UNITED STATES ENVIRONMENT AL PROTECTION AGENCY



### MEMORANDUM

DA TE: 7 1 09115 WASHINGTON, DC 20460

OFFICE OF

CHEMICAL SAFETY AND POLLUTION

PREVENTION



### SUBJECT: Chlorimuron-Ethyl Toxicology Data Evaluation Records.

PC Code: 128901

Decision No.: N/A

Petition No .: NIA 

### DP Barcode: D397470
Registration Nos.: N/A
Regulatory Action: N/A

Case No.: NA Risk Assessment Type: N/A

TXR No. : 0056215 CAS No.: 

### 90982-32-4

40 CFR: N/A MRID No.: See table



### FROM :

THRU:

TO: Karlyn Middleton, Toxicologist 

# h

Registration Action Branch 2

## ~ Health Effects Division (7509 P)

Christina Swartz, Chief 

# /'"\n '**.A~** Registration Action Branch 2

# ~\)-l Health Effects Division (7509 P)

Heather Garvie, Mindy Ondish PM Team 24

Herbicide Branch Registration Division (7505P)



### ACTION REQUESTED: The Health Effects Division (HED) was asked to review toxicology

studies submitted for chlorimuron-ethyl. The studies have been reviewed and data evaluation

records (DERs) have been prepared for the studies (see Table I)

.



### BACKGROUND: Chlorimuron ethyl is an herbicide of the sulfonylurea class. Its mode of

action is through inhibition of the plant enzyme acetolactate synthase, which is also known as acetohydro x y acid synthase

. Inhibition of this enzyme blocks branched-chain amino acid biosynthesis of valine, leucine, and isoleucine (involved in plant growth) processes and leads to

death of the plant. Chlorimuron ethyl is registered for use on soybeans, field corn, peanuts, low growing berries (subgroup l 3-07H

, except strawberry) and non-crop areas such as fence rows and

roadsides for the control of broadleaf weeds and grasses.

Page 1of2

### Page 2 of 2 Table 1. List of Chlorimuron

- ethyl Toxicology Studies with New Data Evaluation Records

MRID Number Guideline [OCSPP] STUDY TITLE

48704301 870.7485 S UBCHRONIC ORAL NEUROTOXICITY STUDY IN RATS

48704302 870.6200 ACUTE ORAL NEUROTOXICITY STUDY IN RATS

### DATA EVALUATION RECORD Chlorimuron Ethyl

PC Code: 128901

TXR#: 0056215

MRID#: 48704301

Study Type: Subchronic Neurotoxicity [feeding]

- 90- Day Study in 

### Crl:CD(SD) rats

OPPTS 870.7800

Prepared for

Health Effects Division Office of Pesticide Programs U.S. Environmental Protection Agency

One Potomac Yard 2777 S. Crystal Drive Arlington, VA 22202

Prepared by

Tetrahedron Incorporated 1414 Key Highway, Suite B Baltimore, MD 21230

Principal Reviewer: _____________________________________ Date: 5/25/2012 Ahmed Elnabawi, Ph.D.

Secondary Reviewer: _____________________________________ Date: 5/29/2012 Katherine Squibb, Ph.D.

Quality Assurance:

_________________________________________ Date: Nasrin Begum, Ph.D.

Contract Number: EP -W-10013 Work Assignment No.: WA -0-01

Task Number: 1-1-88

EPA Reviewer//WAM: Swartz and Levy//Farwell and Brunsman

Disclaimer

This review may have been altered by the EPA subsequent to the contractors’ signature

above.Subchronic Neuroto x icit y S tud y ( rat s) (2011) /P ag e 2 o f 16

C hlorimuron Eth 1 / 128901 OPPTS 870

. 6200b / MAFF 12 No u

. 8147 / 0 E CD 424



### EPA Reviewer: Karlyn Middleton 

### Signature:**--1- -~--** **--** 

### Risk Assessment Branch 2, Health Effects Division (7509P) Date:**~~~~~~~~~** 

### EPA Work Assignment Manager: Lori Brunsman 

### Signature;.

Science Info. Mgmt. Branch, Health Effects Division (7509P) Date.**---#-,'-4-+1-.~--**



### TXR#: 0056215

DATA EVALUATION RECORD

STUDY TYPE: Subchronic Neurotoxicity, (oral

, feeding) :._ (rat); OPPTS 870.6200b [§82-7],

OECD 424; MAFF 12 Nousan 8147 ; EEC B.43 Directive 2004/73/EC

.



### PC CODE: 128901 

### DP BARCODE: D397470



### TEST MATERIAL (PURITY): Chlorimuron Ethyl (DPX

- F6025) (97

. 5% a.i.).



### SYNONYMS: Ethyl 2-( 4

- chloro-6-methoxypyrimidin-2-ylcarbamoylsulfamoy l)benzoate ; Ethyl

2

- [[[[(4-chloro- 6 -metho xy -2-pyrimidinyl)amino]carbon y l]amino]sulfon y l) ben z oate ; DPXF6025-258

.



### CITATION: Satheesh Anand

, S

. (2011). Chlorimuron Ethyl (DPX

- F6025) Technical:

Subchronic Oral Neurotoxicity Study in Rats. E.I. du Pont de Nemours and Company, DuPont Haskell Global Centers for Health and Environmental
Sciences, Newark, Delaware, U.S.A

. Laboratory project numbers: DuPont-31864

, December 15

, 2011. MRID 48704301. Unpublished

.



### SPONSOR: E.I. du Pont de Nemours and Company, Wilmington, Delaware 19898

, U.S.A.



### EXECUTIVE SUMMARY:

In a subchronic neurotoxicity study (MRID 48704301)

, Chlorimuron Ethyl (DPX-F6025)

technical (97.5 % a.i.

, batch# MAR09MA047) was administered in the diet to young adult Crl:CD(SD) rats (12 / sex/dose) at concentration levels of 0

, 500

, 1

, 250

, or 3

, 750 / 5

, 000 ppm (equivalent to 0 / 0, 27/35

, 71 / 90, and 220 / 259 mg/kg/day in males and females, respectively) for approximately 90 days (95-97 days). At Week 9

, the high dietary concentration was increased

from 3,750 to 5,000 ppm as there were minimal or no test substance-related changes observed in

the 3

, 750 ppm groups at this time. Neurobehavioral assessment (functional observational battery

and motor activity testing) was performed on all animals prior to test substance administration (baseline)

, and during Weeks 4, 8

, and 13. At study termination (Days 95 and 96), 6

animals / sex / group were euthanized and perfused in s itu 

### for neuropathologica l examination

. The

brain and peripheral nervous system tissues collected from the perfused animals in the control

and 3

, 750/5

, 000 ppm groups were subjected to histopathological evaluation.

There were no test substance-related effects on mortality or clinical signs at any dietary

concentration level in males and females.

Treatment-related effects on body weights were evident at the high concentration (3,750 / 5,000 ppm) in females

, but not in males. Body weights were significantly reduced by 16

- 10% (Day 21 through Day 91) at 3,750 / 5,000 ppm in females. On Day 84, lower (p :S 0

. 05) mean body weightSubchronic Neurot oxicity Study (rats) (201 1 ) /Page 3 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### was noted in the 1,250 ppm (↓7%) group females. No significant differences in body weights were observed in 500 ppm group females. Mean body weight gain s were significantly lower during test Day 0- 7 (↓34%), Day 14

- 21 (↓40%), and Day 0

- 28 (↓21%) in the 3,750/5,000 group

of females. Overall (0 -91) body weight gains were significantly lower at 1,250 ppm ( ↓ 15%) and 3,750/5,000 ppm ( ↓ 24%) in females when compared to the control group. In males, n o test
substance- related or statistically significant effects were noted on body weight or body weight gain at any dietary concent ration level.

Test substance -related decreases on mean daily food consumption were evident in the high dietary concentration (3,750/5,000 ppm) females. Mean food consumption was significantly reduced by 9 -18% in the 3,750/5,000 ppm group females from Day 14-21 through the end of the treatment period. In addition, lower (p≤0.05) mean food consumption was observed at the dietary concentration of 1,250 ppm on Day 63-70 ( ↓ 11%) and Day 56-91 ( ↓ 8%). Overall (0

- 91) mean food consumption was significantly decreased by ↓12% at 3,750/5,000 ppm; whereas

, overall (0

- 91) mean daily food consumption at concentrations of 500 and 1,250 ppm was similar to the control. In males, no treatment- related or statistically significant effects on mean daily food consumption were seen at any dietary concentration level. There were no test substance

- related effects on food efficiency in the 500, 1,250, or 3,750/5,000 ppm group males or females.

No test substance-related effects on FOB (home cage, open field, removal from the h ome cage and handling) parameters, rearing, forelimb and hindlimb grip strength, body temperature or motor activity (duration of movements and number of movements) were observed at any dose

level in either sex.

There were n o test substance- related alte rations in gross histopathology observations or microscopic neurohistopathology in the 3,750/5,000 ppm group male s and female s.

It is concluded that there were no neurotoxic effects observed at any dietary concentration level

, based on the lack of altered behavior in the FOB parameters, no significant changes observed on motor activity (duration of movements and number of movements), and no effects on the macroscopic and microscopic pathology of nervous system tissues. How ever, systemic toxicity

of was observed in the 3,750/5,000 ppm group females , but not in males . This was characterized by treatment related decreases in body weight and body weight gains and significant reductions in food consumption.

The systemic NOAEL is 1,250 ppm (equivalent to 71/90 mg/kg/day ), based on decreased body weight and body weight gains and reduced food consumption observed in females at

the LOAEL of 3,750/5,000 ppm (equivalent to 220/259 mg/kg/day, M/F respectively ).

The NOAEL for neurotoxicity is the highest dose tested 3,750/5,000 ppm (equivalent to 220/259 mg/kg/day, M/F respectively) since no treatment related neurotoxic effects were seen in the study.

This study is classified as acceptable/guideline and satisfies the guideline requirement ( OPPTS

870.6200b ; OECD 424 ) for a subchronic neurotoxicity study in rats.

COMPLIANCE : Signed and dated GLP, Quality Assurance, Flagging, and Data Confidentiality (no claim of confidentiality under FIFRA, but waiver does not apply to other regulatory agencies and information is labeled trade secret) were provided.Subchronic Neurot oxicity Study (rats) (201 1 ) /Page 4 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### I. MATERIALS AND METHODS:

A. MATERIALS :

1. Test material : Chlorimuron E thyl (DPX

- F6025 ) Technical

Description: Crystalline, powder

Lot/Batch #: MA R 0 9 MA047 Purity: 9 7.5 % a.i. Compound Stability: The Sponsor stated that the test substance was considered to be stable when stored at room temperature for up to 24 days.

CAS # of TGAI: 90982

- 32

- 4

Structure:



### 2. Vehicle : Diet

.

