Document ID: EPA-HQ-OPP-2002-0188-0019
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2002-09-16T04:00Z

UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
MEMORANDUM
05/
20/
2002
SUBJECT:
Hexazinone
Residue
Chemistry
Chapter
for
the
Tolerance
Reassessment
Eligibility
Decision
(TRED);
PC
Code
107201;
DP
Barcode
D279899;
Rereg.
Case
0266.

FROM:
John
S.
Punzi,
Ph.
D.,
Chemist
Reregistration
Branch
II
Health
Effects
Division
(7509C)

THROUGH:
Alan
Nielsen,
Branch
Senior
Scientist
Reregistration
Branch
II
Health
Effects
Division
(7509C)

and
Chemistry
Science
Advisory
Council
(Chem
SAC)
05/
15/
2002
Health
Effects
Division
(7509C)

TO:
Carol
Christensen,
Risk
Assessor
Reregistration
Branch
II
Special
Review
and
Reregistration
Division
(7509C)

and
Dirk
Helder,
Chemical
Review
Manager
Reregistration
Branch
II
Special
Review
and
Reregistration
Division
(7508W)

cc:
JSPunzi
(RRB2),
Hexazinone
Reg.
Std.
File,
Hexazinone
SF,
RF,
LAN.
RD/
I:
RRB2
Chem
Review
Team
(05/
12/
2002),
Alan
Nielsen
(05/
25/
2002).
7509C:
RRB2:
John
S.
Punzi:
CM2:
Rm
712M:
703­
305­
7727:
05/
08/
2002.
INTRODUCTION
Hexazinone
[3­
cyclohexyl­
6­(
dimethylamino)­
1­
methyl­
1,3,5­
triazine­
2,4(
1H,
3H)
dione
is
a
triazine­
dione
herbicide
registered
for
use
on
alfalfa,
blueberries,
pasture
and
range
grasses,
pineapple,
and
sugarcane.
It
is
also
registered
for
use
on
ornamental
plants,
forest
trees,
and
noncrop
areas.
Hexazinone
is
a
proprietary
chemical
of
E.
I.
du
Pont
de
Nemours
and
Company,
Inc.
which
is
the
sole
producer
and
primary
registrant
of
this
broad
spectrum
herbicide.
The
dry
flowable
(DF),
emulsifiable
concentrate
(EC),
and
soluble
concentrate
(SC)
are
the
formulation
classes
registered
to
du
Pont
with
food/
feed
uses.
These
formulations,
sold
under
the
trade
name
Velpar®,
may
be
applied
for
preemergence,
postemergence,
layby,
directed
spray,
or
basal
soil
treatments
using
ground
or
aerial
equipment.

EXECUTIVE
SUMMARY
OF
RESIDUE
CHEMISTRY
DATA
REQUIREMENTS
The
10/
8/
93
Residue
Chemistry
Chapter
required
label
amendments
for:
(1)
alfalfa
to
specify
a
30­
day
preharvest
interval
(PHI)
for
the
feeding
of
forage
and
cutting
of
hay;
(2)
blueberries
to
specify
PHIs
of
90
and
450
days
for
highbush
and
lowbush
varieties,
respectively.
These
label
revisions
remain
outstanding.
Details
of
the
required
label
amendments
are
presented
in
the
respective
endnote
for
GLN
860.1500
(Crop
Field
Trials)
in
Table
B.
Data
depicting
magnitude
of
the
residues
of
hexazinone
and
metabolites
A,
B,
C,
D,
and
E
in/
on
grass
forage
and
hay
harvested
0
day
following
a
single
broadcast
application
of
representative
formulations
at
1.125
lb
ai/
A
are
required.

GLN
860.1300:
Nature
of
the
Residue
­
Plants
The
qualitative
nature
of
the
residue
in
plants
is
adequately
understood.
Studies
indicate
that
root
uptake
is
the
principal
mechanism
for
the
absorption
of
hexazinone
by
plants
from
soils.
Hexazinone
is
translocated
through
the
xylem
to
the
foliage
where
it
blocks
the
photosynthetic
process.
The
HED
Metabolism
Assessment
Review
Committee
(MARC)
concluded
that
the
hexazinone
tolerance
expression
for
plants
and
rotational
crops
should
include
hexazinone
and
metabolites
A,
B,
C,
D,
and
E
(see
Figure
1
for
structures
and
proper
nomenclature).
Toxicity
data
for
the
metabolites
is
not
available;
but,
based
on
the
structural
similarity
of
the
metabolites,
it
is
assumed
they
will
exhibit
similar
toxicity
to
the
parent
hexazinone.
The
current
tolerance
expression
for
hexazinone
in
40
CFR
§180.396
is
for
"combined
residues
of
the
herbicide
hexazinone
(3­
cyclohexyl­
6­(
dimethylamino)­
1­
methyl­
1,3,5­
triazine2,4
1H,
3H)­
dione)
and
its
metabolites,
calculated
as
hexazinone."
The
tolerance
expression
should
be
modified
to
include
specific
metabolites
A,
B,
C,
D,
and
E,
identified
by
the
appropriate
name.

GLN
860.1300:
Nature
of
the
Residue
­
Livestock
The
qualitative
nature
of
the
residue
in
livestock
is
adequately
understood
based
on
acceptable
ruminant
and
poultry
metabolism
studies.
The
HED
MARC
concluded
that
the
hexazinone
tolerance
expression
for
ruminants
should
include
hexazinone
plus
metabolites
B,
C,
C­
2,
and
F
for
milk.
The
Committee
concluded
that
the
hexazinone
tolerance
expression
for
ruminant
tissue
should
include
hexazinone
plus
metabolites
B
and
F.
The
Committee
concluded
that
residues
of
hexazinone
and
metabolites
B,
C,
C1
C­
2,
and
F
should
be
taken
into
account
when
risk
assessments
are
done.

GLN
860.1340:
Residue
Analytical
Methods
Plant
Commodities
Adequate
methods
are
available
for
purposes
of
data
collection
and
enforcement
of
tolerances
for
residues
of
hexazinone
and
metabolites
A,
B,
C,
D,
and
E
in/
on
plant
commodities.

Livestock
Commodities
The
registrant
has
proposed
an
LC/
MS
method
(designated
as
du
Pont
AMR
3783­
96)
as
an
enforcement
method
for
livestock
commodities.
The
method
has
been
subjected
to
a
successful
ILV
and
a
radiovalidation
study
and
will
be
forwarded
to
the
Analytical
Chemistry
Branch
for
a
tolerance
method
validation
by
Agency
chemists.
If
the
results
of
method
validation
by
Agency
chemists
are
successful,
then
Method
AMR
3783­
96
will
be
proposed
for
inclusion
in
PAM
Volume
II,
and
no
additional
data
concerning
this
GLN
topic
will
be
required
for
reregistration.

GLN
860.1360:
Multiresidue
Methods
The
reregistration
requirements
for
multiresidue
methods
data
are
fulfilled.

GLN
860.1380:
Storage
Stability
Plant
Commodities
No
additional
storage
stability
data
for
plant
and
processed
commodities
are
required
for
reregistration.

Livestock
Commodities
Adequate
storage
stability
data
are
available
to
support
the
existing
ruminant
feeding
study.

GLN
860.1500:
Crop
Field
Trials
Berries
Group
Blueberry
The
10/
8/
93
Residue
Chemistry
Chapter
concluded
that
no
additional
data
are
required
for
blueberries
provided
all
pertinent
product
labels
are
amended
to
specify
PHIs
of
90
and
450
days
for
application
to
highbush
and
lowbush
blueberries,
respectively.
Based
on
the
combined
LOQs
(0.55
ppm)
of
the
enforcement
method
for
parent
plus
metabolites,
HED
recommends
that
the
RAC
tolerance
be
increased
from
0.2
ppm
to
0.60
ppm.

Grass
Forage,
Fodder,
and
Hay
Group
Grass
(pasture
and
rangeland)
forage
An
examination
of
registered
uses
of
hexazinone
on
pasture
and
rangeland
grasses
(see
Table
A2)
reveal
that
there
two
distinct
use
patterns,
a
basal
soil
application
and
a
broadcast
application.
It
is
noted
that
the
10­
ppm
tolerance
for
grass
forage
(listed
as
"grasses,
pasture"
and
"grasses,
range"
under
40
CFR
§180.396)
was
established
based
on
residue
data
reflecting
basal
soil
application
only.
In
the
absence
of
residue
data
reflecting
broadcast
application,
HED
is
requiring
the
following
additional
data
for
grass
forage
before
the
RAC
tolerance
can
be
reassessed:
Data
depicting
magnitude
of
the
residues
of
hexazinone
and
metabolites
A,
B,
C,
D,
and
E
in/
on
grass
forage
harvested
0
day
following
a
single
broadcast
application
of
representative
formulations
at
1.125
lb
ai/
A.
It
is
HED
policy
to
require
0­
day
crop
field
residue
data
for
grass
forage
unless
it
is
not
feasible
(e.
g.,
preplant/
preemergence
pesticide
uses).
The
formulations
to
be
tested
may
be
applied
in
side­
by­
side
plots.
The
location
and
number
of
trials
should
be
in
compliance
with
the
current
OPPTS
GLN
for
adequate
geographic
representation
of
data.

Grass
(pasture
and
rangeland)
hay
The
reregistration
requirements
for
residue
data
on
grass
hay
have
not
been
fulfilled.
The
registrant
has
submitted
a
petition
(PP#
1F3967),
for
the
establishment
of
a
tolerance
for
residues
of
hexazinone
and
its
metabolites
in/
on
grass
hay.
The
petition
is
currently
in
reject
status
because
grass
hay
data,
from
field
trials
with
adequate
geographical
representation,
remain
outstanding.
Since
1991
HED
has
reviewed
two
proposals
to
amend
the
original
petition
requesting
that
the
Agency
establish
tolerances
for
grass
hay
based
on
theoretical
grass
drying
factors.
HED
recommended
against
the
establishment
of
grass
hay
tolerances
each
time.
In
addition,
HED
reviewed
two
registrant
responses
to
the
petition
amendment
reviews
and
concluded
in
each
case
that
the
recommendation
to
require
actual
field
trial
data
for
grass
hay
is
appropriate.

Non­
Grass
Animal
Feeds
(Forage,
Fodder,
Straw,
and
Hay)
Group
Alfalfa
forage
and
hay
The
Updated
Table
A
for
Residue
Chemistry
RED
Chapter
dated
9/
8/
94
concluded
that
adequate
residue
data
are
available
for
alfalfa
forage
and
hay.
However,
label
amendments
were
required
on
all
product
labels
for
alfalfa,
including
supplemental
labels,
to
establish
a
30­
day
PHI
for
the
feeding
of
forage
and
the
cutting
of
hay.

The
available
residue
data
indicate
that
the
combined
residues
of
hexazinone
and
its
metabolites
A,
B,
C,
D,
and
E
in/
on
treated
samples
were
<1.87
ppm
and
<3.33
ppm
for
alfalfa
forage
and
hay,
respectively.
Based
on
these
data,
the
established
tolerance
for
alfalfa
forage
is
reassessed
at
its
existing
level
of
2.0
ppm;
however,
the
tolerance
for
alfalfa
hay
should
be
lowered
from
8.0
ppm
to
4.0
ppm.
Table
A2
shows
that
product
labels
for
the
90%
SC
(EPA
Reg.
No.
352­
378)
and
75%
DF
(EPA
Reg.
No.
352­
58)
formulations
have
been
revised
in
compliance
with
previously
requested
label
amendment.
However,
the
product
label
for
the
2
lb/
gal
EC
(EPA
Reg.
No.
352­
392)
formulation
does
not
specify
any
PHI;
this
label
must
be
amended
to
establish
a
30­
day
PHI
(or
pregrazing
interval)
for
the
feeding
of
forage
and
the
cutting
of
hay.

Alfalfa
seed
The
available
residue
data
indicate
that
the
combined
residues
of
hexazinone
and
its
regulated
metabolites
ranged
from
<1.30
ppm
to
<1.46
ppm
in/
on
alfalfa
seed
following
a
single
broadcast
dormant
application
of
the
2
lb/
gal
EC
or
90%
SC
formulation
at
0.75
lb
ai/
A
(1.5x
the
maximum
registered
rate
on
alfalfa
grown
for
seed);
no
data
were
submitted
reflecting
1.0x.
HED
is
requesting
the
registrant
to
propose
a
tolerance
for
hexazinone
residues
of
concern
in/
on
alfalfa
seed
of
2.0
ppm.

Miscellaneous
Pineapple
The
available
data
indicate
that
the
combined
residues
of
hexazinone
and
its
regulated
metabolites
were
<0.35
ppm
in/
on
pineapple
fruits
harvested
at
a
minimum
PHI
of
181
days
following
five
ground
applications
of
a
representative
hexazinone
formulation
at
0.45­
0.9
lb
ai/
A
for
a
total
rate
of
3.6
lb
ai/
A.
Based
on
the
combined
LOQs
(0.55
ppm)
of
the
enforcement
method,
HED
is
now
recommending
that
the
RAC
tolerance
be
increased
from
0.5
ppm
to
0.60
ppm.

Sugarcane
The
available
data
indicate
that
the
combined
residues
of
hexazinone
and
its
regulated
metabolites
were
<0.35
ppm
in/
on
samples
of
sugarcane
treated
with
the
90%
SC
formulation
of
hexazinone
from
the
following
test
locations:
(i)
in
Puerto
Rico
where
sugarcane
was
harvested
288
days
following
a
single
postemergence
application
at
0.45
lb
ai/
A
(0.5x
the
maximum
registered
seasonal
rate
for
this
area);
(ii)
in
TX
where
sugarcane
was
harvested
234
days
following
one
preemergence
application
followed
by
one
postemergence
application
at
0.675
lb
ai/
A/
application
(0.75x
the
maximum
seasonal
rate
in
TX);
and
(iii)
in
HI
where
sugarcane
was
harvested
179­
181
days
following
a
total
of
four
applications
(one
preemergence
application
at
1.35
or
1.47
lb
ai/
A,
a
postemergence
application
at
0.45
lb
ai/
A/
application,
followed
by
two
postemergence
applications
at
1.8
lb
ai/
A/
application)
for
a
total
rate
of
5.4­
5.5
lb
ai/
A/
season
(1.5x
the
maximum
seasonal
rate
in
HI).
Based
on
the
combined
LOQs
(0.55
ppm)
of
the
enforcement
method,
HED
is
now
recommending
that
the
RAC
tolerance
be
increased
from
0.20
ppm
to
0.60
ppm.
GLN
860.1520:
Processed
Food/
Feed
Pineapple
process
residue
and
juice
Residues
of
hexazinone
and
its
regulated
metabolites
did
not
concentrate
in
pineapple
process
residue
and
juice
except
for
Metabolite
B
in
process
residue.
The
registrant
calculated
a
concentration
factor
of
3.0x
for
Metabolite
B
in
pineapple
process
residue
based
on
quantified
residues
of
0.06
ppm
in
pineapple
process
residue
and
0.02
ppm
in/
on
pineapple
RAC
after
treatment
with
hexazinone
at
a
1.0x
rate.
When
this
concentration
factor
of
3.0x
is
multiplied
by
the
highest
average
field
trial
(HAFT)
residue
of
<0.05
ppm,
the
maximum
expected
residues
of
metabolite
B
in
pineapple
process
residue
is
0.15
ppm
which
is
less
than
the
reassessed
RAC
tolerance
of
0.60
ppm.
Therefore,
no
tolerance
for
pineapple
process
residues
is
warranted.

Sugarcane
molasses
and
refined
sugar
An
acceptable
sugarcane
processing
study
is
available.
Following
processing
of
the
RAC
according
to
simulated
commercial
practices,
residues
of
hexazinone
and/
or
metabolites
A
through
E
concentrated
in
"A
molasses"
(4.0x).
However,
residues
declined
in
raw
sugar
(reduction
factor
of
0.2x)
and
processed
sugar
(reduction
factor
of
0.2x).
Adjusting
for
the
degree
of
exaggeration
(2.0x)
used
in
the
processing
study,
the
residue
for
blackstrap
molasses
is
3.83
ppm.
The
available
data
suggest
that
the
established
tolerance
for
sugarcane
molasses
should
be
decreased
from
5.0
ppm
to
4.0
ppm.

GLN
860.1480:
Meat,
Milk,
Poultry,
and
Eggs
The
results
of
ruminant
metabolism
study
suggest
significant
transfer
of
hexazinone
residues
of
concern
to
meat
and
milk.
The
registrant
has
submitted
a
dairy
cattle
feeding
study
(MRID
43703501)
which
was
deemed
acceptable.
HED
is
recommending
that;
in
order
to
reassess
the
established
hexazinone
tolerances
for
milk
and
the
fat,
meat,
and
meat
byproducts
of
livestock
and
to
compute
a
maximum
theoretical
dietary
burden
(MTDB)
of
hexazinone
to
livestock,
uses
on
pasture
and
rangeland
grasses
be
cancelled.
A
MTDB
could
not
be
calculated
including
grass
and
grass
hay
since
additional
residue
data
are
required
for
use
patterns
for
which
significant
residues
are
expected
in/
on
the
RACs.
HED
recognizes
that
the
estimated
100,000
acres
of
pasture
and
rangeland
treated
with
hexazinone
is
relatively
low.
However,
since
grass
and
grass
hay
are
considered
major
dietary
components
of
ruminants
(up
to
60%
of
the
diet
per
current
OPPTS
GLN),
a
MTDB
for
livestock
could
not
be
developed
when
grasses
are
included.
HED
has
determined
that
a
MTDB
could
be
constructed
from
potential
feed
items
for
livestock
and
subsequently
tolerances
for
meats
and
milk
can
be
reassessed.
HED
has
previously
determined
that
tolerances
in
poultry
commodities
and
a
poultry
feeding
study
are
not
required
for
reregistration
based
on
results
of
reviewed
poultry
metabolism
data.

A
brief
summary
of
the
reviewed
dairy
cattle
feeding
study
(MRID
43703501)
is
presented
below.
Three
groups
of
dairy
cows
(3
animals/
dose
group)
were
dosed
with
hexazinone
at
29,
87,
and
290
ppm
in
the
diet
for
28
consecutive
days;
three
additional
cows
served
as
control
animals.
These
dose
levels
are
equivalent
to
6.25x,
18.75x,
and
62.5x,
respectively,
the
MTDB
for
beef
and
dairy
cattle.
These
dose
levels
are
equivalent
to
64x,
190x,
and
640x
the
MTDB
for
hogs.

The
maximum
total
hexazinone
residues
in
milk
were
0.78
ppm
at
the
6.25x
feeding
level
(29
ppm
in
the
diet)
and
11.09
ppm
at
the
62.5x
level.
On
day­
14,
after
total
residues
had
reached
plateaus,
milk
was
separated
into
skim
milk
and
cream.
Total
residues
in
skim
milk
were
comparable
to
those
in
whole
milk;
total
residues
in
cream
were
approximately
half
those
in
skim
milk.
In
tissues,
the
maximum
total
hexazinone
residues
at
the
62.5x
feeding
level
were
3.85
ppm
in
liver,
2.19
ppm
in
kidney,
0.32
ppm
in
muscle,
and
nondetectable
(
#
0.10
ppm)
in
fat.
The
maximum
total
residues
at
the
6.25x
feeding
level
were
0.24
ppm
in
liver,
0.47
ppm
in
kidney,
and
nondetectable
(
#
0.15
ppm)
in
muscle.
Because
total
residues
were
nondetectable
in
all
fat
samples
from
the
18.75x
and
62.5x
levels,
fat
samples
were
not
analyzed
at
lower
feeding
levels.

A
tolerance
of
0.5
ppm
is
presently
established
for
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone)
in
milk.
Based
on
the
MTDB
for
beef
and
dairy
cattle
without
grass
or
grass
hay
as
a
potential
feed
item,
it
is
possible
to
reassess
the
animal
commodity
tolerances.
The
HED
Metabolism
Assessment
Review
Committee
has
concluded
that
the
hexazinone
tolerance
expression
for
ruminants
should
include
hexazinone
plus
metabolites
B,
C,
C­
2,
and
F
for
milk.
Residue
levels
of
hexazinone
and
metabolites
in
whole
milk
from
the
feeding
study
corrected
for
exaggeration
levels
ranged
from
0.110
ppm
to
0.164
ppm.
Based
on
the
enforcement
method,
the
sum
of
the
LOQ's
for
hexazinone
and
metabolites
B,
C,
C­
2,
and
F
is
0.20
ppm
;
therefore
it
is
appropriate
that
the
tolerance
for
milk
be
reduced
from
0.5
to
0.20
ppm.

