Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 2 of 78 1.0 Executive Summary

This document describes the human health risk assessment conducted to support the Section 3 registration decision for the first f ood use of aminocyclopyrachlor. Aminocyclopyrachlor is proposed for use on rangeland, pastures, and Conservation Reserve Program (CRP) acres. T he

assoc i a ted tolerances for residues on grass and livestock commodities are also described.

Aminocyclopyrachlor has previously been registered for non

- food, herbicidal use. Aminocyclopyrachlor is a member of the pyrimidine carboxylic acid chemical class. The pesticidal mode of action is dysregulation of gene products involved in auxin recepto r activity, which interferes with normal shoot and root development to stop the growth of weeds. Three formulations of aminocyclopyrachlor are being registered in this action : the parent acid (PC Code 288008, Reg. Nos. 352

- 782, 352

- 787); the potassium salt (PC Code 288010 , Reg. No

. 352

- 786); and the methyl ester (aminocyclopyrachlor

- methyl, PC Code 288009, Reg. Nos.
352

- 783, 352

- 784, 352

- 785). Two formulations are the parent acid co

- formulated with chlorsulfuron (352

- ILR) or metsulfuron (3 52

- ILN). The parent acid (aminocyclopyrachlor) is considered the active ingredient.

Hazard and Dose

- Response Considerations

Aminocyclopyrachlor and aminocyclopyrachlor

- methyl The toxicology database for aminocyclopyrachlor is adequate for risk assess ment for the

pr oposed use patterns. There are no target organs of toxicity for aminocyclopyrachlor. Mild systemic toxicity is observed via the oral route with repeated exposures at very high (limit) doses. This systemic toxicity is limited to decreased body weight and body weight gain. There

are no appreciable increase s in the severity of these effects with time. The most sensitive species
is the rat.

Aminocyclopyrachlor has been classified as ―Not Likely to be Carcinogenic to Humans‖ because it is not tumorgenic in rodents and was negative in a full panel of in vitro and in vivo genotoxicity assays . Therefore, carcinogenicity was not quantified

.

Re peat ed

- dose toxicity studies via the dermal route showed no systemic toxicity of aminocyclopyrachlor at the limit dose. No repeated

- exposure studies were available via the inhalation route. Therefore, extrapolation from th e oral route of exposure was use d to assess
inhalation risks.

The toxicity database for aminocyclopyrachlor

- methyl is being bridged with aminocyclopyrachlor. Support for bridging is provided by evidence that aminocyclopyrachlor

methyl is rapidly metabolized in rats to aminocyclopyrachlor . Furthermore, oral toxicity studies at select endpoints show that aminocyclopyrachlor

- methyl causes effects similar to aminocyclopyrachlor at the same dose levels.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 3 of 78 Cyclopropane carboxylic acid Cyclopropane carboxylic acid is a n e nvironmental photodegradate of aminocyclopyrachlo r present only in surface water. This photodegradate has a different mode of toxic ac tion than aminocyclopyrachlor and aminocyclopyrachlor

- methyl

. The target organ is the liver and the
mechanism of toxic a ction is impairment of mitochondrial function by inhibiting the beta oxidation of fatty acids, resulting in microvesicular steatosis (accumulation of small fat droplets in cells) that is often accompanied by liver necrosis and inflammation, decreased hepat ic glycogen, and decreased blood glucose levels. These effects have been observed with acute (one to three days) and repeated (up to 14 days) exposure s . The most sensitive species is the rabbit. Hepatic microvesicular steatosis in the rabbit follows a d ifferent dose

- response than body weight decreases observed with aminocyclopyrachlor and aminocyclopyrachlor

- methyl in rats, with a
LOAEL that is 100

- fold lower.

Dietary Exposure (Food and Water)

Dietary exposures to aminocyclopyrachlor and aminocyclopy rachlor

- methyl may occur in food (meat and milk) and drinking water. Dietary exposure to the environmental photo degradate, cyclopropane carboxylic acid, will occur in drinking water only. For aminocyclopyrachlor, no acute dietary endpoint was identified, and so acute dietary risks were not assessed. Assessment of chronic dietary risks in all population subgroups that included an estimated drinking water concentration of 42.2 ppb resulted in no risks of concern. Cancer risks for aminocyclopyrachlor

were not assessed because no cancer endpoint was identified.

Risks from d ietary exposures to cyclopropane carboxylic acid in drinking water were assessed using an annual peak estimated drinking water concentration (EDWC) of 2.12 ppb for acute dietary exposure and an annual average EDWC of 1.52 ppb for chronic dietary exposure. No risks of concern were identified in any population subgroup. Risks from dri n king water exposure were not aggregated with aminocyclopyrachlor/aminocy c lopyrachlor

- methyl due t o the
different mechanism of toxic action of cyclopropane carboxylic acid. Cancer risks for dietary exposure to cyclopropane carboxylic acid in drinking water were not quantitatively assessed
because structure

- activity relationship (SAR) analysis and the open scientific literature indicated no carcinogenicity hazard, and because dietary exposures are very low (< 1 μg/kg/day).

Residential Exposure

Aminocyclopyrachlor is currently registered for use on turf. No new residential uses for aminocyclopyra chlor are proposed in this action. The Agency has previously assessed exposures and risks for residential uses of aminocyclopyrachlor for non

- food uses on turf (D369057, March 17, 2010). No risks of concern were identified for application t o lawn/turf fr om short / intermediate

- term inhalation exposures during open mixing/loading and applying. Post

application hand

- to

- mouth, obj ect

- to

- mouth, and soil ingestion exposures and risks were also
assessed for children and no risks of concern were identified. Derm al risks were not assessed because no dermal endpoint was identified.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 4 of 78 A ggregate exposures to aminocyclopyrachlor were considered for residential short

- and
intermediate

- term scenarios and dietary exposures for children and adults. No ri sks of concern

we re identified

.

Occupational Exposure

Aminocyclopyrachlor will be appl ied to rangeland, pastures, or Conservation Reserve Program ( CR P ) acres aerially or by groundboom. Occupational handler exposures may occur via the
dermal and inhalation routes . These exposures are short

- term or intermediate

- term in duration

. Dermal risks were not assessed because no dermal endpoint was identified from the toxicity
database . Cancer risks for occupational handlers were not assessed because no cancer hazards

we re identified.

Inhalation risk for applicators in the absence of respiratory protection w as assesse d by analysis of
short/ intermediate

- t erm exposures using the product with the highest application rate . No risks
of concern were identified.

Additional Data Needs and Recommendations

No additional data are required to assess the human health risks of aminocyclopyrachlor or aminocyclopyrachlor

- methyl for the use patterns described in this risk assessment. Additional
data are needed to better characteriz e the hazard of chronic exposure to the environmental photo degradate

, cyclopropane carboxylic acid. The Registrant is currently conducting a study to
address this duration of exposure

. The aminocyclopyrachlor database is not sufficient to support rotation to crops other than grasses at this time, as limited rotational crop field trials remain outstanding.

HED recommends conditional registration for use on grasses and further recommends that labels
be amended to prohibit rotation to crops other than grasses until these outstanding data needs are addressed. HED is also providing recommendations for proposed tolerances.

Use of Human Studies

This risk assessment relies in part on data from studies in which adu lt human subjects were intentionally exposed to a pesticide or other chemical. The se studies, listed in Appendix B , have been determined to require a review of their ethical conduct. Some of these studies are also subject to review by the Human Studies R eview Board. All of the studies used have received the appropriate review.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 5 of 78 2.0 HED Recommendations

No additional data are required to assess the human health risks of aminocyclopyrachlor or aminocyclopyrachlor

- methyl for the use patterns desc ribed in this risk assessment. Additional, repeated

- dose toxicity data are needed to ide ntify a N OAEL for microvesicular hepatic steatosis in a sensitive species for the environmental photo degradate cyclopropane carboxylic acid. The Registr ant is currentl y conducting a study to address this. The database is not sufficient to support rotation to crops other than grasses at this time, as limited rotational crop field trials remain outstanding. HED also recommends that an analytical reference standard for aminocyclopyrachlor

- methyl be supplied and that supplies be replenished as requested by the Repository.

HED recommends conditional registration for use on grasses

. The revised label should include
a rotational crop restriction (i.e.

, 1 year plantback interval (PBI) ) in order for rotation not to be a condition of registration. ) If a shorter PBI is requested, rotational data should be submitted.
HED is also providing recommendations for proposed tolerances.

2.1 Data Deficiencies/Conditions of Registrat ion

HED recommends c onditional registration for use on grasses pending receipt of a r epeated

- dose toxicity data for cyclopropane carboxylic acid to identify a N OAEL for microvesicular hepatic
steatosis in a sensitive species. This study was a condition of registration for the previous risk assessment and the Registrant is currently conducting the study.

HED further recommends that labels be amended to prohibit rotation to crops other than grasses until a guideline (860.1900 ) Field Accumulation in Rotational Crops study is received.
HED also recommends that an analytical reference standard for aminocyclopyrachlor

- methyl be supplied and that supplies be replenished as requested by the Repository, as discussed in
Memorandum D 387442 (T. Morton, April 18, 2012 ).Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 6 of 78 2.2 Tolerance Considerations

2.2.1 Enforcement Analytical Method

The recommended tolerance expression and tolerance proposals for aminocyclopyrachlor are found in S ectio n 2.2.3.

The petitioner has proposed high performance liquid chromatography methods with tandem mass spectrometry detection (LC/MS/MS) for enforcement of tolerances for aminocyclopyrachlor on grass commodities, DuPont

- 22582 SU1 RV2, and livestock commodities, DuPon t

- 27162, Revision No. 1. The methods adequately determine residues of aminocyclopyrachlor and aminocyclopyrachlor

- methyl as well as the metabolites IN

- LXT69 and INQFH57 and IN

QGC48 (grass commodities only), in/on grass forage and hay and milk, eggs, and bovine tissues. The validated limit of quantitation (LOQ) is 0.01 ppm for each analyte. HED has concluded that
the livestock and grass method s are adequate for enforcement purposes

. HED has determined
that t olerance method validation (TMV ) by EPA’s Anal ytical Chemistry Branch is not needed for the proposed enforcement methods for plant and livestock commodities. The proposed
enforcement methods or earlier versions of the methods were used for data collection in the submitted storage stability, cattle fe eding, and grass crop field trial studies.

Acceptable multiresidue methods test data have been submitted for aminocyclopyrachlor and aminocyclopyrachlor

- methyl. The data indicate that multiresidue methods may be appropriate
for determination of aminocy clopyrachlor

- methyl but are not suitable for determination of aminocyclopyrachlor or for determination of the two analytes together. The submitted data will be forwarded to the U.S. Food and Drug Administration (FDA) for further evaluation.

2.2.2 Interna tional Harmonization

There are no established or proposed Codex or Canadian maximum residue limits (MRLs) for aminocyclopyrachlor in or on any food or feed crops . T herefore, there are no harmonization
issues.

2.2.3 Recommended Tolerances

It is recom mended that tolerances be established for residues of the herbicide aminocyclopyrachlor, including its metabolites and degradates, i n or on the commodities specified in T able 2.1.

Compliance with the specified tolerance levels is to be determined by measuring only the sum of aminocyclopyrachlor [ 6

- amino

- 5

- chloro

- 2

- cyclopropyl

- 4

- pyrimidinecarboxylic acid ] , and aminocyclopyrachlor

- methyl [ methyl 6

- amino

- 5

- chloro

- 2

- cyclo propyl

- 4

- pyrimidinecarboxylate] calculated as the stoichiometric eq uivalent of aminocyclopyrachlor, in or on the commodity.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 7 of 78 Table 2.1 Tolerance Summary for Aminocyclopyrachlor

Commodity Established/Proposed Tolerance (ppm) Recommended

Tolerance (ppm) Comments

Cattle, fat 0.07 0.0 5
Cattle, liver 0.06 Not required Based on current Agency policy a separate lower tolerance for liver is not appropriate

Cattle, meat 0.02 0.02
Cattle, meat byproducts, except liver 0.4 Not required
Cattle, meat byproducts

-- 0. 3 0 Based on current Agency policy, the meat byproducts tolerance should be based on the highest residue between liver, kidney, and fat

. Goat, fat 0.07 0.0 5
Goat, liver 0.06 Not required See comment for cattle, liver

Goat, meat 0.02 0.02
Goat, meat byproducts, except liver 0.4 Not required
Goat, meat byproducts

-- 0. 3 0 See comment for cattle, meat byproducts, except kidney
Grass, forage 65 80 *
Grass, hay 125 200 *
Horse, fat 0.07 0.0 5
Horse, liver 0.06 Not required See comment for cattle, liver

Horse, meat 0.02 0.02
Horse, meat byproducts, except liver 0.4 Not required
Horse, meat byproducts

-- 0. 3 0 See comment for cattle, meat byproducts

Milk 0.035 0.0 2
Sheep, fat 0.07 0.0 5
Sheep, liver 0.06 Not required See comment for cattle, liver
Sheep, meat 0.02 0.02
Sheep, meat byproducts, except liver 0.4 Not required
Sheep, meat byproducts

-- 0. 3 0 See comment for cattle, meat byproducts

*Based on OECD MRL CalculatorAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 8 of 78 2.2.4 Revisions to Petitioned

- For Tolerances

The Agency used the OECD MRL Calculator (March 2011 version) to determin e the appropriate
tolerance levels in grass forage and hay , whereas the petitioner used a NAFTA calculator . I n instances in which these calculators yielded different results, the Agency used the OECD
calculator to establish tolerances. Th e OECD calculator indicated that proposed tolerances of 65

ppm and 125 ppm for grass forage and hay were too low and should b e established at 80 ppm and 200 ppm, respectively. The cattle feeding study data indicate that tolerances are needed for milk, and the tissues of cattle, goat, horse, and sheep. The proposed tolerance in milk is too high, and the proposed tolerances for liver and meat byproducts, except liver are not consistent with Agency policy. For l ivestock commodities, individual tolerances in cow, goat, horse, and sheep should be established for meat byproducts at 0. 3 0 ppm , fat at 0.05 ppm, and meat at 0.02 ppm.
The tolerance for milk should be established at 0.0 2 ppm. The tolerances for liver and meat byproducts, except liver are not needed.

2.3 Label Recommendations

2.3.1 Recommendations from Residue Reviews

Pending submission of the required limited field rotational crop trials, HED recommends that
labels be revised to prohibit rotation to any crop other than grasses following application of aminocyclopyrachlor or aminocyclopyrachlor

- methyl.

2.3.2 Recommendations from Occupational Assessment

There are no label recommendations from the occupational assessment.

2.3.3 Recommendations f rom Residential Assessment

There are no label recommendations from the residential assessment.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 9 of 78 3.0 In troduction

3.1 Chemical Identity

Table 3.1 Test Compound Nomenclature

- Aminocy clopyrachlor (parent acid)

Chemical Structure

Empirical Formula C 8 H 8 ClN 3 O 2
Common Name Aminocyclopyrachlor
Company experimental name DPX

- MAT28

IUPAC name 6

- a mino

- 5

- chloro

- 2

- cyclopropyl

- 4

- pyrimidinecarboxylic acid

CAS Name 6

- amino

- 5

- chloro

- 2

- cyclopropyl

- 4

- pyrimidinecarboxylic acid
CAS Registry Number 858956

- 08

- 8

End

- use product/EP 352

- 782, 352

- 787 , 352

- ILR (with chlorsulfuron) , 352

- ILN (with metsulfuron)

Chemical Class Pyrimidine carboxylic acid
Known Impurities of Concern NoneAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 10 of 78 Table 3.2 Test Compound Nomenclature

—Aminocyclopyrachlor (potassium salt)

Chemical Structure

Empirical Formula C 8 H 7 ClKN 3 O 2
Common Name Aminocyclopyrachlor , potassium salt
Company experimental name DPX

- MAT28

IUPAC name potassium 6

- amino

- 5

- chloro

- 2

- cyclopropylpyrimidine

- 4

- carboxylate

CAS Name potassium 6

- amino

- 5

- chloro

- 2

- cyclopropyl

- 4

- pyrimidinecarboxylate
CAS Registry Number 858956

- 35

- 1

End

- use product/EP 352

- 786

Chemical Class Pyrimidine carboxylic acid
Known Impurities of Concern NoneAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 11 of 78 Table 3.3 Test Compound Nomenclature

— Aminocyclopyrachlor

- methyl (methyl ester)

Chemical Structure

Empirical Formula C 9 H 10 ClN 3 O 2
Common Name Aminocyclopyrachlor

- methyl
Company experimental name DPX

- KJM44

IUPAC name methyl 6

- amino

- 5

- chloro

- 2

- cyclopropylpyrimidine

- 4

- carboxylate

CAS Name methyl 6

- amino

- 5

- chloro

- 2

- cyclopropyl

- 4

- pyrimidinecarboxylate
CAS Registry Number 858954

- 83

- 3

End

- use product/EP 352

- 783, 352

- 784, 352

- 785

Chemical Class Pyrimidine carboxylic acid
Known Impurities of Concern None

3.2 Physical/Chemical Characteristics

Aminocyclopyrachlor has a log octanol/water partition coefficient of

- 2.48 at pH 7, a molecular weight of 213.6 g/mole ( Memorandum D357886, 8/16/2009) , and contains functional groups (e.g. carboxylic acid and a primary amine) that will be ionized at physiological pH. For these

re asons, the potential for aminocyclopyrachlor to cross biological barriers (such as the skin) and biological membranes is considered low. Aminocy c lopyrachlor

- methyl has a log octanol/water partition coefficient of 1.87, a molecular weight of 227.6 g/mole ( Memorandum D357975, 8/25/2009) and one functional group that will be ionized at physiological pH (a primary amine). The presenc e of fewer charged groups and a log octanol

- water partition coefficient in the range
of

- 1 to 3.5 indicates an increased potenti al for aminocyclopyrachlor

- methyl to cross biologic al barriers (such as the skin) compare d to aminocyclopyrachlor

.

The potential for aminocyclopyrachlor and aminocyclopyrachlor

- methyl to be inhaled as a
volatile is considered low. A minocy c lopyrachlor has a vapor pressure of 6.92 x10 - 6 Pa (6.92
x10 - 9 kPa) at 20 C and 4.91 x10 - 9 k Pa at 25 C ( Memorandum D357886 , August 16, 2009 )

. Aminocyclopyrachlor

- methyl has a vapor pressure of 4.192 x 10 - 4 Pa ( 4.192 x 10 - 7 kPa) at 20 C
and 4.451 x 10 - 4 Pa ( 4.451 x 10 - 7 kPa) at 25 C. It was considered to have negligible tendency to evaporate from aqueous solutions based on Henry’s Law ( Memorandum D357975, August 25, 2009).Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 12 of 78 3.3 Pesticide Use Pattern

DuPont has submitted draft amended labels for the 50% WG formulation (EPA Reg. No. 352

- 787), the 2 lb/gal SL formulation (EPA Reg. No. 352

- 786) of the potassium salt, and the 80% WG formulation (EPA Reg. No. 352

- 786) of aminocyclopyrachlor

- methyl. A summary of the proposed use p a ttern is presented in Table 3. 4 on page 13

.

The labels state that a nonionic surfactant (NIS) is the preferred adjuvant, to be included at 0.06

- 0.50% v/v; crop oil concentrates (COCs), including petroleum or modified seed oil (MSO) may be used at up to 0.5% v/v for MSOs or at 1

- 2% v/v for all others.

The products may be tank mixed with other herbicides, insecticides, and fungicides that are registered for the same use sites, methods of application, and timings. When tank mixing, the most restrictive label limitations of the products being used are to be followed; use of a spray adjuvant is specified for post emergence applications.

The label specifies a restricted entry interval (REI) of 12 hours. Coveralls and shoes plus socks are specified as PPE for contact with anything that has been treated with early entry into treated areas as permitted by the Worker Protection Standard. The Agency considers this REI and PPE adequate for the proposed use patterns.

The following rotational crop restrictions are specified: a 4

- month Plant Back Interval ( PBI ) is specified for grasses (over

- seeding or renovation); and a 1

- year PBI is specified for all other crops. Forage legumes may be seeded after a soil bioassay has been conducted verifying that the level of aminocyclopyrachlor in the soil will not adversely affect the new crop.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 13 of 78 Table 3. 4 Summary of Directions for Use of Aminocyclopyrachlor.

Applic. Timing, Type, and Equip. 1 Formulation

[EPA Reg. No.] Applic.

Rate 2
(lb ai/A) Max. No. Applic. per
Season 2 Max.

Seasonal Applic.
Rate (lb ai/A) PHI

(days) Use Directions and

Limitations

Pasture (including grass grown for hay) and Rangeland Grasses

Foliar, Broadcast, Ground (min. 10 gal/A) or aerial (min. 2 gal/A) 50% WG [352

- 787]

2 lb/gal SL of the K
salt 3
[352

- 786]

80% WG of aminocyclopyrachlor

methyl 4
[352

- 785] 0.038

-

0.172 2 0.281 0 (forage and hay) Apply to new plantings when the majority of grasses
are in the 3

- to 4

- leaf stage or to perennial native grasses and pasture grasses
established for at least one growing season. A 30

- day
treatment interval is specified. Use of a spray adjuvant (nonionic surfactant or crop oil concentrate) is specified. Minimum spray volume of 10 gal/A for ground applications and 2 gal/A for aerial applications.

1 Do not apply through any type of irrigation system; a 12

- hour reentry interval is specified.

2 Rates expressed in terms of the aminocyclopyrachlor ai. Based on calculations, individual maximum application rates are 0.166 lb ai/A for the 50% WG, 0.172 l b ai/A for the 2 lb/g al K SL, and 0.164 lb ai/A for the 80% WG
formulation.

