E
­
1
APPENDIX
E.
Ecological
Effects
Data
Studies
are
with
imazapyr
acid,
unless
otherwise
noted
71­
1
Avian
Acute
Oral
Bobwhite
Quail.
MRID
00131633
(
Acceptable).
In
a
14­
day
oral
gavage
study,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
bobwhite
quail
with
an
LD
50
of
>
2,150
mg
ae/
kg.
The
study
is
scientifically
sound
and
follows
the
guideline
protocols.

Mallard
Duck.
MRID
00131634
(
Acceptable).
In
a
14­
day
oral
gavage
study,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
mallard
ducks
with
an
LD
50
of
>
2,150
mg
ae/
kg.
The
study
is
scientifically
sound
and
follows
the
guideline
protocols.

71­
2
Avian
Subacute
Dietary
Imazapyr
acid
Bobwhite
Quail.
MRID
00131635
(
Acceptable).
In
an
8­
day
dietary
study,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
upland
game
birds
(
bobwhite
quail)
with
an
LC
50
>
5000
ppm.
The
study
is
scientifically
sound
and
generally
followed
guideline
protocols;
however,
there
was
some
unexplainable
low
weight
gains
and
mortality
at
the
625
ppm
test
concentration.

Mallard.
MRID
00131636
(
Acceptable).
In
an
8­
day
dietary
study,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
mallard
ducklings
with
an
LC
50
>
5000
ppm..
The
study
is
scientifically
sound
and
generally
followed
guideline
protocols.

Imazapyr
isopropylamine
salt
Bobwhite
Quail.
MRID
00147115
(
Acceptable).
In
an
8­
day
dietary
study,
the
isopropylamine
salt
of
imazapyr
was
determined
to
be
practically
non­
toxic
to
upland
game
birds
(
bobwhite
quail)
with
an
LC
50
>
5000
ppm.
The
study
is
scientifically
sound
and
generally
followed
guideline
protocols.
This
study
was
conducted
with
the
formulated
product
to
ensure
that
isopropylamine
did
not
affect
the
toxicity
of
the
active
ingredient.

71­
4
Avian
Reproduction
Bobwhite
Quail.
MRID
45119714a
(
Acceptable).
In
a
one­
generation
reproductive
toxicity
study,
imazapyr
acid
produced
no
evidence
of
treatment­
related
adverse
effects
on
adult
or
reproductive
parameters
with
an
NOAEC
of
1670
ppm.
The
study
is
scientifically
sound
and
generally
followed
guideline
protocols.

Mallard.
MRID
45119714b
(
Invalid).
In
a
one­
generation
reproductive
toxicity
study,
imazapyr
acid
resulted
in
a
significant
reduction
in
the
ratio
of
viable
embryos/
eggs
at
the
1,670
ppm
E
­
2
treatment
level.
However,
the
study
was
determined
to
be
invalid
due
to
bacterial
contamination
and
high
embryonic
mortality
in
the
controls.
EFED
recommended
that
another
study
be
conducted
to
determine
the
reproductive
toxicity
of
imazapyr
to
waterfowl.

Bobwhite
Quail.
MRID
43831401
(
Originally
Supplemental;
Reclassified
Core).
In
a
onegeneration
reproductive
toxicity
study,
imazapyr
acid
resulted
in
reduced
hatchlings/
live
embryo
at
2000
ppm
(
LOEC;
NOEC
=
1000
ppm);
however,
the
study
was
originally
determined
to
be
supplemental
due
to
guideline
deficiencies
(
primarily,
EECs
would
be
higher
than
highest
dose
tested
and
control
egg
shell
cracking
was
13%).
EFED
reevaluated
the
studies
and
determined
that
the
dosing
did
reflect
the
maximum
EEC
and
that
the
handling
and
measurement
deficiencies
did
not
reflect
a
dose­
response
relationship;
consequently,
the
study
was
reclassified
as
core
and
the
NOEC
was
changed
to
2000
ppm.

