UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

Date: January 3 1 , 20 13 

MEMORANDUM 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Tebuconazole: Human Health Risk Assessment for Tolerance Increases Based 

on Submission of Condition of Registration Requirements for Barley and 

Cantaloupe; and Crop Group Expansion for Fruiting Vegetable Crop Group 8-10. 

PC Code: 128997 

Decision No.: 464543 

Petition No.: 2E8012 

Risk Assessment Type: Single Chemical/ 

Aggregate 

TXRNo.: NA 

MRIDNo.: NA 

DP Barcode: D402457 

Registration No.: 264-752, 264-748 

Regulatory Action: Tolerance Reassessment 

CaseNo.: NA 

CAS No.: 107534-96-3 

40 CFR: §180.474 

FROM: Barry O'Keefe, Senior Biologist IJ~ 0 :J/.4 

Meheret Negussie, Chemist ffi:J!y 0 '/( ~ 

Whang Phang, Senior Toxicologist frt:;'~ 

Risk Assessment Branch III F (X 

Health Effects Division (7509P) 

THROUGH: JeffDawson, Acting Branch Chief 

Risk Assessment Branch III 

Health Effects Division (7509P) 

TO: Sidney Jackson, RM Team 05 

Introduction 

Risk Integration, Minor Use and Emergency Response Branch 

Registration Division (7505P) 

The Interregional Research Project No. 4 (IR-4) submitted additional field trial data (for barley 

and cucurbits) as required to satisfy previous conditions of registration. The IR-4 also requested 

an expansion of the established tolerance for the fruiting vegetables, group 8. The Registration 

Division (RD) requested that the HED evaluate toxicology and residue chemistry data and 

conduct dietary and aggregate exposure and risk assessments, as needed, to estimate the risk to 

human health resulting from the changes in tolerances. Since no new uses, or changes to existing 

Page 1 of39 
uses, are being proposed by these actions, the tebuconazole use pattern is unchanged. Therefore, 

new occupational and residential risk assessments are not needed. HED has however, conducted 

new dietary and aggregate risk assessments to reflect the changes in tolerances. 

A summary of the findings and an assessment of human risk resulting from these changes in 

tolerances of tebuconazole are provided in this document. The risk assessment was provided by 

Barry O'Keefe, the hazard characterization by Whang Phang, the residue chemistry data review 

and the dietary assessment by Meheret Negussie. The drinking water assessment was provided 

by William Eckel of the Environmental Fate and Effects Division (EFED). 

Page 2 of39 
Page 3 of 39

Table of Contents

1.0 Executive Summary .......................................................................................................... 5

2.0 Regulatory Conclusions and Recommendations............................................................ 8

2.1 Data Deficiencies/Conditions of Registration..................................................... 8

2.2 Tolerance Considerations..................................................................................... 8

2.2.1 Enforcement method ................................................................................ 8

2.2.2 International Harmonization................................................................... 8

2.2.3 Recommended Tolerances........................................................................ 9

2.2.4 Revisions to Petitioned-For Tolerances ................................................ 10

2.3 Label Modifications............................................................................................ 10

3.0 Ingredient Profile ............................................................................................................ 10

3.1 Summary of Proposed Uses................................................................................ 10

3.2 Structure and Nomenclature ............................................................................. 10

3.3 Physical and Chemical Properties..................................................................... 10

3.4 Anticipated Exposure Pathways........................................................................ 10

3.5 Consideration of Environmental Justice .......................................................... 11

4.0 Hazard Characterization/Assessment........................................................................... 11

4.1 Toxicology Studies Available for Analysis........................................................ 11

4.2 Summary of Toxicological Effects (including ADME and Absorption) ........ 11

4.3 Safety Factor for Infants and Children (FQPA Safety Factor)...................... 13

4.3.1 Completeness of Toxicology Database .................................................. 13

4.3.2 Evidence of Neurotoxicity ...................................................................... 13

4.3.3 Evidence of Sensitivity/Susceptibility in the Developing or Young 

Animal.................................................................................................................. 13

4.3.4 Residual Uncertainty in the Exposure Database.................................. 14

4.4 Toxicity Endpoint and Point of Departure Selections..................................... 14

4.4.1 Dose-Response Assessment .................................................................... 16

4.4.2 Recommendation for Combining Routes of Exposures for Risk 

Assessment........................................................................................................... 16

4.4.3 Cancer Classification and Risk Assessment Recommendation .......... 17

5.0 Dietary Exposure/Risk Characterization ..................................................................... 17

5.1 Pesticide Metabolism and Environmental Degradation.................................. 17

5.1.1 Metabolism in Primary and Rotational Crops..................................... 17

5.1.2 Metabolism in Livestock......................................................................... 17

5.1.3 Drinking Water Residue Profile ............................................................ 18

5.1.4 Food Residue Profile............................................................................... 19

5.2 Dietary Exposure and Risk ................................................................................ 21

5.2.1 Acute Dietary Exposure/Risk................................................................. 22

5.2.2 Chronic Dietary Exposure/Risk............................................................. 23

6.0 Residential (Non-Occupational) Exposure/Risk Characterization ............................ 24

6.1 Residential Handler Exposure/Risk Characterization.................................... 25

6.2 Residential Post-Application Exposure and Risk Characterization .............. 25

6.3 Other (Spray Drift, etc.) ..................................................................................... 26

7.0 Aggregate Risk Assessments and Risk Characterization............................................ 27

7.1 Acute & Chronic Aggregate Risk...................................................................... 27

7.2 Short-Term Aggregate Risks............................................................................. 27
Page 4 of 39

8.0 Cumulative Risk Characterization/Assessment........................................................... 29

9.0 References........................................................................................................................ 30

Appendix A: Toxicology Assessment ....................................................................................... 32

Appendix B: EPA Review of Human Research ...................................................................... 37

Appendix C: Structure, Nomenclature, and Physical and Chemical Properties................. 38

Appendix D: International Residue Limit Status................................................................... 39
Page 5 of 39

1.0 Executive Summary

Tebuconazole is a triazole fungicide currently registered for disease control on a variety of fruit 

and field crops. The triazoles act by inhibiting C14-demethylase, an enzyme which plays a role 

in sterol production in fungi. 

This document evaluates requests from IR-4 and Bayer CropScience (Bayer) to 

The IR-4, on behalf of the Agricultural Experiment Stations of California, Idaho, Oklahoma, 

Oregon, South Carolina, Tennessee, Texas and Washington previously submitted a request for

amended registration of the 3.6 lb ai/gal suspension concentrate (SC) (EPA Reg. No. 264-752; 

Folicur 3.6 F®) to add uses on cucurbit vegetables; and tolerances were proposed under PP# 

9E3045. The submitted data were evaluated by HED1. Field trials were conducted on the Crop 

Group 9 representative crops: squash (summer), cucumbers, and cantaloupe. As a condition of 

registration, HED required additional crop field trial data on melons (two trials in Region 10, one 

trial each in Region 2 and in Region 5, with a pre-harvest interval (PHI) of 3 days, or two 

additional field trials in Region 10, with a revised label specifying a PHI of 6 days). 

Currently, the IR-4 requests amending the established tolerances for the residues of the fungicide 

tebuconazole on cucurbit vegetables from 0.09 ppm to 0.4 pm, on barley grain from 0.15 ppm to 0.3 

ppm, and expanding the fruiting vegetables, group 8 to fruiting vegetables, group 8-10.

Bayer CropScience (Bayer) previously submitted a request for amended registration of the 3.6 lb 

ai/gal SC (EPA Reg. No. 264-752; Folicur 3.6 F®) to add use on barley; tolerances were 

proposed under PP# 7F4895. The submitted data were evaluated by HED2. Additional crop 

field trial data were required for barley grain, hay, and straw from regions 10 and 11, 

accompanied by concurrent storage stability data on barley straw. 

IR-4 has now submitted three crop field trials on barley in the United States (US) encompassing 

North American Free Trade Agreement (NAFTA) Growing Zones 10 and 11during the 2009 and 

2010 growing season and two field trials on melons conducted during the 2009 growing season in

California (EPA region 10) conducted at PHI of 6-7 days.

Toxicity/Hazard

The toxicological database for tebuconazole is essentially complete with the exception of an 

immunotoxicity study, which is currently under review. A preliminary evaluation shows no concerns, 

i.e., the results of the immunotoxicity study will not alter the values of the points of departure (POD) 

currently selected for risk assessment. With repeated dosing, the main target organs are the liver, the 

adrenals, the hematopoetic system and the nervous system. Effects on these target organs were seen in 

both rodent and non-rodent species. In addition, ocular lesions are seen in dogs (including lenticular 

 

1 Tebuconazole. IR-4 Request for Tolerances on Cucurbits. Summary of Analytical Chemistry and Residue Data. 

Petition Number #9E6048. DP258559, G. Otakie, 7/20/06.

2

Tebuconazole on Barley Commodities. Summary of Analytical Chemistry and Residue Data. DP344178, S. 

Hummel, 4/10/08.
Page 6 of 39

degeneration and increased cataract formation) following subchronic or chronic exposure. The 

toxicological effects of tebuconazole are consistent with those of other triazole-derivative chemicals. 

In particular, developmental toxicity and hepatocellular tumors are effects common to a number of 

these pesticides. Reliable data show that it would be safe for infants and children to reduce the Food 

Quality Protection Act (FQPA) safety factor to 3x for all potential exposure scenarios. The level of 

concern (LOC) for residential risk is for margins of exposure (MOEs) less than 300, based on the 

uncertainty factors of 10x for interspecies extrapolation, 10x for intraspecies variation, and a 3x 

uncertainty factor to account for LOAEL to NOAEL extrapolation. 

Tebuconazole is considered a “possible human carcinogen, Group C.” For the purpose of 

carcinogenic risk assessment, the chronic risk assessment is considered protective of any cancer 

effects; therefore, a separate quantitative cancer risk assessment is not required. 

Tebuconazole has low acute toxicity by the oral and dermal routes of exposure (Toxicity 

Category III), and moderate toxicity by the inhalation route (Toxicity Category II). It is not a 

dermal sensitizer, nor a dermal irritant; however, it is slightly, to mildly irritating to the eye.

Drinking Water

Since new uses, or changes to existing uses, are not being proposed by these actions, the 

estimated drinking water concentrations (EDWCs) from the latest drinking water assessment 

conducted by the Environmental Fate and Effects Division (EFED) were used and incorporated 

directly into the acute and chronic dietary assessments. The EDWCs are based on the maximum 

application rates specified on the existing labels. The surface water model estimates resulted in 

the highest acute EDWC of 96.6 μg/L from the existing use on turf; however, a 30-year 

distribution of daily surface water concentrations based on this turf use was incorporated into the 

acute dietary assessment. The highest chronic EDWC of 59 μg/L, from the existing use on 

commercial ornamentals, was incorporated into the chronic dietary assessment. The assessment 

was performed using Tier II (PRZM/EXAMS) modeling for surface water and Tier I (SCIGROW) for ground water.

Dietary Exposure (food and drinking water)

Refined acute and chronic dietary (food and drinking water) exposure analyses were performed 

for tebuconazole. The analyses indicate that acute and chronic dietary exposure to tebuconazole 

from food and drinking water are below HED’s LOC. Combined acute dietary exposure from 

food and drinking water at the 99.9th percentile of exposure is estimated to be 0.0095 mg/kg/day 

for the general U.S. population, equivalent to 33% of the acute population adjusted dose (aPAD). 

The population subgroup with the highest estimated acute dietary exposure to tebuconazole is 

children 1-2 years old, with an estimated exposure at the 99.9th percentile of 0.016 mg/kg/day, 

equivalent to 55% of the aPAD. Chronic dietary exposure estimates for food and drinking water 

are below HED’s LOC for all population subgroups. The chronic dietary exposure from food 

and drinking water is estimated at 0.0026 mg/kg/day for the general U.S. population (9% of the 

chronic population adjusted dose (cPAD)) and 0.0042 mg/kg/day (14% of the cPAD) for 

children 1-2 years old, the population subgroup with the highest estimated dietary exposure to 

tebuconazole.
Page 7 of 39

Dietary Assessment of Free Triazole and its Conjugates

Tebuconazole is among the group of pesticides which generate the common triazole metabolites 

1,2,4-triazole (T), triazolylalanine (triazole alanine; TA), triazolylacetic acid (triazole acetic acid; 

TAA), and triazolylpyruvic acid (TP). These triazole residues have been evaluated for the entire 

class of triazole compounds. In connection with the pending tolerance increases for barley, grain

and vegetable, cucurbits, group 9, HED has reviewed the previous triazole dietary assessments to 

include these changes to tebuconazole. HED has determined that dietary risk (food and drinking 

water) remains unchanged and below HED’s LOC. There are no dietary exposure considerations 

for the common triazole metabolites that would preclude granting the tolerance increase requests.

