H ymexazo l H uman H ea lth Ri sk Assess m en t DP No . 0 425247

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

MEMORANDUM

Dat e : Decemb er 03. 20 1 5 WASHINGTON

, D .C. 20460

OFFICE OF
CHEMICAL SAFETY AND
POLL UTION PREVENTION

SUBJECT: Hymexazo l : Human H ea lth Draft Ri sk A ssess ment i n Support of Registr a ti o n
Review. 0425247

.

P C Co d e: 129107

D e ci s ion No.: 499341

P e titi o n No.: NA DP Barcode: 425247 Regi s tration No.: 4 8 2 10-1
Regu l ator y Ac tion: R eg i s trati o n R ev ie w
Case No.: 70 1 6 Risk As sess m e nt T y p e: S in g le C h e mi ca l Aggrega t e

TXR No.: NA CAS No

. : I 0004-44 -1

40 CFR: N I A MRlD No.: NA

FROM: Matthew Lloyd; C IH ; Ri sk**Assess~r** Aust in Wra y
, PhD

, Tmyecr!J:> g i s t 

### /+,,_

,. ,,.._,.. P ete r Savoia, C hemist (/c-ft::L.**~-------** Risk Assessment Branch es V and JI (RAB V / VII)

Health Effects Di v i sio n ( H ED ; 7509 P )

THRO UG H : Danette Dr ew, Chem i st 

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## 1Jf7 n

Michael S. M e t zge r
, C hi e f

, RAB VNII

.

### AA**_L ...,~**  r H E D (7509P ) 

### .Qf?t : <..W<l v**'<'~"4**

TO: Ca itlin Newca mp
, Chemical Review Manager

&

Tom M o ri a rt y, T eam Lead e r
R i sk Mana ge ment a nd Impl e m e nt at ion B ranch I

P es ticid e R e- Eva l uation Di v i s ion (75 08P)Hymexazol Human Health Risk Assessment DP No. D425247

Page 2 of 54 

## Table of Contents

1.0 Executive Summary

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

2.0 HED Recommendations

................................ ................................ ................................ ....... 7

2.1 Da ta Deficiencies

................................ ................................ ................................ ............. 7

2.2 Tolerance Considerations

................................ ................................ ................................ . 7

2.2.1 Enforcement Analytical Method

................................ ................................ ............... 7

2.2.2 International Harmonization

................................ ................................ ..................... 7

2.2.3 Recommended Tolerances

................................ ................................ ......................... 8

2.3 Label Recommendations

................................ ................................ ................................ .. 8

3.0 Introduction

................................ ................................ ................................ .......................... 8

3.1 Chemical Identity

................................ ................................ ................................ ............. 8

3.2 Phys ical/Chemical Characteristics

................................ ................................ ................... 8

3.3 Pesticide Use Pattern

................................ ................................ ................................ ........ 9

3.4 Anticipated Exposure Pathways

................................ ................................ ..................... 10

3.5 Consideration of Environmental Justice

................................ ................................ ........ 10

4.0 Hazard Characterization and Dose

- Response Assessment

................................ ................ 10

4.1 Toxicology Studies Available for Analysis

................................ ................................ ... 10

4.2 Absorption, Distribution, Metabolism, and Excretion (ADME)

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

4.3 Toxicological Effects

................................ ................................ ................................ ..... 12

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

................................ ....... 14

4.5 Toxicology Endpoint and Point of Departure Selections

................................ ............... 14

4.6 Endocrine Disruption

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

5.0 Dietary Exposure and Risk Assessment

................................ ................................ ............ 18

5.1 Metabolite/Degradate Residue Profile

................................ ................................ ........... 18

5.1.2 Summary of Environmental Degradation

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

5.1.4 Residues of Concern Summary and Rationale

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

5.2 Food Residue Profile

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

5.3 Water Residue Profile

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

5.4 Dietary Risk Assessment

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

5.4.1 Overview of Residue Data Used

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

5.4.2 Percent Crop Treated Used in Dietary Assessment

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

5.4.3 Acute Dietary Risk Assessment

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

5.4.4 Chronic Dietary Risk Assessment

................................ ................................ ........... 21

5.4.5 Cancer Dietary Risk Assessment

................................ ................................ ............. 21 5.4.6. Dietary Assessment Summary Tables

................................ ................................ ............ 21

6.0 Residential (Non

- Occupational) Exposure/Risk Characterization

................................ .... 22

6.1 Residential Handler Exposure

................................ ................................ ........................ 22

6.2 Post

- Application Exposure

................................ ................................ ............................. 22

7.0 Non

- Occupational Spray Drift Exposure and Risk Estimates

................................ ........... 22

8.0 Non

- Occupational Bystander Post

- Application Inhalation Exposure and Risk Estimates 22

9. 0 Aggregate Exposure/Risk Characterization

................................ ................................ ....... 22

10.0 Cumulative Exposure/Risk Characterization

................................ ................................ ..... 23

11.0 Occupational Exposure/Risk Characterization

................................ ........................... 23

11.1 Short

- and Intermediate

- Term Handler Risk

................................ .............................. 23

11.2 Short

- and Intermediate

- Term Post

- Application Risk

................................ ................ 27

12.0 Human Incidents

................................ ................................ ................................ ............ 27

13.0 R eferences

................................ ................................ ................................ .......................... 28Hymexazol Human Health Risk Assessment DP No. D425247

Page 3 of 54 Appendix A. Toxicology Assessment

................................ ................................ ........................... 29

A.1 Toxicology Data Requirements

................................ ................................ ...................... 29

A.2 Toxicity Profiles

................................ ................................ ................................ ............ 30

A.3 Ha zard Identification and Endpoint Selection

................................ .......................... 38

A.4 Executive Summaries

................................ ................................ ................................ ... 40 Appendix B. Physical/Chemical Properties

................................ ................................ .................. 53 Appendix C. Review of Human Research

................................ ................................ .................... 54Hymexazol Human Health Risk Assessment DP No. D425247

Page 4 of 54 1.0 Executive Summary

This assessment has been conducted to address the requirement for a Draft Risk Assessment (DRA) to support R egistration R eview. As part of Registration Review, the Pesticide Re

evaluation Division (PRD) of OPP has requested that HED evaluate the hazard an d exposure

data and conduct dietary and occupational and residential exposure assessments, as needed, to estimate the risk to human health that will result from the currently registered use of hymexazol

.

Background

Hymexazol is the common name for the isoxazole fungicide active ingredient 5

- methyl

- 3(2H)

- isoxazolone (CAS Name). Hymexazol is a systemic fungicide for control of foliar and soil

- borne plant diseases. There is only one existing registration as a commercial seed treatment for sugar

beets. As a wettable powder (WP) intended for commercial seed treatment, the maximum application rate is for standard pelletization , at the rate of 45 to 90 grams of TACHIGAREN® 70 WP per unit of 100,000 seeds (approx. 1 kilogram of raw sugar beet seed). Hymexazol may be applied only using commercial seed treatment equipment

. Based on the existing seed treatment registration, occupational handler exposure is expected for the short

- and intermediate

- term for primary handlers treating seed, and for secondar y handlers who plant the seed.

Hazard Assessment

The toxicology database is complete for risk assessment purposes

. In mammals, the primary

target organ of hymexazol and the organismal response were species specific; however

, the mode

of action is curren tly unknown. Dogs were the most sensitive non

- pregnant adult species exhibiting characteristics of thyroid toxicity (increase in thyroid weight and thyroid epithelial height, and increased prevalence of thyroid epithelial hyperplasia) from sub

- chronic oral exposure. Non

- pregnant adult rodents were more tolerant : a cute toxicity was low (Category III) and subchronic and chronic toxicity manifest ed as liver (increased liver weight with associated centrilobular hepatocyte enlargement and granulomatous inflammat ion, elevated liver enzymes) and systemic effects (reduced body weight and body weight gain) at doses 2

- 5x higher than those eliciting thyroid effects in dogs. At similar high doses, there w as no evidence of carcinogenicity or effects that would compromise the immune system. Neurological effects (decreased brain weight and cerebral length) in rodents occurred only at doses approaching the limit dose, and were not strong indicators of a neurotoxi c mode of action. Ingested hymexazol was rapidly eliminated, which limited tissue accumulation and progression of toxicity in all species tested.

Pregnant rodents and developing fetuses exhibited enhanced sensitivity to hymexazol exposure

relative to non

- pregnant adult rodents

. Oral exposure in rats from the pre

- mating period through parturition induced lower post

- implantation survival and a subsequent reduction in litter size. This response was attributed to both compromised maternal health and in utero e xposure and

thus was not indicative of increased susceptibility in the young. Pregnant rats exposed exclusively during the gestation period produced fetuses with developmental abnormalities including reduced ossification of the cervical, thoracic, lumbar, & caudal vertebrae, as well as in the pelvic girdle & in the fore

- & hind

- extremities, and significantly increased incidence of a

bilateral 14th rib

. These developmental effects were observed in the absence of maternal effects indicating enhanced sensitiv ity in the developing rat fetuses. The dose eliciting developmentalHymexazol Human Health Risk Assessment DP No. D425247

Page 5 of 54 effects in rats was similar in d eveloping rabbits exposed in utero

, yet the effects themselves were distinct ( heart/great vessel malformations, particularl y incomplete inferior vena cava, reduced fetal weight and increased incidence of reduced sternebrae ) . In contrast to fetal rats, the rabbit fetuses were not more susceptible to oral exposure as the developmental effects were only observed in concert with compromised health in the rabbit dams. Reproduction was not affected by hymexazol exposure.

Hymexazo l is a skin sensitizer; however, dermal exposure did not irritate the skin ( d ermal

irrita tion: Category IV) and high dermal doses were required to elicit acute (Category III) and subchronic systemic toxicity. It was minimally toxic via acute inhal ation exp osure (Category III)

but is a strong eye irritant (Category I).

Based on the toxicity, duration of exposure, and uses of hymexazol , the following to xicity endpoints were selected: Acute dietary (general population, including infants and children ): Maternal no observed adverse effect level ( NOAEL ) of 150 mg/kg/day based on mortality, abnormal clinical signs (unsteadiness, slumped posture, increased respiration, and salivation) observed in the rabbit developmental study within an hour of dosing, and d ecreased food consumption and body weight loss within 2 days of initial exposure at 450 mg/kg/day (maternal lowest observed adverse effect level ( LOAEL) )

. Chronic dietary (all populations) : NOAEL of 31 mg/kg/day

, derived from a parental LOAEL of 159 mg/kg/day based on increase in post

- implantation loss and a decrease in

litter size observed in the rat 2

- generation reproduction study

. Dermal: Same as chronic dietary

. Inhalation: Same as chronic dietary

.

H ED has applied the traditional uncertainty factors of 10X for inter

- species extrapolation and

10X for intra

- species variability , along with a database uncertainty factor of 10X based on a missing inhalation study 1 for the inhalation route only

. Exposure routes are combined because toxic effects are common between the inhalation and dermal routes of exposure. A total aggregated risk index (ARI) was used for the worker assessment since the level of concern ( LOC ) values for dermal exposure (100) and inhalation exposure (1000) are different.

Dietary (Food and Water) Exposure and Risk

Hymexazol is a non

- food use chemical based upon plant metabolism data that showed it to be

metabolized to carbon dioxide (CO 2 ) and incorporated into sugars. However, there is potential

for hymexazol to reach drinking water sources through its application to sugar beet seeds

. Therefore

, a drinking water assessment was performed. A cute and chronic dietary assessments of drinking water were conducted using model

- derived estimated drinking water concentrations (EDWCs). A cute exposure to hymexazol in drinking water resulted in an estimated risk which

was < 1% of the aRfD (acute reference dose) for the general U.S. population and all population subgroups at the 95 th percentile which is well below the Agency’s level of concern. The estimated chronic exposure to hymexazol in drinking water is also not of concern with risk

1 TXR 0057244Hymexazol Human Health Risk Assessment DP No. D425247

Page 6 of 54 estimates being <1% of the cRfD (chronic reference dose) for the general U.S. population and all population subgroups.

Residential (Non

- Occupational) Exposure and Risk

Because hymexazol is registered only for use as a commercial seed treatment, t here are no existing or proposed residential uses at this time and

, therefore

, no quantitative residential handler or post

- application assessment was completed.

Spray Drift

Hymexazol is registered only for use as a commercial sugar beet seed treatment. Based on that use pattern, no spray drift is anticipated (coated seed for pla nting) and no quantitative assessment was completed.

Volatilization/Residential Bystander

Volatilization of pesticides may be a source of post

- application inhalation exposure to individuals nearby pesticide applications. The agency has developed a Vola tilization Screening Tool and a subsequent Volatilization Screening Analysis, and the Agency will utilize this analysis during Registration Review to determine if data (i.e., flux studies) or further analysis are required for hymexazol

.

Aggregate

Althoug h there is the potential for hymexazol to enter drinking water sources from the nonfood use on seeds, there are no food or residential uses or exposures; therefore, the aggregate risk includes only the contribution to exposure from drinking water . There a re no risks of concern for hymexazol in drinking water.

Occupational Exposure and Risk

No chemical

- specific handler exposure data were submitted in support of this assessment; therefore, HED relied on surrogate data and default assumptions in accordance with standard policies. Based on the proposed use pattern, short

- and intermediate

- term durations of exposure are expected for occupational handlers. The estimates of exposure to pesticide seed treatment handlers (treatment and planting) are based upon ExpoSAC Policies 14 & 15 and a memorandum from the Biological and Economic Analysis Divisi on (BEAD), “Acres Planted Per Day and Seeding Rates of Crops Grown in the United States” (J. Becker, March 2011).

The maximum single application rate for sugar beet seed treatment is the “standard pellet” scenario. A lower application rate (“minimum bui ldup” scenario) is also an option based on the label, although it is rarely used in commercial seed treatment practice. Most “standard pellet” occupational handler scenarios are not of concern (based on the Aggregate Risk Index [ ARI ] LOC of 1) with label

- s pecified PPE. For the mixer scenario, the addition of a filtering facepiece respirator (PF5) results in an inhalation MOE of 1,500, although the ARI for the scenario is still below 1 (ARI = 0.6). However, for the handler mixing the wettable powder, the use ofHymexazol Human Health Risk Assessment DP No. D425247

Page 7 of 54 engineering controls (i.e., water soluble packets) is required to reach MOEs which result in an ARI > 1.

The potential for dermal post

- application exposures following the planting of hymexazol

- treated seeds is unlikely because no routine cultural practice s involve sustained levels of contact with treated seed after it has been placed in the soil or other planting media

.

Commercial treatment of seeds is not within the scope of the Worker Protection Standard. Hymexazol is not registered for non

- com mercial seed treatment and does not require Worker

P rotection Standard labeling.

Similarly, a post

- application inhalation exposure assessment is not required as exposure is expected to be negligible.

Human Studies Review

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 data, which include Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1); ExpoSAC Policy 14 and 15.1 (SOPs for

Seed Treatmen t); are (1) subject to ethics review pursuant to 40 CFR 26, (2) have received that review, and (3) are compliant with applicable ethics requirements. For certain studies, the ethics review may have included review by the Human Studies Review Board. Descr iptions of data sources, as well as guidance on their use, can be found at the Agency website 2

.

2.0 HED Recommendations

2.1 Data Deficiencies

There ar e no data deficiencies for the Registration R eview eligibility of hymexazol in regards to the toxicology, occupational and residential exposure, and chemistry databases

. No tolerances are required, and label modifications are discussed in S ection 2.3.

2.2 Tolerance Considerations

2.2.1 Enforcement Analytical Method

Because no tolerances are required to support the use of hymexazol , an enforcement analytical method is not required.

2.2.2 International Harmonization

International harmonization is not an issue for consideration

, because there are no tolerances

estab lished for hymexazol

.

