Document ID: EPA-HQ-OPP-2005-0058-0003
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-09-27T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF           

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

September 8, 2006		

				

MEMORANDUM

	Subject:	Ethaboxam: Revised Human Health Risk Assessment for Requested
Tolerances on Grapes and Processed Commodities.

		PC Code:  090205

		Petition No:  4E6863

		DP Number:  D332315

		Regulatory Action:  Tolerance without a U.S. Registration

		Risk Assessment Type:  Single Chemical Aggregate

	From:	Michael A. Doherty, Ph.D., Chemist

		Karlyn J. Bailey, Toxicologist			

		Registration Action Branch II

		Health Effects Division (7509C)

	Through:	Richard A. Loranger, Ph.D., Branch Senior Scientist

		Registration Action Branch II

		Health Effects Division (7509C)

		Christina Swartz, Branch Chief

		Registration Action Branch II

		Health Effects Division (7509C)

	To:	Bryant Crowe/Cynthia Giles-Parker

		Fungicide Branch

		Registration Division (7505C)

This document is a revision of the human health risk assessment for
ethaboxam issued by HED on June 20, 2006 (M. Doherty, K. Bailey, DP No.
310098).  The original assessment has been changed to remove several
statements regarding the need for additional testing to elucidate
potential endocrine effects from ethaboxam (p. 12 and P. 25).  The
intent of the original assessment was to indicate that because there are
known endocrine effects associated with ethaboxam, additional testing
may be requested in the future (in accordance with the Endocrine
Disruption Screening Protocols).  However, there are no specific studies
being requested at this time because endocrine effects have been
well-characterized in an acceptable 2-generation reproduction study with
a clear NOAEL/LOAEL, and the chronic reference dose (cRfD) selected for
ethaboxam risk assessments is considered protective.  To the extent that
new or revised tests are developed in connection with the endocrine
disruption screening program that can provide more information on
endocrine effects, EPA will consider whether further testing of
ethaboxam is appropriate. Because the toxicity database for ethaboxam is
complete (i.e., there are no data gaps), there is no evidence of
susceptibility, and all adverse effects have been well-characterized and
are addressed by at least a safety factor of 100X, HED recommended the
10X FQPA safety factor be reduced to 1X.  In addition to the revised
statements regarding testing for endocrine disruption, this revised risk
assessment deletes the need for submission of an analytical reference
standard and completion of the Agency method validation on pages 4, 28
and 29; the analytical reference standard has been received, and a
successful Agency method validation was completed. 

Table of Contents

  TOC \o "1-6" \f  1.0	Executive Summary	  PAGEREF _Toc133304132 \h  5 

2.0	Ingredient Profile	  PAGEREF _Toc133304133 \h  7 

3.0	Metabolism Assessment	  PAGEREF _Toc133304134 \h  8 

3.1 	Comparative Metabolic Profile	  PAGEREF _Toc133304135 \h  8 

3.2	Nature of the Residue in Foods	  PAGEREF _Toc133304136 \h  9 

3.2.1.	Description of Primary Crop Metabolism	  PAGEREF _Toc133304137 \h
 9 

3.2.2	Description of Livestock Metabolism	  PAGEREF _Toc133304138 \h  9 

3.2.3	Description of Rotational Crop Metabolism	  PAGEREF _Toc133304139
\h  9 

3.3 	Environmental Degradation	  PAGEREF _Toc133304140 \h  9 

3.4 	Tabular Summary of Metabolites and Degradates	  PAGEREF
_Toc133304141 \h  10 

3.5	Toxicity Profile of Major Metabolites and Degradates	  PAGEREF
_Toc133304142 \h  11 

3.6	Summary of Residues for Tolerance Expression and Risk Assessment	 
PAGEREF _Toc133304143 \h  11 

3.6.1	Tabular Summary	  PAGEREF _Toc133304144 \h  11 

3.6.2	Rationale for Inclusion of Metabolites and Degradates	  PAGEREF
_Toc133304145 \h  11 

4.0	Hazard Characterization/Assessment	  PAGEREF _Toc133304146 \h  12 

4.1	Hazard Characterization	  PAGEREF _Toc133304147 \h  12 

4.2	FQPA Hazard Considerations	  PAGEREF _Toc133304148 \h  19 

4.2.1	Adequacy of the Toxicity Data Base	  PAGEREF _Toc133304149 \h  19 

4.2.2	Evidence of Neurotoxicity	  PAGEREF _Toc133304150 \h  19 

4.2.3	Developmental Toxicity Studies	  PAGEREF _Toc133304151 \h  20 

4.2.4	Reproductive Toxicity Study	  PAGEREF _Toc133304152 \h  20 

4.2.5	Additional Information from Literature Sources	  PAGEREF
_Toc133304153 \h  21 

4.2.6	Pre-and/or Postnatal Toxicity	  PAGEREF _Toc133304154 \h  22 

4.2.6.1	Determination of Susceptibility	  PAGEREF _Toc133304155 \h  22 

4.2.6.2	Degree of Concern Analysis and Residual Uncertainties for Pre
and/or Post-natal Susceptibility	  PAGEREF _Toc133304156 \h  22 

4.3	Recommendation for a Developmental Neurotoxicity Study	  PAGEREF
_Toc133304157 \h  22 

4.3.1	Evidence that supports requiring a Developmental Neurotoxicity
study	  PAGEREF _Toc133304158 \h  22 

4.3.2	Evidence that supports not requiring a Developmental Neurotoxicity
study	  PAGEREF _Toc133304159 \h  23 

4.4	Hazard Identification and Toxicity Endpoint Selection	  PAGEREF
_Toc133304160 \h  23 

4.4.1	Acute Reference Dose (aRfD) - Females age 13-49	  PAGEREF
_Toc133304161 \h  23 

4.4.2	Acute Reference Dose (aRfD) - General Population	  PAGEREF
_Toc133304162 \h  23 

4.4.3	Chronic Reference Dose (cRfD)	  PAGEREF _Toc133304163 \h  23 

4.4.4	Non-Dietary Exposure (All Durations)	  PAGEREF _Toc133304164 \h 
24 

4.4.5	Classification of Carcinogenic Potential	  PAGEREF _Toc133304165
\h  24 

4.4.6	Recommendation for Aggregate Exposure Risk Assessments	  PAGEREF
_Toc133304166 \h  25 

4.5	FQPA Safety Factor	  PAGEREF _Toc133304167 \h  25 

4.6	Endocrine disruption	  PAGEREF _Toc133304168 \h  26 

5.0	Public Health Data	  PAGEREF _Toc133304169 \h  26 

6.0	Exposure Characterization/Assessment	  PAGEREF _Toc133304170 \h  27 

6.1	Dietary Exposure/Risk Pathway	  PAGEREF _Toc133304171 \h  27 

6.1.1	Residue Profile	  PAGEREF _Toc133304172 \h  27 

6.1.2	Acute and Chronic Dietary Exposure and Risk	  PAGEREF
_Toc133304173 \h  28 

6.2	Water Exposure/Risk Pathway	  PAGEREF _Toc133304174 \h  28 

6.3	Residential (Non-Occupational) Exposure/Risk Pathway	  PAGEREF
_Toc133304175 \h  28 

7.0	Aggregate Risk Assessments and Risk Characterization	  PAGEREF
_Toc133304176 \h  28 

8.0	Cumulative Risk Characterization/Assessment	  PAGEREF _Toc133304177
\h  29 

9.0	Occupational Exposure/Risk Pathway	  PAGEREF _Toc133304178 \h  29 

10.0	Data Needs and Label Requirements	  PAGEREF _Toc133304179 \h  29 

10.1	Toxicology	  PAGEREF _Toc133304180 \h  29 

10.2	Residue Chemistry	  PAGEREF _Toc133304181 \h  29 

10.3	Occupational and Residential Exposure	  PAGEREF _Toc133304182 \h 
30 

References:	  PAGEREF _Toc133304183 \h  31 

Appendices	  PAGEREF _Toc133304184 \h  32 

 

1.0	Executive Summary  TC \l1 "1.0	Executive Summary 

LG Life Sciences, Ltd. has petitioned the Agency to establish tolerances
for residues of the fungicide ethaboxam in/on grapes in order to allow
legal importation of ethaboxam-treated grapes and processed commodities
of grapes into the U.S.  The request covers both wine and table grapes. 
The petition does not include a request to register ethaboxam uses in
this country.  The Health Effects Division (HED) has reviewed the
submitted data and recommends that a tolerance of 6.0 ppm be established
for residues of ethaboxam in/on grapes pending the resolution of
deficiencies related to residue chemistry data.  Since the only source
of exposure to ethaboxam at this time is via food, HED has not assessed
any non-dietary exposures.  Therefore, this document does not include
assessments for exposure via drinking water, through residential
pathways, or from occupational activities.

Toxicological studies with rats, mice, rabbits, and dogs show varying
effects in the different species tested, with rats being the most
sensitive of the four.  In male rats, ethaboxam exposure results in
adverse effects on the testes, epididymides, prostate, and seminal
vesicles.  It also results in reproductive toxicity, observed as
reductions in mating and decreases in the fertility index.  Furthermore,
ethaboxam has been classified as having “suggestive evidence of
carcinogenic potential” based on Leydig cell tumors observed in male
rats.  There was indication of qualitative susceptibility in the rat
developmental toxicity study and the 2-generation reproduction study;
however, there was no susceptibility seen in a developmental rabbit
study.  Administration of ethaboxam to mice resulted in mild effects on
the liver.  In dogs, exposure to ethaboxam resulted in decreases in body
weight and body weight gain.  Treatment-related effects on male
reproductive organs were not observed in studies with mice, rabbits, or
dogs; similarly, treatment-related liver effects were not observed in
studies with rabbits or dogs.  A developmental toxicity study in rats
suggests that ethaboxam may affect normal liver development.  HED has
based this risk assessment on effects observed in the rat studies.

The tolerance petition is relatively complete with respect to residue
chemistry data; however, data deficiencies have been noted.  Some of
these should be resolved prior to establishing tolerances, including
submission of labels from countries in which ethaboxam registrations are
being sought, and submission of a revised Section F of the petition. 
Other deficiencies should be resolved as soon as possible and prior to
the establishment of any additional tolerances for ethaboxam.  The
petitioner has submitted studies depicting the metabolism of ethaboxam
in grape, tomato, and potato.  Based on the information in those studies
and for the purposes of the current petition, HED concludes that the
residue of concern, for the purposes of both tolerance-enforcement and
risk-assessment is ethaboxam, per se.  Residue trials conducted in
Europe, Australia, and South America resulted in measurable levels of
ethaboxam in grapes from all locations.  The submitted data support a
tolerance of 6.0 ppm for residues in/on grapes.  Studies examining the
transfer of ethaboxam to processed grape commodities (e.g., grape juice,
raisins, wine) show that some concentration of ethaboxam may occur
during the production of raisins and grape juice; however, the supported
tolerance of 6.0 ppm for grapes is sufficient to cover the potential for
residues in the processed commodities, and separate tolerances for these
commodities are not needed.

As noted above, the only exposure pathway that is expected for ethaboxam
is dietary exposure.  To assess dietary exposure, HED has used the
Dietary Exposure Evaluation Model with the Food Commodity Intake
Database (DEEM-FCID) with highly health-protective assumptions regarding
level and prevalence of ethaboxam resides in grapes and processed grape
commodities.  Risk estimates based on these assumptions are below
HED’s level of concern for all population subgroups, including those
of infants and children.

HED has evaluated the available data and is recommending that a
permanent tolerance of 6.0 ppm be established for residues of ethaboxam
in/on grape pending resolution of the deficiencies, as noted in Section
10 of this document.  HED further recommends that the CFR entry clearly
states that there is no U.S. registration for ethaboxam on grapes at
this time.2.0	Ingredient Profile  TC \l1 "2.0	Ingredient Profile 

Ethaboxam is a novel thiazole carboxamide fungicide that controls
various diseases caused by oomycetes.  It has been registered in South
Korea and is currently in the registration track in many European
countries.  The chemical structure and nomenclature of ethaboxam are
presented in Table 2.1, and the physicochemical properties of the
technical grade of ethaboxam are presented in Table 2.2.  The petitioner
has indicated that the active ingredient will be formulated as a 10%
suspension concentrate (100 g a.i./L).  The proposed use directions are
summarized below in Table 2.3.

-(α-cyano-2-thienyl)-4-ethyl-2-(ethylamino)-1,3-thiazole-5-carboxamide

CAS name
N-(cyano-2-thienylmethyl)-4-ethyl-2-(ethylamino)-5-thiazolecarboxamide

CAS registry number	162650-77-3

End-use product (EP)	LGC-30473 10% SC (100 g/L ethaboxam)

Table 2. 2.   Physicochemical Properties of Ethaboxam.

Parameter	Value	Reference

Melting point/range	decomposes on melting at 185 ºC	MRID 46378504

pH	6.8 (1% w/v suspension)	MRID 46378502

Density	1.28 at 24 °C

	Water solubility	12.4 mg/L at 25 °C	MRID 46378508

Solvent solubility	                                                     
  at 20 °C

n-heptane                                       0.39 mg/L

xylene                                               0.14 g/L

n-octanol                                          0.37 g/L

1,2-dichloroethane                             2.9 g/L

ethyl acetate                                        11 g/L

methanol                                              18 g/L

λmax (nm)     Absorbance      Є (dm3/mol/cm)

Water:ACN              231 (shoulder)      0.696                11200

                                        311                 1.144       
        18400

0.125M HCl:ACN          235                 0.794                12800

                                        284                 1.006       
        16200

0.125M NaOH:ACN      252                 0.678                10900

                                  262 (shoulder)     0.622              
  10000

                                        289                 0.647       
         10400

                                        335                 1.098       
         17700

No absorption maxima at wavelengths >400 nm.

	1 ACN = acetonitrile; all ratios were 4:1, v:v.

Table 2.3.   Summary of Proposed Directions for Use of Ethaboxam on
Grapes.

Trade Name	Application Timing	Application Rate 

(lb ai/A)

[g ai/ha]	Max. No. Applic. per Season	RTI1

(days)	Max. Seasonal Applic. Rate

(lb ai/A)

[g ai/ha]	PHI

(days)	Use Directions and other Limitations

Grape [including all grapevine cultivars (wine and table) and also
grapevine nursery plants]

LGC-30473 10% SC	May be applied at any crop growth stage	0.178

[200]	5	7-10	0.892

[1,000] 2	21	Three to five applications may be made using ground
equipment in a spray volume of 200-1,000 L/ha.  May be tank mixed with
copper oxychloride.

1 RTI = Retreatment interval

2 Maximum seasonal application rate is implied and is based on the
maximum number of applications and the maximum single application rate.

3.0	Metabolism Assessment  TC \l1 "3.0	Metabolism Assessment 

3.1 	Comparative Metabolic Profile  TC \l2 "3.1 	Comparative Metabolic
Profile 

Data depicting the metabolism of ethaboxam in rats, grape, potato, and
tomato have been submitted to the Agency.  Studies of metabolism in
rotational crops and livestock, and of ethaboxam’s environmental
degradates are not readily available to HED at this time.  Lack of these
studies does not constitute critical data gaps since the current request
is for establishment of “import tolerances.”

