Page 1 of 56

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460 

OFFICE OF 

 CHEMICAL SAFETY AND

 POLLUTION PREVENTION

PC Code: 128997

 DP Barcode: D427434

 Date: November 24, 2015

MEMORANDUM

Subject: Registration Review – Preliminary Problem Formulation for Ecological Risk and 

Drinking Water Assessments for Tebuconazole

To: Jose Gayoso, Chemical Review Manager

Cathryn Britton, Team Leader

Kevin Costello, Branch Chief

Risk Management and Implementation Branch 2

Pesticide Re-evaluation Division (7508P)

Rachel Ricciardi, Chemical Review Manager 

Regulatory Management Branch II 

Antimicrobials Division (7510P)

From: Amy Blankinship, Senior Scientist

Ibrahim Abdel-Saheb, Environmental Scientist

Environmental Risk Branch 6

Environmental Fate and Effects Division (7507P)

James Breithaupt, Agronomist

 for Daniel Cherry, Biologist 

Siroos Mostaghimi, Ph.D., Senior Scientist 

Risk Assessment and Science Support Branch

Antimicrobials Division (7510P)

Reviewed: Nathan Miller, Biologist

William P. Eckel, Ph.D, Senior Science Advisor

Monica Wait, Risk Assessment Process Leader

Environmental Risk Branch 6

Environmental Fate and Effects Division (7507P)

Through: Mark Corbin, Branch Chief

Environmental Risk Branch 6

Environmental Fate and Effects Division (7507P)
Page 2 of 56

Laura Parsons, Associate Branch Chief

Risk Assessment and Science Support Branch

Antimicrobials Division (7510P)

The Environmental Fate and Effects Division (EFED) and Antimicrobials Division (AD) have

completed the preliminary problem formulation for the ecological risk and drinking water 

exposure assessments to be conducted as part of the Registration Review of the fungicide 

tebuconazole (PC Code 128997). This document is intended to provide an overview of what is 

currently known regarding the environmental fate and ecological effects associated with 

tebuconazole and its transformation/degradation products. It describes the preliminary ecological 

risk hypothesis and the processes that will be used during the completion of drinking water and 

ecological risk assessments in support of Registration Review. Tebuconazole is registered as a 

conventional pesticide with agricultural and non-agricultural use patterns and as an antimicrobial 

pesticide with uses such as above-ground and ground-contact wood and wood-based composites, 

and as a materials preservative in plastic, glues, adhesives, and metalworking fluids. 

Additional ecological effects and environmental fate data are requested to complete the risk 

assessment and registration review process for conventional tebuconazole uses. Toxicity data for

passerines, benthic invertebrates, aquatic nonvascular plants, honey bees, and multiple 

concentration (Tier II) seedling emergence and vegetative vigor terrestrial plant testing are 

requested to support conventional uses. Analytical methods in water and soil with LOQs less than 

toxicological levels of concern are also requested to support conventional uses.

Additional ecological effects data are requested to complete the risk assessment and registration 

review process for antimicrobial tebuconazole uses. Toxicity data for benthic invertebrates and 

aquatic nonvascular plants which are requested for the conventional uses will also be used to 

support antimicrobial uses. Additional environmental fate data to support a down the drain 

assessment are also requested for the antimicrobial uses which may result in down the drain 

exposures.
Page 3 of 56

Problem Formulation 

for the 

Ecological Risk and Drinking Water Assessments 

in Support of the 

Registration Review of Tebuconazole

 

[α-[2-(4-chlorophenyl)ethyl]-α-(1,1-dimethyl)-1H-1,2,4-triazole-1-ethanol]

CAS Registry No.: 107534-96-3

PC Code: 128997

Environmental Fate and Effects Division:

Environmental Risk Branch VI

Ibrahim Abdel-Saheb, Ph.D, Environmental Scientist

Amy Blankinship, Senior Scientist

Reviewed by:

Nathan Miller, Biologist

William P. Eckel, Ph.D, Senior Science Advisor 

Monica Wait, Risk Assessment Process Leader

Mark Corbin, Branch Chief

U. S. Environmental Protection Agency

Office of Pesticide Programs

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Antimicrobials Division:

Risk Assessment and Science Support 

Branch

James Breithaupt, Agronomist

Daniel Cherry, Biologist

Siroos Mostaghimi, Ph.D, Senior Scientist

Reviewed by:

Laura Parsons, Associate Branch Chief

N N

N

Cl C

H2

C

H2

OH

CH2

CH3

CH3

CH3
Page 4 of 56

Table of Contents

1. Executive Summary...................................................................................................................5

2. Introduction ...............................................................................................................................7

3. Use Characterization..................................................................................................................8

4. Conclusions from Previous Risk Assessments........................................................................14

5. Environmental Fate and Transport ..........................................................................................15

6. Receptors.................................................................................................................................22

7. Exposure Pathways of Concern...............................................................................................31

8. Analysis Plan ...........................................................................................................................32

8.1 Stressors of Concern.........................................................................................................32

8.2 Measures of Exposure ......................................................................................................33

8.3 Measures of Effect ...........................................................................................................34

9. Endangered Species Assessment.............................................................................................34

10. Endocrine Disruptor Screening Program.................................................................................35

11. Preliminary Identification of Data Gaps..................................................................................36

12. References................................................................................................................................47

Appendix A. Toxicity Data for Tebuconazole...........................................................................48

Appendix B. Screening Level Models to Evaluate Potential Importance of Drinking Water and 

Inhalation Exposure Pathways to Birds and Wild Mammals .....................................................54

Appendix C. TerrPlant results.....................................................................................................56
Page 5 of 56

1. Executive Summary

The Environmental Fate and Effects Division (EFED) and Antimicrobials Division (AD) have

completed the preliminary problem formulation for the ecological risk and drinking water 

assessments to be conducted as part of the registration review of tebuconazole (PC Code 128997). 

The problem formulation describes the methods to be used for the drinking water and ecological 

risk assessments in support of registration review and provides an overview of the environmental 

fate, ecological effects, and potential risks associated with the use of tebuconazole as well as 

uncertainties unique to its risk assessment. This document also identifies additional studies that 

would be beneficial to the conduct of an ecological risk assessment. If the additional 

recommended toxicity data are not available, EFED may presume risk to those taxa from the 

conventional uses.

Data needs for ecological effects are:

Conventional Uses

Honeybee Toxicity Data:

Tier 1:

• Adult Honey Bee Acute Contact Toxicity (850.3020) using TGAI

• Adult Honey Bee Acute Oral Toxicity (non-guideline) using TGAI

• Adult Honey Bee Chronic Oral Toxicity (non-guideline) using TGAI

• Larval Honey Bee Acute Oral Toxicity (non-guideline) using TGAI

• Larval Honey Bee Chronic Oral Toxicity (non-guideline) using TGAI

• Honey Bee Toxicity of Residues on Foliage (850.3030)

Tier 2:

• Semi-Field Testing for Pollinators (non-guideline)—may be waived pending the results of

the lower tier larval and adult honey bee acute and chronic oral toxicity studies

Tier 3:

• Field Trial of residues in pollen and nectar (non-guideline) - may be waived pending the

results of the lower tier larval and adult honey bee acute and chronic oral toxicity studies

• Field Testing for Pollinators (850.3040)—may be waived pending the results of the lower 

tier larval and adult honey bee acute and chronic oral toxicity studies

While, acute oral and contact toxicity studies with adult honey bees are available for end-use 

products that contain tebuconazole, adult and larval honey bee toxicity testing with TGAI is 

not available. As such, Tier 1 toxicity testing with TGAI consistent with the pollinator 

framework is recommend. Depending on the results of Tier 1 testing, additional testing may 

be requested. 

Tier II Terrestrial Plant Toxicity Data:

• Seedling Emergence (850.4100) using a TEP 

• Vegetative Vigor (850.4150) using a TEP
Page 6 of 56

The Tier I terrestrial plant toxicity testing resulted in no observed adverse effect concentration 

(NOAEC) values that were less than the limit concentrations (NOAEC<0.4 lb a.i./A) for 

monocots for seedling emergence testing and for monocots and dicots for vegetative vigor

testing. As such, additional testing is requested in an effort to obtain definitive terrestrial 

plant toxicity values. While testing using a dose-response test design (Tier II) is preferred, 

Tier I testing may be acceptable if the requirements as outlined in OCSPP 850.4100 and 

850.4150 are met for all tested species.

Sediment (benthic invertebrate) Toxicity Data:

• Freshwater Chronic Sediment Toxicity (non-guideline) using TGAI for two species of 

freshwater invertebrates 

• Estuarine/marine Chronic Sediment Toxicity (non-guideline) using TGAI for one species 

of estuarine/marine invertebrates

Given the persistence of tebuconazole and its affinity to bind to soil, sediment-dwelling 

organisms may be exposed. Toxicity data which indicates that tebuconazole affects the 

developmental rate of sediment-dwelling invertebrates are available. However, toxicity data 

evaluating reproductive effects are not available. Since reproductive effects have been 

observed in other aquatic invertebrates, chronic sediment toxicity data which includes 

evaluation of reproduction is requested. 

Aquatic Non-vascular Plant Toxicity Data:

• Algal Toxicity (850.4500) using TGAI for two species of non-vascular plants (freshwater 

and marine diatoms)

• Cyanobacteria Toxicity (850.4550) using TGAI

Aquatic non-vascular plant toxicity data are only available for one (i.e., green algae) of four 

recommended in the OCSPP 850.4500/4550 test guidelines. Differential sensitivity may exist 

among aquatic non-vascular plants, and as such, additional testing with the three other species 

is requested. 

Acute Oral Toxicity Testing with Passerines (850.2100) using TGAI

Acute oral toxicity testing with passerines is not available. Passerines may exhibit differential 

toxicity compared to other birds. Given the mortality observed in the acute oral testing with 

bobwhite quail, testing with passerines is requested.

Data needs for environmental fate assessment are:

Environmental Chemistry Methods (ECM) and Associated Independent Laboratory Validation 

(ILV) Reports:

• ECM & ILV report for analytical method in soil (850.6100) using TGAI 

• ECM & ILV report for analytical method in water (850.6100) using TGAI 
Page 7 of 56

Antimicrobial Uses

These ecological effects data are being requested for the conventional uses, but are also 

needed for the antimicrobial uses. 

Sediment (benthic invertebrate) Toxicity Data:

• Freshwater Chronic Sediment Toxicity (non-guideline) using TGAI for one species of 

freshwater amphipod.

• Estuarine/marine Chronic Sediment Toxicity (non-guideline) using TGAI for one species 

of estuarine/marine amphipod.

Aquatic Non-vascular Plant Toxicity Data:

• Algal Toxicity (850.4500) using TGAI for two species of non-vascular plants (freshwater 

and marine diatoms)

• Cyanobacteria Toxicity (850.4550) using TGAI

These environmental fate data are expected to be required for the antimicrobial use patterns only:

• Guideline 850.3300: Activated sludge respiration inhibition (ASRI)

• Guidelines 835.3110, 835.3220, 835.3240, 835.3280 (WWTP biodegradation studies)1

• Guideline 835.1110, Activated Sludge Sorption Isotherm (ASSI)2 

2. Introduction

Tebuconazole (Figure 1) is a triazole herbicide that has protective, curative, and systemic 

activity, and shows activity against rusts (Puccinia spp.), powdery mildew, and fungi known to 

cause decay in wood and other materials. It provides protective activity by preventing completion 

of the infection process by direct inhibition of sterol synthesis. The mode of action of 

tebuconazole is based on inhibition of cytochrome P450 sterol 14α-demethylase (P45014D) 

activity, a key enzyme in the sterol biosynthetic pathway. It is rapidly absorbed by plants and 

translocated systemically in the young growing tissues. Some trade names for products 

containing tebuconazole include Lynx 45 WG, Lynx 2, Elite 45 DF, and Folicur 3.6F. End-use 

products for conventional uses are formulated as water-soluble granules and a water-soluble 

liquid concentrate, and can be applied by air, ground, or chemigation. End-use products for 

 1. The results of the Activated Sludge Respiration Inhibition Test (ASRI) will determine which of these four biodegradation tests 

is/are anticipated to be required. 

• If the ASRI test EC50 is less than or equal to 20 mg/L, then either the (i) Biodegradation in Activated Sludge Study or (ii) 

Simulation Test - Aerobic Sewage Treatment: A. Activated Sludge Units or (iii) the Porous Pot Test is required. If the ASRI 

test EC50 is greater than 20 mg/L, then the registrant must conduct either: (i) Ready Biodegradability or (ii) a) 

Biodegradation in Activated Sludge or b) Simulation Test - Aerobic Sewage Treatment: A. Activated Sludge Units or c) the 

Porous Pot Test. 

• If the Ready Biodegradability study is conducted and passes, then no further testing is required. If, however, the antimicrobial 

fails the Ready Biodegradability study, then the a) Biodegradation in Activated Sludge or b) Simulation Test - Aerobic 

Sewage Treatment: A. Activated Sludge Units, or c) the Porous Pot study is required.

2 The log Kow is greater than 3 (3.7), and ASSI data are required.
Page 8 of 56

antimicrobial uses are formulated as powders and liquid concentrates for wood protection 

treatments (dip, spray, and pressurized applications), buildings/ indoor products, forest products, 

and for use in a variety of sites as a materials preservative.

Figure 1: Chemical structure of tebuconazole (PC Code 128997) 

Laboratory environmental fate studies have shown that there are several minor degradates (<10% 

formation) of tebuconazole. Fate data for these degradates suggest similar persistence as the 

parent tebuconazole, but they are more mobile than the parent.

EFED and AD evaluated the most recent ecological risk assessments for tebuconazole in 

association with the updated toxicity, exposure, and usage information to determine if sufficient 

data are available or if further updates are needed to support registration review. In addition, 

EFED and AD considered the latest Agency science policies and risk assessment methodologies. 

