Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
EPA
Registration
Division
Contact
:
Mr.
J.
A.
Tompkins,
703­
305­
5697
1.
E.
I.
du
Pont
de
Nemours
and
Company
PP
Nos.
(
to
be
assigned)

EPA
has
received
pesticide
petitions
(
PP
Nos.
to
be
assigned)
from
E.
I.
du
Pont
de
Nemours
and
Company,
Crop
Protection
Products,
Laurel
Run
Plaza,
P.
O.
Box
80038,
Wilmington,
DE
19880­
0038,
and
the
Interregional
Research
Project
No.
4
(
IR­
4),
681
U.
S.
Highway
#
1
South,
North
Brunswick,
New
Jersey
08902­
3390,
proposing
pursuant
to
section
408
(
d)
of
the
Federal
Food,
Drug,
and
Cosmetic
Act,
21
U.
S.
C.
346a
(
d),
to
amend
40
CFR
Part
180.451
by
establishing
a
tolerance
for
residues
of
the
herbicide,
tribenuron
methyl
(
methyl
2­[[[[(
4­
methoxy­
6­
methyl­
1,3,5­
triazin­
2­
yl)
methylamino]
carbonyl]
amino]
sulfonyl]
benzoate)
in
or
on
the
following
raw
agricultural
commodities:
Sunflowers
at
0.05
ppm;
Rice
grain
and
straw
at
0.05
ppm;
Field
corn
forage,
stover,
and
grain
at
0.05
ppm;
Grain
sorghum
forage,
stover,
and
grain
at
0.05
ppm;
and
Soybean
seed
at
0.05
ppm.
EPA
has
determined
that
the
petition
contains
data
or
information
regarding
the
elements
set
forth
in
section
408
(
d)
(
2)
of
the
FFDCA;
however,
EPA
has
not
fully
evaluated
the
sufficiency
of
the
submitted
data
at
this
time
or
whether
the
data
supports
granting
of
the
petition.
Additional
data
may
be
needed
before
EPA
rules
on
the
petition.

A.
Residue
Chemistry
1.
Plant
Metabolism
The
qualitative
nature
of
the
residues
of
tribenuron
methyl
is
adequately
understood.

Tribenuron
methyl
is
rapidly
metabolized
in
wheat
plants
with
a
half­
life
of
less
than
4
days.
A
major
metabolic
reaction
was
N­
demethylation
of
tribenuron
methyl
to
form
metsulfuron
methyl.
Metsulfuron
methyl
was
further
metabolized,
primarily
through
rapid
hydroxylation
of
the
phenyl
ring,
followed
by
conjugation
with
glucose.
Hydrolysis
of
the
sulfonylurea
bridge
of
tribenuron
methyl
to
release
sulfonamide
and
triazine
amine
was
also
observed.
The
sulfonamide
may
be
further
metabolized
to
hydroxylated
sulfonamide
or
cyclized
to
saccharin.
The
presence
of
alphahydroxy
triazine
amine,
N­
demethyl
triazine
amine,
and
O­
demethyl
N­
demethyl
triazine
amine
demonstrated
that
the
released
triazine
moiety
of
tribenuron
methyl
was
also
extensively
degraded
in
wheat.
Metabolism
studies
were
conducted
with
radioactive
[
14C]­
tribenuron
methyl
on
wheat
under
field
conditions.
Wheat
plants
at
the
tillering
stage
were
treated
with
72­
75
g
active
ingredient
(
ai)/
ha
of
[
14C]­
phenyl
and
[
14C]­
triazine
labeled
tribenuron
methyl.
Samples
were
harvested
0,
4,
8,
14,
21,
28,
and
63
days
after
treatment.
Total
[
14C]
residue
levels
in
the
foliage
declined
rapidly
from
5.5
ppm
at
time
of
application
to
0.55
ppm
in
the
mature
straw
and
0.05
ppm
in
the
grain
([
14C]­
phenyl),
and
from
4.2
ppm
to
0.37
ppm
in
the
mature
straw
and
0.01
ppm
in
the
grain
([
14C]­
triazine).
Analysis
of
the
wheat
foliage
and
straw
extracts
by
HPLC
and
TLC
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
revealed
that
tribenuron
methyl
was
rapidly
and
extensively
metabolized.
Metabolites
were
identified
based
on
chromatography
with
authentic
standards.
The
major
metabolites
were
the
glucose
conjugate
of
hydroxylated
metsulfuron
methyl,
hydroxylated
saccharin,
the
glucose
conjugate
of
hydroxylated
saccharin,
saccharin,
triazine
amine,
O­
demethyl
triazine
amine,
and
Ohydroxy
triazine
amine.

A
metabolism
study
was
conducted
with
[
14C]
Tribenuron
methyl
on
ALS­
Tolerant
Canola.
[
14C]
Tribenuron
methyl
was
applied
at
25
g
ai/
ha
as
a
topical
spray
treatment
at
the
2
true
leaf
stage
to
bolting.
Whole
canola
plants
were
harvested
at
0,
2,
and
35
days
after
treatment,
and
at
maturity
(
78
days
after
treatment).
Total
reactive
residue
(
TRR)
in
canola
foliage,
when
expressed
as
tribenuron
methyl
equivalents,
declined
from,
on
average,
0.26
ppm
at
day
0
to
0.04
ppm
at
day
35.
TRR
in
immature
35­
day
canola
seed
pods
was
not
higher
than
0.04
ppm,
and
was
0.02
ppm
in
78­
day
seed
samples.
[
14C]
Tribenuron
methyl
accounted
for
greater
than
81%
of
the
radioactive
residue
in
the
0
and
2
day
foliage
samples.
Other
minor
components
were
polar
metabolites
or
conjugates,
each
less
than
10%
of
the
TRR.
No
single
component
in
the
polar
metabolites
exceeded
0.01
ppm.
In
the
35­
day
foliage
samples,
[
14C]
tribenuron
methyl
accounted
for
only
about
11­
25.5%
of
the
TRR,
which
is
less
than
0.01
ppm.
The
average
half
life
for
[
14C]
tribenuron
methyl
was
15
days.
Several
metabolic
processes
in
the
foliage
are
involved.
They
include
a
hydrolytic
cleavage
of
tribenuron
methyl
as
well
as
N­
demethylation
of
tribenuron
methyl.
Other
demethylation
and
hydroxylation
processes
continued
up
to
final
harvest.
The
results
of
the
study
suggest
that
the
tribenuron
methyl
metabolic
process
in
canola
follows
a
typical
plant
metabolism
pattern,
and
no
accumulation
of
tribenuron
methyl
is
anticipated
in
canola
when
it
is
used
in
accordance
with
the
proposed
labels.