3. Test animals : Species: Rat

Strain: Crl : CD(SD )
Age/weight at study initiation: 5 2 day s of age

. Males: 223.2

- 272.1 g ; Females: 16 1

. 7

- 19 6

. 3 g

. Source: Charles River Laboratories , Inc., Raleigh, NC

. Housing: Housed in pairs in solid bottom caging with bedding mixed with enrichment (Shepherd’s TM Cob + PLUS TM ). Each cage rack contained only animals of one sex

Diet: PMI ® Nutrition International, LLC Certified Rodent LabDiet ® 5002

, ad libitum

, except during neurobehavioral testing

. Water: Tap water, ad libitum

, except during neurobehavioral testing

. Environmental conditions: Temperature: Humidity: Air changes: Photoperiod: 20

- 2 6 °C

30

- 70 %

Not stated

12 hrs dark / 12 hrs light Acclimation period: 7 days



### B. STUDY DESIGN :

1. In life dates: Start: March 11 , 2011 ; End: June 16, 2011.

2. Animal assignment and dose rationale : Animals were randomly assigned to the test groups noted in Table 1 using a weight stratification -based computer program. The body weights of

all animals were within ±20% of the mean weight for each sex. Test substance was

administered orally in the diet to rats at dietary concentration levels of 0, 500, 1,250 and 3,750/5,000 ppm for 90 days (95-97 days).

Dose levels were chosen based on the results of a subchronic toxicity study in rats, conducted

with the test substance at concentration levels of 0, 100, 2,500 and 7,500 ppm ( 1 )



### . In th at study, reduced body weights and nutritional parameters were observed at dietary concentration level of 7, 50 0 ppm in ma les and at 2,500 and 7,500 ppm in females. In

1 DuPont Haskell (1983). Ninety

- day feeding and one

- generation reproduction study in rats with benzoic acid, 2 -[[[[(4- chloro -6- methoxy -2- pyrimidinyl)amino]carbonyl]amino]sulfonyl]

- ethyl ester (INF

- 6025). Unpublished DuPont report, HLR

- 306

- 83.Subchronic Neurot oxicity Study (rats) (201 1 ) /Page 5 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### addition, a higher incidence of margination of hepato cyte cytoplasmic contents was observed in the 2,500 and 7,500 ppm males group and in the 7,500 ppm females group. No clinical signs were observed at any dietary concentration level. Therefore, the no- observed

- adverse

effect (NOAEL) in for the subchronic toxicity was 100 ppm.

Based on these results, the concentration levels selected for the current study were 500 ppm (low concentration ), 1,250 ppm (mid concentration ) and 3,750/5,000 ppm (high concentration) (Table 1) . Starting from Week 9, however, the high-dietary concentration of 3,750 ppm was increased to 5,000 ppm due to a lack of treatment

- related changes observed in this group.

TABLE 1. Study Desi gn

Experimental parameter Concentration in Diet (ppm)

0 5 0 0 1, 2 5 0 3, 7 5 0 /5,00 0 a
Achieved dose (mg/kg/day; M/F) 0/0 27 /3 5 71 / 90 220 / 259 Total number of animals/sex/group 12 12 12 1 2 Behavioral testing (FOB, Motor activity) 1 2 /sex 1 2 /sex 1 2 /sex 1 2 /sex
Neuropathology 6 /sex 0 /sex 0 /sex 6 /sex

a= The dietary concentration of test substance was increased from 3,750 to 5,000 ppm starting from Week 9.

Concentrations of test substance were adjusted for purity of active ingredient

. Data were extracted from page s 12 and 14 of the study report.



### 3. Test Substance preparation and analysis : All diet formulations were prepared by mixing appropriate amounts of test substance with the diet (PMI ® 

### Nutrition International, LLC

Certified Rodent LabDiet ® 

### 5002) and stored refrigerated

. Homogeneity and concentration analyses of test substance were verified in diet samples (top, middle, and bottom) at dietary

concentrations of 500, 1,250 and 3,750 ppm at the start of the study and at 5,000 ppm s tarting from Week 9, whe n the high diet concentration was increased to 5,000 ppm

. Stability of test

substance in the diet was verified at concentration s of 50 and 20,000 ppm for 10, 17, and 24 day s at room temperature storage prior to the start of the study.

Results Homogeneity analysis ( % RSD): 1-3 %.

Stability analysis: T he test substance was stable in the diet at concentrations of 500 and 20,000 ppm for up to 24 day s at room temperature

.

Concentration analysis (range as % nominal): 93.2-102%.

The se analytical data indicated that the mixing procedure was adequate and that the variance between nominal and actual dosage to the animals was acceptable.

4. Statistics : The data were presented as mean± standard deviation (SD). Each test substance exposed group was compared to the control group for the parameters listed below. The data

were analyzed using the following statistical methods and significance was defined at p ≤ 0.05 or p≤0.01 for all tests

.Subchronic Neurot oxicity Study (rats) (201 1 ) /Page 6 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424

Parameters Statistical Methods

- Body weight

- Body weight gain

- Food consumption

- Food efficiency Levene’s test for homogeneity and Shaprio

- Wilk test for normality. If preliminary test was not significant, o ne

- way analysis of variance followed by Dunnett’s test was used to compare treated groups with control groups

. If preliminary test was significant, transforms of the data were used. The

rank order of transform s was log, square

- root, and rank

- order

.

- Rearing

- Grip strength

- Foot splay

- Body temperature

- Motor activity Levene’s test for homogeneity and Shaprio

- Wilk test for normality. If preliminary test was not significant, repeated measures analysis of variance

was followed by linear contr a sts . If preliminary test was significant, a normalizing, variance stabilizing tr ansformation followed by repeated measures analysis of variance or sequential application of the Jonckheere

Terpstra trend test was used

. Incidence FOB, descriptive parameters Cochran

- Armitage test for trend; if the incidence was not significant, but a signif icant lack of fit occurred, Fisher’s Exact test with a Bonferroni

- Holm

correction was used.



### The se stati stical analyses were considered to be appropriate

.

C. METHODS / OBSERVATIONS :

1. Mortality and C linical Observations : Animals were observed twice daily for mortality and moribundity throughout the study. General clin ical observations were recorded once daily throughout the study.

2. Body W eight : Animals were weighed on the days of FOB assessment and weekly during the exposure period.

3. Food C onsumption : Food consumption was recorded weekly throughout the study and reported as g/animal/day. The mean daily food efficiency and mean daily intake of test substance were calculated from the food consumption and body weight data.

4. Cholinesterase determination : Cholinesterase activity was not evaluated.

5. Neurobehavioral A ssessment :

a. Functional Observational B attery (FOB) : All animals were subjected to a FOB during acclimation (baseline) and during Weeks 4, 8 and 1 3. Animals wer e counterbalanced by sex and treatment and tested in replicates over 2 days to minimize the influence of uncontrolled factors. The FOB was conducted by an observer who was “blind” to the treatment status of the animal, and the same observer performed all o f the evaluations.The FOB evaluations were conducted in a sound-attenuated room equipped with a whitenoise-generation system to minimize variations in environmental test conditions. Animals were weighed on the day of the FOB assessment. The time in the o pen

- field was at least 2

minutes.

The following CHECKED (X) parameters were examined.Subchronic Neurot oxicity Study (rats) (201 1 ) /Page 7 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424

HOME CAGE OBSERVATIONS REMOVAL FROM THE HOME

CAGE AND HANDLING OPEN FIELD OBSERVATIONS

X Posture X Ease of removal X Righting reflex

X G ait /coordination X Ease of handling X Gait/coordination

X Convulsions X Vocalization X Muscle spasms/fasciculation

X Tremors X Muscle tone X Convulsions

X Palpebral closure X Piloerection X Tremors

X Fur/skin appearance X Ease of respiration

X Mucous membrane s X Rate of respiration

X Palpebral closure X Posture

NEUROMUSCULAR

OBSERVATIONS X Exophthalmus X Palpebral closure

X Landing foot splay X Lacrimation X Number of rearing movements

X Forelimb grip strength X Salivation X Vocalization s

X Hindlimb grip strength X Dehydration X Arousal

X Emaciation X Approach/touch

PHYSIOLOGICAL

OBSERVATIONS X Papillary constriction/Polyuria /

Diarrhea #

X Body temperature X Tail pinch

X Body weight X Sharp auditory stimulus

P arameters based on OPPTS Guideline 870. 6200

. # Papillary constriction, polyuria and diarrhea were assessed at the end of the m otor a ctivity session. Data were obtained from pages 18

- 20 of the study report.



### b. Motor activity : Motor a ctivity was evaluated after the last animal completed the FOB

pre -exposure (baseline) and during Weeks 4, 8, and 13. An automated Coulbourn ®



### Instruments activity monitor was used with infrared beams for motor activity data

collection. The infrared monitoring device enabled measurements of two dependent variables: duration of movement and number of movements. A continuous movement, regardless of its duration, was counted as one movement by the activity measurement system. The technical characteristics of the measurement system a re such that duration of

movement wa s analogous to “counts” in other types of devices that employ interruption of light beams. Duration of movement and number of movement s were evaluated in 9

consecutive intervals of 10 minutes each as well as for the tota l 90- minute session

.

6. Sacrifice and Pathology : Animal s selected for neuropathological evaluation ( 6 rats/sex/dose) were deeply anaesthetized by i.p. injection of a mixture of ketamine/xylazine and perfused in situ

. Animals were subjected to gross necropsy. The remaining animals were sacrificed by

isoflurane anesthesia and CO 2 

### asphyxiation and were disposed of without any pathological

examinations.

The tissues from the control and high- dose animal s (3,750/5,000 ppm ) were processed for microscopic evaluation. The brain, spinal cord sections, cauda equine, eyes, optic nerve, and gastrocnemius muscle were embedded in paraffin, sectioned at 5μm, and stained with hematoxylin -eosin (H&E). The dorsal root ganglia (including dorsal and ventral root fibers) from the cervical and lumbar swellings, gasserian ganglia, and peripheral nerves were

embedded in glycol methacrylate (GMA) , section ed 3 μm, and stained with hematoxylin

eosin (H&E). Stained histological sections were examined by light microscopy

.

Brai n weight and measurements were not evaluated in this study.Subchronic Neurot oxicity Study (rats) (201 1 ) /Page 8 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### The following CHECKED (X) tissues from the control and high- dose animals, as well as all gross lesions were evaluated.

