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

OFFICE OF CHEMICAL SAFETY AND

POLLUTION PREVENTION

December 15

, 2015

PC Code: 035505
DP Barcode : 423230

MEMORANDUM

SUBJECT : Diuron: Registration Review Problem Formulation for the Environmental Fate, Ecological Risk, Endangered Species, and Drinking Water Assessments

FROM : Freeborn Jewett, M.S., Biologist
Michael Lowit , Ph.D., Ecologist

Environmen tal Risk Branch I Environmental Fate and Effects Division (7507P)

James Breithaupt, Agronomist (LP for JB) David Bays, Biologist Siroos Mostaghimi, Senior Scientist Risk Assessment and Science Support Branch Antimicrobials Division (7510P)

T HRU : Sujatha Sankula, Ph.D., Branch Chief
Environmental Risk Branch 1 Environmental Fate and Effects Division ( 7507P)

Laura Parsons, Associate Branch Chief
Risk Assessment and Science Support Branch Antimicrobials Division (7510P )

TO : Katherine St. Clair

, Chemical Review Manager Tom Myers , Team Leader
Kevin Costello , Branch Chief Risk Management and Implementation Branch 2
Pesticide Re

- Evaluation Division (7508P)

SanYvette Williams, DVM, Chemical Review Manager Rose Kyprianou, Team Leader Lance Wormell, Branch Chief Regulatory Management Branch 2 Antimicrobials Division (7510P)2 

## TABLE OF CONTENTS

1) Executive Summary

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

2) Introduction

................................ ................................ ................................ ................................ .......... 4

4) Conclusions from Previous Risk Assessments

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

5) Environmental Fate and Transport

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

6) Receptors

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

7) Exposure Pathways of Concern

................................ ................................ ................................ ......... 17

8) Analysis Plan

................................ ................................ ................................ ................................ ....... 17

9) Endangere d Species Assessment

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

10) Endocrine Disruptor Screening Program

................................ ................................ ........................... 20

11) Preliminary Identification of Data Gaps

................................ ................................ ............................ 20

12) References

................................ ................................ ................................ ................................ .......... 26

Appendix 1: Maximum Application Rates of Diuron (Conventional Uses)

................................ .............. 28

Appendix 2: Diuron Degradates Identified in Environmental Fate Studies

................................ ............. 31

Appendix: 3: Complete List of Toxicity Endpoints for Diuron

................................ ................................ ... 36

Appendix 4: Ecological Incidents Associated with Diuron (EIIS database)

................................ ............... 42

Appendix 5: SIP (v1.0) Input and Output Data

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

Appendix 6: STIR (v.1) Inputs and Outputs

................................ ................................ ............................... 4 53 1) Executive Summary

The Environmental Fate and Effects Division (EFED) and Antimicrobials Division (AD) ha ve completed the problem formulation for the environmental fate, ecological risk, endangered species, and drinking water exposure assessments to be conducted as part of t he r egistration r eview of the herbicide d iuron (N ’

- (3,4

- dichlorophenyl)

- N,N

- dimethylurea)

, a systemic substituted phenylurea herbicide and an antimicrobial mildewcide and algaecide

. Functioning as the first stage of the risk assessment process for

r egistration r eview, this problem formulation provides an overview of what is currently known about the environmental fate and ecological effects associated with diuron and its degradates. It also describes the preliminary ecological risk hypothesis and ana lysis plan for evaluating and charact erizing drinking water exposure and risk to non

- target species and the environment in support of the r egistration r eview
of diuron . This document also recommends studies that should be included in a data call

- in (DCI) t o address uncertainties surrounding the environmental fate and potential ecological effects of diuron for
both conventional and antimicrobial uses

.

The following studies are recommend ed to reduce uncertainty in the risk assessment for conventional

uses o nly :

• 850.2100 : Avian a cute o ral t oxicity with a passerine species (diuron)

• 850.2300: Avian r eproduction with an upland game species (diuron)

• 850.4100 : Seedling e mergence and s eedling g rowth toxicity (TEP) 1

• 850.4150 : Vegetative v igor toxicity (TEP) 2

• Non

- Guideline (OECD 213): Tier I Honeybee a cute a dult o ral t oxicity (diuron)

• Non

- Guideline : Tier I Honeybee adult chronic oral toxicity (diuron)

• Non

- Guideline : Tier I Honeybee l arval acute and chronic oral toxicity (diuron)

• Non

- Guideline : Tier II Residue in pollen and nectar (based on risks identified in Tier I studies) (TEP)

• Non

- Guideline : Tier II Semi

- field testing for honeybees toxicity (based on risks identified in Tier I studies) (TEP)

• 850.3040: Tier III field testing for pollinator toxicity (based on risks identified in Tier II studies) (TEP)

• 850. 6 100: Independent laboratory validation (ILV) report for analytical method in soil (diuron and DCPMU)

• 850.6100: Environmental chemistry method (ECM) and independent laboratory validation (ILV)
reports for analytical method in water (ECM and ILV for PDMU and mCPMU; ILV only for diuron,

DCPMU

, and mCPDMU

The following studies are recommend ed to reduce uncertainty in the risk assessment for conventional
and antimicrobial uses:

• 850.1400 : Estuarine/marin e f ish e arly

- l ife s tage toxicity (diuron)

• 850.4500: Aquatic plant toxicity study with freshwater diatom, Navicula pelliculosa (diuron)

• 850.4500: Aquatic plant toxicity study with the m arine diatom

, Skeletonema costatum (diuron)

• 850.4550: Aquatic plant toxi city study with blue

- green alga, Anabaena flos

- aquae (diuron)

• 850.4500 /850.4550: Algal /Cyanobacteria Toxicity (DCPMU)

1 Valid endpoints have been submitted for Oilseed Rape, Sugar Beet, Tomato, Onion, and Wheat. Study must include corn and soybean

. Stu dy must include the correct number and type of test species as specified by guideline 850.4100

. 2 Valid endpoints have been submitted for Pea, Oilseed Rape, Onion, Sorghum and Wheat. Study must include the correct number and type of test species as specifi ed by guideline 850.4150

.4 **o** Testing should be with the non

- vascular plant species most sensitive to diuron.

• 850.4500 : Algal /Cyanobacteria Toxicity (mCPDMU)

**o** Testing should be with the non

- vascular plant species most sensitive to diuron.

The following studies are recommend ed to reduce uncertainty in the risk assessment for antimicrobial

uses only :

• Non

- Guideline: Special leaching study for paint

EFED recommends the following information to reduce uncertainty in the risk assessment :

EFED requests that the registrant provide the following information for conventional uses: maximum annual application rates per acre (lb ai/A/year) for all uses , maxim um number of applications per crop/ season (if applicable) and per year (all uses) , and minimum application intervals (all uses)

.

2) Introduction

The purpose of this problem formulation is to provide an under standing of what is known about the environmental fate and ecological effects of diuron considering its currently registered uses. This document provide s a plan for analyzing data relevant to diuron and for conducting ecological risk, endangered species, and drinking water exposure asses sments for its registered uses. T his 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
d iuron

.
Diuron is a pre

- and post

- emergence systemic herbicide belonging to the substituted urea class of herbicides used to control both grasses and broadleaf species. In the U.S., diuron is used on a variety of crops and non

- agricultural uses such as rec reational areas, impervious surfaces, and paved areas. It also may be used in irrigation and drainage systems when water is not present. As a conventional pesticide, diuron is applied alone or as part of formulated product using ground and aerial equipment . It is also registered to be used as an antimicrobial pesticide ( material preservative ) in paints, coatings

, and
adhesives that may be used on building exterior s.

EFED evaluated the most recent ecological risk assessments for diuron in association with the updated toxicity, exposure, and usage information to determine if sufficient data are available and if further updates are needed to support registration review. The most r ecent risk assessment s for diuron include
the Environmental Risk Assessment for the Reregistration of D iuron (USE P A

, 2003 a ) and two endangered species assessments : Determination of Risks of Diuron Use to Federally Threatened
California Red

- legged Frog (USEPA, 2009) and the Endangered and Threatened Salmon and Steelhead Assessment (US EPA, 2003 b )

. In addition, EFED considered the latest Agency science policies and risk assessment methodologies.

3) Use Characterization

a) Mode of Action

Diuron is systemic and easily taken up by plants and rapidly translocated. Diuron primarily functions by inhibiting the Hill reaction in photosynthesis, limiting the production of high

- energy compounds such as adenosine triphosphate (ATP) , which is used for various metabolic processes.5 b) Overview of Pesticide Use and Usage

i) Uses

– Conventional and Antimicrobial

Diuron was first registered in the U.S. as a pre

- and post

- emergen ce herbicide, algaecide

, and
mildewcide in 1967. In the U.S.

, diuron is registered for use on numerous crop species includ ing alfalfa, apples, artichokes, asparagus, bananas, b arley, caneberries, citrus, clover, co rn , cotton, grapes, nut trees, mint, oats, papayas, pasture, peaches, pears, peas, pineapple, sorghum, sugarcane, ornamental plants , flowers and shrubs

, and wheat (USEPA, 2014a)

. Non

- agricultural uses include ornamental ponds, commercial fishery water systems

, patios, rights

- of

- way (railroad)

, and industrial sites (outdoors)

. End

use products are available as flowable concentrates

, soluble concentrates, water dispersible granules (dry flowable), granules, and p ellet s /tablet s for pre

- and post

- emergen ce control of weeds

. Diuron products registered for conventional uses may be applied using ground and aerial equipment.

Diuron is used as an a ntimicrobial material preservative in outdoor building material s such as paints, stains, stucco, caulks, sealants, masonry coatings, plaster, jo int sealants, and roof coatings. Diuron is
added as the building material is being manufactured.

ii) Usage

– Conventional

E stimates of the actual usage of diuron on a gricultural crops between 2004 and 2012 were provided by

t he Biological and Economic Analysis Division (BEAD) ( Screen ing Level Usage Analysis (SLUA); USEPA, 2014b). The greatest use of diuron in terms of pounds applied was for cotton and oranges (1.2

- 1.4
million lb ai /A)

. Asparagus was the use with the highest percentage of treated crop (65%

- 75%). Diuron uses and application rates are summarized in Appendix 1 . This information was obtained from the most recent Label Use Information System (LUIS) report provided by BE AD (USEPA, 2014 c ). The registration review risk assessment will be based on current label information at the time of assessment as provided by BEAD.

