1

OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

PC Code: 128976/138976 

DP Barcode: 428793 

Date: December 15, 2015

MEMORANDUM 

Subject Problem Formulation for the Ecological Risk and Drinking Water Exposure 

Assessments to be Conducted for the Registration Review of Uniconazole 

and Uniconazole-P. 

To: Sue Bartow, Chemical Review Manager 

 Cathryn Britton, Team Leader 

Kevin Costello, Branch Chief 

Risk Management and Implementation Branch IV 

Pesticide Re-evaluation Division

Through: Dana Spatz, Branch Chief

 Environmental Risk Branch III

Environmental Fate and Effects Division

From: James K. Wolf, Ph.D., Soil Physicist 

 Frank Farruggia, Ph.D., Biologist 

 Rosanna Louie-Juzwiak, RAPL 

 Environmental Risk Branch III 

 Environmental Fate and Effects Division

Peer Review: James Hetrick Ph.D., Senior Advisor 

 Environmental Risk Branch III 

Environmental Fate and Effects Division

Executive Summary 

The Environmental Fate and Effects Division (EFED) has completed the preliminary problem 

formulation for the ecological risk and drinking water exposure assessments to be conducted as 

JAMES WOLF

Digitally signed by JAMES WOLF 

DN: c=US, o=U.S. Government, 

ou=USEPA, ou=Staff, cn=JAMES 

WOLF, dnQualifier=0000014028 

Date: 2015.12.15 14:12:13 -05'00'

JAMES 

HETRICK

Digitally signed by JAMES HETRICK 

DN: c=US, o=U.S. Government, 

ou=USEPA, ou=Staff, cn=JAMES 

HETRICK, dnQualifier=0000005599 

Date: 2015.12.15 14:49:05 -05'00'

FRANK 

FARRUGGIA

Digitally signed by FRANK FARRUGGIA 

DN: c=US, o=U.S. Government, 

ou=USEPA, ou=Staff, cn=FRANK 

FARRUGGIA, dnQualifier=0000048865 

Date: 2015.12.15 14:57:13 -05'00'
2

part of the Registration Review of the plant growth regulators uniconazole and uniconazole-P.1

Uniconazole is racemic and is a mixture of 4 isomers. Uniconazole-P is the resolved form of 

uniconazole2, where 3 of the 4 isomers (that have less herbicidal activity) remain at lower 

percentages. To date, the submitted ecotoxicity and fate data appear to have been conducted 

using the resolved form (i.e., uniconazole-P)3, 4. Currently, there are only uniconazole-Pcontaining registered products. In this document, the focus will solely be on uniconazole-P as 

the stressor of concern. 

Uniconazole-P is used as a growth retardant on a wide variety of ornamental and fruiting 

vegetable crops intended for the retail market5. The two uniconazole-P end-use products are 

predominantly applied in commercial greenhouses (indoor only); however, one product label 

includes use in shade houses and lath houses, which may lead to some outdoor exposures. 

EFED previously conducted an ecological assessment for the addition of shade houses and lath 

houses, which identified a number of studies that would be needed to assess potential risk to 

nontarget organisms (i.e., terrestrial and aquatic plants). Additionally, consistent with the 

Guidance for Assessing Pesticide Risks to Bees (U.S. EPA, et. al., 2014), honey bee toxicity and 

exposure data would be needed in order to conduct a risk assessment for pollinators. Below is 

the list of guideline studies that were identified as being needed in order to assess the outdoor 

uses of uniconazole-P: 

- 850.4100, Seedling Emergence and Seedling Growth (TEP)

- 850.4150, Vegetative Vigor (TEP) 

- 850.4400, Aquatic plant Toxicity Test using Lemna (TGAI)

- 850.4500, Algal toxicity (TGAI)

- 850.4550, Cyanobacteria toxicity (TGAI)

- 850.3020, Adult Honey Bee Acute Contact Toxicity Test (Tier 1) (TGAI)

- 850.3030, Honey bee toxicity of residues on foliage (Tier 1) (TEP)

- OECD 237, Adult Honey Bee Acute Oral Toxicity Test (Tier 1) (TGAI)

- Non-guideline, Adult Honey Bee Chronic Oral Toxicity Test (Tier 1) (TGAI)

- Non-guideline, Larvae Honey Bee Acute Oral Toxicity Test (Tier 1) (TGAI)

- Non-guideline, Larvae Honey Bee Chronic Oral Toxicity Test (Tier 1) (TGAI)

- OECD 75, Semi-field Testing for Pollinators (Tier 2) (TEP)

- Non-guideline, Field Trial of Residues in Pollen and Nectar (TEP) 

1

 Resolved uniconazole-P CAS No 83657-17-4 

2

 Racemic uniconazole CAS. No. 83657-22-1 

3

 Odenkirchen, E. Registration 62097-RL – Uniconazole-P Technical; Request for Determination of the Similarity 

Between Product 62097-RL to Valent Product 59639-38 for Environmental Data Bridging Purposes; Request for 

Sufficiency of Cited Studies for Data Requirements. December 14, 2005. 4

 Regelman, E. EFGWB Review of Uniconazole, Response to Registration Standard (Clarification of Sign of Rotation 

of Active Ingredient; Clarification of Chemical Abstracts Registry Numbers. November 19, 1990. 5

 According to registrant correspondence received on Nov. 19, 2015. 
3

- 850.3040, Field Testing for Pollinators (Tier 3) (TEP) 

OPP recently received a draft revised label6 that would limit foliar spray applications of 

uniconazole-P to greenhouse (indoor) use only, to minimize potential drift from foliar sprays 

from applications made in shade houses or lath houses. If this draft label were to be approved, 

then the vegetative vigor toxicity (GL. 850. 4150) would not be needed. 