Residential Exposure

No new residential uses are being requested at this time. However, adults, adolescents and 

children may be exposed to tebuconazole from its currently registered uses on turf, ornamentals

and treated wood surfaces.

Aggregate Risk

The dietary route (food and water) alone is relevant to assess acute and long-term aggregate 

exposure to tebuconazole; therefore, the dietary exposure and risk assessments described above 

evaluate aggregate exposure for these durations. However, there are residential uses of 

tebuconazole that result in short-term exposure that should be considered with background 

dietary exposure. The aggregate assessment results in MOEs that do not exceed the LOC of an 

MOE of 300 or less, and ranged from 310 to 1,500.

Updated Aggregate Assessment of Free Triazole & its Conjugates

HED has completed an updated aggregate human health risk assessment for 1,2,4-triazole and 

the conjugated triazole metabolites (TA, TAA and TP). The only revisions to the components of 

the previous aggregate exposure and risk estimates are to the dietary exposure estimates. For the 

common triazole metabolites, acute and chronic aggregate risks consist only of dietary 

components and, therefore, are equivalent to the dietary risk estimates. For short- and 

intermediate-term aggregate scenarios, the revised aggregate estimates are below HED’s level of 

concern.

Occupational Exposure and Risk

This document presents the risk assessment of the proposed tolerance increases of tebuconazole 

on cucurbits and barley. Occupational exposure from tebuconazole application to cucurbits and 

barley has been previously assessed. No new occupational uses are being requested at this time. 
Page 8 of 39

Environmental Justice Considerations

Potential areas of environmental justice concerns, to the extent possible, were considered in this 

human health risk assessment. Dietary and non-dietary exposures were considered.

Review of Human Research

This risk assessment relies in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide or other chemical. These studies (listed in Appendix B) have 

been determined to require a review of their ethical conduct, and have received that review.

2.0 Regulatory Conclusions and Recommendations

HED has reviewed the new cucurbits and barley residue field trials for tebuconazole. HED 

concurs with the IR-4’s proposal that the barley, grain tolerance be raised to 0.3 ppm and the 

vegetable, cucurbit, group 9 tolerance be raised to 0.4 ppm. Additionally, HED concurs that the 

tolerance on vegetable, fruiting, group 8 be expanded to vegetable, fruiting, group 8-10. 

The specific tolerance recommendations are discussed in Section 2.2.

2.1 Data Deficiencies/Conditions of Registration

There are no outstanding data deficiencies or conditions of registration that would preclude the 

establishment of the tolerance changes outlined in this document.

2.2 Tolerance Considerations

2.2.1 Enforcement method

The data collection and enforcement methods for tebuconazole were previously discussed 

(D373948, B. O’Keefe, 12/28/09). A gas chromatography/Nitrogen Phosphorus Detector 

(GC/NPD) enforcement method for determining tebuconazole residues is available and adequate 

(Method 101341). 

2.2.2 International Harmonization

The US and Canadian tolerance expressions for plants and livestock are in harmony; whereas,

the US and Codex tolerance expressions are in harmony for plants only. The Codex tolerance 

expression for livestock commodities includes parent only. Residue definition in the US

includes parent and the metabolite; therefore, harmonization of tolerances/MRLs (maximum 

residue limits) for livestock commodities is not possible. 

Codex MRLs have been proposed for residues of tebuconazole in/on barley grain at 2 ppm and 

barley straw and fodder, dry at 40 ppm. The US tolerances at 0.3 ppm for barley grain and at 3.5 

ppm for barley straw are not in harmony. The US tolerances cannot be harmonized with the 
Page 9 of 39

Codex MRL’s since there are significant differences in MRL values. There is a Canadian MRL 

on barley grain at 0.15 ppm which is also not in harmony with the US. 

Codex MRLs are established on cucumber (0.15 ppm), summer squash (0.2 ppm), melons 

(except watermelon) (0.15 ppm), sweet peppers (1 ppm), and tomatoes at 0.7 ppm. 

Harmonization is an issue for cucurbit vegetables (Crop Group 9) and fruiting vegetables (Crop 

group 8) since tolerances are established at 0.4 ppm and 1.3 ppm, respectively. Harmonization 

cannot be achieved since Codex MRLs are established on individual crops rather than on crop 

groups and have lower MRLs. There are no Canadian tebuconazole MRLs for any cucurbit 

vegetables and fruiting vegetables. 

An International Residue Limit (IRL) status sheet is appended to this document as Appendix D. 

2.2.3 Recommended Tolerances 

The existing uses and the submitted data support the following tolerances for residues of 

tebuconazole in/on the following raw agricultural commodities.

Barley, grain.............................................................0.3 ppm

Barley, hay ...............................................................7.0 ppm

Barley, straw ............................................................3.5 ppm

Vegetable, cucurbit, group 9....................................0.4 ppm

Vegetable, fruiting, group 8-10................................1.3 ppm

Note to RM: The established tolerance on barley grain at 0.15 ppm should be changed to 

0.3 ppm and on cucurbit vegetables at 0.09 ppm should be changed to 0.4 ppm in 40 CFR

§180.474(a) .

Note to RM: The established tolerance on the vegetable fruiting group 8 at 1.3 ppm can be 

extended to the vegetable fruiting group 8-10 at 1.3 ppm.

Note to RM: In conjunction with the establishment of the vegetable fruiting group 8-10 

tolerance, the existing tolerance for okra needs to be removed from 40 CFR §180.474(a) .

The established and changed tolerances relevant to the current petition are summarized in Table 

2.2.3 below. 

Table 2.2.3. Tolerance Summary for Tebuconazole.

Crop Commodity Established 

Tolerance 

(ppm)

Proposed 

Tolerance 

(ppm)

Recommended 

Tolerance 

(ppm)

Comments

(Correct Commodity Definition)

Barley, grain 0.15 0.3 0.3 The established tolerance (0.15 ppm) 

should be increased to 0.3 ppm.

Barley, hay 7.0 7.0 7.0 Adequate residue data are available; 

the established tolerance is sufficient.

Barley, straw 3.5 3.5 3.5 Adequate residue data are available; 

the established tolerance is sufficient.
Page 10 of 39

Table 2.2.3. Tolerance Summary for Tebuconazole.

Crop Commodity Established 

Tolerance 

(ppm)

Proposed 

Tolerance 

(ppm)

Recommended 

Tolerance 

(ppm)

Comments

(Correct Commodity Definition)

Vegetable, 

cucurbit, group 9 0.09 0.4 0.4 The established tolerance (0.09 ppm) should be increased to 0.4 ppm.

Vegetable, fruiting, 

group 8-10 1.3 1.3 1.3 Adequate residue data are available; the established tolerances are 

sufficient.

Vegetable, fruiting, group 8-10 Okra 1.2 None None

2.2.4 Revisions to Petitioned-For Tolerances

HED concludes that there are no revisions needed to the petitioned for tolerance changes. 

2.3 Label Modifications

There are no label modifications needed.

3.0 Ingredient Profile

3.1 Summary of Proposed Uses

Te IR-4 submitted additional field trial data (for barley and cucurbits, respectively) as required to 

satisfy previous conditions of registration. IR-4 also requested an expansion of the established 

tolerance for the fruiting vegetables, group 8. Therefore, no new uses, or changes to existing 

uses, are being proposed by these actions. 

3.2 Structure and Nomenclature

Structure and nomenclature are reported in Appendix C.

3.3 Physical and Chemical Properties

The physicochemical properties of tebuconazole are reported in Appendix C. 

3.4 Anticipated Exposure Pathways

Humans may be exposed through their diet from applications to agricultural crops. Humans may 

also be exposed to residues in drinking water, since applications may result in residues reaching 

surface and ground water sources. There are residential uses of tebuconazole, so exposure to 

tebuconazole may occur in residential or non-occupational settings during application and as a 

result of residues present after application. In an occupational setting, handlers may be exposed 

while handling the pesticide prior to application, as well as during application. There is also a 

potential for post-application exposure for workers re-entering treated sites. 
Page 11 of 39

Risk assessments have been completed for the existing uses of tebuconazole. This risk 

assessment considers all of the aforementioned exposure pathways based on the proposed 

changes in tolerances of tebuconazole, but also considers existing uses of tebuconazole, 

particularly in the dietary exposure assessment. 

3.5 Consideration of Environmental Justice

Potential areas of environmental justice concerns, to the extent possible, were considered in this 

human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal Actions 

to Address Environmental Justice in Minority Populations and Low-Income Populations," 

(http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf. As a part of every pesticide risk 

assessment, OPP considers a large variety of consumer subgroups according to well-established 

procedures. In line with OPP policy, HED estimates risks to population subgroups from 

pesticide exposures that are based on patterns of that subgroup’s food and water consumption, 

and activities in and around the home that involve pesticide use in a residential setting. 

Extensive data on food consumption patterns are compiled by the U.S. Department of 

Agriculture’s National Health and Nutrition Examination Survey, What We Eat in America, 

(NHANES/WWEIA) and are used in pesticide risk assessments for all registered food uses of a 

pesticide. These data are analyzed and categorized by subgroups based on age, season of the 

year, ethnic group, and region of the country. Additionally, OPP is able to assess dietary 

exposure to smaller, specialized subgroups and exposure assessments are performed when 

conditions or circumstances warrant. Whenever appropriate, non-dietary exposures based on 

home use of pesticide products and associated risks for adult applicators and for toddlers, youths, 

and adults entering or playing on treated areas post-application are evaluated. Further 

considerations are currently in development as OPP has committed resources and expertise to the 

development of specialized software and models that consider exposure to bystanders and farm 

workers as well as lifestyle and traditional dietary patterns among specific subgroups.

4.0 Hazard Characterization/Assessment

Tebuconazole is a member of the triazole fungicide group. The triazoles act by inhibiting, C14-

demethylase, an enzyme which plays a role in sterol production in fungi. Sterols, such as 

ergosterol, are needed for membrane structure and function, making them essential for the 

development of functional cell walls. Hence, inhibition of sterol production leads to abnormal 

fungal growth and eventually death. 

4.1 Toxicology Studies Available for Analysis

The toxicity studies on tebuconazole are essentially complete; an immunotoxicity study has been 

submitted and is under review. A preliminary evaluation of the immunotoxicity study shows no 

concerns, i.e., the results will not alter the values of the points of departures currently selected for 

risk assessment. Refer to the last HED risk assessment for further details (DP384949, K. Rury, 

5/24/11).

4.2 Summary of Toxicological Effects (including ADME and Absorption)
Page 12 of 39

The toxicological profile of tebuconazole is presented in the Appendix A. With repeated dosing, 

the main target organs are the liver, the adrenals, the hematopoetic system and the nervous 

system. Effects on these target organs were seen in both rodent and non-rodent species. In 

addition, ocular lesions are seen in dogs (including lenticular degeneration and increased cataract 

formation) following subchronic or chronic exposure (D256074 & D276447, S. Winfield, 

04/18/08).

Oral administration of tebuconazole caused developmental toxicity in all species evaluated (rat, 

rabbit, and mouse), with the most prominent effects seen in the developing nervous system. In 

developmental toxicity studies, these effects were manifested as increases in malformations of 

the nervous system and skull (including exencephaly and acrania, skull bone and vertebral 

anomalies). Similar types of malformations were seen in all species evaluated. The 

developmental toxicity studies, including the developmental neurotoxicity study, demonstrate 

increased susceptibility in developing fetuses both quantitatively and qualitatively. In the 

reproductive toxicity study, adverse effects on offspring were manifested only as decreased pup 

body weight. However, prolonged gestation and dystocia, as well as decreased offspring 

survival (fewer pups born alive, more stillborn pups, and more pup deaths during the first week 

after birth), were seen in the developmental neurotoxicity study. 

The results of the carcinogenicity study in mice showed that tebuconazole induced an increase in 

the incidence of hepatocellular adenomas, carcinomas and combined adenomas/carcinomas in 

male and female mice. Tebuconazole was classified as a Group C “possible human carcinogen”. 

Submitted mutagenicity studies did not demonstrate any evidence of mutagenic potential for 

tebuconazole.