3 Equivalent to 2 lb ae/gal aminocyclopyrachlor.

4 Equivalent to 75% ae/gal aminocyclopyrachlor.

3.4 Anticipated Exposure Pathways

Humans may be exposed to aminocyclopyrachlor in meat and milk, since aminocyclopyrachlor may be applied directly to pastu re and rangelands on which cattle graze. Humans may also be exposed to aminocyclopyrachlor in surface and ground sources of drinking water after application . Non

- dietary exposures to aminocyclopyrachlor can occur in residential settings during and after application to turf

. In an occupational setting, applicators may be exposed while handling the pesticide prior to application, as wel l as during application. There is a potential for post

- application exposure for workers re

- entering treated fields.

This risk assessment considers dietary and occupational exposures for the proposed new (first food) uses of aminocyclopyrachlor . It als o considers the existing non

- food uses that result in additional dietary exposures in drinking water. Risks from residential exposures were discussed in a previous assessment ( Memorandum D369057, March 17, 2010).Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 14 of 78 3.5 Consideration of Environmental J ustice

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 Population s and Low

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

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

- established procedures. In line with OPP policy, HED estimates risks to population subgroups from pesticide exposures that are based on pat terns 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 pesticide. These data are analyzed and categorized by subgroups based on age, season of the year, ethnic group, and region of the country. Additionally, OPP is able to assess dietary exposure to smaller, specialized subgroups and exposure assessments are performed when conditions or circumstances warrant. Whenever appropriate, non

- dietary exposures based on home use of pesticide products and associated ri sks for adult applicators and
for children 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 s oftware and models that consider exposure to bystanders and farm workers as well as lifestyle and traditional dietary patterns among specific subgroups.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 15 of 78 4.0 Hazard Characterization and Dose

- Response Assessment

4.1 Toxicology Studies Available for Anal ysis

Aminocyclopyrachlor and aminocyclopyrachlor

- methyl The toxicity database is sufficient for characterizing the hazards of aminocyclopyrachlor for exposures that are anticipated to occur via the dermal and oral routes. Dermal exposures are anticipate d to be acute to subchronic, and a subchronic dermal toxicity study is available. Inhalation exposures are also anticipated to occur and are expected to be short

- term to intermediate

- term in duration. Oral exposures to aminocyclopyrachlor are expected to range in duration from acute to chronic, and there are several oral toxicity studies available from which to
assess these effects:

A n EPA guideline acute neurotoxicity study ; Subchronic EPA guideline toxicity studies in rats, mice, and dogs; prenatal development studies in rats and rabbits; a reproduction and fertility effects study in rats; a s ubchronic neurotoxicity study; and immunotoxicity studies in rats and mice ; A chronic toxicity study in dogs, a chronic toxicity and carcinogenicity study in rats, and

a carcinogenicity study in mice

.

There is also a complete genotoxicity battery of in vitro and in vivo studies, metabolism studies
in rats that characterize t he absorption, distribution, metabolism, and excretion ( ADME ) of aminocyclopyrachlor, and acute toxicity studies (oral, dermal, and inhalation studies in rats, eye irritation and dermal irritation studies in rabbits, and a skin sensitization study in guinea p igs ).

The toxicity database for aminocyclopyrachlor

- methyl is being bridged by aminocyclopyrachlo r and is also considered sufficient. The toxicity data supplied for aminocyclopyrachlor

- methyl provide comparative endpoints with effects similar to aminoc yclopyrachlor that support the bridging strategy. These studies are: An EPA guideline subchronic oral toxicity study in rats; An OECD guideline one

- generation reproduction study in rats that includes a modified functional observational battery;
Metaboli sm studies in rats that characterize the ADME of aminocyclopyrachlor

- methyl and show that it is rapidly converted t o aminocyclopyrachlor in rats ; An in vitro genotoxicity (gene mutation) study.

No inhalation studies are available for aminocyclopyrachlor or aminocyclopyrachlor

- methyl. An inhalation study is not required for the proposed uses because the risk estimates for occupational handlers are sufficiently protective (vapor pressure ≤ 4.5 x 10
- 7 kPa, see Section 3.0; MOEs ≥ 49,000, see Section 9.0). Since the MOEs were determined using the maximum seasonal application rate ( as opposed to the lower single application rate) the MOEs are considered to be
conservative. Future use requests may require that this decision be re

- evaluated.

No data in th e open scientific literature are currently available for characterizing the hazard of aminocyclopyrachlor or aminocyclopyrachlor

- methyl.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 16 of 78 Cyclopropane carboxylic acid The toxicity database for the environmental photo degradate, cyclopropane carboxylic acid, is not considered complete. Literature studies are available that describe the mechanism of toxic action for cyclopropane carboxylic acid after limited repeated

- dose exposure and the most sensitive species for this effect is also known, but the NOAEL for this effect has not been identified.

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

The ADME data for aminocyclopyrachlor and aminocyclopyrachlor

- methyl in rats indicate rapid absorption, low tis sue bioavailability, and rapid clearance. The data further indicate that there is

near

- complete conversion of aminocyclopyrachlor

- methyl to aminocyclopyrachlor and no
metabolism of aminocyclopyrachlor

.

Pharmacokinetic studies in rats show that both aminocyclopyrachlor and aminocyclopyrachlor

methyl are rapidly absorbed

, with peak concentrations occurring in plasma and red blood cells ( RBC s) at 0.3

- 1.0 hours for aminocyclopyrachlor and at 0. 3

- 0.6 hours after dosing for aminocyclopyrachlor

- methyl. Aminocyclopyrachlor

- methyl was rapidly metabolized to aminocyclopyrachlor (within 30 minutes). No other metabolites were identified for either compound. The areas under the curve (AUCs) for both compounds scaled with dose, indicating that metabolic pr ocesses were not saturated.

Aminocyclopyrachlor was distributed primarily to the GI contents (47

- 67%) and GI tract (10

- 13%) after administration of a single dose of 25 or 500 mg/kg, with lower amounts present in the carcass (up to 5%), muscle (up to 2 %), skin (up to 1.4%) and blood (up to 1%). The apparent
lack of dose

- related increase in the tissue content of radiolabel suggested saturation of uptake. However, levels in all of these tissues declined to very low levels (<0.5%) by 72 hours. Tissue
dis tribution after repeated dosing at 25 mg/kg bw/day for 14 days was also examined. On Day 13 at 6 hours following dose administration, levels were again highest in the GI tract (0.16

- 0.22%) and GI contents in males/females (7.11

- 1.14%), but were reduced in magnitude compared to 6 hours following single

- dose administration of 25 mg/kg in the GI tract (1.36

- 1.42%) and GI contents (41.7% and 46.77%) in both sexes. Tissue distribution was similar with carcass > skin > blood, with all levels less than 0.5% with in 6 hours of dosing and less than 0.05% by 72 hours.

The (plasma) elimination half

- life of aminocyclopyrachlor of 5.6

- 5.7 hours was shorter than that
fo r aminocyclopyrachlor

- methyl at 8.7

- 13.3 hours. The majority of the administered dose of both compounds was excreted within 24 h, although elimination differed slightly. For amino

cyclopyrachlor, 35.8

- 53.71% was eliminated in the urine and 31.4

- 48.0% was eliminated in the feces. For aminocyclopyrachlor

- methyl, the majority was recovered in the urine ( 78.80

- 78.82% ) , with a smaller amount eliminated in the feces (1.72

- 4.57%). Bile duct cannulation experiments indicated a limited role for secretion of aminocyclopyrachlor or amino cyclopyrachlor

- methyl into the bile.

Metabolite identificati on studies in urine, feces, and bile after administration of amino

cyclopyrachlor confirmed that aminocyclopyrachlor is not metabolized. Aminocyclopyrachlor

methyl was completely metabolized to aminocyclopyrachlor in urine and feces. In bile, <1%Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 17 of 78 of am inocyclopyrachlor

- methyl was not metabolized, with the majority (>99%) metabolized to aminocyclopyrachlor.

Neither aminocyclopyrachlor n or aminocyclopyrachlor

- methyl was eliminated as expired air. No sex differences in absorption, distribution, metabol ism, or excretion were observed for either aminocyclopyrachlor or aminocyclopyrachlor

- methyl.

Evidence that aminocyclopyrachlor can be excreted into milk was not available in rat metabolism studies. However, a metabolism study with aminocyclopyrachlo r

- methyl in goats identified aminocyclopyrachlor residues in milk.

4.3 Toxicological Effects

Aminocyclopyrachlor There are no target organs of toxicity for aminocyclopyrachlor. Mild systemic toxicity is
observed via the oral route with repeated exposures at very high (limit) doses. This systemic toxicity is limited to decreased bod y weight and body weight gain. There is no appreciable increase in the severity of these effects with time. The most sensitive species is the rat.

Toxic effects of aminocyclopyrachlor via the oral route of exposure (in the diet) in subchronic dietary studies in rats were limited to decreases in body weights (≤10%), body weight gains, food consumption, and food efficiency in both sexes when these compounds were at th e limit dose (1000 mg/kg/day). Chronic dietary studies resulted in similar effects at the limit dose, with no appreciable increase in severity over time. No treatment

- related tumors were observed in carcinogenicity studies.

Subchronic dietary exposur e of dogs to aminocyclopyrachlor resulted in no adverse effects at doses up to the highest dose, which was almost half the limit dose (426/388 mg/kg/day in males/females) in both sexes. A subsequent dietary study in dogs in which the dose was
increased to the limit dose and the duration of exposure was extended to one year showed no evidence of toxicity at the limit dose. Similarly, subchronic and chronic dietary exposure studies
in mice showed no adverse effects at the limit dose. No treatment

- related t umors were observed in mice in carcinogenicity studies.

No evidence of neurotoxicity in rats was observed after acute (gavage) or subchronic (dietary) oral administration of aminocyclopyrachlor at the limit dose (2000 mg/kg for acute neurotoxicity, 1000 mg/kg for subchronic neurotoxicity). Aminocyclopyrachlor showed no evidence of immunotoxicity with dietary exposure at the limit dose (1000 mg/kg) in mice or rats.

There were no adverse effects of aminocyclopyrachlor on pre na tal development or mater na l health in rats after oral (gavage) administration to dams at the limit dose (1000 mg/kg/day)

. A dministratio n of aminocyclopyrachlor to rabbit dams via oral gavage at the limit dose resulted
in one treatment

- related death and two abortions that were co nsidered secondary to maternal weight losses of 17

- 19%. These maternal weight losses occurred over a period of approximately
5

- 7 days. No developmental effects were observed in rabbit kits. There were no effects ofAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 18 of 78 aminocyclopyrachlor on reproduction an d fertility in rats at the limit dose. Toxicity in parental rats and offspring was limited to decreases in body weights at the limit dose. A one

- generation reproductive toxicity study in rats for aminocyclopyrachlor

- methyl also showed no adverse
effects on reproduction at the limit dose.

There was no evidence of toxicity when aminocyclopyrachlor was administered via the dermal route in rats at the limit dose for 28 days. No repeated

- exposure inhalation studies are available for aminocyclopyrachlor.

Aminocyclopyrachlor has low acute toxicity by all routes of exposure (oral, dermal, inhalation) in rats and does not cause skin irritation in rats or skin sensitization in guinea pigs. However, aminocyclopyrachlor does cause mild eye irritation in rats. A full genotoxicity panel of in vitro mutation assays in bacteria and mammalian cells as well as in vitro and in vivo studies for chromosomal aberrations showed that aminocyclopyrachlor is not genotoxic in the presence or
absence of metabolic activation.

Aminocyclopyrachlor

- methyl The toxicity database for aminocyclopyrachlor

- methyl is being bridged with aminocyclopyrachlor. Support for bridging via the oral route is provided by metabolism studies and by a full acute toxicity database and comparative t oxicity studies with common endpoints for repeated exposures. Metabolism studies via the oral route show that that aminocyclopyrachlor

methyl is rapidly converted to aminocyclopyrach lor. Acute toxicity studies resulted in the same toxicity category class ifications for aminocyclopyrachlor

- methyl as aminocyclopyrachlor for all
studies. A subchronic dietary exposure study conducted in rats with aminocyclopyrachlor

methyl showed effects of decreased body weight and body weight gain at the limit dose that we re similar those observed with aminocyclopyrachlor. Similarly, a n oral one

- generation reproduction study in rats that includes a modified functional observational battery and a subchronic dietary study in rats showed no evidence of reproductive, developme ntal, or neurotoxicity at the limit dose

. The results of these studies, together with decreased body weight and body weight gain at the limit dose, were similar to aminocyclopyrachlor. Aminocy c lopyrachlor

- methyl was also negative in a genotoxicity test (bacterial mutation) at doses similar to those tested for aminocyclopyrachlor.

Cyclopropane carboxylic acid The toxicity of the environmental photodegradate of aminocyclopyrachlor, cyclopropane

ca rboxylic acid, was also examined because struc tural alerts for toxicity for this compound were identified by structural activity relationships (SAR) in an Agency Memorandum ( D370638,
10/15/2009 ). The re is a substantial amount of information on the toxicity of cyclopropane carboxylic acid in the open scientific literature that identifies the target organ of toxicity, the mechanism of toxicity, and the most sensitive species. As described in an other Agency
Memorandum ( D371431

, 12/13/2009 ), the mechanism of toxicity of cyclopropane carboxylic
acid has been identified by extensive pre

- clinical study of the anxiolytic drug candidate panadiplon, which is metabolized to cyclopropane carboxylic acid after oral administrat ion. This
mechanism is severe impairment of mitochondrial function by inhibition of beta oxidation of fatty acids in the mitochondria. This results in decreased energy production in diverse organs, with the liver being highly sensitive. The toxic endpoint of concern to the Agency forAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 19 of 78 cyclopropane carboxylic acid was identified as micro vesicular steatosis and necrosis in the liver

. Hepatic microvesicular s teatosis /necrosis can occur within 1

- 3 days and has also been observed
after 2 weeks. The most sensitive species in which to observe hepatic microvesicular
steatosis /necrosis resultin g from cyclopropane carboxylic acid exposure is the rabbit.

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

Aminocyclopyrachlor and aminocyclopyrachlor

- methyl

The FQPA Safety F a ctor for aminocyclopyrachlor and aminocyclopyrachlor

- methyl is reduced
to 1X.

Cyclopropane carboxylic acid

The FQPA Safety F actor for cyclopropane c arboxylic acid is retained at 10 X for acute dietary

exposures . This safety factor subsumes extrapolation from a LOAEL to a NOAEL fo r hepatic
steatosis/nec rosis in rabbits as well as a ( low ) potential for cyclopropane carboxylic acid to cause developmental toxicity that cannot be ruled out based on the available data

. A 10X FQPA Safety Facto r is co nsidered protective because hepati c steatosis/necrosis and any developmental toxicity would be caused by the same cellular mechanism. Therefore, protecting for hepatic steatosis/necrosis would protect for any potential developmental toxicity resulting from very low dietary exposures to cy clopropane carboxylic acid. For chronic dietary exposures, the FQPA Safety Factor is increased from 10X to 30X due to an increase in duration of exposure while still using the same study utilized for the acute endpoint (hepatic steatosis /necrosis in r abbits ). This
3

- fold increase in the magnitude of the FQPA Safety Factor for extrapolation from acute to chronic duration is considered protective because the duration of this study was 14 days with the
dose administered as a bolus (via gavage). Because the exposures in this study were repeated
and a bolus dose was used that would over

- estimate dietary exposure, the severity of the effects of hepatic steatosis/necrosis are not expected to vary substantially with time.

4.4 .1 Completeness o f the Toxic ology Database

Aminocyclopyrachlor and aminocyclopyrachlor

- methyl

The toxicity database is conside red adequate for assessing the sensitivity of infants and children under FQPA and selecting endpoints for di etary exposure to aminocyclopyra chlor and aminocyclopyrachlor

- methyl. Therefore, no additional database uncertainty factors are needed.

Cyclopropane carboxylic acid

The toxicity database for cyclopropane carboxylic acid is adequate

. There is a substantial amount of toxicological information for cyclopropane carboxylic acid available in the open
scientific literature that identifies the target organ of toxicity, the mechanism of toxicity, and the most sensitive species. The FQPA Safety Factor for acute and chronic exposures accoun ts for residual uncertainties in the toxicity database.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 20 of 78 4.4.2 Evidence of N eurotoxicity

Aminocyclopyrachlor and aminocyclopyrachlor

- methyl

A developmental neurotoxicity study (DNT) is not required because no evidence of developmental toxicity and because no evidence of neurotoxicity was obser ved in the toxicity
database. No evidence of peripheral or central nervous system toxicity was observed in an acute or subchronic neurotoxicity studies in rodents at the limit dose after exposure to
aminoc yclopyrachlor. Also, no evidence of neurotoxic ity was observed in a one

- generation reproduction study in rats with aminocyclopyrachlor

- methyl that included a modified functional observational battery.

Cyclopropane carboxylic acid

Based on the mechanism of toxicity for cyclopropane carboxylic acid that has been identified in the open scientific literature, the Agency does not expect the nervous system to be more sensitive
than the liver. Although there are n o studies available that directly investigate the effects of cyclopropane carboxylic acid o n the nervous system

, there is indirect evidence that the endpoint on which the Agency is regulating cyclopropane carboxylic acid (hepatic steatosis /necrosis ) is protective of the nervous syste m. First, the molecular mechanism underlying hepatic steatosis has been identified as inhibition of the metabolic pathway of beta oxidation of fatty acids in the mitochondria. This is a major, energy producing pathway in liver but not in brain. Sin ce the ketone bodies generated by this process in the liver are metabolized by the brain for energy, any brain effects from inhibition of this pathway would be secondary to liver effects

. Second,

c yclopropane carboxylic acid is a metabolite of panadiplo n, a drug that was develop ed to target the nervous system as an anxiolytic. Panadiplon failed in preclinical development, not as a result of neurotoxicity, but as a result of liver toxicity that was caused by cyclopropane carboxylic acid

. The result tha t it was the adverse effects of cyclopropane carboxylic acid on the liver but not the nervous system that limited development of this drug provides further support
that the liver is more sensitive than the brain. The Agency’s risk assessment is protective for hepatic steatosis /necrosis , and is therefore protective for any primary or secondary neurotoxicity that may result from cyclopropane carboxylic acid.

4.4.3 Evidence o f Sensitivity/Su sceptibility in the Developing o r Young Animal

Aminocyclopyrachl or and aminocyclopyrachlor

- methyl

There was no evidence of prenatal toxicity resulting from exposure to aminocyclopyrachlor. There is no evidence of increased susceptibility following in utero exposure to aminocyclopyrachlor in rats or rabbits in develop mental toxicity studies, which showed no adverse effects in offspring at the limit dose. An increase in abortions in maternal rabbits was observed at the limit dose, but th ese abortions were considered secondary to severe decreases in
maternal body weight . There was also no evidence of increased susceptibility of offspring toAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 21 of 78 aminocyclopyrachlor or aminocyclopyrachlor

- methyl in reproduction and fertility studies in rats, for which adverse effects were limited to decreased body weights in both maternal animals and offspring at the limit dose. Therefore, the young are not consi dered more susceptible than adults
to adverse effect s from aminocyclopyrachlor or aminocyclopyrachlor

- methyl.

Cyclopropane carboxylic acid

There is no information available that directly investigates the effects of this photo degradate during development or on young animals. However, there is indirect e vidence from the open
scientific literature that the young may potentially be more sensitive to the metabolic effects of cyclopropane carboxylic acid

, and this evidence does not allow this potential sensitivity to be
ruled out

. T his evidence is provided b y inherited conditions , specifically inborn errors of metabolism, that result in an effect (compromised metabolism of fatty acids) that is qualit atively
similar to that of cyclopropane carboxylic acid (inhibition of beta oxidation of fatty acids).
These i nborn error s of metabolism result in energy deficiencies during periods of fasting, and it is known that developing/young children are more sensitive to these effects than pregnant
women or adults. T he magnitude of this effect would be much more severe in the inherited case
than for cyclopropane carboxylic acid . This is because fatty acid oxidation is almost completely compromised in the inherited case and other cellular processes are also impacted , whereas only
beta oxidation of fatty acid s would be impacted for cyclopropane carboxylic acid, and the magnitude of this impact is anticipated to be negligible for the estimated ( low

- level ) dietary

exposures.

4.4.4 Residual Uncertainty in the Exposure Datab ase

Aminocyclopyrachlor and aminocycl opyrachlor

- methyl

The dietary exposure assessment is based on conservative, health

- protective assumptions that ensure that exposures to aminocyclopyrachlor and aminocyclopyrachlor

- methyl are not underestimated. These assumptions include tolerance

- level r esidues and 100% crop treated estimates for all commodities. Furthermore, conservative, upper

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

Cyclop ropane carboxylic acid

The dietary exposure assessment is based on conservative, health

- protective assumptions that ensure that exposures to cyclopropane carboxylic acid 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 through drinking water and residential sources, such that these exposures have not been
underestimated.

4.5 Toxicity Endpoint and Point of D eparture Selections

4.5.1 Dose

- Response AssessmentAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 22 of 78 Aminocyclopyrachlor The only endpoint identified in the toxicity database for aminocyclopyrachlor was decreased body weight . The only species in which this effect was observed was the rat. The dose

- response for this effect is very shallow, with adverse effects on body weight occurring only at the limit
dose with subchronic or chronic administration. There is no acute endpoint because body weight decreases occurring from aminocyclo pyrachlor are a repeated

- dose effect. The dose

- levels at which no adverse effects were identified were similar between subchronic and chronic studies, at about 380 mg/kg bw/day and 2 80 mg/kg bw / day, respectively. This difference may be only apparent as a consequence of dose spacing in th ese studies, or may be due to an increase in the severity of this effect with time. Selection of endpoints based on decreased body weight for a rat study of an appropriate duration relevant to the exposure scenario of inte rest is therefore protective of all adverse effects.