In rats dosed with radiolabeled ethaboxam, nearly 100% of the dose was
excreted within 48 hours of administration.  The primary route of
excretion was in feces (approximately 70% of the administered dose);
excretion in urine accounted for up to 30% of the administered dose.  In
feces, ethaboxam was identified as the major compound, followed by
LGC-32801, which was the major compound identified in rat urine (Table
3.4).  A comparison of low- and high-dose results from the metabolism
study indicates that at the high dose (150 mg/kg for 14 days) uptake of
ethaboxam was less than that which occurred at the low dose (10 mg/kg
for 14 days).

The nature of the residue in grape is adequately understood based on
acceptable metabolism studies conducted on grape, potato, and tomato. 
For the purposes of this petition, the residue of concern is the parent
compound.  Generally, ethaboxam was readily metabolized in the studied
plants and incorporated into natural products (primarily sugars). 
Ethaboxam was the major residue component identified in all reviewed
plant metabolism studies.  However, the extent of ethaboxam metabolism
varied quantitatively among the crops tested.  In grapes, the metabolite
LGC-35523 also comprised a significant portion (up to 18%) of the total
radioactive residue (TRR; Table 3.4).  Further details of the metabolism
of ethaboxam in plants are given in Section 3.2.

Metabolism of ethaboxam appears to be quite different in plants and
animals based on the available data.  Although in all tested species the
major residue is ethaboxam, the primary metabolite in rats, LGC-32801,
was not observed in plants.  Similarly, the primary metabolite in grape
and tomato, LGC-35523, was not formed during metabolism in the rat.

3.2	Nature of the Residue in Foods  TC \l2 "3.2	Nature of the Residue in
Foods 

3.2.1.	Description of Primary Crop Metabolism  TC \l3 "3.2.1.
Description of Primary Crop Metabolism 

In grapes, the parent compound accounted for 52.4-54.6%, 24.9-31.7%,
33.1-34.1%, and 27.4-29.4% of TRR from fruit samples collected 0, 5, 10,
and 14 days following the last treatment, respectively.  Additional
radioactivity in grapes treated with the thiazole radiolabel (15.9-28.5%
TRR) was shown to be incorporated into sugars.  The only other
metabolite identified was LGC-35523, a keto carboxylic acid derivative
of thiophene labeled ethaboxam which the petitioner stated is identical
to a photodegradate present in an aqueous photolysis study.  LGC-35523
accounted for up to 18% of the total radioactive residues in grapes
(Table 3.4).  In tomatoes, the parent comprised 62.6-64.3%, 55.1-61.8%,
59.7-64.3%, and 49.2-57.7% TRR from mature samples collected 3, 7, 14,
and 21 days following the last treatment, respectively.  LGC-35523
accounted for up to 4% of the TRR in tomato fruit.  In potatoes, the
parent accounted for only 2.7% TRR of tubers harvested at a 14-day PHI,
and a significant portion of extractable radioactivity was shown to be
incorporated to carbohydrates such as glucose and starch.  Metabolite
LGC-35523 was not detected in potatoes.

The propensity of translocation of ethaboxam residues in/on grapes and
tomatoes was investigated by covering branches and/or trusses prior to
applications of the test substance.  When the TRR of covered versus
uncovered matrices are compared, approximately 2-13% TRR was
translocated into covered tomatoes and 12.3-25.6% TRR was translocated
into covered grapes.

3.2.2	Description of Livestock Metabolism  TC \l3 "3.2.2	Description of
Livestock Metabolism 

Data depicting metabolism of ethaboxam in livestock are not available,
nor are they required at this time.  Should the petitioner expand their
requests for ethaboxam to include significant livestock feed items, then
a livestock metabolism study will be required.

3.2.3	Description of Rotational Crop Metabolism  TC \l3 "3.2.3
Description of Rotational Crop Metabolism  

The current request does not include a scenario whereby residues in
rotational crops would be of concern.  Should the petitioner wish to
include a U.S. use of ethaboxam on rotated crops, a confined rotational
crop study will be required.

3.3 	Environmental Degradation  TC \l2 "3.3 	Environmental Degradation 

As the current request does not include a registration for use of
ethaboxam in the U.S., HED does not require either environmental fate
information or residue estimates for drinking water at this time.

3.4 	Tabular Summary of Metabolites and Degradates  TC \l2 "3.4 	Tabular
Summary of Metabolites and Degradates 

Table 3.4.   Tabular Summary of Metabolites and Degradates.  Reported
data are ranges across all PHIs.

Chemical Name	Commodity	Percent TRR (ppm)	Structure

Thiazole Label	Thiophene Label

	Ethaboxam

N-(cyano-2-thienylmethyl)-4-ethyl-2-(ethylamino)-5-thiazolecarboxamide
Rat - Feces	Low Dose – 10%

High Dose – 68%	Low Dose – 14%

High Dose – 54%	

	Rat - Urine	Not Found	Not Found

Grape	29-55 (0.16-1.0)	27-52 (0.23-0.82)

Tomato	49-64 (0.20-0.85)	58-63 (0.40-0.92)

Potato 	Not Found	3 (0.001)

	LGC-35523

	Rat – Urine	N/A	Not Found

Grape	N/A	11-18 (0.17)

Tomato	N/A	2-4 (0.02-0.05)

Potato 	N/A	Not Found

	LGC-32800

 

	Rat – Urine	Low Dose – 3

High Dose – 2	Low Dose – 3

High Dose – 2

Grape	Not Found	Not Found

Tomato	Not Found	Not Found

Potato 	Not Found	Not Found

	LGC-32801

2-[(4-Ethyl-2-ethylamino-thiazol-5-yl)-hydroxy-methylimino]-2-thiophen-2
-yl-acetamide	Rat - Feces	Low Dose – 5

High Dose – 2	Low Dose – 5

 

	Rat – Urine	Low Dose – 10

High Dose – 3	Low Dose – 9

High Dose – 3

Grape	Not Found	Not Found

Tomato	Not Found	Not Found

Potato 	Not Found	Not Found

	LGC-32802

Sulfuric acid
mono-{(2-amino-4-ethyl-thiazol-5-yl)-[(cyano-thiophen-2-yl-methylene)-am
ino]-methyl} e

ster	Rat - Feces	Low Dose - 11

High Dose - 5	Low Dose - 10

 

	Rat – Urine	Not Found	Not Found

Grape	Not Found	Not Found

Tomato	Not Found	Not Found

Potato 	Not Found	Not Found

	LGC-32803

Sulfuric acid
mono-[[(cyano-thiophen-2-yl-methylene)-amino]-(4-ethyl-2-ethylamino-thia
zol-5-yl)-meth

yl] ester	Rat - Feces	Low Dose - 6

High Dose - 4	Low Dose - 6

 

	Rat – Urine	Not Found	Not Found

Grape	Not Found	Not Found

Tomato	Not Found	Not Found

Potato 	Not Found	Not Found

	All studies included separate investigation of radiolabel located in
the thiazole ring or the thiophene ring.  Ranges of residues found in
grape, tomato, and potato are due to decreasing residue levels with
increasing PHI.

Grape: MRID No. 46668301, 46378507; Total Application Rate:  1.12 lb
a.i./A (1.25X); 0, 5, 10, 14-day PHIs.

Tomato:  MRID No. 46378508; Total Application Rate:  0.535 lb a.i./A; 0,
3, 7, 14, 21-day PHIs.

Potato:  MRID No. 46378506; Total Application Rate:  1.1 or 1.2 lb
a.i./A; 14-day PHI.

Rat: MRID No. 46378533; dosing level: 10 or 150 mg/kg for 14 days

3.5	Toxicity Profile of Major Metabolites and Degradates   TC \l2 "3.5
Toxicity Profile of Major Metabolites and Degradates  

The OECD Tier II/Tier III summaries that accompanied the ethaboxam data
submission indicate that assays for acute oral toxicity, 28-day repeated
oral toxicity, reverse gene mutation, and in-vitro chromosomal
aberration were conducted with the LGC-35523 metabolite.  The results of
those studies suggest that LGC-35523 is toxicologically insignificant
(See Section 3.6.2 and MRID 46824211, page 21).

3.6	Summary of Residues for Tolerance Expression and Risk Assessment  TC
\l2 "3.6	Summary of Residues for Tolerance Expression and Risk
Assessment 

3.6.1	Tabular Summary  TC \l3 "3.6.1	Tabular Summary 

Table 3.6.  Summary of Metabolites and Degradates to be included in the
Risk Assessment and Tolerance Expression

Matrix	Residues included in Risk Assessment	Residues included in
Tolerance Expression

Plants	Primary Crop	Ethaboxam	Ethaboxam

	Rotational Crop	Not Applicable	Not Applicable

Livestock	Ruminant	Not Applicable	Not Applicable

	Poultry	Not Applicable	Not Applicable

Drinking Water	Not Applicable	Not Applicable

3.6.2	Rationale for Inclusion of Metabolites and Degradates  TC \l3
"3.6.2	Rationale for Inclusion of Metabolites and Degradates 

Ethaboxam and LGC-35523 were the only significant residues found in the
grape metabolism study.  In addition to occurring at a significant
portion of the applied radioactivity in grapes, LGC-35523 was not found
in the rat metabolism study, thereby making it a potential residue of
concern for risk assessment.  However, LGC-35523 is expected to be
significantly less toxic than the parent and to have different toxicity
than ethaboxam for the following reasons (A. Protzel, pers. comm.,
Attachment 1):

LGC-35523 is a very polar compound that is likely to undergo rapid
excretion with very little biochemical transformation in mammals.  It is
not likely to engage in interactions, as the much less polar parent will
do, that might lead to microsomal enzyme induction, inhibition of
mitochondrial respiration or endocrine disruption. 

The following 28-day rat dietary studies indicate that LGC-35523 is less
toxic than the parent:

LGC-35523.  In a rat dietary study conducted at levels of 650, 2000 or
13,000 ppm, LGC-35523 had a NOAEL of 2000 ppm and a LOAEL of 13,000 ppm
(with relatively benign treatment-related effects). 

Ethaboxam.  In a rat dietary study conducted at levels of 500, 1000,
3000, or 5000 ppm, parent ethaboxam had a NOAEL of 500 ppm and a LOAEL
of 1000 ppm attributable to reduced food intake plus toxicity resulting
in growth retardation.  At higher doses liver and thyroid weights were
increased.

4.0	Hazard Characterization/Assessment  TC \l1 "4.0	Hazard
Characterization/Assessment 

4.1	Hazard Characterization  TC \l2 "4.1	Hazard Characterization 

The toxicology database for ethaboxam is complete and adequate for
selection of doses and endpoints for use in risk assessments for
evaluation of the proposed import tolerances.    SEQ CHAPTER \h \r 1
Since the proposed tolerances for ethaboxam are for imported grapes and
its processed commodities, the only study required to evaluate acute
toxicity is the acute oral toxicity study.  Acute oral exposure to
ethaboxam results in low toxicity and is classified in Toxicity Category
IV.

Acute and subchronic neurotoxicity studies are not available for
ethaboxam.  Post-dose salivation was observed in a developmental rat
study at 300 and 1000 mg/kg/day.  However, in another developmental rat
study and a developmental rat range-finding study post-dose salivation
was not observed.  There were no other signs of neurotoxicity observed
in the database. 

The male reproductive system is a target for ethaboxam, with alterations
to the male reproductive organs observed in several rat studies.  In a
90-day feeding study in rats, there were severe testicular alterations
(atrophy, abnormal spermatids, and interstitial cell hyperplasia) at 650
ppm.  In the epididymides, there were abnormal spermatogenic cells
(ducts) and absent spermatozoa.  A combined chronic/carcinogenicity
study in rats demonstrated testicular toxicity in the form of
seminiferous tubule atrophy and degeneration at 650 ppm.  In the
epididymides, there were absent/reduced spermatozoa, abnormal
spermatogenic cells (duct), epithelial vacuolation (duct), and
intraepithelial lumina.  Also at 650 ppm, there were increased
incidences of acinar atrophy and reduced colloid in the prostate, and
seminal vesicle atrophy.  There were no treatment-related male
reproductive effects observed in mice but there were mild effects seen
on the liver.  In a carcinogenicity study in mice, liver effects were
seen at 900 ppm in the form of increased liver weights associated with
centrilobular hypertrophy, and liver histopathology (eosinophilic foci).
 In a 90-day feeding study in mice, liver findings were limited to
increases in liver weight and centrilobular hepatocyte hypertrophy at
450 ppm (males) and 1000 ppm (females); these findings were considered
adaptive responses.  In dogs, there were no treatment-related male
reproductive or liver effects observed.  In a 90-day feeding study in
dogs, the only treatment-related effect seen was decreased body weight
and body weight gain at 15 mg/kg/day in females only.  There were no
treatment-related effects observed in male or female dogs in a chronic
feeding study.

There was indication of increased qualitative susceptibility in the rat
developmental toxicity study and the 2-generation reproduction study. 
In the developmental rat study, there were increased incidences of
abnormal liver lobation, seen in the presence of less severe maternal
effects (increased water consumption and alopecia) at the LOAEL of 100
mg/kg/day.  In the 2-generation reproduction study, there was decreased
body weight and decreased viability of the F1 and F2  pups during
lactation, with parental effects limited to decreased body weight gain
(F0 males) and decreased body weight (F1 males) at 650 ppm.  There was
no evidence of quantitative susceptibility in the rat developmental or
2-generation reproduction study.  In the developmental toxicity study in
rabbits, there was no evidence of quantitative or qualitative
susceptibility.  At 125 mg/kg/day, maternal animals exhibited prolonged
inappetence (GD 7-10), poor body condition (GD 12-13), and greater body
weight loss during GD 6-8 (-73 g vs. -16 g for controls).  Decreased
food consumption was observed at 75 (81%) and 125 mg/kg/day (70%) during
GD 6-7.  There were no treatment-related developmental effects seen in
the study.

Ethaboxam has been shown to induce Leydig cell tumors in male rats.  The
Cancer Assessment Review Committee (CARC) met on February 15, 2006 and
classified ethaboxam as having “suggestive evidence of carcinogenic
potential.”  The Committee concluded that quantification of
carcinogenic potential is not required.  In addition, the Committee
recommends that the in vitro cytogenetics assay be repeated to clarify
the earlier results.  With respect to risk assessment, the chronic RfD
is protective of the potential cancer effects.

  SEQ CHAPTER \h \r 1 It is likely that ethaboxam may cause disruption
in the endocrine system, based on   histopathological (lesions in the
testes, epididymides, prostate, and seminal vesicles) and reproductive
(reductions in percentage mating and male fertility index) alterations
observed in several rat studies.  