The toxicological effects of tebuconazole are consistent with those of other triazole-derivative 

chemicals. In particular, developmental toxicity and hepatocellular tumors are effects common 

to a number of these pesticides. Tebuconazole also shares common metabolites with other 

chemicals in this group, including free triazole (1,2,4-triazole) and triazole-conjugated plant 

metabolites (such as triazole alanine). These common metabolites were the subject of a recent 

risk assessment document (D380512, B. O’Keefe, 05/24/11) updated to incorporate new uses of 

triazole-derivative fungicides.

It should be noted that tebuconazole has low acute toxicity by the oral or dermal route of 

exposure, and moderate toxicity by the inhalation route. It is not a dermal sensitizer or a dermal 

irritant; however, it is slightly to mildly irritating to the eye. 

Following oral administration to rats, tebuconazole was rapidly and extensively absorbed 

(approximately 98% of the administered dose), metabolized, and eliminated. At 72 hours postdosing, >94% of the administered radioactivity was recovered. Approximately 11-33% of the 

administered dose was eliminated in urine and 61-82% was eliminated in the feces. At sacrifice, 

total radioactivity in the body, excluding the GI tract, amounted to 0.3 to 0.5% of the 

administered dose. The data also showed that tebuconazole underwent enterohepatic circulation. 

Elimination via expired air accounted for 0.03% of the administered dose over a 72-hour 

collection period. A total of 10 compounds (metabolites) were identified in the excreta, 

amounting to 51-58% of the administered dose. The parent compound was present in relatively 
Page 13 of 39

small amount (0.5-2.2% of the administered dose).

Previously, a dermal absorption factor of 23.1% was derived from a dermal absorption study in 

the monkey. HED recently re-examined the data from this study and determined the absorption 

factor appropriate for route-to-route extrapolation is 13%, rather than 23.1% (DP397518, B. 

O’Keefe, 4/30/12), and the DER has been updated with a new Executive Summary (DP399045, 

J. Ryman, 2/23/12). 

4.3 Safety Factor for Infants and Children (FQPA Safety Factor)

The RAB3 risk assessment team has determined that reliable data show that it would be safe for 

infants and children to reduce the FQPA safety factor to 3X for all potential exposure scenarios. 

That decision is based on the following findings (Sections 4.4.1 through 4.4.4.):

4.3.1 Completeness of Toxicology Database

The toxicity database for tebuconazole is considered complete. The registrant has submitted an 

immunotoxicity study in rats, and the study is currently under review. With preliminary 

evaluation, tebuconazole tested up to 1000 ppm (78.4 mg/kg/day) produced no immunotoxicity 

under the conditions of this study.

4.3.2 Evidence of Neurotoxicity

Tebuconazole demonstrated neurotoxicity in the acute neurotoxicity study in rats; the LOAEL of 

100 mg/kg/day was based on increased motor activity in male and female rats and decreased 

footsplay in female rats; however, the subchronic neurotoxicity study was unacceptable due to 

inadequate dosing. Malformations indicative of nervous system development disruption were 

seen in developmental toxicity studies in mice, rats, and rabbits. Neurotoxicity was also seen in 

offspring in the developmental neurotoxicity study in rats the LOAEL of 8.8 mg/kg/day was 

based on decreases in body weights, decreases in absolute brain weights, changes in brain 

morphometric parameters, and decreases in motor activity. A NOAEL could not be established. 

However, the LOAEL (8.8 mg/kg/day) was employed as the point of departure in assessing the 

risk for all exposure scenarios, and the FQPA SF is retained as a UFL. A Benchmark Dose 

(BMD) analysis of the datasets relevant to the adverse offspring effects (decreased body weight 

and brain weight) seen at the LOAEL in the DNT study was conducted. All of the BMDLs 

(benchmark dose limit) modeled successfully on statistically significant effects are 1-2X lower 

than the LOAEL. The results also indicate that an extrapolated NOAEL is not likely to be 10X

lower than the LOAEL and that use of an UFL of 3X would not underestimate risk. Therefore, 

the analysis supports reducing the UFL from 10X to 3X. Using an UFL of 3X in risk assessment 

(8.8 mg/kg/day ÷ 3x = 2.9 mg/kg/day) is further supported by other studies in the tebuconazole 

toxicity database [with the lowest NOAELs being 3 and 2.9 mg/kg/day, from a developmental 

toxicity study in mice and a chronic toxicity study in dogs, respectively (respective LOAELs 10 

and 4.5 mg/kg/day)].

4.3.3 Evidence of Sensitivity/Susceptibility in the Developing or Young Animal
Page 14 of 39

Although there is qualitative evidence of increased susceptibility in the prenatal developmental 

studies in rats, the risk assessment team did not identify any residual uncertainties after 

establishing toxicity endpoints and traditional UFs to be used in the risk assessment of 

tebuconazole. The degree of concern for residual uncertainties for prenatal and/or postnatal 

toxicity is low.

4.3.4 Residual Uncertainty in the Exposure Database

EPA utilized a tiered approach in estimating exposure to tebuconazole. While some refinements 

were incorporated into dietary and residential exposure calculations, EPA is confident that the 

aggregate risk from exposure to tebuconazole in food, water and residential pathways will not be 

underestimated. The acute and chronic dietary exposure assessments incorporated refined 

estimates of residues in food commodities from reliable field trial data reflecting maximum use 

conditions, recent monitoring data from USDA’s Pesticide Data Program (PDP), and relevant 

market survey data on the percentage of crops treated. Estimated concentrations of tebuconazole 

in drinking water were incorporated into the chronic dietary analysis as the upper bound point 

estimate and into the probabilistic acute dietary analysis as a distribution. For the residential 

exposure pathway (ornamentals, golf course turf, and treated wood products), potential exposure 

resulting from tebuconazole outdoor uses in the residential setting was assessed using screeninglevel inputs that assumes an adult or child will come in contact with turf and other surfaces 

immediately after application. 

4.4 Toxicity Endpoint and Point of Departure Selections

At this time, the toxicity endpoints and points of departure previously selected for risk 

assessment (D256074 and D276447, S Winfield, 04/18/08) are valid and will be employed for 

this risk assessment. A full discussion of the endpoints selected for risk assessment may be 

found in the above referenced risk assessment. The summary of toxicity endpoints and points of 

departure are presented in Table 4.4.1.
Page 15 of 39

Based on the available toxicity database and the Agency's current practices, the inhalation risk 

for tebuconazole was assessed using an oral toxicity study. The Agency sought expert advice 

and input on issues related to this route to route extrapolation approach (i.e. the use of oral 

toxicity studies for inhalation risk assessment) from its Federal Insecticide, Fungicide, and 

Rodenticide Act Scientific Advisory Panel (SAP) in December 2009. The Agency received the 

SAP’s final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The Agency is in the 

Table 4.4.1. Summary of Toxicological Doses and Endpoints for Tebuconazole for Use in Dietary and NonOccupational Human Health Risk Assessments

Exposure/

Scenario

Point of 

Departure

Uncertainty/FQPA 

Safety Factors

RfD, PAD, Level 

of Concern for 

Risk Assessment

Study and Toxicological Effects

Acute Dietary 

(General 

Population, 

including Infants 

and Children)

LOAEL = 8.8 

mg/kg/day

UF = 300

UFA= 10x

UFH=10x

FQPA(UFL)= 3x

Acute RfD = 

0.029 mg/kg/day

aPAD = 0.029 

mg/kg/day

Developmental Neurotoxicity Study - Rat.

LOAEL = 8.8 mg/kg/day based on decreases in 

body weights, absolute brain weights, brain 

measurements and motor activity in offspring.

Chronic Dietary 

(All Populations)

LOAEL = 8.8 

mg/kg/day

UF = 300

UFA= 10x

UFH=10x

FQPA(UFL)= 3x

Chronic RfD = 

0.029

mg/kg/day

cPAD =0.029 

mg/kg/day

Developmental Neurotoxicity Study - Rat.

LOAEL = 8.8 mg/kg/day based on decreases in 

body weights, absolute brain weights, brain 

measurements and motor activity in offspring.

Incidental Oral 

Short-Term (1-30 

days)

LOAEL = 8.8 

mg/kg/day

UF = 300

UFA= 10x

UFH=10x

FQPA(UFL)= 3x

Residential LOC 

for MOE = 300

Developmental Neurotoxicity Study - Rat.

LOAEL = 8.8 mg/kg/day based on decreases in 

body weights, absolute brain weights, brain 

measurements and motor activity in offspring.

Dermal Short-Term 

(1-30 days)

LOAEL = 8.8 

mg/kg/day

UF = 300

UFA= 10x

UFH=10x

UFL= 3x

DAF = 13%

Residential LOC 

for MOE = 300

Developmental Neurotoxicity Study - Rat.

LOAEL = 8.8 mg/kg/day based on decreases in 

body weights, absolute brain weights, brain 

measurements and motor activity in offspring.

Inhalation ShortTerm (1-30 days)

LOAEL = 8.8 

mg/kg/day

UF = 300

UFA= 10x

UFH=10x

UFL= 3x

Residential LOC 

for MOE = 300

Developmental Neurotoxicity Study - Rat.

LOAEL = 8.8 mg/kg/day based on decreases in 

body weights, absolute brain weights, brain 

measurements and motor activity in offspring.

Cancer (oral, 

dermal, inhalation)

Classification: Group C- possible human carcinogen based on statistically significant increase in the incidence of 

hepatocellular adenoma, carcinoma, and combined adenoma/carcinomas in both sexes of NMRI mice. The chronic 

risk assessment is considered to be protective of any cancer effects; therefore, a separate quantitative cancer risk 

assessment is not required.

Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and used to mark the 

beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no observed 

adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UFA = extrapolation from animal to human 

(interspecies). UFH = potential variation in sensitivity among members of the human population (intraspecies). UFL = use of a LOAEL to 

extrapolate a NOAEL. FQPA SF = FQPA Safety Factor. PAD = population adjusted dose (a = acute, c = chronic). RfD = reference dose. 

MOE = margin of exposure. LOC = level of concern. N/A = not applicable. DAF = dermal absorption factor.
Page 16 of 39

process of evaluating the SAP report and may, as appropriate, re-examine and develop new 

policies and procedures for conducting inhalation risk assessments, including route to route 

extrapolation of toxicity data. If any new policies or procedures are developed, the Agency may 

revisit the need for an inhalation toxicity study for tebuconazole and/or a re-examination of the 

inhalation toxicity risk assessment.

4.4.1 Dose-Response Assessment

Some of the data relevant to this section have been discussed in Section 4.4.2, but they are 

essential details for this section as well. The repetition helps to emphasize that reducing the 

FQPA safety factor in the form of a UFL from 10X to 3X is protective of all the adverse effects 

demonstrated in the tebuconazole toxicity database. 

The tebuconazole risk assessment team selected the most sensitive and protective endpoints from 

the tebuconazole database (from the rat developmental neurotoxicity study) to employ in the risk 

assessment for acute and chronic dietary exposure scenarios and for relevant occupational and 

residential exposure scenarios following dermal, incidental oral and inhalation exposures. In this 

developmental neurotoxicity (DNT) study, the maternal NOAEL was 22.0 mg/kg/day and the 

LOAEL was 65 mg/kg/day based on decreased body weights, body weight gains, and food 

consumption, prolonged gestation with mortality; and an increased number of dead fetuses. The 

offspring LOAEL was 8.8 mg/kg/day (the lowest dose tested) based on decreases in body 

weights, decreases in absolute brain weights, changes in brain morphometric parameters, and 

decreases in motor activity. An offspring NOAEL was not established. BMD analyses were 

conducted using the critical datasets of the developmental neurotoxicity (DNT) study with 

tebuconazole (TXR# 0054776). The analyses do not provide a new POD for risk assessments. It 

does, however, provide scientific support for reducing the default 10X Uncertainty Factor 

applied to a LOAEL when a NOAEL is not identified in the critical study used in risk 

assessments. All of the BMDLs modeled successfully on statistically significant effects are 1-2X

lower than the established LOAEL. The results indicate that an extrapolated NOAEL is not 

likely to be 10X lower than the LOAEL and that use of an Uncertainty Factor of 3X would not 

underestimate risk. Using an UFL of 3X would yield a POD of 2.9 mg/kg/day (8.8 mg/kg/day ÷ 

3X = 2.9 mg/kg/day) which is further supported by the NOAELs established in other studies in 

the tebuconazole toxicity database [i.e., 3 and 2.9 mg/kg/day, from a developmental toxicity 

study in mice and a chronic toxicity study in dogs, respectively (respective LOAELs 10 and 4.5 

mg/kg/day)].

