UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF

PREVENTION, PESTICIDES, AND

TOXIC SUBSTANCES

MEMORANDUM

DATE:		May 15, 2007

SUBJECT:		Fenazaquin: PP# 9E5059.  Tolerances on Apples, Pears and
Citrus Fruits Exported to the US.  HED Risk Assessment.  PC Code:
044501, Decision #: 302678, DP #: 325204.

FROM:		Jack Arthur, Senior Environmental Scientist (RAB3)

		         Danette Drew, Chemist (RRB3)

		         David Soderberg, Chemist (RRB3)

		         Pete Savoia, Chemist (RRB3)

		         Ghazi Dannan, Toxicologist (RAB3)

Health Effects Division (7509P)

THROUGH:	Cathy Eiden, RARC Reviewer

			Elissa Reaves, RARC Reviewer

			Paula Deschamp, Branch Chief

Registration Action Branch 3 (RAB3)

Health Effects Division (7509P)

TO:			Daniel Peacock/John Hebert (RM 07)

Insecticide Branch

Registration Division (7505P)

The Registration Division (RD) of OPP has requested that HED evaluate
toxicology and residue chemistry data and conduct dietary assessments to
estimate the risk to human health from the proposed use of the miticide,
fenazaquin on apples, pears and citrus fruits exported to the United
States.  An assessment of human risk resulting from the proposed use of
fenazaquin is provided in this document.  The hazard assessment was
provided by Ghazi Dannan of RAB3, the residue chemistry data review by
Danette Drew, David Soderberg and Jose Morales of Reregistration Branch
3 (RRB3), the dietary risk assessment by Peter Savoia of RRB3, and the
risk assessment by Jack Arthur of RAB3.  There are currently no
registered food/feed uses or tolerances for fenazaquin in the U.S.  No
drinking water, residential or occupational exposure assessment is
required.

Several deficiencies in the subject petition were noted (see Section 8.1
for details), including the need for a revised Section F.  However,
sufficient data are available to allow HED to   SEQ CHAPTER \h \r 1
recommend establishing tolerances for residues of fenazaquin at 0.2 ppm
in/on apple and pear, 0.5 ppm in/on citrus fruits, except grapefruit,
and 10 ppm in citrus oil, for import purposes.  

Table of Contents

  TOC \o "1-4" \f  1.0  EXECUTIVE SUMMARY	  PAGEREF _Toc166399555 \h  4 

2.0  Ingredient Profile	  PAGEREF _Toc166399556 \h  6 

2.1	Summary of Registered/Proposed Uses	  PAGEREF _Toc166399557 \h  6 

3.0  Hazard Characterization/Assessment	  PAGEREF _Toc166399558 \h  8 

3.1	Hazard and Dose-Response Characterization	  PAGEREF _Toc166399559 \h
 8 

3.1.1	Database Summary	  PAGEREF _Toc166399560 \h  9 

3.1.1.1	Studies available and considered (animal, human, general
literature)	  PAGEREF _Toc166399561 \h  10 

3.1.1.2	Mode of action, metabolism, toxicokinetic data	  PAGEREF
_Toc166399562 \h  10 

3.1.1.3	Sufficiency of studies/data	  PAGEREF _Toc166399563 \h  11 

3.1.3	Dose-response	  PAGEREF _Toc166399564 \h  11 

3.5	Hazard Identification and Toxicity Endpoint Selection	  PAGEREF
_Toc166399565 \h  11 

3.5.1	Acute Reference Dose (aRfD) - Females age 13-49	  PAGEREF
_Toc166399566 \h  11 

3.5.3	Chronic Reference Dose (cRfD)	  PAGEREF _Toc166399567 \h  13 

3.3	FQPA Considerations	  PAGEREF _Toc166399568 \h  15 

3.3.1	Adequacy of the Toxicity Database	  PAGEREF _Toc166399569 \h  15 

3.3.2	Evidence of Neurotoxicity	  PAGEREF _Toc166399570 \h  15 

3.3.3	Developmental Toxicity Studies	  PAGEREF _Toc166399571 \h  16 

3.3.4	Reproductive Toxicity Study	  PAGEREF _Toc166399572 \h  16 

3.3.6	Pre-and/or Postnatal Toxicity	  PAGEREF _Toc166399573 \h  17 

3.3.6.1	Determination of Susceptibility	  PAGEREF _Toc166399574 \h  17 

3.3.6.2	Degree of Concern Analysis and Residual Uncertainties for Pre-
and/or Postnatal Susceptibility	  PAGEREF _Toc166399575 \h  17 

3.3.7	Recommendation for a Developmental Neurotoxicity Study	  PAGEREF
_Toc166399576 \h  17 

3.4	Safety Factor for Infants and Children	  PAGEREF _Toc166399577 \h 
17 

3.5.10	Classification of Carcinogenic Potential	  PAGEREF _Toc166399578
\h  18 

3.5.11	Summary of Toxicological Doses and Endpoints	  PAGEREF
_Toc166399579 \h  19 

3.6	Endocrine disruption	  PAGEREF _Toc166399580 \h  19 

4.0  Public Health Data	  PAGEREF _Toc166399581 \h  20 

5.0  Exposure Characterization/Assessment	  PAGEREF _Toc166399582 \h  20


5.1	Pesticide Metabolism and Environmental Degradation	  PAGEREF
_Toc166399583 \h  20 

5.1.1	Metabolism in Primary Crops	  PAGEREF _Toc166399584 \h  20 

5.1.2	Metabolism in Rotational Crops	  PAGEREF _Toc166399585 \h  21 

5.1.3	Metabolism in Livestock	  PAGEREF _Toc166399586 \h  21 

5.1.4	Analytical Methodology	  PAGEREF _Toc166399587 \h  21 

5.1.5	Pesticide Metabolites and Degradates of Concern	  PAGEREF
_Toc166399588 \h  22 

5.1.6	Food Residue Profile	  PAGEREF _Toc166399589 \h  22 

5.1.7	Proposed Tolerances	  PAGEREF _Toc166399590 \h  23 

5.1.8	International Residue Limits	  PAGEREF _Toc166399591 \h  25 

5.2	Dietary Exposure and Risk	  PAGEREF _Toc166399592 \h  25 

5.3	Anticipated Residue and Percent Crop Treated	  PAGEREF _Toc166399593
\h  26 

6.0  Aggregate Risk Assessments and Risk Characterization	  PAGEREF
_Toc166399594 \h  26 

7.0  Cumulative Risk Characterization/Assessment	  PAGEREF _Toc166399595
\h  26 

8.0  Data Needs and Label Requirements	  PAGEREF _Toc166399596 \h  27 

8.1	Residue Chemistry	  PAGEREF _Toc166399597 \h  27 

REFERENCES	  PAGEREF _Toc166399598 \h  28 

 

1.0	EXECUTIVE SUMMARY tc \l1 "1.0  EXECUTIVE SUMMARY 

HED is conducting a risk assessment for fenazaquin,
4-tert-butylphenethyl quinazolin-4-yl ether, in support of the
establishment of permanent tolerances on apples, pears and citrus fruits
exported to the U.S.  HED has evaluated toxicology and residue data for
fenazaquin submitted by Gowan Company. 

Fenazaquin is a quinazoline class insecticide/acaricide used primarily
for the control of mites.  It is approved for use on a variety of field,
vegetable and fruit crops in a number of countries, but there are
currently no registered food/feed uses or tolerances for fenazaquin in
the U.S.  To support the use of fenazaquin on apples, pears and citrus
fruits grown in other countries for export to the U.S., Gowan Company
has submitted a petition (PP#9E5059) proposing permanent U.S. tolerances
for residues of fenazaquin in/on the following raw agricultural
commodities:

Apple 	 0.2 ppm

Pear 	  0.2 ppm

Citrus fruits 	  0.5 ppm

Fenazaquin is formulated by Gowan as either a 100 g/L emulsifiable
concentrate (EC) or 200 g/L suspension concentrate (FlC) and is approved
for use on pome fruits throughout Europe, North Africa, the Middle-East,
Argentina and Chile and for use on citrus fruits in Chile and selected
Asian and Mediterranean countries.  Depending on the country, fenazaquin
(FlC) may be applied to apples and pears using ground equipment as a
single foliar application during fruit development at a rate of 100-250
g ai/ha (0.09-0.22 lb ai/A), and the minimum pre-harvest interval (PHI)
for any country is 28 days.  For citrus fruits, fenazaquin (EC) may be
applied using ground equipment as a single foliar application during
fruit development at a rate of 100-450 g ai/ha (0.09-0.40 lb ai/A), with
a minimum pre-harvest interval (PHI) of 21 days.

Because there are no proposed or existing residential uses for
fenazaquin, and the proposed use is limited to crops exported to the
U.S., no occupational, residential or drinking water exposure assessment
is required.

Hazard Assessment

Fenazaquin is a miticide that exhibits both contact and ovicidal
activity against a broad spectrum of mite and certain insects through
inhibition of mitochondrial electron transport at the Complex I.  The
toxicology data base is considered adequate for an import food
tolerance.  Fenazaquin is acutely toxic when administered orally in rats
(LD50 = 134/138 mg/kg in males/females) but no information is available
on its acute toxicity by other routes of exposure.  Following repeated
oral administration in 90-day and chronic toxicity studies using rats,
hamsters, or dogs, the major findings were decreased body weight and
gain in addition to reduced food intake and efficiency.  Testicular
atrophy and decreased prostate weight were additional findings in the
90-day hamster study seen at relatively higher doses ((75 mg/kg/day)
than those used in the 18-month hamster study (high dose = 30
mg/kg/day).  Decreased body weight/weight gain and food
intake/efficiency were also identified in parental animals of the rat
developmental and reproduction studies and in the offspring of the
reproduction rat study.  There were no developmental findings in the rat
study and no parental or developmental findings of any kind up to 60
mg/kg/day in the rabbit developmental study.  There is no clear evidence
of consistent neurotoxicity findings in the available toxicity studies. 
Excessive salivation was reported at the high dose in the rat
two-generation reproduction toxicity study in addition to possibly
decreased motor activity and impaired righting reflex in the preliminary
reproduction study.  There are no available acute or 90-day
neurotoxicity studies but the findings in the reproduction studies are
unlikely to be a sign of neurotoxicity since the chemical is not known
to have a neurotoxic mode of action and no similar clinical findings
were reported in the 90-day or chronic/carcinogenicity studies at doses
(up to 33 and 26 mg/kg/day, respectively) comparable to those used in
the reproduction studies (25-27.5 mg/kg/day).

There were no indications of pre- or post-natal enhanced sensitivity or
susceptibility to the young.  The residual uncertainty due to inadequate
dosing in the rabbit developmental study should not impact the current
evaluation because acute and chronic dietary endpoints are based on a
NOAEL of 10 mg/kg/day (maternal animals in the rat developmental study)
and 5 mg/kg/day (parental animals of the reproduction study),
respectively, which are well-below the high dose of 60 mg/kg/day in the
rabbit developmental study.  

Fenazaquin appears to increase peroxisomal proliferation in rats and
mice but hamsters were resistant since peroxisomal beta oxidation was
not increased in the 90-day hamster study.  Oxidation of the t-butyl
substituent (to the corresponding carboxylic acid) on the alkylbenzene
moiety of fenazaquin appears to be the critical step for heptatocellular
peroxisome proliferation in a female mouse study.

There were no findings of carcinogenicity in rat and hamster studies and
no findings of mutagenicity in an in vitro and in vivo test battery.  

At 168 hours following oral administration in rats, most of the
radiolabeled fenazaquin (89.5-107.7%) was recovered in rat excreta with
approximately 20% of the radiolabel in urine.  Additional minor amounts
were recovered in the carcass (0.5-1.6%) and tissues (<0.04% of the dose
in each tissue).  Based on characterization of excretable metabolites,
fenazaquin may undergo oxidation to alcohol and/or carboxyolic acid
derivatives; alternatively, the ether bond may be hydrolyzed to the
respective alcohol and carboxylic acid fragments. 

In conclusion, there is no evidence of developmental or reproductive
toxicity, mutagenicity or carcinogenicity.

Residues of concern/enforcement method

Based on the data from the available apple, orange and goat metabolism
studies, HED concludes that the metabolism of fenazaquin in plants and
livestock commodities is adequately understood for the purpose of this
petition only.  For the purpose of tolerance expression, the residue of
concern in plants is parent fenazaquin.  For risk assessment purposes,
residues of concern in plant commodities include parent fenazaquin and
its dimer.  These residues are included in the current dietary
assessment. Any additional proposed uses of fenazaquin may require new
plant and animal metabolism studies.

The Agency concludes that, for purposes of this petition, finite
residues of fenazaquin are not expected in livestock commodities.
Tolerances for fenazaquin in livestock commodities may be required if
future uses result in significant residues on livestock feedstuffs. In
that case, an enforcement method and storage stability data would be
needed for livestock commodities.

There were several deficiencies in the proposed single analyte
enforcement analytical methods, 

However, the available data indicate fenazaquin tolerances may be
enforced using the existing FDA Multiresidue Methods in PAM, Vol I. 
Testing of fenazaquin through the multiresidue methods indicated that
fenazaquin was adequately recovered from whole oranges and from orange
oil. Radiovalidation data for the single analyte methods should be
submitted with future petitions.

Dietary/Aggregate Risk Estimates 

The DEEM-FCID™ acute and chronic analyses assume that fenazaquin
residues are in/on all registered food commodities at tolerance levels
and that 100% of all Raw Agricultural Commodities (RACs) are treated. 
To support these unrefined analyses, adequate data in the form of crop
field trial studies for the apple, pear, and citrus fruit RACs are
relied upon (DP Barcode D329427, D. Drew & D. Soderberg, 04/26/07). 
These studies present a “worse-case” use pattern for these RACs from
fenazaquin field trials undertaken in several countries abroad.  The
proposed use is limited to apples, pears and citrus fruits exported to
the U.S., and therefore, the exposure/risk assessment is limited to
dietary (food) exposure only.  If new uses are added in the future, the
Agency will reassess the impact of these uses, which may result in the
need for residential and water exposure assessments.  This assessment
concludes that for all supported commodities, the acute and chronic
dietary exposure estimates are below HED’s level of concern (i.e.,
<100% aPAD and cPAD, respectively).  

2.0	Ingredient Profile tc \l1 "2.0  Ingredient Profile 

2.1	Summary of Registered/Proposed Uses tc \l2 "2.1	Summary of
Registered/Proposed Uses 

According to the petitioner, fenazaquin is approved as of 2005 for use
on pome and citrus fruits throughout Europe, North Africa, the
Middle-East, Asia, and in Latin America.  The majority of usage (>80%)
is in Europe. A general summary of the use directions for apples, pears
and citrus fruits was provided (Table 1).  An example label for a 200
g/L FlC formulation from the U.K., with use directions for apples, was
also provided.  This U.K. label specifies a maximum use rate of 150 g
ai/ha on apples with a 30-day PHI.

Table 1.  Summary of Directions for Use of Fenazaquin.

