July
1,
2002
Mr.
Dirk
V.
Helder
Office
of
Pesticide
Programs
(H7508C)
U.
S.
Environmental
Protection
Agency
1921
Jefferson
Highway
Arlington,
VA
22202
Dear
Mr.
Helder
Subject:
Dupont
Response
to
Draft
Hexazinone
Tolerance
Reassessment
Eligibility
Document
(TRED)

We
appreciate
the
opportunity
to
comment
on
the
draft
TRED
for
hexazinone.
First,
we
compliment
the
Agency
on
the
depth
completeness
of
the
data
base
review.

In
some
areas
covered
in
the
review
we
have
no
significant
comments
and
in
others,
particularly
toxicology,
we
have
extensive
comments
which
are
contained
in
the
attached
documents
identified
for
each
section.

The
most
significant
recommendation,
in
our
view,
contained
in
the
draft
documents
pertains
to
the
revocation
of
tolerances
associated
use
of
hexazinone
on
grass.
We
acknowledge
that
guidelines
and
interpretations
regarding
the
practicality
of
grower
over
cattle
grazing
intervals
have
changed
since
data
supporting
this
use
pattern
were
last
submitted.
However,
as
indicated
review,
this
is
a
rather
minor
use
and
our
information
indicates
that
the
current
label
restrictions
regarding
cutting
and
grazing
being
complied
with.
Therefore,
the
tolerances
supporting
the
use
are
sufficient.
Given
the
foregoing,
we
request
that
the
existing
tolerances
and
use
pattern
be
maintained
while
we
conduct
new
residue
work
to
support
EPA's
interpretation
regarding
a
zero
grazing
interval.

We
understand
that
our
recently
submitted
Rabbit
Developmental
Toxicity
Study
(DuPont­
7405,
MRID
45677801)
was
not
in
time
to
be
included
in
the
Draft
TRED.
In
view
of
the
pivotal
importance
of
this
study
to
the
overall
conclusions
of
the
final
(specifically,
the
current
proposal
to
declare
a
significant
gap
in
the
toxicology
data
base,
the
selection
of
appropriate
end
points
regulatory
purposes
and
the
imposition
of
an
additional
10X
safety
factor
due
to
an
incomplete
data
base),
we
respectfully
request
this
study
be
reviewed
as
quickly
as
possible
to
be
included
in
the
final
TRED.

We
also
note
in
the
toxicology
review
that
"Gene
mutation
–
bacterial"
is
listed
as
an
unsatisfied
requirement.
We
have
recently
submitted
(June
28,
2002,
no
MRID
yet
assigned)
a
new
Ames
assay
with
the
75
DF
formulation
which
we
believe
will
satisfy
requirement.

Finally,
we
do
not
believe
a
28­
day
inhalation
study
should
be
required
until
the
existing
and
submitted
21­
day
inhalation
study
(MRID
00063972)
has
been
reviewed
Again,
we
appreciate
this
opportunity
to
comment
and
look
forward
to
our
continued
collaboration.

Sincerely,

Thomas
F.
Stommel
Global
Product
Reg.
Mgr.