4.4.2 Recommendation for Combining Routes of Exposures for Risk Assessment

As per FQPA, 1996, when there are potential residential exposures to a pesticide, aggregate risk 

assessment must consider exposures from three major sources: oral, dermal and inhalation 

exposures. The toxicity endpoints selected for short-, intermediate- and long-term risk 

assessments are identical; the oral, dermal, and inhalation exposures can be combined due to the 

presence of a common toxicity endpoint.
Page 17 of 39

4.4.3 Cancer Classification and Risk Assessment Recommendation

The Carcinogenicity Peer Review Committee concluded that tebuconazole should be classified 

as a Group C - possible human carcinogen (TXR No. 0052724). This conclusion was based on 

results of a 91-week carcinogenicity study in NMRI mice (MRID 42175001, 42469301) in which 

the following effects were observed: 1) a statistically significant increase in the incidence of 

hepatocellular adenomas, carcinomas and combined adenomas/carcinomas in male mice both by 

positive trend and pairwise comparison at the highest dose tested (279 mg/kg/day); and 2) a 

statistically significant increase in the incidence of hepatocellular carcinomas and combined 

adenomas/carcinomas in female mice both by positive trend and pairwise comparison at the 

highest dose tested (366 mg/kg/day). The structural relationship of tebuconazole to at least six 

other triazole fungicides that also produce hepatocellular tumors in male and/or female mice 

supported the Committee's conclusion. These compounds include triadimefon, triadimenol, 

uniconazole, propiconazole, cyproconazole and etaconazole. For the purpose of carcinogenic 

risk assessment, the chronic risk assessment is considered to be protective of any cancer effects; 

therefore, a separate quantitative cancer risk assessment is not required.

5.0 Dietary Exposure/Risk Characterization

5.1 Pesticide Metabolism and Environmental Degradation

5.1.1 Metabolism in Primary and Rotational Crops

No new metabolism data were submitted with the subject petition. Adequate plant metabolism 

studies are available reflecting the metabolism of [14C] tebuconazole in grapes and [U14Ctriazole] tebuconazole in wheat and peanuts. The residue of concern in plants for tolerance and 

risk assessment is tebuconazole. Refer to the last HED risk assessment for further details 

(DP384949, K. Rury, 5/24/11).

5.1.2 Metabolism in Livestock

The nature of tebuconazole residues in livestock is adequately understood based on acceptable 

goat and poultry metabolism studies. The residues of concern in livestock commodities for the 

tolerance expression include both tebuconazole and free and conjugated t-butylhydroxy 

tebuconazole (HWG-2061). In addition to tebuconazole and free and conjugated t-butylhydroxy 

tebuconazole, triazole degradates may occur in livestock from the use of tebuconazole and other 

triazole pesticides. Exposure to these degradates was assessed independently as part of the 

triazole aggregate risk assessment, and therefore, need not be included as a residue of concern 

for risk assessment or tolerance expression in the tebuconazole risk assessment. 
Page 18 of 39

5.1.3 Drinking Water Residue Profile

The tebuconazole risk assessment team determined that the residue of concern in drinking water 

for this single chemical risk assessment is tebuconazole. The EDWCs for tebuconazole were 

calculated for ground and surface drinking water using the Tier II (PRZM/EXAMS) surface 

water modeling and Tier I (SCI-GROW) ground water modeling based on the proposed 

maximum use rates of tebuconazole on turf and ornamentals (DP385878, W. Eckel, 05/10/11). 

The drinking water models and their descriptions are available at the EPA internet site: 

http://www.epa.gov/oppefed1/models/water/. Surface water EDWCs were used in the dietary 

assessment, since they were higher than those for ground water. For the human health risk 

assessment, the highest relevant EDWCs are recommended. Water residues were incorporated in 

the Dietary Exposure Evaluation Model (DEEM-FCID) into the food categories “water, direct, 

all sources” and “water, indirect, all sources.”

Triazole degradates (1,2,4-triazole and triazole conjugates) may occur in drinking water from the 

use of tebuconazole and other triazole pesticides; thus, HED has conducted aggregate human 

health risk assessments for these degradates (DP403618, T. Morton, 08/01/12). The requested 

increases in tebuconazole tolerances did not result in an increase in dietary exposure; therefore,

the last dietary exposure analyses of the triazole metabolites have not changed.

Drinking Water Residues Used in the Dietary Assessment:

The entire 30-year distribution of estimated daily surface water concentrations based on 

tebuconazole being aerially applied to FL turf was used probabilistically for the acute 

assessment. For chronic dietary exposure assessment, the 1 in 10 yr annual mean (chronic) 

concentration of 59 μg/L was used, which was based on tebuconazole being aerially applied to 

commercial ornamentals.

Table 5.1.3.1 provides a summary of the estimated concentrations of tebuconazole in surface 

water. 

Table 5.1.3.1. Estimated Drinking Water Concentrations (EDWCs) Resulting from Applications of Tebuconazole

Scenario

Application 

Type/Annual Fungicide 

Application Rate

(kg ai/ha)

1 in 10 yr annual 

peak (μg/L)

1 in 10 yr annual 

mean (μg/L)

30 yr annual mean 

(μg/L)

FL Turf Aerially applied

1.65 x 3 = 4.95 96.6 a

51.4 33.7

Commercial 

Ornamentals simulated 

with PA Turf

Aerially applied

0.56 x 8 = 4.48 77.4 59.0 46.2

PA Apples Airblast

0.25 x 6 = 1.50 27.4 16.6 10.9

Bold values denote maximum Estimated Drinking Water Concentrations (EDWCs)

a: A 30-year distribution of daily surface water concentrations was used in the acute assessment
Page 19 of 39

Drinking Water Data for Free Triazoles

Residues of 1,2,4-triazole in drinking water were provided to HED by the Environmental Fate 

and Effects Division (DP320682, I. Maher, 02/28/06). EFED stated in electronic communication 

(F. Khan, 04/07/2011) that registered tebuconazole uses are covered by the previous drinking 

water assessment for 1,2,4-triazole.

Due to the inter-conversion between 1,2,4-triazole, triazole alanine, and triazole acetic acid that 

may occur in the environment, the residue estimates used in these assessments are a summation 

of all three residues and, therefore, represent an overestimate of actual concentrations of the 

common triazole metabolites in drinking water. The Tier II PRZM/EXAMS (surface water) and 

SCIGROW (ground water) residue estimates are summarized in Table 5.1.3.2. HED notes that 

there were no detects of 1,2,4-triazole in any of the 271 water samples analyzed by PDP, with a 

limit of quantification of 730 parts-per-trillion (0.73 ppb). The surface water estimates are 

significantly greater than those for ground water, and were used in the assessments for free 

triazole as well as the conjugated metabolites. 

Table 5.1.3.2. Summary of Estimated Drinking Water Concentrations of 1,2,4-Triazole.

Exposure Duration Surface Water Concentration, ppm Ground Water Concentration, ppm

Acute 0.041 0.001

Chronic 0.011 0.001

5.1.4 Food Residue Profile

Residues of Concern

The nature of the residue in plants and livestock is adequately understood. HED has concluded 

that the residue of concern in plants is tebuconazole per se for both regulatory and risk 

assessment purposes (DP186731, G. Otakie, 02/19/93). The residues of concern in animal 

commodities include tebuconazole and free and conjugated t-butylhydroxy tebuconazole, HWG2061 (DP170444, G. Otakie, 02/19/93). 

Crop Field Trials

Crop Field Trial Data in Support of Proposed Increase in Tolerances

Field trial data were submitted to support the uses of tebuconazole on cantaloupe (MRID 

48778702) and barley (MRID 48778701), including concurrent storage stability data on barley 

straw. Analysis of residues of 1,2,4-triazole and its conjugates were also included in the 

submissions.

The field trial data are adequate and support the existing use patterns. Samples were analyzed 

for residues of tebuconazole using adequate analytical methods, and the sample storage 

conditions and intervals from these field trials are supported by the available storage stability 

data.
Page 20 of 39

The submitted data for barley (hay, grain, and straw) and cantaloupe in conjunction with the data 

that were previously submitted under DP344178 and DP258559, respectively, are sufficient. 

The previously established tolerances of 7.0 ppm on barley hay and 3.5 ppm on barley straw will 

not be exceeded. Based on all available data, and using the Organization for Economic 

Cooperation and Development (OECD) statistical calculation procedures, tolerance adjustment is 

required for barley grain and cucurbit vegetables. The proposed tolerances of 0.3 ppm for barley 

grain and 0.4 ppm for cucurbit vegetables are adequate. HED recommends increasing the US

tolerances to reflect this determination.

Cantaloupe

The results from the submitted field trials are summarized in Table 5.1.4.1. These data 

adequately satisfy the deficiencies previously identified.

Table 5.1 4 1. Summary of Residue Data from Cantaloupe Field Trials with Tebuconazole.

Commodity Analyte Total

Rate

(lb ai/A)

PHI 

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

Cantaloupe Tebuconazole 0.684-

0.695

6-7 2 0.05 0.24 0.06 0.20 0.13 0.13 0.10

Tebuconazole

(all available 

data)

6 <0.01 0.24 0.06 0.20 0.04 0.06 0.07

T 2 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

TA 2 0.04 0.09 0.04 0.09 0.07 0.07 0.04

TAA 2 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Comb. TA+TAA 2 <0.05 <0.10 <0.05 <0.10 0.08 0.08 0.04

1 Except for sample min/max, values reflect per trial averages; n = no. of field trials. For calculation of median, mean, and 

standard deviation, the LOQ (0.01 ppm for all analytes) was used for any results reported as <LOQ. N/A = Not applicable.

2 LAFT = lowest-average-field-trial; HAFT = highest-average-field-trial.

Barley

The results from the submitted field trials are discussed below and summarized in Table 5.1.4.2. 

These data adequately satisfy the deficiencies previously identified.

Table 5.1.4.2. Summary of Residue Data from Barley Field Trials with Tebuconazole.

Commodity Analyte Total

Rate

(lb ai/A)

PHI 

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

Barley hay Tebuconazole 0.1088-

0.1147

7-11 3 0.390 3.68 0.452 3.31 1.07 1.61 1.50

T 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

TA 3 <0.07 <0.07 <0.07 <0.07 0.07 0.07 N/A

TAA 3 <0.04 0.047 <0.04 <0.043 0.040 0.041 0.002

Comb. TA+TAA 3 <0.11 <0.117 <0.11 <0.113 0.110 0.111 0.002

Barley

Grain

Tebuconazole 0.1088-

0.1147

29-31 3 0.067 0.280 0.068 0.247 0.106 0.140 0.094
Page 21 of 39

Table 5.1.4.2. Summary of Residue Data from Barley Field Trials with Tebuconazole.

Commodity Analyte Total

Rate

(lb ai/A)

PHI 

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

Tebuconazole (all 

available data)

20 0.01 0.280 0.01 0.247 0.023 0.044 0.056

T 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

TA 3 <0.03 0.059 <0.03 0.057 0.035 0.041 0.015

TAA 3 <0.01 0.015 <0.01 0.014 0.010 0.011 0.003

Comb. TA+TAA 3 <0.04 0.073 <0.04 0.072 0.045 0.052 0.017

Barley

Straw

Tebuconazole 0.1088-

0.1147

29-31 3 0.113 1.24 0.467 1.01 0.611 0.696 0.281

T 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

TA 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

TAA 3 <0.01 0.019 <0.01 0.017 0.013 0.013 0.004

Comb. TA+TAA 3 <0.02 <0.029 <0.02 <0.027 0.023 0.023 0.004

1 Except for sample min/max, values reflect per trial averages; n = no. of field trials. For calculation of median, mean, and 

standard deviation, the LOQs were used for any results reported as <LOQ. LOQs were 0.01 ppm for tebuconazole and T in hay, 

grain, and straw, for TA in straw, and for TAA in grain and straw; 0.07 and 0.03 ppm for TA in hay and grain; 0.04 ppm for TAA 

in hay; and 0.11, 0.04, and 0.02 ppm, respectively for TA + TAA in hay, grain, and straw. N/A = Not applicable. 

2 LAFT = lowest-average-field-trial; HAFT = highest-average-field-trial.

Fruiting Vegetables Crop Group 8

Tolerances have been established for tebuconazole on fruiting vegetables at 1.3 ppm and on okra 

at 1.2 ppm. The available data on fruiting vegetables group 8 and okra are adequate to establish 

tolerances on fruiting vegetables group 8-10. No new residue data are needed for these changes. 

Therefore, the established tolerance on the vegetable, fruiting, group 8 at 1.3 ppm could be 

extended to vegetable, fruiting, group 8-10 at 1.3 ppm.