Applic. Timing, Type, and Equip.	Formulation

[g ai/L]	Applic. Rate

(g ai/ha)

[lb ai/A]	Max. No. Applic. per Season	Max. Seasonal Applic. Rate

 (g ai/ha) 

[lb ai/A]	PHI 1

(days)	Use Directions and Limitations

Apples/Pears 2

Early to late season  foliar application 3; ground equipment	200 g/L FlC
100-250

[0.09-0.22]	1	250

[0.22]	28	Only a single application is allowed per calendar year

Citrus Fruits (Oranges, Mandarins, Lemons) 4

Early to late season  foliar application; ground equipment	100 g/L EC

200 g/L FlC	100-450

[0.09-0.40]	1	450

[0.40]	21	Only a single application is allowed per calendar year

1	The PHIs listed are the minimums allowed in any country; longer PHIs
are required in some countries.

2	Fenazaquin is reportedly approved for use on apples and/or pears in
the following countries: Algeria, Argentina, Azerbajian, Bulgaria,
Chile, China, Croatia, Cyprus, Czech Rep., France, Germany, Greece,
Hungary, Israel, Italy, Jordan, Korea, Lebanon, Macedonia, Morocco,
Peru, Poland, Portugal, Romania, Russia, Slovakia, Saudi Arabia, Serbia,
Slovenia, South Africa, Spain, Switzerland, Taiwan, Turkey, United
Kingdom, Uzbekistan, and Yugoslavia. 

3	Apply after petal fall.

4	Fenazaquin is reportedly approved for use on citrus in the following
countries:  Chile, China, Greece, Italy, Korea, Morocco, South Africa,
Spain, Taiwan, and Turkey.

2.2	Structure and Nomenclature

The structure and nomenclature of fenazaquin is presented below in Table
2.

Table 2.	Fenazaquin Nomenclature.

Compound	

Common name	Fenazaquin

Molecular weight	306.4

Company experimental names	XDE-436, EL-436, XRD-562;,DE-436

IUPAC name	4-tert-butylphenethyl quinazolin-4-yl ether

CAS name	4-[2-[4-(1,1-dimethylethyl)phenyl]ethoxy]quinazoline

CAS registry number	120928-09-8

End-use products (EP)	100 g/L EC  (MAGISTER® 100 EC)

200 g/L FlC (MAGISTER® 200 SC and MATADOR® 200 SC)



2.3.	Physical and Chemical Properties 

The physicochemical properties of fenazaquin are presented below in
Table 3.

Table 3.	Physicochemical Properties of Fenazaquin.

Parameter	Value	Reference

Melting point/range	77.5-80ºC	Evaluation on Fenazaquin, Issue No. 150,
Pesticides Safety Directorate, Depart.  for Environment, Food, and Rural
Affairs, U.K., March 1996

pH	Not determined due to low solubility

	Relative Density	1.16 at 21ºC

	Water solubility (20°C)	0.102 mg/L at pH 5 & 7

0.135 mg/L at pH 9

	Solvent solubility

(g/L at 23ºC)	acetonitrile	33-50	acetone	400-500

n-chlorobutane	>500	chloroform	>500

dichloromethane	 >600	ethyl acetate	400-500 dimethylformamide  300-400
ethylene glycol	<5

hexane	33-50	isopropanol	50-100 methanol	50-100	toluene	>500	

N-methyl-2-pyrrolidone  >500

	Vapor pressure (25ºC)	1.9 x 10-5 Pa

	Dissociation constant, pKa	2.44

	Octanol/water partition coefficient, Log(KOW)	5.71 at 25ºC;  5.51 at
20ºC

	UV/visible absorption spectrum	Not available

	

3.0	Hazard Characterization/Assessment  TC \l1 "3.0  Hazard
Characterization/Assessment 

3.1	Hazard and Dose-Response Characterization  TC \l2 "3.1	Hazard and
Dose-Response Characterization 

Fenazaquin is acutely toxic when administered orally in rats (LD50 =
134/138 mg/kg in males/females).  No data were made available on acute
toxicity by other routes of exposure.

.  At the doses used (≤ 35 mg/kg/day) in all remaining subchronic and
chronic toxicity studies, there were no organ specific toxicity
findings.

Similar effects on body weight/weight gain and food intake/efficiency
were also identified in parental animals of the rat developmental and
reproduction studies and in the offspring of the reproduction rat study.
 There were no developmental findings in the rat study (up to 40 mg/kg)
and no parental or developmental findings of any kind up to 60 mg/kg/day
in the rabbit developmental study.

There are no specific neurotoxicity studies, including acute-,
subchronic-, or developmental.  There is no clear evidence of consistent
neurotoxicity findings in the available toxicity studies.  Findings of
excessive salivation in the rat reproduction toxicity study are unlikely
to be a sign of neurotoxicity since the chemical is not known to have a
neurotoxic mode of action and no similar clinical findings were reported
in the 90-day or chronic/carcinogenicity studies.  See section 3.3.2 for
additional information.

Fenazaquin appears to increase peroxisomal proliferation in rats and
mice but hamsters were resistant since peroxisomal beta oxidation was
not increased in the 90-day hamster study.

ower at doses ≥300 mg/kg.  Conversely, rat peak plasma level was
reached in 8 hours and AUC was proportional to dose while elimination
was independent of dose.  Results from the pharmacokinetics study
indicated similar pharmacokinetics of radiolabeled fenazaquin in the
hamster at doses between 5 and 125 mg/kg with peak plasma levels being
reached in 2 hours.

The hamster was chosen over the mouse for a second carcinogenicity study
based on findings in the hamster of slower elimination kinetics and
greater systemic toxicity.  Because of the high tolerance of the mouse
in regard to effect on body weight gain, the laboratory chose to use
Syrian golden hamsters as a secondary rodent model, along with rats.

 

3.1.1	Database Summary  TC \l3 "3.1.1	Database Summary 

For the purpose of assessing the proposed import food tolerances, the
toxicology database for fenzaquin is complete and adequate for risk
assessment.

3.1.1.1	Studies available and considered (animal, human, general
literature)  TC \l4 "3.1.1.1	Studies available and considered (animal,
human, general literature) 

Subchronic: Dietary 90-day toxicity (rat); gavage 90-day toxicity
(rat), 90-day oral toxicity      (hamster), 6-month oral toxicity (dog)

• Developmental: rat and rabbit developmental toxicity studies 

• Reproduction: 2-generation reproduction study (rat) 

• Chronic: combined oral chronic toxicity/carcinogenicity (rat); oral
carcinogenicity (hamster); 1-year oral toxicity (dog) 

• Other: mutagenicity battery

• Metabolism study

• Liver hypertrophy and peroxisomal acyl-CoA oxidase activity (mouse)

3.1.1.2	Mode of Action, Metabolism, Toxicokinetic Data  TC \l4 "3.1.1.2
Mode of action, metabolism, toxicokinetic data 

Fenazaquin is a miticide that exhibits both contact and ovicidal
activity against a broad spectrum of mite and certain insects by
inhibiting mitochondrial electron transport at the Complex I site
(NADH-ubiquinone reductase).

Metabolism studies were conducted in Fischer 344 rats of both sexes by
gavage administration of uniformly labeled fenazaquin on either the
t-butyl-phenyl ring or the quinazoline-phenyl ring at a single dose (1
or 30 mg/kg) or 14-daily doses (1 mg/kg/day).    

Irrespective of the dosing regimen, most of the radioactivity was
recovered in excreta (89.5-107.7%) at 168 hours post dosing with
approximately 20% of the radiolabel in urine and the remainder in feces.
 Initially, fenazaquin was uniformly distributed in rat tissues but the
levels were very low at the end of the study being about 0.5-1.6% of the
dose in the carcass and below 0.04% of the dose in each tissue.  There
was no radiolabel in the expired air and no evidence for
bioaccumulation.

It is not possible to accurately determine the extent of systemic
absorption or bioavailability of fenazaquin because no study is
available on bile cannulation or intravenous administration.  Based on
excretion (recovery in urine) and tissue residue data, systemic
absorption is estimated at about 20% which is likely to be higher
because some of the nearly 80 % fecal radioactivity may be excreted
through bile following systemic absorption.  An additional bile
cannulation study in rats using a low dose is recommended to help
determine systemic absorption of fenazaquin.

Non-metabolized fenazaquin was higher in feces (1.0-15.0% of
administered dose) than in urine (below 0.5% of dose) and some of the
major metabolites were identified including AN-1 (4.2-5.8% of dose) in
urine in addition to the fecal metabolites F-1, F-2 and F3 representing
3.5-8.4%, 11.9-19.9%, and 4.7-10.5% of the dose, respectively.  The
metabolic pathway of fenazaquin involved cleavage of the ether bond,
resulting in the formation of the respective alcohol (4-OH quinazoline
metabolite) and carboxyl acid (AN-1) derivatives.  Other
biotransformation reactions included oxidation of one of the methyl
groups on the alkyl side chain to produce either an alcohol (F-1) or
carboxylic acid (F-2) metabolites. Finally, hydroxylation at the O-ether
alkyl moiety of the metabolite F-1 or at the 2-position of the
quinazoline ring of the metabolite F-2 revealed the formation of F-1A
and F-3 metabolites, respectively.  The proposed rat metabolism pathway
is shown in Appendix B.

Fenazaquin and several of its analogs (with varying susceptibilities to
metabolism of the ether bond or the alkylbenzene substituents) were
assessed for their peroxisomal proliferation potential in groups of five
CD-1 female mice on day five following four daily gavage administrations
at equimolar concentrations.   Fenazaquin dose-dependently increased
mouse liver peroxisomal fatty acyl-CoA oxidase (FAO, a marker of
peroxisomal proliferation) and relative liver weight at doses from 100
to 750 mg/kg/day.  Based on FAO activity data, oxidation of the t-butyl
substitutent on the alkylbenzene moiety (in fenazaquin or analogues)
appears to be the critical step for hepatocellular peroxisome
proliferation in mice.  Analogs of fenazaquin with an alkylbenzene
substitutent that can be oxidized to a carboxylic acid were active
peroxisome proliferators while analogs less susceptible to oxidation
(e.g., OCF3 instead of t-butyl) were inactive.  Hydrolysis and
subsequent oxidation of the ether bond of fenazaquin and its analogs did
not result in pronounced induction of peroxisome proliferation.  In
addition, halogenation of the quinazoline moiety increased toxicity of
the compounds with no significant increase in liver weight or FAO
activity.  In conclusion, the FAO peroxisomal activity data indicate
that oxidation of the t-butyl substituent on the alkylbenzene moiety (to
the corresponding carboxylic acid) of fenazaquin and related compounds
appears to be the critical step for heptatocellular peroxisome
proliferation in female CD-1 mice.

3.1.1.3	Sufficiency of studies/data

  TC \l4 "3.1.1.3	Sufficiency of studies/data 

The database of available toxicity studies is adequate for selecting
endpoints for the acute and chronic dietary reference doses.

3.1.2	Dose-response  TC \l3 "3.1.3	Dose-response 

The endpoints, points of departure (POD) and doses used in the risk
assessment for fenazaquin are shown in Table 3.5.1.

For the acute and chronic dietary risk assessments, the uncertainty
factors used in determining the respective RfDs were 10X for
interspecies extrapolation and a 10X for intraspecies variability.

3.2	Hazard Identification and Toxicity Endpoint Selection  TC \l2 "3.5
Hazard Identification and Toxicity Endpoint Selection 

3.2.1	Acute Reference Dose (aRfD) – All Populations  TC \l3 "3.5.1
Acute Reference Dose (aRfD) - Females age 13-49 

Study Selected: developmental toxicity study - rat (Guideline
§870.3700a)

MRID No.: 45029911 

EXECUTIVE SUMMARY:  In a developmental toxicity study (MRID 45029911)
EL-436 (Fenazaquin; 98% a.i., Lot ACD13041) was administered to 25 mated
female CD [Crl:CD®(SD)] rats/dose by gavage in 10% (w/v) aqueous acacia
solution at dose levels of 0, 3, 10, or 40 mg/kg bw/day on gestation
days (GDs) 6 through 17.  On GD 20, dams were sacrificed and necropsied.
 Gravid uterine weights, corpora lutea counts, and the numbers and
positions of implantations, live and dead fetuses, and early and late
resorptions were recorded.  All fetuses were weighed, sexed, and
examined for external anomalies.  Approximately one-half of the fetuses
from each litter were subjected to visceral examination, and the
remaining one-half were subjected to skeletal examination.   

There were no deaths, abortions, or treatment-related clinical signs or
gross pathological findings.  At the 40 mg/kg bw/day dose level, mean
body weight gain was markedly decreased throughout treatment (62%, 26%,
and 12% less than controls during GDs 6-9, 10-13, and 14-17,
respectively; p<0.05), and a compensatory increase was seen during GD
18-19 (+26%; p<0.05).  These changes corresponded to decreased food
consumption by this group throughout treatment (9-15% less than
controls; p<0.05), with subsequent increased food consumption during GD
18-19 (+10%; p<0.05). 

The Maternal Toxicity LOAEL for Fenazaquin in CD rats is 40 mg/kg
bw/day, based on decreased food consumption and decreased body weight
gain.  The Maternal Toxicity NOAEL is 10 mg/kg bw/day.   

There were no treatment-related increases in fetal deaths/resorptions,
and there were no treatment-related effects on fetal sex ratios, fetal
body weight, or the incidences of fetal runts.   There was no evidence
of altered fetal ossification rates.  Malformations were observed in
1/24, 3/25, 1/22, and 1/23 litters from the control, low-, mid-, and
high-dose groups, respectively, and there were no significant increases
in litter or fetal incidences of any individual structural abnormalities
for any treated group.  

The Developmental Toxicity LOAEL for Fenazaquin in CD rats is greater
than 40 mg/kg bw/day, and the Developmental Toxicity NOAEL is equal to
or greater than 40 mg/kg bw/day. 

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

Dose and Endpoint for Risk Assessment: Maternal NOAEL = 10 mg/kg/day,
based on decreased body weight gain, food intake, and food efficiency as
early as gestation day 6-9 at the LOAEL of 40 mg/kg/day.  These findings
in the high dose group were clearly related to treatment and were
statistically significantly (SS) different compared to the findings in
control animals.  Dosing administration commenced on gestation day (GD)
6 and, at the first measurement on GD 9, body weight gain and food
intake were SS reduced by 62% and 15% respectively.  During the same
period, food efficiency was also decreased from 30.8 % to 13.6%.  All
three parameters were below respective control values during the
remainder of the treatment period but rebounded (i.e., increased
relative to control) after cessation of treatment (days 18 and 19).  

Comments about Study/Endpoint/Uncertainty Factor: The endpoint could
occur following one oral dose and is therefore appropriate for acute
dietary risk assessment. The findings in the rat developmental study are
supported by information on clinical signs and body weight in the
available rat acute oral toxicity study (LD50).  In the acute oral
toxicity study (MRID 46684003), surviving rats of both sexes had some or
all of the following clinical signs of toxicity: hypoactivity, ataxia,
diarrhea or soft stool, low carriage, hunched posture, soiling,
hind-limb paralysis or weakness, and piloerection.  (In the acute
toxicity study, the lowest dose tested in males and females was 100 and
50 mg/kg, respectively.)  The signs occurred within 1 or 2 hours and
lasted up to 2 or more days in the surviving animals at all the tested
doses from 50 to 300 mg/kg/day with some dose-dependency regarding which
signs were seen.  At its earliest measurement on day 8 post-dosing, body
weight gain was also reduced by 20% in the surviving 100 mg/kg dose
males and by 54%, and 7% in the surviving females at 100 and 50 mg/kg,
respectively.   In conclusion, the findings of clinical signs and
decreased body weight following a single oral dose of 50 mg/kg or higher
support the findings in the rat developmental study and the end-point
(NOAEL/LOAEL = 10/40 mg/kg) that were selected for acute dietary risk
assessment.

