UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
MEMORANDUM
Date:
10/
6/
05
Subject:
Imazaquin.
Tolerance
Reassessment
Eligibility
Decision
(
TRED).
Summary
of
Analytical
Chemistry
and
Residue
Data.

DP
Number:
302944
Decision
Number:
PC
Code:
128848
(
imazaquin
acid),
128840
(
ammonium
salt
of
imazaquin),
and
129023
(
sodium
salt
of
imazaquin)
40
CFR
180.426
Chemical
Class:
imidazole
From:
Danette
Drew,
Chemist
Reregistration
Branch
3
Health
Effects
Division
(
7509C)

Through:
Catherine
Eiden,
Branch
Chief
Reregistration
Branch
3
Health
Effects
Division
(
7509C)

To:
Susan
Stanton,
Risk
Assessor
Reregistration
Branch
3
Health
Effects
Division
(
7509C)

and
Craig
Doty,
CRM
Special
Review
Branch
Special
Review
and
Reregistration
Branch
(
7508C)
2
of
20
Executive
Summary
Imazaquin
is
a
pre­
plant,
pre­
emergence,
and
early
post
emergence
herbicide
registered
for
use
on
the
raw
agricultural
commodity
soybeans.
Except
where
otherwise
noted,
the
term
"
imazaquin"
in
this
document
refers
to
the
technical
acid
(
PC
Code
128848),
the
ammonium
salt
of
imazaquin
(
PC
Code
128840),
and
the
monosodium
salt
of
imazaquin
(
PC
Code
129023).
The
registered
formulation
classes
of
the
herbicide
are
water
dispersible
granule
(
WDG),
wettable
powder
(
WP),
emulsifiable
concentrate
(
EC),
and
soluble
concentrate
(
SC).
The
active
ingredient
in
the
products
range
from
1.7%
to
70%.
A
maximum
of
0.25
lb
ai/
A
may
be
applied
per
year
using
ground
or
aerial
equipment.
The
maximum
single
application
rate
is
0.125
lb
ai/
A.
All
product
labels
indicate
a
pre­
harvest
interval
(
PHI)
of
90
days.

A
petition
for
a
temporary
tolerance
on
corn
was
previously
submitted
(
PP#
5G04527).
The
Health
Effects
Division
(
HED)
recommended
in
favor
of
the
establishment
of
a
temporary
tolerance
for
residues
of
imazaquin
on/
in
field
corn
grain,
forage,
and
stover
at
0.05
ppm
provided
a
revised
Section
B
and
Section
F
are
submitted.
The
conclusions
and
deficiencies
of
the
petition
review
can
be
found
in
the
memorandum
dated
2/
11/
97
(
W.
Wassell,
D216732).
A
tolerance
for
imazaquin
on
corn
has
not
been
established.

The
nature
of
the
residue
in
plants
is
adequately
understood
for
the
use
of
imazaquin
on
soybeans.
Based
on
the
trace
levels
of
radioactivity
found
in
the
soybean
seed
from
an
exaggerated
application
rate,
the
apparent
extensive
degradation
of
imazaquin
into
plant
constituents,
and
the
livestock
grazing/
feeding
prohibition
of
forage,
straw
and
hay
on
current
labels,
the
residue
of
concern
for
the
use
of
imazaquin
on
soybeans
is
imazaquin,
per
se.
If
additional
uses
of
imazaquin
are
proposed,
then
additional
metabolism
data
may
be
required.

The
nature
of
residue
in
livestock
is
adequately
understood
for
the
use
of
imazaquin
on
soybeans.
Tolerances
for
imazaquin
residues
in
livestock
commodities
need
not
be
established
as
a
result
of
the
use
on
soybeans
based
on
nondetectable
residues
in
eggs,
milk,
and
livestock
tissues
from
the
available
animal
metabolism
studies
and
nondetectable
residues
in
the
submitted
magnitude
of
residue
studies
in
livestock
feedstuffs.
If
additional
uses
or
additional
field
studies
result
in
detectable
residues
in
feedstuffs,
then
additional
animal
metabolism
studies
may
be
required.
The
residue
of
concern
in
livestock
commodities
will
be
determined
when
tolerances
for
secondary
residues
in
livestock
commodities
are
deemed
necessary.
Additionally,
label
restrictions
prohibit
the
grazing
or
feeding
of
soybean
forage,
hay
or
straw
to
livestock.

Method
M­
1410
has
been
accepted
for
tolerance
enforcement
purposes
and
is
included
in
PAM,
Vol
II
as
Method
I.
The
gas
chromatography
method
uses
acidic
water
and
methanol
in
the
extraction
process.
The
previous
analytical
methods
(
M­
1283
and
M­
1245)
were
replaced
by
Method
M­
1410
because
the
analysis
of
freezer
stability
samples
using
Methods
M­
1283
and
M­
1245
showed
that
extraction
with
ethyl
acetate
only
extracted
about
50%
of
the
residue.
The
crop
field
samples
were
analyzed
using
Methods
M­
1283
and
M­
1245;
however,
the
fortification
results
indicated
acceptable
recovery.

Imazaquin
has
not
been
tested
for
recovery
via
FDA
Multiresidue
Protocols
(
PAM
Vol.
I)
and
it
is
unknown
whether
it
is
recoverable
by
these
methods.
3
of
20
Tolerances
have
been
established
under
40
CFR
§
180.426
for
imazaquin
in
or
on
soybeans
at
0.05
ppm.
In
crop
field
trials
conducted
on
soybeans
using
pre­
plant
incorporated
and
post­
emergence
treatments
with
diisoproyl­
amine
salt
of
imazaquin
at
rates
of
0.25
lb
ae/
A
(
1x)
to
2
lb
ae/
A
(
8x;
one
trial),
residues
of
imazaquin
were
<
0.05
ppm
in
all
samples
including
seeds,
foliage,
and
straw.
Forage
and
hay
samples
were
not
collected.
Processing
studies
are
not
required
because
residues
were
not
detected
in
soybean
samples
treated
at
8x
the
maximum
application
rate.

Residues
of
imazaquin
are
stable
for
up
to
24
months
on
frozen
soybean
and
corn.
The
storage
duration
of
the
crop
field
trial
soybean
samples
from
harvest
to
analysis
was
not
provided.

Rotational
crop
restrictions
are
required
based
on
the
results
of
confined
and
limited
field
accumulation
in
rotational
crop
studies
conducted
with
wheat,
corn,
carrots,
and
lettuce.
Plantback
intervals
listed
on
current
labels
are
adequate.

Regulatory
Recommendations
and
Residue
Chemistry
Deficiencies
A
tolerance
of
0.05
ppm
has
been
established
under
40
CFR
§
180.426
for
residues
of
imazaquin
in
or
on
soybeans.
HED
supports
this
tolerances,
provided
that
the
following
deficiencies
and
data
gaps
are
resolved:

1.
The
storage
duration
of
the
crop
field
trial
soybean
samples
from
harvest
to
analysis
was
not
provided
and
should
be
submitted.
Storage
stability
studies
indicate
that
residues
of
imazaquin
are
stable
on
soybeans
for
up
to
24
months
of
frozen
storage.