A
metabolism
study
was
conducted
to
determine
the
nature
and
magnitude
of
the
residues
of
tribenuron
methyl
in
cotton
plants
after
exposure
to
[
2­
14C]
tribenuron
methyl.
Soil
treatments
were
applied
at
0.3
oz
ai/
acre
as
a
direct
spray
in
an
aqueous
suspension
containing
inert
dryflowable
formulation
ingredients.
The
application
was
made
immediately
after
planting
cotton
to
provide
the
data
for
the
shortest
anticipated
time
between
application
and
planting.
No
terminal
residues
at
or
above
0.01
ppm
were
observed
in
any
triazine­
label
treated
fractions
of
mature
cotton
after
treatment
with
tribenuron
methyl.
No
detectable
residues
were
found
in
the
undelinted
seed,
and
very
low
residues
(
0.028
ppm)
were
observed
in
the
gin
trash
after
treatment.
Tribenuron
methyl
and
its
known
metabolites
are
not
expected
to
be
present
in
the
terminal
residues
in
gin
trash
or
undelinted
seed,
when
applied
according
to
the
proposed
label.

A
confined
crop
rotation
study
with
[
14C]­
phenyl
tribenuron
methyl
was
conducted
using
red
beets,
cabbage,
sorghum,
soybeans
and
wheat
planted
in
pots
of
sandy
loam
soil
30
and
120
days
after
a
single
application
of
[
14C]­
phenyl­
labeled
tribenuron
methyl.
For
the
30­
day
aging
period,
samples
from
both
treated
and
control
crops
were
taken
at
28,
49,
and
67
days
after
planting
with
additional
samples
taken
from
the
sorghum
and
soybeans
plantings
at
90
and
115
days.
At
maturity,
all
remaining
plants
were
harvested
and
subdivided
into
edible
and
nonedible
portions.
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
Harvest
dates,
expressed
as
days
after
planting,
were:
90
days
(
cabbage),
115
days
(
beets
and
wheat),
and
168
days
(
sorghum
and
soybeans).
Samples
from
all
crops
from
the
120­
day
aging
study
were
taken
at
28,
48,
69,
and
90
days
(
maturity
for
wheat,
beets
and
cabbage)
and
120
days
and
169
days
(
maturity
for
sorghum
and
soybeans).
Tribenuron
methyl
dissipated
rapidly
in
the
soil
with
none
of
the
intact
material
detected
after
the
30­
day
aging
period.
The
major
radiolabeled
residue
extracted
from
the
soil
was
saccharin,
which
remained
in
the
soil
at
very
low
levels
throughout
the
study.
Some
accumulation
of
total
radioactive
residues
was
apparent
in
the
mature
wheat,
soybean,
and
sorghum
foliage
due
to
the
dehydrated
nature
of
samples
harvested.
The
major
residue
in
the
plants
was
identified
as
saccharin.

A
confined
crop
rotation
study
with
[
14C]­
triazine
tribenuron
methyl
was
conducted
using
sorghum,
red
beets,
and
cabbage.
Sandy
loam
soil
was
treated
at
32
g
ai/
ha
with
[
14C]­
phenyl
tribenuron
methyl
in
the
greenhouse.
Rotational
crops
were
sown
30
and
120
days
posttreatment
Tribenuron
methyl
degraded
rapidly
in
the
soil
with
no
detectable
intact
material
present
30
days
post­
treatment.
The
major
radiolabeled
metabolite
was
the
triazine
amine.
No
significant
accumulation
(
i.
e.,
less
than
0.01
ppm)
of
radiolabeled
materials
from
the
soil
were
observed
in
the
mature
crops
of
cabbage
foliage.
Some
accumulation
of
the
radioactivity
was
observed
in
the
mature
beet
foliage
in
the
30­
day
study
(
0.029
ppm)
and
the
120­
day
study
(
0.011
ppm).
Major
metabolites
were
N­
demethyl
triazine
amine
and
O­
hydroxy
triazine
amine.
Accumulation
of
radioactivity
was
observed
in
the
mature
sorghum
straw
due
to
the
dehydrated
nature
of
this
plant
tissue
at
harvest.
Levels
of
radiolabeled
materials
detected
were
0.108
and
0.057
ppm
in
the
30­
day
and
120­
day
studies,
respectively.
The
major
metabolites
were
highly
polar
materials.
Tribenuron
methyl
rapidly
decomposes
in
soil
to
the
triazine
amine,
which
is
then
degraded,
not
accumulated,
in
plants.

Based
on
the
absence
of
quantifiable
residues
in
food
commodities
(
barley
and
oat
grain),
and
on
the
expected
low
residue
levels
of
individual
substances
in
feed
items
(
straw)
under
normal
conditions,
and
the
Residue
Chemistry
Guidelines
(
OPPTS
860­
1300,
D,
ii)
which
state
that
one
metabolism
study
will
be
required
for
each
of
the
crop
groups
defined
in
CFR
40
180.34
(
f)
except
for
herbs
and
spices,
a
plant
metabolism
study
in
barley
and
oat
was
not
required.
Additionally,
based
on
the
results
of
three
metabolism
studies
on
dissimilar
crops
(
wheat,
canola
and
cotton)
having
similar
metabolic
routes,
additional
metabolism
studies
for
sunflowers,
rice,
field
corn,
soybeans,
and
grain
sorghum
are
not
required.

2.
Analytical
Methods
Various
analytical
methods
are
available
for
the
determination
of
residues
of
tribenuron
methyl
in
barley
grain,
wheat
grain,
wheat
straw,
and
wheat
forage
samples.
One
method
uses
normal
phase
liquid
chromatography
and
a
photoconductivity
detector;
and
is
based
on
extraction
of
tribenuron
methyl
from
crops
with
acetonitrile,
and
cleanup
on
a
silica
cartridge.
Recoveries
for
grain,
straw
and
green
forage
samples
fortified
between
0.01
and
0.10
ppm
averaged
88%
with
a
standard
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
deviation
of
14%.
The
lower
level
of
quantitation
for
grain
and
green
forage
is
0.01
ppm
and
for
straw
0.02
ppm.
This
method
was
updated
to
a
HPLC
method
with
UV
detection.
The
method
provides
a
means
to
quantitate
tribenuron
methyl
in
these
matrices
at
levels
as
low
as
0.05
ppm,
based
on
a
5­
gram
sample,
using
column
and
eluent
switching.
More
recently,
this
method
was
further
updated
and
provides
for
analysis
of
wheat
grain,
straw,
and
forage
by
HPLC
column
switching
and
UV
detection.
The
limit
of
quantitation
(
LOQ)
for
this
updated
method
is
0.01
ppm
for
wheat
grain
and
wheat
forage,
and
0.05
ppm
for
wheat
hay.