3.2.2	Chronic Reference Dose (cRfD)  TC \l3 "3.5.3	Chronic Reference
Dose (cRfD) 

Study Selected: 2-generation reproduction toxicity study - rat
(Guideline §870.3800)

MRID No.: 46684001 

EXECUTIVE SUMMARY: In a two-generation reproduction study (MRID
46684001), EL-436 (fenazaquin, 98.4% a.i., lot # 241MH8) was
administered daily by gavage to 30 male and 30 female Crl:CD® (SD)BR
rats/group at doses of 0, 1, 5, or 25 mg/kg/day.  An additional 10 F1
males and females/group were maintained on study during premating, but
were sacrificed prior to breeding.  One litter was produced in each
generation.  F0 and F1 parental males were administered the vehicle
(aqueous 10% acacia) or test article for at least 70 days prior to
mating and during cohabitation; F0 and F1 parental females were
administered vehicle or test article for 70 days prior to mating and
throughout mating, gestation, and lactation.

≤ 0.01).  This finding was not seen in control animals and occurred at
low incidence in the low- and mid-dose groups (0-7 animals/group).  The
incidence of excessive salivation was also significantly increased in
high-dose females of both generations during gestation and in high-dose
F0 females during lactation.

≤ 0.05 or 0.01) than that of controls through premating day 43 for
males (↓4-10%) and day 64 for females (↓4-7%).  For the remainder of
premating, body weight was similar to the control level.  The only
effect on body weight gain was during the first week of premating when
weight gain by the high-dose animals was decreased by 12% for males and
9% for females (both p ≤ 0.01).  Thereafter, weight gain by the
treated groups during premating was occasionally slightly greater than
or less than that of the controls.  Food consumption by the high-dose F1
males and females was significantly less (p ≤ 0.01; ↓7-8%) during
the second week of treatment; no other effects on food consumption were
seen.  Body weight, body weight gain, and food consumption by the low-
and mid-dose F0 males and F1 males and females were similar to those of
the controls during the premating interval.

≤ 0.01; ↑5%) absolute body weight on lactation day 21 compared with
the controls.  Correspondingly, body weight gain by the high-dose F0
females was significantly greater than that of the controls during
lactation.  Food consumption by the high-dose F0 females was not
affected by treatment during lactation.

Testes weight was not affected by treatment.  Gross necropsy was
unremarkable and no treatment-related microscopic lesions were found in
tissues from the reproductive tract of males or females of either
generation.

The Parental Systemic Toxicity LOAEL for EL-436 in male and female
Crl:CD® (SD)BR rats is 25 mg/kg bw/day based on clinical signs of
toxicity and transient decreases in body weight, weight gain, and food
consumption.  The Parental Systemic Toxicity NOAEL is 5 mg/kg bw/day. 

No dose- or treatment-related differences in number of litters, number
of pups/litter, pup survival, or pup sex ratio were observed between the
treated and control groups of either generation.  No treatment-related
clinical signs of toxicity were observed in the pups during lactation.

No statistically significant differences in absolute body weight were
seen between offspring in the treated and control groups of either
generation.  Pup body weight data were not separated by sex.  Weight
gain by the pups in the high-dose group of both generations was
decreased by 11-13% during lactation days 4-7 with no compensation
evident during the remainder of lactation.  This lower weight gain is
considered treatment-related and is the likely reason absolute body
weight of the high-dose F1 animals was less than that of the controls
during the early phase of premating.

The Offspring/Developmental Toxicity LOAEL for EL-436 in male and female
Crl:CD® (SD)BR rats is 25 mg/kg/day based on reduced body weight gain
during lactation days 4-7.  The Offspring/Developmental Toxicity NOAEL
is 5 mg/kg bw/day. 

No treatment-related differences in pre-coital interval, number of
pregnant females, gestation length, or number of whole litter losses
were seen between the treated and control groups of either generation
during litter production.  Estrous cyclicity and sperm parameters were
not evaluated.  

The Reproductive Toxicity NOAEL for EL-436 in male and female Crl:CD®
(SD)BR rats is greater than or equal to 25 mg/kg bw/day and the
Reproductive Toxicity LOAEL is greater than 25 mg/kg/day.  

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

Dose and Endpoint for Risk Assessment: Parental systemic toxicity NOAEL
= 5 mg/kg/day, based on decreased body weight/weight gain, and food
intake in addition to increased salivation at the LOAEL of 25 mg/kg/day.

Comments about Study/Endpoint/Uncertainty Factor: The same endpoint
based on decreased body weight/weight gain, and food intake is found in
other repeated-dosing oral studies with fenazaquin (by dietary feeding
or via gavage) in all tested species and is therefore appropriate for
chronic dietary risk assessment.  The NOAEL/LOAEL (5/25 mg/kg/day) in
the two-generation reproduction study is also similar to the NOAEL/LOAEL
in the chronic toxicity (or carcinogenicity) studies in rats, dogs, and
hamsters (9.2/18.3, 5/12, and 2/15 mg/kg/day, respectively). 

3.3	FQPA Considerations  TC \l2 "3.3	FQPA Considerations 

3.3.1	Adequacy of the Toxicity Database  TC \l3 "3.3.1	Adequacy of the
Toxicity Database 

The data base is considered adequate for selecting endpoints for the
acute and chronic dietary exposure scenarios from imported foods.  Acute
toxicity studies by the inhalation and dermal routes were not made
available.  Also unavailable are studies on eye irritation, dermal
irritation, dermal sensitization, and dermal penetration in addition to
toxicity studies following repeated exposure by the dermal and possibly
inhalation routes.  According to CFR 158.340, a repeated dosing
inhalation toxicity study is conditionally required if use may result in
repeated inhalation exposure at a concentration likely to be toxic. 
These aforementioned studies are not required for this import food
tolerance risk assessment. 

3.3.2	Evidence of Neurotoxicity  TC \l3 "3.3.2	Evidence of Neurotoxicity


There is no clear evidence of consistent neurotoxicity findings in the
available toxicity studies.  Findings of excessive salivation in the rat
reproduction toxicity study are unlikely to be a sign of neurotoxicity
since the chemical is not known to have a neurotoxic mode of action and
no similar clinical findings were reported in the 90-day or
chronic/carcinogenicity studies.  It should be noted, however, that both
later studies utilized a different strain (Fischer 344) than the one
used in the reproduction study (Crl:CD (SD)BR, possibly a Sprague-Dawley
strain).  Another difference is that the 90-day and
chronic/carcinogenicity studies were administered fenazaquin by dietary
feeding while gavage administration was used in the reproduction study. 


According to the HED DER evaluation of the reproduction study, the
finding of excessive salivation was dose-dependent and was well
characterized showing a clear NOAEL/LOAEL (see executive summary under
3.2.3).  During premating, the incidence of excessive salivation in the
high-dose groups was 20/30 F0 males, 14/30 F0 females, 21/40 F1 males,
and 16/40 F1 females (all p ≤ 0.01).  This finding was not seen in
control animals and it occurred at low incidence in the low- and
mid-dose groups (0-7 animals/group).  The incidence of excessive
salivation was also significantly increased in high-dose females of both
generations during gestation and in high-dose F0 females during
lactation.  Increased salivation was also reported in the high dose
group of the preliminary one-generation reproduction study in addition
to findings of impaired righting reflex (males: 1/10, females: 2/10) and
decreased motor activity (females: 2/10) in the high dose group of the
preliminary reproduction study.

  SEQ CHAPTER \h \r 1 There are no available acute or subchronic
neurotoxicity studies but the available remaining repeated dosing
studies in rats, dogs or hamsters had no indications of
treatment-related neurotoxicity including clinical signs, qualitative or
quantitative neurobehavioral effects, brain weight changes, or
gross/microscopic pathology findings.

Among the clinical findings in the available acute oral toxicity study
were hypoactivity, ataxia, and hunched posture among surviving as well
as moribund rats.  In all likelihood, these clinical signs were due to
the high acute toxicity of fenazaquin rather than being symptoms of
neurotoxicity.

 3.3.3	Developmental Toxicity Studies  TC \l3 "3.3.3	Developmental
Toxicity Studies 

In both the rat and rabbit developmental toxicity studies, there is no
evidence of increased quantitative or qualitative susceptibility
following in utero exposure to fenazaquin.   The rabbit developmental
toxicity study is considered unacceptable/guideline due to lack of any
maternal or developmental findings up to 60 mg/kg/day.  This residual
uncertainty should not impact the current evaluation because acute and
chronic dietary endpoints are based on NOAEL/LOAEL of 10/40 and 5/25
mg/kg/day, respectively, which are well-below the high dose of 60
mg/kg/day in the rabbit developmental study.  In addition, the rat is
more sensitive to fenazaquin than the rabbit and a new developmental
toxicity study in rabbits is not expected to affect the acute dietary
end-point selection.  Therefore, a new rabbit developmental study is not
needed. 

Reproductive Toxicity Study

  TC \l3 "3.3.4	Reproductive Toxicity Study 

There are no qualitative or quantitative pre-natal susceptibility issues
and no residual uncertainties in the rat two-generation reproduction
study. 

3.3.5	Additional Information from Literature Sources 

A recently published in vitro study suggests a possible role for
fenazaquin in binding to and inhibition of mitochondrial complex I
resulting in reduction of ATP and toxicity in neuroblastoma cells.
(Sherer, T.B. et.al., J.Neurochemistry, March 2007; 100(6):1469-79).

3.3.6	Pre-and/or Postnatal Toxicity  TC \l3 "3.3.6	Pre-and/or Postnatal
Toxicity 

3.3.6.1	Determination of Susceptibility  TC \l4 "3.3.6.1	Determination
of Susceptibility 

There are no qualitative or quantitative pre- or post-natal
susceptibility issues based on available data from two developmental
toxicity studies and a two-generation reproduction toxicity study.

3.3.6.2	Degree of Concern Analysis and Residual Uncertainties for Pre-
and/or Postnatal Susceptibility  TC \l4 "3.3.6.2	Degree of Concern
Analysis and Residual Uncertainties for Pre- and/or Postnatal
Susceptibility  

As discussed above, there is no evidence of increased quantitative or
qualitative susceptibility following in utero exposure to rats or
rabbits.  There are no residual uncertainties in the rat developmental
study because a clear NOAEL/LOAEL was established.  In the rabbit
developmental toxicity study, there were no maternal or developmental
findings up to 60 mg/kg/day.  As discussed above (3.3.3), this residual
uncertainty should not impact the current evaluation because acute and
chronic dietary endpoints are based on NOAEL/LOAEL of 10/40 and 5/25
mg/kg/day, respectively, which are well-below the high dose of 60
mg/kg/day in the rabbit developmental study.

Also, there is no pre-/post-natal quantitative or qualitative
susceptibility in the two-generation reproduction study and there are no
residual uncertainties. 

3.3.7	Recommendation for a Developmental Neurotoxicity Study  TC \l3
"3.3.7	Recommendation for a Developmental Neurotoxicity Study 

Not recommended at this time.

3.4	FQPA Safety Factor for Infants and Children  TC \l2 "3.4	Safety
Factor for Infants and Children 

Based on the hazard and exposure data, the fenazaquin risk assessment
team has recommended that the FQPA Safety Factor be reduced to 1X
because there is an adequate toxicity database for the food import
tolerance on fenazaquin and exposure data are complete or are estimated
based on data that reasonably account for potential exposures. There is
no evidence of susceptibility following in utero and/or postnatal
exposure in the developmental toxicity studies in rats or rabbits, and
in the two-generation rat reproduction study. There are no residual
uncertainties concerning pre- and postnatal toxicity.  The dietary food
exposure assessment utilizes proposed tolerance level or higher residues
and 100% CT information for all commodities.  By using these
screening-level assessments, acute and chronic exposures/risks will not
be underestimated.  There is no potential for dietary drinking water
exposure and there are no residential uses.

3.5	Classification of Carcinogenic Potential  TC \l3 "3.5.10
Classification of Carcinogenic Potential 

At the request of the Registration Action Branch 3, in an ad hoc
meeting, senior members of HED's Cancer Assessment Review Committee
reviewed the carcinogenicity study in hamsters, as well as the
carcinogenicity study conducted in rats, the mutagenicity studies, and
discussed the possible carcinogenic mode of action of fenzaquin.  Based
on the weight of evidence of these studies, and in accordance with the
2005 Guidelines for Carcinogen Risk Assessment, the members concluded
that the negative hamster findings along with the negative tumor
findings in the 24-month rat study and negative mutagenicity findings
support a cancer classification of “Not likely to Be Carcinogenic to
Humans” for fenazaquin.   In this meeting it was concluded that the
carcinogenicity study in hamsters is “Acceptable/Guideline” and
satisfies the guideline requirement for a carcinogenicity study [OPPTS
870.4200; OECD 451] in hamsters.  Despite the enteritis and
administration of antibiotics, the study is considered acceptable based
on the adequacy of dosing based on evidence of systemic toxicity,
acceptable survival rate at 17 months, and lack of evidence for
tumorigenicity in two species, hamsters and rats.  

3.5.1	Summary of Toxicological Doses and Endpoints 

A summary of the toxicological doses and endpoints for use in the
fenazaquin dietary assessment are presented below in Table 4.  TC \l3
"3.5.11	Summary of Toxicological Doses and Endpoints for Use in Human
Risk Assessments 

Table 4 Summary of Toxicological Doses and Endpoints for Fenazaquin for
Use in Dietary and Non-Occupational Human Health Risk Assessments

Exposure/

Scenario	Point of Departure	Uncertainty/FQPA Safety Factors	RfD, PAD,
Level of Concern for Risk Assessment	Study and Toxicological Effects

Acute Dietary (All Populations, including Females 13-49 and
Infants/Children)	NOAEL= 10 mg/kg/day	UFA= 10 x

UFH= 10 x

FQPA SF= 1 x

	Acute RfD = 0.1 mg/kg/day

aPAD = 0.1 mg/kg/day	Rat developmental toxicity

LOAEL = 40 mg/kg/day based on findings (as early as GD 6-9) of decreased
body weight gain, food intake, and food efficiency.

Chronic Dietary (All Populations)	NOAEL= 5 mg/kg/day	UFA= 10 x

UFH= 10 x

FQPA SF= 1 x	Chronic RfD = 0.05 mg/kg/day

cPAD = 0.05 mg/kg/day	Rat two-generation toxicity study

LOAEL = 25 mg/kg/day based on excessive salivation and decreased body
weight/weight gain and food intake.

Short- and Intermediate-Term Incidential Oral (1-30 days; 1-6 months)
These exposure scenarios do not apply to this risk assessment because
there are no proposed registered residential uses of fenazaquin.

Short- , Intermediate-, and Long-Term Dermal (1-30 days; 1-6 months)
These exposure scenarios do not apply to this risk assessment because
there are no proposed registered residential or occupational uses of
fenazaquin.

Short-, Intermediate-, and Long-Term Inhalation (1-30 days; 1-6 months)
These exposure scenarios do not apply to this risk assessment because
there are no proposed registered residential or occupational uses of
fenazaquin.

Cancer (oral, dermal, inhalation)	Classification:  “Not likely to be
Carcinogenic to Humans” based on the absence of significant tumor
increases in two adequate rodent carcinogenicity studies.

Point of Departure (POD) = A data point or an estimated point that is
derived from observed dose-response data and  used to mark the beginning
of extrapolation to determine risk associated with lower environmentally
relevant human exposures.  NOAEL = no observed adverse effect level. 
LOAEL = lowest observed adverse effect level.  UF = uncertainty factor. 
UFA = extrapolation from animal to human (interspecies).  UFH =
potential variation in sensitivity among members of the human population
(intraspecies).  FQPA SF = FQPA Safety Factor.  PAD = population
adjusted dose (a = acute, c = chronic).  RfD = reference dose.  N/A =
not applicable.

3.6	Endocrine disruption  TC \l2 "3.6	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).

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

4.0		Public Health Data  TC \l1 "4.0  Public Health Data  

There are no existing registered or proposed uses of fenazaquin in the
U.S.  Incident reports have not been identified.  