There are numerous instances where important information is missing from the labels including but not
limited to the annual maximum application rate , maximum number of applications per crop/ season and/or year, and minimum re application interval

. EFED requests that the registrant update labels to
include this information

. The LUIS report (USEPA, 2014 c ) may be consulted for a list of missing information identified by the Agency. EFED will make conservative assumptions i n the absence of label information on application rates.

iii) Usage

– Antimicrobial

Current use information is not available at this time; h owever, it was reported that less than 1% of paint

was treated with diuron at the time of the Registration Eligibility Decision (RED; USEPA, 2003c)

. 4) Conclusions from Previous Risk Assessments

a) Ecological Risk Assessment

The Agency has conducted multiple ec ological risk assessments on diuron . The documents that serve as a b asis for this problem formulation are the Environmental Risk Assessment for the Reregistration of Diuron (USEPA, 2003a ) , the Endangered and Threatened Salmon and Steelhead A ssessment (USEPA, 200 3 b ), and
the California Red

- legged Frog Assessment (USEPA, 2009) . The primary risk concerns identified in these
documents are :

• Acute and chronic risk to birds (listed and non

- listed)6 • Acute dose based (listed) and chronic dose based (listed and non

- listed) risk to mammals

• T errestrial plants ( monocots and dicots ) (listed and non

- listed)

• Acute and chronic risk to f reshwater fish (listed and non

- listed)

• Acute and chronic risk to terrestrial and aquatic

- phase amphibians

• Acute risk to estuarine/marine fish (listed)

• Acute and chronic risk to freshwater invertebrates ( l isted and non

- listed)

• Acute (listed) and c hronic r isk to estuarine/marine invertebrates

• A quatic plants

b) Drinking Water Exposure Assessments

The most recent drin king water assessment (DWA) was conducted in 2001 ( USEPA, 2001 a ) and
evaluated use on citrus . In 2003, monitoring data were evaluated and considered robust enough to use in place of chronic but not acute estimated drinking water concentrations (E DWC ) ( USEPA, 2003d ). The monitoring data were collected in Florida, Georgia, and California by state and federal agencies. A new DWA will be conducted in registration review for all registered uses of diuron to reflect current models and methodology

. c) Clean Water Programs

Diuron is identified as a cause of impairment for eight water bodies in California listed as impaired under section 303(d) of the Clean Water Act (as of 11/2014). 3 A Total Maximum Daily Load (TMDL) has not been developed. 4 The Impaired Waters and TMDL website can be consulted for more information. 5 Aquatic benchmarks h ave been established for diuron. 6

5) Environmental Fate a nd Transport

Vapor pressure (9.19 x 10

- 6 Pa at 25°C) and Henry's Law Constant (7.39 x 10

- 5 Pa·m 3 mol

- 1 ) indicate a lo w possibility of volatilization of diuron from soil and water. Laboratory data indicate that diuron is persistent based on relatively slow degradation by hydrolysis, soil photolysis, soil metabolism (aerobic and anaerobic), and aerobic aquatic metabolism (depending on the system). However, diuron degraded more quickly in water by photolysis, anaerobic aquatic metabolism, and aerobic aquatic metabol ism (depending on the system). The adsorption coefficient for diuron (mean Koc = 920) indicates moderate
mobi lity and suggests that leaching could be a route of dissipation. The available terrestrial field dissipation studies showed diuron was typically detected at a depth range of 0

- 30 cm at all test sites. Consistent with laboratory data, the terrestrial fiel d dissipation studies indicate that diuron is persistent (73

- 139 day half

- lives) in terrestrial environments. The aquatic field dissipation studies, conducted in soils (berm and slope) of drainage channels, also showed persistence of diuron in soils (115

- 142 day
half

- lives) and that some of the dissipation was the result of transport into channel sediment and water.

The p hysical, chemical, and environmental fate properties of diuron and major degradates are
summarized in Table 1 and Table 2 , respectively. Appendix 2 summarizes the maximum formation of diuron degradation products

.

3 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885

4 http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollut ant_group_name=PESTICIDES

5 http://www.epa.gov/ tmdl/

6 http://www2.epa.gov/pesticide

- science

- and

- assessing

- pesticide

- risks/aquatic

- life

- benchmarks

- pestic ide

registration/7 Table 1 : Physical, Chemical, and Environmental Fate Properties of Diuron

Parameter Value Reference (MRID unless

specified) Comments

Chemical Diuron None

--
Chemical Name N`(3,4

- dichlorophenyl)

- N,N

dimethylurea 42661901

--

Empirical Formula C 9 H 10 Cl 2 N 2 O

--
CAS Number 330

- 54

- 1 EPI Suite v 4.1 1

--
Structure 42661901

--

SMILES O=C(N(C)C)Nc(ccc(c1Cl)Cl)c1 EPI Suite v 4.1 1

-- Selected Physical/Chemical Parameters

Molecular mass 233.1 41719303

-- Water Solubility 29 mg/L (20°C)

42 mg/L (25°C) 46879701

41719303 --

Log Pow (22.5°C) 2.88 46879701

-- Vapor pressure (25°C) 9.19 x10

- 6 Pa 46894801

-- Henry’s law constant 7.39 x10

- 5 Pa·m 3 /mol None Calculated assuming solubility at 20 °C

Persistence 2

Hydrolysis (pH 5, 7, and 9) >500 days 3 41418804
Acceptable 4% decline at 30 days

Aqueous Photolysis (t 1⁄2 ) 43 days 41418805
Acceptable --

Soil Photolysis (t 1⁄2 ) 173 days 3 41719302
Acceptable ~14% decline at 30 days
Aerobic Soil Metabolism (t 1⁄2 ) 372 days 41719303
Acceptable --

Anaerobic Soil Metabolism (t 1⁄2 ) 1000 days 3 41418806
Acceptable B ased on 60 days of anaerobic exposure

Aerobic Aquatic Metabolism (t 1⁄2 ) 33, 48, and 231 days* 42260501
Acceptable

45703101
Supplemental * t 1⁄2 = 231 days
based on 24.7 % decline at study

termination

Anaerobic Aquatic Metabolism (t 1⁄2 ) 5 days 42661901
Acceptable -- O

N C H 3

C H 3 N H C l

C l8 Parameter Value Reference (MRID unless

specified) Comments

Mobility

Koc

K ads 468

- 1666 mL/g

7.9

- 28 44490501
(“Upgradeable”)

Supplemental --

Field Dissipation
Aquatic Field Dissipation (t 1⁄2 ) 115

- 142 days 43978901

43762901

“Satisfied”

Classification

TBD t 1⁄2 based on
combined data for slope and berm soils

Dissipation (t 1⁄2 ) 73

- 139 days 44654001

44865001
Acceptable --

1 http Terrestrial Field ://www2.epa.gov/tsca

- screening

- tools/epi

- suitetm

- estimation

- program

- interface

2 Half

- lives may be recalculated at the time of risk assessment using the most up

- to

- date guidance.

3 H alf

- life was extrapolated well beyond the study duration.

a) Transformation Products

Several degradates of diuron were identified in the available laboratory and field studies: four major ( mCPDMU (once

- dechlorinated diuron) , PDMU (twice

- de chlorinated diuron) , DCPMU (once

demethylated diuron)

, and mCPMU (once

- dechlorinated, once

- de meth y lated diuron) ; >10% applied )
and three minor (3,4

- DCA 7 , DCPU (twice

- demethylated diuron)

, and TCAB 8 ; <10% applied) 9

. DCPMU is also a degradate of linuron and 3,4

- DCA is also a degradate of linuron and propanil. Degradate
characteristics are reported in Table 2

.
Limited data are available for the four major degradates of diuron. Laboratory transformation data are only available for mCPDMU, which is stable to hydrolysis, aerobic soil metabolism, and aquatic metabolism (aerobic and anaerobic). The ava ilable terrestrial field dissipation study suggests that

DCPMU is more persistent than diuron. The adsorption coefficients for mCPDMU (mean Koc = 245) and PDMU (mean Koc = 70) suggest that they are more mobile than diuron. Although laboratory mobility
da ta are not available for DCPMU, the available terrestrial field dissipation study suggests that diuron and DCPMU have similar mobility characteristics because both were typically detected at the same depth range (0

- 30 cm). No data are available for mCPMU.

7 3,4

- dichloroaniline

8 Tetrachloroazobenzene (dimer of N

- benzyl portion of diuron molecule)

9 Unidentified minor degradates were observed in several studies.9 Table 2 : Physical, Chemical, and Environmental Fate Properties of Major Degradates

Parameter Value Reference (MRID unless

specified) Comments

Chemical mCPDMU Once

- dechlorinated

diuron

Chemical Name N ’

- ( 3

- chlorophenyl)

- N,N

dimethylurea 42661901

--

Empirical Formula C 9 H 11 ClN 2 O

--
CAS Number 587

- 34

- 8 EPI Suite v 4.1 1

--

Structure 42661901

--

SMILES CN(C)C(=O)Nc1cccc(Cl)c1 EPI Suite v 4.1 1

-- Selected Physical/Chemical Parameters

Molecular mass 198.65 47311702

--
Persistence 2

Hydrolysis (pH 4, 7, and 9) Stable 3 46996704
Supplemental Study conducted at

50

- 70°C. Estimated

to be stable at 20°C

Aerobic Soil Metabolism (t 1⁄2 ) 204 and 533 3 47311703
Supplemental B ased on 120 days study duration

Aerobic Aquatic Metabolism (t 1⁄2 ) Stable 3 47311701
Supplemental DT 50 > 100 days for both test systems

based on 20

- 38% decline at study

termination.

t 1⁄2 = 182 days for one test system and

was not determined

for the other

Anaerobic Aquatic Metabolism (t 1⁄2 ) Stable 3 47311702
Supplemental DT 50 > 100 days

t 1⁄2 was not

determined C H

3

N

C H

3 O

N

H C l10 Parameter Value Reference (MRID unless

specified) Comments

Mobility

Koc

K ads 139

- 418 mL/g

2.3

- 8.0 44490501
(“Upgradeable”)

Supplemental --

Chemical PDMU F enuron (twice

dechlorinated diuron)

Chemical Name 1,1

- dimethyl

- 3

- phenylurea 42661901

-- Empirical Formula C 9 H 12 N 2 O

--
CAS Number 101

- 42

- 8 EPI Suite v 4.11 1

--

Structure 42661901

--

SMILES CN(C)C(=O)NC1=CC=CC=C1 EPI Suite v 4.11 1

-- Selected Physical/Chemical Parameters

Molecular mass 164.21 Calculated

-- Mobility

Koc

K ads 38

- 132 mL/g

0.66

- 1.7 44490501
(“Upgradeable”)

Supplemental --

Chemical DCPMU Once

- demethylated

diuron

Chemical Name N

- (3,4

- dichlorophenyl)

- N`

- methylurea 42661901

--

Empirical Formula C 8 H 8 Cl 2 N 2 O

--

Structure

--

SMILES CNC(=O)NC1=CC(=C(C=C1)Cl)

Cl EPI Suite v 4.11 1

--

Selected Physical/Chemical Parameters

Molecular mass 219.07 Calculated

-- C

H

3

N

C

H

3 O

N

H

C H

3

N

H O

N

H C

l

C l11 Parameter Value Reference (MRID unless

specified) Comments

Persistence
Terrestrial Field Dissipation (t 1⁄2 ) 217

- 1733 days 44654001

44865001
Acceptable --

Chemical mCPMU Once

- demethylated,

once

- dechlorinat e d

diuron

Chemical Name N`

- (3

- chlorophenyl)

- N`

- methylurea 42661901

--

Empirical Formula C 8 H 9 ClN 2 O

--

Structure

--

SMILES CNC(=O)Nc1cccc(Cl)c1 EPI Suite v 4.11 1

-- Selected Physical/Chemical Parameters

Molecular mass 184.63 Calculated

--

1 http://www2.epa.gov/tsca

- screening

- tools/epi

- suitetm

- estimation

- program

- interface

2 Half

- lives may be recalculated at the time of risk assessment using the most up

- to

- date guidance.