The
analyses
of
sunflower
samples
were
conducted
with
this
further
updated
method.
The
LOQ
for
the
analysis
of
sunflower
seed
was
0.05
ppm
based
on
a
5­
gram
sample.
This
method
was
validated
at
0.05
and
0.5
ppm,
with
an
average
recovery
of
70
%
(+/­
6%)
and
70%
(+/­
3%),
respectively.

Methods
have
been
developed
for
the
analysis
of
Tribenuron
methyl
in
other
crops.
Residues
of
tribenuron
methyl
at
levels
of
0.02
ppm
or
above
in
grass
seed,
straw,
and
seed
screenings
are
quantified
using
gel
permeation
chromatography
and
solid­
phase
extraction.
Purified
column
eluent
is
taken
to
dryness,
dissolved
in
ethyl
acetate,
and
analyzed
by
capillary
gas
chromatography
using
a
mass
spectral
detector.
In
fortification
recovery
trials,
an
average
recovery
of
87.6
%
with
a
standard
deviation
of
21
%
was
obtained
for
eighteen
grass
seed
samples
over
a
fortification
range
of
0.02
to
0.06
ppm.
Tribenuron
methyl
residues
in
canola
and
flax
samples
were
determined
by
an
analytical
method,
based
on
the
use
of
liquid
chromatography
with
eluent
and
column
switching
with
UV
detection
at
258
nm,
at
levels
as
low
as
0.02
ppm
(
limit
of
quantitation)
using
a
5
gram
sample.
Residues
in
cotton
seed
and
cotton
gin
trash
were
determined
based
on
the
use
of
column­
switching
liquid
chromatography
with
detection
via
positive
ion
electrospray
mass
spectroscopy.
The
limit
of
quantitation
was
determined
to
be
0.02
ppm
and
the
limit
of
detection
was
estimated
to
be
0.006
ppm,
based
on
a
5
gram
sample.

Residues
in
rice
grain
and
straw,
corn
forage
and
stover,
and
grain
sorghum
forage
and
stover
were
determined
with
an
analytical
method
utilizing
sample
extraction
by
homogenization
in
a
potassium
phosphate
buffer
solution.
The
extracts
were
cleaned­
up
and
concentrated
by
solidphase
extraction.
Analysis
was
performed
by
reversed­
phase
HPLC
and
quantitatively
analyzed
by
tandem
mass
spectrometric
detection.
The
target
limit
of
quantitation
(
LOQ)
was
0.05
ppm
in
these
commodities.

Thifensulfuron
methyl
residues
in
field
corn
grain,
grain
sorghum
grain,
and
soybean
seed
were
determined
by
an
analytical
method
utilizing
LC/
MS/
MS
analysis.
The
analytes
were
resolved
by
HPLC
chromatography
and
quantitatively
analyzed
by
tandem
mass
spectrometric
detection.
The
LOQ
was
0.05
ppm
in
these
commodities.

3.
Magnitude
of
Residue
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
a.
Wheat
and
Barley,
Grain
and
Straw
A
study
was
conducted
to
determine
the
extent
of
residues
of
tribenuron
methyl
in
wheat
when
applied
at
the
maximum
use
rate
(
0.25
oz
ai/
A)
40
days
before
maturity.
Samples
of
mature
wheat
grain
and
straw
were
taken
from
treated
and
control
plots
at
preharvest
intervals
ranging
from
25
to
40
days
after
the
test
substance
was
applied.
A
two­
step
HPLC
method
was
used
to
determine
tribenuron
methyl
at
levels
as
low
as
0.0075
ppm
in
wheat
grain
based
on
a
20
gram
sample,
and
0.014
ppm
in
wheat
straw
based
on
a
10
gram
sample.
No
grain
or
straw
samples
showed
quantifiable
residues
of
tribenuron
methyl.

A
study
was
conducted
to
determine
the
extent
of
residues
of
tribenuron
methyl
in
barley
when
applied
at
the
maximum
use
rate
(
0.25
oz
ai/
A)
40
days
before
maturity.
Samples
of
mature
barley
grain
and
straw
were
taken
from
each
plot
at
preharvest
intervals
ranging
from
24
to
43
days
after
the
test
substance
was
applied.
A
two­
step
HPLC
method
was
used
to
determine
tribenuron
methyl
at
levels
as
low
as
0.0066
ppm
in
barley
grain
based
on
a
20
gram
sample,
and
0.013
ppm
in
barley
straw
based
on
a
10
gram
sample.
One
of
the
grain
samples
showed
a
detectable
residue
(
0.0064
ppm)
of
tribenuron
methyl,
which
is
below
the
established
grain
tolerance
of
0.05
ppm.
A
straw
sample
from
one
of
the
sites
contained
tribenuron
methyl
at
0.034
ppm,
which
is
below
the
established
straw
tolerance
of
0.10
ppm.
The
remaining
grain
and
straw
samples
showed
no
detectable
or
quantifiable
residues
of
tribenuron
methyl.

The
results
of
the
analyses
of
grain
and
straw
from
wheat
and
barley
show
that
no
residues
were
found
in
either
grain
or
straw
from
plants
treated
at
or
below
the
maximum
recommended
application
rate
of
0.25
oz.
ai/
acre,
with
a
0.02
­
0.05
ppm
LOQ.
The
preharvest
intervals
ranged
from
42­
140
days.
A
small
percentage
of
plants
treated
at
higher
rates
showed
some
residues
in
straw.

b.
Grass,
Forage
and
Hay
Established
plots
of
bluegrass,
tall
fescue,
and
perennial
ryegrass
grown
for
production
of
grass
seed
were
each
treated
with
0.25
oz
ai/
A
and
0.50
oz
ai/
A
of
tribenuron
methyl.
Sampling
preharvest
intervals
ranged
from
56
to
85
days.
Reliable
detected
residues
of
tribenuron
methyl
(
0.016
ppm
or
above)
were
not
found
in
any
crop
fraction
from
any
test
site,
with
one
exception
for
a
screenings
waste
sample
with
a
residue
level
of
0.004
ppm
for
the
0.25
oz
ai/
A
treatment,
and
0.006
ppm
for
the
0.50
oz
ai/
A
treatment.
An
attempt
to
reconfirm
this
result
by
reextracting
a
second
screening
waste
sample
failed
to
confirm
the
presence
of
these
tribenuron
methyl
residues.