5.0		Dietary Exposure/Risk Characterization tc \l1 "5.0  Exposure
Characterization/Assessment 

     Pesticide Metabolism and Environmental Degradation tc \l2 "5.1
Pesticide Metabolism and Environmental Degradation 

Metabolism in Primary Crops tc \l3 "5.1.1	Metabolism in Primary Crops 

An adequate apple metabolism study is described in 45029914.der.  This
study shows that TRR in apples are reduced to less than 25% of their
original value at 70 DAT after a late season treatment and are reduced
to between 1 – 4% of their original value at 105 DAT after an early
season application.  Virtually all of the TRR at 0 DAT is solvent
washable fenazaquin on the surface of the apples.  At 70 DAT identified
parent fenazaquin is less than 35% TRR, while a fenazaquin dimer has
increased to between 7 and 33% TRR.  The dimer appears to be a
photolytic product.  At 105 DAT, 12 – 21% TRR was identified as parent
fenazaquin and 10 – 22% TRR was identified as the fenazaquin dimer. 
At harvest, fenazaquin and the dimer are the predominant residues in
apples with smaller amounts of other metabolites.  

An unacceptable orange study is described in 45054401.der.  This study
shows that TRR for the whole oranges are reduced to about 15% of their
original value by 191 DAT.  Furthermore, these residues are almost
completely solvent washable surface residues at 0 DAT, but about 80% of
the remaining TRR are no longer surface washable and can only be
extracted from the homogenized tissues at 191 DAT.  At 0 DAT about 85%
of the TRR is parent fenazaquin.  At 191 DAT the proportion of the TRR
recoverable as parent has decreased to about half that and by that time
2-OH-fenazaquin accounts for another 5-8% TRR.  A photolysis study
showed that a goodly proportion of the change from free, surface
residues, to tissue associated residues may be an effect of sunlight,
but unfortunately, it is not at all clear how much photolysis may have
affected the depletion of the TRR. This study does appear to show
fenazaquin as the predominant residue in/on oranges at all DAT.

Metabolism in Rotational Crops tc \l3 "5.1.2	Metabolism in Rotational
Crops  

Rotational crop studies are not required as no uses are currently being
supported in the U.S. and the uses supported overseas are for perennial
crops. 

Metabolism in Livestock tc \l3 "5.1.3	Metabolism in Livestock  

A ruminant metabolism study is also available reflecting dosing of two
dairy goats with [U-14C-phenyl]- or [U-14C-quinazoline]-labeled
fenazaquin for 5 days at levels equivalent to 10.3 ppm in the diet,
which is 74x the potential dietary burden for cattle.  HED has concluded
that this study is unacceptable.  Although this study provided some
characterization of fenazaquin residues in livestock, the limited
results and insufficient identification of 14C-residues in edible
tissues were not adequate to allow determination of the specific
metabolism of fenazaquin in livestock nor to specify the important
metabolites in the edible tissues.  The study did show that parent
fenazaquin is not the predominant residue in liver.    

The only significant livestock feedstuffs associated with the current
petition are wet apple pomace and dried citrus pulp, which are not fed
in significant amounts to poultry or swine.  Considering the potential
levels of fenazaquin residues in these commodities, the estimated
dietary exposure of beef and dairy cattle is 0.14 ppm.  In addition, to
the goat metabolism study, the petitioner provided at cattle feeding
study in which three dairy cows were dosed with [14C]fenazaquin for 28
days at levels equivalent to 0.093 ppm in their diet (0.7x level). 
Total radioactive residues (TRR) were ≤0.0007 ppm in milk, 0.013-0.014
ppm in liver, <0.007 ppm in fat, <0.006 ppm in muscle, and ≤0.004 ppm
in kidneys.  Considering the TRR levels observed at the 0.7x feeding
level along with the limited data from the goat metabolism, the Agency
concludes that, for purposes of this petition, an additional cattle
feeding study is not required and tolerances for fenazaquin residues in
livestock commodities will not be necessary. Accordingly, analytical
methodology and storage stability data for fenazaquin residues in animal
commodities are also not required for this petition. Tolerances for
fenazaquin in livestock commodities may be required if future uses
result in significant residues on livestock feedstuffs. In that case, an
enforcement method and storage stability data would be needed for
livestock commodities.

Analytical Methodology tc \l3 "5.1.4	Analytical Methodology  

A series of related gas chromatography/mass spectrometry detection
(GC/MSD) methods are available for collecting data on fenazaquin
residues in apples, pears, citrus fruits and their various processed
fractions, and an HPLC/UV method is available for collecting data on
fenazaquin residues in apple juice.  These methods were adequately
validated in conjunction with the various field trials and processing
studies.  For each method, the validated limit of quantitation (LOQ) for
fenazaquin is 0.01 ppm in all matrices, and the reported limit of
detection (LOD) is 0.002 ppm.  Independent laboratory validation (ILV)
trials were conducted on the methods for determining residues in apple
and orange commodities (whole fruit and juice).  However, additional
information must also be submitted for each of these ILV studies before
the methods will be subjected to an Agency TMV (tolerance method
validation).  Adequate radiovalidation data, demonstrating the
extraction efficiency of the proposed enforcement methods, were not
submitted.  

Although the proposed GC/MSD and HPLC/UV methods can not yet be approved
for enforcing tolerances, the available data indicate that fenazaquin
tolerances may be enforced using the existing FDA Multiresidue Methods
in PAM, Vol I.  Testing of fenazaquin through the multiresidue methods
indicated that fenazaquin was adequately recovered from whole oranges
using methods in Sections 302 and 303 and from orange oil using methods
in Section 304.  These data will be forwarded to the U.S. FDA. 
Radiovalidation data of the single analyte methods should be submitted
for future petitions for tolerances on additional crops.

Pesticide Metabolites and Degradates of Concern tc \l3 "5.1.5	Pesticide
Metabolites and Degradates of Concern 

Based on the data from the available apple, orange and goat metabolism
studies, HED concludes that the metabolism of fenazaquin in plants and
animals is adequately understood for the purpose of this petition only. 
Fenazaquin and its dimer are the predominant residues in apples and
oranges. There were no other metabolites above 10% of the total
radioactive residue.  For the purpose of tolerance expression, the
residue of concern in plants is parent fenazaquin.  For risk assessment
purposes, residues of concern in plant commodities include parent
fenazaquin and its dimer.  In the absence of toxicity information, the
dimer is assumed to have equal toxicity to the parent (fenazaquin). 
This is a conservative assumption since the molecular weight of the
dimer is twice that of fenazaquin and is, therefore, far less
bioavailable for mammalian gastrointestinal systemic absorption. 
Moreover, the dimer is expected to be fairly stable but any possible
hydrolysis will likely yield fenazaquin.  

For purposes of this petition, finite residues of fenazaquin are not
expected in livestock commodities. Tolerances for fenazaquin in
livestock commodities may be required if future uses result in
significant residues on livestock feedstuffs.  Any future proposed uses
of fenazaquin in the U.S. are likely to require new plant and animal
metabolism studies.

 Food Residue Profile tc \l3 "5.1.6	Food Residue Profile  

Storage stability data are available indicating that fenazaquin is
stable at <-15(C in apples for up to 14.3 months and in citrus peel and
pulp for up to 12-13 months.  These data support the sample storage
intervals and conditions from all the orange and lemon field trials and
apples and pear field trials, with the exception of several pear and
apple tests conducted in Argentina during 1993/94 and tests on apples
conducted in Chile during 1995.  Apple and/or pear samples in these
tests were stored frozen for up to 22-25 months.  The stability data on
apples and orange peel and pulp will also support the processing
studies, given the shorter storage intervals in the processing studies.

Although storage stability data were not submitted to support several
tests on apples and pears, the majority of available field trials on
apples, pears and oranges are adequate and will support the proposed
tolerances on apples, pears and citrus fruits.  A sufficient number of
tests were conducted at the reported maximum uses rates on apples, pears
and oranges in countries having approved uses of fenazaquin and which
are major exporters of pome or citrus commodities to the U.S.  For
apples, data are available from 14 tests conducted at rates of 210-376 g
ai/ha (0.8-1.5x rates) from South Africa, Chile, Argentina, Italy, and
England.  In these tests, fenazaquin residues were 0.02-0.16 ppm in/on
40 samples of apples harvested at 28-35 DAT, and residues averaged 0.06
ppm.  For pears, data are available from 10 tests conducted at rates of
176-377 g ai/ha (0.7-1.5x rate) from South Africa, Argentina, Chile, and
Italy.  In these tests, fenazaquin residues were <0.01-0.17 ppm in/on 26
samples of pears harvested at 27-31 DAT, and residues averaged 0.05 ppm.
 For oranges, 12 tests are available from Spain in which oranges were
treated with fenazaquin (EC) at rates of 300-843 g ai/ha (0.7-1.9x
rate).  In these tests, fenazaquin residues were 0.06-0.40 ppm in/on 16
samples harvested at 21-23 DAT, and residues averaged 0.20 ppm.  As no
lemon samples were collected at the minimum PHI, none of the lemon field
trials are adequate.  However, the available orange field trials will
cover lemons as 5 of the 12 orange field trials were conducted on
mandarin-type tangerines.  Based on their size and morphology, mandarin
oranges are likely to have some of the highest residues of any of the
major types of citrus fruits.  In the current orange field trials,
residues in/on mandarin oranges were 0.20-0.40 ppm and averaged 0.27
ppm; whereas, residues in/on the larger Navel- or Valencia-type oranges
were 0.06-0.23 ppm and averaged 0.14 ppm. 

  

Adequate apple and orange processing studies are available.  In the
apple processing studies, the average processing factors were 1.7x for
wet pomace, 0.07x for juice and 0.5x for puree.  In the citrus
processing studies, the average processing were 0.07x for flesh (pulp),
3.2x for peel, 0.03x for juice and molasses, 0.1x for marmalade and 25x
for oil.  Although processing data are not available for dried citrus
pulp, the processing factor for peel (3.2x) can be used for dried pulp. 
As residues are confined primarily to the peel, the processing factor
for peel provides a conservative estimate of the processing factor for
dried pulp, which is a combination of the peel, seeds and pulp remaining
after juicing.  As residues did not concentrate in apple juice and
orange juice and molasses, separate tolerances are not required for
these commodities.  However, a separate tolerance is required on citrus
oil.  Based on the 25x processing factor for oil and HAFT residues of
0.40 ppm in/on oranges, a tolerance of 10 ppm should be proposed for
citrus oil.  Although residues also concentrated in wet apple pomace and
dried citrus pulp, separate tolerances are not required for these
feedstuffs as they are unlikely to be imported given their bulk and
limited value as feedstuffs.

5.1.7	Proposed Tolerances tc \l3 "5.1.7	Proposed Tolerances 

For the purpose of tolerance expression for this petition, the residue
of concern in plant and livestock commodities is parent fenazaquin.  For
risk assessment purposes, residues of concern in plant commodities
include parent fenazaquin and its dimer. The residue of concern in
animal commodities for tolerance enforcement and risk assessment is
parent fenazaquin. No tolerances are currently established for
fenazaquin.  The tolerances proposed by the petitioner are listed below
in Table 5, along with the Agency’s recommended tolerance levels. 

Given the wide range (0.7-1.9x) of use rates used to estimate residues
in/on apples, pears and citrus fruits at the worse-case use rates, the
tolerance recommendations are based on the maximum residue levels and
were not calculated using the tolerance harmonization worksheet.

The available apple and pear field trial data will be adequate to
support the proposed 0.2 ppm tolerances for residues of fenazaquin in/on
apples and pears.  The available orange field trial data, which include
field trials on mandarin oranges, are adequate and will support the
proposed 0.5 ppm tolerance for citrus fruits, except grapefruit.

  

Separate tolerances are not required for apple and orange juice as
residues do not concentrate in these commodities.  However, the citrus
processing studies indicate that fenazaquin residues concentrate on
average by 25x in citrus oil.  Therefore, a separate tolerance should be
proposed on citrus oil.  Based on the above processing factor and HAFT
residues of 0.40 ppm in/on oranges, a tolerance of 10 ppm would be
appropriate for citrus oil.  Although the available processing studies
indicate that fenazaquin residues can also concentrate in wet apple
pomace (1.7x) and dried citrus pulp (3.2x), separate tolerances are not
require for these commodities.  Given the bulk and limited value of wet
apple pomace and dried citrus pulp, these processed commodities are
unlikely to ever be imported into the U.S.

For purposes of this petition, tolerances for fenazaquin residues in
livestock commodities will not be necessary as there is no expectation
that residues will occur in those commodities. 

Table 5. 	Tolerance Summary for Fenazaquin.

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


Correct Commodity Definition

Apple	0.2	0.2	Adequate data are available

Pear	0.2	0.2	Adequate data are available

Citrus fruits	0.5	0.5	Adequate data are available.

Fruit, citrus, group 10, except grapefruit

Citrus oil	None	10	Based on HAFT residues of 0.40 ppm and an average
processing factor of 25x for citrus oil, a separate tolerance is
required for Citrus, oil

Apple, pomace, wet	None	None	Although residues were shown to concentrate
in wet apple pomace (1.7x) and dried citrus pulp (3.2x), tolerance are
not required for these feedstuff as they are unlikely to be imported.

Citrus, pulp, dried	None	None

	

5.1.8 International Residue Limits tc \l3 "5.1.8	International Residue
Limits  

  SEQ CHAPTER \h \r 1 There are no established or proposed Canadian,
Mexican or Codex MRLs for residues of fenazaquin in plant commodities
(Appendix I).  However, MRLs have been established for fenazaquin in/on
citrus fruits in a number of countries at the following levels:  0.01
mg/kg in Belgium, Germany, and Luxembourg; 0.05 mg/kg in the United
Kingdom; 0.2 mg/kg in Italy, Spain and Switzerland; 0.5 mg/kg in
Portugal and Taiwan; and 0.7 mg/kg in Korea.  There are also currently
MRLs for fenazaquin in/on apples at 0.1 mg/kg in Germany and in/on pome
fruits at 0.5 mg/kg in Taiwan.

      Dietary Exposure and Risk tc \l2 "5.2	Dietary Exposure and Risk  

DEEM-FCID™ model to form a conservative evaluation of exposure for
fenazaquin.  The acute dietary analysis made at the 95th percentile
indicate risk estimates are reasonably below the 100% of the aPAD
threshold level of concern for each population subgroup.  For the most
highly exposed population subgroup, children 1-2 years of age, acute
dietary risk was estimated to be 48% of the aPAD with an exposure of
0.047574 mg/kg/day.  In conjunction, chronic analysis yielded risk
estimates well below the 100% of the cPAD threshold level of concern for
each population subgroup.  Likewise, for children 1-2 years of age,
chronic dietary risk proved to be 25% of the cPAD with an exposure of
0.012690 mg/kg/day.  An overview summarizing the results of the acute
and chronic dietary assessments is presented in Table 6.  