3 Stable indicates half

- life was extrapolated well beyond the study durat ion or was not determined due to insufficient

decline.

6) Receptors

Consistent with the process described in the Overview Document (USEPA, 2004 ) , the risk assessment for
diuron relies on a surrogate species approach. Toxicological data generated from surrogate test species, which are intended to be representative of broad taxonomic groups, will be used to extrapolate the potential effects on a variety of species (receptors) included unde r these taxonomic groupings. Table 3 lists the most sensitive endpoints of registrant

- submitted studies that are valid for risk assessment. Appendix 3 provides a full listing of the aquatic animal and plant toxicity endpoints for diuron.

a) Effects to Aquatic Organisms

Diuron acute toxicity ranges from practically nontoxic to moderately toxic to freshwater fish ; the most

sensitive freshwater fish is the r ainbow trout ( Onc o r h ynchus mykiss ) ( TN1020 )

. In addition to a reduction in survival following chronic exposure to fathead minnow (MRID 00141636), McCraren et al. (1969; MRID 05020229) observed gill damage and an initial lower growth rate in bluegill sunfish following chronic exposure to diuron. D iur on is slightly to moderately toxic to freshwater invertebrates on an acute basis . Chronic exposure to Daphnia magna resulted in significant reductions in adult length and dry weight. C H

3

N

H O

N

H C

l12 D iuron is moderately toxic to estuarine/marine fish on acute exposure b asis ( MRID 41418803). C hronic toxicity to this tax on is uncertain due to a non

- definitive NOAEC (i.e., effects observed at the lowest test concentration)

. Diuron is moderately to highly toxic to estuarine/marine invertebrates

. Chronic exposure to mysid shr imp affected growth and reproductive rates (MRID 42500601)

. An acceptable toxicity study with nonvascular aquatic plants with green algae ( Pseudokirchneriella subcapitata ) was submitted (MRID 42218401), but studies with the marine diatom, freshwater diatom and blue green algae are needed to quantitatively assess risk to nonvascular aquatic plants . As a result, toxicity to nonvascular aquatic plants remains uncertain until new studies with these species are
submitted and found to be acceptable for quantitative use

. b) Effects to Terrestrial Organisms

Diuron is practically nontoxic to mammals (MRID 00146145) and birds (MRID 00115198) on an acute
oral basis. When mallard ducks ar e exposed to diuron on a chronic basis, the reproductive endpoints
affected are the proportion of eggs set to number eggs laid, number of eggs hatched and hatchling survivors at the highest exposure levels

. Chronic exposure to laboratory rats results in a reduction in pup weight (MRID 41957301)

. Based on the results of a single acute contact study on adult honeybees

, d iuron is practically non

- toxic
to terrestrial invertebrates . Stam et al. (1978; MRID 05016868) found that diuron is “practically non

toxic” to non

- target insect species commonly found in cotton fields

. Acceptable endpoints for all ten recommended terrestrial plant species are not available. As a result, the full toxicological effects to plants are uncertain until these data are submitted. The 5 species where acceptable endpoints for effects on vegetative vigor were submitted were pea s , oilseed rape, onion sorghum, and wheat . The 5 species where acceptable endpoints for effects on seedling emergence and germination were o ilseed rape, sugarb eet s , tomatoes, onion, and wheat. Based on effects on seedling emergence and growth, t he onion is the most sensitive monocot and sugar beet is the most sensitive
dicot (MRID 44113401 ) . In terms of effect s on vegetative vigor, the most sensitive monocot is whea t and
the most sensitive dicot was pea (MRID 44113401 )

.

Table 3 : Most Sensitive Aquatic and Terrestrial Toxicity Endpoints for Diuron

Taxa Study Type % ai Species Toxicity Value & Category MRID & Status Endpoints
Affected

Freshwater
Fish Acute

850.1075 95 .0 Rainbow

Trout Oncorhynchus mykiss 96

- hr LC 50 = 1.95 mg ai /L

M oderately

Toxic TN 1020 Acceptable Survival

Chronic

850.1400 98.6 Fathead

M innow Pimephales promelas LO A EC = 0.0618 mg ai/L

NO A EC= 0.0264 mg ai/L 00141636 Supplemental

Quantitative Survival

Freshwater
Invertebrates Acute

850.1010 95 .0 Water Flea Daphnia

magna 48

- hr EC 50 = 12 mg ai /L Slightly toxic 42046003 Acceptable Survival13 Taxa Study Type % ai Species Toxicity Value & Category MRID & Status Endpoints
Affected

Chronic

850.1300 98.1 Water Flea Daphnia

magna NOAEC = 0.057

mg ai /L

LOAEC = 0.11

mg ai /L 46996702 Acceptable Length and dry weight

Estuarine/
Marine Fish Acute

850.1075 99 .0 Sheepshead

minnow Cyprinodon variegatus 96

- hr LC 50 = 6.7 mg ai /L

NO A EL = 3.6 mg ai /L Moderately

Toxic 41418803 Acceptable Survival

Chronic

850.1400 96.8 Sheepshead

minnow Cyprinodon variegatus LO A EC = 0.44 mg ai /L

NOA EC < 0.44 mg ai /L 42312901 Supplemental

Qualitative Weight and
survival

Estuarine/

Marine
Invertebrates Acute

850.1035 99 .0 Mysid shrimp Mysidopsis
bahia 96

- hr LC 50 = 0.16 mg ai /L Highly Toxic 41418801 Acceptable Survival

Chronic

850.1350 96.8 Mysid Shrimp Mysidopsis
bahia NO A EL = 0.96 mg ai /L

LO A EL = 1.9 mg ai /L 42500601 Acceptable Length/ reproductive rate

Aquatic

Plants Vascular

850. 4400 99.1 Duckweed Lemma gibba EC 50 = 0

. 013

m g ai/L

NOAEC =
0.00249 m g ai/L

LOAEC= Not Reported 46996701 Acceptable EC 50 : Biomass
NOAEC: Frond number,
biomass

, growth

r ate

Non
Vascular

850. 4500 96.8 Green Algae
Pseudokirchne
riella subcapitata EC 50 = 0.00308

m g ai/L

NO A EC = 0.00114 m g ai/L

LO A EC = 0.00225 m g ai/L 42218401 Acceptable Biomass14 Taxa Study Type % ai Species Toxicity Value & Category MRID & Status Endpoints
Affected

Mammals Acute 98.6 Rat

Rattus norvegicus Male LD 50 = 4721 mg ai/kg

- bw
Female LD 50 >10,000 mg ai/kg

- bw Practically

nontoxic 00146145 Acceptable Mortality

Chronic 97.1 Rat

Rattus norvegicus NOAEC= 250 mg ai/kg

- diet

LOAEC= 1750 mg ai/kg

- diet 41957301 Acceptable Pup weight

Acute
Inhalation 98.6 Rat

Rattus norvegicus LC 50 >2.09 mg ai/L 45866203 Acceptable Sublethal effects
included ocular
and nasal
dis charge, irregular respiration, hunched posture and/or hypoactivity

.

Birds Acute Oral

850.2100 95.0 Mallard Duck

Anas platyrhynchos LD 50 >2000

mg ai /kg

- bw Practically

nontoxic 00115198 Acceptable No sublethal
effects.

Acute Dietary

850.2200 95.0 Northern
Bobwhite Quail
Colinus virginianus 5

- Day LC 50 = 1730 mg ai/kg

- diet Slightly Toxic 00022923 Acceptable Mortality

Chronic

850.2300 98.4 Mallard Duck

Anas platyrhynchos NOAEC= 9.80 mg a.i./kg

diet

LOAEC= 33.3 mg ai/kg

- diet 47311704 Acceptable Adult body weight (male and female), total egg production and fertility

Terrestrial
Invertebrates Adult acute

contact
850.3020 80.0 H oneyb ee Apis mellifera LD 50 = 145.03

μ g ai /bee Practically

Nontoxic 00036935 Acceptable Mortality

Terrestrial
Plants Seedling Emergence

Monocot

850.4100 97.3 Onion Allium

cepa EC 25 = 0.099 lb

ai /A

NO A EL= 0 .089
lb ai /A 44113401 Supplemental

Quantitative Shoot Dry Weight15 Taxa Study Type % ai Species Toxicity Value & Category MRID & Status Endpoints
Affected

Terrestrial
Plants Seedling Emergence

Dicot

850.4100 97.3 Sugar Beet Beta vulgaris EC 25 = 0.092 lb ai/ A

NO A EL = 0.047 lb ai/A 44113401 Supplemental

- Quantitative Shoot Dry Weight

Vegetative Vigor

Monocot

850.4150 97.3 Wheat

Triticum

aestivum EC 25 = 0.0294 lb ai/A

NO A EL = 0.0117 lb ai/A 44113401 Supplemental

Quantitative Shoot Dry Weight

Vegetative Vigor

Dicot

850.4150 97.3 Pea Pisum

sativum EC 25 = 0.0124 lb ai/A

NO A EL = 0.0117 lb ai/A 44113401 Supplemental

Quantitative Shoot Dry Weight

c) Degradate Toxicity

ECOSAR was used to predict toxicity of the major degradates (>10% formation of applied ) due to the absence of toxicity data

. ECOSAR uses quantitative structure activity relationships (QSAR) to predict toxicity to aquatic organisms

. P redicted and observed toxicity values for diuron and major degradates
are listed in Table 4

.

ECOSAR estimates provide no indication that any of the degradates are substantially more or less toxic to aquatic taxa than diuron , as all of the predicted toxicities of the degradates are within 1

- 2 orders of magnitude of the toxicity of diuron. Estimates suggest that PDMU may b e the least toxic of the degradates. In most cases

, ECOSAR provided reasonable predictions of diuron toxicity to aquatic organisms based on c omparison of empirically

- derived diuron toxicity endpoints to ECOSAR estimates

. However, there is less confidence in toxicity estimates for green algae and chronic exposure to estuarine/marine invertebrates because of the greater difference between the predicted and measured toxicity of diuron. Data are not available for any of the degradates to specifically judge c onfidence in ECOSAR estimates of the degradates.