Tolerances
of
0.1
ppm
are
presently
established
for
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone)
in
meat.
Residue
levels
of
hexazinone
and
metabolites
in
muscle
from
the
feeding
study
corrected
for
exaggeration
levels
ranged
from
0.003
ppm
to
0.039
ppm.
Based
on
the
enforcement
method,
the
sum
of
the
LOQ's
for
hexazinone
and
metabolites
B
and
F
is
0.10
ppm
therefore
it
is
appropriate
that
the
tolerance
for
meat
byproducts
of
cattle,
goats,
horses,
and
sheep
be
reassessed
at
0.10
ppm.
Residue
levels
of
hexazinone
and
metabolites
in
muscle
from
the
feeding
study
corrected
for
exaggeration
levels
ranged
from
0.0004
ppm
to
0.002
ppm
therefore
tolerances
for
hog
meat
are
not
required.

Tolerances
of
0.1
ppm
are
presently
established
for
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone)
in
meat
byproducts
of
cattle,
goats,
hogs,
horses,
and
sheep.
Residue
levels
of
hexazinone
and
metabolites
in
kidney
from
the
feeding
study
corrected
for
exaggeration
levels
ranged
from
0.046
ppm
to
0.090
ppm.
Based
on
the
enforcement
method,
the
sum
of
the
LOQ's
for
hexazinone
and
metabolites
B
and
F
is
0.10
ppm;
therefore,
it
is
appropriate
that
the
tolerance
for
meat
byproducts
of
cattle,
goats,
horses,
and
sheep
be
reassessed
at
0.10
ppm.
Residue
levels
of
hexazinone
and
metabolites
in
kidney
from
the
feeding
study
corrected
for
exaggeration
levels
ranged
from
0.003
ppm
to
0.007
ppm
therefore
tolerances
for
hog
meat
byproducts
are
not
required
and
should
be
revoked.

Tolerances
of
0.1
ppm
are
presently
established
for
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone)
in
fat.
Residue
levels
of
hexazinone
and
metabolites
in
fat
from
the
feeding
study
were
nondetectable
<0.1
ppm
at
the
62.5x
exaggerated
rate.
HED
has
determined
that
tolerances
for
hexazinone
residues
in
fat
of
cattle,
goats,
hogs,
horses,
and
sheep
are
not
required.
Tolerances
for
fat
of
cattle,
goats,
hogs,
horses,
and
sheep
are
not
required
and
should
be
revoked.

GLN
860.1850:
Confined
Accumulation
in
Rotational
Crops
The
data
requirements
for
confined
rotational
crops
are
satisfied.

GLN
860.1900:
Field
Accumulation
in
Rotational
Crops
The
data
requirements
for
field
accumulation
in
rotational
crops
are
only
partially
satisfied.
This
conclusion
is
based
on
a
recent
review
of
a
limited
field
crop
rotation
study
wherein
the
75%
DF
formulation
of
hexazinone
was
applied
as
a
single
postemergence
broadcast
application
to
mowed
alfalfa
at
1.5
lb
ai/
A
(1x
the
maximum
seasonal
rate
for
alfalfa).
Approximately
one
year
following
application,
the
remaining
alfalfa
crop
residue
was
plowed
up
and
returned
to
the
soil,
and
head
lettuce,
field
corn,
and
wheat
were
planted.

Residues
were
below
the
respective
method
LOQs
for
hexazinone
and
metabolites
A,
B,
C,
D,
E,
F,
G,
H,
G3170,
G3170­
NG,
A­
1,
and
C­
1
in/
on
head
lettuce,
wheat
forage
and
grain,
and
field
corn
forage
and
grain.
In
wheat
straw,
residues
of
metabolite
B
were
<0.02­
0.021
ppm;
residues
of
hexazinone
and
the
remaining
metabolites
were
below
the
LOQ.
In
field
corn
stover,
residues
of
hexazinone
were
0.02­
0.081
ppm,
residues
of
metabolite
B
were
0.038­
0.053
ppm,
and
residues
of
the
remaining
metabolites
were
below
the
LOQ.

These
data
indicate
that
extended
field
rotational
crop
studies
and
rotational
crop
tolerances
will
not
be
required
for
residues
of
hexazinone
residues
of
concern
in/
on
leafy
vegetables
provided
that
labels
are
amended
to
specify
a
rotational
crop
restriction
of
at
least
12
months.
A
previous
review
of
a
confined
rotational
crop
study
concluded
that
rotational
crop
tolerances
were
not
needed
for
root
crops
provided
that
a
12­
month
plantback
interval
was
established;
an
examination
of
the
basic
registrant's
labels
shows
that
the
12­
month
plantback
interval
for
root
crops
has
been
established.

Because
the
data
from
the
limited
field
trials
indicate
that
quantifiable
residues
occur
in
field
corn
stover
and
wheat
straw,
extended
field
rotational
crop
trials
for
corn
stover,
sorghum
stover,
and
wheat
straw
to
support
a
12­
month
rotational
interval
and
a
tolerance
for
inadvertent
hexazinone
residues
are
required.
HEXAZINONE
TRED:
RESIDUE
CHEMISTRY
CONSIDERATIONS
PC
Code
107201;
Case
0266
(DP
Barcode
279899)

TABLE
OF
CONTENTS
page
INTRODUCTION
.........................................................
1
REGULATORY
BACKGROUND
............................................
1
SUMMARY
OF
SCIENCE
FINDINGS........................................
2
GLN
860.1200:
Directions
for
Use
......................................
2
Product
List
....................................................
2
Food/
Feed
Use
Pattern
Table
.......................................
3
Rotational
Crop
Restrictions
.......................................
4
GLN
860.1300:
Nature
of
the
Residue
­
Plants
............................
12
GLN
860.1300:
Nature
of
the
Residue
­
Livestock
.........................
16
GLN
860.1340:
Residue
Analytical
Methods
.............................
18
Plant
Commodities
..............................................
18
Animal
Commodities
............................................
19
GLN
860.1360:
Multiresidue
Methods
..................................
20
GLN
860.1380:
Storage
Stability
Data
..................................
20
Plant
Commodities
..............................................
20
Animal
Commodities
............................................
21
GLN
860.1500:
Crop
Field
Trials
......................................
21
Berries
Group..................................................
21
Blueberry
................................................
21
Grass
Forage,
Fodder,
and
Hay
Group
..............................
22
Grass
(pasture
and
rangeland)
forage...........................
22
Grass
(pasture
and
rangeland)
hay.............................
22
Non­
Grass
Animal
Feeds
(Forage,
Fodder,
Straw,
and
Hay)
Group
........
23
Alfalfa
forage
and
hay
......................................
23
Alfalfa
seed
..............................................
23
Miscellaneous
Commodities
......................................
24
Pineapple
................................................
24
Sugarcane
................................................
24
GLN
860.1520:
Processed
Food/
Feed
...................................
25
Pineapple
process
residue
and
juice............................
25
Sugarcane
molasses
and
refined
sugar..........................
25
GLN
860.1480:
Meat,
Milk,
Poultry,
and
Eggs
............................
26
Maximum
theoretical
dietary
burden
(tentative)
..................
26
Table
of
Contents
(continued)
page
ix
Dairy
cattle
feeding
study
...................................
27
GLN
860.1400:
Water,
Fish,
and
Irrigated
Crops
..........................
28
GLN
860.1460:
Food
Handling
........................................
28
GLN
860.1850:
Confined
Accumulation
in
Rotational
Crops
.................
28
GLN
860.1900:
Field
Accumulation
in
Rotational
Crops
....................
28
TOLERANCE
REASSESSMENT
SUMMARY
................................
35
Tolerances
Listed
Under
40
CFR
§180.396
(a)
.............................
36
Tolerances
Needed
Under
40
CFR
§180.396
(a)
...........................
36
Tolerances
Listed
Under
40
CFR
§180.396
(c)
.............................
36
CODEX
HARMONIZATION
..............................................
38
AGENCY
MEMORANDA
CITATIONS
.....................................
39
STUDY
CITATIONS
.....................................................
45
N
N
N
O
O
CH
3
N
CH
3
CH
3
HEXAZINONE
TRED
­
REPORT
ON
FQPA
TOLERANCE
REASSESSMENT
PROGRESS
AND
INTERIM
RISK
MANAGEMENT
DECISION:

RESIDUE
CHEMISTRY
CONSIDERATIONS
PC
Code
107201;
Case
0266
INTRODUCTION
Hexazinone
[3­
cyclohexyl­
6­(
dimethylamino)­
1­
methyl­
1,3,5­
triazine­
2,4(
1H,
3H)dione
is
a
triazine­
dione
herbicide
registered
for
use
on
alfalfa,
blueberries,
pasture
and
range
grasses,
pineapple,
and
sugarcane.
It
is
also
registered
for
use
on
ornamental
plants,
forest
trees,
and
noncrop
areas.
Hexazinone
is
a
proprietary
chemical
of
E.
I.
du
Pont
de
Nemours
and
Company,
Inc.
(Dupont)
which
is
the
sole
producer
and
primary
registrant
of
this
broad
spectrum
herbicide.
The
dry
flowable
(DF),
emulsifiable
concentrate
(EC),
and
soluble
concentrate
(SC)
are
the
formulation
classes
registered
to
du
Pont
with
food/
feed
uses.
These
formulations,
sold
under
the
trade
name
Velpar®,
may
be
applied
as
preemergence,
postemergence,
layby,
directed
spray,
or
basal
soil
treatments
using
ground
or
aerial
equipment.

REGULATORY
BACKGROUND
Hexazinone
was
first
registered
by
the
Agency
in
November
1975
for
general
weed
control
in
non­
cropland
areas.
Uses
on
Christmas
trees
and
forest
trees
were
added
in
1977.
Use
patterns
for
the
culture
of
sugarcane
and
alfalfa
were
conditionally
registered
in
1980
and
1981,
respectively.

The
Agency
has
issued
several
regulatory
documents
summarizing
the
reregistration
status
of
hexazinone.
In
February
1982,
the
Agency
issued
a
Pesticide
Registration
Standard
for
hexazinone
which
identified
data
gaps
according
to
guidelines
then
in
place.
After
issuance
of
the
1982
Standard,
new
uses
for
hexazinone
were
established
on
blueberries,
rangeland
and
pasture
grasses,
and
pineapple.
A
second
Registration
2
Standard
was
issued
in
September,
1988
(NTIS#
PB89­
126080).
The
1988
Standard
summarized
available
data
supporting
the
registration
of
products
containing
hexazinone
as
the
active
ingredients
and
required
additional
residue
chemistry
data
among
other
requirements.
Hexazinone
was
also
the
subject
of
a
Final
Registration
Standard
and
Tolerance
Reassessment
(FRSTR)
Residue
Chemistry
Chapter
dated
5/
25/
88,
a
Reregistration
Standard
Update
to
the
Residue
Chemistry
Chapter
dated
9/
5/
91,
and
Product
and
Residue
Chemistry
Chapters
for
Hexazinone
Reregistration
Eligibility
Decision
(RED)
document
in
10/
8/
93.
An
Updated
Table
A
for
Hexazinone
Residue
Chemistry
Chapter
RED
was
issued
in
9/
8/
94
in
order
to
reflect
the
conclusions
of
reviews
completed
since
the
RED
Chapter
was
completed.

The
10/
8/
93
Residue
Chemistry
Chapter
to
the
Hexazinone
RED
required
label
revisions
for
alfalfa,
blueberry,
pineapple,
and
sugarcane
in
order
to
reflect
use
pattern
parameters
for
which
residue
data
are
available.
In
addition,
the
10/
8/
93
Residue
Chapter
required
additional
residue
chemistry
data
pertaining
to:
animal
metabolism
(additional
data
were
required
to
upgrade
an
existing
ruminant
study);
residue
analytical
methods
(an
enforcement
method
is
required
for
determination
of
hexazinone
residues
of
concern
in
milk,
meat,
and
meat
byproducts
of
ruminants);
storage
stability
(alfalfa
and
certain
metabolites
for
grass);
magnitude
of
the
residue
in/
on
grass
hay,
sugarcane,
and
in
the
processed
commodities
of
pineapple
and
sugarcane;
and
rotational
crops.
The
basic
registrant,
DuPont,
has
submitted
most
of
the
requested
residue
chemistry
data
which
have
been
evaluated
by
HED.

This
document
is
a
comprehensive
update
to
the
10/
8/
93
Residue
Chapter,
and
the
information
contained
herein
incorporates
HED's
conclusions
of
recently
reviewed
residue
chemistry
studies
as
well
as
a
reassessment
of
hexazinone
tolerances,
as
mandated
by
the
Food
Quality
Protection
Act
(FQPA)
of
1996.

Hexazinone
tolerances
are
established
under
40
CFR
§180.396
(a)
and
(b).
The
tolerance
expression,
for
plant
and
animal
commodities,
is
in
terms
of
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone).
An
adequate
enforcement
method
is
available
for
determination
of
regulated
hexazinone
residues
in/
on
plants.
The
registrant
has
proposed
an
LC/
MS
method
(designated
as
du
Pont
method
AMR
3783­
96)
as
an
enforcement
method
for
livestock
commodities.
The
method
has
been
subjected
to
a
successful
ILV
and
a
radiovalidation
study
and
will
be
forwarded
to
the
Analytical
Chemistry
Branch
for
a
tolerance
method
validation
by
Agency
chemists.
If
the
results
of
method
validation
by
Agency
chemists
are
successful,
then
Method
AMR
3783­
96
will
be
proposed
for
inclusion
in
PAM
Volume
II,
and
no
additional
data
concerning
this
GLN
topic
will
be
required
for
reregistration.

SUMMARY
OF
SCIENCE
FINDINGS
3
GLN
860.1200:
Directions
for
Use
Product
List
A
search
of
the
Agency's
Reference
Files
System
(REFS)
database,
conducted
on
7/
26/
01,
identified
three
active
hexazinone
end­
use
products
(EPs)
registered
to
the
basic
registrant
(DuPont)
under
FIFRA
Section
3
for
use
on
food
and
feed
crops.
There
are
also
eight
products
registered
under
Section
24
(c).
These
products
are
listed
below
in
Table
A1.

Table
A1.
Hexazinone
EPs
with
Uses
on
Feed/
Food
Crops
Registered
to
E.
I.
du
Pont
de
Nemours
and
Company.
EPA
Reg
No.
Label
Acceptance
Date
Formulation
Class
Product
Name
352­
378
1
3/
27/
98
90%
SC
DuPont
Velpar
®
Herbicide
352­
392
2
5/
22/
01
2
lb/
gal
EC
DuPont
Velpar
®
L
Herbicide
352­
581
3
5/
22/
01
75%
DF
DuPont
Velpar
®
DF
Herbicide
1
Including
SLN
TX940008.
2
Including
SLN
ME980002,
MT940001,
NC830012,
and
WY920001.
3
Including
SLN
ME980003,
ND970002,
and
SD970001.

Food/
Feed
Use
Pattern
Table
A
summary
of
hexazinone
food/
feed
use
patterns,
based
on
the
product
labels
registered
to
E.
I.
duPont
de
Nemours
and
Company,
is
presented
in
Table
A2.
The
application
rates
listed
in
Table
A2
depend
on
soil
texture
(coarse,
medium,
and
fine)
and
percent
organic
matter
(OM)
in
the
soil;
a
higher
rate
is
recommended
for
soil
with
organic
matter
greater
than
5%.
Use
on
gravelly
or
rocky
soils,
exposed
subsoils,
hardpan,
sand,
poorly
drained
soil,
or
alkali
soils
is
prohibited.
Unless
otherwise
specified,
applications
may
be
made
in
a
minimum
of
5
gal/
A
by
air
or
in
a
minimum
of
20
gal/
A
using
ground
equipment.

A
tabular
summary
of
the
residue
chemistry
science
assessments
for
reregistration
of
hexazinone
is
presented
in
Table
B.
The
status
of
reregistration
requirements
for
each
guideline
topic
listed
in
Table
B
is
based
on
the
use
patterns
registered
to
the
basic
registrant.
When
end­
use
product
DCIs
are
developed
(e.
g.,
at
issuance
of
the
RED),
RD
should
require
that
all
end­
use
product
labels
(e.
g.,
MAI
labels,
SLNs,
and
products
subject
to
the
generic
data
exemption)
be
amended
such
that
they
are
consistent
with
the
label
of
the
basic
registrant.

The
10/
8/
93
Residue
Chapter
required
label
amendments
for:
(1)
alfalfa
to
specify
a
30­
day
preharvest
interval
(PHI)
for
the
feeding
of
forage
and
cutting
of
hay;
(2)
blueberries
to
specify
PHIs
of
90
and
450
days
for
highbush
and
lowbush
varieties,
respectively;
(3)
pineapple
to
specify
a
maximum
application
rate
of
3.6
lb
4
ai/
A/
cropping
cycle
and
a
minimum
PHI
of
181
days;
(4)
pineapple
forage
to
include
a
pineapple
forage
feeding
restriction;
and
(5)
sugarcane
to
specify
use
rates
if
hexazinone
were
to
be
registered
in
the
state
of
FL.

The
registrant
has
complied
with
some
of
the
previously
requested
label
amendments;
however,
label
revisions
remain
outstanding
for
alfalfa
and
blueberries;
details
of
the
required
label
amendments
are
presented
in
the
respective
endnote
for
GLN
860.1500
(Crop
Field
Trials)
in
Table
B.

Rotational
Crop
Restrictions
The
following
rotational
crop
restrictions
have
been
established
for
the
90%
SC
(EPA
Reg.
No.
352­
378),
2
lb/
gal
EC
(EPA
Reg.
No.
352­
378),
and
75%
DF
(EPA
Reg.
No.
352­
581)
following
use
of
hexazinone
on
alfalfa:
(i)
do
not
replant
treated
areas
to
any
crop
except
corn,
root
crops
or
sugarcane
within
two
years
after
treatment,
as
crop
injury
may
result;
(ii)
corn
may
be
planted
12
months
after
the
last
treatment,
provided
the
use
rate
did
not
exceed
0.75
lb
per
acre,
except
in
areas
of
low
rainfall
(20"
or
less);
(iii)
root
crops
such
as
potatoes,
sugar
beets,
radish
and
carrots
may
be
planted
12
months
after
the
last
treatment,
provided
the
use
rate
did
not
exceed
0.5
lb/
A.
Sites
with
use
rates
higher
than
0.5
lb/
A
should
not
be
replanted
to
any
crop
within
2
years
of
application,
or
unacceptable
crop
injury
may
result;
(iv)
sugarcane
may
be
planted
any
time
following
treatment;
(v)
in
CA,
do
not
replant
seed
alfalfa
areas
to
any
crop
within
two
years
after
treatment,
as
crop
injury
may
result.

Based
on
the
results
of
a
recently
reviewed
field
accumulation
study
(MRID
45084101)
in
rotational
crops,
the
registrant
is
required
to
amend
product
labels
to
establish
a
12­
month
plantback
interval
for
leafy
vegetables.
HED
previously
recommended
the
establishment
of
a
12­
month
plantback
interval
for
root
crops
based
on
the
results
of
a
confined
rotational
crop
study
(MRID
42824001).

Except
for
the
recommendation
to
establish
a
plantback
interval
of
12
months
for
leafy
vegetables,
the
existing
rotational
crop
restrictions
appear
adequate.
HED
notes
that
the
current
labels
bear
certain
plantback
intervals
of
two
years
for
some
crops
which
apparently
is
largely
or
wholly
based
on
phytotoxicity
considerations.
HED
further
notes
that
the
established
plantback
intervals
are
dependent
on
application
rates
which
are
about
0.5x
or
less
the
maximum
seasonal
rate
for
alfalfa.

Because
the
data
from
the
limited
field
trials
indicate
that
quantifiable
residues
occur
in
field
corn
stover
and
wheat
straw,
extended
field
rotational
crop
trials
for
corn
stover,
sorghum
stover,
and
wheat
straw
to
support
a
12­
month
rotational
interval
and
a
tolerance
for
inadvertent
hexazinone
residues
are
required.
5
(continued;
footnotes
follow)

Table
A2.
Food/
Feed
Use
Patterns
Subject
To
Reregistration
for
Hexazinone
(PC
Code
107201).

Site
Application
Type
Application
Timing
Application
Equipment
Formulation
[EPA
Reg.
No.]
Max.
Single
Application
Rate
(lb
ai/
A)
Max.
#

Apps./
Season
Maximum
Seasonal
Rate
(lb
ai/
A)
Preharvest
or
Pregrazing
Interval
(Days)
Use
Directions
and
Limitations
1
Alfalfa
(grown
for
hay)

Broadcast
application
Dormant,
non­
dormant,
and
semi­
dormant
Ground
or
aerial
90%
SC
[352­
378]
1.35
0.675
(for
alfalfa
less
than
one
year
old)
1
1.
35/
year
30
Use
prohibited
in
ND
and
SD.

