UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
MEMORANDUM
DATE:
April
3,
2002
SUBJECT:
Tebuthiuron
Acute
and
Chronic
Dietary
Exposure
Assessments
for
the
Tolerance
Reassessment
Eligibility
Decision
(TRED);
PC
codes
105501;
DP
Barcode
D281821.

FROM:
Sheila
Piper,
Chemist
Chemistry
and
Exposure
Branch
Health
Effects
Division
(7509C)

THROUGH:
F.
B.
Suhre,
Branch
Senior
Scientist
Chemistry
and
Exposure
Branch
Health
Effects
Division
(7509C)

and
Sherrie
Kinard,
Chemist
Douglas
Dotson,
Chemist
Dietary
Exposure
Science
Advisory
Council
(DeSAC)
Health
Effects
Division
(7509C)

TO:
Paula
Deschamp,
Risk
Assessor
Reregistration
Branch
II
Health
Effects
Division
(7509C)
and
Wilhelmena
Livingston,
Chemical
Review
Manager
Special
Review
Branch
Special
Review
and
Reregistration
Division
(7508C)

The
purpose
of
this
memorandum
is
to
summarize
the
results
of
the
dietary
risk
assessment
for
the
general
U.
S.
population
(chronic
only)
and
females
13­
50
years
(acute)
resulting
from
exposure
to
tebuthiuron
through
food.
This
risk
assessment
is
an
updated
risk
analysis
that
has
been
conducted
for
tebuthiuron.
The
most
recent
dietary
risk
assessment
was
conducted
by
J.
M.
Winterseen
(09/
01/
93).
DP
Barcode:
D281821
Dietary
exposure
assessment
/
1
Tebuthiuron
/
105501
1
aPAD/
cPAD
=
acute/
chronic
Population
Adjusted
Dose
=
Acute
or
Chronic
RfD
FQPA
Safety
Factor
1
EPA
Reviewer:
Sheila
Piper
,
Date
April
3,
2002
STUDY
TYPE:
Tebuthiuron
Acute
and
Chronic
Dietary
Exposure
Assessments
for
the
Tolerance
Reregistration
Eligibility
Decision
(TRED)
PC
codes
105501;
DP
Barcode
D281821.

ACTIVE
INGREDIENT:
Tebuthiuron
SYNONYMS:
Spike
RESIDUE
OF
CONCERN:
The
residues
of
concern
in
livestock
commodities
are
tebuthiuron
and
its
metabolites
104,
106,
108,
and
109;
the
terminal
residues
of
concern
in
milk
are
tebuthiuron
and
metabolites
104,
104(
OH),
106,
109
and
109(
OH).
Executive
Summary
A
Tier
2
acute
and
a
chronic
dietary
risk
assessment
were
conducted
for
all
supported
currently
registered
tebuthiuron
food
uses.
Dietary
risk
estimates
are
provided
for
the
general
U.
S.
population
(chronic
only)
and
females
13­
50
(acute).
This
assessment
concludes
that
for
all
included
commodities,
the
acute
risk
estimates
are
below
the
Agency's
level
of
concern
(<
100%
aPAD
1
)
at
the
95
th
exposure
percentile
for
females
13­
50
years
(<
1%
of
the
aPAD).
This
assessment
also
concludes
that
for
all
included
commodities,
the
chronic
risk
estimates
are
below
the
Agency's
level
of
concern
(<
100%
cPAD
1
)
for
the
general
U.
S.
population
(<
1%
of
the
cPAD)
and
all
population
subgroups.

I.
Introduction
Exposure
to
pesticides
can
occur
through
food,
water,
residential
and
occupational
means.
Risk
assessment
incorporates
both
exposure
and
toxicity
of
a
given
pesticide.
The
risk
is
expressed
as
a
percentage
of
a
dose
that
could
be
expressed
as
a
daily
or
a
long
term
dose,
that
poses
no
unreasonable
adverse
effects.
This
is
called
the
population
adjusted
dose
(PAD),
and
is
expressed
as
%PAD.
References
are
available
on
the
DP
Barcode:
D281821
Dietary
exposure
assessment
/
2
Tebuthiuron
/
105501
2
EPA/
pesticides
web
site
which
discuss
the
acute
and
chronic
risk
assessments
in
more
detail:
"Available
Information
on
Assessing
Exposure
from
Pesticides,
A
User's
Guide",
6/
21/
2000,
web
link:
http://
www.
epa.
gov/
fedrgstr/
EPA­
PEST/
2000/
July/
Day­
12/
6061.
pdf
;
or
see
SOP
99.6,
8/
20/
99.

The
purpose
of
this
memorandum
is
to
summarize
the
results
of
the
dietary
risk
assessment
for
the
U.
S.
population
(chronic
only)
and
females
13­
50
(acute)
resulting
from
exposure
to
tebuthiuron
through
food.
This
risk
assessment
is
an
updated
risk
analysis
that
has
been
conducted
for
tebuthiuron.
The
most
recent
dietary
exposure
analysis
was
conducted
by
J.
M.
Winterseen
(09/
01/
93).

II.
Toxicological
Information
HED
has
completed
the
dietary
risk
assessment
for
tebuthiuron
on
the
deliberations
of
the
Hazard
Identification
Assessment
Review
Committee
(HIARC)
and
hazard
endpoints
have
been
selected
for
both
acute
(one
day)
and
chronic
(long
term)
exposure
intervals
(Memorandum:
R.
Fricke
dated
February
5,
2002).