Mallard.
MRID
43831402
(
Originally
Supplemental;
Reclassified
Core).
In
a
one­
generation
reproductive
toxicity
study,
imazapyr
acid
produced
no
evidence
of
treatment­
related
adverse
effects
on
adult
or
reproductive
parameters
with
an
NOAEC
of
1890
ppm
(
measured
concentration;
2000
ppm
nominal
concentration).
However,
the
study
was
originally
determined
to
be
supplemental
due
to
guideline
deficiencies
(
primarily,
EECs
would
be
higher
than
highest
dose
tested,
inaccurate
measurement
of
egg
shell
thickness,
and
insufficient
pre­
egg
laying
period.
EFED
reevaluated
the
studies
and
determined
that
the
dosing
did
reflect
the
maximum
EEC
and
that
the
measurement
deficiencies
did
not
reflect
a
dose­
response
relationship;
consequently,
the
study
was
reclassified
as
core
and
the
NOAEC
was
established
at
2000
ppm.

72­
1
Freshwater
Fish
Acute
Imazapyr
acid
Rainbow
Trout.
MRID
00131629
(
Acceptable).
In
a
96­
hour
acute
test,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
rainbow
trout
with
an
LC
50
of
>
100
mg/
L.
The
NOEC
was
determined
to
be
100
mg/
L.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Bluegill
Sunfish.
MRID
00131630
(
Acceptable).
In
a
96­
hour
acute
test,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
bluegill
sunfish
with
an
LC
50
of
>
100
mg/
L.
The
NOEC
was
determined
to
be
100
mg/
L.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Channel
Catfish.
MRID
00131631(
Acceptable).
In
a
96­
hour
acute
test,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
channel
catfish
with
an
LC
50
of
>
100
mg/
L.
The
NOEC
was
determined
to
be
100
mg/
L.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Imazapyr
isopropylamine
salt
Rainbow
Trout.
MRID
45119713
(
Acceptable).
In
a
96­
hour
flow­
through
test,
imazapyr
isopropylamine
salt
was
determined
to
be
practically
non­
toxic
to
rainbow
trout
with
an
LC
50
of
>
110
mg
ae/
L
(
mean
measured
concentration;
nominal
concentration
120
mg
ae/
L).
The
NOEC
was
determined
to
be
110
mg
ae/
L.
The
study
is
scientifically
sound
and
meets
guideline
E
­
3
protocols.

Bluegill
Sunfish.
MRID
00147116
(
Acceptable).
In
a
96­
hour
test,
imazapyr
isopropylamine
salt
was
determined
to
be
practically
non­
toxic
to
bluegill
sunfish
with
an
LC
50
of
>
818
mg
ae/
L
(
1000
mg
ai/
L).
The
study
is
scientifically
sound
and
meets
guideline
protocols.

72­
2
Freshwater
Invertebrate
Acute
Imazapyr
acid
Daphnia.
MRID
00131632
(
Core).
In
a
48­
hour
acute
test,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
daphnids
with
an
EC
50
of
>
100
mg/
L.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Imazapyr
isopropylamine
salt
Daphnia.
MRID
00147117
(
Core).
In
a
48­
hour
static
test,
imazapyr
isopropylamine
salt
was
determined
to
be
practically
non­
toxic
to
daphnids
with
an
EC
50
of
614
mg
ae/
L
(
750
mg
ai/
L).
The
study
is
scientifically
sound
and
meets
guideline
protocols.

72­
3a
Estuarine/
Marine
Fish
Acute
Silverside
Minnow.
MRID
41315801(
Acceptable).
In
a
96­
hour
flow­
through
test,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
silverside
minnow
with
an
LC
50
of
>
184
mg
ai/
L
(
mean
measured
concentration;
nominal
concentration
200
mg
ai/
L).
The
NOEC
was
determined
to
be
184
mg
ai/
L.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

