UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
PC
Codes:
029801,
029802,
029806,
128931,
128944,
129043
DP
Barcode:
317694
November
15,
2005
MEMORANDUM
Subject:
Revised
EFED
RED
Chapter
For
Dicamba/
Dicamba
Salts
and
Response
to
BASF's
"
Error
Only"
Comments
of
October
27,
2005
To:
Susan
Lewis,
Branch
Chief
Kendra
Tyler,
RM
Reviewer
Reregistration
Branch
1
Special
Review
and
Reregistration
Division
From:
William
Erickson,
Biologist
Ibrahim
Abdel­
Saheb,
Environmental
Scientist
Shannon
Borges,
Biologist
Environmental
Risk
Branch
2,
Environmental
Fate
and
Effects
Division
Through:
Thomas
Bailey,
Branch
Chief,
Environmental
Risk
Branch
2,
Environmental
Fate
and
Effects
Division
EFED
has
completed
a
revision
of
the
RED
chapter
for
dicamba
and
its
salts
in
response
to
BASF's
errors
comments
submitted
on
October
27,
2005.
The
revised
chapter
is
attached.
Below
is
EFED's
response
to
BASF.

BASF
Comment:
BASF
states
that
a
lay
person
reading
the
chapter
could
erroneously
conclude
that
dicamba
has
an
incomplete
data
base.

EFED
Response:
The
data
base
is
incomplete.
In
EFED's
August
31,
2005
risk
assessment,
both
the
cover
letter
and
Appendix
E
identify
the
following
data
gaps:

°
seedling
emergence
and
vegetative
vigor
studies
(
123­
1a,
b);
dicamba
acid,
TEP
°
seedling
emergence
and
vegetative
vigor
studies
(
123­
1a,
b);
dimethylamine
salt,
TEP
°
seedling
emergence
and
vegetative
vigor
studies
(
123­
1a,
b);
diglycoamine
salt,
TEP
°
seedling
emergence
and
vegetative
vigor
studies
(
123­
1a,
b);
isopropylamine
salt,
TEP
°
seedling
emergence
and
vegetative
vigor
studies
(
123­
1a,
b);
sodium
salt,
TEP
°
seedling
emergence
and
vegetative
vigor
studies
(
123­
1a,
b);
potassium
salt,
TEP"

A
DCI
was
issued
in
1992
but
EFED
has
not
received
any
of
the
plant
studies
cited
above.

BASF
Comment:
BASF
notes
that
the
mammalian
NOAEC
reported
as
mg
ai/
kg
diet
should
be
mg
ai/
kg
bw/
day
and
that
mistake
has
lead
to
computational
errors
in
the
risk
quotients
for
chronic
risk
to
mammals.

EFED
Response:
EFED
agrees
that
this
error
occurred.
The
change
in
units
has
been
made
in
the
revised
assessment,
and
the
chronic
mammalian
RQs
have
been
recomputed.
EFED
notes
the
RQs
change
only
slightly,
and
the
risk
conclusions
do
not
change.
Because
an
updated
version
of
T­
REX
(
version
1.2.3,
August
2005)
is
now
available,
EFED
has
used
that
version
to
recalculate
the
RQs.
Because
the
acute
avian
RQs
also
change
slightly,
the
tables
of
acute
avian
RQs
also
are
updated
in
the
revised
assessment,
as
well
the
T­
REX
results
presented
in
Appendix
C
for
sugarcane.

BASF
Comment:
BASF
states
that
they
are
unaware
that
EPA
has
specific
data
requirements
for
riparian
habitats.

EFED
Response:
EFED
has
no
specific
data
requirements
for
riparian
habitats.
EFED
uses
the
terrestrial
plant
phytotoxicity
data
(
guideline
studies
123­
1a,
b)
for
risk
assessments
to
both
upland
and
lowland
plants.
The
difference
is
in
the
exposure
scenarios
(
sheet
runoff
onto
upland
habitats
versus
channelized
runoff
onto
lowland
(
i.
e.,
semi­
aquatic)
habitats).