3. Use Characterization

Conventional Uses

Tebuconazole is currently registered on many agricultural crops including some tree nuts, stone 

fruits, pome fruits, beans, and field crops like corn, soybeans, and wheat (including seed treatment 

use for wheat). It is also registered for use on golf course turf, ornamentals, and grasses grown 

for seed. 

BEAD’s chemical profile includes both a summary of labeled uses as well as a summary of 

available reported usage data (Table 1) for the conventional pesticidal uses of tebuconazole. The 

Screening Level Usage Analysis (SLUA; April 29, 2015) and chemical profile reports conducted 

by BEAD showed highest usage of tebuconazole on peanuts and wheat with an annual average of 

300,000 pounds active ingredient applied to each, based on available data from 2004—2013

(USEPA, 2015). Other crops with higher usage include grapes, soybeans, cherries and corn.

Additionally, the average percent crop treated with tebuconazole was 60% for garlic, 45% for 

peanuts, and 30% for cherries. 

N N

N

Cl C

H2

C

H2

OH

CH2

CH3

CH3

CH3
Page 9 of 56

Table 1. Screening Level Estimates of Agricultural Uses (SLUA) of 

Tebuconazole (128997)

Annual Average Percent Crop Treated

Crop Lbs. A.I. Average Maximum

Almonds 2,000 5 10

Apples <500 <2.5 <2.5

Apricots <500 10 20

Asparagus <500 5 15

Barley 6,000 <2.5 <2.5

Beans, Green <500 <2.5 <2.5

Beans, Lima <500 <2.5 <2.5

Cantaloupes 1,000 <2.5 10

Cherries 10,000 30 45

Corn 10,000 <1 <2.5

Cotton 6,000 <1 <2.5

Cucumbers <500 <1 <2.5

Dry Beans/Peas 4,000 <2.5 5

Garlic 4,000 60 95

Grapes 30,000 25 35

Nectarines 1,000 10 20

Onions 1,000 5 5

Peaches 3,000 10 25

Peanuts 300,000 45 55

Pears <500 5 5

Pecans 9,000 5 15

Pistachios 1,000 5 10

Plums/Prunes <500 <2.5 5

Pumpkins <500 <2.5 <2.5

Soybeans 20,000 <1 <2.5

Squash <500 <2.5 5

Sweet Corn 3,000 <2.5 5

Walnuts <500 <1 <2.5

Watermelons 8,000 15 30

Wheat 300,000 5 15

Wheat (Seed treatment) 7,000 15 20

All numbers are rounded.

<500: less than 500 pounds of active ingredients.

 <2.5: less than 2.5 percent of crop is treated.

<1: less than 1 percent of crop is treated.

SLUA data sources include: 
Page 10 of 56

Table 1. Screening Level Estimates of Agricultural Uses (SLUA) of 

Tebuconazole (128997)

Annual Average Percent Crop Treated

Crop Lbs. A.I. Average Maximum

USDA-NASS (United States Department of Agriculture's National Agricultural Statistics 

Service) 

Private Pesticide Market Research

California DPR (Department of Pesticide Regulation)

These results reflect amalgamated data developed by the Agency and are releasable to the public.

Figure 2 depicts the agricultural usage of tebuconazole on a national scale as compiled by the 

U.S. Geological Survey (USGS, 2012)

3

. Major usage included use on wheat and soybeans with 

increases in use on corn in more recent years. 

 3

http://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2012&map=TEBUCONAZOLE&hilo=L&disp=

Tebuconazole (accessed October 27, 2015)
Page 11 of 56

Figure 2. National Agricultural Usage of Tebuconazole (USGS, 2012)

The use profile and parameters to be utilized for EFED’s risk assessment include the terrestrial 

uses described in Table 2. EFED will use application scenarios that result in maximum exposure 

scenarios for a given use for the risk assessment. It is noted that most uses do not indicate the 

maximum number of applications per year, but do report a maximum application use rate (annual 

or crop cycle). As such, EFED will divide the maximum application use rate by the single 

maximum application rate to determine the number of applications per year for modeling (using 

the minimum re-application interval between applications). If there are situations where the label 

reports a maximum application use rate by crop cycle and does not identify a maximum yearly 

use rate (based on Label Use Information Systems (LUIS) report, only golf courses and 

ornamental uses and some barley use labels report maximum annual rate), EFED may use 

additional information to model more than one crop cycle in a year where appropriate.
Page 12 of 56

Table 2. Tebuconazole Agricultural and Non-agricultural Conventional Use Patterns1.

Crop Maximum 

Single 

Application 

Rate (lb 

a.i./A)

Number of 

Applications

Maximum 

Application Rate 

(Annual or crop 

cycle)2

Reapplication 

Interval

Method of 

Application

Almonds 0.225 NS 0.9 7 Aerial, Ground

Apple 0.1297 NS 0.4409 7 Ground

Asparagus 0.169 3 0.507 14 Aerial, Ground

Banana 0.09 NS 0.45 14 Aerial, Ground

Barley 0.113 NS 0.113 NA Aerial, Ground

Barley (seed 

treatment)

2E-5 lb /lb 

seed

NA NA NA NA

Beans 0.169 NS 0.677 14 Aerial, Ground

Beans, dry type 0.169 NS 0.338 14 Aerial, Ground

Beets 0.203 NS 0.81 14 Aerial, Ground

Brassica (head and 

stem vegetables)

0.112 NS 0.45 10 Aerial, Ground

Bulb vegetables 0.164 NS 0.656 10 Aerial, Ground

Cherries 0.225 NS 1.35 7 Aerial, Ground

Cherries 0.0921 NS 0.1828 7 Aerial, Ground

Cherries (fruit 

cleansing)

0.0045 lb/lb 

fruit

NS NS NS Ground

Corn (unspecified & 

sweet)

0.169 NS 0.677 7 Aerial, Ground

Corn (seed treatment) 0.0002 lb/lb 

seed

NA NA NA NA

Corn, field, pop & 

sweet

0.0895 NS 0.358 7 Aerial, Ground

Cotton 0.225 NS 0.67 7 Aerial, Ground

Cucurbits 0.225 NS 0.67 10 Aerial, Ground

Filbert (hazelnut) 0.225 NS 0.9 7 Aerial, Ground

Fruiting vegetables 0.225 NS 1.35 7 Aerial, Ground

Garlic 0.169 NS 0.33 10 Aerial, Ground

Garlic (in-furrow) 0.57 NS 0.912 NS Ground

Golf course turf

1.3

(some have 

0.72 w/max of 

4.4)

6 4.4 NS Ground

Grapes 0.11 NS 0.9 7 Aerial, Ground

Grasses grown for 

seed

0.225 NS 0.45 14 Aerial, Ground

Hops 0.225 NS 0.9 10 Aerial, Ground

Leek 0.169 NS 0.67 10 Aerial, Ground

Melon 0.22 NS 0.44 10 Ground

Nectarine 0.225 NS 1.35 7 Aerial, Ground

Oats, Wheat & 

Triticale (seed 

treatment)

2E-5 lb/lb seed NA NA NA NA

Okra 0.169 NS 0.67 14 Aerial, Ground

Onion 0.169 NS 0.33 10 Aerial, Ground

Onion (in-furrow) 0.57 NS 0.91 NS Ground

Onions, green 0.169 NS 0.67 10 Aerial, Ground
Page 13 of 56

Table 2. Tebuconazole Agricultural and Non-agricultural Conventional Use Patterns1.

Crop Maximum 

Single 

Application 

Rate (lb 

a.i./A)

Number of 

Applications

Maximum 

Application Rate 

(Annual or crop 

cycle)2

Reapplication 

Interval

Method of 

Application

Ornamentals – tree 

injection

1.5 lb / see 

footnote 3

NS NS When 

needed

Injection

Ornamental grasses

& Rye (seed

treatment)

1.5E-5 lb/lb 

seed

NA NA NA NA

Ornamentals 0.0013 lb 

/plant

4 NS 28 Aerial, Ground

Ornamentals & Roses 6.9 E-6 lb/ 

plant

NS NS 7 Ground

Ornamentals 2.6 3 or 4 NS 28 Granular

Ornamentals 0.28 4 1.1 14 Ground

Ornamentals 0.84 4 3.36 14 Ground

Peach 0.225 NS 1.35 7 Aerial, Ground

Peanuts 0.203 NS 0.81 14 Aerial, Ground

Pecan 0.225 NS 0.9 10 Aerial, Ground

Pistachio 0.225 NS 0.9 10 Aerial, Ground

Plantain 0.09 NS 0.45 14 Aerial, Ground

Plum, Prune (fruit 

cleansing)

0.0002 lb/ lb 

fruit

NS NS NS Ground

Pome fruits 0.225 NS 1.35 7 Aerial, Ground

Shallot 0.169 NS 0.33 10 Aerial, Ground

Shallot (in-furrow) 0.57 NS 0.91 NS Ground

Soybean 0.11 3 0.33 10 Aerial, Ground

Stone fruit 0.225 NS 1.35 7 Aerial, Ground

Subtropical/tropical 

fruit

0.169 8 1.35 10 Ground

Sunflower 0.169 NS 0.45 14 Aerial, Ground

Tree nuts 0.225 NS 0.9 7 Aerial, Ground

Turnip (greens) 0.203 NS 0.81 12 Aerial, Ground

Wheat 0.11 NS 0.11 NA Aerial, Ground

NS means “not stated”; NA means “not applicable” 1 Based on BEAD LUIS report

2 Based on LUIS report, only golf courses, ornamentals and some barley labels specify maximum annual use rate; 

all other uses appear to be based on maximum rate crop cycle. As such EFED may model more than 1 crop cycle 

per year, if appropriate, based on agricultural practices for a crop. 3 If measuring the circumference, divide this number by six (6) to determine the number of capsules needed. If

measuring the diameter, divide this number by 2 (two) to determine the number of capsules needed. If the number 

of capsules results in a fraction, round down to the lower whole number

Antimicrobial Uses

There are 41 active labels for tebuconazole that contain antimicrobial uses. According to the 

labels, tebuconazole can be used for above-ground and ground-contact wood, plastics, glues, 

adhesives, and metalworking fluids. Tebuconazole may be applied as an antisapstain treatment to

wood and wood-composite products including lumber, timbers (logs), landscape ties, fence 

boards and posts, decks, docks, walkways, and shingles. Application methods include pressure 
Page 14 of 56

treatment, dipping, and spraying, and one label (EPA Reg., No. 75341-14) includes remedial 

treatment of in-service wood using brushes, trowels, and pumps. Two labels (EPA Reg. No. 

39967-10 and 39967-13) also include uses in plastics, glues, adhesives, and metalworking fluids. 

4. Conclusions from Previous Risk Assessments

4.1. Ecological Risk Assessments

Tebuconazole has been assessed a number of times for new use risk assessments since the original 

registration in 1993. A couple of the more recent risk assessments include: evaluating 

tebuconazole use on home lawns, athletic fields, and sod in 2013 (DP405730+), and for use on 

fruiting vegetables (crop group 8) in 2009 (D362764).

EFED and AD have evaluated these assessments for tebuconazole in association with the current 

toxicity, exposure, and use information to determine if sufficient data are available and if further 

data/updates are needed to support registration review. In the previous assessments, risks were 

generally assessed using the parent compound only. 

Based on the various past assessments which spanned a range of application rates and use 

patterns, risk tended to be greatest for freshwater fish (chronic), marine/estuarine invertebrates 

(acute and chronic), birds (acute and chronic), mammals (chronic), and terrestrial plants

depending on the use patterns and application rates. A qualitative summary of previous risk 

concerns identified is provided in Table 3.

Table 3. Summary of Previous Risk Concerns Identified for Tebuconazolea

Exposure 

Basis Birds Mammals Terrestrial Plants

Terrestrial 

Inverts. (honey 

bee hazard)

Fish Aquatic 

Inverts

Aquatic 

Plants Persistence

Acute Yes No

Yes Nob

No Yesc

No Yes

Chronic Yes Yes Yes Yes

a. At least one LOC has been exceeded in previous assessments

b. Lack of toxicity data

c. Estuarine/marine invertebrates only

4.2. Drinking Water Assessments

The most recent drinking water assessment (DWA) for tebuconazole (parent only) for an increase 

of maximum use rate of tebuconazole on golf course turf was conducted in 2011. Tebuconazole 

estimated groundwater concentrations were calculated using the Tier I SCIGROW (Screening 

Concentration In Ground Water) model. The maximum concentrations of tebuconazole in surface 

water (use on turf) were estimated to be 92.3 μg/L for the 1-in-10-year annual peak, and 72.4

μg/L for the 1-in-10-year annual average. The maximum peak concentration of tebuconazole in 
Page 15 of 56

groundwater was estimated to be 1.56 μg/L. No surface water monitoring data were available for 

tebuconazole.

4.3. Clean Water Act Programs 

Tebuconazole is not identified as a cause of impairment for any water bodies listed as impaired 

under section 303(d) of the Clean Water Act. No Total Maximum Daily Load (TMDL) criteria 

have been developed for tebuconazole. No aquatic life criteria have been established for 

tebuconazole, although aquatic life benchmarks are available for tebuconazole (Table 4) 

(http:/www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/aquatic-life-benchmarkspesticide-registration). 