c.
Oat,
Grain
and
Straw
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
A
study
was
conducted
to
determine
the
extent
of
residues
of
tribenuron
methyl
in
oats
when
applied
at
one
and
two
times
the
maximum
use
rate,
approximately
40
days
before
harvest.
Samples
of
mature
oat
grain
and
straw
were
taken
from
both
treated
and
control
plots
at
preharvest
intervals
ranging
from
39
to
57
days
after
the
application
of
the
test
substance.
A
twostep
HPLC
method
was
used
to
detect
tribenuron
methyl
residues
in
oat
grain
at
levels
as
low
as
0.0055
ppm
based
on
a
20
gram
sample,
and
in
oat
straw
at
levels
as
low
as
0.018
ppm
based
on
a
10
gram
sample.
Residues
of
tribenuron
methyl
in
oat
grain
from
oats
treated
at
1x
and
2x
rates
were
below
the
LOQ
of
0.013
ppm
and
0.01
ppm,
respectively.
The
residues
of
tribenuron
methyl
in
oat
straw
were
below
the
LOQ
of
0.018
ppm
and
0.04
ppm,
respectively
­
and
also
below
reported
detection
level
of
0.009
ppm
and
0.018
ppm,
respectively,
in
oat
straw
from
oats
treated
at
1x
and
2x
rates.

d.
Canola
and
Flax
Magnitude
of
residue
studies
were
conducted
on
seed
fractions
of
canola
varieties
containing
the
Smart
 
trait.
CDC
Triffid
flax
was
also
treated.
The
post­
emergent
broadcast
application
of
tribenuron
methyl
at
0.07
and
0.14
oz.
ai/
acre
represents
one
to
two
times
the
proposed
use
rate
on
these
canola
and
flax
varieties.
No
tribenuron
methyl
residues
were
found
above
the
LOQ
of
0.02
ppm
in
any
seed
samples
treated
with
the
test
substance
at
a
use
rate
of
0.7
to
0.14
oz
of
tribenuron
methyl/
acre.

e.
Cotton
Seed
and
Gin
Trash
Magnitude
of
residue
studies
were
also
conducted
to
determine
residues
of
tribenuron
methyl
in
cotton
seed
and
cotton
gin
trash.
The
study
consisted
of
three
treatments.
Treatment
1:
One
broadcast
application
at
0.15
oz
ai/
A,
applied
approximately
14
days
prior
to
planting.
Treatment
2:
One
broadcast
application
at
0.15
oz
ai/
A,
applied
pre­
plant,
on
the
day
of
planting.
Treatment
3:
One
broadcast
application
at
0.75
oz
ai/
A,
applied
pre­
plant,
the
day
of
planting.
The
anticipated
target
PHI
was
approximately
120
days
after
the
last
application
of
the
test
substance;
actual
PHIs
ranged
from
123
to
196
days.
The
experimentally
determined
limit
of
quantitation
was
20
ppb
for
both
analytes.
The
limit
of
detection
was
estimated
to
be
6
ppb.
No
tribenuron
methyl
residues
were
found
above
the
limit
of
quantitation
of
0.02
ppm
in
any
cotton
seed
and
cotton
gin
trash
samples
treated
with
the
test
substance.

f.
Sunflowers
Magnitude
of
the
residue
studies
were
conducted
by
IR­
4
to
determine
residues
of
tribenuron
methyl
in
sunflowers.
Test
plots
were
treated
with
three
broadcast
applications
of
tribenuron
methyl,
applied
at
rates
of
0.25
 
1.3
oz
ai/
acre
per
application,
for
a
total
application
rate
of
0.75
to
3.9
oz
ai/
acre
per
crop
season.
Commercially
mature
sunflower
seed
samples
were
collected
67­
84
days
following
the
last
application.
The
results
from
these
trials
show
that
maximum
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
residues
of
tribenuron
methyl
are
less
than
0.05
ppm,
which
is
the
limit
of
quantitation.
Sunflowers
treated
with
the
5X
exaggerated
rate
of
tribenuron
methyl,
i.
e.,
three
applications
at
1.3
oz
ai/
acre/
application,
also
showed
no
residues
of
tribenuron
methyl
at
or
above
the
LOQ.
A
sunflower
processing
study
was,
therefore,
not
conducted.

g.
Corn
Grain,
Forage
and
Stover
Studies
were
conducted
to
determine
residues
of
tribenuron
methyl
in
field
corn
grain,
forage,
and
stover.
Two
test
plots
were
established
at
each
site.
One
plot
was
untreated
and
provided
control
samples
for
analysis.
The
other
plot
received
one
pre­
planting
or
at­
planting
application
of
tribenuron
methyl
at
a
rate
of
1.25
oz
ai/
acre,
which
was
five
times
the
maximum
expected
label
rate.
Field
corn
commodity
samples
 
grain,
forage,
and
stover
­
were
collected
at
normal
harvest
(
112­
150
days
after
application,
75­
106
days
after
application,
and
112­
150
days
after
application,
respectively)
and
analyzed
for
residues
of
tribenuron
methyl.
In
these
exaggerated
rate
studies,
at
normal
harvest,
no
residues
were
detected
(
limit
of
detection
0.02
ppm)
in
any
untreated
control
or
treated
samples
analyzed.

h.
Soybeans
Studies
were
conducted
to
determine
residues
of
tribenuron
methyl
in
soybean
seed.
Two
test
plots
were
established
at
each
site.
One
plot
was
untreated
and
provided
control
samples
for
analysis.
The
other
plot
received
one
pre­
planting
or
at­
planting
application
of
tribenuron
methyl
at
a
rate
of
1.25
oz
ai/
acre,
which
was
five
times
the
maximum
expected
label
rate.
Soybean
seed
samples
were
collected
at
normal
harvest
(
135­
148
days
after
application)
and
analyzed
for
residues
of
tribenuron
methyl.
In
these
studies,
at
normal
harvest,
no
residues
were
detected
(
limit
of
detection
0.02
ppm)
in
any
untreated
control
or
treated
samples
analyzed.

i.
Rice
Grain
and
Straw
Studies
were
conducted
to
determine
residues
of
tribenuron
methyl
in
rice
grain
and
straw.
Two
test
plots
were
established
at
each
site.
One
plot
was
untreated
and
provided
control
samples
for
analysis.
The
other
plot
received
one
pre­
planting
or
at­
planting
application
of
tribenuron
methyl
at
a
rate
of
1.25
oz
ai/
acre,
which
was
five
times
the
maximum
expected
label
rate.
Rice
grain
and
straw
samples
were
collected
at
normal
harvest
(
106­
129
days
after
application)
and
analyzed
for
residues
of
tribenuron
methyl.
In
these
exaggerated
rate
studies,
at
normal
harvest,
no
residues
were
detected
(
limit
of
detection
0.02
ppm)
in
any
untreated
control
or
treated
samples
analyzed.

h.
Grain
Sorghum
Forage,
Stover
and
Grain
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
Studies
were
conducted
to
determine
residues
of
tribenuron
methyl
in
sorghum
forage,
stover,
and
grain.
Two
test
plots
were
established
at
each
site.
One
plot
was
untreated
and
provided
control
samples
for
analysis.
The
other
plot
received
one
pre­
planting
or
at­
planting
application
of
tribenuron
methyl
at
a
rate
of
1.25
oz
ai/
acre,
which
was
five
times
the
maximum
expected
label
rate.
Grain
sorghum
forage,
stover,
and
grain
samples
were
collected
at
normal
harvest
(
87­
103
days
after
application
for
forage,
and
133­
144
days
after
application
for
stover
and
grain)
and
analyzed
for
residues
of
tribenuron
methyl.
In
these
exaggerated
rate
studies,
at
normal
harvest,
no
residues
were
detected
(
limit
of
detection
0.02
ppm)
in
any
untreated
control
or
treated
samples
analyzed.