72­
3b
Estuarine/
Marine
Invertebrate
Acute
Eastern
Oyster.
MRID
45119710
(
Acceptable).
In
a
96­
hour
flow­
through
test,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
the
eastern
oyster
with
an
EC
50
of
>
132
mg
ai/
L
(
mean
measured
concentration;
nominal
concentration
120
mg
ai/
L).
No
mortalities
were
observed
in
either
the
treated
or
control
groups.
The
control
shell
deposition
during
the
study
was
2.46
mm.
The
NOAEC
was
determined
to
be
132
mg
ai/
L,
the
highest
concentration
tested.
No
significant
adverse
effects
were
observed
on
shell
deposition
for
any
treated
group.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Eastern
Oyster.
MRID
41315802
(
Supplemental).
In
a
96­
hour
flow­
through
test,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
the
eastern
oyster
with
an
EC
50
of
>
173
mg
ai/
L
(
mean
measured
concentration;
nominal
concentration
200
mg
ai/
L;
the
highest
concentration
tested).
No
mortalities
were
observed
in
either
the
treated
or
control
groups.
There
was
a
statistically
significant
decrease
in
mean
shell
deposition
at
173
mg/
L
when
compared
to
the
control
group
(
p
#
0.05).
The
NOAEC
was
determined
to
be
109
mg
ai/
L.
Originally,
this
study
was
classified
as
invalid
because
the
control
oyster
growth
(
1.35
mm
new
shell
deposition)
did
not
meet
the
guideline
requirement
of
2
mm
(
amendment
to
SEP,
dated
9/
1990).
In
addition,
the
E
­
4
flow
rate
of
the
test
solution
was
1.05
L/
oyster/
hour.
The
protocols
recommended
by
the
SEP
(
APHA,
1981
and
EPA,
1976)
state
that
each
oyster
should
receive
a
minimum
of
5
L/
oyster/
hour.
This
study
was
later
upgraded
to
supplemental.
The
memorandum
stated
that
shell
growth
in
the
control
group
may
be
used
as
an
indicator
of
stress
for
the
oysters.
Less
than
2
mm
shell
growth
in
the
control
group
indicates
that
the
oysters
may
be
undergoing
stress.
The
low
flow­
through
rate
with
no
supplemental
food
added
in
this
study
may
have
contributed
to
stress
on
the
oysters.
For
this
study,
it
appears
that
the
seawater
was
trucked
in
from
the
ocean
to
Gainesville,
Florida.
During
such
time,
the
food
organisms
(
such
as
algae)
may
have
been
inhibited
during
the
transport
and
storage.
The
oysters
in
the
study
may
not
have
fed
well
because
of
the
combination
of
the
lower
amount
of
available
food
organisms
in
the
shipped
sea
water,
the
low
flow
rate
and
the
lack
of
supplemental
food
added;
thereby,
contributing
to
inadequate
shell
deposition.
However,
since
there
was
some
dose­
response,
the
study
was
upgraded
to
supplemental.

Pink
Shrimp.
MRID
41315803
(
Acceptable).
In
a
96­
hour
flow­
through
test,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
pink
shrimp
with
an
LC
50
of
>
189
mg
ai/
L
(
mean
measured
concentration;
nominal
concentration
200
mg
ai/
L).
There
was
one
mortality
at
the
second
highest
concentration
level
(
111
mg/
L),
which
does
not
appear
to
be
related
to
treatment.
No
other
signs
of
toxicity
were
observed.
Therefore,
the
NOAEC
was
determined
to
be
189
mg
ai/
L,
the
highest
concentration
tested.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

72­
4a
Freshwater
Fish
Early
Life
Stage
Fathead
Minnow.
MRID
45119711
(
Acceptable).
In
an
early
life­
stage
flow­
through
test,
imazapyr
acid
produced
no
treatment­
related
effects
on
embryonic
survival,
time
to
hatch,
alevin
survival,
terminal
length,
or
wet
and
dry
weight.
The
NOEC
was
determined
to
be
118
mg
ai/
L
(
mean
measured
concentration;
nominal
concentration
120
mg
ai/
L).
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Rainbow
Trout.
MRID
41315804
(
Supplemental).
In
an
early
life­
stage
flow­
through
test,
imazapyr
acid
resulted
in
significantly
reduced
percent
hatch
and
an
observed
reduction
on
survival
at
92.4
mg/
L
(
mean
measured
concentration;
nominal
concentration
100
mg/
L).
No
abnormalities
in
embryonic
or
juvenile
development
were
observed.
The
MATC
was
>
43.1
and
<
92.4
mg/
L;
thus
the
geometric
mean
MATC
was
63.1
mg/
L.
The
study
did
not
meet
all
guideline
requirements
(
feeding
limited
the
growth
of
replicates
with
higher
fish
densities).