Table 4. OPP Aquatic Life Benchmarks (μg /L) (freshwater)

Fish Invertebrates Nonvascular Plants Vascular Plants

Acute Chronic Acute Chronic Acute Acute

1135 12 1440 120 1450 151.5

5. Environmental Fate and Transport 

Tebuconazole is persistent in soil (aerobic metabolism T1/2 = 796 days) and moderately to slightly 

mobile in soil (adsorption KOCs range from 906 to 1251 ml/g). Tebuconazole has little potential 

to reach ground water, except in soils of high sand and low organic matter content. During a 

runoff event, tebuconazole adsorbed onto the soil particles could enter adjacent bodies of surface 

water via sediment in runoff. During an application, tebuconazole may drift off-site into the 

surface water. Tebuconazole will not appreciably volatilize from soil or water, based on its vapor 

pressure and water solubility limit

Tebuconazole is resistant to hydrolysis (T1/2 >> 28 days or stable at pH 5, 7, and 9), aqueous and 

soil photodegradation [T1/2= stable (extrapolated T1/2 = 590 days and 192.5 days, respectively)], 

and soil metabolism (aerobic metabolism T1/2 = 796 days). Terrestrial field dissipation halflives varied from about 1.6 to 10 months. Tebuconazole dissipated with an extrapolated half-life 

of 301 days from loamy sand turf plots at one site in Glenmark, New York, when LYNX 25DF 

fungicide was surface broadcasted three times at 1.40 lb a.i./A and once at 0.68 lb a.i./A

(applications separated by one-month). A supplemental study on bare ground in Florida showed 

leaching of tebuconazole to a lower horizon. In sand soil of Vero Beach, FL (sand = 92%, silt = 

0.4%, clay = 7.6%, and organic matter = 1%) tebuconazole was detected up to 0.12 ppm in the 

depth of 6 to 12 inches 30 days after surface application of 1.5 lb. a.i./A (lower depths were not 

sampled, MRID [Master Record Identification Number] 40700963). In addition, tebuconazole 

has a low potential for bioaccumulation in fish tissues, with a log Kow of 3.7 and fish BCFs of

25, 228, and 99 L/kg for edible, nonedible, and whole fish tissues, respectively. Depuration was 
Page 16 of 56

rapid, with 99-100% of the accumulated 14C residues eliminated from the fish tissues by day 15 of 

the depuration period.

For the antimicrobial uses, the low Kow (Log P) of 3.7 in MRID 44108304 also indicates that 

sorption will be a significant route of dissipation, and most residues in the environment will be 

associated with soil and sediment. In a Wastewater Treatment Plant (WWTP), the primary route 

of dissipation is expected to be sorption with limited volatility because of the low vapor pressure 

(1.3 x 10-8 mm Hg) in MRID 44108304 and the Henry’s Law constant of 2 x 10-10 atm m3 mol-1

(calculated). In a modified AWPA E11-124 study using submerged blocks in water, leaching 

from treated wood increases with increasing temperature (5-25 oC) and decreases with increasing 

pH (pH 5.5-8.5), with maximum release rates of 0.78-2.87 μg/cm2/day (MRID 46841601)5. In an 

AWPA E11-12 study (MRID 48901607, unreviewed), the average leaching of tebuconazole was 

6.7 % (no leaching rates calculated). This study will be reviewed during registration review. 

A selection of tebuconazole environmental fate and transport properties is summarized in Table 5

below.

Table 5. Physical Chemical and Environmental Fate Properties of Tebuconazole.

Parameter Value Source

Selected Physical/Chemical Parameters

Chemical 

Structure

CH 3

N

N

N

C

H 2

C H 3 O H

C H 3 C

H 2

C

H 2

Cl

Empirical 

Formula

C16H22ClN3O http://pubchem.ncbi.nlm.nih.gov/compound/Teb

uconazole#section=Names-and-Identifiers

IUAPC Name

(RS)-1-p-chlorophenyl-4,4-dimethyl-3-

(1H-1,2,4-triazol-1-ylmethyl)pentan-3-

ol

http://pubchem.ncbi.nlm.nih.gov/compound/Teb

uconazole#section=Names-and-Identifiers

CAS No. 107534-96-3 http://pubchem.ncbi.nlm.nih.gov/compound/Teb

uconazole#section=Names-and-Identifiers

PC Code No. 128997

SMILES string: CC(C)(C)C(CCC1=CC=C(C=C1)Cl)(C

N2C=NC=N2)O

http://pubchem.ncbi.nlm.nih.gov/compound/Teb

uconazole#section=Names-and-Identifiers

Molecular Weight 307.82 g/mol http://pubchem.ncbi.nlm.nih.gov/compound/Teb

uconazole#section=Names-and-Identifiers

Formulation Water Soluble Granule and Water 

Soluble Liquid Concentrate

 4 American Wood Protection Association, http://www.awpa.com/standards/ 5 U.S. EPA, Milano, T., August 30, 2006 review
Page 17 of 56

Table 5. Physical Chemical and Environmental Fate Properties of Tebuconazole.

Parameter Value Source

Vapor pressure 1.3X10-8 (torr) Tomlin CDS, ed; The e-Pesticide Manual: a 

world compendium. Tebuconazole 13th ed. PC 

CD-ROM, Version 3.0, 2003-04. Surrey, UK: 

British Crop Protection Council, (2003)

Aqueous 

solubility 

36 mg/L at 20 deg C Tomlin CDS, ed; The e-Pesticide Manual: a 

world compendium. Tebuconazole 13th ed. PC 

CD-ROM, Version 3.0, 2003-04. Surrey, UK: 

British Crop Protection Council, (2003)

Dissociation 

constants (pKa ) 

5.0 FootPrint Pesticide Properties 

Database@http://sitem.herts.ac.uk/aeru/iupac/Re

ports/610.htm

Henry’s Law 

Constant

1.4X10-10 atm-cu m/mole calculated

log Kow 3.7 Tomlin CDS, ed; The e-Pesticide Manual: a 

world compendium. Tebuconazole. 13th ed. 

British Crop Protection Council, (2003)

Persistence

Hydrolysis halflife (pH 5, 7, 9)stable MRID 40700957

Aqueous 

photolysis halflife

Stable MRID 40700958

Soil Photolysis

half-life

192.5 days MRID 40700958

Aerobic soil 

metabolism halflife 796 days MRID 40700959 

Anaerobic soil 

metabolism halflife1063 days MRID 40700959 

Anaerobic aquatic 

metabolism halflife 

>365 MRID 48707403 (supplemental)

Aerobic aquatic 

metabolism halflife (total system)

>52 MRID 48707405 (supplemental)

Mobility

Adsorption/

desorption 

KOC:1025, 911, 1251, and 906 mL/g MRID 40995922

Field Dissipation
Page 18 of 56

Terrestrial field 

dissipation halflife

1.6 - 10 months MRID

40700962

41717406

44108306

44108307-09

44108310-17

44666101-06

44699501

45046501

45359901

Fish Bioconcentration

Fish 

bioconcentration 

factors (BCF); 

depuration rate

BCFs (L/kg)

25 (edible)

228 (nonedible)

99 (whole fish tissues)

Depuration 

99-100% eliminated by day 15 of the 

depuration period.

MRID

40995905

40995906

40995907

5.1. Transformation Products

Based on the environmental fate data, carbon dioxide is the only major degradate of tebuconazole. 

Additional minor (<10% of applied activity) organic degradates were identified in the soil and 

aquatic fate studies. These include hydroxyphenyl tebuconazole, dechlorinated tebuconazole, and

deschloro hydroxy tebuconazole (dechlorinated alcohol of tebuconazole). Below, Table 6a

presents identified degradates and their maximum percent of applied radioactivity. Table 6b

presents fate data and summary information regarding parent degradation; other extracted 

products were not identified, but were formed in limited (<8%) quantities. Across the available 

environmental fate studies, formation of degradates was minor because tebuconazole was slow to 

degrade.

The transformation product, 1,2,4-triazole was not detected in any study for tebuconazole (this 

degradate is considered a major degradate for other conazoles). For some conazoles, this 

degradate has been shown to be more or equally toxic than the parent conazole for certain taxa 

(i.e., birds), therefore, the presence or absence of this product was noted for tebuconazole. 

Formation of 1,2,4-triazole in the environment is uncertain because tebuconazole degraded so 

slowly during the environmental fate studies that formation of 1,2,4-triazole, which is formed by 

other conazoles, was not observed. In the environment, however, 1,2,4-triazole may form over 

longer time scales.
Page 19 of 56

Table 6a. Tebuconazole and Its Environmental Transformation Products from Aquatic Metabolism Studies. 

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

(study length)

PARENT

Tebuconazole

(HWG 1608)

IUPAC: (RS)-1-pchlorophenyl-4,4-dimethyl3-(1H-1,2,4-triazol-1-

ylmethyl)pentan-3-ol

CAS: α-[2-(4-

Chlorophenyl)ethyl]-α-

(1,1-dimethylethyl)-1H1,2,4-triazole-1-ethanol

CAS No.: 107534-96-3

Formula: C16H22ClN3O

MW: 307.8 g/mol

SMILES: 

c1cc(Cl)ccc1CCC(O)(C(C)

(C)C)Cn2ncnc2

CH 3

N

N

N

C

H 2

C H 3 O H

C H 3 C

H 2

C

H 2

Cl

835.4300

Aerobic 

aquatic 

metabolism

48707405

Gravel pit 

water:sediment1 94.5% (7 d) 55.8% (364 d)

Drainage ditch 

water:sediment1 91.3% (7 d) 67.3% (364 d)

835.4400

Anaerobic 

aquatic 

metabolism

48707403

Pond 

water/sandy 

loam

107.0% (28 d) 91.1% (365 d)

MAJOR (>10%) TRANSFORMATION PRODUCTS

Carbon dioxide IUPAC: Carbon dioxide

Formula: CO2

MW: 44 g/mol

SMILES: C(=O)=O O C O

835.4300

Aerobic 

aquatic 

metabolism

48707405

Gravel pit 

water:sediment1 20.9% (364 d) 20.9% (364 d)

Drainage ditch 

water:sediment1 10.0% (364 d) 10.0% (364 d)

835.4400

Anaerobic 

aquatic 

metabolism

48707403

Pond 

water/sandy 

loam

0.46% (272 d)2 0.18% (365 d)2

Unextractable residues

NA NA

835.4300

Aerobic 

aquatic 

metabolism

48707405

Gravel pit 

water:sediment1 14.0% (364 d) 14.0% (364 d)

Drainage ditch 

water:sediment1 18.9% (364 d) 18.9% (364 d)
Page 20 of 56

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

(study length)

MINOR (<10%) TRANSFORMATION PRODUCTS

Hydroxyphenyl 

tebuconazole (K237, 

HWG 2606)

IUPAC: 5-(5-Hydroxy-4-

chlorophenyl)-2,2-

dimethyl-3-(1H-1,2,4-

triazol-1-ylmethyl)pentan3-ol

Formula: C16H22ClN3O2

MW: 323.8 g/mol

SMILES: 

CC(C)(C)C(CCc1ccc(c(c1)

O)Cl)(Cn2cncn2)O

CH 3

H O

Cl

O H

N

N

N

C

H 2

C H 3

C H 3 C

H 2

C

H 2

835.4400

Anaerobic 

aquatic 

metabolism

48707403

Pond 

water/sandy 

loam

1.17% (272 d) 0.51% (365 d)

Dechlorinated 

tebuconazole (K239)

IUPAC: 5-Phenyl-2,2-

dimethyl-3-(1H-1,2,4-

triazol-1-ylmethyl)pentan3-ol

Formula: C16H23ClN3O

MW: 273.37 g/mol

SMILES: 

CC(C)(C)C(CCc1ccccc1)(

Cn2cncn2)O

CH 3

O H

N

N

N

C

H 2

C H 3

C H 3 C

H 2

C

H 2 835.4400

Anaerobic 

aquatic 

metabolism

48707403

Pond 

water/sandy 

loam

0.71% (272 d) 0.38% (365 d)

Deschloro hydroxy 

tebuconazole 

(dechlorinated alcohol 

of tebuconazole)

IUPAC: 2,2-Dimethyl-5-

phenyl-3-(1,2,4-triazol-1-

ylmethyl)pentane-1,3-diol

Formula: C16H23N3O2

MW: 289.37 g/mol

SMILES: 

CC(C)(CO)C(CCc1ccccc1)

(Cn2cncn2)O

CH 3

C

H 2

O H

C

H 2

C

H 2

N

N

N

C

H 2

O H C H 3

835.4400

Anaerobic 

aquatic 

metabolism

48707403

Pond 

water/sandy 

loam

0.29% (90 d) 0.05% (365 d)

A AR means “applied radioactivity”. MW means “molecular weight”.

1 Sediments were characterized using the W. German BBA particle size classification system, but soil texture classifications were not reported.

2 Total volatiles are presumed to be carbon dioxide. Results from NaOH, ethylene glycol and H2SO4 traps were not separately reported.
Page 21 of 56

Table 6b. Soil Metabolism Studies and Degradation Summary Information for Tebuconazole

Study Percent Distribution of Recovered Radioactivity

Parent Degradate/transformation 

Product 1,2

Unextractable Residues Study ID

Aerobic Soil 

(phenyl 14C labeled)

98.3-82% from Day 0-112; 

78.8% @ 6 months; 

67.4% at 12 months

0.4-0.9% from Day 0-112; 

0.9&2.6% @ 6 months; 

1.1&2.1% @ 12 months

0.8-16.2% from Day 0-112;

17% @ 6 months;

29.1% @ 12 months

MRID 40700959

Aerobic Soil

(triazole 14C labeled)

98.1-85.0% from Day 0-58 0.3-0.6% from Day 0-582 1.3-14.5% from Day 0-58 MRID 40700959

Anaerobic Soil 73.1-70.3% from Day 0-60 0.4-2.2% from Day 0-60

4.1-7.5% (in flood water) 

from Day 0-60

19.5-23.4% from Day 0-60 MRID 40700959

Soil Photolysis 96-86% from Day 0-35 <1-3% from Day 0-60 2.6-5.5% from Day 0-60 MRID 40700958

Aqueous Photolysis 94-95% from Day 0-30 None observed None observed MRID 40700958 1 Extracted product(s) not identified (unknown)

2 1,2,4-triazole not detected
Page 22 of 56

6. Receptors

Tables 7 through 9 provide a summary of the taxonomic groups tested to characterize the potential 

acute and chronic ecological effects of tebuconazole. In addition, the tables provide a preliminary 

overview of the potential acute toxicity of tebuconazole by providing the acute toxicity 

classifications. The available toxicity data for tebuconazole are presented in Appendix A. 