2 http://www.epa.gov/pesticides/science/handler

- exposure

- data.html and http://www.epa.gov/pesticides/science/post

- app

- exposure

- data.htmlHymexazol Human Health Risk Assessment DP No. D425247

Page 8 of 5 4 2.2.3 Recommended Tolerances

Hymexazol is only registered for application as a commercial seed treatment for sugar beet seed s and is considered to be a non

- food use chemical

, which does not require the establishment of

tolerances.

2.2.4 Revisions to Established Tolerances

There are no tolerances established or needed for hymexazol

, and thus no revisions are required.

2.3 Label Recommendations

No label recommendations have been identified. A summary of the risk estimates has been provided, and shows that there are risk estimates of concern for registered uses of hymexazol based on the use information, and label

- required personal protective equi pment (PPE ).

3.0 Introduction

3.1 Chemical Identity

Table 3. 1. Chemical Identity of Hymexazol

Common Name Hymexazol

IUPAC name 5

- methylisoxazol

- 3

- ol

CAS name 5

- methyl

- 3(2 H )

- isoxazolone

PC Code 129107

CAS registry number 10004

- 44

- 1

Chemical Structure

3.2 Physical/Chemical Characteristics

Hymexazol is the common name for the isoxazole fungicide active ingredient 5

- methyl

- 3(2H)

- isoxazolone (CAS Name). It is registered for use as a seed treatment on sugar beet seeds to
control plant diseases which cause seeding loss. It appears as a colorless crystal in its technical

form and is manufactured for use as a wettable powder (WP)

. It is stable under normal use conditions including that of heat and light. The environmental fate and characterization database

for hymexazol illustrates that its biodegradation is a relatively rapid process. It reports a half

- life

of less than 8

- days under aerobic c onditions and less than 2

- days under anaerobic conditions (D428894, J. Wolf, 09/02/15). Hymexazol is stable to abiotic hydrolysis and is very mobile based on its reported adsorption values (K d & K OC ). There is also the possibility of volatilization

from soil and water based on the reported vapor pressure (1.37 x 10

- 3 torr) and Henry’s Law constant value (2.7 x 10

- 9 ). A detailed summary of the physical/chemical characteristics of hymexazol are presented in Appendix B.Hymexazol Human Health Risk Assessment DP No. D425247

Page 9 of 54 3.3 Pesticide Use Pattern

Hymexazol is a fungicide used in seed treatment for control of seedling diseases caused by Aphanomyces spp. and Pythium spp. in sugar beets. T here are no existing registrations for agricultural foliar or residential use sites. Commercial seed treatment fa cilities may use the hymexazol wettable powder (WP) formulation in commercial seed treatment processing to apply hymexazol as either a “ standard pellet ” or a “ minimum pellet ” seed coating

. In either case, hymexazol must be used with an EPA approved dye tha t imparts an unnatural color to the

seed.

Federal Law requires that bags containing treated seeds shall be labeled with the following information. "This seed has been treated with Hymexazol fungicide. Do not use for feed, food or oil purposes. Store away from feeds and foodstuffs."

For Applicati on as a standard pellet: Apply as a commercial seed treatment on pelleted sugar

beet seeds at the rate of 45 to 90 grams of TACHIGAREN® 70 WP per unit of 100,000 seeds (approx. 1 kilogram of raw sugar beet seed). Seed must be pelleted at a minimum weight t o weight ratio of 2:1 pelleting mixture to raw seed.

An application rate with less active ingredient used “minimum pellet build

- up” is also detailed on the available hymexazol product label.

For Application as a minimum build

- up pellet: Apply as a comme rcial seed treatment on

minimum build

- up pelleted sugar beet seeds at the rate of 20 to 30 grams of TACHIGAREN® 70 WP per unit of 100,000 seeds (approx. 1 kilogram of raw sugar beet seed). Seed must be pelleted at a minimum weight to weight ratio of 3:10 p elleting mixture to raw seed.

The existing labeling restricts use of hymexazol “on agricultural establishments in hopper

- box, planter

- box, slurry

- box or other seed

- treatment applications at or immediately before planting.”

Commercial seed treatment uses are registered for sugar beet, and the one wettable powder (WP) formulation can be applied using only commercial seed treatment equipment. The existing use pattern is outlined below in Table 3.3

.

Table 3.3 . Summary of Existing Commercial Seed Treatment Uses of Hymexazol

Formulation [EPA Reg. No.]

Trade Name a Crop Max Applic ation Rate b Use Directions and

Limitations

70 % TACHIGAREN® 70

WP [ 48210

- 1] Sugar beet Standard pellet 90 g product / kg seed 0.056 lb ai/lb seed  90g/100,000

seeds

 Seed must be pelleted at a

minimum weight to weight ratio of 2:1 pelleting

mixture to raw

seed.

a Formulation codes: WP = wettable powder

. b As registered rates are given as “mass ai per seed”, a seed count (# seeds per pound) is needed to convert to “mass

ai per pound seed” for the purposes of estimating exposure . Based on the BEAD memo “Acres Planted Per DayHymexazol Human Health Risk Assessment DP No. D425247

Page 10 of 54 and Seeding Rates of Crops Grown in the United States” (J. Becker, March 2011), the following seed count

conversions were used to convert lb ai/seed ra tes into lb ai/lb seed: sugar beet

– 4 0 ,000 seeds per pound.

3.4 Anticipated Exposure Pathways

Since there are no food uses for hymexazol, exposure from food will not occur. The registered use patterns could result in residues in drinking water, so ther e is potential for exposure from drinking water. There are no residential uses of hymexazol ; and no exposure to hymexazol via spray drift is anticipated.

S hort

- and intermediate

- term dermal and inhalation exposures are anticipated for occupational

handlers commercially treating sugar beet seed, and secondary planters who are planting treated sugar b eet seed in agricultural fields, and potentially from field volatilization of hymexazol

treated seed.

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.archives.gov/federal

- register/executive

- orders /pdf/12898.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 tha t 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 Agricultur e’s (USDA’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 are

evaluated

, 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. Further considerations are currently in dev elopment

, 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 C haracterization and Dose

- Response Assessment

Hymexazol ( 5

- methyl

- 3(2H)

- isoxazolone ) is a systemic fungicide for control of foliar and soil

borne plant diseases. The hymexazol toxicity database is adequate for risk assessment ( See Appendix A).

4.1 Toxicology Studies Available for AnalysisHymexazol Human Health Risk Assessment DP No. D425247

Page 11 of 54 The hymexazol toxicity database is adequate for human health risk assessment; f or additional

information see Appendix A. The following studies were considered in designating the points of departure (PODs) for each exposure scenario:

- 90 day oral toxicity study

– rat, mouse, and dog

- 90 day dermal toxicity study

– rat

- Prenatal developmental toxicity study

– rat and rabbit

- Multi

- generation reproduction and fertility toxicity study

– rat

- 1 year chronic toxicity study

– dog

- 2 year chronic toxicity/carcinogenicity study

– rat

- 2 year carcinogenicity study

- mouse

- Mutagenicity battery

- Subchronic neurotoxicity study

– rat

- Metabolism pharmacokinetics study

– rat

- Immunotoxicity study

The Hazard Science Policy Council ( HAS POC ) recommended waiv ing the requirement for the acute neurotoxicity study (TXR 0056409) using a weight of evidence (WOE) approach including the following considerations: (1) the lack of neurotoxicity in the available toxicity studies for hymexazol ; (2) th e effects seen in the available subchronic neurotoxicity study are at the limit

dose ; and ( 3 ) the known target organ of hymexazol is the liver and not the nervous system.

The HASPOC did not recommend a waiver for the missing 90

- day inhalation study (TXR 0057244) and instead required a subchronic developmental inhalation study based on the following hazard and exposure considerations: 1) the margin of e xposure (MOE = 300) for the

worst case inhalation scenario is not 10 x greater than the l evel of concern ( LOC = 100 ), 2) the adequate ventilation requirement is not well defined on the label and cannot be factored into risk estimates, and 3) developmental and maternal effects are more sensitive endpoints in rodents. In the absence of the inhalation study, a 10 X database uncertainty factor will be applied only for assessing risk for inhalation scenarios until a developmental inhalation study is submitted or other information is provided to support a waiver.

4.2 Absorpt ion, Distribution, Metabolism, and E xcretion (ADME)

Absorption of hymexazol from the diet was complete irrespective of sex. Pharmacokinetics of absorption, however, was distinct in females and males for both low (40 mg/kg/day) and high (1000 mg/kg/day) dose exposures. Female rats absorbed more hymexazol over the exposure period at both doses and achieved a higher peak plasma concentration ( C max – 49.3 and 545 ppm at low and high doses, respectively) compared to males ( C max – 34.9 and 480 ppm at low and high doses, respectively) . Accordingly , the time to reach the maximum concentration was slightly longer in females (T
max = 1 hr in females vs. 30 minutes in males); however

, T max was independent of dose indicating the rate of absorption scaled with increasing dose.

An ephemeral difference in hymexazol distribution was apparent in males and females throughout the first day after dosing. At the low oral dose, female rats were observed to have greater concentrations of radioactivity in blood

, bone

, brain

, fat

, and heart compared to males 3 0

minutes post

- dose. Males, by contrast, showed greater concentrations in liver . A similar sex

specific idiosyncratic distribution pattern was observed at 1 hour in high dose exposures

, thoughHymexazol Human Health Risk Assessment DP No. D425247

Page 12 of 54 the difference in tissue concentration between sexes were not as stark. At both dose levels t he distribution disparity between sexes persisted for 24 hours, after which tissue concentrations were equivalent.

The route of elimination was identical for males and females despite initial differences in

distribution. Urina ry excretion is the dominant route of elimination for both sexes (>90%) with minimal fecal elimination at low doses that increased slightly at higher doses. No significant effects of repeated oral dosing were observed on the total percentage excreted by ur ine or feces. Elimination was rapid in both sexes at the low dose and was delayed slightly at the high dose. At both dose levels, females (t1⁄2 = 14.1

- 21.4 hr) eliminated hymexazol slower than males (t1⁄2 =

4.25

- 7.25 hr). The recalcitrant nature of the hi gh dose impl ies a saturation of elimination mechanisms. Regardless

, a majority of the administered dose was excreted within 24 hours and was near completely eliminated after 7 days. Tissue accumulation was minimal (<1% of administered dose) and primarily s equestered in the carcass (0.22

- 0.34%) and fat (<0.01%) in all sexes at both dose levels. The concentration in the carcass and fat were higher in the females compared to males which may explain the longer half

- life.

Parent hymexazol and four metabolites were detected in urine and/or feces and tissues. The metabolites consisted of the sulfate and glucuronide conjugates of hymexazol, as well as the

oxidative metabolites 3

- hydroxybutanamide and 3

- hydroxybutyric acid. I n urine, the sulfate and glucuronide conjugates were identified as the major metabolites, with the sulfate predominating at the low dose level, while the glucuronide predominated at the high dose. In feces, parent compound was detected only in male rats

. I n blood, the percentages of hymexazol sulfate and hymexazol glucuronide were approximately equal in male rats over the first 2 hours post

- dose at the low dose. In female rat blood, however, the percentage of hymexazol glucuronide increased

from 28 to 52% of sample radioactivity within the first 2 hours . Liver and kidney were found to contain both conjugated as well as oxidative hymexazol metabolites within 30 minutes after dose administration. A minor pathway involves enzymatic reduction of hymexazol to 3

- hydroxybutamide, 3

- hydroxybutyric acid, carbon dioxide, and possible natural products.

4.2.1 Dermal Absorption

The guideline dermal study was not used to set endpoints for the dermal assessment because the study did not address concerns for fetal sensitivity described in the rat developmental study. Instead, an oral endpoint f r om the reproduction study was selected to be protective of potential developmental effects. A dermal absorption study was not submitted for hymexazol ; therefore, a

conservati ve DAF of 100% was used in lieu of an empirically derived value. The physico

chemical data and endpoints from the guideline studies could not be used to r educe the DAF to

less than 100% and no structurally related chemicals were found in the database to in form the

DAF derivation.

4.3 Toxicological Effects

Hymexazol is an oxazole fungicide that limits fungi growth through inhibition of RNA and DNA synthesis . In mammals

, the primary target organ of hymexazol and the organismal response were species specifi c; however

, the mode of action is currently unknown. D ogs were the most
sensitive adult non

- pregnant animal . Subchronic oral exposure targeted the thyroid leading toHymexazol Human Health Risk Assessment DP No. D425247

Page 13 of 54 increased absolute and relative thyroid weight accompanied by minimal increase in epithelial height and minimal to moderate thyroid epithelial hyperplasia. T hyroid effects were only observed in dogs

. Adult r abbits were comparatively less sensitive to hymexazol exposure ; however, their response to exposure was unique from the other speci es. Mortality was observed during gestation in rabbits exposed to approximately twice the dose required to elicit the thyroid effects in dogs. Surviving f emale rabbits exhibited abnormal clinical signs (unsteadiness, slumped posture, increased respiration, and salivation) after the first dose and within an hour post dose. The internal concentration is predicted to peak at 1 hour, which is consistent with the onset of this acute response. T ransient decreased food consumption and periods of body weight loss

d uring the first two day exposure period further compromised the health of the pregnant rabbits

and likely contributed to the developmental malformations in the young discussed below

. Adult

non

- pregnant rodents were the least sensitive to oral hymexazol exp osure requiring dietary dose s at least 2x greater than rabbits and dogs to elicit liver (increased liver weight with associated centrilobular hepatocyte enlargement and granulo matous inflammation, elevated liver enzyme s in serum ) effects and significant reductions in body weight and body weight gain. High oral doses were also required to induce acute toxicity in rodents (Category III). Rodents were, however, susceptible to acute ocular exposure which manifest ed in severe eye irrit ation, and corneal opacity with hyperaemic blood vessels (Category I). Rapid elimination and low accumulation of ingested hymexazol limited progression of toxicity with increased exposure

duration in all species tested.

Pregnant rats and rabbits, and the ir developing fetuses exhibited enhanced sensitivity to hymexazol exposure relative to non

- pregnant adult rodents. Gavage fed r at d ams produced

fetuses with r eductions in ossification of the cervical, thoracic, lumbar, & caudal vertebrae, as

well as in the pelvic girdle & in the fore

- & hind

- extremities (metacarpals & metatarsals), significantly increased incidence of bilateral 14th ribs

, and reduced body weight without signs of maternal toxicity at 500 mg/kg/day

. At a similar dose, fetal rabbits exhibited distinct effects in the heart (heart/great vessel malformations, particularly incomplete inferior vena cava), along with reduced fetal weight and increased incidence of reduced sternebrae

. C ontrary to the rats, these effects were observed in concert with maternal toxicity (mortality, body weight loss and clinical signs described above) and, therefore, were not indications of susceptibility in developing rabbits

. D ietary exposure at 159 mg/kg/day in the F 0 and F 1 rats from the pre

- mating period through parturition caused a reduction in post implantation survival and litter size in the

F 1 and F 2 offspring

. T he post

- implantation loss and its subsequent impact on litter size were attributed to both compromised healt h in the dams and in utero exposure. Reproduction was not affected by hymexazol exposure up to 159 mg/kg/day.

Hymexazol is a skin sensitizer; however, dermal exposure did not irritate the skin ( d ermal

irrita tion: Category IV) and high dermal doses were required to elicit acute (Category III) and subchronic systemic toxicity.

Other critical physiological systems (neurological, immune, and respiratory) were not principle

target s of hymexazol. Neurological effects, decreased brain weight and cerebral length in males, were equivocal and only evident near the limit dose. The respiratory system was unaffected in

oral and dermal exposures and rats were relatively tolerant of acute inhalation exposures (Category III). No effects on the immune system were o bserved in an oral exposure up to the

limit dose.Hymexazol Human Health Risk Assessment DP No. D425247

Page 14 of 54 4.4 Safety Factor for Infants and Children (FQPA Safety Factor)

Hymexazol is not a food

- use chemical and has no tolerances set based upon plant metabolism

data

, which showed it to be metabolized to carbon dioxide (CO 2 ) and incorporated into sugars. Therefore, FQPA does not apply.