Table 6.  Summary of Dietary Exposure and Risk for Fenazaquin

Population Subgroup	Acute Dietary

(95.0 Percentile)	Chronic Dietary	Cancer

	Dietary Exposure (mg/kg/day)	% aPAD1	Dietary Exposure

(mg/kg/day)	% cPAD1	Dietary Exposure

(mg/kg/day)	Risk

General U.S. Population	0.014857	15	0.003092	6.2	NA2	NA

All Infants (< 1 year old)	0.011808	12	0.004650	9.3	NA	NA

Children 1-2 years old3	0.047574	48	0.01269	25



Children 3-5 years old	0.034100	34	0.009100	18



Children 6-12 years old	0.020877	21	0.004865	9.7



Youth 13-19 years old	0.015223	15	0.002967	5.9



Adults 20-49 years old	0.010338	10	0.001967	3.9



Adults 50+ years old	0.008336	8.3	0.002020	4.0



Females 13-49 years old	0.011299	11	0.002177	4.4



1 Report %PADs to 2 significant figures.

2 Not Applicable (NA).

3 The values for the highest exposed population for each type of risk
assessment should be bolded.

 Anticipated Residue and Percent Crop Treated (%CT) Information tc \l2
"5.3	Anticipated Residue and Percent Crop Treated  

The DEEM-FCID™ acute and chronic analyses assume that fenazaquin
residues are in/on all registered food commodities at tolerance levels
and that 100% of all RACs are treated.  To support these unrefined
analyses, adequate data in the form of crop field trial studies for the
apple, pear, and citrus fruit RACs are relied upon (DP Barcode D329427,
D. Drew & D. Soderberg, 05/02/2007).  These studies present a
“worst-case” use pattern for these RACs from fenazaquin field trials
undertaken in several countries abroad.  A maximum application rate of
250 g ai/ha with a minimum Pre-Harvest Interval (PHI) of 28 days was
used for the apple and pear studies.  For the citrus fruit studies which
were comprised of orange and lemon field trials, a maximum application
rate of 450 g ai/ha with a minimum PHI of 21 days was used.  Although
none of the lemon field trials was adequate, a number of the orange
studies were conducted on mandarin-type tangerines which can be
translated to this commodity.   This is acceptable given the size and
morphology of the mandarin-type tangerines which are likely to have the
highest residue levels of any citrus fruit.  Subsequently, the results
of these studies indicate that residues in processed commodities will
not exceed the tolerances proposed for these RACs.  To account for the
dimer, a default residue value is specified at two times the tolerance
level to provide a conservative estimate for the fenazaquin dietary
assessment.  This approach was based on results from the apple
metabolism study which showed that dimer levels may approach levels of
parent fenazaquin via photolytic processes (MRID No. 45029914).  Details
of the dietary assessment are available in a separate document (DP#:
329427, P. Savoia, 02/05/07).   

6.0		Aggregate Risk Assessments and Risk Characterization tc \l1 "6.0 
Aggregate Risk Assessments and Risk Characterization 

There are no proposed or existing residential uses for fenazaquin.  The
proposed use is limited to apples, pears and citrus fruits exported to
the U.S. only.  The exposure/risk assessment is limited to dietary food
only (no aggregate).

7.0		Cumulative Risk Characterization/Assessment tc \l1 "7.0  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 fenazaquin and any other
substances.  For the purposes of this action, therefore, EPA has not
assumed that fenazaquin 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/.

8.0	    Data Needs and Label Requirements tc \l1 "8.0	Data Needs and
Label Requirements 

8.1	    Residue Chemistry tc \l2 "8.1	Residue Chemistry 

•	Although a general summary of the use directions on apples, pears
and citrus fruits was provided, additional information is required
detailing the maximum allowed use rates and minimum PHIs allowed for
apples, pears and citrus fruits in each country in which these uses are
allowed.   Representative labels (and translations) should be submitted
for each crop from the major growing regions (Europe, South America, and
Asia).

•	Radiovalidation data demonstrating the extraction efficiency of the
proposed single analyte enforcement methods were not submitted. 
However, the available data indicate fenazaquin tolerances may be
enforced using the existing FDA Multiresidue Methods in PAM, Vol I. 
Testing of fenazaquin through the multiresidue methods indicated that
fenazaquin was adequately recovered from whole oranges and from orange
oil. Radiovalidation data for the single analyte methods should be
submitted with future petitions.

•	For future petitions, the following information is needed for each
of the ILV studies:  (i) a description of the number of trials required
to obtain the reported recovery values; (ii) a description of any
problems encountered and a written description of any changes or
modifications that were made to the method during the ILV; (iii)
discussion of any steps considered critical; (iv) time required for
analysis of one set of samples; and (v) details of communications
between the independent laboratory and the method developers or others
familiar with the method.

•	The Agency strongly recommends that the petitioner develop and
validate (ILV and radiovalidation) an analytical enforcement method
capable of quantitating parent fenazaquin and its dimer prior to
conducting crop field trial studies to support any new uses.

•	Additional storage stability data are required on apples to support
the sample storage intervals from the tests conducted on pears and
apples in Argentina during 1993/94 and on apples in Chile during 1995. 
Data should be submitted demonstrating the stability of fenazaquin in
frozen apples for intervals up to 25 months.

•	A reference standard for fenazaquin must be submitted to the
National Pesticide Standards Repository.

•	As residues concentrate by 25x in orange oil, a separate tolerance
must be proposed for citrus oil.  Based on the above processing factor
and HAFT residues of 0.40 ppm, a tolerance of 10 ppm would be
appropriate. The petitioner should submit a revised Section F.

REFERENCES tc \l1 " REFERENCES 

HED: “Evaluation of the Carcinogenicity of Fenazaquin in Syrian Golden
Hamster and the Carcinogenicity/Mutagenic Potential of Fenazaquin.” 
Mary Manibusan, TXR No. 0054584, DP Barcode D328334, May 1, 2007

HED: “Fenazaquin.    SEQ CHAPTER \h \r 1 Request for Tolerances on
Imported Apples, Pears and Citrus Fruits.  Summary of Analytical
Chemistry and Residue Data.”  Danette Drew/David Soderberg,
Reregistration Branch 3; Chemist Petition Number 9E5059; DP Barcode:
329427; April 26, 2007

HED: “Fenazaquin: Acute and Chronic Aggregate Dietary Exposure
Assessment for Section 3 Registration Action on Imported Apples, Pears,
and Citrus Fruits.”  Peter Savoia, Reregistration Branch 3; PC
Code:04451; Decision Number: 302678; DP Number: 329427; Feb. 05, 2007.  

ATTACHMENTS

INTERNATIONAL RESIDUE LIMIT STATUS

Chemical Name: 4-[2-[4-(1,1-dimethylethyl)phenyl] ethoxy]quinazoline
Common Name:

Fenazaquin	X Proposed tolerance

 Reevaluated tolerance

 Other	Date: 1/31/07

Codex Status (Maximum Residue Limits)	U. S. Tolerances

    No Codex proposal step 6 or above

X No Codex proposal step 6 or above for the crops requested 	Petition
Number: 9E5059

DP Barcode: D329427

Other Identifier: 

Residue definition (step 8/CXL):   N/A	Reviewer/Branch: D. Drew/ RAB3

	Residue definition: parent only

Crop (s)1	MRL (mg/kg)	Crop(s) 	Recommended Tolerance (ppm)



Apple	0.2



Pear	0.2



Fruit, citrus, group 10	0.5











Limits for Canada	Limits for Mexico

X No Limits

    No Limits for the crops requested	    No Limits

X No Limits for the crops requested

Residue definition:  N/A	Residue definition: N/A

Crop(s)	MRL (mg/kg)	Crop(s)	MRL (mg/kg)





















Notes/Special Instructions:





APPENDICES

Appendix A: Toxicology Assessment

A1	Toxicology Data Requirements

The requirements (40 CFR 158.340) for imported foods for fenazaquin are
in the table below.  Use of the new guideline numbers does not imply
that the new (1998) guideline protocols were used.

Table A.1.1.  Toxicology Data Requirements for Food Use - Fenazaquin

  SEQ CHAPTER \h \r 1 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 (dog)

870.3200  28-Day Dermal

870.3465  28-Day Inhalation	yes

yes

no

no	yes

yes

---

---

870.3700a  Developmental Toxicity (rat)

870.3700b  Developmental Toxicity (rabbit)

870.3800  Reproduction	yes

yes

yes	yes

yes1

yes

870.4100a  Chronic Toxicity (rat)

870.4100b  Chronic Toxicity (dog)

870.4200a  Oncogenicity (rat)

870.4200b  Carcinogenicity (hamster)

870.4300  Chronic Toxicity/Carcinogenicity (rat)	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—Microneucleus – mammalian   

870.5550  Mutagenicity—Unscheduled DNA - mammalian	yes

yes

yes

yes

yes	yes

yes

yes

yes

yes

870.6100a Acute Delayed Neurotox. (hen)

870.6100b 90-Day Neurotoxicity (hen)

870.6200a Acute Neurotox. Screening Battery (rat)

870.6200b 90 Day Neurotox. Screening Battery (rat)

870.6300   Developmental Neurotoxicity	no

no 

CR

CR

no	---

--- 

NR

NR

---

870.7485  General Metabolism

870.7600  Dermal Penetration	yes

no	yes

---

CR = Conditionally required if acute oral, dermal, or inhalation studies
showed neuropathy or neurotoxicity (as per CFR 158.340)

NR = Not recommended at this time 

A.2	Toxicity Profiles

  SEQ CHAPTER \h \r 1 Table A.2.1. Acute Toxicity Data - Fenazaquin
Technical

Study/ Species	MRID	Results	Toxicity  Category

870.1100 Acute Oral (Rat)	46684003	LD50 = 134/138 mg/kg (male/female)	II

870.1200 Acute Dermal, Rabbits	N/A



870.1300 Acute Inhalation, Rats	N/A



870.2400 Primary Eye Irritation, Rabbits	N/A



870.2500 Primary Skin Irritation, Rabbits	N/A



870.2600 Dermal Sensitization, Guinea pig	N/A



Table A.2.2	Subchronic, Chronic and Other Toxicity Profile - Fenazaquin
Technical

Guideline No. 	Study Type	MRID No. (year)/ Classification /Doses	Results

870.3100

	90-Day oral toxicity (rat) (Fischer 344 from Charles River Laboratories
Inc., Wilmington, MA)	45029904 (1992)

Acceptable/guideline

0, 15, 45, 150, or 450 ppm 

M: .0, 1.0, 3.0, 9.6, and 28.7 mg/kg/d 

F: 0.0, 1.2, 3.5, 11.5, and 33.0 mg/kg/d	NOAEL = 9.6 mg/kg/day

LOAEL = 28.7 mg/kg/day based on decreased body weight, body weight gain,
and food consumption.

870.3100

	90-Day oral (gavage) toxicity (rat) (Fischer 344 from Charles River
Laboratories Inc., Wilmington, MA)	45029905 (1992)

Acceptable/guideline

0, 1, 3, 10, or 30 mg/kg/day

	NOAEL = 10 mg/kg/day

LOAEL = 30 mg/kg/day based on decreased body weight, body weight gain,
and food consumption/efficiency.

870.3100

	90-Day oral toxicity (hamster)	45029903 (1992) Acceptable/guideline

Males: 0, 5, 25, 75, or 150 mg/kg/day

Females: 0, 5, 25, 50, or 100 mg/kg/day	NOAEL = 25 mg/kg/day

LOAEL = 75/50 mg/kg/day (M/F) based on decreased body weight and
testicular atrophy.

870.3150

	90-Day oral toxicity (dog)	45029901 (1992) Acceptable/guideline

0, 1, 5, or 15 mg/kg/day

	NOAEL = 5 mg/kg/day

LOAEL = 15 mg/kg/day based on decreased body weight, body weight gain,
and food consumption/efficiency.

870.3700a

	Prenatal developmental (rat) (Crl:CD® (SD) BR from Charles River
Laboratories Inc., Portage, Michigan)	45029911 (1989)
Acceptable/guideline

0, 3, 10, 40 mg/kg/d	Maternal NOAEL = 10 mg/kg/day

LOAEL = 40 mg/kg/day based on findings (as early as GD 6-9) of decreased
body weight gain, food intake, and food efficiency.

Developmental NOAEL = 40 mg/kg/day

LOAEL = > 40 mg/kg/day.

870.3700b

	Prenatal developmental (rabbit)	45029912 (1990) Unacceptable/guideline

0, 3, 13, 60 mg/kg/d	Maternal NOAEL = 60 mg/kg/day

LOAEL = > 60mg/kg/day based on lack of findings.

Developmental NOAEL = 60 mg/kg/day

LOAEL = > 60 mg/kg/day based on lack of findings.

870.3800

	Reproduction and fertility effects (rat)

(Crl:CD® (SD) BR from Charles River Breeding Laboratories, Raleigh, NC)
46684001 (1991) Acceptable/guideline

0, 1, 5, or 25 mg/kg/d	Parental/Systemic NOAEL = 5 mg/kg/day

LOAEL = 25 mg/kg/day based on excessive salivation and decreased body
weight/weight gain and food intake.

Reproductive NOAEL = 25 mg/kg/day

LOAEL = >25 mg/kg/day.

Offspring NOAEL = 5 mg/kg/day

LOAEL = 25 mg/kg/day based on decreased weight gain during lactation.

870.4300

	Chronic toxicity/ Carcinogenicity

Rat (Fischer 344 from Taconic Laboratory Animals and Services,
Germantown, N.Y)	45029907 (1992) Acceptable/guideline

0, 10, 100, 200, or 400/450 (males/females) ppm

M: .0.0, 0.46, 4.5, 9.2, and 18.3 mg/kg/d 

F: 0.0, 0.57, 5.7, 11.5, and 25.9 mg/kg/d	NOAEL = 9.2 mg/kg/day

LOAEL = 18.3 mg/kg/day based on decreased body weight, body weight gain,
and food consumption/efficiency.

870.4100

	Chronic toxicity (dog)	45029906 (1993) Acceptable/guideline

0, 1, 5, or 12 mg/kg/d	NOAEL = 5 mg/kg/day

LOAEL = 12 mg/kg/day based on decreased body weight, body weight gain,
and food consumption/efficiency.

870.4200

	Carcinogenicity

(hamster)	45029913 (1992) Acceptable/guideline 

0, 2, 15, or 30/35 (males/ females) mg/kg/d	NOAEL = 2/15 mg/kg/day (M/F)

LOAEL = 15/35 mg/kg/day (M/F) based on decreased body weight (F) and
body weight gain (M/F)-food consumption was not recorded.

No evidence of carcinogenicity



870.5100

	Gene Mutation

Bacterial reverse mutation assay	44742909 (1989)

μg/mL in the absence of cytotoxicity with precipitation above this
concentration.



870.5300

	Gene Mutation

Mammalian cell culture (mouse lymphoma cells)	44742908 (1989)

Acceptable/guideline	Negative –S9 severely cytotoxic at concentrations
up to10 µg/mL

Positive + S9 at concentrations (up to 12 µg/mL) that were severely
cytotoxic (10-20% survival) 

 

870.5375 	Cytogenetics

Chromosomal aberrations (CHO cells)	44742907 (1989)

≈50% (1 µg/mL-S9; 60 µg/mL+S9).  Compound precipitation was evident
at levels ≥ 24 µg/mL +/-S9.

 

870.5395

 	Micronucleus Assay (mouse)  	44742904 (1989)

Acceptable/guideline	Negative for clastogenic/aneugenic activity in
mouse bone marrow up to the highest dose tested in males/females
(1600/1200 mg/kg, repeated on two days).  In a preliminary study, the
median lethal doses (MLD) were 3191/ 2430 mg/kg (M/F).

870.5915	In vivo SCE Assay (mouse)	44742905 (1989)

Unacceptable/guideline (each data point had 3 males which is lower than
the guideline recommended 5/sex/dose)	Negative in this cytogenetic assay
(no increase in SCE) of bone marrow from male CD-1 mice treated with
doses up to levels that produced death (2000 mg/kg).

870.5550 	In vitro UDS Assay 

	44742906 (1989)

Acceptable/guideline	Negative up to cytotoxic concentrations (≥0.5 to
1.0 µg/mL).

No Guideline	In viro UDS Assay 	45029908 (1989)

Acceptable/non-guideline	Negative for DNA damage and repair in this in
vivo/in vitro test system up to the maximum tolerated dose (600 mg/kg). 