Cyclopropane carboxylic acid An acute RfD of 0.0026 mg/kg/day and a chronic RfD of 0.00087 mg/kg/day were determined
based on a 2

- week oral (gavage) study conducted in rabbits that was published in t he open scientific literature ( MRID 47916803 )

. This study investigated the toxicity of panadiplon, which is metabolized to cyclopropane carboxylic acid (the toxic entity) in the most sensitive species (the rabbit). The most sensitive endpoint was hepatic steatosis with a dose

- related increase in the incidence and severity of liver damage. No NOAEL was identified, and so a LOAEL of 10 mg/kg/day was used as the point of departure (POD). This POD for panadiplon was converted to
a POD of 2.5 5 mg/kg/day for cyclopropane carboxylic acid, based on molecular weights (337.35 g/mole for panadiplon and 86.09 g/mole cyclopropane carboxylic acid) and a mole ratio of 1 mole of cyclopropane carboxylic acid/mole panadiplon, and assuming 100% conversion of panadiplon to cyclopropane carboxylic acid.

4.5.2 Recommendation for Combining Routes of Exposures for Risk Assessment

The same toxicity endpoint has been identified for oral, dermal, and inhalation exposur es to aminocyclopyrachlor. This en dpoint i s decreased body weight, and was the only endpoint identified in the hazard database for this chemical. Moreover, this same endpoint is used for exposures by all relevant routes to aminocyclopyrachlor

- methyl due to evidence that aminocyclopyrachlor

- methyl is rapidly converted to aminocyclopyrachlor in the body. No dermal hazard was identified at the limit dose. However, oral and inhalation routes of exposure should be combined based on use of the same endpoint for aminocyclopyrachlor/ aminocyclopyrachlor

- methyl for any scenarios in which simultaneous exposures via these routes is anticipated.

The only anticipated route of exposure to the environmental photo degradate cyclopropane carboxylic acid is oral (in drinking water). Since the toxicity of cyclo propane carboxylic acid is biologically and quantitatively different than aminocyclopyrachlor / aminocyclopyrachlor

methyl, coincident oral exposures to these chemicals should not be combined.

4.5.3 Cancer Classification and Risk Assessment Recommendatio nAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 23 of 78 Aminocyclopyrachlor The carcinogenic potential of aminocyclopyrachlor was examined in chronic dietary studies in rats and mice, a full battery of in vitro and in vivo genotoxicity assays, and by structure

- activity relationships (SAR). Chronic administ ration of aminocyclopyrachlor in rats and mice did not

cause treatment

- related tumors at doses up to the limit dose. Genotoxicity assays were negative. SAR analysis in conjunction with experimental data indicated no bas i s for concern. In
accordance wi th the EPA's Final Guidelines for Carcinogen Risk Assessment 1 , the aminocyclopyrachlor was classified as ―Not L ikely to be Carcinogenic to Humans‖ ( CARC Memo, J. Kidwell, November 9, 2011). Therefore, there is no cancer risk associated with aminocyclopyrachlor.

Cyclopropane carboxylic aci d No chronic dietary studies have been performed to assess the carcinogenic potential of cyclopropane carboxylic acid. No structural alerts for genotoxicity or carcinogenicity were observed in SAR analysis, and there are no reports of tumorgenic responses to cyclopropane carboxylic acid or panadiplon (which is metabolized to cyclopropane carboxylic acid) in the open scientific literature.

1 Guidelines for Carcinogen Risk Assessment. Risk Assessment Forum, US EPA, Washington, DC. EPA/630/P

03/001F. March 2005.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 24 of 78 4. 5

. 4 Summary of Po ints of Departure and Toxicity Endpoints Used in Human Risk
Assessment

Aminocyclopyrachlor
Table 4

. 1 Summary of Toxicol ogical Doses and Endpoints for Aminocyclopyrachlor for Use in Dietary and Non

- Occupational Human Health Risk Assessments

Exposure/
Scenario Point of

Departure Uncertainty/FQPA

Safety Factors RfD, PAD,

Level of
Concern for
Risk
Assessment Study and Toxicological Effects

Acute Dietary (General Population, including
Females 13

- 49 years of age ) NA

( No hazard

was identified ). NA NA Acute Neurotoxicity

- rat (870.6200a)

NOAEL = 2000 mg/kg/day. No acute neurotoxicity.

Chronic Dietary (All Populations) NOAEL=

279 mg/kg/day UF A = 10 x

UF H =10 x FQPA SF= 1 x Chronic RfD

= 2.79 mg/kg/day

cPAD = 2.79 mg/kg/day Combined chronic toxicity/

carcinogenicity

- rat

LOAEL = 892/957 mg/kg/day based on mild decreases in body weight/body weight gain

.

Incidental Oral
Short

- / Inter

me d i ate Term (1

- 30 days /1

- 6
months ) NO AEL=

350 mg/kg/day UF A = 10 x

UF H =10 x FQPA SF= 1 x Residential

LOC for
MOE = 100 90

- Day Oral Toxicity Feeding

- rat

(870.3100)

LOAEL = 1045 mg/kg/day (limit dose)
based on decreased body weights, body weight gains, food consumption, and food efficiency in both sexes

.

Dermal
Short

- /Inter

mediate Term (1

- 30 days /1

- 6
months ) NA

( No hazard

was identified ) NA NA 28

- Day Dermal Toxicity

- rat (870.3200) NOAEL = 1000 mg/kg/day. No dermal toxicity.

Inhalation
Short

- /Inter

mediate Term (1

- 30 days /1

- 6
months ) NO AEL=

350 mg/kg/day UF A = 10 x

UF H =10 x Residential

LOC for
MOE = 100 90

- Day Oral Toxicity Feeding

- rat

(870.3100)

LOAEL = 1045 mg/kg/day (limit dose)
based on decreased body weights, body weight gains, food consumption, and food efficiency in both sexes

.

Cancer (oral, dermal, inhalation) ―Not likely‖ to be carcinogenic in humans

Point of Departure (POD) = A data point or an estimated point that is derived from observed dose

- response data and used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UF A = extrapolation from animal to human (interspecies). UF H = potential variation in sensitivit y among members of the human population (intraspecies). UF L FQPA SF = FQPA Safety Factor. PAD = population adjusted dose (a = acute, c = chronic). RfD = reference dose. MOE = margin of exposure. LOC = level of concern. N/A = not applicable.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 25 of 78 Table 4. 2 Summary of Toxicological Doses and Endpoints for Aminocyclopyrachlor for Use in Occupational Human Health Risk Assessments

Exposure/
Scenario Point of

Departure Uncertainty

Factors Level of Concern

for Risk
Assessment Study and Toxicological Effects

Dermal
Short

- /Inter

mediate Term (1

- 30 days /1

- 6
months ) NA

( No hazard

was identified ) NA NA 28

- Day Dermal Toxicity

- rat (870.3200) NOAEL = 1000 mg/kg/day. No dermal toxicity.

Inhalation
Short

- /Inter

mediate Term (1

- 30 days /1

- 6
months ) NO AEL=

350 mg/kg/day UF A = 10 x

UF H =10 x LOC for MOE =

100 90

- Day Oral Toxicity Feeding

- rat

(870.3100)

LOAEL = 1045 mg/kg/day (limit dose)
based on decreased body weights, body weight gains, food consumption, and food efficiency in both sexes

.

Cancer (oral, dermal, inhalation) ―Not likely‖ to be carcinogenic in humans

Point of Departure (POD) = A data point or an estimated point that is derived from observed dose

- response data and used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UF A = extrapolation from animal to human (interspecies). UF H = potential v ariation in sensitivity among members of the human population (intraspecies). MOE = margin of exposure. LOC = level of concern. N/A = not applicable.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 26 of 78 Cyclopropane carboxylic acid
Table 4. 3 Summary of Toxicological Doses and Endpoints for the Enviro nmental Degradate, IN

- V0977 (Cyclopropane Carboxylic Acid) for Use in Dietary Human Health
Risk Assessments

Exposure/
Scenario Point of

Departure Uncertainty

Factors RfD, PAD,

Level of
Concern for
Risk
Assessment Study and Toxicological Effects

Acute Dietary (All Populations) LOAEL =

2.55 mg/kg/day cyclopropane carboxylic
acid UF A = 10x

UF H = 10x FQPA SF 1

= 10x RfD=

0.0 26 mg/kg/day

aPAD=0.0026 mg/kg/day Rabbit study

MRID 47916803 (1998)
Non

- guideline, oral (gavage) for 14 days 0, 10, 20 mg/kg/day (panadiplon) 0, 2.55, 5 mg/kg/day (cyclopropane carboxylic acid) LOAEL = 10 mg/kg/day based on hepatic
steatosis

Chronic Dietary Long

- term (>6 months) LOAEL =

2.55 mg/kg/day cyclopropane carboxylic
acid UF A = 10x

UF H = 10x FQPA SF 2 =30x RfD=

0.0087 mg/kg/day

cPAD=0.00087 mg/kg/day Rabbit study

MRID 47916803 1998)
Non

- guideline, oral (gavage) for 21 days 0, 10, 20 mg/kg/day (panadiplon) LOAEL = 10 mg/kg/day based on hepatic
steatosis

Cancer (oral) NA Point of Departure (POD) = A data point or an estimated point that is derived from observed dose

- response data and used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no observed adverse effect level. LOAEL = lowes t 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). UF L = use of a LOAEL to extrapolate a
NOAE L. UF S = use of a short

- term study for long

- term risk assessment. UF DB = to account for the absence of key data (i.e., lack of a critical study). MOE = margin of exposure. LOC = level of concern. N/A = not applicable.

1 The FQPA SF of 10X is a composite of UF L and UF DB . 2 The FQPA SF of 3 0X is a composite of UFL

, UF DB , and UF S
.

5.0 Dietary Exposure and Risk Assessment

5.1 Metabolite/Degradate Residue Profile

5.1.1 Summary of Plant and Animal Metabolism Studies

The nature of the residue in g rass and livestock is adequately understood for the purposes of this petition. Metab olism studies in grasses , rotational crops, and livestock were performed using [2

- pyrimidinyl

14 C] aminocyclopyrachlor

- methyl , which is considered sufficient to evaluate the metabolism of aminocyclopyrachlor and the aminocyclopyrachlor potassium salt. Because grass is not a significant feed stuff for poultry, a hen metabolism study is not required at this time; however, a hen metabolism study may be needed to support f uture uses on additional

crops.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 27 of 78 Primary crops (grasses) Aminocyclopyrachlor

- methyl was identified in grass from all harvest intervals; residues declined from 24.7% TRR (3.86 ppm) at 0 days after application ( DAA ) to 8.6% total radioactive residues ( TRR ) (0.211 ppm) at 60 DAA. Aminocyclopyrachlor was the major identified residue in grass samples at all harvest intervals, accounting for 32.9

- 67.7% TRR (0.805

- 10.5 ppm). Several
minor metabolites were identifie d, including IN

- LXT69, IN

- QFH57, IN

- QGC48, IN

- Q3007, and
IN

- V0977. IN

- LXT69 was identified at all sampling intervals, accounting for 4.2

- 6.1% TRR (0.138

- 0.769 ppm); the remaining metabolites were each present at ≤ 4.1% TRR.

Rotational crops Aminocyclopy rachlor accounted for 83.1% and 80.1% TRR (0.014 and 0.021 ppm) in 30

- and
60

- days after treatment ( DAT ) immature cabbage and for 60.0% and 60.6% TRR (0.014 and 0.008 ppm) in 30

- and 60

- DAT mature cabbage following application at 0.067 lb ai/ A, and for 54.3% TRR (0.006 ppm ) and 83.0% TRR (0.010 ppm) in 300

- DAT immature and mature cabbage following application at 0.329 lb ai/A. In turnips, aminocyclopyrachlor accounted for 96.0% TRR (0.010 ppm) in 30

- DAT immature roots, for 57.3

- 83.1% TRR (0.010

- 0.017 pp m) in
30

- , 60

- , 120

- , and 300

- DAT immature tops following application at 0.067 lb ai/A, and for 40.5

- 59.3% TRR (0.004

- 0.007 ppm) in 60

- and 120

- DAT mature tu rnip tops; residues of aminocyclopyrachlor were 85.6% TRR (0.072 ppm) in 300

- DAT immature turnip to ps following application at 0.329 lb ai/A.

In corn, aminocyclopyrachlor accounted for 62.7

- 71.4% TRR (0.007

- 0.176 ppm) in 15

- , 120

- , and 300

- DAT forage following application at 0.067 and/o r 0.329 lb ai/A. In stover, aminocyclopyrachlor accounted for 71.9 % TRR (0.106 ppm) declining to 45.9% TRR (0.026 ppm) in 15

- , 120

- , and 300

- DAT samples following application at 0.067 lb ai/A, and for 58.0% TRR (0.151 ppm) in 300

- DAT samples following application at 0.329 l b ai/A. Residues of aminocyclopyrachlor in cobs accounted for 58.9% and 43.8% TRR (0.014 and 0.005 ppm) in 15

- DAT and 300

- DAT samples harvested following application at 0.067 and 0.329 lb ai/A, respectively. Residues in grain were 70.9

- 76.0% TRR (0.009

- 0.064 ppm) in 15

- , 120

- , and 300

- DAT samples foll owing application at 0.067 and/or 0.329 lb ai/A.

Aminocyclopyrachlor

- methyl was identified in immature and mature 30

- DAT cabbage, mature
60

- DAT cabbage, and immature 300

- DAT cabbage following application at 0.329 lb ai/A, and immature turnip roots at 3.3

- 4.6% TRR. In turnip tops, residues accounted for 15.9

- 17.8% TRR (0.002

- 0.003 ppm) in 30

- and 60

- DAT immature and mature tops, and for 5.6% TRR (0.001 ppm) in 120

- DAT immature tops. In 15

- DAT c orn forage and stover, aminocyclopyrachlor

methyl accounte d for 9.1

- 10.0% TRR (0.009

- 0.013 ppm); residues were identified at ≤ 5.4%
TRR in 15

- DAT grain and cobs, and 300

- DAT forage and/or stover and grain following application at 0.067 and/or 0.329 lb ai/A. Remaining residues were characterized as minor unknowns, including an apolar unknown and multicomponent minor unknowns, which
accounted for 5.0

- 6.9% TRR (0.012

- 0.018 ppm) and 16.3

- 25.3% TRR (0.038

- 0.064 ppm), respectively, in 300

- DAT corn forage and stover following application at 0.329 ppm, and together accoun ted for ≤ 0.014 ppm in all remaining matrices.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 28 of 78 Livestock Aminocyclopyrachlor

- methyl was not detected in excreta, milk, or any tissue. The parent acid, aminocyclopyrachlor, was the only compound identified and was found in all matrices. It was
the si ngle radiolabeled component detected in liver (65.7% TRR; 0.197 ppm), kidney (55.3% TRR; 0.925 ppm), omental fat (47.5% TRR; 0.005 ppm), renal fat (83.8% TRR; 0.013 ppm), and subcutaneous fat (80.7% TRR; 0.021 ppm). Aminocyclopyrachlor was detected in mus cle at 43.3% TRR (0.018 ppm) along with two minor unknowns (14.4

- 18.3% TRR; 0.006

- 0.008 ppm), and in milk at 15.9% TRR (0.004 ppm) along with three minor unknowns (7.4

- 29.5% TRR;
0.002

- 0.007 ppm). TLC analysis of liver and kidney extracts prior to SPE cl ean

- up (86.7% TRR and 98.3% TRR, respectively) confirmed that aminocyclopyrachlor was the only compound present in these samples.

5.1.2 Summary of Environmental Degradation

The following information on environmental stability and degradation products of aminocyclopyrachlor is summarized from EFED’s ― Drinking Water Degradates Identification
Memorandum for Aminocyclopyrachlor‖ M emorandum ( D368339 , August 25, 2009 ).

Aminocyclopyrachlor is non

- volatile and highly soluble in water, which indicates that dissipation of aminocyclopyrachlor in the environment is expected to occur predomi na ntly via runoff and leaching. Terrestrial field dissipation studies conducted in the continental United States and Canada showed that dissipation occurred with half

- lives ranging from 22 to 126 days. Aminocyclopyrachlor is characterized as being moderately mobile to slightly mobile in test soils
base d on the adsorption of aminocyclopyrach lor to test soils in b atch equilibrium studies. Aminocyclopyrachlor was detected at soil depths of 70

– 90 cm at 365 days, indicating that leaching of residues into groundwater ma y occur

.

Aminocyclopyrachlor is environmentally persistent in diverse env ironments. It persists in aerobic aquatic environments with a dissipation time of greater than 100 days and in aerobic
terrestrial environments with a half

- life of 315 days. It is also stable in anaerobic aquatic
environments with a half

- life of 1733 day s and in anaerobic terrestrial environments with a half

life of 6932 days.

The major route of degradation of aminocyclopyrachlor is abiotic via aqueous photolysis with a
half

- life of l.2 days in shallow, clear, and well

- lit natural (pH 6.2) water bodies a nd 7.8 days in pH 4 buffer solution. However, it is slowly photolyzed on soil, with a half

- life of 129 days. Aminocyclopyrachlor is stable to hydrolysis at pH 4 and 7. At pH 9, the half

- life was calculated to be at least 34.7 days, however, the possibil ity that the compound does not degrade at this pH
could not be ruled out due to mass balance issues.

The major environme ntal degradates of aminocyclopyrachlor include IN

- LXT69, IN

- QFH57,
IN

- Q3007, IN

- V0977, IN

- YY905, CO 2 and an unidentified aqueous photo product.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 29 of 78 5.1.3 Comparison of Metabolic Pathways

The metabolism of aminocyclopyrachlor and aminocyclopyrachlor

- methyl in grass, rotational

crops , livestock, and rats has been well characterized. In crops, livestock, and rats aminocyclopyrachlor

- methyl is converted to aminocyclopyrachlor. For mammals (livestock and rats), there is no further metabolism. However, in plants aminocyclopyrachlor i s subsequently decarboxylated to form the metabolite IN

- LXT69. Photo

- induced simultaneous elimination of hydrogen chloride and pyrimidine ring contraction (occurring as a minor pathway) yields the
imidazole

- nitrile metabolite, IN

- QGC48, which undergoes de methylation to form IN

- QFH57;
IN

- QFH57 may also be formed through photolysis of aminocyclopyrachlor . An additional minor pathway involves pyrimidine ring opening proceeding through the postulated intermediate IN

YY905, with subsequent oxidations to form t he amide and carboxylic acid compounds, IN

Q3007 and IN

- V0977, respectively.

5.1.4 Residues of Concern Summary and Rationale

Plants and livestock For grass and rotational crops and livestock commodities, the Residues of Concern Knowledgebase Subcommittee ( ROCKS ) recommended that aminocyclopyrachlor and aminocyclopyrachlor

- methyl be the residues of concern for both the tolerance expression and the risk assessment ( Memorandum D393619, September 22, 2011). Although additional metabolites

were me asured in grass crop field trials, they were all present at low levels, ranging from less than the Level of Quantification (LOQ) to 0.11 ppm. Results from metabolism and feeding
studies show that aminocyclopyrachlor is the major residue in ruminant commo dities. Although quantifiable residues of aminocyclopyrachlor

- methyl are not expected in edible livestock commodities, its inclusion as a residue of concern is recommended for the convenience to have the same tolerance expression for all re levant agricultu ral commodities. The analytical method
determines both the ester and acid in the same analysis. Based on these considerations, the ROCKS recommended that aminocyclopyrachlor and aminocyclopyrachlor

- methyl are included
for risk assessment and tolerance en forcement purposes.

Drinking water For drinking water, the ROCKS recommended that residues of concern are aminocyclopyrachlor and cyclopropane carboxylic acid (IN

- V0 977) in surface water and amin ocyclopyrachlor in ground water ( Memorandum D370638, October 15, 2009). Four of the degra dates (IN

- LXT69,
IN

- QFH57, IN

- V0977, IN

- YY905) were excluded as residues of concern. However, structura l alerts and studies in the general scientific literature indicated that the environmental degra date
IN

- V0977 (cycl opropane carboxylic acid) ha s a different mode of to xicity than the parent compound. T he mechanism of toxic action is impairment of mitochondrial function by inhibiting the beta oxidation of fatty acids in the liver , resulting in microvesicular steatosi s (accumulation of small fat droplets in cells) in the liver that is often accompanied by liver necrosis and inflammation, decreased hepatic glycogen, and d ecreased blood glucose levels. The time of onset, dose

- response, and species sensitivity for this e ffect also differ from aminocyclopyrachlor ( Memorandum D371431, December 31, 2009).Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 30 of 78 Table 5.1 Summary of Metabolites and Degradates to be included in th e Risk
Assessment and Tolerance Expression

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

Plants Primary Crop

(Grass Only) Aminocyclopyrachlor and

Aminocyclopyrachlor

- methyl 1 Aminocyclopyrachlor and Aminocyclopyrachlor

- methyl

Rotational Crop Aminocyclopyrachlor and

Aminocyclopyrachlor

- methyl Aminocyclopyrachlor and Aminocyclopyrachlor

- methyl

Livestock Ruminant Aminocyclopyrachlor and Aminocyclopyrachlor

- methyl Aminocyclopyrachlor and Aminocyclopyrachlor

- methyl

Poultry Not Applicable Not Applicable

Drinking water Aminocyclopyrachlor Cyclopropane carboxylic acid (IN

- V0977) Not Applicable

1 Aminocyclopyrachlor is 6

- amino

- 5

- chloro

- 2

- cyclopropyl

- 4

- pyrimidinecarboxylic acid ; Aminocyclopyrachlor

methyl is methyl 6

- amino

- 5

- chloro

- 2

- cyclopropyl

- 4

- pyrimidinecarboxylate

.

