UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
MEMORANDUM
June
20,
2006
SUBJECT:
Triadimenol:
HED
Response
to
Comments
Received
During
the
Public
Comment
Phase
(
Docket
ID
Number
EPA­
HQ­
OPP­
2006­
0038/
Closed
4/
17/
06).

DP
Barcode:
328604
FROM:
Richard
Griffin,
Risk
Assessor
Reregistration
Branch
II
Health
Effects
Division
(
HED)

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

TO:
John
Pates,
Jr.,
Chemical
Review
Manager
Veronique
Lacapra,
Team
Leader
Reregistration
Branch
I
Special
Review
and
Reregistration
Division
(
7508P)

As
part
of
the
reregistration
process
for
triadimenol,
this
memo
is
the
HED
response
to
public
comments
concerning
the
HED
human
health
risk
assessment
dated
February
9,
2006
(
and
supporting
documents).
This
response
is
specific
to
the
comments
received
from
the
primary
registrant
(
Bayer
CropScience)
on
April
13,
and
April
17,
2006.
3
Product
/
Residue
Chemistry
1.
The
2/
9/
06
risk
assessment
listed
a
number
of
product
and
residue
chemistry
requirements
for
triadimenol;
including
metabolism
studies;
storage
stability
studies;
field
trial
data
for
wheat,
corn,
and
cotton;
and
a
processing
study
in
wheat.
Concerning
metabolism
in
plants
the
assessment
stated;
"
Separate
metabolism
studies
with
triazole­
14C
and
phenyl­
14C
labeled
triadimenol
applied
as
a
seed
treatment
to
wheat
or
corn
and
cotton
should
be
conducted
to
confirm
the
residues
of
concern."

As
a
response,
Bayer
has
submitted
four
additional
plant
metabolism
studies,
and
a
summary
of
all
plant
metabolism
studies
titled;
"
Regulatory
Recommendations
and
Residue
Chemistry
Deficiencies."
With
these
submissions,
Bayer
seeks
a
waiver
for
any
additional
data
concerning
plant
metabolism.
HED
notes,
however,
that
any
remaining
data
deficiencies,
concerning
plant
metabolism,
would
not
significantly
impact
the
triadimenol
dietary
risk
assessment.
HED
will
review
the
studies,
and
assess
the
waiver
request,
at
a
later
date.

Toxicology
2.
The
2/
9/
06
risk
assessment
also
listed
two
neurotoxicity
studies,
acute
and
subchronic,
as
triadimenol
data
gaps
(
the
triadimenol
assessment
relied
principally
on
triadimefon
toxicity
data
to
establish
endpoints).
Based
on
available
data
on
the
similar
effects,
similar
structure,
and
similar
mode
of
action
of
triadimefon
and
triadimenol,
Bayer
concurs
with
the
Agency's
use
of
triadimefon
data
to
support
triadimenol
risk
assessment.
At
this
time
the
Agency
will
not
require
the
submission
of
two
new
neurotoxicity
with
triadimenol.

3.
As
the
case
with
triadimefon,
Bayer
agrees
with
the
Agency's
use
of
the
triadimefon
subchronic
neurotoxicity
study
for
acute
(
aPAD)
and
chronic
(
cPAD)
dietary
risk
assessment.
Bayer,
however,
believes
that
the
dose
level,
or
"
Point
of
Departure",
may
be
several­
fold
higher
than
the
NOAELs
reported
in
these
studies.
Bayer
indicates
they
are
currently
evaluating
the
data
from
this
study
to
assess
the
appropriate
POD
for
risk
assessment.

4.
Bayer's
concluding
comments
to
the
Agency's
risk
assessment
for
triadimenol
concern
the
Toxicology
Requirements
Table
(
or
Appendix
Table
1).

Bayer
notes
the
21­
day
dermal
toxicity,
listed
as
not
required
by
the
Agency,
should
be
required.
The
Agency
agrees
and
the
21­
day
study
is,
in
fact,
required
for
triadimenol.

Bayer
notes
the
90­
day
inhalation
toxicity
study,
listed
as
required,
is
not
discussed
in
the
risk
assessment.
The
Agency
agrees
with
Bayer,
and
a
rationale
will
be
provided
in
a
revised
risk
assessment
for
triadimenol.
4
Bayer
notes
the
dermal
penetration
study,
listed
as
required,
is
not
actually
needed
for
risk
assessment,
since
the
15­
day
dermal
toxicity
study
is
an
acceptable
guideline
study.
The
Agency
agrees
with
Bayer
on
this
issue
and
does
not
currently
require
a
new
dermal
penetration
study.

Bayer
notes
the
list
of
special
ocular
effects
in
the
toxicology
requirement
table
and
believes
it
is
not
appropriate
to
include
these.
The
Agency
re­
states
that
these
studies
are
not
required
for
triadimenol.