72­
4b
Freshwater
Invertebrate
Life
Cycle
Daphnia.
MRID
41315805
(
Acceptable).
In
a
life
cycle
flow­
through
test,
imazapyr
acid
produced
no
treatment­
related
effects
on
survival,
growth
and
reproduction
of
first
generation
daphnids.
No
physical
or
behavioral
abnormalities
were
observed.
The
MATC
and
NOEL
were
determined
to
be
$
97.1
mg/
L.
The
study
is
scientifically
sound
and
meets
guideline
protocols.
E
­
5
72­
5
Freshwater
Fish
Life
Cycle
Fathead
Minnow.
MRID
45119712
(
Supplemental).
In
a
full
life
cycle
flow­
through
test,
imazapyr
acid
produced
no
treatment­
related
effects
on
growth,
embryo
survival,
time
to
hatch,
or
larval
and
juvenile
survival
of
the
F
0
and
F
1
generations.
No
treatment­
related
effects
were
observed
on
percent
spawning
frequency,
mean
number
of
eggs
produced
per
female
or
mean
percent
fertilization
success.
The
NOEC
was
reported
at
the
nominal
concentration
of
120
mg
ai/
L
(
mean
measured
concentration
118
mg
ai/
L).
The
study
is
scientifically
valid
but
did
not
meet
all
guideline
requirements
(
F
1
generation
was
maintained
for
4
weeks
instead
of
8
weeks).

81­
1
Acute
Mammalian
Oral
Imazapyr
acid
Rat.
MRID
132030
(
Acceptable).
In
an
acute
oral
study,
imazapyr
acid
was
determined
to
have
a
low
toxicity
(
Toxicity
Category
III)
to
rats
with
an
LD
50
>
5000
mg/
kg.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Imazapyr
isopropylamine
salt
Rat.
MRID
00147049
(
Acceptable).
In
an
acute
oral
study,
imazapyr
isopropylamine
salt
was
determined
to
exhibit
no
toxicity
(
Toxicity
Category
IV)
to
rats
with
an
LD
50
of
>
5000
mg/
kg
(>
4090
mg
ae/
kg).
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Rat.
MRID
44735301
(
Acceptable).
In
an
acute
oral
study,
imazapyr
isopropylamine
salt
was
determined
to
exhibit
no
toxicity
(
Toxicity
Category
IV)
to
rats
with
an
LD
50
of
>
5000
mg/
kg
(>
4090
mg
ae/
kg).
The
study
is
scientifically
sound
and
meets
guideline
protocols.

83­
3
Mammalian
Developmental
Rat.
MRID
00131611
(
Acceptable).
In
a
2­
generation
developmental
study,
imazapyr
acid
produced
maternal
toxicity
in
Sprague
Dawley
rats
at
1000
mg
ai/
kg/
day
(
LOAEL),
based
on
salivation
in
the
gravid
dams
between
gestation
days
8­
15.
The
findings
were
determined
to
be
treatment­
related.
The
NOAEL
was
300
mg
/
kg
bw/
day.
No
treatment­
related
effects
were
reported
for
developmental
parameters.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Rabbit.
MRID
00131613
(
Acceptable).
In
a
2­
generation
teratology
study,
imazapyr
acid
produced
no
treatment­
related
effects
for
maternal
or
developmental
parameters;
consequently,
the
NOAEL
for
both
endpoints
was
$
400
mg/
kg
bw/
day
in
New
Zealand
white
rabbits.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

83­
4
Mammalian
Reproduction
E
­
6
Rat.
MRID
41039505
(
Acceptable).
In
a
2­
generation
reproduction
study,
imazapyr
acid
produced
no
treatment­
related
effects
for
maternal
or
developmental
parameters;
consequently,
the
parental
systemic,
reproductive,
and
offspring
NOAEL
was
$
738
mg/
kg
bw/
day
in
males
and
933.3
mg/
kg
bw/
day
in
females.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

122­
2
Aquatic
Plant
Nonvascular
Imazapyr
acid
Green
algae.
MRID
40811802
(
Acceptable).
In
a
Tier
II
toxicity
test
with
Selenastrum
capricornutum,
the
7
day
EC
50
for
cell
density
was
71
mg
ai/
L
(
NOEC
=
50.9
mg
ai/
L).
The
study
is
scientifically
sound
and
meets
the
guideline
protocols.

Blue­
green
algae.
MRID
40811802
(
Acceptable).
In
a
Tier
II
toxicity
test
with
Anabaena
flosaquae
the7­
day
EC
50
for
cell
density
was
12.2
mg
ai/
L
(
NOEC
=
9.6
mg
ai/
L).
The
study
is
scientifically
sound
and
meets
the
guideline
protocols.

