Page
1
of
18
Overview
of
the
2,4­
D
Risk
Assessments
June
18,
2004
Introduction
This
document
summarizes
EPA's
human
health
and
ecological
risk
findings
and
conclusions
for
the
herbicide
2,4­
dichlorophenoxyactic
acid
(
2,4­
D),
as
presented
fully
in
the
documents,
2,4­
D.
HED's
Human
Health
Risk
Assessment
for
the
Reregistration
Eligibility
Decision
(
RED)
Revised
to
Reflect
Error­
only
Comments
from
Registrants,
dated
June
2,
2004,
and
the
Environmental
Fate
and
Effects
Division's
Risk
Assessment
for
the
Reregistration
Eligibility
Document
for
2,4­
Dichlorophenoxyacetic
Acid
(
2,4­
D),
dated
May
24,
2004.
These
documents
also
summarize
the
HED
and
EFED
response
to
comments
as
submitted
by
the
registrants
and
the
2,4­
D
Task
Force,
during
Phase
I
of
the
Public
Participation
Process.
The
purpose
of
this
summary
is
to
assist
the
reader
by
identifying
the
key
features
and
findings
of
these
risk
assessments
and
conclusions
reached
in
the
assessments.
This
overview
was
developed
in
response
to
comments
and
requests
from
the
public
which
indicated
that
the
risk
assessments
were
difficult
to
understand,
that
they
were
too
lengthy,
and
that
it
was
not
easy
to
compare
the
assessments
for
different
chemicals
due
to
the
use
of
different
formats.

The
risk
assessments
for
2,4­
D
will
be
made
available
to
the
public
in
EPA's
Pesticide
Docket,
and
will
be
posted
on
the
Internet.
Once
the
risk
assessments
are
available
to
the
public,
there
will
be
an
opportunity
for
the
public
to
view
them
and
to
comment
on
them.
Public
comments
will
be
invited
and
welcomed.
This
feedback
will
be
used
to
complete
the
Reregistration
Eligibility
Decision
(
RED)
document,
which
will
include
the
resultant
risk
management
decisions.
These
documents,
in
hard
copy
form,
may
be
viewed
in
the
OPP
docket
room
and
public
comments
may
be
submitted
to
the
OPP
public
docket
under
OPP­
2004­
0167,
located
in
Room
119,
Crystal
Mall
#
2,
1921
Jefferson
Davis
Highway,
Arlington,
VA
or
viewed
via
the
Internet
and
public
comments
may
be
submitted
to
the
OPP
electronic
docket
at:
www.
epa.
gov.
edockets
under
the
same
docket
number.
In
addition,
documents
may
be
downloaded
or
viewed
via
the
Internet
at:
www.
epa.
gov/
pesticides/
reregistration/.

Use
Profile
$
Herbicide:
2,4­
D
is
a
herbicide
in
the
phenoxy
family
used
for
selective
control
of
broadleaf
weeds.
2,4­
D,
a
synthetic
auxin
herbicide,
causes
disruption
of
plant
hormone
responses.
Plant
injuries
include
growth
and
reproduction
abnormalities,
especially
on
new
growth.
Symptoms
may
appear
on
young
growth
almost
immediately
after
application,
but
death
may
not
occur
for
several
weeks.
2,4­
D
formulations
are
typically
applied
as
broadcast,
banded,
or
directed
(
spray
or
wiper)
applications
during
dormancy
or
preplant,
preharvest,
preemergence,
emergence,
postemergence,
or
postharvest
using
ground
or
aerial
equipment.
Registered
forms
of
2,4­
D
incude
2,4­
D
acid,
2,4­
D
Page
2
of
18
dimethylamine
salt
(
DMAS),
2,4­
D
isopropyl
acid
(
IPA),
2,4­
D
triisopropyl
acid
(
TIPA),
2,4­
D
ethylhexyl
ester
(
EHE),
2,4­
D
butoxy
ethyl
ester
(
BEE),
2,4­
D
diethyl
amine
(
DEA),
2,4­
D
isopropyl
ester
(
IPE),
and
2,4­
D
sodium
salt.