The following discussion is a summary of the currently registered uses as labeled, the available 

environmental fate and ecological toxicity data and data uncertainties, and the problem 

formulation to support the conduct of an exposure and risk assessment for outdoor uses. 

Chemical Overview 

Use Characterization 

Uniconazole-P reduces plant height by reducing internode elongation through inhibition of 

gibberellin biosynthesis. Uniconazole-P is registered for use in commercial greenhouses, shade 

houses and lath houses on a variety of ornamentals, as well as the following food crops: 

eggplant, groundcherry, pepino, pepper, tomatillo, and tomato. Uniconazole-P may be applied 

as a pre-plant application to soil surface, drench application, a pre-plant bulb soak or foliar 

application using standard spray equipment. 

There are four Section 3 products (two technical and two end-use products) and one Section 

24c product registered for uniconazole-P. The end-use labels (i.e., EPA Reg. Nos. 59639-37; 

62097-18) indicate that multiple applications can be used. The maximum number of 

applications per year and maximum application rate per year are not specified. Application 

rates depend on the desired plant height, duration and degree of control, pot size, stage of 

growth, method of application, season, and cultivar response. Cultural practices such as 

watering, potting media, fertilization, temperature, and light conditions may affect the growth 

response to a given dosage. 

Summary of Previous Risk Assessments 

Based on a previous risk assessment (U.S. EPA, 20087) in support of the proposed addition of 

shade houses and lath house uses to the Sumagic product label (EPA Reg. No. 59639-37, Valent 

Corporation), potential acute risks to fish, aquatic invertebrates, birds, and mammals are 

6

 Email received on November 30, 2015, with draft label from OPP/PRD, S. Bartow. 

7 Anderson, B. and M. Corbin. 2008. Transmittal of the Environmental Fate and Effects Division (EFED) Section 3 Ecological Risk 

Assessment of Uniconazole Proposed for New Uses in Fruiting Vegetables, Bedding Plants, Bulb Crops, and Ornamental Plants in 

Greenhouses, Shade houses, and Lath-houses (D349381+; 04/10/08).
4

expected to be lower than concern levels. However, levels of concern (LOC) were exceeded for 

reproductive risk to birds and mammals for the highest assessed application rate (0.09 lb 

a.i./Acre). EFED concluded that a reduction of the maximum application rate to 0.07 lb a.i./A 

would result in no LOC exceedance for birds or mammals. 

Uniconazole-P use in shade houses and lath-houses may result in exposure to non-target 

aquatic and terrestrial plants and animals through dietary or contact exposure, resulting from 

direct spray, residues on food items, or from runoff and/or spray drift to adjacent areas. Use of 

uniconazole-P in greenhouse facilities is likely to reduce environmental exposures, assuming 

that runoff from indoor treatments is controlled. 

No toxicity studies are available that allow for an estimation of chronic risk to fish or aquatic 

invertebrates, saltwater organisms, aquatic plants, or terrestrial plants. However, potential risks 

to freshwater or saltwater organisms from chronic exposure to uniconazole-P were not 

anticipated given that new endpoints would need to be significantly more sensitive (e.g., at 

least 3,000 times) than the available acute toxicity data, to result in an exceedance of the LOC. 

Risk to terrestrial and aquatic plants was noted as a potential risk concern because incidents 

have been reported in the EIIS that correlate uniconazole-P application to plant damage. Also, 

since uniconazole-P is a plant growth regulator, it is expected that exposed non-target plants 

would be affected. As such, the following data were conditionally required to support the 

addition of the proposed outdoor uses onto the product label: seedling emergence and 

seedling growth study (OCSPP GL. 850.4100), vegetative vigor study (OCSPP GL. 850.4150; Tier I 

aquatic plant growth studies (850.4400, 850.4500); and, honey bee acute contact study (OCSPP 

GL. 850.3020). In 2011, EPA evaluated and granted a data waiver request to Valent Corporation 

for the submission of these studies (DP Barcode D385384) based on the removal of the shade 

house uses from their labels. 

Environmental Fate and Transport Summary 

Uniconazole-P (and uniconazole) is a triazole which contains a double bond and one chiral 

center. Four isomers are possible with uniconazole-P (two geometrical isomers, E and Z, each 

with two optical isomers, R and S due to the chiral center) (Appendix A). Uniconazole is racemic 

and is a mixture of 4 isomers. Uniconazole-P is the resolved form of uniconazole8, and is the 

form used in registered products. 