2.
Multiresidue
method
data
were
not
submitted.
The
registrant
should
submit
data
pertaining
to
the
recovery
of
imazaquin
via
FDA
Multiresidue
Protocols
(
PAM
Vol.
I).

3.
Residue
data
were
not
provided
for
soybean
forage
and
hay;
however,
these
data
are
not
required
provided
current
label
restrictions
prohibiting
the
grazing
and
feeding
of
forage,
straw
and
hay
to
livestock
are
maintained.

Background
The
chemical
structure
and
nomenclature
of
imazaquin
are
listed
in
Table
1,
the
chemical
names
and
structures
of
the
metabolites
of
imazaquin
are
presented
in
Table
2,
and
the
physicochemical
properties
of
imazaquin
are
presented
in
Table
3.
4
of
20
N
N
H
N
OH
O
O
CH
3
CH(
CH
3
)
2
N
N
H
N
O
O
O
CH
3
CH(
CH
3
)
2
NH
4
+

N
N
H
N
O
O
O
CH
3
CH(
CH
3
)
2
Na
+
TABLE
1.
Imazaquin
and
Salts
Nomenclature
Chemical
structure
Common
name
Imazaquin
Molecular
Formula
C17H17N3O3
Molecular
Weight
311.34
IUPAC
name
(
RS)­
2­(
4­
isopropyl­
4­
methyl­
5­
oxo­
2­
imidazolin­
2­
yl)
quinoline­
3­
carboxylic
acid
CAS
name
2­[
4,5­
dihydro­
4­
methyl­
4­(
1­
methylethyl)­
5­
oxo­
1H­
imidazol­
2­
yl]­
3­
quinolinecarboxylic
acid
CAS
#
81335­
37­
7
PC
Code
128848
Chemical
structure
Common
name
Imazaquin,
ammonium
salt
IUPAC
name
(
RS)­
2­(
4­
isopropyl­
4­
methyl­
5­
oxo­
2­
imidazolin­
2­
yl)
quinoline­
3­
carboxylic
acid,
monoammonium
salt
CAS
name
2­[
4,5­
dihydro­
4­
methyl­
4­(
1­
methylethyl)­
5­
oxo­
1H­
imidazol­
2­
yl]­
3­
quinolinecarboxylic
acid,
monoammonium
salt
CAS
#
81335­
47­
9
PC
Code
128840
Chemical
structure
Common
name
Imazaquin,
sodium
salt
IUPAC
name
(
RS)­
2­(
4­
isopropyl­
4­
methyl­
5­
oxo­
2­
imidazolin­
2­
yl)
quinoline­
3­
carboxylic
acid,
monosodium
salt
CAS
name
2­[
4,5­
dihydro­
4­
methyl­
4­(
1­
methylethyl)­
5­
oxo­
1H­
imidazol­
2­
yl]­
3­
quinolinecarboxylic
acid,
monosodium
salt
CAS
#
81335­
46­
8
TABLE
1.
Imazaquin
and
Salts
Nomenclature
5
of
20
N
N
H
N
OH
O
O
CH
3
CH(
CH
3
)
2
N
N
H
N
OH
O
O
CH
3
CH(
CH
3
)
2
OH
N
OH
O
O
OH
N
OH
O
O
OH
PC
Code
129023
TABLE
2.
Chemical
Names
and
Structures
of
Metabolites
of
Imazaquin1
Common
Name
Chemical
Name
Structure
Imazaquin
±
­
2­(
4,5­
Dihydro­
4­
methyl­
4­(
1­
methylethyl)­
5­
oxo­
1H­
imidazol­
2­
yl)­
3­
quinolinecarboxylic
acid
5­
Hydroxy
imazaquin
CL
343,684
2­[
4,5­
dihydro­
4­
methyl­
4­(
1­
methylethyl)­
5­
oxo­
1H­
imidazol­
2­
yl]­
5­
hydroxy­
3­
quinolinecarboxylic
acid
CL
263,875
quinoline­
2,3­
dicarboxylic
acid
1.
The
metabolites
were
identified
in
field
corn
forage
(
MRID
43671601)
(
D216732,
W.
Wassell,
2/
11/
97).

TABLE
3.
Physicochemical
Properties
of
Imazaquin
Parameter
Value
Reference
Melting
point
219­
224
°
C
(
decomposes)
MRID
00146197;
PP#
5F3273,
RCB
#
1265,
1/
9/
86,
A.
Smith
pH
4.6
at
25
°
C
Density,
bulk
density,
or
specific
gravity
0.39
g/
mL
untapped;
0.43
g/
mL
tapped
Water
solubility
at
25
°
C
60
ppm
TABLE
3.
Physicochemical
Properties
of
Imazaquin
Parameter
Value
Reference
6
of
20
Solvent
solubility
g/
100
mL
Acetone
0.30
DMF
6.80
DMSO
15.9
Ethanol
0.30
Heptane
0.02
Methanol
0.50
Methylene
chloride
1.36
Toluene
0.04
Vapor
pressure
<
2
x
10­
8
mm
Hg
at
45
°
C
Dissociation
constant,
pKa
3.8
Octanol/
water
partition
coefficient
2.2
at
22
°
C
UV/
visible
absorption
spectrum
Not
available
860.1200
Directions
for
Use
Product
List
There
are
twelve
active
end­
use
products
(
EPs)
containing
imazaquin
for
use
on
soybeans.
Seven
of
the
products
contain
the
imazaquin
acid,
four
contain
the
ammonium
salt
of
imazaquin,
and
one
contains
the
sodium
salt
of
imazaquin.
All
products
are
registered
to
BASF
Corp.
Additionally,
there
are
three
SLN
registrations.
The
EPs
are
listed
in
Table
4.

TABLE
4.
Imazaquin
End­
Use
Products
(
EPs)
with
Food/
Feed
Uses
(
Only
Soybeans)

End­
use
products
(
EPs)
Formulation1,2
Product
Name
Registrant
Company
Imazaquin
(
PC
Code
128848)

241­
3063
70%
WDG
Scepter
®
70
DG
Herbicide
BASF
Corp.

241­
361
5.4%
SC
Detail
®
Herbicide
BASF
Corp.

241­
369
35%
WDG
Imazaquin/
Imazathapyr
DG
BASF
Corp.

241­
376
1.9%
EC
Steel
®
Herbicide
BASF
Corp.

241­
407
2.8%
EC
Backdraft
 
Herbicide
BASF
Corp.

241­
408
70%
WP
Backdraft
 
CP
BASF
Corp.

241­
415
1.7%
SC
Backdraft
 
SL
Herbicide
BASF
Corp.

LA010010
70%
WDG
Scepter
®
70
DG
Herbicide
BASF
Corp.

MS010011
2.8%
EC
Backdraft
 
Herbicide
BASF
Corp.

MS020002
1.7%
SC
Backdraft
 
SL
Herbicide
BASF
Corp.

Ammonium
salt
of
imazaquin
(
PC
Code
128840)

241­
307
4.72%
EC
(
4.48%
ae)
TRI­
SCEPT
®
BASF
Corp.