CENTRAL NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM

BRAIN SCIATIC NERVE

X Forebrain Mid

- thigh Region

X Cerebrum X Sciatic N erve

X Hippocampus X Tibial Nerve
Basal ganglia X Sural Nerve

X Cerebellum

Thalamus

X Pons

X Medulla oblongata OTHER

X Midbrain X Lumbar dorsal root ganglion
Hypothalamus X Lumbar dorsal root fibers

SPINAL CORD X Lumbar ventral root fibers

X Cervical swelling X Cervical dorsal root ganglion

X Lumbar swelling X Cervical dorsal root fibers

X Thoracic swelling X Cervical ventral root fibers

OTHER

X Gasserian Ganglion
Trigeminal nerves

X Optic nerve

X Eye

X Gastrocnemius muscle



### 7. Positive Controls : It was stated in this report that three separate reports (MRID 44628703, MRID 47053501 and MRID 48710304, performed in 1997, 2002 and 2011, respectively) were previously performed by DuPont Haskell to generate positive control data and validate the procedu res and the inter -observer reliability of the performing lab to conduct and assess neurobehavioral and neuropathology tests. The data also documents that the equipment and procedures are capable of detecting effects that may be seen in neurotoxicity studie s. The positive control data is acceptable for use with the current study. Historical control data were not provided in the report.

II. RESULTS :

A. OBSERVATIONS :

1. Mortality: There were no treatment

- related mortalities.

2. General C linical Observations : There were no significant test substance

- related clinical findings in the 500, 1,250 or 3,750/5,000 ppm group males or females.

B. BODY WEIGHT AND BODY WEIGHT GAIN : Summary results of mean body weights and body weight gains are presented in Table 2 (a and b) and Table 3, respectively. There

were no test substance

- related or statistically significant effects on body weight or body weight gain in males at any dietary co ncentration level (Table 2a). The only significant (p≤0.05) difference from the control group was a lower mean body weight gain in theSubchronic Neurot oxicity Study (rats) (201 1 ) /Page 9 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### 3,750/5,000 ppm ( ↓ 14 %) group males on Day 0-7 compared to the control (Table 2a ); however, this finding was considered incidental and not treatment related since there was no dose response relationship and it o ccurred only at one time point . Overall (0 -91) body weight gains were increased by 5

- 7% at concentrations of 500, 1,250 and 3,750/5,000 ppm in males,

but were not st atistically significant ly different and did not change in a dose responsive

manner

.

In contrast to males, treatment

- related effects on body weights were evident in the high dietary concentration (3,750/5,000 ppm) group females (Day 21 though Day 91) (Tab le 2b). At 3,750/5,000 ppm, lower (p≤0.05) body weights ranged from ↓6 -10% in fe males from Day 21 though Day 91. On Days 7 and 14, body weight was reduced by ↓5% in the 3,750/5,000 ppm females compared to the control, but not statistically significant different. No significant differences in body weights were noted in females at dietary concentration levels of 500 or 1,250 ppm compared to the controls, except on Day 84, when a lower (p≤0.05) mean body weight was noted in the 1,250 ppm (↓7%) group females. M ean body weight gains were reduced by ↓ 34%, ↓ 40% and ↓ 21% in the 3,750/5,000 ppm group females during test Day 0- 7, Day 14-21, and Day 0 -28 , respectively, compared to the controls (Table 3). Overall (0-91) body weight gains were significantly lower at 1,250 ppm ( ↓ 15%) and 3,750/5,000 ppm ( ↓ 24%) in females when compared to the control group.

It is concluded that lower body weight gains observed in females, but not in males, in the high concentration (3,750/5,000 ppm) groups were associated with the reductions in body weights observed over the entire study period and were test substance- related. Over the full period of the study (Day 0 to 91), lower mean body weight gains were also observed in the female 1,250 ppm treated group.

TABLE 2 a

. Selected Mean ( ±SD) Body Weights and Body Weight Gains in Male Rats

Exposure Time Concentration i n Diet ( ppm )

0 5 0 0 1, 2 5 0 3, 7 5 0 /5,000

Body Weight (g) Day 0 248.1 ± 9.4 249.9 ± 7.0 251.6 ± 14.1 253.6 ± 7.6 Day 7 308.8 ± 12.8 307.5 ± 9.2 311.9 ± 20.7 305.9 ± 12.5 Day 28 423.4 ± 27.4 426.9 ± 23.7 433.7 ± 35.3 429.6 ± 34.7
Day 63 516.2 ± 43.0 530.7 ± 46.3 526.4 ± 44.2 533.3 ± 54.6
Day 70 528.9 ± 44.3 545.9 ± 46.8 541.6 ± 45.7 549.8 ± 61.2 Day 84 556.8 ± 46.1 578.1 ± 54.9 571.7 ± 51.8 573.7 ± 64.3 Day 91 562.8 ± 46.4 586.4 ± 58.7 581.5 ± 56.5 583.2 ± 65.3 Body Weight Gains (g) Day 0

- 7 60.7 ± 7.8 57.6 ± 6.7 60.3 ± 7.9 52.4±8.2* (↓14%) Day 0

- 28 175.3 ± 24.8 177.0 ± 23.6 182.0 ± 26.9 176.0 ± 30.9
Day 28

- 56 81.7 ± 15.0 88.8 ± 25.7 81.6 ± 18.3 90.7 ± 21.3 Day 56

- 91 57.7 ± 13.5 70.7 ± 21.8 66.3 ± 15.8 62.9 ± 14.5 Overall ( Day 0

- 91 ) 314.7 ± 43.7 336.5 ± 56.4 329.9 ± 50.2 329.6 ± 62.8

Values represent mean ± SD, n=1 2. The dietary concentration level of 3,750 ppm was increased to 5,000 ppm on Week 9

. Percent difference from the control is included in parentheses and was calculated by the Investigator s. * Significantly different from the control group, p ≤0.0 5. Statistically s ignificant results are shown in bold.

Data were obtained from Table s 3 ( pages 32-3 3) and 5 (pages 37

- 39) of the study report.Subchronic Neurot oxicity Study (rats) (201 1 ) /Page 10 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### TABLE 2 b . Mean ( ±SD) Body Weights and Body Weight Gains in Female Rats

Exposure Time Concentration i n Diet (ppm)

0 50 0 1, 2 5 0 3, 7 5 0 /5,000
Body Weights (g) Day 0 183.1 ± 10.5 184.2 ± 6.8 180.9 ± 8.5 181.3 ± 9.0
Day 7 206.6 ± 14.4 207.8 ± 6.8 201.9 ± 12.3 197.0 ± 10.7 Day 14 224.8 ± 16.0 230.9 ± 9.4 217.6 ± 11.8 214.7 ± 13.5 Day 21 238.8 ± 15.1 245.7 ± 11.3 230.9 ± 12.0 223.1 ± 13.0 * (↓ 7 %) Day 28 251.6 ± 19.2 255.5 ± 14.0 241.5 ± 11.8 235.2 ± 15.7 * (↓ 7 %) Day 35 263.6 ± 20.9 274.0 ± 12.5 252.4 ± 11.9 247.0 ± 17.5 * (↓ 6 %) Day 42 271.3 ± 20.8 281.0 ± 13.1 257.3 ± 14.3 254.3 ± 18.7 * (↓ 6 %) Day 49 282.0 ± 20.6 286.1 ± 14.6 266.4 ± 15.8 259.3 ± 20.4 * (↓ 8 %) Day 56 283.1 ± 27.6 286.9 ± 15.4 267.2 ± 16.0 260.8 ± 22.0 * (↓ 8 %) Day 63 292.8 ± 27.8 298.7 ± 18.6 273.4 ± 17.6 266.8 ± 21.1 * (↓ 9 %) Day 70 298.6 ± 27.4 303.7 ± 20.2 277.9 ± 17.3 272.0 ± 19.3 * (↓ 9 %)
Day 77 304.7 ± 26.0 309.0 ± 19.7 285.8 ± 15.0 276.0 ± 19.6 * (↓ 9 %) Day 84 309.0 ± 30.9 310.4 ± 19.9 286.8 ± 15.1 * (↓ 7 %) 278.4 ± 20.1 * (↓ 10 %)
Day 91 308.9 ± 32.0 311.8 ± 20.4 287.7 ± 16.3 277.6 ± 19.7 * (↓ 10 %) Body Weight Gains (g) Day 0

- 7 23.5 ± 7.0 23.6 ± 5.1 21.1 ± 8.1 15.6±5.0* (↓ 34 %)
Day 7

- 14 18.2 ± 7.0 23.1 ± 5.0 15.7 ± 7.0 17.7 ± 5.9 Day 14

- 21 14.0 ± 5.0 14.8 ± 4.1 13.3 ± 6.3 8.4±6.0* (↓ 40 %) Day 21

- 28 12.8±7.2 9.8±8.2 10.6±5.0 12.1±6.6 Day 0

- 28 68.5±10.6 71.2±11.0 60.6±8.5 53.9±9.3* (↓ 21 %) Day 28

- 35 12.0±6.9 18.5±14.7 10.9±10.0 11.8±8.8

Overall ( Day 0

- 91 ) 125.8±25.8 127.6±19.2 106.8±13.0 * (↓ 15 %) 96.2±14.3* (↓ 24 %)

Values represent mean ± SD, n=12. The dietary concentration level of 3,750 ppm was increased to 5,000 ppm on Week 9

. Percent difference from the control is included in parentheses and was calculated by the Investigators. * Significantly different from the control group, p ≤0.05. Statistically s ignifi cant results are shown in bold.

Data were obtained from Table s 4 ( pages 34-3 6) and 6 (pages 40

- 42) of the study report.



### C. FOOD CONSUMPTION : R esults of mean food consumption (g/animal/day) in males and females are presented in Table 4. In males, no test substance- related or statistically significant effects on food consumption occurred at any dietary concentration level. The only significant (p≤0.05) difference from the control group was higher food consumption in the 3,750/5,000 ppm ( ↑8 %) group males on Day 63-70 compared to the controls (Table 4). However, this finding was considered incidental and not treatment related since there was no dose response relationship and it occurred only at one time point . Overall (0 -91) food consumption was not a ffected.Subchronic Neurot oxicity Study (rats) (201 1 ) /Page 11 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### In females, treatment -related effects on mean daily food consumption were evident in the high dietary concentration (3,750/5,000 ppm). Lower ( p≤0.05) mean food consumption ranged ↓9

- 18% from Day 14 -21 though the end of the treatment (Table 4). In addition, lower (p≤0.05) mean food consumption was observed at the dietary concentration of 1,250 ppm on Day 63 -70 ( ↓ 11%) and Day 56-91 ( ↓ 8%). Overall (0 -91) mean food consumption was significantly decreased by ↓12% at 3,750/5,000 ppm; whereas overall (0

- 91) mean daily food consumptions at concentration s of 500 and 1,250 ppm w ere similar to control values

.

It wa s concluded that the effect s on body weight and body weight gains were consistent with the effects observed on food consumption in the high di etary concentration (3,750/5,000 ppm) group females

.