6.1. Aquatic Organisms

Invertebrates, Acute. The estuarine/marine invertebrate, mysid shrimp (Americamysis bahia), was 

the most sensitive species with a 96-hr LC50 value of 0.49 mg a.i./L (MRID 40995902).

Invertebrates, Chronic. Chronic toxicity data are available for freshwater and estuarine/marine 

fish and invertebrates. In the freshwater invertebrate toxicity study, using Daphnia magna, the 

NOAEC value was 0.120 mg a.i./L based on reductions in adult body length and reproduction 

(LOAEC=0.230 mg a.i./L; MRID 40700915). In this study, it is noted that measured test solution 

concentrations increased during the study which may have been related to an increase in stock 

solution concentration. The reported effects are based on measured concentrations. 

A NOAEC of 0.035 mg a.i./L (LOAEC=0.061 mg a.i./L) was reported in the mysid shrimp (A.

bahia) chronic toxicity study based on a decrease in reproduction (MRID 42038201). Undissolved 

test material was noted in the diluter system and in the test chambers of the highest test 

concentration (0.200 mg a.i./L), and efforts to centrifuge or filter test solution samples prior to 

analysis were not reported. Given that there was undissolved material observed in the diluter 

system which prepared all the test solutions, there is uncertainty in the actual dissolved test 

concentrations in this study. Test solutions were approximately 50% of nominal at the beginning 

of the study, and measured concentrations generally gradually increased over the duration of the 

study. 

Given the uncertainty in exposure concentration in the mysid shrimp chronic toxicity study, an 

acute to chronic ratio (ACR) using the Daphnia magna toxicity data were used to calculate a 

chronic toxicity value for mysid shrimp. Using the ACR (28) and the acute mysid shrimp toxicity 

value (0.49 mg a.i./L), a chronic value of 0.018 mg a.i./L was derived, which is similar to the 

reported NOAEC in the mysid chronic study. Although there is uncertainty in the exposure 

concentrations, additional chronic estuarine/marine toxicity data are not requested, as the NOAEC 

value reported in the study along with other lines of evidence (e.g., ACR calculations, chronic 

toxicity data from other conazoles) will be used to evaluate potential risk to estuarine/marine 

invertebrates.

Fish, Acute. Tebuconazole is classified as moderately acutely toxic to fish and freshwater 

invertebrates, and highly toxic to estuarine/marine invertebrates. Acute toxicity data were 

available for three species of fish, with the most sensitive 96-hr LC50 value reported as 2.27 mg 

a.i./L for rainbow trout, Oncorhynchus mykiss (MRID 46919204). This study was conducted under 

static-renewal conditions (24-hr renewals) in which only Day 0 test solutions were measured. It 
Page 23 of 56

was reported that test solutions were measured in the rangefinder study with Day 0 samples 

ranging from 97-100% of nominal and 24-hr samples ranging from 90-102% of the initial Day 0 

concentrations, suggesting that test solution may have been stable during the 24-hr renewal period. 

In another rainbow trout acute toxicity study conducted under flow-through conditions, the 

reported 96-hr LC50 value is 4.4 mg a.i./L (MRID 40700911). 

Fish, Chronic. Several chronic toxicity studies are available for both freshwater and 

estuarine/marine fish. In a rainbow trout (O. mykiss) fish early life-stage study, there were no 

effects on hatch, but survival and growth were significantly reduced at ≥0.025 mg a.i./L (NOAEC 

of 0.012 mg a.i./L; MRID 40700914). 

In another fish early life-stage toxicity study with sheepshead minnows (Cyprinodon variegatus), 

there were no effects on hatch or survival, but wet weight was significantly reduced at ≥0.048 mg

a.i./L and length was reduced at 0.099 mg a.i./L (NOAEC of 0.022 mg a.i./L; MRID 42038202).

No reproductive effects were noted in a sheepshead minnow life cycle study (MRID 43009601), 

but parental survival was significantly reduced (day 58 & 177) at the highest treatment tested 

(0.197 mg a.i./L), and parental body length was significantly reduced at the mid-high treatment 

(0.097 mg/L; highest treatment not analyzed due to mortality). Additionally, offspring length was 

significantly reduced at the mid and mid-high concentrations (≥0.044 mg a.i./L, compared to 

solvent control) with an overall study NOAEC of 0.019 mg a.i./L. In this study, it is noted that 

salinity and temperature were variable throughout study, and there was low parental survival 

(24%) in one solvent control replicate at the end of the study (56% survival overall in solvent 

control). Also, it was reported that the offspring embryos were treated with 10% formalin to 

prevent disease. 

In a fathead minnow (Pimephales promelas) sexual development study (MRID 48109802), there 

was no effect on hatch but survival was significantly reduced at ≥0.045 mg a.i./L with significant 

reduction in female growth (body weight and length) at 0.022 mg a.i./L (NOAEC of 0.011 mg

a.i./L). There was no difference in sex ratio after 54 days of exposure. Increases (not statistically 

analyzed) in spinal deformities were observed at ≥0.022 mg a.i./L; histopathological effect on the 

liver and pancreas were observed at 0.011 mg a.i./L, and effects on gonadal histopathology was 

observed at 0.011 and 0.022 mg a.i./L for females and males, respectively. 

Finally, in the screening-level fish short-term reproduction assay (FSTRA) with fathead minnows, 

there were no statistically significant effects on survival, growth, or reproduction (fecundity) up to 

0.0195 mg a.i./L compared to the control (MRID 48688301). Alterations in non-apical endpoints 

included: alterations in female gonad histology, and statistically significant decreases in plasma 

vitellogenin as well as decreases in gonadal weight (relative to body weight) in males and females 

at 0.0195 mg a.i./L compared to the control. It is noted that in the Endocrine Disruptor Screening 

Program (EDSP) weight of evidence analysis, a medaka extended one-generation reproduction 

assay (MEOGRT) was recommended for tebuconazole (see EDSP section). 

In a published study by Yu et al. (2013), zebrafish embryos were exposed to tebuconazole at 

concentrations of 0, 1, 2, or 4 mg/L from shortly after spawning to 120 h post-fertilization. There 

were no significant effects on hatching, malformations, or survival.
Page 24 of 56

Amphibians. In the screening-level amphibian metamorphosis assay (AMA) with Xenopus laevis

tadpoles, a significant delay of median Nieuwkoop-Faber (NF) developmental stage by one stage 

was observed at Day 7 at all treatment groups (0.017, 0.067 & 0.341 mg/L), and significant delays 

at Day 21 at the mid (by one stage) and high (by 5 stages) concentrations. Additionally, decreases 

in snout-vent length and body weight were observed at the high concentration on both Day 7 and 

21 (MRID 48673701). 

Aquatic Plants. Several green algae toxicity studies are available for tebuconazole with the lowest 

EC50 value of 1.45 mg a.i./L, based on cell counts, and a NOAEC value of 0.32 mg a.i./L (MRID 

40995908). However, toxicity testing for the other three aquatic non-vascular species are not 

available (i.e., freshwater and marine diatoms, and cyanobacteria). Given that there may be 

differential sensitivity among the four species and the observed toxicity in the aquatic vascular 

plant study, toxicity testing with these additional species is recommended to support both 

conventional and antimicrobial uses of tebuconazole. The 14-d EC50, based on frond density, for 

the aquatic vascular plant, Lemna gibba, was reported as 0.151 mg a.i./L (EC05=0.034 mg a.i./L; 

MRID 44246901).

Benthic Invertebrates. A 28-d sediment toxicity study (spiked sediment) with the benthic 

invertebrate Chironomus riparius, evaluating survival and emergence and development rates is 

available (MRID 48707402). The most sensitive endpoint was development rate with reported 

NOAECs of 15.7 mg a.i./kg in sediment and 0.481 and 0.404 mg a.i./L in pore and overlying 

water, respectively. Given tebuconazole’s observed persistence in terrestrial and aquatic 

environments and its potential to bind to soil/sediment, chronic toxicity testing with sedimentdwelling (benthic) invertebrates is recommended. While the above study did evaluate longer-term 

survival and development, it did not evaluate reproduction which was reported as a sensitive 

endpoint in both the freshwater and estuarine/marine chronic invertebrate studies. Additionally, 

effects on larval body length were reported for the freshwater benthic harpacticoid copepod, 

Attheyella crassa (Turresson et al. 2007). As such, chronic benthic toxicity testing with 

tebuconazole which includes evaluating reproduction is recommended for both freshwater (two 

species, an amphipod and midge) and estuarine/marine invertebrates (one species, an amphipod) to 

support conventional uses of tebuconazole. For antimicrobials, studies conducted for one species 

of freshwater amphipod and one species of estuarine/marine amphipod will satisfy this 

requirement. 

Mesocosm Study. A mesocosm study which simulated turf applications of 0.68 lb a.i./A at two 

week intervals was applied 4 times by subsurface injection was conducted to determine if the use 

of this product could result in chronic effects to fish and aquatic invertebrate communities (MRID 

42760101). A review of the study found that tebuconazole altered juvenile fish growth and 

survival at the highest test concentrations (24.4 to 149 μg/L in water). These alterations in fish 

populations altered the community structure with regards to other species (plant and invertebrates).

 
Page 25 of 56

Table 7. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for Tebuconazole

Taxonomic 

Group

Study 

Type Tested Species

Toxicity Value

(95% conf. 

intervals)

(mg a.i./L)

Acute 

Toxicity 

Classification

Source

(Study Classification)

Comments

Freshwater 

fish1

Acute

Rainbow trout 

(Oncorhynchus 

mykiss)

96-Hr LC50 = 2.27

(1.59-3.31)

Slope: 3.25

Moderately 

toxic

46919204 (Supplemental)

Chronic 

Fathead minnow 

(Pimephales 

promelas)

NOAEC = 0.011 NA

48109802 (Supplemental)2

Based on reduction in female 

growth

Freshwater 

invertebrates

Acute Water Flea 

(Daphnia magna)

48-Hr EC50 = 2.88

(2.1-3.9)

Slope = 2.38

Moderately 

toxic 46919205 (Acceptable)

Chronic Water Flea 

(Daphnia magna)

21-d NOAEC = 

0.120 NA

40700915 (Acceptable)

Based on reduction in 

parental body length and 

reproduction

Estuarine/ 

marine fish

Acute Sheepshead 

minnow 

(Cyprinodon 

variegatus)

96-hr LC50 = 5.9

(5.3-7.0)

Slope: NA

Moderately 

toxic 40995904 (Acceptable)

Chronic NOAEC = 0.019 NA

43009601 (Supplemental) 

Based on reduction in 

offspring body length

Estuarine/

marine 

invertebrates

Acute Mysid shrimp

(Americamysis 

bahia)

96-hr LC50 = 

0.49 (0.33-0.66)

Slope: 2.3

Moderately 

toxic 48587107 (Acceptable)

Chronic NOAEC = 0.035 NA

42038201 (Supplemental)3 

Based on reduction in 

reproduction

Aquatic 

plants and 

algae

Vascular Duckweed 

(Lemna gibba)

EC50 = 0.151

(0.139-0.165)

EC05 =0.034 N/A 44246901 (Acceptable)

Nonvascular

Green Algae

(Scenedesmus 

subspicatus)

EC50 = 1.45 (NA)

NOAEC 0.32 N/A 40995908 (Supplemental)

1 Freshwater fish may be surrogates for aquatic-phase amphibians. 2 Although this species is different than most acutely sensitive species, the rainbow trout chronic NOAEC value is 0.012 

mg a.i./L, which is similar to fathead minnow NOAEC.

3 Downgraded during review for problem formulation due to uncertainty in exposure concentrations from observation of 

undissolved test material

Formulation Toxicity. Additionally, acute toxicity studies using a formulation which contained 

tebuconazole are available for fish, Daphnia, and aquatic plants (SC 400 (200+200) G; 17.1% 

fluopyram and 17.5-17.8% tebuconazole). However, in these studies, only the other active 

ingredient (fluopyram, PC 080302) was measured in which recoveries were generally around 

nominal concentrations. As such, the toxicity values reported in Table 6 are based on nominal 

tebuconazole concentrations. The results of these studies, adjusted to percent tebuconazole, are 

similar or higher (less toxic) compared to toxicity values using TGAI. 
Page 26 of 56

Table 8. Acute Formulation Toxicity Data with Tebuconazole for Aquatic Species

Species Acute Toxicity Value 

(mg product/L)

Acute Toxicity Value 

(mg tebuconazole/L)

Study ID

Daphnia magna 48-hr EC50 = 56.9 48-hr EC50 = 9.961 47567611

Rainbow trout 96-hr LC50 = 21.7 96-hr LC50 = 3.81 47567612

Lemna gibba 7-d EC50 = 4.3 7-d EC50 = 0.762 47567616

Lemna gibba 7-d EC50 = 0.73 7-d EC50 = 0.132 47567617

Green algae 72-hr EC50 = 11 72-hr EC50 = 1.91 47567618

1 Based on 17.5% tebuconazole

2 Based on 17.8% tebuconazole

6.2. Terrestrial Organisms

Birds, Acute. Tebuconazole is slightly toxic to birds on an acute oral basis and practically nontoxic on a dietary basis, and it is slightly toxic to mammals on an acute oral exposure basis (Table 

7). In the acute oral bobwhite quail study (MRID 40700950) with tebuconazole, the acute LD50

value was 1,988 mg/kg-bw with decreased body weight observed at doses of ≥720 mg/kg-bw (no 

effect 432 mg/kg-bw). In the subacute dietary studies with mallard duck, no mortality was 

observed up to 4816 mg a.i./kg-diet, however, reduced body weight gain was observed 4816 mg 

a.i./kg-diet (MRID 40700907). In the sub-acute study with bobwhite quail, while the LC50 value 

was >5,000 mg.kg-diet, mortalities were observed at ≥2,500 mg/kg-diet with decreased body 

weight gains at all treatments (≥325 mg/kg-diet; MRID 40700908). 