Marine
diatom.
MRID
40811802
(
Acceptable).
In
a
Tier
II
toxicity
test
with
Skeletonema
costatum,
the7­
day
EC
50
for
cell
density
was
92
mg
ai/
L
(
NOEC
=
15.9
mg
ai/
L).
The
study
is
scientifically
sound
and
meets
the
guideline
protocols.

Diatom.
MRID
40811802
(
Acceptable).
In
a
Tier
II
toxicity
test
with
Navicula
pelliculosa,
the
7­
day
EC
50
for
cell
density
was
>
41
mg
ai/
L
(
NOEC
=
41
mg
ai/
L).
The
study
is
scientifically
sound
and
meets
the
guideline
protocols.

Imazapyr
isopropylamine
salt
Green
algae.
MRID
43889102
(
Acceptable).
In
a
Tier
II
toxicity
test
with
green
algae,
the
7­
day
EC
50
,
based
on
slight
changes
in
cell
shape
was
11.5
mg
ae/
L
(
NOEC
=
7.16
mg
ae/
L).
The
study
is
scientifically
sound
and
meets
the
guideline
protocols.

123­
1(
a)
Seedling
Emergence
­
Tier
II
Imazapyr
Acid
Monocots
(
4
species)
and
Dicots
(
4
species).
MRID
40811801
(
Supplemental).
In
a
Tier
II
seedling
emergence
study,
the
most
sensitive
monocot
tested
was
wheat
(
EC
25
0.0046
lb
ae/
acre,
EC
05
0.00099
lb
ae/
acre;
shoot
weight).
The
most
sensitive
dicot
tested
was
sugarbeet
(
EC
25
0.0024
lb
ae/
acre,
EC
05
0.00017
lb
ae/
acre;
shoot
weight).
Due
to
deficiencies
in
the
study,
the
guideline
requirements
are
only
partially
fulfilled;
acceptable
data
endpoints
were
used
in
the
risk
assessment.

Nontarget
Terrestrial
Plant
Seedling
Emergence
Toxicity
(
Tier
II)

Species
%
ai
EC25
(
lbs
ai/
A)
NOEC
/
[
EC05]
Endpoint
Affected
MRID
No.
Study
Classification
22.6%
408118­
01
Monocot­
Corn
0.025
0.0156
height
invalid2
Nontarget
Terrestrial
Plant
Seedling
Emergence
Toxicity
(
Tier
II)

Species
%
ai
EC25
(
lbs
ai/
A)
NOEC
/
[
EC05]
Endpoint
Affected
MRID
No.
Study
Classification
E
­
7
Monocot­
Oat
0.054
0.0156
"
supplemental3
Monocot­
Onion
0.034
[
0.01]
A
weight4
supplemental3
Monocot­
Wheat
0.0046
[
0.00099]
A
"
supplemental3
Dicot­
Sunflower
0.0027
[
0.000021]
A
height
invalid2
Dicot­
Soybean
0.012
0.0078
"
invalid2
Dicot­
Pea
0.093
0.0624
weight4
invalid2
Dicot­
Cucumber
0.0043
[
0.000005]
A
"
invalid2
Dicot­
Sugarbeet
0.0024
[
0.00017]
A
"
supplemental3
Dicot­
Tomato
0.008
0.0003
"
supplemental3
1Determination
of
the
most
sensitive
species
is
based
on
EC25
values;
results
are
based
on
the
non­
linear
regression
analysis.
2
Large
seedlings
were
subjected
to
overcrowding,
10
seeds
were
planted
in
a
4­
in
dixie
cup.
3
Small
seedlings
could
be
subjected
to
overcrowding,
10
seeds
were
planted
in
a
4­
in
dixie
cup.
4
Fresh
weight
was
recorded
instead
of
dry
weight.
A
The
NOEC
value
is
above
the
EC25,
equal
to
the
EC25,
or
below
the
lowest
concentration,
an
EC05
value
is
used
instead.
.

123­
1(
b)
Vegetative
Vigor
­
Tier
II
Imazapyr
acid
Monocots
(
4
species)
and
Dicots
(
4
species).
MRID
40811801
(
Supplemental).
In
a
Tier
II
vegetative
vigor
study,
the
most
sensitive
monocot
tested
was
wheat
(
EC
25
0.012
lb
ae/
acre,
NOEC
0.0039
lb
ae/
acre;
shoot
weight).
The
most
sensitive
dicot
tested
was
cucumber
(
EC
25
0.0009
lb
ae/
acre,
EC
05
0.000064
lb
ae/
acre;
shoot
height).
Due
to
deficiencies
in
the
study,
the
guideline
requirements
are
partially
fulfilled;
acceptable
data
endpoints
were
used
in
the
risk
assessment.