5 .2 Food Residue Profile

Adequate residue data are available to support dietary risk assessment and proposed tolerances

on grasse s and livestock commodities. However, rotational crop studies indicate that rotational crop tolerances may be needed. Adequate data are not a vailable to support a dietary assessment

or proposed tolerances on rotational crop commodities

. In the absence of the required limited field rotational crop trials, the labels must be revised to prohibit rotation to any crop other than grasses following application of aminocyclopyrachlor or aminocyclopyrachlor

- methyl. The revised label should include a rotational crop restriction (i.e. 1 year plantback interval (PBI)) in order for rotation not to be a condition of registration. If a shorter PBI is reque sted, rotational
data should be submitted.

A detailed description of crop field trials is provided in Memorandum D387442 ( April 18, 2012 ). Crop field trials (grass forage and hay) were conducted in North America. Residues were quantifiable and combi ned residues of aminocyclopyrachlor

- methyl and aminocyclopyrachlor
declined with increasin g PHI in grass forage and hay

. Storage stability studies on grass forage and hay sho w ed that residues of aminocyclopyrachlor and aminocyclopyrachlor

- methyl are
stable in/on grass forage and hay stored frozen (

- 20 °C) for up to 499

- 502 days (~16.5 months)

.

Cattle feeding studies showed that residues of aminocyclopyrachlor were quantifiable in milk
and cream but did not concentrate in cream

. Residues were highest in kidney, followed by fat, liver, and muscle. Storage stability studies showed that aminocyclopyrachlor and aminocyclopyrachlor

- methyl are stable when stored frozen (

- 20 °C) for up to 146 days (4.8 months) in milk, skim milk and cream; up to 138 days (4. 5 months) in muscle; and up to 147 days (4.8 months) in fat. Residues of aminocyclopyrachlor

- methyl were unstable in kidney and
liver and underwent biotransfor mation to aminocyclopyrachlor during frozen storage (

- 20 °C ). However, residues of ami nocyclopyrachlor were stable in liver up to 147 days (2.9 months) andAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 31 of 78 in kidney up to 88 days (2.9 months).

Residue studies in rotational crops indicate that residues of aminocyclopyrachlor may exceed the
0.01

- ppm trigger value in turnip tops and corn forage, stover, and grain at a 300

- day PHI following application of aminocyclopyrachlor at ~1x the maximum proposed seasonal application rate to grass. Based on the study results limited rotat ional crop field trials are required for aminocyclopyrachlor to establish PBIs and/or tolerances for rotational crops. Pending submission of the required limited field rotational crop trials, the labels must be revised to prohibit rotation to any crop oth er than grasses following application of aminocyclopyrachlor or aminocyclopyrachlor

- methyl.

HED does not require residue data for any processed commodities associated with grass. Therefore, data requirements for processed food and feed are not relevant to this tolerance petition.

5.3 Water Residue Profile

The previous drinking water ass essment for aminocyclopyrachlor (D368238, October 15, 2009) was updated for the proposed new use o n rangeland (D394887, November 3, 2011). It was also updated to refl ect no application of percent cropped area for non

- agricultural crops (e.g. turf).

Tier I screening models were employed for this assessment. For surface water, the FIRS T ( F QPA I ndex R eservoir S creening T ool) Version1.1.1 model was used to estimate drinking
water concentrations of aminocyclopyrachlor and cyclopropane carboxylic acid (IN

- V0977),
which were identified as residues of concern. For ground water, the SCI

- GROW model ( Screening Concentration in Ground Water Program Version 2.3 wa s used to predict the
maximum acute and acute concentrations of aminocyclopyrachlor present in shallow ground

water. Cyclopropane carboxylic acid (IN

- V0977) is not anticipated to be present in ground water due to the absence of sunlight (IN

- V0977 is a pho todegradate of aminocyclopyrachlor ).Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 32 of 78 Table 5. 2 Summary of Estimated Surface Water and Groundwater Concentrations for Aminocyclopyrachlor

Drinking
Water
Source (Model) Compound Use Method Application
Rate (interval
between applications) Adjustment

Factor 1 Peak Day

(acute)
Concentration (μg/L) Annual

Average (chronic)
Concentration (μg/L)

Surface Water (FIRST) Aminocyclopyrachlor Rangeland Aerial 2 app @
0.17 lb a.e./A (30 days)

1.0 34.28 21.32

Turf Granular 3 app @ 0.108
lb a.e./A (30 days) 31.36 19.50

Cyclopropanecarboxylic Acid (IN

- V0977) Rangeland

Granular 2 2 app @
0.01 lb a.e./A (30 days) 2.12 1.52

Turf 3 app @

0.006 lb a.e./A (30 days) 2.00 1.43

Ground Water (SCI

- GROW) Aminocyclopyrachlor Rangeland --- 2 app @
0.17 lb a.e./A (30 days) --- 42.2 <42.2

Turf 3 --- 3 app @ 0.108

a.e. /acre (30 days) --- 40.2 < 40.2

Bold values denote maximum Estimated Drinking Water Concentrations (EDWCs)

1 Adjustment Factors: PCA = Percent Crop Area

2 Granular method of application was selected for the degradate (Drift = 0.0% and Application Efficiency = 100%). All applications are liquid unless otherwise noted.

3 Model estimates obtained from D386238Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 33 of 78 5.4 Dietary Risk Assessment

5 .4.1 Description of Residue Data Used in Dietary Assessment

Aminocyclopyrachlor was registered only for non

- food uses. The current proposed use on grass and pastureland was descri bed in a memorandum (D387446, 04/18/2012) th at updates the previous assessm ent (D372779, 1/19/10) by adding this proposed new use and incorporating revised Estimated Drinking Water Concentrations (EDWCs). A chronic dietary exposure analysis (food and drinking water) was performed in order to support a Section 3 request f or the new use of aminocyclopyrachlor on livestock commodities after grazing on treated grass and pastureland The analysis was performed using the Dietary Exposure Evaluation Model DEEM

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

- 1996 along with a supplemental children’s survey from 1998. The analysis included tolerance
residue levels and a 100% crop treated assumption

. For the chronic exposure to aminocyclopyrachlor the ground water EDWC of 42.2 ppb was used

.

D ietary assessments for the drinking water degradate, cyclopropane carboxylic acid, were also performed using the revised EDWCs. An annual peak of 2.12 ppb was used for the acute dietary assessment and an annual average of 1.52 ppb was used for the chronic dietary

assessment

.

5.4.2 Percent Crop Treated Used in Dietary Assessment Percent crop treated values were not estimated. A default of 100% was used.

5.4.3 Acute Dietary Risk Assessment

There is no acute dietary risk for aminocyclopyrachlor because no hazard was identified. For cyclopropane carboxylic acid, t he most highly exposed population subgroup is All Infants (<1

yea r old), with risk estimates of 16% of the acute population adjusted dose (aPAD) (See Table
5.4 ). T his is below HED’s level of concern for all population subgroups (<100% (aPAD) acute Population Adjusted Dose).

5.4.4 Chronic Dietary Risk Assessment

A chronic dietary analysis was conducted for both aminocyclopyrachlor and cyclopropane carboxylic acid. For aminocyclopyrachlor, the most highly exposed population subgroup is All Infants (<1 year old), with risk estimates of <1 % of the acute population adjusted dose ( c PAD) (see Table 5.3 ) . For the cyclopropane carboxylic acid , the most highly exposed population subgroup is All Infants (<1 year old), with risk estimates of 12% of the chronic population adjusted dose ( c PAD) (see Table 5.4 ) . These risk estimates for aminocyclopyrachlor and cyclopropane carboxylic acid are b elow HED’s level of concern for all population subgroups (<100% ( c PAD) acute Population Adjusted Dose).Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 34 of 78 The most conservative (e.g. largest magnitude) estimates of chronic dietary e xposure to aminocyclopyrachlor for children and adults were used to determine aggregate risk from exposure to ami n ocyclopyrachlor from residential and dietary scenarios in Section 7.0. These
estimates for adults were 0.001054 mg/kg bw/day determined for t he General U.S. Population
and 0.003184 mg/kg bw/day determined for All Infants (< 1 year old) in Table 5.4.1.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 35 of 78 5.4.5 Cancer Dietary Risk Assessment

No cancer dietary risk assessment was performed because aminocyclopyrachlor was classified as ―Not Lik ely to be Carcinogenic to Humans‖ ( CARC Memo, J. Kidwell, November 9, 2011).

5.4.6 Summary Table s

Table 5.3 Summary of Dietary Exposure and Risk for Aminocyclopyrachlor and

Aminocyclopyrachlor

- methyl (Food and Drinking Water)

Population Subgroup* Acute Dietary Chronic Dietary Cancer

Dietary Exposure (mg/kg/day) % a PAD Dietary Exposure (mg/kg/day) % c PAD Dietary Exposure (mg/kg/day) Risk

General U.S. Population

Not applicable: No acute dietary endpoint was
identified 0.001054 1 <1 Not Applicable at this
time

. All Infants (< 1 year old) 0.00 3184 2 <1

Children 1

- 2 years old 0.00 2122 <1

Children 3

- 5 years old 0.001771 <1

Children 6

- 12 years old 0.001171 <1

Youth 13

- 19 years old 0.000786 <1

Adults 20

- 49 years old 0.000922 <1

Adults 50+ years old 0.000959 <1

Females 13

- 49 years old 0.000919 <1

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

1 Used for Adult Male and Adult Female in Dietary MOE calculations f or aggregate risk in Table 7.2

. 2 Used for Child Dietary MOE calculations f or aggregate risk in Table 7.2

.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 36 of 78 Table 5.4 Summary of Dietary Exposure and Risk for Aminocyclopyrachlor Metabolite

Cyclopropane Carboxylic Acid (IN

- V0977) (Drinking Water Only)

Population Subgroup* Acute Dietary
95 th percentile Chronic Dietary Cancer

Dietary Exposure (mg/kg/day) % a PAD Dietary Exposure (mg/kg/day) % c PAD Dietary Exposure (mg/kg/day) Risk

General U.S. Population 0.000111 4.3 0.000032 3.7 Not applicable at this
time

. All Infants (< 1 year old) 0.000 418 16 0.000 105 12

Children 1

- 2 years old 0.0001 74 6.7 0.000 048 5.5

Children 3

- 5 years old 0.000159 6.1 0.000045 5.1

Children 6

- 12 years old 0.000111 4.3 0.000031 3.5

Youth 13

- 19 years old 0.000090 3.5 0.000023 2.7

Adults 20

- 49 years old 0.000103 4.0 0.000030 3.4

Adults 50+ years old 0.000093 3.6 0.000031 3.6

Females 13

- 49 years old 0.000 103 4.0 0.000030 3.4

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

6.0 Residential (Non

- Occupational) Exposure/Risk Characterization

No new residential uses for aminocyclopyrachlor are proposed in this action. The Agency has previously assessed exposures and risks for residential uses of aminocyclopyrachlor for non

- food
uses on turf (Memorandum D369057, March 17, 2010). No risks of c oncern were identified for application to lawn/turf from short

- term and intermediate

- term inhalation exposures during ope n mixing/loading and applying when using a LOC of 100. Although a point of departure from an
oral study was used to assess residential handler inhalation risks for aminocyclopyrachlor, HED
does not believe this assessment is under

- protective of adult handlers. MOEs calculated for residential handlers were all ≥ 7,300,000 and thus provided an ample ma rgin of safety to account for any uncertainties in route

- to

- route extrapolation. Post

- application hand

- to

- mouth, object

- to

mouth, and soil in gestion exposures and risks were also assessed for children and no risks ofAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 37 of 78 concern were identified when using a L OC of 100. Dermal risks were not assessed because no dermal endpoint was identified. The data tables containing these risk estimates are reproduced below, and the most conservative estimat es are labeled with an asterisk (*).

Table 6.1 Summary of Re sidential Short and Intermediate

- Term Risk Assessment for
Aminocyclopyrachlor (Acid and Potassium Salt) and Aminocyclopyrachlor

- Methyl *

Exposure Scenario Application

Rate

(lb ae/A) Area

Treated

(A/day) Inhalation

Unit

Exposure

( g/lb ai ) Inhalation

Daily Dose

(mg/kg/day) Inhalation

Short/Intermediate

Term MOE

Open Mixing, Loading,

and Applying

Low Pressure

Handwand

(Soluble Liquid)

0 .07 0.5 30 0.0000 15 23,000,000

Open Mixing, Loading,

and Applying

Hose

- end Sprayer

(Dry Flowable) 17 0.0000 085 41,200,000

Open Mixing, Loading,

and Applying

Belly Grinder

(Granular) 0.10 62 0.000048 7,300,000 **

*Designated as Table 6.1.1 in D369057, March 17, 2010. **Most conservative estimate for use in aggregate risk calculations (MOE Inhalation Residential Exposure, Adult Male, Adult Female in Table 7.2). ae=acid equivalent; A=acre; ai=active ingredientAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 38 of 78 T able 6.2 Residential Risk Estimates for Post

- Application Exposure to
Aminocyclopyrachlor (Acid an d Potassium Salt) and Aminocyclopyrachlor

- Methyl for

Children 3

- 6 Years of Age*

Exposure Scenario TC

cm 2 /hr Route of

Exposure Application Rate MOE at Day 0 Combined MOE 1

Ingestion

Outdoors S

- Term Int

- Term

Hand to Mouth Activity

on Turf

N/A Oral 0.1 234,000 ** 493,000

32 2,000 Object to Mouth

Activity on Turf 938,000

Soil Ingestion 70,000,000
*Designated as Table 6.2.1: Toddler Residential Risk Estimates for Post

- Application Exposure to Aminocyclopyrachlor (Acid and Potassium Salt) and Aminocyclopyrachlor

- Methyl in Memorandum D369057, March 17, 2010. Note that ―Toddler‖ has been changed to Ch ildren 3

- 6 years of age. **Most conservative estimate for use in aggregate risk calculations (MOE Oral Residential Exposure, Child in Table 7.2).

Aminocyclopyrachlor is persistent in soil and has the potential to accumulate with repeated applications. In a recent assessment (Memorandum D38477 , 04/18/2012 ), t he Agency assessed
intermediate

- term risk from soil ingestion by using a yearly application rate of 0.56 lb ai/A for aminocyclopyrachlor , which is double the maximum single rate of 0.2 8 lb ai/A. This is a conservative approach that would address incidental oral risk due to the potential build up of aminocyclopyrachlor in the soil and woul d also be protective for long

- term soil ingestion

. The same oral endpoint and LOC for MOE of 100 were utilized. No risk s of concern were identified (MOE = 1.25 x 10 7 ).

Importantly, this risk estimate for intermediate

- /long

- term soil ingestion is 50

- fold less
conservative than the short

- term Hand

- to

- Mouth Activity on Turf estimate of 234,000 in Table
6.2. It is this latter (more conservative) estimate that is used t o determine aggregate risk

.

6.1 Combined Exposure

The potential for combined exposure to aminocyclopyrachlor by both children and adu lts was considered in this assessment. No endpoint has been identified for dermal toxicity due to lack of toxicity at the limit dose. The same toxicity endpoint was identified for inhalation and incidental oral exposures . However, HED anticipates that a dults would have only inhalation exposures that would be limited to application and that children would have only oral exposures that would be limited to post

- application. Therefore, HED considers it unlikely that simultaneous exposure to aminocyclopyr achlor would occur for non

- food routes and so routes of exposure were notAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 39 of 78 combined for non

- food risk assessments. However, HED is aggregating inhalation and
incidental oral exposures with dietary exposures, as described in Section 7.0. Humans will be

exp os ed to cyclopropane carboxylic acid, an environmental degradate of aminocyclopyrachlor, only in drinking water. The toxicity endpoint for this degradate is qualitatively and quantitatively different from aminocyclopyrachlor

.

6. 2 Spray Drift

Spray drift is always a potential source of exposure to residents nearby to spraying operations. This is pa rticularly the case with aerial application, but, to a lesser extent, could also be a potential source of exposure from the ground application method empl oyed for aminocy c lopyrachlor

. 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 Agency’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 database submitted by the Spray Drift Task Force, a membership of U.S. pesticide registrants, and is developing a policy on how to appropriately apply the data and the AgDRIFT computer model to its risk assessments for 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 with specific products with si gnificant
risks associated with drift.

Although a quantitative residential post application inhalation exposure assessment was not performed as a result of pesticide drift from neighboring treated agricultural fields, an inhalation exposure assessment was performed for 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 inhalation 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 aggregate assessment, exposures from relevant sources are added together and compared to quantitative estimates of hazard (e.g., a NOAEL or PAD), or the risks themselves can be aggregated. When aggregating exposures and risks from various sources, HED considers both the route and duration of exposure. Alth ough there is potential for aggregate exposures to aminocyclopyrachlor from residential uses and dietary exposure, there is no potential for aggregate exposures to cyclopropane carboxylic acid because exposure can only occur in drinking water.Aminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 40 of 78 7.1 Ac ute Aggregate Risk

No acute dietary endpoint for aminocyclopyrachlor was identified. Therefore, acute aggregate risks from combined exposures to aminocyclopyrachlor were not assessed.

7.2 Short

- /Intermedia te

- Term Aggregate

In aggregating short

- term risk, HED considers background chronic dietary exposure (food + water) and short

- term, residential exposures. Aggregate risk for adults was determined by combining short/intermediate

- term inhalation risks during application of am inocyclopyrachlor
with risks from chronic dietary exposure. Aggregate risk for children was determined by combining risks from short

- term, post

- application incidental oral exposures with chronic dietary

exposure. These risk estimat es are summarized in Ta ble 7.2

. The LOC for all residential scenarios and dietary exposures was 100. No aggregate risks of concern were identified.

Table 7.2 Short

- / Intermediate Term Aggregate Risk Calculations for Aminocyclopyrachlor and Aminocyclopyrachlor

- methyl

Population Short

- or Intermediate

- Term Scenario

LOC for Aggregate
Risk 1 Dietary

MOE 2 M OE Oral

Residential Exposure 3 M OE

Dermal
Residential Exposure 4 M OE

Inhalation
Residential Exposure 5 Aggregate

MOE (food, water, and residential) 6

Adult Male 100 2 65 ,000 NA NA 7, 300,000 260,000
Adult Female 100 265 ,000 NA NA 7, 300,000 260,000
Child 100 88 ,000 234,000 NA NA 64,000

1 10X (interspecies), 10X (intraspecies)

2 MOE dietary = Chronic dietary POD [ Table 4.5.4.1] / dietary exposure [Table 5.4.1].
MOE dietary (Adult Male, Adult Female) = [(279 mg/kg bw/day) / ( 0.0010504 mg/kg bw/day)] = 265 ,000. MOE dietary (Child) = [(2 7 9 mg/kg bw/day )/(0.003 184 mg/kg bw/day)] = 88 ,000

. 3 Most cons ervative estimate in Table 6.2 (Short

- Term Hand

- to

- Mouth Activity on Turf).

4 No dermal endpoint was identified.

5 Most con servative estimate in Table 6. 1 (Belly Grinder).

6 MOE Aggregate = 1 / [(1/MOE dietary) + (1/MOE oral) + (1/MOE dermal) + (1/MOE inhalation)]

7.3 Chronic Ag gregate Risk

There are no long

- term residential exposure scenarios for aminocyclopyrachlor, and so chronic aggregate risks were not assessed. Chronic dietary risks for exposure to aminocyclopyrachlor
were assessed in Section 5.

7.4 Cancer Aggregate RiskAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 41 of 78 Cancer aggregate risk was not assessed because aminocyclopyrachlor was classified as ―Not Likely to be Carcinogenic to Humans‖ (CARC Memo, J. Kidwell, November 9, 2011).

8.0 Cumulative Exposure/Risk Characterization

Unlike other pesticides for whi ch EPA has followed a cumulative risk approach based on a common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as to aminocyclopyrachlor and any other substances and aminocyclopyrachlor does not appear to produce a toxic me tabolite produced by other substances. For the purposes of this tolerance action, therefore, EPA has not assumed that aminocyclopyrachlor has a common mechanism of toxicity with other substances. For information regarding EPA’s efforts to determine which

c hemicals have a common mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see the policy statements released by EPA’s Office of Pesticide Programs concerning common mechanism determinations and procedures for cumulating 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 Characterization

Occupational exposures and risks were as sessed for aminocyclopyrachlor and aminocyclopyrachlor

- methyl. Exposure to the environmental degradate, cyclopropane

car boxylic acid, is not expected because r esidue chemistry studies (MRID 4833617) indicate that cyclopropane carboxylic acid is not found on the surface of crops.

9.1 Short

- /Intermedia te

- Term Handler Risk

Amino cyclopyrachlor will be applied to rangeland, pastures, or CRP acres aerially or by groundboom. Occupational handler exposures to aminocyclopyrachlor and aminocyclopyrachlor

- methyl via these application methods during application or following application (post

- application) may occur dermally and by inhalation . These exposures are short

term or inter mediate

- term in duration based on the potential for multiple applications per season

. Cancer risks for occupational handlers were not assessed because no cancer hazards were
identified.

