UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON
D.
C.,
20460
OFFICE
OF
PREVENTION,
PESTICID
ES
AND
TOXIC
SUBSTANCES
MEMORANDUM
PC
Code:
121001
DP
Barcode:
318160,
318162
DATE:
June
22,
2005
SUBJECT:
Environmental
Fate
and
Effects
Division
Error
only
corrections
on
the
Sethoxydim
RED
TO:
James
Parker,
Chemical
Review
Manager
Reregistration
Branch
I
Special
Review
and
Reregistration
Division
(
7508W)

FROM:
Michael
Davy,
Agronomist
William
Eckel,
Ph.
D.,
Agronomist
Environmental
Fate
and
Ecological
Effects
Division
(
7507C)

THROUGH:
Tom
Bailey,
Ph.
D.,
Branch
Chief
Environmental
Review
Branch
II
The
EFED
responses
to
the
error­
only
comments
from
BASF
on
the
sethoxydim
RED
are
attached
in
tabular
format.
All
comments
listed
as
"
corrected"
have
been
changed
in
the
original
document.
Environmental
Fate
and
Ecological
Risk
Assessment
of
Endothall
No.
Location
Comment
EFED
Response
1
General
with
first
occurrence
on
page
2
EPA
has
recalculated
the
reported
endpoint
from
the
mallard
reproduction
study,
resulting
in
a
NOAEL
of
<
100
mg/
kg
rather
than
the
reported
1000
mg/
kg..
BASF
supports
the
original
study
endpoint
of
NOAEL
=
1000
mg/
kg.
We
are
currently
working
with
the
laboratory
that
conducted
the
study
to
provide
additional
supporting
information.
EFED
will
evaluate
any
additional
data
from
registrant
concerning
the
establishment
of
a
NOAEL
for
the
mallard.

2
Page
3
The
EPA­
approved
Poast
®
and
Poast
Plus
®
Herbicide
labels
(
EPA
Registration
No.'
s
7969­
58
and
7969­
88,
respectively),
pages
4
and
5,
restrict
the
use
of
nozzles
to
the
medium
or
course
category
as
defined
by
ASAE
572
diameter
definition.
The
labels
also
restrict
aerial
applications
to
wind
conditions
of
10
MPH
or
less,
and
the
release
height
to
10
ft.
Copies
of
the
most
recent
EPAapproved
labels
are
included
in
Appendix
2,
for
reference.
The
label
restriction
invalidates
both
the
ground
and
aerial
calculations
performed
by
EPA
since
these
restrictions
were
not
followed.
Since
EPA
did
not
follow
the
label
while
estimations
of
spray
drift
were
made,
buffer
calculations
made
to
protect
threatened
and
endangered
species
are
not
correct.
BASF
has
recalculated
the
suggested
buffer
distances
required
to
protect
threatened
and
endangered
species
and
are
part
of
this
response
(
see
#
9
below).
Please
note
that
BASF
has
also
submitted
label
amendments
to
EPA
for
Poast
®
and
Poast
Plus
®
Herbicides
(
copy
of
cover
letters
attached
in
Appendix
3),
prohibiting
aerial
application
to
all
registered
tree
crops
and
grapes
so
that
the
10­
foot
release
height
can
be
achieved.
EFED
cannot
calculate
proper
spray
drift
buffers
for
terrestrial
plants
until
the
registrant
submits
vegetative
vigor
plant
toxicity
data
(
guideline
123­
1)
using
a
Typical
End
Product
(
TEP)
formulation.
The
submitted
data
using
Technical
Grade
Active
Ingredient
(
TGAI)
lacks
the
"
adjuvant
systems
...
critical
for
penetration
of
the
chemical
by
the
leaf
surface"
(
registrant's
comment
#
4).
Use
of
TGAI
plant
toxicity
data
underestimates
the
toxicity,
so
even
a
refined
exposure
estimate
will
underestimate
the
risk
and
the
required
buffer
zone.
EFED
will
delete
the
calculated
buffer
zones
in
the
chapter.

3
Page
4
EPA
concludes
"
environmental
fate
and
modeling
estimates
indicate
that
Sethoxydim
residues
will
leach
into
ground
water
in
highly
vulnerable
areas.
The
Agency
is
also
recommending
that
the
label
be
modified
so
that
the
use
of
Sethoxydim
is
restricted
in
sandy
soils
(>
90%
sand
and
<
1%
organic
matter)
and
in
areas
of
shallow
ground
water
(<
25
feet)."
BASF
proposes
to
place
the
following
statement
on
product
labeling:
"
Environmental
fate
data
and
modeling
estimates
indicate
that
sethoxydim
residues
could
be
found
in
ground
water
in
highly
vulnerable
areas.
Avoid
applying
Poast
®
(
Poast
Plus
®
)
in
sandy
soils
(>
90%
sand
and
<
1%
organic
matter)
and
in
areas
of
shallow
ground
(<
25
feet).
We
agree
with
this
comment,
and
the
suggested
label
language.