TABLE 3

. Selected Mean ( ±SD) Food Consumption (g/animal/day) in Male and Female Rats

Exposure Time Concentration i n Diet (ppm)

0 5 0 0 1, 2 5 0 3, 7 5 0 /5,000

Males Day 0

- 7 24.5 ± 0.9 23.8 ± 0.6 25.1 ± 1.6 24.1 ± 1.0
Day 7

- 14 26.3 ± 1.6 25.2 ± 1.2 26.5 ± 1.6 27.4 ± 2.4
Day 0

- 28 25.5 ± 1.3 24.9 ± 1.1 26.4 ± 1.4 25.8 ± 1.5
Day 28

- 56 25.6 ± 1.7 25.5 ± 1.3 26.5 ± 1.4 26.6 ± 1.6 Day 63

- 70 24.5 ± 1.8 25.0 ± 1.4 25.6 ± 1.6 26.6±1.7* ( ↑8 %)
Day 84

- 91 24.6 ± 1.4 25.2 ± 1.7 25.3 ± 1.7 25.8 ± 1.8 Overall ( Day 0

- 91 ) 25.3 ± 1.4 25.3 ± 1.2 26.2 ± 1.2 26.2 ± 1.5

Females Day 0

- 7 17.2 ± 1.5 18.2 ± 1.8 17.8 ± 2.2 16.7 ± 3.9
Day 7

- 14 18.3 ± 1.1 19.1 ± 1.8 17.9 ± 1.6 17.4 ± 1.5
Day 14

- 21 19.6 ± 1.5 20.5 ± 1.9 20.1 ± 2.7 17.0 ± 1.6 * (↓ 13 %)
Day 21

- 28 20.1 ± 2.5 19.6 ± 1.5 18.3 ± 2.0 17.1 ± 1.1 * (↓ 15 %)
Day 0

- 28 18.8 ± 1.5 19.3 ± 1.6 18.5 ± 1.6 17.1 ± 1.8 * (↓ 9 %) Day 28

- 35 19.4 ± 2.0 19.7 ± 1.4 17.8 ± 2.1 16.7 ± 0.8 * (↓ 14 %)
Day 35

- 42 19.4 ± 1.8 19.2 ± 1.5 19.0 ± 2.1 17.7 ± 3.5 * (↓ 9 %)
Day 42

- 49 20.8 ± 3.0 19.1 ± 2.0 20.3 ± 3.1 17.0 ± 3.1 * (↓ 18 %)
Day 49

- 56 18.4 ± 2.0 18.9 ± 1.7 17.5 ± 1.1 16.4 ± 1.8 * (↓ 11 %) Day 28

- 56 19.5 ± 1.9 19.2 ± 1.4 18.6 ± 1.6 16.9 ± 2.2* (↓ 13 %) Day 56

- 63 18.2 ± 1.7 19.0 ± 2.4 17.0 ± 1.2 16.9 ± 1.7 Day 63

- 70 19.0 ± 1.9 18.3 ± 1.2 17.0 ± 1.4* (↓ 11 %) 16.9 ± 3.2* (↓ 11 %) Day 70

- 77 18.8 ± 1.8 17.9 ± 0.8 17.5 ± 1.5 15.5 ± 0.9* (↓ 17 %)
Day 77

- 84 18.3 ± 1.7 18.9 ± 1.5 16.9 ± 1.1 16.8 ± 2.2* (↓ 8 %) Day 84

- 91 18.0 ± 1.7 17.0 ± 3.0 16.7 ± 1.5 15.5 ± 1.3* (↓ 14 %)Subchronic Neurot oxicity Study (rats) (201 1 ) /Page 12 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### TABLE 3

. Selected Mean ( ±SD) Food Consumption (g/animal/day) in Male and Female Rats

Exposure Time Concentration i n Diet (ppm)

0 5 0 0 1, 2 5 0 3, 7 5 0 /5,000

Day 56

- 91 18.5 ± 1.7 18.2 ± 1.6 17.0 ± 0.9* (↓ 8 %) 16.3 ± 1.7* (↓ 12 %)

Overall (Day 0

- 91) 18.9 ± 1.6 18.9 ± 1.4 18.1 ± 1.4 16.7 ± 1.9 * (↓ 12 %)

Values represent mean ± SD, n=12. The dietary concentration of 3,750 ppm was increased to 5,000 ppm on Week 9

. Percent difference from the control is included in parentheses and was calculated by the Investigators. * Significantly different from the control group, p ≤0.05. Statistically significant results are shown in bold.

Data were obtained from pages Tables 7 ( pages 43 -45) and 8 (pages 4 6- 48 ) of the study report.



### D. FOOD EFFICIENCY : There were no test substance

- related effects on food efficiency in

the 500, 1,250, or 3,750/5,000 ppm group males and females. The only significant differences from the control group were lower mean food efficiency in males ( ↓ 12%, p≤0.05 ) and females ( ↓28 %, p≤0.05 ) at the high concentration (3,750/5,000) groups on Day 0-7 (Table 4). Overall (0 -91) mean food efficiency was not statistically significant different from the control group in males or females at any dietary concentration level. No test substance

related effects on mean food efficiency were noted at 500 or 1,250 ppm in males or females.

TABLE 4

. Selected Mean ( ±SD) Daily Food Efficiency (g/g) in Male and Female Rats

Exposure Time Concentration i n Diet (ppm)

0 50 0 1, 2 5 0 3, 7 5 0 /5,000

Males Day 0

- 7 0.353 ± 0.038 0.346 ± 0.042 0.342 ± 0.035 0.310 ± 0.044 * (↓ 12 %) Day 0

- 91 0.136 ± 0.014 0.146 ± 0.021 0.138 ± 0.018 0.138 ± 0.023

Females Day 0

- 7 0.193 ± 0.048 0.185 ± 0.036 0.171 ± 0.066 0.140 ± 0.053 * (↓ 28 %)

Day 0

- 91 0.073 ± 0.014 0.074 ± 0.009 0.065 ± 0.007 0.064 ± 0.010 (↓ 13 %) NS

Food efficiency was reported as average weight gain/average food consumption

. Values represent mean ± SD, n=12. The dietary concentration of 3,750 ppm was increased to 5,000 ppm on Week 9

. Percent difference from the control is included in parentheses and was calculated by the Investigators. * Significantly different from the control group, p ≤0.05. Significant results are shown in bold.

Data were obtained from pages Tables 9 (pages 49

- 51 ) a nd 10 (pages 52 -54 ) of the study report.



### E. TEST SUBSTANCE INTAKE : The mean daily intake (mg/kg/day) of Chlorimuron E thyl over the entire study period is presented in Table 5.

TABLE 5 . Intake of Chlorimuron E thyl in Males and Females

Test Group Concentration in Diet (ppm) Mean daily intake (mg/kg bw/day)

Male Female

1 50 0 27±16 35±2.2

2 1, 2 5 0 71±4.4 90±6.2

3 3, 7 5 0 /5,000 220±49.9 259±37.8

Data were obtained fro m Table s 11 ( p. 55-56 ) and 12 (p. 5 7- 58 ) of the study report.



### F. NEUROBEHAVIORAL RESULTS:Subchronic Neurot oxicity Study (rats) (201 1 ) /Page 13 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### 1. FOB findings : No test substance- related effects on FOB (home cage, open field, removal from the home cage and handling ) parameters were noted at any dietary concentration level

for either sex. In addition, t here were no statistically significant differences between the control and the test substance-exposed groups at any time point or between any of the doses.

2. Motor activity : No test substance- related effects were observed on motor activity (duration of movements and number of movements) in either sex at any dietary concentration level of the test substance. In addition, there were no statistically significant differences between the control and the test substance-exposed groups at any time point. The comparison of th e single intervals with the control group during the assessment of the duration of movement resulted in some isolated significantly increased values (interval 4; at 3,750/5,000 ppm) during the pretest evaluation , or decreased values (interval 2; at 3,750/5,000 ppm) at Week 4

in males , and increased values (intervals 8 and 9; at 3,750/5,000 ppm) at Week 8 in females. On the other hand, during the assessment of the number of movements, some increased

individual interval values were observed during the pretest evaluation in males (interval 3; at 3,750/5,000 ppm) and at Week 8 in females (interval 9; at 3,750/5,000 ppm). These

deviations were considered to be incidental based on the isolated occurrence and the lack of a dose-response relationship. Interval motor activity was provided in Tables 17 to 20 on pages 74-77 of the study report.

TABLE 6

. Motor Activity in Male and Female Rats

Exposure Time Concentration i n Diet (ppm)

0 50 0 1, 2 5 0 3, 7 5 0 /5,000

Total Duration of Movements (sec)

Males

Baseline 968 ± 289 1057 ± 311 971 ± 208 1043 ± 269

Week 4 1745 ± 555 1684 ± 392 1612 ± 571 1686 ± 440

Week 8 1794 ± 483 1742 ± 474 1641 ± 488 1616 ± 407

Week13 1507 ± 464 1486 ± 410 1229 ± 363 1464 ± 305

Females

Baseline 1324 ± 426 1259 ± 429 1318 ± 524 1528 ± 700

Week 4 1730 ± 556 1715 ± 606 1791 ± 492 1766 ± 475

Week 8 1565 ± 453 1689 ± 499 1730 ± 560 1823 ± 444

Week13 1444 ± 353 1480 ± 409 1469 ± 458 1548 ± 378

Total Number of Move ments

Males

Baseline 451 ± 178 469 ± 130 451 ± 132 515 ± 152

Week 4 771 ± 280 734 ± 204 695 ± 263 764 ± 195

Week 8 866 ± 277 818 ± 217 748 ± 284 799 ± 204

Week13 779 ± 205 736 ± 179 681 ± 233 771 ± 185

Females

Baseline 668 ± 256 629 ± 176 652 ± 242 737 ± 244

Week 4 821 ± 239 789 ± 238 870 ± 208 840 ± 204

Week 8 799 ± 233 847 ± 225 900 ± 260 916 ± 201

Week13 821 ± 201 811 ± 221 841 ± 243 880 ± 216

Values represent mean ±SD, n=12. The dietary concentration of 3,750 ppm was increased to 5,000 ppm on Week 9

. No statistically s ignificant differen ces from the control group.

Data were obtained from Tables 17 to 20 on pages 74-77 of the study report

.



### 3. Rearing: Mean number of rearing movements was unaffected by the test diet consumption at 500, 1,250, or 3,750/5,000 ppm in males and females. There were no statistically significantSubchronic Neurot oxicity Study (rats) (201 1 ) /Page 14 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### differences between the control and the test substance -exposed groups (by sex) at the study Week 4, 8, and 13 evaluations.

4. Forelimb and Hindlimb Grip Strength : There were no test substance

- related effects on forelimb and hindlimb grip strength in eit her sex at any dietary test substance concentration level. The only significant (p≤0.05) difference from the control group was a higher mean forelimb grip strength in the 1,250 ppm (↑16%) group males at Week 8 (Table 7); however, this finding was considered incidental and not treatment related since there was no evidence

of a dose response relationship.