870.7485

	Metabolism and pharmacokinetics

(species)	44742901 (1992)

Unacceptable/guideline

	Irrespective of dose, most of an orally administered radiolabeled
fenazaquin was in rat excreta (89.5-107.7%) at 168 hours with
approximately 20% of the radiolabel in urine.  After initial uniform
distribution, about 0.5-1.6% of the dose was in the carcass and below
0.04% of the dose in each tissue.  There was no radiolabel in the
expired air and no evidence for bioaccumulation.  Based on excretion and
tissue residue data, bioavailability is conservatively estimated at
about 20% of an administered dose.

Non-metabolized fenazaquin was higher in feces (1.0-15.0% of
administered dose) than in urine (below 0.5% of dose) and some of the
major metabolites were identified including AN-1 (urine) in addition to
the fecal metabolites F-1, F-2 and F3.  The metabolic pathway of
fenazaquin involved cleavage of the ether bond, resulting in the
formation of the respective alcohol (4-OH quinazoline metabolite) and
carboxyl acid (AN-1) derivatives.  Other biotransformation reactions
included oxidation of one of the methyl groups on the alkyl side chain
to produce either an alcohol (F-1) or carboxylic acid (F-2) metabolites.
Finally, hydroxylation at the O-ether alkyl moiety of F-1 or the
2-position of the quinazoline ring of F-2 resulted in F-1A and F-3
metabolites, respectively.

Non-guideline	Special studies:

Potential to induce hepatic hypertrophy and peroxisome acyl- CoA oxidase
activity in mice	44742903 (1993)

Acceptable/non-guideline	Fenazaquin and several of its analogs (with
varying susceptibilities to metabolism of the ether bond or the
alkylbenzene substituents) were assessed for their ability to increase
liver peroxisomal fatty acyl-CoA oxidase (FAO, a marker of peroxisomal
proliferation) and relative liver weight in groups of five CD-1 female
mice.   The FAO peroxisomal activity data indicate that oxidation of the
t-butyl substituent on the alkylbenzene moiety (to the corresponding
carboxylic acid) of fenazaquin and related compounds appears to be the
critical step for heptatocellular peroxisome proliferation.



A.3	Executive Summaries TC \l2 "A.3  Executive Summaries 

A.3.1	Subchronic Toxicity

870.3100	90-Day Oral Toxicity (Gavage) – Rat (Fischer 344 from Charles
River Laboratories Inc., Wilmington, MA)

 EXECUTIVE SUMMARY:  In a 90-day oral toxicity study (MRID 45029905),
EL-436 ((99% a.i.) was administered to 15 F344 rats/sex/dose group daily
by gavage at dose levels of 0, 1, 3, 10, or 30 mg/kg/day for 90 days. 
In addition, 10 rats/sex in the control and high-dose groups were
maintained 1-month post treatment to evaluate the reversibility of
observed effects.

There were no compound related effects on survival, clinical signs,
ophthalmic, hematologic, or urinary parameters.   Statistically
significant decreases in body weight (8%-12% in males) and body weight
gain (18% and 13% in males and females, respectively) were noted only
among high-dose rats.  The high dose also resulted in a statistically
significant decrease in food consumption (4%-8%) and food efficiency
(10% and 12%) in both sexes. Following a recovery period these
parameters returned to normal.  Slight changes in clinical chemistry
parameters observed in high–dose male and female rats were reversible
1-month post treatment.  Statistically significant increases in absolute
and relative liver and adrenal weight in mid- or high-dose male and
female rats (6%-20% for liver and 10%-42% for adrenal, respectively)
observed during the treatment period were reversible during the post
treatment period.   However, these findings were not supported by
histopathological changes.  Changes in serum enzyme activity levels and
liver weight were considered adaptive changes in response to the
treatment. The LOAEL for EL-436 in male and female rats is 30 mg/kg/day
based on decreases in body weight gain, food consumption and food
efficiency in both sexes.  The NOAEL is 10 mg/kg/day.

This 90-day oral toxicity study in the rat is acceptable/guideline and
satisfies the guideline requirement for a 90-day oral toxicity study
(OPPTS 870.3100; OECD 408) in rodent species.

870.3100	90-Day Oral Toxicity (Dietary Feeding) – Rat  (Fischer 344
from Charles River Laboratories Inc., Wilmington, MA)

EXECUTIVE SUMMARY: In a 90-day oral toxicity study (MRID 45029904)
EL-436 (fenazaquin) (98.4% a.i., lot # 271MH8) was administered to 10
Fischer 344 rats/sex/dose in the diet at dose levels of 0.0%, 0.0015%,
0.0045%, 0.015%, or 0.045% (equivalent to 0.0, 1.0, 3.0, 9.6, and 28.7
mg/kg bw/day for males and 0.0, 1.2, 3.5, 11.5, and 33.0 mg/kg bw/day
for females, respectively). 

All rats survived to scheduled termination, and no treatment-related
clinical signs were noted. In the high dose group, body weight of males
was significantly reduced by 10-14% throughout the study, and overall
body weight gain was reduced by 21%. Body weight of high dose females
was significantly reduced by 5-7% during most of the study, and overall
body weight gain was reduced by 14%. Food consumption by the high dose
males and females was significantly reduced by 10 to 21% throughout the
study, and overall food consumption was reduced by 14% and 11%,
respectively, compared to that of the controls. Food efficiency in the
high dose males was significantly reduced by 16% at week one and by 8%
at study end; food efficiency for all other treated groups was
comparable to that of controls.

Hematology results for all groups were unremarkable. Changes in clinical
chemistry included increased serum enzyme activities (61-75% over
controls) in the high dose males and increased hepatic microsomal enzyme
activities (21-80%) in mid and high dose males and females. Due to a
lack of histological correlates and minimal increases in liver weight,
these changes in isolation are considered an adaptive response rather
than a toxic effect. Urinalysis was unremarkable. 

Changes in absolute organ weight in the mid and high dose groups were
generally less than 10%, and not considered biologically significant.
Increased relative organ weights (7-17% over controls) for those groups
reflected the decreased body weights. No histological correlates were
seen for the organ weight changes. Gross pathology was unremarkable, and
no treatment-related histopathologic changes were seen.

The LOAEL for fenazaquin in rats is 0.045% in the diet (28.7 mg/kg
bw/day for males and 33.0 mg/kg bw/day for females) based on decreases
in body weight, body weight gain, and food consumption. The NOAEL is
0.015% in the diet (9.6 mg/kg bw/day for males, 11.5 mg/kg bw/day for
females).

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

90-Day Oral Toxicity – Hamster

EXECUTIVE SUMMARY: In a 90-day oral toxicity study (MRID 45029903)
EL-436 (purity 98%, batch no. Lot ACD13041) was administered to 15
Syrian golden hamster [Lak:LVG(SYR)]/sex/dose by gavage at doses of 0,
5, 25, 75, or 150 mg/kg/day for males and 0, 5, 25, 50, or 100 mg/kg/day
for females.  Control animals received 5 ml/kg of the vehicle (10%
aqueous acacia solution).

There were no treatment related mortalities or clinical signs and no
difference between the controls and the EL-436 treated groups in
urinalysis.  Food consumption data from the first 10-weeks of the study
were considered unreliable due to excessive spillage.

There were slight dose-related increases (22-69%) in liver microsomal
p-nitroanisole-o-demethylase enzyme activity in all animals that
received EL-436 at ≥ 25 mg/kg/day but no changes were seen in hepatic
peroxisomal β-oxidation activity (fatty acyl CoA oxidase).  Small
changes occurred in some hematology parameters (≤ 6% decrease) among
treated hamsters but, the changes were within the normal ranges of
biological variation and were not considered toxicologically meaningful.


The greatest effect of treatment was on body weight.  At termination,
the body weight in males decreased (p<0.01) 16 and 23% relative to the
controls in the 75 and 150 mg/kg/day groups.  Similarly, body weight in
females decreased (p<0.01) 19 and 28% relative to the controls in the 50
and 100 mg/kg/day groups, respectively.  The body weight gains from the
same treated groups were also substantially reduced 54 and 74% less than
the controls in males and 39 and 61% less than the controls in females,
respectively.  Because of growth retardation, the absolute organ weights
of kidney, heart, and spleen were decreased in animals at dose levels
≥ 50 mg/kg/day.  The large decrease in absolute (42-49%) and relative
weights (27-36%) of testes and prostate are considered treatment-related
in males administered 75 and 150 mg/kg/day EL-436.  These findings are
corroborated by histopathology findings of increased testicular
hypospermatogenesis (0/15, 1/15, 2/15/, 5/15/ and 8/15 in control
through the high dose groups, respectively, moderate to severe at the
top two doses).  

Under the conditions of the study, the LOAEL for EL-436 in male hamsters
is 75 mg/kg/day based on decreased body weight, reduced testes and
prostate weights, and testicular hypospermatogenesis.  The LOAEL is 50
mg/kg/day in females based on decreased body weight.  The NOAEL for
EL-436 is 25 mg/kg/day for both males and females.

  SEQ CHAPTER \h \r 1 This 90-day oral toxicity study in the rat is
Acceptable/Guideline and does satisfy the guideline requirement for a
90-day oral toxicity study (OPPTS 870.3100; OECD 408) in the hamster.

90-Day Oral Toxicity – Dog

EXECUTIVE SUMMARY: In a 90-day oral toxicity study (MRID 45029901,)
XDE-436 (98.1% a.i., lot# 435MH8) was administered to 4 Beagle
dogs/sex/dose in diet at dose levels of 0, 1, 5, or 15 mg/kg bw/day at
constant dosing.  All percentages presented are changes from controls.

No toxicological effects on organ weight, clinical chemistry, clinical
signs, hematology, gross and histopathology were related to the dietary
exposure of XDE-436 to beagle dogs.  At 15 mg/kg/day dose, significant
reductions in body weight of males (6 to 12%) and females (4 to 11%)
were reported.  At the high dose, overall body weight gain decreased in
males (76%) and females (73%); mean food consumption was reduced in
males (6 to 24%) and females (10 to 27%).  Food efficiency values were
also significantly decreased in high dose groups, males (72%) and
females (67%).  These specific body weight and food consumption effects
have been similarly reported in the chronic 1-year dog study of  XDE-436
dietary exposure with the same percentage of reduction in the first 90
days.

The toxicologically significant body weight changes correspond to the
decrease in food consumption reported for the high dose group, which
appears to be due only in part to a reduction in palatability of the
diet.  Based on the toxicological findings associated with XDE-436
90-day dietary exposure to beagle dogs, the NOAEL is established at 5
mg/kg/day and the LOAEL is established at 15 mg/kg/day based on
reductions of body weight, body weight gain, food consumption and food
efficiency.  

This 90-day oral toxicity study in the dog is acceptable (guideline) and
satisfies the guideline requirement for a 90-day oral toxicity study
(OPPTS 870.3150; OECD 409) in non-rodent species.  There were several
minor deficiencies identified in the study, but these deficiencies would
not be expected to alter the study conclusion.

A.3.2	Prenatal Developmental Toxicity

870.3700a Prenatal Developmental Toxicity Study – Rat

EXECUTIVE SUMMARY:  In a developmental toxicity study (MRID 45029911)
EL-436 (Fenazaquin; 98% a.i., Lot ACD13041) was administered to 25 mated
female CD [Crl:CD®(SD)] rats/dose by gavage in 10% (w/v) aqueous acacia
solution at dose levels of 0, 3, 10, or 40 mg/kg bw/day on gestation
days (GDs) 6 through 17.  On GD 20, dams were sacrificed and necropsied.
 Gravid uterine weights, corpora lutea counts, and the numbers and
positions of implantations, live and dead fetuses, and early and late
resorptions were recorded.  All fetuses were weighed, sexed, and
examined for external anomalies.  Approximately one-half of the fetuses
from each litter were subjected to visceral examination, and the
remaining one-half were subjected to skeletal examination.   

There were no deaths, abortions, or treatment-related clinical signs or
gross pathological findings.  At the 40 mg/kg bw/day dose level, mean
body weight gain was markedly decreased throughout treatment (62%, 26%,
and 12% less than controls during GDs 6-9, 10-13, and 14-17,
respectively; p<0.05), and a compensatory increase was seen during GD
18-19 (+26%; p<0.05).  These changes corresponded to decreased food
consumption by this group throughout treatment (9-15% less than
controls; p<0.05), with subsequent increased food consumption during GD
18-19 (+10%; p<0.05). 

The Maternal Toxicity LOAEL for Fenazaquin in CD rats is 40 mg/kg
bw/day, based on decreased food consumption and decreased body weight
gain.  The Maternal Toxicity NOAEL is 10 mg/kg bw/day.   

There were no treatment-related increases in fetal deaths/resorptions,
and there were no treatment-related effects on fetal sex ratios, fetal
body weight, or the incidences of fetal runts.   There was no evidence
of altered fetal ossification rates.  Malformations were observed in
1/24, 3/25, 1/22, and 1/23 litters from the control, low-, mid-, and
high-dose groups, respectively, and there were no significant increases
in litter or fetal incidences of any individual structural abnormalities
for any treated group.  

The Developmental Toxicity LOAEL for Fenazaquin in CD rats is greater
than 40 mg/kg bw/day, and the Developmental Toxicity NOAEL is equal to
or greater than 40 mg/kg bw/day. 

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

870.3700b	Prenatal Developmental Toxicity Study – Rabbit

EXECUTIVE SUMMARY:  In a developmental toxicity study (MRID 45029912,
EL-436 (Fenazaquin) (98% a.i., Batch/Lot # ACD13041) was administered to
groups of 20 presumed pregnant rabbits by gavage at dose levels of 0, 3,
13, or 60 mg/kg bw/day from gestation days (GD) 6-18.  The does were
sacrificed on GD 28.  The ovaries were removed and the corpora lutea
were counted.  The uteri were removed, weighed, and the number and
distribution of implantation sites, resorptions, and live and dead
fetuses were recorded.  Uteri with no evidence of implantation sites
were stained with 10% aqueous ammonium sulfide to identify the presence
of implantation scars.  Live fetuses were weighed, examined for
external, visceral, and skeletal abnormalities, and the sex was
determined by internal examination.

No treatment-related death occurred and no treatment-related clinical
signs were observed in does administered any dose of the test material. 
One doe in the 13-mg/kg/day group and six does in the 60-mg/kg/day group
died or were killed because of causes unrelated to the test material. 
Maternal body weight, weight gain, and net weight gain of does
administered the test material were similar to those of the control
group.  Maternal food consumption was not affected by treatment with the
test material; a 24% (p≤0.05) reduction in food consumption from GD
6-12 in the 60-mg/kg/day group is not considered treatment related.  

Therefore, the Maternal Systemic Toxicity LOAEL for EL-436 in rabbits
was not determined (greater than 60 mg/kg/day).  The Maternal Systemic
Toxicity NOAEL is equal to or greater than 60 mg/kg/day.

No treatment-related effect was observed on number of live
fetuses/litter, number or percentage of resorptions/litter (early, late,
and total), fetal weight (male, female, or combined), or percent male
fetuses/litter.  Three litters were aborted between GD 23 and 26, one
from the 13-mg/kg/day group and two from the 60-mg/kg/day group.  No
increase in the number or percentage of fetuses/litter or the number or
percentage of litter with malformations, variations, or deviations was
observed in groups administered the test material.

Therefore, the Developmental Toxicity LOAEL for EL-436 in rabbits was
not determined (greater than 60 mg/kg/day).  The Developmental Toxicity
NOAEL is equal to or greater than 60 mg/kg/day.

The developmental toxicity study in the rabbit is classified
Unacceptable/guideline and does not satisfy the guideline requirement
for a developmental toxicity study (OPPTS 870.3700; OECD 414) in
rabbits.  In the absence of any treatment-related maternal or
developmental toxicity, the doses selected were not adequate for testing
developmental toxicity in the rabbit.  The limit dose was not tested in
this study.