B.
Toxicological
Profile
1.
Acute
Toxicity
Based
on
EPA
criteria,
technical
tribenuron
methyl
is
in
acute
toxicity
Category
IV
for
oral
and
inhalation
routes
of
exposure,
and
for
skin
irritation.
Tribenuron
methyl
is
in
acute
toxicity
Category
III
for
the
dermal
route
of
exposure,
and
for
eye
irritation.
It
is
not
a
skin
sensitizer.

Acute
oral
toxicity
in
rats
LD50
>
5000
mg/
kg
Acute
dermal
toxicity
in
rabbits
LD50
>
2000
mg/
kg
Acute
inhalation
toxicity
in
rats
LC50
>
6.7
mg/
L
Primary
eye
irritation
in
rabbits
Moderate
effects
reversed
within
3
days
Primary
dermal
irritation
in
rabbits
Non­
irritating
Dermal
sensitization
Sensitizer
2.
Genotoxicity
Technical
tribenuron
methyl
has
shown
no
genotoxic
or
mutagenic
activity
in
the
following
in
vitro
and
in
vivo
tests
:

In
vitro
Mutagenicity
Ames
Assay
Negative
In
vitro
Mutagenicity
CHO/
HPRT
Assay
Negative
In
vitro
Unscheduled
DNA
Synthesis
Negative
In
vivo
Cytogenetic
Negative
In
vivo
Bone
Marrow
Metaphase
Analysis
(
Rat)
Negative
In
vivo
Micronuclei
Induction
(
Mouse)
Negative
Tribenuron
methyl
was
negative
for
mutagenicity
in
an
in
vitro
bacterial
gene
mutation
assay
using
Salmonella
typhimurium
and
in
an
in
vitro
mammalian
cell
gene
mutation
assay
using
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
Chinese
hamster
ovary
cells.
In
cultured
primary
rat
hepatocytes
in
vitro,
tribenuron
methyl
was
negative
for
the
induction
of
unscheduled
DNA
synthesis.

In
a
test
measuring
clastogenic
damage
in
vivo,
tribenuron
methyl
was
negative
for
the
induction
of
chromosome
aberrations
in
male
and
female
rat
bone
marrow
cells
at
5000
mg/
kg.
A
study
measuring
chromosome
damage
in
vivo
was
conducted.
The
study
included
the
evaluation
of
micronuclei
in
bone
marrow
polychromatic
erythrocytes
of
male
and
female
mice.
The
result
was
negative
when
exposures
were
conducted
at
5000
mg/
kg
body
weight.

3.
Reproductive
and
Developmental
Toxicity
On
long­
term
dietary
administration,
tribenuron
methyl
did
not
affect
the
reproduction
or
lactation
performance
of
rats.
Developmental
studies
in
the
rat
and
rabbit
by
gavage
administration
indicated
that
tribenuron
methyl
did
not
present
a
unique
toxic
risk
to
the
fetus.

There
were
no
effects
in
reproduction
or
lactation
in
a
one­
generation
reproduction
study
with
rats
fed
for
90
days
with
diets
that
contained
0,
100,
1750,
or
5000
ppm
active
ingredient.
The
NOEL
was
100
ppm
(
7
mg/
kg/
day
for
males
and
8
mg/
kg/
day
for
females)
based
on
lower
mean
dam
and
pup
body
weights
for
the
intermediate
and
high
dose
groups.

There
were
no
effects
on
fertility
observed
in
a
2­
generation
reproduction
study.
In
this
study,
rats
were
fed
for
at
least
90
days
with
diets
that
contained
0,
25,
250,
or
1000
ppm
active
ingredient.
The
NOEL
was
25
ppm
based
on
lower
body
weights
for
the
dams
and
offspring
at
250
and
1000
ppm.
There
were
no
differences
attributed
to
administration
of
tribenuron
methyl
in
the
number
of
litters
produced
or
other
indices
of
reproductive
performance.
No
compound­
related
effects
on
male
fertility
were
noted.
No
effect
on
the
number
of
pups
born
or
pup
survival
were
observed
in
any
tribenuron
methyl
treated
group.

In
a
study
to
evaluate
developmental
toxicity
potential
in
rats,
tribenuron
methyl
did
not
produce
birth
defects
after
administration
via
oral
intubation
to
pregnant
rats
at
dose
levels
of
0,
20,
125,
and
500
mg/
kg/
day.
The
NOEL
for
this
study
was
20
mg/
kg/
day
for
both
maternal
and
developmental
toxicity.
This
was
based
on
maternal
effects
at
the
125
and
500
mg/
kg/
day.
The
effects
included
decreased
body
weight
gain
and
food
consumption,
and
an
increased
incidence
of
excess
salivation.
Fetal
effects
included
decreased
body
weights
(
at
125
and
500
mg/
kg/
day)
and
increased
number
of
resorptions
(
only
at
500
mg/
kg/
day).
In
the
rabbit
developmental
toxicity
study,
rabbits
were
fed
dosage
levels
of
0,
5,
20,
and
80
mg/
kg/
day.
The
NOEL
for
maternal
and
developmental
toxicity
was
20
mg/
kg/
day.
This
was
based
on
maternal
effects,
including
decreased
feed
consumption
and
an
increased
incidence
of
abortions
at
80
mg/
kg/
day.
Fetal
effects
included
slightly
reduced
body
weights
at
80
mg/
kg/
day.
No
teratogenicity
was
observed.