On
December
13,
2001
and
January
17,
2002
the
HIARC
evaluated
the
results
of
a
rabbit
developmental
toxicity
study
and
its
impact
on
the
Food
Quality
Protection
Act
(FQPA)
assessment
and
toxicity
endpoint
selection
for
tebuthiuron.
An
appropriate
endpoint
attributable
to
a
single
dose
was
not
available
in
the
database
for
an
acute
reference
dose
(general
population).
An
appropriate
acute
endpoint
(females
13+)
attributable
to
a
single
dose
at
25
mg/
kg/
day
was
selected
for
risk
assessment,
since
there
was
no
dose
response
in
the
observed
early
resorptions.
In
addition,
the
selection
of
the
25
mg/
kg/
day
dose
for
risk
assessment
is
supported
by
the
NOAEL
of
50
mg/
kg/
day
in
a
rabbit
developmental
range­
finding
study
with
a
structurally
related
urea.
For
chronic
reference
dose,
the
NOAEL
is
14
mg/
kg/
day
from
the
twogeneration
reproduction
study
based
on
decreased
body
weight,
body
weight
gain
and
food
consumption
in
F1
females
at
30
mg/
kg/
day.
The
acute
and
chronic
hazard
endpoints
selected
for
dietary
exposure
to
tebuthiuron
are
listed
in
Table
1.

In
a
meeting
on
February
4,
2002,
the
FQPA
Safety
Factor
Committee
recommended
that
the
10X
FQPA
Safety
Factor
(as
required
by
the
Food
Quality
Protection
Act
of
August
3,
1996)
be
reduced
to
3X
for
acute
dietary
exposure
(females
13­
50)
and
1X
for
chronic
dietary
exposure
(general
population)
when
assessing
the
potential
dietary
risks
posed
by
tebuthiuron
use
(C.
Christensen,
FQPA
memo,
02/
12/
02).
The
basis
and
rationale
for
the
3x
FQPA
safety
factor
for
females
13­
50
years
is
due
to
a
data
gap
for
assessing
susceptibility
of
fetuses
DP
Barcode:
D281821
Dietary
exposure
assessment
/
3
Tebuthiuron
/
105501
3
following
in
utero
exposure
to
tebuthiuron.
For
chronic
dietary
exposure
to
the
general
population,
the
FQPA
safety
factor
will
be
reduced
to
1x
because
there
was
no
susceptibility
identified
in
the
2­
generation
rat
reproduction
study
(a
long­
term
study).

Table
1.
Summary
of
Toxicological
Dose
and
Endpoints
for
Tebuthiuron
for
Use
in
Dietary
Exposure
Assessment
EXPOSURE
SCENARIO
DOSE
(mg/
kg/
day)
ENDPOINT
STUDY
Acute
Dietary
(Females
13­
50)
NOAEL=
25
UF
=
100
FQPA=
3X
Increased
post­
implantation
loss
and
fetal/
litter
resorptions
at
50
mg/
kg/
day
(LOAEL).
Developmental
Toxicity
Study
in
the
Rabbit
Acute
RfD
(Females
13­
50
years
old)
=
0.25
mg/
kg/
day
Acute
PAD
(females
13­
50)=
0.083
mg/
kg/
day
Acute
Dietary
(General
Population)
No
appropriate
effects
attributed
to
a
single
exposure
were
identified.

Chronic
Dietary
NOAEL
=
14
UF
=
100
FQPA=
1X
Decreased
body
weight
and
feed
consumption
in
F1
females
at
30
mg/
kg/
day
(LOAEL)
2­
Generation
Reproduction
Study
in
the
Rat
Chronic
RfD
=
0.14
mg/
kg/
day
Chronic
PAD
(all
population)=
0.14
mg/
kg/
day
Cancer
No
endpoint
for
carcinogenicity
due
to
inadequate
carcinogenicity
studies
Category
D
or
not
classifiable
as
to
human
carcinogenicity
Rat
and
mouse
carcinogenicity
studies
III.
Residue
Information
Tebuthiuron
[N­[
5­(
1,1­
dimethylethyl)­
1,3,4­
thiadiazol­
2­
yl]­
N,
N'­
dimethylurea]
is
a
relatively
nonselective,
soil
activated
herbicide
registered
for
use
to
control
broadleaf,
woody
weeds,
grasses
and
brush
on
terrestrial
feed
crop
sites
(pastures
and
rangeland).
Pelleted/
tableted
(P/
T)
is
the
only
tebuthiuron
formulation
class
registered
for
use
on
food/
feed
crops.
This
formulation
may
be
applied
preplant,
preemergence,
postemergence,
or
postharvest.
The
registered
mode
of
DP
Barcode:
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Dietary
exposure
assessment
/
4
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/
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4
application
is
broadcast
using
ground
or
aerial
equipment.

Tolerances
for
residues
of
tebuthiuron
have
been
established
for
grasses
and
livestock
commodities
(40
CFR
§180.390).
These
tolerances
are
expressed
in
terms
of
the
combined
residues
of
N­[
5­(
1,1­
diemthylethyl)­
1,3,4­
thiadiazol­
2­
yl]­
N,
N'­
dimethylurea
and
its
metabolites
containing
the
dimethylethyl
thiadiazole
moiety.
Adequate
enforcement
methods
are
available
for
the
determination
of
residues
in/
on
grasses
and
in
animal
tissues
and
milk.

Tebuthiuron
is
a
List
A
FIFRA
reregistration
chemical
that
was
the
subject
of
a
Reregistration
Standard
Guidance
Document
dated
7/
87.
The
Residue
Chemistry
Chapter
of
the
Tebuthiuron
Tolerance
Reregistration
Eligibility
Decision
(TRED)
is
being
completed
in
conjunction
with
this
document
and
reflects
the
evaluation
of
all
the
submissions
made
in
response
to
the
earlier
reregistration
documents.