241­
289
17.3%
SC
(
16.4%
ae)
Scepter
®
BASF
Corp.

241­
292
17.3%
SC
(
16.4%
ae)
Scepter
®
BASF
Corp.
TABLE
4.
Imazaquin
End­
Use
Products
(
EPs)
with
Food/
Feed
Uses
(
Only
Soybeans)

7
of
20
241­
327
3.65%
SC
(
3.46%
ae)
Squadron
®
BASF
Corp.

Sodium
salt
of
imazaquin
(
PC
Code
129023)

241­
321
5.61%
SC
(
5.24%
ae)
Scepter
O.
T
®
BASF
Corp
1.
WDG
­
water
dispersiable
granule;
SC
­
soluble
concentrate;
EC
­
emulsifiable
concentrate;
WP
=
wettable
powder
2.
ae
=
acid
equivalent
3.
The
registrant
has
indicated
that
the
only
product
currently
being
marketed
is
the
Scepter
70
DG
(
241­
306).
However,
all
products
with
active
registrations
are
presented
in
this
document.

Use
Patterns
For
the
purposes
of
re­
registration,
the
registered
food/
feed
uses
of
imazaquin
have
been
reevaluated
for
soybeans.
Table
5
presents
a
brief
summary
of
the
directions
for
use
of
imazaquin.
All
labels
have
geographic
restrictions
limiting
use
to
approximately
the
eastern
half
of
the
United
States.
Rotational
crop
plant­
back
intervals
range
from
3
months
to
40
months,
depending
on
rotated
crop.(
See
product
labels
for
specifics
on
geographical
regions
allowed
and
plant­
back
intervals.)

TABLE
5.
Directions
For
Use
of
Imazaquin
Application
Timing
°
Application
Type
Max.
Single
Application
Rate
Max.
Seasonal
Rate
Max.
No.
Applications/
cc
&
yr
Restrictions
SOYBEANS
Preplant,
Preemergence,
Postemergence,
Early
Postemergence
°
Broadcast,
Soil
Incorporated
°
Ground,
Aerial
0.125
lb
ae/
A
0.25
lb
ae/
A
(
EPA
Reg.
No.
241­
292)
2
°
90
day
preharvest
interval
°
Do
not
graze
or
feed
treated
soybean
forage,
hay,
or
straw
to
livestock
°
Do
not
apply
through
any
type
of
irrigation
system.
°
Rotational/
plant
back
crop
restriction.
°
Geographic
restrictions.

PRODUCT
NUMBERS
CONTAINED
IN
THIS
REPORT
PC
Code
128848:
241­
306,
241­
361,
241­
369,
241­
376,
241­
407,
241­
408,
241­
415
PC
Code
128840:
241­
307,
241­
289,
241­
292,
241­
327
PC
Code
129023:
241­
321
HOMEOWNER
PRODUCTS
CONTAINED
IN
THIS
REPORT
None
A
tabular
summary
of
the
chemistry
science
assessments
is
presented
in
Table
6.
The
conclusions
listed
in
Table
6
regarding
the
re­
registration
eligibility
of
imazaquin
food/
feed
uses
are
based
on
the
use
patterns
registered
by
the
producer.
When
end­
use
product
data
call
in's
(
DCIs)
are
developed
(
e.
g.,
at
issuance
of
the
TRED),
the
Registration
Division
(
RD)
should
require
that
all
end­
use
product
labels
(
e.
g.,
MAI
labels,
SLNs,
and
products
subject
to
the
generic
data
8
of
20
exemption)
be
amended
such
that
they
are
consistent
with
the
basic
producer
labels.

TABLE
6.
Residue
Chemistry
Science
Assessment
for
Reregistration
of
Imazaquin
.

GLN
Data
Requirements
Current
Tolerances
(
ppm)
[
§
180.426]
Additional
Data
Needed?
MRID
Nos.

860.1200:
Directions
for
Use
N/
A
=
Not
Applicable
No1
See
Table
5
860.1300:
Nature
of
the
Residue
­
Plants
­
soybeans
N/
A
No
131563,
131546,
1470122
42874001
3
860.1300:
Nature
of
the
Residue
­
Animals
­
Goats
and
poultry
N/
A
No
1470124
860.1340:
Residue
Analytical
Method
­
Plant
Commodities
N/
A
No
131563,
1470125
­
Animal
Commodities
N/
A
No
None
860.1360:
Multiresidue
Method
N/
A
Yes6
None
submitted
860.1380:
Storage
Stability
Data
­
Plant
Commodities
N/
A
Yes7
147012,
436716048
860.1400:
Magnitude
of
the
Residue
­
Water,
Fish,
and
Irrigated
Crops
N/
A
N/
A
N/
A
860.1460:
Magnitude
of
the
Residue
­
Food
Handling
N/
A
N/
A
N/
A
860.1480:
Magnitude
of
the
Residue
­
Meat,
Milk,
Poultry,
Eggs
N/
A
No
None
860.1500:
Crop
Field
Trials
­
Soybean
N/
A
Yes9
131546,
13156,
14701210
860.1520:
Processed
Food/
Feed
­
Soybean
meal,
hulls,
oil
N/
A
No
N/
A
860.1650:
Submittal
of
Analytical
Reference
Standards
N/
A
No
11
N/
A
860.1850:
Confined
Accumulation
in
Rotational
Crops
N/
A
No
147012
12
860.1900:
Field
Accumulation
in
Rotational
Crops
N/
A
No
42874001,
42874002
13
1.
See
Table
5.
.
2.
PP#
G2979,
R.
Loranger,
3/
28/
84
and
PP#
3273,
A.
Smith,
1/
9/
86.
3.
PP#
5G4527,
D216732,
W.
Wassell,
2/
11/
97.
4.
PP#
G2979,
R.
Loranger,
3/
28/
84;
PP#
3273,
A.
Smith,
1/
9/
86.
5.
PP#
3273,
A.
Smith,
1/
9/
86;
PP#
5F3273,
E.
Greer,
2/
26/
86
;
A.
Smith,
3/
6/
86;
PP#
G22979,
R.
Loranger,
3/
28/
84.
6.
Multiresidue
method
data
were
not
submitted.
The
registrant
should
submit
data
pertaining
to
the
recovery
of
imazaquin
via
FDA
Multiresidue
Protocols
(
PAM
Vol.
I).
7.
The
storage
duration
of
the
field
samples
was
not
provided.
The
submitted
storage
stability
information
indicate
the
residues
are
stable
for
24
months
in
frozen
storage.
If
the
storage
duration
of
the
field
samples
was
greater
than
24
months,
storage
stability
information
should
be
submitted
to
cover
the
storage
duration.
8.
PP#
3273,
A.
Smith,
1/
9/
86;
PP#
5G4527,
D216732,
W.
Wassell,
2/
11/
97.
9.
The
storage
duration
of
the
crop
field
samples
from
harvest
to
analysis
was
not
provided
and
should
be
9
of
20
submitted.
10.
PP#
G2979,
R.
Loranger,
3/
28/
84;
PP#
3273,
A.
Smith,
1/
9/
86.
11.
Replenish
standards
as
requested
by
the
repository.
12.
ACC
No.
073703,
RCB
Nos.
1768,1769,
M.
Metzger;
2/
2/
87;
D194l81
&
D194180,
G.
Kramer,
6/
17/
94.
13.
D194l81
&
D194180,
G.
Kramer,
6/
17/
94.