Species
%
a.
i.
EC
25
(
lbs
ae/
A)
NOEC
[
EC05]
(
lbs
ae/
A)
Endpoint
affected
MRID
No.
Study
classification
22.6%
408118­
01
Monocot­
Corn
>
0.0156A
0.0078
weight2
supplemental3
Monocot­
Oats
0.013
0.0039
height
supplemental3
Monocot­
Onion
­­
­­
n/
aC
invalid
Monocot­
Wheat
0.012
0.0039
weight2
supplemental3
Dicot­
Soybean
­­
­­
n/
aC
invalid
Dicot­
Pea
­­
­­
n/
aC
invalid
Dicot­
Sugarbeet
0.00097
[
0.00039]
B
weight2
supplemental3
Species
%
a.
i.
EC
25
(
lbs
ae/
A)
NOEC
[
EC05]
(
lbs
ae/
A)
Endpoint
affected
MRID
No.
Study
classification
E
­
8
Dicot­
Sunflower
0.0054
0.0039
weight2
supplemental3
Dicot­
Cucumber
0.0009
[
0.000064]
B
height
supplemental3
Dicot­
Tomato
>
0.0156A
0.00097
weight2
supplemental3
1Determination
of
the
most
sensitive
species
is
based
on
EC25
values.
2
Fresh
weight
was
recorded
instead
of
dry
weight.
3
the
toxicity
values
could
be
underestimated
since
the
study
was
tested
with
older
plants
(
28D)
at
a
less
sensitive
stage
of
growth
(
timing
of
application).
A
The
EC25
value
is
above
the
highest
concentration
tested.
B
The
NOEC
value
is
above
the
EC25,
equal
to
the
EC25,
or
below
the
lowest
concentration,
an
EC05
value
is
used
instead.
C
No
data
Imazapyr
isopropylamine
salt
Monocots
(
3
species)
and
Dicots
(
2
species).
MRID
43889101
(
Core).
In
a
Tier
II
vegetative
vigor
study,
chlorosis,
stunting,
and
plant
death.
The
most
sensitive
monocot
tested
was
onion
(
EC
25
0.010
lb
ae/
acre,
NOEC
0.004
lb
ae/
acre;
shoot
weight).
The
most
sensitive
dicot
tested
was
sugar
beet
(
EC
25
0.0016
lb
ae/
acre,
NOEC
0.0008
lb
ae/
acre;
shoot
weight).
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Monocots
(
4
species)
and
Dicots
(
4
species).
MRID
40003711
(
Supplemental).
This
study
was
a
modified
Tier
II
vegetative
vigor
study
that
did
not
meet
guideline
requirements.
Only
descriptive
summary
data
was
presented;
consequently
effect
levels
were
not
determined.
Observed
effects
included
chlorosis,
stunting,
leaf
tip
burning,
necrosis,
and
plant
death.

123­
2
Aquatic
Plant
Vascular
Imazapyr
acid
Duckweed.
MRID
40811802
(
Acceptable).
In
a
14­
day
toxicity
test
with
duckweed,
the
EC
50
for
frond
production
was
0.024
mg
ai/
L
and
the
NOEC
was
0.01
mg
ai/
L.
Imazapyr
is
considered
highly
toxic
and
expected
to
exert
a
detrimental
effect
on
vascular
aquatic
plants.
The
study
is
scientifically
sound
and
meets
guideline
protocols.

Imazapyr
isopropylamine
salt
Duckweed.
MRID
43889102
(
Acceptable).
In
a
14­
day
toxicity
test
with
duckweed,
the
EC
50
for
frond
production
was
0.018
mg
ai/
L
and
the
NOEC
was
0.011
mg
ai/
L.
The
study
is
scientifically
sound
and
meets
guideline
protocols.
E
­
9
141­
5
Acute
Honey
Bee
Contact
Honey
Bee.
MRID
00131637
(
Acceptable).
In
a
48­
hour
acute
contact
study
with
the
honey
bee,
imazapyr
acid
was
determined
to
be
practically
non­
toxic
to
honey
bees
and
the
LD
50
was
>
100
µ
g/
bee.
The
study
is
scientifically
sound
and
meets
guideline
protocols.