Broadcast
application
Dormant,
non­
dormant,
and
semi­
dormant
Ground
or
aerial
2
lb/
gal
EC
[352­
392]
75%
DF
[352­
581]
1.5
For
the
EC
formulation
only:
0.75
(for
alfalfa
<1
year
old)
1
1.
5/
year
30
(75%
DF
only)

Alfalfa
(grown
for
seed)

Broadcast
application
Dormant,
non­
dormant,
and
semi­
dormant
Ground
or
aerial
90%
SC
[352­
378]

2
lb/
gal
EC
[352­
392]
75%
DF
[352­
581]
0.5
1
0.5
Not
specified
(NS)
Use
limited
to
CA.
A
maximum
rate
of
0.5
lb
ai/
A
is
specified
for
fields
with
sandy
loam
or
loamy
sand
soils
having
1­
2%
OM
and
on
seed
alfalfa
that
has
been
established
for
only
one
growing
season.
Table
A2.
(continued).
Site
Application
Type
Application
Timing
Application
Equipment
Formulation
[EPA
Reg.
No.]
Max.
Single
Application
Rate
(lb
ai/
A)
Max.
#

Apps./
Season
Maximum
Seasonal
Rate
(lb
ai/
A)
Preharvest
or
Pregrazing
Interval
(Days)
Use
Directions
and
Limitations
1
6
(continued;
footnotes
follow)

Alfalfa
(grown
for
forage)

Broadcast
application
Dormant
Ground
2
lb/
gal
EC
[MT940001]
[WY920001]
75%
DF
[ND970002]
[SD970001]
1.0
1
1.0
30
(75%
DF)
Use
limited
to
MT,
ND,
SD,
and
WY
for
established
stands
of
forage
alfalfa.

Application
to
soils
with
<1.5%
OM
is
prohibited
for
the
EC
formulation.

Blueberry
2
Broadcast
application
Spring
of
fruiting
year
(prior
to
budbreak)
Ground
2
lb/
gal
EC
[ME980002]
75%
DF
[ME980003]
2.0
NS
2.
0
450
Use
limited
to
ME
for
established
lowbush
blueberries.
Do
not
exceed
2.0
or
1.8
lb
ai/
A
if
soil
has
been
respectively
treated
with
the
EC
or
DF
formulations
of
hexazinone
within
the
past
8
years.

Broadcast
application
Dormant
(prior
to
budbreak)

Ground
2
lb/
gal
EC
[NC830012]
2.0
NS
NS
50
Use
limited
to
NC.
Application
may
be
made
in
sufficient
water
to
provide
thorough
and
uniform
coverage,
usually
20
gal/
A.
Table
A2.
(continued).
Site
Application
Type
Application
Timing
Application
Equipment
Formulation
[EPA
Reg.
No.]
Max.
Single
Application
Rate
(lb
ai/
A)
Max.
#

Apps./
Season
Maximum
Seasonal
Rate
(lb
ai/
A)
Preharvest
or
Pregrazing
Interval
(Days)
Use
Directions
and
Limitations
1
7
(continued;
footnotes
follow)

Pineapple
Broadcast
or
directed
spray
application
Ground
or
aerial
90%
SC
[352­
378]

2
lb/
gal
EC
[352­
392]
75%
DF
[352­
581]
1.8
NS
3.
6/
crop
cycle
181
Broadcast
applications
may
be
made
between
successive
pineapple
crops,

preplant
after
rows
have
been
mulched,
and
postplant
prior
to
active
growth.
Three
to
ten
months
after
planting,
directed
spray
applications
may
be
made
to
the
soil
between
crop
rows.
Broadcast
applications
may
be
made
in
100­
400
gallons
of
water/
A
using
ground
equipment,
or
in
at
least
10
gal/
A
using
aerial
equipment.
Directed
sprays
may
be
applied
at
50­
200
gal/
A
using
ground
equipment.
Directed
spot
treatments
are
also
permitted
at
0.9­
1.8
lb
ai/
100
gal
prior
to
floral
induction.
Table
A2.
(continued).
Site
Application
Type
Application
Timing
Application
Equipment
Formulation
[EPA
Reg.
No.]
Max.
Single
Application
Rate
(lb
ai/
A)
Max.
#

Apps./
Season
Maximum
Seasonal
Rate
(lb
ai/
A)
Preharvest
or
Pregrazing
Interval
(Days)
Use
Directions
and
Limitations
1
8
(continued;
footnotes
follow)

Pasture
Broadcast
application
Ground
90%
SC
[352­
378]

2
lb/
gal
EC
[352­
392]
75%
DF
[352­
581]
1.125
1
1.
125
(implied)
60
Use
limited
to
Bermuda
grass/
Bahia
grass
pastures.
Applications
may
be
made
in
a
minimum
of
25
gal/
A
using
ground
equipment.

Basal
soil
application
(undiluted)
Ground
2
lb/
gal
EC
[352­
392]
2­
4
mL
of
product
for
each
inch
of
stem
diameter
NS
0.67/
year
NS
Use
limited
to
brush
control
in
pastures
and
rangelands.
No
restrictions
on
grazing
by
domestic
animals
nor
on
cutting
surrounding
vegetation
for
forage
and
hay
when
product
is
applied
as
a
basal
soil
treatment.

Basal
soil
application
Ground
75%
DF
[352­
581]
2
lb/
1
gal
[2­
4
mL
of
suspension
for
each
inch
of
stem
diameter]
NS
0.67/
year
NS
Table
A2.
(continued).
Site
Application
Type
Application
Timing
Application
Equipment
Formulation
[EPA
Reg.
No.]
Max.
Single
Application
Rate
(lb
ai/
A)
Max.
#

Apps./
Season
Maximum
Seasonal
Rate
(lb
ai/
A)
Preharvest
or
Pregrazing
Interval
(Days)
Use
Directions
and
Limitations
1
9
(continued;
footnotes
follow)

Rangeland
Basal
soil
application
(undiluted)
Ground
2
lb/
gal
EC
[352­
392]
2­
4
mL
of
product
for
each
inch
of
stem
diameter
NS
0.67/
year
NS
Use
limited
to
brush
control
in
pastures
and
rangelands.
No
restrictions
on
grazing
by
domestic
animals
nor
on
cutting
surrounding
vegetation
for
forage
and
hay
when
product
is
applied
as
a
basal
soil
treatment.

Basal
soil
application
Ground
75%
DF
[352­
581]
2
lb/
1
gal
[2­
4
mL
of
suspension
for
each
inch
of
stem
diameter]
NS
0.67/
year
NS
Sugarcane
Broadcast
application
Preemergence
and
postemergence
Ground
or
aerial
90%
SC
[352­
378]

2
lb/
gal
EC
[352­
392]
75%
DF
[352­
581]
3.6
1
3.6/
crop
cycle
(18­
24
months)
180
Use
limited
to
HI.
Application
may
be
made
with
a
nonionic
surfactant
at
0.25%

v/
v.
Table
A2.
(continued).
Site
Application
Type
Application
Timing
Application
Equipment
Formulation
[EPA
Reg.
No.]
Max.
Single
Application
Rate
(lb
ai/
A)
Max.
#

Apps./
Season
Maximum
Seasonal
Rate
(lb
ai/
A)
Preharvest
or
Pregrazing
Interval
(Days)
Use
Directions
and
Limitations
1
10
(continued;
footnotes
follow)

Sugarcane
(continued)
Broadcast
application
Preemergence
(in
fall)
and
postemergence
(in
spring
before
active
cane
tillering
begins)
Ground
or
aerial
90%
SC
[352­
378]

2
lb/
gal
EC
[352­
392]
75%
DF
[352­
581]
0.9
NS
0.
45/
year
for
the
90%
SC
1.5/
year
for
the
2
lb/
gal
EC
and
75%
DF
234
Use
limited
to
LA.

Broadcast
application
Preemergence
and
postemergence
Ground
or
aerial
90%
SC
[352­
378]

2
lb/
gal
EC
[352­
392]
75%
DF
[352­
581]
0.45­
0.5
NS
0.
9/
crop
cycle
288
Use
limited
to
PR.

Preemergence,
early
postemergence,
and/
or
directed
layby
Ground
or
aerial
90%
SC
[352­
378]

2
lb/
gal
EC
[352­
392]
75%
DF
[352­
581]
0.9
NS
1.
8/
crop
cycle
234
Use
limited
to
TX.
Two
treatments
are
allowed
(one
early
treatment
plus
one
directed
treatment
at
layby),
provided
60
days
have
elapsed
and
at
least
3"
of
rainfall
have
occurred.
Table
A2.
(continued).
Site
Application
Type
Application
Timing
Application
Equipment
Formulation
[EPA
Reg.
No.]
Max.
Single
Application
Rate
(lb
ai/
A)
Max.
#

Apps./
Season
Maximum
Seasonal
Rate
(lb
ai/
A)
Preharvest
or
Pregrazing
Interval
(Days)
Use
Directions
and
Limitations
1
11
Sugarcane
(continued)
Preemergence,
early
postemergence,
or
directed
layby
Ground
or
aerial
90%
SC
[TX940008]
0.45
1
0.
45
NS
Tank
mix
use
with
diuron
(Karmex
DF
Herbicide)
limited
to
TX.
Application
may
be
made
in
a
minimum
of
5
gal/
A
by
air
or
in
a
minimum
of
25
gal/
A
using
ground
equipment.
The
feeding
of
sugarcane
forage
to
livestock
is
prohibited.
Use
on
gravelly
or
rocky
soils,
thinly­
covered
subsoils,
coarse­
textured
soils
with
<2%

OM,
or
on
any
soil
with
<1%
OM
is
prohibited.
The
planting
of
any
crop
other
than
sugarcane
within
18
months
of
the
last
application
is
prohibited.

1
The
restricted
entry
interval
(REI)
for
the
90%
SC
(EPA
Reg.
No.
352­
378),
2
lb/
gal
EC
(EPA
Reg.
No.
352­
378),
and
75%
DF
(EPA
Reg.
No.

352­
581)
formulations
is
24
hours.

2
A
REFS
search,
conducted
7/
26/
01,
listed
blueberries
as
a
use
site
for
the
Federal
labels
of
the
2
lb/
gal
EC
(EPA
Reg.
No.
352­
392)
and
the
90%

SC
(EPA
Reg.
No.
352­
378).
However,
upon
label
examination
of
these
products,
it
was
determined
that
there
are
no
Section
3
registrations
of
hexazinone
on
blueberries;
only
Section
24(
c)
registrations
exist.
12
GLN
860.1300:
Nature
of
the
Residue
­
Plants
The
qualitative
nature
of
the
residue
in
plants
is
adequately
understood.
The
10/
8/
93
Residue
Chemistry
Chapter
reported
that
acceptable
metabolism
studies
had
been
conducted
on
alfalfa,
pineapple,
and
sugarcane.
These
studies
indicate
that
root
uptake
is
the
principal
mechanism
for
the
absorption
of
hexazinone
by
plants
from
soils.
Hexazinone
is
translocated
through
the
xylem
to
the
foliage
where
it
blocks
the
photosynthetic
process.
Hexazinone
is
metabolized
by
hydroxylation
to
metabolite
A
which
is
then
metabolized
to
metabolite
C
by
demethylation
and
to
metabolite
E
after
oxidation.

The
available
plant
metabolism
data
for
hexazinone
were
presented
to
the
HED
Metabolism
Assessment
Review
Committee
(MARC)
in
a
meeting
held
January
29,
2002
for
a
determination
of
hexazinone
residues
to
be
regulated
(DP
Barcode
D279897,
02/
05/
2002,
S.
Kinard).
The
Committee
concluded
that
the
hexazinone
tolerance
expression
for
plants
and
rotational
crops
should
include
hexazinone
and
metabolites
A,
B,
C,
D,
and
E.
Toxicity
data
for
the
metabolites
are
not
available
but
based
on
the
structural
similarity
of
the
metabolites
it
is
assumed
they
will
exhibit
similar
toxicity
to
the
parent
hexazinone.
The
current
tolerance
expression
for
hexazinone
in
40
CFR
§180.396
is
for
"combined
residues
of
the
herbicide
hexazinone
(3­
cyclohexyl­
6­
(dimethylamino)­
1­
methyl­
1,3,5­
triazine­
2,4(
1H,
3H)­
dione)
and
its
metabolites,
calculated
as
hexazinone."
Hexazinone
metabolites
which
are
currently
regulated
(because
they
are
measured
by
the
enforcement
analytical
method)
include
the
parent
and
metabolites
A,
B,
C,
D,
and
E.
The
hexazinone
enforcement
method
involves
extraction
and
several
cleanup
steps,
followed
by
analysis
by
GLC
with
nitrogen
phosphorus
detection.
Hexazinone
and
each
of
the
five
metabolites
are
quantitated
as
individual
peaks.
The
chemical
names
and
structures
of
the
hexazinone
residues
of
concern
in
plants
and
livestock
are
presented
in
Figure
1.

Brief
summaries
of
the
available
plant
metabolism
data,
initially
reported
in
the
Hexazinone
Registration
Standard
dated
2/
82
and
then
in
the
Hexazinone
FRSTR
Residue
Chemistry
Chapter
dated
5/
25/
88,
are
presented
below.

Alfalfa
(MRID
00104846)

In
a
study
conducted
at
the
University
of
Kentucky
Research
Farm,
a
12
ft
2
area
of
alfalfa
was
isolated
and
fenced
for
this
study.
In
mid­
March,
the
test
plot
was
sprayed
using
a
hand­
held
sprayer,
with
125
mg
of
[
14
C]
hexazinone
dissolved
in
water;
the
application
rate
was
equivalent
to
1.0
lb
ai/
100
gal/
A.
Alfalfa
samples
were
collected
at
two,
three,
and
six
months
after
treatment.
Total
radioactive
residues
(TRR),
calculated
as
hexazinone,
declined
at
each
sampling
interval,
and
respectively
were
0.6,
0.5,
and
0.1
ppm.
The
extractable
percentages
of
TRR
were
95,
84,
and
80%
for
the
two­,
three
and
six­
month
harvests,
respectively.
Analysis
of
the
two­
month
alfalfa
cutting
identified
hexazinone
(2.7%
TRR),
free
metabolite
A
(7.1%
TRR),
free
metabolite
B
13
N
N
N
O
O
CH
3
N
CH
3
CH
3
(0.7%
TRR),
and
conjugated
metabolites
A,
B,
and
C
(4.5%
TRR).
The
remaining
radioactive
residues
were
found
in
water­
soluble,
polar
materials
which
were
subsequently
found
to
be
comprised
of
amino
acids,
sugars,
polybasic
acids,
and
smaller
amounts
of
natural
products.

Pineapple
(MRID
00126127)

A
pineapple
metabolism
study
was
submitted
by
the
basic
registrant
in
conjunction
with
PP#
3F2846.
The
Hexazinone
FRSTR
Residue
Chemistry
Chapter
dated
5/
25/
88
reported
the
salient
features
of
this
study
with
respect
to
residue
characterization/
identification
only.
The
fruit
(pulp
and
rind)
were
extracted
with
methanol,
and
94­
99%
of
TRR
was
extractable.
The
following
components
were
identified
in
the
pulp:
hexazinone
(0.8­
1.8%
TRR),
metabolite
A
(23­
28%
TRR),
metabolite
C
(13­
15%
TRR),
metabolite
D
(16­
21%
TRR),
and
metabolite
F
(1­
2%
TRR).

Sugarcane
(MRID
00078047)

Greenhouse­
grown
dwarf
sugarcane
were
grown
in
large
tubs
(2
canes/
tub)
and
when
the
canes
reached
5.5
to
6.0
feet
in
height,
they
were
treated
with
a
soil
drench
application
of
[
14
C]
hexazinone
at
rates
of
0.54
and
1.0
kg/
ha
(0.48
and
0.89
lb
ai/
A);
a
third
tub
was
maintained
as
a
control.
About
six
months
after
treatment,
sugarcane
samples
were
collected.
The
TRRs,
calculated
as
hexazinone,
were
0.07­
0.08
and
0.05
ppm
in
sugarcane
treated
at
0.89
and
0.48
lb
ai/
A,
respectively.
Following
organic
solvent
extraction,
76%
of
TRR
was
recovered.
The
following
components
were
identified
by
GC/
MS
in
sugarcane:
metabolite
E
(30%
TRR),
metabolite
C
(23%
TRR),
metabolite
A
(14%
TRR),
metabolite
B
(1%
TRR),
metabolite
D
(3%
TRR),
and
hexazinone
(<
1%
TRR).

Figure
1.
Chemical
Structures
of
Hexazinone
and
its
Regulated
Metabolites
(Metabolites
A
through
F).

Common
Name/
Code
Chemical
name
Structure
Hexazinone
3­
cyclohexyl­
6­(
dimethylamino)­
1­
methyl­
1,3,5­
triazine­
2,4(
1H,
3H)­
dione
Figure
A
(continued).

Common
Name/
Code
Chemical
name
Structure
14
(continued
next
page)
N
N
N
O
O
CH
3
N
CH
3
CH
3
HO
N
N
N
O
O
CH
3
N
H
CH
3
N
N
N
O
O
CH
3
N
H
CH
3
HO
N
N
NH
O
O
CH
3
O
Metabolite
A
3­(
4­
hydroxycyclohexyl)­
6­
(dimethylamino)­
1­
methyl­
1,3,5­
triazine
2,4­(
1H,
3H)­
dione
Metabolite
A­
1
is
hydroxylated
at
the
2­
position
of
the
cyclohexyl
ring;
Metabolite
A­
2
is
hydroxylated
at
the
3­
position
of
the
cyclohexyl
ring.

Metabolite
B
3­
cyclohexyl­
6­(
methylamino)­
1­
methyl
1,3,5­
triazine­
2,4­(
1H,
3H)­
dione
Metabolite
C
3­(
4­
hydroxycyclohexyl)­
6­
methylamino
1­
methyl­
1,3,5­
triazine­
2,4­(
1H,
3H
dione
Metabolite
C­
1
is
hydroxylated
at
the
2­
position
of
the
cyclohexyl
ring;
Metabolite
C­
2
is
hydroxylated
at
the
3­
position
of
the
cyclohexyl
ring.

Metabolite
D
3­
cyclohexyl­
1­
methyl­
1,3,5­
2,4,6
1H,
3H,
5H)­
trione
Figure
A
(continued).

Common
Name/
Code
Chemical
name
Structure
15
N
N
NH
O
O
CH
3
O
HO
N
N
N
O
O
CH
3
NH
2
Metabolite
E
3­(
4­
hydroxycyclohexyl)­
1­
methyl
1,3,5­
triazine­
2,4,6­(
1H,
3H,
5H)­
trione
Metabolite
F
3­
cyclohexyl­
6­
amino­
1­
methyl
1,3,5­
triazine­
2,4­(
1H,
3H)­
dione
16
GLN
860.1300:
Nature
of
the
Residue
­
Livestock
The
qualitative
nature
of
the
residue
in
livestock
is
adequately
understood
based
on
acceptable
ruminant
and
poultry
metabolism
studies.
The
requirement
to
confirm
the
identities
of
metabolites
in
goat
tissues
and
milk
by
a
second
method,
specified
in
the
10/
8/
93
Residue
Chemistry
Chapter,
has
been
fulfilled.
The
requirement
to
radiovalidate
the
proposed
enforcement
method
using
samples
collected
from
the
ruminant
metabolism
study
has
also
been
fulfilled.
No
additional
livestock
metabolism
data
are
required
for
reregistration.

The
available
livestock
metabolism
data
were
presented
to
the
HED
MARC
in
a
meeting
held
January
29,
2002
for
a
determination
of
hexazinone
residues
to
be
regulated
(D279897,
02/
05/
2002,
S.
Kinard).
The
Committee
concluded
that
the
hexazinone
tolerance
expression
for
ruminants
should
include
hexazinone
plus
metabolites
B,
C,
C­
2,
and
F
for
milk.
The
Committee
concluded
that
the
hexazinone
tolerance
expression
for
ruminant
tissue
should
include
hexazinone
plus
metabolites
B
and
F.
The
Committee
concluded
that
residues
of
hexazinone
and
metabolites
B,
C,
C1
C­
2,
and
F
should
be
taken
into
account
when
risk
assessments
are
done.
The
above
determination
was
partially
based
on
the
assumption
that
the
current
enforcement
method
listed
in
the
PAM,
Volume
II
for
plant
commodities
could
be
used
for
livestock
commodities
provided
additional
method
validation
data
are
submitted;
there
is
presently
no
enforcement
method
listed
in
PAM
Volume
II
for
livestock
commodities.

