UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
August
1,
2002
CERTIFIED
MAIL
Tom
Stommel
Dupont
Stine­
Haskell
Research
Center
PO
Box
30
Newark,
DE
19714
Dear
Mr.
Stommel:

This
is
the
Environmental
Protection
Agency's
(hereafter
referred
to
as
EPA
or
the
Agency)
"Report
of
the
Food
Quality
Protection
Act
(FQPA)
Tolerance
Reassessment
Progress
and
Risk
Management
Decision
(TRED)
for
Hexazinone,"
which
was
approved
on
August
1,
2002.
A
Notice
of
Availability
of
this
tolerance
reassessment
decision
will
be
published
in
the
Federal
Register
(FR)
shortly.

The
Federal
Food,
Drug
and
Cosmetic
Act
(FFDCA),
as
amended
by
FQPA,
requires
EPA
to
reassess
all
the
tolerances
for
registered
chemicals
in
effect
on
or
before
the
date
of
the
enactment
of
the
FQPA,
which
was
August
of
1996.
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.
Once
a
safety
finding
has
been
made
that
aggregate
risks
are
not
of
concern,
the
tolerances
are
considered
reassessed.
A
Reregistration
Eligibility
Decision
(RED)
for
hexazinone
was
completed
in
September,
1994,
prior
to
FQPA
enactment.
Therefore,
the
tolerances
need
to
be
reassessed
to
meet
the
FQPA
standard.

The
Agency
has
evaluated
the
dietary
risk
associated
with
hexazinone
and
has
determined
that
there
is
a
reasonable
certainty
that
no
harm
to
any
population
subgroup
will
result
from
aggregate
exposure
to
hexazinone
when
considering
dietary,
drinking
water,
and
residential
exposure
and
all
other
non­
occupational
sources
of
pesticide
exposure
for
which
there
is
reliable
information.
There
are
no
registered
residential
uses
for
hexazinone.

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
considering
other
substances
is
because
of
the
possibility
that
low­
level
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
review
of
hexazinone,
2
because
the
Agency
has
not
determined
that
there
are
any
other
chemical
substances
that
have
a
mechanism
of
toxicity
common
with
that
of
hexazinone.
If
EPA
identifies
other
substances
that
share
a
common
mechanism
of
toxicity
with
hexazinone,
then
a
cumulative
risk
assessment
will
be
conducted
that
includes
hexazinone
once
the
final
framework
EPA
will
use
for
conducting
cumulative
risk
assessments
is
available.
Further,
EPA
is
in
the
process
of
developing
criteria
for
characterizing
and
testing
endocrine
disrupting
chemicals
and
plans
to
implement
an
Endocrine
Disruptor
Screening
Program.
Hexazinone
will
be
reevaluated
at
that
time
and
additional
studies
may
be
required.

The
Agency's
human
health
findings
for
the
pesticide
hexazinone,
were
discussed
in
a
closure
conference
call,
and
are
summarized
in
the
enclosed
Hexazinone
Overview
and
Hexazinone
Summary
of
the
risk
assessments.
The
risk
assessments
and
other
documents
pertaining
to
the
hexazinone
tolerance
reassessment
decision
are
available
on
the
Internet
at
http://
www.
epa.
gov/
pesticides/
reregistration/
status.
htm
and
are
in
the
public
docket
for
viewing.

The
Agency
has
reassessed
all
25
tolerances
for
hexazinone
and
can
make
a
FQPA
safety
determination.
Anticipated
residues
for
commodities
included
in
the
dietary
risk
assessment
are
equal
to
the
tolerance
levels
and
it
was
assumed
that
100%
of
each
crop
was
treated.
Acute
and
chronic
dietary
risks
from
exposure
to
hexazinone
does
not
exceed
the
Agency's
level
of
concern.
Tolerances
for
residues
of
hexazinone
in/
on
plant,
livestock,
and
processed
commodities
are
currently
expressed
in
terms
of
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone).

Because
existing
data
were
inadequate
to
calculate
residue
estimates
for
pasture
and
rangeland
grass
and
grass
hay,
EPA
constructed
the
maximum
theoretical
dietary
burden
(MTDB)
of
hexazinone
to
livestock
using
protective
assumptions
for
the
contributions
of
other
hexazinone­
treated
feed
items.
Thus,
tolerances
for
meats
and
milk
can
be
reassessed.
Additional
field
trial
data
for
grass
forage
and
grass
hay,
as
well
as
rotational
crop
studies
for
corn
and
wheat
are
required.
Because
of
the
relatively
low
volume
of
use
on
pasture
and
rangeland,
data
from
these
confirmatory
studies
are
not
expected
to
significantly
change
current
dietary
risk
estimates.
Final
tolerances
are
being
proposed
as
part
of
this
Tolerance
Reassessment
Decision
(TRED).
Some
revisions
to
these
tolerance
values
may
be
needed
once
the
field
trial
data
and
rotational
crop
studies
have
been
submitted
to
and
reviewed
by
the
Agency.