4.
Subchronic
Toxicity
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
The
most
sensitive
species
to
subchronic
exposure
of
tribenuron
methyl
was
the
rat.
In
the
rat
study,
rats
were
fed
dosage
levels
of
0,
100,
1750
or
5000
ppm
tribenuron
methyl
for
90
days.
The
findings
show
that
the
NOEL
for
tribenuron
methyl
was
100
ppm
for
both
male
and
female
rats
(
90­
day
dietary).
This
concentration
is
equivalent
to
7
and
8
mg/
kg/
day
in
male
and
female
rats,
respectively.
The
NOEL
was
based
on
the
decreased
body
weight
and
decreased
feed
consumption
noted
in
the
1750
and
5000
ppm
groups.
The
NOEL
for
the
90­
day
mouse
feeding
study
was
500
ppm
(
70
mg/
kg/
day
for
males
and
90
mg/
kg/
day
for
females)
based
on
liver
and
spleen
effects
at
1250,
2500,
and
5000
ppm
at
4
weeks.
An
increase
in
liver
weights
at
2500
ppm
was
noted,
with
no
histologic
effects
at
any
level.
The
NOEL
for
subchronic
(
90­
day
dietary)
exposure
in
dogs
was
73
mg/
kg/
day
for
male
and
78
mg/
kg/
day
for
female
dogs.
This
was
highest
dose
tested,
and
no
clear
treatment
related
effects
were
observed.
A
specific
target
organ
was
not
identified
in
any
of
the
species
studied.

5.
Chronic
Toxicity/
Oncogenicity
The
NOEL
for
chronic
(
18­
month
dietary)
exposure
in
mice
(
males)
was
20
ppm
(
equivalent
to
3
mg/
kg/
day).
This
was
based
on
an
increased
incidence
of
bilateral
seminiferous
degeneration
and
oligospermia
in
the
mid­
and
high­
dose
groups.
Within
females,
there
was
no
LOAEL
established,
but
the
minimal
body
weight
reductions
in
the
highest
dosed
females
suggested
that
the
NOEL
was
30
mg/
kg/
day.
There
were
no
neoplastic
or
other
histopathological
effects
associated
with
this
compound
and
no
target
organ
was
identified.
Additionally,
no
evidence
of
tribenuron
methyl
induced
oncogenicity
was
observed
in
the
mouse
study.

The
NOEL
for
chronic
(
2­
year
dietary)
exposure
in
rats
was
25
ppm
(
0.95
and
1.2
mg/
kg/
day
for
male
and
female
rats,
respectively).
Lower
body
weight
gains,
which
paralleled
lower
food
consumption
and
organ
weight
effects,
were
observed
in
the
250
and
1250
ppm
groups.
There
were
no
clinical
or
histopathological
effects
associated
with
these
organ
weight
effects.
The
incidence
of
mammary
adenocarcinomas
was
greater
than
controls
for
female
rats
in
the
1250
ppm
group.
This
effect
was
only
observed
in
this
high­
dose
group
and
under
conditions
of
significant
physiological
stress
(
mean
body
weights
for
female
rats
were
43%
lower
than
the
controls),
which
was
determined
to
be
above
the
maximum
tolerated
dose
(
MTD).

In
a
1­
year
feeding
study
in
dogs,
the
NOEL
was
determined
by
DuPont
to
be
250
ppm
(
8.16
and
8.18
mg/
kg/
day
for
male
and
female
dogs,
respectively).
This
was
based
on
slightly
lower
body
weights
and
increased
serum
creatinine
concentrations
for
dogs
in
the
high­
dose
group
(
1500
ppm).
Upon
review
by
the
EPA,
the
NOEL
was
set
at
25
ppm
(
0.8
mg/
kg/
day)
based
on
observations
such
as
elevated
bilirubin
blood
levels
and
reduction
in
body
weight
gain
in
male
dogs.
There
were
no
neoplastic
or
other
histopathological
effects
associated
with
compound
administration.
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
6.
Animal
Metabolism
The
metabolism
of
tribenuron
methyl
was
evaluated
in
rats
using
both
phenyl
and
triazine
labeling.
Tribenuron
methyl
was
extensively
and
rapidly
converted
to
polar
metabolites,
and
primarily
excreted
in
the
urine
and
feces.
Urinary
excretion
accounted
for
two
to
four
times
the
amount
of
radiolabel
excreted
via
feces.
Essentially
all
of
the
tribenuron
methyl
and
its
metabolites
were
excreted
in
the
urine
and
feces
of
the
rat
within
96
hours
after
dosing.
Levels
of
radiolabeled
residues
in
tissues
were
correspondingly
higher
in
those
groups
with
slower
elimination
kinetics,
but
no
evidence
of
bioconcentration
was
seen.
None
of
the
dosed
label
was
expired
as
carbon
dioxide
or
volatile
metabolites.

The
average
excretion
half­
life
values
for
male
and
female
rats
in
the
low­
dose
group
(
20
mg/
kg)
were
approximately
the
same
(
26­
33
hours),
and
independent
of
dietary
preconditioning.
The
average
excretion
half­
lives
for
male
and
female
rats
in
the
high­
dose
groups
(
1700,
1800,
and
2000
mg/
kg)
were
approximately
51­
54
hours
(
males)
and
68­
96
hours
(
females).
These
results
indicate
that
the
metabolism
of
tribenuron
methyl
in
male
and
female
rats
is
qualitatively
similar,
however,
female
rats
metabolize
and
excrete
this
product
much
slower
than
male
rats
at
the
high
doses.
The
low
residual
radioactivity
in
the
rat
indicated
that
tribenuron
methyl
does
not
covalently
bind
to
tissue
macromolecules.
Based
on
these
data,
the
body
burden
of
this
compound
is
not
expected
to
increase
significantly
upon
repeated,
long­
term
administration.

The
major
metabolites
of
tribenuron
methyl
are
those
expected
from
the
enzymatic
hydroxylation
and
dealkylation
activities
of
the
hepatic
microsomal
mixed
function
oxidase
system.
The
major
urinary
metabolites
were
identified
as
metsulfuron
methyl
and
saccharin
(
phenyl
labeled
groups)
and
metsulfuron
methyl
and
O­
demethyl
triazine
amine
(
triazine
labeled
groups);
no
evidence
of
glucuronide
or
sulfate
conjugation
was
seen.