No
monitoring
data
were
available
for
tebuthiuron.
An
adequate
method
is
available
for
the
enforcement
of
plant
commodity
tolerances.
A
GLC
with
flame
photometric
detection
is
designated
as
Method
II
in
PAM
Vol.
II.
Tebuthiuron
and
metabolites
104
and
109
are
thermally
degraded
on
the
GLC
column
and
are
determined
as
104;
metabolite
103(
OH)
is
determined
as
104(
OH).
A
revised
enforcement
method
for
milk,
to
include
hydrolysis
steps
and
the
determination
of
metabolites
104(
OH)
and
109(
OH)
is
being
requested.
The
stated
detection
limits
are
0.1
ppm
for
tebuthiuron
and
metabolites
104
and
109,
and
0.2
ppm
for
metabolite
103(
OH).

Residues
in
meat
and
milk
were
estimated
using
livestock
feeding
studies.
The
order
of
preference
for
the
purpose
of
refining
dietary
exposure
assessment
is
usually:
monitoring
data>
field
trial
data>
tolerance.
The
registrant
submitted
all
field
trial
data
for
registered
uses
of
tebuthiuron
on
plant
commodities
which
reflect
maximum
application
rates
and
shortest
PHIs
(S.
Funk,
D187699,
8/
93).

Metabolites
C
For
dietary
risk
assessment,
the
Metabolism
Committee
concluded
that
the
residues
of
concern
in
plants
are
the
parent
compound
and
its
metabolites
103,
103(
OH),
104,
and
109.
The
residues
of
concern
in
livestock
commodities
(fat,
meat,
kidney,
and
liver)
are
tebuthiuron
and
its
metabolites
104,
106,
108,
and
109;
the
terminal
residues
of
concern
in
milk
are
tebuthiuron
and
metabolites
104,
104(
OH),
106,
109,
and
109(
OH).
A
poultry
metabolism
study
is
not
required
since
grasses
are
not
considered
to
be
poultry
feed
items.
DP
Barcode:
D281821
Dietary
exposure
assessment
/
5
Tebuthiuron
/
105501
5
Percent
Crop
Treated
Information
C
An
updated
quantitative
usage
analysis
for
tebuthiuron
was
provided
by
BEAD
based
on
data
years
1996­
99
(S.
Smearman,
Biological
and
Economic
Analysis
Division,
2/
28/
02).
The
percentage
of
the
acres
for
each
site
treated
in
1999,
an
average
of
less
than
1
percent
of
rangeland/
pastureland
acreage
was
treated
up
to
an
estimated
maximum
2
percent
of
acres
treated
annually.
For
the
miles
of
railroad
rights
of
way
and
electric
utility
rights
of
way
treated
annually,
the
average
percentage
of
miles
treated
was
less
than
1
percent,
respectively.
No
information
pertaining
to
the
percent
of
area
treated
for
industrial
facilities
or
miles
of
pipeline
rights
of
way
was
available,
but
based
on
the
percentage
of
a.
i.
allocated
to
these
sites
it
is
assumed
that
the
percent
of
area/
mileage
treated
also
averages
less
than
1
percent.

Processing
Information
C
Processing
factors
were
taken
from
the
DEEM
default
values.

Residue
Estimates
for
Meat
and
Milk
C
The
only
source
of
dietary
(food)
exposure
is
the
consumption
of
secondary
residues
in
meat
and
milk
from
livestock
fed
tebuthiuron
treated
grass
forage
and
hay.
Tolerances
in
meat
(2ppm)
and
milk
(0.3
ppm)
are
established
and
in
grass
forage
and
hay
at
10
ppm
for
residues
of
tebuthiuron
and
its
metabolites
containing
the
dimethyl
thiadiazole
moiety.

C
The
residues
of
concern
in
livestock
commodities
(fat,
meat,
kidney,
and
liver)
are
tebuthiuron
and
its
metabolites
104,
106,
108,
and
109;
the
terminal
residues
of
concern
in
milk
are
tebuthiuron
and
metabolites
104,
104(
OH),
106,
109,
and
109(
OH).
A
poultry
metabolism
study
is
not
required
since
grasses
are
not
considered
to
be
poultry
feed
items.

C
Feeding
studies
(S.
Funk,
Ruminant
Feeding
Study,
D217379,
12/
05/
95)
have
demonstrated
a
transfer
of
tebuthiuron
to
animal
tissue
(meat,
meat
by­
products,
etc.).
The
results
of
the
ruminant
feeding
study
conducted
at
a
nominal
45
ppm
tebuthiuron
feeding
level
for
28
days
show
that
the
existing
tolerances
for
milk
and
meat
are
inadequate
and
should
be
revised.
The
tolerances
for
meat
(2
ppm)
and
fat
(2
ppm)
may
DP
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be
lowered
to
1
ppm,
but
the
tolerances
for
milk
(0.3
ppm)
and
meat
byproducts
(2
ppm)
must
be
increased
to
0.8
ppm
for
milk
and
5
ppm
for
meat
byproducts.

C
A
dietary
burden
of
tebuthiuron
for
beef
cattle
(extrapolating
to
goats,
sheep
and
horses)
is
based
on
the
feed
items
of
grass
forage.
For
dairy
cattle,
the
residues
used
were
the
average
residues
from
grass
forage
field
trials
while
for
beef
cattle
the
highest
average
field
trial
(HAFT)
residue
values
were
used.
See
Table
2
below.