Table 4 : Acute and Chronic (mg ai/L) Toxicity V alues P redicted t hrough ECOSAR M odeling

Exposure (Acute/ Chronic) Taxa Parent Degradate

Diuron ( L ab

S tudies ) Diuron (Predicted) DCPMU 

### m CPDMU PDMU mCPMU

Acute Daphnia magna

LC 50 12 5.7 1 8.59 20.4 8 71.2 5 3 0.48

Chronic Daphnia magna

NOAEC 0.06 0.5 5 0.7 5 1.45 3 .72 1.95

Acute Freshwater fish

LC 50 1.4 18.2 1 25.56 52.82 148.64 73.34

Chronic Freshwater fish

NOAEC 0.06 0.43 0 .58 1.10 2.7 2 1 .4616 Exposure (Acute/ Chronic) Taxa Parent Degradate

Diuron ( L ab

S tudies ) Diuron (Predicted) DCPMU 

### m CPDMU PDMU mCPMU

Acute Estuarine/
marine fish LC 50 6.7 9.8 1 11.6 1 1 6.89 28.21 19.7 7

Chronic Estuarine/
marine fish

NOAEC -- 0.5 2 1

-- -- -- --

Acute Estuarine/marine
invertebrates ( Mysidopsis
bahia )

LC 50 0.16 2.9 1 4.1 2 8 .67 25.07 19.7 7

Chronic Estuarine/marine
invertebrates ( Mysidopsis
bahia )

NOEL 0.96 0.01 0.02 0.05 0 .18 0.07

Acute Green algae

EC 50 0.004 0.1 7 0.19 0.2 7 0.4 1 0 .30

d) Ecological Incidents

T he Ecological Incident Information System ( EIIS ) maintained by the Environmental Fate and Effects Division, and the Avian Incident Monitoring System (AIMS) maintained by the American Bird Conservancy, were searched on November 3, 2015 to locate incidents resulting f rom the use of diuron

.

There were 4 2 incidents recorded in the EIIS database for diuron involving non

- target species

. Eight
incidents impacted aquatic taxa, 32 impacted terrestrial plants, and 2 impacted terrestrial /aquatic
animals . A summary list of all EIIS incidents is included in Append ix 4

.

The AIMS database recorded one incident in South Carolina where 70 birds were killed. In this case, diuron was applied as a mixture with isopropylamine salt of glyphosate and metsulfuron

- methyl

. N o information was provided about the specific cause of the incident

.

In addition to the incidents recorded in EIIS and AIMS, additional incidents are reported to the Agency in aggregated form. Pesticide registrants report certain types of incidents to the Agency as aggregate counts of incidents occurring per product per qu arter. 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 insect s and
other terrestrial invertebrates. There are 44 reported incident summaries as of November 4 , 201 5

. These summaries reported 18 minor fish and wildlife incidents and 33 minor plant incidents (s everal

summaries reported more than one incident , and as a result some of the incident summaries include both terrestrial and plant incidents )

. These incident reports do not differentiate between conventional
and antimicrobial uses.17 7) Exposure Pathways of Concern

a) Conventional Uses

The Screening Imbibition Pro gram (SIP v.1.0) and the Screening Tool for Inhalation Risk (STIR v.1.0) are upper bound screening tools used during the problem formulation phase of r egistration r eview to assess the potential for exposure to birds and mammals through drinking water and i nhalation , respectively

. These tools estimate risk to birds based on available mammalian and avian toxicity endpoints. The inputs and outputs for avian and mammalian risk are available for SIP in Appendix 5 and STIR in Appendix 6

.

SIP indicates that chro nic exposure through drinking water alone may be a potential concern for birds; however, there is not an acute concern for birds nor and acute or chronic concern for mammals

.

The STIR model indicates that avian exposure from the inhalation of droplets may be a potential

exposure pathway of concern for birds. The non

- definitive endpoints for avian acute oral exposure ( LD 50 >2000 mg ai/kg

- bw) and acute mammalian inhalation exposure (LC 50 >2.09 mg ai/L) indic ate that the re is uncertainty about the magnitude of the potential risk presented by this exposure pathway

. T he STIR
model indicates that inhalation exposure through droplets remains a concern until either the inhalation

LC 50 approaches 7mg ai/L or the ac ute oral LD 50 approaches 6900 mg ai/kg

- bw . These hypothetical endpoints are 3.45x higher (indicating a 3.45x reduction in toxic ity) than the h ighest concentrations
tested in each study

. As the available studies did not observe effects a t the highest concentrations tested, it is possible that the actual LC 50 and LD 50 values are more than 3.45x less toxic . As a result, an avian inhalation stud y is not requested at this time.

b) Antimicrobial Uses

AD intends to conduct an aquatic ecological risk assessment for the antimicrobial uses of diuron as it
leaches from paints and coatings on structures and enters surface waters. This is likely to be a small contribution relative to the conventional uses, but is a potential exposure pathway.

8) Analysis Plan

a) Stressors of Concern

i) Ecological Risk Assessment

For both the conventional and antimicrobial uses, t he stressor s of concern are diuron and major degradates mCPDMU and DCPMU (formed >10% of applied)

. Although PDMU and mCPMU are major degradates and could potentially be considered stressors of concern , they are expected to have only a

minor impact on EECs, in part because the only evidence of their formation at >10% is by anaerobic aquatic metabolism

. Nevertheless, they may be considered if it appears that risk conclusions may be impacted (past risk assessments suggest that risk conclusions would not be impacted)

. No toxicity
studies have been submitted that evaluate the toxicity of any major or minor degradates to aquatic or

t errestrial taxa

. 10 B ased on predictions from ECOSAR modeling, there is no evidence that major degradates are more or less toxic than diuron to aquatic organisms

. In the absence of toxicity data that
indicates otherwise

, the stressors of concern (mCPDMU and DCPMU ; potentially PDMU and mCPMU)

10 DCPMU also forms from linuron, an herbicide like diuron. No DCPMU toxicity data have been submitted for the linuron registration.18 will be assumed to have similar toxicity to aquatic taxa as diuron

. Furthermore, a TTR approach may be
used to estimate aquatic exposure

. DCPMU is the only stressor of concern for terrestrial environments because mCPDMU, PDMU, and mCP MU only form as major degradates in aquatic fate studies. In the absence of toxicity data, it will be assumed that diuron and DCPMU are similar in toxicity to terrestrial organisms.

ii) Drinking Water Assessment

Conventional Uses

D iuron, mCPDMU, and DCPMU will be considered the stressors of concern in the diuron DWA,
consistent with the conclusions of the Metabolism Assessment Review Committee (MARC) of the Health
Effects Division (HED) ( USEPA, 2001 b ). The residues of concern may b e reevaluated pending reevaluation of existing data and receipt and review of additional data for diuron or its degradation products.

The DWA will be based on modeled estimates of exposure but will also include a summary of available surface and ground water monitoring data. The potential use of monitoring data in place of chronic DW EECs will be reevaluated based on the availability of data reflecting present use patterns.

Antimicrobial Uses

AD does not anticipate the need to conduct a DWA for antimi crobial uses because it is assumed that residues resulting from crop uses will be higher than those resulting from leaching from structur al building elements . Therefore, it is anticipated that the drinking water residues incorporated into the
human dieta ry assessment will be based on only conventional use scenarios.

b) Measures of Exposure

The Agency will use standard available models to evaluate potential exposures to aquatic and terrestrial organisms

. 11

i) Available Monitoring Data

EFED is aware of monitoring data collected by federal and state agencies. In 2003, monitoring data collected in Florida, Georgia, and California were evaluated and considered robust enough to use in place of chronic EDWCs ( USEPA, 2003d ). The risk assessment will incorporate available data on diuron and degradation products.

ii) Down

- the

- Drain (DtD) Exposure from Antimicrobial Uses

There are 17 products with antimicrobial uses of diuron for use in outdoor building materials. The diuron content (% w/w) var ies among products, ranging from 0.12

- 0.61 % (paints, stains, and coatings),

0.09

- 0.61% (stucco, caulks, sealants, masonry coatings, and plaster), 0.07

- 0.61 % (joint sealants), and

0.25

- 0.61 % (roof coatings). According to the RED (USEPA, 2003c) , about 1 % of paints contain ed diuron
at that time

. AD does not expect any DtD exposure from diuron b ased on the regis tered antimicrobial

11 http://www2.epa.gov/pesticide

- science

- and

- assessing

- pesticide

- risks/models

- pesticide

- risk

- assessment19 uses and th e physical/chemical and environmental fate properties of diuron ( Table 1 

### ) and its degradates ( Table 2 )

. While no wastewater treatment plant exposure is expected, t here is limited potential for environmental exposure from diuron that may leach from paints and coating s used in structural building
elements

.



### c) Measures of Effect

Toxicity data presented in Table 3 and Appendix 3 of this problem formulation will 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 will also be considered. The open literature stu dies are identified using EPA's E COTOXicology database (ECOTOX), 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 insigh t into the direct and indirect effects of pesticides on biotic communities from loss of species that are sensitive to the chemicals and from changes in structure and functional
characteristics of the affected communities.

9) Endangered Species Assessment

Cons istent with EPA’s responsibility under the Endangered Species Act (ESA), the Agency will evaluate risks to federally listed threatened and endangered (listed) species from registered uses of pesticides in accordance with the Joint Interim Approaches develo ped to implement the recommendations of the April 2013 National Academy of Sciences (NAS) report, Assessing Risks to Endangered and Threatened Species from Pesticides

. The NAS report 12 outlines recommendations on specific scientific and technical

issues re lated to the development of pesticide risk assessments that EPA and the Services (U.S. Fish and Wildlife Service and National Marine Fisheries) must conduct in connection with their obligations under
the ESA and FIFRA. EPA will address concerns specific t o diuron in connection with the development of its final registration review decision for diuron

.
In November 2013, EPA, the Services, and USDA released a white paper containing a summary of their joint Interim Approaches for assessing risks to listed spe cies from pesticides. These Interim Approaches were developed jointly by the agencies in response to the NAS recommendations, and reflect a common approach to risk assessment shared by the agencies as a way of addressing scientific differences
between the EPA and the Services. Details of the joint Interim Approaches are contained in the November 1, 2013 white paper

, Interim Approaches for National

- Level Pesticide Endangered Species Act Assessments Based on the Recommendations of the National Academy of Sci ences April 2013 Report. 13

Given that the agencies are continuing to develop and work toward implementation of the Interim Approaches to assess the potential risks of pesticides to listed species and their designated critical habitat, this ecological problem formulation supporting t he Preliminary Work Plan for diuron does not describe the specific ESA analysis, including effects determinations for specific listed species or designated critical habitat, to be conducted during registration review. While the agencies continue to
develo p a common method for ESA analysis, the planned risk assessment for the registration review of
diuron will describe the level of ESA analysis completed for this particular registration review case. This
assessment will allow EPA to focus its future evaluat ions on the types of species where the potential for effects exists, once the scientific methods being developed by the agencies have been fully vetted. Once

12 http://www.nap.ed u/catalog/18344/assessing

- risks

- to

- endangered

- and

- threatened

- species

- from

- pesticides

13 http://www2.epa.gov/endangered

- species/interim

- approaches

- pesticide

- endangered

- species

- act

- assessments

based

- nas

- report20 the agencies have fully developed and implemented the scientific methods necessary to complete ris k assessments for listed species and their designated critical habitats, these methods will be applied to subsequent analyses of diuron as part of completing this registration review

. Two endangered species assessments have been conducted for diuron: Deter mination of Risks of Diuron Use to Federally Threatened California Red

- legged Frog (USEPA, 2009) and the Endangered and Threatened Salmon and Steelhead Assessment (USEPA, 2003 b ).