Results
from
a
metabolism
study
with
two
radioactive
forms
of
tribenuron
methyl
([
14C]­
triazine
and
[
14C]­
phenyl)
in
lactating
goats
show
that
most
of
the
dosed
radioactivity
was
recovered
in
the
urine
(
61­
71%)
and
feces
(
15­
20%).
In
the
urine,
intact
tribenuron
methyl
and
metsulfuron
methyl
accounted
for
17­
23%
and
20­
22%
of
the
administered
dose,
respectively.
The
third
major
component
in
phenyl­
dosed
goat
urine
was
saccharin
(
23.5%
of
the
dose);
the
third
major
metabolite
in
the
triazine­
dosed
goat
urine
was
O­
demethyl
N­
demethyl
triazine
amine
(
10.9%).
The
highest
levels
of
residues
observed
in
the
milk
were
0.09
ppm
(
tribenuron
methyl
equivalents)
from
the
triazine­
dosed
goat,
and
0.006
ppm
from
the
phenyl­
dosed
goat.
Recoveries
of
the
administered
dose
were
82.2%
for
the
goat
given
the
triazine
label,
and
86.8%
for
the
goat
dosed
with
the
phenyl
label.
Throughout
the
dosing
phase,
the
goats
did
not
display
any
signs
of
toxicity,
and
there
was
no
effect
on
milk
production.
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
There
were
no
significant
levels
of
unique
plant
metabolites
of
tribenuron
methyl
found
in
food
or
feed
products
at
crop
maturity.
Hence,
toxicity
testing
of
other
degradation
products
of
tribenuron
methyl
is
not
necessary.

7.
Metabolite
Toxicology
There
is
no
evidence
that
the
metabolites
of
tribenuron
methyl,
as
identified
in
either
the
plant
or
animal
metabolism
studies,
are
of
any
toxicological
significance.

8.
Endocrine
Effects
In
the
two­
year
study,
female
rats
fed
tribenuron
methyl
had
a
significant
increase
in
mammary
adenocarcinoma
incidence,
but
only
at
a
dose
that
greatly
exceeded
the
maximum
tolerated
dose
(
43%
decrease
in
body
weight).
In
contrast,
an
18­
month
feeding
study
demonstrated
that
tribenuron
methyl
was
not
oncogenic
in
mice,
nor
was
there
oncogenicity
in
the
rat
study
at
doses
which
produced
marked
toxicity,
but
did
not
exceed
the
maximum
tolerated
dose.

A
subsequent
mechanistic
study
was
conducted
at
a
dose
level
that
produced
similar
body
weight
gain
decrements
observed
in
the
rat
oncogenicity
study.
This
mechanistic
study
demonstrated
an
increased
incidence
of
rats
with
prolonged
estrus
and
suggested
that
this
may
have
been
associated
with
the
high­
dose
mammary
adenomas
observed
in
the
rat
oncogenicity
study.
However,
the
role
of
the
body
weight
effect
must
be
considered
in
interpreting
this
data.
Numerous
studies
have
demonstrated
that
nutritional
deficits
can
also
significantly
impact
the
estrus
cycle.
Such
hormone­
mediated
effects
are
considered
to
have
a
threshold
below
which
growth
of
mammary
tissue
will
not
be
affected.
Thus
potential
endocrine
effects
of
tribenuron
methyl
are
unlikely
to
be
a
concern
at
biologically
relevant
doses.
Adequate
margins
of
safety
protect
humans
from
these
threshold
effects.

C.
Aggregate
Exposure
Tribenuron
methyl
is
the
active
ingredient
in
various
DuPont
herbicides,
with
new
proposed
uses
on
the
following
commercial
crops:
sunflowers,
rice,
field
corn,
soybeans,
and
grain
sorghum.
There
are
no
residential
uses
for
any
tribenuron
methyl
containing
herbicides.

1.
Dietary
Exposure
The
chronic
reference
dose
(
cRfD)
of
0.008
mg/
kg/
day
is
based
on
the
NOEL
determined
by
EPA
of
0.8
mg/
kg/
day
from
the
one­
year
dog
feeding
study
and
a
100X
safety
factor.
Based
on
the
acute
toxicity
profile
of
tribenuron
methyl,
there
are
no
acute
effects.
Non­
specific
clinical
signs
and
weight
effects
have
been
observed
in
developmental
studies
after
high,
multiple
doses.
However,
in
the
acute
LD50
study
conducted
at
the
limit
dose
of
5000
mg/
kg,
the
only
clinical
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
sign
observed
was
stained
perineum
in
some
animals.
Therefore
no
relevant
acute
dietary
endpoint
attributable
to
a
single
dose
was
identified.

2.
Food
a.
Chronic
Dietary
Exposure
Assessment
Chronic
dietary
exposure,
resulting
from
the
registered
and
proposed
uses
of
tribenuron
methyl
on
barley,
canola,
cotton,
flax,
grass,
oats,
wheat,
rice,
soybeans,
grain
sorghum,
field
corn,
and
sunflowers
is
well
within
the
acceptable
limits
for
all
sectors
of
the
population,
as
predicted
by
the
Chronic
Module
of
the
Dietary
Exposure
Evaluation
Model
(
DEEM,
Exponent,
Inc.,
2003
Version
7.87).
The
percentage
or
proportion
of
a
crop
that
is
treated
can
have
a
significant
effect
on
the
exposure
profile.
In
this
case,
it
was
assumed
for
the
crop
that
100%
was
treated
with
tribenuron
methyl.
Based
on
a
comparison
with
the
use
profile
for
most
other
herbicides,
this
is
an
extremely
conservative
estimate.

The
predicted
chronic
exposure
for
the
U.
S.
population
subgroup
was
0.00021
mg/
kg
bw/
d.
The
population
subgroup
with
the
highest
predicted
level
of
chronic
exposure
was
children
1­
6
years,
with
an
exposure
of
0.000477
mg/
kg
bw/
day.
Based
on
a
chronic
NOEL
of
0.8
mg/
kg
bw/
d
and
a
100­
fold
safety
factor,
the
cRfD
would
be
0.008
mg/
kg
bw/
d.
For
the
U.
S.
population,
the
predicted
exposure
is
equivalent
to
2.7%
of
the
cRfD.
For
the
population
subgroup
with
the
highest
level
of
exposure
(
children
1­
6
years),
the
exposure
would
be
equivalent
to
6.0%
of
the
cRfD.
Because
the
predicted
exposures,
expressed
as
percentages
of
the
cRfD,
are
well
below
100%,
there
is
reasonable
certainty
that
no
chronic
effects
would
result
from
dietary
exposure
to
tribenuron
methyl.

b.
Acute
Dietary
Exposure
Acute
dietary
risk
assessments
are
performed
for
a
food­
use
pesticide
if
a
toxicological
study
indicates
the
possibility
of
an
effect
of
concern
as
a
result
of
a
one
day
or
a
single
exposure.
No
acute
dietary
endpoint
attributable
to
a
single
dose
was
identified
for
tribenuron
methyl.
Therefore
the
quantification
of
acute
dietary
risk
is
not
considered
necessary.
There
is
reasonable
certainty
that
no
acute
effects
would
result
from
dietary
exposure
to
tribenuron
methyl.