No dermal hazard for aminocyclopyrachlor and aminocyclopyrachlor

- methyl was identified because no toxicity was observed at the limit dose in a subchronic dermal exposure study with aminocyclopyrachlor. Therefore, a quantitative dermal risk assessment for applicators was not done. Inhalation risk for applicators in the absence of respiratory protection was assessed by analysis of short

- term and intermediate

- term exposures using the product ( EPA Reg. No. 352

- 786 ) with the highest application rate (0.28 lbs of acid equivalent/acre) . Inhalation unit exposures were quantified using the PHED Surrogate Exposure Guide (August 1998). H az ards were quantified from subchronic oral toxicity studies . A target margin of exposure (MOE) ofAminocyclopyrachlor Human Health Risk Assessment DP No. D387448

Page 42 of 78 100 was utilized. Risk estima tes for the proposed new use on rangeland/pastures/CRP acres are
summarized in Table 9.1

. No risks of concern for applicators were identified in occupational exposure scenarios , as the
calculated MOEs were 81

- fold to 13,000

- fold higher than the target MOE of 100.Aminocyclopyrachlor Human Health Risk Assessment DP No. D 387448

Page 43 of 78 T able 9.1. Short

- /Intermediate

- Term Occupational Exposure and Risk Estimates for Aminocyclopyrachlor and Aminocyclopyrahclor

- methyl

. All estimates are without mitigation (e.g. without PPE)

Exposure
Scenario Crops Application.
Rate (lb ae/A) 1 Area Treated

(A/day) 2 Inhalation

Unit Exposure ( g/lb ai) 7 Inhalation

Daily Dose (mg/kg/day) 3 Inhalation

Short/Intermediate

- term MOE 4

Mixer/Loader (dry flowable) 5

Groundboom Pasture/ Rangeland

grasses 6 0.28 200

8.96 0.007168 49,000

Aerial 1200 0.043008 8

, 100

Applying (dry flowable)

Groundboom (Open Cab) Pasture/ Rangeland

grasses 0.28 200 0.34 0.000272 1,300,000

Aerial (enclosed Cockpit) 1200 0.068 0.000327 1,100,000

Flagging (dry flowable)

Aerial Flagging Pasture/ Rangeland

grasses 0.28 1200 0.35 0.00168 210,000

1. Application rates are based on maximum values found in proposed labels (ae = acid equivalent) 2. Daily area treated is based on the area or gallons that can be reasonably applied in a single day or ―one time application

- (non

- crop)‖ for each exposure scenario of concern based on the application method and formulation/packaging type. (standard EPA /OPP/HED values). 3. Daily Dose (mg/kg/day) was calculated by Unit Exposure * 100% * Appl. rate * Area treated} / 70 kg. Short and Intermediate

- term endpoints are the same, thus one column.
4. Short

- /Intermediate

- Term MOE = Inhalation NOAEL (350 mg/kg/ day). The LOC for the target MOE = 100. 5. Note: Open mixing and loading formulation was calculated using a ―dry

- flowable‖ exposure scenario. See PHED version 1.1 for details. 6. Rangeland Grasses: Weeds /non

- agricultural item. Max. "Yearly" applicati on label rate for pasture/rangeland only : 9 oz./Acre/applicati on.: (9oz./Acre x 1lb/16 oz) x 50% = .28 lbs ae/ Acre) "One time Application/year" Reference label [352

- 786]. 7. HED policies on use of surrogate data, including their sources, are presented in the ―Occupational Pesticide Handler Unit Exposure Surrogate Reference Table‖ ( http://www.epa.gov/pesticides/science/handler

- exposure

- table.pdf ) and (http://www.epa.gov/pesticides/science/handler

- exposure

- data.html)Aminocyclopyrachlor Human Health Risk Assessment DP No. D 387448

Page 44 of 78 9.2 Short

- /Intermediat e
- Term Post

- Application Risk

9.2.1 Dermal Post application Risk

Occupational post

- application exposures via the dermal route were not assessed because no hazard was identified at the limit dose in a subchronic dermal toxicity study.

9.2.2 Inhalation Post application Risk

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

- application inhalation exposure

assess ment was not performed for aminocyclopyrachlor at this time primarily because of the low acute inhalation toxicity (Toxicity Category III and IV), low vapor pressure (less than 1x10 - 5 kPa), and the low proposed use rate. However, there are multiple potent ial 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 final report on M arch 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 Task Force and m ay, 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 put into place, the Agency may revisit the need for a quantitative occupational post

- application inhalation exposure assessment for aminocyclopyrachlor

.

Although a quantitative occupational postapplication inhalation exposure assessment was not performed, an inhalation exposure assessment was performed for occupational/commercial handlers. Handler exposure resulting from application of pesticides outdoors is likely to result in higher exposure than postapplication exposure. Therefore, it is expected that these handler inhalation exposure estimates would be protective of most occupational postapplication inhalation exposure scenarios.Aminocyclopyrachlor Human Health Risk Assessment DP No. D 387448

Page 45 of 78 10.0 References (in Data Package Number Order)

PRODUCT CHEMISTRY REVIEW OF: DPX KJM44 Technical Herbicide

, A. Abramovitch , August 25, 2009, D357975.

PRODUCT CHEMISTRY REVIEW OF: DPX MAT28 Technical Herbicide

, A. Abramovitch, August 16, 20009, D357886.

Drinkin g wate r assessment for aminocyclopyrachlor acid and its degradate cyclopropane carboxylic acid (IN

- V0977) for non

- crop and turf use , C. Khoper , January 8, 2010, D368238.

Aminocyclopyrachlor. Report of the Residues of Concern Knowledgebase Subcommittee (ROCKS)

, G. Kramer, October 15, 2009, D370638

.

Aminocyclopyrachlor: Human Health Risk Assessment for Proposed Uses as an Herbicide, J.
Ryman, J, Miller, T. Morton, March 17, 2010, D369057.

Toxicity assessment of IN

- V0977 (cyclopropane carboxylic acid) .J. Ryman , December 31, 2009, D371413, TXR 0055290.

Occupational and Resi dential Risk Assessment to Support the Request for Registration of Aminocyclopyrachlor, its methyl ester and potassium salt on Turf and Non

- crop areas, J.S. Miller, January 30, 2010, D372493.

Aminocyclopyrachlor: Revised Acute and Chronic Dietary (Drin king Water Only) Exposure Analysis for the Section 3 Registration Action, T. Morton, January 19, 2010, D 372779.

Aminocyclopyrachlor. Petition for Tolerances in Support of New Uses on Grasses (PP#0F7817). Summary of Analytical Che mistry and Residue Data, T. Morton, April 18 , 2012 , D387442

.

Aminocyclopyrachlor: Acute and Chronic Dietary Exposure Analysis for the Section 3 Registration Acti on, T. Morton, April 18 , 2012 , D387446.

Aminocyclopyrachlor, Aminocyclopyrachlor Methyl Ester, and Aminocyclopyrachlor Potassium Salt: Worker Risk Analysis for Amended Use on Rangeland Grasses, J. Miller, April 18, 2012

, D387447.

Aminocyclopyrachlor. Report of the Residues of Concern Knowledgebase Subcommittee (ROCKS) , I. Negron

- Encarnacion, September 22, 2011, D393619.

Updated Drinking Water Exposure Assessment for Aminocyclopyrachlor Acid and its Degradate Cyclopropanecarboxylic Acid (IN

- V0977) for T urf, and the Proposed New Use on Rangeland (Tolerance # 0F7817), R. Baris a nd M. Corbin, November 3, 2011, D394887.Aminocyclopyrachlor Human Health Risk Assessment DP No. D 387448

Page 46 of 78 AMINOCYCLOPYRACHLOR: Report of the Cancer Assessment Review Committee, J. Kidwell, November 9, 2011, TXR 0056120.

Aminocyclopyrachlor

- ToxSAC Meeting on September 15, 2011, J. Kidwell, October 11, 2011.

Lowrie, C. (2009) The Metabolism of [ 14 C]DPX

- KJM44 (Methyl Ester of DPX

- MAT28) in Grass. Project ID Number: 807943. Sponsor Study Number: DuPont

- 22393. Unpublished study prepared by E. I. du Pont de Nemours and Company. 102 p. MRID 4833 3 617.Aminocyclopyrachlor Human Health Risk Assessment DP No. D 387448

Page 47 of 78 A ppend ix A

. Toxicology Profile and Executive Summaries

A.1 Toxicology Data Requirements The requirements (40 CFR 158.340) for FOOD use for AMINOCYLOPYRACHLOR are in Table 1. ( Use of the new guideline numbers does not imply that the new (1998) guideline protoco ls were used )

.

Test Technical

Required Satisfied

870.1100 Acute Oral Toxicity

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

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

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

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

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

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

870.3100 Oral Subchronic (rodent)

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

................................ ......... 870.3200 21

- Day Dermal

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

- Day Dermal

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

- Day Inhalation

................................ .......................... CR
CR

no
yes CR yes
yes
yes yes (waived) 2

Waiver recommended 1

870.3700a Developmental Toxicity (rodent)

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

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

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

870.4100a Chronic Toxicity (rodent)

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

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

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

................................ .................... CR
CR
CR
CR yes
yes
yes
yes

870.5100 Mutagenicity

— Gene Mutation

- bacterial

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

— Gene Mutation

- mammalian

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

— In Vitro Chromosomal Aberrations

...... 870.5385 Mutagenicity

— In Vivo Bone Marrow
Chromosomal

................................ ................................ ................... 870.5395 Mutagenicity

— In Vivo Erythrocyte Micronucleus

....... yes
yes
yes
yes
yes yes
yes
yes yes (waived) 2

yes

870.6100a Acute Delayed Neurotox. (hen)

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

- Day Neurotoxicity (hen)

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

....................... 870.6200b 90

- Day Neuro. Screening Battery (rat)

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

................................ .............................. CR
CR

yes
yes CR Waiver recommended 1

Waiver recommended 1

yes
yes
Waiver recommended 1

870.7200 Companion animal safety

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

................................ ...................... 870.7600 Dermal penetration

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

................................ ............................. CR

CR
CR

yes Waiver recommended 1

yes
Waiver recommended 1

yes

CR=conditionally required

1 Rationale described in a Memorandum entitled ―Recommended waivers of conditionally required toxicology studies for non

- food uses of aminocyclopyrachlor‖ (J. Ryman, February 4, 2010, D373897).

2 Rationale described in a Memorandum entitled ―Waiver request for a 90

- day dermal toxicity study (870.32 50) and status of the mutagenicity testing database for DPX

- MAT28‖ ( J. Ryman, May 13, 2009, D364576, TXR 0055180).Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 48 of 78 A.2 Toxicity Profile s

Table A.2.1 Acute Toxicity Profile for Aminocyclopyrachlor technical

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

870.1100 Acute oral [rat] 47559934 LD 50 >5000 mg/kg IV

870.1200 Acute dermal [rat] 47559935 LD 50 >5000 mg/kg IV

870.1300 Acute inhalation [rat] 47560001 LD 50 >5.4 mg/L IV

870.2400 Acute eye irritation [White New

Zealand rabbit] 47560002 Mild irritant III

870.2500 Acute dermal irritation [rabbit] 47560003 Non

- irritant IV

870.2600 Skin sensitization [Guinea Pig] 47560004 Non

- sensitizer IV

Table A.2.2 Acute Toxicity Profile for Aminocyclopyrachlor

- methyl technical

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

870.1100 Acute oral [rat] 47560027 LD 50 >5000 mg/kg IV

870.1200 Acute dermal [rat] 47560028 LD 50 >5000 mg/kg IV

870.1300 Acute inhalation [rat] 47560029 LD 50 >5.4 mg/L IV

870.2400 Acute eye irritation [White New

Zealand rabbit] 47560030 Mild irritant III

870.2500 Acute dermal irritation [rabbit] 47560031 Non

- irritant IV

870.2600 Skin sensitization [Guinea Pig] 47560032 Non

- sensitizer IV

Table A.2.3 Subchronic, Chronic and Other Toxicity Profile Toxicity Profile for Aminocyclopyrachlor

Guideline No Study Type MRID
Classification
Doses Results

870.3100
90

- Day Oral Toxicity Feeding

- mouse 47560010 (2008) 47560011 (2008) Acceptable/guideline

0, 300, 1000, 3000, 7000 ppm 0/0, 47/61, 154/230, 459/649, and 1088/1623 mg/kg/day (M/F) NOAEL= 7 000 ppm ( 1088/1623 mg/kg/day M/F, limit dose)

LOAEL = not established.

870.3100
90

- Day Oral Toxicity Feeding

- rat 47573403 (2008) 47560007 (2008) Acceptable/guideline 0, 600, 2000, 6000, 18000 ppm NOAEL = 6000 ppm (349.4/448.0 mg/kg/day M/F)

LOAEL = 18,000 ppm (1044.6/1424.9 mg/kg/day M/F), based on decreased body weights, body weight gains, food consumption, and food efficiency i n both sexes.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 49 of 78 0/0, 34.8/44.8, 114.3/145.7, 349.4/448.0,
1044.6/1424.9 mg/kg/day (M/F)

870.3150

90

- Day Oral Toxicity Feeding

- dog 47560012 (2008) 47560013 (2008) Unacceptable/guideline

0, 250, 1250, 5000, 15000 ppm

0/0, 6.5/7.0, 33/38, 126/124, 426/388 mg/kg /day M/F NOAEL = 15,000 ppm (426/388 mg/kg/day M/F)

LOAEL = not established.

870.3200
28

- Day Dermal Toxicity

- rat 47560014 (2 008) Acceptable/guideline

0, 150, 400, or 1000 mg/kg/day NOAEL = 1000 mg/kg/day

LOAEL = not established.

870.3250
90

- Day Dermal Toxicity

- rat 47725701 (2009) Waived Memo D364756 (2009)

870.3465
90

- Day Inhalation No study available. Waived Memo D373897 (2010)

870.3700a
Prenatal Developmental

- rat 47560016 (2008) Acceptable/guideline

0, 30, 100, 300, or 1000 mg/kg/day (GD
6

- 20) Maternal NOAEL = 1000 mg/kg/day
LOAEL = not established. Developmental NOAEL= 1000 mg/kg/day
LOAEL = not established.

870.3700b
Prenatal Developmental

rabbit 47560015 (2008) Acceptable/guideline

0, 100, 300, 500, or 1000 mg/kg/day (GD
7

- 28) Maternal NOAEL = 500 mg/kg/day LOAEL = 1000 mg/kg/day based on mortality and abortion and decreased body weight gains and food consumption. Developmental NOAEL = 1000 mg/kg/day
LOAEL =not established.

870.3800 Reproduction and Fertility Effects

- rat 47575101 (2008) Acceptable/guideline

0, 500, 1500, 5000, or 17,000 ppm

0/0, 36/41, 109/125, 363/416, or 1285/1454 mg/kg/day M/F Parental Systemic NOAEL = 5000 ppm (363/416 mg/kg/day M/F) Parental Systemic LOAEL = 17000 ppm (1285/1454 mg/kg/day) based on decreased body weights. Reproduction NOAEL = 17000 ppm (1285/ 1454 mg/kg/day M/F) Reproduction
LOAEL was not established. Offspring NOAEL = 5000 ppm (363/416 mg/kg/day) Offspring LOAEL = 17,000 ppm (1285/1454 mg/kg/day M/F) based on decreased body weights in F1 and F2 pups.
870.4100b Chronic Toxicity

nonrodent 48333608 (2010) Acceptable/guideline

0, 1250, 5000, 15, 000

, NOAEL = 30, 000 pp m ( 1077/1073 mg/kg/day M/F)

LOAEL = Not observed.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 50 of 78 or 30, 000 ppm

0/0, 38/47, 178/175, 465/542, 1077/1073 mg/kg/day M/F
870.4200a Carcinogenicity

- mouse 48333606 (2010) Acceptable/guideline

0, 300, 1000, 3000, 7000 ppm

0/0, 39/50, 133/171, 393/527, 876/1190 mg/kg/day M/F Chronic toxicity NOAEL = 7000 ppm (876/1190 mg/kg bw/day)

Chronic toxicity LOAEL = Not observed.

Not carcinogenic.

870. 4300
Combined chronic toxicity/carcinogenicity

rat 48333607 (2010) Acceptable/guideline

0, 600, 2000, 6000, 18,000 ppm

0/0, 27/29, 97/100, 279/309, 892/957 mg/kg/day M/F Chronic toxicity NOAEL = 6000 ppm (279/309 mg/kg bw/day)

Chronic toxicity LOAEL = 18 ,000 ppm (892/957 mg/kg bw/day) based on mild decreases in body weight/body weight gain

Not carcinogenic.

Gene Mutation
870.5100
In vitro Bacterial Gene
Mutation 47560019 (2007) Acceptable/guideline 0, 50, 150, 500, 1500, or 5000 μg/plate (+/

- S9) There was no evidence of induced mutant colonies over background in the presence or absence of S9

- activation.

Gene Mutation
870.5300
In vitro Mammalian
Cells Gene Mutation (Chinese Hamster Ovary Cells) 47560020 (2007) Acceptable/guideline 0, 750, 1000, 1500, 1750, or 2150 μg/mL (+/

- S9) There was no evidence of induced mutant colonies over background in the presence or absence of S9

- activation.

Cytogenetics
870.5375
In vitro Mammalian Cytogenetics
Chromosomal Aberration Assay

human peripheral blood lymphocytes 47560021 (2007) Acceptable/guideline 0, 267, 534, 1068, or 2136 μg/mL (+/

- S9) There was no evidence of chromosome aberrations induced over background in the presence or absence of S9

- activa tion.

Cytogenetics
870.5385
Mammalian Bone
Marrow Chromosome
Aberration Test No study available Waived
Memo D364576 (2009)

Cytogenetics

- other
870.5395 In Vivo
Mammalian Cytogenetics

- Erythrocyte
Micronucleus

- mouse 47560022 (2007) 0, 500, 1000, or 2000 mg/kg (limit dose) No significant increase in the frequency of micronucleated polychromatic erythrocytes in bone marrow after any
treatment time.

870.6100a Acute Waiver recommendedAminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 51 of 78 Delayed Neurotox

- hen No study available Memo D373897 (2010)
870.6100b 90

- Day
Neurotox.

- hen No study available Waiver recommended Memo D373897 (2010)
870.6200a Acute Neurotoxicity

- rat 47725702 (2009) Acceptable/guideline 0, 200, 1000, 2000 mg/kg (limit dose)

(0.5%carboxy

methylcellulose vehicle) NOAEL = 2000 mg/kg (limit dose)

No acute neurotoxicity.

870.6200b
Subchronic Neurotoxicity

- rat 47573403 (2008) 47560007 (2008) Acceptable/guideline 0, 600, 2000, 6000, 18000 ppm 0/0, 34.8/44.8, 114.3/145.7, 349.4/448.0,
1044.6/1424.9 mg/kg/day (M/F) NOAEL = 18,000 ppm (limit dose) (1044.6/1424.9 mg/kg/day M/F)

No subchronic neurotoxicity.

870.7485
Metabolism and
Pharmacokinetics

- rat 47560023 (2007) Acceptable/guideline 25 or 500 mg/kg bw (single oral dose) Peak plasma and RBC concentrations at 0.3

- 1.0 h. AUC
scaled with dose. Whole blood radiolabel distribution: plasma (60%), RBCs (40%) in RBCs. Plasma elimination
half

- life was 5.6

- 5.7 h. Majority eliminated within 24 h as unmetabolized parent: 35.8

- 53.71% (urine) 31.4

- 48.0% (feces). No sex differences.
870.7485
Metabolism and
Pharmacokinetics

- rat 48333610 (2010) Acceptable/guideline Confirms 47560023 and extends observations to bile

- duct
cannulated animals, tissue distribution, and metabolism for single and repeated

- dose administration. There was evidence for a limited role of enterohepatic circulation. Distribution highest in GI tract/GI contents followed by carcass, skin, and blood. Elimination near

- complete (<1%)
72 hours after administration. Evidence of saturation of uptake, as percentage of radiolabel in tissues decreases with repeated

- dose administration. DPX

- MAT28 identified as sole radiolabelled substance in excreta, indicating no
metab olism.
870.7600 Dermal penetration No study available Waiver recommended Memo D373897 (2010)
870.7800 Immunotoxicity

- rat 47560025 (2008) \ Acceptable/guideline 0, 600, 6000, 18000 ppm (male rats) 0, 42, 407, 1277 mg/kg/day (male rats) Systemic NOAEL= 18,000 ppm (1277 mg/kg/day) Systemic LOAEL= not established Immunotoxicity NOAEL= 18,000 ppm (1277 mg/kg/day) Immunotoxicity LOAEL= not established

870.7800 Immunotoxicity

- mouse 47560026 (2008) Acceptable/guideline 0, 300, 3000, 7000

ppm (male mice) 0, 45, 425, and 1056 mg/kg/day (male mice Systemic NOAEL= 7,000 ppm (1056 mg/kg/day) Systemic LOAEL= not established Immunotoxicity NOAEL= 7,000 ppm (1056 mg/kg/day) Immunotoxicity LOAEL= not establishedAminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 52 of 78 Table A.2.4 Subchronic, Chronic and Other Toxicity Profile Toxicity Profile for Aminocyclopyrachlor

- methyl

Guideline No Study Type MRID
Classification
Doses Results

No n

- guideline, OECD
415

– One Gen. Repro.

- rat 47560018 (2006) Acceptable/non

guideline 0, 600, 5000, 17000

ppm 0/0, 49/53, 385/435,
1378/1489 mg/kg/day M/F (28 d premating to PND 60 of F1). Parental Systemic NOAEL = 5000 ppm (398/435 mg/kg/day

M/F) Parental Systemic LOAEL = 17,000 ppm (1378/1489 mg/kg/day) based on decreased food consumption and efficiency in the P generation and on decreased body weights and food consumption in the F1 generation. .

No reproductive toxicity (NOAEL=17,000 ppm (1378/1489 mg/kg/day).

Offspring NOAEL = 5000 ppm (398/435 mg/kg/day M/F) Offspring LOAEL = 17,000 ppm (1378/1489 mg/kg/d ay M/F) based on dehydration, decreased pup body weight gains, and decreased body weights late in lactation.
870.3100
90

- Day Oral Toxicity Feeding

- rat 47560008 (2008) 47560009 (2008) Acceptable/guideline 0, 600, 2000, 6000, 18000 ppm 0/0, 35/43, 117/133, 347/405, 1022/1219 mg/kg/day (M/F) NOAEL = 6000 ppm (347/405 mg/kg/day M/F)

LOAEL = 18,000 ppm (1022/1219 mg/kg/day M/F) based on decreased body weights, body weight gains, food consumption, and food efficiency in both sexes.