A.3.3	Reproductive Toxicity

870.3800 Reproduction and Fertility Effects – Rat

EXECUTIVE SUMMARY: In a two-generation reproduction study (MRID
46684001), EL-436 (fenazaquin, 98.4% a.i., lot # 241MH8) was
administered daily by gavage to 30 male and 30 female Crl:CD® (SD)BR
rats/group at doses of 0, 1, 5, or 25 mg/kg/day.  An additional 10 F1
males and females/group were maintained on study during premating, but
were sacrificed prior to breeding.  One litter was produced in each
generation.  F0 and F1 parental males were administered the vehicle
(aqueous 10% acacia) or test article for at least 70 days prior to
mating and during cohabitation; F0 and F1 parental females were
administered vehicle or test article for 70 days prior to mating and
throughout mating, gestation, and lactation.

≤ 0.01).  This finding was not seen in control animals and occurred at
low incidence in the low- and mid-dose groups (0-7 animals/group).  The
incidence of excessive salivation was also significantly increased in
high-dose females of both generations during gestation and in high-dose
F0 females during lactation.

≤ 0.05 or 0.01) than that of controls through premating day 43 for
males (↓4-10%) and day 64 for females (↓4-7%).  For the remainder of
premating, body weight was similar to the control level.  The only
effect on body weight gain was during the first week of premating when
weight gain by the high-dose animals was decreased by 12% for males and
9% for females (both p ≤ 0.01).  Thereafter, weight gain by the
treated groups during premating was occasionally slightly greater than
or less than that of the controls.  Food consumption by the high-dose F1
males and females was significantly less (p ≤ 0.01; ↓7-8%) during
the second week of treatment; no other effects on food consumption were
seen.  Body weight, body weight gain, and food consumption by the low-
and mid-dose F0 males and F1 males and females were similar to those of
the controls during the premating interval.

≤ 0.01; ↑5%) absolute body weight on lactation day 21 compared with
the controls.  Correspondingly, body weight gain by the high-dose F0
females was significantly greater than that of the controls during
lactation.  Food consumption by the high-dose F0 females was not
affected by treatment during lactation.

Testes weight was not affected by treatment.  Gross necropsy was
unremarkable and no treatment-related microscopic lesions were found in
tissues from the reproductive tract of males or females of either
generation.

The Parental Systemic Toxicity LOAEL for EL-436 in male and female
Crl:CD® (SD)BR rats is 25 mg/kg bw/day based on clinical signs of
toxicity and transient decreases in body weight, weight gain, and food
consumption.  The Parental Systemic Toxicity NOAEL is 5 mg/kg bw/day. 

No dose- or treatment-related differences in number of litters, number
of pups/litter, pup survival, or pup sex ratio were observed between the
treated and control groups of either generation.  No treatment-related
clinical signs of toxicity were observed in the pups during lactation.

No statistically significant differences in absolute body weight were
seen between offspring in the treated and control groups of either
generation.  Pup body weight data were not separated by sex.  Weight
gain by the pups in the high-dose group of both generations was
decreased by 11-13% during lactation days 4-7 with no compensation
evident during the remainder of lactation.  This lower weight gain is
considered treatment-related and is the likely reason absolute body
weight of the high-dose F1 animals was less than that of the controls
during the early phase of premating.

The Offspring/Developmental Toxicity LOAEL for EL-436 in male and female
Crl:CD® (SD)BR rats is 25 mg/kg/day based on reduced body weight gain
during lactation days 4-7.  The Offspring/Developmental Toxicity NOAEL
is 5 mg/kg bw/day. 

No treatment-related differences in pre-coital interval, number of
pregnant females, gestation length, or number of whole litter losses
were seen between the treated and control groups of either generation
during litter production.  Estrous cyclicity and sperm parameters were
not evaluated.  

The Reproductive Toxicity NOAEL for EL-436 in male and female Crl:CD®
(SD)BR rats is greater than or equal to 25 mg/kg bw/day and the
Reproductive Toxicity LOAEL is greater than 25 mg/kg/day.  

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

A.3.4	Chronic Toxicity

870.4100a  Chronic Toxicity – Rat

A combined chronic toxicity/carcinogenicity study (870.4300) in rats is
included in section A.3.5 below.

870.4100b Chronic Toxicity – Dog

EXECUTIVE SUMMARY: In a chronic toxicity study (MRID 45029906), XDE-436
(98.1%, Lot #435MH8) was administered to 4 Beagle dogs /sex/dose in the
diet at constant dose levels of 0, 1, 5 or time weighted average 12
mg/kg/day.  On day 95, the initial high dose level of 15 mg/kg/day was
reduced to 10 mg/kg/day based on reduced palatability of the diet.  The
time weighted average test material consumed by this dose group was
calculated to be 12 mg/kg/day and is referred to on the tables and
throughout the report as the high dose level for approximately 365 days.

Animals were evaluated for clinical appearance, body weight, feed
consumption, feed efficiency, clinical chemistry, hematology,
urinalysis, selected organ weights, opthalmological, gross and
histopathological appearance of tissues.  All animals survived to study
termination and there were no clinical signs of toxicity.  Overall body
weight gains for males at the high dose were decreased (85% from
controls) and females in the high dose (89% from controls). 

Mean food consumption values among treated groups were highly variable
throughout the study period.  Lowered feed consumption was noted on day
1-8 (week 1) in the high dose male and female dogs (39% and 44% from
controls, respectively).  Between day 87-94 in both high dose male and
female dogs, a similar decrease in food consumption was reported (10%
and 12% from controls, respectively).  Changes in body weight and food
consumption values are consistent with those effects projected by the
two-week repeated dose study (MRID 45029902) and similar to those
reported in the 13-week subchronic dog dietary feeding study (MRID
45029901). 

Feed efficiency values also reflect an increase in toxicity from
exposure to XDE-436, with a significant decrease in the high dosed males
in the first 90 days (96% from controls).  Females, however, did not
show a remarkable change in feed efficiency except in the mid dose (27%
from control).

The NOAEL for XDE-436 was established at 5 mg/kg/day and the LOAEL was
established at the time weighted average of 12 mg/kg/day based on
toxicologically relevant body weight reductions, decreased food
consumption and feed efficiency.

This chronic study in the dogs is an acceptable guidelines study and
satisfies the guideline requirement for a chronic oral study [OPPTS
870.4100, OECD 452] in dogs.  There were several minor deficiencies in
the study that are not serious enough to invalidate or detract from this
well conducted study and would not be expected to alter the study
conclusions.

A.3.5	Carcinogenicity

870.4200b Carcinogenicity (dietary feeding) – Hamster

EXECUTIVE SUMMARY:

In a carcinogenicity study (MRID 45029913), EL-436 (Fenazaquin, 97.28%,
a.i., Lot No. ACD13041) was administered orally by gavage to 100 Syrian
Golden hamsters/sex in the control group or 80 Syrian Golden
hamsters/sex/dose in treated animals at dose levels of  2, 15, or 30
(males only) and 35 (females only) mg/kg/day for 18 months. Supplemental
studies were included to provide justification in using the hamster in a
carcinogenicity study (MRID 44742910) and to provide historical data on
the incidence of adrenocortical adenomas in hamsters (MRID 43798702).  

significant (p≤0.01) decrease in body weight in the 15 and 30
mg/kg/day males with the decreases in the15 mg/kg/day males being
within10% of controls and ranging from 9-20% less than controls in the
30 mg/kg/day males. A statistically significant (p≤0.01) decrease in
body weight gain was also observed in the 15 and 30 mg/kg/day males. In
weeks 0-24, body weight gain was 19 and 42% less than controls in the 15
and 30 mg/kg/day males, respectively. The males in the 15 mg/kg/day
group had body weight gain similar to controls during the second year of
treatment and overall were comparable to controls; however, the 30
mg/kg/day males continued to have decreased body weight gain and overall
gained 40% less weight than the controls. 

Treated females had statistically significant (p≤0.01) decreases in
body weight and body weight gain in the highest dosed (35 mg/kg/day)
group only. The 15 mg/kg/day females had some sporadic differences but
overall were similar to controls. The 35 mg/kg/day females had
significant body weight loss (11-14%) in the first 6 months of
treatment, but body weight was comparable to controls by the end of the
study. Mean body weight gain was decreased compared to controls, 23% in
weeks 0-13, 28% in weeks 0-24 and 21% in the first year but then was
similar in the second year.

Effects on hematology, clinical chemistry and organ weights that were
statistically significant were secondary to the incidence of amyloidosis
and/or enteritis and not treatment-related. 

The lowest-observed-adverse-effect level (LOAEL) for EL-436 in hamsters
was 15 mg/kg/day in males and 35 mg/kg/day in females based on decreases
in body weight (F) and body weight gain (M/F).  The
no-observed-adverse-effect level (NOAEL) was 2 mg/kg/day for males and
15 mg/kg/day for females.

At the doses tested, there was not a treatment related increase in tumor
incidence when compared to controls. An increase in adrenocortical
adenomas in females was observed but may not be considered associated
with treatment as this is a common tumor in aged hamsters, and the
incidence was still within historical data range. Dosing was considered
adequate based on decreased body weight and body weight gain.

This carcinogenicity study in hamsters is Acceptable/Guideline and
satisfies the guideline requirement for a carcinogenicity study [OPPTS
870.4200; OECD 451] in hamsters.  Despite the enteritis and
administration of antibiotics, the study is considered acceptable based
on the adequacy of dosing based on evidence of systemic toxicity,
acceptable survival rate at 17 months, and lack of evidence for
tumorigenicity in two species, hamsters and rats.  This conclusion was
also supported by Senior Cancer Experts at a meeting on March 22, 2007.

870.4300 Combined Chronic Toxicity/Carcinogenicity Study – rat

EXECUTIVE SUMMARY:

In a combined chronic/carcinogenicity study (MRID 45029907) EL-436
(Fenazaquin, 98.5%, a.i.; Lot No. ACD13041) was administered to sixty
Fischer 344 rats/sex/dose in the diet for two years at concentrations of
0, 0.001%, 0.01%, 0.02% or 0.04% (males) or 0.045% (females) equivalent
to 0, 0.46, 4.5, 9.2 and 18.3 mg/kg bw/day in males and 0, 0.57, 5.7,
11.5 and 25.9 mg/kg bw/day in females, respectively. 

≤0.01 or p≤0.05) in body weight was observed in male rats fed the
0.02 and 0.04% diets throughout the study, but the initial weight on day
0 was much lower than controls. The body weight in the 0.02% males
remained less than that of controls during the study but was within 10%;
the 0.040% males were within 10% of controls in the first year but were
12-14% less than controls in the second year. Mean body weight gain in
the 0.02% males was statistically significantly (p≤0.01 or p≤0.05)
decreased in the first week (14%), but was within 10% that of controls
for the remainder of the study. In the 0.04% males, mean body weight
gain was affected the most during the first week when the rats gained
27% less than controls; this trend continued throughout the first and
second year with these rats gaining 12-18% less than controls. Overall,
there was a 14% decrease in body weight gain in the males fed the 0.04%
diet compared to controls. 

≤0.01) decreases in body weight and body weight gain were observed in
the 0.02% group but were within 10% of controls, except for a 21%
decrease observed from weeks 13-50. In the 0.045% females, body weight
decreased in the first year but was within 10% of control values. During
year two, the females fed the 0.045% diet had body weights that were
decreased 14-17% from controls.  The 0.045% females consistently had
less body weight gain (17-31%) compared to the controls throughout the
entire study with an overall decrease of 20%.  A corresponding
statistically significant decrease in cholesterol and triglycerides were
observed in the 0.02, 0.04 (males) and 0.045% (females) but this is not
considered an adverse effect.  Food consumption and efficiency of food
utilization (EFU) were statistically and toxicologically decreased in
the 0.045% females and 0.04% males with the effects being less in the
males. Like the body weight and body weight gain, males and females in
the 0.02% groups had decreased food consumption and EFU but most were
within 10% of 

control values.

All non-neoplastic lesions observed on gross and histopathological
examination were typical of aged rats with no increase in incidence with
treatment. 

The lowest-observed-adverse-effect level (LOAEL) for EL-436 in rats was
0.04% (18.3 mg/kg/day) for males and 0.045% (25.9 mg/kg/day) for females
based on a decrease in body weight, body weight gain, food consumption
and efficiency of food utilization (EFU). The no-observed-adverse-effect
level (NOAEL) was 0.02% in both males (9.2 mg/kg/day) and females (11.5
mg/kg/day).

At the doses tested, there was not a treatment related increase in tumor
incidence in any tumor type in males or females when compared to
controls. The only finding was a decrease in the incidence of
mononuclear cell leukemia in male rats with increasing doses. The
incidence rate was 33/60 (55%), 26/60 (43%), 31/60 (52%), 22/60 (37%)
and 17/60 (28%) in the controls, 0.001, 0.01, 0.02 or 0.04% groups,
respectively.  Dosing was considered adequate based on the decreased
body weight, body weight gain and food consumption.

This chronic/carcinogenicity study in the rat is ACCEPTABLE/GUIDELINE
and satisfies the guideline requirement for a chronic/ carcinogenicity
study OPPTS 870.4300); OECD 453] in rats.

A.3.6	Mutagenicity

870.5100 Bacterial Reverse Mutation Assay

EXECUTIVE SUMMARY: In a single gene mutation assay in bacteria (MRID
44742909), four strains of S almonella typhimurium [strains TA1535,
TA1537, TA98 and TA100 and strain WP2 uvrA of E.coli were exposed to
EL-436, (98% a.i.) in dimethyl sulfoxide at concentrations ranging from
187.5 to 3000 µg/plate in the presence and absence of mammalian
metabolic activation derived from male rats induced with Aroclor 1254 in
the standard plate incorporation assay. 

In a preliminary cytotoxicity and solubility test with eight
concentrations (50 to 5000 µg/plate) of Fenazaquin, compound
precipitation was evident above 3000 µg/plate but no significant
cytotoxicity was seen up to 5000 µg/plate.  Whereas the positive
controls induced the appropriate responses in the corresponding strains,
no increases in revertant colonies of any strain were seen at any
concentration with or without S9 activation.  There was no evidence or a
concentration-related positive response of induced mutant colonies over
background.

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

870.5300	In Vitro Mammalian Cell Gene Mutation Assay 

EXECUTIVE SUMMARY: In independently repeated mammalian cell gene
mutation assay at the thymidine kinase (TK+/-) locus (MRID44742908),
mouse lymphoma cells cultured in vitro were exposed to EL-436, (98%
a.i., batch/lot ACD13041) in dimethyl sulfoxide at eight concentrations
ranging from 0.05 to 20 µg/mL in the absence of mammalian metabolic
activation or at 0.05 to 20 µg/mL in the presence of mammalian
metabolic activation for 4 hours.  The S9 mix was derived from the
livers of Fischer rats induced with Aroclor 1254.  

 /mL+/-S9), the test material was severely cytotoxic at ≥ 25 µg/mL
+/-S9 causing <10% suspension growth (SG).  At 10 µg/mL, %SG was 16%
(-S9) and 9% (+S9).  Compound precipitation was evident at ≥ 250
µg/mL.  Based on these data, the starting levels for the mutation
assays were 20 µg/mL –S9 and 12 µg/mL +S9.

EL-436 was not mutagenic in the absence of S9 activation; however, a
reproducible increase in the mutation frequency (MF) was found under
S9-activated conditions at EL-436 concentrations of 6 to 10 µg /mL in
the initial and two repeat trials as follows: 

Initial trial:  MF = 2.9, 4.2, 4.3 or 4.7 mutants/105 colony forming
units (CFU) at 4, 6, 8, or 12 µg/mL +S9; respectively vs. 1.4
mutants/105 CFU for the DMSO control cultures.  Total survival (TS) at
these levels was 64, 19, 6 or 3%.

