Page 2 of 68



## Table of Contents

1.0 Executive Summary

................................ ................................ ................................ .................. 4
2.0 HED Recommendations

................................ ................................ ................................ ............ 7
2.1 Data D eficiencies/Conditions of Registration

................................ ................................ .......... 7
2.2 Tolerance Considerations

................................ ................................ ................................ .......... 8
2.2.1 Enforcement Analytical Method

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

................................ ................................ ................................ ...... 8
2.2.3 Recommended Tolerances

................................ ................................ ................................ ......... 8
2.2.4 Revisions to Petitioned

- For Tolerances

................................ ................................ ................... 10
2.3 Label Recommendations

................................ ................................ ................................ ......... 10
2.3.1 Recommendations from Residue Reviews

................................ ................................ .............. 10
2.3.2 Recommendations from Occupational Assessment

................................ ................................ . 10
2.3.3 Recommendations from Residential Assessment

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

................................ ................................ ................................ .................... 11
3.1 Chemical Identity

................................ ................................ ................................ .................... 11
3.2 Physical/Chemical Characteristics

................................ ................................ .......................... 11
3.3 Summary of Existing/Proposed Uses

................................ ................................ ...................... 12
3.4 Anticipated Exposure Pathways

................................ ................................ ............................. 14
3.5 Consideration of Environmental Justice

................................ ................................ ................. 14
4.0 Hazard Characterization and Dose

- Response Assessment

................................ ..................... 15

4.1 Hazard and Dose

- Response Characterization

................................ ................................ ......... 15

4.1.1 Database Summary

................................ ................................ ................................ .................. 15

4.2 Absorption, Distribution, Metabolism, & Elimination (ADME)

................................ ............ 15

4.2.1 Dermal Absorption

................................ ................................ ................................ ................... 16
4.3 T oxicological Effects

................................ ................................ ................................ .............. 16
4.4 Safety factor for Infants and Children (FQPA Safety Factor)

................................ ................ 18
4.4.1 Completeness of the Toxicology Database

................................ ................................ .............. 18
4.4.2 Evidence of Neurotoxicity and Immunotoxicity

................................ ................................ ...... 19
4.4.3 Evidence of Sensitivity/Susceptibility in the Developing or Young Animal

.......................... 20
4.4.4 Residual Uncertainty in the Exposure Database

................................ ................................ ...... 20
4.5 Toxicity Endpoint and Point of Departure Selections

................................ ............................ 20
4.5.1 Dose

- Response Assessment

................................ ................................ ................................ .... 20
4.5.2 Recommendation for Combining Routes of Exposures for Risk Assessment

........................ 22
4.5.3 Classification of Carcinogenic Potential

................................ ................................ ................. 22
4.5.4 Summary of Points of Departure and Toxicity Endpoints Used in Human Risk

Assessment

................................ ................................ ................................ .............................. 23
5.0 Dietary Exposure and Risk Assessment

................................ ................................ ................. 24
5.1 Metabolite/Degradate Residue Profile

................................ ................................ .................... 24
5.1.1 Summary of Plant and Animal Metabolism Studies

................................ ................................ 24
5.1.2 Summary of Environmental Degradation

................................ ................................ ................ 25
5.1.3 Comparison of Metabolic Pathways

................................ ................................ ........................ 26
5.1.4 Residues of Concern Summary and Rationale

................................ ................................ ......... 27
5.2 Food Residue Profile

................................ ................................ ................................ ............... 27Page 3 of 68

5.3 Water Residue Profile

................................ ................................ ................................ ............. 29
5. 4 Dietary Risk Assessment

................................ ................................ ................................ ........ 30
5.4.1 Description of Residue Data Used in Dietary Assessment

................................ ...................... 30
5.4.2 Percent Crop Treated Used in Dietary Assessment

................................ ................................ . 30
5.4.3 Acute Dietary Risk Assessment

................................ ................................ ............................... 30
5.4.4 Chronic Dietary Risk Assessment

................................ ................................ ........................... 30
5.4.5 Cancer Dietary Risk Assessment

................................ ................................ ............................. 31
5.4.6 Dietary Summary Table

................................ ................................ ................................ ........... 31 6.0 Residential (Non

- Occupational) Exposure/Risk Characterization

................................ ......... 31
6.1 Handlers

................................ ................................ ................................ ................................ .. 32
6.2 Post

- application Exposure

................................ ................................ ................................ ...... 32
6.2.2 Inhalation Post

- application Exposure

................................ ................................ ...................... 33
6.2.3 Spray Drift

................................ ................................ ................................ ............................... 34
7.0 Aggregate Exposure/Risk Characterization

................................ ................................ ............ 34
7.1 Acute Aggregate Risk

................................ ................................ ................................ ............. 35

7.2 Short

- and Intermediate

- Term Aggregate Risk

................................ ................................ ....... 35
7.3 Cancer Aggregate Risk

................................ ................................ ................................ ........... 36
7.4 Cancer Aggregate Risk

................................ ................................ ................................ ........... 36
8.0 Cu mulative Exposure/Risk Characterization

................................ ................................ .......... 36
9.0 Occupational Exposure/Risk Pathway

................................ ................................ .................... 36
9.1 Handlers

................................ ................................ ................................ ................................ .. 36
9.2 Occupational Post

- application

................................ ................................ ................................ 43
9.2.1 Occupational Post

- application Dermal

................................ ................................ .................... 43
9.2.1 Occupational Post

- application Inhalation

................................ ................................ ................ 45
10.0 References

................................ ................................ ................................ ............................... 45 Appendix A: Toxicology Profile and Executive Summaries

................................ .......................... 47

A.1 Toxicology Data Requirements

................................ ................................ .............................. 47
Table A.2.3 Acute Toxicity Profile

– Primo TM Formulation (12% Trinexapac

- ethyl )

................ 48 A.3 Hazard Identification and Endpoint Selection

................................ ................................ ............. 54Page 4 of 68

1.0 Executive Summary

Trinexapac

- ethyl is a plant growth regulator used on perennial grass grown for seed. It is proposed for its first food uses on sugarcane and cereal grain s (barley

, oats, triticale, and wheat ). Previously, Syngenta proposed registration of the 1 lb/gal EC product on grasses to include

gras ses grown for seed throughout the U.S. However, a number of deficiencies were noted in the petition that precluded establishing permanent tolerances for trinexapac

- ethyl in grass and
livestock commodities and resulted in a regionally restricted registrati on on ryegrass

.

Syngenta has re

- proposed use of trinexapac

- ethyl in/on grasses grown for seed throughout the U.S. and proposes registration and tolerances of the 1 and 2 lb/gal EC products for this use (PP# 0F7719 ) . The proposed use directions would allow for a single or split application of trinexapac

- ethyl to grasses grown for seed during stem elongation and floral development, at a
maximum application rate of 0.5 lb ai/A. The registrant has proposed a maximum seasonal rate of 0.5 lb ai/A, a 35

- day preh arvest interval (PHI) for ma ture grass, and a 49

- day pre

- grazing interval (PGI) for regrowth of forage and hay following harvest. In additi on, the registrant is proposing new uses and tolerances to support the use of the 1 and 2 lb /gal EC products o n cereal grains ( barley, oats, triticale, and wheat ) and sugarcane (PP#0F7720) . The registrant proposes to
allow a maximum seasonal rate of 0. 11 lb ai/A and a 4 5

- day PHI for cereal grains and a maximum seasonal rate of 0. 31 lb ai/A and a 28

- day PHI for suga rcane.

Hazard Characterization

The toxicity database for trinexapac

- ethyl is incomplete under the new 40 CFR Part 158 data requirements for conventional pesticides, which requires certain generic testing, including acute (in review) and subchronic neurot oxicity studies. However, the Agency believes that the current toxicity database is adequate to evaluate the hazards associated with these new uses.

Trinexapac

- ethyl is a cyclohexadione plant growth regulator that inhibits the biosynthesis of gibberellin (GA 1 ), which is a phytohormone that promotes growth of various plant organs. In mammals, the compound is rapidly and extensively absorbed (> 95% of the administered dose) and rapidly eliminated (> 85% of the administered dose eliminated within 12 h), with no significant bioaccumulation. Significant residues identified in the rat metabolism study were the acid metabolite of trinexapac

- ethyl (approximately 80

– 90% of radioactivity) and the parent compound (<1%). The acute toxicity is low via t he oral, dermal, or inhalation routes of exposure (Categories III

- IV), and it is not a dermal sensitizer. The toxicity profile of trinexapac

- ethyl is attached ( Appendix A; Table A2 ).

Trinexapac

- ethyl is a low toxicity chemical with a high acute oral LD 50 (oral LD 50 = 5,000 mg/kg) and systemic effects occurring at or well above 300 mg/kg/day in subchronic and lifetime dosing studies. At higher doses, however, there is e vidence of increased qualitative and quantitative susceptibility in the developmental and reproduction studies . Developmental toxicity was observed in the rat at the limit dose (increased incidence of asymmetrical sternebrae) and rabbit (decreased number of live fetuses/litter and increased post

- implantation loss) at the highest dose test ed , with no evidence of maternal toxicity observed at the highestPage 5 of 68

dose tested in either species. Clear no

- adverse

- effect

- levels (NOAELs) were established in these developmental studies. I n the multi

- generation rat reproduction study, parental and offspri ng toxicity occurred at the limit dose ; however, the type of effect in the offspring was more severe (decreased pup survival). No reproductive toxicity was observed up to the limit dose.

An in utero effect from the developmental rabbit study provided an acute reference dose for
females 13

- 49 yrs old but is not appropriate for the general population. An acute dietary endpoint was not identified for the general population. T he chronic reference dose (cRfD) wa s based on the chronic dog toxicity study which i s considered conservative since the NOAEL is more than

10

- fold lower (i.e., more protective) than the dose LOAEL at which neurotoxicity was observed in the same dog study

. Since the point of departure for the chronic assessment is also approximately 10

- fo ld lower than the dose levels where developmental toxicity was seen in the developmental rabbit study, it is also protective of any developmental or offspring toxicity.

E ndpoint s of concern for the incidental oral , dermal and inhalation scenarios for children are not available from the trinexapac

- ethyl toxicity studies. The short

- and intermediate

- term dermal and
inhalation adult scenarios were based on the developmental rabbit study. Since the dermal and
inhalation scenarios are based on the same stu dy , they can be combine d when assessing occupational exposure.

HED recommends that the 10x FQPA Safety Factor be reduced to 1x, as t he toxicological
database for trinexapac

- ethyl is adequate

. The toxicological database for trinexapac

- ethyl is complete wi th regard to pre

- and postnatal toxicity , acute neurotoxicity (in review), immunotoxicity, and there are no residual uncertainties

. In addition, the exposure databases are of high quality such that dietary and residential exposures will not be underestimat ed.

T rinexapac

- ethyl has been classified as ―not likely to be carcinogenic to humans,‖ and therefore, does not require quantification of cancer risk.

Metabolism/Metabolites and Degradates of Concern

The metabolism of trinexapac

- ethyl in plants and a nimals has been adequately delineated. The primary degradation pathway in both livestock and plants involves trinexapac

- ethyl rapidly underg oing hydrolysis of the ethyl ester to form trinexapac.

The residue of concern in primary crops

, rotational crops and livestock for both tolerance
enforcement and risk assessment i nclude free and conjugated residues of both parent trinexpac

ethyl and its acid metabolite , trinexapac . In drinking water

, degradates of concern for risk

assessment are trinexapac

- ethyl

, tr inexapac

, 2

- (4

- cyclopropyl

- 4

- hydroxy

- 2

- oxobutyl)succinic acid ( CGA

- 313458 ) , an open chain cyc lohexane ring, and the unidentified hydroproduct M3.

Food Residue Profile

The residue profile for the proposed commodities is adequate. For all commodities, the registrants submitted adequate field trial data for parent trinexapac

- ethyl as trinexapac . The
recommended tolerances range from 0.4 ppm in barley straw to 40.0 ppm in grass seed s. For allPage 6 of 68

field grown crops, a dequate numbers of trials were performed in the recommended NAFTA growing zones. Concentration was observed in some processed commodities such that separate
tolerances are needed on , wheat middling only

. Based on cattle and hen feeding studies tolerances are needed for the meat, fat, and meat byproducts of cattle, goats, horses, sheep and hog . The recommended tolerances for all commodities are listed in Table 2.2.3

.

Dietary Exposure and Ris k

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

. These unrefined assessments a re based on tolerance

- level residues

, 100% crop treated assumptions for all commodities , and d efault processing factors. The acute and chronic dietary r isk estimates are below HED’s level of concern for all population subgroups, including those comprised of infants and children. Because such conservative assumptions were made in the assessments, HED is confident that the acute and chronic dietary exposur e assessments do not underestimate risk to the general U.S. population or any population subgroup.

Residential Exposure and Risk

HED determined that there is a potential for residential exposure to trinexapac

- ethyl from the currently registered turf us es . HED assumes that only short

- term exposures are applicable to
residential handler risk assessments , and are considered to be protective of intermediate

- term exposure and risk

. The combined dermal plus inhalation risk estimate s to residential handlers do not exceed HED’s level of concern for all scenarios (i.e., MOEs ≥ 100)

.

HED determined that there is a potential for exposure from entering trinexapac

- ethyl

- treated residential areas, such as lawns, sports fields, and golf courses that could lead to post

application exposures to adults. Short

- term dermal risk estimate s we re estimated for adults only. The residential post

- application margin of exposure ( MOEs ) ranged from 650 to 24,000
and therefore

, do not exceed HED’s level of concern (MOE ≥ 100).

Aggregate Exposure and Risk

The acute (females only) and chronic aggregate risks are equivalent to the corresponding dietary (food plus water) risks, which are not of concern. The short

- and intermediate

- term dermal and
inhalation toxicological endpoin ts for trinexapac

- ethyl are the same. The resulting aggregate
short

- and intermediate

- term risk estimates (MOE ≥ 100) ; therefore, the short

- and intermediate

term aggregate risks of exposure to trinexapac

- ethyl are not of concern.

Occupationa l Exposure and Ris k

It is anticipated that there will be occupational handler and post

- application exposure from the proposed agricultural uses as well as all of the currently registered uses of trinexapac

- ethyl

. Dermal and inhalation risks for short

- and intermedia te

- term exposures were combined in this assessment, since the toxicological effects for the dermal and inhalations routes were the same.

MOE s greater than or equal to 100 for dermal and inhalation routes is deemed adequate to protect occupational trinexap ac

- ethyl handlers. All handler scenarios resulted in MOEs greaterPage 7 of 68

than the level of concern (i.e., MOEs ≥ 100) when wearing labeled personal protective equipment (PPE) (e.g

. , long

- sleeve shirt, long pants, shoes, socks, chemical

- resistant gloves, and
prot ective eyewear) and, therefore are not of concern. The label restricted entry interval (REI) of

12

- hour is appropriate and in compliance of the Worker Protection Standard requirements.

Occupational short

- and intermediate

- term dermal exposures are expected from post

- application
activities. Chemical

- specific data relevant to post

- application were not submitted; therefore,
post

- application exposure estimates were calculated using standard HED default assumptions. Using default dislodgeable foliar re sidue values, risk estimate s are not a concern for any post

application occupational scenario on day 0, except for hand

- harvesting sugarcane where the
MOE increases to 110 within 8 days of application (short

- and intermediate

- term post

application)

. Howev er, HED does not recommend that sugarcane REI’s be changed on the trinexapac

- ethyl labels at this time based on two main issues. First , almost all sugarcane harvesting in the United States is done mechanically. Secondly , the proposed trinexapac

- ethyl
lab els have a 28

- day pre

- harvest interval (PHI) for sugarcane so hand harvesting should not occur until after 28 days which is protective of the estimated REIs

.

Human Studie s

This risk assessment relies in part on data from studies in which adult human subjects were intentionally exposed to a pesticide or other chemical. These studies, which comprise the
Pesticide Handlers Unit Exposure Reference Table ( O PHED)

, the Agricultural Reentry Task Force (ARTF), and the Outdoor Residential Exposure Task Force (ORETF) da tabase s , have been determined to require a review of their ethical conduct, have received that review, and have been
determined to be ethical.

2.0 HED Recommendations

P rovided the registrant submits a revised Section F

, there are no human health risk estimates of concern that would preclude the establishment of tolerances for the residue s of trinexapac

- ethyl. A new entry should be made in the 40 CFR for the active ingredient trinexapac

- ethyl to support
the new uses.

2.1 Data Deficiencies/Conditions of Registration

The registrant is required to submit a revised Section F in which the recommended tolerances

l isted in Table 2.2.3. are proposed.

The following data should be submitted:

TOXICOLOGY

870. 6200 NeurotoxicityPage 8 of 68

The acute (in review) and subchronic neurotoxicity studies are required under 40 CFR Part 158 for registration of a pesticide (food and non

- food uses).

2.2 Tolerance Considerations

2.2.1 Enforcement Analytical Method

An adequate enforcement method is available for trinexapac

- ethyl , Method GRM020.01A

, which utilizes high performance liquid chromatography with triple

- quadrupole mass
spectrometry (LC

- MS/MS). The new method includes a strong acid hydrolysis/extraction procedure to release both ―free‖ and ―conjugated‖ residues of CGA179500 from field grown grass commodities

. The reported limit of quantitation (LOQ) is 0.010 pp m . The met hod has been adequately validated. Also, trinexapac

- ethyl was evaluated using the FDA multiresidue method Protocols C and D, and its acid metabolite, trinexapac, was evaluated using Protocol B.
These data indicate FDA multi

- residue methods are not suitab le for determining residues of trinexapac

- ethyl and trinexapac in plant commodities.

2.2.2 International Harmonization

There are no established or proposed Codex, Canadian, or Mexican maximum residue limits (MRLs) for trinexapac

- ethyl in or on any f ood or feed crops. However, a variety of European countries, as well as Argentina, Brazil, Japan, Korea, and Australia have established or proposed MRLs for trinexapac

- ethyl on cereal grains (0.02

- 0.5 mg/kg), cereal grain forages and fodders (0.2

- 3 mg/k g), sugar cane (0.05

- 0.1 mg/kg), sugar forage and fodder ( 1 mg/kg), meat (0.02

m g/kg), and/or milk (0.1

- 0.005 mg/kg).

2.2.3 Recommended Tolerances

Tolerances should be established for residues of the plant growth regulator trinexpac

- ethyl, including its met abolite and degradate, in or on the commodities listed below. For plant and livestock commodities, the tolerances should be established as follows:

Tolerances are established for residues of trinexapac

- ethyl, including its metabolites an d degradates, i n or on the commodities in the table below. Compliance with the tolerance levels specified below is to be d etermined by measuring both trinexapac

- ethyl, ethyl 4

- (cyc lopropylhydroxymethylene)

- 3, 5

- dioxocyclohexanecarboxylate and the associated
metabolite tri nexpac, 4

- (cyclopropylhydroxymethylene)

- 3,5

- dioxocyclohexanecarboxylic
acid , calculated as the stoichiometric equivalent of trinexapac

- ethyl.Page 9 of 68

Table 2.2.3 Tolerance Summary for Trinexapac

- ethyl.

Commodity Proposed Tolerance (ppm) Recommended Tolerance (ppm) Comment

(correct commodity definitions)

PP# 0F7719
Grass, forage 1.6 1.5
Grass, hay 3.5 4.0
Grass, seed screenings 45.0 40 .0

Grass, straw 12.0 10 .0

Cattle, fat 0.05 0.02

Cattle, meat 0.05 0.02
Cattle, meat byproducts 0.05 0.04 Based on highest residue in cattle kidney

Goat, fat 0.05 0.02

Goat, meat 0.05 0.02
Goat, meat byproducts 0.05 0.04 Based on highest residue in cattle kidney

Horse, fat 0.05 0.02

Horse, meat 0.05 0.02
Horse, meat byproducts 0.05 0.04 Based on highest residue in cattle kidney
Sheep, fat 0.05 0.02
Sheep, meat 0.05 0.02
Sheep, meat byproducts 0.05 0.04 Based on highest residue in cattle kidney

PP# 0F7720
Barley, grain 1.60 2.0
Barley, hay 0.70 0.8
Barley, straw 0.35 0.4
Cattle, kidney 0.05 Not needed Based on the recommended tolerance for ―cattle, meat byproducts‖ an individual tolerance for kidney is not
needed.
Sugarcane, cane 0.80 0.8
Hog, fat None 0.02

Hog, meat None 0.02
Hog, kidney 0.05 0.03 Hog, meat byproducts Based on highest residue in cattle kidney
Oat, forage 1.00 1.0 Data translated from wheat forage
Oat, grain 4.10 4.0 Data translated from wheat grain
Oat, hay 1.30 1.5 Data translated from wheat hay

Oat, straw 0.70 0.9 Data translated from wheat

strawPage 10 of 68

Table 2.2.3 Tolerance Summary for Trinexapac

- ethyl.