The dominant dissipation mechanisms for uniconazole are leaching, plant uptake, and to a 

lesser extent microbial degradation. Uniconazole is stable to hydrolysis and persistent to 

8

 Racemic uniconazole CAS. No. 83657-22-1 
5

degradation in aerobic terrestrial systems. There are no data on degradation in aerobic aquatic 

or anaerobic aquatic environments, nor are there any field dissipation studies. The physical and 

chemical properties that determine the fate and transport are detailed in Table 1. Available 

environmental fate data include hydrolysis, aerobic soil metabolism, batch equilibrium studies 

(adsorption/desorption data), and volatility from soil surface. 

Table 1. Chemical Properties and Environmental Fate Parameters of Uniconazole-P (and Uniconazole).

Chemical/Fate Parameter Value Description/Comments Source (MRID)

Selected Physical/Chemical Parameters 

Company Code 3307D, XE-1019L - - 

Common Name Uniconazole Plant Growth Regulators - 

SMILES Notation 

Canonical 

Isomeric

Uniconazole-P: 

CC(C)(C)C(C(=CC1=CC=C(C=C1)Cl)N2C=NC=N2)O

CC(C)(C)[C@@H](/C(=C\C1=CC=C(C=C1)Cl)/N2C=NC=N2)O 

Molecular formula C15H18N3OCl - 46657801 

Molecular mass 291.78 g/mole - 46657801 

Vapor pressure (20qC) 4.0 x 10-5 mm Hg (S)-(E)-isomer 40820501 

Water solubility (25qC) 8.41 mg/L (S)-(E)-isomer 40820501 

Hertsb

Octanol-water partition 

coefficient (Log KOW) 

3.77 

3.84c

(TGAI) 

Temperature unspecified 

(S)-(E)-isomer 

Hertsb

Henry’s Law Constant (25°C) 1.83 x 10-6 atm-m3/mole Calculated - 

Persistence 

Hydrolysis half-life (days; 25qC) Stable @ pH 5, 7, 9 40345427 

40573601 

Aerobic soil metabolism halflife (25°C) 857 to 1,880 daysa The (S)-(E)-isomer 

[the active isomer] 

40345428 

40573602 

Volatilization from Soil Surface 

[Guideline # 163-2] 

0.012 to 0.014 % of applied 

radioactivity 

(S)-(E)-isomer 

Required for greenhouse use. 40462604 

Vapor-Phase Photodegradation 

half-life 32.5 days 

Uniconazole 

Artificial light 1⁄4 to 1⁄2 the 

intensity of sunlight 

40820501 

40462604 

Mobility 

Soil-water partition coefficients 

(KF) 

[Freundlich] (mL/g) 

0.20 to 48.6 

Average = 18.6 

The (S)-(E)-isomer 

[the active isomer] 

40345429 

40573602 

40724301 
6

Chemical/Fate Parameter Value Description/Comments Source (MRID)

Organic carbon-normalized soil 

partition coefficients (KFOC) 

(mL/goc) 

137 to 636 

Average = 371 

The (S)-(E)-isomer 

[the active isomer] 

40345429 

40573602 

40724301 

Bioconcentration Factor in Fish 

Fish bioconcentration factors 

(steady-state) 

35X, 75X, 99X for fillet, 

whole fish and viscera, 

respectively 

- 40657901 

a Half-lives estimated [Slow t1⁄2 Model] with PestDF9 following NAFTA Guidance10. 

b http://sitem.herts.ac.uk/aeru/ppdb/en/Reports/675.htm#none 

Uniconazole is a triazole fungicide. Several of the triazole class fungicides have been 

documented to degrade to 1,2,4-triazole; however, 1,2,4-triazole was not detected in any of 

the environmental fate studies. Several identified degradates (i.e., 7KE, 7KZ, 7SA, 7SK, and 7EP) 

were detected at percentages of applied less than 5% (Appendix A). These degradates have not 

been previously identified as being a concern for toxicity and have not been included in this 

assessment. 

Exposure Pathways 

For terrestrial vertebrates, the major routes of exposure to uniconazole-P are considered to be 

via contact exposure and dietary ingestion of food items such as plants and/or animals that 

have uniconazole-P residues as a result of direct application, spray drift, and/or runoff. 

Exposure to terrestrial vertebrates through inhalation is considered unlikely given uniconazoleP’s low vapor pressure. The lowest rat inhalation endpoint is non-definitive (LC50 > 2.75 mg/L; 

MRID 40345409); even if using this as a definitive value, the results from the Screening Tool for 

Inhalation Risk (STIR v. 1.0) indicate that inhalation is not expected to be an exposure route of 

concern. The Screening Imbibition Program (SIP v. 1.0) suggests that drinking water alone is not 

expected to be an exposure pathway of concern for acute and chronic exposure to mammals, 

and for acute exposures to birds. However, chronic exposure to contaminated drinking water 

alone may be a potential exposure route of concern for birds (Appendix B). 

 

9 http://www.epa.gov/oppefed1/ecorisk_ders/degradation_kinetics/NAFTA_Degradation_Kinetics_Equations.htm

10 http://www.epa.gov/oppefed1/ecorisk_ders/degradation_kinetics/archive2015/ftt_sop_using_nafta_guidance.pdf
7

Stressor of Concern 

The stressor of concern for terrestrial and aquatic organisms is the parent uniconazole-P. 