4.4.1 Completeness of the Toxicology Database

The toxicity database is adequate for assessing the susceptibility of infants and child ren to hymexazol exposure. Qualitative and quantitative susceptibility at critical developmental life stages was addressed in two guideline developmental studies, and a 2 generation reproduction study. Additionally, a neurotoxicity battery and immunotoxici ty study were available to assess unique toxicity in these systems. An inhalation study is not available for assessing route specific toxicity and may have implications on infant and child exposure. Based on a weight of evidence approach, the HASPOC recommended that a subchronic developmental inhalation study should

be required (TXR 0057244). The decision was made after careful consideration of all the available hazard and exposure information including: 1) worst case inhalation MOE of 300 for

workers without respiratory protection operating at the maximum single seed treatment application rate

, 2) the adequate ventilation requirement is not well defined on the label and cannot be factored into risk estimates, and 3) developmental and maternal effects are more sensitive endpoints in rodents. In the absence of this study, a 10X database uncertainty factor will be applied only for assessing risk for inhalation scenarios until an inhalation study is submitted or other information is provided to support a w aiver.

4.4.2 Evidence of Neurotoxicity

There was evidence of neurotoxicity in the subchronic neurotoxicity ( SCN ) study; however, concern is low as the effects were only seen in males at a dose approaching the limit dose, the

effects have clear NOAEL/LOAE L values, there were no other effects on the nervous system observed in the database, and the risk assessment endpoints chosen are protective for these

effects.

4.4.3 Evidence of Sensitivity/Susceptibility in the Developing or Young Animal

Developing ra ts were qualitatively and quantitatively more sensitive to hymexazol exposure compared to adults in the developmental rat study; however

, concern for infant and young animal susceptibility is low. Clear NOAELs and LOAELs were established in both developmen tal studies and the 2 generation reproduction study and the selected endpoints are protective for these effects (see section 4.5.1).

4.5 Toxicology Endpoint and Point of Departure Selections

4.5.1 Dose

- Response AssessmentHymexazol Human Health Risk Assessment DP No. D425247

Page 15 of 54 Toxicity endpoints and points of departure (PODs) for dietary and non

- dietary exposure scenarios to hymexazol are summarized below. Detailed description s of the studies used as a basis for the selected endpoints are presented in Appendix A.

A n acute reference dose (a RfD) for the general population was established at 1.5 mg/kg/day

based on acute maternal effects in the rabbit developmental study. The N OAEL for the maternal

effects was 150 mg/kg/day based on m ortality, abnormal clinical signs ( unsteadin ess, slumped posture, incre ased respiration and salivation) within an hour after the first dose

, and decreased food consumption and body weight loss within 2 days of initial exposure at the LOAEL of 450 mg/kg/day

. The se were the only acute effects observed across the gamut of submitted studies. The POD derived from this NOAEL is protective of acute developmental effects observed in the rat developmental study. The post implantation loss observed in the 2

- generation reproduction study was also not used as a dietary POD for women 13

- 49. Post

- implantation loss was not observed at a similar dose in the shorter duration rat development study indicating this effect required a longer exposure duration to manifest. A UF 100x (10x to account for interspecies extrapol ation and 10x for intraspecies variation) was applied to the NOAEL to calculate the

a RfD.

A chronic reference dose (cRfD) was established at 0.31 mg/kg/day based on adverse offspring

effects observed in the F 1 and F 2 offspring at the LOAEL in the two generation reproductive study. The NOAEL for the offspring effects was 31 mg/kg/day based on reduced post

implantation survival rate and de creased litter size at the LOAEL of 159 mg/kg/day. The offspring NOAEL in the reproduction study is the lo west POD in the toxicity database and is protective of the developmental effects observed at higher doses (450

- 500 mg/kg/day) in the rat and rabbit development study and the thyroid effects observed in the subchronic dog study. A UF 100x (10x to account fo r interspecies extrapolation and 10x for intraspecies variation) was applied to the NOAEL to calculate the cRfD.

The offspring NOAEL from the two general reproduction study was used to set points of departure (POD) for the short

- (1

- 30 days) and intermed iate

- term (1

- 6 months) dermal exposures as well. The submitted dermal study did not examine potential developmental impacts from the dermal exposure that were observed in the developmental and reproduction studies. No dermal absorption study was submitted; therefore, a DAF of 100% was assumed for the exposure

assessment. A 100x UF (10x to account for interspecies extrapolation and 10x for intraspecies variation) was applied to the NOAELs for these exposures.

In the absence of a route specific study, t he of fspring NOAEL from the two general reproduction study was used for the short

- (1

- 30 days) and intermediate

- term (1

- 6 months) inhalation

exposures. Toxicity from inhalation was assumed to be equivalent to an oral exposure. A 100 0 x UF (10x to account for int erspecies extrapolation

, 10x for intraspecies variation , and 10x database uncertainty factor ) was applied to the NOAELs for these exposures as well. The HASPOC determined that a subchronic developmental inhalation study is required for hymexazol; therefore, a 10X database uncertainty factor was applied for assessing inhalation scenarios until a developmental inhalation study is submitted or other information is provided to support a waiver.

4.5.2 Recommendations for Combining Routes of Exposure for Risk AssessmentHymexazol Human Health Risk Assessment DP No. D425247

Page 16 of 54 When there are potential residential exposures to the pesticide, risk assessment must consider exposures from three major sources: oral, dermal and inhalation exposures. If the toxicity endpoints for d ermal, oral, and inhalation routes of exposure are similar

, the exposure or risk estimates from these exposure routes need to be combined. Exposure routes are combined in Section 11 (the worker assessment) because toxic effects are common between the inhal ation and dermal routes of exposure. A total aggregated risk index (ARI) was used since the LOC values for dermal exposure (100) and inhalation exposure (1000) are different.

4.5.3 Cancer Classification and Risk Assessment Recommendation

There is no ev idence linking hymexazol to a carcinogenic and mutagenic mode of action. Rats and mice exposed to hymexazol at high doses (> 500 mg/kg/day) for two years did not develop neoplastic tumors and no signs of mutagenicity were reported in gene mutation, mouse lymphoma, or micronucleus assays. In accordance with the Agency’s 2005 Guideline for Carcinogen Risk Assessment, the hymexazol team has classified hymexazol as “ Not Likely to be Carcinogenic to Humans ”.

4.5.4 Summary of Points of Departure and Toxicity Endpoints Used in Human Risk

Assessment

A summary of points of departure used in the hymexazol dietary / non

- occupational (Tabl e 4.5.4.1) and occupational (Table 4.5.4.2) human health risk assessment are presented below.

Table 4.5.4.1 Summary of Toxicological Doses and Endpoints for Hymexazol for Use in Dietary and Non

Occupational Human Health Risk Assessments

Exposure/

Scenario Point of

Departure Uncertainty

Factors RfD, PAD,

Level of

Concern for

Risk

Assessment Study and Toxicological Effects

Acute Dietary ( General Population ) NOAEL =

150 mg/kg/day UF A = 10x

UF H =10x aRfD = 1.5

mg/kg/day Developmental

– rabbit

Maternal LOAEL = 450 mg/kg/day based on mortality, abnormal clinical signs (unsteadiness, slumped posture, increased respiration, and salivation) within an hour of dosing, and decreased food consumption and body weight loss within 2 days of initial exposure

Acute Dietary ( Females 13

- 49 ) A n acute RfD specific to Females 13

- 49 was not calculated because no effect attributable to a

single day oral exposure that would be specific to this population subgroup was observed in the toxicity database including the developme ntal and reproduction studies

.

Chronic Dietary (All Populations) NOAEL =

31 mg/kg/day UF A = 10x

UF H =10x c RfD = 0.3

mg/kg/day 2

- generation reproduction

– rat

Parental/ Offspring LOAEL = 159 mg/kg

based on i ncrease in post

- implantation loss, decrease in litter sizeHymexazol Human Health Risk Assessment DP No. D425247

Page 17 of 54 Table 4.5.4.1 Summary of Toxicological Doses and Endpoints for Hymexazol for Use in Dietary and Non

Occupational Human Health Risk Assessments

Exposure/

Scenario Point of

Departure Uncertainty

Factors RfD, PAD,

Level of

Concern for

Risk

Assessment Study and Toxicological Effects

Incidental Oral, Dermal,

Inhalation There are no registered residential uses for hymexazol and no residential exposures anticipated

from application adhering to the labels of registered uses.

Cancer (oral, dermal, inhalation) Hymexazol is not carcinogenic in long term studies with rats and mice and not mutagenic in the

gene mutation, mouse lymphoma, and micronucleus assays. In accordance with the Agency’s 2005 Guideline for Carcinogen Risk Assessment, hymexazol is classified as “ Not Likely to be Carcinogenic to Humans ”. 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. UF A = extrapolation from animal to human (interspecies). UF H = potential variation in sensitivity among members of the human population (intraspecies). RfD = reference dose. N/A = not applicable.

Table 4.5.4.2 Summary of Toxicological Doses and Endpoints for Hymexazol for Use in Occupational

Human Health Ri sk Assessments

Exposure/

Scenario Point of

Departure Uncertainty

Factors Level of Concern

for Risk

Assessment Study and Toxicological Effects

Dermal

Short

- and

Intermediate

Term NOAEL =

31 mg/kg/day UF A =10x

UF H =10x LOC for MOE =

100 2

- generation reproduction

– rat

Parental/ Offspring LOAEL = 159 mg/kg

based on i ncrease in post

- implantation loss, decrease in litter size

Inhalation

Short

- and

Intermediate

Term NOAEL =

31 mg/kg/day UF A =10x

UF H =10x

UF DB =10x LOC for MOE =

100 0 2

- generation reproduction

– rat

Parental/ Offspring LOAEL = 159 mg/kg

based on i ncrease in post

- implantation loss, decrease in litter size

Cancer (dermal, inhalation) Hymexazol is not carcinogenic in long term studies with rats and mice and not mutagenic in the

gene mutation, mouse lymphoma, and micronucleus assays. In accordance with the Agency’s 2005 Guideline for Carcinogen Risk Assessment, hymexazol is classified as “ Not Likely to be Carcinogenic to Humans ”. 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 ob served adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UF A = extrapolation from animal to human (interspecies). UF H = potential variation in sensitivity among members of the human population (intraspecies). MOE = margin of exposure. LOC = level of concern. N/A = not applicable.

4.6 Endocrine Disruption

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse outcomes from exposure to chemicals. Collectively, these studies i nclude acute, subchronic and chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, reproductive, and general or systemic toxicity. These studies include endpoints which may be susceptible to endocrine influence, includin g effects on endocrine target organ histopathology, organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss,Hymexazol Human Health Risk Assessment DP No. D425247

Page 18 of 54 and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and

chronic stu dies that assess growth, developmental and reproductive effects in different taxonomic groups. As part of its reregistration decision for hymexazol , EPA reviewed these data and selected the most sensitive endpoints for relevant risk assessment scenarios fr om the existing hazard database. However, as required by FFDCA section 408(p), TCVP is subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determine whether certain substances (inclu ding pesticide active and other ingredients) may have an effect in humans or wildlife similar to an effect produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator may designate.” The EDSP employs a two

- tiered appro ach to making the statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that g o through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on the available data. Ti er 2 testing is designed to identify any adverse endocrine

- related effects caused by the substance, and

establish a dose

- response relationship between the dose and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must screen all pesticide che micals. Between October 2009 and February 2010, EPA issued test orders/data call

- ins for the first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals identified for EDSP screening was p ublished on June 14, 2013 3 and includes some pesticides scheduled for Registration Review and chemicals found in water

. Neither of these lists should be construed as a list of known or likely endocrine disruptors.

For further information on the status of the EDSP, the policies and procedures, the lists of chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our

website. 4

5.0 Dietary Exposure and Risk Assessment

5.1 Metabolite/Degradate Residue Profile

5.1.1 Sum mary of Plant and Animal Metabolism Studies

The nature of the residue in plants is adequately understood based on a sugar beet metabolism study that was submitted. Normally, the uptake of radioactivity would lead the Agency t o conclude that the treatment of sugar beet seeds is a food use. However, considering the low level of activity and the substantial evidence that hymexazol has been metabolized/degraded to carbon dioxide ( CO 2 )

, which in turn

, is incorporated into sugars, the Agency considers the treatment of sugar beet seeds with hymexazol to be a non

- food use for the registration of this seed treatment (D200191, J. Morales, 04/04/1994)

.

3 See http://www.regulations.gov/#!documentDetail;D=EPA

- HQ

- OPPT

- 2009

- 0477

- 0074 for the final second list of

chemicals.

4 http://www.epa.gov/endo/Hymexazol Human Health Risk Assessment DP No. D425247

Page 19 of 54 Data pertaining to livestock metabolism are not required to support hymexazol use on sugar beet

seeds.

5.1.2 Summary of Environmental Degradation

The biodegradation of hymexazol is found to be a relatively rapid process. Its chemical species

are short

- lived and transient. The end products are carbon dioxide (CO 2 ) under aerobic conditions and methane (CH 4 ) under anaerobic conditions. The metabolite 5

- methyl

- 2(3H)

- oxazolone was proposed as a possible intermediate in the degradation of hymexazol to CO 2 , but it was not identified in the aerobic soil metabolism study (D428894, J. Wo lf, 09/02/2015).

5.1.3 Comparison of Metabolic Pathways

As mentioned in the previous section, t he biodegradation of hymexazol was found to be a rapid process forming carbon dioxide (CO 2 ) under aerobic conditions and methane (CH 4 ) under

anaerobic conditions. In plants, the submitted sugar beet metabolism study showed that hymexazol is metabolized to carbon dioxide (CO 2 ) and incorporated into sugars. R at metabolism

data are also available which show the excretion of hymexazol derived radioactivity is largely through urine. The metabolites of hymexazol identified in this study include the glucuronic acid and sulfate conjugates of hymexazol, and the oxidative metabolites 3

- hydroxybutamide and 3

- hydroxybutyric acid. Urine showed mainly hymexazol con jugates, while oxidative metabolites were found in liver and kidney of both sexes.

5.1.4 Residues of Concern Summary and Rationale

There are no uses for hymexazol which require residues of concern to be established for

tolerance enforcement and risk asse ssment on food/feed crops and/or livestock. Dietary exposure may occur through drinking water. Because there are no toxic degradates and no new fate data have been received, the Risk Assessment Branch (RAB) V/VII risk assessment team has concluded that p arent hymexazol only is the residue included in risk assessment for drinking

water.

5.2 Food Residue Profile

The residue chemistry database is complete in supporting the use of the fungicide hymexazol for treating sugar beet seeds. A metabolism study wa s provided which demonstrated that hymexazol

is a non

- food

- use chemical since it is metabolized to carbon dioxide (CO 2 ) and incorporated into sugars (D200191, J. Morales, 04/04/1994). No additional residue chemistry data are thus required. The r egistered use will not result in residues on food.

5.3 Water Residue Profile

D rinking water exposure is considered since hymexazol is used outdoors as a seed treatment for sugar beets. The EDWCs used for dietary analyses were provided by EFED in the mem orandum “Hymexazol: Drinking Water Assessment for Registration Review” (D428894, J. Wolf, 09/02/2015). This drinking water assessment completed by EFED was conducted for parentHymexazol Human Health Risk Assessment DP No. D425247

Page 20 of 54 hymexazol only since there are no degradates of concern. The resulting EDWCs determined for hymexazol were incorporated into the DEEM

- FCID program for analysis in the food categories “water, direct, all sources” and “water, indirect, all sources.”