HED
has
determined
that
tolerances
for
hexazinone
residues
in
eggs
and
poultry
tissues
are
not
required
(Category
3,
40
CFR
§180.6a)
based
on
the
results
of
the
reviewed
poultry
metabolism
study.
In
the
poultry
study,
the
liver
contained
the
highest
TRR,
0.19
ppm.
Considering
that
the
feeding
level
was
about
38x
the
maximum
theoretical
dietary
burden,
the
maximum
residue
in
poultry
tissue
would
be
0.005
ppm,
an
order
of
magnitude
below
the
limit
of
detection
for
hexazinone
metabolites.

Brief
summaries
of
available
goat
and
hen
metabolism
studies
are
presented
below.

Goat
(MRIDs
42187901,
43074201,
and
43488901)

A
lactating
goat
was
dosed
orally
with
[
14
C]
hexazinone
radiolabeled
in
the
triazine
ring
at
a
dose
rate
of
136.4
mg/
day,
equivalent
to
2.2
mg/
kg
body
weight
for
five
consecutive
days.
This
dose
represents
a
level
of
approximately
90
ppm
in
the
feed,
which
is
19.4x
the
maximum
theoretical
dietary
burden
for
ruminants.
TRRs,
expressed
as
hexazinone
equivalents,
were
6.74
ppm
in
milk,
3.03
ppm
in
liver,
2.54
ppm
in
kidney,
0.27
ppm
in
muscle,
and
0.03
ppm
in
fat.
Residues
were
adequately
extracted
with
organic
solvents.
A
list
of
characterized/
identified
residues
in
goat
matrices
is
presented
below.
17
Table
1.
Characterization/
identification
of
residues
from
goat
milk
and
tissues
dosed
with
90
ppm
of
[
14
C]
hexazinone
for
5
consecutive
days.
(Reproduced
from
DP
Barcode
D198348,
5/
25/
94,
S.
Hummel).

Metabolite
Liver
TRR
=
3.03
ppm
Kidney
TRR
=
2.54
ppm
Muscle
TRR
=
0.27
ppm
Milk
TRR
=
6.74
ppm
%TRR
PPM
%TRR
PPM
%TRR
PPM
%TRR
PPM
Hexazinone
0.1
0.
04
­­
<0.01
­­
<0.01
1.
2
0.08
B
56.7
1.
70
28.3
0.
72
40.7
0.
11
48.1
3.
24
A­
2
­­
<0.01
0.4
0.
01
­­
<0.01
0.4
0.
03
A,
A­
1
0.
1
0.04
2.0
0.
05
­­
<0.01
3.9
0.
26
C
­­
<0.01
3.1
0.
08
­­
<0.01
3.4
0.
23
C­
1,
C­
2
11.9
0.
36
18.5
0.
47
7.
4
0.02
16.6
1.
12
E
­­
<0.01
1.2
0.
03
­­
<0.01
­­
<0.01
F
11.6
0.
35
37.4
0.
95
25.9
0.
07
17.1
1.
15
Others*
5.
8
0.19
5.1
0.
13
14.8
0.
04
4.
0
0.27
Total
Identified
86.2
2.
68
96.0
2.
44
88.9
0.
24
94.7
6.
38
Unknown
­­
<0.01
­­
<0.01
­­
<0.01
5.2
0.
35
Unextracted
11.9
0.
36
4.
7
0.12
11.1
0.03
0.1
0.
01
Total
98.1
3.
03
101
2.56
100
0.27
100
6.74
*Others
identified
at
<0.01
ppm
each
Poultry
(MRIDs
41524801,
42690601,
43074201)

Five
ISA
Brown
laying
hens
were
dosed
orally
at
6.9
mg/
day
with
carbonyl­
labeled
[
14
C]
hexazinone
for
six
consecutive
days.
The
daily
dose
rate
was
equivalent
to
57
ppm
in
the
feed,
which
is
38x
the
maximum
theoretical
dietary
burden.
Mean
TRR
levels,
expressed
as
hexazinone
equivalents,
were
0.189
ppm
in
liver,
0.02
ppm
in
fat,
0.078
and
0.106
ppm
in
thigh
and
breast
muscle,
respectively,
and
0.059
ppm
in
skin.
TRR
level
in
eggs
(day
6)
was
0.12
ppm.
Residues
were
adequately
extracted
with
organic
solvents.
No
single
metabolite
in
edible
poultry
tissue
was
greater
than
0.04
ppm,
and
unidentified
metabolites
represented
less
than
0.05
ppm
in
all
edible
tissues.
A
list
of
characterized
and
identified
residues
in
poultry
muscle
and
eggs
is
presented
below.
18
Table
2.
Characterization/
identification
of
residues
from
hen
eggs
and
muscle
tissues
dosed
with
57
ppm
of
[
14
C]
hexazinone
for
six
consecutive
days.
(DP
Barcode
D198348,
5/
25/
94,
S.
Hummel).

Metabolite
Muscle
TRR
=
0.12
ppm
Eggs
TRR
=
0.13
ppm
%TRR
PPM
%TRR
PPM
Hexazinone
–
<0.01
­­
<0.01
A,
A­
1,
A­
2
16.7
0.
02
23.1
0.
03
C
16.7
0.02
23.1
0.
03
A­
OH,
C­
OH
16.7
0.
02
7.
7
0.01
E
­­
<0.01
­­
<0.01
Others*
33.3
0.
04
15.4
0.
02
Total
Identified
83.5
0.
10
69.3
0.
09
Unknown
16.7
0.
02
23.1
0.
03
Unextracted
8.4
0.01
7.7
0.
01
Total
109
0.13
100
0.13
*Others
identified
at
<0.01
ppm.

GLN
860.1340:
Residue
Analytical
Methods
Plant
Commodities
The
10/
8/
93
Residue
Chapter
concluded
that
adequate
methods
are
available
for
purposes
of
data
collection
and
enforcement
of
tolerances
for
residues
of
hexazinone
and
metabolites
A,
B,
C,
D,
and
E
in/
on
plant
commodities.
No
additional
data
on
residue
analytical
methods
for
plant
commodities
are
required
for
reregistration.

For
tolerance
enforcement,
the
PAM,
Volume
II
lists
Method
I
as
available
for
the
determination
of
hexazinone
residues
of
concern
in/
on
plant
commodities.
Using
this
method,
residues
of
hexazinone
and
metabolites
A,
B,
D,
and
E
are
extracted
with
chloroform
and
cleaned
up
by
liquid­
liquid
partitioning.
Residues
of
Metabolite
C,
a
highly
polar
metabolite,
are
extracted
from
samples
with
methanol
in
a
separate
isolation
scheme.
Both
schemes
use
derivatization
of
residues
with
trifluoroacetic
anhydride
and
determination
of
the
derivatives
by
nitrogen­
selective
GLC.
Some
samples
(e.
g.,
alfalfa
and
grasses)
require
additional
cleanup
on
a
gel
permeation
column,
before
derivatization,
or
on
a
deactivated
Florisil
column,
either
before
or
after
derivatization.
The
combined
limit
of
quantitation
(LOQ)
for
hexazinone
residues
by
Method
I
in
PAM,
Volume
II,
is
0.55
ppm.

For
data
collection,
the
registrant
utilized
Method
Nos.
92013­
V2
and
92013­
V3
during
analyses
of
samples
collected
from
field
trials
on
alfalfa.
These
methods
are
similar
to
the
PAM,
Volume
II
method
but
were
modified
to
include
additional
clean
up
steps.
They
have
been
deemed
adequate
for
data
collection
based
on
acceptable
method
19
validation
and
concurrent
recovery
data.

Livestock
Commodities
The
10/
8/
93
Residue
Chapter
required
data
collection
and
tolerance
enforcement
methodology
for
determination
of
hexazinone
residues
of
concern
in
livestock
commodities.
In
an
attempt
to
fulfill
this
requirement,
the
registrant
requested
a
meeting
with
HED
to
report
progress
of
their
work
in
developing
a
new
method
prior
to
submitting
it
for
an
independent
laboratory
validation
(ILV).
In
a
meeting
held
8/
31/
94,
the
registrant
advised
that
the
current
method
in
PAM,
Volume
II
for
plant
commodities
did
not
appear
appropriate
for
livestock
commodities
because
of
complications
with
matrix
effects
and
the
inability
to
detect
metabolite
F,
among
other
problems.

The
registrant
instead
proposed
an
LC/
MS
method
(designated
as
du
Pont
AMR
3783­
96)
as
an
enforcement
method.
The
proposed
method
would
determine
residues
of
parent
hexazinone,
metabolite
B,
metabolite
C
and
its
isomer
(C­
2),
and
metabolite
F
in
milk.
In
livestock
tissues,
Method
AMR
3783­
96
would
determine
residues
of
parent
hexazinone,
metabolite
B,
and
metabolite
F.
Briefly,
residues
in
milk
and
animal
tissues
are
extracted
three
times
with
acetone:
aqueous
0.1
M
potassium
phosphate/
0.5
M
sodium
chloride
solution
(1:
1,
v:
v).
The
extract
is
concentrated
to
remove
the
acetone,
and
purified
using
solid
phase
extraction
(SPE)
cartridges.
A
combination
of
reverse­
(C8)
and
normal­
(silica)
phase
SPE
sorbents
is
used
to
remove
most
substances
that
may
interfere
with
the
instrument
analysis.
Residues
of
hexazinone
and
metabolites
B
and
F
are
quantitated
in
tissue
samples
and
residues
of
hexazinone
and
metabolites
B,
C,
C­
2,
and
F
are
quantitated
in
milk
using
LC/
MS
with
an
electrospray
interface
and
selected
ion
monitoring
(SIM).
The
reported
LOQs
were
0.02
ppm
for
hexazinone
and
metabolite
B
and
0.05
ppm
for
metabolites
C,
C­
2,
and
F.

The
proposal
to
develop
DuPont
Method
AMR
3783­
96
as
an
enforcement
method
was
based
on
a
cattle
feeding
study
which
had
been
reviewed
by
HED
and
deemed
acceptable.
Data
from
the
cattle
feeding
study
indicate
that
in
milk,
the
metabolites
determined
by
the
proposed
method
represent
nearly
95%
of
total
hexazinone
residues.
In
tissues,
parent
and
metabolite
B
represent
at
least
85%
of
total
residues
in
liver
and
63%
of
total
residues
in
kidney;
metabolite
B
is
the
only
residue
detected
in
muscle,
even
at
the
10x
feeding
level;
and
all
residues
are
nondetectable
in
fat
at
the
10x
level.

DuPont
Method
AMR
3783­
96
has
been
subjected
to
a
successful
ILV
and
a
radiovalidation
study.
The
ILV
data
did
support
the
reliability
of
and
reproducibility
of
the
method
for
the
determination
of
residues
of
hexazinone,
metabolite
B,
metabolite
C
and
its
isomer
(C­
2),
and
metabolite
F
in
milk;
the
ILV
data
also
showed
that
Method
AMR
3783­
96
can
adequately
recover
residues
of
hexazinone,
metabolite
B,
and
metabolite
F
in
livestock
tissues.
Method
AMR
3783­
96
will
be
forwarded
to
the
Analytical
Chemistry
Branch
(ACL;
Beltsville,
MD)
for
a
tolerance
method
validation
20
by
Agency
chemists.
If
the
results
of
method
validation
by
Agency
chemists
are
successful,
then
Method
AMR
3783­
96
will
be
proposed
for
inclusion
in
PAM,
Volume
II,
and
no
additional
data
concerning
this
GLN
topic
will
be
required
for
reregistration.

GLN
860.1360:
Multiresidue
Methods
The
reregistration
requirements
for
multiresidue
methods
data
are
fulfilled.
The
10/
99
FDA
PESTDATA
database
(PAM,
Volume
I,
Appendix
I)
indicates
that
hexazinone
is
only
partially
recovered
(50­
80%)
using
Multiresidue
Method
Sections
302
(Luke
Method;
Protocol
D)
and
is
not
recovered
using
Sections
303
(Mills,
Onley,
Gaither;
Protocol
E
­
nonfatty
foods)
and
304
(Mills;
Protocol
E
­
fatty
foods).

There
is
a
small
recovery
(<
50%)
of
metabolite
A
(IN­
T3937)
and
metabolite
C
INT3935
using
Multiresidue
Method
Section
302
(Luke
Method;
Protocol
D).
There
is
also
a
small
recovery
(<
50%)
of
metabolite
B
(IN­
T3928)
and
metabolite
E
(IN­
T3936)
using
Multiresidue
Method
Section
302
(Luke
Method;
Protocol
D)
but
the
metabolites
are
not
recovered
using
Sections
303
(Mills,
Onley,
Gaither;
Protocol
E
­
nonfatty
foods)
and
304
(Mills;
Protocol
E
­
fatty
foods).
Metabolite
D
(IN­
B2838)
is
partially
recovered
(50­
80%)
using
Multiresidue
Method
Sections
302
(Luke
Method;
Protocol
D)
and
is
not
recovered
using
Sections
303
(Mills,
Onley,
Gaither;
Protocol
E
­
nonfatty
foods)
and
304
(Mills;
Protocol
E
­
fatty
foods).

GLN
860.1380:
Storage
Stability
Data
Plant
Commodities
The
Updated
Table
A
for
Residue
Chemistry
RED
Chapter
dated
9/
8/
94
required
additional
storage
stability
data
for:
(1)
hexazinone
and
metabolites
in
alfalfa,
and
(2)
metabolite
C
in
grass.
The
registrant
has
submitted
the
requested
data
which
were
deemed
adequate
to
support
the
storage
conditions
and
intervals
of
samples
used
for
tolerance
reassessment.
No
additional
storage
stability
data
for
plant
and
processed
commodities
are
required
for
reregistration.
A
summary
of
the
available
storage
stability
data
is
presented
below.

Residues
of
hexazinone
and
its
metabolites
A,
B,
C,
D,
and
E
are
relatively
stable
under
frozen
(­
20
to
­10
°C)
storage
conditions
in/
on
blueberries
for
up
to
13
months,
in/
on
pineapple
for
up
to
8
months,
in
pineapple
juice
for
up
to
6
months,
in/
on
sugarcane
for
up
to
12
months,
and
in
sugarcane
processed
commodities
for
up
to
6
months.
Hexazinone
and
metabolites
A,
B,
D,
and
E
are
also
stable
in
grass
samples
during
frozen
(­
20
°C)
storage
for
up
to
24
months,
and
metabolite
C
is
stable
in
grass
samples
during
frozen
(­
20
±
10
°C)
storage
for
up
to
36
months.

Livestock
Commodities
21
Adequate
storage
stability
data
are
available
to
support
the
existing
ruminant
feeding
study.
Samples
of
milk,
liver,
kidney,
muscle,
and
fat
samples
were
stored
under
freezer
storage
conditions
for
maximums
of
8,
10,
14,
2,
and
2
months,
respectively,
prior
to
residue
analysis.
In
a
fortification
study,
hexazinone
residues
of
concern
were
found
to
be
stable
during
maximum
storage
times
for
samples
collected
and
analyzed
from
the
feeding
study.

GLN
860.1500:
Crop
Field
Trials
Pending
label
revisions
for
certain
crops,
the
reregistration
requirements
for
data
depicting
magnitude
of
the
residue
in/
on
the
following
raw
agricultural
commodities
(RACs)
are
satisfied:
alfalfa
forage,
alfalfa
hay,
alfalfa
seed,
blueberries,
pineapple,
and
sugarcane.
An
adequate
number
of
field
trials
have
been
conducted
for
these
RACs,
and
the
trials
were
conducted
using
registered
hexazinone
formulation(
s)
at
the
maximum
registered
rate.

Brief
summaries
of
available
hexazinone
residue
data,
deemed
useful
for
tolerance
reassessment,
are
presented
below.
It
is
noted
that
product
labels
of
registrants
other
than
du
Pont
were
not
examined
in
the
preparation
of
this
document.

Berries
Group
Blueberry
The
10/
8/
93
Residue
Chapter
concluded
that
no
additional
data
are
required
for
blueberries
provided
all
pertinent
product
labels
are
amended
to
specify
PHIs
of
90
and
450
days
for
application
to
highbush
and
lowbush
blueberries,
respectively.

Data
(MRIDs
41964101
and
41964102)
reviewed
in
the
Hexazinone
Update
indicate
that
the
combined
residues
of
hexazinone
and
its
regulated
metabolites,
as
measured
by
the
data­
collection
method,
were
<0.3
ppm
(nondetectable;
<0.05
ppm
for
each
compound)
in/
on:
(1)
12
samples
of
lowbush
blueberries
harvested
433­
446
days
following
a
single
application
of
the
2
lb/
gal
EC
or
90%
SC
formulation
at
3
or
6
lb
ai/
A
(1.5
or
3.0x
the
maximum
registered
rate)
using
ground
or
aerial
equipment;
and
(2)
12
samples
of
highbush
blueberries
harvested
68­
97
days
following
a
single
application
of
the
2
lb/
gal
EC
or
90%
SC
formulation
at
2
or
4
lb
ai/
A
(0.8
or
1.3x
the
maximum
registered
rate).
Based
on
the
combined
LOQs
(0.55
ppm)
of
the
enforcement
method,
HED
is
now
recommending
that
the
RAC
tolerance
be
reassessed
from
0.2
ppm
to
0.60
ppm.

Although
uses
of
hexazinone
on
blueberries
(see
Table
A2)
are
limited
to
Section
24(
c)
registration,
label
revisions
remain
a
requirement.
The
product
labels
for
ME980002
22
and
ME980003,
which
are
limited
for
use
on
lowbush
blueberries,
should
be
amended
to
specify
a
PHI
of
450
days.
The
product
label
for
NC830012
should
also
be
amended
to
specify
PHIs
of
90
and
450
days
for
application
to
highbush
and
lowbush
blueberries,
respectively.

Grass
Forage,
Fodder,
and
Hay
Group
Grass
(pasture
and
rangeland)
forage
An
examination
of
registered
uses
of
hexazinone
on
pasture
and
rangeland
grasses
(see
Table
A2)
reveal
that
there
two
distinct
use
patterns,
a
basal
soil
application
and
a
broadcast
application.
It
is
noted
that
the
10­
ppm
tolerance
for
grass
forage
(listed
as
"grasses,
pasture"
and
"grasses,
range"
under
40
CFR
§180.396)
was
established
based
on
residue
data
reflecting
basal
soil
application
only.

Data
reflecting
basal­
soil
application
were
submitted
under
PP#
1F2513
and
summarized
in
the
Hexazinone
FRSTR
Residue
Chemistry
Chapter
dated
5/
25/
88.
Samples
of
range
and
pasture
grasses
were
harvested
at
various
intervals
following
application
of
the
2
lb/
gal
EC
formulation
at
3
or
6
mL
per
one
inch
of
diameter
at
breast
height
(0.75
or
1.5x
the
maximum
registered
rate
for
directed
spray
basal
soil
application).
Samples
were
taken
2",
12",
and
24"
in
radius
from
the
treatment
point
on
days
0­
56
after
application.
The
FRSTR
Residue
Chemistry
Chapter
did
not
report
specific
residues;
however,
it
was
concluded
that
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone)
did
not
exceed
the
established
tolerances
of
10
ppm
in/
on
treated
samples
of
pasture
and
range
grass
forage.

In
the
absence
of
residue
data
reflecting
broadcast
application,
HED
is
requiring
the
following
additional
data
for
grass
forage
before
the
RAC
tolerance
can
be
reassessed:
"Data
depicting
magnitude
of
the
residues
of
hexazinone
and
metabolites
A,
B,
C,
D,
and
E
in/
on
grass
forage
harvested
0
day
following
a
single
broadcast
application
of
representative
formulations
at
1.125
lb
ai/
A.
It
is
the
Agency
policy
to
require
0­
day
crop
field
residue
data
for
grass
forage
unless
it
is
not
feasible
(e.
g.,
preplant/
preemergence
pesticide
uses).
The
formulations
to
be
tested
may
be
applied
in
side­
by­
side
plots.
The
location
and
number
of
trial
should
be
in
compliance
with
the
current
OPPTS
GLN
for
adequate
geographic
representation
of
data.

Grass
(pasture
and
rangeland)
hay
The
reregistration
requirements
for
residue
data
on
grass
hay
have
not
been
fulfilled.
The
registrant
has
submitted
a
petition
(PP#
1F3967)
for
the
establishment
of
a
tolerance
for
residues
of
hexazinone
and
its
metabolites
in/
on
grass
hay.
The
petition
is
currently
in
reject
status
because
additional
grass
hay
data,
from
field
trials
with
adequate
23
geographical
representation,
remain
outstanding.
Since
1991
HED
has
reviewed
two
proposals
to
amend
the
original
petition
requesting
that
the
Agency
establish
tolerances
for
grass
hay
based
on
theoretical
grass
drying
factors.
HED
recommended
against
the
establishment
of
grass
hay
tolerances
each
time.
In
addition,
HED
reviewed
two
registrant
responses
to
the
petition
amendment
reviews
and
concluded
in
each
case
that
the
recommendation
to
require
actual
field
trial
data
for
grass
hay
is
appropriate
(D162863,
D181318,
D172408,
D201738).