In a 5-day metabolism study in rats with radiolabeled thiazole or
thiophene, the majority of the radiolabeled compound was excreted in the
feces or urine within 48 hours of administration, regardless of
radiolabel, dose, or sex.   For both radiolabels, fecal and urinary
excretion combined accounted for 96-104% of the administered dose.  The
main route of excretion was feces (66-74% of single or repeated
administered low-dose), followed by urine (23-30% of the administered
low-dose).  In the biliary excretion study, the percentage of thiazole
radiolabeled compound absorbed within 48 hours was 71% (males) and 72%
(females) in the low dose and 48% (males) and 61% (females) in the high
dose.  Approximately 79-94% of compound was absorbed after 48 hrs,
depending upon the dose.  Minimal amounts (<1% of the dose) of the
radiolabeled compound were retained in the tissues up to 120 hours post
dosing.  The thyroid generally contained the highest μg equivalents/g
of the thiazole label, but only minimal amounts of the thiophene label. 
There were minimal differences between the thiazole or thiophene label,
except for the longer half-life (t1/2) in blood cells.  The blood cell
pharmacokinetic values were generally comparable to or lower than plasma
values.  There were also minimal quantitative differences noted within
the metabolic profiles of urine, feces, or bile from rats administered
the same doses of compound with the thiazole or thiophene label.  The
major urinary radioactive component was LGC-32801, followed by
LGC-32800.  The major fecal component was the parent compound
(LGC-30473), followed by LGC-32802, LGC-32803 and LGC-32801.  The main
biliary radioactive components were LGC-32801 and LGC-32794.

Since this assessment is for an import tolerance, the anticipated   SEQ
CHAPTER \h \r 1 exposure route for the U.S. population is via the diet
(food only).  Thus, residential and occupational exposure risk
assessments for incidental oral, dermal, and inhalation routes of
exposure are not required.  A developmental toxicity study in the rat
was used to select the dose and endpoint for establishing the aRfD of
0.3 mg/kg/day for pregnant females ages 13-49; an aRfD for the general
population was not identified.  For chronic dietary exposure (cRfD), a
combined chronic/carcinogenicity study in the rat was used to select the
dose and endpoint for establishing the cRfD of 0.055 mg/kg/day.

 

Table 4.1 Acute Toxicity Profile for Ethaboxam (99.0%)

Guideline Number	Study Type

Classification	MRID

Number	Results 	Toxicity Category

870.1100	Acute-oral	46378518	  SEQ CHAPTER \h \r 1 LD50 (♂ or ♀) >
5,000 mg/kg 

LD50 Combined >5,000 mg/kg	IV

870.1200	Acute-dermal	  SEQ CHAPTER \h \r 1 Not applicable for proposed
use pattern (Import tolerance)

870.1300	Acute-inhalation	  SEQ CHAPTER \h \r 1 Not applicable for
proposed use pattern (Import tolerance)

870.2400	Acute-eye irritation-rabbit	  SEQ CHAPTER \h \r 1 Not
applicable for proposed use pattern (Import tolerance)

870.2500	Acute-dermal irritation-rabbit	  SEQ CHAPTER \h \r 1 Not
applicable for proposed use pattern (Import tolerance)

870.2600	  SEQ CHAPTER \h \r 1 Skin sensitization - guinea pig	  SEQ
CHAPTER \h \r 1 Not applicable for proposed use pattern (Import
tolerance)

Table 4.2 Subchronic, Chronic and Other Toxicity Profile for Ethaboxam

  SEQ CHAPTER \h \r 1 GDLN 	Study Type/ Classification	Dose Levels	MRID
Results

870.3100	1997

13 WEEK FEEDING-RAT

Acceptable/Guideline	ppm = 0, 200, 650, 2000

mg/kg/day =

M: 0, 16.3, 49.7, 154

F: 0, 17.9, 58, 164	46387805	NOAEL (mg/kg/day)

M: 16.3 

F: 58

LOAEL (mg/kg/day):

M: 49.7,  based on testicular/epididymal effects (abnormal spermatids in
the testes, and abnormal spermatogenic cells in the epididymides)

F: 164, based on decreased body weights and fine vacuolation of the
adrenal zona glomerulosa. 

870.3100	2002

13 WEEK FEEDING-MOUSE

Acceptable/Guideline	ppm = 0, 200, 450, 1000

mg/kg/day =

M: 0, 33, 74, 163, 405

F: 0, 41, 93, 195, 483	46387802	NOAEL (mg/kg/day)

M: 450

F: 483

LOAEL (mg/kg/day):

not determined

870.3150	2001

13 WEEK FEEDING-DOG

 

Acceptable/Guideline	mg/kg/day =

0, 15, 40, 100	46387803	NOAEL (mg/kg/day): 

M: 100, F: not determined

LOAEL (mg/kg/day): M: not determined 

F: 15, based on reduced body weight (10%) and reduced body weight gain
(62%) 

870.3700	1997

DEVELOPMENTAL TOXICITY-RAT

Acceptable/guideline	mg/kg/day =

0, 10, 30, 100, 300	46387808

46488701

	Maternal: NOAEL (mg/kg/day): 30

Maternal: LOAEL (mg/kg/day): 100, based on hair loss (7/25) and
increased water consumption (124%).

Developmental: NOAEL (mg/kg/day): 30

LOAEL (mg/kg/day): 100, based on abnormal liver lobation (4 fetuses from
4 litters).

870.3700	1997

DEVELOPMENTAL TOXICITY-RABBIT

Acceptable/Guideline	mg/kg/day =

0, 25, 75, 125

	46490401

	Maternal: NOAEL (mg/kg/day): 75

LOAEL (mg/kg/day): 125, based on inappetence (2 animals sacrificed),
decreased food consumption (70%), and body weight loss (-73g vs. -16
controls). 

Developmental: NOAEL (mg/kg/day): 125

LOAEL (mg/kg/day): not determined

870.3800	2002

2-GENERATION REPRODUCTION-RAT 

Acceptable/Guideline	ppm = 

0, 65, 200, 650

mg/kg/day =

M: 0, 5.2, 16.2, 52.6

F: 0, 5.7, 17.6, 56.1      	46387804	Parental: 

NOAEL (mg/kg/day)

M/F: 16.2/17.6

LOAEL (mg/kg/day):

M/F: 52.6/56.1, based on decreased premating body weight gain of the F0
and F1 generation males (10.5-22% and 10.7-14.5%, respectively),
decreased premating body weight of the F1 males and females (10.3-17.45
and 7-12.9%, respectively).

Reproductive:

NOAEL (mg/kg/day)

M: 16.2, F: 56.1

LOAEL (mg/kg/day): 

M: 52.6, based on testicular lesions and reduced fertility in F1 males. 

F: not determined

Offspring:  

NOAEL (mg/kg/day)

M/F: 16.2/17.6

LOAEL (mg/kg/day):

M/F: 52.6/56.1, based on decreased body weight in male and female F1
pups (13.1-15.7%), and decreased viability of the F1 (14%) and F2 (17%)
males during lactation. 

870.4300	2002-104 WEEK COMBINED CHRONIC   TOXICITY/CARCINOGENICITY-RAT

Acceptable/Guideline	ppm = 

0, 100, 300, 650

mg/kg/day =

M: 0, 5.5, 16.4, 35.8

F: 0, 7, 21, 45.5	46387811	NOAEL (mg/kg/day)

M: 5.5 

F: 21

LOAEL (mg/kg/day):

M: 16.4, based on adverse effects seen in the male reproductive organs
(testes, epididymides, prostate, seminal vesicles)  

F: 45.5, based on decreased body weight (12%) and body weight gain
(16%).

Evidence of carcinogenicity Interstitial/Leydig cell adenoma at the
highest dose tested (35.8/45.5 mg/kg/day)

870.4100	2001-52 WEEK FEEDING-DOG

Acceptable/Non-guideline	mg/kg/day =

0, 5, 10, 30	46387809	NOAEL (mg/kg/day): 

M/F = 30

LOAEL (mg/kg/day): not determined

870.4200	2003- 52 WEEK CARCINOGENICITY-MICE

Acceptable/Guideline	ppm = 

0, 100, 300, 900

mg/kg/day =

M: 0, 12, 35, 117

F: 0, 14, 44, 135	46235628	NOAEL (mg/kg/day)

M/F: 35/44

LOAEL (mg/kg/day):

M/F: 117/135, based on decreased body weight (M/F=9%), body weight gain
(M/F =20%) and food efficiency (M=16%; F = 19%) in both sexes, and liver
toxicity in males.

No evidence of carcinogenicity 

870.5100	2004-BACTERIAL REVERSE MUTATION ASSAY

Acceptable/Guideline

46378529

 

	Negative

870.5300	2001-IN VITRO MAMMALIAN CELL GENE MUTATION TEST

Acceptable/Guideline

46378530

	Negative

870.5375	2001-IN VITRO MAMMALIAN CELL CHROMOSOME ABERRATION TEST 

Unacceptable/Guideline

46378531

	LGC-30473 induced significant (p< 0.01) increases in chromosome
aberrations and a marked increase in the mitotic index at a
concentration of 250 µg/mL (-S9) after a 3 hour exposure and at 100
µg/mL after 19 hours of continuous exposure.

870.5395	2001-MAMMALIAN ERYTHROCYTE MICRONUCLEUS TEST (XDE-750)

Acceptable/Guideline

46378532

	Negative

870.7485	2003-METABOLISM AND PHARMOKINETICS-RAT 

Acceptable/Guideline	Thiazole or Thiophene radiolabeled

mg/kg/day =

Low dose: 10

High dose: 150

Thiazole radiolabeled

Mg/kg/day = 10

Daily for 14 days

	46378533

	Excretion-Majority of the radiolabeled compound was excreted in the
feces or urine within 48 hours of administration, regardless of
radiolabel, dose, or sex.  For both radiolabels, fecal and urinary
excretion combined accounted for 96-104% of the administered dose. The
main route of excretion was feces (66-74% of single or repeated
administered low-dose), followed by urine (23-30% of the administered
low-dose).  Biliary excretion-thiazole radiolabeled compound absorbed in
males and females within 48 hours; low dose = 71 and 72%, respectively,
high-dose = 48 and 61%, respectively. After 48hrs, 79-94% compound
absorbed depending upon the dose.  

Tissue distributions-minimal amounts (<1% of the dose) of the
radiolabeled compound were retained in the tissues up to 120 hours post
dosing.  The thyroid generally contained the highest µg equivalents/g
of the thiazole label, but only minimal amounts of the thiophene label. 

870.7485	2003-METABOLISM AND PHARMOKINETICS-RAT 

Continued

	Thiazole or Thiophene radiolabeled

mg/kg/day =

Low dose: 10

High dose: 150

Thiazole radiolabeled

Mg/kg/day = 10

Daily for 14 days

	46378533

	Pharmacokinetic studies- minimal differences between the thiazole or
thiophene label, except for the longer t1/2 in blood cells.  The blood
cell pharmacokinetic values were generally comparable to or lower than
plasma values. 

Minimal quantitative differences were noted within the metabolic
profiles of urine, feces, or bile from rats administered the same doses
of compound with the thiazole or thiophene label.  The major urinary
radioactive component was LGC-32801, followed by LGC-32800.  The major
fecal component was the parent compound (LGC-30473), followed by
LGC-32802, LGC-32803 and LGC-32801.  The main biliary radioactive
components were LGC-32801 and LGC-32794.

4.2	FQPA Hazard Considerations  TC \l2 "4.2	FQPA Hazard Considerations 

4.2.1	Adequacy of the Toxicity Data Base  TC \l3 "4.2.1	Adequacy of the
Toxicity Data Base 

The toxicology database for ethaboxam is complete and adequate to
characterize potential pre- and/or post-natal risk for infants and
children.  Acceptable/guideline developmental toxicity studies in rats
and rabbits, and a 2-generation reproduction study in rats were
available for consideration during endpoint selection.

4.2.2	Evidence of Neurotoxicity  TC \l3 "4.2.2	Evidence of Neurotoxicity

Acute and subchronic neurotoxicity studies are not available for
ethaboxam.  Post-dose salivation was observed in a developmental rat
study (MRID 46488701) at 300 and 1000 mg/kg/day.  However, in another
developmental rat study (MRID 46387808) and a developmental rat
range-finding study (MRID 46387806), post-dose salivation was not
observed.  There were no other neurotoxic effects observed in the
available database.

4.2.3	Developmental Toxicity Studies  TC \l3 "4.2.3	Developmental
Toxicity Studies 

In two developmental toxicity studies in rats, there was evidence of  
SEQ CHAPTER \h \r 1 increased qualitative susceptibility.  In one study
(MRID 46387808), there were dose-related increases in water consumption
observed in all treated maternal animals.  Fur loss/alopecia was seen at
100 (7/25) and 300 mg/kg/day (8/25) compared to controls (1/25).  At 300
mg/kg/day, there were transient reductions in maternal body weight gain
and food consumption.  In fetuses, there were increased incidences of
abnormal liver lobation at 100 (4 fetuses/4 litters) and 300 mg/kg/day
(7 fetuses/5 litters) compared to controls (2 fetuses/2 litters).  In
another developmental rat study (MRID 46488701), increases in abnormal
liver lobation were also observed at 100 (5 fetuses/3 litters), 300 (5
fetuses/5 litters), and 1000 mg/kg/day (9 fetuses/7 litters), compared
to the control group (1 fetus/1 litter).  The abnormal liver lobation
was accompanied by thin diaphragm and protrusion of the liver at 1000
mg/kg/day.  The relevance of abnormal liver lobation without concurrent
diaphragm malformations is unclear; however, it cannot be dismissed in
the absence of historical control data.  There was no evidence of
increased quantitative susceptibility seen in the studies.

In the developmental toxicity study in rabbits, there was no evidence of
quantitative or qualitative susceptibility.  At 125 mg/kg/day, maternal
animals exhibited prolonged inappetence (GD 7-10), poor body condition
(GD 12-13), and greater body weight loss during GD 6-8 (-73 g vs. -16 g
for controls).  Decreased food consumption was observed at 75 (81%) and
125 mg/kg/day (70%) during GD 6-7.  There were no treatment-related
developmental effects seen in the study.

4.2.4	Reproductive Toxicity Study  TC \l3 "4.2.4	Reproductive Toxicity
Study 

In the 2-generation reproduction study, there was also evidence of   SEQ
CHAPTER \h \r 1 increased qualitative susceptibility.    SEQ CHAPTER \h
\r 1 Signs of parental toxicity included body weight changes, reduced
food consumption, organ weight changes, and microscopic changes in
reproductive tissues at 650 ppm (52.6/56.1 mg/kg/day).  In the F0 males,
there were decreases in body weight gain compared to control values
(10.5-22% (p<0.01), during weeks 1-3 of premating.  The F1 males had
reduced absolute body weight, significantly different from controls
during week 0 to week 6 of premating (p<0.01; decreases of 10.3-17.4%). 
Body weight gain was decreased during weeks 1-5 (p<0.01, reductions of
10.7-14.5%).  Among the F1 females, decreases in body weights were
significantly different from those of controls throughout premating
(p<0.01, decreases of 7.0-12.9%).  Food consumption was decreased for
the F1 males during weeks 2-5 and for the females during weeks 4, 6, 7,
and 9 (p<0.01; about 10-13%).  There were significant weight changes
observed for the following organs: reduced absolute adrenal weight of
the F0 males and females and the F1 females, reduction in the relative
adrenal weight of the F0 females, and increased absolute thyroid and
parathyroid weight in the F0 females;   SEQ CHAPTER \h \r 1 however,
necropsy revealed no macroscopic or microscopic correlates.