$
Use
Sites:
In
terms
of
pounds,
total
2,4­
D
usage
is
allocated
mainly
to
pasture/
rangeland
(
24%),
lawn
by
homeowners
with
fertilizer
(
12%),
Spring
wheat
(
8%),
Winter
wheat
(
7%),
lawn/
garden
by
lawn
care
operators/
landscape
maintenance
contractors
(
7%),
lawn
by
homeowners
alone
(
without
fertilizer)
(
6%),
field
corn
(
6%),
soybeans
(
4%),
summer
fallow
(
3%),
hay
other
than
alfalfa
(
3%)
and
roadways
(
3%).
Agricultural
sites
with
at
least
10%
of
U.
S.
acreage
treated
include
Spring
wheat
(
51%),
filberts
(
49%),
sugarcane
(
36%),
barley
(
36%),
seed
crops
(
29%),
apples
(
20%),
rye
(
16%),
Winter
wheat
(
15%),
cherries
(
15%),
oats
(
15%),
millet
(
15%),
rice
(
13%),
soybeans
(
12%)
and
pears
(
10%).

$
Tolerances:
Tolerances
are
currently
established
for
residues
of
2,4­
D
in/
on:
numerous
raw
agricultural
commodity
(
RAC)
human
foods
derived
from
fruits,
grasses,
grains,
nuts,
vegetables,
sugarcane,
cotton,
hops,
and
asparagus
at
0.1
ppm
to
5
ppm;
processed
products
of
sugarcane
(
5
ppm)
and
grains
(
2
ppm);
fish
and
shellfish
at
1.0
ppm
and
potable
water
at
0.1
ppm
[
40
CFR
§
180.142(
a)(
1­
6
and
9­
13)].
A
temporary
tolerance
of
0.02
ppm
for
2,4­
D
per
se
in/
on
soybean
seed
will
expire
on
12/
31/
04
[
40
CFR
§
180.142(
a)(
11)].
A
time­
limited
tolerance
of
0.1
ppm
in/
on
wild
rice
established
under
FIFRA
Section
18
will
expire
12/
31/
05.
Tolerances
for
residues
in
livestock
commodities
are
currently
established
in
terms
of
residues
of
2,4­
D
and/
or
its
metabolite
2,4­
dichlorophenol
[
40
CFR
§
180.142(
a)(
8)].

$
Formulations:
Formulation
types
registered
include
emulsifiable
concentrate,
granular,
soluble
concentrate/
solid,
water
dispersible
granules
(
dry
flowable),
and
wettable
powder.

$
Method
of
Application:
2,4­
D
may
be
applied
with
a
wide
range
of
application
equipment
including
aircraft,
backpack
sprayer,
band
sprayer,
boom
sprayer,
granule
applicator,
ground,
hand
held
sprayer,
helicopter;
injection
equipment,
tractor­
mounted
granule
applicator,
and
tractor­
mounted
sprayers.
Methods
of
application
of
2,4­
D
may
include
band
treatment,
basal
spray
treatment,
broadcast,
frill
treatment,
girdle
treatment,
ground
spray,
soil
band
treatment,
soil
broadcast
treatment,
spot
treatment,
stump
treatment,
tree
injection
treatment,
and
water
related
surface
treatment.

$
Use
Rates:
For
2,4­
D,
rates
per
application
and
rates
per
year
are
generally
less
than
or
equal
to
1.50
pounds
acid
equivalents
(
ae)
per
acre
(
lbs
ae/
A)
and
2.00
lbs
ae/
A,
respectively.

$
Annual
Poundage:
Based
primarily
on
pesticide
usage
information
from
1992
through
2000
for
agriculture
and
1993
through
1999
for
non­
agriculture,
total
annual
domestic
usage
of
2,4­
D
is
approximately
46
million
pounds,
with
30
million
pounds
(
66%)
used
by
agriculture
and
16
million
pounds
(
34%)
used
by
non­
agriculture.
2,4­
D
is
used
predominantly
in
the
Midwest,
Great
Plains,
and
Northwestern
United
States.
Page
3
of
18
$
Technical
Registrants:
Industry
Task
Force
II
on
2,4­
D
Research
Data.
Members
include:
Agro­
Gor
Corp
(
jointly
owned
by
Attanor,
S.
A.
and
PBI­
Gordon
Corp.),
Dow
AgroSciences,
and
Nufarm
USA.