Non­
Grass
Animal
Feeds
(Forage,
Fodder,
Straw,
and
Hay)
Group
Alfalfa
forage
and
hay
The
Updated
Table
A
for
Residue
Chemistry
RED
Chapter
dated
9/
8/
94
concluded
that
adequate
residue
data
are
available
for
alfalfa
forage
and
hay.
However,
label
amendments
were
required
on
all
product
labels
for
alfalfa,
including
supplemental
labels,
to
establish
a
30­
day
PHI
for
the
feeding
of
forage
and
the
cutting
of
hay.

The
available
residue
data
(MRIDs
43074401
and
43074402)
indicate
that
the
combined
residues
of
hexazinone
and
its
metabolites
A,
B,
C,
D,
and
E
did
not
exceed
the
established
tolerances
of
2.0
ppm
in/
on
alfalfa
forage
and
8.0
ppm
in/
on
alfalfa
hay
harvested
29­
31
days
following
a
single
broadcast
dormant
or
non­
dormant
application
of
the
2
lb/
gal
EC
or
90%
SC
formulation
at
1.5
lb
ai/
A
(~
1x).
The
maximum
combined
residues
in/
on
treated
samples
were
<1.87
ppm
and
<3.33
ppm
for
alfalfa
forage
and
hay,
respectively.
Based
on
these
data,
the
established
tolerance
for
alfalfa
forage
is
reassessed
at
its
existing
level
of
2.0
ppm;
however,
the
tolerance
for
alfalfa
hay
should
be
lowered
from
8.0
ppm
to
4.0
ppm.

Table
A2
shows
that
product
labels
for
the
90%
SC
(EPA
Reg.
No.
352­
378)
and
75%
DF
(EPA
Reg.
No.
352­
58)
formulations
have
been
revised
in
compliance
with
the
requested
label
amendment.
However,
the
product
label
for
the
2
lb/
gal
EC
(EPA
Reg.
No.
352­
392)
formulation
does
not
specify
any
PHI;
this
label
must
be
amended
to
establish
a
30­
day
PHI
(or
pregrazing
interval)
for
the
feeding
of
forage
and
the
cutting
of
hay.

Alfalfa
seed
The
Updated
Table
A
for
the
Residue
Chemistry
RED
Chapter
dated
9/
8/
94
concluded
that
adequate
residue
data
have
been
submitted
for
alfalfa
seed;
the
Chapter,
however,
required
the
registrant
to
propose
a
tolerance
for
this
commodity
in
order
to
support
registered
uses
of
hexazinone
on
alfalfa
grown
for
seed.

The
available
residue
data
(MRIDs
43074401
and
43074402)
indicate
that
the
combined
residues
of
hexazinone
and
its
regulated
metabolites
ranged
from
<1.30
ppm
24
(sum
of
the
LOQs)
to
<1.46
ppm
in/
on
alfalfa
seed
following
a
single
broadcast
dormant
application
of
the
2
lb/
gal
EC
or
90%
SC
formulation
at
0.75
lb
ai/
A
(1.5x
the
maximum
registered
rate
on
alfalfa
grown
for
seed);
no
data
were
submitted
reflecting
1.0x.
HED
is
requesting
the
registrant
to
propose
a
tolerance
for
hexazinone
residues
of
concern
in/
on
alfalfa
seed;
the
available
data
suggest
that
a
tolerance
level
of
2.0
ppm
is
appropriate.

Residue
data
and
a
tolerance
proposal
for
alfalfa
seed
screenings,
previously
requested
in
the
Updated
Table
A
for
the
Residue
Chemistry
RED
Chapter
dated
9/
8/
94,
are
no
longer
required
because
this
item
has
been
deleted
from
Table
1
of
OPPTS
860.1000
as
a
significant
livestock
feed
item.

Miscellaneous
Commodities
Pineapple
The
10/
8/
93
Residue
Chapter
concluded
that
no
additional
residue
data
are
required
for
pineapple
provided
all
pertinent
product
labels
are
amended
to
specify
a
maximum
application
rate
of
3.6
lb
ai/
A/
cropping
cycle
and
a
minimum
PHI
of
181
days.
The
basic
registrant
has
complied
with
this
requirement
as
shown
in
Table
A2.

The
available
data
(MRID
42535601)
indicate
that
the
combined
residues
of
hexazinone
and
its
regulated
metabolites,
as
measured
by
the
data­
collection
method,
were
<0.35
ppm
(or
<0.05
ppm
for
each
compound)
in/
on
pineapple
fruits
harvested
at
a
minimum
PHI
of
181
days
following
five
ground
applications
of
a
representative
hexazinone
formulation
at
0.45­
0.9
lb
ai/
A
for
a
total
rate
of
3.6
lb
ai/
A.
Based
on
the
combined
LOQs
(0.55
ppm)
of
the
enforcement
method,
HED
is
now
recommending
that
the
RAC
tolerance
be
reassessed
from
0.5
ppm
to
0.60
ppm.

HED's
request
to
impose
a
feeding
restriction
on
pineapple
forage,
previously
specified
in
the
Updated
Table
A
for
the
Residue
Chemistry
RED
Chapter
dated
9/
8/
94,
is
no
longer
required
because
this
item
has
been
deleted
from
Table
1
of
OPPTS
860.1000
as
a
significant
livestock
feed
item.

Sugarcane
The
Updated
Table
A
for
Residue
Chemistry
RED
Chapter
dated
9/
8/
94
concluded
that
no
additional
residue
data
are
required
for
sugarcane
provided
all
pertinent
product
labels
are
amended
to
prohibit
use
of
hexazinone
on
sugarcane
grown
in
FL.
The
basic
registrant
has
complied
with
the
requested
label
amendment
(see
Table
A2).
Presently,
registered
uses
of
hexazinone
on
sugarcane
are
limited
to
those
grown
in
the
states
of
HI,
LA,
TX,
and
in
Puerto
Rico.
25
The
available
data
(MRID
42322701)
indicate
that
the
combined
residues
of
hexazinone
and
its
regulated
metabolites,
as
measured
by
the
data­
collection
method,
were
<0.35
(or
<0.05
ppm
for
each
compound)
in/
on
samples
of
sugarcane
treated
with
the
90%
SC
formulation
of
hexazinone
from
the
following
test
locations:
(i)
in
Puerto
Rico
where
sugarcane
was
harvested
288
days
following
a
single
postemergence
application
at
0.45
lb
ai/
A
(0.5x
the
maximum
registered
seasonal
rate
for
this
area);
(ii)
in
TX
where
sugarcane
was
harvested
234
days
following
one
preemergence
application
followed
by
one
postemergence
application
at
0.675
lb
ai/
A/
application
(0.75x
the
maximum
seasonal
rate
in
TX);
and
(iii)
in
HI
where
sugarcane
was
harvested
179­
181
days
following
a
total
of
four
applications
(one
preemergence
application
at
1.35
or
1.47
lb
ai/
A,
a
postemergence
application
at
0.45
lb
ai/
A/
application,
followed
by
two
postemergence
applications
at
1.8
lb
ai/
A/
application)
for
a
total
rate
of
5.4­
5.5
lb
ai/
A/
season
(1.5x
the
maximum
seasonal
rate
in
HI).
Based
on
the
combined
LOQs
(0.55
ppm)
of
the
enforcement
method,
HED
is
now
recommending
that
the
RAC
tolerance
be
reassessed
from
0.20
ppm
to
0.60
ppm.

GLN
860.1520:
Processed
Food/
Feed
Pineapple
process
residue
and
juice
The
registrant
has
submitted
a
pineapple
processing
study
(MRIDs
42492101
and
43401901)
which
was
first
deemed
inadequate
but
later
upgraded
as
acceptable.
Residues
of
hexazinone
and
its
regulated
metabolites
did
not
concentrate
in
pineapple
process
residue
and
juice
except
for
Metabolite
B
in
process
residue.
The
registrant
calculated
a
concentration
factor
of
3.0x
for
Metabolite
B
in
pineapple
process
residue
based
on
quantified
residues
of
0.06
ppm
in
pineapple
process
residue
and
0.02
ppm
in/
on
pineapple
RAC
after
treatment
with
hexazinone
at
a
1.0x
rate.
When
this
concentration
factor
of
3.0
x
is
multiplied
by
the
highest
average
field
trial
(HAFT)
residue
of
<0.05
ppm,
the
maximum
expected
residues
of
metabolite
B
in
pineapple
process
residue
is
0.15
ppm
which
is
less
than
the
reassessed
RAC
tolerance
of
0.60
ppm.
Therefore,
no
tolerance
for
pineapple
process
residues
is
warranted.

Sugarcane
molasses
and
refined
sugar
An
acceptable
sugarcane
processing
study
(MRIDs
42276001
and
42417901)
is
available.
The
reviewed
study
indicate
that
residues
of
the
parent
hexazinone
were
0.23
ppm
in/
on
the
RAC
(sugarcane)
following
application
of
the
90%
SC
formulation
at
a
total
rate
of
7.2
lb
ai/
A
(2.0x
the
maximum
seasonal
application
rate
for
sugarcane
grown
in
HI).
Residues
of
metabolites
A,
B,
C,
D,
and
E
were
each
nondetectable
(<
0.05
ppm)
in/
on
treated
RAC
samples.
Following
processing
of
the
RAC
according
to
simulated
commercial
practices,
residues
of
hexazinone
and/
or
metabolites
A
through
E
concentrated
in
bagasse
(1.6x)
and
"A
molasses"
(4.0x).
However,
residues
26
declined
in
raw
sugar
(reduction
factor
of
0.2x)
and
processed
sugar
(reduction
factor
of
0.2x).
The
presently
regulated
processed
commodities
of
sugarcane
are
molasses
and
refined
sugar;
bagasse
has
been
removed
from
Table
1
of
OPPTS
860.1000.

Samples
of
treated
"A
molasses"
from
the
above
study
were
re­
analyzed
to
confirm
results.
The
average
total
residues
of
hexazinone
and
its
regulated
metabolites,
from
duplicate
analysis,
were
1.915
ppm
for
"A
molasses".
Based
on
this
re­
analysis,
residues
of
hexazinone
and
metabolites
concentrated
about
8.0x
in
"A
molasses".
The
registrant
reported
that
a
4.0x
concentration
factor
should
be
considered
when
"A
molasses"
is
further
processed
to
final
(blackstrap)
molasses,
the
form
of
molasses
typically
fed
to
livestock.

To
reassess
the
adequacy
of
the
established
0.5
ppm
tolerance
for
sugarcane
molasses,
HED
will
consider
the
HAFT
residue
reported
from
the
field
study
as
well
as
the
concentration
factors
observed
from
the
processing
study.
Data
from
the
sugarcane
field
trials
indicate
that
residues
of
hexazinone
and
its
regulated
metabolites,
as
measured
by
the
data­
collection
method,
were
<0.35
ppm
(or
<0.05
ppm
for
each
compound)
in/
on
samples
of
sugarcane
treated
according
to
the
maximum
registered
use
pattern.
According
to
OPPTS
GDLN
860.1520,
if
no
quantifiable
residues
are
found
in
the
RAC
from
the
maximum
registered
rate,
but
the
exaggerated
rate
does
produce
quantifiable
residues,
the
latter
samples
should
be
adjusted
for
the
degree
of
exaggeration.
These
adjusted
residues
should
then
be
compared
to
the
LOQ
for
the
RAC.
If
the
adjusted
residues
are
greater
than
or
equal
to
twice
the
LOQ,
then
a
tolerance
is
needed.

The
maximum
average
combined
residue
of
hexazinone
and
its
regulated
metabolites
was
1.915
ppm
for
"A
molasses".
To
correct
concentrations
in
"A
molasses"
to
blackstrap
molasses,
residues
in
"A
molasses"
are
multiplied
by
a
concentration
factor
of
4.0x,
resulting
in
7.66
ppm.
Adjusting
for
the
degree
of
exaggeration
(2.0x)
used
in
the
processing
study,
the
residue
for
blackstrap
molasses
is
3.83
ppm.
Because
this
result
is
greater
than
twice
the
LOQ
for
the
RAC
(sugarcane),
the
available
data
suggest
that
the
established
tolerance
for
sugarcane
molasses
should
be
decreased
from
5.0
ppm
to
4.0
ppm.

GLN
860.1480:
Meat,
Milk,
Poultry,
and
Eggs
The
Agency
changed
the
data
requirement
status
for
this
GLN
topic
from
"Reserved"
to
"Required"
because
the
results
of
ruminant
metabolism
study
suggested
a
very
significant
transfer
of
hexazinone
residues
of
concern
to
meat
and
milk
(Memo,
2/
4/
93,
R.
Perfetti).
The
registrant
has
since
submitted
an
acceptable
dairy
cattle
feeding
study
(MRID
43703501)
which
was
deemed
acceptable.
HED
is
recommending
that
in
order
to
reassess
the
established
hexazinone
tolerances
for
milk
and
the
fat,
meat,
and
meat
byproducts
of
livestock
and
to
compute
a
maximum
theoretical
dietary
burden
(MTDB)
27
of
hexazinone
to
livestock,
uses
on
pasture
and
rangeland
grasses
must
be
revoked.
A
MTDB
could
not
be
calculated
including
grass
and
grass
hay
since
additional
residue
data
are
required
for
use
patterns
in
which
significant
residues
are
expected
in/
on
the
RACs.
HED
recognizes
that
the
estimated
100,000
acres
of
pasture
and
rangeland
treated
with
hexazinone
is
relatively
low.
Since
grass
and
grass
hay
are
considered
major
dietary
components
of
ruminants
(up
to
60%
of
the
diet
per
current
OPPTS
GLN)
a
MTDB
for
livestock
could
not
be
developed
when
grasses
are
included
in
the
registered
uses.
HED
has
determined
that
a
MTDB
could
be
constructed
from
other
potential
feed
items
for
livestock
and
subsequently
tolerances
for
meats
and
milk
can
be
reassessed.
HED
has
previously
determined
that
tolerances
in
poultry
commodities
and
a
poultry
feeding
study
are
not
required
for
reregistration
based
on
results
of
reviewed
poultry
metabolism
data.

Maximum
theoretical
dietary
burden
(tentative,
pending
revocation
of
uses
on
pasture
and
rangeland
grasses
and
hay)

There
are
no
registered
direct
livestock
treatments
for
hexazinone
on
cattle,
goats,
hogs,
horses,
or
sheep.
However,
hexazinone
residues
of
concern
may
transfer
to
milk
and
edible
tissues
of
livestock
as
a
result
of
ingestion
of
feed
items
such
as:
alfalfa
forage,
hay,
meal,
and
silage;
grass
forage,
hay,
and
silage;
pineapple
process
residue;
and
sugarcane
molasses.
The
maximum
theoretical
dietary
burdens
of
hexazinone
to
beef
and
dairy
cattle
are
tentatively
calculated
to
be
4.64
ppm
(see
Table
3
below).
The
dietary
burden
calculations
are
tentative
because
it
assumes
use
on
pasture
and
rangland
grasses
will
be
canceled
and
tolerances
revoked
Table
3.
Tentative
calculation
of
maximum
ruminant
dietary
burden
for
hexazinone.

Feed
Commodity
Reassessed
Tolerance
(ppm)
%
Dry
Matter
1
Beef
Cattle
Dairy
Cattle
%
of
Diet
1
Burden
(ppm)
2
%
of
Diet
1
Burden
(ppm)
2
Alfalfa,
forage
2
35
60
3.
43
60
3.
43
Alfalfa,
hay
(as
meal)
4
89
15
0.68
15
0.68
Sugarcane
molasses
4
75
10
0.53
10
0.53
TOTAL
85
3
4.64
85
3
4.64
1
Table
1
(OPPTS
Guideline
860.1000).
2
Contribution
=
[tolerance
/
%
DM
(if
cattle)]
X
%
diet).
3
All
beef
and
dairy
cattle
in
the
U.
S.
should
have
in
their
diet
15%
cottonseed
meal,
peanut
meal,
soybean
meal,
canola
meal,
or
flax
seed
meal.
Hexazinone
is
not
registered
for
use
on
any
of
these
commodities.
Therefore,
to
account
for
these
commodities
in
the
diet
of
beef
and
dairy
cattle,
the
percentage
has
been
reduced
by
15%
to
85%.

Dairy
cattle
feeding
study
28
A
brief
summary
of
the
reviewed
dairy
cattle
feeding
study
(MRID
43703501)
is
presented
below.
Three
groups
of
dairy
cows
(3
animals/
dose
group)
were
dosed
with
hexazinone
at
29,
87,
and
290
ppm
in
the
diet
for
28
consecutive
days;
three
additional
cows
served
as
control
animals.
The
registrant
indicated
that
these
dose
levels
represent
feeding
level
of
1.0x,
3.0x,
and
10.0x
based
on
a
diet
of
grass
forage.
These
dose
levels
are
equivalent
to
6.25x,
18.75x,
and
62.5x,
respectively,
the
maximum
theoretical
dietary
burden
for
beef
and
dairy
cattle
when
grass
or
grass
hay
is
not
included.
An
additional
treatment
group,
fed
at
17.4
ppm
(3.88x),
was
added
later,
and
one
animal
was
held
over
from
the
control
group
for
this
phase
of
the
study.
These
dose
levels
are
equivalent
to
64x,
190x,
and
640x
the
MTDB
for
hogs.
Hexazinone
was
placed
into
gelatin
capsules
and
administered
by
balling
gun,
twice
daily
after
each
milking.
Milk
was
collected
twice
daily.
The
cattle
were
sacrificed
13­
21
hours
after
administration
of
the
final
dose,
and
samples
of
liver,
kidney,
muscle,
and
fat
were
collected.

The
collected
milk
and
tissue
samples
were
analyzed
for
residues
of
hexazinone
and
its
metabolites
using
two
analytical
methods.
One
method
was
used
for
milk,
muscle,
and
fat,
and
another
method
for
liver
and
kidney.
Although
cumbersome
and
complicated,
the
method
was
deemed
adequate
for
data
collection.
Based
on
the
data­
collection
method
used
in
this
study,
the
registrant
is
now
proposing
an
LC/
MS
method
(designated
as
du
Pont
AMR
3783­
96)
as
an
enforcement
method
for
milk
and
animal
tissues.
Refer
to
"GLN
860.1340:
Residue
Analytical
Methods
­
Animal
Commodities"
for
a
discussion
of
this
method
and
a
list
of
specific
hexazinone
residues
that
the
method
can
determine.
Assuming
Method
AMR
3783­
96
passes
a
successful
tolerance
method
validation,
the
tolerance
expression
for
milk
and
tissues
will
be
changed.

The
maximum
total
hexazinone
residues
in
milk
were
0.78
ppm
at
the
6.25x
feeding
level
(29
ppm
in
the
diet)
and
11.09
ppm
at
the
62.5x
level.
On
day­
14,
after
total
residues
had
reached
plateaus,
milk
was
separated
into
skim
milk
and
cream.
Total
residues
in
skim
milk
were
comparable
to
those
in
whole
milk;
total
residues
in
cream
were
approximately
half
those
in
skim
milk.
In
tissues,
the
maximum
total
hexazinone
residues
at
the
62.5x
feeding
level
were
3.85
ppm
in
liver,
2.19
ppm
in
kidney,
0.32
ppm
in
muscle,
and
nondetectable
(
#
0.10
ppm)
in
fat.
The
maximum
total
residues
at
the
6.25x
feeding
level
were
0.24
ppm
in
liver,
0.47
ppm
in
kidney,
and
nondetectable
(
#
0.15
ppm)
in
muscle.
Because
total
residues
were
nondetectable
in
all
fat
samples
from
the
18.75x
and
62.5x
levels,
fat
samples
were
not
analyzed
at
lower
feeding
levels.

A
tolerances
of
0.5
ppm
is
presently
established
for
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone)
in
milk.
Based
on
the
MTDB
for
beef
and
dairy
cattle
without
grass
or
grass
hay
as
a
potential
feed
item,
it
is
possible
to
re­
assess
the
animal
commodity
tolerances.
The
HED
MARC
has
concluded
that
the
hexazinone
tolerance
expression
for
ruminants
should
include
29
hexazinone
plus
metabolites
B,
C,
C­
2,
and
F
for
milk.
Residue
levels
of
hexazinone
and
metabolites
in
whole
milk
from
the
feeding
study
corrected
for
exaggeration
levels
ranged
from
0.110
ppm
to
0.164
ppm.
Based
on
the
enforcement
method,
the
sum
of
the
LOQ's
for
hexazinone
and
metabolites
B,
C,
C­
2,
and
F
is
0.20
ppm;
therefore,
it
is
appropriate
that
the
tolerance
for
milk
be
reduced
from
0.5
to
0.20
ppm.