No acute passerine bird toxicological data are available. Given the observed mortality in the acute 

oral and dietary studies with bobwhite quail and sublethal effects of reduced body weight gain in 

both the mallard and bobwhite subacute dietary studies, an avian acute oral study using a passerine 

species is requested to support conventional uses. Passerine exposure is not expected to result from 

antimicrobial uses, and AD does not anticipate the need for a passerine study to support 

registration review.

 

Birds, Chronic. In the avian one-generation reproduction toxicity studies (two quail and two 

duck), dietary administration of tebuconazole resulted in reproductive effects in two of the studies. 

In the first bobwhite quail study, no treatment-related reproductive effects or clinical signs were 

noted at dietary levels up to the highest concentration tested, 73.5 mg/kg-diet (MRID 40700910).

However, in the second bobwhite quail study conducted at higher concentrations (MRID 

41624201), significant reproductive effects were observed at the high dose (290 mg/kg-diet),

including a reduction of 33% in the number of eggs laid, 11% reduction in normal hatchlings, as 

well as a 37% decrease in offspring survival and 7-11% decreases in offspring body weight. In 

this study, significant reductions in offspring body weight (4-6%) were also reported at all

treatment groups (NOAEC <156 mg/kg-diet). In the first mallard duck study, no treatment-related 

reproductive effects or clinical signs were noted at dietary levels up to the highest concentration 

tested, 76 mg/kg-diet (MRID 40700909). However, in the second mallard duck study (MRID 

41818301), significant decreases in the number of hatchlings per hen were reported at the high 
Page 27 of 56

concentration of 611 mg/kg-diet; however, no significant effects on the number of hatchlings per

viable embryos were determined at any treatment concentration. Considering the results of these 

studies collectively and the magnitude of effects observed at 156 mg/kg-diet, a NOAEC value of 

73.5 mg/kg-diet will be used in the assessment.

Mammals. The mammalian acute toxicity LD50 value is 1615 mg/kg bw (MRID 42090006). In a 

2-generation reproductive toxicity study in rats, the lowest NOAEL was reported as 300 mg 

a.i./kg-diet, based on decreased maternal and pup body weights and pup viability; the LOAEL was 

1000 mg a.i./kg-diet (MRID 40700946).

Honey Bees. Acute contact or oral toxicity data to bees for tebuconazole TGAI were not submitted 

to the Agency. A contact LD50 value of 176 μg a.i./bee has been reported.6 However, acute oral 

and contact toxicity data for adult honeybees are available for two formulations containing 

tebuconazole. In the first study (SC 400 (200+200) G) acute oral and contact LD50 values of 62.5 

and >200 μg product/bee (10.9 and >35 μg tebuconazole/bee) were reported, respectively (MRID 

47567613). However, as in the acute aquatic toxicity studies with this formulation, tebuconazole 

concentrations were not measured. In another formulation study with tebuconazole (17%), acute 

contact and oral LD50 values were 7.6 and 1.5 μg a.i./bee, respectively (MRID 48844515). While a 

definitive toxicity value was obtained in the second formulation study, given that there was another 

active ingredient present and there are no submitted data with tebuconazole only, it is unknown 

how this other a.i. (flupyradifurone) influenced the overall toxicity and what may be attributed to 

tebuconazole. Chronic toxicity data are not available for adult bees nor are acute or chronic data 

available for larval bees. Data on pollinator toxicity is required to sufficiently evaluate risk to 

pollinators (USEPA 2014a). Therefore, acute and chronic toxicity data for both adult and larvae 

honeybees using TGAI are recommended to support conventional uses. 

Antimicrobial uses of tebuconazole are expected to present far less exposure risk to honeybees 

than conventional uses, and then only to adult honeybees. Because tebuconazole is not expected to 

be applied to wood used to construct honey bee enclosures, tebuconazole poses no appreciable 

chronic risk to honeybees from antimicrobial uses. Therefore, only an adult acute contact study is 

necessary and sufficient to support antimicrobial uses. AD will use the most sensitive data 

endpoints available at the time of risk assessment to assess the risk posed to honeybees by 

tebuconazole. However, tebuconazole endpoints extrapolated from formulation toxicity studies are 

sufficient to characterize the acute risk posed by antimicrobial uses of tebuconazole to adult 

honeybees at this time. No further honeybee studies are expected to be required to support 

antimicrobial uses at this time.

Other Terrestrial Invertebrates. Other terrestrial invertebrate toxicity data with the SC 400 G 

formulation are available for earthworms, parasitoid wasps, ladybird beetles, green lacewing, and 

predatory mites. For these studies, in many cases, there were no effects up to the highest 

concentration tested (3L product/ha). For earthworms, a 14-d LC50 value of 875 mg product/kg dry 

weight (153 mg tebuconazole/kg) was reported.

 6 As reported in Bayer Report 99753, 1987, cited in Section 3 new use risk assessment D333331, 332261 and 332171. 

The DER for MRID 48844515 report an LD50 value of >175 μg/bee for tebuconazole.
Page 28 of 56

Terrestrial Plants. 

Tier I (limit concentration) terrestrial plant seedling emergence and vegetative vigor data are 

available for tebuconazole. While the IC25 values were greater than the limit concentration, 

NOAEC values were less than the limit concentration, except for dicot seedling emergence. As 

such, additional testing is requested in an effort to obtain definitive terrestrial plant toxicity values. 

While testing using a dose-response test design (Tier II) is preferred, Tier I testing may be 

acceptable if the requirements as outlined in OCSPP 850.4100 and 850.4150 for all tested species

are met, keeping in mind the concentration for which the current no NOAEC value is set at (i.e., 

testing would likely need to incorporate a rate lower than the current limit concentration). It is 

noted that the limit concentration (0.4 lb a.i./A) is slightly above estimated environmental 

concentrations (EECs) using the single maximum ground application rate for golf course turf at 1.3 

lb a.i./A (maximum EEC=0.27 lb a.i./A; TerrPlant v1.2.2; Appendix C). However, while the EECs 

are lower when modeling one application, EECs using multiple applications may be used in the 

future. 

As mentioned, Tier I (limit test) toxicity studies are available for monocot and dicot seedling 

emergence as well as for monocot and dicot vegetative vigor. In the first Tier I seedling 

emergence study with monocots and the Tier I vegetative vigor study with monocots and dicots, 

the IC25 values were greater than the limit concentration (single concentration tested at 0.4 lb 

a.i./A; 45821301). However, there were significant differences between the limit concentration and 

control for both monocots and dicots (NOAEC<0.4 lb a.i./A). 

In additional Tier 1 vegetative vigor and seedling emergence studies (MRID 4757615 and 

47567614), the IC25 values for monocots were >0.18 lb tebuconazole/A (1L product/ha; SC 400 

(200+200) G; 17.8% tebuconazole). However, for monocots in the vegetative vigor study, a 

significant 14% difference between the limit concentration and control was observed for oats

(NOAEC<0.18 lb a.i./A). For dicots, the IC25 values were <0.18 lb a.i./A in the seedling 

emergence study for four dicot species (cucumber was most sensitive with 41% inhibition), and 

were >0.18 lb a.i./A in the vegetative vigor study. 

The results of the seedling emergence Tier I study showed that dicots were more sensitive than 

monocots, with dicots exhibiting a >25% effect. As such, Tier II seedling emergence testing was 

conducted for dicots. The IC25 value for the most sensitive dicot species (tomato) from the Tier II 

seedling emergence study was 0.045 lb a.i./A (IC05 = 0.016 lb a.i./A; MRID 47299201). Since 

definitive IC25 and NOAEC values are available, additional testing with dicots for seedling 

emergence is not recommended. 

Antimicrobial uses of tebuconazole are expected to present less exposure to terrestrial plants than 

are conventional uses. No further terrestrial plant toxicity studies are required to support 

antimicrobial uses of tebuconazole.

 
Page 29 of 56

Table 9. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for 

Tebuconazole

Taxonomic 

Group

Study Type Tested Species Toxicity 

Value

Acute Toxicity 

Classification 

Source

(Study Classification)

Comments

Birds1

Acute

Bobwhite quail 

(Colinus. 

virginianus)

21-D LD50

1988 mg 

a.i./kg-bw

Slightly Toxic

40700905 (Acceptable)

Reduced body weight at 

720 ppm (no effect at 432). 

Sub-acute 

dietary

8-D LC50 ≥ 

5000 mg 

a.i./kg-diet 

Practically nontoxic

40700907 (Acceptable)

Mortality at ≥2500 ppm; 

reduced body weight gain 

at all concentrations (no 

effect <325 ppm)

Chronic

NOAEC = 

73.5 mg 

a.i./kg-diet N/A

40700910 & 41624201 

(Acceptable) Offspring 

body weight reductions at 

156 ppm

Mammals

Acute Oral Mouse (Mus 

musculus)

2

LD50 1615 

mg a.i./kgbw 

Slightly toxic 42090006 (Acceptable)

Acute 

Inhalation

Laboratory rat 

(Rattus norvegicus)

LD50

>0.371 

mg/L 

NA

40700922 (Acceptable); 

dosing to aerosol for 4 

hours with a 14-d 

observation period

Chronic

2-gen 

NOAEC = 

300 mg 

ai/kg-diet

LOAEC = 

1000 mg 

ai/kg-diet

N/A

40700946 (Acceptable) 

Based on decreased 

maternal and pup body 

weight and decreased 

pup viability [NOAEC 

= 15 mg/kg/day; 

LOAEC = 50 mg/kgday]

Insects

Acute 

contact

Honey bee 

(Apis mellifera L.)

No data available for TGAI

(formulation toxicity data available for acute oral and contact 

adult honeybees)

Acute Oral

Chronic 10-

Day

Larval 

Emergence

Terrestrial 

plants

Seedling 

Emergence

Dicot – tomato

(Solanum 

lycopersicum)

21-D IC25 = 

0.045 lbs 

ai/acre

IC05 = 0.016

lbs ai/acre 

N/A 47299201 (Supplemental)
Page 30 of 56

Table 9. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for 

Tebuconazole

Taxonomic 

Group

Study Type Tested Species Toxicity 

Value

Acute Toxicity 

Classification 

Source

(Study Classification)

Comments

Monocot – wheat

(Triticum aestivum)

21-D IC25 >

0.4 lbs 

ai/acre

NOAEC = 

<0.4 lbs 

ae/acre

N/A 45821301 (Supplemental)

Vegetative 

vigor

Dicot—Cucumber

(Daucus carota)

21-D IC25 >

0.4 lbs 

ai/acre

NOAEC = 

<0.4 lbs 

ae/acre

N/A

45821301 (Supplemental)

(Monocot – wheat

(Triticum aestivum)

21-D IC25 >

0.4 lbs 

ai/acre

NOAEC = 

<0.4 lbs 

ae/acre

N/A

1 Birds represent surrogates for terrestrial-phase amphibians and reptiles. 2 The acute oral toxicity LD50 value with rats is 3352 mg/kg-bw (females) MRID 40700917

6.3 Incidents

A review of the Ecological Incident Information System (EIIS, version 2.1) and the Avian 

Monitoring Information System (AIMS) was completed on October 16, 2015. There are 17

reported incidents in EIIS for tebuconazole (Table 10). No ecological incidents involving 

tebuconazole were identified in AIMS. In addition to the incidents recorded in EIIS, additional 

incidents have been reported to the Agency in aggregated incident reports. Pesticide registrants 

report certain types of incidents to the Agency as aggregate counts of incidents occurring per 

product per quarter. Ecological incidents reported in aggregate reports include those categorized as 

‘minor fish and wildlife’ (W-B), ‘minor plant’ (P-B), and ‘other non-target’ (ONT) incidents. 

‘Other non-target’ incidents include reports of adverse effects to insects and other terrestrial 

invertebrates. For tebuconazole, registrants have reported 2 minor fish and wildlife, 43 minor 

plant, and 0 other non-target incidents. Incident databases will be reviewed again at the time of the 

risk assessment.

Table 10. Summary of Ecological Incidents Associated with Tebuconazole as Reported 

In EIIS

Incident Type Legality Certainty

All Possible Probable High Probable

Fish and 

aquatic 

invertebrates

Registered Use or 

Unknown

1 1 -- --

Known Misuse 1 -- -- 1

All 2 1 -- 1
Page 31 of 56

Table 10. Summary of Ecological Incidents Associated with Tebuconazole as Reported 

In EIIS

Incident Type Legality Certainty

All Possible Probable High Probable

Plants Registered Use or 

Unknown

11 11 -- --

Known Misuse 3 1 2 --

All 14 12 2 --

One aquatic incident (incident # 1007892-003) was reported in compliance with 6(a)2 regulations 

about a fish kill in Minnesota on June 25, 1998. An undetermined number of fathead minnow were 

killed along a long stretch of a creek adjacent to two wheat fields that had been treated (one by 

aircraft) with Folicur. This incident was rated as "possible" because of the moderate acute toxicity 

of tebuconazole to fish. In addition, there were no data with regard to application parameter 

details.

Regarding one of the incidents to terrestrial plants, one was the result of a "misuse" situation

(incident # I01 5 152-001) where a formulator added tebuconazole to a 790-gallon lot of a mixture 

of quintozene, thiabendazol, and captan on March 12, 2004. This created a formulation of an 

unregistered end-use product for a soybean seed treatment which was used by about 10 

commercial seed treating companies in IL, IN, OH, MI, and LA. Stunted growth was observed on 

May 21, 2004, and growers were consequently instructed to destroy their crops. Damage to about 

1,950 acres of soybeans from the use of tebuconazole in conjunction with unknown adjuvant(s) 

resulted in plant stress and yellowing (incident # I016595-031, I0016595-032). Another incident 

with soybean occurred when damage was caused by high heat and the application of tebuconazole 

(incident # I01 16737-021). Damage to spring wheat resulted from a reported "off label use" of 

tebuconazole (incident # I016662-021, I01662-022). Leaf and head malformation were observed.

One incident (I021587-001, 2009) reported mortality to adult honeybees from 320 hives in Utah. 