3.
Drinking
Water
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
Surface
water
exposure
was
estimated
using
the
Generic
Expected
Environmental
Concentration
(
GENEEC)
model.
Groundwater
exposures
were
estimated
using
SCI­
GROW.

The
EPA
uses
drinking
water
levels
of
comparison
(
DWLOCs)
as
a
surrogate
measure
to
capture
risk
associated
with
exposure
to
pesticides
in
drinking
water.
A
DWLOC
is
the
concentration
of
a
pesticide
in
drinking
water
that
would
be
acceptable
as
an
upper
limit
in
light
of
total
aggregate
exposure
to
that
pesticide
from
food,
water,
and
residential
uses.
Since
there
are
no
residential
uses
for
tribenuron
methyl,
the
aggregate
exposure
is
due
to
food
and
water
only.
A
DWLOC
will
vary
depending
on
the
residue
level
in
foods,
the
toxicity
endpoint,
and
with
drinking
water
consumption
patterns
and
body
weights
for
specific
subpopulations.
Default
body
weights
and
consumption
values,
as
used
by
the
USEPA
Office
of
Water,
used
to
calculate
the
DWLOC
values
for
tribenuron
methyl
are:
70kg
and
2L
(
adult
male),
60
kg
and
2L
(
adult
female),
and
10
kg
and
1L
(
child).

No
acute
dietary
endpoint
was
identified.
Therefore,
an
acute
drinking
water
risk
assessment
is
not
considered
necessary.
One
can
conclude
with
reasonable
certainty
that
residues
of
tribenuron
methyl
in
drinking
water
do
not
contribute
significantly
to
the
aggregate
acute
human
health
risk.

The
chronic
DWLOCs
are
0.28
ppm
for
adult
men,
0.24
ppm
for
adult
women,
and
0.08
ppm
for
children
1­
2
years
old.
These
DWLOC
values
are
substantially
higher
than
the
GENEEC
56­
day
estimated
environmental
concentration
of
0.3
ppb
for
tribenuron
methyl
in
surface
water,
estimated
concentrations
in
ground
water
are
even
lower.
Therefore,
one
can
conclude
with
reasonable
certainty
that
residues
of
tribenuron
methyl
in
drinking
water
do
not
contribute
significantly
to
the
aggregate
chronic
human
health
risk.

4.
Non­
Dietary
Exposure
Tribenuron
methyl
is
not
registered
for
any
use
which
could
result
in
non­
occupational
or
nondietary
exposure
to
the
general
population.

D.
Cumulative
Effects
Tribenuron
methyl
belongs
to
the
sulfonylurea
class
of
crop
protection
chemicals.
Other
structurally
similar
compounds
in
this
class
are
registered
as
herbicides.
However,
the
herbicidal
activity
of
sulfonylureas
is
due
to
the
inhibition
of
acetolactate
synthase
(
ALS),
an
enzyme
found
only
in
plants.
This
enzyme
is
part
of
the
biosynthesis
pathway
leading
to
the
formation
of
branched
chain
amino
acids.
Animals
lack
ALS
and
this
biosynthetic
pathway.
This
lack
of
ALS
contributes
to
the
relatively
low
toxicity
of
sulfonylurea
herbicides
in
animals.
There
is
no
reliable
information
that
would
indicate
or
suggest
that
tribenuron
methyl
has
any
toxic
effects
on
mammals
that
would
be
cumulative
with
those
of
any
other
chemical.
Pesticide
Petition
for
Tolerances
AGRICULTURAL
COMMODITIES
for
Tribenuron
Methyl
Sunflowers,
Rice,
Field
Corn,
Soybeans,
and
Grain
Sorghum
Copyright
by
E.
I.
du
Pont
de
Nemours
and
Company
Wilmington,
DE
19880­
0038
(
August
2004)
E.
Safety
Determination
Based
on
data
and
information
submitted
by
DuPont,
EPA
previously
determined
that
the
establishment
of
tolerances
of
tribenuron
methyl
on
wheat,
barley,
oats,
cotton,
canola,
flax,
and
grass
raw
agricultural
commodities
would
protect
the
public
health,
including
the
health
of
infants
and
children.
Establishment
of
new
tolerances
for
tribenuron
methyl
on
sunflowers
at
0.05
ppm,
field
corn
commodities
at
0.05
ppm,
grain
sorghum
commodities
at
0.05
ppm,
rice
commodities
at
0.05
ppm,
and
soybean
seed
at
0.05
ppm
will
not
adversely
impact
public
health.

1.
U.
S.
Population
Using
the
conservative
exposure
assumptions
described
above,
and
based
on
the
most
sensitive
chronic
NOEL
of
0.79
mg/
kg/
day
and
a
cRfD
of
0.008
mg/
kg/
day,
the
chronic
dietary
exposure
will
utilize
2.7
%
of
the
cRfD
for
the
U.
S.
population.
Generally,
exposures
below
100
%
of
the
RfD
are
of
no
concern
because
the
RfD
represents
the
level
at
or
below
which
daily
dietary
exposure
over
a
lifetime
will
not
pose
risk
to
human
health.
Therefore,
it
is
concluded
that
there
is
reasonable
certainty
that
no
harm
will
result
from
exposure
to
tribenuron
methyl
residues.

2.
Infants
and
Children
Chronic
dietary
exposure
of
the
most
highly
exposed
subgroup
in
the
population,
children
1­
6
years
old,
is
0.000477
mg/
kg/
day,
or
6.0
%
of
the
cRfD.
There
are
no
residential
uses
of
tribenuron
methyl
and
contamination
of
drinking
water
is
extremely
unlikely.
Based
on
the
completeness
and
reliability
of
the
toxicity
data,
the
lack
of
toxicological
endpoints
of
special
concern,
the
lack
of
any
indication
of
greater
sensitivity
of
children,
and
the
conservative
exposure
assessment,
there
is
a
reasonable
certainty
that
no
harm
will
result
to
infants
and
children
from
the
aggregate
exposure
to
residues
of
tribenuron
methyl
from
all
anticipated
sources
of
dietary
and
non­
occupational
exposure.
Accordingly,
there
is
no
need
to
apply
an
additional
safety
factor
for
infants
and
children.

F.
International
Tolerances
The
MRL
in
Canada
for
tribenuron
methyl
on
canola
is
0.1
ppm.
Tolerances
for
tribenuron
methyl
on
cereals,
barley,
and/
or
wheat
commodities
have
been
established
or
proposed
in
other
countries
 
for
example
in
Greece,
France,
Italy,
Portugal,
Spain
and
the
United
Kingdom
at
levels
ranging
from
0.01
to
0.2
ppm.
No
Codex
maximum
residue
limits
(
MRLs)
have
been
established
or
proposed.