10) Endocrine Disruptor Screening Program

Diuron was not included in the first g roup of chemicals issued an order to conduct Tier 1 endocrine disruption screening program ( EDSP ) testing

. 14 Diuron was included in the second group of 109 chemicals issued in order to conduct Tier I EDSP testing.

11) Preliminary Identification of Data Gaps

a) Environmental Fate

Table 5 lists the status of the fate and transport data requirements for diuron. Four degradates of diuron were identified as major (forming > 10% of applied )

. 15 A limited number of laboratory studies are available for mCPDMU (hydrolysis, aerobic soil metabolism, aerobic and anaerobic aquatic metabolism, adsorption/desorption) and PDMU (adsorption/desorption) whereas none are available for DCPMU and

mCPMU. These degradates will be included in aquatic EECs for both ecological risk assessment ( mCPDMU and DCPMU and potentially PDMU and mCPMU if risk conclusions will be impacted ) and drinking water assessments (mCPDMU and DCPMU based on the most recent MARC memo (USE PA, 2001b) ). Conservative assumptions will be made about physical and chemical properties of degradates

in the absence of data and sources such as EPI Suite 16 may be used to estimate values. Study

- sourced environmental fate and physiochemical properties o f the major degradates may reduce uncertainty in the aquatic exposure and drinking water assessments.

Table 5 : Environmental Fate Data and Data Gaps for Diuron

Guideline Data Requirement MRID Classification Data Gap? Comments

835.2120 Hydrolysis 41418804 Acceptable No 1 Pending review

2 The available study tested one soil type; four are recommended. It is unlikely that additional data will
demonstrate that diuron is not stable. Therefore, EFED does not recommend requesting additional
data. 835.2240 Aqueous Photolysis 41418805 Acceptable No

835.2410 Soil Photolysis 41719302 Acceptable No

835.4100 Aerobic Soil
Metabolism 41719303

44221001 Acceptable

I n Review Yes 1

835.4200 Anaerobic Soil
Metabolism 41418806 Acceptable Yes 2

14 http://www2.epa.gov/endocrine

- disruption

15 Other major degradates could be identified in studies under review.

16 http://www2.epa.gov/tsca

- screening

- tools/epi

- suitetm

- estimation

- program

- interface21 Guideline Data Requirement MRID Classification Data Gap? Comments

835.4300 Aerobic Aquatic
Metabolism 42260501

45703101 Acceptable Supplemental No 3 The available study tested one

water

- sediment system; two are recommended. Although the data requirement is not filled, additional data are not expected to substantially change exposure
estimates. EFED does not recommend requesting additional data; howe ver, conservative assumptions will be made following current EFED guidance.

4 The available study tested three soil types; five are recommended including one with organic matter (OM) content ≤ 1%. Data on additional soils are not expected to
differ subs tantially from the available data based on preliminary
test results on two low OM content soils that was presented in the available study. EFED does not recommend requesting additional
data.

5 Guideline satisfied; study
classification to be determined (T BD).

6 ECM are available; however, ILV

are required for diuron and

DCPMU.

7 ECM are available for diuron,

DCPMU

, and mCPDMU ; however, ILV are required for these compounds. ECM and ILV are required for PDMU and mCPMU. 835.4400 Anaerobic Aquatic
Metabolism 42661901 Acceptable Yes 3

835.1230

835.1240 Leaching Adsorption/ Desorption 44490501 Supplemental Yes 4

835.6100 Terrestrial
Field Dissipation 44654001

44865001 Acceptable No

835.6200 Aquatic Field Dissipation 43762901

43978901 TBD 5 No

850.6100 Analytical
Method in S oil 41719305 Not applicable Yes 6

Analytical
Method in

Water 47033303 Not applicable Yes 7

850.1730 Accumulation
in Fish 00025491 In Review Yes 1

Non

Guideline Special Leaching Study

- Paint - - Yes

BOLD = Recommended Studies22 b) Effects

Table s 6 and 7 identify ecological effect 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 conduct a risk assessment. Rationale for the additional data requeste d is pre sent below the tables.

EFED is recommending the submission of data to characterize the toxicity of major degradates mCPDMU
and DCPMU to non

- vascular aquatic plants for two reasons. First, ECOSAR estimates do not provide evidence that they are more or less toxic than diuron to aquatic plants; therefore, in the absence of data they will be assumed equal in toxicity to diuron. However, compared to other taxa there is less confidence in the presumption of equal toxicity of diuron and degradates to aquatic pla nts due to the greater difference between the predicted and measured toxicity of diuron. Second

, previous
assessments identified a risk concern for aquatic plants based on exposure to only diuron ; thus, the risk
conclusion (i.e., there is a risk concern) would not have change d if the degradates had been considered
in the risk assessment

. Nonetheless , assumptions made about degradate toxicity to aquatic non

vascular plants could have an impact on any future mitigation efforts

. Data are recommended to

con firm the assumption of equal toxicity of mCPDMU, DCPMU, and diuron given the greater uncertainty
about this assumption for aquatic non

- vascular plants than for other taxa

.

At this point, study

- sourced data on toxicity of mCPDMU and DCPMU to fish and invertebrate taxa are not recommended because ECOSAR was able to provide reasonable toxicity estimates for degradates that suggested similar toxicity to diuron

. In the absence of toxicity data, mCPDMU, DCPMU, and diuron will be assumed equall y toxic to fish and aquatic invertebrates.

Table 6 : Data Gap Table of Aquatic Effect Data f or Diuron and Major Degradates

Guideline Data requirement MRID Classification Data Gap? Comments

850.1010 Freshwater
Invertebrate Acute Toxicity 42046003 Acceptable No

-

850.1025 Estuarine/Marine
Invertebrate Acute Toxicity 41418801 Acceptable No

-

850.1075 Freshwater Fish Acute Toxicity TN 1020/

STODIU04 Acceptable No

-

850.1075 Estuarine/Marine

F ish Acute Toxicity 41418803 Acceptable No

-

850.1300 Freshwater
Invertebrate Life Cycle 46996702 Acceptable No

-

850.1350 Estuarine/Marine
Invertebrate Life Cycle 42500601 Acceptable No

-23 Guideline Data requirement MRID Classification Data Gap? Comments

850.1400 Freshwater Fish Early

- Life Stage 00141636 Supplemental No Raw data are unavailable and

test concentrations were not analytically confirmed throughout the study. Study may be used to fulfil guideline requirement for a Freshwater Fish Early

- Life Stage test.

850.1400 Estuarine/Marine Fish Early

- Life Stage 42312901 Supplemental Yes Study does not fulfill guideline requirements. Significant reductions in weight and/or survival at all
concentrations meant that a

NOAEC value could not be
established. In the absence of data, endpoints from linuron

may be used in risk

assessments.

850.4 400 Aquatic Vascular Plant Toxicity Test using Lemna spp. 46996701 Acceptable No

-

850.4500 Nonvascular Aquatic Plants: Algal Toxicity
Pseudokirchneriella subcapitata 42218401 Acceptable No

-

850.4500 Nonvascular Aquatic Plants:
Freshwater diatom
Navicula pelliculosa 47936502 Supplemental (qualitative) Yes The shorter than
recommended duration of the study means that this study may only be used to assess risk qualitatively and
do es not satisfy guideline requirements

. 850.4500 Nonvascular Aquatic Plants:
Marine diatom
Skeletonema

costatum - - Yes

-

850.4550 Nonvascular Aquatic Plants: Blue Green Algae Anabaena flos

aquae 47936501 Supplemental (qualitative) Yes The shorter than
recommended duration of the study means that this study may only be used to assess risk qualitatively and does not satisfy guideline requirements.24 Guideline Data requirement MRID Classification Data Gap? Comments

Degradate DCPMU There is uncertainty in the ECOSAR estimates, but ECOSAR suggests that degradates are potentially similar to diuron in toxicity. Recommending submission of algae data to refine risk conclusions given ECOSAR
estimates and the mode of
action as an herbicide.

T oxicity data are
recommended only for the aquatic plant species most
sensitive to diuron . The most sensitive aquatic plant species will be determined upon review of aquatic plant
studies. 850.4500 /

850.4550 Algal / Cyanobacteria Toxicity - - Yes

Degradate mCPDMU

850.4500 /

850.4550 Algal / Cyanobacteria Toxicity - - Yes

BOLD = Recommended Studies

Table 7 : Data Gap Table of Terrestrial Effects Data for Diuron

Guideline Data requirement Submitted
Studies (MRID) Classification Data Gap? Comments

850.2100 Avian Acute Oral Toxicity (Upland

game or waterfowl species) 00115198 Acceptable No

-

850.2100 Avian Acute Oral Toxicity (Passerine species) - - Yes Measures of effect from a

non

- passerine species could potentially underestimate diuron toxicity to passerine species, consequently,
additional information on diuron toxicity to a passerine species is needed to reduce the uncertainty.

850.2200 Avian Dieta ry Toxicity 00022923 Acceptable No

-25 Guideline Data requirement Submitted
Studies (MRID) Classification Data Gap? Comments

850.2300 Avian Reproduction 47311704 Acceptable Yes Data submitted are for mallard duck only; data are also required for an upland bird species

. 850.3020 Tier I

- Honeyb ee Acute Adult Contact Toxicity 00036935 Acceptable No

-

Non

Guideline (OECD 213) Tier I

- Honeybee

A cute A dult O ral Toxicity - - Yes

-

Non

Guideline Tier I

- Honeybee

A dult C hronic

O ral E xposure - - Yes

-

850.3030 Tier II

- Honeybee Toxicity of
Residues on Foliage - - No The acute contact 48

- hr

LD 50 was above 100 μg/bee. This study is triggered if contact toxicity is less than 11 μg/bee

. Non

Guideline Tier I

- Honeybee
Larval Acute and

C hronic O ral

E xposure - - Yes

-

Non

Guideline Tier II

- Nectar
and Pollen Residue Study
for Insect
Pollinators - - Yes If risks are identified in the
Tier I risk assessment then

Tier II studies may be
needed . Diuron is systemic
and some registered uses are pollinator attractive

crops 17 , so exposure through translocation to nectar and pollen could be a
route of expos ure to insect pollinators. In addition, incidental residues may
occur on or near the

treatment site. Non

Guideline (OECD 75) Tier II

- Semi

Field Testing for Honeybees (tunnel and feeding studies) - - Yes

850.3040 Tier III

- Field Testing for
Pollinators - - Yes If risks are identified in the

Tier II risk assessment then
Tier III field studies may be
needed

.

17 USDA, 2014. Attractiveness of Agricultural Crops to Pollinating Bees for the Collection of Nectar and /or Pollen.26 Guideline Data requirement Submitted
Studies (MRID) Classification Data Gap? Comments

850.4100 Seedling Emergence and Seedling Growth 44113401 Supplemental Yes Th e seedling emergence and growth study (MRID 44113401) submitted valid endpoints for the following species:

• Oilseed Rape

• Sugar Beet

• Tomato

• Onion

• Wheat

The vegetative vigor study submitted valid endpoints for the following species :

• Pea

• Oilseed Rape

• Onion

• Sorghum

• Wheat

To fulfil guideline requirements, valid endpoints must be
submitted fo r the required number and type of species

. 850.4100 Seedling Emergence and Seedling Growth 42398501 Invalid

850.4150 Vegetative Vigor 44113401 Supplemental Yes

Yes 850.4150 Vegetative Vigor 42398501 Invalid

BOLD = Recommended Studies

12) References

Johnson, W. and Finley, M.