Table
2:
Dietary
Burden
of
Tebuthiuron
to
Beef
and
Dairy
Cattle
Commodity
%
DM
a
Beef
Cattle
Dairy
Cattle
Average
Field
Trial
Data
(ppm)
b
%
Diet
a
Concentration
(ppm)
HAFT
b
(ppm)
%
Diet
a
Concentration
c
(ppm)

Grass
Forage
25
1.97
60
2.56
2.56
60
6.14
Corn
grain
88
0
40
0
0
40
0
TOTAL
­
100
2.56
100
6.14
a
OPPTS
Guideline
860.1000
b
Beef
cattle
based
on
average
field
trial
data;
dairy
cattle
based
on
highest
average
field
trial
(HAFT)
data
c
Ruminant
contribution=
[tolerance/
%DM]
x
%diet
Dow
Elanco
dosed
four
groups
of
three
dairy
cows
each
for
28
days
with
gelatin
capsules
containing
tebuthiuron
at
nominal
dosage
rates
of
0
ppm,
45
ppm
(9.5x),
135
ppm
(28.5x),
and
450
ppm
(95x).
Daily
milk
samples
were
collected,
and
within
24
hours
of
the
last
dosing
the
cows
were
sacrificed
and
tissues
were
collected.

For
beef
cattle,
the
nominal
dosage
rates
of
0
ppm,
45
ppm
(7.3x),
135
ppm
(22x),
and
450
ppm
(73x)
were
determined
based
on
the
dietary
burden
for
beef
cattle.
Tissue
samples
(5
grams)
were
analyzed
by
Method
GRM
94.01,
which
determines
tebuthiuron
and
metabolites
104,
106,
108
and
109.
Liver,
kidney,
muscle,
or
fat
was
hydrolyzed
with
6N
HCl
which
converts
metabolite
109
to
104.
The
maximum
incurred
residues
in
various
tissues
at
the
45
ppm
feeding
level,
expressed
as
the
sum
of
tebuthiuron,
104
+
109
as
104,
and
106
+
108
as
106.
Results
of
the
analyses
of
bovine
tissues
are
summarized
in
Table
3.
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Table
3:
Residues
of
Tebuthiuron
and
Metabolites
in
Tissues
from
the
Oral
Administration
of
Tebuthiuron
for
28
Days
Diet
(ppm
tebuthiuron)
Tissue
Analyte
Concentration
1
(ppm)
Range
2
(ppm)
Average
3
(ppm)

0
liver
tebuthiuron
<0.1
4
<0.1
4
104
+
109
5
0.032
­
<0.05
4
0.039
+
0.010
6
106
+
108
7
0.104
­
0.368
0.201
+
0.14
kidney
tebuthiuron
0.055
­
<0.1
4
0.075
+
0.023
104
+
109
5
0.108
­
<0.2
4
0.138
+
0.054
106
+
108
7
<0.1
4
­
0.19
0.248
+
0.19
muscle
tebuthiuron
<0.2
4
<0.2
4
104
+
109
5
<0.06
4
<0.06
4
106
+
108
7
<0.06
4
<0.06
4
fat
tebuthiuron
<0.01
4
0.01
4
104
+
109
5
0.006
­
<0.01
4
0.007
+
0.002
106
+
108
7
<0.01
<0.01
45
liver
tebuthiuron
<0.1
<0.1
104
+
109
5
0.94
­
2.13
1.73
+
0.68
106
+
108
7
1.50
­
1.80
1.65
+
0.15
kidney
tebuthiuron
<0.1
<0.1
104
+
109
5
0.355
­
0.907
0.679
+
0.29
106
+
108
7
0.756
­
1.06
0.873
+
0.16
muscle
tebuthiuron
<0.2
<0.2
104
+
109
5
0.214
­
0.560
0.418
+
0.18
106
+
108
7
0.196
­
0.230
0.216
+
0.018
fat
tebuthiuron
<0.01
<0.01
104
+
109
5
0.12
­
0.38
0.206
+
0.15
106
+
108
7
0.033
­
0.164
0.093
+
0.066
135
liver
tebuthiuron
0.098
­
0.265
0.154
+
0.096
104
+
109
5
4.46
­
8.23
6.96
+
2.16
106
+
108
7
2.76
­
3.67
3.35
+
0.51
kidney
tebuthiuron
0.050
­
0.069
0.059
+
0.01
104
+
109
5
1.58
­
2.72
2.27
+
0.60
106
+
108
7
1.44
­
3.20
2.22
+
0.90
muscle
tebuthiuron
0.120
­
0.140
0.13
+
0.01
104
+
109
5
1.32
­
2.86
2.26
+
0.82
106
+
108
7
0.466
­
0.816
0.601
+
0.19
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Table
3:
Residues
of
Tebuthiuron
and
Metabolites
in
Tissues
from
the
Oral
Administration
of
Tebuthiuron
for
28
Days
Diet
(ppm
tebuthiuron)
Tissue
Analyte
Concentration
1
(ppm)
Range
2
(ppm)
Average
3
(ppm)

8
fat
tebuthiuron
0.01
­
0.074
0.036
+
0.03
104
+
109
5
0.52
­
2.00
1.33
+
0.75
106
+
108
7
0.158
­
0.428
0.250
+
0.15
450
liver
tebuthiuron
0.359
­
1.20
0.666
+
0.46
104
+
109
5
28.4
­
41.6
33.3
+
7.2
106
+
108
7
11.2
­
18.0
14.6
+
3.4
kidney
tebuthiuron
0.107
­
0.244
0.155
+
0.77
104
+
109
5
10.5
­
15.4
13.5
+
2.1
106
+
108
7
5.79
­
8.78
6.80
+
1.7
muscle
tebuthiuron
0.210
­
0.370
0.280
+
0.082
104
+
109
5
8.96
­
13.6
11.2
+
2.3
106
+108
7
2.68
­
3.95
3.11
+
0.73
fat
tebuthiuron
0.064
­
0.140
0.100
+
0.038
104
+
109
5
5.03
­
6.64
5.61
+
0.89
106
+
108
7
0.830
­
1.26
1.01
+
0.22
1
Not
corrected
for
concurrent
method
recovery.
2
Range
of
average
of
duplicate
determinations
for
three
cows.
3
Average
of
duplicate
determinations
for
three
cows.
4
"<"
values
are
estimated
limits
of
detection.
5
Results
are
expressed
as
104
equivalents.
6
<0.01
values
were
assigned
0.01.
7
Results
are
expressed
as
106
equivalents.