860.1300
Nature
of
the
Residue
­
Plants
Soybean
metabolism
studies
were
conducted
in
Florida
and
New
Jersey
using
post­
emergence
and
pre­
plant
incorporated
treatment
methods.
Both
sites
used
carboxyl
labeled
imazaquin
as
the
test
substance.
The
New
Jersey
site
also
used
benzene
labels,
however,
not
all
of
the
benzene
results
were
submitted.
Diisopropyl­
amine
salt
of
imazaquin
was
applied
to
all
test
plots
at
a
rate
of
0.38
lb
ai/
A
(
1.5x).
For
the
post­
emergence
trials,
the
test
substance
was
applied
at
the
trifoliate
leaf
stage.
For
the
pre­
plant
incorporated
trials,
the
test
substance
was
applied
to
the
soil
and
incorporated
2
inches.
Plants
were
harvested
at
intervals
of
one
week
to
6.5
months,
dividing
the
more
mature
samples
into
fodder,
hulls,
and
seed.

For
preplant
application
the
soybean
seed
had
total
radioactivity
residue
(
TRR)
of
0.01
to
0.02
ppm
(
14C­
carboxyl
label)
and
0.03
ppm
(
14C­
benzene
label).
The
foliage
had
radioactivity
at
0.43
to
0.50
ppm
at
one
month;
0.05
ppm
to
0.09
ppm
at
2
months;
0.07
ppm
to
0.12
ppm
in
mature
foliage.
The
mature
hulls
had
TRR
at
0.04
ppm.

For
early
postemergence
application
soybean
seed
had
TRR
of
0.01
ppm
to
0.05
ppm
(
14Ccarboxyl
label)
and
0.04
ppm
(
14C­
benzene
label).
The
TRR
on
foliage
was
0.24
to
0.60
ppm
at
one
month
and
was
0.19
to
0.66
ppm
in
mature
foliage.

Total
radioactivity
from
1
month
up
to
maturity
were
similar
between
the
carboxyl
and
benzene
labeled
imazaquin,
indicating
that
loss
of
CO
2
from
the
carboxylic
acid
moiety
is
not
a
major
degradation
route
as
residues
from
the
carboxyl
label
should
be
considerably
lower
in
that
case.

The
residues
were
not
chemically
identified;
however,
some
characterization
involving
the
carboxyl
label
was
accomplished
by
solvent
fractionation
of
the
activity
and
isolation
of
the
protein
portion
of
the
seed.
HED
determined
that
the
characterization
was
adequate
to
show
that
imazaquin
was
extensively
degraded
and
reincorporated
into
native
plant
parts.

The
characterization
of
radioactivity
on
foliage
or
straw
was
not
presented
in
the
study
report.
At
a
preregistration
conference
on
3/
10/
83,
the
registrant
indicated
that
the
methanol
soluble
activity
of
straw
contained
8
metabolites
(
each
<
0.01
to
0.02
ppm)
and
the
foliage
contained
at
least
11
metabolites,
with
no
parent
compound
present.

Based
on
the
trace
levels
of
radioactivity
found
in
the
soybean
seed
from
an
exaggerated
application
rate,
the
apparent
extensive
degradation
of
imazaquin
into
plant
constituents,
and
the
livestock
grazing/
feeding
prohibition
of
forage,
straw
and
hay
on
current
labels,
the
residue
of
concern
for
the
use
of
imazaquin
on
soybeans
is
imazaquin,
per
se.
If,
in
the
future,
additional
uses
of
imazaquin
are
proposed,
additional
plant
metabolism
studies,
using
the
14C­
radiolabel
in
the
imidazol
ring,
may
be
required.
10
of
20
Metabolism
data
were
submitted
for
the
petition
for
a
temporary
tolerance
of
imazaquin
on
corn.
HED
determined
that
for
the
purposes
of
a
temporary
tolerance
on
corn,
the
nature
of
residue
in
corn
is
the
parent
compound
(
D216732,
W.
Wassell,
2/
11/
97).
A
brief
description
of
the
methodology
and
results
of
the
corn
metabolism
study
follows:

Following
a
single
preplant
incorporated
(
PPI)
or
preemergence
(
PRE)
application
of
[
14C]
imazaquin
to
field
corn
plants
at
0.5
lb
ae/
A
(
4x
the
proposed
maximum
application
rate),
the
total
radioactive
residues
(
expressed
as
imazaquin
equivalents)
were
0.045­
0.585
ppm
in/
on
forage,
0.012­
0.024
ppm
in/
on
silage,
0.018­
0.033
ppm
in/
on
fodder,
and
0.007­
0.016
ppm
in/
on
grain.
The
bulk
of
residue
characterization
and
identification
were
conducted
on
immature
forage
samples
(
15
and
30
DAT)
since
this
commodity
contained
the
highest
levels
of
radioactivity.
Following
extraction
and
HPLC
analyses,
­

79­
95%
of
TRR
in
forage
were
characterized/
identified.
The
principal
component
identified
was
the
parent
imazaquin
which
accounted
for
­

23­
34%
of
the
TRR
in
forage.
The
metabolites,
5­
hydroxy
imazaquin
(
CL
343,684)
and
quinoline­
2,3­
dicarboxylic
acid
(
CL
263,875)
were
also
qualitatively
identified
in
the
aqueous
fractions
of
corn
forage.
The
remainder
of
the
characterized
radioactivity
consisted
of
several
metabolite
regions
(
designated
as
Metabolites
A
through
I)
mostly
comprising
<
10%
of
the
TRR
except
for
Metabolite
F
which
comprised
­

21%
of
TRR
(
0.125
ppm)
in
15­
DAT
PPI
forage.
Further
analytical
work
to
isolate
and
identify
the
polar
Metabolite
F
was
not
successful
but
HPLC
analysis
of
the
isolated
fraction
characterized
the
metabolite
to
be
multi­
component
in
nature.

The
proposed
metabolic
pathway
of
imazaquin
applied
to
corn
is
as
follows:
(
i)
direct
conjugation
of
the
parent
chemical;
(
ii)
hydroxylation
of
the
parent
chemical
to
its
5­
hydroxy
metabolite
(
CL
343,684)
followed
by
conjugation;
and
(
iii)
degradation
of
the
imidazoline
ring
system
to
quinoline­
2,3­
dicarboxylic
acid
(
CL
263,875)
followed
by
conjugation.
Plant
residues,
although
substantive
in
the
early
growth
stages,
are
comprised
of
a
variety
of
metabolites
which
decline
in
content
to
<
0.01
ppm
in
mature
field
corn
commodities.