The concentrations of degradate compounds are unlikely to be greater than the parent, as 

parent is assumed to be persistent. Therefore, any potential risk posed by degradates is 

expected to be inconsequential in comparison to the parent. 

Measures of Exposure 

To estimate risks to aquatic and terrestrial organisms from exposure to uniconazole-P, all 

exposure modeling and resulting risk conclusions will be made based on maximum application 

rates, application methods, and any mitigation measures indicated on the label or formally 

agreed to by registrants prior to the conduct of the risk assessments. Exposure modeling (e.g., 

Surface Water Concentration Calculator) for uniconazole-P at maximum treatment levels, rates 

in the lath house or shade houses (i.e., based upon concentration per 100 ft2) and an upperbound estimated exposure rate (i.e., based upon the number of plants/A) will be used for 

aquatic estimated environmental concentrations (EEC). Models that will be used to predict 

estimated environmental concentrations (EECs) of uniconazole-P are discussed on EPA’s model 

website. These models include: SWCC, PRZM-GW, T-REX, and TerrPlant. 

The Agency is not aware of surface water or groundwater monitoring conducted by federal or 

state agencies. However, if monitoring data of uniconazole or uniconazole-p becomes available, 

they will be considered in the assessment. 

An updated drinking water assessment (DWA) is not anticipated to be needed at this time; 

however, if one is needed, an updated exposure assessment will incorporate the current water 

exposure models (e.g., SWCC and PRZM-GW) and guidance for model input parameters. 

Measure of Effects 

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

receptors. Data are typically obtained from registrant-submitted studies or from literature, 

including studies housed in ECOTOX. ECOTOX is a source for locating single chemical toxicity 

data and potential chemical mixture toxicity data for aquatic life, terrestrial plants, and wildlife. 

ECOTOX was created and is maintained by the USEPA, Office of Research and Development, 

and the National Health and Environmental Effects Research Laboratory's Mid-Continent 

Ecology Division. 
8

Table 2 and Table 3 are summaries of the available ecotoxicity data submitted by the 

registrant. 

Table 2. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for Uniconazole-P 

Test Type Endpoint Comments MRID 

Laboratory rat 

Rattus norvegicus

LD50 = 430 mg/kgbw Acceptable 40345405 

Laboratory rat 

Rattus norvegicus

NOAEC = 150 ppm 

(7.5 mg/kg-bw) Acceptable 41162004 

Northern Bobwhite Quail 

(Colinus virginianus) 

LD50 = 1461 mg/kgbw Acceptable 40345419 

Mallard Duck 

Anas platyrhynchos LC50 = 3442 ppm Acceptable 40345420 

Northern Bobwhite Quail 

(Colinus virginianus) NOAEL = 20 ppm 

Supplemental study in quail. 

Reproduction NOAEC in mallard 

ducks was 20 ppm. LOAEC was 80 

ppm based on increased incidence of 

cracked eggs. 

40936007 

Honey Bee Acute Contact None Invalid study 40345426 

Table 3. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for Uniconazole-P. 

Test Type Endpoint Comments MRID 

Acute Freshwater Fish 6.8 mg/L 

Acceptable study in bluegill. Rainbow

trout and carp LC50s were 14.8 mg/L

and 7.5 mg/L, respectively. 

40345423 

Acute Freshwater Invertebrate 

Daphnia magna EC50

>10 mg/L 

Supplemental study because test 

concentrations did not reach the limit

concentration and 50% inhibition was

not achieved. Irregular swimming

occurred at 10 mg/L. 

40345425 

 
9

Integration of Exposure and Effects 

Risk characterization is the integration of exposure and ecological effects to determine the 

potential ecological risk from the use of pesticides and the likelihood of direct and indirect 

effects to non-target organisms in aquatic and terrestrial habitats. For the assessment of risks, 

the risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs 

are divided by acute and chronic toxicity values. The resulting RQs are then compared to the 

Agency’s Levels of Concern (LOCs). These criteria will be used to indicate when uniconazole-P 

use, as directed on the label, has the potential to cause adverse direct or indirect effects to 

non-target organisms. In addition, any additional incident data from the Ecological Incident 

Information System v. 2.1.1 (EIIS), maintained by EFED; 2) the Avian Incident Monitoring System 

(AIMS), maintained by the American Bird Conservancy; and, 3) the Incident Data System (IDS) 

maintained by OPP will be considered as part of the risk characterization. 

Incident Information 

Three incidents reported in EIIS involving uniconazole-P have been reported, all of which 

involve damage to terrestrial plants (petunias or oak trees). In all cases uniconazole-P was 

applied directly to the damaged plants. The certainty index for these uses was probable or 

possible. Table 4 summarizes the available incidents. 

Table 4. Summary of Incidents Reported for Uniconazole-P in EIIS. 