TABLE 7 . Mean ( ±SD) Forelimb Grip Strength (kg) for Male Rats

Exposure Time Concentration in Diet (ppm)

0 50 0 1, 2 5 0 3, 7 5 0 /5,000

Baseline (Pretest) 0.69 ± 0.12 0.70 ± 0.08 0.68 ± 0.13 0.72 ± 0.13

Week 4 1.23 ± 0.26 1.17 ± 0.24 1.23 ± 0.19 1.20 ± 0.17

Week 8 1.32 ± 0.35 1.26 ± 0.27 1.53 ± 0.34* ( ↑16 %) 1.41 ± 0.30

Week 13 1.25 ± 0.25 1.14 ± 0.22 1.20 ± 0.15 1.16 ± 0.31

Values represent mean ±SD, n=12. Percent difference from the control is included in parentheses and was calculated by the Reviewers. * Significantly different from the control group, p ≤0.05. Statistically significant results are shown in bold.

Data were obtained from Table 1 3 on page 59 of the study report.



### 5. Foot Splay: No treatment

- related effects on f oot splay occurred at any dietary concentration

level of the test substance in males and females. There were no statistically significant

differences between the control and test substance

- treated groups.

6. Body Temperature : Body temperature was unaffected by the administration of test

substance at 5 00, 1,25 0, or 3,750/5,000 ppm in males and females. There were no statistically significant differences between the control and test substance

- treated groups

G. SACRIFICE AND PATHOLOGY :

1. Gross Pathology : No adverse, treatment -related effects were noted during gross pathology.

2. Neuropathology : No adverse, treatment

- related histologic al changes were noted in the high

concentration (3,750/5,000 ppm) group males or females compared to controls.Subchronic Neurot oxicity Study (rats) (201 1 ) /Page 15 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### III. DISCUSSION AND CONCLUSIONS:

A. INVESTIGATORS’ CONCLUSIONS :

The investigator concluded that under the conditions of this study, the no- observed

- adverse

effect level (NOAEL) for systemic toxicity was 3 ,750/5,000 ppm (220 mg/kg/day), the highest concentration, for male rats and 500 ppm (35 mg/kg/day) for female rats. The female NOAEL was based on decreased body weight and nutritional parameters in females

administered 1 ,250 and 3,750/5,000 ppm. The NOAEL for neurotoxicity in males and females was greater than 3 ,750/5,000 ppm (220 and 259 mg/kg/day, respectively), the highest dietary concentration tested, based on the absence of test substance

- related effects on the nervous system.

B. REVIEWER COMMENTS :

Exposure of Crl:CD(SD) male and female rats to Chlorimuron E thyl at dietary concentration

levels of 500, 1,250 or 3,750/5,000 ppm resulted in no effect on mortality or clinical signs in

either male or female rats

.

No test substance- related effects were observed on FOB (home cage, open field, remov al from the home cage and handling) parameters, rearing, hindlimb grip strength, body temperature or motor activity (duration of movements and number of movements) at any dietary concentration level in either sex. Higher (p≤0.05) mean forelimb grip streng th was noted in the 1,250 ppm (↑16%) group males at Week 8; however, this finding was considered

incidental with no dose or time relationships that would indicate that this finding was related to treatment, nor were there similar trends in both males and f emales.

Treatment -related effects on body weights, body weight gains and food consumption were evident in the high dietary concentration (3,750/5,000 ppm) group females, but not in males. In females, mean body weight was significantly reduced by 6- 10% fr om Day 21 though Day 91. No significant differences in body weights were noted in females at dietary concentration levels of 500 or 1,250 ppm compared to the controls, except on Day 84, lower (p≤0.05) body weight was noted in the 1,250 ppm (↓7%) group females. However, the decrease was not

considered adverse since the reduction was less than 10%. Mean body weight gain was lower (p≤0.05) during test Day 0

- 7 (↓34%), Day 14

- 21 (↓40%) and Day 0

- 28 (↓21%) in the 3,750/5,000 ppm group females when compared to the control group. Overall (0 -91) body weight gains were significantly reduced by ↓15% and ↓24% at concentrations of 1,250 and 3,750/5,000 ppm in females, respectively. Lower ( p≤0.05) mean daily food consumption ranged ↓9

- 18% from Day 14 -21 though the end of the treatment in the 3,750/5,000 ppm group females . In addition, mean daily food consumption was significantly decreased by 11% and 8% on Day 63-70 and Day 56- 91, respectively, at the concentration of 1,250 ppm. However, in the absence of a treatment related effect on absolute b odyweight, the reductions in bodyweight gain and food consumption were not considered adverse at 1,250 ppm. Overall (0 -91) mean food consumption was lower (p≤0.05) in the 3,750/5,000 ppm group
females. In contrast to females, there were no treatment

- relat ed or statistically significant effects on body weight, body weight gain or food consumption in males at any dietary

concentration level. There were no test substance -related effects on food efficiency in the 500, 1,250, or 3,750/5,000 ppm group males or f emales. It wa s concluded that lower body weight gains observed in the high concentration (3,750/5,000 ppm) group females, but not inSubchronic Neurot oxicity Study (rats) (201 1 ) /Page 16 of 16 Chlorimuron Ethyl / 128901 OPPTS 870.6200 b/ MAFF 12 Nousan 8147/ OECD 424



### males, were associated with the significant reduction in body weights and food consumption over the entire study period and were test substance

- related. Overall, females were more

sensitive than males.

No test substance-related alterations were observed in gross histopathology observations or microscopic neurohistopathology in the 3,750/5,000 ppm group male s and female s.

It is concluded that Chlorimuron E thyl did not exhibit neurotoxic effects on Crl:CD(SD)

male and female rats at dietary concentration levels of 500, 1,250 and 3,750/5,000 ppm, based on the lack of altered behavior in the FOB parameters, no significant effe cts in motor activity (duration of movements and number of movements), and no effects on the macroscopic and microscopic pathology of nervous system tissues. However, systemic toxicity was observed in females at 3,750/5,000 ppm. This was characterized by decreased body weight s and body weight gains and significant reductions in food consumption over the study period.

The systemic NOAEL is 1,250 ppm (equivalent to 71/90 mg/kg/day), based on decreased body weight and body weight gains and reduced food consumption observed in females

at the LOAEL of 3,750/5,000 ppm (equivalent to 220/259 mg/kg/day, M/F respectively ).

The NOAEL for neurotoxicity is the highest dose tested 3,750/5,000 ppm (equivalent to 220/259 mg/kg/day, M/F respectively) since no treatment related neurotoxic effects were seen in the study.

This study is classified as acceptable/guideline and satisfies the guideline requirement ( OPPTS 870.6200b ; OECD 424 ) for a sub chronic neurotoxicity study in rats.

C. STUDY DEFICIENCIES :

In the study report, the highest dietary concentration was primarily reported as 3,500/5,000 ppm (e.g. see Summary section; page 12 and Conclusion section; page 26), however the Study Design table on page 14 indicates that the high dietary concentration of Chlorimuron Ethyl was 3,750/5,000 ppm. Also, all summary and individu al Tables as well as Appendix B indicate the high dose was 3,750/5,000 ppm. Except the aforementioned problem, there were no other deficiencies reported in this study.

### DATA EVALUATION RECORD Chlorimuron Ethyl

PC Code: 128901

TXR#: 0056215

MRID#: 48704302

Study Type: A cute Neurotoxicity [feeding]

- 14- Day Study in 

### Crl:CD(SD) rats

OPPTS 870.7800

Prepared for

Health Effects Division Office of Pesticide Programs U.S. Environmental Protection Agency

One Potomac Yard 2777 S. Crystal Drive Arlington, VA 22202

Prepared by

Tetrahedron Incorporated 1414 Key Highway, Suite B Baltimore, MD 21230

Principal Reviewer: _____________________________________ Date:

5/16/2012 Henry Spencer, Ph.D.

Secondary Reviewer: _____________________________________ Date:

5/25/2012 William Burnam, M.S.

Quality Assurance:

_________________________________________ Date:

5/28/2012 Nasrin Begum, Ph.D.

Contract Number: EP -W-10013 Work Assignment No.: WA -0-01

Task Number: 1-1-88

EPA Reviewer//WAM: Swartz and Levy//Farwell and Brunsman

Disclaimer

This review may have been altered by the EPA subsequent to the contractors’ signature

above.

### Chlorimuron Ethyl/12890 I



### TXR#: 0056215 Acute Neurotoxi c it y St ud y (ra t s ) ( 2 0 I I ) I Pa ge 2 o f I 4

OPPTS 8 70. 620 0a/ DA C 4.5.12 / OECD 424



### DATA EVALUATION RECORD

STUDY TYPE: Acute Neurotoxicity

- Rats OPPTS 870.6200a [§81-8]; OECD 424.

PC CODE: 128901 DP BARCODE: D397470

TEST MATERIAL (PURITY) : Chlorimuron Ethy l (chlorimuron ethyl) 97

. 5% a.i.

SYNONYMS: DPX-F6025

, IPAC Name: Ethy l 2-(-4-ch loro-6-m ethoxypyrimidin-2- ylcarbamoy l sulfamoy l) benzoate; CAS Name: Ethy l 2 -[[ [[(4 -chl oro

- 6-methoxy2-pryrimidinyl)am ino ]carbonyl]amino] su lfon yl]benzoate

CITATION: Author: Carpenter

, C. (20 11)

, Title: Chlorimuron Ethyl (DPX

- F6025) Technical:

Acute Oral Neurotoxicity Study in rats

. Laboratory: DuPont Haskell Global

Centers for Health & 

### Environmental Sciences P.O. Box 50, Newark, Delaware
19714, U.S.A., Laboratory report number: DuPont- 31865

, December 12

, 2011.

MRID48704 302. Unpublished.

SPONSOR: E.I du Pont de Nemours and Company, Wilmington, Delaware, 19898.

EXECUTIVE SUMMARY:

In an acute neurotoxicity study (MRID 48704302)

, groups Crl:CD (SD) rats (12 / sex / dose) were given a sing l e ora l dose of chlorimuron ethy l (97.5% a.i, DPX F6025-258) in 0.5% methylcellulose at doses of I 00, 500, or 2000 mg / kg bw and observed for 14 days.

Neurobehaviora l assessment (functiona l observationa l battery and motor activity testing) was performed on all animals at

- 7 days (pretest)

, 0 (approxima t e l y 2 hours after dosing)

, 7, and 14 days

. At study termination, 6 animals / sex in the control and high dose groups were euthani z ed

and perfused 

### in situ for histopathological eva lu ation of brain and peripheral nervous system

tissues.

Treatment related clinical signs were absent in the animals. There were no effects on mortality

, histopathology, or neuropathology.

No significant body weight changes were seen in male and female gro u ps when compared to
controls. Body weight gains were significantly reduced by 111.4 % (p < 0.05) in ma l es on day 0-1

at 2000 mg/kg bw

, but these effects were not seen at l ater time intervals. Reductions in bod y weight gain in males at other dose levels were not significant, though there were questionable

reductions at 500 mg/kg bw on Days 0-1.

