UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.,
20460
ENVIRONMENTAL
FATE
AND
EFFECTS
DIVISION
OFFICE
OF
PESTICIDE
PROGRAMS
March
18,
2003
SUBJECT:
Response
to
BASF's
comments
on
the
RED
fo
sodium
acifluorfen
(
PC
Code
114402
/
Company:
007969
BASF
Corporation)
for
uses
on
soybeans,
peanuts
and
rice.

FROM:
James
J.
Goodyear,
Ph.
D.
Biologist
(
7507C)
Kevin
Costello,
Geologist
Environmental
Risk
Branch
3,
EFED
THRU:
Ben
Smith,
Branch
Chief
(
7507C)
Environmental
Risk
Branch
3,
EFED
TO:
Betty
Shackleford,
Branch
Chief
(
7508C)
Christina
Scheltema,
Chemical
Review
Manager
Reregistration
Branch
3,
SRRD
EFED
has
review
BASF's
second
set
of
comments
on
EFED's
portion
of
the
RED
for
acifluorfen.
Our
responses
are
below.

BASF
Comments.

"
1.
Comment
no.
1
Evaluation
of
chronic
risk
to
birds."
"
BASF
respectfully
requests
that
EFED
further
refine
the
assessment
to
consider
the
effects
of
three
other
conservative
factors."

The
assumption
that
a
breeding
bird
will
take
100%
of
its
diet
exclusively
from
a
treated
field.

EFED
Response:

As
EFED
has
stated
previously
that
the
current
risk
assessment
method
for
terrestrial
organisms
was
designed
to
account
for
uncertainties.
Because
of
the
uncertainty,
the
method
includes
some
conservative
assumptions.
In
some
aspects,
conservative
assumptions
are
made
that
will
tend
to
over­
estimate
exposure.
2
However,
in
many
other
aspects,
assumptions
are
made
and
factors
are
overlooked
that
may
cause
the
risk
to
be
underestimated.
For
example,
all
routes
of
exposure
other
than
ingestion
of
contaminated
food
are
ignored,
and
animals
in
the
wild
are
assumed
to
consume
food
at
a
rate
no
greater
than
those
kept
in
captivity.
Overall,
EFED
does
not
believe
that
the
risk
assessment
is
inappropriately
conservative.
EFED
is
working
on
developing
risk
assessment
methods
that
will
address
some
of
these
factors.
EFED
is
open
to
receiving
data
from
BASF
that
further
explore
consumption
patterns
of
terrestrial
organisms
in
the
wild.
Until
these
studies
are
submitted
and
approved,
EFED
must
analyze
the
study
reports
based
upon
the
models
that
it
has
on
hand.

The
use
of
the
maximum
residue
values
of
240
ppm
per
lb
a.
i./
A
for
short
grass
and
58
ppm
lb
a.
i./
A
for
broadleaves
and
insects
instead
of
BASF's
calculated
value
of
125
ppm
for
short
grass
and
33
ppm
for
broadleaf
plants
and
insects
over
the
entire
assessment.

EFED
Response:

The
above
answer
applies
to
this
comment
as
well.
In
addition,
EFED
did
not
use
240/
58
ppm
a.
i./
A
for
calculating
risk.
That
value
is
calculated
from
(
as
BASF
states)
the
application
of
1
lb.
a.
i./
A.
EFED
used
the
label
rates
(
e.
g.,
0.25
lb
a.
i./
A)
to
calculate
the
EECs.
On
page
35
[
the
page
numbers
are
from
the
document
that
EFED
sent
to
SRRD;
SRRD
should
change
the
numbers
to
the
ones
for
the
document
that
they
sent
to
the
registrant,
JG],
in
Chapter
7
under
EXPOSURE
the
table
Estimated
Environmental
Concentrations
is:

Estimated
Environmental
Concentrations
(
EECs)
on
avian
and
mammalian
food
items
(
ppm)
immediately
following
the
second
of
two
applications
of
0.25
lb
ai/
A.

Food
Items
EEC
(
ppm)
Predicted
Maximum
Residue
EEC
(
ppm)
Predicted
Mean
Residue
Short
grass
120
43
Tall
grass
55
18
Broadleaf
plants
/
Insects1
68
23
Seeds
8
4
Page
36
(
3rd
paragraph)
states,
"
The
duration
of
the
chronic
risk
will
be
for
three
days
after
the
first
application
and
more
than
15
days
after
the
second
application."
3
The
nature
of
the
effect
observed
in
the
Northern
bobwhite
reproduction
study
and
the
use
of
20
ppm
as
the
NOEAC.