Processed Food and Feed

The previously reviewed pepper reduction study and tomato processing studies are adequate

(DP362720, W. Cutchin, 9/14/09).

Meat, Milk, Poultry, and Eggs

The livestock feedstuffs associated with this petition are barley grain, hay, and straw; in addition, 

there are established tolerances for numerous livestock feedstuffs. The additional data for barley 

hay and grain will not increase the previously estimated dietary burden (DP287292 etc, S. 

Hummel, 11/27/06). The existing tolerances for animal commodities do not need to be 

reassessed for this petition.

5.2 Dietary Exposure and Risk

Acute and chronic aggregate dietary (food and drinking water) exposure and risk assessments 

were conducted using the Dietary Exposure Evaluation Model software with the Food 

Commodity Intake Database (DEEM-FCID) Version 3.16. This software uses 2003-2008 food 

consumption data from the U.S. Department of Agriculture’s (USDA’s) National Health and 
Page 22 of 39

Nutrition Examination Survey, What We Eat in America, (NHANES/WWEIA).

Refined acute probabilistic and chronic dietary exposure assessments were conducted for all 

existing food uses of tebuconazole. For both the acute and chronic dietary analyses, the 

exposure assessment incorporated the same input parameters used in the previous assessment 

(DP384950, C. Walls, 05/31/2011). Please refer to this document for detailed information of the 

assessment. The only changes made to the previous dietary assessment are in the acute 

anticipated residues from field trial data (in the residue distribution file; RDF) for cantaloupe, the 

average residue input on cantaloupe for chronic assessment, and inputs for gojiberry and tomato 

tree for crop group expansion. No changes were made to barley residues since PDP data were 

used for acute and chronic dietary assessments. 

Livestock commodities:

The livestock feedstuffs associated with this petition are barley grain, hay, and straw; in addition, 

there are established tolerances for numerous livestock feedstuffs. The additional data for barley 

hay and grain will not increase the previously estimated dietary burden. Based on these 

calculations, the existing tolerances for meat and milk remain adequate, while tolerances in 

poultry and eggs are still not required (D384787, L. Cheng, 04/01/11). 

5.2.1 Acute Dietary Exposure/Risk

The estimated acute dietary exposure to tebuconazole from food and drinking water at the 99.9th

percentile of exposure is estimated to be 0.0095 mg/kg/day for the general U.S. population, 

equivalent to 33% of the acute Population Adjusted Dose (aPAD). The population subgroup 

with the highest estimated acute dietary exposure to tebuconazole is children 1-2 years, with an 

estimated exposure at the 99.9th percentile of 0.016 mg/kg/day, equivalent to 55% of the aPAD. 

Table 5.2.1. Results of Acute Dietary (Food + Drinking Water) Exposure Analysis Using DEEM-FCID.

Population 

Subgroup

aPAD 

(mg/kg/day)

95th Percentile 99th Percentile 99.9th Percentile

Exposure 

(mg/kg/day)

% aPAD Exposure 

(mg/kg/day)

% aPAD Exposure 

(mg/kg/day)

% aPAD

General U.S. 

Population

0.029

0.003007 10 0.004957 17 0.009549 33

All Infants 

(< 1 year old)

 0.005564 19 0.008649 30 0.013549 47

Children 1-2 

years old 0.004914 17 0.008155 28 0.015881 55

Children 3-5 

years old 0.004294 15 0.007114 24 0.014256 49

Children 6-12 

years old 0.003219 11 0.005390 19 0.011692 40
Page 23 of 39

Table 5.2.1. Results of Acute Dietary (Food + Drinking Water) Exposure Analysis Using DEEM-FCID.

Population 

Subgroup

aPAD 

(mg/kg/day)

95th Percentile 99th Percentile 99.9th Percentile

Exposure 

(mg/kg/day)

% aPAD Exposure 

(mg/kg/day)

% aPAD Exposure 

(mg/kg/day)

% aPAD

Youth 13-19 

years old 0.002372 8.2 0.003929 14 0.007612 26

Adults 20-49 

years old 0.002841 9.8 0.004348 15 0.007862 27

Adults 50+ 

years old 0.002598 9.0 0.004341 15 0.008363 29

Females 13-49 

years old 0.002639 9.1 0.004153 14 0.007533 26

Note: The bolded values represent the subgroup with the highest food and water exposure.

5.2.2 Chronic Dietary Exposure/Risk

The chronic dietary exposure estimates for food and drinking water for the general U.S. 

population is 0.0026 mg/kg/day, equivalent to 9.0% of the cPAD. The population subgroup with 

the highest estimated chronic dietary exposure to tebuconazole is children 1-2 years with an 

estimated exposure of 0.042 mg/kg/day, equivalent to 14% of the cPAD. 

Table 5.2.2. Summary of Chronic Dietary (Food + Drinking Water) Exposure and Risk for Tebuconazole 

Using DEEM-FCID.

Population Subgroup Exposure

(mg/kg/day) % cPAD

General U.S. Population 0.002622 9.0

All Infants (< 1 year old) 0.004024 14

Children 1-2 years old 0.004200 14

Children 3-5 years old 0.003877 13

Children 6-12 years old 0.002746 9.5

Youth 13-19 years old 0.002046 7.1

Adults 20-49 years old 0.002567 8.9

Adults 50+ years old 0.002471 8.5

Note: The bolded values represent the subgroup with the highest food and water exposure.
Page 24 of 39

5.3 Dietary Assessment of Free Triazole and its Conjugates

Tebuconazole is a triazole fungicide. A separate updated dietary exposure and risk analysis 

(DP403618, T. Morton, 08/01/12) for the common triazole metabolites 1,2,4-triazole (T), 

triazolylalanine (TA), triazolylacetic acid (TAA), and triazolylpyruvic acid (TP) was conducted

previously; the review was associated with a registration request for the triazole fungicide, 

propiconazole. The increased tolerances for tebuconazole in/on barley, grain and vegetables, 

cucurbits, group 9 are not expected to change the risk of exposure to the triazoles. 

For all four analyses, risk estimates were below HED’s LOC for all population subgroups. There 

are no dietary exposure considerations for the common triazole metabolites that would preclude 

granting the tolerance requests for tebuconazole. 

Table 5.3. Summary of Dietary (Food and Drinking Water) Exposure and Risk for the Common Triazole 

Metabolites Adding the Amended Use for Propiconazole.

Population Subgroup

Acute Dietary

(95th Percentile) Chronic Dietary Cancer

Dietary 

Exposure 

(mg/kg/day)

% aPAD*

Dietary 

Exposure

(mg/kg/day)

% cPAD*

Dietary 

Exposure

(mg/kg/day)

Risk

1,2,4-Triazole

General U.S. Population 0.008282 28 0.001327 27

Not 

Applicable

Not 

Applicable

All Infants (< 1 year old) 0.012115 40 0.001843 37

Children 1-2 years old 0.023117 77 0.003832 77

Children 3-5 years old 0.018974 63 0.003064 61

Children 6-12 years old 0.010992 37 0.001665 33

Youth 13-19 years old 0.007222 24 0.001085 22

Adults 20-49 years old 0.006609 22 0.001137 23

Adults 50+ years old 0.005820 19 0.001073 22

Females 13-49 years old 0.006747 22 0.001110 22

Triazolylalanine + Triazolylacetic Acid+Triazolylpyruvic acid

General U.S. Population

Not 

Applicable

Not 

Applicable

0.018547 21

Not 

Applicable

Not 

Applicable

All Infants (< 1 year old) 0.021851 24

Children 1-2 years old 0.058600 65

Children 3-5 years old 0.047124 52

Children 6-12 years old 0.024837 28

Youth 13-19 years old 0.015657 17

Adults 20-49 years old 0.015272 17

Adults 50+ years old 0.014323 16

Females 13-49 years old 0.079772 80 0.014900 17

* The values for the highest exposed population for each type of risk assessment are bolded.

6.0 Residential (Non-Occupational) Exposure/Risk Characterization

No new residential uses are being requested at this time. However, adults, adolescents, and 

children may be exposed to tebuconazole from its currently registered uses on turf, flower 

gardens, trees, ornamentals, and pressure-treated wood. Each of these existing residential use 

patterns has previously been assessed and the resulting exposures and risk estimates did not 

exceed HED’s LOC (see DP346795, B. O’Keefe, 11/27/07 and DP349926, B. O’Keefe, 
Page 25 of 39

3/13/08). Additionally, HED has recently updated the residential standard operating procedures 

(SOPs; see http://www.epa.gov/pesticides/science/residential-exposure-sop.html for specifics) 

and body weights to be used in all human health assessments. Therefore, all of the existing 

residential use patterns were reassessed for handler and post-application exposures to adults and 

children using the updated procedures and data, since the residential exposures can impact the 

aggregate assessment for tebuconazole (see DP397518, B. O’Keefe, 4/30/12).

6.1 Residential Handler Exposure/Risk Characterization

Residential handler exposure is expected to be short-term. Intermediate-term exposures are not 

likely because of the intermittent nature of applications by homeowners. Dermal and inhalation 

exposures were combined since the same endpoint and POD is used for both routes of exposure. 

Table 6.1 summarizes the residential handler exposures and risk estimates for tebuconazole. All 

combined risk estimates are not of concern to HED with MOEs ranging from 2,800 to 91,000.

1 Application rates are based on maximum values found on existing labels.

2 Daily Exposure (mg/kg/day) = (Unit Exposure * % Absorption * Application rate * Amount handled daily) / Body Weight of 69-kg; where 

dermal absorption is 13%. and inhalation absorption is 100%.

3 Short-/Intermediate-Term MOE = NOAEL / Daily Exposure. The dermal/inhalation NOAEL is 8.8 mg/kg/day. The LOC is 300.

6.2 Residential Post-Application Exposure and Risk Characterization

Adults and children golfing, working in gardens, and performing physical activities on pressuretreated wood after application of tebuconazole may receive exposure to tebuconazole residues. 

Exposure is expected to be short-term in duration. Short-term dermal and incidental oral 

exposure and risk estimates have been previously assessed and indicate no risk estimates of 

concern. Table 6.2 summarizes the residential post-application exposure and risk estimates for 

tebuconazole. Residential dermal post-application MOEs for all life stages range from 340 to 

6,200. The residential exposure for 1 to 2 year olds coming in contact with pressure treated 

wood resulted in a dermal MOE of 460, an oral hand-to-mouth MOE of 2,600, and a combined 

dermal plus oral MOE of 390. 

Table 6.2. Residential Post-Application Short-Term Exposure and Risk Estimates for Tebuconazole.

Scenario Formulation

Application 

Rate

Amount 

Treated Activity Exposure Route Daily Dose (mg/kg/day) MOE1

Table 6.1. Residential Handler Short-term Exposure and Risk Estimates for Tebuconazole.

Scenario Formulation

Equipment/

Application 

Method

Application 

Rate1

Amount 

Treated

Exposure 

Route

Daily Dose 

(mg/kg/day)2 MOE Combined MOE3

Residential 

Handler for 

flower 

gardens, 

trees, 

ornamentals

Liquid

Manually 

Pressurized 

Handwand

0.0053 lb 

ai/gal 5 gal

Dermal 0.00314 2,800

2,800

Inhalation 0.00000690 1.3E+6

Hose-End 

Sprayer

0.0014 lb 

ai/gal 11 gal

Dermal 0.00168 5,200

5,200

Inhalation 0.000000312 2.8E+7

Backpack 0.0014 lb 

ai/gal 5 gal

Dermal 0.00171 5,100

5,100

Inhalation 0.0000142 6.2E+5

Ready To Use 

(RTU) Liquid Trigger Sprayer 0.0003 lb ai/bottle 2 bottles

Dermal 0.0000961 92,000

91,000

Inhalation 0.000000530 1.7E+7
Page 26 of 39

Table 6.2. Residential Post-Application Short-Term Exposure and Risk Estimates for Tebuconazole.

Scenario Formulation

Application 

Rate

Amount 

Treated Activity Exposure Route Daily Dose (mg/kg/day) MOE1

Golf Course 

Turf Liquid 1.35 lb ai/A NA

Adults Golfing Dermal 0.020 440

Children 11 to <16 yr old Dermal 0.0201 440

Children 6 to <11 yr old Dermal 0.0217 370

Gardens, 

Tress & 

Ornamentals

Liquid 0.27 lb ai/A 1 can

Adults to Gardens Dermal 0.0261 340

Adults to Trees Dermal 0.0024 3700

Children 6 to <11 yr old 

to Gardens Dermal 0.0155 570

Children 6 to <11 yr old 

to Trees Dermal 0.00143 6200

Pressure 

Treated 

Wood1

Liquid 1 μg/cm2 NA

Children 1-2 yr old Dermal 0.0191 460

Children 1-2 yr old Oral hand-to-mouth 0.0034 2600

Children 1-2 yr old Oral HTM & Dermal 0.0225 390

1 Wood surface residue adjusted for dermal transfer or “transfer efficiency” (EPA high end assumption of 1 μg/cm2) (DP 

Barcode 330159, 6/20/06, T. Leighton).