Incident No. Product Species Affected Description of Effects Certainty Index 

I007467-023 Sumagic Petunia

Spots on leaves and

scarring on stem

tissues

Possible

I007467-24 Sumagic Petunia Blisters and Leaf spots Possible 

I002969-057 Prunit Oak Unspecified damage Probable

Endocrine Disruptor Screening Program (EDSP) 

Uniconazole-P was not included in the first group of 67 chemicals issued an order to conduct 

Tier 1 EDSP testing. Tier 1 screening results for List 1 chemicals are available at 

http://www2.epa.gov/ingredients-used-pesticide-products/endocrine-disruptor-screeningprogram-tier-1-assessments. For additional information on the EDSP, visit 

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

Endangered Species

Consistent 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 developed 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 outlines 

recommendations on specific scientific and technical issues related to the development of 

pesticide risk assessments that EPA and the Services must conduct in connection with their 

obligations under the ESA and FIFRA. EPA will address concerns specific to uniconazole-P in 

connection with the development of its final registration review decision for uniconazole-P. 

 

In November 2013, EPA, the U.S. Fish and Wildlife Service, National Marine Fisheries (the 

Services), and USDA released a white paper containing a summary of their joint Interim 

Approaches for assessing risks to listed species 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 Sciences April 2013 Report. 

 

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 the Preliminary 

Work Plan for uniconazole-P 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 develop a common method for ESA 

analysis, the planned risk assessment for the registration review of uniconazole-P will describe 

the level of ESA analysis completed for this particular registration review case. This assessment 

will allow EPA to focus its future evaluations 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 the agencies have fully developed and implemented the scientific methods 

necessary to complete risk assessments for listed species and their designated critical habitats, 

these methods will be applied to subsequent analyses of uniconazole-P as part of completing 

this registration review. 
11

Preliminary Identification of Data Gaps 

The following sections identify data that are needed to complete an ecological risk assessment 

in support of the Registration Review of the registered uses of uniconazole-P. 

Environmental Fate and Transport 

Table 5 identifies the environmental fate studies submitted by the registrant, as well as study 

classifications and whether or not additional data are needed in order to support the 

registration review exposure assessments. It was not possible to confirm that the test material 

in the environmental fate studies was uniconazole-P (see footnote in Table 5 and Appendix A). 

However, there are sufficient environmental fate data to conduct an exposure assessment for 

the existing uses, if needed. 

Table 5. Environmental Fate Data for Uniconazole-Pa.

OCSPP 

Guideline Data Requirement MRID Study Classification 

Are Data 

Needed to 

Conduct Risk 

Assessment 

835.2120 Hydrolysis 40345427 

40573601 Acceptable No 

835.2370 Aqueous Photolysis  ̄ - No 

No studies are currently available. In 

the absence of empirical data, 

stability was assumed. In order to 

assess outdoor uses, the submission 

of these data would help to address 

uncertainty with assumed stability.

835.2410 Soil Photolysis - No 

In the absence of empirical data, 

stability was assumed. In order to 

assess outdoor uses, the submission 

of these data would help to address 

uncertainty with assumed stability.

835.4100 Aerobic Soil Metabolism 40345428 

40573602 Acceptable No 

835.4200 Anaerobic Soil 

Metabolism - - No 

No studies are currently available. 

This study is useful for 

characterization but is not a model 

input for Tier I exposure assessments. 

835.4300 Aerobic Aquatic 

Metabolism  ̄ - No 

In the absence of empirical data, 

stability was assumed. In order to 

assess outdoor uses, the submission 

of these data would help to address 

uncertainty with assumed stability.
12

OCSPP 

Guideline Data Requirement MRID Study Classification 

Are Data 

Needed to 

Conduct Risk 

Assessment 

835.4400 Anaerobic Aquatic 

Metabolism  ̄ - No 

No studies are currently available. 

This study is useful for 

characterization but is not a model 

input for Tier I exposure assessments. 

835-2370 Vapor-Phase 

Photodegradation 

40820501 

40462604 Acceptable No -- 

835.1230 Adsorption/Desorption 

(Batch Equilibrium) 

40345429 

40573602 

40724301 

Acceptable No -- 

835.6100 Aquatic Field Dissipation - - No -- 

835.6100 Terrestrial Field 

Dissipation - - No 

No studies are currently available. In 

the absence of empirical data, 

stability was assumed. In order to 

assess outdoor uses, the submission 

of these data would help to 

characterize uniconazole-P’s fate in 

the environment.

835.1730 Bioaccumulation in Fish 40657901 Acceptable No -- 

a

 The studies identified the test material as S-3307D; however, S-3307D has referenced as both uniconazole and 

uniconazole-P, additionally the CAS # of have been used interchangeably. Study introductions suggest the test 

material was uniconazole-P (CAS No. 83567-17-4).

Effects 

The ecological effects database is incomplete for the risk assessment to support outdoor uses. 

Table 6 and Table 7 identify the ecological effects studies, as well as study classifications and 

whether or not further data are needed in order to support the risk assessment for all currently 

registered uses of uniconazole. 

Table 6. Submitted Aquatic Ecological Effects Data for Uniconazole-P 

OCSPP 

Guideline Data Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed to 

conduct risk 

assessment? 

Comments 

 850.1010 

Freshwater 

invertebrate 

acute toxicity 

40345425 Supplemental No 
13

OCSPP 

Guideline Data Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed to 

conduct risk 

assessment? 