Commodity Proposed Tolerance (ppm) Recommended Tolerance (ppm) Comment

(correct commodity definitions)
Wheat, forage 1.00 1. 5
Wheat, grain 4.10 4.0
Wheat, hay 1.30 1.5

Wheat, straw 0.70 0.9

Tolerances that need to be proposed
Wheat middling None 6 .5

2.2.4 Revisions to Petitioned

- For Tolerances

As noted in Table 2.2.3 many of the proposed tolerances are different from the tolerances being recommended by HED . The reason for the differences may be that the Agency imputing the
mean residue values from each trial site instead of the individual residue value s into the OECD

MRL calculator . Also, HED dietary burden was calculated differently (using the highest residue instead of tolerance level residues). The registrant should submit a revised Section F in which the proposed tolerances are the same as those r ecommended by HED.

2.3 Label Recommendations

2.3.1 Recommendations from Residue Reviews

The label must be modified to specify a 30

- day plantback restriction for cereal grains and leafy vegetables, and prohibit the planting of all other crops not listed on the label.

2.3.2 Recommendations from Occupational Assessment

Not all of the current trinexapac

- ethyl labels have the proper REIs in place to reflect the acute toxicity of trinexapac

- ethyl (Toxicity Category III for acute dermal, oral, and primary eye irritation, and Category IV for acute inhalation and primary skin irritation). Per the Worker Protection Standard (WPS), a 12

- hr restricted entry interval (REI) is required for chemicals classified under Toxicity Category III/IV. The Registration Division (RD) should ensure the proper REIs are put in place on the labels to reflect these requirements.

2.3.3 Recommendations f rom Residential Assessment

No label revisions are needed for residential purposes and no recommendations are being made by HED

.Page 11 of 68

3.0 Ingredient Profile

Trinexapac

- ethyl is a new plant growth regulator being proposed by Syngenta Crop Protection
for use on grasses grown for seed , sugarcane and cereal grain s throughout the U.S. Trinexapac

ethyl inhibits internodal elongation and growth in cereal grains, grasses and several dicotyledonous species.

3.1 Chemical Identity

Table 3.1. Test Compound Nomenclature Compound

Common name Trinexapac

- ethyl Company experimental name CGA163935

IUPAC name ethyl ( RS )

- 4

- cyclopropyl(hydroxy)methylene

- 3,5

- dioxocyclohexanecarboxylate

CAS name ethyl 4

- (cyclopropylhydroxymethylene)

- 3,5

- dioxocyclohexanecarboxylate CAS registry number 95266

- 40

- 3

End

- use product (EP) 1.0 lb/gal EC (PalisadeTM EC; EPA Reg. No. 100

- 949) 2.0 lb/gal EC (Palisade 2EC; EPA Reg. No. 100

- 1241) Regulated Metabolite

Common Name Trinexapac Company Experimental

Name CGA

- 179500

IUPAC name ( RS )

- 4

- cyclopropyl(hydroxy)methylene

- 3,5

- dioxocyclohexanecarboxylic acid

CAS name 4

- (cyclopropylhydroxymethylene)

- 3,5

- dioxocyclohexanecarboxylic acid CAS registry number 104273

- 73

- 6

3.2 Physical/Chemical Characteristics

Trinexapac

- ethyl has a relatively low octanol/water partition coefficient. At pH 5.3, the l og K OW value is 2.44 ( K OW = 275 ). It has a low vapor pressure ( 2.16 x 10 - 3 PA at 25oC), which decreases its potential for inhalation exposure. Trinexapac

- ethyl has a low potential to leach intoPage 12 of 68

groundwater and is not expected to be volatile, because of the low vapor pressure (2.16 x 10 - 3 Pa
at 25 o C) . See Table 3.2 for a listing of trinexapac

- ethyl physical and chemical properties.

Table 3.2. Physical and Chemical Properties of Trinexapac

- Ethyl.

Parameter Value Reference Melting point/range 36.1

- 36.6°C Provided in MRID
46809305 pH 3.3 Density (20oC) 1.215 g/cm 3
Water solubility (g/L at 25°C) 2.8 at pH 4.9 10.2 at pH 5.5 21.1 at pH 8.2 Solvent solubility Acetone 100% Ethanol 100%
Toluene 100% n

- octanol 100%

n

- hexane 5% Vapor pressure (25oC) 2.16 x 10 - 3 Pa Dissociation constant, pK

a 4.57

Octanol/water partition coefficient, Log(K OW ) at 25oC 2.44 at pH 5.3

UV/visible absorption spectrum Neutral: 9335 L/mol·cm @ 240.2 nm
13976 L/mol·cm @ 277.4 nm
Acidic: 11712 L/mol·cm @ 240.0 nm
12368 L/mol·cm @380.4 nm
Basic: 21320 L/mol·cm @ 270.8 nm

3.3 Summary of Existing/Proposed Uses

Trinexapac

- ethyl is a cyclohexadione plant growth regulator that is marketed as an emulsifiable concentrate, wettable powder packed in water

- soluble bags, granule, and as a technical chemical used for formulation only. The form ulations being proposed by Syngenta for use on cereal grains ( barley, oats, triticale, and wheat ), sugarcane, and grasses grown for seed are the 1 lb/gal EC (12% ai, PalisadeTM EC; EPA Reg. No. 100

- 949) and the 2 lb/gal EC ( 25.5%, Palisade ® 2EC; EPA Reg. No . 100

- 1241 ). An analysis of the exposures and risk estimates resulting from the currently registered uses of trinexapac

- ethyl has also been included because significant changes have been made to the trinexapac

- ethyl hazard assessment. Both EC formulations are currently registered for use on perennial ryeg rass in the Pacific Northwest. Trinexapac

- ethyl also has multiple products (e.g., liquids, granules, and wettable powders packed in water soluble bags ) that are registered for use on turf a reas such as sod farms, golf courses, sport fields, and cemeteries. The proposed new uses are summarized in Table 3.3.Page 13 of 68

Table 3. 3 Summary of Directions for the Proposed Uses of Trinexapac

- Ethyl.

Applic. Timing, Type, and Equip. Form.

[EPA Reg. No.] Applic.

Rate (lb ai/A) Max. No.

Applic.

per Season Max.

Seasonal Applic. Rate (lb ai/A) RTI

(days) PHI (days) Use Directions and Limitations

Grasses grown for seed 1

Broadcast foliar application 1.0 lb/gal

EC [100

- 949]

2.0 lb/gal
EC [100

- 1241] 0. 0 9

-

0.50 1

0.5 7

- 10 2 35 For single application, apply before or during stem elongation stage of development (Zadoks 30

- 37
or Feekes 5

- 8). For split application, apply the first application before or during stem elongation stage of development (Zadok 30

- 37
or Feekes 5

- 8) followed by a second application 7

- 10 days
later. Do not allow livestock to graze or cut for feed within 49 days of the last application. Other crops may be planted 30 days after the last application. Apply
in a minimum of 5 and 10 gal/A using aerial and

groun d equipment, respectively. 0.05

- 0.25 2

Cereal Grains including Wheat (Winter, Spring, and Durum), Barley (Winter and Spring), Oats, and
Triticale

Broadcast foliar application

1.0 lb/gal

EC [100

- 949]

2.0 lb/gal

EC [100

- 1241] 0.09

-

0.11 1

0.11 NA 3

45 Apply at Feekes 5 (leaf sheath strongly erect) to Feekes growth stage 8 (ligule of flag leaf visible). Apply before the flag leaf sheath extends. For barley, it is recommended to apply
before the third node. For improved root development, apply at Feekes 3

- 5 (tillers
formed to leaf sheath strongly erect). Apply in a minimum of 20 gal/A.

Broadcast foliar application 0.05 2 NS 3 For split applications, apply
at Feekes 4

- 5 (leaf sheaths lengthening to leaf sheath strongly erect) and then again at Feekes 7 (second node visible). For barley, apply at Feekes 6

- 7 (1 st to
2 nd nodes visible) and then again at 8 (flag leaf just visible). Apply in a minimum of 20 gal/A.Page 14 of 68

Table 3. 3 Summary of Directions for the Proposed Uses of Trinexapac

- Ethyl.

Applic. Timing, Type, and Equip. Form.

[EPA Reg. No.] Applic.

Rate (lb ai/A) Max. No.

Applic.

per Season Max.

Seasonal Applic. Rate (lb ai/A) RTI

(days) PHI (days) Use Directions and Limitations

Sugarcane

Broadcast foliar application for ripening

1.0 lb/gal

EC [100

- 949]

2.0 lb/gal

EC [100

- 1241] 0.18

-

0.31 1

0.31 NA 3 28 Application may be made

28

- 60 days prior to harvest to increase sugar content
and/or extend harvest
window.

Broadcast foliar application for
internode shortening for seed piece production 0.06

- 0.2 2 NS 3 NS For split applications, make first application when 6 fully developed full size leaves have appeared. Note the
bottom leaf should be feeding internodes above the
soil surface. Make a second application when 6 additional fully developed
full size leaves h ave appeared.

1 PP#0F7719, Section B for grasses grown for seed specifies that other crops may be planted 30 days after the last application.

2 For split applications, the second application should be made 7

- 10 days following the first application.

3 NA = Not Applicable; NS = Not Specified

3.4 Anticipated Exposure Pathways

The Registration Division requested that HED perform an assessment of human health risk to support the proposed new use of trinexapac

- ethyl on cereal grains, sugarcane, turf grass, sod farms, golf courses, and residential lawns . Humans m ight be exposed to trinexapac

- ethyl i n food and drinking water because trinexapac

- ethyl may be applied directly to growing crops . In addition, these applications can result in trinexapac

- ethyl reac hing surface and groundwater , both
of which can serve as sources of drinking water. The uses on turf grass result in the potential for
both residential and occupational exposures. In a ddition, because of the agricultural uses, applicators might be exposed while handling the pesticide prior to application, mixing/loading the pesticide, a nd during application. T here is a potential for post

- application exposure for
workers re

- entering treated fields.

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 Lo w

- Income Populations, ‖ ( http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf

. As a part of every pesticide risk assessment, OPP considers a large variety of consumer subgroups accord ing to well

- established procedures. In line with OPP policy, HED estimates risks to population subgroups fromPage 15 of 68

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

and activities in and around the home that involve pesticide use in a residential setting. Extensive data on food consumption patterns are compiled by the USDA under the Continuing Survey of Food Intake by Individuals (CSFII) and are used in pesticide risk assessments for all registered food uses of a pes ticide. 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

pe rformed when conditions or circumstances warrant. Whenever appropriate, non

- dietary exposures based on home use of pesticide products and associated risks for adult applicators and for toddlers, youths, and adults entering or playing on treated areas post application are evaluated. Further considerations are currently in development as OPP has committed resources and expertise to the development of specialized software and models that consider exposure to bystanders and farm workers as well as lifestyle an d traditional dietary patterns among specific subgroups.

4.0 Hazard Characterization and Dose

- Response Assessment

4.1 Hazard and Dose

- Response Characterization

Table A.2.1 ( see Appendix A) summarizes the acute toxicity of the technical grade of trinexapac

ethyl. As demonstrated, technical trinexapac

- ethyl is relatively non

- toxic when administered acutely to laboratory animals. Table A.2. 4 ( see Appendix A) summarizes the subchro nic, chronic and other toxicity studies of the technical grade of trinexapac

- ethyl

.

4.1.1 Database Summary

The toxicology database for trinexapac

- ethyl is considered adequate for risk assessment in support of the current registration action under FIFRA S ection 3 for food use with the exception
of an acute (in review) and subchronic neurotoxicity studies that are required as part of EPA guideline requirements (40 CFR § 158)

. Toxicity studies submitted in support of registration are
detailed in the followin g section and a brief summary of the findings is discussed in section 4.3, Toxicological Effects.

4.2 Absorption, Distribution, Metabolism, & Elimination (ADME)

Absorption: T rinexapac

- ethyl was rapidly and extensively absorbed in both sexes of rat following single or repeat low

- dose (0.97 mg/kg bw) administration and single high

- dose (166 mg/kg bw) administration. Greater than 95% of the administered dose was absorbed followin g single or repeat low

- dose administration and single high

- dose administration. Data suggests that there was very little or no biliary absorption. Distribution: The highest residue levels were observed in the fat, lungs, kidneys and liver; however, mean re covery of radioactivity in tissues/carcass at sacrifice (at 168 h post

- dosing) was less than 0.3% of administered dose for all dose groups indicating little potential for accumulation. Metabolism: The major component inPage 16 of 68

urine and fecal extracts was identif ied as 4

- cyclopropyl

- hydroxy

- methylene)

- 3,5

- dioxo

cyclohexanecarboxylic acid, the free acid derivative of trinexapac

- ethyl resulting from hydrolysis of the ester bond of the parent compound accounting for approximately 82

– 91.6% of
the administered dose. The only other residue found (found in fecal extract only) was identified as the parent compound, accounting for less than 0.1% of the administered dose. Excretion: Excretion was rapid, with the majority of radioactivity being eliminated within 12 h post

- d osing

via urine (greater than 85% of the administered dose at the low and high dose) and within 24 h
post

- dosing via feces (0.56

– 1.43 and 0.80

– 2.01% at the low and high dose, respectively). The major route of excretion was via urine, accounting for approxi mately 95% of administered dose at both dose levels. Fecal excretion accounted for approximately 1.0

– 2.4% of administered dose at both dose levels. By 72 h r less than 0.01% of the administered dose was recovered in expired air. Data suggest that there was very little or no biliary excretion. Significant qualitative differences were not found in absorption, distribution, metabolism or excretion of trinexapac

ethyl between the sexes, between single and repeat low

- dose administration, or between single
low

- dos e and high

- dose administration. These results indicate that toxicity of both the parent and acid metabolite has been accounted for in the submitted toxicity studies.

4.2.1 Dermal Absorption

A single dermal dose of 0.01, 0.1, or 1.0 mg/cm 2 14 C

- trinexapa c

- ethyl administered to male rats was rapidly absorbed, distributed and eliminated (MRID 42238105). The amount absorbed increased with duration of exposure. The average 14 C

- trinexapac

- ethyl absorbed within 24 hours was 56.8, 66.7, and 33.8% of the applied dose for the low

- , mid

- , and high

- dose groups, respectively. Recovery of the applied dose was 97

- 117% and most was recovered from the skin washes and urine. A dermal absorption factor of 77.5% was estimated based on the sum of
56.5% absorbed after 10 ho urs in the low dose group (0.01 mg/cm2), in addition to 21% of applied dose that was associated with the application site after wash.

4.3 Toxicological Effects

The acute toxicity of the technical material is low via the oral, dermal, or inhalation rout es of exposure (Categories III

- IV), and it is not a dermal sensitizer. The toxicity profile of trinexapac

ethyl is attached in Appendix A. With the exception of an acute neurotoxicity ( ACN

- has been
submitted ) and subchronic neurotoxicity ( SCN) required b y the new Part 158 guidelines, the toxicology database is complete and adequate to support non

- food and food uses

.

Trinexapac

- ethyl is a low acute toxicity chemical with a high acute oral LD 50 (oral LD 50 = 5,000 mg/kg) and systemic effects occurring at or well above 300 mg/kg/day in subchronic and lifetime dosing studies. There is, however, e vidence of increased qualitative and quantitative suscepti bility in the rat (increased incidence of asymmetrical s ternebrae) and rabbit (decreased number of live fetuses/litter and increased post

- implantation loss) developmental studies, but only at relatively high doses (300

– 1,000 mg/kg/day). Qualitative sensitivity was observed in
the 2

- generation reproduction st udy but only above the limit dose (1,000 mg/kg/day). Decreased pup survival when analyzed with sexes combined resulted in statistical significance (5

- 7%), but was not significant when analyzed separately. Further evaluation of the individual littersPage 17 of 68

sugge sted that one or two litters were not the cause of the reduced pup survival at the highest
dose tested. R eproductive toxicity was not observed up to the limit dose. Refer to Table 4.3.1 for a comparison of the effects across toxicity studies.

Looking ac ross the available toxicity studies, t he dog appears to be the most sensitive species. In adult animals, no systemic adverse effects were seen in rats, rabbits, or mice below the limit dose (1

, 000 mg/kg/day) following subchronic or chronic oral exposure. In the dogs, however, decreased body weight gain and food consumption, diffuse thymic atrophy, and changes in the epithelial cells of the renal tubules were seen in the 90

- day dog study at 516/582 mg/kg/day (males/females). Following chronic exposure, do se

- related neuropathology of the brain was seen at ≥365/357 mg/kg/day in male and female dogs, respectively. The lesions remained confined to the supporting cells in the central nervous system and did not progress to more advanced or more extensive damage of the nervous tissue. They were not associated with other neuropathological findings or overt neurological signs, so their biological significance is unknown. Similar lesions were not observed in the rat or mouse following subchronic or chronic dietary exposure, and there was no other evidence in any other species tested to indicate a neuroto xicity potential. Furthermore, the brain lesions observed in the chronic dog study are not likely to develop from a
short

- term exposure and were not observed in ei ther the rat or mouse short

- term studies. The combined chronic toxicity/carcinogenicity study in the rat did not demonstrate an increase in any tumor type that would be relevant to humans. The observation of squamous cell carcinomas
in the non

- glandular portion of the stomach of two males at 806 mg/kg/day does not provide reasonable evidence of a possible deleterious effect of trinexapac

- ethyl on the pharynx and/or esophagus (non

- glandular areas) of the human because trinexapac

- ethyl would not be in cont act with the human tissues for a significant period of time compared to the length of time with which it would have been in contact with the rat stomach. Follicular adenocarcinoma of the thyroid was significantly increased in males (5%) at 806 mg/kg/day, but was within the historical control range. In the mouse, there was no evidence of carcinogenicity. The mutagenicity database is complete, with no evidence of mutagenicity. The cancer classification for trinexapac

- ethyl is ―Not likely to be carcinogenic to humans.‖

Study summaries of the toxicology studies for trinexapac

- ethyl are provided in Appendix A.

Table 4.3.1 Comparison of NOAELs/LOAELs for consideration in risk assessment for trinexapac

ethyl

Study NOAEL mg/kg/day LOAEL

mg/kg/day Endpoint

Rat Developmental

M aternal 1000 >1000 none

D evelopmental 200 1000 B ased on increased incidence of asymmetrically

- shaped sternebrae

Rabbit Developmental

M aternal 360 (HDT) >360 nonePage 18 of 68

D evelopmental 60 360 (HDT) Based on a decrease in the mean number
of fetuses/litter and an increase in post

implantation loss

2

- Generation Reproduction

- Rat

P arental 594 1212 Based on reduced premating and gestation body weight/body

- weight gain and food consumption

Offspring 594 1212 Based on decreased F1 postnatal survival and reduced pup body weights in both generations [both sexes].

Chronic Dog

Adult males and
females 31.6 357 B ased on elevated serum cholesterol values in females, mucoid feces in females and bloody feces in both sexes, and minimal, focal vacuolation of the dorsal medial hippocampus and/or lateral
midbrain in both sexes.

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

The proposed use pattern for trinexapac

- ethyl could potentially result in dietary (various crops) and residential (turf) exposure to infants and children ; however, was not assessed due to lack of an appropriate endpoint) . Thu s, FQPA hazard considerations were addressed in HED’s evaluation of the toxicology database. HED recommends that the 10x FQPA Safety Factor (for the protection of infants and children) be reduced to 1x. The toxicological database for trinexapac

- ethyl is complete with regard to pre

- and postnatal toxicity, immunotoxicity and neurotoxicity (SCN is required) , and there are no residual uncertainties. Additionally, the dietary exposure assessment is based on conservative, health

- protective assumptions that ens ure that
exposures to trinexapac

- ethyl are not underestimated. These assumptions include tolerance

- level residues and 100% crop treated estimates for all commodities. Furthermore, conservative,

upper

- bound assumptions were used to determine exposure thro ugh drinking water and residential sources, such that these exposures have not been underestimated.

4.4.1 Completeness of the Toxicology Database

The toxicology database is complete with the exception of acute (in review) and subchronic neurotoxicity studies (OPPTS 870.6200a and b) which are new data requirements under 40 CFR Part 158 for registration of a pesticide (food and non

- food uses).

There are no residual uncertainties in the toxicological database and EPA has det ermined that an additional database uncertainty factor for lack of all guideline studies is not needed at this time.Page 19 of 68

The rationale is based on the following: 1) although there is evidence of brain neurotoxicity in the chronic dog study, there are clear NO AELs/LOAELs for this effect; 2) there is a large dose spread in the chronic dog study such that the PoD or NOAEL from the chronic dog study is 10

- fold lower than the dose at which neuropathology is observed and therefore sufficiently protective; 3) there a re no concerns for children via incidental oral ingestion exposures since no endpoint of concern (i.e. non in

- utero ) was identified in the available studies; and 4 ) the registrant has submitted the acute neurotoxicity study (in review) and is currently con ducting the subchronic neurotoxicity study. Preliminary review of the ACN showed no signs of neurotoxicity at the highest dose tested (NOAEL=2000 mg/kg )

.

Currently, an oral toxicity study is being used to assess inhalational exposure. However, with th e oral NOAEL currently used for inhalation risk assessment, all of the occupational and residential
inhalation MOEs are well above the LOC and the conventional 100X safety factor has been applied to inhalation risk assessments. Therefore, even if an inhal ation study were to provide a lower point of departure than the oral study, it's not expected to have a significant impact on aggregate risk.