, 1980. Handbook of acute toxicity of chemicals to fish and aquatic
invertebrates. Resource Publication 137. U

. S

. Fish and Wildlife Service, Washington, D.C. 98p.

McCraren, J.P., Cope, O.B., Eller, L.

, 1969. Some chronic effects of diuron on bluegills. Weed Science 17(4): 497

- 504. MRID 05020229

Stam, P.A., D.F., Clower, J.B., Graves, and P.E., Schilling.

, 1978. Effe cts of certain herbicides on some insects and spiders found in Louisiana cotton fields. Journal of Economic Entomology. 71 (3):477

- 480. MRID 05016868.

USEPA, 2001 a . Drinking Water Assessment for Diuron and its Degradates. Environmental Fate and
Effects Di vision, Office of Pesticide Programs, U

. S

. Environmental Protection Agency. D275046.

USEPA, 2001 b

. Diuron

. Results of the Health Effects Division (HED) Metabolism Assessment Review Committee (MARC) Meeting Held on 03

- July

- 2001. Health Effects Division, Office of Pesticide Programs, U

. S

. Environmental Protection Agency.27 USEPA, 2003 a . Environmental Risk Assessment for the Reregistration of Diuron. Environmental Fate and Effects Division, Office of Pesticide Programs, U

. S

. Environmental Protection Agency. D 275045.

USEPA, 2003 b . Diuron (035505): Analysis of Risks to Endangered and Threatened Salmon and Steelhead. Environmental Fate and Effects Division, Office of Pesticide Programs, U

. S

. Environmental Protection Agency. http://www.epa.gov/oppfead1/endanger/litstatus/effects/#diuron

USEPA, 2003 c

. Registration Eligibility Decision (RED) for Diuron. Office of Pesticide Programs, U

. S

. E nvironmental Protection Agency. http://arc hive.epa.gov/pesticides/reregistration/web/pdf/diuron_red

- 2.pdf

USEPA, 2003 d . Surface Water Monitoring Data for Diuron. Environmental Fate and Effects Division, Office of Pesticide Programs, U

. S

. Environmental Protection Agency. D281404.

USEPA

, 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs. Environmental Fate and Effects Division, Office of Pesticide Programs, U

. S

. Environmental Protection Agency. January 23, 2004.

USEPA, 2009. Diuron (035505): Risk s of Diuron Use to Federally Threatened California Red

- legged Frog ( Rana aurora draytonii ). Environmental Fate and Effects Division, Office of Pesticide Programs,

U

. S

. Environmental Protection Agency. http://www.epa.gov/oppfead1/endanger/litstatus/effects/#diuron

USEPA, 2014a. BEAD Chemical Profile (BCP) for Registration Review: Diuron (035505)

.
USEPA, 2014 b . Diuron (035505) Screening Level Usage Analysis (SLUA).

USEPA, 2014 c

. Revised Diuron (035505) Label Use Report Package in Support of Registration Review. Environmental Fate and Effects Division, Office of Pesticide Programs, U

. S

. E nvironmental Protection Agency.28 Appendix 1: Maximum Application Rates of Diuron (Conventional Uses)

The purpose of T able 1

- 1 is to summarize the maximum application rates reported in the most recent LUIS report (USEPA, 2014 c ). It does not include antimicrobial use rates which are based on applicat ions to the paint or building material as they are being manufactured. The antimicrobial exposure assessment will be based on the amount leached from the materials and the amount of materials
assumed to be used in the watershed and not based on the use r ate.

The table is not intended to capture all the nuance of the labeled rates; therefore, it should not be relied upon for risk assessment. For example, in some cases the highest maximum application rate may be applied to only a specific geographic area , using a specific application technique, under specific timing (e.g., relative to season or planting), etc. and a lower maximum application rate would apply under different restrictions. Furthermore, in some cases some labels may provide information such as the maximum number of applications per year and others do not. In these and similar cases either the lack of information or the most conservative value is reported below. For example, for a given use/application rate if the maximum number of applicat ions is reported on one label and not another then NS (not stated) is reported below. Likewise, if an annual application limit is reported on one label and not another then NS is reported below. Along the same lines, if a use has a lower maximum single

a pplication rate without an associated annual limit then that rate is reported below in addition the highest maximum single application rate ( e.g. , see banana). The registration review risk assessment will
be based on current label information at the time of assessment as provided by BEAD.

Table 1

- 1 A Summary of Maximum Application Rates of Diuron (Conventional Uses)

Use Max Single Application Rate
(lb ai/A) Max # Applications per Year/ Crop Cycle
(lb ai/A) Max Application Rate per Year/

Crop Cycle

(lb ai/A) Minimum

Retreatment Interval (days)

Airports/Landing Fields 12 1 NS 12 90

Alfalfa 2.4 1 2.4 NS Apple 3.2 NS/ NS 3.2/ 3.2 90

Artichoke 3.2 NS NS NS
Asparagus 2.4 2 NS NS

3.2 1 NA NA

Banana 4.8 NS 9.6215 42

2.4 NS NS NS Barley 1.6 1/ 1 NS/ NS NS Blueberry 3.2 NS NS NS

Caneberries 1.6 2 NS NS

2.4 NS/ 1 NS/ NS NS

Citrus 3.2 NS NS NS

6.4 NS 6.4 NS

Clover 1.6 1/ 1 NS/ NS NS Commercial Fishery Water Systems 3.2 2 9 NS 7

0.025 3 9 NS 7 Corn, Field 1.1 NS NS NS29 Use Max Single Application Rate
(lb ai/A) Max # Applications per Year/ Crop Cycle
(lb ai/A) Max Application Rate per Year/

Crop Cycle

(lb ai/A) Minimum

Retreatment Interval (days)

Cotton (Unspecified) 1.6 NS 2.2 21

2.2 NS 2.2 21 Drainage Systems 12 NS 12.0269 90 Filbert (Hazelnut) 2.2 NS/ NS 3.2072 /3.2072 150 Gooseberry 1.6 2/ 2 NS/ NS NS

2.4 NS/ 1 NS/ NS NS
Grapes 4 NS/ NS 8.0179/ 8 90

Grasses Grown For Seed 2.4 1 2.4054 NS Household/Domestic Dwellings Outdoor

Premises 12 1 NS 12 90

Industrial / Construction Areas (Outdoor) 8 NS 12 90

12 1 NS 12 90 Irrigation Systems 12 NS 12.0269 90 Macadamia Nut (Bushnut) 4.8 NS 8.0179 NS Nonagricultural Outdoor Buildings/Structures 12 1 NS 12 90 Nonagricultural Rights

- Of

Way/Fencerows/Hedgerows 8 NS 12 90

12 1 NS 12 90 Nonagricultural Uncultivated Areas/Soils 12 2 NS 90 Nonagricutural Uncultivated Soil

Sterilization 12 1 NS 12 90

Oats 1.6 1 NS NS

Olive 1.6 2 NS NS Ornamental and/or Shade Trees 4 NS NS NS

Ornamental Herbaceous Plants 4.4 NS/ 1 NS/4.3796 NS

4 NS 6.0134 NS Ornamental Nonflowering Plants 3.2 NS/ 1 NS/ NS NS

Ornamental Ponds/Aquaria 0.0001 4 NS NS NS

NDC NS NS 30
Papaya 4 NS NS NS

Pastures 2.4 NS NS NS Paths/Patios 12 1 NS 12 90

Paved Areas (Private Roads & Sidewalks) 12 1 NS 12 90

Peach 3 NS NS NS

Pear 3.2 NS NS NS Peas (Unspecified) 1.6 NS NS NS

Pecan 3.2 1 NS NS Peppermint 2.4 NS NS NS Pineapple 5 NS NS NS

6.4 NS/ NS NS/ 12.8 NS

Plantain 4.8 NS 9.6215 42

2.4 NS NS 42 Pricklypear Cactus Pads 3.5 NS NS NS30 Use Max Single Application Rate
(lb ai/A) Max # Applications per Year/ Crop Cycle
(lb ai/A) Max Application Rate per Year/

Crop Cycle

(lb ai/A) Minimum

Retreatment Interval (days)

Recreational Areas 12 1 NS 12 90 Rights

- Of

- Way (Railroad) 12 NS 12 90 Sorghum 0.4 NS NS NS Spearmint 2.4 NS NS NS
Sugarcane 6.4 NS/ NS NS/ 16 NS

5 NS 9.62 NS

4.8 NS NS NS

Trefoil 1.6 NS/ 1 NS/ NS NS

Triticale 1.6 NS/ 1 NS/ NS NS

Urban Areas 12 1 NS 12 90 Utility Poles / Rights

- Of

- Way 12 1 NS 12 90 Walnut (English/Black) 3 NS/ NS 3.2/ 3.2072 150

Wheat 1.6 NS NS NS31 Appendix 2 : Diuron Degradates Identified in Environmental Fate Studies

Table 2

- 1 . A Summary of Diuron Degradates Identified in Environmental Fate Studies

Degradate

Name Chemical Name Major Degradates
(>10% formed) Minor Degradates
(<10% formed)

Maximum Percent Formed 1

mCPDMU N ’

- ( 3

- chlorophenyl)

- N,N

- dimethylurea Aerobic Aquatic Metabolism : 25%, total system (study termination; increasing)

MRID 42260501

24.1%, total system (day 55; decreasing to study termination)

MRID 45703101

Anaerobic Aquatic Metabolism : 76

- 83%, total system (day 7

- 98; decreasing to study termination)

MRID 42661901 --

PDMU (fenuron) 1,1

- dimethyl

- 3

- phenylurea Anaerobic Aquatic Metabolism : 13%, total system (day 288; decreasing to study termination)

MRID 42661901 --32 Degradate

Name Chemical Name Major Degradates
(>10% formed) Minor Degradates
(<10% formed)

Maximum Percent Formed 1

DCPMU N

- (3,4

- dichlorophenyl)

- N ’

- methylurea Aerobic Soil Metabolism : 21.7% (study termination; increasing)

MRID 41719303

Anaerobic Soil Metabolism : 10.3% (day 45 of anaerobic conditions; relatively constant through study termination)

MRID 41418806

Terrestrial Field Dissipation : 13.7% of maximum diuron detection; 0

- 90 cm core (day 22 FL site; decreasing to study

term ination)

MRID 44654001 & 44865001 Soil Photolysis : 3.6% (study termination)

MRID 41719302

Aerobic Aquatic Metabolism : 9.2%, total system (day 22; relatively constant through study termination)

MRID 42260501

4.4%, total system (day 91;

constant to study termination)

MRID 45703101

4.1%, total system (study termination; increasing)

MRID 45703101

Terrestrial Field Dissipation : 6.9% of maximum diuron detection; 0

- 90 cm core (day 29 MS site; decreasing to study termination)

MRID 44654001 & 44865001

9.9% of maximum diuron detection;

0

- 90 cm core (day 120 CA site; decreasing to study termination)

MRID 44654001 & 44865001

Aquatic Field Dissipation : detected in berm soil, slope soil, and channel sediment (only silt loam application site); estimated < 10% of d iuron detected immediately after application in berm and slope soil.