6.3 Other (Spray Drift, etc.)

Residential Bystander Post-Application Inhalation Exposure

Based on the Agency's current practices, a quantitative post-application inhalation exposure 

assessment was not performed for tebuconazole at this time because the chemical has low vapor 

pressure (9.75 x 10-9 mm Hg (20oC)) and is not applied via airblast or aircraft. However, 

volatilization of pesticides may be a potential source of post-application inhalation exposure to 

individuals nearby to pesticide applications. The Agency sought expert advice and input on 

issues related to volatilization of pesticides from its Federal Insecticide, Fungicide, and 

Rodenticide Act Scientific Advisory Panel (SAP) in December 2009. The Agency received the 

SAP’s final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html) and is in the process of 

evaluating the SAP report. The Agency may, as appropriate, develop policies and procedures to 

identify the need for and, subsequently, the way to incorporate post-application inhalation 

exposure into the Agency's risk assessments. If new policies or procedures are put into place, the 

Agency may revisit the need for a quantitative post-application inhalation exposure assessment 

for tebuconazole.

Spray Drift

Spray drift is always a potential source of exposure to residents nearby to spraying operations. 

This is particularly the case with aerial application, but, to a lesser extent, could also be a 

potential source of exposure from the ground application method employed for the previouslyregistered uses of tebuconazole. The Agency has been working with the Spray Drift Task Force, 

EPA Regional Offices, and State Lead Agencies for pesticide regulation and other parties to 

develop the best spray drift management practices. The Agency is now requiring interim 

mitigation measures for aerial applications that must be placed on product labels/labeling. The 

Agency has completed its evaluation of the new data base submitted by the Spray Drift Task 

Force, a membership of U.S. pesticide registrants, and is developing a policy on how to 

appropriately apply the data and the AgDRIFT computer model to its risk assessments for 
Page 27 of 39

pesticides applied by air, orchard airblast, and ground hydraulic methods. After the policy is in 

place, the Agency may impose further refinements in spray drift management practices to reduce 

off-target drift and risk estimates associated with aerial as well as other application types where 

appropriate.

7.0 Aggregate Risk Assessments and Risk Characterization

In accordance with the FQPA, HED must consider and aggregate (add) pesticide exposures and 

risks from three major sources: food, drinking water, and residential exposures. In an aggregate 

assessment, exposures from relevant sources are added together and compared to quantitative 

estimates of hazard (e.g., a NOAEL or PAD), or the risks themselves can be aggregated. When 

aggregating exposures and risks from various sources, HED considers both the route and 

duration of exposure.

7.1 Acute & Chronic Aggregate Risk

Refer to Section 5.2, which discusses acute and chronic dietary (food and drinking water) 

exposure in detail. The dietary route alone is relevant for acute exposure and risk assessment; 

and the acute dietary exposure and risk assessment conducted for tebuconazole is a refined, 

probabilistic assessment. The dietary route alone is also relevant for long-term/chronic exposure 

and risk assessment; and the chronic dietary exposure and risk assessment conducted for 

tebuconazole is a refined, deterministic assessment. 

7.2 Short-Term Aggregate Risks

The short-term aggregate risk assessments in this document use a deterministic approach, in that 

point estimates of exposure from each source are added together; and each of the point estimates 

used are in turn deterministic [dietary exposure estimates use point estimates for food and 

drinking water residues (anticipated residues based on field trial and PDP data, and tolerance 

level residues) and the residential scenarios also employ point estimates (central to high-end 

values considered protective)]. Exposures are assumed to occur over the same time frame, and 

no use frequency data is considered. There is the potential for residential exposure to co-occur 

with background dietary exposure over the short-term (1-30 days), whereas co-occurring 

intermediate exposures (1-6 months) are less likely. However, since the POD employed for both 

durations are the same, the aggregate assessments address both exposure durations. Although 

there are two adult residential exposure scenarios considered in this document, the likelihood of 

a residential handler treating ornamentals with tebuconazole and then playing golf on a 

tebuconazole-treated course is considered low; therefore, each scenario is considered separately 

with background dietary exposure. In sum, these aggregate risk assessments are considered 

protective. Aggregate risk estimates for all examined population subgroups were not of concern 

to HED, and above the level of concern (LOC = 300). 

These aggregate exposure assessments are considered conservative estimates, that should not 

underestimate risks, for the following reasons: 1) the dietary analysis used refined dietary 

exposure inputs for its acute and chronic dietary assessments, including crop specific (turf) 

screening level drinking water modeling data (i.e., surface water modeling); 2) maximum 
Page 28 of 39

application rates and minimum application intervals were used; and 3) conservative SOPs and 

upper level estimates of exposure were employed.

Table 7.2.1. Short-Term Aggregate Risk Calculations

Population Residential Scenario

Short-Term Scenarios

LOAEL LOC1

Max 

Allowable 

Exposure2

(mg/kg/day)

Average Food 

& Water 

Exposure 

(mg/kg/day)

Residential 

Exposure3

(mg/kg/day)

Aggregate 

MOE4

(dietary and 

residential)

Residential Handler

Adult

Manually Pressurized 

Handwand to gardens, 

trees, ornamentals

8.8 300 0.029 0.002622 0.0031469 1,500

Residential Post-Application

Children 11 to 

<16 yr old Golfer, Turf 8.8 300 0.029 0.002046 0.0201 400

Children 6 to 

<11 yr old Golfer, Turf 8.8 300 0.029 0.002746 0.0217 360

Adults Gardens 8.8 300 0.029 0.002622 0.0261 310

Children (3-5) Activities on pressure 

treated wood surfaces 8.8 300 0.029 0.003877 0.0225 330

1. The basis for the LOC are the standard inter- and intra- species uncertainty factors totaling 100, as well as an additional uncertainty factor for LOAEL 

to NOAEL extrapolation (UFL = 3X)

2. Maximum allowable exposure (mg/kg/day) = LOAEL / LOC

3. Residential Exposure = [Oral Exposure + Dermal Exposure + Inhalation Exposure]. See Section 6.0 for derivation of residential exposure 

assessments.

4. Aggregate MOE = [LOAEL/(Average Food & Water Exposure + Residential Exposure)]

Updated Aggregate Assessment of Free Triazole & its Conjugates

In 2006, HED issued aggregate human health risk assessments for 1,2,4-triazole (T) and the 

conjugated triazole metabolites (DP322215, M. Doherty, et al., 02/07/06). In 2012, HED 

reviewed the dietary and residential exposure of T and the triazole metabolites for a petition 

associated with propiconazole (DP403619, T. Morton, 08/01/12). The findings of the

assessments were that risk estimates for all exposure scenarios were below HED’s level of 

concern. Neither the toxicological information nor the non-dietary exposure estimates detailed 

in the 2006 memorandum have changed; thus, the only alterations to the previous aggregate 

exposure and risk estimates in 2012 are due to changes in the dietary exposure estimates. For 

complete hazard characterization and non-dietary exposure assessments for the common triazole 

metabolites, see the 2006 and 2012 risk assessments.

The revised aggregate estimates are summarized below for short- and intermediate-term 

scenarios for T (Tables 7.2.2 and 7.2.3, respectively). The conjugated triazole metabolites are 

formed in plants by the conjugation of 1,2,4-T to serine. The TA may then be further 
Page 29 of 39

metabolized to form TAA and/or TP. Because of the nature of this process, HED has assumed 

that it occurs within the plant itself and not on leaf surfaces. Therefore, the residues are not 

available for dermal, hand-to-mouth, or object-to-mouth exposures and HED has not conducted a 

residential exposure assessment for the triazole conjugates. Residues of TA, TAA, and TP may 

occur in soil. 1,2,4-Triazole is more toxic than TA/TAA/TP and exposures to these via soil 

ingestion are unlikely to exceed those of 1,2,4-T. The assessment for soil ingestion of 1,2,4-T 

shows that risk estimates are below HED’s level of concern; therefore, risk estimates for soil 

ingestion of the conjugates will also be below HED’s level of concern.

Table 7.2.2. Short-term Aggregate Exposure and Risk Estimates for 1,2,4-Triazole.

Population Subgroup

Exposure Estimate, mg/kg/day1

Aggregate 

MOE2 Dietary

Dermal

(M/L/A)

Dermal 

(PostApplic.)Hand-toMouthObjectto-MouthSoil 

Ingestion Aggregate

U.S. Population (total) 0.001327 0.00183 0.0051 N/A N/A N/A 0.008257 3600

All infants (< 1 year) 0.001843 N/A 0.0086 0.0041 0.0010 0.000019 0.015562 1900

Children 1-2 yrs 0.003832 N/A 0.0086 0.0041 0.0010 0.000019 0.017551 1700

Children 3-5 yrs 0.003064 N/A 0.0086 0.0041 0.0010 0.000019 0.016783 1800

Children 6-12 yrs 0.001665 N/A 0.0086 N/A N/A N/A 0.010265 2900

Youth 13-19 yrs 0.001085 0.00183 0.0051 N/A N/A N/A 0.008015 3700

Adults 20-49 yrs 0.001137 0.00183 0.0051 N/A N/A N/A 0.008067 3700

Adults 50+ yrs 0.001073 0.00183 0.0051 N/A N/A N/A 0.008003 3700

Females 13-49 yrs 0.001110 0.00183 0.0051 N/A N/A N/A 0.00804 3700

1 Exposure estimates for dermal, hand-to-mouth, object-to-mouth, and soil ingestion are from J. Arthur, DP 322240, 12/9/05.

2 Aggregate MOE = NOAEL (30 mg/kg/day) ÷ Aggregate Exposure Estimate (mg/kg/day). Level of Concern = 1000.

Table 7.2.3. Intermediate-term Aggregate Exposure and Risk Estimates for 1,2,4-Triazole.

Population Subgroup

Exposure Estimate, mg/kg/day

Aggregate MOE2 Dietary Soil Ingestion1 Aggregate

U.S. Population (total) 0.001327 N/A 0.001327 11000

All infants (< 1 year) 0.001843 0.000019 0.001862 8100

Children 1-2 yrs 0.003832 0.000019 0.003851 3900

Children 3-5 yrs 0.003064 0.000019 0.003083 4900

Children 6-12 yrs 0.001665 N/A 0.001665 9000

Youth 13-19 yrs 0.001085 N/A 0.001085 14000

Adults 20-49 yrs 0.001137 N/A 0.001137 13000

Adults 50+ yrs 0.001073 N/A 0.001073 14000

Females 13-49 yrs 0.001110 N/A 0.001110 14000

1 Soil ingestion estimates are from J. Arthur, DP 322240, 12/9/05

2 Aggregate MOE = NOAEL (15 mg/kg/day) ÷ Aggregate Exposure Estimate (mg/kg/day). Level of Concern = 3000.

8.0 Cumulative Risk Characterization/Assessment

Tebuconazole is a member of the triazole-containing class of pesticides. Although conazoles act 

similarly in plants by inhibiting ergosterol biosynthesis, there is not necessarily a relationship 

between their pesticidal activity and their mechanism of toxicity in mammals. Structural 

similarities do not constitute a common mechanism of toxicity. Evidence is needed to establish 

that the chemicals operate by the same, or essentially the same, sequence of major biochemical 

events (EPA, 2002). In conazoles, however, a variable pattern of toxicological responses is 

found; some are hepatotoxic and hepatocarcinogenic in mice. Some induce thyroid tumors in 

rats. Some induce developmental, reproductive, and neurological effects in rodents. 

Furthermore, the conazoles produce a diverse range of biochemical events including altered 
Page 30 of 39

cholesterol levels, stress responses, and altered DNA methylation. It is not clearly understood 

whether these biochemical events are directly connected to their toxicological outcomes. Thus, 

there is currently no evidence to indicate that conazoles share common mechanisms of toxicity 

and EPA is not following a cumulative risk approach based on a common mechanism of toxicity 

for the conazoles. For information regarding EPA’s procedures for cumulating effects from 

substances found to have a common mechanism of toxicity, see EPA’s website at 

http://www.epa.gov/pesticides/cumulative.