  SEQ CHAPTER \h \r 1 In regard to reproductive toxicity, the male
reproductive system is an apparent target for ethaboxam.  At 650 ppm,
reproductive toxicity in the F0 parental males was characterized by
impaired sperm motility (76% motile, compared with 85% for controls;
p<0.01) and an increased percentage of decapitate and abnormal sperm in
the vas deferens (13.3%, compared with 5.0% for controls; p<0.01). 
Microscopic examination revealed abnormal spermatogenic cells in the
epididymal ducts.  Reproductive parameters of the F0 females were not
affected by treatment with ethaboxam.  Also at 650 ppm, F1 parental
males exhibited reductions in the following: absolute weight of the
seminal vesicle plus coagulating gland (p<0.01, 13.1% reduction);
absolute weight of the epididymides (p<0.01, 16.7% reduction); relative
weight of the epididymides (p<0.05, 11.5% reduction); and absolute
weight of the testes (p<0.01, 14.1% reduction).  Microscopic examination
of the epididymides revealed a statistically significant reduction in
the absolute number of sperm and an increased percentage of abnormal
sperm.  In the testes, increased incidences of tubules showing a
depletion of all germ cells and of abnormal spermatids in occasional
tubules were observed.  F1 parental males had treatment-related
reproductive effects that included reductions in the percentage of males
mating (78%, compared with 100% of controls; p<0.05) and in the male
fertility index (52%, compared with 89% of controls; p<0.01) at 650 ppm.
 Necropsy revealed increased incidences of small epididymides and
testes, and microscopic examination revealed abnormal spermatogenic
cells in the epididymal ducts, reduced numbers of sperm in the
epididymides, depletion of germ cells and the presence of abnormal
spermatids in testicular tubules.  At 650 ppm, the F1 parental females
had a reduced number of implantation sites (p<0.05, 19.4% reduction). 
No other treatment-related effects on reproduction were apparent for the
F1 parental females.  The fertility index and conception rates of the F1
females were decreased to 70 and 73%, respectively.  These percentages
were not statistically significant when compared to the control values
of 89% for both parameters.  The effects on implantation sites,
fertility index and conception rate reflect the adverse,
treatment-related effects on the fertility of the parental males.

Offspring toxicity was manifested   SEQ CHAPTER \h \r 1 as a significant
decrease in the viability index of the F1 (80.9%; p< 0.05) and F2 pups
(77.5%; p<0.01) compared to controls (94.5% and 99.7%, respectively) at
650 ppm.  In addition, the F2 generation had significant reductions in
mean live litter size throughout lactation (p<0.05 or 0.01) and the live
birth index (84.8%) and was significantly lower (p<0.01) than that of
the control group (93.8%).  Decreased body weight was observed at 650
ppm in the F1 male and female pups from Day 14 to Day 21 of lactation
(p<0.01, decreases of 13.1-15.7%) and in the F2 male and female pups
from Day 14 to Day 28 (p<0.01, decreases of 12.4-18.2%).  Overall body
weight gain from Day 1-21 (F1 pups) and 1-28 (F2 pups) was also reduced.
 At 650 ppm, there was also a delay in sexual maturation of 2.4 days for
males and 2.1 days for females in F1 pups.

4.2.5	Additional Information from Literature Sources  TC \l3 "4.2.5
Additional Information from Literature Sources 

An internet search for ethaboxam results in a research article regarding
the effects of ethaboxam on growing fungi, as well as references to the
ongoing registration activities for ethaboxam in many European
countries.  Generally, documents related to those activities have not
been available to the review team due to their draft status.  The team
has been aided by OECD summary documents (MRID 46824211) in making an
informed assessment for this chemical.

4.2.6	Pre-and/or Postnatal Toxicity  TC \l3 "4.2.6	Pre-and/or Postnatal
Toxicity 

4.2.6.1	Determination of Susceptibility  TC \l4 "4.2.6.1	Determination
of Susceptibility 

The toxicology database is complete and adequate to assess questions of
increased qualitative and/or quantitative susceptibility.  There is
indication of increased qualitative susceptibility in the rat
developmental toxicity study and the 2-generation reproduction study. 
In the developmental study, the developmental NOAEL is 30 mg/kg/day,
based on increased incidences of abnormal liver lobation, seen at the
LOAEL of 100 mg/kg/day.  The maternal NOAEL is also 30 mg/kg/day, based
on less severe effects of increased water consumption and alopecia seen
at the same LOAEL of 100 mg/kg/day.  In the reproduction study, the
developmental NOAEL is 200 ppm (16.2/17.6), based on decreased body
weight and decreased viability of the F1 and F2  pups during lactation
at 650 ppm (52.6/56).  These effects are more severe than the parental
effects seen at 650 ppm which were decreased body weight gain of the F0
generation (males) and decreased absolute body weight of the F1 males
and females.

4.2.6.2	Degree of Concern Analysis and Residual Uncertainties for Pre
and/or Post-natal Susceptibility  TC \l4 "4.2.6.2	Degree of Concern
Analysis and Residual Uncertainties for Pre and/or Post-natal
Susceptibility 

Since there is evidence of increased qualitative susceptibility in the
rat developmental and reproduction studies, a Degree of Concern analysis
was performed to determine the level of concern and to identify any
residual uncertainties after establishing toxicity endpoints and
traditional uncertainty factors to be used in the risk assessment for
this chemical.  

In the rat developmental toxicity study, increased qualitative
susceptibility was evidenced as increased incidences of litters
containing fetuses with abnormal liver lobation, in the presence of
lesser maternal toxicity (increased water consumption and alopecia) at
650 ppm.  In the rat reproduction study, qualitative susceptibility was
observed as decreased pup weights and viability among F1 and F2
offspring during lactation, with maternal toxicity limited to decreased
body weight gain in F0 males and decreased body weight in F1 males and
females at 650 ppm.

Considering the overall toxicity profile and the doses and endpoints
selected for risk assessment for ethaboxam, the Degree of Concern for
effects observed in the studies is low based on the following: the
developmental/offspring effects observed in the studies are well
characterized and occur in the presence of maternal toxicity; a clear
NOAEL has been identified in both of the studies; and there are no
residual uncertainties for pre-and/or postnatal toxicity.  Furthermore,
the toxicology endpoint established for risk assessment is based on a
lower NOAEL, and thus considered protective of developmental/offspring
effects.

4.3	Recommendation for a Developmental Neurotoxicity Study  TC \l2 "4.3
Recommendation for a Developmental Neurotoxicity Study 

4.3.1	Evidence that supports requiring a Developmental Neurotoxicity
study  TC \l3 "4.3.1	Evidence that supports requiring a Developmental
Neurotoxicity study 

A developmental neurotoxicity study is not required at this time.

4.3.2	Evidence that supports not requiring a Developmental Neurotoxicity
study  TC \l3 "4.3.2	Evidence that supports not requiring a
Developmental Neurotoxicity study 

Post-dose salivation was observed in a developmental rat study (MRID
46488701) at 300 and 1000 mg/kg/day.  However, in another developmental
rat study (MRID 46387808) and a rat developmental range-finding study
(MRID 46387806), post-dose salivation was not observed.  There were no
other neurotoxic effects observed in the available database for
ethaboxam.  Therefore, a developmental neurotoxicity study is not
recommended at this time.

4.4	Hazard Identification and Toxicity Endpoint Selection  TC \l2 "4.4
Hazard Identification and Toxicity Endpoint Selection 

4.4.1	Acute Reference Dose (aRfD) - Females age 13-49  TC \l3 "4.4.1
Acute Reference Dose (aRfD) - Females age 13-49 

Study:		Developmental Toxicity-Rat

NOAEL:	30 mg/kg/day

LOAEL:	100 mg/kg/day

Uncertainty Factor: 100X (10X interspecies extrapolation, 10X
intraspecies variability)

Comments: A developmental toxicity study in the rat was used to select
the dose and endpoint for establishing the aRfD of 0.3 mg/kg/day.  The
developmental NOAEL of 30 mg/kg/day and the developmental LOAEL of 100
mg/kg/day was based on abnormal liver lobation.

  = 0.3 mg/kg/day

4.4.2	Acute Reference Dose (aRfD) - General Population  TC \l3 "4.4.2
Acute Reference Dose (aRfD) - General Population 

An acute reference dose for the general population has not been
established.  There were no appropriate studies that demonstrated
evidence of toxicity attributable to a single dose for this population.

4.4.3	Chronic Reference Dose (cRfD)  TC \l3 "4.4.3	Chronic Reference
Dose (cRfD) 

Study:		Combined Chronic/Carcinogenicity -Rat

NOAEL:	5.5 mg/kg/day

LOAEL:	16.4 mg/kg/day

Uncertainty Factor: 100X (10X interspecies extrapolation, 10X
intraspecies variability)

Comments: A combined chronic/carcinogenicity study in the rat was used
to select the dose and endpoint for establishing the cRfD of 0.055
mg/kg/day.  The NOAEL of 5.5 mg/kg/day and the LOAEL of 16.4 mg/kg/day
were based on effects observed in the male reproductive organs (testes,
epididymides, prostate, seminal vesicles).  This endpoint is protective
for toxic effects (decreased bodyweight/body weight gain) seen in
females at 45.5 mg/kg/day as well as for potential cancer effects to the
general population.

  = 0.055 mg/kg/day

4.4.4	Non-Dietary Exposure (All Durations)  TC \l3 "4.4.4	Non-Dietary
Exposure (All Durations) 

The petitioner is seeking tolerances for ethaboxam on grapes and its
processed commodities without a U.S. registration (i.e., “import
tolerances”).  The anticipated   SEQ CHAPTER \h \r 1 exposure route
for the US population is via the diet (food only); therefore,
residential and occupational exposure risk assessments for incidental
oral, dermal, and inhalation routes of exposure are not required.  At
such time that these pathways and routes of exposure become relevant,
HED will reexamine the toxicological database for ethaboxam and select
doses and endpoints for use in human health risk assessment as needed.

4.4.5	Classification of Carcinogenic Potential  TC \l3 "4.4.5
Classification of Carcinogenic Potential 

In accordance with EPA’s Final Guidelines for Carcinogen Risk
Assessment (March, 2005), the Cancer Assessment Review Committee (CARC)
classified ethaboxam as having “Suggestive Evidence of
Carcinogenicity,” and concluded that potential human risk to Leydig
cell tumorigenesis would not be expected at exposure levels that do not
cause tumors in rats.  The NOAEL and LOAEL selected for the cRfD is
based on reproductive toxicity observed at lower doses than the Leydig
cell tumor response.  Thus, the cRfD is protective of the cancer
effects.

This determination was based on the following weight-of-evidence
considerations:  

There was a treatment-related increase in only one tumor type (benign
Leydig cell tumors of the testes), only at the highest dose tested (650
ppm), and in only one species (Sprague Dawley rat).

There were no treatment-related tumors seen in female rats or male or
female mice.

Ethaboxam does not appear to be a gene mutagen; however, the clastogenic
potential of this compound cannot be determined at this time.  Although
the weight-of-evidence does not support a mutagenicity concern, the
Committee recommends that the in vitro cytogenetics assay be repeated to
clarify the earlier results.

It is well accepted that rat Leydig cell tumors are typically the result
of disruption of the endocrine and paracrine control of Leydig cell
function (testosterone production).  Thus, a nonlinear dose-response
approach should be used for non-mutagenic compounds causing Leydig
tumors by a hormonal mode of action.  Leydig cell tumor induction in
rats is of potential concern to humans unless the human relevance can be
ruled out by the mode of action (Clegg et al., 1997; Cook et al., 1999)

In a mode-of-action study in rats, investigating reproductive hormone
levels, exposure to ethaboxam resulted in a decrease in testosterone,
and a slight increase in luteinizing hormone  (LH). However, the data
presented did not support a consistent pattern of decreased testosterone
or increased LH and cannot be linked with increases in Leydig cell
adenomas.  In other rat studies, there were adverse reproductive effects
and marked testicular damage observed, effects indicative of a decrease
in testosterone and testicular toxicity.  The hormonal data and overall
male reproductive effects observed are suggestive of a
hormonally-mediated pathway; however, the data are inadequate to
delineate a sequence of key events leading to tumor formation.  Thus,
the available data are insufficient to characterize the human relevance
of this tumor finding.

 

4.4.6	Recommendation for Aggregate Exposure Risk Assessments  TC \l3
"4.4.6	Recommendation for Aggregate Exposure Risk Assessments 

As noted in Section 4.4.4, the only expected route of exposure to
ethaboxam is via the diet.  At such time as other routes of exposure to
ethaboxam may occur, the HED will reexamine the toxicological database
and determine for which routes, if any, aggregation is appropriate.

4.5	FQPA Safety Factor  TC \l2 "4.5	Special FQPA Safety Factor 

Based on the hazard database, HED recommends that the FQPA safety factor
be reduced to 1X because there were no/low concerns and no residual
uncertainties with regard to pre- and/or post-natal toxicity.  After
evaluating the toxicological and exposure data, the ethaboxam team
recommends the 1X safety factor based upon the following:

Although there was evidence of increased qualitative susceptibility
observed in the rat developmental and reproduction studies, there are no
residual uncertainties with regard to pre-and postnatal toxicity.  The
developmental/offspring effects observed in the studies are well
characterized (clear NOAEL established), and the dose selected for risk
assessment (NOAEL = 5.5 mg/kg/day) is protective of effects seen in both
studies.

The dietary exposure assessment is based on models and input parameters
designed to be protective of human health.

The proposal is for foreign use of ethaboxam; therefore residential and
occupational exposures in the U.S. are not anticipated.

Table 4.4.  Summary of Ethaboxam Toxicological Doses and Endpoints for
Use in Human Health Risk Assessments.

Exposure

Scenario	Dose Used in Risk Assessment, UF 	FQPA SF  and Level of Concern
for Risk Assessment	Study and Toxicological Effects

Acute Dietary

(General population including infants and children)	N/A	N/A	No
appropriate endpoint attributable to a single dose identified.

Acute Dietary

(Females 13-49 years of age)	NOAEL

   = 30 mg/kg

UF = 100

Acute RfD

   = 0.3 mg/kg	aPAD

   = aRfD/FQPA SF

   = 0.3 mg/kg	Developmental Toxicity-Rat

Developmental LOAEL (mg/kg/day): 100, based on abnormal liver lobation.

Chronic Dietary

(all populations)	NOAEL

   = 5.5 mg/kg/day 

UF = 100

Chronic RfD

   = 0.055 mg/kg/day	cPAD

   = cRfD/FQPA SF

   = 0.055 mg/kg/day	Combined Chronic/Carcinogenicity-Rat

LOAEL (mg/kg/day):  16.4, based on effects observed in the male
reproductive organs (testes, epididymides, prostate, seminal vesicles). 
  

Dermal 

All Durations	Risk assessments for these routes and durations are not
required at this time.  The requested action is for tolerance on
imported commodities.  There are no proposed uses that would result in
non-dietary exposures in the US.