4
Page
15
The
third
paragraph
states
"
because
the
re­
application
interval
is
14
days,
and
the
degradates
are
more
persistent,
it
is
reasonable
to
conclude
that
M­
SO
and
M­
SO2
are
the
forms
that
have
biological
activity."
The
conclusion
that
the
sulfoxide
and
sulfone
degradates
must
be
herbicidally
active
compounds
is
not
correct.
Sethoxydim
is
a
foliarly
active
herbicide
and
there
is
no
evidence
of
herbicidal
activity
in
the
soil.
Since
sethoxydim
is
foliarly
active,
its
half­
life
in
the
environment
needs
only
be
long
enough
for
penetration
into
the
leaf.
Further,
as
with
other
compounds
in
this
class
of
chemistry,
adjuvant
systems
are
critical
for
penetration
of
the
chemical
by
the
leaf
surface.
In
a
paper
by
Ishikawa,
H.,
I.
Iwataki,
and
M.
Sawaki.
1985,
The
We
will
review
this
issue
(
soil
activity)
when
the
translated
paper
is
provided.
This
issue
is
not
important
for
spray
drift
exposure.
Environmental
Fate
and
Ecological
Risk
Assessment
of
Endothall
No.
Location
Comment
EFED
Response
Development
of
Two
Herbicides,
Alloxydim­
sodium
and
Sethoxydim,
published
in
the
Journal
of
Pesticide
Science
10(
2),
pg
301­
313
(
see
Appendix
4
for
a
copy
of
this
article),
the
foliar
activity
of
sethoxydim,
sethoxydim
sulfoxide,
and
sethoxydim
sulfone
were
compared
for
selectivity
on
Avena
sative
and
Digitara
adscendens.
Based
on
results
in
this
paper,
sethoxydim
(
parent)
was
clearly
the
most
active
molecule.
The
Agency's
comments
regarding
behavior
of
sethoxydim
and
it
degradates
in
soil
are
only
mechanistically
correct
(
i.
e.­
sethoxydim
does
degrade
to
a
sulfone
and
sulfoxide
degradate),
and
comments
with
regard
to
soil
activity
are
not
relevant.
In
summary,
the
compound
is
only
active
as
a
foliar
herbicide.
(
In
paragraph
four
on
the
same
page,
the
reference
to
an
unacceptable
study
to
support
the
position
seems
inappropriate.)
5
Page
17
The
empirical
formula
needs
to
be
corrected
as
follows:
C17
H29
O3
NS.
In
addition,
according
to
EPA
records,
the
CAS
number
is
74051­
80­
2.
Please
see
a
copy
of
the
reference
printed
from
the
EPA
database
in
Appendix
5.
We
agree
with
these
comments,
and
the
errors
will
be
corrected.

6
Page
43
In
order
to
generate
EEC
values
for
ecotox
assessment
of
total
residues,
EPA
used
GENEEC2.
BASF
was
able
to
replicate
the
results
from
GENEEC2
based
on
input
from
Table
8,
page
43.
However,
the
Agency
referenced
the
citrus
use
pattern
to
obtain
maximum
estimated
residues
in
water,
and
contradicted
the
label
(
Poast
and
Poast
Plus
Herbicides,
EPA
Reg.
No.'
s
7969­
58
and
7969­
88,
respectively)
in
two
significant
ways:
1)
the
GENEEC2
calculations
are
based
on
aerial
application,
but
the
label
prohibits
this
method
of
application
for
citrus;
2)
medium
or
coarser
spray
nozzles
must
be
used
based
on
the
ASAE
572
definition
when
aerial
(
or
ground)
applications
are
made.
The
Agency
used
fine
to
medium
nozzles
for
its
exposure
assessment.
BASF
recalculated
the
EEC
values
for
the
citrus
use
pattern,
since
it
allows
the
greatest
amount
of
active
ingredient
to
be
applied.
Both
the
California
and
Florida
scenarios
were
run.
Results
from
these
calculations
can
be
found
in
the
table
below:
(
see
Footnote
1)
This
comment
is
moot,
since
EFED
has
already
determined
that
the
risk
to
aquatic
organisms
is
below
the
level
of
concern
(
from
sethoxydim
itself)
using
very
conservative
exposure.
However,
fate
data
on
the
petroleum
solvent
containing
naphthalene
would
help
us
to
better
understand
exposure
by
run­
off.
This
issue
may
be
revisited
if
the
aquatic
grass
toxicity
data
show
a
risk
above
the
level
of
concern
with
the
current
exposure
estimate.