860.1300
Nature
of
the
Residue
­
Livestock
Acceptable
ruminant
and
poultry
metabolism
studies
were
submitted
and
evaluated
in
conjunction
with
PP#
5F3273
(
A.
Smith,
1/
9/
86).
The
available
ruminant
metabolism
study
indicate
that
the
total
radioactive
residues
were
nondetectable
in
milk,
liver,
kidney,
muscle,
and
fat
of
lactating
goats
following
oral
administration
of
[
14C]
imazaquin
at
0.25
and
0.75
ppm
for
seven
consecutive
days;
the
limits
of
detections
were
<
0.01
ppm
for
milk
and
<
0.05
ppm
for
tissues.
The
poultry
metabolism
study
indicates
that
the
total
radioactive
residues
were
also
nondetectable
(<
0.05
ppm)
in
egg
white,
egg
yolk,
muscle,
liver,
kidney,
skin,
and
fat
of
laying
hens
following
oral
administration
of
[
14C]
imazaquin
at
0.25
and
0.75
for
seven
consecutive
days.

The
nature
of
residue
in
livestock
is
adequately
understood
for
the
use
of
imazaquin
on
soybeans.
Tolerances
for
imazaquin
residues
in
livestock
commodities
need
not
be
established
as
a
result
of
the
use
on
soybeans
based
on
nondetectable
residues
in
eggs,
milk,
and
livestock
tissues
from
the
available
animal
metabolism
studies
and
nondetectable
residues
in
the
submitted
magnitude
of
residue
studies
in
livestock
feedstuffs.
If
additional
uses
or
additional
field
studies
result
in
detectable
residues
in
feedstuffs,
then
additional
animal
metabolism
studies
may
be
required.
The
11
of
20
residue
of
concern
in
livestock
commodities
will
be
determined
when
tolerances
for
secondary
residues
in
livestock
commodities
are
deemed
necessary.
Additionally,
label
restrictions
prohibit
the
grazing
or
feeding
of
soybean
forage,
hay
or
straw
to
livestock.
HED
considers
the
feeding
restrictions
to
be
enforceable,
and
therefore
acceptable,
since
soybeans
are
grown
for
seed
and
the
feed
items
remain
under
the
control
of
the
grower.

860.1340
Residue
Analytical
Methods
Method
M­
1410
is
adequate
for
data
collection
and
enforcement
of
tolerances
on
soybeans.
The
method
is
included
in
PAM
II
as
Method
I
and
replaces
Methods
M­
1283
and
M­
1245
for
their
lack
of
extractability
data.
The
initiation
of
freezer
storage
stability
work
using
Methods
M­
1283
and
M­
1245
showed
that
ethyl
acetate
(
the
previous
extraction
solvent)
extracted
only
about
50%
of
the
residue.

Briefly,
in
Method
M­
1410,
the
residues
are
extracted
from
the
soybean
tissue
with
acidic
water
and
methanol.
After
filtration
the
extract
is
partitioned
with
methylene
chloride.
Once
the
methylene
chloride
is
evaporated,
the
residue
is
dissolved
in
acetonitrile,
which
is
washed
three
times
with
hexane.
The
acetonitrile
is
evaporated
and
the
residue
is
dissolved
in
acetone.
Ammonium
chloride
is
used
to
precipitate
the
impurities
and
the
residue
is
filtered
and
partitioned
with
methylene
chloride.
To
clean
the
residue
further,
the
methylene
chloride
is
evaporated
and
residue
is
sent
through
a
micro
ion
exchange
column.
The
column
uses
0.1
N
of
hydrochloric
acid
solution
as
the
elutant
and
imazaquin
is
partitioned
into
the
methylene
chloride
phase.
Methylene
chloride
is
evaporated
again
and
the
imazaquin
is
dissolved
in
methanol.
Trimethylanilinium
is
added
and
quantization
of
the
imazaquin
occurs
through
gas
chromatography
(
A.
Smith,
3/
13/
86).

At
fortification
levels
ranging
from
0.05
to
0.5
ppm
for
soybean
straw
and
seed
and
0.05
to
50
ppm
for
green
plants,
the
Registrant
obtained
recoveries
of
83
to
100%
in
soybean
seed
samples,
80
to
97%
in
green
plant
samples,
and
83
to
102%
in
straw
samples.
Additionally,
the
Registrant
provided
data
on
the
extractability
of
total
carbon­
14
from
soybean
seed,
straw,
and
green
plants
treated
with
radiolabeled
imazaquin.
In
seed,
straw
and
green
plants,
the
percent
of
carbon­
14
extracted
was
72%,
72%,
and
33%.

An
EPA
method
trial
of
Method
M­
1410
was
conducted
using
soybeans
fortified
at
0.052
ppm
and
0.1
ppm.
Recoveries
ranged
from
79%
to
85%.
The
detection
limit
was
determined
to
be
0.01
ppm
(
PP#
5F3273,
E.
Greer,
2/
26/
86).

Methods
M­
1283
and
M­
1245
were
used
to
analyze
soybean
samples
from
the
field
trials.
In
these
methods,
plants
and
straw
are
extracted
with
acidic
ethyl
acetate,
filtered,
and
the
filtrate
is
evaporated
before
dissolving
the
residue
on
aqueous
methanol.
After
a
hexane
wash
the
pesticide
is
partitioned
into
methylene
chloride
with
the
latter
evaporated
before
dissolving
the
residue
in
acetone.
Various
impurities
are
removed
by
precipitation
with
ammonium
chloride­
phosphoric
acid
solution.
After
filtering,
the
active
ingredient
is
partitioned
into
methylene
chloride,
pH
7
phosphate
buffer,
and
back
into
methylene
chloride
(
after
acidification
of
the
buffer).
Final
cleanup
is
done
on
a
silica
gel
SEP­
PAK
before
dissolving
in
methanol
in
the
presence
of
trimethylanilinium
hydroxide
(
TMAH).
The
latter
results
in
on­
column
methylation
of
imazaquin
12
of
20
(
presumably
to
form
methyl
ester)
upon
injection
into
the
gas
chromatograph.
The
detector
of
choice
is
nitrogen­
phosphorus
specific.
For
soybeans,
the
cleanup
procedure
is
shorter
than
that
for
other
plant
parts.
After
extraction
with
acidic
ethyl
acetate,
the
mixture
is
filtered
and
evaporated
before
precipitating
between
hexane
and
acetonitrile.
The
latter
is
evaporated
and
the
residue
partitioned
between
methylene
chloride
and
pH
7
phosphate
buffer.
After
acidifying
the
aqueous
phase
imazaquin
is
brought
back
into
methylene
chloride
prior
to
GC
determination.
Recoveries
from
samples
fortified
at
0.05
­
1.0
showed
acceptable
recoveries
(
92­
100%
for
plants,
80­
90%
for
straw,
and
86­
105%
for
beans)
(
R.
Loranger,
3/
28/
84).

HED
determined
that
methods
M­
1283
and
M­
1245
were
adequate
for
enforcing
a
tolerance
for
imazaquin
residues
on
soybeans.

860.1360
Multiresidue
Methods
Imazaquin
and
its
metabolites
have
not
been
tested
for
recovery
via
FDA
Multiresidue
Protocols
(
PAM
Vol.
I)
and
it
is
unknown
whether
these
compounds
are
recoverable
by
the
Multiresidue
Protocols.