To estimate EDWCs, models including the Surface Water Concentration Calculator (SWCC) for

surface water and PRZM

- GW for groundwater were used. The assessment was based on the maximum seeding rate for sugar beets which results in application rates of 0.126 to 1.25 lb ai/A. The method of hymexazol chemical application is by seeding with incorporation or drilling

which is assumed to be 7

- days before crop emergence with zero spray drift since the pesticide is applied directly to the seed. Because there is no leeching study available, the EFED analyses assume that 100% of the hymexazol product applied to the seed will be available for leeching

and runoff.

EFED modeling found groundwater exposure concentrations to be higher than surface water estimates. Based upon groundwater modeling analysis using the Wisconsin central sand s scenario, the recommended EDWCs for risk assessment were calculated to be 66.6 ppb for the peak, and 54.5 ppb for the chronic exposure. The se model s and their description s are available

at the EPA internet site: http://www.epa.gov/oppefed1/models/water/

.

The recommended EDWCs for hymexazol calculated by EFED for risk assessment are

summarized below in Table 5.3

.

Table 5.3 . Estimated Drinking Water Concentrations (EDWCs) for Hymexazol

. Drinking Water Source [Model] Scenario [application rate] Acute Chronic Cancer

Surface Water (SWCC) a MN Sugar Beets [1.25 lb a.i./A] 1

- in

- 10 yr 30

- yr Avg. μg/L

32.80 7.69 2.67 Groundwater (PRZM

- GW) WI Central Sands Highest daily Conc. Post breakthrough Avg
[1.25 lb a.i./A] 66.6 54.5

a PCA was not applied since groundwater is greater than surface water.

5.4 Dietary Risk Assessment

5.4.1 Overview of Residue Data Used

Given that the only use of hymexazol is commercial sugar beet seed, there are no food or feed uses that require the establishment of tolerances. However, there is potential for hymexazol to reach drinking water sources through its outdoor application to sugar beet seeds which require s a drinking water assessment to be per formed. Therefore, the dietary assessment conducted for hymexazol i s performed using model

- derived EDWCs.

5.4.2 Percent Crop Treated Used in Dietary Assessment

Percent crop treated information is not relevant for analysis because a food dietary as sessment is not required for hymexazol.

5.4.3 Acute Dietary Risk AssessmentHymexazol Human Health Risk Assessment DP No. D425247

Page 21 of 54 The acute dietary (drinking water only) exposure analysis and risk assessment conducted is a conservative determination using model

- derived EDWCs for all direct and indirect wat er sources provided by the Environmental Fate and Effects Division (EFED). It was conducted for the general U.S. population and all population subgroups since an acute toxicological endpoint was

identified for all populations

. The acute r isk estimate s w ere well be low the Agency’s level of

concern (LOC) ( i.e. , <100% of the acute reference dose ( aRfD ))

. The estimated risk for hymexazol from drinking water f or the general U.S. population and all population subgroups

exposure is <1 % of the aRfD at the 9 5 th percentile.

5.4.4 Chronic Dietary Risk Assessment

The chronic dietary (drinking water only) exposure and risk assessment is also considered

conservative and is based on model

- derived EDWCs for all direct and indirect water sources. It was conducted for the general U.S. population and all population subgr oups since a chronic toxicological endpoint was identified for all populations

. The chronic dietary risk estimates for hymexazol are below the Agency’s level of concern for the general U.S. population and all population subgroups. For the general U.S. po pulation and all population subgroups exposure is

<1 % of the chronic reference dose ( cRfD )

.

5.4.5 Cancer Dietary Risk Assessment

A cancer dietary exposure and risk assessment was not conducted since hymexazol is not likely to be carcinogenic to humans.

5.4.6. Dietary Assessment Summary Tables

The results of the acute and chronic drinking water only dietary exposure analysis is reported in

Table 5.4.6. Risks do not exceed the Agency’s level of concern

.

Table 5.4.6

. Summary of Dietary (Drinking W ater) Exposure and Risk for the Hymexazol.

Population Subgroup Acute Dietary 1
(95 th Percentile) Chronic Dietary 2

Dietary Exposure (mg/kg/day) % aRfD Dietary Exposure (mg/kg/day) % cRfD

General U.S. Population 0.003631 <1 0.001141 <1

All Infants (< 1 year old) 0.011374 <1 0.00 2943 <1

Children 1

- 2 years old 0.005600 <1 0.001646 <1

Children 3

- 5 years old 0.004544 <1 0.001387 <1

Children 6

- 12 years old 0.003472 <1 0.001000 <1

Youth 13

- 19 years old 0.003024 <1 0.000832 <1

Adults 20

- 49 years old 0.003574 <1 0.001139 <1

Adults 50

- 99 years old 0.003183 <1 0.001126 <1Hymexazol Human Health Risk Assessment DP No. D425247

Page 22 of 54 Table 5.4.6

. Summary of Dietary (Drinking W ater) Exposure and Risk for the Hymexazol.

Population Subgroup Acute Dietary 1
(95 th Percentile) Chronic Dietary 2

Dietary Exposure (mg/kg/day) % aRfD Dietary Exposure (mg/kg/day) % cRfD

Females 13

- 49 years old NA NA 0.001134 <1

1 Acute dietary analysis derived from a 1.5 mg/kg/day aRfD for the general population

. 2 Chronic dietary analysis derived from a 0. 31 mg/kg/day cRfD for the general population.

3 Highest exposures found for each assessment are noted in bold.

4 NA

– “Not assessed” because no attributable effect was identified

6.0 Residential (Non

- Occupational) Exposure/Risk Characterization

6. 1 Residential Handler Exposure

HED uses the term “handlers” to describe those individuals who are involved in the pesticide application process. There are currently no registered or proposed residential uses for hymexazol ; therefore, a residential handler assessment was not performed.

6. 2 Post

- Application Exposure

There are currently no registered or proposed residential uses for hymexazol ; therefore, a residential post

- application assessment was not performed

.

7.0 Non

- Occupational Spray Drift Exposur e and Risk Estimates

Spray drift is a potential source of exposure to those nearby pesticide applications. Where appropriate, the potential for spray drift will be quantitatively evaluated for each pesticide during the Registration Review process which e nsures that all uses for that pesticide will be considered concurrently. In the case of hymexazol, the only registered use is commercial seed treatment. Planting pelleted seed treated with hymexazol is not anticipated to result in spray drift.

8.0 Non

- Occupational Bystander Post

- Application Inhalation Exposure and Risk

Estimates

Volatilization of pesticides may be a source of post

- application inhalation exposure to

individuals nearb y pesticide applications. The A gency sought expert advice and input on issues related to volatilization of pesticides from its FIFRA SAP in December 2009, and received the SAP’s final report on March 2, 2010

. 5 The A gency has evaluated the SAP report and has developed a Volatilization Screening Tool and a subsequent Volatilization Screening Analysis

. 6

D uring Registration Review, the A gency will utilize this analysis to determ ine if data (i.e., flux studies) or further analysis are required for hymexazol

.

9. 0 Aggregate Exposure/Risk Characterization

5 http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html

6 http:/ /www.regulations.gov/#!docketDetail;D=EPA

- HQ

- OPP

- 2014

- 0219Hymexazol Human Health Risk Assessment DP No. D425247

Page 23 of 54 In accordance w ith the FQPA, HED must consider and aggregate (add) pesticide exposures and risks from three major sources: food, drinking water, and residential exposures. Although there is the potential for hymexazol to enter drinking water sources from the nonfood

us e on seeds, there are no food or residential uses or exposures; therefore, aggregate exposure includes only exposure from drinking water . There are no risks of concern for hymexazol in drinking water.

10. 0 Cumulative Exposure/Risk Characterization

Unlike other pesticides for which EPA has followed a cumulative risk approach based on a common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as

to hymexazol and any other substances ; additionally, hymexazol does not appear to produce a toxic metabolite produced by other substances. For the purposes of this action, therefore, EPA

has not assumed that hymexazol has a common mechanism of toxicity with other substances. For information regarding EPA’s efforts to determine whic h chemicals have a common mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see the policy statements released by EPA’s Office of Pesticide Programs concerning common mechanism determinations and procedures for cumulating effe cts from substances found to have a common

mechanism on EPA’s website 7

.

11 .0 Occupational Exposure/Risk Characterization

11 .1 Short

- and Intermediate

- T erm Handler Risk

HED uses the term handlers to describe those individuals who are involved in the pesticide application process. HED believes that there are distinct job functions or tasks related to applications and exposures can vary depending on the specifics of each task. Job requirements (amount of chemical used in each application), the kinds of equipment used, the target being treated, and the level of protecti ve gear or controls used by a handler can cause exposure levels to differ in a manner specific to each application event.

Based on the existing seed treatment registration (sugar beet ), occupational handler exposure is expected . Occupational seed treatment handlers may experience short

- and intermediate

- term
exposure to hymexazol while performing seed treatment activities in commercial settings. In addition, occupational handlers may experience short

- and intermediate

- term exposure while planting hymexazol

- treated seeds (for the purposes of seed treatment risk assessment , planting treated seeds are referred to as ‘secondary handlers’).

Treating Seed (Primary Handler)

Potential occu pational exposure scenarios from the use of hymexazol as a commercial seed treatment include: mixing, loading, applying wettable powder formulations; bagging treated seed; sewing bags; and multiple activities. Typically, for large

- scale commercial

seed tr eatments, workers perform only those specific individual tasks listed above; however, it is assumed that workers also may perform multiple activities throughout the day. As a result a “multiple activities” scenario (i.e. where one worker performs all seed

7 Available: http://www.epa.gov/pesticides/cumulative/Hymexazol Human Health Risk Assessment DP No. D425247

Page 24 of 54 treatment tasks such as loading/applying, sewing, bagging, cleaning, calibration, repair, forklift driver, etc.) was addressed.

Planting Treated Seed (Secondary Handler) Potential occupational exposure scenarios from the use of hyme xazol as a commercial seed treatment include planting treated seed (secondary handler). Planting treated seed consists of the farmer purchasing bags of treated seed, placing the seed in the hopper and applying seed to fields.

The quantitative exposure/ri sk assessment developed for occupational handlers is based on the following scenarios:

 Mixer

– wettable powder slurry

 Mixing/loading/applying wettable powders;

 Bagging treated seeds;

 Sewing bags with treated seeds;

 Multiple (commercial) seed treatment activities; and,

 Planting treated seeds.

Occupational Handler Exposure Data and Assumptions

A series of assumptions and exposure factors served as the basis for completing the occupational

h andler risk assessments. A ssumption s and factor s, as well as algorithms used to estimate non

cancer exposure and dose for occupational handlers

, are detailed in the most recent ORE memo (L loyd

, 2015

, D 42929 8 ).

Based on the registered use pattern for hymexazol ( commercial seed treatment only) , short

- and

intermediate

- term exposures are expected, and the POD selected for dermal/ inhalation risk assessment is protective of both exposure durations. Long

- term exposures are not anticipated. The maximum single application rate for sugar beet seed treatment is the “standard pellet” scenario. A lower application rate (“minimum buildup” scenario) is also an option based on the label, although it is rarely used in commercial seed treatment practice.

Applicators and mixer/loaders who handle hymexazol, such as in commercial seed treatment facilities, must wear long

- sleeved shirt and long pants, chemical

- resistant gloves made from any waterproof material, shoes plus socks, protective eyewear, and in the absence of adequate ventilation or dust control systems, a non

- powered air purifying respirator equipped with a R

or P

- series filter. Baggers and other persons who handle treated seed, such as in commercial seed treatment facilities, must wear the same protection as applicators and mixer/loaders minus

the chemical resistant gloves.

Combining Exposures/Risk Estimates Exposure routes are combined because toxic effects are common between the inhalation and dermal routes of exposure. A total aggregated risk index (ARI) was used since the LOC values for dermal exposure (100) and inhalation exposure (1000) are different. The target ARI is 1; therefore, ARIs of less than 1 are risk estimates of concern. The aggregate risk index (ARI) was

calculated as follows.Hymexazol Human Health Risk Assessment DP No. D425247

Page 25 of 54 Aggregate Risk Index (ARI) = 1÷ [(Dermal LOC ÷ Dermal MOE) + (Inhalation LOC ÷ Inhalation MOE)]

Summary of Occupational Handler Non

- Cancer Exposure and Risk Estimates

Occupational handler risk estimates are presented below in Table 11.1 (seed treaters) and 11.2 (secondary planters) . The occupational handler risk estimates for seed treatment are presented for the “standard pellet” application scenario (the maximum application rate).

The results of the occupational handler exposure and risk assessment indicate that short

- and

interm ediate

- term combined dermal and inhalation risk estimates exceed HED’s LOC in some

cases. R isk estimates of concern were identified for the following “standard pellet” scenarios:

 Mixer (wettable powder)

– combined ARI of 0.22

 Multiple Activities (w/o glov es)

– combined ARI of 0.87

Overall, d ermal MOEs range from 76 to 2

, 1 00 for seed treaters (LOC = 100)

. The multiple activities (w/o gloves) scenario has a combined ARI below 1 (0.87) because the dermal MOE is

97. Inhalation MOEs range from 300 to 81

, 000 fo r seed treaters (LOC = 1,000)

. For the mixer scenario, the addition of a filtering facepiece respirator (PF5) results in an inhalation MOE of 1,500, although the ARI is still below 1. Combined risk estimates for the wettable powder mixer

exceed the ARI LOC of 1 only when engineering controls (i.e., water soluble packets) are

considered.Hymexazol Human Health Risk Assessment DP No. D425247

Page 26 of 54 Table 11.1 Summary of Short

- and Intermediate

- Term Handler Exposures and Risks for Hymexazol Seed Treatment

Seed Type [sugarbeet] Max Application

Rate 1 Unit Exposure 2

(mg/lb ai) Amount of

Seed Treated 3 Absorbed Dose (mg/kg/day) 4 MOE 5

Total ARI 6

lb ai/lb seed Dermal Inhal

. lb seed/day Dermal Inhal

. Dermal

(LOC = 100) Inhal

.

(LOC = 1 ,0 00)

Mixer

- Wettable Powder (single layer, gloves , no respirator )

Standard Pellet 0.05 6 0.170 0.0434 3,000 0.4 1 0.104 76 300 0.22

Mixer

- Wettable Powder ( double layer, gloves , no respirator )

Standard Pellet 0.05 6 0.1 3 0 0.0434 3,000 0. 31 0.104 100 300 0.23

Mixer

- Wettable Powder ( double layer, gloves , PF5 respirator )

Standard Pellet 0.05 6 0.1 3 0 0.0 0868 3,000 0. 31 0. 021 100 1500 0.6

Mixer

- Wettable Powder ( water soluble packets, no respirator )

Standard Pellet 0.05 6 0. 0098 0.0434 3,000 0.0 23 0. 001 1,300 54,000 10.5
LOADER/APPLICATOR (single layer, gloves 7 )

Standard Pellet 0.056 0.023 0.00034 3,000 0. 055 0.001 560 38,000 4.9
SEWER (single layer, no gloves)

Standard Pellet 0.0 56 0.0062 0.00023 3,000 0.0173 0.0006 2,100 56,000 15.3
BAGGER (single layer, no gloves) Standard pellet 0.0 56 0.0091 0.00016 3,000 0.02532 0.00045 1,400 81,000 11.9

MULTIPLE ACTIVITIES (combination of loader/applicator with out gloves 7 + no coveralls, sewer without gloves, stacker without gloves)

Standard pellet 0.056 0.134 0.0016 3,000 0.3 20 0.00 38 97 8,100 0.87

MULTIPLE ACTIVITIES (combination of loader/applicator with gloves 7 + no coveralls, sewer with gloves, stacker with gloves)
Standard pellet 0.0 56 0.042 0.0016 3,000 0.1 00 0.00 38 310 8

, 1 00 2.2

1 Application Rates based on existing label uses for hymexazol (see Table 4.1).

2 Unit Exposures from HED Exposure Science Advisory Council Policy 14.

3 HED default for lb seed treated per day from HED Exposure Science Advisory Council Interim Policy 15 .1 and the BEAD memo “Acres Planted Per Day and Seeding Rates of Crops Grown in the United States ” (J. Becker, March 2011).