Inhalation 

All Durations

	Cancer (all routes)	Classification:  “Suggestive Evidence of
Carcinogenicity.”  The chronic RfD is protective of potential cancer
effects.

4.6	Endocrine disruption  TC \l2 "4.6	Endocrine disruption 

EPA is required under the FFDCA, as amended by FQPA, to develop a
screening program to determine whether certain substances (including all
pesticide active and other ingredients) “may have an effect in humans
that is similar to an effect produced by a naturally occurring estrogen,
or other such endocrine effects as the Administrator may designate.” 
Following recommendations of its Endocrine Disruptor and Testing
Advisory Committee (EDSTAC), EPA determined that there was a scientific
basis for including, as part of the program, the androgen and thyroid
hormone systems, in addition to the estrogen hormone system.  EPA also
adopted EDSTAC’s recommendation that the Program include evaluations
of potential effects in wildlife.  For pesticide chemicals, EPA will use
FIFRA and, to the extent that effects in wildlife may help determine
whether a substance may have an effect in humans, FFDCA authority to
require the wildlife evaluations.  As the science develops and resources
allow, screening of additional hormone systems may be added to the
Endocrine Disruptor Screening Program (EDSP).

  SEQ CHAPTER \h \r 1 Based on histopathological (lesions in the testes,
epididymides, prostate, and seminal vesicles) and reproductive
(reductions in percentage mating and male fertility index) alterations
observed in several studies following oral administration of ethaboxam,
it is likely that ethaboxam may cause disruption in the endocrine
system.  

When additional appropriate screening and/or testing protocols being
considered under the Agency’s EDSP have been developed, ethaboxam may
be subjected to further screening and/or testing to better characterize
effects related to endocrine disruption.

5.0	Public Health Data  TC \l1 "5.0	Public Health Data 

No public health data were used in developing this risk assessment. 
Currently, ethaboxam does not have any registered uses in the U.S.

6.0	Exposure Characterization/Assessment  TC \l1 "6.0	Exposure
Characterization/Assessment 

6.1	Dietary Exposure/Risk Pathway  TC \l2 "6.1	Dietary Exposure/Risk
Pathway 

Acute and chronic dietary risk assessments were conducted using the
Dietary Exposure Evaluation Model (DEEM-FCID, Version 2.03), which uses
food consumption data from the USDA’s Continuing Surveys of Food
Intakes by Individuals (CSFII) from 1994-1996 and 1998.  The analyses
were performed to support a request for tolerances without a U.S.
registration on grapes (import tolerance).  Since there are no
established or requested uses of ethaboxam in the U.S. at this time,
residues in water were not included in these analyses.  Both the acute
and chronic dietary analyses are based on tolerance-level residues (6
ppm) and an assumption of 100% crop treated.  Additionally, empirical
evidence shows that residues of ethaboxam do not concentrate in grape
juice, raisins, or wine to levels that would exceed the grape tolerance;
therefore, residue estimates for these processed commodities were set at
the grape tolerance for the dietary assessment.  These are very
conservative assumptions regarding the level and frequency with which
residues of ethaboxam in/on grape commodities may occur.  Using
assumptions considered to be highly protective of human health, the
acute dietary risk estimate associated with the foreign use of ethaboxam
on grapes is approximately 4% of the acute population-adjusted dose
(aPAD) for females 13-49 years of age, which is the only population
subgroup relevant to the selected acute endpoint.  Other population
subgroups were not assessed with respect to acute exposure.  Based on
the same conservative assumptions, the chronic dietary risk estimates
associated with the foreign use of ethaboxam on grapes range from
approximately 2% of the chronic population-adjusted dose (cPAD; youth
13-19 years old) to approximately 31% of the cPAD (children 1-2 years
old).  Generally, HED is concerned when dietary risk estimates exceed
100% of the PAD; therefore, the acute and chronic dietary risk estimates
associated with the foreign use of ethaboxam on grapes are below HED’s
level of concern for all population subgroups.  HED notes that the acute
exposure estimate for females 13-49 years of age is the estimated
per-capita exposure, which is not reflective of exposures estimates for
grape “consumers” (i.e., person-days reflect 39% of user-days).  The
risk estimate for “consumers” is approximately 10% of the aPAD.

6.1.1	Residue Profile  TC \l3 "6.1.1	Residue Profile 

Both the acute and chronic assessments are based on tolerance-level
residues of 6 ppm in all grapes and grape commodities (i.e., 100% crop
treated).  The tolerance level was derived using the NAFTA tolerance/MRL
harmonization protocol and is based on a series of 24 field trials
conducted in Europe, South America, and Australia.  Empirical data
indicate that residues of ethaboxam in processed grape commodities (e.g,
juice, raisins, etc.) are not expected to exceed the tolerance level for
grapes; therefore, no concentration factors were used in these analyses.

There are a number of data deficiencies associated with the ethaboxam
residue chemistry database (see Section 10).  It is worth noting that
the proposed analytical enforcement method for ethaboxam has not been
radiovalidated, either explicitly or through commonality with methods
used to extract the residues of concern during conduct of the metabolism
studies.  In evaluating this petition, HED has inferred that the
analytical enforcement method will be successfully radiovalidated based
on the following reasoning:

Use patterns from the grape metabolism study and the field trials are
similar, and residues reported in the field trials are similar to or
greater than those reported for ethaboxam in the metabolism study.

Solubilities of ethaboxam in ethyl acetate (the extraction solvent used
in the metabolism study) and methanol are very similar (Table 2.2).  HED
is assuming that the solubility of ethaboxam in acetonitrile, which is
the primary solvent in the enforcement method, will be similar to its
solubility in methanol.

The acetonitrile/water mixture used to extract ethaboxam in the
enforcement method is likely to have equal or better miscibility with
the wet grape matrix than does ethyl acetate.

6.1.2	Acute and Chronic Dietary Exposure and Risk  TC \l3 "6.1.2	Acute
and Chronic Dietary Exposure and Risk 

Table 6.1.  Summary of Dietary Exposure and Risk Estimates for
Ethaboxam.  aPAD = 0.3 mg/kg/day for females 13-49 years of age.  cPAD =
0.055 mg/kg/day for all population subgroups.

Population Subgroup	Acute Dietary

(95th Percentile)	

Chronic Dietary	

Cancer

	Exposure (mg/kg/day)	% aPAD	Exposure

(mg/kg/day)	% cPAD	Exposure

(mg/kg/day)	Risk

General U.S. Pop.	N/A	N/A	0.003055	6	Not Required

All Infants (< 1 year)

	0.005122	9	N/A	N/A

Children (1-2 years)

	0.017131	31

Children (3-5 years)

	0.010445	19

Children (6-12 years)

	0.004007	7

Youth (13-19 years)

	0.001326	2

Adults (20-49 years)

	0.001882	3

Adults (50+ years)

	0.002189	4

Females (13-49 years)	0.013035	4	0.002036	4

6.2	Water Exposure/Risk Pathway  TC \l2 "6.2	Water Exposure/Risk Pathway

The petitioner has not requested a registration for use of ethaboxam in
the U.S.  Therefore, an exposure assessment that includes ethaboxam
residues in drinking water is not warranted at this time.

6.3	Residential (Non-Occupational) Exposure/Risk Pathway  TC \l2 "6.3
Residential (Non-Occupational) Exposure/Risk Pathway 

The petitioner has not requested a registration for use of ethaboxam in
the U.S. and the only significant pathway of exposure is via the diet. 
Risk assessments for residential exposure to ethaboxam are not warranted
at this time.

7.0	Aggregate Risk Assessments and Risk Characterization  TC \l1 "7.0
Aggregate Risk Assessments and Risk Characterization 

The petitioner has not requested a registration for use of ethaboxam in
the U.S. and the only significant pathway of exposure is via the diet. 
Therefore, aggregate risk estimates are equivalent to the dietary risk
estimates discussed in Section 6.

8.0	Cumulative Risk Characterization/Assessment  TC \l1 "8.0	Cumulative
Risk Characterization/Assessment 

Unlike other pesticides for which EPA has followed a cumulative risk
approach based on a common mechanism of toxicity, EPA has not made a
common mechanism of toxicity finding as to ethaboxam and any other
substances, and ethaboxam does not appear to produce a toxic metabolite
produced by other substances. For the purposes of this tolerance action,
therefore, EPA has not assumed that ethaboxam has a common mechanism of
toxicity with other substances.  For information regarding EPA’s
efforts to determine which chemicals have a common mechanism of toxicity
and to evaluate the cumulative effects of such chemicals, see the policy
statements released by EPA’s Office of Pesticide 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 Pathway  TC \l1 "9.0	Occupational
Exposure/Risk Pathway 

The petitioner has not requested a registration for use of ethaboxam in
the U.S.  As such, there are no scenarios in which occupational exposure
to ethaboxam by U.S. workers will occur.

10.0	Data Needs and Label Requirements  TC \l1 "10.0	Data Needs and
Label Requirements 

10.1	Toxicology  TC \l2 "10.1	Toxicology 

The Cancer Assessment Review Committee recommends that the in vitro
cytogenetics assay be repeated to clarify the earlier results.

10.2	Residue Chemistry  TC \l2 "10.2	Residue Chemistry 

The following issues should be resolved prior to the establishment of
tolerances for residues of ethaboxam in/on grapes:

860.1200 Directions for Use

The petitioner should submit labels for ethaboxam end-use products from
all countries in which registration of ethaboxam exists or is being
sought.  The labels should be accompanied by English translations as
needed.

860.1550 Proposed Tolerances

  SEQ CHAPTER \h \r 1 

The petitioner needs to submit a revised Section F to specify a
tolerance level of 6.0 ppm for grapes without a U.S. registration.  HED
has determined that ethaboxam tolerances for grape juice and raisins are
not needed because residues expected in these processed commodities, as
a result of the proposed use, will be covered by the assessed RAC
tolerance.  The petitioner needs to delete tolerances for grape juice,
raisins, and wine in a revised Section F.  The Agency does not set
pesticide tolerances in wine because wine is under the purview of the
Bureau of Alcohol, Tobacco, and Firearms.  The chemical name for
ethaboxam in the revised Section F should be the one provided by the
Chemical Abstracts Service: 
N-(cyano-2-thienylmethyl)-4-ethyl-2-(ethylamino)-5-thiazolecarboxamide

Prior to the establishment of any other tolerances for ethaboxam or the
granting of any U.S. registrations for this chemical, the following
issues should be resolved:

860.1340 Residue Analytical Methods

Before the proposed LC/MS method can be considered adequate for
tolerance enforcement, a confirmatory method (or an interference study)
is required since the method monitors only a single ion.    SEQ CHAPTER
\h \r 1 HED normally requests an interference study for a GC/MS or LC/MS
method if less than three separate and unique ions are analyzed.

The LC/MS method needs to be radiovalidated using samples from the plant
metabolism studies in order to determine whether the method is able to
extract incurred residues of concern.

860.1380 Storage Stability

When the ongoing storage stability study is completed, the final report
should include a complete description of the fortification procedures,
the storage conditions of all samples (i.e., including control and fresh
fortification samples and the point at which fresh fortification samples
were fortified), and the actual dates of fortification, extraction and
analysis of all samples.  In addition, because HED is unable to
determine the maximum storage intervals of grape samples collected from
trials described in MRIDs 46378514 and 46387801, the petitioner should
provide information pertaining to dates of sample harvest, extraction,
and analysis to determine the:  (1) actual sample storage intervals; and
(2) adequacy of available storage stability data.

10.3	Occupational and Residential Exposure  TC \l2 "10.3	Occupational
and Residential Exposure 

None

Table 10.  Tolerance Summary for Ethaboxam.

Commodity	Proposed Tolerance (ppm)	Recommended Tolerance (ppm)	Comments/

Correct Commodity Definition

Grapes	3.5	6.0	Grape

Grape Juice	3.3	Not needed	Covered by the RAC

Raisins	5.8	Not needed	Covered by the RAC

Wine	2.5	Not needed	Not under the purview of EPA

References  TC \l1 "References: 

Ethaboxam.  Petition for the Establishment of Tolerances without a U.S.
Registration on Grape and its Processed Commodities.  Summary of
Analytical Chemistry and Residue Data.  PP# 4E6863.  DP Number 313733. 
M. Doherty.  04/27/06.

Ethaboxam: Acute and Chronic Dietary Exposure Assessments for the
Establishment of Tolerances without a U.S. Registration on Grapes.  DP
Number 328148.  M. Doherty.  04/27/06.

MRID 46824211.  EU Plant Protection Product Dossier According to
91/414/EEE Annex II/IIIA – Active Substances Tier 3 Overall Assessment
and Conclusions – Document N.  September 2003.  82 p.Appendices  TC
\l1 "Appendices 

1.0	TOXICOLOGY DATA REQUIREMENTS 

  SEQ CHAPTER \h \r 1 The requirements (40 CFR 158.340) for food use
(tolerances on imported commodities only) of ethaboxam are in Appendix
Table 1.  Use of the new guideline numbers does not imply that the new
(1998) guideline protocols were used.

Appendix Table 1.  Toxicology Data Requirements

Test	Technical

	Required	Satisfied

870.1100	Acute Oral Toxicity	

870.1200	Acute Dermal Toxicity	

870.1300	Acute Inhalation Toxicity	

870.2400	Primary Eye Irritation	

870.2500	Primary Dermal Irritation	

870.2600	Dermal Sensitization		yes

no

no

no

no

no	yes

-

-

-

-

-

870.3100	Oral Subchronic (rodent)	

870.3150	Oral Subchronic (nonrodent)	

870.3200	21-Day Dermal	

870.3250	90-Day Dermal	

870.3465	90-Day Inhalation		yes

yes

no

no

no	yes

yes

-

-

-

870.3700a	Developmental Toxicity (rodent)	

870.3700b	Developmental Toxicity (nonrodent)	

870.3800	Reproduction		yes

yes

yes	yes

yes

yes

870.4100a	Chronic Toxicity (rodent)	

870.4100b	Chronic Toxicity (nonrodent)	

870.4200a	Oncogenicity (rat)	

870.4200b	Oncogenicity (mouse)	

870.4300	Chronic/Oncogenicity		yes

yes

yes

yes

yes	yes

yes

yes

yes

yes

870.5100	Mutagenicity—Gene Mutation - bacterial	

870.5300	Mutagenicity—Gene Mutation - mammalian	

870.5375	Mutagenicity—Structural Chromosomal Aberrations

870.5395	Mutagenicity—Erythrocyte Micronucleus-mammalian	yes

yes

yes

yes	yes

yes

no

yes

870.6100a	Acute Delayed Neurotoxicity (hen)	

870.6100b	90-Day Neurotoxicity (hen)	

870.6200a	Acute Neurotoxicity Screening Battery (rat)	

870.6200b	90 Day Neurotoxicity Screening Battery (rat)	

870.6300	Developmental Neurotoxicity		no

no

no

no

no	-

-

-

-

-

870.7485	General Metabolism	

870.7600	Dermal Penetration		yes

no	yes

-

  SEQ CHAPTER \h \r 1 2.0	TOXICOLOGY STUDIES

Oral Subchronic Toxicity Study-Rat; OPPTS 870.3100; OECD 408

EXECUTIVE SUMMARY:   SEQ CHAPTER \h \r 1 In a 13-week oral toxicity
study (MRID 46387805), Ethaboxam (LGC-30473, 99.2% a.i.) was
administered to 10 Crl:CD BR rats/sex/dose in the diet at concentrations
of 0, 200, 650, or 2000 ppm (approximately equivalent to 0, 16.3, 49.7,
and 154 mg/kg/day males, and 0, 17.9, 58.0, and 164 mg/kg/day females).