860.1380
Storage
Stability
Based
on
a
storage
stability
study,
imazaquin
is
stable
in
soybean
plants
and
seeds
stored
at
­
10
°
F
to
­
20
°
F
for
up
to
24
months
(
A.
Smith
1/
9/
86).
Additionally,
data
were
submitted
in
conjunction
with
the
corn
use
petition
depicting
the
stability
of
imazaquin
residues
in/
on
field
corn
commodities.
These
data
show
that
imaquazin
is
stable
in
corn
forage,
grain,
and
stover
stored
frozen
(­
20
°
C)
for
up
to
24
months
(
D216732,
W.
Wassell,
2/
11/
97).

The
storage
duration
and
conditions
from
harvest
to
analysis
of
the
crop
field
trial
soybean
samples
were
not
provided;
therefore,
a
determination
on
the
adequacy
of
the
submitted
storage
stability
data
cannot
be
determined
at
this
time.
The
registrant
should
submit
the
storage
stability
information
from
the
soybean
field
trials.

860.1400
Water,
Fish,
and
Irrigated
Crops
Imazaquin
is
not
presently
registered
for
direct
use
on
water
and
aquatic
food
and
feed
crops;
therefore,
no
residue
chemistry
data
are
required
under
these
guideline
topics.

860.1460
Food
Handling
Imazaquin
is
not
presently
registered
for
use
in
food­
handling
establishments;
therefore,
no
residue
chemistry
data
are
required
under
these
guideline
topics.

860.1480
Meat,
Milk,
Poultry,
and
Eggs
13
of
20
No
studies
pertaining
to
magnitude
of
the
residue
in
eggs,
milk,
and
meat
were
submitted.
Several
raw
agricultural
and
processed
commodities
of
soybean
may
be
utilized
as
livestock
feed
items.
Based
on
the
results
of
the
animal
metabolism
studies
where
livestock
were
dosed
at
94x
(
ruminant)
and
68x
(
poultry)
the
maximum
theoretical
dietary
burden,
there
is
no
reasonable
expectation
of
finite
imazaquin
residues
to
occur
in
meat,
milk,
poultry,
and
eggs
(
Category
3
of
40
CFR
§
180.6)
as
a
result
of
the
use
pattern
on
soybean.
Additionally,
soybean
seed
samples
treated
at
up
to
8x
maximum
application
rate,
had
no
detectable
residues
(<
0.05
ppm;)
of
imazaquin.
Soybean
forage,
hay,
and
straw
are
restricted
as
feed
items.
Therefore,
livestock
feeding
studies
or
tolerances
for
meat,
milk,
poultry,
and
eggs
are
not
required.
However,
HED
reserves
the
right
to
request
livestock
feeding
studies
in
the
future
if
additional
uses
on
crops
with
livestock
feed
items
are
proposed
for
registration.

Table
7.
Maximum
Theoretical
Dietary
Burden
(
MTDB)
for
Cattle,
Hogs,
and
Poultry
Feedstuff
Tolerance
Level,
ppm
%
Dry
Matter
(
DM)
%
of
Diet
Dietary
Burden
ppm*

Maximum
Theoretical
Dietary
Burden
for
Beef
and
Dairy
Cattle
soybean,
seed
0.05
89
15
0.008
Maximum
Theoretical
Dietary
Burden
for
Poultry
soybean,
seed
0.05
89
20
0.011
Maximum
Theoretical
Dietary
Burden
for
Hogs
soybean,
seed
0.05
89
25
0.014
*
Dietary
burden
=
(
tolerance
level
÷
dry
matter
fraction)
x
(%
of
diet).

860.1500
Crop
Field
Trials
American
Cyanamid
Company
has
submitted
field
trial
data
for
diisopropyl­
amine
salt
of
imazaquin
on
soybean.
Eleven
trials
were
conducted
in
AR(
2),
IA(
2),
LA,
MS(
2),
MO,
NC,
IN,
and
NJ.
According
to
the
current
OPPTS
Guideline
860.1500,
20
field
trials
(
or
15
if
no
quantifiable
residues
are
detected)
are
required.
However,
given
the
geographical
restrictions
on
current
labels
limiting
use
to
specific
states,
and
areas
of
states,
in
the
eastern
half
of
the
U.
S.,
11
field
trials
on
soybeans
are
considered
adequate.

Pre­
emergence,
as
well
as
post­
emergence,
ground
and
aerial
treatments
were
examined
in
the
submitted
field
trials.
One
or
two
applications
were
made
where
total
application
rates
ranged
from
0.25
lb
ae/
A
(
1x)
to
2
lb
ae/
A
(
8x).
Single
application
rates
ranged
from
0.125
lb
ae/
A
to
2
lb
ae/
A.
Seeds
were
harvested
in
all
locations
with
PHIs
ranging
from
98­
188
days.
PHIs
for
straw
(
collected
at
5
locations)
ranged
from
98­
147
days
and
PHIs
for
soybean
foliage
(
collected
at
3
locations)
were
30,
60,
and
90
days
(
R.
Loranger,
3/
28/
84;
A.
Smith
1/
9/
86).

The
storage
duration
from
time
of
harvest
to
analysis
was
not
provided.
Additionally,
it
was
noted
that
in
several
trials
the
plant
parts
were
held
at
room
temperature
for
10­
13
days
prior
to
shipment
to
the
analytical
laboratory.
Storage
stability
data
submitted
with
the
rotational
crop
studies
indicate
that
imazaquin
is
stable
in
soybeans
for
up
to
24
months.
14
of
20
Soybean
plants,
straw
and
soybean
seed
were
analyzed
using
Method
M­
1283
and
M­
1245,
respectively.
The
methods
have
since
been
replaced
by
Method
1410,
however
analysis
of
fortified
samples
(
0.05
­
1.0
ppm)
with
Methods
M­
1286
and
M­
1245
showed
acceptable
recoveries
(
92­
100%
for
plants,
80­
90%
for
straw,
and
86­
105%
for
beans).
Examination
of
the
chromatograms
and
raw
data
shows
no
real
difference
between
control
and
treated
plots.
Residues
of
imazaquin
were
<
0.05
ppm
in
all
samples
including
seeds,
foliage,
and
straw.
Residue
data
for
forage
and
hay
were
not
provided;
however,
the
labels
restrict
the
grazing
and
feeding
of
forage,
hay,
and
straw
to
livestock.

Residue
data
for
aspirated
grain
fractions
are
not
required
as
the
early
preharvest
use
of
imazaquin
is
not
expected
to
result
in
detectable
residues
in
soybean
seed.

860.1520
Processed
Food
and
Feed
Processed
food
and
feed
studies
were
not
submitted
for
soybean
meal,
hulls,
or
oil;
however,
these
studies
are
not
required
because
residues
were
nondetectable
in
soybeans
treated
at
2
lb
ai/
A
(
8x
the
current
maximum
application
rate).

860.1650
Submittal
of
Analytical
Reference
Standards
As
of
8/
16/
04,
an
analytical
reference
standard
for
imazaquin
is
available
at
the
EPA
National
Pesticide
Standards
Repository.