4 Daily Absorbed Dose (mg/kg/da y) = daily unit exposure ( m g/ lb ai) × ap plication rate (lb ai/lb seed) × amount treated (lb seed/day) × Absorption (100% for dermal, 100% for inhalation) ÷ body weight (69 kg adult female for dermal exposure due to sex

- specific toxicity;

5 MOE = NOAEL ( d ermal = 31 mg/kg/day for short

- and intermediate

- term exposure; inhalation = 31 mg/kg/day for short

- and intermediate

- term ) ÷ Absorbed Dose (mg/kg/day) . LOC = 100.

6 ARI = Aggregate Risk Index = 1÷ [(Dermal LOC ÷ Dermal MOE) + (Inhalation LOC ÷ Inhalati on MOE)].

7 Available data represents workers wearing chemical

- resistant gloves and other label

- represented PPE.Hymexazol Human Health Risk Assessment DP No. D425247

Page 27 of 54 Table 11 .2

. Summary of Secondary Handler (Planter) Exposure and Risk Estimates for Hymexazol ( Single Layer, Gloves during Loading Only)

.

Seed Type Max

Application

Rate a Unit Exposure b

(mg/lb ai) Amount

of Seed

Planted

Per Day c Absorbed Dose

(mg/kg/day) d MOE e Total ARI f

lb ai/lb seed Dermal Inhal. lb seed/day Dermal Inhal. Dermal

(LOC = 100) Inhal

.

(LOC =

1 ,0 00)
Standard

Pellet 0.056 0.25 0.0034 87 1 0.174 0.00 24 180 13,000 1.6

a Application Rates based on proposed label uses for hymexazol (see Table 4.1).

b Unit Exposures from HED Exposure Science Advisory Council Policy 14: Standard Operating Procedures for Seed Treatment. Available data represents workers wearing chemical

- resistant gloves. Unit exposures representing workers without chemical

- resistant gloves were calculated by increasing exposure to the hands

- only portion of the total dermal exposure measurement assuming chemical

- resistant gloves provide 90% protection (i.e., dividing non

- gloved hand exposures by 0.1), the standard protection factor assumption for chemical

- resistant glove s.

c HED default for lb seed planted per day for sugar beets from HED Exposure Science Advisory Council Interim Policy 15 and the BEAD memo “Acres Planted Per Day and Seeding Rates of Crops Grown in the United States ” (J. Becker, March 2011).

d Daily Absorbed Dose (mg/kg/day) = daily unit exposure ( m g/ lb ai) × ap plication rate (lb ai/lb seed) × amount treated (lb seed/day) × Absorption (100% for dermal, 100% for inhalation) ÷ body weight (69 kg ).

e MOE = NOAEL ( dermal = 31 mg/kg/day for short

- and intermediate

- term exposure; inhalation = 31 mg/kg/day for short

- and intermediate

term ) ÷ Absorbed Dose (mg/kg/day) . LOC = 100.

f ARI = Aggregate Risk Index = 1÷ [(Dermal LOC ÷ Dermal MOE) + (Inhalation LOC ÷ Inhalation MOE)].

11 .2 Short

- and Intermediate

- Term Post

- Application Risk

HED uses the term post

- application to describe exposures that occur when individuals are present in an environment that has been previously treated with a pesticide (also referred to as re

entry exposure). Suc h exposures may occur when workers enter previously treated areas to perform job functions, including activities related to crop production, such as scouting for pests or harvesting.

The potential for dermal and inhalation post

- application exposures fol lowing the planting of hymexazol

- treated seeds is unlikely because no routine cultural practice s involve sustained levels of contact with treated seed after it has been placed in the soil or other planting media

. Commercial treatment of seeds is not with in the scope of the Worker Protection Standard. Hymexazol is not registered for non

- commercial seed treatment and does not require Worker Protection Standard labeling.

A post

- application inhalation exposure assessment is not required as exposure is expecte d to be negligible.

1 2 .0 Human Inciden ts

Because there were no reported incident cases for hymexazol in both IDS and SENSOR

Pesticides, there does not appear to be a concern at this time that would warrant further investigation (Recore, 2015, D429 771 ). The Agency will continue to monitor the incident information and if a concern is triggered, additional analysis will be included in the risk

assessment.Hymexazol Human Health Risk Assessment DP No. D425247

Page 28 of 54 1 3 .0 References

EFED DW

– Wolf, J. (2015). D42 8894

. Hymexazol. Drinking Water Assessment for Regist ration Review.

Bever

, R . (2015 ). TXR# 005724 4

. Hymexazol HASPOC Recommendations on the Need for the Repeated Dose Inhalation Study.

Lloyd, M. (2015)

. D 42929 8

, Hymexazol : Occupational and Residential Exposure Assessment for Registration Review.

Recore, S. and Evans, E. (2015). D 429771

. Hymexazol : Tier I Update Revi ew of Human Incidents/Epidemiology for Draft Risk Assessment

Savoia, P. (2015). D4 29383. Hymexazol. Acute and Chronic Dietary Exposure and Risk Assessments of Drinking Water to Support Registr ation Review.

Morales, J. (1994). D200191. 048210

- R . Hymexazol in/on Sugar Beet Seeds. Determination of

Food/Non

- food Use. CBTS# 13,341. DP Barcode D200191. MRID# 428263

- 14.Hymexazol Human Health Risk Assessment DP No. D425247

Page 29 of 54 Appendix A

. Toxicology Assessment

A.1 Toxicology Data Requirements
The requirements (40 CFR 158.500) for non

- food use for hymexazol are in Table 1. Use of the new guideline numbers does not imply that the new (1998) guideline protocols were u sed.

Study 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 28

- Day Dermal

................................ .............................. 870.3250 90

- Day Dermal

................................ .............................. 870.3465 90

- Day Inhalation

................................ .......................... yes

yes

no

yes

yes 1 yes

yes

- yes

no

870.3700 Developmental Toxicity (rodent)

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

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

................................ ................................ . yes

yes

yes yes

yes

yes

870.4100 Chronic Toxicity (rodent)

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

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

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

870.4300 Chronic/Oncogenicity (rat) yes

yes

yes

yes

no yes

yes

yes

yes

yes

870.5100 Mutagenicity

— Bacterial reverse mutation assay

.................... 870.5300 Mutagenicity

— gene mutation test

- mammalian

...................... 870.53xx Mutagenicity

— chromosome aberration test

.......................... 870.53xx Mutagenicity

— other

................................ ..................... yes

yes

yes

yes yes

yes

yes

yes 870.6100 Acute Delayed Neurotoxicity (hen)

................................ 870.6100 90

- Day Neurotoxicity (hen)

................................ ........... 870.6200 Acute Neurotoxicity Screening Battery (rat)

.................. 870.6200 90

- Day Neurotoxicity Screening Battery (rat)

............... 870.6300 Developmental Neurotoxicity

................................ ....... no

no waived 2

yes

no NA

NA

- yes

no

870.7485 General Metabolism

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

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

................................ ............................. yes

no

yes yes

NA

yes

1 Required by HASPOC (TXR 0057244)

2 Waived by HASPOC (TXR 0056409)Hymexazol Human Health Risk Assessment DP No. D425247

Page 30 of 54 A.2 Toxicity Profiles

Table A.2.1 Acute Toxicity Profile

- Hymexazol

Guideline No. Study Type MRID(s) Results Toxicity Category

870.1100 Acute oral [rat] 42960008 LD 50 = M =1600 mg/kg

F = 1700 mg/kg Both = 1.7 g/kg III

870.1100 Acute oral [mouse] LD 50 = 1700 mg/kg

870.1200 Acute dermal [rat] 42960009 LD 50 > 2000 mg/kg III

870.1300 Acute inhalation [rat] 42960010 LC 50 > 0.65 mg/L 4 hour, aerosol, whole body III

870.2400 Acute eye irritation [rabbit] 42960011 Severe ocular

irritant/Severe corneal opacity w/ hyperaemic blood

vessels I

870.2500 Acute dermal irritation [rabbit] 42997301 Non

- irritant IV

870.2600 Skin sensitization [guinea pig] 42960012 Sensitizing (Magnusson

Kligman maximization test) n/aHymexazol Human Health Risk Assessment DP No. D425247

Page 31 of 54 Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

- Hymexazol

Guideline

No. Study

Type/Animal Species and Strain MRID No. (year)/

Classification /Doses Results

870.3100 90

- Day oral

toxicity (rat)

Crl:CD (SO) BR

rats 42960013, 42826304

(rangefinding) (1990)
Acceptable/Guideline

Tachigaren Technical, 92.7% a.i.; Lot No.

8033102

0, 1250, 5000 or 20000 ppm (equivalent to 0, 95, 371, 1694 mg/kg/day in males and 113, 450, 2084 mg/kg /day in females,

respect ively) via diet for

13 weeks LOAEL = 1694 mg/kg/day for males and 2084 mg/kg/day for females based on decreases in body weight gain, food utilization efficiency, and urinary volume, pH, and protein level, and increases in urinary reducing substances, and absolute and relative liver weight concurrently with slightly elevated

levels of SGOT and SGP T and one instance of centrilobular hepatocyte enlargement in

females.

NOAEL = 371 mg/kg/day for males and 450 mg/kg/day for females

870.3100 90

- Day oral

toxicity (mouse)

CD

- 1 mice 42960014 (1990)

Acceptable/Guideline

97.3% a.i.; Batch 3 5050

0, 300, 1200, 5000, or 20000 ppm (equivalent to 0, 55, 225, 952, 4006 mg/kg bw/day in males and 76, 326, 1295, 5433 mg/kg bw/day in females, respectively) via diet for

13 weeks LOAEL = not established (>HDT)

NOAEL = 4006 mg/kg/day for males and 5433 mg/kg /day for females

870.3150 90

- Day oral

toxicity (dog)

Pure

- bred beagles 42960016 (1990)

Acceptable/Guideline

92.2% a.i.; Batch number

90211018

0, 500, 7500 or 22500 ppm (equivalent to 0, 92, 286, 885 mg/kg bw/day in males and 98, 292, 894 mg/kg bw/day in females, respectively) via diet for

13 weeks. LOAEL = 286 mg/kg/day in males and 292 mg/kg/day in females based on increased absolute and relative thyroid weight accompanied by minimal increased epithelial height and minimal thyroid epithelial hyperpla sia

.

NOAEL = 92 mg/kg/day for males and 98 mg/kg/day for femalesHymexazol Human Health Risk Assessment DP No. D425247

Page 32 of 54 Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

- Hymexazol

Guideline

No. Study

Type/Animal Species and Strain MRID No. (year)/

Classification /Doses Results

870.3150 90

- day oral toxicity

(dog)

Pure

- bred beagles 42960017 (1990)

Acceptable/Guideline

92.2% a.i.; Batch number

90211018

0, 900, 1500 or 2500 ppm (equivalent to 0, 35, 61, 98 mg/kg bw/day in males and 37, 64, 109 mg/kg bw/day in females, respectively) via diet for

13 weeks. LOAEL = not established (> HDT)

NOAEL = 98 mg/kg/day for males and 109 mg/kg/day for females

870.3200 21

- Day dermal

toxicity (rabbit) No study available

870.3250 90

- day dermal

toxicity study

(rat)

Sprague Dawley (Crl:CD (SD) from Charles River (UK)

Ltd 49212101 (2013)

Acceptable/Guideline

99.29% a.i.; Batch

Number 00315211

0 (purified water), 100, 300 or 1000 mg/kg/day applied to shaved skin, covered with gauze and

left undisturbed for 6 hrs/day over 13 weeks. Systemic and Dermal LOAEL = not established (> HDT)

Systemic and Dermal NOAEL = 1000 mg/kg/day for males and femal es

870.3465 90

- Day inhalation

toxicity (rat) Required but no study available (TXR 0057244)Hymexazol Human Health Risk Assessment DP No. D425247

Page 33 of 54 Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

- Hymexazol

Guideline

No. Study

Type/Animal Species and Strain MRID No. (year)/

Classification /Doses Results

870.3700 Prenatal

developmental in (rat)

Female CD (Sprague

- Dawley)

rats 42826307 & 42826306

(range

- finding) (1989)

Acceptable/Guideline

Tachigaren Technical,

92.7% a.i.

0, 20, 100, or 500 mg/kg/day administered by gavage on days 6

- 15 of gestation Maternal LOAEL = not established (> HDT)

Maternal NOAEL = 500 mg/kg/day

Developmental LOAEL = 500 mg/kg/day

based on reductions in ossification of the cervical, thoracic, lumbar, & caudal vertebrae, as well as in the pelvic girdle & in the fore

- &

hind

- extremities (metacarpals & metatarsals), significantly increased incidence in the percent

of fetuses with bil ateral 14th ribs and reduced fetal body weight.

Developmental NOAEL = 100 mg/kg/day

870.3700 Prenatal

developmental in (rabbit)

Time

- mated New

Zealand White

rabbits 42960022 (1993)

Acceptable/Guideline

99.3% a.i.; Lot no.

10228211

0, 50, 150, or 450 mg/kg bw/day administered by gavage in 1% aqueous methylcellulose on gestation days (GDs) 7 through 19, inclusive. Maternal LOAEL = 450 mg/kg bw/day based on mortality, abnormal clinical signs (unsteadiness, slumped posture, increased respiration, and salivation), transient decreased food consumption, and body weight loss during

GDs 7

- 9.

Maternal NOAEL = 150 mg/kg bw/day

Developmental LOAEL = 450 mg/kg bw/day based on decreased fetal weight, heart/great vessel malformations, particu larly incomplete inferior vena cava, reduced sternebrae, and increased supernumerary ribs.

Developmental NOAEL = 150 mg/kg bw/dayHymexazol Human Health Risk Assessment DP No. D425247

Page 34 of 54 Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

- Hymexazol

Guideline

No. Study

Type/Animal Species and Strain MRID No. (year)/

Classification /Doses Results

870.3800 Reproduction and

fertility effects (rat)

Sprague Dawley:CD rats 42826309 (1991)

Acceptable/Guideline

92.2% a.i., lot #90211018

0, 100, 500, or 2500 ppm (equivalent to 0, 6.26, 30.9, and 159 mg/kg bw/day for F 0 males; 0, 7.50, 37.5, and 192 mg/kg bw/day for F 0 females; 0, 7.74, 37.5, and 193 mg/kg bw/day for F 1 males; and 0, 9.04, 43.9, and 230 mg/kg bw /day for F 1 females.) administered via

diet to F 0 and F 1 parental

animals for at least 14 weeks prior to mating, throughout mating (≤21 days), gestation, and lactation, and until necropsy after weaning of litters on postnatal day (PND) 25. Parental LOAE L = 159 mg/kg/day for males

an d 192 mg/kg/day for females based on reduced post

- implantation survival rate and

litter size

Parental NOAEL = 31 m g/kg/day for males

and 38 mg/kg/day for females

Offspring LOAEL = 159 mg/kg/day for males and 192 mg/kg/day for females based on reduced post

- implantation survival rate and

litter size

Offspring NOAEL = 3 1 mg/kg/day for

males and 3 8 mg/kg/day for females

Reproductive LOAEL = not established (> HDT)

Reproductive NOAEL = 159 mg/kg/day for males and 192 mg/kg/day for females

870.4100 Chronic toxicity

(rat) See guideline 870.4300

870.4100 Chronic Toxicity

(Dog)

– 1 Year

Pure

- bred beagles 42997302 (1992)

Acceptable/Guideline

93.7% a.i.; Batch number

90211018

0, 100, 500 or 2500 ppm (equivalent to 0, 3.55, 17, and 87 mg/kg/day in males and 0, 3.62, 18.18, and 91 mg/kg/day for females, respectively) via

diet for 52 weeks. LOAEL = not established (> HDT)

NOAEL = 87 mg/kg/day for males and 91

mg /kg/day for femalesHymexazol Human Health Risk Assessment DP No. D425247

Page 35 of 54 Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

- Hymexazol

Guideline

No. Study

Type/Animal Species and Strain MRID No. (year)/

Classification /Doses Results

870.4200 Carcinogenicity

(mouse)

- 2 years

CD

- 1 42960019 (1992)

Acceptable/Guideline

92.2% a.i., Batch

90211018

0, 300, 2500, or 20,000 ppm (equivalent to 0, 42, 355, and 2994 mg/kg bw / day for males and 0, 52, 440, and 3733 mg/kg bw/day for females) via

diet for 104 weeks. LOAEL = 2994 mg/kg bw/day for males and 3733 mg/kg bw/day for females based on increased absolute and relative liver weights

with associated liver granulomatous

infl ammation.