Tolerances
of
0.1
ppm
are
presently
established
for
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone)
in
fat,
meat,
and
meat
byproducts
of
cattle,
goats,
hogs,
horses,
and
sheep.
The
Committee
concluded
that
the
hexazinone
tolerance
expression
for
ruminant
tissue
should
include
hexazinone
plus
metabolites
B
and
F.
Residue
levels
of
hexazinone
and
metabolites
in
kidney
from
the
feeding
study
corrected
for
exaggeration
levels
ranged
from
0.046
ppm
to
0.090
ppm.
Based
on
the
enforcement
method,
the
sum
of
the
LOQ's
for
hexazinone
and
metabolites
B
and
F
is
0.10
ppm
therefore
it
is
appropriate
that
the
tolerance
for
meat
byproducts
of
cattle,
goats,
horses,
and
sheep
be
reassessed
at
0.10
ppm.
Residue
levels
of
hexazinone
and
metabolites
from
the
feeding
study
corrected
for
exaggeration
levels
ranged
from
0.003
ppm
to
0.007
ppm
therefore
tolerances
for
hog
meat
are
not
required.

Residue
levels
of
hexazinone
and
metabolites
in
muscle
from
the
feeding
study
corrected
for
exaggeration
levels
ranged
from
0.003
ppm
to
0.039
ppm.
Based
on
the
enforcement
method,
the
sum
of
the
LOQ's
for
hexazinone
and
metabolites
B
and
F
is
0.10
ppm;
therefore,
it
is
appropriate
that
the
tolerance
for
meat
byproducts
of
cattle,
goats,
horses,
and
sheep
be
reassessed
at
0.10
ppm.
Residue
levels
of
hexazinone
and
metabolites
in
muscle
from
the
feeding
study
corrected
for
exaggeration
levels
ranged
from
0.0004
ppm
to
0.002
ppm
therefore
tolerances
for
hog
meat
are
not
required.

Tolerances
of
0.1
ppm
are
presently
established
for
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone)
in
fat.
Residue
levels
of
hexazinone
and
metabolites
in
fat
from
the
feeding
study
were
nondetectable
(<
0.1
ppm)
at
the
62.5x
exaggerated
rate.
The
Agency
has
determined
that
tolerances
for
hexazinone
residues
in
fat
of
cattle,
goats,
hogs,
horses,
and
sheep
are
not
required
(Category
3,
40
CFR
§180.6a).
Tolerances
for
fat
of
cattle,
goats,
hogs,
horses,
and
sheep
are
not
required
and
should
be
revoked.

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

GLN
860.1460:
Food
Handling
30
Hexazinone
is
presently
not
registered
for
use
in
food­
handling
establishments;
therefore,
no
residue
chemistry
data
are
required
under
this
guideline
topic.

GLN
860.1850:
Confined
Accumulation
in
Rotational
Crops
The
data
requirements
for
confined
rotational
crops
are
satisfied.
The
basic
registrant
has
submitted
acceptable
studies
(MRIDs
41008401,
42824001,
43892401)
which
indicate
that
[
14
C]
hexazinone
residues
accumulate
at
0.01
ppm
in/
on
tested
rotational
crop
commodities
at
certain
plantback
intervals.
Based
on
these
data,
the
registrant
was
required
to
conduct
a
limited
field
rotational
crop
study
in
order
to
assess
the
adequacy
of
existing
rotational
crop
restrictions
on
the
registrant's
end­
use
product
labels
and
to
determine
whether
rotational
crop
tolerances
are
needed.

The
major
residue
components
that
were
identified
from
the
confined
rotational
crop
study
were
either
the
glucose
conjugate
of
G3170
or
hexazinone
or
both.
The
remaining
ten
identified
metabolites
all
contain
the
triazinone
ring
structure,
and
four
of
these
compounds
(metabolites
A,
B,
C,
and
F)
have
been
determined
to
be
residues
of
concern
in/
on
primary
crops.

GLN
860.1900:
Field
Accumulation
in
Rotational
Crops
The
data
requirements
for
field
accumulation
in
rotational
crops
are
only
partially
satisfied.
This
conclusion
is
based
on
a
recent
review
of
a
limited
field
crop
rotation
study
(MRID
45084101)
wherein
the
75%
DF
formulation
of
hexazinone
was
applied
as
a
single
postemergence
broadcast
application
to
mowed
alfalfa
at
test
sites
in
MN
and
CA
at
1.5
lb
ai/
A
(1x
the
maximum
seasonal
rate
for
alfalfa).
Approximately
one
year
following
application,
the
remaining
alfalfa
crop
residue
was
plowed
up
and
returned
to
the
soil,
and
head
lettuce,
field
corn,
and
wheat
were
planted
(350
days
after
treatment,
DAT,
for
the
MN
test
site
and
358
DAT
for
the
CA
test
site).

Residues
were
below
the
respective
method
LOQs
for
hexazinone
and
metabolites
A,
B,
C,
D,
E,
F,
G,
H,
G3170,
G3170­
NG,
A­
1,
and
C­
1
in/
on
head
lettuce,
wheat
forage
and
grain,
and
field
corn
forage
and
grain.
In
wheat
straw,
residues
of
metabolite
B
were
<0.02­
0.021
ppm;
residues
of
hexazinone
and
the
remaining
metabolites
were
below
the
LOQ.
In
field
corn
stover,
residues
of
hexazinone
were
0.02­
0.081
ppm,
residues
of
metabolite
B
were
0.038­
0.053
ppm,
and
residues
of
the
remaining
metabolites
were
below
the
LOQ.

These
data
indicate
that
extended
field
rotational
crop
studies
and
rotational
crop
tolerances
will
not
be
required
for
residues
of
hexazinone
residues
of
concern
in/
on
leafy
vegetables
provided
that
labels
are
amended
to
specify
a
rotational
crop
restriction
of
at
least
12
months.
A
previous
review
of
a
confined
rotational
crop
study
concluded
31
that
rotational
crop
tolerances
were
not
needed
for
root
crops
provided
that
a
12­
month
plantback
interval
was
established;
an
examination
of
the
basic
registrant's
labels
shows
that
the
12­
month
plantback
interval
for
root
crops
has
been
established.

Because
the
data
from
the
limited
field
trials
indicate
that
quantifiable
residues
occur
in
field
corn
stover
and
wheat
straw,
extended
field
rotational
crop
trials
for
corn
stover,
sorghum
stover,
and
wheat
straw
to
support
a
12­
month
rotational
interval
and
a
tolerance
for
inadvertent
hexazinone
residues
are
required.

The
data
for
the
application
rate
used
in
this
study
are
sufficient
to
support
rotation
from
alfalfa
and
pasture
and
rangeland
grass
only.
The
registrant
has
stated
previously
that
they
intend
to
modify
product
labels
to
restrict
rotation
from
sugarcane
to
sugarcane
only
(HED
memorandum,
10/
31/
96,
J.
Abbotts).
32
Table
B.
Residue
Chemistry
Science
Assessments
for
Reregistration
of
Hexazinone.

GLN:
Data
Requirements
Tolerances
[40
CFR]
(ppm)
Must
Additional
Data
Be
Submitted?
References
1
860.1200:
Directions
for
Use
N/
A
=
Not
Applicable
Yes
2
See
Table
A
860.1300:
Plant
Metabolism
N/
A
No
00078047,
00104846,
00126127
860.1300:
Animal
Metabolism
N/
A
No
00104843,
41524801,
42187901
3
,
42219301
4
,
42248901
5
,
42690601
6
,
43488901
7
860.1340:
Residue
Analytical
Methods
­
Plant
commodities
N/
A
No
00038868,
00101574,
00126127,
41964101,
41964102,
42987201
8
,
430025401
9
­
Animal
commodities
N/
A
Reserved
10
00038868,
43074201
11
,
44259101
12
,
44259102
12
860.1360:
Multiresidue
Methods
N/
A
No
41572101,
41572102,
41572103,
41572104,
41572105,
41572106
860.1380:
Storage
Stability
Data
­
Plant
commodities
N/
A
No
42276001
13
,
42322701
14
,
42418001
15
,
42423001
16
,
42492101
17
,
42535601
18
,
42867501
19
,
43524301
20
,
43936501
21
,
44133501
22
­
Animal
commodities
N/
A
No
43703501
23
860.1500:
Crop
Field
Trials
Berries
Group
­
Blueberries
0.2
[§
180.396(
a)]
No
24
00101574,
41964101,
41964102
Grass
Forage,
Fodder,
Hay
Group
GLN:
Data
Requirements
Tolerances
[40
CFR]
(ppm)
Must
Additional
Data
Be
Submitted?
References
1
33
­
Grasses
(pastures
and
rangeland),
forage
and
hay
10,
grasses,
pasture
and
rangeland
[§
180.396(
a)]
Yes
25,
26
00138226,
41898301
27
,
42419101
15
,
42867501
19
Table
B
(continued).

GLN:
Data
Requirements
Tolerances
[40
CFR]
(ppm)
Must
Additional
Data
Be
Submitted?
References
1
34
Non­
grass
Animal
Feeds
(forage,
fodder,
straw,
and
hay)
Group
­
Alfalfa,
forage,
hay,
and
seed
2.0,
forage
8.0,
hay
[§
180.396(
a)]
No
28
,
29
00118050,
43074401
30
,
43074402
30
Miscellaneous
Commodities
­
Pineapple
0.
5,
whole
fruit
[§
180.396(
a)]
No
00126127,
42535601
18
­
Sugarcane
0.
2
[§
180.396(
c)]
No
00028733,
00114039,
42322701
14
860.1520:
Processed
Food/
Feed
­
Pineapple
None
No
42492101
17
,
43401901
31
­
Sugarcane
5.
0,
molasses
[§
180.396(
c)]
No
42276001
13
,
42417901
32
,
PP#
8F2119/
FAP#
4H5683
33
860.1480:
Meat,
Milk,
Poultry,
Eggs
­
Milk,
Fat,
Meat,
and
Meat
Byproducts
of
Cattle,
Goats,
Hogs,
Horses,
and
Sheep
0.1,
milk,
fat,
meat,
and
meat
byproducts
[§
180.396(
a)]
No
34
00028866,
00140161,
43703501
23
­
Eggs
and
the
Fat,
Meat,
and
Meat
Byproducts
of
Poultry
None
No
35
00104845
860.1400:
Water,
Fish,
and
Irrigated
Crops
NA
No
860.1460:
Food
Handling
NA
No
860.1850:
Confined
Rotational
Crops
NA
No
41008401
36
,
42824001
37
,
43892401
38
860.1900:
Field
Rotational
Crops
None
Yes
39
45084101
40
Table
B
(continued).

35
1.
Bolded
references
were
reviewed
in
the
Reregistration
Update
of
9/
5/
91.
Unbolded
references
were
reviewed
in
the
Residue
Chemistry
Science
Chapter
of
the
Final
Registration
Standard
and
Tolerance
Reassessment
(FRSTR)
dated
5/
25/
88.
All
other
references
were
reviewed
as
noted.

2.
Label
amendments
are
required
for
alfalfa
and
blueberries,
and
details
of
the
required
label
amendments
are
presented
in
the
respective
endnote
for
GLN
860.1500
(Crop
Field
Trials)
of
this
table.
Label
amendments
are
also
required
to
establish
a
12­
month
plantback
interval
for
leafy
vegetables.

3.
DP
Barcode
D174764,
CBRS
No.
9418,
5/
22/
92,
J.
Abbotts.

4.
DP
Barcode
D175243,
CBRS
No.
9510,
7/
14/
92,
J.
Abbotts.

5.
DP
Barcode
D176715,
CBRS
No.
9697,
9/
15/
92,
J.
Abbotts.

6.
DP
Barcode
D189285,
CBRS
No.
11656,
6/
25/
93,
J.
Abbotts.

7.
DP
Barcode
D210574,
CBRS
No.
14889,
1/
19/
95,
J.
Abbotts.

8.
DP
Barcode
D196446,
CBRS
No.
12815,
1/
6/
94,
J.
Abbotts.

9.
DP
Barcode
D197342,
CBRS
No.
12932,
1/
6/
94,
J.
Abbotts.

10.
The
registrant
has
proposed
an
LC/
MS
method
(designated
as
du
Pont
AMR
3783­
96)
as
an
enforcement
method
for
animal
commodities.
Method
AMR
3783­
96
has
been
subjected
to
a
successful
ILV
and
a
radiovalidation
study.
Method
AMR
3783­
96
will
be
forwarded
to
the
Analytical
Chemistry
Branch
(ACL;
Beltsville,
MD)
for
a
tolerance
method
validation
by
Agency
chemists.
If
the
results
of
method
validation
are
successful,
then
Method
AMR
3783­
96
will
be
proposed
for
inclusion
in
PAM
Volume
II,
and
no
additional
enforcement
methodology
for
animal
commodities
will
be
required
for
reregistration.

11.
DP
Barcode
D198348,
CBRS
No.
13076,
5/
25/
94,
S.
Hummel.

12.
DP
Barcode
D282683,
05/
15/
02,
J.
S.
Punzi.

13.
DP
Barcode
D177572,
CBRS
No.
9808,
6/
18/
92,
S.
Funk.

14.
DP
Barcode
D178771,
CBRS
No.
9985,
9/
22/
92,
J.
Abbotts.

15.
DP
Barcode
D181318,
CBTS
No.
10354,
1/
28/
93,
R.
Lascola.

16.
DP
Barcode
D181480,
CBRS
No.
10365,
11/
9/
92,
J.
Abbotts.

17.
DP
Barcode
D183296,
CBRS
No.
10702,
2/
23/
93,
J.
Abbotts.

18.
DP
Barcode
D184852,
CBRS
No.
10924,
2/
25/
93,
J.
Abbotts.

19.
DP
Barcode
D195426,
CBRS
No.
12617,
10/
25/
93,
J.
Abbotts.

20.
DP
Barcode
D211642,
CBRS
No.
15101,
3/
14/
95,
J.
Abbotts.

21.
DP
Barcode
D282685,
05/
15/
02,
J.
S.
Punzi.
Table
B
(continued).

36
22.
DP
Barcode
D282682,
05/
15/
02,
J.
Punzi.

23.
DP
Barcode
D217257,
CBRS
No.
15881,
9/
25/
95,
J.
Abbotts.

24.
No
additional
data
are
required
for
blueberries.
However,
label
revisions
remain
a
requirement.
The
product
labels
for
ME980002
and
ME980003,
which
are
limited
for
use
on
lowbush
blueberries,
should
be
amended
to
specify
a
PHI
of
450
days.
The
product
label
for
NC830012
should
also
be
amended
to
specify
PHIs
of
90
and
450
days
for
application
to
highbush
and
lowbush
blueberries,
respectively.

25.
Uses
on
grass
should
be
cancelled
and
tolerances
revoked.
The
following
grass
forage
would
be
required
for
grass:
"Data
depicting
magnitude
of
the
residues
of
hexazinone
and
metabolites
A,
B,
C,
D,
and
E
in/
on
grass
forage
harvested
0
day
following
a
single
broadcast
application
of
representative
formulations
at
1.125
lb
ai/
A.
It
is
the
Agency
policy
to
require
0­
day
crop
field
residue
data
for
grass
forage
unless
it
is
not
feasible
(e.
g.,
preplant/
preemergence
pesticide
uses).
The
formulations
to
be
tested
may
be
applied
in
side­
by­
side
plots.
The
location
and
number
of
trials
should
be
in
compliance
with
the
current
OPPTS
GLN
for
adequate
geographic
representation
of
data.

26.
Uses
on
grass
should
be
cancelled
and
tolerances
revoked.
Additional
grass
hay
data
would
be
required.
The
registrant
has
submitted
a
petition
(PP#
1F3967)
for
the
establishment
of
a
tolerance
for
residues
of
hexazinone
and
its
metabolites
in/
on
grass
hay.
The
petition
is
currently
in
reject
status
because
additional
grass
hay
data,
from
field
trials
with
adequate
geographical
representation,
remain
outstanding.

27.
DP
Barcodes
D165324,
D165303,
and
D165277,
CBRS
Nos.
8147,
8148,
8149,
8134,
8152,
and
8153,
11/
14/
91,
J.
Smith.

28.
No
additional
data
are
required
for
alfalfa
forage
and
hay.
However,
the
product
label
for
the
2
lb/
gal
EC
(EPA
Reg.
No.
352­
392)
formulation
must
be
amended
to
establish
a
30­
day
PHI
(or
pregrazing
interval)
for
the
feeding
of
forage
and
the
cutting
of
hay.

29.
No
additional
data
are
required
for
alfalfa
seed.
However,
the
registrant
is
required
to
propose
a
tolerance
for
hexazinone
residues
of
concern
in/
on
alfalfa
seed;
the
available
data
suggest
that
a
tolerance
level
of
2.0
ppm
is
appropriate.

30.
DP
Barcode
D198336,
CBRS
No.
13075,
6/
22/
94,
S.
Hummel.

31.
DP
Barcode
D208605,
CBRS
No.
14591,
1/
20/
95,
C.
Eiden
and
DP
Barcode
D215057,
11/
28/
95,
C.
Eiden.

32.
DP
Barcode
D181308,
CBRS
No.
10333,
10/
26/
92,
B.
Cropp­
Kohlligian.

33.
DP
Barcode
D196510,
CB
No.
12796,
9/
1/
94,
S.
Hummel.

34.
An
acceptable
dairy
cattle
feeding
study
is
available.
HED
is
able,
at
this
time,
to
reassess
the
established
hexazinone
tolerances
for
milk
and
the
fat,
meat,
and
meat
byproducts
of
livestock
using
maximum
theoretical
dietary
burdens
of
hexazinone
to
livestock,
calculated
without
grass
or
grass
hay.
Since
additional
residue
data
are
required
for
grass
forage
and
hay,
for
which
significant
residues
are
expected
in/
on
the
RACs
and
are
considered
major
dietary
components
of
ruminants,
HED
recommends
that
the
uses
be
canceled
and
tolerances
revoked.

35.
HED
has
determined
that
tolerances
for
hexazinone
residues
in
eggs
and
poultry
tissues
are
not
required
(Category
3,
40
CFR
§180.6)
based
on
the
results
of
the
reviewed
poultry
metabolism
study.

36.
DP
Barcode
D188349,
CBRS
No.
11458,
5/
14/
93,
L.
Cheng.
Table
B
(continued).

37
37.
DP
Barcode
D192877,
CBRS
No.
12222,
3/
3/
94,
F.
Fort.

38.
DP
Barcode
D222455,
CBRS
No.
16791,
7/
1/
96,
L.
Cheng.

39.
Because
the
data
from
the
limited
field
trials
indicate
that
quantifiable
residues
occur
in
field
corn
stover
and
wheat
straw,
extended
field
rotational
crop
trials
for
corn
stover,
sorghum
stover,
and
wheat
straw
to
support
a
12­
month
rotational
interval
and
a
tolerance
for
inadvertent
hexazinone
residues
are
required.

40.
DP
Barcode
D282684,
05/
15/
02,
J.
S.
Punzi.
38
TOLERANCE
REASSESSMENT
SUMMARY
Tolerances
for
residues
of
hexazinone
in/
on
plant,
livestock,
and
processed
commodities
are
currently
expressed
in
terms
of
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone).
Permanent
tolerances
are
established
for
several
raw
agricultural
commodities
and
livestock
commodities
under
40
CFR
§180.396(
a).
Tolerances
with
regional
registrations
which
exclude
use
of
hexazinone
on
sugarcane
in
Florida
are
established
under
40
CFR
§180.396(
c).

The
qualitative
nature
of
the
residue
in
plants
and
livestock
is
adequately
understood.
The
HED
MARC
concluded
that
the
hexazinone
tolerance
expression
for
plants
and
rotational
crops
should
include
hexazinone
and
metabolites
A,
B,
C,
D,
and
E.
The
qualitative
nature
of
the
residue
in
livestock
is
adequately
understood
based
on
acceptable
ruminant
and
poultry
metabolism
studies.
The
HED
MARC
concluded
that
the
hexazinone
tolerance
expression
for
ruminants
should
include
hexazinone
plus
metabolites
B,
C,
C­
2,
and
F
for
milk.
The
Committee
concluded
that
the
hexazinone
tolerance
expression
for
ruminant
tissue
should
include
hexazinone
plus
metabolites
B
and
F.
The
Committee
concluded
that
residues
of
hexazinone
and
metabolites
B,
C,
C1
C­
2,
and
F
should
be
taken
into
account
when
risk
assessments
are
done.
HED
has
determined
that
tolerances
for
hexazinone
residues
in
eggs
and
poultry
tissues,
hog
meat
and
meat
by
products,
and
fat
of
livestock
are
not
required
(Category
3,
40
CFR
§180.6)
based
on
the
results
of
the
respective
metabolism
and
feeding
studies.