By study end, 7/10 high-dose female rats had developed alopecia.  No
alopecia was found in the control group or other treatment groups.  The
body weight of high-dose male and female groups was significantly
decreased within one week of treatment and remained decreased throughout
the study.  Total body weight gain of the high-dose male and female rats
for the study was ~67% of their respective control groups.  This was
accompanied by an ~20% decrease in food consumption.

No significant treatment-related effects were found on mortality,
hematology, opthalmoscopic, or urinalysis parameters.  An increased
relative liver weight (to body weight) of high-dose male and female rats
and centrilobular hypertrophy was found in most high-dose male and
female rats.  Fine vacuolation of the adrenal zona glomerulos observed
in 3/10 high-dose males and 8/10 high-dose females was not observed in
any other group. 

	Severe testicular atrophy and interstitial cell hyperplasia were noted
in most high-dose rats.  There were no spermatozoa found in the
epididymides of high-dose rats and abnormal spermatogenic cells were
found in some of the ducts.  In rats at 650 ppm, abnormal spermatids
were found in the testes of 4/10 rats, and abnormal spermatogenic cells
were found in the epididymal ducts of 6/10 rats.  	

The LOAEL for males is 650 ppm (49.7 mg/kg/day) based on
testicular/epididymal effects (abnormal spermatids in the testes,
abnormal spermatogenic cells in epididymal ducts).  The LOAEL for
females is 2000 ppm (164 mg/kg/day) based on fine vacuolation of the
adrenal zona glomerulosa, and lower body weights. The NOAELS for males
and females are 200 ppm (16.3 mg/kg/day) and 650 ppm (58 mg/kg/day),
respectively.

The 13-week oral toxicity study in the rat is Acceptable/Guideline and
satisfies the guideline requirement (OPPTS 870.3100; OECD 408) for a
90-day oral toxicity study in rats. 

Oral Subchronic Toxicity Study-Mouse; OPPTS 870.3100; OECD 408

EXECUTIVE SUMMARY:   SEQ CHAPTER \h \r 1 In a 13-week oral toxicity
study (MRID 46387802), Ethaboxam (LGC-30473, 99.0% a.i.) was
administered to groups of 10 mice/sex at concentrations of 0, 200, 450,
1000, or 2500 ppm in the diet (approximately equivalent to 0, 33, 74,
163, or 405 mg/kg bw/day in males and 0, 41, 93, 195, or 483 mg/kg
bw/day in females).  

No clinical signs were observed.  One high-dose male died during week 8.
 No additional deaths were recorded during the study.  Final body
weights in males in the control through high-dose group (47, 44, 46, 42,
and 44 g) and in females in the control through high-dose group (34, 36,
33, 34, and 33 g) did not show a clear dose-response effect; mean male
body weights in the 1000 and 2500 ppm groups were 89 and 94% of the
control group weight, respectively.  The overall mean body weight gains
were significantly decreased in males at 1000 ppm (9.5 ± 2.7 g) and
2500 ppm (9.6 ± 2.0 g) compared to the control group (13.8 ± 5.8 g). 
The mean body weight gains of treated females were significantly higher
than that of the control over the first 4 weeks of the study, but
increases were not dose-related.  The weight gain in females at 450,
1000, and 2500 ppm  over treatment weeks 4-13 were slightly less than
that of the control group, but the differences were not statistically
significant and did not show a dose relationship.  The overall weight
gains in treated females were not significantly different from the
control group at study termination.  Treated mice tended to eat less
food than the control groups, but the differences in males were not
statistically significant and did not show a clear dose effect.  Females
at 2500 ppm ate significantly less food than the control group
throughout the study.  The overall food efficiency (g weight gained/g
food consumed X 100) calculated by the reviewer was decreased in males
at 1000 ppm (1.63) and 2500 ppm (1.62) compared to the control group
(2.25).  Food efficiency in females did not show any treatment-related
decrease.

Hematology, clinical chemistry, and urinalysis parameters were not
measured in the study.

The relative (adjusted for body weight) mean liver weights in males were
significantly increased by 8.6% at 450 ppm (p<0.05), by 12.7% at 1000
ppm (p<0.01), and by 35.3% at 2500 ppm (p<0.01) compared to the control
group.  The relative liver weights in females were increased
significantly by 12.0% at 1000 ppm (p<0.05) and by 42.1% at 2500 ppm
(p<0.01).

The incidence of liver centrilobular hepatocyte hypertrophy was
increased in males at 450 ppm (50%, p <0.05), 1000 ppm (80%, p<0.01),
and 2500 ppm (90%, p<0.01) compared to the control group (0%).  The
centrilobular hepatocyte hypertrophy incidence in females was increased
at 1000 ppm (40%, p<0.01), and at 2500 ppm (80%, p<0.01) compared to the
controls (0%). There were no other treatment-related microscopic
findings. The increase in liver weight and centrilobular hypertrophy are
considered adaptive responses in the absence of corroborating liver
findings.

   

The LOAELs for males and females are not determined and the NOAEL for
both sexes is 2500 ppm (405 mg/kg/day in males and 483 mg/kg/day in
males).    

The 90-day oral toxicity study in mice is Acceptable/Guideline and
satisfies the guideline requirement (870.3100; OECD 408) for a 90-day
oral toxicity study in mice

Oral Subchronic Toxicity Study-Dog; OPPTS 870.3150; OECD 409

EXECUTIVE SUMMARY:   SEQ CHAPTER \h \r 1 In a 90-day oral toxicity study
(MRID 46387803), Ethaboxam 

(LGC-30473, 98% a.i.) was administered to four beagle dogs/sex/dose in a
capsule daily at concentrations of 0, 15, 40, or 100 mg/kg/day.

There were no differences between the controls and treated groups in
food and water consumption, ophthalmology, and urinalysis parameters
that were considered toxicologically significant.  There were three
premature sacrifices (40 and 100 mg/kg/day groups) done for humane
reasons, one male dog had meningitis and two females suffered from an
anemic condition at necropsy.  There were no clinical signs of toxicity
noted for the surviving beagle dogs.

Treated dogs showed increases in absolute and relative (adjusted for
body weight) liver weights in the 40 and 100 mg/kg/day groups of both
sexes.  These changes were associated with the microscopic finding of
hepatocyte hypertrophy.  A slight involution/atrophy of the thymus and
extramedullary hematopoiesis in the spleen were detected in one dog of
each sex in the 100 mg/kg/day group and one female in the 40 mg/kg/day
group.

At termination, the treated male dogs had body weights comparable with
controls while there was a 10 to 15% reduction in body weight of the
female dogs.  The body weight gain of the females was correspondingly
reduced in all groups (62%, 52% and 41% of control levels in the 15, 40,
and 100 mg/kg/day groups, respectively). 

The LOAEL for females is 15 mg/kg/day based on reduced body weight and
body weight gain and the LOAEL for males is not determined.  The NOAEL
for males is 100 mg/kg/day and the NOAEL for females is not determined.

The 90-day oral toxicity study in dogs is Acceptable/Guideline and
satisfies the guideline requirement (OPPTS 870.3150; OECD 409) for a
90-day oral toxicity study in dogs.

Developmental Toxicity Study-Rat; OPPTS 870.3700a; OECD 414

		

EXECUTIVE SUMMARY:   SEQ CHAPTER \h \r 1    SEQ CHAPTER \h \r 1 In a
developmental toxicity study (MRID 46387808), Ethaboxam (LGC-30473,
97.5% a.i.) was administered to 25 female Crl:CD® BR VAF/Plus rats/dose
by oral gavage at dose levels of 0, 10, 30, 100, or 300  mg/kg bw/day
from gestation day (GD) 6 through 19, inclusive.  The vehicle was 1%
methylcellulose.  On GD 20, all females were killed by CO2 asphyxiation
and subjected to macroscopic post mortem examination.  Half of the
fetuses in each litter were preserved in Bouin’s solution for
subsequent free-hand sectioning to discover visceral abnormalities; the
remainder were fixed and stained for skeletal examination.

Fur loss/alopecia was observed on seven animals at 100 mg/kg/day and
eight animals at 300 mg/kg/day compared with one control animal. 
Absolute body weight was similar between the treated and control groups
throughout the study.  Treatment at 300 mg/kg/day was associated with
transient reductions in maternal body weight gain (GD 6-8: control: 9.2
g; 300 mg/kg/day: 4.1 g; GD 6-12: control: 41.3 g; 300 mg/kg/day: 35.3
g) and food intake (91% of control for GD 6-7).  Dose-related increased
water consumption was observed for all treated groups: at 300 mg/kg/day,
water consumption was up to 145% of control for 13 treatment days; at
100 mg/kg/day, water consumption was up to 124% of control for 8
treatment days; at 30 mg/kg/day,  water consumption was up to 124% of
control for 7 treatment days; and at 10 mg/kg/day, water consumption was
up to 118% of control for 3 treatment days.  Maternal necropsy was
unremarkable.

The maternal toxicity LOAEL is 100 mg/kg bw/day based on hair loss and
increased water consumption.  The maternal NOAEL is 30 mg/kg bw/day.

The number of fetuses (litters) examined was 232 (18), 311(24), 268(23),
272(24), and 287(23) in the 0, 10, 30, 100, and 300 mg/kg/day groups,
respectively.  Pre-implantation loss for the 100- and 300-mg/kg/day
groups was significantly greater than that of the control (13.5% and
11.6%, respectively, compared to 7.9% for the controls), but no effects
were observed on the mean number of implantations or mean number of live
fetuses.  The distribution of dams showing total resorption (1 control
and 2 at 30 mg/kg/day) did not suggest a relationship to treatment.  The
fetal sex ratio was unaffected by treatment.  Fetal body weight was
similar between the treated and control groups.

No treatment-related external or skeletal malformations/variations were
observed.  The incidence of litters containing fetuses with abnormal
liver lobation was higher than that of the control group at 100 and 300
mg/kg/day.  The number of fetuses (litters) with abnormal liver lobation
was 2(2), 3(2), 2(2), 4(4), and 7(5), in the 0, 10, 30, 100, and 300
mg/kg/day groups, respectively.  Increased incidences of abnormal liver
lobation, and thin diaphragm with liver protrusion were observed in
another developmental study (MRID 46488701) at 100, 300, and 1000 mg/kg
bw/day.   

The developmental toxicity LOAEL is 100 mg/kg/day based on abnormal
liver lobation.  The developmental toxicity NOAEL is 30 mg/kg bw/day.

The developmental toxicity study in the rat is classified
Acceptable/Guideline and satisfies the guideline requirement (OPPTS
870.3700; OECD 414) for a developmental toxicity study in the rat.

Developmental Toxicity Study-Rabbit; OPPTS 870.3700b; OECD 414

EXECUTIVE SUMMARY:   SEQ CHAPTER \h \r 1 In a developmental toxicity
study (MRID 46490401), Ethaboxam (LGC-30473, 97.5% a.i.) was
administered to 20 mated female New Zealand White rabbits/dose by gavage
in 1% methylcellulose at dose levels of 0, 25, 75, or 125 mg/kg bw/day
on gestation days (GD) 6 through 28, inclusive.  On GD 29, all surviving
does were sacrificed and necropsied.  Gravid uterine weight, corpora
lutea count, the number and position of live fetuses, the number of
early and late embryonic/fetal deaths, and number of aborted fetuses
were recorded.  All live fetuses were weighed, sexed, and subjected to
external, visceral, and skeletal examinations, including evaluation of
the brain via a slice taken through the line of the frontoparietal
suture.

Two high-dose females were sacrificed (one each on GDs 15 and 16) after
exhibiting prolonged inappetence beginning on GD 7-10 and poor body
condition beginning on GD 12-13.  High-dose does had a greater body
weight loss during GD 6-8 (-73 g vs. -16 g for controls; N.S., not
statistically significant), followed by compensatory increased body
weight gain during GD 8-17 (145% of controls).  Cumulative body weight
gain over the dosing interval was similar to that of controls.  Mid- and
high-dose does had decreased mean daily food consumption during GD 6-7
(81% and 70%; p<0.05 and p<0.01, respectively).  There were no
treatment-related effects on absolute body weight, corrected (for gravid
uterus) body weight, or gross pathology. These effects are consistent
with those observed in the range-finding study (see appendix) after
exposure to LGC-30473.  In the study, decreased food consumption was
seen in treated groups compared to controls, as well as inappetence,
body weight loss, and poor physical condition at 300 mg/kg/day.  

The maternal LOAEL is 125 mg/kg bw/day, based on inappetence,
decreased food consumption, and body weight loss.  The maternal NOAEL is
75 mg/kg bw/day.

There were no treatment-related effects on live litter size, early or
late embryonic/fetal deaths, or postimplantation loss.  There were no
treatment-related effects on fetal sex ratios or the mean fetal weight
for the combined sexes.  The total numbers of fetuses (and litters)
evaluated in the control, low-, mid-, and high-dose groups were 172
(19), 133 (17), 170 (20), and 137 (16), respectively, and there were a
total of 5 (4), 8 (7), 4 (3), and 4 (4) fetuses (litters) with
malformations in these same respective groups.  

The developmental LOAEL is not determined, and the developmental NOAEL
is 125 mg/kg bw/day.

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

Reproduction and Fertility Effects-Rat; OPPTS 870.3800; OECD 416

		

EXECUTIVE SUMMARY:   SEQ CHAPTER \h \r 1  In a two-generation
reproduction study (MRID 46387804), Ethaboxam (LGC-30473, 99.0% a.i.)
was administered to thirty-two Crl:CD®BR (Sprague Dawley origin)
rats/sex/dose in the diet at concentrations of 0, 65, 200, or 650 ppm. 
Premating doses for the F0-generation parental animals were 0, 5.2,
16.2, or 52.6 mg/kg bw/day for males, and 0, 5.7, 17.6, or 56.1 mg/kg
bw/day for females.  One litter was produced in each generation. 
Parental animals of both generations were administered test or control
diets for 10 weeks prior to mating, and throughout mating, gestation,
and lactation.

The adverse effects on the two generations of parental rats and their
offspring occurred only at 650 ppm.  There were no treatment-related
effects at 65 or 200 ppm and the results reported in this summary are
for the high-dose groups and the controls, only.

Signs of parental systemic toxicity included body weight changes,
reduced food consumption, organ weight changes, and microscopic changes
in reproductive tissues.  The F0 males showed no significant changes in
absolute body weight, but their body weight gain was decreased, in
comparison to control values, by 10.5-22% (p<0.01) during weeks 1-3 of
premating.  Body weight, weight gain, and food consumption of the
treated F0 females were comparable to control values throughout
premating.  The F1 males had reduced absolute body weight, significantly
different from controls during week 0 to week 6 of premating (p<0.01;
decreases of 10.3-17.4%).  Body weight gain was decreased during weeks
1-5 (p<0.01, reductions of 10.7-14.5%).  Among the F1 females, decreases
in body weight were significantly different from controls throughout
premating (p<0.01, decreases of 7.0-12.9%).  Food consumption was
decreased for the F1 males during weeks 2-5 and for the females during
weeks 4, 6, 7, and 9 (p<0.01; about 10-13%).  