860.1850
Confined
Accumulation
in
Rotational
Crops
A
rotational
crop
residue
study
was
conducted
using
phenyl
14C­
labeled
imazaquin
(
37.97
mcCi/
mg)
mixed
with
quinoline
13C­
labeled
for
a
total
activity
of
19.0
mcCi/
mg.
The
chemical,
formulated
as
the
ammonium
salt
of
imazaquin,
was
applied
to
soil
at
the
rate
of
0.19
lbs
ai/
A
and
incorporated
2
inches.
Soybeans
were
planted
and
grown
to
maturity,
about
4.5
months.
Winter
wheat
was
planted
3
months
after
treatment
and
spring
wheat
and
field
corn
were
planted
8.5
months
after
treatment.
Carrots
and
lettuce
were
also
planted
9.5
months
after
treatment.
Soybean
plant
residue
were
removed
prior
to
follow
crop
planting
only
in
one
trial
(
winter
wheat)
(
RCB
Nos.
1768
and
1769,
M.
Metzger,
2/
2/
87).
The
total
radioactive
residue
(
TRR)
in
corn
RACs
was
below
0.01
ppm,
except
in
fodder
which
was
0.02
ppm.
The
maximum
TRR
observed
in
the
study
was
in
winter
wheat
straw
(
0.07
ppm).
Sixty
percent
of
the
wheat
straw
residue
was
extractable.
The
extractable
residue
was
separated
on
HPLC
into
7
­
9
unknown
compounds,
each
at
a
level
below
0.01
ppm
(
D194l81
&
D194180,
G.
Kramer,
6/
17/
94).
Based
on
the
results
of
the
confined
accumulation
study,
rotational
crop
restrictions
on
the
current
labels
are
adequate.
No
residues
were
identified
in
the
rotational
crop
study.

860.1900
Field
Accumulation
in
Rotational
Crops
15
of
20
Field
accumulation
in
rotational
crop
study
was
conducted
by
the
American
Cyanamid
Company
for
the
reduction
of
the
rotational
crop
tolerances
for
imazaquin
on
soybeans
followed
by
corn
(
MRIDs
42874001­
02).
The
study
was
in
support
of
the
reduction
of
the
plant
back
interval
to
be
readjusted
to
9.5
months,
instead
of
the
11
months
already
in
place.
Imazaquin
was
applied
to
the
following
soil
types:
loamy
sand
silt
(
IL),
loam
(
IN),
silty
clay
loam
(
OH),
silt
loam
(
GA),
and
silt
loam
(
IA)
at
a
rate
of
0.125
lb
ae/
A
in
both
pre­
plant
incorporation
and
post­
emergence
stages.
The
maximum
applied
rate
was
0.25
lbs
ae/
A.
At
three
sites,
imazaquin
was
applied
at
both
PPI
and
post­
emergence
stages.
At
the
other
three
sites,
imazaquin
was
applied
at
PPI
or
post­
emergence
on
separate
plots.
Soybeans
were
grown
to
maturity
and
harvested.
Corn
was
planted
281­
334
days
(
9.3
to
11
months)
after
final
imazaquin
treatment.
Corn
samples,
after
planting,
were
harvested
at
40­
41days
for
forage,
60­
93
days
for
early
silage,
84­
110
days
for
late
silage,
and
111­
181
days
for
grain
and
foddler.
Imazaquin
samples
were
analyzed
using
HPLC
with
UV
detection
in
method
M­
2124.
Method
M2124
is
adequate
for
collection
of
residue
data
for
imazaquin
per
se
from
samples
of
field
corn
forage,
silage,
grain,
and
stover
based
on
concurrent
method
recovery
data
submitted
with
the
study
(
87
±
6.1%
for
grain,
82
±
5.5%
for
forage
and
91
±
19%
for
fodder).
No
detectable
imazaquin
residues
were
detected,
i.
e.
all
sample
detections
were
<
0.05
ppm.

The
corn
samples
were
stored
frozen
for
eight
months.
Storage
stability
is
considered
adequate
based
on
the
stabilty
of
imazaquin
in
corn
for
24
months.

Based
on
the
submitted
confined
accumulation
and
field
accumulation
in
rotational
crop
studies,
HED
was
in
favor
of
the
proposed
label
amendment
to
reduce
the
plant
back
interval
from
eleven
months
to
nine
and
a
half
months
for
corn
(
D194l81
&
D194180,
G.
Kramer,
6/
17/
94).

Currently,
labels
specify
PBIs
from
3
to
11
months
for
most
rotated
crops.
PBIs
greater
than
11
months
are
specified
for
some
rotated
crops,
presumably
because
of
phytotoxicity
concerns.
Based
on
the
plant
back
intervals
(
PBIs)
used
in
the
confined
accumulation
study
and
field
accumulation
study,
where
no
residues
of
imazaquin
were
detected,
the
rotational
crop
restrictions
on
the
current
labels
are
adequate.
According
to
a
6/
28/
88
memo
from
R.
Taylor,
the
registrant
requested
reduced
rotational
crop
intervals.
EPA
indicated
that
rotational
crop
tolerances
would
be
necessary
for
the
reduction
of
the
restrictions
and
residue
data
would
need
to
be
submitted
that
would
support
the
proposed
tolerances.

Tolerance
Reassessment
for
Imazaquin
The
tolerance
for
residues
of
imazaquin
in/
on
plant
commodities
is
expressed
in
terms
of
residues
of
imazaquin
per
se
2­[
4,5­
dihydro­
4­
methyl­
4­(
1­
methylethyl)­
5­
oxo­
1Himidazol­
2­
yl]­
3­
quinoline
carboxylic
acid.
A
summary
of
the
imazaquin
tolerance
reassessment
for
soybeans
is
presented
in
Table
8.

Tolerances
Listed
Under
40
CFR
§
180.426:

A
tolerance
has
been
established
under
40
CFR
§
180.426
for
residues
of
imazaquin
in
or
on
soybeans.
Provided
that
the
deficiencies
cited
in
this
document
are
resolved,
HED
supports
the
current
tolerance
of
0.05
ppm.
16
of
20
TABLE
8.
Tolerance
Summary
for
Imazaquin
Commodity
Current
Tolerance
(
ppm)
Reassessed
Tolerance
(
ppm)
Comments
(
correct
commodity
definition)

Soybeans
0.05
0.05
Soybean,
seed
Codex/
International
Harmonization
There
are
no
Codex
or
Canadian
maximum
residue
limits
(
MRLs)
for
imazaquin.
Currently
in
Canada,
a
default
MRL
of
0.1
ppm
applies
when
specific
MRLs
have
not
been
established.
Based
on
this
consideration
and
the
fact
that
detectable
residues
of
imazaquin
are
not
expected
in
soybeans
from
its
current
U.
S.
uses,
the
lack
of
compatible
Codex
and
Canadian
MRLs
should
not
present
a
significant
trade
concern
for
U.
S.
growers.