An
adequate
enforcement
method
is
available
for
plant
commodities.
Method
I
of
PAM,
Volume
II
is
a
nitrogen­
selective
GLC
method
capable
of
determining
residues
of
hexazinone
and
metabolites
A,
B,
C,
D,
and
E.
The
combined
limit
of
quantitation
(LOQ)
for
hexazinone
residues
by
Method
I
is
0.55
ppm.
An
enforcement
method,
Method
AMR
3783­
96,
has
been
proposed
for
milk
and
livestock
tissues.
Method
AMR
3783­
96
has
been
subjected
to
a
successful
ILV
and
a
radiovalidation
study.
It
will
be
forwarded
to
the
Analytical
Chemistry
Branch
for
a
tolerance
method
validation
by
Agency
chemists.

HED
is
recommending
that
the
hexazinone
tolerances
listed
under
40
CFR
§180.396
(a)
and
(c)
be
reorganized,
as
listed
below,
to
indicate
the
specific
residues
of
concern
that
can
be
quantitated
by
the
existing
plant
enforcement
method
and
the
proposed
livestock
enforcement
method.
This
proposal
to
reorganize
hexazinone
tolerances
is
contingent
upon
successful
validation
of
Method
AMR
3783­
96.
Note
that
for
simplicity
the
tolerence
expression
is
shown
as
"Hexazinone
and
its
metabolites
A,
B,
C,
D,
and
E
(calculated
as
hexazinone)"
however
the
metabolites
must
be
identified
by
the
appropriate
chemical
name.

Table
4.
39
40
CFR
Reserved
for
Tolerance
Expression
§180.396
(a)
(1)
Permanent
tolerances
for
plant
and
processed
commodities
Hexazinone
and
its
metabolites
A,
B,
C,
D,
and
E
(calculated
as
hexazinone)

§180.396
(a)
(2)
Milk
Hexazinone
and
its
metabolite
B,
metabolite
C
and
its
isomer
(C­
2),
and
metabolite
F
(calculated
as
hexazinone)

§180.396
(a)
(3)
Ruminant
tissues
Hexazinone
and
its
metabolite
B
and
metabolite
F
(calculated
as
hexazinone)

§180.396
(c)
Tolerances
for
plant
and
processed
commodities
with
regional
registration
Hexazinone
and
its
metabolites
A,
B,
C,
D,
and
E
(calculated
as
hexazinone)

NOTE:
See
Figure
1
for
full
chemical
names
of
regulated
hexazinone
metabolites.

A
summary
of
hexazinone
tolerance
reassessments
is
presented
in
Table
C.
Discussions
of
residue
data
used
for
tolerance
reassessment
are
presented
in
the
"Summary
of
Science
Findings"
section
for
GLNs
860.1500
(Crop
Field
Trials)
and
860.1480
(Meat,
Milk,
Poultry,
and
Eggs).
Certain
commodity
definitions
need
to
be
corrected.

Tolerances
Listed
Under
40
CFR
§180.396
(a):

Sufficient
data
are
available
to
ascertain
the
adequacy
of
tolerances
listed
in
40
CFR
§180.96
(a)
for
alfalfa
forage,
alfalfa
hay,
blueberries,
and
pineapple.
Tolerances
for
pasture
and
rangeland
grasses
should
be
revoked
and
uses
cancelled.

An
acceptable
ruminant
feeding
study
is
available;
HED
is
able
to
reassess
the
established
hexazinone
tolerances
for
milk
and
the
fat,
meat,
and
meat
byproducts
of
livestock
using
a
maximum
theoretical
dietary
burden
of
hexazinone
to
livestock
assuming
revocation
of
tolerances
for
grasses
and
hay.

The
established
tolerances
for
blueberries
and
pineapple
should
be
increased
to
0.60
ppm
to
reflect
the
combined
LOQs
of
the
enforcement
method.
The
available
field
trial
data
indicate
that
residues
of
hexazinone
and
its
regulated
metabolites,
as
measured
by
the
data­
collection
method,
were
nondetectable
in/
on
these
RACs
following
treatment
at
1.0x.

Tolerances
Needed
Under
40
CFR
§180.396
(a):

The
registrant
is
required
to
propose
a
tolerance
for
hexazinone
residues
of
concern
in/
on
alfalfa
seed;
the
available
data
suggest
that
a
tolerance
level
of
2.0
ppm
is
appropriate.

Tolerances
Listed
Under
40
CFR
§180.396
(c):
40
Adequate
data
are
available
for
sugarcane
and
sugarcane
molasses.
The
tolerance
for
sugarcane
molasses
should
be
reduced
from
5.0
ppm
to
4.0
ppm
based
on
re­
calculation
of
expected
residues.
41
(continued;
endnotes
follow)
Table
C.
Tolerance
Reassessment
Summary
for
Hexazinone.

Commodity
Current
Tolerance
(ppm)
a
Range
of
residues
(ppm)
b
Tolerance
Reassessment
(ppm)
Comment/
Correct
Commodity
Definition
Tolerances
listed
under
40
CFR
§180.396(
a):

Alfalfa
green
forage
2
<1.87
2.0
Alfalfa,
forage
Alfalfa
hay
8
<3.33
4.
0
Alfalfa,
hay
Blueberries
0.2
<0.3
ppm
(nondetectable;
<0.05
ppm
for
each
compound)
0.60
Tolerance
should
be
increased
based
on
the
combined
LOQ
(0.55
ppm)
of
the
enforcement
method.
Blueberry
Cattle,
fat
0.
1
Revoke
c
Cattle,
mbyp
0.1
0.
10
Cattle,
meat
0.1
0.
10
Goat,
fat
0.
1
Revoke
c
Goat,
mbyp
0.1
0.
10
Goats,
meat
0.1
0.
10
Grasses,
pasture
10
Revoke
d
Grass,
forage
Grass,
hay
Grasses,
rangeland
10
Revoke
d
Hog,
fat
0.1
Revoke
c
Hog,
mbyp
0.1
Revoke
c
Hog,
meat
0.1
Revoke
c
Horses,
fat
0.
1
Revoke
c
Horses,
mbyp
0.1
0.
10
Horses,
meat
0.1
0.
10
Milk
0.5
0.
20
Pineapple
0.
5
<0.35
(or
<0.05
ppm
for
each
compound)
0.60
Tolerance
should
be
increased
based
on
the
combined
LOQ
(0.55
ppm)
of
the
enforcement
method.

Sheep,
fat
0.
1
Revoke
c
Sheep,
mbyp
0.1
0.
10
Sheep,
meat
0.1
0.
10
Tolerances
needed
under
40
CFR
§180.396(
a):

Alfalfa,
seed
­­
<1.30­<
1.46
2.
0
Table
C
(continued).

Commodity
Current
Tolerance
(ppm)
a
Range
of
residues
(ppm)
b
Tolerance
Reassessment
(ppm)
Comment/
Correct
Commodity
Definition
42
Tolerances
listed
under
40
CFR
§180.396(
c):

Sugarcane
0.
2
<0.05
ppm
(nondetectable)
each
for
hexazinone
and
its
metabolites
0.60
Tolerance
should
be
increased
based
on
the
combined
LOQ
(0.55
ppm)
of
the
enforcement
method.

Sugarcane
molasses
5
(1.915
x
4x)
÷
2x
=
3.83
4.0
a
Expressed
in
terms
of
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone).
b
Refer
to
section
on
Magnitude
of
Residues
in
Crop
Plant
for
detailed
discussion
of
residues
in
crops.
c
Tolerances
for
fat
are
not
required
(Category
3,
40
CFR
§180.6).
d
HED
is
recommending
revocation
of
these
tolerances
and
cancellation
of
uses,
since
grasses
are
a
major
feed
item
and
required
data
are
not
available
for
reassessment.

CODEX
HARMONIZATION
No
maximum
residue
limits
(MRLs)
for
hexazinone
and
its
metabolites
have
been
established
or
proposed
by
Codex
for
any
agricultural
commodity.
Therefore,
no
compatibility
questions
exist
with
respect
to
U.
S.
tolerances..
43
AGENCY
MEMORANDA
CITATIONS
Agency
Memoranda
Citations
Relevant
to
Hexazinone
Reregistration.

Date
DP
Barcode
CB
No.
From
To
MRID
Nos.
Subject
7/
18/
91
D162863
7835
R.
Lascola
J.
Miller/
D.
Wilson
None
PP#
1F3967.
Hexazinone
(Velpar
L)
in/
on
Pasture
and
Rangeland
Hay.

11/
14/
91
D165277,
D165303,
D165324
8134,
8147,
8148,
8149,
8152,
8153
J.
Smith
J.
Miller
41898301
Hexazinone.
Amendment
of
label
reflecting
a
new
pregrazing
interval
for
forestry
use,
new
replanting
instructions
following
alfalfa,
reduced
use
on
sugarcane,
and
overall
clarifications.

3/
11/
92
D174869
9463
D.
McNeilly
A.
Ertman
None
Hexazinone
reregistration;
question
concerning
pineapple
forage
feeding
restriction
from
DuPont
Agricultural
Products.

5/
22/
92
D174764
9418
J.
Abbotts
L.
Rossi
42187901
Hexazinone.
Du
Pont
Company
Response
to
the
Reregistration
Standard:
Animal
Metabolism
Data
for
Goat.

6/
18/
92
D177572
9808
S.
Funk
A.
Ertman
42276001
Reregistration
of
Hexazinone
(Velpar).
171­
4(
l):

Sugarcane
Processing
Study.
171­
4(
K):
Sugarcane
Field
Trial
Time
Extension
Request.

6/
24/
92
D172408
9127
R.
Lascola
E.
Wilson/

J.
Miller
None
PP#
1F3967.
Hexazinone
(Velpar
L)
in/
on
Pasture
and
Rangeland
Hay.
Amended
Response
to
Registration
Standard
Data
Gap.

7/
14/
92
D175243
9510
J.
Abbotts
L.
Rossi
42219301
Hexazinone.
Du
Pont
Company
Response
to
the
Reregistration
Standard:
Storage
Stability
Data
for
Animal
Metabolism
in
Poultry.

8/
21/
92
D178781
9961
J.
Abbotts
A.
Ertman
None
Hexazinone.
Du
Pont
Company
Response
to
the
Reregistration
Update
to
the
Residue
Chemistry
Chapter.
Agency
Memo
Citations
for
Hexazinone
(continued).

Date
DP
Barcode
CB
No.
From
To
MRID
Nos.
Subject
44
8/
25/
92
D174070
9366
M.
Bradley
J.
Miller
None
Hexazinone.
Label
Amendment
to
Add
Pregrazing
Intervals
for
Forestry
and
Non
Crop
Land
Use.

9/
15/
92
D176715
9697
J.
Abbotts
L.
Rossi
42248901
Hexazinone.
Du
Pont
Company
Response
to
the
Reregistration
Standard:
Storage
Stability
Data
for
Animal
Metabolism
in
Goat.

9/
22/
92
D178771
9985
J.
Abbotts
L.
Rossi
42322701
Hexazinone.
Du
Pont
Company
Response
to
the
Reregistration
Standard:
Residue
Data
for
Sugarcane.

10/
26/
92
D181308
10333
B.
Cropp
Kohlligian
L.
Rossi
42417901
Hexazinone:
Supplemental
Data
Submitted
to
Address
Sugarcane
Processing
Study
Deficiencies.

11/
9/
92
D181480
10365
J.
Abbotts
L.
Rossi
42423001
Hexazinone.
Du
Pont
Company
Response
to
the
Reregistration
Standard:
Storage
Stability
Data
for
Blueberry.

1/
28/
93
D181318
10354
R.
Lascola
E.
Wilson/

J.
Miller
42418001
and
42419101
PP
1F3967.
Hexazinone
(Velpar
L)
in/
on
Pasture
and
Rangeland
Hay.

2/
4/
93
None
None
R.
Perfetti
L.
Rossi
and
E.
Saito
None
Animal
Feeding
Studies:
Requirement
Status
Modification.

2/
23/
93
D183296
10702
J.
Abbotts
L.
Rossi
42492101
Hexazinone.
Du
Pont
Company
Response
to
the
Reregistration
Standard:
Processing
Data
for
Pineapple.

2/
25/
93
D184852
10924
J.
Abbotts
L.
Rossi
42535601
Hexazinone.
Du
Pont
Company
Response
to
the
Reregistration
Standard:
Residue
Data
for
Pineapple.

5/
14/
93
D188349
11458
L.
Cheng
A.
Ertman/
W.
Waldrop
41008401
Hexazinone.
Rotational
Crop
Data
Requirement.

6/
25/
93
D189285
11656
J.
Abbotts
A.
Ertman
42690601
Hexazinone,
Reregistration.
Supplemental
Data
on
Poultry
Metabolism.
Agency
Memo
Citations
for
Hexazinone
(continued).

Date
DP
Barcode
CB
No.
From
To
MRID
Nos.
Subject
45
7/
22/
93
None
None
R.
Perfetti
L.
Rossi
and
A.
Rathman
None
Animal
Feeding
Studies.
Requirement
Status
Modification:
Reconsideration.

9/
9/
93
None
None
M.
Metzger
L.
Rossi
None
Animal
Feeding
Studies
(171­
4(
j));
Requirement
Status
Modification.

10/
5/
93
D194489
12425
J.
Abbotts
A.
Ertman
None
Hexazinone,
Reregistration.
Animal
Feeding
Study
Protocol.

10/
5/
93
D194395
12427
J.
Abbotts
A.
Ertman
None
Hexazinone,
Reregistration.
Pineapple
Residue
Data.

10/
8/
93
None
None
J.
Abbotts
L.
Rossi
and
F.
Chow/
C.
Frick
None
Hexazinone.
Reregistration
Eligibility
Document
Chapters
for
Product
Chemistry
and
Residue
Chemistry,
Current
Status.

10/
8/
93
None
None
J.
Abbotts
Hexazinone
Reregistration
File
None
Hexazinone.
Anticipated
Residues
for
Reregistration
Eligibility
Document.

10/
25/
93
D195426
12617
J.
Abbotts
A.
Ertman
42867501
Hexazinone,
Reregistration.
Storage
Stability
Data
in
Grass.

1/
6/
94
D196446
12815
J.
Abbotts
A.
Ertman
42987201
Hexazinone,
Reregistration.
Analytical
Method
for
Sugarcane
Commodities.

1/
6/
94
D197342
12932
J.
Abbotts
A.
Ertman
43025401
Hexazinone,
Reregistration.
Independent
Laboratory
Validation
of
an
Analytical
Method
for
Sugar
Commodities.

3/
3/
94
D192877
12222
F.
Fort
L.
Rossi/
W.
Waldrop
42824001
Hexazinone.
Supplemental
Information
Pertaining
to
Rotational
Crop
Requirements.
List
A
Case
No.
0266.

Chemical
I.
D.
No.
107201.

3/
16/
94
D199887
13301
S.
Hummel
A.
Ertman
None
Hexazinone
(107201),
Reregistration
Case
No.
0266.

Storage
Intervals
and
Conditions
in
Grass
Time
Extension
Request
for
Livestock
Feeding
Study.
Agency
Memo
Citations
for
Hexazinone
(continued).

Date
DP
Barcode
CB
No.
From
To
MRID
Nos.
Subject
46
4/
20/
94
D201203
13492
F.
Suhre
A.
Ertman
None
Hexazinone
(ID
107201).
Magnitude
of
the
Residue,

Cattle
Feeding
Study
[171­
4(
j)];
Protocol
Amendment.

4/
29/
94
D201738
13527
G.
Kramer
E.
Wilson/

J.
Miller
None
PP#
1F3967.
Hexazinone
(Velpar
L)
in/
on
Pasture
and
Rangeland
Hay.
Amendment
of
3/
28/
94.

5/
16/
94
None
None
S.
Hummel
Metabolism
Committee
None
Hexazinone
(107201),
Reregistration
Case
No.
0266.

Issues
to
be
Presented
to
the
Metabolism
Committee.

5/
25/
94
D198348
13076
S.
Hummel
A.
Ertman
43074201
Hexazinone
(107201),
Reregistration
Case
No.
266.

Livestock
Metabolism
­
Confirmatory
Analyses
Hexazinone
Tolerance
Expression.

5/
25/
94
D203472
None
S.
Hummel
HED
Metabolism
Committee
None
Hexazinone
(107201)
Plant
and
Animal
Metabolism:

Results
of
HED
Metabolism
Committee
Meeting
Held
May
19,
1994.

6/
1/
94
D202919
13649
F.
Suhre
W.
Waldrop
None
Hexazinone
(107201).
Pineapple
Processing
Study
171­
4(
l).

6/
22/
94
D198336
13075
S.
Hummel
A.
Ertman
43074401
and
43074402
Hexazinone
(107201)
Residue
Data
on
Alfalfa.

9/
1/
94
D196510
12796
S.
Hummel
E.
Wilson/

J.
Miller/
A.
Ertman
None
PP#
8F2119/
FAP#
4H5683
Hexazinone
(107201)

Residue
Data
on
Sugarcane
Reregistration
Case
No.

0266.

9/
8/
94
D207225
14319
S.
Hummel
A.
Ertman
None
Hexazinone
(107201)
­
Reregistration
Case
No.
0266.

Updated
Table
A
for
Residue
Chemistry
RED
Chapter.

9/
22/
94
D207493
14363
S.
Hummel
E.
Wilson/

J.
Miller/
A.
Ertman
None
PP#
8F2119/
FAP#
4H5683
Hexazinone
(107201)
on
Sugarcane
Reregistration
Case
No.
0266.
Clarification
of
CB
12796,
DP
Barcode
D196510.
Agency
Memo
Citations
for
Hexazinone
(continued).

Date
DP
Barcode
CB
No.
From
To
MRID
Nos.
Subject
47
10/
12/
94
D207995
14455
S.
Hummel
E.
Wilson/

J.
Miller/
A.
Ertman
None
PP#
8F2119/
FAP#
4H5683
Hexazinone
(107201)
on
Sugarcane
Amendment
of
9/
21/
94
EPA
Reg.
No.
352­

378
DuPont
Velpar
Herbicide
Reregistration
Case
No.

0266
Amended
Registration,
Deletion
of
Use
in
FL.

11/
30/
94
D209648
14740
S.
Hummel
E.
Wilson/
A.
Ertman
None
PP#
8F2119/
FAP#
4H5683
Hexazinone
(107201)
on
Sugarcane
Amendment
of
11/
2/
94,
Draft
FR
Notice
EPA
Reg.
No.
352­
378
DuPont
Velpar
Herbicide
Reregistration
Case
No.
0266
Justification
for
Disallowing
Use
in
FL.

1/
19/
95
D210574
14899
J.
Abbotts
A.
Ertman
43488901
Hexazinone
(107201),
Reregistration
Case
0266.

Ruminant
Metabolism,
Supplemental
Data.

1/
20/
95
D208605
14591
C.
Eiden
W.
Waldrop
43401901
Hexazinone.
Pineapple
Processing
Study.

3/
14/
95
D211642
15101
J.
Abbotts
A.
Ertman
43524301
Hexazinone
(107201),
Reregistration
Case
0266.

Storage
Stability
of
Metabolite
C
in
Grass,
Interim
Report.

9/
25/
95
D217257
15881
J.
Abbotts
A.
Ertman
43703501
Hexazinone
(107201),
Reregistration
Case
0266.

Cattle
Feeding
Study.

11/
28/
95
D215057
15974
C.
Eiden
W.
Waldrop/

A.
Ertman
None
Hexazinone.
Pineapple
Processing
Study
Follow­
Up:

Response
from
Registrant.

4/
15/
96
None
None
J.
Abbotts
A.
Ertman
None
Hexazinone
(107201),
Reregistration
Case
0266.

Meeting
with
Registrant
DuPont,
4/
9/
96,
on
Progress
Toward
Analytical
Method,
Animal
Commodities.

7/
1/
96
D222455
16791
L.
Cheng
P.
Deschamp
43892401
Hexazinone.
Case
0266.
Confined
Rotational
Crop
Studies
(GLN
165­
1).

9/
27/
96
D228808
17552
J.
Abbotts
M.
Metzger
None
Hexazinone
(107201),
Reregistration
Case
0266.

Registrant
DuPont
Agricultural
Products.
Guideline
860.1900.
Field
Rotational
Crops,
Limited.
Agency
Memo
Citations
for
Hexazinone
(continued).

Date
DP
Barcode
CB
No.
From
To
MRID
Nos.
Subject
48
10/
31/
96
None
None
J.
Abbotts
P.
Deschamp
None
Hexazinone
(107201),
Reregistration
Case
0266.

Meeting
with
Registrant
DuPont,
10/
30/
96,
on
Requirements
for
Limited
Field
Rotational
Trials.