4.4.2 Evidence of Neurotoxicity and Immunotoxicity

Dose

- related neuropathology characterized as focal bilateral vacuolation of the dorsal medial hippocampus and/or lateral midbrain in both sexes was observed at study termination in the chronic dog study at the two highest doses tested ( 356 mg/kg/day: 3/8 dogs and 727 mg/kg/day: 8/8 dogs in the mid

- and high dose gr oups, respectively). The vacuolation was associated with the astrocytes and oligodendrocytes. The lesions remained confined to the supporting cells in the CNS and did not progress to more advanced or more extensive damage of the nervous tissue.
The lesions were not associated with other neuropathological findings or overt neurological signs. The biological significance of these lesions is not known. Similar microscopic lesions in the brain were not reported in the 90

- day dog study

, although

, there was an in consistency in the level of screening of the brain in the 90

- day study

. It is highly unlikely, however, that lesions would develop within a short

- term (1

- 30 days) period of exposure. Furthermore, s imilar lesions
were not observed in the rat or mouse foll owing subchronic or chronic dietary exposure, and there was no other evidence in any species tested to indicate a neurotoxicity potential.

The registrant has submitted the acute neurotoxicity study (in review) and is currently conducting the subchronic neurotoxicity study. Preliminary review of the ACN showed no signs of neurotoxicity at the highest dose tested (NOAEL=2000 mg/kg).

An i mmun otoxicity study (MRID 48444101 ) in mice was submitted for trinexapac

- ethyl. T his study satisf

ies t he guideline requirement for an immunotoxicity study (OPPTS 870.7800). There were no treatment related effects on mortality, clinical observations, body weights, food consumption, thymus and spleen weights, or macroscopic findings in the splenic antibody

forming cell (A FC) and the Natural Killer c ell (NKC) groups.Page 20 of 68

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

Evidence of increased qualitative and quantitative susceptibility of the offspring was seen only at high doses in the developmental rat and rabbit studies, and reproduction study . Developmental toxicity in the rat was only observed at the limit dose ( increased incidence of asymmetrical
sternebrae at 1,000 mg/kg) in the absence of maternal toxici ty. In the rabbit, no maternal toxicity was demonstrated at the highest dose tested [360 mg/kg/day], but there was a decrease in the mean number of fetuses/litter and an increase in post

- implantation loss at this dose level. However, clearly identified n o effect levels were established in both the rat and rabbit developmental studies. Reproductive toxicity was not observed in the rat reproduction study, but
decreased pup survival and decreased pup body weight/body

- weight gain during lactation were
observ ed above the limit dose with only reduced body weight and food consumption observed in the parental animals (>1200 mg/kg/day).

Although

, there is evidence of susceptibility in the rat and rabbit developmental studies and in
the 2

- generation rat reprodu ction study

, these effects only occurred at the highest dose s tested (360

- 1200 mg/kg/day), for each study, and there were clearly identified NOAELs (60

- 593 mg/kg/day) for each fetal/offspring effect

.

4.4.4 Residual Uncertainty in the Exposure Database

There are no residual uncertainties in the exposure database. Since the dietary and non

- dietary exposure estimates were based on several conservative assumptions, HED does not believe that the exposure estimates are underestimated. The dietary exposure as sessment is based on conservative, health

- protective assumptions that ensure that exposures to trinexapac

- ethyl are not underestimated. These assumptions include tolerance

- level residues and 100% crop treated estimates for all commodities. Actual exposur es and risks from trinexapac

- ethyl will likely be lower. Furthermore, conservative, upper

- bound assumptions were used to determine exposure through drinking water and residential sources, such that these exposures have not been
underestimated.

4.5 Toxic ity Endpoint and Point of Departure Selections

The database is adequate to characterize any potential for prenatal or postnatal risk for infants
and children. The details for selecting toxicity endpoints and points of departure are presented in Appendix A 2.

4.5.1 Dose

- Response Assessment

The acute reference dose (aRfD) is based on the most sensitive acute endpoint observed in the database, which are fetal effects observed in the rabbit developmental study. I t is, therefore, considered protective of all of the developmental effects observed in the rat or rabbit

.Page 21 of 68

The chronic reference dose (cRfD) is also based on the neuropathy from the chronic dog toxicity study. The NOAEL ( 31.6 mg/kg/day ) from this study is more than 10

- fold lower than the LOAEL (357 mg/kg/day) at which brain vacuolization is observed. Since the point of departure
for the chronic assessment (31.6 mg/kg/day ) is approximately 10

- fold lower than the dose levels where developmental toxicity was observed in the developmental rabbit study (360 mg/kg/day),
it is also considered protective for any developmental toxicity.

An endpoint of concern for the incidental oral scenario was not identified from the available trinexapac

- ethyl toxi city studies. The rationale for this conclusion is based on the following weight of evidence considerations: 1) t he t oxicity observed during the appropriate duration of concern (short/intermediate term) were observed only at high doses [LOAEL = 900 mg/kg/ day in the dog, 1000 mg/kg/day in the rat, and 1212 mg/kg/day in the reproduction study]; 2) t he brain
lesions observed in the chronic dog study are not appropriate for this scenario since the brai n lesions were seen only at termination (i.e. after exposur e to 1

- year) and toxicity observed after chronic exposure is not appropriate for application to the short/intermediate term scenarios; 3 )
the brain lesion observed in the chronic study are not expected to occur after short term exposure
due to the lack of similar lesions or associated toxicity (i.e., clinical neurologic signs) in the 90

- day studies in rats or dogs; 4) the cause for concern for the brain lesions is low because of the minimal lesion severity, lack of associated changes (i.e., gliosis, myelin loss astrocyte hypertrophy, neuronal necrosis etc), and the non

- specific nature of the lesions (i.e., focal vacuoles); 5) the overall toxicity profile of this chemical clearly shows that toxicity is observed only at high doses (lowest LOAEL = 360 m/k/d i n the chronic dog study); and 6 ) the in utero endpoint identified in the rabbit study is not appropriate for this population of concern (children).

For adults, the short

- and intermediate

- term dermal and inhalation scenarios are both based on
the in utero effect observed in the rabbit developmental study (LOAEL 360 mg/kg/day). This is protective of female workers that may become pregnant while exposed to trinexapac

- ethyl. The chronic dog study was also considered since it has a similar LOAEL (357 mg/kg/day ). The NOAELs established in these two studies, however, are 2

- fold different due to the dose

- spread in the two studies. Therefore, the higher NOAEL of 60 mg/kg/day from the rabbit developmental study (LOAEL 360 mg/kg/day) is protective of the effects ob served (LOAEL 357 mg/kg/day) in the chronic dog study with NOAEL of 31.6 mg/kg/day. Although the 21

- day rabbit dermal study did not result in systemic toxicity at the limit dose and suggests a dermal assessment is not warranted, this study is performed on ly in adult animals, not pregnant animals. It is currently unknown if a dermal study with pregnant rabbits would result in an in utero effect similar to that observed in the rabbit developmental study. Therefore, the use of the rabbit developmental study
for the short

- and intermediate

- term dermal and inhalation scenarios is conservative and protective for these routes of exposure.

The short

- and intermediate

- term dermal and inhalation endpoints selected for adults are only applicable to adults (females ) because the endpoint is based on in utero effects. HED reviewed the full toxicological database for trinexapac

- ethyl in an attempt to select endpoints for the dermal and inhalation children scenarios; however, no appropriate endpoint was available for

t hese scenarios based on the following reasons:

dermal irritation effects are mild after 21/28 days of exposure in the rabbit study,Page 22 of 68 dermal irritation effects after a single exposure disappear after seven days, there are no systemic effects up to the limit dose in the dermal rabbit study, and there are no adverse toxicological effects (at doses close to the limit dose of 1000 mg/kg/day) in the 2

- generation reproductive study in rats or in the chronic/carcinogenicity studies in rats and mice,

.

The Toxicolog ical Doses and Endpoints for trinexapac

- ethyl are shown on Tables 4.5.4.1 and 4.5.4.2. The trinexapac

- ethyl risk assessment team has recommended that that the FQPA safety factor be reduced to 1X (Section 4.4).

4.5.2 Recommendation for Combining Routes of Expos ures for Risk Assessment

In accordance with the requirements of the FQPA (1996), HED has considered the potential for concurrent exposure to trinexapac

- ethyl via oral, dermal, and inhalation routes. HED aggregates exposure from different routes for each p opulation if the same toxic effects are observed for
similar duration s and routes of exposure . In the case of trinexapac

- ethyl, short

- and

i ntermediate

- term dermal and inhalation can be combined since the PoDs are from the same study (rabbit developmental) and thus the effects are the same

.

4.5.3 Classification of Carcinogenic Potential

Trinexapac

- ethyl is classified as ―Not likely to be carcinogenic to humans‖, and therefore, quantification of cancer risk is not necessary. The mutagenicity database is considered complete, and there was no evidence of mutagenicity.Page 23 of 68

4.5.4 Summary of Points of Departure and T oxicity Endpoints Used in Human Risk

Assessment

Table 4.5.4 . Summary of Toxicological Doses and Endpoints for Trinexapac

- ethyl for use in Human
Health Risk Assessments

. Exposure/
Scenario Point of

Departure Uncertainty/

FQPA Safety

Factors RfD, PAD,

Level of
Concern for
Risk
Assessment Study and Toxicolo g ical Effects

Acute Dietary (General Population

, including
Infants and Children) No appropriate endpoint for the general population including infants and children

Acute Dietary (Females 13

- 49 years of age) NOAEL = 60

mg/kg UF A = 10x

UF H = 10x FQPA SF=

1x Acute RfD =

0.6 mg/kg

aPAD = 0.6 mg/kg Developmental rabbit study

MRID 41869524

LOAEL = 360 mg/kg, based on a
decrease in mean number of fetuses/litter and an increase in post

implantation loss

Chronic Dietary (All Populations) NOAEL=

31.6 mg/kg/day UF A = 10x

UF H = 10x FQPA SF=

1x Chronic RfD =

0.32 mg/kg/day

cPAD = 0.32 mg/kg/day C

hronic oral toxicity study

– dog
MRID 42779402/ 42779401

LOAEL = 357 mg/kg/day, based on
elevated serum cholesterol values in females, mucoid feces in females and bloody feces in both sexes, and minimal, focal vacuolation of the dorsal medial hippocampus and/or lateral
midbrain in both sexes

Incidental
Oral (Short and
Intermediate

Term ) No appropriate endpoint for the incidental oral scenario for childrenPage 24 of 68

Table 4.5.4 . Summary of Toxicological Doses and Endpoints for Trinexapac

- ethyl for use in Human
Health Risk Assessments

. Exposure/
Scenario Point of

Departure Uncertainty/

FQPA Safety

Factors RfD, PAD,

Level of
Concern for
Risk
Assessment Study and Toxicolo g ical Effects

Dermal &
Inhalation
Short

- and
Intermediate

t erm (adults only) NOAEL= 60

mg/kg/day

Dermal absorption
rate = 77.5%
of oral absorption

Inhalation absorption
rate = 100%
of oral absorption UF A = 10x

UF H = 10x FQPA SF=

1x Residential

LOC for MOE

= 100

Occupational
LOC for MOE

= 100 Developmental rabbit study

MRID 41869524

LOAEL = 360 mg/kg, based on a
decrease in mean number of fetuses/litter and an increase in post

implantation loss

Dermal &
Inhalation
Short

- and
Intermediate

t erm No appropriate endpoint for the dermal and inhalation scenario for children

Cancer (oral, dermal, inhalation) Classification: ―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). FQPA SF = FQPA Safety Factor. PAD = population adjusted dose (a = acute, c = chronic). RfD = reference dose. MOE = margin of exposure. LOC = level
of concern.

5 .0 Dietary Exposure and Risk Assessment

5.1 Metabolite/Degradate Residue Profile

5 .1.1 Summary of Plant and Animal Metabolism StudiesPage 25 of 68

Primary Crops The nature of the residue in plants (primary and rotational crops) and livestock commodities are adequate. The registrant submitted rice, grass and wheat metabolism studies on [1,2,6

- 14 C

c yclohexyl ]trinexapac

- ethyl. The major metabolite in rice and grass is metabolite trinexapac, CGA 179500. The parent was detected at 2% of the total radioactive residue (TTR). In rice and grass, the metabolism of 14 C

- trinexapac

- ethyl rapidly undergoes hydrolysis of the ethyl ester to form trinexapac. Also, the tricarboxylic acid metabolite , CGA 275537 was identified at the 4x rate in rice (3

- 17%TRR) at 60 DAT and in grass (9

- 15% TRR). CGA 275537 has the potential for inhibiting the citric acid cycle.

Rotational Crops

In field rotation crop studies on l ettuce, radish and wheat, the TRR values in all raw agricultural commodities ( RAC s) were low; only 30

- day plant

- back interval ( PBI ) lettuce, wheat forage and hay samples had TRR >0.01 ppm. No parent trinexapac

- ethyl was found as a radiolabeled residue in any extracted RAC at any PBI. Trinexapac was found in 30

- day PBI wheat forage (20%TRR) and wheat hay (9% TRR). The aconitic acid metabolite ( CGA 312753 ) was found only in wheat hay at 30

- d ay PBI (18% TRR) and 120

- day PBI (11% TRR). The formation of aconitic acid, which is an intermediate in the citric acid cycle, results in the incorporation of the
molecule into natural plant components.

Livestock The metabolism of trinexapac

- ethyl was investigated in both laying hens and lactating goats

. F or poultry, the major residues were identified as the parent compound trinexapac

- ethyl (31% TRR) and its metabolite CGA 179500 (20% TRR). In a ruminant metabolism study, trinexapac

- ethyl
was not dete cted in any goat matrices analyzed. The major 14 C

- residue in milk and all tissues was the acid metabolite, CGA 179500, accounting for 66% of the TRR in liver and 84

- 97% of the TRR in milk and the remaining tissues. The metabolite CGA 113745 was also iden tified in the liver (16% TRR), kidney (6% TRR) and fat (11%), but was not detected in muscle or milk.

5 .1.2 Summary of Environmental Degradation

The major environmental degradates of trinexapac

- ethyl include its free acid CGA

- 179500,
CGA

- 313458, an open chain cyclohexane ring, CO 2 and an unidentified hydroproduct M3. Environmental transport of trinexapac

- ethyl can occur through surface water runoff after rain events, soil and possible wind erosion and spray drift. Leaching into groundwater is not expected to be a major dissipation pathway based on submitted terrestrial field dissipation studies which showed that trinexapac

- ethyl has a low potential to leach. Surface water runoff from the areas of application is assumed to follow topography. Spray drift will follow the wind directions. Potential emission of volatile compounds is not considered as a viable release mechanism for trinexapac

- ethyl, since volatilization is not expected to be a significant route of dissipation.

Considering abiotic deg radation, trinexapac

- ethyl is stable to hydrolysis in acidic and neutral conditions and appears to hydrolyze under basic conditions (t 1⁄2 = 8.1 days). Photodegradation does not appear to be a major degradation pathway in aqueous and soil environments. ThePage 26 of 68

aqueous photolysis study shows an environmental phototransformation half

- life of about 18 days. The compound was considered stable in the soil photolysis study since the extrapolated
half

- life was well beyond the duration of the study.

Biodegradation ap pears to be the major dissipation pathway for trinexapac

- ethyl, specifically
aerobic biotransformation in terrestrial environments and aerobic and anaerobic biotransformation in aquatic environments. Half

- lives ranged from 2.8 hours in a loam soil to

4.3 days in a loamy sand soil in an aerobic soil metabolism study. Half

- lives ranged from 2.8 days in a river water

- sand sediment system to 4.0 days in a pond water

- sandy clay loam sediment system in an aerobic aquatic metabolism stud y . Half

- lives averaged 3 .5 days in pond water and
lake water

- sediment systems in an anaerobic aquatic metabolism study. Biodegradation was slower under anaerobic soil conditions. The estimated half

- life is about 25 days in a sandy loam
soi l

.

5.1.3 Comparison of Metabolic Pathways

The metabolism of trinexapac

- ethyl in crops, livestock, and rats has been well characterized. Major residues identified in plant metabolism and crop field trials include parent trinexapac

- ethyl
and metabolites trinexapac ( CGA 179500 )

, aconitic a cid metabolite CGA 312753 , and tricarboxylic acid metabolite CGA 275537

. Exposure to trinexapac

- ethyl results primarily in systemic toxicity in multiple species including rat, rabbit , and dog, as well as thyroid effects in dogs

. Based on rat metabolism studies, trinexapac

- ethyl is rapidly and exte nsively absorbed (> 95% of administered dose s absorbed), and with li ttle potential for accumulation ( >85%
eliminated w/in 12 hours via ur ine; 2% via feces w/in 24 hours). The major comp onent in urine
and fecal extracts was trinexapac , the free acid derivative of trinexapac

- ethyl resulting from hydrolysis of the ester bond of the parent compound accounting for approximately 82.0

– 91.6% of the administered dose. The only other residue found (found in fecal extract only) was identified as the parent compound, accounting for less than 0.1% of the administered dose. Significant qualitative differences were not found in absorption, distribution, metabolism or excretion of trinexapac

- ethyl betwee n the sexes, between single and repeat low

- dose administration, or between single low

- dose and high

- dose administration. These results indicate that toxicity of both the parent and acid metabolite has been accounted for in the submitted toxicity studies.

The proposed metabolic pathways in rats, livestock and plants are common. Trinexpac

- ethyl involves hydrolysis of the ethyl ester to yield trinexapac (CGA 179500). Trinexapac undergoes cleavage of the hexane ring to yield the succinic acid metabolite, CG A 313458, which then undergoes stepwise oxidation/ decarboxylation to yield saturated and unsaturated tricarboxylic acids, such as CGA 275537 (tricarboxylic acid) and CGA 312753 (aconitic acid).

For drinking water, a total residue approach was used for the risk assessment. The primary degradates that EFED identified were parent, trinexapac (CGA 179500), CGA 313458, the open chain cyclohexane ring, and the unidentified hydroproduct M3. See appendix table A.2.5 for the
structures of these metabolites and degradates.Page 27 of 68

5 .1.4 Residues of Concern Summary and Rationale

For plants (primary and rotational crops) and livestock commodities, the HED recommend s that parent trinexapac

- ethyl and the metabolite trinexapac ( CGA 179500) be the residues of concern
for bo th the tolerance expression and the risk assessment. For drinking water, a total residue approach should be used for the risk assessment. See Table 5. 1. 4 for the summary of metabolites and degradates to be included in the risk assessment.

Table 5.1.4

. Summary of Metabolites and Degradates to be included in th e Risk Assessment

and Tolerance Expression

. Matrix Residues included in Risk Assessment Residues included in Tolerance Expression

Plants Primary Crop Trinexapac

- ethyl parent + Trinexapac metabolite ( CGA 179500 ) Trinexapac

- ethyl parent + Trinexapac metabolite ( CGA 179500 )

Rotational Crop Trinexapac

- ethyl parent + Trinexapac

metabolite ( CGA 179500 ) Trinexapac

- ethyl parent + Trinexapac metabolite ( CGA 179500 )

Livestock Ruminant Trinexapac

- ethyl parent + Trinexapac metabolite ( CGA 179500 ) Trinexapac

- ethyl parent + Trinexapac metabolite ( CGA 179500 )

Poultry Trinexapac

- ethyl parent + Trinexapac

metabolite ( CGA 179500 ) Trinexapac

- ethyl parent + Trinexapac metabolite ( CGA 179500 )

Drinking Water Total residues (parent + identified degradates) 1 Not Applicable

1 A total major residue approach is recommended, including parent and major environmental degradates CGA

179500, CGA

- 313458, the open chain cyclohexane ring, and the unidentified hydroproduct M3.

5 .2 Food Residue Profile

The registrant submitted adequate field trial data from trials comparing trinexapac

- ethyl as trinexapac ( CGA179500 ) residues in/on barley

, wheat

, sugarcane and grass grown for seed following application of an EC formulation containing 2.1 lb ai /gal. E ach field trial included one treated plot in which trinexapac

- ethyl was applied to barley, wheat and sugarcane as a fo liar spray application at a target rate of 0.115 lb ai/A and grass grown for seed at 0.5 lb ai/A (~1x the proposed maximum seasonal rate )

. The recommended MRLs ranged from 0.4 ppm in barley straw to 40.0 ppm in grass seeds. In the residue decline studies , residues declined from the initial to the final sampling. For all field grown crops, adequate numbers of trials were performed in the recommended NAFTA growing zones. Table 5.2 provides a summary of the crop field trials that were performed for trinexap ac

- ethyl.