Tebuconazole is a triazole-derived pesticide. This class of compounds can form the common 

metabolite 1,2,4-triazole and two triazole conjugates (triazolylalanine and triazolylacetic acid). 

To support existing tolerances and to establish new tolerances for triazole-derivative pesticides, 

including tebuconazole, U.S. EPA conducted a human health risk assessment for exposure to 

1,2,4-triazole, triazolylalanine, and triazolylacetic acid resulting from the use of all current and 

pending uses of any triazole-derived fungicide. The risk assessment is a highly conservative, 

screening-level evaluation in terms of hazards associated with common metabolites (e.g., use of 

a maximum combination of uncertainty factors) and potential dietary and non-dietary exposures 

(i.e., high end estimates of both dietary and non-dietary exposures). In addition, the Agency 

retained the additional 10X FQPA safety factor for the protection of infants and children. The 

assessment includes evaluations of risks for various subgroups, including those comprised of 

infants and children. The Agency’s complete risk assessment is found in the propiconazole 

reregistration docket at http://www.regulations.gov, Docket Identification (ID) Number EPAHQ-OPP-2005-0497.

9.0 References

Tebuconazole: Human Health Risk Assessment to support tolerances in/on Asparagus, Barley, 

Beans, Beets, Brassica leafy greens, Bulb Vegetables, Coffee (import), Commercial 

Ornamentals, Corn, Cotton, Cucurbits, Hops, Lychee, Mango, Okra, Pome fruit, Soybean, Stone 

fruit, Sunflower, Tree Nut Crop Group, Turf, Turnips and Wheat. DP256074 and DP276447, S. 

Winfield, 4/18/08.

Tebuconazole: Human Health Risk Assessment to Harmonize Tolerances of Tebuconazole in/on 

Oats and Wheat with Canada. DP384949, K.Rury, 5/24/11.

Tebuconazole: Occupational Exposure and Risk Assessment for Proposed Increase in 

Application Rate for Golf Course Turf. DP397518, B. O’Keefe, 4/30/12

Tebuconazole. IR-4 Request for Tolerances on Cucurbits. Summary of Analytical Chemistry 

and Residue Data. Petition Number #9E6048. DP258559, G. Otakie, 7/20/06.

Tebuconazole on Barley Commodities. Summary of Analytical Chemistry and Residue Data. 

DP344178, S. Hummel, 4/10/08.

Tebuconazole. Supplemental Residue Data for Barley and Cantaloupe. Response to Condition 

of Registration Requirements Specified Under DP#s 258559 and 344178 and Crop Group 

Expansions to Fruiting Vegetable Crop Group 8-10. Summary of Analytical Chemistry and 
Page 31 of 39

Residue Data. M. Negussie, DP402456, 01/31/13.

Tebuconazole. Petition for the Establishment of a Tolerance on Fruiting Vegetables (Crop Group 

8). Summary of Analytical Chemistry and Residue Data. DP362720, W. Cutchin, 9/14/09

Tebuconazole: Acute and Chronic Aggregate Dietary Exposure and Risk Assessments for 

Condition of Registration Requirements Specified Under DP#s D258559 and D344178 and Crop 

Group Expansions to Fruiting Vegetable Crop Group 8-10. DP408526, 01/31/13. M. Negussie, 

DP408526, 01/29/13. 

Drinking Water Assessment for Tebuconazole: Fluopyram/Tebuconazole 400 SC Fungicide 

(EPA Reg. No. 264-RNOR), DP 385878, W. Eckel, 05/10/11. 

Common Triazole Metabolites: Updated Dietary (Food + Water) Exposure and Risk Assessment 

to Address The Amended Propiconazole Section 3 Registration to Add Foliar Use on Sugarcane. 

T. Morton. DP403618. 8/1/2012.

Common Triazole Metabolites: Updated Aggregate Human Health Risk Assessment to Address 

The Amended Propiconazole Section 3 Registration to Add Use on Sugarcane. T. Morton. 

DP403619. 8/1/2012.
Page 32 of 39

Appendix A: Toxicology Assessment

A.1 Toxicology Data Requirements

The requirements (40 CFR 158.340) for food and non-food uses for Tebuconazole are in Table 1. Use of the new 

guideline numbers does not imply that the new (1998) guideline protocols were used.

Test Technical

Required Satisfied

870.1100 Acute Oral Toxicity.......................................................

870.1200 Acute Dermal Toxicity ..................................................

870.1300 Acute Inhalation Toxicity..............................................

870.2400 Primary Eye Irritation....................................................

870.2500 Primary Dermal Irritation ..............................................

870.2600 Dermal Sensitization......................................................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.3100 Oral Subchronic (rodent)...............................................

870.3150 Oral Subchronic (nonrodent) .........................................

870.3200 21-Day Dermal ..............................................................

870.3250 90-Day Dermal ..............................................................

870.3465 90-Day Inhalation..........................................................

yes

yes

yes

no

yes

yes

yes

yes

no

yes+

870.3700a Developmental Toxicity (rodent)...................................

870.3700b Developmental Toxicity (nonrodent).............................

870.3800 Reproduction .................................................................

yes

yes

yes

yes

yes

yes

870.4100a Chronic Toxicity (rodent) ..............................................

870.4100b Chronic Toxicity (nonrodent)........................................

870.4200a Oncogenicity (rat)..........................................................

870.4200b Oncogenicity (mouse)....................................................

870.4300 Chronic/Oncogenicity....................................................

no

yes

yes

yes

yes

no

yes

yes

yes

yes

870.5100 Mutagenicity—Gene Mutation - bacterial.....................

870.5300 Mutagenicity—Gene Mutation - mammalian................

870.5xxx Mutagenicity—Structural Chromosomal Aberrations...

870.5xxx Mutagenicity—Other Genotoxic Effects.......................

yes

yes

yes

yes

yes

yes

870.6100a Acute Delayed Neurotox. (hen) .....................................

870.6100b 90-Day Neurotoxicity (hen)...........................................

870.6200a Acute Neurotox. Screening Battery (rat) .......................

870.6200b 90-Day Neuro. Screening Battery (rat)..........................

870.6300 Develop. Neuro..............................................................

no

no

yes

yes

yes

-

-

yes

yes

yes

870.7485 General Metabolism ......................................................

870.7600 Dermal Penetration ........................................................

870.7800 Immunotoxicity...............................................

yes

no

yes

yes

yes

yes*

Special Studies for Ocular Effects

Acute Oral (rat)...........................................................

Subchronic Oral (rat) ..................................................

Six-month Oral (dog)..................................................

no

no

no

no

no

no

*The study has been received and is currently under review.

+ An acceptable 21-day inhalation toxicity study in rats was submitted.

A.2 Toxicity Profiles
Page 33 of 39

Table A.2.1 Acute Toxicity Profile - Tebuconazole

Guideline No. Study Type MRID(s) Results Toxicity 

Category

870.1100 Acute oral [rat] 40700917 LD50 (fasted) = > 5000 mg/kg (M); 3933 

mg/kg (F);

(unfasted)=4264 mg/kg (M); 3352 

mg/kg (F)

III

870.1200 Acute dermal [rat] 40700917

41290801

LD50 = >5000 mg/kg (M & F) III

870.1300 Acute inhalation [rat] 40700922 LC50 (4 h, aerosol)= >371 mg/m3

LC50 (4 h, dust)= >5093 mg/ m3

II

870.2400 Acute eye irritation [rabbit] 40700925

40700917

Slight to Mild irritant III

870.2500 Acute dermal irritation [rabbit] 40700917

40995910

Non-irritant IV

870.2600 Skin sensitization 

[guinea pig]

40700928

41290802

No evidence of skin sensitization using 

the Buehler test

NA

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

Guideline No.

Study Type

MRID No. (year)

Doses/ Classification Results

870.3100

90-Day oral toxicity

- rat

40700930 (1986)

(0, 100, 400, 1600 ppm in diet); 

0, 8.6, 34.8, 171.7 mg/kg/d (m); 

0, 10.8, 46.5, 235.2 mg/kg/d (f)

Acceptable/guideline

Male: NOAEL = 34.8 mg/kg/d; LOAEL= 171.7 mg/kg/d 

based on decreased body wt., body wt. gain, and 

histopathology findings.

Female: NOAEL=10.8 mg/kg/d, LOAEL= 46.5 mg/kg/d 

based on histopathological changes in the adrenal gland.

870.3150

90-Day oral toxicity 

- dog

40700934 (1987)

(0, 200, 1000, 5000 ppm in diet); 

0, 73.7, 368.3, 1749.1 mg/kg/d (m);

0, 73.4, 351.8, 1724.8 mg/kg/d (f)

Acceptable/guideline

NOAEL = 73.4/73.7 mg/kg/d (m/f)

LOAEL = 368.3/ 351.8 mg/kg/d (m/f) based on 

decreased body wt. gain, food consumption and 

increased liver enzyme activities.

870.3200

21/28-Day dermal toxicity 

- rabbit

40700937 (1984)

0, 50, 250, 1000 mg/kg/day

Acceptable/guideline

NOAEL = 1000 mg/kg/day.

No dermal or systemic toxicity was seen.

870.3465

21-Day inhalation toxicity 

- rat

40700938 (1985)

0, 1.2, 10. 6, 155.8 mg/m3

Acceptable/guideline

NOAEL = 10.6 mg/m3/d (0.0106 mg/L/day)

LOAEL = 155.8 mg/m3/d (0.1558 mg/L/day) based on 

clinical signs and induction of liver microsomal 

enzymes.

870.3700a

Prenatal developmental

- rat

40700943 (1988)

0, 30, 60 , 120 mg/kg/d, GD 6-15

Acceptable/guideline

Maternal NOAEL = 30 mg/kg/day

LOAEL=60 mg/kg/d based on increased liver wt and 

liver/body weight ratios.

Developmental NOAEL=30 mg/kg/day 

LOAEL =60 mg/kg/d based on delayed ossification of 

several bones and increased numbers of fetuses with 

supernumerary ribs.

870.3700a

Prenatal developmental

- rat (Dermal)

41450801 (1988)

0, 100, 300, 1000 mg/kg/d, GD 6-15

Acceptable/guideline

Maternal NOAEL= 1000 mg/kg/d

Developmental NOAEL= 1000 mg/kg/d

No evidence of maternal or developmental toxicity seen 

via dermal route.
Page 34 of 39

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

Guideline No.

Study Type

MRID No. (year)

Doses/ Classification Results

870.3700a

Prenatal developmental

- mouse

40821501 (1988)

0, 10, 30, 100 mg/kg/d, GD 6-15 

40821500 (1988)

Supplementary study

0, 10, 20, 30, 100 mg/kg/d GD 6-15 

Acceptable/guideline

Maternal NOAEL = 30 mg/kg/d

LOAEL = 100 mg/kg/d based on increased hepatic 

triglycerides, pale lobular liver, increased severity of 

hepatic vacuoles and lipidosis.

Developmental NOAEL = 10 mg/kg/d

LOAEL = 30 mg/kg/d based on increased number of 

runts.

870.3700a

Prenatal developmental

- mouse

43776201, 43776202(1995)

0, 10, 30, 100 mg/kg/d, GD 6-15 

Supplementary group

0, 1, 3 mg/kg/d GD 6-15

Acceptable/guideline

Maternal: NOAEL = 3 mg/kg/d

LOAEL = 10 mg/kg/d based on increased hepatic 

enzyme induction and severity of vacuolization in liver 

cells.

Developmental: NOAEL= 3 mg/kg/d

LOAEL=10 mg/kg/d based on increased external, 

visceral, and skeletal malformation/variation in the head 

and skull.

870.3700a

Prenatal developmental

- mouse (Dermal)

42010301 (1990)

0,100,300,1000 mg/kg/d GD 6-15

Acceptable/guideline

Maternal NOAEL= 1000 mg/kg/d

Developmental NOAEL= 1000 mg/kg/d

No evidence of maternal or developmental toxicity seen 

via dermal route.

870.3700b

Prenatal developmental

- rabbit

40700945 (1987)

0, 10,30,100 mg/kg/d, GD 6-18

Acceptable/guideline

Maternal NOAEL = 30 mg/kg/d

LOAEL = 100 mg/kg/d based on decreased body weight 

gain and food consumption.

Developmental NOAEL = 30 mg/kg/d

LOAEL = 100 mg/kg/d based on increased resorptions 

and post-implantation losses, decreased live fetuses/doe, 

and external and skeletal abnormalities.