02/
05/
02
D279897
None
S.
Kinard
C.
Olinger
None
Hexazinone.
The
Outcome
of
the
HED
Metabolism
Assessment
Review
Committee.

05/
15/
02
D282685
None
J.
Punzi
D.
Helder
43936501
Hexazinone
(107201),
Reregistration
Case
0266.

Storage
Stability
Study
for
Hexazinone
and
Metabolites
A,
B,
C,
D,
and
E
in
Pasture
and
Range
Grasses.

05/
15/
02
D282682
None
J.
Punzi
D.
Helder
44133501
Hexazinone
(107201),
Reregistration
Case
0266.

Storage
Stability
Study
for
Hexazinone
and
Metabolites
A,
B,
C,
D,
and
E
in
Alfalfa
Forage,
Hay,

and
Seed.

05/
15/
02
D282683
None
J.
Punzi
D.
Helder
44259101
Hexazinone
(107201),
Reregistration
Case
0266.

Enforcement
Method
For
the
Determination
of
Hexazinone
and
its
Metabolites
in
Animal
Tissue
and
Milk
Using
ESI­
LC/
MS
05/
15/
02
D282683
None
J.
Punzi
D.
Helder
44259102
Hexazinone
(107201),
Reregistration
Case
0266.

Independent
Laboratory
Validation
of
Proposed
Enforcement
Method
For
the
Determination
of
Hexazinone
and
its
Metabolites
in
Animal
Tissue
and
Milk
Using
ESI­
LC/
MS
05/
15/
02
D282684
None
J.
Punzi
D.
Helder
45084101
Hexazinone
(107201),
Reregistration
Case
0266.
Field
Accumulation
in
Rotational
Crops
49
STUDY
CITATIONS
00028733
E.
I.
du
Pont
de
Nemours
&
Company
(1976)
Determination
of
Hexazinone
Metabolite
C.
Undated
method.
(Unpublished
study
received
Jan
21,
1980
under
352­
378;
CDL:
099225­
A)

00028866
Holt,
R.
F.;
Baude,
F.
J.;
More,
D.
W.
(1979)
Hexazinone
Livestock
Feeding
Studies:
Milk
and
Meat.
(Unpublished
study
received
Mar
14,
1980
under
352­
378;
submitted
by
E.
I.
du
Pont
de
Nemours
&
Co.,
Wilmington,
Del.;
CDL:
099298­
F)

00038868
Holt,
R.
F.
(1980)
Determination
of
Hexazinone
and
Metabolite
Residues
Using
Nitrogen
Selective
Gas
Chromatography.
Undated
method.
(Unpublished
study
received
Jul
1,
1980
under
352­
378;
submitted
by
E.
I.
du
Pont
de
Nemours
&
Co.,
Wilmington,
Del.;
CDL:
099514­
E)

00038869
Rapisarda,
C.
(1978)
Metabolism
of
14C­
Labeled
Hexazinone
in
the
Goat.
(Unpublished
study
received
Jul
1,
1980
under
352­
378;
submitted
by
E.
I.
du
Pont
de
Nemours
&
Co.,
Wilmington,
Del.;
CDL:
099514­
F)

00078047
Rhodes,
R.
C.
(1975)
Letter
sent
to
324
File
dated
Aug
12,
1975:
Uptake
and
metabolism
studies
with
14
C­
DPX­
3674
on
sugarcane
in
the
greenhouse.
(Unpublished
study
received
Mar
22,
1976
under
352­
EX­
91;
submitted
by
E.
I.
du
Pont
de
Nemours
&
Co.,
Wilmington,
Del.;
CDL:
095980­
E)

00101574
Interregional
Research
Project
No.
4
(1982)
Residue
Studies
of
Hexazinone
on
Blueberries
and
Methomyl
on
Sugarcane.
(Compilation;
unpublished
study
received
May
17,
1982
under
2E2687;
CDL:
070861­
A)

00104843
Study
ADP
record
deleted.
Study
is
a
duplicate
of
MRID
38869
00104845
E.
I.
du
Pont
de
Nemours
&
Co.,
Inc.
(1979)
Results
of
Tests
on
the
Amount
of
Residue
Remaining
on
Treated
Crop:
Hexazinone
plus
Metabolites.
(Compilation;
unpublished
study
received
May
24,
1979
under
9G2214;
CDL:
098309­
C)

00104846
Rapisarda,
C.
Metabolism
of
14C­
labeled
Hexazinone
in
Alfalfa:
Doc.
No.
HME
12­
79.
(Unpublished
study
received
May
24,
1979
under
9G2214;
submitted
by
E.
I.
du
Pont
de
Nemours
&
Co.,
Inc.,
Wilmington,
DE;
CDL:
098309­
D)

00114039
E.
I.
du
Pont
de
Nemours
&
Co.,
Inc.
(1978)
Investigations
Made
with
Respect
to
Residue
Chemistry:
[Velpar].
(Compilation;
unpublished
50
study
received
Aug
29,
1978
under
352­
378;
CDL:
097321­
E)

00118050
E.
I.
du
Pont
de
Nemours
&
Co.,
Inc.
(1982)
Data
Supporting
Amendment
of
Velpar
Weed
Killer
Use
on
Alfalfa
and
Adding
Velpar
L
Weed
Killer
Use
on
Alfalfa.
(Unpublished
study
received
Nov
15,
1982
under
352­
378;
CDL:
248831­
A)

00126127
E.
I.
du
Pont
de
Nemours
&
Co.,
Inc.
(1983)
Results
of
Tests
on
the
Amount
of
Residue
Remaining
on
Treated
Crop:
Hexazinone.
(Compilation;
unpublished
study
received
Feb
28,
1983
under
352­
378;
CDL:
071438­
A)

00138226
E.
I.
du
Pont
de
Nemours
&
Co.,
Inc.
(1984)
Residue
Chemistry
Data
Supporting
the
Use
of
Velpar
L
Weed
Killer
for
Control
of
Undesirable
Woody
Plants
in
Rangeland.
(Compilation;
unpublished
study
received
Apr
4,
1984
under
352­
392;
CDL:
252954­
A)

00140161
Magnitude
of
the
Residue
in
Animals
41008401
Rapisarda,
C.
(1980)
Rotational
Crop
Studies
with
14C­
LabeledHexazinone
Laboratory
Project
AMR­
26­
80.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
&
Co.
25
p.

41524801
Hawkins,
W.;
Elsom,
L.;
Gray,
S.,
et
al.
(1990)
The
Metabolism
of
Carbon
14­
Hexazinone
in
Laying
Hens:
Lab
Project
Number:
203/
90454:
AMR­
1517­
89.
Unpublished
study
prepared
by
Huntingdon
Research
Centre,
Ltd.
80
p.

41572101
Fomenko,
J.
(1990)
Testing
of
DPX­
A3674
through
FDA
Multi­
Residue
Protocols
A­
E:
Lab
Project
Number:
AMR­
1489­
89:
DP001­
01.
Unpublished
study
prepared
by
Spectralytix.
67
p.

41572102
Fomenko,
J.
(1990)
Testing
of
IN­
T3937
through
FDA
Multi­
Residue
Protocols
A­
E:
Lab
Project
Number:
AMR­
1490­
89:
DP001­
02.
Unpublished
study
prepared
by
Sprectalytix
Inc.
57
p.

41572103
Fomenko,
J.
(1990)
Testing
of
IN­
A3928
through
FDA
Multi­
Residue
Protocols
A­
E:
Lab
Project
Number:
AMR­
1491­
89:
DP001­
03.
Unpublished
study
prepared
by
Spectralytix,
Inc.
67
p.

41572104
Fomenko,
J.
(1990)
Testing
of
IN­
T3935
through
FDA
Multi­
Residue
Protocols
A­
E:
Lab
Project
Number:
AMR­
1492­
89:
DP001­
04.
Unpublished
study
prepared
by
Spectralytix
Inc.
57
p.
51
41572105
Fomenko,
J.
(1990)
Testing
of
IN­
B2838
through
FDA
Multi­
Residue
Protocols
A­
E:
Lab
Project
Number:
AMR­
1493­
89:
DP001­
05.
Unpublished
study
prepared
by
Spectralytix
Inc.
67
p.

41572106
Fomenko,
J.
(1990)
Testing
of
IN­
B3936
through
FDA
Multi­
Residue
Protocols
A­
E:
Lab
Project
Number:
AMR­
1494­
89:
DP001­
06.
Unpublished
study
prepared
by
Spectralytix
Inc.
67
p.

41898301
Bollin,
E.
(1991)
Magnitude
of
Residues
of
Velpar
Herbicide
in
Pasture
and
Range
Grasses:
Lab
Project
Number:
AMR­
1429­
89.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
and
Co.
241
p.

41964101
Bollin,
E.;
Hay,
R.
(1991)
Magnitude
of
Residues
of
Velpar
and
Velpar
L
Herbicide
in
Lowbush
Blueberries:
Lab
Project
Number:
AMR­
1431­
89.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
and
Co.
46
p.

41964102
Bollin,
E.;
Hay,
R.
(1991)
Magnitude
of
Residues
of
Velpar
and
Velpar
L
Herbicide
in
Highbush
Blueberries:
Lab
Project
Number:
AMR­
1434­
89.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
and
Co.
46
p.

42187901
Hawkins,
D.;
Elsom,
L.;
Dighton,
M.;
et
al.
(1992)
The
Metabolism
of
Carbon
14­
Hexazinone
in
the
Goat:
Lab
Project
Number:
245/
91718:
AMR­
1906­
90.
Unpublished
study
prepared
by
Huntingdon
Research
Centre
Ltd.
105
p.

42219301
Hawkins,
D.;
Elsom,
L.;
Dighton,
M.;
(1992)
The
Metabolism
of
Carbon
14­
Hexazinone
in
Laying
Hens:
The
Freezer
Storage
Stability
of
Tissues,
Eggs
and
Excreta
from
Laying
Hens
Dosed
with
Carbon
14­
Hexazinone:
Supplement
to:
Lab
Project
Number:
HRC/
203/
90454;
AMR­
1517­
89.
Unpublished
study
prepared
by
Huntingdon
Research
Centre
Ltd.
33
p.

42248901
Hawkins,
D.;
Elsom,
L.;
Dighton,
M.
(1992)
The
Metabolism
of
Carbon­
14
Hexazinone
in
the
Goat,
Supplement
1:
The
Freezer
Storage
Stability
of
Carbon­
14
Residues
in
Tissues
and
Milk
from
a
Lactating
Goat
Dosed
with
Carbon
14
Hexazinone:
Lab
Project
Number:
HRC/
DPT
245/
91718:
AMR­
1906­
90.
Unpublished
study
prepared
by
Huntingdon
Research
Centre.
36
p.

42276001
Powley,
C.;
Tomic,
D.
(1992)
Magnitude
of
the
Residue
of
Velpar
Herbicide
in
Sugarcane
and
its
Processed
Fractions:
Lab
Project
Number:
AMR
1473­
89:
35­
5300:
14­
5308.
Unpublished
study
prepared
by
Dupont
and
Hawaiian
Sugar
Planters
Association.
151
p.
52
42322701
Powley,
C.;
Tomic,
D.
(1992)
Magnitude
of
Residues
of
Velpar
Herbicide
in
Sugarcane:
Lab
Project
Number:
AMR
1472­
89:
14­
5308.
Unpublished
study
prepared
by
E.
I.
DuPont
de
Nemours
and
Co.
and
Hawaiian
Sugar
Planters
Assoc.
180
p.

42417901
Mulcahey,
L.
(1992)
Magnitude
of
the
Residues
of
Velpar
Herbicide
in
Sugarcane
and
its
Processed
Fractions
(Supplemental):
Lab
Project
Number:
AMR
1473­
89
(SUPP
1):
35­
5300:
14­
5308.
Unpublished
study
prepared
by
E.
I.
DuPont
de
Nemours
and
Co.
in
coop
with
the
Hawaiian
Sugar
Planters'
Assoc.
40
p.

42418001
Klemens,
A.;
Tomic,
D.
(1992)
Freezer
Storage
Stability
of
Hexazinone
and
Metabolites
in
Pasture
and
Range
Grasses.
Lab
Project
Number:
AMR
1582­
90:
A022.005.
Unpublished
study
prepared
by
E.
I.
DuPont
de
Nemours
and
Co.
in
coop
with
Huntingdon
Analytical
Services.
54
p.

42419101
Mulcahey,
L.
(1992)
Magnitude
of
Residues
of
Velpar
Herbicide
in
Pasture
and
Range
Grasses:
A
Supplement:
Lab
Project
Number:
AMR
1429­
89:
1022.004:
91012.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
and
Co.
89
p.

42423001
Klemens,
A.;
Devine,
P.
(1992)
Freezer
Storage
Stability
of
Velpar
Herbicide
and
Metabolites
on
Blueberries:
Lab
Project
Number:
AMR
1911­
90.
Unpublished
study
prepared
by
E.
I.
DuPont
de
Nemours
and
Co.
47
p.

42492101
Powley,
C.;
Tomic,
D.
(1992)
Magnitude
of
Residues
of
Velpar
Herbicide
in
the
Processed
Fractions
of
Pineapples:
Lab
Project
Number:
AMR
1471­
89:
MP
90­
03.01:
36­
5309.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
&
Co.
114
p.

42535601
Powley,
C.;
Tomic,
D.
(1992)
Magnitude
of
Residues
of
Velpar
Herbicide
in
Pineapples:
Lab
Project
Number:
AMR
1570­
89:
36­
5309.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
and
Co.;
Hawaiian
Sugar
Planters'
Association.
81
p.

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Hawkins,
D.
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Elsom,
L.
F.;
Gray,
S.
P.,
et
al.
(1990)
The
Metabolism
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14C­
Hexazinone
in
Laying
Hens,
Supplement
2.
Du
Pont
AMR­
1517­
89,
Supplement
2.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
&
Co.,
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42824001
Rapisarda,
C.
(1993)
Rotational
Crop
Studies
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(carbon
14)­
Labeled
Hexazinone:
Supplement
No.
1:
Lab
Project
Number:
AMR
26­
80.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
and
Co.
11
p.
53
42867501
Klemens,
A.;
Devine,
P.
(1993)
Freezer
Storage
Stability
of
Hexazinone
and
Metabolites
in
Pasture
and
Range
Grasses:
Supplement
No.
1:
Lab
Project
Number:
AMR
1582­
90:
A022.005.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
and
Co.
and
Huntingdon
Analytical
Services.
72
p.

42987201
Powley,
C.;
Zhou,
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DeBernard,
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(1993)
Method
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the
Determination
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Hexazinone
in
Sugarcane
and
Processed
Fractions:
Lab
Project
Number:
AMR
2654­
93.
Unpublished
study
prepared
by
DuPont
Agricultural
Products.
30
p.

43025401
Bruns,
G.
(1993)
Independent
Laboratory
Validation
of
the
Analytical
Enforcement
Method
for
the
Determination
of
Hexazinone
in
Sugarcane,
Molasses,
and
Bagasse
by
Gas
Chromatography:
Lab
Project
Number:
DUP69/
REP:
AMR/
2804/
93.
Unpublished
study
prepared
by
Enviro­
Test
Labs.
34
p.

43074201
Hawkins,
D.;
Elsom,
L.;
Dighton,
M.;
et
al.
(1993)
A
Comparison
of
(carbon
14)­
Hexazinone
Metabolites
in
Hen
Tissues
and
Eggs
and
Goat
Tissues
and
Milk
Synthesised
Metabolite
Standards:
Lab
Project
Number:
294/
932331:
DPT/
294/
932331:
HRC/
DPT/
294/
932331.
Unpublished
study
prepared
by
Huntingdon
Research
Centre
Ltd.
110
p.

43074401
Djanegara,
T.;
Devine,
P.
(1993)
Magnitude
of
Residues
of
Hexazinone
in
Alfalfa
Forage,
Hay,
and
Seed
Grown
in
the
Western
United
States
Following
Application
of
Velpar
Herbicide:
Lab
Project
Number:
AMR
1924­
91:
92013.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
&
Co.
and
Spectralytix,
Inc.
330
p.

43074402
Djanegara,
T.;
Devine,
P.
(1993)
Magnitude
of
Residues
of
Hexazinone
in
Alfalfa
Forage
and
Hay
Grown
in
the
Eastern
United
States
Following
Application
of
Velpar
Herbicide:
Lab
Project
Number:
AMR
2010­
91:
92025.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
&
Co.
and
Spectralytix,
Inc.
316
p.

43401901
Powley,
C.;
Devine,
P.
(1994)
Magnitude
of
Residues
of
Velpar
Herbicide
in
the
Processed
Fractions
of
Pineapples:
Supplement
No.
1:
Lab
Project
Number:
MP/
90/
03/
01:
5309:
AMR/
1471/
89.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
and
Co.;
Maui
Pineapple
Co.,
Ltd.;
and
Hawaiian
Sugar
Planters'
Association.
74
p.

43488901
Hawkins,
D.;
Elsom,
L.;
Dighton,
M.
et
al.
(1994)
A
Comparison
of
(carbon
14)­
Hexazinone
Metabolites
in
Hen
Tissues
and
Eggs
and
Goat
Tissues
and
Milk
With
Synthesised
Metabolite
Standards:
Supplement
1:
54
Examples
of
Calculations
and
Chromatographic
Raw
Data:
Lab
Project
Number:
DPT
294/
932331:
AMR
2633­
93.
Unpublished
study
prepared
by
Huntingdon
Research
Centre,
Ltd.
94
p.

43524301
Mulcahey,
L.;
Orescan,
D.
(1995)
Freezer
Storage
Stability
of
Hexazinone
and
Metabolites
in
Pasture
and
Range
Grasses:
Supplement
No.
2:
Lab
Project
Number:
AMR
1582­
90:
HAS­
A022.005:
SPX­
92020.
Unpublished
study
prepared
by
DuPont
Agricultural
Products;
Huntingdon
Analytical
Services;
and
Spectralytix.
76
p.

43703501
Mulcahey,
L.;
George,
S.;
Brisbin,
J.
et
al.
(1995)
Magnitude
of
Residues
of
Hexazinone
in
Edible
Tissues
and
Milk
of
Lactating
Dairy
Cows:
Lab
Project
Number:
.

43892401
Djanegara,
T.;
Reardon­
Green,
L.
(1996)
Confined
Accumulation
Study
of
(4­
Carbonyl­(
carbon
14))­
Hexazinone
(DPX­
A3674)
in
Rotational
Crops:
Lab
Project
Number:
AMR
2800­
93.
Unpublished
study
prepared
by
DuPont
Agricultural
Products.
115
p.
Relatesto
letter
L0000071.

43936501
Mulcahey,
L.
(1996)
Freezer
Storage
Stability
of
Hexazinone
and
Metabolites
in
Pasture
and
Range
Grasses:
Supplement
No.
3
(Final):
Lab
Project
Number:
AMR
1582­
90:
HAS­
A022.005:
SPX­
92020.
Unpublished
study
prepared
by
DuPont
Agricultural
Products;
Huntingdon
Analytical
Services
and
Environmental
Analytical
Services.
63
p.

44133501
Bollin,
E.
(1996)
Magnitude
of
the
Residue
of
Hexazinone
in
Alfalfa
Forage,
Hay,
and
Seed
Grown
in
the
Western
United
States
Following
Application
of
Velpar
Herbicide:
Supplement
No.
1
to
MRID
43074401:
Lab
Project
Number:
AMR
1924­
91:
92013.
Unpublished
study
prepared
by
DuPont
Agricultural
Products
and
Environmental
Analytical
Services,
Inc.
40
p.

44259101
Brill,
F.;
Bramble,
F.;
Norwood,
G.;
et
al.
(1997)
Enforcement
Analytical
Method
for
the
Determination
of
Hexazinone
and
Metabolites
of
Interest
in
Animal
Tissues
and
Milk
Using
ESI­
LC/
MS:
Lab
Project
Number:
AMR
3783­
96.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
and
Co.
100
p.

44259102
Xu,
B.
(1997)
Independent
Laboratory
Validation
of
a
Proposed
Enforcement
Analytical
Method
for
the
Determination
of
Hexazinone
and
Metabolites
of
Interest
in
Animal
Tissue
and
Milk
Using
ESI­
LC/
MS:
Lab
Project
Number:
AMR
4366­
97:
008­
07.
Unpublished
study
prepared
by
Centre
Analytical
Laboratories,
Inc.
117
p.
55
45084101
Brill,
F.
(2000)
Magnitude
of
Residues
of
Hexazinone
in
Rotational
Crops
Following
Application
of
Velpar
Herbicide
at
Maximum
Label
Rates
to
Alfalfa:
Lab
Project
Number:
AMR
4336­
97.
Unpublished
study
prepared
by
E.
I.
du
Pont
de
Nemours
and
Co.
253
p.