NOAEL = 355 mg/kg bw/day for males and 440 mg/kg bw/day for females

At the doses tested, there was not a treatment related increase in tumor incidence of any tumor type when compared to controls. Dosing was considered adequate based on decreased body weight and increased liver weights with associated histopathological lesions.

870.4300 Combined Chronic

Toxicity/Carcinoge nicity (rat)

– 2

Years

Sprague Dawley

rats 42960018 (1992)

Acceptable/Guideline

92.2

– 93.7% a.i., Lot

Number 90211018

0, 400, 2000, or 10,000 ppm (equivalent to 0, 20, 99, and 532 mg/kg bw/day for males and 0, 28, 149, and 769 mg/kg bw/day for females) via

diet for 104 weeks. LOAEL = 532 mg/kg / day for males and 769 mg/day based on decreased body weight in

ma les and females

NOAEL = 99 mg/kg/day in males and 149 mg/ kg/ day in females

No incidences of neoplastic effects were observed in either sex exposed to the HDT.

870.5100 Gene Mutation

(Ames Assay)

Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537, TA 1538, &

Escherichia coli

strain WP2 uvrA 42960023 (1993)

Acceptable

Tachigaren Technical,

99.3% a.i.

0, 312.5, 625, 1250, 2500, & 5000 μg/plate, with and without exogenous

metabolic activation Hymexazol was non

- toxic to the Salmonella strains, but was toxic to the E. coli strain at 2500 & 5000 μg/plate in the presence and

absence of S

- 9. There was no evidence of induced revertant colonies over background at any dose tested, either with or withou t S

- 9 mix.Hymexazol Human Health Risk Assessment DP No. D425247

Page 36 of 54 Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

- Hymexazol

Guideline

No. Study

Type/Animal Species and Strain MRID No. (year)/

Classification /Doses Results

870.5300 Mouse Lymphoma

Assay

L5178Y mouse lymphoma cells

Examined the thymidine kinase

locus 42960024 (1993)

Acceptable

Tachigaren Technical,

99.3% a.i

500, 750, 1000, 1500, 1750 or 2000 μg/mL with

& without Aroclor

induced rat liver S

- 9 mix. No evidence of cytotoxicity or a mutagenic

effect at the TK locus of L5178Y mouse lymphoma cells.

870.5395 Micronucleus

Assay

CD

- 1 mice 42960025 (1993)

Acceptable

Tachigaren Technical (99.3% a.i.)

0, 360, 720, or 1440 mg/kg in 1% (v/v) methylcellulose via oral

gavage

A vehicle control (20 mL/kg) and positive control (mitomycin C at 12 mg/kg) were run concurrently Of 39 mice treated at 1440 mg/kg, 1 male & 3 females died & were replaced with anim als from a concurrently treated satellite group. Other signs of compound toxicity in the high

dose group included piloerection, hunching, lethargy, increased respiratory rates, & twitching.

The incidence of micronucleated cells/1000

PCEs was not increased relative to control and the ratio of PCE to NCE (normochromatic erythrocytes) was not decreased at any dose level at any time point assayed.

870.6200 Subchronic

Neurotoxicity (rat)

Crl:CD®(SD)IGS

BR rats 48716601 (2006)

Acceptable/Guideline

99.6%, batch 3128

- 2110(D)

0, 1250, 4,000 or 12,500 ppm (equivalent to 0, 85 and 107, 287 and 354 or 901 and 1111 mg/kg/day for males and females, respectively) via diet for

13 weeks. LOAEL = 901 mg/kg/day for males and 1111 mg/kg/day for females mg/kg/day based on deaths in females and body weight effects and a decrease in brain weight and cerebral length in

males

.

NOAEL = 287 mg/kg/day for males and 354 mg/kg/day in females.Hymexazol Human Health Risk Assessment DP No. D425247

Page 37 of 54 Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

- Hymexazol

Guideline

No. Study

Type/Animal Species and Strain MRID No. (year)/

Classification /Doses Results

870.7485 Metabolism and

pharmacokinetics (rat)

male and female Sprague

- Dawley 42826310 & 43253802

14 CHymexazol was administered orally in

water to groups (5/sex/dose) of male and female Sprague

- Dawley

rats at nominal doses of 40 mg/kg (single and repeated low oral doses; IV dose) or 1000 mg/kg (single high oral dose). These groups were used for study of the disposition of hymexazol. Separate groups (4/sex) received hymexazol at 40 or 1000 mg/kg for serial blood sampling to examine pharmacokinetics and temporal distribution of hymexazol. Metabolites in urine, feces, liver, kidney, a nd

blood were characterized. Absorption of hymexazol from the diet was complete irrespective of sex (93

- 110% of

administered dose collected in the urine).

Female rats showed a greater extent of absorption, as indicated by a higher area under the curve, C

ma x , T
max , & slower elimination

half

- life vs. male rats. Male rats showed an initial distribution of hymexazol derived radioactivity to the liver at 0.5 hrs post

- dose, whereas females showed higher concentrations in blood, bone, brain, fat, & heart. Excretio n of hymexazol derived radioactivity was largely through urine, where 93

- 110% of the dose was recovered for all dose groups. Fecal elimination accounted for only 0.53

- 1.73% of the administered low dose and slightly more of the high dose (2.59

- 4.47%). A t 168 hours post

dose, less than 1% of the administered radioactivity was found in any tissue of male and female rats from any dose group. On a μg/g
tissue basis, fat and residual carcass were found to contain the highest levels of radioactivity, &

were hi gher in female rats in all dose groups than in males. Metabolites of hymexazol identified in this study included the glucuronic acid and sulfate conjugates of hymexazol, &

the oxidative metabolites 3

- hydroxybutamide &

3

- hydroxybutyric acid. Urine showed m ainly hymexazol conjugates, while oxidative metabolites were found in liver & kidney of

both sexes.

Dermal Absorption A dermal absorption study was not submitted for hymexazol; therefore, a 100 % dermal absorption factor was used in lieu of an empirically derived value. The physicochemical data and endpoints from the guideline studies could not be used to estimate

the DAF. T he low molecular weight precluded reducing the DAF to 10% despite a low K
ow . Likewise, a clear LOAEL was not reported for the dermal study and could not be compared to LOAEL established in the oral study.Hymexazol Human Health Risk Assessment DP No. D425247

Page 38 of 54 Table A.2.2 Subchronic, Chronic and Other Toxicity Profile

- Hymexazol

Guideline

No. Study

Type/Animal Species and Strain MRID No. (year)/

Classification /Doses Results

870.7800 Immunotoxicity

(rat)

female Sprague Dawley 48970401 (2012)

Acceptable/ Guideline

99.29% purity, Lot No.

00315211

0, 3125, 6250, or 12,500 ppm (equivalent to 0, 289, 551, and 1023 mg/kg bw/day) via diet for 28 days.

A concurrent positive control group received the basal diet, but were treated with 50 mg/kg bw of cyclophosphamide (CPS) by intraperitoneal (IP) injecti on on Day 27 of the study. Systemic LOAEL = 1023 mg/kg/day based on decreased body weight gains

Systemic NOAEL = 551 mg/kg/day

Immunotox LOAEL = not established (> HDT)

Immunotox NOAEL = 1023 mg/kg/day

A.3 Hazard Identification and Endpoint Selection

A.3.1 Acute Reference Dose (aRfD)

- Females age 13

- 49

An acute RfD specific to Females 13

- 49 was not calculated because no effect attributable to a single day oral exposure that would be specific to this population subgroup was observed in the toxicity database including the developmental and reproduction studies. The post implantation loss

observed in the 2

- generation reproduction study was not used as a dietary POD for women 13

- 49.

Post

- implantation loss was not observed at a similar dose in t he shorter duration rat development study indicating this effect required a longer exposure duration to manifest. Likewise, the developmental variations in the rat developmental study could not be unequivocally attributed to a single dose. Nevertheless, th e acute general population POD is protective of these developmental perturbations.

A.3.2 Acute Reference Dose (aRfD)

- General Population

Study Selected: Developmental

- rabbit

MRID No.: 42960022 Executive Summary : See Appendix A, Guideline [§ 870.37 00] Dose and Endpoint for Risk Assessment: NOAEL = 150 mg/kg/day based on m ortality, abnormal clinical signs ( unsteadiness, slumped posture, incre ased respiration and salivation)Hymexazol Human Health Risk Assessment DP No. D425247

Page 39 of 54 within an hour after the first dose

, and decreased food consumption and body we ight loss within 2 days of initial exposure in the dams at the LOAEL = 450 mg/kg/day. Uncertainty Factors: 100

– 10x for interspecies variation and 10x for intraspecies variation. Comments about Study/Endpoint: The post dose clinical signs, and decrease in food consumption and body weight loss on gestation days 7

- 9 in the high dose dams were the only

treatment

- related effects attributable to an acute exposure across the gamut of submitted studies.

The UF 100x was applied to the NOAEL to calculate the a RfD

.

A.3.3 Chronic Reference Dose (cRfD) Study Selected: 2 generation reproduction

- rat
MRID No.: 42826309 Executive Summary : See Appendix A, Guideline [§ 870.3800] Dose and Endpoint for Risk Assessment: NOAEL = 31 mg/kg/day based on reduced post implan tation survival and litter size seen at LOAEL = 159 mg/kg/day. Uncertainty Factors: 100

– 10x for interspecies variation and 10x for intraspecies variation

. Comments about Study/Endpoint: The offspring NOAEL in the reproduction study is the lowest

POD in the toxicity database and is protective of the developmental effects observed at higher doses (450

- 500 mg/kg/day) in the rat and rabbit development study and the thyroid effects observed in the subchronic dog study. The UF 100x was applied to the NOAEL to calculate the

cRfD.

A.3.4 Dermal Exposure (Short

- and Intermediate

- Term) Study Selected: 2 generation reproduction

- rat
MRID No.: 42826309 Executive Summary : See Appendix A, Guideline [§ 870.3800] Dose and Endpoint for Risk Assessment: NOAEL = 31 mg/kg/day based on reduced post implantation survival and litter size seen at LOAEL = 159 mg/kg/day. Uncertainty Factors: 100

– 10x for interspecies variation and 10x for intraspecies variation Comments about Study/Endpoint: The 2 generation re production study provided the lowest points of departure for a duration that approximated a short and intermediate term exposure. The submitted 90 day dermal study was not selected because it did not address possible developmental

effects for this route of exposure. No dermal absorption study was submitted; therefore, a DAF = 100% was assumed for the exposure assessment.

A.3.5 Inhalation Exposure (Short

- and Intermediate

- Term) Study Selected: 2 generation reproduction

- rat
MRID No.: 42826309

Executive Summary : See Appendix A, Guideline [§ 870.3800] Dose and Endpoint for Risk Assessment: NOAEL = 31 mg/kg/day based on reduced post implantation survival and litter size seen at LOAEL = 159 mg/kg/day. Uncertainty Factors: 100 0

– 10x for interspecies variat ion, 10x for intraspecies variation , and 10x for the lack of a route specific inhalation study Comments about Study/Endpoint: The 2 generation reproduction study provided lowest points of departure for a duration that approximated a short and intermediate term exposure. An inhalationHymexazol Human Health Risk Assessment DP No. D425247

Page 40 of 54 study was not selected because no route specific study was available. Absorption from inhalation was assumed to be equivalent to an oral exposure.

A.4 Executive Summaries

A.4.1 Subchronic Toxicity

870.3100 90

- Day Oral Toxicity

- Rat

The test substance, hymexazol (Tachigaren Technical, 92.7% a.i.), was administered to Sprague

Dawley rats at dietary levels of 1250, 5000, and 20000 ppm (for males: 95, 371, and 1694 mg/kg/day; for females: 113, 450, and 2084 mg/kg/day). Th e rats were observed for signs of toxicity; body weight and food and water consumption values were recorded. Hematology, clinical chemistry, urinalysis, and ophthalmological evaluations were performed prior to termination at 13 weeks. Organ weight, necrops y, and histopathology data were reported. At 20000 ppm, evidence of toxicity consisted of decreased mean body weight gain in both sexes (37% less than control for males, 25% for females), although food intake was not affected and the efficiency of food uti lization at the 20000 ppm dose level was decreased. Decreases in urinary volume, pH, and protein were observed at 20000 ppm, and treatment

- related increases in the amount of total reducing substance (TRS) in the urine were observed in 100% of the males

an d 50% of the females at that dietary level. Additionally at 20000 ppm, slight increases in SGPT and SGOT levels, absolute and relative liver weights, and histopathology findings were suggestive of treatment

- related effects in the liver, particularly in fem ales. At the 5000 ppm level, only a slight (8%) decrease in mean body weight was observed in males.

The LOAEL i s 1694 and 2084 mg/kg/day for males and females, respectively , based on decrease in body weight gain, decrease in urinary parameters, increase i n total reducing substances in the urine, and increase in absolute and relative liver weights accompanied by slight increases in SGPT and SGOT levels and histopathological findings . The NOAEL i s 371 and 450 mg/kg/day for males and females, respectively.

This 90

- day oral toxicity study in the rats is Acceptable/Guideline ; this study satisfies guideline recommendations for a §82

- 1 subchronic toxicity study in rats.

870.3100 90

- Day Oral Toxicity

- Mouse

In a 90

- day oral toxicity study (MRID 42960014) hyme xazol (97.3% a.i., Batch 3 5050) was administered to 10 Crl:CD

- 1 (ICR) BR mice /sex/dose in the diet at concentration of 0, 300, 1200, 5000, or 20000 ppm (equivalent to dose levels of 0, 55, 225, 952, and 4006 mg/kg bw/day

in males and 0, 76, 326, 1295, and 5433 mg/kg bw/day for females ).

There were no mortalities, clinical signs of toxicity, or treatment related effects on food consumption, body weight, body weight gains, hematology, clinical chemistry, urinalysis, gross pathology or microscopic patholog y

.Hymexazol Human Health Risk Assessment DP No. D425247

Page 4 1 of 54 The LOAEL was not established. The NOAEL is 4006 and 5433 mg/kg/day in males and females, respectively.

This 90

- day oral toxicity study in the mice is Acceptable/Guideline and satisfies the guideline requirement for a 90

- day ora l toxicity study (OCSPP 870.3100; OECD 40 8 ) in mice

.

870.3150 90

- Day Oral Toxicity

- Dog

In a 90

- day oral toxicity study (MRID 42960016), hymexazol (92.2% a.i.; batch number 90211018) was administered to pure

- bred beagles, 4/sex/dose in the diet at concentration level s of 0, 500, 7500 or 22500 ppm (equivalent to doses of 0, 92, 286, 885 mg/kg bw/day in males and 98, 292, 894 mg/kg bw/day in females, respectively).

No adverse, treatment

- related effects were noted on mortality, clinical signs, food consumption, ophthal mology, or urinalysis.

At the mid dose (92 mg/kg/day in males and 98 mg/kg/day in females), findings in females included increased absolute thyroid weight (↑61%) and increased incidences of the following histological findings: minimal f ollicular epithelia l increased height (3/4 v. 0/4 in controls) and minimal follicular epithelial hyperplasia (2/4 v. 0/4 in controls). These symptoms became more prevalent and severe in at the high dose (885 mg/kg/day in males and 894 mg/kg/day in females). In addition, decr eased alkaline phosphates was noted in the mid

- dose females and was considered of equivocal biological significance. Effects on hemoglobin, erythrocyte count, hematocrit, serum total protein and albumin , were considered not adverse at the mid

- dose and

low er, due to the low magnitude of effect.