Comments 

850.1025 

850.1035 

850.1045 

850.1055 

Saltwater 

invertebrate 

acute toxicity 

No study 

submitted No 

Saltwater fish and invertebrates 

would need to be 

approximately 200-fold or 300-

fold, respectively, more 

sensitive than freshwater 

organisms on an acute basis to 

result in LOC exceedances 

850.1075 Freshwater fish 

acute toxicity 

40345423 Acceptable 

40345422 Acceptable No -- 

40345424 Supplemental 

 850.1075 Saltwater fish 

acute toxicity 

No study 

submitted -- No 

Saltwater fish and invertebrates 

would need to be 

approximately 200-fold or 300-

fold, respectively, more 

sensitive than freshwater 

organisms on an acute basis to 

result in LOC exceedances 

 850.1300 

Freshwater 

invertebrate 

life cycle 

No study 

submitted -- No 

Uniconazole-P is expected to be 

persistent in the aquatic 

environment. However; the 

chronic NOAEC would need to 

be approximately 5000-fold 

lower than the acute EC50 to 

result in LOC exceedances for 

the registered uses. 

 850.1350 

Saltwater 

invertebrates 

life cycle 

No study 

submitted -- No 

Potential acute risks to 

freshwater invertebrates were 

considerably lower than 

concern levels, and potential 

risks from chronic exposure to 

uniconazole-P were presumably 

lower than concern levels. 

 850.1400 Freshwater fish 

early-life stage

No study 

submitted -- No -- 
14

OCSPP 

Guideline Data Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed to 

conduct risk 

assessment? 

Comments 

 850.1400 Saltwater fish 

early-life stage 

No study 

submitted -- No -- 

 850.1500 Fish life cycle No study 

submitted -- No 

The life-cycle NOAEC would 

need to be approximately 3700 

fold lower than the acute LC50 

to result in LOC exceedances. 

850.4400 

Aquatic plant 

growth: 

Tier II vascular 

plants 

No study 

submitted -- Yes 

Needed to assess risk from 

shade house or other outdoor 

uses; no data needed for indoor 

uses 

850.4500 

Aquatic Plant 

Growth: 

Tier II Algal 

Toxicity 

No study 

submitted 

 

-- Yes 

Needed to assess risk from 

shade house or other outdoor 

uses; no data needed for indoor 

uses 

850.4550 

Aquatic Plant 

Growth: 

Tier II 

Cyanobacteria 

Toxicity 

No study 

submitted -- Yes 

Needed to assess risk from 

shade house or other outdoor 

uses; no data needed for indoor 

uses 

Table 7. Submitted Terrestrial Ecological Effects Data for Uniconazole-P 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed for 

risk 

assessment? 

Comments 

 850.2100 Avian oral 

toxicity 

40345418 Acceptable 

No 

Acute avian oral toxicity studies 

using mallard duck and 

bobwhite quail are available. 

Although data are not available 

for a passerine species, based 

on existing information, it is not 

expected that a passerine study 

would add any valuable 

information to the avian risk 

assessment. 

40345419 Acceptable 

 850.2200 Avian dietary 

toxicity 

40345420 Acceptable 

No -- 

40345421 Acceptable 
15

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed for 

risk 

assessment? 

Comments 

850.2300 Avian 

reproduction 

40936007/

43634301 Supplemental/ 

No -- 

40936009/

43634302 Supplemental/ 

850.3020 

Honey bee 

acute contact 

toxicity 

40345426 Invalid Yes 

Needed to assess risk from 

shade house or other outdoor 

uses; no data needed for indoor 

uses 

NonGuideline 

Study 

(Tier I) 

Honey bee 

adult acute 

oral toxicity 

No study 

submitted -- Yes 

Needed to assess risk from 

shade house or other outdoor 

uses; no data needed for indoor 

uses 

NonGuideline 

Study 

(Tier I) 

Honey bee 

larvae acute 

oral toxicity 

No study 

submitted -- Yes 

Needed to assess risk from 

shade house or other outdoor 

uses; no data needed for indoor 

uses 

NonGuideline 

Study 

(Tier I) 

Honeybee 

adult chronic 

oral toxicity 

No study 

submitted -- Yes 

Needed to assess risk from 

shade house or other outdoor 

uses; no data needed for indoor 

uses 

NonGuideline 

Study 

(Tier I) 

Honey bee 

larvae chronic 

oral toxicity 

No study 

submitted -- Yes 

Needed to assess risk from 

shade house or other outdoor 

uses; no data needed for indoor 

uses 

850.3030 

Honey bee 

toxicity of 

residues on 

foliage 

No study 

submitted Yes Dependent on Tier I results 

NonGuideline 

Study 

(Tier II) 

Semi-field 

testing for 

pollinators 

(tunnel or 

colony feeding 

studies) 

No study 

submitted 

-- Yes Dependent on Tier I results 

NonGuideline 

Study 

(Tier II) 

Field trial of 

residues in 

pollen and 

nectar 

No study 

submitted -- Yes Dependent on Tier I results 
16

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed for 

risk 

assessment? 

Comments 

850.3040 

(Tier III) 

Field testing 

for pollinators 

No study 

submitted -- Yes Dependent on Tier I results 

850.4100 

Terrestrial 

plant toxicity: 

Tier II seedling 

emergence 

No study 

submitted -- Yes 

Needed to assess risk from 

shade house or other outdoor 

uses; no data needed for indoor 

uses 

850.4150 

Terrestrial 

plant toxicity: 

Tier II 

vegetative 

vigor 

No study 

submitted -- Yes 

Needed to assess risk from 

shade house or other outdoor 

uses; no data needed for indoor 

uses 
17

APPENDIX A. 