Gene Mutation
870.5100
In vitro Bacterial Gene
Mutation 47560033 (2005) Acceptable/Non

guideline 0, 100, 333, 1000, 3333, or 5000 μg/plate (+/

- S9) There was no evidence of induced mutant colonies over

background in the presence or absence of S9

- activation.

870.6300 Developmental Neurotoxicity

- rat No study available Waiver recommended Memo D373897 (2010)

870.7200 Companion animal safety No study available Waiver recommended Memo D373897 (2010)

870.7485
Metabolism and
Pharmacokinetics

- rat 47560024 (2007) Acceptable/guideline 25 or 500 mg/kg bw (single oral dose) Peak plasma and RBC concentrations at 0.3

- 0.6 h. AUC

scaled with dose. Whole blood radiolabel distribution: plasma (60%), RBCs (40%) in RBCs. Plasma elimination
half

- life was 8.7

- 13.3 h. Majority eliminated within 24 h as
DPX

- MAT28: 78.80

- 78.82% (urin e), minor in feces (1.72

- 4.57%). No sex differences.
870.7485
Metabolism and
Pharmacokinetics

- rat 48333609 (2010) Acceptable/guideline Confirms 47560024 and extends observations to bile

- duct

cannulated animals, tissue distribution, and metabolism.
There was no evidence of elimination in bile. Tissue distribution was less than 1%. The majority was eliminated
in the urine as DPX

- MAT28 with less than 1% of DPX

KJM44 remaining. In the bile, no unmetablo lized DPX

KJM44 was identified, as all had been metabolized to DPX

MAT28.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 53 of 78 Table A.2.5 Toxicity Profile for Cyclopropane Carboxylic Acid (IN

- V0977, Environmental Degradate)

Guideline No Study Type MRID
Classification
Doses Results

No n

- guideline 14

- day oral toxicity study 47916803 (1995 ) Acceptable/non

guideline

0, 10, 20 mkd oral (gavage)
administrati o n of panadiplon* to rabbits (10/dose) for 14 days

*metabolized to cyclopropane carboxylic acid NOAEL = Not observed

LOAEL = 10 mkd panadiplon (2.5 mkd cyclopropane carboxylic acid) based on gross liver lesions and microscopic effects of microvesicular hepatic steatosis and necrosis.

A.3.1 Acute Reference Dose (aRfD)

- Females age 13

- 49

Aminocyclopyrachlor Study Selected: Acute neurotoxicity

- rat MRID No .: 47560015 Executive Summary : See Appendix A, Guideline 870. 6300 Dose and Endpoint for Risk Assessment: NOAEL = 2000 mg/kg/day . No LOAEL was identified. Comments about Study/Endpoint/Uncertainty Factors: This study was selected because it of the most relevant exposure duration and there is no evidence of any effects in the toxicity database for longer duration studies that may be attributable to a single exposure. Maternal deaths and abortions were observed in the prena tal develo pmental study in rats at 1000 m g/kg bw/day. This study was considered as an acute endpoint. However, it was not selected because these maternal deaths/abortions were considered secondary to large weight losses that occurred over a period of 5

- 7 days, and so were not considered a single dose effect. A 10X interspecies
and a 10X intra species uncertainty factors are required. Reduction of the FQPA Safety Factor to 1X is justified.

Cyclopropane carboxylic acid Study Selected: 14 day oral toxicity study
MRID No .: 47916803 Executive Summary : See Appendix A Dose and Endpoint for Risk Assessment: NOAEL = Not observed. LOAEL=10 mg/kg/day panadiplon* (2.5 mg/kg/day cyclopropane carboxylic acid). (*Panadiplon is metabolized to cyclopropane carboxylic acid). Comments about Study/Endpoint/Uncertainty Factors: This study was selected because it

mea sures the most sensitive effect (hepatic microvesicular steatosis) in the most sensitive species (rabbit) via a relevant route of exposure (oral). This is a non

- guideline, literature study and theAminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 54 of 78 only duration of exposure examined was 14 days. This stud y was considered as an acute endpoint. For acute exposures, the standard 10X FQPA safety factor is retained due to lack of a
NOAEL and lack of data examining the toxicity of this degradate during development. The standard 10X interspecies and a 10X in traspecies uncertainty factors will also be utilized.

A.3.2 Acute Reference Dose (aRfD)

- General Population

Aminocyclopyrac h lor Same as Acute Reference Dose (aRfD)

- Females age 13

- 49.

Cyclopropane carboxylic acid Same as Acute Reference Dose (aRfD )

- Females age 13

- 49.

A.3.3 Chronic Reference Dose (cRfD ) `

Aminocyclopyrachlor Study Selected: Combined chronic toxicity/carcinogenicity

- rat MRID No .: 48333607 Executive Summary : See Appendix A, Guideline 870.4300 Dose and Endpoint for Risk Assessment: NOAEL = 279/309 mg/kg/day in males/females (use 279 mg/kg bw/day). The LOAEL is 892/957 mg/kg bw/day in males/females based on mild decreases in body weight/gain with no treatment

- related tumors. Comments about Study/Endpoint/Uncertainty Factors: This study was selecte d because this is the lowest NOAEL at which body weight decreases (the only adverse effect observed in the toxicity database for rats) were observed. When compared to the 90

- day rat oral study, this
NOAEL is lower than the 349/448 mg/kg bw/day. It is unclear if this difference is due to an increase in the sensitivity of the rats over time to the test substance, or if it is an artifact of dose spacing. Regardless, using the NOAEL in the chronic/carcinogenicity study as the POD is protective. A 10X interspecies and a 10X intr aspecies uncertainty factor are required. Reduction of the FQPA Safety Factor to 1X is justified.

Cyclopropane carboxylic acid Study Selected: 14 day oral toxicity study
MRID No .: 47916803
Exec utive Summary : See Appendix A Dose and Endpoint for Risk Assessment: NOAEL = Not observed. LOAEL=10 mg/kg/day panadiplon* (2.5 mg/kg/day cyclopropane carboxylic acid). (*Panadiplon is metabolized to cyclopropane carboxylic acid). Comments about Study/E ndpoint/Uncertainty Factors: This study was selected because it measures the most sensitive effect (hepatic microvesicular steatosis) in the most sensitive species (rabbit) via a relevant route of exposure (oral). This is a non

- guideline, literature study and the only duration of exp osure examined was 14 days. T he standard 10X FQPA safety factor is
retained due to l ack of a NOAEL and lack of data examining the toxicity of this degradate during development. The standard 10X interspecies and a 10X intraspecies uncertainty factors will also
be utilized. An additional 3X uncertainty factor is also applied for extrapolation from an acute to a chronic endpoint

.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 55 of 78 A.3.4 Incidental Oral Exposure (Short

- and Intermediate

- Term)

Study Selected: 90 day oral

- rat MRID No .: 475373403/47560007
E xecutive Summary : See Appendix A, Guideline 870.3100 Dose and Endpoint for Risk Assessment: NOAEL = 349/448 mg/kg/day (use 350 mg/kg bw/day). The LOAEL is 1045/1425 mg/kg bw/day base on decreased body weight/gain, food consumption/efficiency in both sexe s. Comments about Study/Endpoint/Uncertainty Factors: This study was selected because it is of the most relevant exposure duration (a 28 day oral toxicity study was not available), the endpoints of concern for this chemical are included, and the rat is the most sensitive species at this endpoint. Therefore, use of this study for the endpoint is both conservative and protective.
A 10 X interspecies and a 10X intraspecies uncertainty factors are required. Reduction of the FQPA Safety Factor to 1X is justified.

A.3.5 Dermal Exposure (Short

- , Intermediate

- and Long

- Term )

Study Selected: 28

- day dermal toxicity

- rat MRID No .: 477257 01 Executive Summary : See Appendix A, Guideline 870.3200 Dose and Endpoint for Risk Assessment: NOAEL = 1000 mg/kg/day . No LOAEL was
identified. Comments about Study/Endpoint/Uncertainty Factors: This study was selected because it is

a route

- specific study in the most sensitive species that measured the endpoint of concern (decreased body weight/gain) for this chemical. A 10X interspecies and a 10X intraspecies uncertainty factors are required. R eduction of the FQPA Safety Factor to 1X is justified.

A.3.6 Inhalation Exposure (Short

- , Intermediate

- Term)

Study Selected: 90 day oral

- rat MRID No .: 475373403/47560007 Executive Summary : See Appendix A, Guideline 870.3100 Dose and Endpoint for Risk Assessment: NOAEL = 349/448 mg/kg/day (use 350 mg/kg bw/day). The LOAEL is 1045/1425 mg/kg bw/day base d on decreased body weight/gain, food consumption/efficiency in both sexes. Comments about Study/Endpoint/Uncertainty Factors: Thi s study was se lected because no

route

- specific study was available. Therefore, extrapolation from the oral route at 100% is being performed. This study is of an appropriate duration to cover intermediate

- term exposure. It is also protective for short

- term exposures ( a 28

- study is not available). The endpoints of concern
for this chemical are included and the rat is the most sensitive species . A 10X interspecies and a 10X intraspecies uncertainty factors are required. Reduction of the FQPA Safety Factor to 1X is jus tified.

A.4 Executive SummariesAminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 56 of 78 A.4.1 Subchronic Toxicity

Non

- guideline 14

- Day Oral Toxicity

- Rabbit

EXECUTIVE SUMMARY : Cyclopropane carboxylic acid has been identified as an environmental degradate of aminocyclopyrachlor that is of concern. There are no toxicity studies with cycl o propane carboxylic acid suitable for risk assessment. However, cyclopropane carboxylic acid is also a metabolite of a drug called panadiplon, the toxic effects of which are mediated by cyclopropane carboxylic acid. Therefore, the following study from the general scientific literature with panadiplon was used.

In a 14

- day oral toxicity study, micronized panadiplon (purity unknown, batch/lot unknown), which is metabolized to cyclopropane carboxylic acid, was adminis tered to Dutch

- belted rabbits/dose orally (via gavage) in 1.25% low viscosity, microcrystalline cellulose and sodium carboxymethylcellulose NF, 0.2% polysorbate NF food grade, and 0.1N sodium hydroxide in purified water USP without sorbic acid at dose leve ls of 0 mg/kg (9 rabbits), 10 mg/kg (10 rabbits), or 20 mg/kg (10 rabbits) per day.

In 20 mg/kg animals, there was treatment related mortality in 2/10 rabbits and clinical signs (lethargy and weakness) in 6/10 rabbits. Both treated groups had gross liv er lesions (white streaks and masses on the liver from a few mm up to 2 cm) in 4/10 animals (10 mg/kg) and 10/10 animals (20 mg/kg). Serum triglycerides were elevated on Day 14 only for 10 mg/kg animals, whereas 20 mg/kg animals had elevated serum triglyc erides from Day 4 onward and elevated serum liver enzyme (aspartic acid transcarbamylase) from Day 8 onward. Microvesicular hepatic steatosis was observed in all treated animals. This was accompanied by single cell or
multi

- cell centrilobular necrosis in 7/10 animals at 10 mg/kg and centrilobular necrosis or focal coagulative necrosis in 10/10 animals at 20 mg/kg. Inflammatory cells and fibrosis were observed in larger necrotic foci that corresponded with gross lesions.

The LOAEL for panadiplon is 10 mg/kg/day based on gross liver lesions and microscopic effects of microvesicular hepatic steatosis and necrosis. The NOAEL was not observed.

The LOAEL for panadiplon (LOAEL P ) was converted to a LOAEL for CPCA (LOAEL C ) based on molecular weight and mole fraction, assuming a metabolic conversion of panadiplon to cyclopropane carboxylic acid of 100%. 100% was assumed because no experimental data were available regarding the percent conversion of panadiplon to cyclopropa ne carboxylic acid.

LOAEL P = 10 mg/kg/day x [(86.09 g CPCA/mole) / (337.35 g panadiplon/mole)] x [1 mole CPCA/mole panadiplon]= 2.55 mg/kg/day = LOAEL C

The LOAEL for cyclopropane carboxylic acid is 2.5 mg/kg/day, based on gross liver lesions and microscopic effects of microvesicular hepatic steatosis and necrosis. The NOAEL was
not observed.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 57 of 78 This 90

- day oral toxicity study in female Dutch

- belted rabbit is acceptable/non

- guideline

.

870.3100 90

- Day Oral Toxicity

- Rat

EXECUTIVE SUMMARY : In a subchronic oral and neurotoxicity study (MRID 47573403 ), aminocyclopyrachlor (DPX

- MAT28; 92.2 % a.i.; Batch No. DPX

- MAT28

- 009 ) was administered
in the diet to Crl:CD(SD) rats ( 15/ sex/dose) at doses (adjusted for purity) of 0, 600, 2000, 6000, or 18,000 ppm (equivalent to 34.8/44.8, 114.3/145.7, 349.4/448.0, and 1044.6/1424.9 mg/kg/day) for 13 weeks (94

- 95 days in males and 96

- 97 days in females). Neurobehaviora l assessment (functional observational battery [FOB] and motor activity testing) was performed prior to treatment and during Weeks 4, 8, and 13 on 10 rats/sex/group. On Day 56, plasma
concentrations of DPX

- MAT28 and the metabolite IN

- LXT69 were measured i n 5/sex/dose. At study termination, gross and histopathology were performed on 10 rats/sex/group, while 5

rats /sex/group were anesthetized and perfused in situ for neuropathological examination. The tissues from the perfused animals in the control and 18 ,000 ppm groups were subjected to histopathological evaluation of brain, spinal cord, and peripheral nervous system tissues.

All animals survived to the day of scheduled sacrifice. One control male and one 6000 ppm female were accidentally killed during blood collection just prior to necropsy.

No treatment

- related effects were observed in daily or weekly clinical observations and there
were no test substance

- related opthamological signs for either sex. There were no test substance

related or statistically significant effects on functional observational battery (FOB) parameters: forelimb and hindlimb grip strength, footsplay, body temperature, or behavioral parameters in
either se x. Additionally, there were no test substance

- related or statistically significant effects on duration of movement or number of movements measured in the motor activity analysis of males
and females.

At 18,000 ppm, decreases (p≤0.05; except as noted) in body weights were observed in the males from Days 28

- 91 (↓6

- 9%, NS at Days 56 and 70) and in the females on Days 56, 70, and 77 (↓8

- 10%). Overall (Days 0

- 91) body weight gain was decreased (p≤0.05) by 15

- 18% in both sexes. Significant decreases (p≤0.05) in food consumption were observed at 18,000 ppm during Days
0

- 7, 21

- 28, and 42

- 49 in males (↓7

- 8%) and during Days 70

- 77 in females (↓11%). D ecreased (p≤0.05) food efficiency was noted in males during Da ys 21

- 28, 70

- 77, and 77

- 84 (↓18

- 73%) and in females during Days 62

- 70 (↓112%). Overall (Days 0

- 91) food efficiency was decreased (p≤0.05) by 11% in males and 17% in females.

There were no adverse effects of the test substance on organ weights, ophthalmolo gy, hematology, coagulation, clinical chemistry, or urinalysis parameters in males and females. There were no effects of the test substance on brain weights or gross or microscopic neuropathology in either sex at any dose.

The plasma concentrations of DP X

- MAT28 and the metabolite IN

- LXT69 were measured on Day 56 by high performance liquid chromatography with detection by tandem mass spectrometry (LC/MS/MS, MRID 47560007). DPX

- MAT28 was the most abundant metabolite in male andAminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 58 of 78 female rats, with the highest concentrations at 10, 268 and 13, 428 ng/mL for 18,000 ppm male and female rats, respectively. In contrast, plasma levels of IN

- LXT68 were lower for this dose group at concentrations of 82 and 80 ng/mL for males and females, respectively. The average

co ncentration of DPX

- MAT29 in plasma was higher in females than in males at all dose levels.
The IN

- LXT69 plasma concentrations were below the limit of quantitation for the 600 ppm dietary concentration. The average IN

- LXT69 plasma concentrations appeared to be similar for males and females. There was no apparent plateau for the DPX

- MAT28 of IN

- LXT68 plasma concentrations when compared to dietary intake levels (e.g. plasma concentrations increased with increasing concentration in the diet).

The LOAEL for systemic effects is 18,000 ppm (1044.6/1424.9 mg/kg/day) , based on decreased body weights, body weight gains, food consumption, and food efficiency in both

sexes. The NOAEL is 6000 ppm (349.4/448.0 mg/kg/day)

.

The LOAEL for neurotoxicity was not obse rved. The NOAEL is 18,000 ppm (1044.6/1424.9 mg/kg/day) in both sexes.

The study is classified as Ac ceptable/ G uideline and satisfies the guideline requirements for a
90

- day oral toxicity study (OPPTS 870.3100; OECD 408) and a subchronic neurotoxicity st udy ( OPPTS 870.6200b ; OECD 424 ) in rats.

.

870.3100 90

- Day Oral Toxicity

- Mouse

EXECUTIVE SUMMARY : In a subchronic oral toxicity study (MRIDs 47560010 and 47560011), Aminocyclopyrachlor (92.2% a.i.; Batch# DPX

- MAT28

- 009) was administered to
15 CD

- 1 mice/sex/dose group in the diet at dose levels of 0, 300, 1000, 3000, or 7000 ppm (equivalent to 0/0, 47/61, 154/230, 459/649, and 1088/1623 mg/kg/day, in males/females) for approximately 90 days (95/96 days in males/females). At Day 60, blood was collected from the orbital sinus or tail vein of each mouse from the satellite groups (5/sex/concentration) for the determination of plasma concentration of the test substance ( DPX

- MAT28 ) and metabolite (IN

LXT69).

There were no trea tment

- related deaths during the study. Small but s tatistically significant decreases in body weights were seen for males starting at Day 49 and continuing through the end of treatment at doses of 1000, 3000, and 7000 ppm (↓4

- 8%) . Significant decreases in b ody weights ( ↓ 8

- 11%) were observed for females at 1000, 3000, and 7000 ppm. Body weight gains from Day 0

- 91 were significantly decreased in males ( 12

- 27%) at 1000 and 7000 ppm. Decreases in body weight gains were not statistically significant for femal es. There were no effects on food consumption for either sex. Overall food efficiency (Days 0

- 91) was significantly decreased (↓24%) in the 7000 ppm males and in females at 1000 ppm and 7000 ppm ( 28

- 36%), but not at 3000 ppm.

The number of reticulocytes in the 7000 ppm females was significantly decreased (p<0.05) by 15% compared to controls, but this was not considered adverse.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 59 of 78 Absolute and relative (to brain weight) changes in organ weights were observed,
but these were not considered adverse due to a lack of corroborating macroscopic or microscopic effects. These changes were: decreased absolute and relative heart weights (↓17

- 19%) at 7000 ppm compared to controls, increased relative (to body weight) brain weights in the 1000 ppm males, decreased relative (to brain) heart weights in the 1000 ppm females, and increased relative (to body weight) kidney weights in the 1000 ppm females.

T he LOAEL was not observed. The NOAEL is 7000 ppm (equivalent to 1088/1623 mg/kg/day in males/females).

The plasma concentration of the parent DPX

- MAT28 and the metabolite IN

- LXT69 were measured on Day 60. Plasma concentrations of DPX

- MAT28 were increased in all treated groups and was slightly higher in males than females at all dose levels. The IN

- IXT69 metabolite was not detected in any samples.

This study is classified as Acceptab le/Guideline and satisfies the guideline requirements (OPPTS 870.3100a; OECD 408) for a subchronic oral toxicity study in mice.

870.3150 90

- Day Oral Toxicity

- Dog

EXECUTIVE SUMMARY : In this subchronic oral toxicity study (MRID 47560012), 4 beagle dogs/sex/group were administered aminocyclopyrachlor (DPX

- MAT28; 92.2% a.i.; Batch No.
DPX

- MAT28

- 009) daily via the diet (400 g offered daily for approximately 2 hours) at doses of 0, 250, 12 50, 5000, or 15,000 ppm (equivalent to 0/0, 6.5/7.0, 33/38, 126/124, and 426/388 mg/kg/day in males/females) for 13 weeks.

No treatment related effect was observed on mortality, clinical signs, neurological evaluations, body weight, body weight gains, foo d consumption, food efficiency, hematology, clinical chemistry, urinalysis, organ weights, or gross or microscopic pathology.

A dose

- related increase in the incidence of skin scaling on the feet was observed in males, with 4/4 males affected at 15,000 ppm

. Half of the females were affected at the high dose. In most cases, all 4 feet exhibited scaling. The time of onset of scaling in most cases was 41

- 56 days, continuing to study termination (Day 91). The clinical severity of this effect was not noted a nd the foot pads were not biopsied. This effect was not considered adverse, because no impairment in walking or weight bearing and no grooming (e.g. licking/biting) of the feet was observed.

The plasma concentrations of parent increased with dietary int ake ranging from 1968

- 63,000 ng/mL in males and 3193

- 82,575 ng/mL in females at doses of 250

- 15,000 ppm. Plasma concentrations were always higher in the females than in the males. The metabolite IN

- LXT69 was below the limit of quantitation except at 15,0 00 ppm, where only minor amounts (11.6

- 11.7 ng/mL) were noted (MRID 47560013).