In fema l e s, there was a significant decrease in body weight gain for the time period of 0- 7 days

,Acute Neurotoxicity Study (rats) ( 2011) / Page 3 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424



### but this significance was not seen for the 9-14 day period. FOB findings on motor activity

indicated that male s at 2000 mg/kg bw preferred a curled up posture. Arousal was also reduced

at 500 and 2000 mg/kg bw in males and females on Day 0. Palpebral closure was noted in a few

females at 2000 mg/kg bw on day 0. No treatment

- related effects were seen in the 100 mg/kg bw group.

Motor activity on Day 0 was affected in a few early sessions by statistically significant reductions in activity in males at 500 and 2000 mg/kg bw. Sessions at 100 mg/kg bw showed changes, but only the #2 session at 1 00 mg/kg bw was statistically significantly different from

the control. Sessions in females from # 2-#6 at 500 mg/kg bw were reduced but the changes were not statistically significant

.

The NOAEL is 100 mg/kg/day, based on reduced arousal and reduced motor activity in male and

female rats at the LOAEL of 500 mg/kg bw.

This neurotoxicity study is classified as acceptable/guideline) and satisf ies the guideline requirement for an acute neurotoxicity study in rats (870.6200a; OECD 424).

COMPLIANCE : Signed and dated GLP, Quality Assurance, and Data Confidentiality statements were provided.Acute Neurotoxicity Study (rats) ( 2011) / Page 4 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424



### I

. MATERIALS AND METHODS :

A. MATERIALS :

1. Test m aterial : Chlorimuron Ethyl (DPX

- F6025) Technical Description: Crystalline, powder, white

Lot/b atch #: DPX

- F6025

- 258 (Laboratory designation); Analysis No.:MAR09MA047 Purity: 97.5 % a.i.

CAS # of TGAI: 90982

- 32

- 4

Structure:

2. Vehicle and/or positive control : T he vehicle was 0.5% methylcellulose.

3. Test animals : Species: Rat

Strain: Crl:CD(SD)
Age/weight at dosing: 49 days, 200.5

- 256.6g males, 143.6

- 201.9 g

females.

Source: Charles River Labs. Inc., Kingston, New York Housing: One sex, in pairs in solid bottom caging

Diet: PMI Nutrition International, LLC Certified Rodent LabDiet ® 5002 ad

libitum.

Water: Tap water was provided ad libitum.

Environmental

conditions: Temperature: Humidity: Air changes: Photoperiod: 18

- 26°C

30-70% Thenumber of changes of air/ hour was not reported. 12 hrs dark/12hrs light
Acclimation period: Quarantined 8 day, acclimated for additional 7 days



### B. STUDY DESIGN :

1. In life dates : Start: May 17, 2011; End: June 3, 2011

2. Animal assignment and treatment : Animals were assigned to the test groups noted in Table 1 by a computerized , stratified, random ization program so that body weight means for each group were comparable within a sex. R ats on Day 0 were given a single dose of chlorimuron ethyl in 0.5% methylcellulose by oral

- gavage at 10 mL/kg bw based on the body weight taken just before dosing. Controls received only the 0.5% methylcellulose solution.

The study animals were then observed 2X daily for daily health observations and were weighed on Day 0, 1, 7, and 14 for 14 days. Dose levels were chosen based on a recent acute oral toxicity study using 175, 550, 1750 or 5000mg/kg bw chlorimuron ethyl in distilled

water. No significant clinical signs of toxicity were reported. There was no determination of a time to peak effect reported previously. The 2000 mg/kg bw dose was included in the present study with the 100 and 500 mg/kg bw doses as a limit range. Administration was staggered over a 2-day interval to facilitate neurobehavioral observations. Males and females

were treated on the same days in 4 replicates in the 2-day period. Survivors were sacrificed and a necropsy was performed.Acute Neurotoxicity Study (rats) ( 2011) / Page 5 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424

TABLE 1.Study design

Experimental parameter Dose group (mg/kg bw) 0 mg/kg

bw 100 mg/kg

bw 500 mg/kg

bw 2000 mg/kg

bw

Total number of a nimals/sex/group 12/sex 12/sex 12/sex 12/sex

Behavioral t esting [F OB, ( Motor Activity (9)10 min

sessions ) Days 0, 7, 14 ] 12 /sex 12 /sex 12 /sex 12 /sex

Neuropathology 6/sex 6/sex 6/sex 6/sex
Body weights, weight gains, and food consumption on Days 0, 1, 7, 14 12/ sex 12 /sex 12 /sex 12 /sex



### 3. T est Substance p reparation and a nalysis : The test substance was supplied as a white solid.

It was used in the established period of stability of 5 days at ambient temperature. A weighed portion of the white powder corrected for purity was suspended in 0.5% methyl

cellulose. Exact methods of formulation were not provided. The homogeneity was determined for each formulation by sampling a portion at levels designated as top, middle,

and bottom for test material concentration. Homogeneity was evaluated by calculating the

relative standard deviation (RSD) of the measured concentration of each level.

Concentrations of the test substance in the sample analyses for each respective dose level

were determined. Stability was determined by comparing the values found at February 17, 2011 and comparing them to the values found after a resuspension following storage for 5 days at ambient temperature.

Results :

Homogeneity analysis: RSD range 2%- 5% comparing initial and 5 days storage

.

Stability analysis: 99.9%-94.2% at 10 mg/mL; and 95%-90.5% at 200 mg/mL in initial and 5 day storage, respectively.

Concentration analysis: Percent of nominal: 10mg/mL 99.9% RSD =3 %; 200 mg/mL 95%

RSD=3%. At initial formulation , t he analytical data indicated that the mixing procedure was adequate and that the variance between nominal and actual dosage to the animals wa s acceptable.

4. Statistics : Statistical analyses noted that m ales and females were analyzed s eparately and that significance was set at p<0.05.

Table 2 .Parameters and statistical tests used

Method of Statistical Analysis

Parameter Preliminary Test If preliminary test is not significant If preliminary test is significant

Body Weight Body Weight Gain Food Consumption Food Efficiency Levine’s test for homogeneity and Shapiro

- Wilk test for normality One

- way analysis of

variance follo w ed by Dunnett’s test Transforms of the data to achieve normality and variance homogeneity were used.The order of transforms attempted was log, square

- root, and

rank

- order.If the log and square

- roottransforms failed, the rank

- order was used. Grip Strength Foot Splay Body Tempe rature Rearing Levine’s test for homogeneity and Shapiro

- Wilk test for normality Repeated measures

and ana lysis of

variance followed by linear contrasts (1) A normalizing variance stabilizing transformation followed by repeated measures analysis of variance or (2) sequential application

of Jonckheere

- Terpstra b trend test.Acute Neurotoxicity Study (rats) ( 2011) / Page 6 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424

Motor Activit y a

Incidence of FOB Descriptive

Parameters None Cochran

- Armitage test for trend.If the incidence is not significant, but a significant lack of fit occurs, the Fisher’s Exact test with a Bonferroni

Holm correction is used.

a - Test day and 10

- minute interval were used as repeated measure factors.

b - If there w as a significant lack of monotonicity (i.e. Linear Trend:Dose was not significant , and Quadratic Trend:

Dose was significant), Dunn’s test was used instead of Jonckheere

- Terpstra.



### For each parameter analyzed with a trend test, the test was applied to the data sequentially. If a significant dose response was detected, data from the top dose group was excluded and the test repeated until no significant trend is detected. The analyses used were appropriate.

C. METHODS / OBSERVATIONS :

1. Mortality and c linical observations : Animals were observed 2X daily for mortality and morbidity. Detailed clinical o bservations were recorded at least once daily except on the day

of a neurobehavioral evaluation. Times in the day when each evaluation or observations

we re made were not provided.

2. Body weight : Animals were weighed during the baseline FOB and on test day 0, and on Days 1, 7, and 14.

3. Food consumption : Each animal ‘s food consumption was determined on Days 0, 1, 7, and

14. The feeders were weighed prior to adding new material and again weighed after the consumption period.

4. Cholinesterase determination : Cholinesterase activity was not determined in this study.

5. Neurobehavioral a ssessment :

a. Functional Observational Battery (FOB ): Open

- field behavioral observations included sharp auditory stimulus evaluation following the use of a clicker. Additional ly, pain reception was evaluated by a tail pinch. Grip strengths were measured using a Chatillon ® Digital Force gauge. Rectal body temperatures were recorded with a YSI PrecisionTM 4000 thermometer and temperature probe. The landing foot splay was determined using

measurements of fresh ink impression s made by the heels of the hind paws when the animals were dropped from about a 32 cm height. The animals were examined as a blind effort usingthe same investigators throughout the study. The studies were carried out in a soundattenuated room with white -noise- generation to minimize environmental test conditions.

Exact time of the day the evaluations were conducted after exposure was not provided. Table 3.shows the parameters evaluated in the FOB.

Table 3. The CHECKED (X) parameters were examined.

X HOME CAGE OBSERVATIONS X HANDLING OBSERVATIONS X OPEN FIELD OBSERVATIONS

X Posture* Reactivity* X Mobility Biting X Lacrimation*/ chromodacryorrhea X Rearing+

X Convulsions* X Salivation* X Arousal/ ge n eral activity level*Acute Neurotoxicity Study (rats) ( 2011) / Page 7 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424

X HOME CAGE OBSERVATIONS X HANDLING OBSERVATIONS X OPEN FIELD OBSERVATIONS

X Tremors* X Piloerection* X Convulsions*

X Abnormal Movements* X Fur appearance X Tremors*

X Palpebral closure* X Palpebral closure* X

X Abnormal m ovements* spasms/ fasciculations Feces consistency Respiratory rate+ X Urination / defecation*

X coordination Red/crusty deposits* Grooming

SENSORY OBSERVATIONS X Mucous membranes /eye /skin

color X Gait abnormalities / posture*

X Approach response+ X Eye prominence* X Gait score*

X Vocalization X Righting reflex

X Dehydration X Ease and rate of respiration

X Emaciation X vocalization

X Touch response+ X Muscle tone* Bizarre / stereotypic behaviour*

X Startle response* X Ease of removal / handling Backing

X Pain response* PHYSIOLOGICAL

OBSERVATIONS Time to first step

X Pupil response* X Body weight* X Palpebral closure
Eyeblink response X Body temperature+ NEUROMUSCULAR

OBSERVATIONS

Forelimb extension Hindlimb extensor strength

Hindlimb extension OTHER OBSERVATIONS X Forelimb grip strength*

X Air righting reflex+ X Hindlimb grip strength* Olfactory orientation X Landing foot splay* Rotarod performance

*R equired parameters; +Recommend e d parameters



### b. Locomotor a ctivity : Locomotor Activity was evaluated on individuals in one of thirty identical, automated infrared beam activity monitors (Moulbourn® Instruments). Measurements were of duration of movement and number of movements per animal in a series of 9, 10 minute consecutive intervals. There were 12 animals/sex/dose in this

evaluation. Scoring criteria were not provided for the measured parameters. However,

“co unts” appeared to be of duration in seconds (total activity) and the number of counts representing the numbers of any type of movement.