Repeat trial 1:  MF = 3.3, 6.2, 5.5 or 6.7 mutants/105 CFU at 4, 6, 8,
or 10 µg/mL +S9; respectively, vs. 1.7 mutants/105 CFU for the DMSO
control cultures.  TS at these levels was 61, 13, 10 or 9 %.

Repeat trial 2:  MF = 8.8, 7.1 or 8.9 mutants/105 CFU at 6, 8, or 10
µg/mL +S9; respectively, vs. 1.6 mutants/105 CFU for the DMSO control
cultures.  TS at these levels was 12, 7 or 5 %.

The positive controls induced the appropriate response.  It was,
therefore, concluded that EL-436 was mutagenic in mouse lymphoma cells
generally at concentrations that were severely cytotoxic (10-20%
survival) in the presence of S9 activation. 

This study is classified as acceptable (guideline) and satisfies the
guideline requirement for Test Guideline OPPTS 870.5300, OECD 476 for in
vitro mutagenicity (mammalian forward gene mutation) data.

870.5375	Cytogenetics Assay (In Vitro Chromosomal Aberrations)

EXECUTIVE SUMMARY: In independent mammalian cell cytogenetics assay
(MRID44742907), Chinese hamster ovary (CHO) cells were exposed to
EL-436, (98% a.i., batch/lot ACD13041) in dimethyl sulfoxide at
concentrations ranging from of 0.1 to 60 µg/mL without S9 metabolic
activation and 40, 50 or 60 µg/mL with S9 metabolic activation for 4
hours.  Cells were harvested 18-24 hours postexposure and analyzed for
the frequency of structural and numerical chromosome aberrations.  

In a preliminary cytotoxicity test, nine concentrations ranging from
0.05 to 240µg/mL+/-S9 were tested.  Results indicated that percent
cells survival was severely decreased at concentrations  >1.0 µg/mL-S9
(6% at 10 µg/mL) and at levels >48µg/mL +S9 (6% at 96 µg/mL).  

In the parallel cytotoxicity test, relative cell survival was <50% at
≥ 1.0 µg/mL –S9 and at ≥ 70.0 µg/mL +S9.  Compound precipitation
was evident at levels ≥ 24 µg/mL +/-S9.  Based on these findings,
concentrations of 0.1, 0.5 or 1.0 µg/mL –S9 or 40, 50 or 60 µg/mL
+S9 were examined for aberrant chromosome aberrations.  At the EL-436
concentrations analyzed, there were no significant increases in the
percentage of cells with structural or numerical aberrations over the
solvent control cultures. Positive controls induced the appropriate
response.  Therefore, EL-436 is not clastogenic in Chinese hamster ovary
cells. 

This study is classified as acceptable (guideline) and satisfies the
guideline requirement for Test Guideline (In vitro mammalian
cytogenetics OPPTS 870.5375; OECD 473) for in vitro cytogenetic
mutagenicity data.

870.5395	 	Micronucleus Assay (Mouse)

g/kg bw (♂) or 0, 400, 800 or 1200 mg/kg bw (♀).  Bone marrow was
harvested at 24 hours following administration of the second dose. 

Cells were scored to determine the polychromatic erythrocyte:
normochromatic erythrocyte ratio (PCE:NCE) and the incidence of
micronucleated PCEs (MPCEs).

Dose selection for the main assay was determined from the findings of a
dose-range finding assay with calculated median lethal doses (MLD) of
3191 mg/kg (♂) and 2430 mg/kg (♀).  Accordingly, the selected high
doses for the micronucleus were ½ of the MLD (1600 mg/kg, ♂ and 1200
mg/kg, ♀) administered 2X daily. The test material was not overtly
toxic or induced a cytotoxic effect on the target organ.   There was
also no appreciable increase in the frequency of MPCEs at any dose in
either sex.  The positive control induced the appropriate response. 
EL-436 did not significantly increase in the frequency of MPCEs in bone
marrow from male or female mice treated with doses up to levels that
exceed the limit dose of 2000 mg/kg.

This study is classified as acceptable (guideline) and satisfies the
guideline requirement for Test Guideline OPPTS 870.5395; OECD 474 for in
vivo cytogenetic mutagenicity data.

870.5915		In vivo Sister Chromatic Exchange Assay (Mouse)

EXECUTIVE SUMMARY: In a CD-1 mouse bone marrow sister chromatid exchange
assay (SCE) (MRID 44742905), groups of three males were administered
EL-436, (98% a.i., batch/lot ACD13041) in 10% aqueous acacia at doses of
0, 500, 1000, or 2000 mg/kg bw via oral gavage.  Bone marrow cells were
harvested at 21 hours following administration and metaphases were
evaluated for the induction of SCEs.

	

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f 4000 mg/kg.  Accordingly, the high dose is ½ the MLD.   The test
material was lethal for two high-dose and one mid-dose animal.  There
was, however, no clear evidence of a cytotoxic effect on the target
organ.   There was also no appreciable increase in the frequency of SCEs
at any dose.  Owing to mortality, bone marrow cells were only available
for one high-dose animal and two mid-dose males.   The positive control
induced the appropriate response.  EL-436 did not significantly increase
in the frequency of SCEs in bone marrow from male CD-1 mice treated with
doses up to levels that produced death. 

the number of animals examined at each data point (3♂) was lower than
the number recommended by guideline (5/sex/dose) for this test system.

870.5550	In vitro Unscheduled DNA Synthesis Assay 

EXECUTIVE SUMMARY: In independent unscheduled DNA synthesis assays (MRID
44742906), primary rat hepatocyte cultures were exposed to EL-436, (98%
a.i., batch/lot ACD13041) in dimethyl sulfoxide (DMSO), at
concentrations of 0, 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1.0 or 5.0
µg/mL for 20 hours in both trials.  

≥0.5 to 1.0 µg/mL) in two independent trials but did not increase the
incidence of UDS.  The positive controls induced the appropriate
response.  There was no evidence that UDS, as determined by radioactive
tracer procedures (nuclear silver grain counts) was induced.

This study is classified as [acceptable (guideline)] and satisfies the
guideline requirement for Test Guideline OPPTS 870.5550; OECD 482/486
for other genotoxic mutagenicity data.

A.3.7	Metabolism

870.7485	Metabolism - Rat

; 97.33->99.9%, 4.23 and 5.44 μCi/mg, Lot Nos. 657-4BE-5 and
553-VJ7-187) or the quinazoline-phenyl ring (quinazoline; 98.8-99.2%,
19.8 μCi/mg, Lot No. 553-VE9-091)) was administered to groups of five
male and five female Fischer 344 (F344/Crl) rats as a single 1 mg/kg or
30 mg/kg radiolabeled dose.  A group of eight male and eight female rats
received 14-daily doses of 1 mg/kg unlabeled test material followed by a
single radiolabeled gavage dose.  An additional group of three male and
three female rats received a single 1 mg/kg radiolabel dose to determine
elimination of the compound in expired air.   

Overall recovery of the radiolabel was excellent (89.5-107.7% of the
administered dose).  Within 48 hours of treatment, ~75% of the
radiolabel was recovered in the excreta, and by 72 hours after
treatment, >84% was recovered.  No sex-related differences in
elimination were noted.  Approximately ~20% of the radiolabel was
recovered in the urine with the remainder in the feces.  Less than 1.6%
of the radiolabel was recovered in the residual carcass or tissues and
essentially no significant amount of radiolabel was recovered in the
expired air.  There are no available excretion studies following bile
cannulation or intravenous (i.v.) administration to determine test
material bioavailability (gastrointestinal absorption).  Therefore,
while the nearly 20% of the administered dose was absorbed before it was
excreted in urine, it is not clear if any or all of the remaining dose
(nearly 80%) that was found in feces was actually absorbed prior to its
fecal elimination.

In the urine, the primary metabolite was AN-1
[4-(2-hydroxy-1,1-dimethylethyl) phenylacetic acid] (24-29% of total
urinary radioactivity) plus numerous minor metabolites.  This metabolite
was characterized by the absence of protons associated with the
quinazoline portion of the molecule, indicating cleavage of the ether
bridge.   No significant differences between the sexes or dose groups
were observed.  

Four primary metabolites and numerous minor metabolites were found in
the feces.  The parent compound, EL-436, represented 1.2-4.2% of the
recovered radioactivity in the single or multiple low-dose groups and
11.5-20.6% of the recovered activity in single high-dose rats. 
Metabolite F1 (4.6-9.4% of the administered dose) had the phenyl and
quinazoline rings and both sets of methylene protons intact, as well as
the addition of a single oxygen atom to the phenyl-t-butyl portion of
the parent molecule.  Metabolite F-1A, a minor metabolite contributing
0.6-2.6% of the radioactivity, was characterized by intact phenyl and
quinazoline rings and hydroxylation of the ethoxy bridge.  Metabolite
F-2 was the primary fecal metabolite identified (16.3-22.8% of the
recovered radioactivity) and was similar to metabolite F1, but with the
addition of two oxygen atoms and the loss of two hydrogen atoms to form
a carboxylic acid on one of the methyl alky groups attached to the
phenyl ring.  Metabolite F3 contributed 6.5-12.6% of the recovered
radioactivity and contained both the phenyl and quinazoline ring
systems; however, the quinazoline ring had been hydroxylated and one of
the methyl alkyl groups of the phenyl ring had been carboxylated.  While
the fecal metabolites were likely produced by the liver, it is not
possible to exclude metabolism by intestinal microflora.

These studies show that radiolabeled EL-436 is rapidly metabolized and
eliminated from male and female rats following treatment with either
single or multiple low doses or following a single high dose of the
compound.  However, there is no information on biliary excretion or
fecal/urinary elimination following i.v. administration.

This metabolism study in the rat is classified Unacceptable/Guideline
and does not satisfy the guideline requirement for a metabolism study
[OPPTS 870.7485, OECD 417] because the extent of absorption of the test
material was not determined.  It is upgradeable to Acceptable/Guideline
if the results of a biliary excretion test are made available (compound
water solubility may be too low for i.v. administration).

A.3.8	Special/Other Studies

In Vivo/In Viro UDS Assay

EXECUTIVE SUMMARY:  In an in vitro/in vivo Sprauge Dawley rat DNA repair
assay (MRID 45029908), groups of male rats (5/group) were administered
fenazaquin (Batch No. RMM1836/435MH8, 99.3% a.i.) suspended in 1%
methylcellulose (MC) at doses of 0, 180 or 600 mg/kg for 2 or 14 hours. 
Hepatocytes were isolated from 4 animals in each treatment, vehicle or
positive [dimethylnitrosamine (DMN) and 2-acetylaminofluorene (2-AAF)]
control groups at 2 and 14 hours.  Recovered cells were allowed to
attach to coverslips, placed in tridiated thymidine, and prepared for
autoradiographs.  Unscheduled DNA sysnthesis (UDS) was determined by
comparing radioactive labeling in hepatocyte nuclei from animals treated
with fenazaquin to cells recovered from the vehicle control group.  

Based on death and other toxic signs in the preliminary toxicity test,
600 mg/kg was selected as the maximum tolerated dose (MTD).  Three rats
died “shortly” after treatment (1 at 180 mg/kg and 2 at 600 mg/kg);
other toxic signs included lethargy and increased respiratory rates. 
There was, however, no evidence of a cytotoxic effect on the harvested
hepatocytes. Similarly, the test material did not adversely affect DNA
since animals did not manifest any increases in either the gross nuclear
grain counts or net nuclear counts (NNGC = gross nuclear grain counts
minus cytoplasmic grain counts) at any dose or sacrifice time.  By
contrast, positive control groups showed significant (p<0.01) increases
in the NNGC compared to the vehicle control group.  Therefore, Fenzaquin
has shown no evidence of DNA damage and repair in this test system, as
determined by radioactive tracer procedures (nuclear silver grain
counts).

This study is classified as acceptable.  As yet, there is no FIFRA Test
Guideline for this type of in vivo study.

Peroxisome Proliferation

EXECUTIVE SUMMARY: A series of studies (MRID 44742903) were conducted to
determine the mechanism for metabolic activation of XDE-436 (Fenazaquin,
purity >95%; Lot No. not reported) to induce hepatocellular peroxisome
proliferation.  Equimolar concentrations of XDE-436 and several of its
analogs (all with purity >95% and with varying susceptibilities to
metabolism of the ether bond (tether) or the alkylbenzene substituents)
were assessed for their peroxisome proliferation potential in groups of
five CD-1 female mice.  These analogs included 209068 (methylene
tether), 278131 (nitrogen tether), 149953 (ethanol), 215257
(trifluoromethoxy), 247356 (methylfluoro ether), 257641 (biphenyl),
809161 (TFMPE, 2-[4-(trifluoromethyl) benzyl]ethanol), and 809305
(t-butyrate).  The parent compound and its analogs were solubilized in
corn oil (except for 247356 which was suspended in 10% acacia gum
solution) and were administered by gavage in four daily treatments.  The
mice were killed the day following the last treatment and the absolute
and relative liver weights and liver peroxisomal fatty acyl-CoA oxidase
(FAO) activity as a marker for peroxisome proliferation were measured.  

FAO activity data indicated that oxidation of the t-butyl substitutent
on the alkylbenzene moiety of XDE-436 and related compounds is the
critical step for induction of hepatocellular peroxisome proliferation
in mice.  Analogs of XDE-436 containing a substitutent on the
alkylbenzene portion of the molecule oxidizable to a carboxylic acid
were active peroxisome proliferators while analogs less sensitive to
oxidation were inactive.  Hydrolysis and subsequent oxidation of the
tether of XDE-436 and its analogs did not result in pronounced
peroxisome proliferation.  

This peroxisome proliferation study in the mouse is classified
Acceptable/Nonguideline and satisfies the study’s intent.

Appendix B.	Expected rat metabolic pathway

Appendix C.	Fenazaquin Metabolites

C.1.	Metabolic Profile (Apple)

The primary mode of metabolism of fenazaquin occurs in the first 7-14
days and is a result of photolysis.  Cleavage of the ether link in the
fenazaquin results in production of photoproducts which are incorporated
into the peel and pulp.  Parent fenazaquin was the primary metabolite in
the surface solvent washes.  A (photolyticly produced) dimer of
fenazaquin was also observed in the surface washes.  In the pulp and the
washed peel, metabolites I, J and C/L were also seen.  

FIGURE C..1. 	Proposed Metabolic Profile of Fenazaquin in Apples (copied
unmodified from MRID 46684002



TABLE C.1. Identification of Compounds from Apple Metabolism Study
(MRIDs 45029914, 45029917)

Common name/code

Figure C.3.1  ID No.	Chemical name	Chemical structure

Fenazaquin	4-[2-(4-tert-Butyl-phenyl)-ethoxy]-





The apple metabolism study is adequate to show that parent fenazaquin is
the primary residue of toxicological interest present in superficial
residues (50% to 100% of the TRR).  Data on residues in the flesh are
very limited, but suggest that fenazaquin can be somewhere between 5% to
50% of the TRR in the flesh.  Under the conditions of this study
superficial residues completely predominated over residues in the flesh,
but the way the study was performed would have maximized that
predominance.

Appendix D	Goat Metabolism

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 and excreta were inadequate. The study indicates that bioaccumulation
of fenazaquin residues in ruminants is limited, but the metabolism of
fenazaquin in goats was not determined.  

Table D. Chemical Names and Structures of Reference Standards Used in
Goat Metabolism Study.

Common name;

Company code	Chemical name	Chemical structure

Fenazaquin

AGR 289213





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