Significant weight changes were observed for the following organs:
reduced absolute adrenal weight of the F0 males and females and the F1
females, reduction in the adrenal to body weight ratio of the F0
females, and increased absolute thyroid and parathyroid weight in the F0
females; however, necropsy revealed no macroscopic or microscopic
correlates.

The parental toxicity LOAEL for males and females is 650 ppm
(approximately 52.6 mg/kg/day in males and 56.1 mg/kg/day for females),
based on decreased premating body weight gain of the F0-generation males
and decreased premating absolute body weight of the F1 males and
females.  The parental toxicity NOAEL is 200 ppm for males and females
(approximately 16.2 mg/kg/day in males and 17.6 mg/kg/day in females).

With regard to offspring viability, the only significant (p<0.05)
finding for the F1 pups was a viability index of 80.9% compared with
94.5% for the controls.  For the more severely affected F2 generation,
significant reductions were observed in mean live litter size throughout
lactation (p<0.05 or 0.01).  The live birth index of 84.8% and viability
index of 77.5% were significantly lower (p<0.01 for both) than the
control values of 93.8% and 99.7%, respectively.  Decreased body weight
was observed at 650 ppm in the F1 male and female pups from day 14 to
day 21 of lactation (p<0.01, decreases of 13.1-15.7%) and in the F2 male
and female pups from day 14 to day 28 (p<0.01, decreases of 12.4-18.2%).
 Overall body weight gain from day 1-21 (F1 pups) and 1-28 (F2 pups) was
also reduced.  No clinical signs were observed during lactation of
either generation of pups and no treatment-related systemic effects were
observed in either generation at 65 or 200 ppm.  Lower body weight of
the F1 pups at 650 ppm resulted in a delay in sexual maturation of 2.4
days for males and 2.1 days for females.

The offspring toxicity LOAEL for males and females is 650 ppm
(approximately equivalent to 52.6 mg/kg/day in males and 56.1 mg/kg/day
in females), based on decreased body weight and decreased viability of
the F1 and F2 males and females during lactation.  The offspring
toxicity NOAEL for male and female rats is 200 ppm (approximately 16.2
mg/kg/day in males and 17.6 mg/kg/day in females).



In addition to body weight, the male reproductive system is the apparent
target for the toxicity of LGC-30473.  The F1 males exhibited reductions
in the following: absolute weight of the seminal vesicle plus
coagulating gland (p<0.01, 13.1% reduction); absolute weight of the
epididymides (p<0.01, 16.7% reduction); relative weight of the
epididymides (p<0.05, 11.5% reduction); and absolute weight of the
testes (p<0.01, 14.1% reduction).  Microscopic examination of the
epididymides revealed a statistically significant reduction in the
number of sperm and an increase in the number (percentage) of abnormal
sperm.  In the testes, increased incidences of tubules showing a
depletion of all germ cells and of abnormal spermatids in occasional
tubules were observed.

Reproductive toxicity in the F0 parental males was also characterized by
impaired sperm motility (76% motile, compared with 85% for controls;
p<0.01) and an increased percentage of decapitate and abnormal sperm in
the vas deferens (13.3%, compared with 5.0% for controls; p<0.01). 
Microscopic examination revealed abnormal spermatogenic cells in the
epididymal ducts.  Reproductive parameters of the F0 females, including
numbers mated and pregnant, number of live litters born, conception
rate, fertility index, and gestation index, were not affected by
treatment with LCG-30473.

The males of the F1 parental generation had treatment-related
reproductive effects that included reductions in the percentage of males
mating (78%, compared with 100% of controls; p<0.05) and in the male
fertility index (52%, compared with 89% of controls; p<0.01).  Necropsy
revealed increased incidences of small epididymides and testes, and
microscopic examination revealed abnormal spermatogenic cells in the
epididymal ducts, reduced numbers of sperm in the epididymides,
depletion of germ cells and the presence of abnormal spermatids in
testicular tubules.

The F1 parental females had a reduced number of implantation sites
(p<0.05, 19.4% reduction). No other treatment-related effects on
reproduction were apparent for the F1 parental females.  The fertility
index and conception rates of the F1 females were decreased to 70 and
73%, respectively.  These percentages were not statistically significant
when compared to the control values of 89% for both parameters.  The
effects on implantation sites, fertility index and conception rate
reflect the adverse, treatment-related effects on the fertility of the
parental males.

The reproductive toxicity LOAEL in males is 650 ppm (52.6 mg/kg/day),
based on testicular lesions and reduced fertility in the F1 males, the
reproductive LOAEL in females was not determined.  The reproductive
toxicity NOAEL is 200 ppm (16.2 mg/kg/day) for male rats and 650 ppm
(56.1 mg/kg/day) for females.

This study is Acceptable/Guideline and satisfies the guideline
requirement (OPPTS 870.3800; OECD 416) for a two-generation reproductive
study in rats.

Oral Chronic Toxicity study -Dog; OPPTS 870.4100; OECD 452

		

EXECUTIVE SUMMARY:   SEQ CHAPTER \h \r 1 In a 52-week oral chronic
toxicity study (MRID 46387809), Ethaboxam (LGC-30473, 99 % a.i.) was
administered to four beagle dogs/sex/dose in capsules at concentrations
of 0, 5, 10, or 30 mg/kg/day.

There were no differences between the controls and the treated groups in
food and water consumption, ophthalmology, hematology, clinical
chemistry, or urinalysis.  There were no treatment related mortalities
and no treatment related clinical signs of toxicity.  One male dog in
the 10 mg/kg/day group developed bilateral inguinal hernias unrelated to
treatment and was sacrificed at Week 41.

10 mg/kg/day.

Total body weight gain was decreased to 33% of control in the males of
the 5 and 30 mg/kg/day groups, respectively, and 53% and 32% of controls
in the 5, and 30 mg/kg/day female groups, respectively.  The decreases
in total body weight gain were not considered adverse since food
consumption was unaffected by treatment, and total body weight of the
treated dogs was not decreased. 

The NOAEL is 30 mg/kg/day for male and female beagle dogs, and the LOAEL
is not determined.

This chronic study is Acceptable/Non-guideline and does not satisfy the
guideline requirement [OPPTS 870.4100, OECD 452] for a chronic oral
study in the dog.  A LOAEL was not established in the study and dogs
were not tested up to the limit dose.  A higher dose could have been
tolerated. 

  SEQ CHAPTER \h \r 1 Combined Chronic Toxicity/Carcinogenicity Feeding
– Rat; OPPTS 870.4300; OECD 453

EXECUTIVE SUMMARY:   SEQ CHAPTER \h \r 1 In a combined chronic
toxicity/carcinogenicity study (MRID 46387811), Ethaboxam (LGC-30473,
99% a.i.) was administered in the diet to groups of 60 male and 60
female Crl:CD rats at concentrations of 0, 100, 300, or 650 ppm
(approximately 0, 5.5, 16.4, or 35.8 mg/kg/day in males and 0, 7, 21, or
45.5 mg/kg/day, in females) for 104 weeks (carcinogenicity phase). 
Groups of 20 males and 20 females were administered the same diets and
sacrificed at 52 weeks (chronic toxicity phase).

No treatment-related clinical signs, effects on survival/mortality,
abnormalities of the eyes (ophthalmoscopic examination), hematologic
changes, or urinalysis changes were observed in any group of male or
female rats receiving any dose of the test material.  No
treatment-related neurological effects were observed during the
functional observational battery (FOB).  Statistically significant
clinical chemistry changes were observed in male and female rats, but
they were not considered adverse in the absence of corresponding
histopathological lesions.  Body weight gain was significantly decreased
by 11% and 20% in mid- and high-dose males, respectively, and by 10%,
10%, and 17% in low-, mid-, and high-dose group females, respectively,
during week 1 of the study; otherwise, there were no other
treatment-related effects observed on body weight or body weight gain in
males or  low- or mid-dose females.  High-dose group females weighed up
to 12% less than controls throughout the remaining weeks of the study
and gained 10% (p≤0.01) less weight than controls during the first
year, 93% less during the second year, and 16% (p≤0.05) less over the
entire study.  Food consumption was within 8% of the control level
throughout the study and food efficiency was similar to that of controls
over the first 14 weeks of the study.

≤0.01) in mid- and high-dose males, respectively, compared with 9/59
in controls, and the incidence of epididymides with reduced number of
spermatozoa was 18/59 (p≤0.05) in high-dose males compared with 8/59
in controls.  Other epididymal lesions found at significantly increased
incidences in high-dose males included abnormal spermatogenic cells and
epithelial vacuolation in the epididymal duct and intraepithelial
lumina.  Microscopic lesions were also observed in the seminal vesicle
and prostate.  The incidence of seminal vesicle atrophy and acinar
atrophy in the prostate was increased, but not significantly, in
high-dose males and reduced colloid in the prostate was significantly
increased in mid- and high group males.  The non-neoplastic findings in
male rats suggest that LGC-30473 is a potential endocrine disruptor
affecting the male reproductive organs.

In female rats, no treatment-related lesions were observed at 52 weeks
or in the carcinogenicity phase of the study.  The incidences of lesions
that were significantly increased at 52 weeks at the high dose (focal
acinar cell atrophy and pituitary pars distalis hyperplasia) were not
significantly increased in the carcinogenicity phase, and the incidence
of ovaries with no corpora lutea was within range of historical
controls.

The LOAEL for males is 300 ppm (16.4 mg/kg/day) based on effects in the
male reproductive organs (testes, epididymides, prostate, and seminal
vesicles) and the LOAEL for females is 650 ppm based on decreased body
weight and body weight gain.  The NOAEL for males is 100 ppm (5.5
mg/kg/day) and the NOAEL for females is 300 ppm (21.0 mg/kg/day). 

At the doses tested, there was some evidence of carcinogenicity in male
rats based on a significantly increased incidence of interstitial
(Leydig) cell adenoma in the mid and high-dose groups compared with the
control group.  The incidence was 1/60 (2%), 4/60 (7%), 6/60 (10%,
p<0.05), and 7/60 (12%, p<0.05) at 0, 100, 300, and 650 ppm,
respectively.  The incidence of interstitial cell adenoma in the testes
also exceeded that of historical controls, which ranged from 0-6.2% with
an average of 2.5%.  The test material produced non-neoplastic lesions
in the testes, epididymides, seminal vesicles, and prostate and
neoplastic lesions in the testes indicating that the mode of action of
LGC-30473 is possibly endocrine disruption affecting the hypothalamic-
pituitary-testicular axis in males. 

The incidence of pituitary pars distalis adenoma was 32/60 (53%), 39/60
(65%), 43/60 (72%, p<0.01), and 36/60 (60%) and the incidence or pars
distalis adenoma/adenocarcinoma combined was 42/60 (70%), 48/60 (80%),
51/60 (85%, p<0.05), and 51/60 (85%, p<0.05) in females at 0, 100, 300,
and 650 ppm, respectively.  The incidences of adenoma in mid-dose
females and adenoma/adenocarcinoma combined in mid- and high-dose
females were slightly above the upper range of historical controls;
nevertheless, the lack of a clear dose-related trend and the extremely
high incidence in controls suggest that the increased incidences are not
treatment related.  The rats were adequately dosed to test for
carcinogenicity as evidenced by decreased body weight gain in female
rats and non-neoplastic lesions in the reproductive organs in male rats.

The chronic toxicity/carcinogenicity study in the rat is
Acceptable/Guideline and satisfies the guideline requirement (OPPTS
870.4300); OECD 453) for a chronic toxicity/carcinogenicity study in
rats.  

  SEQ CHAPTER \h \r 1 Carcinogenicity Study -Mouse; OPPTS 870.4200b;
OECD 451

EXECUTIVE SUMMARY:   SEQ CHAPTER \h \r 1 In a 78-week oral
carcinogenicity study (MRID 46387810), Ethaboxam (LGC-30473, 99.0% a.i.)
was administered to groups of 50 Crl:CD-1®(ICR)BR mice/sex/dose in the
diet at 0, 100, 300, or 900 ppm (approximately equivalent to 0, 12, 35,
or 117 mg/kg bw/day in males and 0, 14, 44, or 135 mg/kg bw/day in
females).

There were no treatment-related effects on mortality or clinical signs. 
The mean final body weight of males and females at 900 ppm was decreased
by 9%, and the mean body weight gain of males and females at 900 ppm was
decreased by 20%, compared to the control groups.  Food consumption was
similar in all groups of males and females.  The overall food efficiency
during the 78-week study was decreased by about 16% in males and 19% in
females at 900 ppm compared to the control group.  The differential
blood counts did not reveal any physiologically significant changes at
52 or 78 weeks. 

The group mean relative liver weight (adjusted for body weight) was
significantly increased by about 20% in females at 900 ppm compared to
the control group.  Relative liver weight in males was increased by 10%
compared to controls. Incidences of centrilobular hepatocyte hypertrophy
(36%) and liver eosinophilic foci (18%) were increased in males at 900
ppm compared to the control group (22% and 10%, respectively).  The
liver alterations (hepatocyte hypertrophy, and increased liver weights)
seen at 900 ppm are considered adverse due to the presence of
eosinophilic foci at this dose. The incidences of lung alveolar
macrophage aggregations (14%) and the presence of perivascular lymphoid
cells (12%) in males at 900 ppm were increased compared to the control
group (2%).  The incidence of testicular focal interstitial cell
hyperplasia was significantly increased in males at 300 ppm (18%) and
900 ppm (10%) compared to the controls (2%), but the increases were not
dose related.

The LOAEL is 900 ppm (approximately 117 mg/kg/day in males and 135
mg/kg/day in females) in mice based on decreased body weight gain and
food efficiency in both sexes, and liver toxicity (hepatocyte
hypertrophy, increased liver weights, and eosinophilic foci) in males. 
The NOAEL is 300 ppm (approximately 35 mg/kg/day in males and 44
mg/kg/day in females).

Treatment of Crl: CD-1®(ICR)BR mice with LGC-30473 at dietary levels of
up to 900 ppm for up to 78 weeks did not result in a significant
increase in the incidence of individual neoplasms compared to the
control groups.  However, the incidence of hepatocellular adenoma (38%)
in males at 900 ppm was increased (not statistically significant, NS)
compared to the control group (26%), and was near the upper range seen
in historic control animals (~14-40%).  Combining the liver adenoma and
carcinoma incidences resulted in the combined incidence (40%) being
significantly different (p=0.048) from the control group (26%).  The
liver neoplasms were not increased in high-dose females compared to the
control group.

This carcinogenicity study in the mouse is Acceptable/Guideline and
satisfies the guideline requirement (OPPTS 870.4200b; OECD 451) for a
carcinogenicity study in mice.