6. Sacrifice and pathology : On day 16, 6 rats/sex/dose were anesthetized by an i.p. dose of a

mixture of ketamine/ xylazine and who le -body perfused in situ.The perfusion solution was not described. The remaining animals not chosen for histological evaluation were terminated with isoflurane anesthesia and asphyxiated by carbon dioxide. Necropsy was not performed

on the remaining animals. The perfused animals in each group were eviscerated and necropsy samples taken prior to emersion fixation for further processing of the appropriate tissues.

Paraffin embedded, which were sectioned at about 5 μm and stained with hematoxylin and eosin tissues included: the brain (cerebrum and hippocampus, forebrain, midbrain, cerebellum, pons, and medulla) spinal cord (cervical, thoracic, and lumbar), eye with optic nerve, and gastrocnemius muscle. Tissues that were embedded in gl ycol methacrylate (GMA), sectioned at about 3 μm and stained with hematoxylin and eosin included: cervical and lumbar dorsal root fibers and ganglia, and ventral root fibers, sciatic, tibial and sural nerves and gasserian ganglia. Only the tissues from the high dose and control animals were processed and evaluated as reported in Table 4.Acute Neurotoxicity Study (rats) ( 2011) / Page 8 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424



### Table 4. The CHECKED (X) tissues were evaluated.

X CENTRAL NERVOUS SYSTEM X PERIPHERAL NERVOUS SYSTEM

BRAIN SCIATIC NERVE

X Forebrain

X Center of cerebrum X Sciatic Notch

X Midbrain

X Cerebellum OTHER

X Pons X Sural Nerve

X Medulla oblongata X Tibial Nerve

SPINAL CORD

X Cervical swelling X Lumbar dorsal root ganglion

X Lumbar swelling X Lumbar dorsal root fibers

X Thoracic swelling X Lumbar ventral root fibers

OTHER X Cervical dorsal root ganglion

X Gasserian Ganglion X Cervical dorsal root fibers

X Optic nerve X Cervical ventral root fibers

X Eyes

X Gastrocnemius muscle



### 7. Positive controls : It was stated in this report that three separate reports (MRID 44628703, MRID 47053501 and MRID 48710304, performed in 1997, 2002 and 2011, respectively) were previously performed by DuPont Haskell to generate positive control data and validate the procedures and the inter

- observer reliability of the per forming lab to conduct and assess neurobehavioral and neuropathology tests. The data also documents that the equipment and procedures are capable of detecting effects that may be seen in neurotoxicity studies. The positive control data is acceptable for use with the current study. Historical control data were not provided in the report.

II. RESULTS :

A. OBSERVATIONS :

1. Clinical signs : There were no c linical signs considered to be treatment related in either sex

.

2. Mortality: All animals survived to termination

.

B. BODY WEIGHT AND BODY WEIGHT GAIN : The body weight of the male and female groups d id not show significant changes when compared to control. There did not appear to be much variability between groups. The body weight gains however, do show significant reduction (-111.4%) in gains in males at 2000 mg/kg bw in the day 0-1 interval. Control

f

emales also exhibited poor weight gains between Day 0 -1 (- 0.5 g) . The body weight gains in the test groups were greater with a gain of 3.3 g seen at 500 mg/kg bw , and 2.9 g at 2000 mg/kg bw. There was some significance at the female high dose for body weight gain for days 0 -7, but the significance was gone at day 14. The 500 mg/kg bw females showed lower weight gains than the 100 mg/kg bw group on Day 0-1.Acute Neurotoxicity Study (rats) ( 2011) / Page 9 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424

T ABLE 5 .Body weight and body weight gain (g)

Observation (g ± s.d.) Dose level (mg/kg bw) N=12 0 mg/kg bw 100 mg/kg bw 500 mg/kg bw 2000 mg/kg bw

Body weight

- males

- Day 0 238.2 ± 14.2

Diff

. - 236.1 ± 13.2

Diff.

- 0.9 % 232.3 ± 15.1

Diff.

- 2.5 % 237.9 ± 13.9

Diff.

- 0.1 % Day 1 243 ± 12.7

Diff.

- 241.4 ± 12.6

Diff.

- 0.7% 238.2 ± 15.9

Diff.

- 2% 237.3 ± 12.0

Diff.

- 2.3% Day 7 300.9 ± 21.1

Diff.

- 297.5 ± 12.2

Diff.

- 1.1% 294.8 ± 19.5

Diff.

- 2% 294.5 ± 18.9

Dif.

- 2.1% Day 14 360.6 ± 26.7

Diff.

- 355.7 ± 12.0

Diff.

- 1% 355.5 ± 23.9

Diff.

- 1% 356.7 ± 24/9

Diff.

- 1% Body weight

- females

- Day 0 180.7 ± 11.5

Diff.

- 178 ± 14.2

Diff.

- 1.5% 177.8 ± 16.1

Diff.

- 1.6% 178.9 ± 10.3

Diff.

- 1% Day 1 180.1 ± 11.7

Diff.

- 181.8 ± 14.3

Diff.

- 0.9% 181.2 ± 14.8

Diff.

- 0.6% 181.9 ± 10.3

Diff.

- 1% Day 7 209.8 ± 11.6

Diff.

- 203.2 ± 18.6

Diff.

- 3.1% 207.9 ± 17.1

Diff.

- 0.9% 201.4 ± 12.6

Diff.

- 4% Day 14 235.1 ± 12.2

Diff.

- 228.6 ± 21.4

Diff.

- 2.8% 231.8 ± 18.8

Diff.

- 1.4% 229.2 ± 14.3

Diff.

- 2.5%
Body weight gain

- males

- Day 0

- 1 4.8 ± 2.9

Diff.

- 5.3 ± 4.0

Diff.10.5% 5.9 ± 10.1

Diff. 22.5% - 0.6 ± 6.2 #

Diff.

- 111.4%
Day 0

- 7 62.7 ± 7.9

Diff.

- 61.4 ± 3.1

Diff.

- 2% 62.5 ± 16.3

Diff.

- 0.3% 56.6 ± 8.7

Diff.

- 9.7% Day 7

- 14 59.8 ± 8.8

Diff.

- 58.3 ± 6.3

Diff.

- 2.5% 60.7 ± 6.7

Diff. 1.6% 62.2 ± 8.6

Diff. 4% Day 0

- 14 122.5 ± 14.4

Diff.

- 119.7 ± 6.7

Diff.

- 2.3% 123.2 ± 22.1

Diff. 0.6% 118.8 ± 16.8

Diff.

- 3% Body weight gain

- females

- Day 0

- 1

- 0.5 ± 3.5

Diff.

- 3.9 ± 5.5

Diff

- 838.1% 3.3 ± 5.7

Diff.

- 733.3% 2.9 ± 3.0

Diff.

- 657.1%
Day 0

- 7 29.1 ± 4.6

Diff.

- 25.2 ± 6.6

Diff.

- 13.4% 30.1 ± 5.5

Diff. 3.4% 22.5 ± 8.0 #

Diff.

- 22.8%
Day 7

- 14 25.3 ± 5.5

Diff.

- 25.4 ± 9.5

Diff. 0.3% 23.9 ± 7.4

Diff.

- 5.6% 27.8 ± 6.3

Diff. 9.7%
Day 0

- 14 54.4 ± 5.8

Diff.

- 50.6 ± 11.6

Diff.

- 7% 54 ± 10.8

Diff.

- 0.8% 50.3 ± 9.2

Diff.

- 7.7%

# p<0.05

. Data extracted from pages 32 and 33 of the study report.



### C. FOOD CONSUMPTION : Significant reductions in food consumption w ere observed at Day 0 -1 in both sexes (Males, -9.6% (NS ) and females, -20.8% (p<0.05) at 2000 mg/kg bw.

TABLE 6 .Food consumption (g/kg/day)

Days No. Dose level (mg/kg bw) n=12 0 mg/kg bw 100 mg/kg bw 500 mg/kg bw 2000 mg/kg bw

Males Days 0

- 1 23.0 ± 4.2

Diff.

- 26.0 ± 1.4

Diff.13.2% 25.3 ± 3.0

Diff. 10.3% 20.8 ± 4.1

Diff.

- 9.6% Days 0

- 7 27.4 ± 1.7

Diff.

- 26.9 ± 0.7

Diff.

- 1.9% 27.4 ± 1.6

Diff. 0.1% 27.7 ± 1.8

Diff. 1%

Females Days 0

- 1 17.2 ± 1.4

Diff.

- 19.3 ± 2.3

Diff. 12.4% 18.4 ± 2.6

Diff. 7.3% 13.6 ± 3.5 #

Diff.

- 20.8%
Days 0

- 7 19.4 ± 0.7

Diff.

- 18.6 ± 0.9

Diff.

- 3.9% 19.6 ± 1.4

Diff. 1.2% 18.4 ± 0.7

Diff.

- 4.9%

Data were extracted from pages 35, 36 of the study report. Values represent mean + s.d.Acute Neurotoxicity Study (rats) ( 2011) / Page 10 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424

n=12/ group
# p<.05, when compared to control means

Diff. = difference of group compared to control group.



### D. CHOLINESTERASE ACTIVITIES : Cholinesterase activity was not measured in this study.

E. NEUROBEHAVIORAL RESULTS :

1. FOB f indings : FOB results noted in Table 7 showed males in the 2000 mg/kg bw group preferred a c urled -up posture (4/12 treated vs. 0/12 control) on Day 0. T hey were also more difficult to arouse in the 500 and 2000 mg/kg bw groups (3/12 and 3/12 respectively, vs. 0/12 controls) (p<0.05). The posture of females at 500 and 2000 mg/kg bw was only slightly affected (2/12, 2/12 respectively vs.0/12 controls) (N.S). Palpebral closure occurred in 2/12

animals on Days 0 and 14 (p<0.05).

TABLE 7. Functional observation battery results

Observation Dose level (mg/kg bw) n=12 0 mg/kg bw 100 mg/kg bw 500 mg/kg bw 2000 mg/kg bw

Males
Posture: curled up

- Pretest

- Day 0

- Day 7

- Day 14 1

0

0

0 1

0

2

0 0

1

0

0 1

4 #

3

0

Arousal

- low

- Pretest

- Day 0

- Day 7

- Day 14 0

0

0

0 0

2

3

1 1

3#

1

1 1

3#

1

1

Females Home cage curled up

- Pretest

- Day 0

- Day 7

- Day 14 0

1

0

0 0

0

0

0 1

2

0

0 1

2

1

2# Home cage Palpebral closure Appears to be sleeping

- Pretest

- Day 0

- Day 7

- Day 14 0

0

0

0 0

0

0

0 1

0

0

0 0

2#

1

2#

Data were extracted from pages 43, 47, 50 Values represent incidence

n=12

# =p<.05 compared with controls



### Additionally, both male and female rats at 2000 mg/kg bw on Day 0 exhibited reduced activity in the number of rearing incidences. The reduction in f emales (4/7 treated vs. controls) was statistically significant while the males were lower (2/5) , but not statistically significant. Body temperatures on Day 0 at 2000 mg/kg bw were significantly lower than controls by 1 and 1.2 degrees i n males and females

, respectively. Females also exhibited slightly lower body temperatures at 500 mg/kg bw.

