweed test is a static test instead of renewal test.

4 Cell density (77,000 cells/ml) is highe r than recommended (10,000 cells/ml).