Human
Health
Risk
Assessment
In
laboratory
animals,
following
subchronic,
oral
exposure
at
dose
levels
of
2,4­
D
above
the
threshold
of
saturation
for
renal
clearance,
the
primary
target
organs
are
the
eye,
thyroid,
kidney,
adrenals,
and
ovaries/
testes.
2,4­
D
is
classified
as
a
Group
D
chemical
(
not
classifiable
as
to
human
carcinogenicity).
2,4­
D
acid
is
currently
considered
to
be
representative
of
all
nine
member
chemicals
of
the
2,4­
D
case.

Acute
Dietary
(
Food)
Risk
(
For
a
compete
discussion,
see
section
3.0
of
the
Human
Health
Risk
Assessment)

Acute
dietary
risk
is
calculated
considering
what
is
eaten
in
one
day
and
maximum,
or
high­
end
residue
values
in
food.
A
risk
estimate
that
is
less
than
100%
of
the
acute
Population
Adjusted
Dose
(
aPAD),
the
dose
at
which
an
individual
could
be
exposed
on
any
given
day
and
no
adverse
health
effects
would
be
expected,
does
not
exceed
the
Agency's
level
of
concern.
The
aPAD
is
the
acute
reference
dose
(
aRfD)
adjusted
for
the
FQPA
Safety
Factor.

°
Acute
dietary
(
food)
risks
are
all
less
than
the
Agency's
level
of
concern
(
i.
e.,
less
than
100%
of
the
aPAD).
Acute
dietary
risks
were
calculated
using
both
Lifeline
and
DEEM
software.
Lifeline
and
DEEM
are
computer
models
that
calculate
estimated
exposure
concentrations.
°
For
females
13­
50
years
of
age,
the
toxicological
endpoint
is
skeletal
abnormalities
as
seen
at
the
lowest
observed
adverse
effect
level
(
LOAEL)
of
75
mg/
kg/
day
in
the
rat
developmental
toxicity
study
The
no
observed
adverse
effect
level
(
NOAEL)
in
this
study
is
25
mg/
kg/
day.

$
For
the
general
population
including
infants
and
children,
the
toxicological
endpoint
is
gait
abnormalities
as
seen
at
the
lowest
observed
adverse
effect
level
(
LOAEL)
of
227
mg/
kg/
day
in
the
acute
neurotoxicity
study
in
rats.
The
no
observed
adverse
effect
level
(
NOAEL)
in
this
study
is
67
mg/
kg/
day.
°
Risk
to
the
general
U.
S.
population
was
17%
of
the
aPAD
using
both
DEEM
and
Lifeline.
°
The
most
highly
exposed
population
subgroup
using
both
DEEM
and
Lifeline
was
children
1­
2
years
of
age;
risks
were
33%
and
30%
of
the
aPAD,
respectively.
°
Although
not
the
most
highly
exposed
population
subgroup,
risk
to
females
13­
49
years
of
age
was
31%
of
the
aPAD
using
DEEM
and
42%
of
the
aPAD
using
Lifeline;
these
higher
risks
are
due
to
the
2.7x
lower
NOAEL
for
developmental
effects
applicable
to
the
acute
dietary
risk
assessment
of
Females
13­
49
years
of
Page
4
of
18
age.

$
A
10x
database
uncertainty
factor
has
been
assessed
based
on
the
need
for
a
developmental
neurotoxicity
study
in
the
rat,
and
a
2­
generation
reproduction
study
with
special
emphasis
on
thyroid
and
immunotoxic
effects.

Chronic
Dietary
(
Food)
Risk
(
For
a
compete
discussion,
see
section
3.0
of
the
Human
Health
Risk
Assessment)

The
chronic
dietary
assessment
was
moderately
refined,
making
use
of
the
following:
tolerance­
level
exposure
values
for
most
commodities;
averages
of
field
trial
data
and
processing
study
factors
for
small
grains,
citrus,
and
sugarcane
sugar
and
molasses;
%
crop
treated
(
CT)
information
for
all
commodities;
and
the
MCL
(
70
ppb)
as
well
as
the
highest
observed
groundwater
monitoring
concentration
(
15
ppb)
for
drinking
water
in
a
forward
calculation.
As
in
the
case
of
the
acute
assessment,
one­
half
the
value
for
the
average
limit
of
detection
(
LOD)
from
PDP
monitoring
data
was
used
for
milk.