MRID 43762901 & 43978901

mCPMU N ’

- ( 3

- chlorophenyl)

- N ’

- methylurea Anaerobic Aquatic Metabolism : 21%, total system (study termination; increasing)

MRID 42661901 Aerobic Aquatic Metabolism : 1.1%, total system (study termination; increasing)

MRID 42260501

3,4

- DCA 3,4

- dichlorobenzeneamine -- Hydrolysis : 0.5% (study termination)

MRID 41418804

Soil Photolysis : 0.029% (day 14 followed by decline to study termination)

MRID 4171930233 Degradate

Name Chemical Name Major Degradates
(>10% formed) Minor Degradates
(<10% formed)

Maximum Percent Formed 1

DCPU 3,4

- dichlorophenylurea -- Soil Photolysis : 0.6% (study termination)

MRID 41719302

Aerobic Soil Metabolism : 0.9% (day 30; relatively constant through study termination)

MRID 41719303

TCAB 3, 3’ ,4,4’

- tetrachloroazobenzene -- Soil Photolysis : 0.038 ppm (day 14; stable to study termination)

MRID 41719302

-- 3

- chloroaniline

-- Hydrolysis (mCPDMU study) : estimated < 10% (day 30 @ 20°C)

MRID 4699670434 Degradate

Name Chemical Name Major Degradates
(>10% formed) Minor Degradates
(<10% formed)

Maximum Percent Formed 1

Unidentified

-- Anaerobic Aquatic Metabolism (mCPDMU study ) : Mean total of unidentified peaks was 10.6% (total system at study termination); unidentified largest peak 12.7% (total system at study termination

MRID 47311702 Hydrolysis (mCPDMU study) : one unknown estimated < 10% (day 30 @ 20°C)

MRID 46996704

Aqueous Photolysis : < 9% (at least 13 unknowns); the most substantial unknown formed 8.5% (day 51.4)
then declined

MRID 41418805

Soil Photolysis : 3.2% (one unknown, study termination)

MRID 41719302

Aerobic Soil Metabolism : 3.3%, unknown B1 (day 30; relatively constant through study termination)

MRID 4171930 3

Aerobic Soil Metabolism: (mCPDMU study ) : largest unknown peaks; 1.8%, silty clay loam soil and 4.1%, sandy loam soil (day 46 in both soils)

MRID 47311703

Aerobic Aquatic Metabolism : 1.1%, unknown A; total system (day 22; relatively constant through study termination)

MRID 4171930335 Degradate

Name Chemical Name Major Degradates
(>10% formed) Minor Degradates
(<10% formed)

Maximum Percent Formed 1

Unidentified

-- 3.5%; sum of other unknowns each contributing < 0.6%; total system (study termination; increasing)

MRID 41719303

0.6%; unclear if single unknown or sum of unknowns, total system (study termination, increasing)

MRID 45703101

3.2%; unclear if single unknown or sum of unknowns, total system (day 14; decreasing to study termination)

MRID 45703101

Aerobic Aquatic Metabolism (mCPDMU study ) : Unidentified peaks totaled 3.9%; total system of

river water

- loam sediment (study

terminatio n)

MRID 47311701
Unidentified peaks totaled 6.3%; total system of lake water

- sandy loam sediment (day 76); decrease at day 100

MRID 47311701

Anaerobic Aquatic Metabolism : 4.1%, sum of unknowns, total system (study termination; slightly increasing)

MRID 42 661901

1 Fate studies for diuron unless indicated otherwise.36 Appendix: 3 : Complete List of Toxicity Endpoints for Diuron

Table 3

- 1: Summary of Toxicity Endpoints from Aquatic Toxicity Studies for Diuron

Study Type Species % ai Toxicity Value & Category MRID & Status

Freshwater fish

Acute Rainbow Trout Oncorhynchus mykiss 80 96

- hr LC 50 : 4.9 mg ai /L Moderately toxic 40094602 1 Supplemental

Bluegill Sunfish Lepomis
macrochirus 95 96

- hr LC 50 : 3.2 mg ai/L Moderately Toxic STODIV03 Acceptable

Rainbow Trout Oncorhynchus mykiss 28 96

- hr LC 50 : 23.8 mg ai/L Slightly Toxic STODIV02 Acceptable

Bluegill Sunfish Lepomis
macrochirus 28 96

- hr LC 50 : 84 mg ai/L Slightly Toxic STODIU04 Acceptable

Rainbow Trout Oncorhynchus mykiss 95 96

- hr LC 50 : 3.2 mg ai/L Moderately Toxic STODIU03 Acceptable

Rainbow Trout Oncorhynchus mykiss 95 96

- hr LC 50 : 1.95 mg ai/L Moderately Toxic TN 1020 Acceptable

Bluegill Sunfish Lepomis
macrochirus 80 96

- hr LC 50 >300 mg ai/L Practically Nontoxic 42046001 Acceptable

Rainbow Trout Oncorhynchus mykiss 80 96

- hr LC 50 : 190 mg ai/L Practically Nontoxic 42046002 Acceptable

Fathead Minnow Pimephales promelas 98.6 96

- hr LC 50 : 14.2 mg ai/L Slightly Toxic STODIU07 Acceptable

Cutthroat Trout Oncorhynchus
clarki 95 96

- hr LC 50 : 1.4 mg ai/L Moderately Toxic 40094602 1 Supplemental

Lake Trout
Salvelinus namaycush 95 96

- hr LC 50 : 2.7 mg ai/L Moderately Toxic 40094602 1 Supplemental

Acute and Chronic (Early

Life Stage) Fathead minnow Pimephales promelas NS 2 96

- hr LC 50 : 14.2 mg ai/L

LO A EC: 0.0618 mg ai/L

NO A EC: 0.0264 mg ai/L
Sublethal Effects: lethargy Slightly Toxic 00141636 Supplemental

– Qualitative

D oes not fulfill guideline

- Raw data and percentage of active ingredient are not
included37 Study Type Species % ai Toxicity Value & Category MRID & Status

Freshwater invertebrates

Acute Water Flea Daphnia pulex 95 48

- hr EC 50 : 1.4 mg ai/L Moderately Toxic 40094602 1 Supplemental

Zooplankton Simocephalus sp. 95 48

- hr EC 50 : 2.0 mg ai/L Moderately Toxic 40094602 1 Supplemental

Stone Fly Pteronarcys sp. 95 96

- hr LC 50 : 1.2 mg ai/L Moderately Toxic 40094602 1 Supplemental

Water Flea Daphnia magna 80 48

- hr EC 50 : 12 mg ai /L Slightly toxic 42046003 Acceptable

Chronic Water Flea Daphnia magna 98.2 NO A EC: 0.2 mg ai/L

LO A EC > 0.2 mg ai/L Endpoint: mortality STODIV05 Acceptable

Water Flea Daphnia magna 98.1 Length NOAEC: 0.057 mg ai/L Length LOAEC: 0.11 mg ai/L Endpoints affected: Adult Survival, Live Young Produced, Growth (Length and dry weight) 46996702 Acceptable

Estuarine marine fish

Acute Sheepshead

minnow Cyprinodon variegatus 99 96

- hr LC 50 : 6.7 mg ai/L

NO A EL: 3.6 mg ai/L Moderately Toxic 41418803 Acceptable

Chronic (Early

Life Stage) Sheepshead

minnow Cyprinodon variegatus 96.8 LO A EC: 0.44 mg ai/L
NOAEC: couldn’t be
determined

- Weight
and survival significantly reduced
at all tested

concentrations 42312901 Supplemental

Qualitative
Does not fulfill guideline

- could not
establish a NOAEC

Estuarine Marine Invertebrates

Acute Mysid shrimp Mysidopsis bahia 99 48

- hr LC 50 : 1. 2 mg ai/L

NO A EL: 0.6 mg ai/L Moderately Toxic 41418801 Acceptable

Scud

Gammarus fasciatus 95 96

- hr LC 50 : 0.16 mg ai/L Highly Toxic 40094602 1 Supplemental

Eastern Oyster

Crassostrea virginica 96.8 48

- hr EC 50 = 4.8 mg ai/L 42217201 Acceptable38 Study Type Species % ai Toxicity Value & Category MRID & Status

Reduction in shell
thickness was
observed at all test
levels. Moderately Toxic

Chronic (Life Cycle Toxicity) Mysid Shrimp Mysidopsis bahia 96.8 NO A EL: 0.96 mg ai/L

LO A EL: 1.9 mg ai/L

Most sensitive parameter: Length/ reproductive rate 42500601 Acceptable

Aquatic Plants

Vascular Duckweed Lemma gibba 99.1 EC 50 : 0

. 00019 mg ai/L

Biomass

NOAEC: 0.00249 m g ai/L LOAEC: Not Reported

Most sensitive
parameter: Frond number, Biomass, Growth Rate 46996701 Acceptable

Non

- Vascular Green Algae
Pseudokirchneriella subcapitata 96.8 EC 50 : 0.00308 m g ai/L 1

NOEC: 0.00114 m g ai/L

LO A EC: 0.00225 m g ai/L
biomass 42218401 Acceptable

Blue

- Green Alga Synechococcus leopoliensis 96.8 EC 50 : 0.026 mg ai/L

Biomass 47936501 Supplemental

qualitative
Freshwater

Diatom Navicula pelliculosa 96.8 EC 50 : 0.022 mg ai/L

LO A EC: 0.033 mg ai/L

NO A EC: 0.011 mg ai/L

Biomass 47936502 Supplemental

qualitative

Green Algae
Scenedesmus subspicatus 96.7 EC 50 : 0.0079 mg ai/L

LO A EC: 0.0032 mg ai/L

NO A EC: 0.0056 mg ai/L

Biomass 47946501 Supplemental

qua litative

1 These endpoints (Johnson and Finley, 1980) were published as a collection of a produced by government laboratories. This collection is a useful resource for characterizing risk, but care should be taken as th e data are not available for verification of accuracy of the analysis. As data are not reviewed, these endpoints are classified as supplemental and should only be used to characterize risk qualitatively.