Bacterial Reverse Mutation Assay; OPPTS 870.5100; OECD 471

EXECUTIVE SUMMARY: In independent bacterial reverse mutation assays
(MRID 46378529), four histidine dependent auxotrophic strains (his-) of
Salmonella typhimurium  (TA1535, TA1537, TA98 and TA100) and the
tryptophan dependent auxotrophic strain (try-) of Escherichia coli WP2
uvra (CM891) were exposed for 3 days at 37° C to LGC-30473 (Lot No.
P980622, 99% a.i. dissolved in dimethyl sulfoxide, DMSO) at  five
concentrations ranging from 50 to 5000 ug/plate in the presence and
absence of the supernatant of hepatic mixed function oxidase homogenates
(±S9) plus a generating cofactor system (S9-mix), employing a plate
incorporation assay and a pre-incubation assay,  a variation of the
standard plate assay.  In addition to cultures exposed to solvent only
(representing the “negative” control), other cultures were treated
with strain-specific mutagens, as positive controls for the nonactivated
(-S9) and activated (+S9) series.  At harvest, the incidences of
revertants in test cultures was compared to that in negative controls,
as an indication of reverse mutation to prototrophy (his- to his+; try-
to try+) and the incidences in positive controls compared to negative
controls to assess the sensitivity (acceptance) of the assay.

A preliminary range-finding test was performed at seven concentrations
of the test article from 5 to 5000 ug/plate, plus negative and positive
controls, using the standard plate procedure. 

No cytotoxicity was observed in either experiment at any concentration
up to the limit dose, 5000 ug/plate.

There was no evidence of reverse mutagenicity at any concentration in
either the first (the range-finder) or the second (independent) test,
compared with the marked increases of revertants indicating positive
mutagenicity in all positive control cultures.  Therefore, LGC-30473
(ethaboxam) is considered negative for mutagenic activity in this
standard bacterial test system.

This study is classified as acceptable/guideline and satisfies the
guideline requirement (OPPTS 870.5100; OECD 471) for in vitro
mutagenicity (bacterial reverse gene mutation) data.

In Vitro Mammalian Cell Gene Mutation Test; 870.5300, OECD 476

						

EXECUTIVE SUMMARY: In independent (Trials I and II) mammalian cell
forward mutation assays (MRID 46378530), cultures  of  mouse  lymphoma 
L5178Y cells,  heterozygous  at  the  thymidine  kinase  locus (TK+/-)
were exposed for 3 hours to LGC-30473 (Batch No. 980662, 99% a.i.),
dissolved in dimethyl sulfoxide (DMSO), at 7 concentrations ranging from
2.3 to 150 ug/mL, or 8 concentrations ranging from 2.3 to 300 ug/mL, in
the presence and absence of metabolic activation (±S9).  The production
of homozygous forward mutations (TK-/-) was determined following
incubation in a medium containing the modified nucleoside,
trifluorothymidine, which allows the mutant colonies to survive, but
kills any remaining heterozygotes, as well as homozygous convertants
(TK+/+).  In addition to cell cultures exposed to the solvent,
representing the “negative” control, other cultures were treated
with the mutagens, methyl methanesulfonate (MMS, 10 ug/mL) and
methylcholanthrene (MC, 2.5 ug/mL), to serve as positive controls (Trial
1).

In Trial 2, non-activated cell cultures (-S9) were exposed for 24 hours
to the test article, but at a reduced range of concentrations, 0.25 to
10.0 ug/mL, whereas S9-activated cultures were exposed to 10 to 300
ug/mL.  Forward mutations were determined as before, and negative and
positive controls accompanied all test conditions.  However, in this
trial, 5 ug/mL MMS were given to non-activated cultures, and the same
concentration as in Trial 1 to S9-activated cultures.

In a preliminary cytotoxicity test, cells were exposed for 3 hours to
the test article at 8 concentrations of 2.3 to 300 ug/mL ±S9, and for
24 hours –S9.  Survival of treated cells relative to the negative
control decreased by 10% to 20% at ≥ 150 ug/mL ± S9.

LGC-30473 did not increase mutation frequency in either Trial, either in
the presence or absence of metabolic activation, compared to marked
increases by both positive controls.  Therefore, LGC-30473 is considered
non-mutagenic in this in vitro assay.

This study is classified acceptable/guideline and satisfies the
guideline requirement (870.5300, OECD 476) for mammalian in vitro
mutagenicity data.

In Vitro Mammalian Chromosome Aberration Test; OPPTS 870.5375; OECD 473

	EXECUTIVE SUMMARY: In independent in vitro mammalian chromosome
aberration (metaphase analysis) assays (MRID 46378531), human
lymphocytes, stimulated to divide by exposure to phytohemmaglutinin,
were treated for 3 hours followed by 16 hours recovery with LGC-30473
(Lot No. P980622, 99% a.i., dissolved in dimethyl sulfoxide, DMSO) at
concentrations ranging from 15.6 to 2000 ug/mL in the presence and
absence of exogenous metabolic activation ±S9 (Trial 1); or
continuously for 19 hours at a range of 8 concentrations, 20 to 600
ug/mL  -S9, and for 3 hours followed by a 16 hour recovery period at the
same concentration range +S9 (Trial 2).  In addition to cultures exposed
to the solvent (representing the “negative” control), other cultures
were treated with the clastogenic mutagens, mitomycin C (MMC: 0.1 ug/mL
for the 19-hour exposures; 0.2 ug/mL for the 3-hour exposures) and
cyclophosphamide (CPP, 6 ug/mL).  Two hours before harvest, all cultures
were exposed to the anti-mitotic alkaloid, colchicine (as Colcemid®),
which arrests cell division at the metaphase stage.  Following this
treatment, cytotoxicity was determined by Mitotic Index (MI), and the
proportion of cells with chromosome aberrations recorded.

	In the human lymphocyte cytogenetics assay (MRID 46378531), ethaboxam
induced significant (p < 0.01) increases in chromosome aberrations and a
marked increase in the mitotic index (MI) at a concentration of 250
ug/mL –S9 after a 3-hour exposure and at 100 ug/mL after a 19-hour
continuous exposure.  The most frequently observed aberration was
chromatid breaks suggesting a cytotoxic effect; this observation is
supported by the severe cytotoxicity reported as necrotic cells and a
reduction in scoreable metaphase at higher concentrations (≥ 500
ug/mL, 3-hour exposure; ≥ 200 ug/mL –S9, 19-hour exposure).  With
S9-activation, no firm conclusion can be reached because the levels
showing significant increases (p < 0.01) in chromosome aberrations (125
and 250 ug/mL +S9) were not evaluated in the repeat because of severe
cytotoxicity at ≥ 200 ug/mL;  no explanation was given for excluding
100 ug/mL +S9 from testing.  Similarly, no explanation was presented for
the marked increases in the MIs of cells treated with concentrations as
low as 20 ug/mL –S9 (626% vs. 100% for the solvent control) or 60
ug/mL +S9 (145% vs. 100% in the solvent control).  In agreement with the
earlier nonactivated findings, chromatid breaks were the most frequently
observed structural aberration.

This study is classified as unacceptable/guideline and does not satisfy
the guideline requirement (OPPTS 870.5375; OECD 473) for in vitro
cytogenetic data.

Mammalian Bone Marrow Chromosome Aberration Test; OPPTS 870.5385

EXECUTIVE SUMMARY: In a bone marrow micronucleus assay (MRID 46378532),
groups of six or seven male rats were administered LGC-30473 (Batch No.
P980622, 99% a.i., suspended in 0.5 methylcellulose, MC) by oral gavage
at single doses of 500 (7 animals); 1000 (7 animals), and 2000 (6
animals) mg/kg.  Bone marrow cells were collected 24 hours after dosing,
and the incidences of micronuclei in “immature” (i.e.,
polychromatic) erythrocytes (mPCEs) recorded; mPCEs were also scored 48
hours after dosing in 7 negative control males and 7 males given the
highest test article dose.  Additionally, the incidences of
micronucleated “mature” (i.e., normochromatic) erythrocytes were
recorded.  In addition to the 7 males given MC (representing the
“negative” control) by oral gavage, 5 animals received
cyclophosphamide (CPA, 20 mg) once orally, to serve as the positive
control.

In a preliminary oral toxicity test, groups of 2M:2F test
article-treated animals were administered single doses of  500, 1000,
and 2000 mg/kg  (the last, the internationally recognized limit dose for
acute studies).  The test article was tolerated at 500 and 1000 mg/kg,
but caused clinical toxicity at 2000 mg/kg (i.e., abnormal gait, flat
posture, rapid respiration and bulging eyes).  All animals, however,
survived to scheduled sacrifice.  There were no toxicological
differences between males and females; consequently, only males were
tested in the main assay. 

Clinical signs, similar to seen in the earlier test, and one mortality,
was recorded for the high dose males.  No statistically significant
increases in the incidence of mPCEs in test article-treated rats were
found at any dose level in either timed post-treatment group, when
compared to vehicle control values.  As well, there were no marked
decreases  in  the proportion of  PCEs  (p > 0.01 in each case).  In
contrast, CPA produced significant increases in mPCES, and a significant
decrease in the proportion of PCEs (p < 0.001).  Therefore, LGC-30473
showed no evidence of causing either a clastogenic or aneugenic response
when administered by oral gavage up to a clinically toxic dose.

This study is classified as acceptable/guideline and satisfies the
guideline requirement (OPPTS 870.5385; OECD 475) for in vivo cytogenetic
mutagenicity data.

Metabolism Study-Rat; OPPTS 870.7485; OECD 417

EXECUTIVE SUMMARY:   SEQ CHAPTER \h \r 1 In a five-day metabolism study
(MRID 46378533), either [14C-thiazole]LGC-30473 or
[14C-thiophene]LGC-30473 was administered by oral gavage or cannula (for
bile-duct cannulated rats) to groups of  Sprague-Dawley rats at doses of
10 or 150 mg/kg.  To assess excretion, tissue distribution, and
metabolism, groups of 4 rats were administered a single oral dose of 10
or 150 mg/kg of the thiazole or thiophene radiolabeled compound, or 10
mg/kg of the thiazole radiolabeled compound orally once daily for 14
days.  Biliary excretion was assessed in groups of 4 bile-duct
cannulated rats/sex administered a single dose of 10 or 150 mg/kg of the
thiazole labeled compound.  Plasma and blood cell pharmacokinetics were
assessed in groups of 12 rats/sex administered a single oral dose 10 or
150 mg/kg of the thiazole or thiophene radiolabeled compound, or 10
mg/kg of the thiazole radiolabeled compound orally once daily for 14
days

Mass balance was acceptable for the studies, ranging from 88-94% for the
biliary excretion study and 96-105% for the excretion, tissue
distribution, and metabolism studies.  Most of the radiolabeled compound
was excreted in the feces or urine within 48 hours of administration,
regardless of radiolabel, dose, or sex.  For both radiolabels, fecal and
urinary excretion combined accounted for 96-104% of the administered
dose.  The main route of excretion was feces, accounting for 66-74% of
the single or repeated administered low-dose, followed by urine
accounting for 23-30% of the administered low-dose.  Increasing the dose
to 150 mg/kg resulted in more compound being excreted in the feces and
less in the urine: fecal excretion accounted for 83-92% of the
administered dose, while urine accounted for 13-17% of the administered
dose.  Results were similar in the biliary excretion study, where the
percentage of thiazole radiolabeled compound absorbed in males and
females within 48 hours of dosing was 71 and 72%, respectively, for the
low dose, and 48 and 61%, respectively, for the high-dose.  

Tissue distributions studies demonstrated that minimal amounts (<1% of
the dose) of the radiolabeled compound were retained in the tissues up
to 120 hours post dosing.  The thyroid generally contained the highest
µg equivalents/g of the thiazole label, but only minimal amounts of the
thiophene label.  The liver, kidney, blood cells, and whole blood
contained the next highest equivalents, with comparable equivalents
measured for both radiolabels. 

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 in blood cells, blood cell pharmacokinetic values were generally
comparable to or lower than plasma values.  The t1/2 was similar
following single administration of both the low- and high-dose, while
the Cmax, tcmax, and the AUC120 were higher following the high-dose
compared to the low-dose.  However, as stated by the author, the
increases were not proportional to dose and suggest capacity limited
absorption of radioactivity.  Compared to single dosing of the thiazole
radiolabelled compound, repeated administration of the low-dose resulted
in slight increases in plasma Cmax and notable increases in t1/2 and
AUC120.  Female rats had higher maximum mean plasma radioactivity
concentrations, higher plasma AUC120, and longer terminal plasma
half-life.  

Minimal quantitative differences were noted within the metabolic
profiles of urine, feces, or bile from rats administered the same doses
of compound with the thiazole or thiophene label, following single or
repeated oral administration of the low-dose of the thiazole label, or
between sexes.  The major urinary radioactive component was LGC-32801,
followed by LGC-32800.  The major fecal component was the parent
compound (LGC-30473), followed by LGC-32802, LGC-32803 and LGC-32801. 
The main biliary radioactive components were LGC-32801 and LGC-32794. 

 

The metabolism study is classified Acceptable/Guideline and satisfies
the guideline requirement [OPPTS 870.7485, OECD 417] for a metabolism
study in the rat.

Attachment 1.  Personal Communication from Alberto Protzel, HED
regarding residues of concern for ethaboxam.

Alberto Protzel/DC/USEPA/US

03/31/2006 02:22 PM	To:  Michael Doherty/DC/USEPA/US@EPA

Cc:  Karlyn-J Bailey/DC/USEPA/US@EPA, Louis Scarano/DC/USEPA/US@EPA

Subject:  Re: Metabolism Question

Hello Mike:

Here is my response:

LGC-35523 is expected to be significantly less toxic than the parent and
not to share the same toxicity endpoints as the parent ethaboxam.  For
the following reasons:

1.  LGC-35523 is a very polar compond, that is likely to undergo rapid
excretion with very little biochemical transformation in mammals.   It
is not likely to engage in interactions, as the much less polar parent
will do, that might lead to microsomal enzyme induction, inhibition of
mitochondrial respiration or endocrine disruption. 

2.  The following 28-day rat dietary studies indicate that LGC-35523 is
less toxic than the parent:

-  In a  rat dietary study conducted at levels of 650, 2000 or 13,000
ppm, LGC-35523 had a NOAEL of 2000 ppm and a LOAEL of 13,000 ppm (with
relatively benign treatment-related effects). 

-  In a rat dietary study conducted at levels of 500, 1000, 3000, or
5000  ppm, parent ethaboxam had a NOAEL of 500 ppm and a LOAEL of 1000
ppm attributable to reduced food intake plus toxicity resulting in 
growth retardation.  At higher doses liver and thyroid weights were
increased.

Thus, it does not need to be included as a residue of concern for risk
assessment.

I'll place all the documents that i've received from you and Karlyn on
your respective chairs. 

Bye.    

Alberto.

___________________________________________

Alberto Protzel Ph.D.

US Environmental Protection Agency

Office of  Pesticide Programs (7509C)

Tel. (703) 305-5347

Fax (703) 605-0670

Deliveries: 1801 S. Bell St. (Rm 712K)

                     Arlington VA   22202

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