Milk
samples
were
analyzed
for
residues
of
tebuthiuron
and
metabolites
104,
106,
109,
104(
OH),
and
109(
OH)
using
Method
GRM
92.08.
Metabolites
109
and
109(
OH)
were
converted
to
metabolites
104
and
104(
OH),
respectively,
in
an
initial
acid
hydrolysis.
The
hydrolysis
product
mixture
was
partitioned
with
ethyl
acetate
and
purified
on
a
neutral
alumina
solid
phase
extraction
cartridge.
A
separate
sample
was
required
for
metabolite
106.
The
maximum
incurred
residue
in
milk
at
the
45
ppm
feeding
level,
expressed
as
the
sum
of
tebuthiuron,
104
plus
109
as
104,
104(
OH)
plus
109(
OH)
as
104(
OH),
and
106.
See
Table
4.

Table
4:
Residues
of
Tebuthiuron
and
Metabolites
in
Milk
Diet
(ppm)
Day
1
Analyte
Concentration
2
(ppm)
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0
25
Tebuthiuron
<0.04
3
28
104
+
109
<0.02
28
104(
OH)
+
109(
OH)
<0.01
28
106
<0.01
45
6
12
4
Tebuthiuron
0.017;
0.023
(<
0.14)
5
104
+
109
0.550;
0.726
22
104(
OH)
+
109(
OH)
0.063;
0.116
5
106
0.118;
0.132
135
7
22
Tebuthiuron
5
0.227;
0.480
5
104
+
109
3.03;
3.38
22
104(
OH)
+
109(
OH)
0.143;
0.188
5
106
0.507;
0.626
450
8
22
Tebuthiuron
1.47;
3.18
25
104
+
109
23.0;
40.8
22
104(
OH)
+
109(
OH)
1.15;
1.64
28
9
106
4.13;
5.25
1
Day
of
plateau
of
residue,
unless
otherwise
indicated.
2
Not
corrected
for
concurrent
method
recovery.
First
entry
is
average
of
three
cows;
second
entry
is
maximum
residue.
For
104
+
109,
results
are
expressed
as
104
equivalents.
For
104(
OH)
+
109(
OH),
results
are
expressed
as
104(
OH)
equivalents.
3
"<"
values
are
estimated
limits
of
detection.
4
Residues
were
lower
on
subsequent
days,
except
one
cow
(0.035
ppm)
on
day
13.
5
Results
were
variable
among
cows
on
a
given
days
and
among
different
days.
The
residue
ranged
from
0.148
to
0.288
ppm
on
day
25,
0.205
ppm
average,
112%
recovery.
6
Actual
feeding
levels
were
71,
51,
and
56
ppm.
7
Actual
feeding
levels
were
192,
197,
and
136
ppm.
8
Actual
feeding
levels
were
903,
587,
and
646
ppm.
9
Residue
may
not
have
plateaued,
but
low
recovery
(40%)
obscures
trends.

The
average
residues
in
various
tissues
at
the
45
ppm
(7.3x),
135
ppm
(22x),
and
450
ppm
(73x)
feeding
levels,
expressed
as
the
sum
of
tebuthiuron,
104
+
109,
and
106
+
108;
and
the
total
residues
at
6.14
ppm
tebuthiuron,
assuming
a
linear
regression
relationship
between
diet
intake
and
residues,
are
summarized
in
Table
5a.

Table
5a:
Average
Residues
for
Each
Tissue
Based
on
Linear
Regression
Beef
Cattle
Diet
(ppm)
Liver
(ppm)
Muscle
(ppm)
Kidney
(ppm)
Fat
(ppm)

45ppm
(7.3x)
3.43
0.80
1.6
0.
31
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135ppm
(22x)
10.44
2.96
4.53
1.62
450ppm
(73x)
48.57
14.55
19.79
6.72
Calculated
Maximum
at
6.14
ppm
(1x)
0.646
0.193
0.264
0.090
For
milk,
the
average
residues
in
milk
at
the
45
ppm
(9.5x),
135
ppm
(28.5x),
and
450
ppm
(95x)
feeding
levels,
expressed
as
the
sum
of
tebuthiuron,
104
+
109,
and
104(
OH)
+
109(
OH),
and
106;
and
the
total
residues
at
4.73
ppm
tebuthiuron,
assuming
a
linear
regression
relationship
between
diet
intake
and
residues,
are
summarized
in
Table
5b.

Table
5b:
Average
Residues
for
Milk
Based
on
Linear
Regression
Dairy
Cattle
Diet
(ppm)
Milk
(ppm)

45ppm
(9.5x)
0.748
135ppm
(28.5x)
3.91
450ppm
(95x)
29.75
Calculated
Maximum
at
4.73
ppm
(1x)
0.296
Example:
Calculation
for
Liver
Step
1:
The
sum
of
the
average
of
tebuthiuron
residues,
average
104
+
109
residues,
and
106
+
108
residues
are
calculated
from
the
feeding
studies
(see
Table
4).
Average
refers
to
the
average
of
duplicate
analyses
per
each
of
the
three
cows.
Please
note
the
values
using
½
LOD.
45
ppm:
0.05
ppm
(parent)
+
1.73
ppm
(104
+
109)
+
1.65
ppm
(106
+
108)=
3.43
135
ppm:
0.129
ppm
(parent)
+
6.96
ppm
(104
+
109)
+
3.35
ppm
(106
+
108)=
10.44
450
ppm:
0.668
ppm
(parent)
+
33.25
ppm
(104
+
109)
+
14.65
ppm
(106
+
108)=
48.57
Step
2:
The
linear
relationship
(average
residues
versus
beef
cattle
diets)
for
liver
was
derived
from
Table
5a
using
linear
regression
graph
and
equation
to
determine
1x.