However, the legality of the use was unknown and was rated as unlikely for tebuconazole. 

Overall, the incident data that are available indicate that exposure pathways for tebuconazole are

complete and that exposure levels are sufficient to result in field-observable effects to non-target

terrestrial plants.

7. Exposure Pathways of Concern

The environmental fate properties and conventional use patterns of tebuconazole indicate runoff and 

spray drift of tebuconazole applications represent potential transport mechanisms of tebuconazole

to aquatic and terrestrial organisms. The exposure pathways for antimicrobial uses are included in 

Section 8.2 below.

Drinking Water. The drinking water exposure pathway for birds and mammals was screened using 

the SIP (Screening Imbibition Program) screening method. The inhalation exposure pathway is 

typically evaluated using the STIR (Screening Tool for Inhalation Risk) screening method. SIP 

and STIR are described in detail at: http://www2.epa.gov/pesticide-science-and-assessing-
Page 32 of 56

pesticide-risks/models-pesticide-risk-assessment#terrestrial. The drinking water pathway alone for 

tebuconazole was found to not be an exposure pathway of potential concern on an acute or chronic 

basis for mammals or acute basis for birds, but did suggest a potential pathway of concern on a 

chronic basis for birds. SIP results are presented in Appendix B. This pathway will be explored 

further in the registration review risk assessment for tebuconazole. 

Inhalation. The inhalation exposure pathway was not considered likely to be an exposure pathway 

of potential concern for mammals or for vapor-phase for birds. However, it did suggest a potential 

concern for droplet inhalation for birds (Appendix B). In this analysis, a non-definitive acute LD50

inhalation value for rats was used as a definitive value (no mortality occurred in study). The 

trigger for potential concern is a ratio greater than 0.1, and the output for droplet inhalation for 

birds was 0.13. Given the use of the non-definitive value, and that the ratio was just above 0.1, 

additional inhalation toxicity data with birds is not requested at this time.

8. Analysis Plan 

8.1 Stressors of Concern

8.1.1 Ecological Risk 

No major degradates (>10% formation) were identified in either the soil or aquatic metabolism 

studies. Minor degradates were identified in the anaerobic aquatic metabolism study which are 

similar in structure to parent tebuconazole. Given the similarity in structure to parent 

tebuconazole, they may have similar toxicity profiles as the parent structure and could be 

considered for inclusion in exposure analyses using a total toxic residue (TTR) approach. 

However, given that the maximum formation rate for the three products ranged from 0.29-1.17%, 

inclusion of these products is anticipated to have no appreciable impact on resulting estimated 

environmental concentrations. Therefore, the stressor of ecological concern for terrestrial and 

aquatic organisms for the ecological risk assessment will only be the parent compound, 

tebuconazole. 

8.1.2 Drinking Water 

The Health Effects Division (HED) Metabolism Committee (MARC) determined that the residue 

of concern in drinking water is tebuconazole per se (Memo, 06/07/2001, W. Donovan, et al., 

D275136). Therefore, the residue that will be assessed in drinking water from surface and ground 

water is tebuconazole only.

Estimated drinking water concentrations (EDWC) for tebuconazole uses for use in the human 

health risk assessment will be modeled during registration review, due to the introduction of new 

(PRZM-GW) or revised (SWCC) models since the last drinking water exposure assessment.
Page 33 of 56

8.2 Measures of Exposure 

8.2.1 Modeling of Ecological Exposure 

Conventional Uses

EFED will use standard available models to evaluate potential exposures to aquatic and terrestrial 

organisms as described at http://www2.epa.gov/pesticide-science-and-assessing-pesticiderisks/models-pesticide-risk-assessment. 

Antimicrobial Uses

Based on the summary of registered uses of tebuconazole and the chemical, physical, and 

environmental fate properties in Table 4, the Agency has developed conceptual model diagrams 

for exposure of ecological organisms to tebuconazole.

The Agency has created conceptual models for potential routes of environmental exposure which 

are included in “Conceptual Models for Environmental Exposure Pathways of Antimicrobial 

Pesticides,” (EPA-HQ-OPP-2014-0638-0002), found in the docket at 

http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2014-0638-0002. The Agency 

does not consider the wall board or treated adhesives in packaging uses to create environmental 

exposure because the treated materials are not anticipated to come into contact with water. 

Use sites and corresponding figures of conceptual model diagrams are as follows:

• Wood preservation (slides 29-31)

• Metalworking fluids (slide 18)

• Glues and adhesives (slide 17)

• Plastics (slide 15)

Screening Level Down-the-Drain Analysis for Antimicrobial Uses of Tebuconazole

Chemicals that are released down-the-drain can typically take from a few to several hours to reach 

wastewater treatment plant intakes following their discharge and from several hours to roughly a 

day following their discharge down-the-drain to subsequently be discharged from wastewater 

treatment plants to surface water. Data on WWTP dissipation have not been submitted for 

tebuconazole, however, the primary routes of dissipation are expected to be partitioning to sludge 

with some subsequent outflow in effluent. 

For the metalworking fluid use, the Down-the-Drain (DtD) module of E-FAST (Exposure and Fate 

Assessment Screening Tool) will be used to determine the potential for aquatic organisms 

downstream of domestic wastewater treatment plants (WWTPs) that receive discharges from 

application of tebuconazole to be exposed to tebuconazole from the point of application to the 

point of discharge following wastewater treatment. The results of the DtD module runs are 

expressed as number of days of exceedance of concentrations of concern (COC) for aquatic 

organisms. In order to complete the down the drain assessment, the following studies will need to 

be submitted by the registrant: 850.3300 - Modified Activated Sludge Respiration inhibition; 
Page 34 of 56

835.3110 - Ready Biodegradable Test or one of three Biodegradable in Activated Sludge 

Simulation Tests (835.3220, 835.3280, 835.3240); and 835.1110 - Activated Sludge Sorption 

Isotherm.

 

8.2.2 Modeling of Drinking Water in Human Dietary Risk Assessment

The drinking water assessments conducted to support future human health risk assessments of 

tebuconazole will incorporate modeling of tebuconazole in surface and ground water. Since the 

last drinking water assessment was conducted, EFED has updated its surface and ground water

models, the drinking water modeling input parameters, and the percent cropped area (PCA) 

guidelines. For all modeling, input parameters are selected according to the current input 

guidance, and where in question, a conservative approach is taken in the selection of half-lives. 

Descriptions of all executable versions of current models for drinking water exposure can be 

obtained from the following URL link: http://www2.epa.gov/pesticide-science-and-assessingpesticide-risks/models-pesticide-risk-assessment#aquatic.

8.2.3 Available Water Quality Monitoring Data 

EFED will consider all ground and surface water monitoring data available, and will conduct a 

comprehensive evaluation of the data for the risk assessment. The data that may be considered 

include the United States Geological Survey (USGS) National Water-Quality Assessment 

(NAWQA) Program monitoring data, the EPA STORET database, and any State data available at 

the time of risk assessment.

8.3 Measures of Effect 

Toxicity data presented in Section 6 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 be considered. The open literature studies are 

identified using EPA’s ECOTOXicology database (ECOTOX) (USEPA, 2007), which employs a 

literature search engine for locating chemical toxicity data for aquatic life, terrestrial plants, and 

wildlife. The evaluation of both sources of data can also provide insight into the direct and 

indirect effects of pesticides on biotic 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

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 
Page 35 of 56

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 tebuconazole in connection 

with the development of its final registration review decision for tebuconazole. 

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 

tebuconazole 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 tebuconazole 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 tebuconazole as part of completing this registration review.

10. Endocrine Disruptor Screening Program

Tebuconazole was included in the first group of chemicals issued an order to conduct Tier 1 EDSP 

testing for which EPA has received all of the required Tier 1 assay data. The Agency has reviewed 

all of the assay data received for the appropriate List 1 chemicals and the conclusions of those 

reviews are available at http://www2.epa.gov/ingredients-used-pesticide-products/endocrinedisruptor-screening-program-tier-1-assessments. For additional information the EDSP program,

visit http://www2.epa.gov/endocrine-disruption. Based on the weight of evidence findings, for 

wildlife, the Medaka Extended One-Generation Reproduction Test (MEOGRT) was

recommended. 
Page 36 of 56

11. Preliminary Identification of Data Gaps 

11.1 Environmental Fate 

Table 11 identifies environmental fate studies by MRID that offer data for each guideline 

requirement, as well as study classifications and whether or not further data are needed in order to 

support risk assessment. Analytical methods in soil and water and associated independent 

laboratory validations are needed with LOQs below toxicological levels of concern. No other 

environmental fate data are needed.

Table 11: Environmental Fate Data Requirements for Tebuconazole

Guideline 

#

Data 

Requirement MRID #s

Study 

Classification

Are data 

needed to 

conduct risk 

assessment?

Justification and 

Assumptions EPA will 

Make in Absence of 

Data

835.2120 Hydrolysis 40700957 Acceptable

No NA

835.2240

Photodegradation 

in Water

40700958

45344601

Acceptable

Unacceptable 

No NA

835.2410

Photodegradation 

on Soil 40700958 Acceptable

No NA

835.4100

Aerobic Soil 

Metabolism

40700959

45344601

Acceptable

Invalid

No NA

835.4200

Anaerobic Soil 

Metabolism 40700959 Acceptable

No NA

835.4400

Anaerobic 

Aquatic 

Metabolism 48707403 Supplemental

No NA

835.4300

Aerobic Aquatic 

Metabolism 48707405 Supplemental

No NA

835.1240

835.1230

LeachingAdsorption/Desor

ption

40995922 

40700960

40700961

Acceptable

Acceptable

Unacceptable

No NA

835.1410

Laboratory 

Volatility N/A N/A

N/A

NA

835.8100 Field Volatility N/A N/A

N/A NA
Page 37 of 56

Table 11: Environmental Fate Data Requirements for Tebuconazole

Guideline 

#

Data 

Requirement MRID #s

Study 

Classification

Are data 

needed to 

conduct risk 

assessment?

Justification and 

Assumptions EPA will 

Make in Absence of 

Data

835.6100

Terrestrial Field 

Dissipation

40700962

41717406

44108306

44108307-09

44108310-17

44666101-06

44699501

45046501

45359901 Supplemental

No NA

850.6100 Analytical 

method in water

No data

N/A Yes

An analytical method in 

water and an associated 

independent laboratory 

validation report are 

requested for use by 

state lead agencies.

850.6100 Analytical 

method in soil

No data

N/A Yes

An analytical method in 

soil and an associated 

independent laboratory 

validation report are 

requested for use by 

state lead agencies.

850.1730 Fish

Bioconcentration

40995905-07 Supplemental No NA

850.3300

Activated sludge 

respiration 

inhibition (ASRI)

No data

N/A Yes

Data are needed to 

conduct a “down the 

drain” assessment for the 

antimicrobial uses.

Only one biodegradation 

study is needed. The 

appropriate study is 

determined by the results 

of the ASRI study.

835.3110

835.3220

835.3240

835.3280

WWTP 

biodegradation 

studies

No data

N/A Yes

835.1110 Activated Sludge 

Sorption Isotherm

No data

N/A Yes

11.2 Effects

Tables 12 and 13 identify ecological effects studies by MRID that offer data for each guideline 

requirement, as well as study classifications and whether or not further data are needed in order to 

support risk assessment. 
Page 38 of 56

Table 12. Available Ecological Effects Data for Aquatic Organisms Exposed to 

Tebuconazole and Remaining Data Gaps. 

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classification

Are data 

needed to 

conduct risk 

assessment

for 

conventional 

uses?

Are data needed

to support 

antimicrobial 

uses?

Justification and 

Assumptions EPA 

will Make in 

Absence of Data

850.1010 Freshwater 

invertebrate 

acute toxicity

40700913

46919205

47567611

Acceptable

Acceptable

Supplemental

No No NA

850.1025

850.1035

850.1045

850.1055 

Saltwater 

invertebrate 

acute toxicity 

40995902

40995903

48587107

Acceptable

Acceptable

Acceptable

No No NA

850.1075 Freshwater 

fish acute 

toxicity 

40700911

40700912

46919204

47567612

Acceptable

Acceptable

Supplemental

Supplemental

No No NA

850.1075 Saltwater fish 

acute toxicity 

40995904 Acceptable No No NA

850.1300 Freshwater 

invertebrate 

life cycle 

40700915 Acceptable No No NA

850.1350 Saltwater 

invertebrates 

life cycle 

42038201 Supplemental No No NA

850.1400 Freshwater 

fish 

early-life 

stage

40700914

40700915

48109802

Acceptable

Acceptable

Supplemental

No No NA

850.1400 Saltwater fish 

early-life 

stage 

42038202 Acceptable No No NA

850.1500 Fish life cycle 43009601 Supplemental No No NA

850.1735 Whole 

Sediment 

Acute 

Toxicity 

Invertebrates, 

Freshwater

No data N/A No No Given 

tebuconazole’s 

persistence, 

requesting chronic 

study below in lieu 

of acute study

850.1740 Whole 

Sediment 

Acute 

Toxicity 

Invertebrates, 

Saltwater

No data N/A No No Given 

tebuconazole’s 

persistence, 

requesting chronic 

study below in lieu 

of acute study
Page 39 of 56

Table 12. Available Ecological Effects Data for Aquatic Organisms Exposed to 

Tebuconazole and Remaining Data Gaps. 

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classification

Are data 

needed to 

conduct risk 

assessment

for 

conventional 

uses?

Are data needed

to support 

antimicrobial 

uses?

Justification and 

Assumptions EPA 

will Make in 

Absence of Data

NonguidelineWhole 

Sediment 

Chronic

Toxicity 

Invertebrates, 

Freshwater

No data N/A Yes Yes Tebuconazole is 

persistent and may 

partition to 

soil/sediment and 

therefore, sediment 

organisms may be 

exposed. The 

exposure should be 

from treated 

sediment and not 

overlying water, and 

the study should 

evaluate 

reproduction

NonguidelineWhole 

Sediment 

Chronic

Toxicity 

Invertebrates, 

Saltwater

No data N/A Yes Yes Tebuconazole is 

persistent and may 

partition to 

soil/sediment and 

therefore, sediment 

organisms may be 

exposed. The 

exposure should be 

from treated 

sediment and not 

overlying water, and 

the study should 

evaluate 

reproduction

850.4400 Aquatic plant 

Toxicity Test 

using Lemna

spp.