2. Motor activity : The total activity counts in Table 8 for the sum of 9, 10 minute sessions suggests that on Day 0, males at 500 and 2000 mg/kg bw were more subdued than controlsAcute Neurotoxicity Study (rats) ( 2011) / Page 11 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424



### and animals at 100 mg/kg bw. The reduced activity numbers were not statistically significantly different from controls. However, t here were several 10 minute sessions in

males and females at the 500 and 2000 mg/kg bw dose levels that measured a decrease in activity at Day 0 as indicated by the mean number of movements per session (Tables, 9, 10). In males on Day 0, Session # 2 showed statistically significant reductions in activity in all test groups. Session #3 showed statistically significant reductions in the 500 and 2000 mg/kg bw groups. Sessions # 4 and #5 were not statistically significant and appeared to plateau at lower activity levels –not unlike controls.

F emale rat s at 2000 mg/kg bw showed significantly reduced movements in sessions # 1, #2,

#3. However , at 500 mg/kg bw, sessions #2, #3, #4, #5, #6 showed lower activity than controls, but were not statistically significantly different.

The statistically significant reduced effect at 2000 mg/kg bw in females is in 1 -3 sessions (30 minutes), but sessions #4, #5 also show effects lower than controls. A statistically significant effect at 500 mg/kg bw did not occur, but sessions #1 - #6 show effects lowered compared to

control. The duration in seconds/s ession were also statistically significantly decreased in

sessions #2 -#3 and #2-#4 in males on Day 0 at 500 and 2000 mg/kg bw respectively. The females at 500 and 2000 exhibited statistically significant reduction of counts in sessions #1- #4. Changes in ac tivity at 100 mg/kg bw were similar to controls.

TABLE 8 .Motor activity (total activity counts for 90 minute session)

Test day Dose level (mg/kg bw) n=12

0 mg/kg bw 100 mg/kg bw 500 mg/kg bw 2000 mg/kg bw

Males

Pre

- test 536 ± 164 468 ± 163 532 ± 165 575 ± 240

Day 0 402 ± 107 365 ± 84 317 ± 91 319 ± 161

Day 7 496 ± 246 539 ± 213 456 ± 142 534 ± 267

Day 14 583 ± 154 568 ± 246 497 ± 127 577 ± 257

Females

Pre

- test 610 ± 237 693 ± 207 759 ± 294 718 ± 296

Day 0 412 ± 167 487 ± 243 339 ± 100 242 ± 122

Day 7 639 ± 259 704 ± 295 670 ± 242 620 ± 238

Day 14 611 ± 227 648 ± 220 632 ± 223 731 ± 218

Data were extracted from pages 58,59 Values represent mean + s.d.

n= 12



### Table 9. Day 0 mean number of movements per session in Male Rats n=12

Session @10 min 0 mg/kg bw 100 mg/kg bw 500 mg/kg bw 2000 mg/kg bw

#1 126 ± 22 126 ± 16 113 ± 22 113 ± 40

#2 123 ± 27 91 ± 45# 48 ± 41# 31 ± 36#

#3 56 ± 45 40 ± 43 16 ± 20# 18 ± 19#

#4 17 ± 15 13 ± 9 39 ± 37 16 ± 18

#5 28 ± 37 29 ± 42 19 ± 13 33 ± 37

#6 9 ± 7 21 ± 25 26 ± 21 23 ± 17

#7 14 ± 18 24 ± 34 28 ± 26 21 ± 19

#8 18 ± 32 12 ± 8 13 ± 11 32 ± 29

#9 10 ± 12 10 ± 8 16 ± 18 31 ± 26# Data extracted from Page 58 of the study report.Acute Neurotoxicity Study (rats) ( 2011) / Page 12 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424

#=p<.05 compared with controls



### Table 10. Day 0 mean number of movements per session in Female Rats n=12

Session @ 10 min 0 mg/kg bw 100 mg/kg bw 500 mg/kg bw 2000 mg/kg bw

#1 129 ± 18 134 ± 16 131 ± 21 103 ± 34#

#2 72 ± 47 101 ± 55 42 ± 31 30 ± 24#

#3 55 ± 54 59 ± 55 15 ± 15 11 ± 13#

#4 47 ± 51 42 ± 55 18 ± 26 17 ± 21

#5 44 ± 52 26 ± 41 19 ± 27 14 ± 12

#6 36 ± 44 27 ± 26 10 ± 11 27 ± 25

#7 6 ± 7 26 ± 44 33 ± 41 18 ± 23

#8 13 ± 18 35 ± 43 47 ± 45 9 ± 10

#9 10 ± 8 35 ± 47 24 ± 28 12 ± 18 Data extracted from Page 59 of the study report.

# = p<0.05



### F. SACRIFICE AND PATHOLOGY :

1. Gross pathology : There were no treatment

– related gross pathological lesions observed. An eye lesion was seen in 1 female at 2000 mg/kg bw. The lesion (which was graded minimal) is considered a normal finding resulting from the folding of the retina; it was

not considered to be treatment related.

2. Brain weight : Brain weights were not measured in this study.

3. Neuropathology : No microscopic alterations of neural fibers or tissues were observed

.

III. DISCUSSION AND CONCLUSIONS :

A. INVESTIGATORS ’ CONCLUSIONS : The investigators found reduced body weight gains reduced by 111% in males and in females by 23% at 2000 mg/kg bw in days 0-1 and Days 0- 7 respectively, and concluded that effects on body weight and body weight gains were not

affected at 100 or 500 mg/kg bw . The reported change s were transient and not considered

adverse. Food consumption was reduced 9.6% (N.S.) in males and by 21% in females at 2000 mg/k bw compared to controls. The changes were considered transient and not adverse

and did not affect the b ody weights of the test animals. It was determined that there were no effects on grip strength or foot splay in either sex at any dose. Body temperatures were reduced statistically significantly in males at 2000 mg/kg bw and in females at 500 and 2000 mg/kg bw on Day 0, but recovery occurred by Day 7 and the changes were not considered

adverse.

Males at 2000 mg/kg bw had fewer rearing incidences than controls (N.S.) at Day 0. However, females had fewer incidences of rea ring at 2000 (p<0.05) at Day 0, but were essentially back to control group levels at Day 7. The effect was considered to be test dose

related and adverse. There was a reported decrease of activity as related to the home cage

condition of a curled- up post ure and low arousal in the open field. In both cases the controls were 0/12. The posture change included 4/12 and correlated in males at 2000 mg/kg bw with reduced motor activity on Day 0. The effect was considered to be test substance related and

adverse. Changes later in the study (i.e. Day 7 and Day 14) were not considered test dose

related in females.Acute Neurotoxicity Study (rats) ( 2011) / Page 13 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424



### Motor activity was statistically significantly decreased in males at 500, 2000 mg/kg bw in the first 30 minutes (sessions 1-3) of Day 0 and in females at 2000 mg/kg bw (sessions 1- 3). The

decreases in males at 500 and above were considered to be adverse and test dose related. However, there was statistically positive data for 100 mg/kg bw males in the #2 session followed by a NS decrease in session #3 , these changes were not considered adverse. Statistically significant decreases in duration (seconds/session) were noted in the 500 mg/kg bw group in sessions 1, 3, 4 and at 2000 mg/kg bw in sessions 1, 2, 3, 4. These decreases

were considered test related and adverse. No test substance related gross lesions of neural tissues or microscopic pathology were observed.

The investigators considered at the NOAEL is 100 mg/kg bw in males and females based on systemic toxicity (body weight gains) accompanied by associated effects on motor activity, rearing and/or low arousal parameters on Day 0 (dosing) at 500 mg/kg bw. A NOAEL for neurotoxicity is 2000 mg/kg bw based on the absence of neuropathology and neurobehavioral

parameters.

B. REVIEWER COMMENTS :

Body weight gains were significantly reduced by 111.4% (p<0.05) in males on day 0- 1 at 2000 mg/kg bw , but these effects were not seen at later time intervals. Reductions in body weight gain in males at other dose levels were not significant, though there w ere questionable reductions at 500 mg/kg bw on Days 0-1. In females there was a significant decrease in body weight gain for the time period of 0-7 days, but this significance was not seen for the 9-14 day period. In the absence of decreased absolute body weights, the changes were not

considered adverse.

Food intake values at Day 0-1 for both sexes at 2000 mg/kg bw indicate significant reductions in consumption (Males, -9.6% (NS) and females, -20.8% (p<0.05).

Body temperatures on Day 0 were statisticall y significantly reduced 1 °C in males at 2000 mg/kg bw and at 500 (p<0.05 ) and 2000 mg/kg bw 1.2 °C in females. Recovery was complete by Day 7.

R earing in males 2/12 vs. 5/12 (NS) and females 4/12 vs. 7/12 was significantly reduced at 2000 mg/kg bw at Day 0.

In FOB observations, males preferred a curled -up posture at 2000 mg/kg bw on Day 0 (4/12 vs. 0/12, p<0.05) compared to control animals. Additionally, the males were more difficult to arouse in the 500 and 2000 mg/kg bw groups (3/12, 3/12 vs. 0/12), (p<0.05). Females

e xhibited slightly lower body temperatures at 500 mg/kg bw (p<0.05) compared to controls.

Motor activity total counts were lower for the sum of the 9, 10 minute sessions on Day 0 in males at 500 and 2000 mg/kg bw than controls or animals at 100 mg/kg bw. The reduced activity numbers were not statistically different from controls. However, individual 10 minute sessions in male and female rats at 100, 500 and 2000 mg/kg bw showed a temporary albeit significant reduction in activity

. In Session #2 (20 minutes) all three dose levels were significantly reduced in males. In Session #3 (30 minutes) reductions occurred at 500 andAcute Neurotoxicity Study (rats) ( 2011) / Page 14 of 14 Chlorimuron Ethyl/128901 OPPTS 870.6200a/ DACO 4.5.12/ OECD 424



### 2000 mg/kg bw in males. In Session s #4 and #5 (40-50 minutes) (NS), reductions appeared

to plateau to levels similar to controls in males. Females at Session #2 were statistically significantly reduced at 2000 mg/kg bw and NS but lower than controls at 500 mg/kg bw. In Sessions #4-#6 females at 500 and 2000 mg/kg bw had values lower than control, but NS.

The NOAEL is 100 mg/kg/day, based on reduced arousal and reduced motor activity in male

and female rats at the LOAEL of 500 mg/kg bw.

The study is considered to be Acceptable / Guideline and satis fies the requirement for acute neurotoxicity.

C. STUDY DEFICIENCIES :

• Time to peak effect information was not presented.