Table
6.
Summary
of
Tebuthiuron
and
its
Metabolites
in
Meat
and
Milk
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RAC
Anticipated
Residues
Chronic
(ppm)
Acute
(RDF)

Liver
0.
006
(0.646
ppm
x
1%
CT)
0.013
(0.646
ppm
x
2%
CT)

Kidney
0.
003
(0.264
ppm
x
1%
CT)
0.005
(0.264
ppm
x
2%
CT)

Muscle
0.002
(0.193
ppm
x
1%
CT)
0.004
(0.193
ppm
x
2%
CT)

Fat
0.
001
(0.090
ppm
x
1%
CT)
0.002
(0.090
ppm
x
2%
CT)

Milk
0.003
(0.296
ppm
x
1%
CT)
0.006
(0.296
ppm
x
2%
CT)

I.
DEEM™
Program
and
Consumption
Information
Tebuthiuron
acute
and
chronic
dietary
exposure
assessments
were
conducted
using
the
Dietary
Exposure
Evaluation
Model
(DEEM™)
software
Version
7.74,
which
incorporates
consumption
data
from
USDA's
Continuing
Surveys
of
Food
Intake
by
Individuals
(CSFII),
1989­
1992.
The
1989­
92
data
are
based
on
the
reported
consumption
of
more
than
10,000
individuals
over
three
consecutive
days,
and
therefore
represent
more
than
30,000
unique
"person
days"
of
data.
Foods
"as
consumed"
(e.
g.,
apple
pie)
are
linked
to
raw
agricultural
commodities
and
their
food
forms
(e.
g.,
apples­
cooked/
canned
or
wheat­
flour)
by
recipe
translation
files
internal
to
the
DEEM
software.
Consumption
data
are
averaged
for
the
entire
US
population
and
within
population
subgroups
for
chronic
exposure
assessment,
but
are
retained
as
individual
consumption
events
for
acute
exposure
assessment.

For
chronic
exposure
and
risk
assessment,
an
estimate
of
the
residue
level
in
each
food
or
food­
form
(e.
g.,
orange
or
orange­
juice)
on
the
commodity
residue
list
is
multiplied
by
the
average
daily
consumption
estimate
for
that
food/
food
form.
The
resulting
residue
consumption
estimate
for
each
food/
food
form
is
summed
with
the
residue
consumption
estimates
for
all
other
food/
food
forms
on
the
commodity
residue
list
to
arrive
at
the
total
estimated
exposure.
Exposure
estimates
are
expressed
in
mg/
kg
body
weight/
day
and
as
a
percent
of
the
cPAD.
This
procedure
is
performed
for
each
population
subgroup.
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For
acute
exposure
assessments,
individual
one­
day
food
consumption
data
are
used
on
an
individual­
by­
individual
basis.
The
reported
consumption
amounts
of
each
food
item
can
be
multiplied
by
a
residue
point
estimate
and
summed
to
obtain
a
total
daily
pesticide
exposure
for
a
deterministic
(Tier
1
or
Tier
2)
exposure
assessment,
or
"matched"
in
multiple
random
pairings
with
residue
values
and
then
summed
in
a
probabilistic
(Tier
3/
4)
assessment.
The
resulting
distribution
of
exposures
is
expressed
as
a
percentage
of
the
aPAD
on
both
a
user
(i.
e.,
those
who
reported
eating
relevant
commodities/
food
forms)
and
a
per­
capita
(i.
e.,
those
who
reported
eating
the
relevant
commodities
as
well
as
those
who
did
not)
basis.
In
accordance
with
HED
policy,
per
capita
exposure
and
risk
are
reported
for
all
tiers
of
analysis.
However,
for
tiers
1
and
2,
significant
differences
in
user
vs.
per
capita
exposure
and
risk
are
identified
and
noted
in
the
risk
assessment.

II.
Results/
Conclusions
Acute
Dietary
Exposure
Analysis
A
Tier
2
acute
and
chronic
dietary
risk
assessments
were
conducted
for
all
supported
tebuthiuron
food
uses.
Dietary
risk
estimates
are
provided
for
the
general
U.
S.
population
(chronic
only)
and
females
13­
50
years
(acute).
This
assessment
concludes
that
for
all
included
commodities,
the
acute
risk
estimates
are
below
the
Agency's
level
of
concern
(<
100%
aPAD)
at
the
95
th
exposure
percentile
for
females
13­
50
years
(<
1%
of
the
aPAD).
This
assessment
also
concludes
that
for
all
commodities,
the
chronic
risk
estimates
are
below
the
Agency's
level
of
concern
(<
100%
cPAD)
for
the
general
U.
S.
population
(<
1%
of
the
cPAD)
and
all
population
subgroups.
The
results
reported
in
Table
7
are
for
females
13­
50
years
only
for
acute
dietary
exposure
analysis
and
Table
8
is
the
results
of
chronic
dietary
exposure
analysis.