RDI:
William
Donovan
(
10/
6/
05)
17
of
20
BIBLIOGRAPHY
Study
Citations
131546
American
Cyanamid
Co.
(
1983)
Product
Chemistry:
Scepter
Herbicide.
(
Compilation;
unpublished
study
received
Oct
14,
1983
under
241­
EX­
108;
CDL:
072010­
A)

131563
American
Cyanamid
Co.
(
1983)
Residue
Data
Chemistry:
Scepter
Herbicide.
(
Compilation;
unpublished
study
received
Oct
14,
1983
under
241­
EX­
108;
CDL:
072013­
A)

147012
American
Cyanamid
Co.
(
19??)
Residue
Chemistry:
Scepter
Herbicide.
Unpublished
compilation.
484
p.

159843
Gatterdam,
P.
(
1986)
Scepter
Herbicide,
Imazaquin
(
AC
252,214):
Residual
Radioactivity
in
Follow
Crops
(
Winter
Wheat,
Spring
Wheat...
Derived
Residues
at
Clayton,
NC.
Unpublished
study
pre­
pared
by
American
Cyanamid
Co.
177
p.

40622101
Gatterdam,
P.
(
1988)
Amended
Data
Submitted
Under
40
CFR
158.130
Rotational
Crops
(
Confined)
Guideline
No.
165­
1:
Scepter
Herbi­
cide:
Report
No.
PD­
M
Volume
23­
16.
Unpublished
study
prepared
by
American
Cyanamid
Co.
4
p.

41195000
Citation:
American
Cyanamid
Co.
(
1989)
Submission
of
Storage
Stability
Data
to
Support
the
Registration
of
SCEPTER
O.
T.
Herbicide
for
Use
in
Soybeans.

42874001
Dixon,
C.
(
1992)
Imazaquin
(
CL
252,214):
Validation
of
HPLC
Method
M2124
for
the
Determination
of
CL
252,214
Residues
in
Corn
Grain,
Whole
Grain
Plants,
and
Corn
Fodder:
Lab
Project
Number:
C3739:
0206:
SC91PT01.
Unpublished
study
prepared
by
American
Cyanamid
Co.
36
p.

42874002
Leonard,
R.
(
1992)
CL
252,214
(
Imazaquin):
Residues
of
CL
252,214
in
Field
Corn
Commodities
(
Forage,
Silage,
Grain
and
Fodder)
in
Field
Corn
Planted
Approximately
(
sic)
9.5
Months
after
Application
of
SCEPTER
Herbicide:
Lab
Project
Number:
C­
3823:
C­
3824:
C­
3825.
Unpublished
study
prepared
by
Huntingdon
Analytical
Service
and
American
Cyanamid
Co.
508
p.

43671601
Kao,
L.;
Robinson,
R.
(
1995)
CL
252,214:
Metabolism
of
(
Carbon­
14)
CL
252,214
in
Corn:
Lab
Project
Number:
M93P214OH1:
MET
95­
010:
RPT00194.
18
of
20
Unpublished
study
prepared
by
Xeno
Biotic
Labs,
Inc.
and
Battelle
Memorial
Institute.
332
p.

43671603
Leonard,
R.;
Baragary,
N.
(
1995)
CL
252,214
(
Imazaquin):
Residues
of
CL
252,214
in
Field
Corn
Commodities
(
Forage,
Silage,
Grain
and
Fodder)
in
Field
Corn
Treated
with
Either
a
PPI
or
PE
Application
of
SCEPTER
70DG
Herbicide:
Lab
Project
Number:
RES
94­
117:
RES
94­
118:
RES
94­
119.
Unpublished
study
prepared
by
ABC
Labs,
Inc.
and
American
Cyanamid
Co.
493
p.

43671604
Dixon,
C.
(
1995)
CL
252,214
(
Imazaquin):
Freezer
Stability
of
Imazaquin
(
CL
252,214)
Residues
in
Typical
Corn
Substrates:
Lab
Project
Number:
SC92PT05:
RES
94­
165.
Unpublished
study
prepared
by
American
Cyanamid
Co.,
Inc.
49
p
19
of
20
Agency
Memoranda
Citations.

Date
DP
Barcode
CB
No.
ID
Number
From
To
MRID
Nos.
Subject
3/
28/
84
 
 
PP#
4G2979
R.
Loranger
R.
Taylor
and
Toxicology
Branch
131546,
131563
(
Accession
Numbers
072010
and
072013)
Scepter
on
Soybeans.
Evaluation
of
Analytical
Method
and
Residue
Data.

2/
26/
86
 
 
PP#
5F3273
E.
Greer
C.
Trichilo
 
Scepter
in
Soybeans
3/
10/
86
 
RCB
No.
350
 
A.
Smith
R.
Taylor
 
EPA
registration
No.
241­
EIO:

Sceptor
in
Soybeans.
Letter
of
December
18,
1985
3/
13/
86
 
 
A.
Smith
A.
Murtagh
 
Method
and
materials
for
Method
M­
1410;
GC
method
for
the
determination
of
imazaquin
in
soybean
plants,
straw,
seed.

2/
2/
87
 
RCB
Nos.

1768,
1769
 
M.
Metzger
R.
Taylor
147012
(
Accession
No.

073703)
Imazaquin
(
scepter
Herbicide,

EPA
Reg.
No.
241­
289;
Scepter
Herbicide
Containing
Surfactant,

EPA
Reg.
No.
241­
292)
on
Soybeans.
Amendment
to
Modify
Rotational
Crop
Restrictions
5/
5/
88
 
 
 
J.
Stokes
RCB
files
 
Discussion
of
additional
residue
data
requirements
for
reduction
of
rotational
crop
restrictions
and/
or
establishment
of
rotational
crop
tolerances.

6/
22/
88
 
 
 
R.
Taylor
M.
Galley
 
Scepter
Herbicide
EPA
Registration
No.
241 
289
Scepter
Herbicide
Contains
Surfactant
EPA
Registration
No.
241 
292
Scepter
7ODG
Herbicide
EPA
Registration
No.
241 
306
Rotational
Crop
Restrictions
6/
17/
94
D194l81
&

D194180
 
000241­
00306
&

000241­
00289
G.
F.
Kramer
R.
Taylor
428740­
02
Review
of
limited
field
trials
whether
rotational
crop
tolerances
are
needed
for
imazaquin.
Agency
Memoranda
Citations.

Date
DP
Barcode
CB
No.
ID
Number
From
To
MRID
Nos.
Subject
20
of
20
1/
9/
86
 
RCB
No
1265
 
A.
Smith
R.
Taylor
147012,
146197
(
Accession
Nos.

073703,
073706,

073678)
PP#
5F3273:
Scepter
on
Soybeans.

Evaluation
of
Analytical
Method
and
Residue
Data.

2/
11/
97
D216732
CBTS
No.

15784
 
W.
Wassell
D.
McCall/
C.

Eiden
436716­
01
through
­

04.
PP#
5G04527.
Imazaquin
(
SCEPTER
70
DG)
in/
on
Field
Corn.
Review
of
Metabolism
Data,
Analytical
Methods,
and
Residue
Data.

Chemical
No.
128848;
Case:

286657
