UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
July
5,
2002
CERTIFIED
MAIL
Dear
Registrant:

This
is
to
inform
you
that
on
July
5,
2002,
the
Environmental
Protection
Agency
(hereafter
referred
to
as
EPA
or
the
Agency)
completed
its
"Report
of
FQPA
Tolerance
Reassessment
Progress
and
Interim
Risk
Management
Decision
(TRED)
for
Tebuthiuron".
A
Notice
of
Availability,
soliciting
public
comment
for
a
30
day
period,
will
be
published
in
the
Federal
Register
(FR)
Notice
shortly.

FFDCA,
as
amended,
requires
EPA
to
reassess
all
the
tolerances
for
registered
chemicals
in
effect
on
or
before
the
date
of
the
enactment
of
the
Food
Quality
Protection
Act
(FQPA)
in
August
of
1996
against
the
new
safety
standard
adopted
in
the
FQPA.
In
reassessing
these
tolerances,
the
Agency
must
consider,
among
other
things,
aggregate
risks
from
non­
occupational
sources
of
pesticide
exposure,
whether
there
is
increased
susceptibility
to
infants
and
children,
and
the
cumulative
effects
of
pesticides
with
a
common
mechanism
of
toxicity.
The
tolerances
are
considered
reassessed
once
the
safety
finding
has
been
made
or
a
modification
or
revocation
occurs.
A
reregistration
eligibility
decision
(RED)
for
Tebuthiuron,
was
completed
in
April
1994,
prior
to
FQPA
enactment.
Therefore,
it
needed
to
be
updated
to
reassess
the
tolerances
under
the
FQPA
standard.

The
Agency
has
evaluated
the
dietary
risk
associated
with
Tebuthiuron
and
has
determined
that
there
is
a
reasonable
certainty
that
no
harm
to
any
population
subgroup
will
result
from
exposure
to
Tebuthiuron
when
considering
dietary
exposure
and
all
other
non­
occupational
sources
of
pesticide
exposure
for
which
there
is
reliable
information.
Therefore,
no
mitigation
measures
are
needed,
and
the
tolerances
established
for
residues
of
Tebuthiuron
in/
on
raw
agricultural
commodities
are
now
considered
reassessed
as
safe
under
section
408(
q)
of
the
FFDCA.

FQPA
requires
that
EPA
consider
"available
information"
concerning
the
cumulative
effects
of
a
particular
pesticide's
residues
and
"other
substances
that
have
a
common
mechanism
of
toxicity."
The
reason
for
consideration
of
other
substances
is
due
to
the
possibility
that
lowlevel
exposures
to
multiple
chemical
substances
that
cause
a
common
toxic
effect
by
a
common
mechanism
could
lead
to
the
same
adverse
health
effect,
as
would
a
higher
level
of
exposure
to
any
of
the
other
substances
individually.
EPA
did
not
perform
a
cumulative
risk
assessment
as
part
of
this
reregistration
review
of
Tebuthiuron,
because
the
Agency
has
not
determined
if
there
are
any
other
chemical
substances
that
have
a
mechanism
of
toxicity
common
with
that
of
Tebuthiuron.
If
EPA
identifies
other
substances
that
share
a
common
mechanism
of
toxicity
with
Tebuthiuron,
then
a
cumulative
risk
assessment
will
be
conducted
that
includes
Tebuthiuron
once
the
final
framework
EPA
will
use
for
conducting
cumulative
risk
assessments
is
available.

The
Agency's
human
health
findings
for
the
pesticide
Tebuthiuron,
were
discussed
in
a
closure
conference
call,
and
are
summarized
in
the
attached
chemical
overview
of
the
risk
assessments.
These
risk
assessments
and
other
documents
pertaining
to
the
Tebuthiuron
tolerance
reassessment
decision
are
listed
at
the
end
of
this
document
and
are
available
on
the
Internet
at
http://
www.
epa.
gov/
pesticides/
reregistration/
status.
htm
and
the
public
docket
for
viewing.

Tolerances
for
residues
of
tebuthiuron
are
related
to
the
consumption
of
secondary
residues
in
meat
and
milk
from
livestock
fed
tebuthiuron­
treated
grass
forage
and
hay.
The
registered
uses
of
tebuthiuron
are
classified
in
40
CFR§
180.390.