The submitted confined rotational crop study is adequate to satisfy data requirements. TRR values in all RACs were low; only 30

- day PBI lettuce, wheat forage and wheat hay samples had TRR >0.01 ppm. The maximum TRR was 0.017 ppm (30

- day PBI mature lettuce). No parent trinexapac

- ethyl was found as a radiolabeled residue in any extracted RAC at any PBI. The submitted confined rotational crop study is adequate to satisfy data requirements. TRR values in all RACs were low; only 30

- day PBI lett uce, wheat forage and wheat hay samples had TRR >0.01 ppm. The maximum TRR was 0.017 ppm (30

- day PBI mature lettuce). The data from thePage 28 of 68

confined rotational crop study indicate that trinexapac residues were greater than 0.01 ppm and
were detected at the 3 0

- day PBI. Therefore, the label must be modified to specify a 30

- day plantback restriction for cereal grains and leafy vegetables, and prohibit the planting of all other crops not listed on the label.

In the processing studies that were performed, residues concentrated in some commodities but
not in others. These data suggest that a tolerance is needed for wheat middling at 6 .5 ppm.

Freezer storage stability data are available which demonstrate that residues of trinexapac are stable under frozen storage conditions for up to 24 months for wheat grain

, 12 months for wheat

straw , and up to 9 months in grass. To support the sample storage durations in the dairy cattle feeding study , s amples were stored frozen (≤

- 18 o C) for up to 121 days and then analyzed with freshly fortified samples. To support the sample storage durations in the poultry feeding study

, samples were stored frozen (

- 20 °C) and then analyzed at 0 and 31

- 82 days with freshly fortified samples

.

T he residue data from the cattle feeding study are adequate to satisfy data requirements. HED concludes that the following tolerances are appropriate for the free and conjugated residues of both parent and its acid metabolite, trinexapac in livestock commodities: 0.02 ppm for the fat
and meat of c attle, goat, horse, and sheep; 0.04 ppm for the meat byproduct of cattle, goat, horse, and sheep; and 0.02 ppm for the fat and meat of hog; 0.03 ppm for the meat byproduct of hog.

Th e trinexapac residue data from the poultry feeding study is adequate to satisfy data requirements. Based on the transfer coefficients for hen tissues and the relatively low dietary burden for poultry of 3.00 ppm for trinexapac , no tolerances are needed fo r poultry. Although secondary residues occur in poultry kidney, no tolerance is required since poultry kidney is not considered a commodity used as human food [OPPTS 860.1480(d)(4)(iv)].

Table 5.2 . Summary of Residue Data from Crop Field Trials with Trinexapac

- ethyl

Commodity Analyte Total Applic.

Rate (lb ai/A) PHI

(days) Residue Levels (ppm) 1

n Min. Max. HAFT Mean Std.

Dev. Barley (proposed use = 0. 11 lb ai/A total application rate, 45

- day PHI) Barley, hay CGA179500 0.113

- 0.119 30 24 <0.01 0.54 0.48 0.19 0.1 Barley, straw CGA179500 0.114

- 0.120 45 24 <0.01 0.29 0.24 0.11 0.1 Barley, grain CGA179500 0.114

- 0.120 45 24 <0.01 1.3 1.2 0.59 0.3

Wheat (proposed use = 0.1 1 l b ai/A total application rate, 4 5

- day PHI) Wheat, forage CGA179500 0.114

- 0.120 30 40 <0.01 0.98 0.94 0.16 0.2 Wheat, hay CGA179500 0.114

- 0.120 30 39 <0.01 1.3 1.2 0.27 0.3 Wheat, straw CGA179500 0.113

- 0.120 45 40 <0.01 0.64 0.60 0.19 0.2 Wheat, grain CGA179500 0.113

- 0.120 45 39 3 0.07 4.0 3.3 0.73 0.7 Sugarcane (proposed use = 0.31 lb ai/A total application rate, 28

- day PHI) Sugarcane CGA179500 0.313

- 0.341 28 16 <0.01 0.43 0.41 0.16 0.1 Grass grown for seed (proposed use = 0.5 lb ai/A total application rate, 35

- day PHI for mature grass and 49

- day PHI for regrowth of forage and hay following harvest) Grass, forage CGA179500 0.505

- 0.537 49 24 0.031 1.2 0.88 0.24 0.3 Grass, hay CGA179500 0.505

- 0.537 49 22 0.10 3.4 2.6 0.65 0.8 Grass, straw CGA179500 0.505

- 0.537 35 24 0.19 5.7 5.4 2.0 2 Grass, seed screenings CGA179500 0.505

- 0.537 35 22 0.32 20.0 18.3 6.5 7Page 29 of 68 1 The LOQ is 0.010 ppm.

5.3 Water Residue Profile

The drinking water residues used in the dietary risk assessment were provide d by the

E nvironmental Fate and Effects Division (E FED ) in the following memorandum: ― Tier II Drinking Water Assessment for Trinexapac

- Ethyl use on Turf ‖ ( C. Koper , D 395601

, 10/28 /11) and incorporated directly into th e dietary assessment.

Based on the ROCKS memorandum (D390121 , 7/12/11) , the parent ester including its free
acid CGA

- 179500, CGA

- 313458, an open chain cyclohexane ring and an unidentified hydroproduct M3 should be inc luded in a TTR approach for the drinking water assessment.

Water residues were incorporated in the DEEM

- FCID into the food categories ―water, direct, all sources‖ and ―water, indirect, all sources.‖ A Tier II screening

- level drinking water assessment was conducted to support the human health risk assessment for the proposed first food use registration for trinexapac

- ethyl. The recommen ded estimated drinking water concentrations (EDWCs) for the human health risk

- assessment are based on highest predicted value for surface water and groundwater ( see Table 5.3 ). The recommended EDWCs in surface water and ground water are based on 8 applica tions of 0.34 lbs. a.i./acre/year on Pennsylvania turf. For surface water, a foliar ground application to Pennsylvania turf yielded the highest EDWCs. The 1

- in

- 10 yr annual peak (acute) concentration was 12.61 μg/L, the 1

- in

- 10 yr annual mean (chronic) c oncentration was 1.56 μg/L and the 30

- year annual mean (cancer chronic) concentration was 1.04 μg/L. For groundwater, based on the proposed highest annual use rate for turf, the SCI

- GROW model estimated the trinexapac ethyl concentration at 0.009 μg/L.

Table 5.3 provides a summary of the Tier 2 modeled drinking water concentrations. The model and its description are available at the EPA internet site: http://www.epa.gov/oppefed1/models/water/

.

Table 5.3. Trinexapac

- Ethyl Estimated Drinking Water Concentrations (EDWC s) 1 for
Surface Water and Ground Water based on selected Crop Scenarios

Proposed
Label Use PRZM/EXAMS

Scenario 1
(first app date) Method 2 Maximum Application Rate (interval between applications) 1

- in

- 10

year
acute ( μg/L ) 1

- in

- 10

year chronic
( μg/L ) 30

- year

average ( μg/L )

Primo ® WSB

Surface Water

Turf FL Turf

( Feb 15

– foliar) G 8 app @ 0.34 lb a.i./acre 10.16 1.22 0.84

PA Turf ( April 15

– foliar) G 8 app @ 0.34 lb a.i./acre 12.61 1.56 1.04

Ground Water

SCI

GROW Turf

-- 8 app @ 0.34 lb a.i./acre 0.009 0.009 0.009Page 30 of 68

Table 5.3. Trinexapac

- Ethyl Estimated Drinking Water Concentrations (EDWC s) 1 for
Surface Water and Ground Water based on selected Crop Scenarios

Proposed
Label Use PRZM/EXAMS

Scenario 1
(first app date) Method 2 Maximum Application Rate (interval between applications) 1

- in

- 10

year
acute ( μg/L ) 1

- in

- 10

year chronic
( μg/L ) 30

- year

average ( μg/L )

1 For surface water (PRZM/EXAMS), EDWC values adjusted with a Percent C ropped Area (PCA) factor of 1.0

. For ground water (SCI

- GROW), no PCA adjustment was utilized.

2 G = ground application

. Bold numbers denote maximum EDWC values.

5 .4 Dietary Risk Assessment

5 .4.1 Description of Residue Data Used in Dietary Assessment

Acute and chronic aggregate dietary (food and drinking water) exposure and risk assessments were conducted using the Dietary Exposure Evaluation Model DEEM

- FCIDTM, Version 2.03 which uses food consumption data from the U.S. Department of Agriculture’s (USDA’s) Continuing Surveys of Fo od Intakes by Individuals (CSFII) from 1994

- 1996 and 1998.

The acute and chronic analyses are based on tolerance

- level residues

, 100% crop treated assumptions for all commodities and d efault processing factor s

. T he drinking water estimates provided by EF ED are modeled estimates, and were generated using the most conservative model available for the proposed crops. HED is confident that the acute and chronic dietary
exposure assessments significantly over estimate risk to the general U.S. population an d va rious population subgroup s

.

5.4.2 Percent Crop Treated Used in Dietary Assessment

As stated above, the acute and chronic assessments were both based on the assumption tha t 100% of all commodities with trinexapac

- ethyl recommended tolerances will be treat ed.

5 .4. 3 Acute Dietary Risk Assessment

The acute dietary exposure was estimated for females 13

- 49 years old only, since an acute endpoint of concern was not identified for the general U.S. population

. The acute dietary exposure estimate for females 13

- 49 years old is 0. 014348 mg/kg/day (2% of the a cute population adjusted dose (a PAD ) ).

5 .4. 4 Chronic Dietary Risk Assessment

The chronic dietary exposure and risk estimates are conservative since they assume that 100% of crops are treated and that the residues are present at the recommended tolerance levels

. C ombined chronic dietary exposure estimates for food and drinking water are well below HED’s level of concern. Using the DEEM

- FCID software, d ietary exposure is estimated at 0. 00 7884 mg/kg/day for the general U.S. population , which is equivalent to 2 .5 % of the chronic population adjusted d ose (cPAD)

, and 0. 0 19496 mg/kg/day , equivalent to 6 % of the cPAD for children 1

- 2Page 31 of 68

years old, the population subgroup with the highest estimated chronic dietary ex posure to trinexapac

- ethyl. Results for all population subgroup are summarized in Table 5.4. 6 , below.

5 .4. 5 Cancer Dietary Risk Assessment

Trinexapac

- ethyl is classified as ―Not Likely to be Carcinogenic to Humans

, ‖ therefore, a cancer dietary exposure assessment was not conducted.

5 .4. 6 Dietary Summary Table

Table 5.4.6 . Summary of Dietary (Food and Drinking Water) Exposure and Risk for Trinexapac

- ethyl.

Population Subgroup Acute Dietary 1

(95 th % Percentile) Chronic Dietary

Dietary Exposure (mg/kg/day) % aPAD Dietary Exposure (mg/kg/day) % cPAD

General U.S. Population 0.00 7884 2.5

All Infants (< 1 year old) 0.00 5505 2

Children 1

- 2 years old 0.0194 96 6

Children 3

- 5 years old 0.0 19289 6

Children 6

- 12 years old 0.0 13202 4

Youth 13

- 19 years old 0.0 07655 2

Adults 20

- 49 years old 0.0 06283 2

Adults 50+ years old 0.00 5236 2

Females 13

- 49 years old 1 0.0143 48 2 0.0058 95 2

1 aPAD=0.6 mg/kg/day for females 13

- 49 only (no appropriate endpoint for general US population including infants and children) and cPAD=0.32 mg/kg/day

. Not likely to be Carcinogenic to Humans

6.0 Residential (Non

- Occupational) Exposure/Risk Characterizat ion

Trinexapac

- ethyl is currently registered (e.g., liquids, granules, and wettable powders packed in water soluble bags) for use on residential lawns, athletic fields, parks, and golf courses by residential consumers as well as applied by pest control op erators ( PCOs ) and commercial applicators. Based on these uses, residential handler and residential post

- application exposure isPage 32 of 68

expected. HED assumes that only short

- term exposures are applicable to residential handler risk

assessments , and are consider ed to be protective of intermediate

- term exposure and risk. The details regarding the assumptions and calculations used to evaluate residential exposure and risk

are descr ibed in a separate memo (M. Hawkins, DP392798, 8/31/11).

6.1 Handlers

All handler scenarios resulted in MOEs that do not exceed HED’s le vel of concern (i.e., MOEs ≥
100)

.

Table 6.1

. a. Short

- Term Residential Handler Baseline Dermal and Inhalation Exposures

Crop Grouping Target

MOE Dermal

Unit Exposure (mg/lb ai) Inhalation

Unit Exposure (mg/lb ai) Application

Rate a (lb ai/A) Area

Treated Daily b (acres/day) Baseline Baseline Inhalation Total

Baseline Baseline Dermal
Dose c (mg/kg/day) Dermal

MOE d Dose e MOE f Baseline

Dermal +
Baseline
Inhalation
MOE g

Mixer/Loader/Applicator (Liquids)

- Low Pressure Handwand Application

Turf 100 100 0.03 0.34 0.023 0.01 5800 0.0000039 15000000 5800

Mixer/Loader/Applicator (Wettable Powders)

- Low Pressure Handwand Application

Turf 100 250 1.063 0.34 0.023 0.026 2300 0.00014 430000 2300

Mixer/Loader/Applicator (Liquids)

- Hose End Sprayer Application

Turf 100 11 0.017 0.34 0.5 0.025 2400 0.000048 1200000 2400

Mixer/Loader/Applicator (Liquids)

- Backpack Sprayer Application

Turf 100 5.1 0.03 0.34 0.023 0.00053 110000 0.0000039 15000000 110000

Mixer/Loader/Applicator (Granules)

- Push Type Spreader Application

Turf 100 0.67 0.00088 0.44 0.5 0.002 31000 0.0000032 19000000 30000

Mixer/Loader/Applicator (Granules)

- Belly Grinder Application

Turf 100 110 0.062 0.44 0.023 0.015 4000 0.00001 5700000 4000

a. Application rates based on proposed labels

. b. Based on HED Science Advisory Committee Policy 12: Recommended Revisions to the Standard Operating Procedures for Residential Exposure Assessment (February 22, 2001), and on professional judgment.

c. Dermal Dose (mg/kg/day) = daily unit exposure (mg/ lb ai) x application rate (lb ai/acre or lb ai/gal) x acres or gal treated x 75.5 % dermal absorption / body weight (60 kg).
d. Inhalation Dose (mg/kg/day) daily unit exposure (μg/ lb ai) x application rate (lb ai/acre or lb ai/gal) x acres or gal treated x 100% inhalation absorption / body weight (60 kg).

e. Dermal MOE = NOAEL ( 6 0 mg/kg/day) / dermal daily dose (mg/ kg/ day). Level of concern = 100.
f. Inhalation MOE = NOAEL ( 6 0 mg/kg/day) / inhalation daily dose (mg/ kg/ day). Level of concern = 100.

g. Combined Dermal + Inhalation MOE = NOAEL ( 60 mg/kg/day) / Combine d dermal + inhalation dose (mg/kg/day).

6.2 Post

- application Exposure

Based on the SOPs for Residential Exposure Assessment and the uses specified in the proposed labels, the following residential pos t

- application exposure scenarios are evaluated:Page 33 of 68

Dermal d ose from pesticide residues on treated turf: Post

- applicat ion exposure calculations for homeowners (adult s only ) from skin contact with pesticide residues on
treated turf

.

Short

- term dermal risk estimate s we re assessed for adults. The residential post

- application MOEs ranged from 650 to 24,000 and therefore do not exceed HED’s level of concern (MOE ≥ 100).

Table 6.1.a

. Short

- Te rm Residential Postapplication Exposure and Risk Estimates for Trinexapac

- ethyl (Liquids)

Lifestage Postapplication Exposure Scenario Application

Rate Dose a MOEs b

Adult Turf

- sprays High Contact
Lawn Activities (Dermal) 0.34 0.071 840

Golfing (Dermal) 0.17 0.0025 24

, 000

Mowing (Dermal) 0.34 0.0025 24

, 000

a=Turf Transferable Residue x Weight Unit Conversion Factor x Transfer Coefficient x Exposure Time x 0.775/60 (kg) b=NOAEL (60 mg/kg/day)/Average Daily Dose (mg/kg/day)

Table 6

. 1.b. Short

- Ter m Residential Postapplication Exposure and Risk Estimates for Trinexapac

- ethyl (Granular Formulations)

Lifestage Postapplication Exposure Scenario Application

Rate Dose a MOEs b

Adult Turf

- granules High Contact Lawn Activities (Dermal) 0.4 4 0.092 650

Golfing (Dermal) 0.17 0.0025 24,000 Mowing (Dermal) 0.4 4 0.0032 19,000

a=Turf Transferable Residue x 6 Weight Unit Conversion Factor x Transfer Coefficient x Exposure Time x 0.775/60 (kg) b=NOAEL (60 mg/kg/day)/Average Daily Dose (mg/kg/day)

6.2.2 Inhalation Post

- application Exposure

Based on the Agency's current practices, a quantitative post

- application inhalation exposure assessment was not performed for trinexapac

- et hyl at this time primarily because of the low acute inhalation toxicity (Toxicity Category IV) . However, volatilization of pesticides may be aPage 34 of 68

potential source of post

- application inhalation exposure to individuals nearby to pesticide applications. The A gency sought expert advice and input on issues related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009. The Agency received the SAP’s final report on March 2, 20 10 ( http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html ). The Agency is in the process of evaluating the SAP report and may, as appropriate, develop policies and procedures to identify the need for and, subsequently, the way to incorporate pos t

- application inhalation exposure into the Agency's risk assessments. If new policies or procedures are put into place, the Agency may revisit the need for a quantitative post

- application inhalation exposure assessment
for trinexapac

- ethyl

.

6.2.3 Spray Drift

Spray drift is always a potential source of exposure to residents nearby to spraying operations.
This is particularly the case with aerial application, but, to a lesser extent, could also be a potential source of exposure from the ground applicatio n method employed for trinexapac

- ethyl. The Agency has been working with the Spray Drift Task Force, EPA Regional Offices and State Lead Agencies for pesticide regulation and other parties to develop the best spray drift management practices (see the Agen cy’s Spray Drift website for more information at http://www.epa.gov/opp00001/factsheets/spraydrift.htm)

. On a chemical by chemical basis

, the Agency is now requiring interim mitigation measures for aerial applications that must be placed on product labels /labeling. The Agency has completed its evaluation of the new data base submitted by the Spray Drift Task Force, a membership of U.S. pesticide registrants, and is developing a policy on how to appropriately apply the data and the AgDRIFT computer model t o its risk assessments for pesticides applied by air, orchard airblast and ground hydraulic methods. After the policy is in place, the Agency may impose further refinements in spray drift management practices to reduce off

- target drift and risks associate d with aerial as well as other application types where appropriate.

Although a quantitative residential post

- application inhalation exposure assessment was not performed as a result of pesticide drift from neighboring treated agricultural fields, an inh alation exposure assessment was performed for occupational flaggers. This exposure scenario is representative of a worse case inhalation (drift) exposure and may be considered protective of most outdoor agricultural and commercial post

- application inhalat ion exposure scenarios

.

7.0 Aggregate Exposure/Risk Characterization

In accordance with the FQPA, HED must consider and aggregate (add) pesticide exposures and risks from three major sources: food, drinking water, and residential exposures. In an aggr egate assessment, exposures from relevant sources are added together and compared to quantitative estimates of hazard (e.g., a NOAEL or PAD), or the risks themselves can be aggregated. When aggregating exposures and risks from various sources, HED conside rs both the route and duration of exposure.Page 35 of 68

7.1 Acute Aggregate Risk

Acute aggregate risk result s from exposure to residues in food and drinking water alone. The acute dietary exposure analysis included both food and drinking water . Therefore, acute aggregate risk is equivalent to the acute dietary risk

, as discussed in Section 5.4.3, above. All
risk estimates are below HED’s level of concern.

7.2 Short

- and Intermediate

- Term Aggregate Risk

The short

- and intermediate

- term toxicological endpoints for trinexapac

- ethyl are the same for each route of exposure. Therefore, for residential exposure scenarios, only short

- term exposures were assessed, and are considered to be protective of intermediate

- term exposure and risk. Exposure s from th ese scenario s a re aggregated with c hronic dietary exposure from food and
water which is considered to be background exposure. The levels of concern for these exposure
routes are all 100.

For the adult short

- and intermediate

- term aggregate risk assessment, chronic diet ary exposure

was added directly to the adult postapplication exposure estimate. To be health protective, the postapplication scenario was used in the aggregate because it resulted in higher exposure than the
handler scenario. The chronic dietary exposure estimate for the general U.S. population was used to determine the aggregate risk estimate.

For the adult ’s short

- and intermediate

- term aggregate risk assessment, chronic dietary exposure is added directly to the adult postapplication dermal exposure es timates

. The results of the
adult ’s aggregate risk determina tions are given in Table 7.2.a

.

Table 7.2 .a Short

- Term and/or Intermediate Term Dermal Aggregate Risk Calculations

Population Short

- or Intermediate

- Term Scenario

NOAEL mg/kg/day LOC 1 Average

Food and
Water Exposure mg/kg/day Residential

Postapplication

Dermal Exposure mg/kg/day 3 Tota l

Exposure mg/kg/day 4 Aggregate

MOE (food, water, and residential) 5

U.S. Pop 60 100 0.00 7884 Liquid
Products 6 0.071 0.078884 761

U.S. Pop 60 100 0.00 7884 Granular
Products 7 0.092 0.099884 601

1 An UF of 100x was applied to account for interspecies extrapolation (10x) and intraspecies variation (10x) and no additional uncertainty factors/safety factors are required.