44246901

47567616

47567617

Acceptable

Acceptable

Acceptable

No No No

850.4500 Algal toxicity 40995908

42905401

44079601

47567618

Supplemental

Acceptable

Acceptable

Supplemental

Yes Yes Only toxicity data for 

green algae are 

available. Toxicity 

testing for two other 

algal taxa are 

required per 40 CFR 

Part 158 (i.e., 

freshwater and 

marine diatoms). 

Additionally, given 

the persistence of 

tebuconazole in 
Page 40 of 56

Table 12. Available Ecological Effects Data for Aquatic Organisms Exposed to 

Tebuconazole and Remaining Data Gaps. 

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classification

Are data 

needed to 

conduct risk 

assessment

for 

conventional 

uses?

Are data needed

to support 

antimicrobial 

uses?

Justification and 

Assumptions EPA 

will Make in 

Absence of Data

aquatic 

environments, there 

is a potential for 

exposure.

850.4550 Cyanobacteria No data N/A Yes Yes Only toxicity data for 

green algae are 

available. Toxicity 

testing for 

cyanobacteria are 

required per 40 CFR 

Part 158. 

Additionally, given 

the persistence of 

tebuconazole in 

aquatic 

environments, there 

is a potential for 

exposure.
Page 41 of 56

Table 13. Available Ecological Effects Data for Terrestrial Organisms Exposed to 

Tebuconazole and Remaining Data Gaps. 

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment

for 

conventional 

uses?

Are data needed 

to support 

antimicrobial 

uses?

Justification and 

Assumptions 

EPA will Make in 

Absence of Data

850.2100 Avian oral 

toxicity

40700905 Acceptable Yes No An acute oral 

study with a 

passerine species 

has not been 

submitted to the 

agency. Given 

observed mortality 

in the bobwhite 

quail acute oral 

and acute dietary 

study, a study with 

a passerine species 

is requested to 

support 

conventional uses.

850.2200 Avian dietary 

toxicity 

40700907

40700908

Acceptable

Acceptable

No No NA

850.2300 Avian 

reproduction

40700909

40700910

41624201

41818301

Acceptable

Acceptable

Acceptable

Supplemental

No No NA

NonguidelineAvian 

inhalation

No Data N/A No No Data have not been 

submitted to fulfill 

this guideline. A 

data gap was not 

identified as these 

data are not 

necessary for risk 

assessment at this 

time.
Page 42 of 56

Table 13. Available Ecological Effects Data for Terrestrial Organisms Exposed to 

Tebuconazole and Remaining Data Gaps. 

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment

for 

conventional 

uses?

Are data needed 

to support 

antimicrobial 

uses?

Justification and 

Assumptions 

EPA will Make in 

Absence of Data

850.3020 Honey bee 

acute contact 

toxicity

47567613

48844515

Supplemental

Acceptable

Yes No The available data 

were conducted 

with a formulated 

product and data 

have not been 

submitted to fulfill 

this guideline for 

TGAI. These data 

with TGAI are 

needed to evaluate 

acute risk to 

pollinators for 

conventional use 

risk assessment. 

This study is not 

needed to support 

antimicrobial uses.

850.3030 Honey bee 

residue on 

foliage

No Data N/A Yes No Data have not been 

submitted to fulfill 

this guideline. The 

conduct of this 

study is contingent 

upon the results of 

850.3020 for 

conventional uses. 

This study is not 

needed to support 

antimicrobial uses.

NonguidelineHoney bee 

adult acute 

oral toxicity

47567613

48844515

Supplemental

Acceptable

Yes No The available data 

were conducted 

with a formulated 

product and data 

have not been 

submitted to fulfill 

this guideline for 

TGAI. These data 

with TGAI are 

needed to evaluate 

acute risk to 

pollinators for 

conventional use 

risk assessments. 

This study is not 

needed to support 

antimicrobial uses.
Page 43 of 56

Table 13. Available Ecological Effects Data for Terrestrial Organisms Exposed to 

Tebuconazole and Remaining Data Gaps. 

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment

for 

conventional 

uses?

Are data needed 

to support 

antimicrobial 

uses?

Justification and 

Assumptions 

EPA will Make in 

Absence of Data

NonguidelineHoney bee 

adult chronic 

oral toxicity

No Data N/A Yes No Chronic (repeated 

dose) data is 

needed on adult 

honey bees to 

evaluate chronic 

risk to pollinators 

for the risk 

assessment for 

conventional uses. 

Although EPA has 

not developed a 

guideline for this 

study, guidance for 

a 10-day oral 

toxicity study is 

currently in 

development by 

OECD. A 

protocol should be 

submitted prior to 

study initiation. 

This study is not 

needed to support 

antimicrobial uses.

NonguidelineHoney bee 

larval acute 

oral toxicity

No Data N/A Yes No In addition to the 

adult honey bee 

data gaps 
Page 44 of 56

Table 13. Available Ecological Effects Data for Terrestrial Organisms Exposed to 

Tebuconazole and Remaining Data Gaps. 

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment

for 

conventional 

uses?

Are data needed 

to support 

antimicrobial 

uses?

Justification and 

Assumptions 

EPA will Make in 

Absence of Data

NonguidelineHoney bee 

larval chronic 

oral toxicity

No Data N/A Yes No identified above, 

data is needed for 

the additional 

honey bee life 

stage of larvae to 

complete the risk 

assessment for 

pollinators. 

Although EPA has 

not developed a 

guideline for these 

studies, OECD 

TG237 may be 

used to assess 

acute oral effects 

on larvae. Chronic 

(repeat dose) study 

guidance for 

assessing chronic 

oral toxicity to 

honey bee larvae is 

currently in 

development by 

OECD. A 

protocol should be 

submitted prior to 

study initiation. 

This study is not 

needed to support 

antimicrobial uses. 
Page 45 of 56

Table 13. Available Ecological Effects Data for Terrestrial Organisms Exposed to 

Tebuconazole and Remaining Data Gaps. 

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment

for 

conventional 

uses?

Are data needed 

to support 

antimicrobial 

uses?

Justification and 

Assumptions 

EPA will Make in 

Absence of Data

850.3040 Field testing 

for 

pollinators

No Data N/A Yes No Data have not been 

submitted to fulfill 

this guideline. 

Results from lower 

tier studies should 

inform the conduct 

of the field test to 

address remaining 

uncertainties. 

Pending the results 

of lower tier 

studies (adult 

honey bee acute 

oral, chronic adult 

honey bee, acute 

and chronic 

larval), a field 

testing study may 

not be needed to 

complete the risk 

assessment for 

pollinators for 

conventional uses. 

A protocol should 

be submitted prior 

to test initiation.

This study is not 

needed to support 

antimicrobial uses.
Page 46 of 56

Table 13. Available Ecological Effects Data for Terrestrial Organisms Exposed to 

Tebuconazole and Remaining Data Gaps. 

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment

for 

conventional 

uses?

Are data needed 

to support 

antimicrobial 

uses?

Justification and 

Assumptions 

EPA will Make in 

Absence of Data

850.4100 Seedling 

Emergence 

and Seedling 

Growth

45821301

47299201

45821302

45280001

47567601

Supplemental

Supplemental

Supplemental

Supplemental

Supplemental

Yes1 No Definitive 

NOAEC values 

were not 

determined, 

therefore, 

additional Tier II 

testing is requested 

for monocots to 

support 

conventional uses. 

A definitive IC25 

and NOAEC value 

is available for 

dicot seedling 

emergence, so 

additional testing 

with dicots is not 

requested. This 

study is not needed 

to support 

antimicrobial uses.

850.4150 Vegetative 

Vigor

45821301

47567615

Supplemental

Supplemental

Yes1 No Definitive 

NOAEC values 

were not 

determined, 

therefore, 

additional Tier II 

testing is requested 

for monocots and 

dicots to support 

conventional uses.

This study is not 

needed to support 

antimicrobial uses.

1 It is noted that while Tier II (dose-response) testing is preferred, if Tier I testing criteria as outlined in 

OCSPP 850.4100 and 850.4150 are met for all tested species, then Tier II testing may not be necessary.
Page 47 of 56

12. References 

MRID 44108304. Fritz, R. (1988) Adsorption/Desorption of FOLICUR (HWG 1608) on Soil: Lab 

Project Number: 1310222/1: 100101. Unpublished study prepared by Bayer Corp. 48 p.

MRID 46841601. Brooks, K. (2005) Copper and Tebuconazole Loss Rates from Southern Pine 

Treated to a Retention of 0.246 Pounds Per Cubic Foot with Copper Azole Type B (CA-B) 

Preservative. Unpublished study prepared by Aquatic Environmental Sciences and Battelle Marine 

Sciences Lab. 332 p.

MRID 48901607. Muchow, T. (2012) AWPA E11 Leachability Testing. Project Number:

OSMOSE/2012/21, 10/0504. Unpublished study prepared by Timber Products Inspection. 9p.

United Nations Food and Agriculture Organization. Assessing soil contamination: A reference 

manual. http://www.fao.org/docrep/003/x2570e/x2570e06.htm

U.S. EPA. August 30, 2006. Review of Leaching Data For Southern Pine Treated With Copper 

Azole Type B (CA-B) Preservative. Milano, T. D330143.

USEPA, 2015. BEAD Chemical Profile for Registration Review: Tebuconazole (128997). Office 

of Pesticides Program, Biological and Economic Analysis Division. Arlington, VA. 

USEPA, 2014a. Guidance for Assessing Pesticide Risks to Bees. Office of Pesticide Programs, 

USEPA, Washington D.C. Health Canada Pest Management Regulatory Agency, Ottawa, ON, 

Canada. California Department of Pesticide Regulation, Sacramento, CA. June 23, 2014.

U.S. EPA, Office of Pesticide Programs, Antimicrobial Division, Risk Assessment and Science 

Support Branch. August 4, 2014. Conceptual Models for Environmental Exposure Pathways of 

Antimicrobial Pesticides. EPA-HQ-OPP-2014-0638. 

http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2014-0638-0002

Yu, L, Chen, M, Liu, Y, et al. (2013) Thyroid endocrine disruption in zebrafish larvae following 

exposure to hexaconazole and tebuconazole. Aquat. Toxicol. 138: 35-42.
Page 48 of 56

Appendix A. Toxicity Data for Tebuconazole

Table A.1 Summary of Aquatic Toxicity Studies for Tebuconazole (TGAI)

Taxonomic 

Group

Study 

Type Tested Species

Toxicity Value

(95% conf. 

intervals)

(mg a.i./L)

Acute Toxicity 

Classification

Source

(Study Classification)

Comments

Freshwater 

fish1

Acute

Rainbow trout 

(Oncorhynchus 

mykiss)

96-Hr LC50 = 2.27 

(1.59-3.31)

Slope: 3.25

Moderately 

toxic

46919204 (Supplemental); 

Sublethal effects observed at 

≥0.95 ppm (no effects at 0.46 

ppm)

96-Hr LC50 = 4.4

(3.8-5.2)

Slope: 6.4

Moderately 

toxic

40700911 (Acceptable); 

Sublethal effects observed at 

≥2.5 ppm (no effects at 1.5 

ppm)

Bluegill (Lepomis 

macrochirus)

96-Hr LC50 = 5.7

(4.2-6.4)

Slope: NA

Moderately 

toxic

40700912 (Acceptable)

Sublethal effects observed at 

all test concentrations ≥1.4

ppm 

Chronic 

Fathead minnow 

(Pimephales 

promelas)

NOAEC = 0.011 NA

48109802 (Supplemental) 

Based on reduction in female 

growth (fish sexual 

development test); LOAEC 

0.022 ppm

Rainbow trout 

(Oncorhynchus 

mykiss)

NOAEC = 0.012 NA

40700914 (Acceptable) 

Based on reduction larval 

hatch (early life-stage study); 

LOAEC 0.025 ppm

Fathead minnow 

(Pimephales 

promelas)

No effect = 0.019 NA

48688301 (Satisfies) No 

effect on survival, growth 

reproduction at highest conc. 