2 The %ai was not specified in this study

Table 3

- 2 : Summary of Toxicity Endpoints from Terrestrial Toxicity Studies for Diuron39 Study Type Species %ai Toxicity Value & Category MRID & Status Mammalian Toxicity

Acute (Oral) Rat Rattus norvegicus 98.6 Male LD 50 : 4721 mg/kg

- bw
Female LD 50 > 10,000 mg/kg

bw Practically nontoxic 00146145 Acceptable

Chronic (2 generation) Rat Rattus norvegicus 97.1 NO A EL/LO A EL : 250/1750 mg/kg Affected Endpoints: Pup weight 41957301 Acceptable

Acute (Inhalation) Rat Rattus norvegicus 98.6 LC 50 >2.09 mg ai /L
Sublethal effects: ventral staining, facial staining, reduced fecal volume, dyspnea. 45866203 Acceptable

Avian Toxicity

Acute (Oral) Mallard Duck Anas platyrhynchos 95 LD 50 >2000 mg/kg

- bw Practically nontoxic 00115198 Acceptable

Sub

- Acute

Dietary Northern Bobwhite Quail Colinus virginianus 95 5

- Day LC 50 : 1730 mg ai /kg

- bw 00022923 Acceptable

Japanese Quail Coturnix japonica 95 5

- Day LC 50 >5000 mg ai /kg

bw 00022923 Acceptable Ring

- Necked Pheasant
Phasianus colchicus 95 5

- Day LC 50 >5000 mg ai /kg

bw 00022923 Acceptable
Mallard Duck Anas platyrhynchos 95 5

- Day LC 50 : 5000 mg ai /kg

- bw 00022923 Acceptable

Chronic (Reproductive) Mallard Duck Anas platyrhynchos 98.4 NOAEC: 9.80 mg ai/ kg

- diet

LOAEC : 33.3 mg ai/ kg

- diet Endpoints affected: Adult body weight (male and female), total egg production and fertility 47311704 Acceptable

Terrestrial Invertebrate s

Adult

- Acute

(Contact) Honeyb ee Apis mellifera TEP

not speci
fied LD 50 >10 μ g ai /bee Practically nontoxic 00001999 Acceptable

Adult

- Acute

(Contact) Honeyb ee Apis mellifera 80 LD 50 : 2.77 μ g ai /bee Moderately toxic 00036935 Acceptable

Terrestrial Plants ( Seedling Emergence )

Monocot specie s Onion Allium cepa 97.3 EC25: 0.099 lb ai/A

NO A EL: 0.089 lb ai/A Shoot Dry Weight 44113401 Supplemental 1

Wheat

Triticum aestivum 97.3 EC25: 1.05 lb ai/A

NO A EL: 0.38 lb ai/A Shoot Dry Weight 44113401 Supplemental 140 Study Type Species %ai Toxicity Value & Category MRID & Status

Dicot species Rapeseed Brassica napus 97.3 EC25: 0.094 lb ai/A

NO A EL: 0.047 lb ai/A Shoot Dry Weight 44113401 Supplemental 1

Sugar Beet Beta vulgaris 97.3 EC25: 0.092 lb ai/A

NO A EL: 0.047 lb ai/A Shoot Dry Weight 44113401 Supplemental 1

Tomato Lycopersicon
esculentum 97.3 EC25: 1.05 lb ai/A

NO A EL: 0.38 lb ai/A Shoot Dry Weight 44113401 Supplemental 1

Terrestrial Plants (Vegetative Vigor)

Monocot species Onion Allium cepa 97.3 EC25: 0.187 lb ai/A

NO A EL: 0.375 lb ai/A Shoot Dry Weight 44113401 Supplemental 1

Sorghum Sorghum bicolor 97.3 EC25: 0.0555 lb ai/A

NO A EL: 0.0117 lb ai/A Shoot Dry Weight 44113401 Supplemental 1

Wheat

Triticum aestivum 97.3 EC25: 0.0294 lb ai/A

NO A EL: 0.0117 lb ai/A Shoot Dry Weight 44113401 Supplemental 1

Dicot species Pea

Pisum sativum 97.3 EC25: 0.0124 lb ai/A

NO A EL: 0.0117 lb ai/A Shoot Dry Weight 44113401 Supplemental 1

Rapeseed Brassica napus 96.8 EC25: 0.0360 lb ai/A

NO A EL: 0.0469 lb ai/A Shoot Dry Weight 44113401 Supplemental 1

1 The seedling emergence that provided valid endpoints for terrestrial plants (MRID 44113401) only tested onion, wheat, rapeseed, sugar beets, and tomatoes. The guideline requires that a minimum of 10 species need to be tested, 4 of which are monocot species , one of which must be corn, and 6 dicot species, one of which must be soybean. Until this guideline requirement is fulfilled, toxicity to terrestrial plants remains an uncertainty.4142 Appendix 4 : Ecological Incidents Associated with Diuron (E IIS database )

Table 4

- 1

Incident ID Type Total Magnitude State Year Legality

B0000

- 300

- 32 AQUATIC

- SC 1982 Undetermined

B0000

- 300

- 45 PLANTS

- OK 1972 Undetermined

I000022

- 001 TERRESTRIAL/AQUATIC

- SC 1992 Undetermined

I005925

- 001 AQUATIC

- TX 1997 Undetermined

I005925

- 008 AQUATIC 3000 fish MD 1996 Undetermined

I005925

- 010 AQUATIC

- OK 1996 Undetermined

I005925

- 014 AQUATIC

- TX 1995 Undetermined

I005972

- 001 PLANTS

- TX 1997 Registered Use

I007154

- 001 AQUATIC

- MS 1998 Registered use

I007269

- 002 PLANTS

- TN 1998 Registered use

I013194

- 001 PLANTS 10 acres ND 2002 Undetermined

I013281

- 008 AQUATIC

- OK 2002 Undetermined

I013587

- 020 PLANTS

- WA 1998 Registered use

I013850

- 001 PLANTS 1/3 of back yard MI 2002 Registered use

I013884

- 004 PLANTS

- WA 1998 Registered use

I014177

- 001 PLANTS 30 acres CA 2002 Registered use

I014407

- 013 PLANTS

- WA 1994 Undetermined

I014409

- 062 PLANTS

- WA 1992 Undetermined

I0144700

- 001 PLANTS

- OK 2004 Registered use

I015278

- 001 PLANTS 67 acres OR 2003 Registered use

I015382

- 001 PLANTS

- WY 2004 Undetermined

I015796

- 001 PLANTS 1

- 4 acres KY 2004 Registered use

I016036

- 024 PLANTS 53 acres CA 2004 Registered use

I016302

- 001 PLANTS Less than an

acre WA 2005 Undetermined

I016362

- 001 PLANTS

- MI 2005 Undetermined

I016429

- 001 PLANTS $90,000 damage WA 2005 Registered use

I016569

- 001 PLANTS

- NM 2005 Undetermined

I018428

- 010 PLANTS 4 acres CA 2006 Registered Use

I018527

- 001 PLANTS

- WY 2007 Undetermined

I019519

- 045 PLANTS 7 acres CA 2008 Undetermined

I020180

- 033 PLANTS 9 acres CA 2008 Undetermined

I020274

- 001 AQUATIC 5,000 fish CA 2008 Undetermined

I020459

- 001 PLANTS

- WA 2000 Undetermined

I020459

- 003 PLANTS

- WA 2000 Undetermined

I020459

- 005 PLANTS

- WA 1999 Undetermined43 Incident ID Type Total Magnitude State Year Legality

I020459

- 008 PLANTS

- WA 1999 Undetermined

I020459

- 011 TERRESTRIAL

- WA 2000 Undetermined

I020459

- 012 PLANTS

- WA 2000 Undetermined

I021457

- 014 PLANTS $1,000.00 WA 2006 Undetermined

I021457

- 016 PLANTS 3 plant crops WA 2006 Undetermined

I021457

- 025 PLANTS

- WA 2006 Undetermined

I022180

- 001 PLANTS “ A few ”

trees NV 2010 Undetermined44 Appendix 5 : SIP (v1.0) Input and Output Data

Table 5

- 1 : Inputs
Parameter Value Chemical name Diuron Solubility (in water at 25 o C; mg/L) 42

Mammalian LD 50 (mg/kg

- bw) 5000 Mammalian test species laboratory rat Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg

- bw) 12.5 Mammalian test species laboratory rat Body weight (g) of "other" mammalian species

Avian LD 50 (mg/kg

- bw) 2000 Avian test species mallard duck Body weight (g) of "other" avian species Mineau scaling factor 1.15

Mallard NOAEC (mg/kg

- diet) 9.8 Bobwhite quail NOAEC (mg/kg

- diet) 0 NOAEC (mg/kg

- diet) for other bird species Body weight (g) of other avian species NOAEC (mg/kg

- diet) for 2nd other bird species Body weight (g) of 2nd other avian species

Table 5

- 2 : Mammalian Results
Parameter Acute Chronic Upper bound exposure (mg/kg

- bw) 7.2240 7.2240 Adjusted toxicity value (mg/kg

- bw) 3845.8028 9.6145 Ratio of exposure to toxicity 0.0019 0.7514

Conclusion* Drinking water exposure alone is NOT a potential

concern for mammals Drinking water exposure alone is NOT a potential

concern for mammals

Table 5

- 3 : Avian Results
Parameter Acute Chronic Upper bound exposure (mg/kg

- bw) 34.0200 34.0200 Adjusted toxicity value (mg/kg

- bw) 1038.4508 0.4862 Ratio of exposure to acute toxicity 0.0328 69.9708

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

*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.45 Appendix 6 : STIR (v.1) Inputs and Outputs



### Input
Application and Chemical Information

Enter Chemical Name Diuron
Enter Chemical Use Herbicide Is the Application a Spray? (enter y or n) y If Spray What Type (enter ground or air) air Enter Chemical Molecular Weight (g/mole) 233.1 Enter Chemical Vapor Pressure (mmHg) 6.90E

- 08 Enter Application Rate (lb ai/ acre) 12
Toxicity Properties

**Bird**

Enter Lowest Bird Oral LD 50 (mg/kg bw) 2000 Enter Mineau Scaling Factor 1.15 Enter Tested Bird Weight (kg) 1.58
**Mammal**

Enter Lowest Rat Oral LD 50 (mg/kg bw) 5000

Enter Lowest Rat Inhalation LC 50 (mg/L) 2.09 Duration of Rat Inhalation Study (hrs) 4 Enter Rat Weight (kg) 0.35



### Output Results Avian (0.020 kg ) Maximum Vapor Concentration in Air at Saturation (mg/m 3 ) 8.66E

- 04
Maximum 1

- hour Vapor Inhalation Dose (mg/kg) 1.09E

- 04
Adjusted Inhalation LD 50 3.36E+00

Ratio of Vapor Dose to Adjusted Inhalation LD 50 3.24E

- 05 Exposure not Likely Significant
Maximum Post

- treatment Spray Inhalation Dose (mg/kg) 1.15E+00 Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD 50 3.43E

- 01 Proceed to Refinements

Results Mammalian (0.015 kg ) Maximum Vapor Concentration in Air at Saturation (mg/m 3 ) 8.66E

- 04
Maximum 1

- hour Vapor Inhalation Dose (mg/kg) 1.37E

- 04
Adjusted Inhalation LD 50 1.24E+02

Ratio of Vapor Dose to Adjusted Inhalation LD 50 1.10E

- 06 Exposure not Likely Significant
Maximum Post

- treatment Spray Inhalation Dose (mg/kg) 1.45E+00 Ratio of Droplet Inhalation Dose to Adjusted Inhalation
LD 50 1.16E

- 02 Exposure not Likely Significant