The
40
CFR
tolerance
expression
under
40
CFR§
180.390
must
be
modified
as
follows:

CFR§
180.390
Tebuthiuron;
tolerances
for
residues
(a)
Tolerances
are
established
for
the
combined
residues
of
the
herbicide
tebuthiuron
(N­[
5­(
1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl­
N,
N'­
dimethylurea)
and
its
metabolites
N­[
5­(
2­
hydroxy­
1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl]­
N,
N'dimethylurea
–[
5­(
1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl]­
N­
methylurea,
and
N
5­(
1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl]­
N'­
hydroxymethyl­
N­
methylurea
in
or
on
the
following
agricultural
commodities:

Grass,
hay
Grass,
forage
(b)
Tolerances
are
established
for
the
combined
residues
of
the
herbicide
tebuthiuron
(N­[
5­(
1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl­
N,
N'­
dimethylurea)
and
its
metabolites
N­[
5­(
1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl]­
N­
methylurea,
–[
5­
(1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl]
urea,
2­
dimethylethyl­
5­
amino­
1,
3,
4thiadiazole
and
N­[
5­(
1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl]­
N'­
hydroxymethylN
methylurea
in
or
on
the
following
raw
agricultural
commodities:

Cattle,
fat
Cattle,
mbyp
Cattle,
meat
Goats,
fat
Goats,
mbyp
Goats,
fat
Horses,
fat
Horses,
mbyp
Horses,
meat
Sheep,
fat
Sheep,
mbyp
Sheep,
meat
(c)
A
tolerance
is
established
for
the
combined
residues
of
the
herbicide
tebuthiuron
(N­[
5­(
1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl­
N,
N'­
dimethylurea)
and
its
metabolites
N­[
5­(
1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl]­
N­
methylurea,
N­[
5
2­
hydroxy­
1,
1­
dimethylethyl)­
1,
3,
4­
thiadiazol­
2­
yl]­
N­
methylurea,
N­[
5­(
1,
1dimethylethyl
1,
3,
4­
thiadiazol­
2­
yl]
urea,
N­[
5­(
1,
1­
dimethylethyl)­
1,
3,
4thiadiazol
2­
yl]­
N'­
hydroxymethyl­
N­
dimethylurea,
and
N­[
5­(
2­
hydroxy­
1,
1dimethylethyl
1,
3,
4­
thiadiazol­
2­
yl]­
N'­
hydroxymethyl­
N­
methylurea
in
or
on
the
following
raw
agricultural
commodity:

Milk
The
Codex
Commission
has
established
that
there
are
no
maximum
residue
limits
(MRLs)
for
residues
of
tebuthiuron
in/
on
various
raw
agricultural
and
processed
commodities.
Therefore,
issues
of
compatibility
with
respect
to
U.
S.
tolerances
and
Codex
MRLs
do
not
exist.

Tebuthiuron
Tolerances
Commodity
Current
Tolerance
(ppm)
Reassessed
Tolerance
(ppm)
Tolerance
Reassessment
Cattle,
Fat
2
1
Lowered
Cattle,
MBYP
2
5
Raised
Cattle,
Meat
2
1
Lowered
Goats,
Fat
2
1
Lowered
Goats,
MBYP
2
5
Raised
Goats,
Meat
2
1
Lowered
Grasses,
Forage
20
10
Lowered
Grasses,
Hay
20
10
Lowered
Horses,
Fat
2
1
Lowered
Horses,
MBYP
2
5
Raised
Horses,
Meat
2
1
Lowered
Milk
0.
3
0.
8
Raised
Sheep,
Fat
2
1
Lowered
Sheep,
MBYP
2
5
Raised
Sheep,
Meat
2
1
Lowered
A
generic
Data
Call­
In
(DCI)
that
outlines
further
data
requirements
for
this
chemical
will
be
prepared
and
mailed
to
you
in
the
near
future.

If
you
have
questions
on
this
document,
please
contact
the
Chemical
Review
Manager,
Wilhelmena
Livingston,
at
(703)
308­
8025.

Lois
A.
Rossi,
Director
Special
Review
and
Reregistration
Attachments:

TRED
for
Tebuthiuron
Addendum
to
TRED
Drinking
Water
Assessment
for
Tebuthiuron
Product
Chemistry
Chapter
for
the
TRED
Residue
Chemistry
Chapter
for
the
TRED
Acute
and
Chronic
Dietary
Exposure
Assessment
for
the
TRED
Toxicology
Chapter
for
the
TRED
Third
Report
of
the
HIARC
Committee
Report
of
the
FQPA
Safety
Factor
Committee
The
Outcome
of
the
HED
MARC
Meeting