°
Chronic
dietary
risks
are
all
less
than
the
Agency's
level
of
concern
(
i.
e.,
less
than
100%
of
the
aPAD).
°
The
toxicological
endpoints
are
decreased
body­
weight
gain
(
females)
and
food
consumption
(
females),
alterations
in
blood
cell
and
blood
chemistry
parameters,
increased
thyroid
weights
(
both
sexes),
and
decreased
testes
and
ovarian
weights,
as
seen
at
the
lowest
observed
adverse
effect
level
(
LOAEL)
of
75
mg/
kg/
day
in
the
rat
chronic
toxicity
study.
The
no
observed
adverse
effect
level
(
NOAEL)
in
this
study
is
5
mg/
kg/
day.
°
For
food
consumption
only,
chronic
dietary
(
food
only)
risks
calculated
using
the
DEEM
software
consumed
2.5­
6.9%
of
the
cPAD
(
2.5­
6.7%
cPAD
using
Lifeline).
°
Risk
to
the
general
U.
S.
population
was
3.4%
of
the
cPAD
using
DEEM
and
3.2%
cPAD
using
Lifeline.
°
Risk
to
children
1­
2
years
of
age,
the
most
highly
exposed
population
subgroup,
was
6.9%
of
the
cPAD
using
DEEM
and
6.7%
cPAD
using
Lifeline.

Drinking
Water
Dietary
Risk
Drinking
water
exposure
to
pesticides
can
occur
through
groundwater
and
surface
water
contamination.
EPA
considers
both
acute
(
one
day)
and
chronic
(
lifetime)
drinking
water
risks
and
uses
either
modeling
or
actual
monitoring
data,
if
available,
to
estimate
those
risks.
To
determine
the
maximum
allowable
contribution
from
water
allowed
in
the
diet,
EPA
first
looks
at
how
much
of
the
overall
allowable
risk
is
contributed
by
food
and
then
determines
a
"
drinking
water
level
of
comparison"
(
DWLOC)
to
ascertain
whether
modeled
or
monitored
concentration
levels
exceed
this
level.

The
Agency
uses
the
DWLOC
calculation
to
estimate
risk
associated
with
exposure
from
Page
5
of
18
pesticides
in
drinking
water.
The
DWLOCs
represent
the
maximum
contribution
to
the
human
diet
(
in
ppb
or
ug/
L)
that
may
be
attributed
to
residues
of
a
pesticide
in
drinking
water
after
dietary
exposure
is
subtracted
from
the
aPAD
or
the
cPAD.
Risks
from
drinking
water
are
assessed
by
comparing
the
DWLOCs
to
the
estimated
environmental
concentrations
(
EECs)
in
surface
water
and
groundwater.
EECs
less
than
the
DWLOC
are
not
of
concern.
Drinking
water
modeling
is
considered
to
be
an
unrefined
assessment
and
generally
provides
high­
end
estimates.

For
the
current
assessment,
EECs
were
derived
through
an
evaluation
of
monitoring
data
and
modeling.
A
number
of
different
scenarios
were
assessed
and
EECs
provided
for
each.
Scenarios
evaluated
included
the
direct
application
of
2,4­
D
to
water
bodies
for
aquatic
weed
control,
a
rice
use
scenario,
and
terrestrial
uses
including
food
and
nonfood
uses.
Although
of
high
quality,
the
available
monitoring
data
is
not
targeted
to
2,4­
D
use.
However,
the
data
provide
context
to
model
results
and
indicate
that
there
is
little
evidence
that
concentrations
are
likely
to
be
found
exceeding
these
estimates.
In
addition,
several
registrant­
submitted
aquatic
dissipation
studies
provide
additional
context
to
the
scenarios
discussed
below.

°
Acute
water
risk:
°
The
lowest
acute
DWLOC
is
450
ppb
for
children
1­
2
years
old
which
is
higher
than
the
estimated
drinking
water
concentration
(
EDWC)
of
70
ppb
(
aquatic
weed
control),
118
ppb
(
terrestrial
use,
or
280
ppb
(
calculated
from
MCL)
applicable
to
surface
water,
as
well
as
the
groundwater
EDWC
of
15
ppb.
°
If
it
is
determined
that
for
aquatic
weed
contol
use,
the
70­
ppb
label
restriction
is
practical,
enforceable,
and
uniformly­
applied,
acute
aggregate
risk
estimates
associated
with
exposure
to
2,4­
D
residues
in
food
and
drinking
water
do
not
exceed
HED's
level
of
concern.
However,
if
the
opposite
determination
is
made,
the
modeled
peak
concentration
of
811
ppb
is
above
the
DWLOCs
calculated
for
infants,
children,
and
females
13­
49
years
old,
thus
creating
at
least
an
apparent
risk
that
exceeds
the
Agency's
level
of
concern.