7
Page
44
As
in
#
3
above,
the
POAST
®
and
Poast
Plus
®
product
labels
(
pages
4­
5)
restrict
the
use
of
nozzles
to
the
medium
or
course
category
as
defined
by
ASAE
572
diameter
definition.
The
labels
also
restrict
aerial
applications
to
wind
conditions
of
10
MPH
or
less,
and
the
release
height
to
10
ft.
The
label
restriction
invalidates
both
the
ground
and
aerial
calculations
performed
by
EPA
since
these
restrictions
were
not
followed.
Therefore,
BASF
has
redone
the
EPA
calculations
following
the
restrictions
on
the
label.
For
ground
applied
material,
medium
or
coarser
spray
nozzles
must
be
used
based
on
the
label
(
ASAE
572
definition).
For
aerial
applied
material,
the
label
limits
applications
in
wind
to
a
maximum
of
10
mph.
The
label
also
restricts
release
height
to
10
feet.
The
10
mph
and
10
foot
release
height
were
used
in
our
assessment.
The
BASF
recalculated
EEC
values
using
AgDrift
are
presented
in
the
table
below.
(
See
Footnote
2)
This
comment
is
also
moot,
since
the
risks
(
from
sethoxydim
itself)
from
spray
drift
to
the
pond
have
already
been
determined
to
be
below
level
of
concern
for
fish
and
invertebrates
using
very
conservative
exposure.
This
issue
may
be
revisited
if
the
aquatic
grass
toxicity
data
show
a
risk
above
the
level
of
concern
with
the
current
exposure
estimate
Environmental
Fate
and
Ecological
Risk
Assessment
of
Endothall
No.
Location
Comment
EFED
Response
8
Page
57
and
with
occurrence
there
after
It
is
unclear
from
the
data
currently
available
to
EPA
if
the
formulation
used
in
the
chronic
aquatic
studies
with
the
mysid
shrimp
and
sheepshead
minnow
contained
petroleum
solvent
(
and
consequently
Naphthalene).
The
formulation
utilized,
POAST
3.5
EC
(
Registration
number
7679­
129),
does
contain
naphthalene
via
the
petroleum
solvent
known
as
Aromatic
150.
Based
on
the
confidential
statement
of
formula,
POAST
3.5
EC
contains
a
total
of
50%
Aromatic
150
petroleum
solvent
(
contained
in
the
manufacturing
use
product
and
also
added
as
a
separate
component).
Aromatic
150
petroleum
solvent
is
comprised
of
a
mixture
of
organic
compounds,
8.6%
of
which
is
Naphthalene.
Information
on
the
formulation
for
chronic
mysid
shrimp
and
chronic
estuarine
fish
studies
will
be
corrected
in
the
chapter.

9
Page
60
and
any
other
occurrence
For
ground­
applied
material,
medium
or
coarser
spray
nozzles
must
be
used
based
on
the
label
(
ASAE
572
definition).
The
Agency
used
fine
to
medium
nozzles
for
its
exposure
assessment.
For
aerial
applied
material,
the
label
limits
applications
in
wind
to
a
maximum
of
10
mph.
The
Poast
®
and
Poast
Plus
®
labels
also
restrict
release
height
to
10
feet.
The
label
restriction
invalidates
both
the
ground
and
aerial
calculations
performed
by
EPA
since
these
restrictions
were
not
followed.
Therefore,
BASF
has
redone
the
EPA
calculations
following
the
restrictions
on
the
label.
The
10
mph
and
10
foot
release
height
were
used
in
our
assessment.
In
order
to
determine
the
buffers
required
to
protect
terrestrial
plants,
the
Agency
selected
the
NOEC
of
0.025
lb
ai/
acre
(
based
on
ryegrass).
Recalculation
of
spray
drift
buffer
zones
is
not
possible
(
for
plants)
until
TEP
toxicity
data
are
submitted
(
see
response
to
comment
#
2).
EFED
has
removed
all
buffer
zone
calculations
from
the
chapter.
For
animals,
the
comment
is
moot,
since
the
risk
is
calculated
with
the
Hoerger­
Kenaga
nomogram,
not
spray
drift
exposures.