2 Maximum Allowable Exposure (mg/kg/day) = NOAEL/LOC

3 Residential Exposure = Dermal exposure from treated turf (see table 6.1.a).

4 Total Exposure = Avg Food & Water Exposure + Residential Exposure

5 Residential Exposure)]Page 36 of 68 6 See Table 6.1.a

7 See Table 6.1.b

7.3 Cancer Aggregate Risk

The chronic aggregate risk assessment results from long

- term exposure to residues in food and drinking water, as there are no residential scenarios that result in long

- term exposure. The chronic dietary exposure analysis included both food and drinking wa ter and, therefore, the chronic aggregate risk assessment is equivalent to the chronic dietary risk assessment discussed
in Section 5.4.4 above. All risk estimates are below HED’s level of concern.

7.4 Cancer Aggregate Risk

The CARC classified trinexapac

- eth yl as ―not likely to be carcinogenic to humans. ‖ The chronic dietary risk assessment is protective of cancer effects and, therefore, cancer risk resulting from exposure to trinexapac

- ethyl is not of concern.

8.0 Cumulative Exposure/Risk Characterization

The Food Quality Protection Act (FQPA) requires the Agency to consider the cumulative risks of chemicals sharing a common mechanism of toxicity. The Agency determined that there was insufficient evidence to suggest trinexapac

- ethyl shares a common mechan ism of toxicity with
other chemical substances. For information regarding EPA’s efforts to determine which 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 Program concerning common mechanism determinations and procedures for cumulating effects from substances
found to have a common mechanism on EPA’s website at http://www.epa.gov/pesticides/cumulative/

.

9.0 Occupational Exposure/Risk Pa thway

9.1 Handlers

An analysis of the exposures and risk estimates resulting from the currently registered uses of trinexapac

- ethyl has also been included because significant changes have been made to the trinexapac

- ethyl hazard assessment since the last trinexapac

- ethyl assessment was completed by
the HED. Based upon the proposed trinexapac

- ethyl use patterns, HED assessed risks to occupational pesticide handlers in the following scenarios:Page 37 of 68

Mixing/loading liquids for aerial applications
Mixing/loading liquids for groundboom applications
Mixing/loading liquids for chemigation
Mixing/loading liquids for LCO handgun applications
Mixing/loading wettable powders in water soluble bags for aerial applications
Mixing/loading wettable powders in water soluble ba gs for chemigation
Mixing/loading wettable powders in water soluble bags for groundboom applications
Mixing/loading wettable powders in water soluble bags for LCO handgun applications
Mixing/loading granules for aerial applications
Mixing/loading granules for tractor drawn spreader applications
Applying sprays for aerial applications
Applying sprays for groundboom equipment
Applying granules for tractor drawn spreader applications
Flagging (liquids) during aerial applications
Flagging (granules) during aerial applications
Mixing/loading/applying wettable powders for low pressure handwand applications
Mixing/loading/applying liquids for backpack sprayer applications
Mixing/loading/applying liquids for handgun sprayer applications
Mixing/loading/applying l iquids for low pressure handwand applications
Mixing/loading/applying wettable powders in water soluble bags for backpack sprayer applications
Mixing/loading/applying water soluble bags for handgun sprayer applications
Mixing/loading/applying granules for belly grinder applications
Mixing/loading/applying granules for push type spreader applications

No chemical

- specific handler exposure data were submitted in support of the Section 3 registration. To assess handler exposures for regulatory actions when ch emical

- specific monitoring data are not available, HED relies on the most scientifically

- reliable surrogate data currently available from various sources such as the Pesticide Handler Exposure Database (PHED), the Agricultural Handler Exposure Task Force ( AHETF), and the Outdoor Residential Exposure Task Force (ORETF). Some of this data, such as the industry task force data, is compensatory, subject to the data protection provisions of the Federal Insecticide, Fungicide, and Rodenticide Act ( FIFRA ) . HED p olicy on use of surrogate data is described in more detail on the Agency's website (http://www.epa.gov/pesticides/science/handler

- exposure

- data.html).
Scenario

- specific surrogate exposure data, including their sources, are presented in the ―Occupational P esticide Handler Unit Exposure Surrogate Reference Table‖ (http://www.epa.gov/pesticides/science/handler

- exposure

- table.pdf).

Handlers’ Exposure and Risk

Short

- term and intermediate

- term risk estimates for occupational h andlers are included in Table
9.1.a . All handler scenarios resulted in MOEs greater than the LOC (MOEs ≥ 100) for dermal, inhalation, and combined dermal and inhalation exposures when wearing labeled PPE (long

-Page 38 of 68

sleeve shirt, long pants, shoes, socks, chemical

- resistant gloves, and prot ective eyewear) and,
therefore are not of concern.

The handler exposure estimates in this assessment are based on a central tendency estimate of unit exposure and an upper

- percentile assumption for the application rate, and are assumed to be representativ e of high

- end exposures. The uncertainties associated with this assessment stem from the use of surrogate exposure data (e.g., differences in use scenario and data confidence), and assumptions regarding the amount of chemical handled. The estimated expos ures are believed to reasonable high

- end estimates based on observations from field studies and professional judgment.Page 39 of 68

Table 9.1.a . Short

- Term and Intermediate

- Term Occupational Handler Dermal and Inhalation Exposures

Crop Grouping Target MOE Dermal Unit Exposure (mg/lb ai) Inhalation Unit

Exposure (mg/lb ai) Application

Rate a Area Treated

Daily b PPE

- G Baseline Inhalation Total

PPE

- G Baseline (lb ai/A) (acres/day) Dermal Dose c (mg/kg/day) Dermal

MOE d Dose e MOE f MOE g

Mixer/Loader (Liquids)

- Aerial Application

Grasses Grown for Seed 100 0.0376 0.000219 0.5 350 0.085 710 0.00064 94000 700

Sod 100 0.0376 0.000219 0.34 350 0.058 1000 0.00043 140000 1000

Sugarcane 100 0.0376 0.000219 0.31 350 0.053 1100 0.0004 150000 1100

Cereals 100 0.0376 0.000219 0.11 350 0.019 3200 0.00014 430000 3200

Mixer/Loader (Liquids)

- Groundboom Application

Grasses Grown for Seed 100 0.0376 0.000219 0.5 80 0.019 3100 0.00015 410000 3100

Sod 100 0.0376 0.000219 0.34 80 0.013 4500 0.000099 600000 4500

Sugarcane 100 0.0376 0.000219 0.31 80 0.012 5000 0.000091 660000 4900

Golf Course 100 0.0376 0.000219 0.17 40 0.0033 18000 0.000025 2400000 18000

Cereals 100 0.0376 0.000219 0.11 80 0.0043 14000 0.000032 1900000 14000

Mixer/Loader (Liquids)

- Chemigation

Grasses Grown for Seed 100 0.0376 0.000219 0.5 350 0.085 710 0.00064 94000 700

Sod 100 0.0376 0.000219 0.34 350 0.058 1000 0.00043 140000 1000

Sugarcane 100 0.0376 0.000219 0.31 350 0.053 1100 0.0004 150000 1100

Cereals 100 0.0376 0.000219 0.11 350 0.019 3200 0.00014 430000 3200

Mixer/Loader (Liquids)

- LCO Handgun Application

Turf 100 0.0376 0.000219 0.34 100 0.017 3600 0.00012 480000 3600

Mixer/Loader(Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Aerial Application

Sod 100 0.0098 0.00024 0.34 350 0.015 4000 0.00048 130000 600

Mixer/Loader (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Chemigation

Sod 100 0.0098 0.00024 0.34 350 0.015 4000 0.00048 130000 600

Mixer/Loader (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Groundboom Application

Sod 100 0.0098 0.00024 0.34 80 0.0034 17000 0.00011 550000 2600

Golf Course 100 0.0098 0.00024 0.17 40 0.00086 70000 0.000027 2200000 10000Page 40 of 68

Table 9.1.a . Short

- Term and Intermediate

- Term Occupational Handler Dermal and Inhalation Exposures

Crop Grouping Target MOE Dermal Unit Exposure (mg/lb ai) Inhalation Unit

Exposure (mg/lb ai) Application

Rate a Area Treated

Daily b PPE

- G Baseline Inhalation Total

PPE

- G Baseline (lb ai/A) (acres/day) Dermal Dose c (mg/kg/day) Dermal

MOE d Dose e MOE f MOE g

Mixer/Loader (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- LCO Handgun Application

Turf 100 0.0098 0.00024 0.34 100 0.0043 14000 0.00014 440000 2100

Mixer/Loader (Granules)

- Aerial Application

Sod 100 0.0069 0.0017 0.44 350 0.014 4400 0.0044 14000 3300

Mixer/Loader (Granules )

- Tractor Drawn Spreader Applications

Sod 100 0.0069 0.0017 0.44 80 0.0031 19000 0.001 60000 15000

Golf Course 100 0.0069 0.0017 0.17 40 0.00061 99000 0.00019 310000 75000

Applicator (Sprays)

- Aerial

Grasses Grown for Seed 100

-- -- 0.5 350

-- -- -- -- --

Sod 100

-- -- 0.34 350

-- -- -- -- --

Sugarcane 100

-- -- 0.31 350

-- -- -- -- --

Cereals 100

-- -- 0.11 350

-- -- -- -- --

Applicator (Sprays)

- Groundboom Equipment

Grasses Grown for Seed 100 0.0161 0.00034 0.5 80 0.0083 7200 0.00023 260000 7000

Sod 100 0.0161 0.00034 0.34 80 0.0057 11000 0.00015 390000 10000

Sugarcane 100 0.0161 0.00034 0.31 80 0.0052 12000 0.00014 430000 11000

Golf Course 100 0.0161 0.00034 0.17 40 0.0014 42000 0.000039 1600000 41000

Cereals 100 0.0161 0.00034 0.11 80 0.0018 33000 0.00005 1200000 32000

Applicator (Granules)

- Tractor Drawn Spreader Applications

Sod 100 0.0072 0.0012 0.44 80 0.0033 18000 0.0007 85000 15000

Golf Course 100 0.0072 0.0012 0.17 40 0.00063 95000 0.00014 440000 78000

Flagger (Liquids)

- Aerial Spray Application

Grasses Grown for Seed 100

-- 0.00035 0.5 350

-- -- 0.001 59000

--

Sod 100

-- 0.00035 0.34 350

-- -- 0.00069 86000 --

Sugarcane 100

-- 0.00035 0.31 350

-- -- 0.00063 95000

--

Cereals 100

-- 0.00035 0.11 350

-- -- 0.00022 270000

--Page 41 of 68

Table 9.1.a . Short

- Term and Intermediate

- Term Occupational Handler Dermal and Inhalation Exposures

Crop Grouping Target MOE Dermal Unit Exposure (mg/lb ai) Inhalation Unit

Exposure (mg/lb ai) Application

Rate a Area Treated

Daily b PPE

- G Baseline Inhalation Total

PPE

- G Baseline (lb ai/A) (acres/day) Dermal Dose c (mg/kg/day) Dermal

MOE d Dose e MOE f MOE g

Flagger (Granules)

- Aerial Application

Sod 100

-- 0.00015 0.44 350

-- -- 0.00039 160000

-- Mixer/Loader/Applicator (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Low Pressure Handwand Application

Edging/Banding 100

-- -- 0.68 0.023

-- -- -- -- --

Turf 100

-- -- 0.34 0.023

-- -- -- -- --

Golf Course 100

-- -- 0.17 0.023

-- -- -- -- -- Mixer/Loader/Applicator (Liquids)

- Backpack Sprayer Application

Edging/Banding 100 2.5 0.03 0.68 0.023 0.00051 120000 0.0000078 7700000 120000

Turf 100 2.5 0.03 0.34 0.023 0.00025 240000 0.0000039 15000000 230000

Golf Course 100 2.5 0.03 0.17 0.023 0.00013 480000 0.000002 31000000 470000

Mixer/Loader/Applicator (Liquids)

- Handgun Sprayer Application

Turf 100 0.45 0.0015 0.34 5 0.0099 6100 0.000043 1400000 6000

Golf Course 100 0.45 0.0015 0.17 5 0.0049 12000 0.000021 2800000 12000

Mixer/Loader/Applicator (Liquids)

- Low Pressure Handwand Applications

Edging/Banding 100 0.33 0.0027 0.68 0.023 0.000067 900000 0.0000007 85000000 890000

Turf 100 0.33 0.0027 0.34 0.023 0.000033 1800000 0.00000035 170000000 1800000

Golf Course 100 0.33 0.0027 0.17 0.023 0.000017 3600000 0.00000018 340000000 3600000

Mixer/Loader/Applicator (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Backpack Sprayer Application

Edging/Banding 100

-- -- 0.68 0.023

-- -- -- -- --

Turf 100

-- -- 0.34 0.023

-- -- -- -- --

Golf Course 100

-- -- 0.17 0.023

-- -- -- -- -- Mixer/Loader/Applicator (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Handgun Sprayer Application

Turf 100

-- -- 0.34 5

-- -- -- -- --

Golf Course 100

-- -- 0.17 5

-- -- -- -- -- Mixer/Loader/Applicator (Granules)

- Belly Grinder Application

Edging/Banding 100 9.3 0.062 0.88 0.023 0.0024 25000 0.000021 2900000 24000Page 42 of 68

Table 9.1.a . Short

- Term and Intermediate

- Term Occupational Handler Dermal and Inhalation Exposures

Crop Grouping Target MOE Dermal Unit Exposure (mg/lb ai) Inhalation Unit

Exposure (mg/lb ai) Application

Rate a Area Treated

Daily b PPE

- G Baseline Inhalation Total

PPE

- G Baseline (lb ai/A) (acres/day) Dermal Dose c (mg/kg/day) Dermal

MOE d Dose e MOE f MOE g

Turf 100 9.3 0.062 0.44 0.023 0.0012 49000 0.00001 5700000 49000

Golf Course 100 9.3 0.062 0.17 0.023 0.00047 130000 0.000004 15000000 130000

Mixer/Loader/Applicator (Granules)

- Push Type Spreader Application

Turf 100 0.22 0.0073 0.44 0.5 0.0063 9600 0.00027 220000 9200

Golf Course 100 0.22 0.0073 0.17 0.5 0.0024 25000 0.0001 580000 24000 a. Application Rates based on proposed labels.

b. Science Advisory Council Policy No. 9.1

c . Dermal Dose (mg/kg/day) = daily unit exposure (mg/ lb ai) x dermal absorption ( 7 5 .5 %) application rate (lb ai/acre or lb ai/gal) x acres or gallons treated / body weight (60 kg).

d . Dermal MOE = NOAEL ( 6 0 mg/kg/day) / dermal daily dose (mg/ kg/ day). Level of concern = 100.

e . Inhalation Dose (mg/kg/day) daily unit exposure (μg/ lb ai) x application rate (lb ai/acre or lb ai/gal) x acres treated or gallons treated / body weight (60 kg).

f . Inhalation MOE = NOAEL ( 6 0 mg/kg/day) / inhalation daily dose (mg/ kg/ day). Level of concern = 100.

g . Combined Dermal + Inhalation MOE = NOAEL ( 6 0 mg/kg/day) / Combined dermal + inhalation dose (mg/kg/day)

-- = Data Not Available or Liquids Exposure Scenario is considered protective of this scenarioPage 43 of 68

9.2 Occupational Post

- application

9.2.1 Occupational Post

- application Dermal

In the case of trinexpac

- ethyl , there is a potential for postapplication dermal exposure to field workers following fo liar applications of trinexpac

- ethyl to agricultural crops

. Chemical and

crop

- specific data relevant to post

- application exposure (i.e., dislodgeable foliar residue (DFR) data) for the new trinexpac

- ethyl proposed uses were not submitted. T herefore, derm al exposures during postapplication activities were estimated using dermal transfer coefficients from the Science Advisory Council for Exposure Policy Number 3 (http://www.epa.gov/pesticides/science/exposac_policy3.pdf). This policy reflects adoption of

a ll Agricultural Reentry Exposure Task Force (ARTF) data. Use of the data in this policy requires compensation to the ARTF under FIFRA.

In the absence of chemical

- specific DFR data, HED assumes that 20% of the initial application is
available for trans fer on day 0 ( i.e., 12 hours after application) and that the residue dissipate s at a rate of 10% per day. Furthermore, HED also assumes an 8 hour workday for post

- application
workers . Average d aily doses (ADD) were calculated on each post

- ap plication day after application.

Equations/Calculations: The assumptions, equations, and calculations used to determine occupational post

- application exposure and risk estimates are given in the ORE memo prepared in support of this registration action ( Monica Hawkins , D392798, 8/31/11).

The post

- application MOEs at day 0 range from 47 to 12,000. The results indicate that occupational post

- application risk estimate s, as calculated per HED default values, do not exceed HED’s level of concern (an MOE ≥ 100) on day zero after application for all post

- application tasks that were assessed except for hand

- harvesting sugarcane where the MOE increases to 110 within 8 days of application (short

- and intermediate

- term post

- application)

.

Table 9.2.a. Summary of Trinexapac

- ethyl Occupational Short

- Term and Intermediate

Term Post

- application Risk Estimate s Using Default Data

Crop Grouping Crop Exposure
Potential Max

Foliar

Rate (lb ai/ acre) Transfer
Coefficient (cm 2 /hr) Activities MOE

at Day

Zero Day Acceptable
MOE

Field/Row Crop (Low) Turf/Sod

(Golf Course) Low 0.17 3700 Maintenance 410

--

Field Row Crop (Low) Turf/Sod

(Sod) Low 0.34 0 Roll Harvesting

-- --

6700 Maintenance,

Slab Harvesting, Transplanting 110

--Page 44 of 68

Table 9.2.a. Summary of Trinexapac

- ethyl Occupational Short

- Term and Intermediate

Term Post

- application Risk Estimate s Using Default Data

Crop Grouping Crop Exposure
Potential Max

Foliar

Rate (lb ai/ acre) Transfer
Coefficient (cm 2 /hr) Activities MOE

at Day

Zero Day Acceptable
MOE

/ Planting

Field/Row Crop (Low/Medium) Sugarcane Low

0.31 0 Transplanting

-- --

70 Hand

Weeding 12000

--

High 0 Mechanical Harvesting,
Mechanical Weeding -- --

1100 Scouting 760

17600 Hand

Harvesting 47 8

Field/Row Crop (Low/Medium) Grasses

grown for
seed Low 0.5 0 Mechanical Harvesting, Fertilizing, Irrigation (non

- hand set) -- --

1100 Scouting 470

--

1900 Irrigation

(hand set) 270

--

Field/Row Crop (Low/Medium) Cereals Low 0.11 0 Irrigation (non

- hand set),
Mechanical Harvesting -- --

1100 Scouting 2100

--

Restricted Entry Interval: C urrent trinexapac

- ethyl labels have either no REI, 0 days, or a 4
hour REI. The trinexapac

- ethyl technical material has been classified in Toxicity Category III for acute dermal, oral, and primary eye irritation and Category IV for acute inhalation and primary skin irritation. Per the Worker Protection Standard (WPS), a 12

- hr restricted entry interval (REI) is required for chemicals classified under Toxicity Category III/IV. The

R egistration D ivision (RD) should ensure the proper REIs are put in place on the labels to
reflect these requirements

.

Based on HED’s occupational postapplication exposure assessment, REIs for hand

- harvesting sugarcane were estima ted to be 8 days for short

- and intermediate

- te rm exposure. However,
HED does not recommend that sugarcane REI’s be changed on the trinexapac

- ethyl labels at this
time based on two main issues. First , almost all sugarcane harvesting in the United States isPage 45 of 68

done mechanically. Secondly , the proposed t rinexapac

- ethyl labels have a 28

- day pre

- harvest interval (PHI) for sugarcane so hand harvesting should not occur until after 28 days which is protective of the estimated REIs

.

9.2.1 Occupational Post

- application Inhalation

Based on the Agency's current practices, a quantitative post

- application inhalation exposure

assessment was not performed for trinexapac

- ethyl at this time primarily because of the low acute inhalation toxicity (Toxicity Category IV). However, there are m ultiple potential sources of post

- application inhalation exposure to individuals performing post

- application activities in previously treated fields. These potential sources include volatilization of pesticides and resuspension of dusts and/or particulates that contain pesticides. The Agency sought expert advice and input on issues related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, and
received the SAP’s fin al report on March 2, 2010 ( http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html ). The Agency is in the process of evaluating the SAP report as well as available post

- application inhalation exposure data generated by the Agricultural Reentry Ta sk Force and may, as appropriate, develop policies and procedures, to identify the need for and, subsequently, the way to incorporate occupational
post

- application inhalation exposure into the Agency's risk assessments. If new policies or procedures are p ut into place, the Agency may revisit the need for a quantitative occupational
post

- application inhalation ex posure assessment for trinexapac

- ethyl

.

Although a quantitative occupational post

- application inhalation exposure assessment was not performed, an inhalation exposure assessment was performed for occupational handlers. Handler exposure resulting from application of pesticides outdoors is likely to result in higher exposure than post

- application exposure. Therefore, it is expected that these handler inhalation exposure estimates would be protective of most occupational post

- application inhalation exposure scenarios.