Total cytochrome P450 measured was unrelated to dose in both sexes and was 0.320

- 0.409 nmol/mg in males and 0.378

- 0.421 nmol /mg in females. At 5000 and 15,000 ppm, induction ofAminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 60 of 78 the isozymes 1A1 in males (↑402

- 420%) and 2B1/2 in males (↑91

- 125%) and females (↑34

- 93%) was observed (p 0.05 at 5000 ppm only). A decreased level of 2E1 was noted in the 15,000 ppm males ( 37%). Al though the effect on 2E1 seemed dose

- dependent, the noted decrease was not statistically significant and a similar effect was not noted in females. It is unclear if there is an inhibitory effect on 2E1.

The LOAEL was not observed. The NOAEL is 15,000 ppm (equivalent to 426/388 mg/kg/day in males/females).

This study is classified Unacceptable/Guideline and does not satisfy the guideline requirements (OPPTS 870.3150; OECD 409) for a subchronic oral toxicity study in dogs. An adverse effect
was not noted and the limit dose was not tested. This study is upgradable pending submission of a satisfactory dose

- selection rationale.

870.3200 21/28

- Day Dermal Toxicity

– Rat

EXECUTIVE SUMMARY : In a 28

- day dermal toxicity study (MRID 47560014 ), DPX

MAT28 ( Aminocyclopyrachlor ; 90.9 % a.i., B atch # DPX

- MAT28

- 010 ) was applied to the
shaved intact skin of 10 Sprague

- Dawley rats /sex/dose at dose levels (adjusted for purity) of 0, 150, 400, or 1000 mg/kg / day (limit dose) for 6 hours/day for 28 consecutive days.

There were no unscheduled deaths. There were no effects of the test substance on ophthalmology parameters. The only clinical sign observed was limited and very slight (barely perceptible) erythema/edema (score of 1 on a scale of 4, 4 being severe) in three males. Animals affected were one male at 400 mg/kg/day on Day 28, one male at 1000 mg/kg/day on Day 3, and one male at 1000 mg/kg/day on Day 28. There were no adverse effects of the test substance on body weight, body weight g ain, food consumption, food efficiency, clinical chemistry, hematology, gross pathology, or histopathology.

There were statistically significant, dose

- related changes in adrenal gland and ovary weights in 1000 mg/kg/day females and a decrease in kidney weights in females at 150 mg/kg/day that were
not considered adverse due to a lack of c orroborating microscopic lesions.

The LOAEL was not observed. The NOAEL is 1000 mg/kg/day (limit dose).

This study is classified as A cceptable/ G uideline and satisfies the guideline requirement for a
28

- day dermal toxicity study (OPPTS 870.3200; OECD 410) in rats

.

870.3465 90

- Day Inhalation

– Rat

None available.

A.4.2 Prenatal Developmental Toxicity

870.3700a Prenatal Developmental Toxicity Study

- RatAminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 61 of 78 EXECUTIVE SUMMARY : In a developmental toxicity study (MRID 47560016 ), Aminocyclopyrachlor (92.2%; Batch #DPX

- MAT28

- 9

- 009) in 0.5% methylcellulose was administered via daily oral gavage in a dose volume of 5 mL/kg to 25 time

- mated presumed

pr egnant Sprague

- Dawley rats/dose group at doses of 0, 30, 100, 300, or 1000 mg/kg/day from gestation days (GD) 6

- 20 . On GD 21, all maternal rats were euthanized; each dam’s uterus was
removed via cesarean section and its contents examined. The fetuses were examined for external, visceral, and skeletal malformations and variations.

All maternal animals survived until scheduled termination. No clinical signs of toxicity were noted in any of the dams. Body weights, body weight gains, and food consumptio n in the treated groups were comparable to controls throughout the study . The only gross abnormality was liver discoloration in a single dam at 100 mg/kg/day, and this finding was considered incidental
because it was minimal in incidence and not observed at the high dose.

The maternal LOAEL was not observed. The maternal NOAEL is 1000 mg/kg/day (limit dose).

There were no abortions, premature deliveries, late resorptions, complete litter resorptions , or dead fetuses. There were no effects of treatment on the numbers of litters, live fetuses, or early resorptions. Furthermore, sex ratio and post

- implantation losses in the treated groups were comparable to controls.

There was no evidence of altered growth or development. Fetal body weights in the treated groups were comparable to controls.

There were no treatment

- related external, visceral, or skeletal variations or malformations. Skeletal variations in the skull, vertebrae, ribs, and sternebrae were unrelated to dose. One skeletal malformation (fused cervical vertebrae) was found at 300 mg/kg/day. The only other malformations were: anophthalmia and eye bulge in one 300 mg/kg/day fetus and protruding tongue in another 300 mg/kg/day fetus. The se findings were considered incidental because they only occurred in individual fetuses and were not observed at the high dose.

The developmental LOAEL was not observed. The developmental NOAEL is 1000 mg/kg/day (limit dose).

This study is classified as A cceptable/ G uideline and satisfies the guidel ine requirement (OPPTS
870.3700a ; OECD 414) for a developmental toxicity study in rat s.

870.3700b Prenatal Developmental Toxicity Study

- Rabbit EXECUTIVE SUMMARY : In a developmental toxicity study (MRID 47560015 ), Aminocyclopyrachlor (92.2% a.i.; Lot #MAT28

- 009) in 0.5% methylcellulose was administered daily via oral gavage in a dose volume of 4 mL/kg to 22 time

- mated presumed pregnant New
Zealand White rabbits/d ose group at doses of 0, 100, 300, 500, or 1000 mg/kg/day from gestation days (GD) 7

- 28 . On GD 29, all maternal rabbits were euthanized; each dam’s uterusAminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 62 of 78 was removed via cesarean section and its contents examined. The fetuses were examined for external, visceral, and skeletal malformations and variations.

There was one maternal death at 1000 mg/kg/day on GD 13 that was considered treatment

related. Increased respiration was observed 1 hour after dosing on GD 7 in this animal, and rales
and decreased de fecation were noted during GD 9

- 13. This female had a body weight loss of 394 g from GD 7

- 13 and consumed 14 g food/day for 4

- 5 days prior to death. Also at 1000 mg/kg/day, two animals aborted (one on GD 20 and the other on GD 26). Clinical findings

no ted for both females included decreased defecation several days prior to abortion and red material in the cage pan or anogenital area on the day of abortion. These abortions may be secondary to body weight loss >10%. These females exhibited body weight l osses of 636

- 643 g (17

- 19%) from GD 7 through the day of abortion. These maternal effects corresponded with reduced food consumption, generally 17 g/day from GD 13 or 17 through the day of abortion.

There was one death at 1000 mg/kg/day unrelated to treatment that was attributed to a gavage error and another death at 100 mg/kg/day of unknown cause. One 300 mg/kg/day animal aborted on GD 28. Clinical findings noted for this female prior to abortion i ncluded 11 occurrences of decreased defecation and 3 occurrences of soft stool. This female consumed ≤18 g of food per day between GD 18

- 19 and 27

- 28, but had no notable effects on body weight gain. This abortion at 300 mg/kg/day was not considered an e ffect of treatment because it was not dose

- related (no abortions at 500 mg/kg/day). Aside from the above

- mentioned clinical signs associated with mortality and abortion, no treatment

- related clinical signs were observed. The only treatment

related gross findings at necropsy were in animals that died or aborted. These findings included red skin matting around the urogenital or nasal areas, dark red contents in the vagina, and white precipitate in the abdominal soft tissue.

Reductions in food consumption were statistically significant only in the 1000 mg/kg/day group. These reductions were consistently about 30% after GD 14

- 15 through the end of the study. Decreases in body weight gain were statistically significant only at GD 14

- 17, although the
decreas es throughout the remainder of the study are probably of biological significance. This consistent relationship between decreased food consumption and decreased body weight gain were not observed in the 500 mg/kg/day group. In this group, no significant di fferences in body weight gain were observed and there were no significant decreases in food consumption.

The maternal LOAEL is 1000 mg/kg/day (limit dose) based on mortality, decreased body weight gains and food consumption, and abortion. The maternal NOAEL is 500 mg/kg/day.

At 1000 mg/kg/day, there were two animals that were not pregnant, two that died, and two that aborted, resulting in a lower number of litters at this dose (16) compared to controls (21). When examined on a per litter basis, there were no effects of treatment on the mean numbers live fetuses, early resorptions, or late resorptions. Furthermore, fetal body weights, sex ratio, and post

- implantation losses in the treated groups were comparable to controls.

There were no treatment

- rel ated external, visceral, or skeletal malformations or variations.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 63 of 78 The developmental LOAEL was not observed. The developmental NOAEL is 1000 mg/kg/day (limit dose).

This study is classified Acceptable/Guideline and satisfies the guideline requirement (OP PTS 870.3700b; OECD 414) for a developmental toxicity study in rabbits.

A.4.3 Reproductive Toxicity

870.3800 Reproduction and Fertility Effects

- Rat

EXECUTIVE SUMMARY : In a two

- generation reproduction toxicity study (MRID 47575101), DPX

- MAT28 (Aminocyclopyrachlor; 90.9

- 92.2% a.i.; Batch Nos. DPX

- MAT28

- 009 and DPX

- MAT28

- 010) was administered in the diet to 28 Sprague Dawley (Crl:CD[SD]) rats/sex/dose group at dietary le vels of 0, 500, 1500, 5000, or 17,000 ppm (equivalent to 0/0, 36/41, 109/125, 363/416, and 1285/1454 mg/kg bw/day in males/females during pre

- mating) for two successive generations with one litter per generation. The P (parental) generation animals
were f ed the test diets for at least ten weeks prior to mating to produce the F1 litters. The F1 litters were culled on post

- natal day (PND) 4 to eight pups/litter (four/sex where possible). On PND 21, one pup/sex/litter (where possible) was selected and fed t he same test diet concentration as the dam. These animals were fed the test diets for at least ten weeks prior to mating (at 13 weeks of age) to produce the F2 litters.

No treatment

- related effects were observed on mortality, clinical signs, or macroscopic or microscopic findings.

Over the pre

- mating period in P and F1 males, body weights were significantly (p 0.05) decreased ( 6

- 15%) at 5000 ppm and above, as were body weight gains ( 7

- 17%). Food efficiency was decreased ( 8

- 15%) at 1500 ppm a nd above. For P and F1 females over this period, body weights were decreased ( 6

- 14%) at 17,000 ppm. Food efficiency and body weight gain were decreased for P females only at 17,000 ppm ( 12

- 16%).

Over the period of gestation in P and F1 females, body weight and body weight gain was significantly decreased for P females only at 17,000 ppm ( 8

- 12%). Food consumption and food efficiency were also decreased for these animals ( 10% and 20%, respectively). There were no significant effects of the test sub stance on these parameters in F1 females. Over the lactation period, body weights were transiently but significantly decreased ( 7

- 9%) in P females at 17,000 ppm on LD 0

- 7. Decreases in body weights of F1 females were not statistically significant.

Ter minal body weights were significantly (p 0.05) decreased at 17,000 ppm for P males and females ( 6

- 7%) F1 males ( 16%). At 5,000 ppm, terminal body weight was decreased ( 9%) for F1 males only. There were significant decreases ( 4

- 5%) in absolute (but n ot relative) brain weights for P and F1 females at 17,000 ppm. At 5,000 ppm, decreases in absolute brain weights were observed for P females only ( 4%). There were no correlating microscopic findings.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 64 of 78 The LOAEL for parental toxicity is 17, 000 ppm (eq uivalent to 1285/1454 mg/kg in males/females), based on decreased body weights in parental males and females. The NOAEL is 5000 ppm (equivalent to 363/416 mg/kg in males/females).

No treatment

- related effects on litter parameters were noted for the F1 or F2 generations. Specifically, there were no treatment

- related effects on survival indices, clinical signs, sex ratio, attainment of developmental landmarks, or gross or microscopic pathology.

At 17,000 ppm, body weights were significantly (p 0.05) decre ased at PND 21 in the F1 ( 15%) and F2 pups ( 8%). Body weights in the F1 pups were consistently decreased at PND 0, 4, 7, 14, and 21 at this dose, whereas body weights were decreased in F2 pups only at PND 21. There were no statistically significant de creases in body weight gain. In weanlings, terminal body weights were significantly decreased in both generations for both sexes (F1 males, F1 females, F2 males, F2 females) at 17,000 ppm ( 9

- 14%).

The LOAEL for offspring toxicity is 17,000 ppm (equiv alent to 1285/1454 mg/kg in males/females), based on decreased body weights in the F1 and F2 pups. The NOAEL is 5000 ppm (equivalent to 363/416 mg/kg in males/females).

No treatment

- related differences were observed in estrus cycle length or cyclicity, s perm parameters, numbers of primordial and pre

- antral follicles, mating, fertility, pre

- coital interval length, gestation length, number of implantation sites, or post

- implantation loss, or reproductive failures. Thus reproductive performance of P and F1 animals was not affected by treatment.

The LOAEL for reproductive toxicity was not observed. The NOAEL is 17,000 ppm (equivalent to 1285/1454 mg/kg in males/females).

This study is classified as Acceptable/Guideline and satisfies the guideline requirem ents (OPPTS 870.3800; OECD 416) for a two

- generation reproduction study in the rat.

A.4.4 Chronic Toxicity

870.4100a (870.4300) Chronic Toxicity

– Rat

EXECUTIVE SUMMARY : Five groups of Main male and female Crl:CD(SD) rats (7 0 /sex/group) were administered DPX

- MAT28 in the diet at concentrations of 0, 600, 2000, 6000, or 18000 ppm (0/0, 27/29, 279/309, 892/957 mg/kg bw/day in males/females) for 2 years. Satellite animals (10/sex/dose) were administered DPX

- MAT28 at these same dietary concentrations. For both Main and Satellite animals, body weights and food consumption were evaluated prior to dietary exposure, weekly for the first 13 weeks, and then biweekly thereafter. Body weights were also recorded on the day of necropsy. Detailed clinical observations were performed prior to dietary exposure, on the day of first dietary exposure, and weekly thereafter. Ophthalmological assessments were performed prior to the start of dietary exposure and near the end of the exposure perio d. For Satellite animals, hematology, clinical chemistry, and urinalysis were performed at 6 months and 1 year and coagulation measurements were performed at 1 year. For Main Study animals, blood smears and white blood differential counts were performed a t 1Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 65 of 78 year and 2 years and for animals sacrificed in extremis . Satellite and Main Study animals were sacrificed, organ weights were recorded, and gross and histopathology performed at 1 year and 2 years, respectively.

Mild effects on body weight and body weight gain were observed in both sexes at the highest dose. These effects were considered transient, since they resolved by study completion. Quantification of body weight decreases at Days 189, 385, and 539 revealed that the magnitudes
of the decreases in body weight were less than 10% in males and were above 10% in females (at 12%) only at Day 539. Quantification of decreases in body weight gain over Weeks 1, 1

- 13, 1

- 52, and 1

- 104 revealed that decreased body weight gain never exceeded 10% in males a nd exceeded 10% (at 11%) in females only at Weeks 1

- 52. Together, these data indicate that the effects of the test substance on body weight gain and body weight were mildly adverse. No test article effects on food consumption or food efficiency were obser ved.

No effects of the test article were observed on clinical signs, ophthalmology, clinical chemistry parameters (including coagulation), hematology, urinalysis, organ weights, and gross pathology.
There were also no effects of the test article on mor tality.

No microscopic effects of the test article were observed in Satellite animals.

The LOAEL for chronic toxicity is 18,000 ppm (892/957 mg/kg bw/day in males/females) based on mild decreases in body weight and body weight gain. The NOAEL is 6,00 0 ppm (279/309 mg/kg bw/day).

No treatment

- related tumors were observed.

This study in the rat is Acceptable/Guideline and satisfies the guideline requirements for a Combined Chronic Toxicity/Carcinogenicity Study (OPPTS 870.4300) in rats

.

870.4100b Chronic Toxicity

- Dog

EXECUTIVE SUMMARY : In a chronic oral toxicity study (MRID 48333608), DPX

- MAT28

- 23 technical (88.3% a.i.; Batch No. 8571

- 1 ) was administered to four beagle dogs/sex/dose group in the diet at doses of 0, 1,250, 5,000, 15,00 0 or 30,000 ppm (equivalent to 0, 37.9, 178.0, 465.1 and 1076.7 mg/kg/day in males and equivalent to 0, 46.9, 174.6, 542.1 and 1072.5 mg/kg/day in females) for 12 months.

There were no treatment related deaths in the study. No adverse treatment

- related e ffects were observed in the following parameters e.g. body weight and body weight gain, food consumption and food efficiency, clinical signs (including neurological parameters), ophthalmology evaluation, hematology (including coagulation), clinical chemist ry, urinalysis, gross findings, organ weights and histopathology.

The NOAEL is 30,000 ppm (1076.6/1072.5 mg/kg bw/day in males/females). The LOAEL was
not observed.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 66 of 78 This study is classified as Acceptable/Guideline and satisfies the guideline requir ements (OPPTS 870.4100b; OECD 452) for a chronic oral toxicity study in dogs.

A.4.5 Carcinogenicity

870.4200a Carcinogenicity Study

- rat

EXECUTIVE SUMMARY : Five groups of Main male and female Crl:CD(SD) rats (7 0 /sex/group) were administered DPX

- MAT28 in the diet at concentrations of 0, 600, 2000, 6000, or 18000 ppm (0/0, 27/29, 279/309, 892/957 mg/kg bw/day in males/females) for 2 years. Satellite animals (10/sex/dose) were administered DPX

- MAT28 at these same dietary concentrations. For both Main and Satellite animals, body weights and food consumption were evaluated prior to dietary exposure, weekly for the first 13 weeks, and then biweekly thereafter. Body weights were also recorded on the day of necropsy. Detailed clinical observations were performed prior to dietary exposure, on the day of first dietary exposure, and weekly thereafter. Ophthalmological assessments were performed prior to the start of dietary exposure and near the end of the exposure perio d. For Satellite animals, hematology, clinical chemistry, and urinalysis were performed at 6 months and 1 year and coagulation measurements were performed at 1 year. For Main Study animals, blood smears and white blood differential counts were performed a t 1 year and 2 years and for animals sacrificed in extremis . Satellite and Main Study animals were sacrificed, organ weights were recorded, and gross and histopathology performed at 1 year and 2 years, respectively.

Mild effects on body weight and body weight gain were observed in both sexes at the highest dose. These effects were considered transient, since they resolved by study completion. Quantification of body weight decreases at Days 189, 385, and 539 revealed that the magnitudes
of the decreases in body weight were less than 10% in males and were above 10% in females (at 12%) only at Day 539. Quantification of decreases in body weight gain over Weeks 1, 1

- 13, 1

- 52, and 1

- 104 revealed that decreased body weight gain never exceeded 10% in males a nd exceeded 10% (at 11%) in females only at Weeks 1

- 52. Together, these data indicate that the effects of the test substance on body weight gain and body weight were mildly adverse. No test article effects on food consumption or food efficiency were obser ved.

No effects of the test article were observed on clinical signs, ophthalmology, clinical chemistry parameters (including coagulation), hematology, urinalysis, organ weights, and gross pathology.
There were also no effects of the test article on mor tality.

No microscopic effects of the test article were observed in Satellite animals.

The LOAEL for chronic toxicity is 18,000 ppm (892/957 mg/kg bw/day in males/females) based on mild decreases in body weight and body weight gain. The NOAEL is 6,00 0 ppm (279/309 mg/kg bw/day).

No treatment

- related tumors were observed.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 67 of 78 This study in the rat is Acceptable/Guideline and satisfies the guideline requirements for a Combined Chronic Toxicity/Carcinogenicity Study (OPPTS 870.4300) in rats

.

870.4200b Carcinogenicity (feeding)

- Mouse

EXECUTIVE SUMMARY :

The objective of this study (MRID 48333606) was to assess the carcinogenic potential of DPX

MAT28 Technical (DPX

- MAT28) in mice. Five groups of young adult male and female Crlj:CDl (ICR) mice (60/sex/group) were administered diets that contained 0, 300, 1000, 3000, or 7000 ppm (corresponding to 0/0, 39/50, 133/171, 393/527, 876/1190 mg/kg bw/day) DPX

MAT28 for approximately 18 months.

Body weights and food consumption were evalua ted weekly for the first 13 weeks, then every other week thereafter. Detailed clinical observations were evaluated weekly. Ophthalmological assessments were performed prior to the start of dietary exposure and near the end of the exposure period. White blo od cell differential counts (via blood smear) were evaluated in surviving mice at the end of the exposure period and in mice that were sacrificed in extremis. After approximately 18 months of dietary exposure, mice were sacrificed and given a gross and
mic roscopic pathological examination.

No test article

- related changes were observed in the following observations in male and female mice fed up to 7000 ppm DPX

- MAT28: clinical observation, body weight parameters, food intake parameters, ophthalmology, white blood cell differential counts, cause of death, organ weights and gross pathological parameters, and neoplastic or non

- neoplastic changes.

DPX

- MAT28 is not an oncogen in mice.

The NOAEL for c hronic toxicity is 7000 ppm (876/1190 mg/kg bw/day in males and females).
The LOAEL was not observed.

This study is classified as Acceptable/Guideline and satisfies the guideline requirements for a carcinogenicity study (OPPTS 870.4200 b ) in mice

.

A.4.6 Mutagenicit y

Gene Mutation

Gene Mutation
870.5100
In vitro Bacterial Gene
Mutation 47560019 (2007) Acceptable/guideline 0, 50, 150, 500, 1500, or 5000 μg/plate (+/

- S9) There was no evidence of induced mutant colonies over background in the presence or absence of S9

- activation.

Gene Mutation
870.5300
In vitro Mammalian
Cells Gene Mutation 47560020 (2007) Acceptable/guideline 0, 750, 1000, 1500, 1750, or 2150 μg/mL There was no evidence of induced mutant colonies over background in the presence or absence of S9

- activation.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 68 of 78 (Chinese Hamster Ovary Cells) (+/

- S9)

Cytogenetics
870.5375
In vitro Mammalian Cytogenetics
Chromosomal Aberration Assay

human peripheral blood lymphocytes 47560021 (2007) Acceptable/guideline 0, 267, 534, 1068, or 2136 μg/mL (+/

- S9) There was no evidence of chromosome aberrations induced over background in the presence or absence of S9

- activation.