°
Chronic
water
risk:
DWLOCs
were
not
calculated
for
the
chronic
aggregate
assessment
because,
as
per
recent
policy,
drinking
water
exposure
to
2,4­
D
is
included
directly
in
the
overall
dietary
risk
using
the
DEEM
and
Lifeline
software
to
generate
a
quantitative
aggregate
assessment.
Page
6
of
18
Dermal
and
Inhalation
Toxicity
The
following
endpoints
were
used
to
determine
residential,
aggregate,
and
occupational
risk.
°
Short­
term
incidental
oral,
dermal,
and
inhalation
exposures:
LOAEL
of
75
mg/
kg/
day
and
NOAEL
of
25
mg/
kg/
day,
based
on
decreased
maternal
bodyweight
gain
and
skeletal
malformations
and
skeletal
variations
from
the
rat
developmental
toxicity
study.
°
Intermediate­
term
and
long­
term
incidental
oral,
dermal,
and
inhalation
exposures
are
not
expected
based
on
the
2,4­
D
use
scenarios.

Note
that
the
dermal
absorption
rate,
as
determined
from
a
human
dermal
absorption
study,
is
5.8%
of
that
absorbed
via
the
oral
route
for
all
dermal
exposure
durations.
As
there
is
no
available
repeat­
dose
2,4­
D
inhalation
study,
absorption
via
the
inhalation
route
is
assumed
to
be
equivalent
to
oral
absorption,
i.
e.,
100%.
All
of
the
above
exposure
routes
and
durations
are
applicable
to
the
residential
setting.
A
10x
database
uncertainty
factor
has
been
assessed
based
on
the
need
for
a
developmental
neurotoxicity
study
in
the
rat,
and
a
2­
generation
reproduction
study
with
special
emphasis
on
thyroid
and
immunotoxic
effects.
Therefore,
the
target
residential
MOE
=
1000
for
assessment
of
incidental
oral,
dermal,
and
inhalation
risks.

Residential
Risk
(
For
a
complete
discussion,
see
section
4.4
of
the
Human
Health
Risk
Assessment)

According
to
the
EPA
Pesticide
Sales
and
Usage
Report
for
1998/
1999,
2,4­
D
is
the
most
commonly
used
conventional
pesticide
active
ingredient
in
the
home
and
garden
market
sector
with
7
to
9
million
pounds
applied
per
year.
It
is
also
the
most
commonly
used
conventional
active
ingredient
in
the
Industry/
Commercial/
Government
market
section
with
17
to
20
million
pound
applied
per
year.
This
segment
includes
applications
to
homes
and
gardens
by
professional
applicators.

$
The
residential
products
are
typically
formulated
as
dry
weed
and
feed
products
or
as
liquids
in
concentrates
or
ready
to
use
sprays.

$
Many
of
these
formulations
include
other
phenoxy
herbicides
such
as
MCPP­
p
and
dicamba.

$
Both
spot
and
broadcast
treatments
are
included
on
the
labels.
Exposures
are
expected
to
be
short­
term
in
duration
for
broadcast
treatments
because
the
label
allows
only
two
broadcast
treatments
per
year.
Exposures
are
also
expected
to
be
short­
term
in
duration
for
spot
treatments
because
the
labels
recommend
repeat
applications
for
hard
to
kill
weeds
in
two
to
three
weeks.
Page
7
of
18
Residential
Applicator
(
Handler)

°
A
summary
of
the
MOE
calculations
for
homeowner
lawn
applicators
is
included
in
Table
1.
All
of
the
MOEs
are
greater
than
the
target
MOE
of
1000
and
are
not
of
concern.