Other effects noted at the high dose included: (i) decreased body weight in males; (ii) increased platelets in males; (iii) decreased hemoglobin, erythrocyte count, and hematocrit in both sexes, (iv) decreased seru m albumin and total protein in males; (v) increased liver weight with increased incidence of parenchymal inflammatory foci in males; (vi) increased kidney weight in males; (vii) increased thyroid weight in both sexes; (viii) increased pituitary weight in f emales; (ix) enlarged thyroids in females; (x) increased incidence of thyroid epithelial follicular height and hyperplasia in both sexes. In addition, decreased alkaline phosphates was noted in the males and was considered of equivocal biological significa nce.

The LOAEL i s 286 mg/kg/day in mal es and 292 mg/kg/day in females, based on increased absolute and relative thyroid weight accompanied by minimal increased epithelial height

and minimal thyroid epithelial hyperplasia in females. The NOAEL is 92 mg/kg/day in

males and 98 mg/kg/day in females

.

This study is classified as Acceptable/Guideline and satisfies g uideline re commendation for a

90

- day oral toxicity study (OCSPP 870.3150; OECD 409) in the non

- rodent (beagle dog).

870.3150 90

- Day Oral Toxicity

– DogHymexazol Human Health Risk Assessment DP No. D425247

Page 42 of 54 In a 90

- day oral toxicity study (MRID 42960017), hymexazol ( 92.2 % a.i. ; B atch # 90211018 )

w as administered to pure

- bred beagles, 4 /sex/dose in the diet at dose levels of 0, 900, 1500 or

2500 ppm (equivalent to 0, 35, 61, 98 mg/kg bw/day in males and 37, 64, 109 mg/kg bw/day in females, respectively ).

There were no mortalities during the study period and no significant treatment related effects in body weight, body weight gain, hematology, urinalysis, or clinical chemistry. Mid (61 and 64 mg/kg/day in males and females, respectively) and high (98 and 109 mg/kg/day in males and females, respectively) dose males exhibited significantly increased absolute and relative liver weight and absolute lung weight. A non

- significant increas e in absolute liver and thyroid weight were observed in high dose females along with a significant increase in relative liver weight. No associated gross or histopathological anomalies were observed in these organs to indicate an adverse reaction to hymexa zol treatment.

No LOAEL was established for this study. The NOAEL i s 98 and 109 mg/kg/day in males and females, respectively.

This study is Acceptable/Non

- g uideline

. Although the study was considered scientifically sound, the study does not satisfy the guideline re commendation for a 90

- day oral toxicity study (OCSPP 870.3150; OECD 409) in the non

- rodent (dog), because the animals could have tolerated a higher dose. An acceptable, guideline subchronic toxicity study in dogs was submitted (see MRID 429600 16).

870.3200 90

- Day Dermal Toxicity

– Rat

In a 90

- day dermal toxicity study (MRID 4921201), hymexazol (99.29% a.i.; Batch Number 00315211) was applied to the shaved skin of Sprague Dawley (Crl:CD (SD) from Charles River (UK) Ltd.) rats for a period of 13 weeks. Four groups, each comprising ten males and ten females received Hymexazol at doses of 0 (Control; with purified water and were subject to the

same semi

- occlusion procedures) 100, 300 or 1000 mg/kg/day under semi

- occluded conditions for approxim ately six hours each day.

No treatment

- related effects were observed on clinical condition; body weight; food consumption; ophthalmic, hematology, or blood chemistry parameters; organ weights; or macropathology and histopathology findings. The dermal app lication of hymexazol for 13 weeks at doses up to 1000 mg/kg/day saw no indication of irritation to the skin after repeated occluded application.

Although a decrease (p<0.01) in body weight gain of 30% was noted in th e 1000 mg/kg/day males, an increase (p<0.01) in body weight gain of 27% was noted in the 1000 mg/kg/day females. At 1000 mg/kg/day, terminal body weights were decreased (p<0.05) by 14% in males and increased (p<0.01) by 15% in females. However, the mean of the 1000 mg/kg/day males

was with in 1 standard deviation of the mean of the controls. In a 13

- week oral (dietary) study, decreases in body weight gains were noted in the 1694 mg/kg/day males ( ↓ 37%) and 2084 mg/kg/day females (↓ 25%). Thus, the oral study showed a comparable effect on body weightHymexazol Human Health Risk Assessment DP No. D425247

Page 43 of 54 gain in males but at a substantially higher dose. The effect on body weight and body weight gain is considered unclear in this dermal study.

The L OAEL wa s not established. The NOAEL i s 1000 mg/kg/day (limit dose) in both sexes

.

This study is classified as Acceptable/Guideline and satisfies the guideline requirement for a

90

- day dermal toxicity study (OPPTS 870.3250; OECD 411) in the rat since the l imit dose was

tested.

870.3465 90

- Day Inhalation

– Rat

Required by HASPOC (TXR 0057244 ).

A.4.2 Prenatal Developmental Toxicity

870.3700a Prenatal Developmental Toxicity Study

- Rat

Maternal Toxicity The test substance, hymexazol (Tachigaren Technical, 92.7% a.i.), was administered by gavage to pregnant female CD (Sprague

- Dawley) rats on days 6

- 15 of gestation at dose levels of 20, 100, and 500 mg/kg/day. The rats were observed for signs of toxicity; b ody weight and food and water consumption values were recorded. On day 20 of gestation, the rats were sacrificed and necropsied. The uteri were examined, implantation sites were counted, and the numbers of corpora lutea were determined. The fetuses were re moved, weighed, sexed, and examined for external anomalies. They were then processed for visceral and skeletal evaluation.

There was no evidence of treatment

- related maternal toxicity in any treatment group.

The maternal LOAEL was not determined. T he mate rnal NOAEL i s greater than or equal to 500 mg/kg/day (highest dose tested).

Developmental Toxicity At 500 mg/kg/day, a dose which was not maternally toxic, mean fetal body weight was reduced 9.3% below control. Indications of developmental delays were al so observed in the skeletal evaluation data. These included reductions in ossification of the cervical, thoracic, lumbar, and caudal vertebrae, as well as in the pelvic girdle and in the fore

- and hind

- extremities (metacarpals and metatarsals). In additio n, a significantly increased incidence in the percent of fetuses with bilateral 14th ribs was reported.

The developmental LOAEL i s 500 mg/kg/day based on lower fetal body weight, skeletal defects, and increased incidence of fetuses with bilateral 14 th rib . The developmental

NOAEL i s 100 mg/kg/day.

Minimum ; this study satisfies minimum guideline recommendations for a §83

- 3(a) developmental toxicity (teratology) study in rats.

870.3700b Prenatal Developmental Toxicity Study

- RabbitHymexazol Human Health Risk Assessment DP No. D425247

Page 44 of 54 In a developmental toxicity study ( MRID 42960022 )

, Hymexazol technical (99.3% a.i.; Lot no. 10228211) was administered by gavage in 1% aqueous methylcellulose to groups of 18 mated

female New Zealand White rabbits at dose levels of 0, 50, 150, or 450 mg/kg bw /day (constant dosing volume of 10 mL/kg bw) on gestation days (GDs) 7 through 19, inclusive. On GD 29, dams were sacrificed and necropsied.

Maternal toxicity was evident at the highest dose level (450 mg/kg/day). Two high

- dose animals

were sacrificed ahead of schedule for humane reasons: one on GD 14 due to poor body condition, abnormal clinical signs (unsteadiness, hunched posture, “dark eyes,” and cold ears), and weight loss (783 g) ; t he other on GD 23 after being found unable to stand following

abo rtion

. Treatment

- related a bnormal post

- dosing observations were seen at 450 mg/kg/day. Among the 15 high

- dose survivors, these included unsteadiness

, slumped posture

, increased respiration , and salivation (exhibited on one or more occasions by 11, 6, 7, and 7 animals, respectively). Additional treatment

- related clinical signs included decreased appetite/r educed fecal output during GDs 7

- 9 in high

- dose females and o range

- stained tray paper in mid

- (150 mg/kg/day) and high

- dose females. H igh

- dose females had a treatment

- related decrease in mean food consumption during GDs 7

- 8 (

- 46%; p<0.01) and a correlated mean body weight loss during GDs 7

- 9 (

- 148 g vs. +22 g for controls; p<0.05)

. There were not treatment related effects on gross pathology, number of l itters or sex ratio. No abortions, premature deliveries, or dead fetuses occurred during the study period and no maternal intrauterine effects were evident.

The maternal toxicity LOAEL is 450 mg/kg bw /day, based on mortality, abnormal clinical signs (unsteadiness, slumped posture, increased respiration, and salivation), transient decreased food consumption, and body weight loss during GDs 7

- 9. The maternal toxicity

NOAEL is 150 mg/kg bw/day.

Various adverse findings were noted in the fetuses at 450 mg/kg/day. Mean fetal body weight was decreased by 7% and was considered an adverse, treatment related effect, although this effect was not reported to be statistically significant. Additionally at 450 mg/k g/day there was an increased percentage of fetuses per litter with reduced sternebrae. The total numbers of fetuses (and litters) evaluated in the control, low

- , mid

- , and high

- dose groups were 140 (16), 115 (14), 110 (13), and 108 (14), respectively. In these same respective groups, malformations were observed in a total of 2 (2), 3 (2), 4 (4), and 6 (4) fetuses (and litters) . Heart /great vessel

malformations were noted in 1 (1) mid

- dose and 4 (4) high

- dose fetuses (and litters ) and were not seen in any control or low

- dose litters (p<0.05 for high

- dose litter incidence). Individual heart/great vessel malformations were noted as follows: incomplete inferior vena cava with persist e nt left posterior cardinal vein in 1/13 mid

- dose and 3/14 high

- dose litters; interventricular septal defect in 2/14 high

- dose litters; and dilated ascending aorta/aortic arch

, double outlet r ight

ventricle , n arrow pulmonary trunk/ductus arteriosus, and dorsally displaced pulmonary trunk each noted in 1/14 high

- dose litters. Altho ugh the incidences were low and statistical significance was only attained for the grouped heart/great vessel findings, these findings are

considered treatment

- related and adverse. Fetal sex ratio was not affected by treatment, and there

were no clear effe cts on deaths/resorptions.Hymexazol Human Health Risk Assessment DP No. D425247

Page 45 of 54 T he developmental toxicity LOAEL is 4 50 mg/kg bw/day, based on heart/great vessel malformations, particularly incomplete inferior vena cava , decreased fetal weight, reduced sternebrae, and increased supernumerary ribs . The de velopmental toxicity NOAEL is 1 50 mg/kg bw/day.

This study is classified Acceptable/Guideline and satisfies the guideline recommendations for a developmental toxicity study (OCSPP 870.3700; OECD 414) in the rabbit.

A.4.3 Reproductive Toxicity

870.3800 Reproduction and Fertility Effects

– Rat

In a two

- generation reproduction study (MRID 42826309 ), h ymexazol (92.2% a.i., lot #90211018) was administered to groups of 24 Sprague Dawley: CD rats/ sex /dose in the diet at dietary concentrations of 0, 10 0, 500, or 2500 ppm

. Pre

- mating doses were, respectively: 0, 6.3

, 3 1 , and 159 mg/kg bw/day for F 0 males; 0, 7.5, 3 8 , and 192 mg/kg bw/day for F 0 females; 0, 7. 7

, 38 , and 193 mg/kg bw/day for F 1 males; and 0, 9.0, 4 4 , and 230 mg/kg bw/day for F 1 females. Hereafter, the male/female F 0 premating doses 0, 6.3/7.5, 31/38, and 159/192 mg/kg/day will be referred to as the control, low, mid, and high dose, respectively. F 0 and F 1 parental animals were

administered the treated or control diets for at lea st 14 weeks prior to mating, through out mating (≤21 days) , gestation

, and lactation , and until necropsy after weaning of litters on postnatal day (PND) 25. One litter was produced by each generation.

In F 0 and F 1 animals, there were no treatment

- relate d effects on clinical signs, pre

- mating body

w eight, body weight gain

, food consumption , or postmortem observations, with one exception

. O ne F 0 female from the high dose group was found dead on GD 22 with a high degree of post

implantation loss revealed at necropsy . This mortality may have been treatment

- related in light

of the reduced post

- implantation survival index in this group (see below) though it was the only mortality to occur during the study period

. At the high dose , differences were observed in gestation length and in body weight gain during gestation and lactation. Gestation length was approximately 0.3 to 0.5 day s longer in the F 0 and F 1 females , respectively; this was statistically significant in the F 1 females

. Because the difference was less than one full day and there was a lack of effect on corresponding parameters (e.g., dystocia, decreased live birth indices) this prolongation was not considered adverse. In the F 0 females, there was a decrease in body wei ght gain during gestation (by 13% overall; 24% during GD 13

- 20) , correlating with reduced post

implantation survival and litter size. Although not statistically significant, a slight body weight gain reduction in the F 1 dams also was noted during GD 13

- 20 (↓10%). From LD 1 to LD 25, F 0 and F 1 dams in the 2500 ppm group lost approximately 4% body weight (vs. a 3% gain in F 0 controls, and negligible change in the F 1 controls). These changes were not considered treatment related because a comparable body wei ght loss was observed in the low dose F 1 dams, and the

mid dose F 0 (↑2%) and F 1 (↑4%) dams experienced an increase in body weight. Furthermore, the body weight changes during gestation and lactation were not considered adverse because absolute body weights were comparable across all groups.Hymexazol Human Health Risk Assessment DP No. D425247

Page 46 of 54 P ost

- implantation survival rate and litter size was significantly reduced in the high dose F 1 (↓17%) and F 2 (↓20%) offspring compared to controls. Lower survival rates led to reduced l itter

size at birth/on postnatal day ( PND ) 1 in both the F 1 (↓ 26

- 27% ) and F 2 (↓ 17% ) generations. T his reduction continued until PND 4 (pre

- cull), with 16% fewer F 1 pups and 19% fewer F 2 pups per litter compared to controls

. It was impossible to determine if this was a maternal or in utero effect without more data; therefore, it was attributed to both.

The paternal toxicity LOAEL for h ymexazol in rat pups i s 159 mg/kg bw/day for males and 192 mg/kg bw/day for females, based on reduced litter size due to lower post

- implantation

survival ra te. The paternal NOAEL i s 31 mg/kg bw/day for males and 38 mg/kg bw/day

for females

.

As mentioned previously, smaller litter size caused by increased post

- implantation loss was considered both an offspring and maternal effect. There were no treatment

- re lated effects on the general physical condition, body weight, or developmental landmarks (pinna unfolding, hair growth, tooth eruption, and eye opening) of the F 1 or F 2 pups. No offspring or developmental

adverse effects were observed in mid or low dose of fspring.

The offspring toxicity LOAEL for h ymexazol in rat pups i s 159 mg/kg bw/day for males and 192 mg/kg bw/day for females , based on reduced litter size due to lower post

implantation survival rate. The offspring NOAEL i s 31 mg/kg bw /day for males and 38 mg/kg bw/day for females

.

There was no definitive evidence of reproductive toxicity. Although t here were no treatment related effects on mating performance, fertility, or reproductive organs , it should be noted that

sperm enumerati on and evaluation for motility and morphology was not done; ovarian follicle counts were not done (F 1 parental females); and t he age of vaginal opening and preputial separation were not determined for the F 1 weanlings selected for mating

.

T he reproducti ve toxicity LOAEL for h ymexazol in rats was not determined . The reproductive toxicity NOAEL i s greater than or equal to 159 mg/kg bw/day for males and 192 mg/kg bw/day for females

.