Cytogenetics
870.5385
Mammalian Bone
Marrow Chromosome
Aberration Test No study available Waived
Memo D364576 (2009)

Cytogenetics

- other
870.5395 In Vivo
Mammalian Cytogenetics

- Erythrocyte
Micronucleus

- mouse 47560022 (2007) 0, 500, 1000, or 2000 mg/kg (limit dose) No significant increase in the frequency of micronucleated polychromatic erythrocytes in bone marrow after any
treatment time.

Cytogenetics

Cytogenetics
870.5375
In vitro Mammalian Cytogenetics
Chromosomal Aberration Assay

human peripheral blood lymphocytes 47560021 (2007) Acceptable/guideline 0, 267, 534, 1068, or 2136 μg/mL (+/

- S9) There was no evidence of chromosome aberrations induced over background in the presence or absence of S9

- activation.

Cytogenetics
870.5385
Mammalian Bone
Marrow Chromosome
Aberration Test No study available Waived
Memo D364576 (2009)

Cytogenetics

- other
870.5395 In Vivo
Mammalian Cytogenetics

- Erythrocyte
Micronucleus

- mouse 47560022 (2007) 0, 500, 1000, or 2000 mg/kg (limit dose) No significant increase in the frequency of micronucleated polychromatic erythrocytes in bone marrow after any
treatment time.

Other Genotoxicity

No other genotoxicity studies are available.

A.4.7 Neurotoxicity

870.6100 Delayed Neurotoxicity Study

- HenAminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 69 of 78 Not available and not required.
870.6200 Acute Neurotoxicity Screening Battery

EXECUTIVE SUMMARY : In an acute neurotoxicity study (MRID 47725702 ), DPX

- MAT28 (92.2% a.i.; Lot # 009) in 0.5% aqueous m ethylcellulose was administered once via gavage (5 mL/kg) to 10 Sprague

- Dawley rats/sex/gr oup at dose l evels of 0, 200, 1000, or 2000 mg/kg (limit dose). Neurobehavioral assessment (functional observational battery [FOB] and motor activity testing) was performed on all rats at pre

- dosing and Days 1 (approximately 2 hours post

- dosing; estimated time of peak effect), 8, and 15. At study termination, 5 rats /sex/group were anesthetized and perfused in situ for neuropathological examination. The tissues from the perfused animals in the control and 2000 mg/kg groups were subjected to histopathological
evaluatio n of brain and peripheral nervous system tissues. Acceptable positive control data were provided.

There were no treatment

- related effects on mortality, clinical signs of toxicity , body weight, food consumption, brain weight , body weight gain, gross patho logy

, or neuropathology. FOB and motor activity testing revealed no treatment

- related effects.

There were no neurological effects observed at any dose in either sex.

The LOAEL was not observed

. The NOAEL is 2000 mg/kg (limit dose).

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

870.6200 Subchronic Neurotoxicity Screening Battery

EXECUTIVE SUMMARY : In a subchronic oral and neuroto xicity study (MRID 47573403 ), aminocyclopyrachlor (DPX

- MAT28; 92.2 % a.i.; Batch No. DPX

- MAT28

- 009 ) was administered in the diet to Crl:CD(SD) rats ( 15/ sex/dose) at doses (adjusted for purity) of 0, 600, 2000, 6000, or 18,000 ppm (equivalent to 34.8/44.8, 1 14.3/145.7, 349.4/448.0, and 1044.6/1424.9 mg/kg/day) for 13 weeks (94

- 95 days in males and 96

- 97 days in females). Neurobehavioral assessment (functional observational battery [FOB] and motor activity testing) was performed prior to treatment and during Weeks 4, 8, and 13 on 10 rats/sex/group. On Day 56, plasma
concentrations of DPX

- MAT28 and the metabolite IN

- LXT69 were measured in 5/sex/dose. At study termination, gross and histopathology were performed on 10 rats/sex/group, while 5

rats /sex/group wer e anesthetized and perfused in situ for neuropathological examination. The tissues from the perfused animals in the control and 18,000 ppm groups were subjected to histopathological evaluation of brain, spinal cord, and peripheral nervous system tissues.

All animals survived to the day of scheduled sacrifice. One control male and one 6000 ppm female were accidentally killed during blood collection just prior to necropsy.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 70 of 78 No treatment

- related effects were observed in daily or weekly clinical observations and there
were no test substance

- related opthamological signs for either sex. There were no test substance

related or statistically significant effects on functional obser vational battery (FOB) parameters: forelimb and hindlimb grip strength, footsplay, body temperature, or behavioral parameters in either sex. Additionally, there were no test substance

- related or statistically significant effects on
duration of movement o r number of movements measured in the motor activity analysis of males
and females.

At 18,000 ppm, decreases (p≤0.05; except as noted) in body weights were observed in the males from Days 28

- 91 (↓6

- 9%, NS at Days 56 and 70) and in the females on Days 56 , 70, and 77 (↓8

- 10%). Overall (Days 0

- 91) body weight gain was decreased (p≤0.05) by 15

- 18% in both sexes. Significant decreases (p≤0.05) in food consumption were observed at 18,000 ppm during Days
0

- 7, 21

- 28, and 42

- 49 in males (↓7

- 8%) and during Days 7 0

- 77 in females (↓11%). D ecreased (p≤0.05) food efficiency was noted in males during Days 21

- 28, 70

- 77, and 77

- 84 (↓18

- 73%) and in females during Days 62

- 70 (↓112%). Overall (Days 0

- 91) food efficiency was decreased (p≤0.05) by 11% in males and 17% in fema les.

There were no adverse effects of the test substance on organ weights, ophthalmology, hematology, coagulation, clinical chemistry, or urinalysis parameters in males and females. There were no effects of the test substance on brain weights or gross or microscopic neuropathology in either sex at any dose.

The plasma concentrations of DPX

- MAT28 and the metabolite IN

- LXT69 were measured on Day 56 by high performance liquid chromatography with detection by tandem mass spectrometry (LC/MS/MS, MRID 47560007 ). DPX

- MAT28 was the most abundant metabolite in male and female rats, with the highest concentrations at 10, 268 and 13, 428 ng/mL for 18,000 ppm male and female rats, respectively. In contrast, plasma levels of IN

- LXT68 were lower for this dose group at concentrations of 82 and 80 ng/mL for males and females, respectively. The average
concentration of DPX

- MAT29 in plasma was higher in females than in males at all dose levels.
The IN

- LXT69 plasma concentrations were below the limit of quantitation for t he 600 ppm dietary concentration. The average IN

- LXT69 plasma concentrations appeared to be similar for males and females. There was no apparent plateau for the DPX

- MAT28 of IN

- LXT68 plasma concentrations when compared to dietary intake levels (e.g. plas ma concentrations increased with increasing concentration in the diet).

The LOAEL for systemic effects is 18,000 ppm (1044.6/1424.9 mg/kg/day) , based on decreased body weights, body weight gains, food consumption, and food efficiency in both

sexes. The NOAEL is 6000 ppm (349.4/448.0 mg/kg/day)

.

The LOAEL for neurotoxicity was not observed. The NOAEL is 18,000 ppm (1044.6/1424.9 mg/kg/day) in both sexes.

The study is classified as Ac ceptable/ G uideline and satisfies the guideline requirements for a
90

- day oral toxicity study (OPPTS 870.3100; OECD 408) and a subchronic neurotoxicity study ( OPPTS 870.6200b ; OECD 424 ) in rats.

.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 71 of 78 870.6300 Developmental Neurotoxicity Study

Not available and not required at this time.

A.4.8 Metabolism

870.7485 Metabolism

- Rat

EXECUTIVE SUMMARY In this metabolism stud y (MRID 47 560023 ), [ p yra midine

- 2

- 14 C]

- DPX

- MAT28 ( aminocyclopyrachlor ; Lot No. 01 ; radiochemical purity 99. 5 %) in 0.5% methylcellulose (4 ml/kg) was administered by a single oral gavage to groups of Sprague Dawley

rats for the following studies: (i) a pilot m ass balance stud y conducted on one rat/sex dosed at 25 mg/kg; (ii) a b lood pharmacokinetic stud y conducted on four rats/sex given either a 25 or 500 mg/kg dose ; and (iii) a plasma me tabolite study conducted on three rats/sex dosed at 500 mg/kg

. Metabolite profiles were also determined for urine and feces collected in the pilot mass balance study

.

DPX

- MAT28 was absorbed with peak concentrations occurring in plasma and RBCs at 0.3

- 1.0 h
post

- dosing. The AUC for DPX

- MAT28 was 7.0

- 9.0 g*h/g at 25 mg/kg and 150.8

- 168.4 g*h/g at 500 mg/kg, a difference of approximately 19 to 21

- fold, which scaled with the 20

- fold difference in dose. The majority of the whole blood radiolabel was foun d in the plasma (60%), with about 40% in RBCs, Total recoveries of the administered dose (AD) were 69.9% for the male (which is low) and 107.9% for the female. DPX

- MAT28 was rapidly eliminated after a single oral gavage dose, with mean elimination half

- life values of 5.6

- 5.7 h for plasma at 25 or 500 mg/kg. The majority of radioactivity was recovered 0

- 24 h post

- dosing, with 35.8

- 53.71%
eliminated in the urine of males and females and 31.4

- 48.0% eliminated in the feces of males and
females No radioactiv ity was detected in the expired air as exhaled volatiles or CO 2 for DPX

MAT28. Cage wash accounted for a small portion (0.36

- 1.21% AD) of radioactivity, and a minor amount of radioactivity was detected in the residual feed. At 168 h post

- dosing, the
resi dual carcass of the male accounted for 0.04% AD; radioactivity was below the limit of
detection in the collected tissues from both sexes and in the female residual carcass.

Plasma, urine, and feces were examined for metabolites at 30 minutes, 24 hours, an d 24 hours, respectively. Only a single peak was observed in each matrix, and was identified as unmetabolized parent. In a concurrently reviewed subchronic oral toxicity study in rats (MRID 47573403), a metabolite (IN

- LTX69) was quantified in plasma; how ever, this metabolite was not detected in the present study following a single dose of the test compound. Control pooled plasma samples and pre

- dose urine and fecal samples were fortified with radiolabeled DPX

MAT28 dosing solution to determine stability at 3 (feces), 10 (urine), and 14 (plasma) days; no noticeable differences were observed, indicating that the test compound was stable in the plasma, urine, and feces, and in the prepared sample extracts.

This metabolism study is classified Acceptable/Guid eline and satisfies the guideline requirement for a Tier 1 metabolism study [OPPTS 870.7485, OECD 417] in rats.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 72 of 78 EXECUTIVE SUMMARY : A previous study (MRID 47560023) characterized the plasma pharmacokinetics of DPX

- MAT28 in male and female rats a fter administration of a single low or high dose and provided a pilot material mass balance.

In metabolism studies (MRID 48333610), [pyrimidine

- 2

- 14 C]

- aminocyclopyrachlor ( 14 C

- DPX

MAT28 ) (9 9.5 % radiochemical purity) was administered in 0 .5% methylcellulose by oral gavage

to male and female Sprague

- Dawley Crl:CD(SD) rats (4/sex/dose). Control animals (1/sex/dose)
were administered 0 .5% methylcellulose . Different study designs were employed to investigate metabolism and disposition.

In the first study, 1 4 C

- DPX

- MAT28 was administered at a single dose of 25 or 500 mg/kg bw. Total recovery and recovery in urine, feces, and as exhaled CO 2 were monitored for 72 hours. Total recovery was excellent at ≥97.4%. Negligible amounts were exhaled as CO 2 . Recoveries in urine and feces were similar for both sexes and doses (with feces being slightly higher) and

was near

- complete by 72 hours. Recoveries in urine peaked at 6 hours, whereas recoveries in feces peaked at 12

- 24 hours. At 72 hours, percent re coveries in urine were 47.74 ± 3.75 and
40.04 ± 5.14 for males at 25 and 500 mg/kg bw. For f emales, these values were 56.51 ± 14.55 and 44.08 ± 4.78, respectively. Percent recoveries in feces at 72 hours were 47.97 ± 3.32 and
54.76 ± 5.14 for males at 25 and 500 mg/kg bw. For females, these values were 39.48 ± 13.42 and 51.08 ± 3.33and 56.51 ± 14.55, respectively.

In the second study, biliary elimination was examined by administration of a single dose of 25 or 500 mg/kg bw in bile duct

- cannulated r ats for 48 hours. Total recovery and recovery in urine,
feces , and bile were monitored for 48 hours. Total recovery was excellent at ≥ 95.1 %. Maximum recoveries and times of peak recoveries in urine and feces were similar to uncannulated rats. However, a larger fraction of radioactivity was increased in the feces than the urine. At 48 hours, percent recoveries in feces were 62.06 ± 3.41 and 57.86 ± 7.77 for males at 25 and 500 mg/kg bw and 68.47 ± 6.59 and 60.68 ± 4.87, respectively, for females. In uri ne at 48 hours, percent recoveries were 34.52 ± 3.57 and 30.06 ± 7.89 at 25 and 500 mg/kg bw for males and 22.18 ± 2.13 and 32.24 ± 5.60, respectively for females. Maximum excretion in the bile for both sexes occurred by 6 hours. However, total excretion in the bile within 48 hours was low at less than 0.3% for both sexes at both doses. Together, this data indicate a minor role for enterohepatic circulation in the metabolism of 14 C

- DPX

- MAT28

.

The tissue distribution of radiolabel was observed at T M AX (1 hour), T MAX + 5 hours, and 72 hours following a single oral (gavage) dose of 25 or 500 mg/kg bw in males/females. The majority of the dose was found in the GI contents (46.7

- 67.0%) and GI tract (9.54

- 13.08%) in both sexes at both doses by T MAX + 5 h ours without an apparent dose

- related increase. Radioactivity was largely absent in the GI contents/GI tract by 72 hours (<<1%). The highest levels or radiolabel for both sexes and doses were found in the carcass (up to about 5%), followed by the muscle (up to 2%), skin (up to 1.4%), and blood (up to 1%). Again, there was no apparent dose

- related increase in tissue levels. However, levels in all of these tissues declined to very low levels (<0.5%) by 72 hours. The apparent lack of dose

- related increase in the tissue content of radiolabel suggested saturation of uptake.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 73 of 78 Tissue distribution after repeated dosing the 25 mg/kg bw/day for 14 days was also examined. On Day 13 at 6 hours following dose administration , Levels were again highest in the GI tra ct (0.16

- 0.22%) and GI contents in males/females (7.11

- 1.14%), but were reduced in magnitude compared to 6 hours following single

- dose administration of 25 mg/kg in the GI tract (1.36

- 1.42%) and GI contents (41.7% and 46.77%) in both sexes. Tissue distrib ution was similar with carcass > skin > blood, with all levels less than 0.5% within 6 hours of dosing and less than 0.05% by 72 hours.

The analysis of urine, feces and bile for potential metabolites clearly showed that 14 C

- DPX

MAT28 was the sole 14 C com ponent in excreta. No metabolism was evident.

This metabolism study in the rat is classified acceptable/guideline and satisfies the guideline requirement for a metabolism study [OPPTS 870.7485 ( § 85

- 1)] in rats.

870.7600 Dermal Absorption

- Rat

Not available and not required at this time.

A.4.9 Immunotoxicity

870.7800 Immunotoxicity

EXECUTIVE SUMMARY : In an immunotoxicity study (MRID 47560025 ) DPX

- MAT28 (Aminocyclopyrachlor; 92.2% a.i.; Batch No. DPX

- MAT28

- 009) was administered to ten male Sprague Dawley (Crl:CD[SD]) rats/ dose group in the diet at dose levels of 0, 600, 6,000 or 18,000 ppm ( equivalent to 0, 42, 407, and 1277 mg/kg bw/day) for 28 days

. An additional group of five rats were dosed by intraperitoneal injection (10 mL /kg) with 25 mg/kg cyclophosphamide monohydrate to serve as positive controls

. Systemic toxicity parameters were evaluated, and immunotoxicity was investigated by performing an enzyme

- linked immunoabsorbant assay (ELISA) to measure serum IgM responses to sheep red blood cells (sRBC) following
immunization with sRBC.

Systemic toxicity was not observed

. There were no effects of treatment on mortality, clinical signs, body weights, body weight gains, food consumption, food efficiency, organ weights, or

gros s pathology at any dose level.

The LOAEL for systemic toxicity wa s not observed . The NOAEL for systemic toxicity is 18,000 ppm (equivalent to 1277 mg/kg bw/day in males )

.

There was no evidence of immunotoxicity. No effects of treatment were observed on the humoral immune response as measured by the primary serum IgM antibody response to the T

dependent antigen, sheep erythrocytes. Spleen and thymus weights were unaffected by

treatment.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 74 of 78 Positive control rats demonstrated an 82% decrease in Log 2 titer compared to concurrent controls, demonstrating the ability of this ELISA to detect suppression of the humoral immune

response.

The LOAEL for immuno toxicity was not observed

. The NOAEL for immuno toxicity is 18,000 ppm (equivalent to 1277 mg/kg bw/day in males )

.

This immunotoxicity study is classified Acceptable/Guideline and satisfies the guideline requirement s (OPPTS 870.7800) for an immunotoxicity study in rats.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 75 of 78 EXECUTIVE SUMMARY : In an immunotoxicity study (MRID 47560026 ) DPX

- MAT28 (Aminocyclopyrachlor; 92.2% a.i.; Batch Nos. DPX

- MAT28

- 009) was administered to ten male
CD

- 1 (Crl:CD[ICR]) mice/ dose group in the diet at dose levels of 0, 300, 3,000 or 7,000 ppm ( equivalent to 0, 45, 425, and 1056 mg/kg bw/day) for 28 days

. An additional group of five mice were dosed by intraperitoneal injection (10 mL/kg) with 25 mg/kg cyclophosphamide monohydrate to serve as positive controls

. Systemic toxicity parameters were evaluated, and immunotoxicity was investigated by performing an enzyme

- linked immunoabsorbant assay (ELISA) to measure serum IgM responses to sheep red blood cells (sRBC) following
immunization with sRBC.

Systemic toxicity was not observed. There were no effects of treatment on mortality, clinical signs, body weights, body weight gains, food consumption, food efficiency, organ weights, or gross pathology at any dose level.

The LOAEL for systemic toxicity was not observed. The NOAEL for systemic toxicity is
7 000 ppm (equivalent to 1 056 mg/kg bw/day in males ).

There was no evidence of immunotoxicity. No effects of treatment were observed on the humoral immune response as measured by the primary serum IgM antibody response to the T

dependent antigen, sheep erythro cytes. Spleen and thymus weights were unaffected by

treatment.

Positive control mice demonstrated a 73 % decrease in Log 2 titer compared to concurrent controls, demonstrating the ability of this ELISA to detect suppression of the humoral immune

response.

The LOAEL for immunotoxicity was not observed. The NOAEL for immunotoxicity is
7 000 ppm (equivalent to 1 056 mg/kg bw/day in males ).

This immunotoxicity study is classified Acceptable/Guideline and satisfies the guideline requirement s (OPPTS 870.7800) fo r an immunotoxicity study in mice.

Appendix B

. Review of Human Research

This risk assessment relies in part on data from studies in which adult human subjects were intentionally exposed to a pesticide to determine their dermal and inhalation exposure. Many such studies, involving exposure to many different pesticides, comprise generic pesticide exposure databases such as PHED and the Outdoor Residential Exposure Task Force (ORETF). EPA has reviewed all the studies supporting these multi

- pesticide gene ric exposure databases, and has found no clear and convincing evidence that the conduct of any of them was either fundamentally unethical or significantly deficient relative to the ethical standards prevailing at
the time the research was conducted. All a pplicable requirements of EPA’s Rule for the Protection of Human Subjects of Research (40 CFR Part 26) have been satisfied, and there is no regulatory barrier to continued reliance on these studies.Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 76 of 78 Appendix C: Chemical Structures of Degradates

The foll owing chemical structures of the 5 environmental degradates of aminocyclopyrachlor

were obtained from HED’s ― Aminocyclopyrachlor. Report of the Residues of Concern
Knowledgebase Subcommittee (ROCKS)‖ memorandum (from G. Kramer, October 15, 2009,

D3706 38).

Degradate 1: IN

- LXT69

IUPAC Name:

5

- Chloro

- 2

- cyclopropyl

- pyrimidin

- 4

- ylamine

CAS Name :
Not reported

CAS. No.:

Not reported

Degradate 2: IN

- QFH57

IUPAC Name:

4

- Cyano

- 2

- cyclopropyl

- 1H

- imidazole

- 5

- carboxylic acid

CAS Name :

4

- Cyano

- 2

- cyclopropyl

- 1H

- imidazole

- 5

- carboxylic acid

CAS. No.:

Not reportedAminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 77 of 78 Degradate 3: IN

- Q3007

IUPAC Name:

Cyclopropanecarboxamide

CAS Name :
Cyclopropanecarboxamide

CAS. No.: 6228

- 73

- 5

Degradate 4: IN

- V0977

IUPAC Name:

Cyclopropanecarboxylic acid

CAS Name :
Cyclopropanecarboxylic acid

CAS. No.: 1759

- 53

- 1Aminocyclopyrachlor Human Health Risk Assessment DP No. 387448

Page 78 of 78 Degradate 5: IN

- YY905

IUPAC Name:

Cyclopropanecarboximidamide

CAS Name :
Cyclopropanecarbamidine

CAS. No.: Not reported