Tested (fish short-term 

reproduction assay)

Freshwater 

invertebrates

Acute

Water Flea 

(Daphnia magna)

48-Hr EC50 = 2.88 

(2.1-3.9)

Slope = 2.38

Moderately 

toxic

46919205 (Acceptable); no 

effects observed at 0.49 ppm

48-Hr EC50 = 4.0

(3.4-4.8)

Slope = 3.8

Moderately 

toxic

46919205 (Acceptable); no 

effects observed at 0.74 ppm

Chronic 21-d NOAEC = 

0.120 NA

40700915 (Acceptable) 

Based on reduction in 

parental body length and 

reproduction; LOAEC = 

0.230 ppm

Estuarine/ 

marine fish

Acute

Sheepshead 

minnow 

(Cyprinodon 

variegatus)

96-hr LC50 = 5.9 

(5.3-7.0)

Slope: NA

Moderately 

toxic

40995904 (Acceptable)

sublethal effects observed at 

all test concentrations ≥1.2 

ppm

Chronic NOAEC = 0.019 NA

43009601 (Supplemental) 

Based on reduction in 

offspring body length (fish 

life-cycle test); 

LOAEC=0.044 ppm
Page 49 of 56

NOAEC = 0.022 NA

42038202 (Acceptable) 

Based on reduction in body 

weight (early life-stage test); 

LOAEC=0.048 ppm

Estuarine/

marine 

invertebrates

Acute Mysid shrimp

(Americamysis 

bahia)

96-hr LC50 = 

0.49 (0.33-0.66)

Slope: 2.3

Moderately 

toxic

48587107 (Acceptable)

sublethal effects observed at 

all test concentrations ≥0.3 

ppm

Chronic NOAEC = 0.035 NA

42038201 (Supplemental)

Based on reduction in 

reproduction (life-cycle test)

Acute

Eastern Oyster 

(Crassostrea 

virginica)

96-hr EC50 = 2.7

(2.5-3.0)

Slope: NA

Moderately 

toxic

48587107 (Acceptable); no 

effects observed at 1.7 ppm

Aquatic 

plants and 

algae

Vascular Duckweed 

(Lemna gibba)

EC50 = 0.151

(0.139-0.165)

EC05 =0.034 N/A 44246901 (Acceptable)

Nonvascular

Green Algae 

(Selenastrum 

capricornutum)

EC50 = 2.73 (2.33-

3.19)

NOAEC = 1.24 N/A 42905401 (Acceptable)

Green Algae 

(Selenastrum

capricornutum)

EC50 = 2.83 (2.41-

3.02)

NOAEC =1.19 N/A 44079601 (Acceptable)

Green Algae

(Scenedesmus 

subspicatus )

EC50 = 1.45 (NA)

NOAEC 0.32 N/A 40995908 (Supplemental)

1 Freshwater fish may be surrogates for aquatic-phase amphibians.

Table A.2. Acute Formulation Toxicity Data (SC 400 (200+200) G with Tebuconazole for 

Aquatic Species

Species Acute Toxicity 

Value (mg 

product/L)

Acute Toxicity 

Value (mg 

tebuconazole/L)

Study ID / 

Classification

Daphnia magna 48-hr EC50 = 56.9 48-hr EC50 = 9.961 47567611 / 

Supplemental

Rainbow trout 96-hr LC50 = 21.7 96-hr LC50 = 3.81 47567612 / 

Supplemental

Lemna gibba 7-d EC50 = 4.3 7-d EC50 = 0.762 47567616 / Acceptable

Lemna gibba 7-d EC50 = 0.73 7-d EC50 = 0.132 47567617 / Acceptable

Green algae 72-hr EC50 = 11 72-hr EC50 = 1.91 47567618 

/Supplemental

1 Based on 17.5% tebuconazole

2 Based on 17.8% tebuconazole
Page 50 of 56

Table A.3. Summary of Terrestrial Toxicity Studies for Tebuconazole 

Taxonomic 

Group

Study Type Tested Species Toxicity 

Value

Acute Toxicity 

Classification 

Source

(Study Classification)

Comments

Birds1

Acute

Bobwhite quail 

(Colinus. 

virginianus)

21-D LD50 

1988 mg 

a.i./kg-bw

Slightly Toxic

40700905 (Acceptable)

Reduced body weight at 

720 ppm (no effect at 432). 

Sub-acute 

dietary

8-D LC50 ≥ 

5000 mg 

a.i./kg-diet 

Practically nontoxic

40700907 (Acceptable)

Mortality at ≥2500 ppm; 

reduced body weight gain 

at all concentrations (no 

effect <325 ppm)

Chronic

NOAEC = 

73.5 mg 

a.i./kg-diet N/A

40700910 (Acceptable) No 

effects at highest 

concentration tested

NOAEC 

<156 mg 

a.i./kg-diet NA

41624201 (Acceptable); 

reduction in offspring body 

weight

Sub-acute 

dietary

Mallard duck (Anas 

platyrhynchos )

8-D LC50 ≥ 

4816 mg 

a.i./kg-diet 

Practically nontoxic

40700908 (Acceptable)

No mortality; reduced body 

weight gain at limit test 

concentration

Chronic

NOAEC = 

75.8 mg 

a.i./kg-diet N/A

40700909 (Acceptable) No 

effects at highest 

concentration tested

NOAEC = 

320 mg 

a.i./kg-diet

NA

41818301 (Supplemental); 

based on reduced number 

of hatchling per pen at 611 

ppm (while lower than 

control, this endpoint is not 

significant when hatchlings 

compared to number of live 

21-d embryos)

Mammals

Acute Oral Mouse (Mus 

musculus)

2

LD50 1615 

mg a.i./kgbw 

Slightly toxic 42090006 (Acceptable)

Acute 

Inhalation

Laboratory rat 

(Rattus norvegicus)

LD50 >0.371 

mg/L NA

40700922 (Acceptable); 

dosing with aerosol for 4 

hours with a 14-d 

observation period

Chronic

2-gen 

NOAEC = 

300 mg 

ai/kg-diet

LOAEC = 

1000 mg 

ai/kg-diet

N/A

40700946 (Acceptable) 

Based on decreased 

maternal and pup body 

weight and decreased pup 

viability [NOAEC = 15 

mg/kg/day; LOAEC = 50 

mg/kg-day]

Insects Acute 

contact

Honey bee 

(Apis mellifera L.)

> 35 μg 

tebuconazole

/bee

Practically nontoxic

47567613 (Supplemental) 

(formulation in which 

tebuconazole 
Page 51 of 56

Table A.3. Summary of Terrestrial Toxicity Studies for Tebuconazole 

Taxonomic 

Group

Study Type Tested Species Toxicity 

Value

Acute Toxicity 

Classification 

Source

(Study Classification)

Comments

Acute Oral

10.9 μg 

tebuconazole

/bee

N/A

concentrations not 

measured; fluopyram other 

a.i.)

Acute 

contact

7.6 μg 

tebuconazole

/bee

Slightly toxic 48844515 (Acceptable) 

(formulation; 

flupyradifurone other a.i.) Acute Oral

1.5 μg 

tebuconazole

/bee

N/A

Subchronic

Earthworm (Eisenia 

fetida)

14-d LC50 = 

875 mg 

product/kgdw

NA

47567619 (Supplemental) 

(formulation- SC400 G; 

17.5% tebuconazole); 

LOAEC= 178 mg 

product/kg-dw 

(NOEC=100)

Chronic

28-d 

NOAEC= 30 

mg 

product/kgdw

NA

47567620 (Supplemental)

(formulation- SC400 G; 

17.5% tebuconazole); no 

effects, LOAEC > 30 mg 

product/kg-dw 

Chronic

Parasitoid wasp 

(Aphidius 

rhopalosiphi)

LR50 >3L 

product/ha NA

47567627 and 47567622 

(Supplemental)

(formulation- SC400 G; 

17.5% tebuconazole); based 

on product density rate is 3 

lbs product/Acre or 0.53 lb 

a.i./A

Chronic

Ladybird Beetle 

(Coccinella 

septempunctata)

LR50 >3L 

product/ha NA

47567627 (Supplemental)

(formulation- SC400 G; 

17.5% tebuconazole); based 

on product density rate is 3 

lbs product/Acre or 0.53 lb 

a.i./A

Chronic

Green Lacewing 

(Chrysoperla 

carnea)

LR50 >3L 

product/ha NA

47567627 (Supplemental)

(formulation- SC400 G; 

17.5% tebuconazole); based 

on product density rate is 3 

lbs product/Acre or 0.53 lb 

a.i./A

Chronic Predatory Mite 

(Typholdromus pyri)

LR50 >3L 

product/ha NA

47567621 (Supplemental)

(formulation- SC400 G; 

17.5% tebuconazole); based 

on product density rate is 3 

lbs product/Acre or 0.53 lb 

a.i./A

Terrestrial 

plants

Seedling 

Emergence

Dicot – tomato 

(Solanum 

lycopersicum)

21-D IC25 = 

0.045 lbs 

ai/acre

IC05 = 0.016 

lbs ai/acre 

N/A 47299201 (Supplemental)
Page 52 of 56

Table A.3. Summary of Terrestrial Toxicity Studies for Tebuconazole 

Taxonomic 

Group

Study Type Tested Species Toxicity 

Value

Acute Toxicity 

Classification 

Source

(Study Classification)

Comments

Monocot – wheat

(Triticum aestivum)

21-D IC25 > 

0.4 lbs 

ai/acre

NOAEC =

<0.4 lbs 

ai/acre

N/A

45821301 (Supplemental)

Dicot – tomato 

(Solanum 

lycopersicum)

21-D IC25 <

0.4 lbs 

ai/acre

NOAEC = 

<0.4 lbs 

ai/acre

N/A

Dicot – tomato 

(Solanum 

lycopersicum)

21-D IC25 =

0.089 lbs 

ai/acre

IC05 = 0.014

lbs ai/acre

N/A 45821302 (Supplemental)

Dicot – turnip 

(Brassica rapa)

21-D IC25 =

3.4 mg 

a.i./kg

NOAEC = 1 

mg a.i./kg

N/A

45280001 (Supplemental)

Monocot – Oat 

(Avena sativa)

21-D IC25 =

57 mg a.i./kg

NOAEC = 

10 mg a.i./kg

N/A

Dicot – cucumber 

(Cucumis sativus)

21-D IC25 <

0.18 lbs 

ai/acre

NOAEC 

<0.18 lbs 

ae/acre

N/A

47567614 (Supplemental)

Monocot –Oat 

(Avena sativa)

21-D IC25 >

0.18 lbs 

ai/acre

NOAEC > 

0.18 lbs 

ae/acre

Vegetative 

vigor

Dicot—Cucumber 

(Daucus carota)

21-D IC25 > 

0.4 lbs 

ai/acre

NOAEC = 

<0.4 lbs

ae/acre

N/A

45821301 (Supplemental)

(Monocot – wheat

(Triticum aestivum)

21-D IC25 > 

0.4 lbs 

ai/acre

NOAEC = 

<0.4 lbs 

ae/acre

N/A
Page 53 of 56

Table A.3. Summary of Terrestrial Toxicity Studies for Tebuconazole 

Taxonomic 

Group

Study Type Tested Species Toxicity 

Value

Acute Toxicity 

Classification 

Source

(Study Classification)

Comments

Dicot – Sunflower 

(Helianthus annuus 

L.)

21-D IC25 >

0.18 lbs 

ai/acre

NOAEC > 

0.18 lbs 

ae/acre

N/A

47567615 (Supplemental)

Monocot –Oat 

(Avena sativa)

21-D IC25 >

0.18 lbs 

ai/acre

NOAEC < 

0.18 lbs 

ae/acre

N/A

1 Birds represent surrogates for terrestrial-phase amphibians and reptiles. 2 The acute oral toxicity LD50 value with rats is 3352 mg/kg-bw (females) MRID 40700917
Page 54 of 56

Appendix B. Screening Level Models to Evaluate Potential Importance 

of Drinking Water and Inhalation Exposure Pathways to Birds and Wild 

Mammals

SIP (Screening Imbibition Program, v1.0) Inputs and Conclusions

Table 1. Inputs

Parameter Value

Chemical name tebuconazole

Solubility (in water at 25o

C; mg/L) 36

Mammalian LD50 (mg/kg-bw) 3352

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg-bw) 15

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Avian LD50 (mg/kg-bw) 1988

Avian test species northern bobwhite quail

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet)

Bobwhite quail NOAEC (mg/kg-diet) 73

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) 6.1920 6.1920

Adjusted toxicity value (mg/kg-bw) 2578.2262 11.5374

Ratio of exposure to toxicity 0.0024 0.5367

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 29.1600 29.1600

Adjusted toxicity value (mg/kg-bw) 1432.2139 7.7598

Ratio of exposure to acute toxicity 0.0204 3.7578

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.
Page 55 of 56

STIR (Screening Tool for Inhalation Risk, v. 1.0) Inputs and Conclusion

Non-definitive rat inhalation value used as definitive value

Input

Application and Chemical Information

Enter Chemical Name tebuconazole

Enter Chemical Use turf

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) 308

Enter Chemical Vapor Pressure (mmHg) 1.30E-08

Enter Application Rate (lb a.i./acre) 1.3

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 1988

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 0.178

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 3352

Enter Lowest Rat Inhalation LC50 (mg/L) 0.317

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) 2.15E-04

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.71E-05

Adjusted Inhalation LD50 1.05E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 2.58E-05 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 1.37E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 1.31E-01 Proceed to Refinements

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 2.15E-04

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.40E-05

Adjusted Inhalation LD50 1.89E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.80E-06 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 1.73E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 9.15E-03 Exposure not Likely Significant

**NOTE**: When entering values, pres 

in order to update linked cells.
Page 56 of 56

Appendix C. TerrPlant results

TerrPlant v. 1.2.2

Green values signify user inputs (Tables 1, 2 and 4). 

Input and output guidance is in popups indicated by red arrows.

Chemical Name

PC code

Use

Application Method

Application Form 

Solubility in Water (ppm)

Input Parameter Symbol Value Units

Application Rate A 1.3 lb ai/A

Incorporation I 1 none

Runoff Fraction R 0.02 none

Drift Fraction D 0.01 none

Equation EEC

(A/I)*R 0.026

(A/I)*R*10 0.26

A*D 0.013

((A/I)*R)+(A*D) 0.039

((A/I)*R*10)+(A*D) 0.273

Plant type EC25 NOAEC EC25 NOAEC 

Monocot 0.4 0.4 0.4 0.4

Dicot 0.4 0.4 0.4 0.4

Plant Type Listed Status Dry Semi-Aquatic Spray Drift

Monocot non-listed <0.1 0.68 <0.1

Monocot listed <0.1 0.68 <0.1

Dicot non-listed <0.1 0.68 <0.1

Dicot listed <0.1 0.68 <0.1

Description

Total for semi-aquatic areas

Table 1. Chemical Identity.

tebuconazole

golf turf

Table 2. Input parameters used to derive EECs.

ground

Spray

35

128899

Table 3. EECs for tebuconazole. Units in lb ai/A.

Runoff to dry areas

Runoff to semi-aquatic areas

Spray drift

Total for dry areas

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.

Seedling Emergence Vegetative Vigor

Table 5. RQ values for plants in dry and semi-aquatic areas exposed to tebuconazole through runoff 

and/or spray drift.*

Table 4. Plant survival and growth data used for RQ derivation. Units are in lb ai/A.