Summary of Fate Data 

The chemical structures of the four uniconazole-P isomers along with the chemical 

nomenclature are given in Table A-1. Uniconazole-P is the resolved form of uniconazole (a 

process to increase the percent of most active isomer [(S)-(E)-isomer] with the other three 

isomers occurring as lower percentages. Among the four isomers the (S)-(E)-isomer [or (E)-(S)-

isomer] has the highest biological activity which is derived from the ability of inhibiting 

biosynthesis of gibberellin, and is a major ingredient of the plant growth retardant uniconazoleP. There is some uncertainty concerning the whether uniconazole (racemic) or uniconazole-P 

(resolved form) was used as the test material (specified on as S-3307D) in the environmental 

fates studies as there was some inconsistency in the use of the CAS Number (83657-22-1 or 

83657-17-4) and Company ID (S-3307D), and name (uniconazole or uniconazole-P) between 

study reports and literature. The specific study introductions did suggest that the test material 

was the resolved uniconazole-P. 

 Abbreviationa

 Chemical Namea Synonym 

Used by Registrant Nomenclature Used by Registrant 

(S)-(E)-isomerb (S)-E-1(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (E)-(S)-isomer

(R)-(E)-isomer (R)-E-1(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (E)-(R)-isomer 

(S)-(Z-isomer (S)-Z-1(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (Z)-(S)-isomer

(R)-(Z)-isomer (R)-Z-1(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (Z)-(R)-isomer a Nomenclature used by Registrant Submissions. 

b Most active isomer. 

Table A-1. Structures and Chemical Names for the Four Isomers of Uniconazole and Uniconazole-P.

Hydrolysis (MRID 40345427, 40573601) 

The S-E isomer showed no degradation at pH 5, 7, or 9. Estimated half-lives were beyond the 

duration of the study but suggest half-lives of at least one year. Studies also suggest that the 
18

other isomers exhibit similar hydrolytic half-lives. Trace amounts (<0.1% of applied 

radioactivity) of the Z-isomers were observed, with no tendency to increase with time. The 

parent compound is resistant to hydrolysis at pH 5, 7, and 9 (25°C, dark, sterile conditions) and 

that the E/Z isomerization and R/S epimerization did not occur under these conditions. 

Aerobic Soil Metabolism (40345428, 40573602) 

The half-lives for the (S)-(E)-isomer ranged from 857 to 1,880 days varied due to radiolabel 

location and soil type. Generally, the E-isomers had longer half-lives compared to the Z-isomers. 

The four isomers of uniconazole-P; E and the Z and the corresponding (R) and (S) were 

separately labeled in the phenyl (Ph-14C) and the 1,2,4-triazole (Trz-14C) rings and were 

aerobically incubated for a 12-month period in two soils. Several were unique to the E and Z 

isomers. For the (S)-(E)-isomer, the predominate degradation product was 1-(4-chlorophenyl)-

4,4-dimethyl-2-(1,2,4-triazole-1,2-epoxypentan-3-ol (7EP) (<1.5% of applied after 12 months). 

Between 2.4 and 5.4% CO2 evolved depending upon the soil. The bound residues increased with 

time (27 to 46% after 12 months). However, degradation half-lives varied by isomer and 

followed the order (R)-(Z) -> (S)-(Z) > (R)-(E) > (S)-(E) with corresponding half-lives of 3 to 4 days, 

300 to 500 days, 260 to 1,250 days, and 857 to 1,880 days, respectively. 

Transformation Products 

Uniconazole-P is a triazole fungicide, several of the triazole class fungicides have been 

documented to degrade to 1,2,4-triazole. However, 1,2,4-triazole was not detected in any of 

the environmental fate studies. Other degradates identified in environmental fate studies are E1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazole-1-yl)-1-pentene-3-one (7KE), Z-1-(4-

chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazole-1-yl)-1-pentene-3-one (7KZ), 1-(4-chlorophenyl)-

4,4-dimethyl-2-(1,2,4-triazole-1-yl)-pentan-3-ol (7SA), 1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-

triazole-1-yl)-pentan-3-one (7SK), 1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazole-1-yl)-1,2-

epoxypentan-3-ol (7EP), and CO2. All identified degradates were detected at percentages of 

applied less than 5%. These degradates have not been previously identified as being a concern 

for toxicity by HED and have not been included in exposure modeling. 

A proposed degradation pathways of the (E)- and (Z)-isomers of uniconazole (uniconazole-P) in 

aerobic soil is shown in Table A-2. 
19

Table A-2. Proposed degradation pathways of the (E)- and (Z)-isomers in aerobic soil (MRID 40345428).