10.0 References

DP#: 378491, 328850, 328853, 328898 Subject: Trinexapac

- ethyl: Application for Sect ion 3 Registration for Use on Cereal Grains

and Sugarcane (PP#0F7720) and Grasses Grown for Seed ( PP# 0F7719). Summary of Analytical Chemistry and Residue Data.

From: S. Piper

To: B. Benbow and K. Montague

Date: 11/2 3 /11

MRIDs: 48043701

- 09, 47101606, 47101603, 48043601

- 04, 45898901

- 09, 46809305

- 06Page 46 of 68

DP#: 394830 Subject: Trinexapac

- ethyl: Acute and Chronic Dietary Exposure and Risk Assessment for

Proposed Uses on Cereal Grains, Sugarcane and Grasses Grown for Seed.

From: S.Piper

To: B. Benbow and K. Mo ntague
Date: 10/28 / 11

MRIDs: NA

DP#: 390121 Subject: Trinexapac

- ethyl : Report of the Residues of Concern Knowledgebase

Subcommittee (ROCKS).

From: E. Holman

To: Trinexapac

- Ethyl Risk Assessment Team

Date: 07/05/11

MRIDs: NA

DP#: 392798 Subject: Trinexapac

- ethyl: Occupational and Residential Exposure/Risk Assessment for

Proposed Uses on grasses grown for seed, sugarcane, and cereals (wheat, barley, and oats)

. From: M. Hawkins

To: M. Waller / T. Stowe

Date: 08/31/11

MRIDs: NA

DP#: 395601 Subject: Tier II Drinking Water Assessment for Trinexapac

- Ethyl use on Turf

From: C. M. Koper

To: B. Benbow and S.Piper

Date: 10 / 28 /11

MRIDs: NAPage 47 of 68



### Appendix A: Toxicology Profile and Executive Summaries

A.1 Toxicology Data Requirements
The requirements (40 CFR 158.340) for a food use for trinexapac

- ethyl are in Table 1 below. Use of the new guideline numbers does not imply that the new (1998) guideline protocols were
used. A description of the outstanding study is in Table A. 2. 1.

Table A. 1. Toxicology Data Requirements

Test Technical Required Satisfied

870.1100 Acute Oral Toxicity

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

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

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

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

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

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

yes

yes

yes

yes

yes yes

yes

yes

yes

yes

yes

870.3100 Oral Subchronic (rodent)

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

................................ ........ 870.3200 21/28

- Day Dermal

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

- Day Dermal

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

- Day Inhalation

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

yes

yes

no

no yes

yes

yes

---

---

870.3700a Developmental Toxicity (rodent)

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

............................ 870

- 3800 Reproduction

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

yes

yes yes (83

- 3a)

yes (83

- 3b) yes (83

- 4)

870.4100a Chronic Toxicity (rodent)

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

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

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

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

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

yes

yes

yes

yes yes

yes

yes

yes

yes

870.5100 Mutagenicity

— Gene Mutation

- bacterial

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

— Gene Mutation

- mammalian

............... 870.5375 Mutagenicity

— Structural Chromosomal Aberrations

.. 870.5395 Mutagenicity

— Other Genotoxic Effects

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

yes

yes

yes yes

yes

yes

yes
870.6100a Acute Delayed Neurotox. (hen)

................................ ..... 870.6100b 90

- Day Neurotoxicity (hen)

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

....................... 870.6200b 90 Day Neurotox. Screening Battery (rat)

.................... 870.6300 Develop. Neurotoxicity

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

no

yes

yes CR ---

---

no

no

no

870.7485 General Metabolism

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

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

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

no

yes yes

yes

no Non guideline Thyroid MOA Investigation Study No

--- CR=pending results of acute and subchronic neurotoxicity studies

.Page 48 of 68

A.2 .1 Toxicity Profiles Table A.2.1. Acute Toxicity Profile of Trinexapac

- ethyl (97%).

Guideline

No. Study Type MRID Results Toxicity Category

870.1100 Acute oral [rat] 4156390

1 ♂ LD 50 = 4613 mg/kg

♀ LD 50 = 4212 mg/kg
Combined LD 50 = 4458 mg/kg III

870.1200 Acute dermal [rabbit] 4156391
0 LD 50 > 4000 mg/kg III

870.1300 Acute inhalation [rat] 4156391

2 LC 50 ≥ 5.3 mg/L IV

870.2400 Acute eye irritation

[rabbit] 4156391

4 Minimal irritant; cleared by 72

hours III

870.2500 Acute dermal irritation

[rabbit] 4156391

6 Slightly irritating; cleared by

day 7 IV

870.2600 Skin sensitization [guinea

pig] 4186952

2 Not a dermal sensitizer N/A

Table A.2.2 Acute Toxicity Profile

- – Vision TM Formulation (23% Trinexapac

- ethyl)

Guideline

No. Study Type MRID(s) Results Toxicity Category

870.1100 Acute oral rat] 41563909 LD 50 = 4514 mg/kg (both sexes) III

870.1200 Acute dermal [rabbit] 41563911 LD 50 >2020 mg/kg III

870.1300 Acute inhalation [rat] 41563913 LC 50 = > 0.912 mg/L III

870.2400 Acute eye irritation [rabbit] 41563915 severe irritant I

870.2500 Acute dermal irritation [rabbit] 41563916 moderate irritant III

870.2600 Skin sensitization [guinea pig] 41869519

41869521 not a dermal sensitizer N/A

Table A.2.3 Acute Toxicity Profile

– Primo TM Formulation (12% Trinexapac

- ethyl )

Guideline

No. Study Type MRID(s) Results Toxicity Category

870.1100 Acute oral rat] 41869514 LD 50 = 5010 mg/kg (males)

LD 50 = 5730 mg/kg (females) IV

870.1200 Acute dermal [rabbit] 41869515 LD 50 >2020 mg/kg III

870.1300 Acute inhalation [rat] 41869516 LC 50 = > 0.888 mg/L III

870.2400 Acute eye irritation [rabbit] 41869517 moderately irritating ; corneal involvement, conjunctival
irritation did not clear within 7 days II

870.2500 Acute dermal irritation [rabbit] 41869519 slightly irritating IV

870.2600 Skin sensitization [guinea pig] 41869522 not a dermal sensitizer N/APage 49 of 68

Table A.2.4. Subchronic, Chronic and Other Toxicity Profile of Trinexapac

- ethyl.

Guideline No./ Study Type MRID No. (year)

Classification /Doses Results

870.3100
90

- Day oral toxicity [rat] MRID 41563921 (1989)

0, 5, 50, 500, 5000, 20000 ppm [males 0, 3, 34, 346, 1350 mg/kg/day] [females 0, 4, 38, 395, 1551 mg/kg/day] acceptable/guideline NOAEL = 20000 ppm [males 1350/females 1551 mg/kg/day

HDT

870.3150

13

- week oral toxicity in nonrodent (dog)

7

- week pilot study MRID 41563920 ( 1989 )

0, 50, 100, 15000, 30000 ppm [males 0, 2.0, 34.9, 515.9, 927.1 mg/kg/day] [females 0, 1.9, 38.8, 582.4, 890.8 mg/kg/day]

acceptable/guideline
MRID 41869523 0, 500, 5000, 15000

- 50000 ppm [males 0, 22, 219, (686, 956, 734)* mg/kg/day] [females 0, 23, 214, ( 680, 1373, 965)* mg/kg/day] *15000 ppm (days 1

- 3); 30000 ppm (days 4

- 28); 50000 ppm (weeks 4

- 7) NOAEL = 15000 ppm [males 515.9/females 582.4 mg/kg/day LOAEL = 30000 ppm [males 927.1/females 890.8 mg/kg/day, based on clinical signs (few feces and
emaciati on) decreased BWG/FC/FE in both sexes (related to lack of palatability) and diffuse thymic atrophy

Negative BWG in males HDT from week 5 on; HDT females from week 6 on; BW of HDT males 81% of control/females 74% control at week 7; severe
decrease in food consumption HDT; tubular dilatation and degeneration/regeneration of epithelial cells of renal tubules at HDT; diffuse thymic atrophy at mid

and high

- dose females and high

- dose males

870.3200

21/28

- Day dermal toxicity (rabbit) MRID 41563922 (1989)

[46809310 (2006)] 0, 10, 100, or 1000 mg/kg/day,

acceptable/guideline Systemic toxicity NOAEL: 1000 mg/kg/day
LOAEL: Not determined
Local dermal irritation NOAEL: 10 mg/kg/d LOAEL: 100 mg/kg/d based on hyperkeratosis and subacute lymphocytic

inf iltrates in the skin

83

- 3a
Prenatal developmental in rodent [rat] MRID 41563923 (1988)

0, 20, 200, 1000 mg/kg/day gestation days 6

- 15

Acceptable/guideline; (does not
fulfill 870.3700a because study

pre

- dates this 1998 guideline) Maternal NOAEL = 1000 mg/kg/day, highest dose
tested Developmental NOAEL = 200 mg/kg/day Developmental LOAEL = 1000 mg/kg/day, based on increased incidence of asymmetrically

- shaped
sternebrae

Note: Performed under the old protocol guideline 83

- 3a.

83

- 3b
Prenatal developmental in
nonrodent MRID 41869524 (1990)

0, 10, 60, or 360 mg/kg/day gestation days 7

- 19 Materna l toxicity NOAEL = 360 mg/kg/day, highest
dose tested Developmenta l toxicity NOAEL = 60 mg/kg/day Developmental toxicity LOAEL

based on a decrease in the mean number ofPage 50 of 68

Table A.2.4. Subchronic, Chronic and Other Toxicity Profile of Trinexapac

- ethyl.

Guideline No./ Study Type MRID No. (year)

Classification /Doses Results

(rabbit)
Acceptable/guideline; (does not

fulfill 870.3700b because study

pre

- dates this 1998 guideline) fetuses/litter and an increase in post

- implantation loss

Note: Performed under the old protocol guidel ine 83

- 3b.

83

- 4 Reproduction and fertility effects (rats) MRID 43128604 (1991)

0, 10, 1000, 10000, 20000 ppm [P0 males: 0, 0.59, 59.97, 595.26, 1169.16 mg/kg/day] [P0 females: 0, 0.75, 74.84, 736.89, 1410.08 mg/kg/day]

F1 males: 0, 0.59, 59.10, 591.76, 1254.96 mg/kg/day]

F1 females 0, 0.77, 77.17, 765.20, 1559.65 mg/kg/day]

Acceptable/guideline; (does not
fulfill 870.3800 because study

pre

- dates this 1998 guideline) Parental toxicity NOAEL = 10000 ppm [males 593.5/females 751.1 mg/kg/day]
Par ental toxicity LOAEL 20000 ppm [males 1212.1/females 1484.9 mg/kg/day], based on reduced premating and gestation body weight/body

- weight gain and food consumption Reproductive NOAEL = 20000 ppm [males 1212/females 1484 mg/kg/day]. No adverse treatment

rel ated effect on reproductive parameters up to and including 20000 ppm (HDT) Offspring NOAEL = 10000 ppm [males 593.5/females 751.1 mg/kg/day] Offspring LOAEL = 20000 ppm [males 1212.1/females 1484.9 mg/kg/day], based on decreased F1 postnatal survival and reduced pup body weights in both generations [both sexes].

Note: Performed under the old protocol guideline 83

- 4. Developmental milestone data (age of vagina l opening and preputial separation; anogenital distance for F2 pups); assessment of implantations sites; estrous cycle length and periodicity (F1 weanlings); and sperm measures were not included in this study.

870.4100a Chronic toxicity rodents (rat) MRID 42238104 (1992)

0, 10, 100, 3000, 10000, 20000

ppm M 0, 0.38, 3.87, 115.6, 392.7, 805.7 mg/kg/day F 0, 0.49, 4.88, 147.4, 494.0, 1054 mg/kg/day
acceptable/guideline Systemic toxicity NOAEL = 20000 ppm [males 806/females 1054 mg/kg/day, highest dose tested.

870.4100b Chronic toxicity nonrodent (dogs) MRID 42779402/42779401

(1991

- 92) 0, 40, 1000, 10000, or 20000 ppm

[males 0, 1.56, 31.62, 356.72, or 726.65 mg/kg/day]

[females 0, 1.37, 39.54, 357.13, 783.83 mg/kg/day]

acceptable/guideline Systemic toxicity NOAEL = 1000 ppm [males 31.62/females 39.54 mg/kg/day Systemic toxicity LOAEL = 10000 ppm [males 365.72/females 357.13 mg/kg/day], based on elevated serum cholesterol values in females, mucoid feces in females and bloody feces in both se xes, and minimal, focal vacuolation of the dorsal medial hippocampus
and/or lateral midbrain in both sexes.

870.4200 MRID 42238104 (1992) see above under 870.4100aPage 51 of 68

Table A.2.4. Subchronic, Chronic and Other Toxicity Profile of Trinexapac

- ethyl.

Guideline No./ Study Type MRID No. (year)

Classification /Doses Results

Carcinogenicity (rat)
Sprague

- Dawley 0, 10, 100, 3000, 10000, 20000

ppm M 0, 0.38, 3.87, 115.6, 392.7,
805.7 mg/kg/day F 0, 0.49, 4.88, 147.4, 494.0, 1054 mg/kg/day

acceptable/guideline There was a possible treatment related increased incidence of squamous cell carcinoma of the forestomach in M at 20000 p pm (HDT); however, this
is no t considered toxicologically relevant to humans.

No treatment

- related difference detected in total
number
of animals with tumors or in the total number of benign or malignant tumors at 52 or 104 weeks. No

treatment

- related effect on the time

- dependent

occ urrence of tumor

- bearing animals.

Not Likely to be Carcinogenic to Humans

870.4300 Carcinogenicity (mouse)
CD

- 1 [Crl:CD

- 1 (ICR)Br] MRID 43128603 (1991)

0, 7, 70, 1000, 3500, 7000 ppm [males 0, 0.91, 9.01, 130.81, 450.72, 911.77 mg/kg/day] [females 0, 1.08, 10.66, 154.08, 538.73, 1073.42 mg/kg/day]

acceptable/guideline Systemic toxicity NOAEL = 7000 ppm [males 911/females 1073 mg/kg/day], the highest dose tested.

There was no treatment

- related increase in tumors of any type in either sex at dose levels up to an including 7000 ppm, the HDT

Not Likely to be Carcinogenic to Humans

870.5100
Bacterial

Reverse Gene Mutation Assay 46809308 (2001)

Salmonella typhimurium strains TA98, TA100, TA102,
TA1535 and TA1537
Escherichia coli strain WP2 uvr A

0, 312.5, 625, 1250, 2500, or 5000 μg/plate ± S9 metabolic activation

Acceptable/guideline Negative acceptable/guideline

870.5300

Mouse Lymphoma
Cells/Mammalia
n Activation
Gene Forward Mutation Assay

at TK +/

- locus 43128605 (1993

Mouse lymphoma L5178Y cells (at the thymidine kinase locus) 0, 7.54, 30.16, 120.62, or 1930 μg/mL for 4 hours
± S9 metabolic activation Negative acceptable/guideline

870.5395
Structural
chromosomal
aberration test

- Micronucleus 41563926 (1989)

42081402 (1991) 41869527 (1991)
M and F mouse bone marrow cells (erythrocytes) 0, 1000, 2000, or 4000 mg/kg bw Negative acceptable/guideline

Significant increased frequency of micronucleated polychromatic erythrocytes in M and sexes combined at 48 h in the initial assay; however, values were within historical control range and not observed in thePage 52 of 68

Table A.2.4. Subchronic, Chronic and Other Toxicity Profile of Trinexapac

- ethyl.

Guideline No./ Study Type MRID No. (year)

Classification /Doses Results

Test Mouse (sacrifice at 16, 24, and 48 h)

Initial assay: 0 or 3000 mg/kg bw (sacrifice at 16, 24, and 48 h) Confirmatory assay: 0, 750, 1500, or 30 00 mg/kg bw (sacrifice at 48 h) confirmatory assay at 3000 mg/kg bw at 48 h . In this study possible weak clastogen, however, weight of evidence suggests

CGA

- 163935 not likely clastogenic.

870.5550
Other Genotoxicity

In vitro UDS in Primary Rat Hepatocytes 41604205 (1987)

41869528 (1991)
Preliminary cytotoxicity assay: 0, 5, 10, 21, 41, 82, 164, 328, 656, 1313, 2625, or 5250 μg/mL Initial UDS assay: 0, 0.8, 4, 20, 100, 200, or 400 μg/mL; Confirmatory UDS assay: 0, 4, 20, 100, 150, 200, 300, 400, or 500 μg/ mL Negative acceptable/guideline

870.7485
Metabolism and pharmacokinetic

s (rat) MRID 41563927 (1990 )

i. v. 0.91 mg/kg [ 14 C

- CGA

163935] oral 0.97 or 166 mg/kg [ 14 C

- CGA

163935] oral 0.97 mg/kg/day [CGA

163935] for 14 days followed by 0.97 mg/kg [ 14 C

- CGA

- 163935] acceptable/guideline Rapidly, extensively absorbed (both sexes) w/ >95% of administered dose being absorbed; little potential for accumulation; >85% eliminated w/in 12 hours via urine; 2% via feces w/in 24 hours; very little or no biliary e xcretion; no sex difference; free acid derivative resulting from hydrolysis of the ester bond of parent compound is major component in urine and feces; only other component was parent, found only in
feces.

870.7600
Dermal penetration

(rat) MRID 42238105 (1990)

0, 0.01, 0.1, or 1.0 mg/cm 2 [ 14 C

CGA

- 163935] single dermal dose
acceptable/guideline Recovery of applied dose 97%

- 117%; most recovered in skin washes and urine; <1% in blood and feces;
excreted in urine within 2 hours of dose

56.5% absorbed, wit h 21% associated with application
site
dermal absorption factor 77.5% based on 10 hour exposure regimen.

870.7 8 00 Immunotoxicity study (mice ) MRID 4 8444101 ( 2011 )

0, 500

, 2000

, and 5000 ppm 0,160.2, 613.7, 1530.5 mg/kg/day acceptable/guideline Systemic toxicity NOAEL = 5000 ppm (1530.5 mg/kg/day, the highest dose tested) the LOAEL was not established. The immunotoxicity NOAEL for anti

- SRBC AFC response and NK cell activity is 5000 ppm (1530.5 mg/kg/day), the LOAEL was not established

.Page 53 of 68

Table A.2.5. Structures of Trinexapac

- ethyl Major Metabolites and Degradates

Code Name Chemical Abstracts Name

(IUPAC Name) Structure

Trinexapac

ethyl ethyl 4

(cyclopropylhydroxymethylene)

- 3,5

- dioxocyclohexanecarboxylate

Trinexapac

(CGA

179500) 4

- (cyclopropylhydroxymethylene)

- 3,5

-

dioxocyclohexanecarboxylic acid

CGA 113745 3,5

- dioxo

- cyclohexanecaroxylic acid

Aconitic acid

CGA 312753 (1E)

- prop

- 1

- ene

- 1,2,3

- tricarboxylic

acid

Tricarboxylic
acid

CGA

- 275537 propane

- 1,2,3

- tricarboxylic acid

CGA

- 313458 2

- (4

- Cyclopropyl

- 2,4

- dioxo

- butyl)

-

succinic acidPage 54 of 68

Table A.2.5. Structures of Trinexapac

- ethyl Major Metabolites and Degradates

Code Name Chemical Abstracts Name

(IUPAC Name) Structure

Open chain cyclohexane degradate

A.3 Hazard Identification and Endpoint Selection

A.3.1 Acute Reference Dose (aRfD)

- Females age 13

- 49 Study Selected: Prenatal Developmental Toxicity Study

– rabbit
MRID No.: 41869524 Summary : See Appendix A, Guideline 83

- 3 Dose and Endpoint for Risk Assessment: NOAEL = 60 mg/kg, based on a decrease in the mean number of fetus/litter and an increase in post

- implantation loss at the developmental toxicity LOAEL of 360 mg/kg/day. Uncertainty Factor(s): 100X [10 interspecies; 10X intraspecies] FQPA SF = 1X, UF DB = 1X. Comments about Study/Endpoint/Uncertainty Factor : The route and duration of exposure are

approp riate for selection of the acute dietary endpoint for females 13

- 49 years old . The toxicity could occur following a single exposure and is appropriate for this exposure scenario. This endpoint will be protective of the fetal effects [increased incidence of asymmetrical sternebrae] observed at higher dose levels [1000 mg/kg/day] in the rat. This is a conservative endpoint since this is such a large dose spread (the NOAEL is 6

- fold lower than LOAEL).

aRfD = aPAD = 60 mg/kg/day = 0.60 mg/kg/day

100

A.3.2 Acute Reference Dose (aRfD) general population

An acute reference dose was not defined; no effects attributable to a single dose were identified in the toxicology database. An in utero effect from the developmental rabbit study provided an
acute reference dose for females 13

- 49 yrs old but is not appropriate for the general population.