Table
7.
Results
of
Acute
Dietary
Exposure
Analysis
Population
Subgroup
95
th
Percentile
99
th
Percentile
99.9
th
Percentile
Exposure
(mg/
kg/
day)
%
aPAD
Exposure
(mg/
kg/
day)
%
aPAD
Exposure
(mg/
kg/
day)
%
aPAD
Females
13­
50
years
old
0.000078
<1
0.000121
<1
0.000207
<1
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Chronic
Dietary
Exposure
Analysis
Table
8.
Results
of
Chronic
Dietary
Exposure
Analysis
Population
Subgroup
Exposure
(mg/
kg/
day)
%
cPAD
U.
S.
Population
(total)
0.000023
<1
All
Infants
(<
1
year)
0.
000036
<1
Children
1­
6
years
0.
000083
<1
Children
7­
12
years
0.
000043
<1
Females
13­
50
0.000013
<1
Males
13­
19
0.000025
<1
Males
20+
years
0.
000012
<1
Seniors
55+
0.000012
<1
III.
Discussion
of
Uncertainties
C
Residue
Issues
­
The
Agency
notes
that
field
trial
data
are
generally
considered
by
HED
as
an
upper­
end
or
a
worst
case
scenario
of
possible
residues
and
are
more
suited
to
the
requirements
of
tolerance
setting,
because
it
requires
the
highest
rates
of
application
and
shortest
PHI,
than
to
the
requirements
of
dietary
exposure
assessment
(when
the
most
realistic
estimate
is
desired).

IV.
List
of
Attachments
Attachment
1:
Acute
Residue
Input
Data
for
DEEM
Analysis
for
Tebuthiuron
Attachment
2:
Acute
Residue
Analysis
for
Tebuthiuron
Attachment
3:
Chronic
Residue
Input
Data
for
DEEM
Analysis
for
Tebuthiuron
Attachment
4:
Chronic
Residue
Analysis
for
Tebuthiuron
DP
Barcode:
D281821
Dietary
exposure
assessment
/
14
Tebuthiuron
/
105501
14
cc:
S.
Piper
(CEB),
RF
RDI:
ChemSAC:
3/
27/
02;
Secondary
Reviewers:
4/
1/
02;
FBSuhre
4/
8/
02
7509C:
CEB:
CM­
2:
RM
810F:
308­
2717:
Tebuthiuron­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­

­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­


Attachment
1:
Acute
Residue
Input
Data
for
DEEM
Analysis
for
Tebuthiuron
U.
S.
Environmental
Protection
Agency
Ver.
7.76
DEEM
Acute
analysis
for
TEBUTHIURON
Residue
file
name:
C:\
deem\
tebuthiruon\
tebuthiuronacute.
RS7
Analysis
Date
04­
02­
2002
Residue
file
dated:
04­
02­
2002/
15:
58:
50/
8
Reference
dose:
aRfD
=
0.083
mg/
kg
bw/
day
NOEL
=
25
mg/
kg
bw/
day
Comment:
Assumes
3x
factor
for
FQPA­
females
13­
50
yrs
only
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­


Food
Crop
Food
Name
Def
Res
Adj.
Factors
RDL
Code
Grp
(ppm)
#1
#2
Ind
­­­­
­­­­
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
­­­­­­­­­­
­­­­­­
­­­­­­
­­­
318
D
Milk­
nonfat
solids
0.296000
1.000
0.020
319
D
Milk­
fat
solids
0.296000
1.000
0.020
320
D
Milk
sugar
(lactose)
0.296000
1.000
0.020
321
M
Beef­
meat
byproducts
0.646000
1.000
0.020
322
M
Beef­
other
organ
meats
0.646000
1.000
0.020
323
M
Beef­
dried
0.193000
1.920
0.020
324
M
Beef­
fat
w/
o
bones
0.090000
1.000
0.020
325
M
Beef­
kidney
0.264000
1.000
0.020
326
M
Beef­
liver
0.646000
1.000
0.020
327
M
Beef­
lean
(fat/
free)
w/
o
bones
0.193000
1.000
0.020
328
M
Goat­
meat
byproducts
0.646000
1.000
0.020
329
M
Goat­
other
organ
meats
0.646000
1.000
0.020
330
M
Goat­
fat
w/
o
bone
0.090000
1.000
0.020
331
M
Goat­
kidney
0.264000
1.000
0.020
332
M
Goat­
liver
0.646000
1.000
0.020
333
M
Goat­
lean
(fat/
free)
w/
o
bone
0.193000
1.000
0.020
334
M
Horsemeat
0.193000
1.000
0.020
336
M
Sheep­
meat
byproducts
0.646000
1.000
0.020
337
M
Sheep­
other
organ
meats
0.646000
1.000
0.020
338
M
Sheep­
fat
w/
o
bone
0.090000
1.000
0.020
339
M
Sheep­
kidney
0.264000
1.000
0.020
340
M
Sheep­
liver
0.646000
1.000
0.020
341
M
Sheep­
lean
(fat
free)
w/
o
bone
0.193000
1.000
0.020
398
D
Milk­
based
water
0.296000
1.000
0.020
Attachment
2:
Acute
Residue
Analysis
for
Tebuthiuron
U.
S.
Environmental
Protection
Agency
Ver.
7.76
DEEM
ACUTE
Analysis
for
TEBUTHIURON
(1989­
92
data)
Residue
file:
tebuthiuronacute.
RS7
Adjustment
factor
#2
used.
Analysis
Date:
04­
02­
2002/
15:
54:
34
Residue
file
dated:
04­
02­
2002/
15:
51:
52/
8
NOEL
(Acute)
=
25.000000
mg/
kg
body­
wt/
day
Daily
totals
for
food
and
foodform
consumption
used.
Run
Comment:
"Assumes
3x
factor
for
FQPA­
females
13­
50
yrs"
===============================================================================
DP
Barcode:
D281821
Dietary
exposure
assessment
/
15
Tebuthiuron
/
105501
15
Summary
calculations
(per
capita):