870.3700b

Prenatal developmental

- rabbit

43776201 (1995)

0, 10, 30, 100 mg/kg/day GD 6-18

Acceptable/guideline

Maternal NOAEL = Not established (<10 mg/kg/d)

LOAEL = 10 mg/kg/d based on increased incidence of 

single cell necrosis in liver cells.

Developmental NOAEL = 10 mg/kg/d

LOAEL = 30 mg/kg/d based on increased external and 

visceral malformation/variations.

870.3800

Reproduction and fertility 

effects

- rat

40700946 (1987)

0, 100, 300, 1000 ppm in diet 

(equivalent to 0, 5, 15, 50 

mg/kg/day)

Acceptable/guideline

Parental/Systemic NOAEL = 15 mg/kg/day (m & f)

LOAEL = 50 mg/kg/day based on increased severity of 

splenic hemosiderosis (m & f), increased incidence of 

splenic hematopoiesis (m), and decreased weight gain 

during gestation (f)

Reproductive NOAEL = 50 mg/kg/day

LOAEL = not determined

Offspring NOAEL = 15 mg/kg/day

LOAEL = 50 mg/kg/day based on decreased pup body 

wt.

870.4300

Chronic/ carcinogenicity

- rat

40700939, 40816401 (1988)

0, 100, 300, 1000 ppm in diet; 

M: 0, 5.2, 15.9, 55 mg/kg/d;

F: 0, 7.4, 22.8, 86.3 mg/kg/d

Acceptable/guideline

Males: NOAEL = 15.9 mg/kg/d; LOAEL=55 mg/kg/day 

based on decreased testes weight.

Females: NOAEL= 7.4 mg/kg/d; LOAEL=22.8 

mg/kg/day based on decreased body wt. & wt. gain, 

decreased erythrocyte parameters and increased 

incidence of splenic hemosiderosis (increased 

erythrocyte clearance).

No evidence of carcinogenicity at the doses tested.
Page 35 of 39

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

Guideline No.

Study Type

MRID No. (year)

Doses/ Classification Results

870.4100b

Chronic toxicity 

- dog

40700940 (1987)

0, 40, 200, 1000/2000 ppm in diet; 

0, 15.5, 77.3, 483 mg/kg/d

Acceptable/guideline

NOAEL = 15.5 mg/kg/day

LOAEL = 77.3 mg/kg/day based on ocular lesions and 

changes in erythrocyte morphology (anisocytosis)

870.4100b

Chronic toxicity 

- dog

42030601 (main) (1989) & 

42537201 (suppl.) (1992); 

0, 100, 150 ppm; 

M: 0, 2.96, 4.39 mg/kg/d 

F: 0, 2.94, 4.45 mg/kg/d 

Acceptable/guideline together with 

40700940

NOAEL = 2.96 mg/kg/day (m), 2.94 mg/kg/d (f)

LOAEL = 4.39 mg/kg/day (m), 4.45 mg/kg/d (f) based 

on lesions in the adrenal gland.

870.4200b

Carcinogenicity

- mouse

40700941 (1988)

0, 20, 60, 180 ppm in diet; 

M: 0, 5.9, 18.2, 53.1 mg/kg/d

F: 0, 9.0, 26.1, 80.5 mg/kg/d

42175001

0, 500, 1500 ppm

M: 0, 84.9, 279 mg/kg/day

F: 0, 103.1, 365.5 mg/kg/day

Acceptable/guideline

Male mice had statistically significant, dose-related 

increasing trends in hepatocellular adenomas, 

carcinomas and combined adenomas and/or carcinomas. 

There were also statistically significant differences in the 

pair-wise comparisons of the controls with the 1500 ppm 

dose group for hepatocellular adenomas (29% vs. 5% 

controls), hepatocellular carcinomas (21% vs. 0% 

controls) and combined adenomas and/or carcinomas 

(47% vs. 5% controls).

870.5100 

Salmonella point mutation

40700947 & 40700948 (1988)

Acceptable/guideline

Negative with or without activation at doses ranging 

from 39.5 to 450 μg/plate

870.5300

CHO-HGPRT forward 

mutation

40700949 (1988)

Unacceptable/guideline

Negative with or without activation at concentrations 

ranging from 12.5-200 and 80-100 μg/mL, respectively; 

highest concentration tested did not produce high level 

of cytotoxicity.

870.5375 

In vitro Cytogenetics 

(human lymphocytes)

40700953 (1988)

Acceptable with activation; 

Unacceptable without activation

Negative for chromosome aberrations with activation 

(30-300 μg/mL) and without activation (10-300 μg/mL); 

highest dose not cytotoxic without activation.

870.5395

Mammalian erythrocyte 

micronucleus

40700951 (1985)

Acceptable/guideline

Negative at all doses up to 2000 mg/kg bw

870.5450

Mouse dominant lethality

40700950 (1986)

Unacceptable/guideline

Negative at 2000 mg/kg bw (only dose tested) during 12 

serial mating periods; positive control was not included

870.5500

DNA damage and repair 

(E.coli)

40700955 (1983)

Unacceptable/guideline

Negative with or without activation at concentrations 

ranging from 625-10,000 μg/plate); no growth inhibition 

zone detected

870.5550

Unscheduled DNA 

synthesis (rat hepatocytes)

40816402 (1988)

Acceptable/guideline

No evidence of an increase in unscheduled DNA 

synthesis at 0.504-25.2 μg/mL

870.5900

Sister chromatid exchange 

(CHO cells in vitro)

40700952 (1987)

Acceptable/guideline

Negative with and without activation with S9 at 

concentrations ranging from 4-30 μg/mL and 15-120 

μg/mL, respectively.

870.6200a 

Acute neurotoxicity 

screening battery 

-rat

44449301, 44545701 (1997)

0, 21, 50, 103, 497, 950 mg/kg

Unacceptable/Guideline

(Upgradeable)

NOAEL = 50 mg/kg/day

LOAEL = 100 mg/kg/day based on increased motor 

activity in males and females and decreased footsplay in 

females.
Page 36 of 39

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

Guideline No.

Study Type

MRID No. (year)

Doses/ Classification Results

870.6200b 

Subchronic neurotoxicity 

screening battery 

-rat

44588001 (1998)

0, 100, 400, or 1600 ppm 

M: 0.00, 7.57, 29.2, 107 mg/kg/day 

F: 0.00, 8.81, 34.0, 122 mg/kg/day

Unacceptable/Guideline

(Not upgradeable)

NOAEL = 107 mg/kg/day

LOAEL = Not determined [>107 mg/kg/day]

870.6300

Developmental 

neurotoxicity 

-rat

45074301 (2000)

0, 100, 300, 1000 ppm 

[GD/LD 0/0, 8.8/16.3, 22/41.3, 

65/125.4 to dams], GD6 to LD11

Acceptable/Guideline

Maternal NOAEL = 22 mg/kg/day

LOAEL = 65 mg/kg/day based on decreased body 

weight, body weight gain, and food consumption; 

prolonged gestation with mortality, increased number of 

dead fetuses.

Offspring NOAEL = <8.8 mg/kg/day

LOAEL = 8.8 mg/kg/day based on decreased body 

weight, decreased absolute brain weights and brain 

measurements, and decreased motor activity.

870.7485

Metabolism

- rat

40995911, 40995912 (1987)

Acceptable/guideline

98.1% of oral dose is absorbed. Over 87% of dose 

excreted in urine & feces within 72 hours after dosing. 

At sacrificed (72 hrs postdosing) total residue (minus GI 

tract) amounted to 0.63% of the dose. A total of 10 

compounds were identified in excreta. A large fraction 

of the identified metabolites corresponded to successive 

oxidation steps of a methyl group of tebuconazole. At 

higher dose 920 mg/kg) changes in detoxification 

patterns may result from metabolic saturation.

870.7600

Dermal penetration

- monkey

46634901 (2003)

132 μg/cm2tebuconazole in Folicur 

EW250, single 8 hr administration

Acceptable/nonguideline

Estimated dermal absorption 23.1%. (including the 

fraction of the dose absorbed and the amount of dose 

remaining in the skin after washing).

Literature study: 

Developmental 

neurotoxicity 

/immunotoxicity

45486901 (2001), 45591701 (2002), 

46146701 (2003)

0, 6, 20, 60 mg/kg (gavage) GD14-

PND7 to dams, PND7-42 to 

offspring

Study evaluated reproductive, immuno-, and 

neurotoxicity in offspring. Identified one effect of 

concern: learning deficits in high dose offspring, 

evaluated starting on PND74. Neuropathological effects 

identified in the original study were retracted based on a 

pathology peer-review.
Page 37 of 39

Appendix B: EPA Review of Human Research

This risk assessment relies in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide or other chemical. These studies (which compose PHED, 

listed below) were determined to require a review of their ethical conduct, have received that 

review and have been determined to be ethical.

Data from the Outdoor Residential Exposure Task Force (ORETF). 

HED Residential Standard Operating Procedures (2012). 
Page 38 of 39

Appendix C: Structure, Nomenclature, and Physical and Chemical Properties

Table C.1. Tebuconazole Nomenclature.

Chemical structure

Common name Tebuconazole

Company experimental name HWG 1608

IUPAC name (RS)-1-p-Chlorophenyl-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)pentan-3-ol

CAS name α-[2-(4-Chlorophenyl)ethyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol

CAS registry number 107534-96-3

End-use product (EP) Folicur 3.6 F Foliar Fungicide (EPA File Symbol 264-752) 

Chemical structure of 

t-butylhydroxy-tebuconazole; 

HWG 2061

1-(4-Chlorophenyl)-4,4-dimethyl-3-(1H-1,2,4-triazole-1-yl-methyl)-pentane-3,5-

diol

Table C.2. Physicochemical Properties of Tebuconazole.

Parameter Value Reference

Melting point/range 104.7 °C PP#9F3724/9F3818, 5/9/91, 

G. Otakie pH Not soluble enough

Specific gravity (20 oC) 1.202 g/mL

Water solubility (20 °C) 32 mg/L

Solvent solubility (g/L at 20oC) n-hexane 2-5 

dichloromethane >200

2-propanol 100-200

toluene 50-100

Vapor pressure 1.3 x 10-3 mPa (20 oC) 

3.1 x 10-3 mPa (25 oC)

Dissociation constant, pKa does not dissociate

Octanol/water partition coefficient, 

Log(KOW)

3.7 at 20 oC

UV/visible absorption spectrum Not available

Cl OH CH3

CH3

CH3

N

N

N

Cl OH CH3

CH3

CH2OH

N

N

N
Page 39 of 39

Appendix D: International Residue Limit Status

Tebuconazole (PC Code; 01/04/2012)

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico2 Codex3

40 CFR 180.474:

Plant: (1) tebuconazole [α-[2-(4-

chlorophenyl) ethyl]-α-(1,1-

dimethylethyl)-1H-1,2,4-triazole-1-

ethanol]

Livestock: sum of tebuconazole 

(alpha-[2-(4-chlorophenyl)ethyl]-

alpha-(1,1-dimethylethyl)-1 H -

1,2,4-triazole-1-ethanol) and its 

diol metabolite (1-(4-

chlorophenyl)-4,4-dimethyl-3-(1 H

-1,2,4-triazole-1-yl-methyl)-

pentane-3,5-diol), calculated as the 

stoichiometric equivalent of 

tebuconazole

Plants: (+)-α-[2-(4-

chlorophenyl)ethyl]-α-

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

Livestock: (±)-α-[2-(4-

chlorophenyl)ethyl]-α-

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

including the metabolite 

5-(4-chlorophenyl)-2,2-

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

triazol-1-

ylmethyl)-1,3-pentanediol

Tebuconazole

The residue is fatsoluble.

Commodity1 Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico2 Codex3

Barley, grain 0.3 0.15 barley 2 barley

Barley, hay 7.0

Barley, straw 3.5 40 barley straw and 

fodder, dry

Vegetable, cucurbit, group 9 0.4

0.15 cucumber; melons, 

except watermelon

0.2 summer squash

Vegetable, fruiting, group 8-10, 

except okra 1.3

0.1 eggplant

0.7 tomato

10 peppers chili, dried

1 peppers, sweet 

(including pimento or 

pimiento)

Completed: M. Negussie; 01/07/2013

1

Includes only commodities of interest for this action. Tolerance values should be the HED recommendations and 

not those proposed by the applicant.

2 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.

3 * = absent at the limit of quantitation; Po = postharvest treatment, such as treatment of stored grains. PoP = 

processed postharvest treated commodity, such as processing of treated stored wheat. (fat) = to be measured on the 

fat portion of the sample. MRLs indicated as proposed have not been finalized by the CCPR and the CAC.