This study is A cceptable/ Guideline and satisf ies the guideline requirement for a 2

- generation reproductive toxicity study [OCSPP 870.3800; OECD 416] in rats

.

A.4.4 Chronic Toxicity

870.4100a (870.4300) Chronic Toxicity

– Rat

In a carcinogenicity study (MRID 42960018), hymexazol (92.2

– 93.7% a.i., Lot Number

90211018 ) was administered to groups of 50 male and female Sprague Dawley rats/ sex/dose in

the diet at dose levels of 0, 400, 2000, or 10,000 ppm (equivalent to 0, 20, 99, and 532 mg/kg bw/day for males and 0, 28, 149, and 769 mg/kg bw/day for females) for 104 weeks

. Hereafter,Hymexazol Human Health Risk Assessment DP No. D425247

Page 47 of 54 the male/female dose groups 0, 20/28, 99/149, and 532/769 will be referred to as control, low, mid, and high dose, respectively. Satellite groups of 20 rats/sex/dose received the same dietary

concentrations for 52 weeks before sacrif ice.

Treatment did not affect survival; however it did cause a statistically and biologically significant decrease in body weight of high dose males from week 13 to the end of the study (↓10

– 15%) and high dose females from week 26 through week 75 (↓ 8

– 21%) . No biologi cally or toxicologically relevant effects were noted for food consumption, hematology, clinical chemistry, urinalysis, ophthalmology, or gross pathology. An increased incidence of centrilobular and periportal hepatocyte enlargement was o bserved in high dose male and female rats, respectively. However, neither high dose males nor females exhibited concomitant signs of liver toxicity in other liver parameters. Ostensibly, enzyme levels were elevated in high dose males, yet closer examinatio n revealed a strong influence from two individuals resulting in artificially inflated values and high variability. Furthermore, liver weight was not different from controls in the high dose males. Conversely, liver weight of high dose females was statistic ally different from controls, yet the increase was slight and not biologically significant, and serum enzymes levels were comparable to controls. Based on the lack of corroborating evidence in other liver parameters, the liver enlargement anomalies were no t considered adverse.

The LOAEL is 532 mg/kg bw/day for males and 769 mg/kg bw/day for females based on decreased body weight. The NOAEL is 99 mg/kg/day in males and 149 mg/kg/day in

females.

Hymexazol given to male and female rats at a dose of 532 and 769 mg/kg bw/day, respectively, did not induce neoplastic effects.

This study is classified as Acceptable / Guideline and satisfies the guideline re commendations for a carcinogenicity study [ O CSPP 870.4200; OECD 451] in rats.

870.4100b Chronic Toxicity

- Dog

In a chronic toxicity study (MRID 42997302), hymexazol ( 93.7% a.i.; B atch number 90211018 )

was administered to 4 pure

- bred beagles /sex/dose in the diet at dose levels of 0, 100, 500 or 2500 ppm (equivalent to 0, 3.55, 17, and 87 mg/kg/day in males and 0, 3.62, 18.18, and 91 mg/kg/day for females, respectively ) for 52 weeks.

Hymexazol treatment did not result in any unexpected mortalities and did not adversely affect body we ight, body weight gain, food consumption, hematology, clinical chemistry, or urinalysis parameters. Significant increase in high dose female liver weight was not accompanied by adverse pathological anomalies in the liver indicating an adaptive response to exposure. Weight of all other organs were comparable to control. All gross and histopathological findings were

minor and not attributed to treatment.

The LOAEL was not determined. The NOAEL i s equal to or greater than 87 mg/kg/day for males and 91 mg/kg/d ay for females.Hymexazol Human Health Risk Assessment DP No. D425247

Page 48 of 54 This study is classified as Acceptable/Guideline and satisfies the guideline requirement for a chronic oral study [O CSPP 870.4100, OECD 452] in the dog. Although the animals could have tolerated higher doses than those tested, there was a clear NOAEL.

A.4.5 Carcinogenicity

870.4200a Carcinogenicity Study

- rat

See executive summary for 870.4100a.

870.4200b Carcinoge nicity

- Mouse

In a carcinogenicity study (MRID 42960019) hymexazol (92.2% a.i. Batch #90211018) was administered to 60 Crl:CD

- 1 (ICR) BR mice/ sex/dose in the diet at dose levels of 0, 300, 2500,

and 20000 ppm (equivalent to 0, 42, 355, and 2994 mg/kg bw /day in males and 0 , 52, 440, and

3733 mg/kg bw/day in females ) for 91 weeks. Ten mice of each sex from each dosage level were sacrificed for interim study following 52 weeks of treatment.

Absolute (↑15% at interim, ↑10% at end of study) and relative (↑18 % at interim, ↑19% at end of study) liver weight in high dose females and relative (↑18%) liver weight in high dose males was significantly increased at the high dose and coincided with increased incidence of granulomatous inflammation (males: 29/50, minim al to moderate severity in high dose v. 13/50, minimal to marked severity in controls; and females: 28/50, minimal to moderate severity in high dose v. 17/50, minimal to moderate severity in controls). In combination these two liver effects were

considered adverse. Similar liver were not observed in the low and mid dose animals. Significant weight increases in other organs were not accompanied by clear adverse gross or histopathological damage and were thus not considered adverse responses to treatment. Bod y weight gain was depressed for the entire study period in high dose males and females which correlated with significantly lower absolute body weight in high dose males and females from week 39 through week 91. However, the significance of the body weight findings were questionable because high mortality in treated and control groups from week 39 through week 91 may have confounded the body weight statistical analysis. As a result, the body weight effects were not considered in the endpoint selection. There were no treatment related effects evident in the clinical examinations, food consumption, hematology or gross pathology analyses for any of the dose groups.

The LOAEL is 2994 mg/kg/day in males and 3733 mg/kg/day in females , based on increased liver weig ht concurrent with liver granulomatous inflammation. The NOAEL is 355 mg/kg/day in males and 440 mg/kg/day in females

.

At the doses tested, there was not a treatment related increase in tumor incidence when compared to controls. Dosing was considered adeq uate based increased liver weight accompanied by increased incidence and severity of liver granulomatous inflammation in high dose males and

females.Hymexazol Human Health Risk Assessment DP No. D425247

Page 49 of 54 This carcinogenicity study in mice is Acceptable/Guideline and satisfies the guideline requirement for a carcinogenicity study [OPPTS 870.4200; OECD 451] in mice.

A.4.6 Mutagenicity

Gene Mutation

Guideline 870.5100, Gene Mutation

MRID 4290023 Acceptable Hymexazol was non

- toxic to the Salmonella strains, but was toxic to the

E. coli strain at 2500 & 5000 μg/plate in the presence and absence of S

- 9. There was no evidence of induced revertant colonies over background at any dose tested, either with or without S

- 9 mix

Cytogenetics

Guideline 870.5300, Mouse Lymphoma Assay

MRID 42960024 Acceptable No evidence of cytotoxicity or a mutagenic effect at the TK locus of L5178Y mouse lymphoma cells.

Micronucleus Assay

Guideline 870.5395, Micronucleus Assay

MRID 42960025 Acceptable The incidence of micronucleated cells/1000 PCEs was not increased

relative to control and the ratio of PCE to NCE (normochromatic erythrocytes) was not decreased at any dose level at any time point assayed.

A.4.7 Neurotoxicity

870.6100 Delayed Neurotoxicity Study

- Hen

Not required

870.6200 Acute Neurotoxicity Screening Battery

Waived by HASPOC (TXR 0056409)

870.6200 Subchronic Neurotoxicity Screening Battery

In a subchronic neurotoxicity study (2006, MRID 48716601) Hymexazol (99.6%, batch 3128

- 2110(D)) was administered to 10 Crl:CD®(SD)IGS BR rats /sex/group at dose levels of 0, 1250, 4,000 or 12,500 ppm for 13 weeks. These doses were equivalent to 0, 85 and 107, 287 and 354 or 901 and 1111 mg/kg/day for males and females for the control, low, mid or high dose test groups. Assessment for neurotoxicity as det ermined by FOB and motor activity were made at pretest, weeks 2, 4, 8 and 13 with 10 rats/sex/group. At termination, 5 rats/sex in the control and high dose groups were perfused in situ and subjected to neurohistopathological examination of

the brain and peripheral nerves.Hymexazol Human Health Risk Assessment DP No. D425247

Page 50 of 54 There were two deaths in the high dose group females that occurred in the later weeks of the study and although the exact cause could not be determined, they are considered to be related to treatment. At necropsy they were noted to h ave dark livers. Decreased body weight and gain were noted only the high dose (both sexes) but food consumption was not affected suggesting an effect on food efficiency. There was a statistically significant decrease in absolute brain weight (6.3%, p < 0 .05) and a decrease in cerebral length (3.7%, p < 0.05) noted in the high dose group males. Although there was no associated histopathological change, the decrease in brain weight and cerebral length may be effects of hymexazol since brain weight is conse rved when there is body weight loss. There were no differences in FOB parameters, motor activity or histopathology to indicate treatment related effects.

The LOAEL is 901 in males and 1111 in females mg/kg/day based on deaths in females and body weight effects and a decrease in brain weight and cerebral length in males . The

NOAEL is 287 in males and 354 in females mg/kg/day.

The study is classified as Acceptable/Guideline and satisfies the guideline requirement for a subchronic neurotoxicity study in rats (870.6200b).

870.6300 Developmental Neurotoxicity Study

Not required

A.4.8 Metabolism

870.7485 Metabolism

- Rat

In MRID 42826310 and 43253802 14C

- Hymexazol was administered orally in water to groups (5 sex/dose) of male and female Sprague

- Dawl ey rats at nominal doses of 40 mg/kg (single and repeated low oral doses; intravenous dose) and 1000 mg/kg (single high oral dose). These groups were used for study of the disposition of hymexzaol. Separate groups (4/sex) received hymexazol

at 40 and 1000 mg/kg for serial blood sampling to examine pharmacokinetics and temporal distribution of hymexazol. Metabolites in urine, feces, liver, kidney, and blood were

characterized.

Bioavailability was essentially complete for all dose groups of male and female r ats, but female rats showed a greater extent of absorption, as indicated by a higher area under the curve, cmax,

and half

- life vs. male rats. At 168 hours post

- dose, less than 1% of the administered radioactivity was found in any tissue of male and female rats from any dose group. On a ug/g tissue basis, fat and residual carcass were found to contain the highest levels of radioactivity, and were higher in female rats in all dose groups than in males. Male rats showed an initial distribution of hymexzaol der ived radioactivity in the liver at 0.5 hours post

- dose, werheas females showed higher concentrations in blood, bone, brain, fat, and heart. Differences may exist in the biotransformation and/or distribution of hymexazol in male and female rats. Excretion o f hymexazol derived radioactivity was largely through urine, where 95

- 110% of the dose wasHymexazol Human Health Risk Assessment DP No. D425247

Page 51 of 54 recovered for all dose groups by this route. There were no significant dose

- or sex

- related differences in excretion. Metabolites of hymexazol identified in this stu dy included the glucuronic acid and sulfate conjugates of hymexazol, and the oxidative metabolites 3

- hydroxybutamide and 3

- hydroxybutyric acid. Urine showed mainly hymexazol conjugates, while oxidative metabolites were found in liver and kidney of both sex es.

These studies are classified as Minimum and together satisfy the guideline requirement for a metabolism study in rats (870.7485).

870.7600 Dermal Absorption

- Rat

No study submitted. A 100% dermal absorption factor was assumed for concentrated and dilute

solutions

.

A.4.9 Immunotoxicity

870.7800 Immunotoxicity

In an immunotoxicity study (MRID 48970401), hymexa z ol (99.29% purity, Lot No. 00315211) was administered to groups of 10 female Sprague Dawley rats/dose in the diet at concentrations of 0, 3125, 6250, and 12500 ppm (equivalent to 0, 289, 551, and 1023 mg/kg bw/day) for 28 days. A concurrent positive contro l group received the basal diet, but were treated with 50 mg/kg bw of cyclophosphamide (CPS) by intraperitoneal (IP) injection on Day 27 of the study. All rats were given a single intravenous (IV) bolus dose of sheep red blood cell (SRBC, 2x10 8 cells /mL, 1 mL/animal) on Day 25. All rats were sacrificed on Day 29, and the spleen and thymus removed and weighed. Splenic cell suspensions were prepared for the plaque

- forming cell (PFC) assay to determine the effect of dietary administration of hymexazol on the antigen specific activity of the immune system.

There were no treatment

- related deaths and no clinical signs of toxicity were observed. Female rats treated with 12,500 ppm hymexazol had a ~24% decrease in body weight gain during Weeks

1

- 4 of the study an d a slight decrease in body weight (↓5%) compared to the control on Day 29.

No treatment

- related effects were found for rats treated with 3125 or 6250 ppm hymexazol. No effects on spleen or thymus absolute or relative to body weight were found for female rats treated with hymexazol.

Under conditions of this study, the systemic LOAEL i s 1023 mg/kg bw/day based on decreased body weight gains. The systemic NOAEL i s 551 mg/kg bw/day.

There were no treatment

- related effects on spleen cell number, and the P FC response to the T

cell dependent antigen SRBC (i.e., specific activity, and total spleen activity). A high inter

individual variability was noted in all the treatment groups as well as in the control group.

Evaluation of individual animal data did not show any trend or distribution that would demonstrate significant suppression of SRBC antibody response. The positive control animalsHymexazol Human Health Risk Assessment DP No. D425247

Page 52 of 54 confirmed the ability of the test system to detect immunosuppressive effects and confirmed the validity of the study desig n.

The Natural Killer (NK) cells activity was not evaluated in this study. The toxicology database for hymexazol does not reveal any evidence of immunotoxicity. The overall weight of evidence suggests that the chemical does not directly target the imm une system. Under HED guidance a NK cell activity assay is not required at this time.

A LOAEL for immun otoxicity in female SD rats was not identified. The immuno toxicity NOAEL for hymexazol in female SD rats i s 1023 mg/kg bw/day.

This immunotoxicity study is classified Acceptable/Guideline and satisfies the guideline requirement for an immunotoxicity study (OCSPP 870.7800) in female rats.Hymexazol Human Health Risk Assessment DP No. D425247

Page 53 of 54 Appendix B. Physical/Chemical Properties

Physi o chemical Properties of Hymexazol. 1

Parameter Value

Molecular mass (g/mole) 99.09

Vapor pressure, at 25 ̊C 1.37 E

- 3 mmHg (torr)

Henry’s Law Constant 6.5 E

- 9 atm

- m 3 /mole*

2.74E

- 9 atm

- m 3 /mole (calculated @ pH7)

Solubility in water (g/L) , 20 ̊C @ pH7 5.82 g/mL b (pH 3) 58.2 g/L

6.51 g/mL b (pH 7) 65.1 g/L (bold value used to

calculate Henry’s constant

6.78 g/mL b (pH 9) 67.8 g/L

There appears to be a conversion error in one of the sources of solubility data as (e.g., 6.51 g/mL does not equal 65.1 g/L).

pK
a 5.92

1. D428894, J. Wolf, 09/02/2015.

* Estimated via EPISuite

a MRIDs 428263

- 01/

- 02/

- 03. Reviewed 03/29/1995.

b Solubility in the Problem Formulation (02/16/2010) solubility was reported in g/mL however in other sources report solubility in g/L.Hymexazol Human Health Risk Assessment DP No. D425247

Page 54 of 54 Appendix C . 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 data include studies from the Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1), a nd ExpoSAC Policy 14 and 15.1 (SOPs for Seed Treatment) These data are subject to ethics review pursuant to 40 CFR 26, have received that review, and are compliant with applicable ethics requirements. For certain studies that review may have included review by the Human Studies Review Board. Descriptions of data sources as well as guidance on their use can be found at http://www.epa.gov/pesticides/science/handler

- exposure

- data.html and http://www.epa.gov/pesticides/science/post

- app

- exposure

- data.html

.