95th
Percentile
99th
Percentile
99.9th
Percentile
Exposure
%
aRfD
MOE
Exposure
%
aRfD
MOE
Exposure
%
aRfD
MOE
­­­­­­­­­­
­­­­­­­
­­­­­­­­
­­­­­­­­­­
­­­­­­­
­­­­­­­­
­­­­­­­­­­
­­­­­­­
­­­­­­­­
Females
13+
(preg/
not
nursing):
0.000109
0.13
229030
0.000128
0.15
195001
0.000195
0.24
128105
Females
13+
(nursing):
0.000118
0.14
211948
0.000183
0.22
136354
0.000195
0.23
128528
Females
13­
19
(not
preg
or
nursing):
0.000098
0.12
255390
0.000175
0.21
142798
0.000235
0.28
106564
Females
13­
50
yrs:
0.000078
0.09
319551
0.000121
0.15
206558
0.000207
0.25
120907
Attachment
3:
Chronic
Residue
Input
Data
for
DEEM
Analysis
for
Tebuthiuron
U.
S.
Environmental
Protection
Agency
Ver.
7.76
DEEM
Chronic
analysis
for
TEBUTHIURON
1989­
92
data
Residue
file:
C:\
deem\
tebuthiruon\
tebuthirchronic.
RS7
Adjust.
#2
used
Analysis
Date
04­
02­
2002
Residue
file
dated:
04­
02­
2002/
15:
52:
42/
8
Reference
dose
(RfD)
=
0.14
mg/
kg
bw/
day
Comment:
Assumes
1x
factor
for
FQPA
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
Food
Crop
RESIDUE
Adj.
Factors
Code
Grp
Food
Name
(ppm)
#1
#2
­­­­
­­­­
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
­­­­­­­­­­
­­­­­­
­­­­­­
318
D
Milk­
nonfat
solids
0.296000
1.000
0.010
319
D
Milk­
fat
solids
0.296000
1.000
0.010
320
D
Milk
sugar
(lactose)
0.296000
1.000
0.010
321
M
Beef­
meat
byproducts
0.646000
1.000
0.010
322
M
Beef­
other
organ
meats
0.646000
1.000
0.010
323
M
Beef­
dried
0.193000
1.920
0.010
324
M
Beef­
fat
w/
o
bones
0.090000
1.000
0.010
325
M
Beef­
kidney
0.264000
1.000
0.010
326
M
Beef­
liver
0.646000
1.000
0.010
327
M
Beef­
lean
(fat/
free)
w/
o
bones
0.193000
1.000
0.010
328
M
Goat­
meat
byproducts
0.646000
1.000
0.010
329
M
Goat­
other
organ
meats
0.646000
1.000
0.010
330
M
Goat­
fat
w/
o
bone
0.090000
1.000
0.010
331
M
Goat­
kidney
0.264000
1.000
0.010
332
M
Goat­
liver
0.646000
1.000
0.010
333
M
Goat­
lean
(fat/
free)
w/
o
bone
0.193000
1.000
0.010
334
M
Horsemeat
0.193000
1.000
0.010
336
M
Sheep­
meat
byproducts
0.646000
1.000
0.010
337
M
Sheep­
other
organ
meats
0.646000
1.000
0.010
338
M
Sheep­
fat
w/
o
bone
0.090000
1.000
0.010
339
M
Sheep­
kidney
0.264000
1.000
0.010
340
M
Sheep­
liver
0.646000
1.000
0.010
341
M
Sheep­
lean
(fat
free)
w/
o
bone
0.193000
1.000
0.010
398
D
Milk­
based
water
0.296000
1.000
0.010
DP
Barcode:
D281821
Dietary
exposure
assessment
/
16
Tebuthiuron
/
105501
16
Attachment
4:
Chronic
Residue
Analysis
for
Tebuthiuron
U.
S.
Environmental
Protection
Agency
Ver.
7.76
DEEM
Chronic
analysis
for
TEBUTHIURON
(1989­
92
data)
Residue
file
name:
C:\
deem\
tebuthiruon\
tebuthirchronic.
RS7
Adjustment
factor
#2
used.
Analysis
Date
04­
02­
2002/
16:
03:
16
Residue
file
dated:
04­
02­
2002/
15:
52:
42/
8
Reference
dose
(RfD,
Chronic)
=
.14
mg/
kg
bw/
day
COMMENT
1:
Assumes
1x
factor
for
FQPA
===============================================================================
Total
exposure
by
population
subgroup
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­


Total
Exposure
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
Population
mg/
kg
Percent
of
Subgroup
body
wt/
day
Rfd
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
­­­­­­­­­­­­­
­­­­­­­­­­­­­­­
U.
S.
Population
(total)
0.000023
0.0%

U.
S.
Population
(spring
season)
0.000023
0.0%
U.
S.
Population
(summer
season)
0.000022
0.0%
U.
S.
Population
(autumn
season)
0.000024
0.0%
U.
S.
Population
(winter
season)
0.000023
0.0%

Northeast
region
0.000023
0.0%
Midwest
region
0.000026
0.0%
Southern
region
0.000021
0.0%
Western
region
0.000023
0.0%

Hispanics
0.000025
0.0%
Non­
hispanic
whites
0.000023
0.0%
Non­
hispanic
blacks
0.000020
0.0%
Non­
hisp/
non­
white/
non­
black
0.000024
0.0%

All
infants
(<
1
year)
0.000036
0.0%
Nursing
infants
0.000007
0.0%
Non­
nursing
infants
0.000048
0.0%
Children
1­
6
yrs
0.000083
0.1%
Children
7­
12
yrs
0.000043
0.0%

Females
13­
19
(not
preg
or
nursing)
0.000019
0.0%
Females
20+
(not
preg
or
nursing)
0.000011
0.0%
Females
13­
50
yrs
0.000013
0.0%
Females
13+
(preg/
not
nursing)
0.000022
0.0%
Females
13+
(nursing)
0.000019
0.0%

Males
13­
19
yrs
0.000025
0.0%
Males
20+
yrs
0.000012
0.0%
Seniors
55+
0.000012
0.0%
Pacific
Region
0.000023
0.0%

­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