EFED
Response:

In
performing
avian
chronic
toxicity
studies,
the
Agency
encourages
registrants
to
perform
studies
at
numerous
levels
in
order
to
better
refine
their
estimates
of
LOAECs
and
NOAECs,
but
does
not
typically
consider
studies
based
on
less
than
five
treatment
levels.
In
this
case,
BASF
only
provided
information
on
two
levels.
Rather
than
requiring
new
studies,
the
Agency
agreed
to
consider
the
information
in
its
risk
assessment
process.
Unfortunately,
by
selecting
such
an
approach,
BASF
has
limited
the
Agency's
ability
to
draw
conclusions
about
intermediary
doses.
There
is
no
basis
for
imputing
an
effect
at
intermediate
doses
of
acifluorfen,
as
it
cannot
even
be
established
that
the
effect
would
be
linear
in
this
range.
Furthermore,
having
incomplete
information,
it
would
inappropriate
for
the
Agency
to
pick
the
least
conservative
conclusion
based
on
a
LOAEC.
Should
BASF
desire
consideration
of
intermediate
points
for
the
NOAEC,
they
have
the
option
to
perform
studies
at
those
levels
to
demonstrate
its
accuracy.
Lacking
such
information,
the
Agency
must
continue
to
use
20
ppm
as
the
NOAEC.

BASF
Comments:
"
2.
Comment
no.
2.
Discussion
of
uncertainty
of
chronic
risk
to
freshwater
and
estuarine
animals."
"
BASF
argues
that
the
preponderance
of
the
evidence
leads
to
the
conclusion
that
acifluorfen
does
not
pose
a
chronic
risk
to
aquatic
organisms.
Acifluorfen
has
a
fairly
short
photolytic
half­
life
in
water
(
3.8
days),
is
not
acutely
toxic,
and,
even
with
a
theoretical
20­
fold
increase
in
toxicity,
the
chronic
RQs
for
all
crops
are
well
below
LOCs.
BASF
does
not
believe
an
additional
study
(
aquatic
phototoxicity)
is
necessary
to
address
aquatic
chronic
toxicity."

"
BASF
argues
that
the
preponderance
of
the
evidence
leads
to
the
conclusion
that
acifluorfen
does
not
pose
a
chronic
risk
to
aquatic
organisms.
Acifluorfen
has
a
fairly
short
photolytic
half­
life
in
water,
is
not
acutely
toxic,
and,
even
with
a
theoretical
20­
fold
increase
in
toxicity,
the
chronic
RQs
for
all
crops
are
well
below
LOCs.
BASF
does
not
believe
an
additional
study
(
aquatic
phototoxicity)
is
necessary
to
address
aquatic
chronic
toxicity."
The
Agency
disagrees
with
BASF
on
both
of
its
conclusions.
Clearly
establishing
that
there
is
no
chronic
effect
requires
an
evaluation
that
includes
studies
at
proper
conditions
and
demonstration
of
a
NOAEC.
BASF
has
provided
neither.
They
acknowledge
they
have
not
provided
data
at
a
clear
NOAEC.
The
sole
effect
observed
at
1.5
mg/
L
was
on
weight.
BASF
did
not
provide
additional
information
on
behavior
or
blood
chemistry
that
would
have
enabled
the
Agency
further
to
refine
its
evaluation
of
the
importance
of
this
effect.
Consequently,
we
are
left
with
the
presumption
that
the
NOAEC
is
some
level
less
than
1.5
mg/
L.
4
As
stated
in
the
draft
RED,
the
Agency
has
good
reason
to
expect
an
increase
in
toxicity
similar
to
that
observed
in
the
study
of
carfentrazone­
ethyl
(
20­
fold).
Taken
together,
these
points
suggest
a
chronic
level
of
concern
considerably
below
75
g/
L.
How
far
below
75
g/
L
the
level
of
concern
is
can
only
be
addressed
by
a
properly
conducted
study
of
phototoxicity.
BASF
also
asserts
that
acifluorfen's
short
half­
life
in
water
makes
it
unlikely
that
it
would
persist
in
shallow,
clear
bodies
of
water
where
photolytic
activity
could
generate
increased
phototoxicity.
Consequently,
BASF
believes
it
is
unlikely
that
a
60­
day
EEC
of
20
g/
L
associated
with
soybeans
would
be
likely
to
occur.
The
Agency
disagrees,
as
normal
water
body
mixing
should
be
more
than
adequate
to
maintain
long
term
concentrations
estimated
by
PRZM/
EXAMS.
Counterbalancing
BSAF's
concern
is
the
inherent
inability
of
chronic
toxicity
studies
to
account
for
the
impact
of
higher
initial
concentration
"
shock"
levels
on
organisms
that
can
amplify
chronic
effects
in
the
natural
environment.
While
the
Agency
acknowledges
that,
without
phototoxicity,
a
14­
fold
safety
factor
of
safety
would
not
pose
a
chronic
concern
for
aquatic
life.
This
statement
is
consistent
with
the
fact
that
one
must
consider
phototoxicity
as
a
possible
mechanism
of
concern
for
acifluorfen.
When
such
phototoxicity
is
considered,
the
quotient
is
not
fourteen,
but
approximately
three.
This
narrow
margin,
coupled
with
the
shortcomings
of
the
provided
study
(
which
failed
to
establish
an
NOAEC),
leads
the
Agency
to
conclude
the
requested
study
is
still
necessary.

BASF
Comments:

"
3.
Comment
no.
3.
Nontarget
terrestrial
plant
testing.
BASF
is
willing
to
work
with
the
Agency
to
further
define
the
risk."

EFED
Response:
The
registrant
acknowledges
that
additional
studies
are
needed.
EFED
looks
forward
to
seeing
BASF's
new
studies
or
to
discussing
their
new
protocol.