10
Page
12
and
any
other
occurrence
It
appears
that
the
reviewer
inadvertently
missed
Tier
II
seedling
emergence
data
that
BASF
had
previously
submitted,
re:
MRID
43614603.
This
report
includes
Tier
II
seedling
germination
(
no
longer
required)
and
seedling
emergence
data
on
three
monocot
species
and
should
be
useful
in
the
evaluation
of
the
compound.
BASF
requests
that
the
data
from
the
Tier
II
seedling
emergence
study
be
considered
in
the
final
risk
assessment.
The
study
submitted
(
MRID
43614603)
has
3
grass
species
tested
­
corn,
oat,
and
ryegrass.
This
study
used
the
aromatic150
with
sethoxydim.
The
testing
agent
would
be
considered
as
the
TEP.
EFED
reviewed
the
study
and
recalculated
the
ryegrass
seedling
emergence
EC25
using
a
continuous
endpoint
statistical
program
(
nuthatch).
The
results
are
attached.
The
results
will
be
incorporated
into
the
risk
assessment.
11
page
83
The
review
states
that
the
study
does
not
satisfy
the
data
requirement
at
this
time
since
the
floodwater
was
not
completely
characterized.
However,
BASF
would
like
to
note
that
characterization
of
the
water
is
not
relevant
since,
according
to
guideline
requirements,
the
water
utilized
was
HPLC
grade
deionized
water.
Characterization
of
deionized
water
is
not
necessary
(
please
see
page
64
of
the
study
report,
showing
the
reference
to
HPLC
grade
water,
Burdick
and
Jackson,
Lot
no.
AT027)
Subdivision
N
states
that
the
water
used
in
aerobic
aquatic
metabolism
studies
should
be
collected
near
an
intended
use
site
(
that
is,
it
should
be
a
natural
water).
Since
HPLC
grade
deionized
water
does
not
fit
this
description,
the
study
cannot
be
fully
acceptable.

12
page
138
The
first
sentence
states
"
There
are
no
chronic
data
for
fish.
A
freshwater
fish
early
life­
stage
test
is
required
if
the
following
criteria
(
40
CFR
Part
158)
have
been
met: "
Please
note
that
the
report
previously
submitted
by
BASF,
entitled
"
Sethoxydim:
An
Early
Life­
Stage
Toxicity
Test
with
the
Sheepshead
Minnow
(
Cyprinodon
variegatus),"
fills
this
data
requirement
for
estuarine
and
marine
organisms
(
re:
MRID
43614601).
This
sentence
is
in
error.
Correction
will
be
made.
Environmental
Fate
and
Ecological
Risk
Assessment
of
Endothall
No.
Location
Comment
EFED
Response
13
page
139
The
first
sentence
states
"
There
are
no
chronic
data
for
estuarine
invertebrates.
Aquatic
invertebrate
life
cycle
test
is
required
if
the
following
criteria
(
40
CFR
Part
158)
have
been
met: "
Please
note
that
the
report
previously
submitted
by
BASF,
entitled
"
Chronic
Toxicity
of
Sethoxydim
to
the
Mysid,
Mysidopsis
bahia,"
fills
this
data
requirement
for
estuarine
invertebrates
(
re:
MRID
43614602).
This
sentence
is
in
error.
Correction
will
be
made.

Footnote
1
­
Summary
of
compound
input
information
Crop
App.
Rate
(
lb
ai
/
ac)
App.
No.
App.
Interval
Wet
In
Incorp.
Depth
PHI
CAM
Reference
Citrus
0.47a
4
14
n
n/
a
n/
a
1
Poast
®
Label
Application
dates
5/
1,
5/
14,
5/
28,
and
6/
11
Summary
of
PRZM/
EXAMS
calculations
assessing
runoff
and
drift
Scenario
Acute
4
Day
21
Day
60
Day
90
Day
Annual
Method
­­­­­­­­­­­­­­­­­­­­­­­­­­
ug/
L­­­­­­­­­­­­­­­­­­­­­­­

CA
­
Citrus
0.829
0.804
0.711
0.608
0.525
0.197
g
FL
­
Citrus
16.7
16.1
13.8
1.1
8.58
2.79
g
g
­
ground
applied
Footnote
2
­

Revised
BASF
Calculations
Application
Method
EEC
in
Standard
Pond
(
ug/
L)

Ground
0.4
Aerial
3.6