Tolerance
Reassessment
Summary
for
Hexazinone.

Commodity
Current
Tolerance
(ppm)
a
Tolerance
Reassessment
(ppm)
Comment/
Correct
Commodity
Definition
Tolerances
presently
listed
under
40
CFR
§180.396(
a):

Alfalfa
green
forage
2.0
2.0
Alfalfa,
forage
Alfalfa
hay
8.0
4.0
Tolerance
should
be
reduced
based
on
re­
calculation
of
expected
residues.
Alfalfa,
hay
Blueberries
0.2
0.6
Tolerance
should
be
increased
based
on
the
combined
LOQ
(0.55
ppm)
of
the
enforcement
method.
Blueberry
Commodity
Current
Tolerance
(ppm)
a
Tolerance
Reassessment
(ppm)
Comment/
Correct
Commodity
Definition
3
Cattle,
fat
0.1
Revoke
b
Cattle,
mbyp
0.1
0.1
Cattle,
meat
0.1
0.1
Goat,
fat
0.1
Revoke
b
Goat,
mbyp
0.1
0.1
Goats,
meat
0.1
0.1
Grasses,
pasture
10
TBD
c
Grass,
forage
Grasses,
rangeland
10
TBD
c
Grass,
hay
Hog,
fat
0.1
Revoke
b
Hog,
mbyp
0.1
Revoke
b
Hog,
meat
0.1
Revoke
b
Horses,
fat
0.1
Revoke
b
Horses,
mbyp
0.1
0.1
Horses,
meat
0.1
0.1
Milk
0.5
0.2
Tolerance
should
be
reduced
based
on
re­
calculation
of
expected
residues.

Pineapple
0.5
0.6
Tolerance
should
be
increased
based
on
the
combined
LOQ
(0.55
ppm)
of
the
enforcement
method.

Sheep,
fat
0.1
Revoke
b
Sheep,
mbyp
0.1
0.1
Sheep,
meat
0.1
0.1
Tolerances
needed
under
40
CFR
§180.396(
a):

Alfalfa,
seed
2.0
Tolerances
presently
listed
under
40
CFR
§180.396(
c):

Sugarcane
0.2
0.6
Tolerance
should
be
increased
based
on
the
combined
LOQ
(0.55
ppm)
of
the
enforcement
method.

Sugarcane
molasses
5.0
4.0
Tolerance
should
be
reduced
based
on
re­
calculation
of
expected
residues.
Commodity
Current
Tolerance
(ppm)
a
Tolerance
Reassessment
(ppm)
Comment/
Correct
Commodity
Definition
4
Sugarcane
molasses
d
5.0
4.0
Tolerance
should
be
reduced
based
on
re­
calculation
of
expected
residues.
a
Expressed
in
terms
of
the
combined
residues
of
hexazinone
and
its
metabolites
(calculated
as
hexazinone).
b
Tolerances
for
fat
are
not
required
(Category
3,
40
CFR
§180.6).
c
TBD:
These
tolerances
require
additional
field
trial
data
and
may
be
revised
once
the
data
have
been
submitted
to
and
reviewed
by
the
Agency.
d
For
reassessment
counting
purposes,
the
Agency
will
count
the
sugarcane
molasses
tolerances
as
two
reassessments
to
reflect
the
tolerances
which
existed
both
in
40
CFR
Part
185
(185.3575)
and
Part
186
(186.3575)
at
the
start
of
FQPA.

No
maximum
residue
limits
(MRLs)
for
hexazinone
and
its
metabolites
have
been
established
or
proposed
by
Codex
for
any
agricultural
commodity.
Therefore,
no
compatibility
questions
exist
with
respect
to
U.
S.
tolerances.

Note
that
you
will
be
sent
a
Section
3(
c)(
2)(
B)
Data­
Call­
In
(DCI)
letter
under
the
Federal
Insecticide,
Fungicide,
Rodenticide
Act
(FIFRA)
in
a
separate
mailing.
If
you
have
questions
on
this
or
any
of
the
attached
documents,
please
contact
the
Chemical
Review
Manager,
Dirk
V.
Helder,
at
(703)
305­
4610.

Sincerely,

Lois
A.
Rossi,
Director
Special
Review
and
Reregistration
Division
Enclosures:
"Hexazinone
Overview"
and
"Hexazinone
Summary"