Mobility (Sorption) 40345429, 40573602, 40724301) 

Adsorption of the (S)-(E) isomer appears to be somewhat dependent on the amount of soil 

organic matter (MRID 40345429, 40573602, 40724301, and 40728501) with KF ranging from 0.2 

to 45 and corresponding KFOCs ranging from 137 to 636. Subsequent analysis suggests a good 

correlation between KF and fraction of organic carbon (%OC)) with the exception of the Kodaira 

and Sapporo soils. Measured soil properties for these two soils suggest other factors that may 

influenced the sorption (KF) values. Both of these soils had the highest exchange acidity values 

(Table 3 MRID 40573602); the exchange acidity values were 53.9 (units not specified) and 35.0 

for the Kodaira and Sapporo soil, respectively. Soil pHs values were acidic, 4.4 and 5.3 Kodaira 

and Sapporo, respectively. 

Study authors reported that the Aichi and Muko soils did not adsorbed 30% of applied 14C as 

observed in the other soils (MRID 40724301). They suggest experimental error as the cause. 

However, these soils had the lowest organic carbon content (based upon organic matter) and 

high sand percentages which could also influence sorption capacity. 

The soil texture (i.e., particle size distribution) and cation exchange capacity (CEC) information 

submitted by the registrant (MRID 40573602) in order to compare Japanese soils to United 

States soils is not sufficient. Other factors such as parent material is equally important, for 

which there was no information submitted, may influence the sorption observed in these two 

soils. Japanese soils are much more likely to be formed in volcanic material compared to the 
20

United States. There is uncertainty about the representativeness of the parent material for all 

the soils used (mobility and aerobic soil metabolism) being representative of U.S. soils. 

Additionally, the units of measurement and what was included in the exchangeable acidity 

would be informative (it is assumed to be meq Fe+3 + Al+3/100 g). Specific information would 

include soil mineralogy (i.e., clay), soil parent material (i.e., volcanic), drainage class, and 

climate conditions (temperature and precipitation) would be informative to relate the Japanese 

soils used for the aerobic soil metabolism study and the soil sorption partition coefficients to 

U.S. soils. 

Volatilization of Uniconazole from Soil Surface 

The volatilization rate and air concentration of radioactivity (S)-(E)-isomer) on the first day were 

7.06 x 10-6 μg/cm2/hour and 7.14 x 10-2 μg/m3, respectively, and gradually decreasing with time. 

Uniconazole volatility from soil was low during a 30 day period; with 0.012% and 0.014% of the 

applied radioactivity volatilized from soil (MRID 40462604). The unchanged (S)-(E)-isomer was a 

main component of the radiocarbon in the extracts of soil and polyurethane foam plug. 

Vapor-Phase Photodegradation of Uniconazole 

The photodegradation half-life for uniconazole in air was 32.5 days (first-order rate constant) 

under artificial light artificial sunlight [24 hours exposure with a lamp with intensity 1⁄4 to 1⁄2 the 

intensity of sunlight (MRID 40820501). The degradation products identified after 31 days of 

exposure to light are summarized in Table A-3. 

Table A-3. Uniconazole Photodegradation Products (MRID 40820501). 

 % AR Abbreviation, Chemical Name 
21

APPENDIX B. 

Screening Imbibition Program Version 1.0 

Table 1. Inputs 

Parameter Value 

Chemical name Uniconazole-P 

Solubility (in water at 25oC; mg/L) 8.41 

 

Mammalian LD50 (mg/kg-bw) 430 

Mammalian test species laboratory rat 

Body weight (g) of "other" mammalian species 

 

Mammalian NOAEL (mg/kg-bw) 7.5 

Mammalian test species laboratory rat 

Body weight (g) of "other" mammalian species 

 

Avian LD50 (mg/kg-bw) 1461 

Avian test species mallard duck 

Body weight (g) of "other" avian species 

Mineau scaling factor 1.15 

 

Mallard NOAEC (mg/kg-diet) 80 

Bobwhite quail NOAEC (mg/kg-diet) 20 

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 2. Mammalian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 1.4465 1.4465 

Adjusted toxicity value (mg/kg-bw) 330.7390 5.7687 

Ratio of exposure to toxicity 0.0044 0.2508 

Conclusion* 

Drinking water exposure 

alone is NOT a potential 

concern for mammals 

Drinking water exposure 

alone is NOT a potential 

concern for mammals 

 
22

Table 3. Avian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 6.8121 6.8121 

Adjusted toxicity value (mg/kg-bw) 758.5883 2.1260 

Ratio of exposure to acute toxicity 0.0090 3.2042 

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. 

 

STIR Version 1.0 results 

Input

Application and Chemical Information

Enter Chemical Name Uniconazole-P

Enter Chemical Use

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) ground

Enter Chemical Molecular Weight (g/mole) 297.78

Enter Chemical Vapor Pressure (mmHg) 4.00E-05

Enter Application Rate (lb a.i./acre) 0.07

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 1461

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 0.178

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 430

Enter Lowest Rat Inhalation LC50 (mg/L) 2.75

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/m3) 6.41E-01

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 8.06E-02

Adjusted Inhalation LD50 5.21E+01
23

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.55E-03 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 7.40E-03

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 1.42E-04 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 6.41E-01

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 1.01E-01

Adjusted Inhalation LD50 1.64E+02

Ratio of Vapor Dose to Adjusted Inhalation LD50 6.19E-04 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 9.30E-03

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 5.68E-05 Exposure not Likely Significant