A.3.3 Chronic Reference Dose (cRfD)

Study Selected: chronic oral toxicity

- dog
MRID No.: 42779402/42779401Page 55 of 68

Executive Summary : See Appendix A, Guideline 870.4100 b Dose and Endpoint for Risk Assessment: NOAEL = 1000 ppm [males 31.6 mg/kg/day; females 39.5 mg/kg/day], based on elevated serum cholesterol values in females, mucoid feces in
femal es and bloody feces in both sexes, and minimal, focal vacuolation of the dorsal medial hippocampus and/or lateral midbrain in both sexes at the LOAEL of 10000 ppm [ males 365.72/females 357.13 mg/kg/day]

. Uncertainty Factor(s): 100X [10 interspecies; 10X in traspecies] FQPA SF = 1X, UF DB = 1X. Comments about Study/Endpoint/Uncertainty Factor : The route and duration of exposure are appropriate for selection of the chronic dietary endpoint. This endpoint is protective since the dog is the most sensitive species, there is a large dose spread in the chronic dog study (the
NOAEL is 10

- fold lower than the LOAEL), and there is a clear NOAEL and LOAEL. The
vacuolation was also observed in all of t he dogs at the high dose level (males 727 mg/kg/day /females 784 mg/kg/day) and was associated with the astrocytes and oligodendrocytes in the hippocampus . The lesions remained confined to the supporting cells in the CNS and did not progress to more advanc ed or more extensive damage of the nervous tissue. The lesions were not associated with other neuropathological findings or overt neurological signs. Similar microscopic lesions in the brain were not reported in the 90

- day dog study, but there was an incon sistency in the level of screening of the brain, which precludes a definitive determination on the occurrence of this lesion following subchronic exposure. Similar lesions were not observed in the rat (including neonates) or mouse following subchronic or c hronic dietary exposure, and there was no other evidence in any other species tested to indicate a neurotoxicity potential.

cRfD = cPAD = 31.6 mg/kg/day = 0.32 mg/kg/day

100

A.3.4 Incidental Oral Exposure (Short

- and intermediate Term)

Study Selected :

– No appropriate endpoint was available for the incidental oral exposure

A.3.5 Dermal and Inhalation Exposure (Short and IntermediateTerm

- Adults only Study Selected: Prenatal Developmental Toxicity Study

– rabbit
MRID No.: 41869524 Summary : See Appendix A, Guideline 83

- 3 Dose and Endpoint for Risk Assessment: NOAEL = 60 mg/kg, based on a decrease in the mean number of fetus/litter and an increase in post

- implantat ion loss at the developmental toxicity LOAEL of 360 mg/kg/day. Uncertainty Factor(s): LOC for MOE =100. 100X [10 interspecies; 10X intraspecies] FQPA SF = 1X, UF DB = 1X. Comments about Study/Endpoint/Uncertainty Factor : The developmental toxicity study in rabbits (an oral study) is selected for the short and intermediate

- term dermal and inhalation exposure scenarios for adults only . This endpoint is protective of female workers that may become pregnant while exposed to trinexacpac

- ethyl. The chronic dog study was also considered since it has a similar LOAEL (357 mg/kg/day). The NOAELs established in these two studies, however, is 2

- fold different due to the dose

- spread in the two studies. Therefore, the higher NOAEL of 60 mg/kg/day from the rabbit devel opmental study (LOAEL 360 mg/kg/day) is protective of the effects observed (LOAEL 357 mg/kg/day) in the chronic dog study withPage 56 of 68

NOAEL pf 31.6 mg/kg/day. While we recognize that this endpoint is most appropriate for pregnant adults and not applicable to chil dren and men, it is, nonetheless, protective of these two populations which have effects at higher doses. Although there is a 21

- day dermal toxicity study in rabbits that did not identify adverse systemic effects at the limit dose of 1 000 mg/kg/day, it di d not evaluate the developmental effects on the fetus (decreased number of fetuses/litter and increased post

- implantation loss).

Dermal irritation was observed in the dermal toxicity study at 100 mg/kg/day (NOAEL = 10 mg/kg/day) , however, this was not re lied upon for use in risk assessment because of the transient nature of irritation. The Agency prefers to preclude irritation through p roduct labeling and the
use of gloves and/or other clothing to minimize dermal contact. The proposed endpoint, however, will protect for irritation for children playing on the lawn. If a dermal absorption factor of 77.5% is applied to the developmental NOAEL of 60 mg/kg/day, the derived dermal equivalent dose (DED) would be 77.4 mg/kg/day. This endpoint will also be p rotective of the fetal effects ( increased incidence of asymmetrical sternebrae) obser ved at higher oral dose levels (1000 mg/kg/day) in the rat. Note: While the idea of separate endpoints for pregnant women and children were discussed, it was decided that this was not necessary. The point of departure based on the developmental rabbit study would be protective of the potential impact of children’s dermal exposure to trinexapac

- ethyl since the dermal NOAEL for children would be higher than for pregnant wom en (594 mg/kg/day vs . 60 mg/kg/day, respectively).

The inhalation exposure limit is based on the NOAEL from an oral toxicity study for this exposure scenario, since no route

- specific study is available. In the absence of inhalation absorption data, toxici ty by the inhalation route was considered to be equivalent to toxicity by the oral route of exposure.

Based on use pattern, long term exposures are not expected

.

A.4 Executive Summaries

Subchronic Rat

In a subchronic oral toxicity study [MRID 41563921], 15 Sprague

- Dawley [Crl:VAF/Plus CD® rats/sex/dose were administered CGA 163935 Technical [96.9%] via the diet at concentrations of 0 ppm, 50 ppm, 500 ppm, 5000 ppm, or 20000 ppm for 13 consecutive weeks . The mean daily intakes were 3, 34, 346, or 1350 mg/kg/day for males and 4, 38, 395, or 1551 mg/kg/day for females, respectively.

There was no adverse effect of treatment on survival, and no apparent treatment

- related clinical signs of toxicity. At 2000 0 ppm, both sexes displayed slight decreases in body weight throughout most of the study [93%

- 94% of control at study termination], and overall body

- weight gains were reduced in both sexes [males 93%/females 89% of control]. Both sexes at the 20000 ppm
do se level displayed decreased food consumption throughout the study, with the largest deficit occurring initially suggesting a palatability problem.Page 57 of 68

There were no treatment

- related ocular changes in either sex. There were no apparent, treatment

related ef fects on the hematology or clinical chemistry parameters monitored in either sex. The urinalysis assessment found decreased urinary pH values in both sexes at 20000 ppm.
There were no treatment

- related effects on organ weights in either sex. There was an increased incidence of renal tubular changes [basophilia (3, 2, 1, 7, 13***), hyaline droplets (5, 7, 7, 11*, 13**), casts (2, 2, 0, 2, 6), with increasing dose] in males at 5000 ppm and 20000 ppm, which was said to represent a shortened time of onset of s pontaneous senile nephropathy, a common condition in aging rats. However, based on the fact that the incidence of senile nephropathy was comparable among the male groups in the chronic rat study at dose levels up to 20000 ppm for
104 weeks indicates that t hese findings should not be considered adverse.

The systemic toxicity NOAEL is 20000 ppm [males 1350 mg/kg/day; females 1551 mg/kg/day], the highest dose tested.

This guideline subchronic oral toxicity study is classified ACCEPTABLE , and it satisfies th e guideline [OPPTS 870.3100; §82

- 1] for a subchronic oral toxicity study in the rat. COMMENT: The original DER identified a no observed effect level [NOEL], which was based on the renal tubular changes in the males at 5000 ppm [346 mg/kg/day] and 20000 pp m [ 1350 mg/kg/day]

.

Subchronic Dog

In a subchronic oral toxicity study [MRID 41563920], 4 beagle dogs/sex/dose were administered CGA 163935 Technical [96.9%] via the diet at concentrations of 0 ppm, 50 ppm, 1000 ppm, 15000 ppm, or 30000 ppm for 13 consecutive weeks. The mean daily intakes were 2.0, 34.9, 515.9, or 927.1 mg/kg/day for males and 1.9, 39.8, 582.4, or 890.8 mg/kg/day for females receiving 50, 1000, 1 5000, or 30000 ppm, respectively.

There was no adverse effect of treatment on survival, and no apparent treatment

- related clinical signs of toxicity other than few feces and emaciation. Both sexes at the 30000 ppm dose level displayed decreased food cons umption throughout the study and, consequently, body weights [males 74%/females 88% of control at termination] and body

- weight gains [negative weight gain compared to control (males

– 0.325 kg vs 1.775 kg (control)/females

– 0.075 kg vs 1.225 kg (control)] w ere decreased throughout the study also.

There were no treatment

- related ocular changes in either sex. There were no apparent, treatment

related effects on the hematology, clinical chemistry, or urinalysis parameters monitored in either

sex.

The treatme nt

- related effects on most organ weights in both sexes at the 30000 ppm dose level are considered to be changes that would be expected due to decreased body weight/body

- weight gain. Both sexes at the 30000 ppm dose level displayed decreased popliteal lymph node weights [absolute and relative

- to

- brain]. Non

- significant decreases in thymic weight were reported in males at 30000 ppm. No other treatment

- related organ

- weight effects were reported in either sex.Page 58 of 68

Diffuse thymic atrophy was observed in all dogs [ both sexes] at the 30000 ppm dose level compared with none of the controls [either sex]. Focal thymic atrophy was not observed at the 30000 ppm dose level but was observed in 3 of the 4 male controls (2

- 3 males in all other groups) and all of the female co ntrols (2

- 3 females in all other groups). It was noted that the diffuse thymic atrophy observed at 30000 ppm most likely occurred secondary to the nutritional imbalances related to reduced food consumption and body

- weight loss.

The systemic toxicity NO AEL is 15000 ppm [males 515.9 mg/kg/day; females 582.4 mg/kg/day], based on clinical signs (few feces and emaciation), decreased body weight/body

- weight gain, and decreased food consumption in both sexes (related to the lack of palatability) and diffuse th ymic atrophy at the systemic LOAEL of 30000 ppm [males 927.1 mg/kg/day; females 890.8 mg/kg/day].

This guideline subchronic oral toxicity study is classified ACCEPTABLE, and it satisfies the guideline [OPPTS 870.3150; §82

- 1] for a subchronic oral toxicity study in the dog.

NOTE: In the original DER, the subchronic oral toxicity study in the dog was c lassified Supplementary, pending the submission of the 7

- week pilot study for justification of the dose
levels selected.

In a 7

- week pilot study [MRID 41869523], beagle dogs [3/sex/group] were administered CGA 163935 technical (96.6%) via the diet at leve ls of 0, 500, 5000, 15000, or 15000

- 50000 ppm. At the highest dietary level, dogs were fed 15000 ppm for 3 days, 30000 ppm from day 4 to 28, and 50000 ppm from day 29 to 49. During the first 4 weeks of the 7

- week pilot study, males at the highest dose leve l gained 42% less body weight than the control, and females at this dose level gained 12% less than control. During the week 4 to week 5 interval, both sexes at the highest dose level displayed a negative body

- weight gain [males

- 0.80 kg/females

– 0.76 kg] compared to the positive body

- weight gains in the controls [males 0.3 kg/females 0.23 kg] and other dose groups [males 0.07 kg to 0.13 kg/females 0.03 kg to 0.13 kg]. At study termination, decreased body weight/negative body

- weight gains were observed at t he highest dose level in both sexes [males 82% of control/

- 0.54kg; females 74% of control/

- 0.43 kg]. Food consumption was decreased throughout the study in both sexes at the highest dose level [males 68% and 30% of control; females 89% and 34% of control d uring weeks 1

- 4 and 4

- 7, respectively]. No apparent adverse effects were observed in hematology, clinical chemistry, or urinalysis parameters monitored. Absolute and relative thymus weights were decreased in females at the highest dose level [14.5 g vs 3.4 g] only. In the kidney, tubular dilatation and tubular degeneration/regeneration were observed in all dogs/both sexes at the highest dose level compared to none in the control or other dose groups. Diffuse thymic atrophy was observed in all dogs/both sexe s at the highest dose level and in 2 of 3 females at 15000 ppm. Due to the (1) lack of palatability of the test material, (2) refusal of the dogs to eat diets containing greater than 30000 ppm of the test material, and (3) severe weight losses at 50000

pp m during weeks 4

- 7, it was concluded that 50000 ppm was too excessive for use in the subchronic (13 week) study. The average daily compound intake was 22.2, 218.7, 685.8, 956.2, and 733.6 mg/kg/day for males and 23.1, 214.3, 679.9, 1373.3, and 964.7 mg/kg/ day for females at the 500 ppm, 5000 ppm, 15000 ppm, 30000 ppm, and 50000 ppm dose levels, respectively.Page 59 of 68

The dose levels used in the subchronic study are considered adequate [30000 ppm], based

on the 7

- week pilot study [MRID 41869523; HED Document No. 00 9711].

Comment : Microscopic evidence of minimal, focal vacuolation of the dorsal medial hippocampus and/or lateral midbrain in all dogs at 20000 ppm and in one male and two female dogs at 10000 ppm was observed in the one year dog study. Although similar microscopic lesions in the brain were not reported in this 90

- day study in dogs, there was an inconsistency in the level of sectioning of the brain [MRID 42779401] in the subchronic study, which precludes a
definitive determination of the occurrence of th ese lesions following subchronic exposure. However, the chronic study identifies a NOAEL for these lesions [1000 ppm [males 31.6/females 39.5 mg/kg/day], which were observed at the LOAEL of 10000 ppm [males 366/females 357 mg/kg/day].

21

- Day Rabbit Dermal Toxicity Study

In a repeat dermal toxicity study [MRID 41563922], 5 New Zealand white rabbits/sex/dose were administered CGA 163935 Technical [96.6%] via dermal application at dose levels of 0 (unt reated), 0 (vehicle: de hydrated alcohol), 10, 100, or 100 0 mg/kg/day for at least 21 consecutive days. There was no adverse effect of treatment on survival, and no apparent treatment

- related clinical signs of toxicity. There were no treatment

- related, adverse effects on body weight, body

- weight gain, or food co nsumption in either sex.

There were no treatment

- related effects on any of the hematology parameters monitored in either sex. There were no apparent, treatment

- related, consistent, adverse effects on the clinical chemistry parameters monitored in either s ex, although several statistically

- significant trends were noted at 100 mg/kg/day and 1000 mg/kg/day. For example, decreased mean total bilirubin was observed in both sexes on day 21, but there was no dose response. Higher albumin/globulin
ratios were obse rved at termination in both sexes compared to both control groups, but statistical significance was not attained in females and a dose response was not observed in males.
There were no treatment

- related effects on organ weights in either sexes. Microscopi c evaluation of the liver, kidney, and lungs did not reveal any treatment

- related effects in either sex.
There was a dose

- related increase in gross lesions [dark, red or tan] of the treated skin, including the vehicle group. Erythema was observed in femal es at the mid

- (5 of 5) and high

- (4 of 5) dose groups compared to none in either control of low

- dose groups. No microscopic findings of the skin were observed in any of the untreated controls (both sexes). Dermal microscopic
observations included subacute lymphocytic infiltration in all high

- dose females and 2 of 5 mid

dose females compared to none in either control group or low

- dose group, and acanthosis was observed in all rabbits at each dose level (both sexes) and in the vehicle control group (both

sex es) compared to none in the untreated control groups.

The systemic toxicity NOAEL is 1000 mg/kg/day, the highest dose tested. The dermal toxicity NOAEL is 10 mg/kg/day, based on subacute lymphocytic infiltration in females at the LOAEL of 100 mg/kg/day.Page 60 of 68

This guideline repeat dermal toxicity study is classified ACCEPTABLE, and it satisfies the guideline [OPPTS 870.3200; §82

- 2] for a repeat dermal toxicity study in the rabbit.

COMMENT: In the original DER, the NOEL [10 mg/kg/day] was based on effects on various biochemistry parameters [decreases in total bilirubin, increase in mean albumin/globulin ratios, and increase in mean phosphorus] and on microscopic observations of the skin [hyperkerotosis and subacute lymphocytic infiltrates]. The original revie wer [1990] concluded that no adverse effects were noted in the clinical chemistry parameters. Since that time, NOAELs rather than NOELs are established. The registrant submitted a request [MRID 46809310] to establish a NOAEL for this study, based on argume nts that the clinical chemistry findings do not constitute adverse effects due to dermal exposure to trinexapac

- ethyl. The updated Executive Summary incorporates this change.

Developmental Rat

In a developmental oral toxicity study [MRID 41563923], 24 pr egnant Tif: RAIf (SPF), hybrids of RII/1 x RII/2 rats/sex/dose were administered CGA 163935 Technical [96.6%] via gavage at dose levels of 0, 20, 200, or 1000 mg/kg/day during gestation days 6

- 15. There was no adverse effect of treatment on survival, and no apparent treatment

- related clinical signs of toxicity. Body weight was not adversely affected at any dose level. At the high

- dose level, the dams displayed a significant decrease in body

- weight g ain during GD 0

- 6 (prior to dosing; 92% of control) and GD 0

- 21 (overall; 94% of control). Corrected body weight and body

- weight gains were comparable among the groups. There was no treatment

- related effect on food consumption.

Pregnancy rates were compar able among the groups (pregnant prior to dosing). There were no maternal deaths, no abortions, and no premature deliveries. There was a statistically

- significant decrease (89% of control) in the mean number of corpora lutea at the high

- dose level [17.0]

co mpared to the control [19.1]; however, the value is stated to be within the historical control range. Also at the high

- dose level, the mean numbers of implantations (95% of control) and live fetuses (94% of control) were slightly lower than the control. Th e number of early resorptions was comparable among the groups, and there were no late resorptions. There were no dead
fetuses. Pre

- and post

- implantation losses were comparable among the groups. Fetal body weights and sex ratios were comparable among the g roups. There were no treatment

- related malformations. One fetus at 1000 mg/kg/day displayed hypoplasia of the testicle (no historical control data reported). There was an increase in the incidence of asymmetrically shaped sternebra at 1000 mg/kg/day [8 fe tuses in 7 litters; litter incidence: 29.2%] compared to the concurrent [2 fetuses in 2 litters; litter incidence: 9.1%] and historical [48 fetuses/35 litters; litter incidence: 15.1%] control groups.

The maternal toxicity NOAEL is 1000 mg/kg/day, the hi ghest dose tested. The developmental toxicity NOAEL is 200 mg/kg/day, based on an increased incidence of asymmetrically

- shaped sternabrae at the LOAEL of 1000 mg/kg/day (limit dose).Page 61 of 68

This guideline developmental toxicity study is classified ACCEPTABLE, a nd it satisfies the guideline [OPPTS §83

- 3, but not 870.3700 because it only dosed from GD 6

- 15] for a developmental toxicity study in the rat.

Rabbit Developmental

In a developmental oral toxicity study [MRID 41869524], 16

- 17 pregnant New Zealand White rabbits/sex/dose were administered CGA 163935 Technical [96.6%] via gavage at dose levels of 0, 10, 60, or 360 mg/kg/day during gestation days 7

- 19. On pregnant doe at the high

- dose level was found dead (convulsion) on gestation day [GD] 13. A second high

- dose doe was sacrificed on GD 24 following abortion on GD 22 and severe weight loss (hemorrhagic depressions in the stomach). There were no treatment

- related abortio ns, but one doe in each of the control, mid

- , and high

- dose groups aborted. There were no apparent

treatment

- related clinical signs of toxicity in any of the surviving does.

Body weight/body

- weight gain and food consumption were not adversely affected in the survivors at any dose level.

Pregnancy rates were comparable among the groups (pregnant prior to dosing). There were no premature deliveries. The mean number of corpora lutea was comparable among the groups. At the high

- dose level, the mean number of implantations [7.6±2.4 vs 8.8±2.7; 86% of control] and mean number of live fetuses [5.7±2.7 vs 7.7±2.8; 74% of control] was reduced compared to the control. The mean number of live fetuses at the high

- dose level was below that of the historical control [6. 1]. Total and mean numbers of resorptions were comparable among the groups, and
there were no dead fetuses. Pre

- [24.3%] and post

- [24.8%] implantation losses were increased at the high

- dose level compared to the control [14.3% and 13.2%, respectively]. Fe tal body weights and sex ratios were comparable among the groups.
There were no treatment

- related malformations or variations [external, visceral, or skeletal].

The maternal toxicity NOAEL is 360 mg/kg/day, the highest dose tested. The developmental tox icity NOAEL is 60 mg/kg/day, based on a decrease in the mean number of fetus/litter and an increase in post

- implantation loss at the developmental toxicity LOAEL of 360 mg/kg/day.

This guideline developmental toxicity study is classified ACCEPTABLE , and it satisfies the guideline [OPPTS §83

- 3, but not 870.3700 because it only dosed dams from GD 7

- 19] for a developmental toxicity study in the rabbit.

