UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
January
27,
2006
MEMORANDUM
SUBJECT:
Thidiazuron:
HED
Response
to
RED
Comments.
PC
Code:
120301,
Case
#:
4092,
DP
Barcode:
D325893
FROM:
Toiya
Goodlow,
Chemist
and
Risk
Assessor
Reregistration
Branch
1
Health
Effects
Division
(
7509C)

THROUGH:
Whang
Phang,
Ph.
D.,
Branch
Senior
Scientist
Reregistration
Branch
1
Health
Effects
Division
(
7509C)

TO:
John
Pates
Jr.,
Chemical
Review
Manager
Special
Review
and
Reregistration
Division
(
7508C)

This
document
was
written
in
response
to
comments
submitted
for
the
Thidiazuron
Reregistration
Eligibility
Decision
Document
(
RED).
All
comments
have
been
reviewed
by
RRB1/
HED
and
incorporated
into
the
RED
document
as
deemed
appropriate
by
the
Agency.

Changes
include
the
following:

°
The
statement
of
revocation
for
the
cottonseed
hulls
tolerance
has
been
revised
for
consistency.

°
Table
2.1
has
been
changed
to
reflect
a
maximum
seasonal
application
rate
of
0.125
lb
ai/
A
for
EPA
registration
#
264­
00634.

°
The
dosage
level
in
food
and
exaggeration
rate
for
the
ruminant
feeding
study
has
been
corrected.

°
The
1
month
plant
back
interval
(
PBI)
has
been
changed
to
2
weeks
for
small
grain
crops.

1
of
2
2
of
2
The
following
comments
were
not
revised
in
the
RED:

°
Comment:
Most
of
the
studies
cited
for
the
product
chemistry
data
requirements
are
not
the
studies
supporting
the
registration
of
Bayer
CropScience's
registration
for
thidiazuron.

Response:
The
studies
cited
in
the
RED
reflect
the
references
the
Agency
has
on
file
for
the
thidizuron
product
chemistry
data
requirements.
Please
advise
HED
if
there
are
other
relevant
references
available
for
the
Bayer
CropScience
registration.

References
Goodlow,
Toiya.
DP
Barcode:
D319302.
August
31,
2005.
Thidiazuron:
Revised
HED
Chapter
of
the
Reregistration
Eligibility
Decision
Document
(
RED),
Phase
3­
Public
Comments.

7509C:
RRB1:
TGoodlow:
CM#
2:
Rm
722H:
308­
0070:
1/
27/
06
WPhang:
1/
27/
06