Reproductive Toxicity Study

In a 2

- generation reproduction study (MRID 43128604 ), CGA 163935 Technical [ 96.2% a. i.] was administered to 30 Sprague

- Dawley rats/sex/dose in the diet at concentration levels of 0, 10, 1000, 10000, or 20000 ppm [equivalent to 0, 0.91, 9.01, 130.81, 450.72, or 911.77 mg/kg bw/day (males)/ 0, 1.08, 10.66, 154.08, 538.73, or 1073. 42 mg/kg/day (females)] for 78 weeks. There were no adverse or compound

- related effects on mortality or clinical signs for either the P or F1 generation. At 20000 ppm, decreased body weight [P males 92%**/females 83%** of control (day 91); F1 males 82%**/ females 86%** of control (day 84)], body

- weight gain [PPage 62 of 68

males 87%**/females 62%** of control (days 0

- 91); F1 males 83%**/females 81%* of control (days 0

- 84)], and food consumption [P males 86%**

- 96%*/females 81%**

- 87%** of control;
F1 males 87%**/females 8 6%**

- 93%** of control] were observed during the pre

- mating period in both generations. At 10000 ppm, there were slight decreases in body weight [P males94%*/females 93%* of control (day 91); F1 males 93%*/females 96% of control], body

weight gain [P males 90%**/females 85% of control; F1 males 90%**/females 94% of control], and food consumption [P males 93%*

- 98%/females 95% of control; F1 males 90%**

- 93%/females 94%

- 100% of control] during the pre

- mating period. Although sporadic, significant, decreases i n body weight [P males 93%

- 95%*/females 94%

- 96% of control; F1
males 92%*

- 95%/females 94%*] and body

- weight gain [P males 93%/females 89% of control; F1 males 87%**/females 88% of control] were noted at 1000 ppm mainly in the males (both generations), ther e was no dose

- response. Additionally, during week 4 the P 1000 ppm rats were inadvertently fed the 20000 ppm diet, which may have contributed to these weight changes. Throughout gestation, dams at the 20000 ppm displayed decreased body weights [P generati on 83%**

- 86%** of control; F1 generation 89%** of control] and body

- weight gain [ P generation 93%; F1 generation 89% of control (days 0

- 20)]. Food consumption was decreased initially also [P generation 90%** of control (days 0

- 7), 91%

- 92% of control (days 7

- 20); F1 generation 87%** (days 0

- 7)/91%* (days 7

- 14)/94% (days 14

- 20) of control]. Throughout lactation, there was a decrease in body weight at 20000 ppm, although the deficit diminished with time. The overall body

- weight gain (days 0

- 21) at 20000 ppm was positive [P dams 30.5 grams **; F1 dams 21.1 grams **] compared to negative gains in the control and lower dose groups.

There was no adverse effect on reproductive performance in either generation [comparable male and female mating index, fertility index, gestation index, gestation duration, # and % pregnant, # implantation sites, # viable litters, # and % stillbirths, pre

- and post

- implantation losses].
There were no treatment

- related adverse effects on organ weights, and no treatment

- related differences in macroscopic and microscopic pathology for either generation. There were no adverse effects on the mean litter size on day 0, and the % of males was

c omparable among the groups for both generations. In each generation, pup survival (days 0

- 4) at 20000 ppm was lower [F1 90.1%/F2 93.6%] than the control [F1 96.9%/F2 96.9%] and other dose groups [F1 96.3%, 93.4% 98.5% with increasing dose/F2 96.9%, 96.5%, 96.9%, 96.9% with increasing dose], although statistical significance was not attained. F1 pup survival (lactation days 4

- 21) was lower at 20000 ppm [92.4%*] than the control [98.3%] and other dose groups [97.8%, 100%, 98.3%, 98.0% with increasing dose]. F 2 pup survival (lactation days 4

- 21) was comparable among the groups. Pup body weights were decreased at 20000 ppm for both generations on day 0 [F1 males 94%/females 95% of control; F2 males 95%/females 93%* of control] and throughout lactation [F1 males 76%**

- 82%**/females 77%**

- 82%** of control;
F2 males 76*

- 83%**/females 76**

- 93%* of control]. Body

- weight gains were decreased in both sexes/both generations throughout the lactation period at 20000 ppm, with the largest deficit being observed initially ( days 0

- 4; F1 males 39%/females 41% of control; F2 males and females 59% of control). The magnitude of the body

- weight gain deficits was 74%

- 89% (F1 males),

76%

- 87% (F1 females), 70%

- 81% (F2 males), and 71%

- 79% (F2 females). Clinical observations of the pup s during lactation did not demonstrate treatment

- related systemic toxicity.Page 63 of 68

The NOAEL for reproductive toxicity is 20000 ppm [males 1212 mg/kg/day; females 1485 mg/kg/day (highest dose tested; HDT)]. The NOAEL for parental systemic toxicity is 10000 ppm (males 593.5 mg/kg/day; females 751.1 mg/kg/day), based on reduced premating and gestation body weight/body

- weight gain and food consumption at the parental systemic toxicity LOAEL of 20000 (males1212 mg/kg/day; females 1485 mg/kg/day)

. The offspring syste mic toxicity NOAEL is 10000 ppm (males 593.5 mg/kg/day; females 751.1 mg/kg/day), based on decreased pup survival and decreased pup body weight/body

weight gain during lactation at the offspring systemic toxicity LOAEL of 20000 ppm [males 1212 mg/kg/day; f

emales 1485 mg/kg/day).

This 2

- generation reproduction study in rats is acceptable (guideline), and it satisfies the guideline requirement for a reproduction study [OPPTS 83

- 4; OECD 416] in rats. Developmental milestone data (age of vaginal opening and pr eputial separation; anogenital distance for F2 pups); assessment of implantations sites; estrous cycle length and periodicity (F1 weanlings); and sperm measures were not included in this study.

Chronic Dog Study

In an oral chronic toxicity study (MRID 42 779402, CGA

- 163935 Technical [ (96.2/92.2% a.i.), batch/lot #s FL 882373, 892178, 891417] was administered to 4 purebred beagle dogs/sex/dose

via the diet at dose levels of 0, 40, 1000, 10000, or 20000 ppm (equivalent to 0, 1.56, 31.62, 365.72, or 726.65 (males)/1.37, 39.54, 357.13, or 783.83 mg/kg bw/day) for 52 weeks. All dogs survived until study termination. At dose levels of 10000 ppm and/or 20000 ppm, emesis with food (earliest occurrence at week 7 in males), mucoid/bloody feces (earliest occurrence at week 6 in males), reduced RBC and hematocrit, elevated cholesterol and alkaline phosphatase were observed in both sexes. Slightly lower body w eights were observed at study termination in males at 10000 ppm [89% of control] and 20000 ppm [90% of control] and in females at 20000 ppm [89% of control]. Body

- weight gains fluctuated throughout the study especially in males such that a clear dose

- respo nse was not evident. Decreased body

- weight gains were observed initially at 20000 ppm in both sexes [males negative gain; females 14% of control during first week; males 55%/females 60% of control during weeks 1

- 13 interval]. Overall, males at 10000 ppm [6 6% of control] and 20000 ppm [76% of control] displayed the lowest body

- weight gain, although there was no dose

- response. Females at 20000 ppm displayed a decrease in body

- weight gain overall [73% of control]. Food consumption was not affected. Although no t statistically significant, decreased spleen weights were observed in both sexes at 20000 ppm. Testes (absolute*, relative

- to

- body/brain) and uterus weights (absolute*, relative

- to

body*/brain) were significantly decreased at the three highest dose levels , but there was no dose

response and no histopathological lesions in either organ. There was microscopic evidence of minimal, focal vacuolation of the dorsal medial hippocampus and/or lateral midbrain in all dogs at 20000 ppm and in one male and two female dogs at 10000 ppm. Dose levels up to 20000 ppm were well tolerated by both sexes and are considered adequate. The LOAEL is 10000 ppm [males 365.72/females 357.13 mg/kg/day], based on elevated serum cholesterol values in females, mucoid feces in females a nd bloody feces in both sexes, and minimal, focalPage 64 of 68

vacuolation of the dorsal medial hippocampus and/or lateral midbrain in both sexes. The NOAEL is 1000 ppm [males 31.62/females 39.54 mg/kg/day]. This chronic oral toxicity study in the dog is acceptable

, a nd it satisfies the guideline requirement for a chronic oral study [OPPTS 870.4100, OECD 452] in the dog.

Combined Chronic Toxicity/Carcinogenicity Study in Rats

In a chronic toxicity/carcinogenicity study [MRID 42238104], 50 Sprague

- Dawley Crl:VAF Plus CD(SD)BR rats/sex/dose were administered CGA 163935 Technical [96.9%/96.2%/92.2%] via the diet at concentrations of 0 ppm, 10 ppm, 100 ppm, 3000 ppm, 10000 ppm, or 20000 ppm for 104 weeks [carcinogenicity phase]. An additional group of 20 Sprague

- Dawley Crl:VAF Plus CD(SD)BR rats/sex/dose were administered CGA 163935 via the diet at the same concentrations for 104 weeks [chronic toxicity phase], and an additional group of 10 Sprague

- Dawley Crl:VAF Plus CD(SD)BR rats/sex/dose were administered CGA 163935 v ia the diet at the same concentrations for 52 weeks [interim sacrifice]. The time

- weighted mean daily intakes were 0.38, 3.87, 115.6, 392.7 or 805.7 mg/kg/day for males and 0.49, 4.88, 147.4, 494.0, or 1054 mg/kg/day for females receiving 10, 100, 3000, 10 000, or 20000 ppm, respectively. A recovery phase of 4 weeks followed the administration of the test material to 10 rats/sex at the 20000 ppm dose level [compared with an additional control group of 10 rats/sex].
There was no adverse effect of treatment o n survival, and no apparent treatment

- related clinical signs of toxicity. There was a reduction in body weight in both sexes [males 91%

- 94%; females
86%

- 92%] at the 20000 ppm dose level throughout the study beginning at day 7. At 13 weeks,
both sexes at 20 000 ppm displayed an 8% decrease in body weight. At study termination, males at 20000 ppm displayed a 9% deficit in body weight compared to the control. Females at this dose level showed a greater gain in body weight during the last 24 weeks of the study [ week 76

- 104 interval] such that terminal body weight was comparable [98% of control] to the control; however, at week 76, females at 20000 ppm displayed a 14% deficit in body weight compared to the control. Decreased body

- weight gains were observed in bot h sexes at the high dose during
the weeks 0

- 12 interval [males 93*%/females 84%** of control]. Females also showed decreased body

- weight gain at the 1

- year time point [81%**of control]. Overall body

- weight gain was 90% of control for the males and 95% of c ontrol for the females at 20000 ppm. Food consumption values were lower than the control values for the first 6 months in males and for the
first 15.5 months for females.

There were no treatment

- related ocular changes in either sex. There were no apparent , treatment

related effects on the hematology or clinical chemistry parameters monitored in either sex. Urinary pH was decreased in both sexes at the 10000 ppm and 20000 ppm dose levels throughout the study, although no histopathological correlations accom panied these findings. In males, decreased absolute and relative

- to

- brain heart weights were observed at 20000 ppm at 52 weeks. There was a slight but significant increase in relative liver and lung weights in females at the 20000 ppm dose level at 52 we eks. At termination [104 weeks], the increased relative organ weights were considered due to decreased body weight at 20000 ppm. No treatment

related organ

- weight effects were reported in either sex at 10000 ppm.Page 65 of 68

In the liver, there was a statistically

- significant increase in bile duct hyperplasia in males at 20000 ppm at study termination [16, 11, 13, 13, 18, 35** with increasing dose]. Females at 20000 ppm displayed an increased incidence of acanthosis in the gla ndular stomach at study termination [7, 6, 1, 1, 8, 13* with increasing dose]. Lymphangietasis was increased at the two highest dose levels in males at study termination [3, 4, 8, 4, 9*, 19* with increasing dose]. Females displayed an increased incidence o f galactocele of the mammary gland [5, 5, 4, 7, 9, 13** with increasing dose] and stromal hyperplasia of the ovary was increased at the two highest dose levels [3, 1, 3, 1, 7*, 5* with increasing dose], but there was no dose response. Squamous cell carcin oma of the non

- glandular stomach was observed in two males (2.5%) at 20000 ppm but in none of the control rats or other rats at any dose level in either sex. The normal range reported for males by the author was 0%

- 1.2%. Follicular adenocarcinoma of the

t hyroid was significantly increased in males (5%) at 20000 ppm, and there was a significant positive trend [1, 0, 0, 1, 1, 4*]. The historical control range was 0%

- 5% (1.8% mean) compared
to 1.2% in concurrent control. The incidence of combined follicular a denomas and adenocarcinomas of the thyroid did not show a dose

- related increase [5, 2, 3, 6, 6, and 7 with increasing dose]. Urinary bladder papilloma incidence was significantly increased in females at 20000 ppm [0, 0, 0, 0, 1, 2* with increasing dose), b ut the increase was slight and the finding is
considered incidental.

The systemic toxicity NOAEL is 20000 ppm [males 806 mg/kg/day; females 1054 mg/kg/day], the highest dose tested.

This guideline chronic toxicity/carcinogenicity study is classified A CCEPTABLE , and it satisfies the guideline [OPPTS 870.4300; §83

- 5] for a chronic toxicity/carcinogenicity study in
the rat.

Non

- neoplastic lesions : There was no apparent increase in the incidence of any non

- neoplastic
lesion in either sex. Neoplastic les ions : Squamous cell carcinomas were observed in the non

- glandular portion of the rat stomach in two males at the 20000 ppm dose level.
Discussion of Tumor Data : It was concluded that extrapolation of effects on the non

- glandular portion of the rat stomach to possible deleterious effects of trinexapac

- ethyl on the pharynx and/or esophagus (non

- glandular areas) of the human was not appropriate. This was because trinexapac

- ethyl would not be in contact with the human tissues for a significant period of time

c ompared with how it would have been in contact with the rat stomach.

Adequacy of the Dose Levels Tested : The highest dose [20000 ppm ] is approaching the limit dose in males (806 mg/kg/day) and is greater than the limit dose in females (1054 mg/kg/day). The dose levels are considered adequate for the assessment of carcinogenicity potential in the rat.

Car cinogenicity Study in Mice

In a carcinogenicity study (MRID 43128603 ), CGA 163935 Technical [FLs 872026, 881224, 882373; 96.9%/96.2% a. i.] was administered to 70 CD

- 1 mice (Crl:CD

- 1(ICR)BR)/sex/dose in the diet at dose levels of 0, 7, 70, 1000, 3500, or 7000 ppm [equivalent to 0, 0.91, 9.01, 130.81,Page 66 of 68

450.72, or 911.77 mg/kg bw/day (males)/ 0, 1.08, 10.66, 154.08, 538.73, or 1073.42 mg/kg/day (females)] for 78 weeks. There were no adverse or compound

- related effects on mortality, clinical signs, body weigh t, food consumption, hematology, organ weights, or gross and histologic (including tumors) pathology. The decreased body

- weight gain observed in the 7000 ppm female group initially was attributed to palatability. No LOAEL was attained. The NOAEL is 911/1 073 mg/kg/day (highest dose tested; HDT).

There was no treatment

- related increase in tumor incidence when compared to controls. Dosing was considered adequate based on a lack of adverse effect at dose levels up to and exceeding the
limit dose.

This carci nogenicity study in mice is acceptable (guideline), and it satisfies the guideline requirement for a carcinogenicity study [OPPTS 870.4200; OECD 451] in mice.

Non

- neoplastic lesions : There was no apparent increase in the incidence of any non

- neoplastic
le sion in either sex. Neoplastic lesions : There was no treatment

- related increase in tumor incidence when compared
to controls.
Discussion of Tumor Data : There was no increase in tumors of any type in either sex of mouse. Adequacy of the Dose Levels Tested : . Dosing was considered adequate based on a lack of adverse effect at dose levels up to and exceeding the limit dose.

Dermal Absorption Study

A single dermal dose of 0.01, 0.1, and 1.0 mg/cm2 14C

- CGA

- 163935 administered to male rats was rapidly absorbed, distributed and eliminated. The amount absorbed increased with duration of exposure. Using the direct procedure to calculate skin absorption, the average 14C

- CGA

163935 absorbed within 24 hours was 64.9, 63.86, and 30.85% of the applied dose for the low

- , mid

- , and high

- dose groups, respectively. Using the indirect procedure to calculate skin absorption, the average 14C

- CGA

- 163935 absorbed within 24 hours was 56.83, 66.74, and 33.84% of the applied dose for the low

- , mid

- , and high

- dose groups, r espectively. The direct procedure is the more realistic procedure to use. A dermal absorption factor of 77.5% was estimated based on the sum of 56.5% absorbed after 10 hours in the low dose group (0.01 mg/cm 2 ), in addition to 21% of applied dose that was associated with the application site.

Immunotoxicity study

In an immun otoxicity study (MRID 48444101 )

, trinexapac

- ethyl ( 96.6 % a.i. ; Lot no.
SMO5D180 ) was administered to female B6C3F1 mice (10/ dose ) in the diet at dose levels of 0,
500

, 2000

, or 5000 ppm (0, 160.2, 613.7, or 1530.5 mg/kg/day, respectively) for 28 days.
Animals w ere divided into two subsets, the splenic antibody

- forming cell (A FC) group and the
Natural Killer c ell (NKC) group

. In the AFC group, positive control mice were administered

c yclophosphamide via intraperitoneal injection (50 mg/kg/day) once daily for 4 consecutive days (study days 24 through 27 ). On study d ay 24, a ll AFC group mice were immunized with 0.2 mL of sheep red blood cells (SRBC, 7.5x10 7 /mL) via intravenous injection s. In the NKC group,Page 67 of 68

positive control mice were administered anti

- asialo GM1 via a single intravenous injection (0.2 mL/animal) on study day 27, approximately 24 hours prior to scheduled necropsy. On day 28, all animals were necropsied, gross pathology ob servations were performed and selected organs (spleen and thymus) weighted. The immunotoxicity assessment was evaluated with a splenic antibody

- forming cell (A FC) assay and a Natural Killer c ell (NKC) activity assay.

There were no treatment related effects on mortality, clinical observations, body weights, food consumption, thymus and spleen weights, or macroscopic findings in either the AFC or NKC groups of animals.

The systemic toxicity NOAEL is 5000 ppm (1530.5 m g/kg/day, the highest dose tested), the
LOAE L was not established.

In the AFC group, there were no effects attributed to trinexapac

- ethyl on spleen cell numbers and
anti

- SRBC antibody

- forming

- cell (AFC) response in either specific activity (AFC/10 6 cells) or total activity (AFC/spleen) to the T

- cell

- dependent antigen SRBC. The positive control (cyclophosamide) produced statistically sign ificant decreases in s pecific activity (

- 100%) and

t otal s pleen a ctivity (

- 100%) in the female B6C3F1 mice as expected , w hen compared to the
vehicle control animals

.



### In the NKC group, there were no statistically s ignificant effects attributed to trinexapac

- ethyl at any E:T ratio as com pared to the vehicle controls. The positive control (anti

- asialo GM1) signifi cantly decrea sed the functional response of the NK cells, reaching the level of statistical signific ance at the E:T ratios of 200:1 and 100:1 , when compared to the vehicle control animals.

The immunotoxicity NOAEL for ant i

- SRBC AFC response and NK cell activity is 500 0 ppm (1530.5 mg/kg/day) , the LOA EL was not established.

T his immunotoxicity study is classified A cceptable/guideline and satisf ies the guideline requirement for an immunotoxicity study (OPPTS 870.7800)

.

COMPLIANCE : Signed and dated Data Confidentiality , GLP Compliance, Flagging, and Quality Assurance statements were provided.

References
41563920 Chau, R. Y.; McCormick, G. C.; and Arthur, A. T. (1989). 13

- Week Oral Feeding

Study in Dogs.
41563921 Chau, R. Y.; McCormick, G. C.; and Arthur, A. T. (1989). 13

- Week Oral Feeding

Study in Rats.
41563922 Huber, K. R.; Batastini, G.; and Arthur, A. T. (1989). 21

- Week Dermal Toxicity

Study in Rabbits.
41563923 Schoch, M. (1988). Developmental Toxicity (Teratogenicity) Study with CGA

163935 Technical in Rats.Page 68 of 68

41869524 Hughes, E. (1990). Developmental Toxicity (Teratogenicity) Study with CGA

163935 Technical in Rabbits.

42238104 Giknis, M. L.; Batastini, G.; and Arthur, A. T. (1992).52/104 Week Oral Toxicity

Study in Rats

. 42779401 Hardisty, J. F. (1992). Supplement to 52

- Week Feeding Study in Dogs.
42779402 Chau, R. Y.; Kirchner, F. R.; and Arthur, A. T. (1991). 52

- Week Feeding Study in

Dogs.
43128603 Rudzki, M. W.; Batastini, G., and Arthur, A. T. (1991). 78

- Week Oral

Carcinogenicity Study in Mice.

43128604 Singh, A.; Hazelette, J.; and Yau, E. (1991). CGA

- 163935 Technical. A Two

Generation Reproductive Toxicity Study in Rats. 43128605 Geleick, D. Gene Mutations Test Mouse Lymphoma Mutagenicity Assay in vitro

. 4 6809308 Deparade, E. (2001). CGA275537 Technical (metabolite of trinexapac

- ethyl).