Table
1.
2,4­
D
Short­
term
MOEs
for
Homeowner
Applications
to
Lawns
Scenario
Application
Rate
(
lbs
ae/
acre)
Treated
Area
(
acres/
day)
MOE
1
Hand
Application
of
Granules
2.0
0.023
4,600
2
Belly
Grinder
Application
2.0
0.023
5,100
3.
Load/
Apply
Granules
with
a
Broadcast
Spreader
2.0
0.5
38,000
4.
Mix/
Load/
Apply
with
a
Hose­
end
Sprayer
(
Mix
your
own)
2.0
0.5
2,300
5.
Mix/
Load/
Apply
with
a
Hose­
end
Sprayer
(
Ready
to
Use)
2.0
0.5
9,300
6.
Mix/
Load/
Apply
with
Hand
Held
Pump
Sprayer
2.0
0.023
15,000
7.
Mix/
Load/
Apply
with
Ready
to
Use
Sprayer
2.0
0.023
10,000
Note:
1000
square
feet
equals
0.023
acres
Residential
Postapplication­
Turf
Use
°
MOEs
resulting
from
both
short­
term
(
California
turf
transferrable
residue
(
TTR)
data
only)
and
one­
day
toddler
postapplication
exposures
(
i.
e.,
hand­
to­
mouth,
object­
tomouth
and
soil
ingestion)
to
treated
turf
were
1000,
just
matching
the
Agency's
level
of
concern.
In
the
case
of
adults,
the
one­
day/
short­
term
postapplication
exposure
MOEs
were
1300
for
heavy
yardwork
and
19000
for
playing
golf:
neither
scenario
is
of
Agency
concern.

Residential
Postapplication­
Aquatic
Use
The
master
label
indicates
that
2,4­
D
can
be
used
for
aquatic
weed
control
of
surface
weeds
such
as
Water
Hyacinth
and
submersed
weeds
such
as
Eurasian
Milfoil.
Surface
weeds
are
controlled
by
foliar
spray
applications
at
a
maximum
rate
of
2.0
lb
ae/
acre.
Submersed
weeds
can
be
controlled
by
subsurface
injection
of
liquids
to
achieve
a
target
concentration
of
2
to
4
ppm
in
the
water
column
surrounding
the
weeds.
Although
many
herbicide
treatments
are
applied
to
aquatic
areas
where
recreational
swimming
is
not
likely
to
occur,
some
of
the
subsurface
treatments
are
made
at
recreational
lakes.
These
treatments
are
made
because
the
Eurasian
Milfoil
interferes
with
recreation
and
other
activities.
This
problem
is
particularly
prevalent
in
northern
states
such
as
Minnesota,
Pacific
Northwest
states
such
as
Washington,
and
in
the
New
England
region.
Page
8
of
18
$
Potential
post­
application
residential
exposure
scenarios
that
result
from
the
aquatic
use
of
2,4­
D
include
dermal
exposure
and
incidental
ingestion
of
water.

$
All
of
the
dermal
MOEs
meet
or
exceed
the
target
MOE
of
1000,
and
are
thus
not
of
concern,
when
2,4­
D
acid
or
2,4­
D
DMA
is
used,
because
these
forms
have
very
low
skin
permeability
coefficients.

$
Both
the
one­
day
and
short­
term
dermal
MOEs
are
of
concern
when
2,4­
D
BEE
is
used
because
2,4­
D
BEE
has
a
relatively
high
skin
permeability
coefficient.

$
The
ingestion
MOEs
are
of
concern
for
short­
term
children's
exposure
and
are
not
dependent
on
the
form
used.

$
If
a
lower
target
concentration
of
2
ppm
is
used,
the
MOEs
for
ingestion
rise
to
above
1000;
however,
the
dermal
MOEs
remain
below
1000
for
2,4­
D
BEE
exposures.

Aggregate
Risk
(
For
a
complete
discussion,
see
section
5.0
of
the
Human
Health
Risk
Assessment)

Aggregate
risk
looks
at
the
combined
risk
from
exposure
through
food,
drinking
water,
and
residential
uses
of
a
pesticide.
Generally,
all
risks
from
these
exposures
must
occupy
less
than
100
percent
of
the
PAD
to
be
below
the
Agency's
level
of
concern.

For
aggregate
risk,
EPA
considers
the
combined
exposures
from
food
and
residential
sources
and
calculates
a
DWLOC
(
as
described
above
in
the
drinking
water
section)
which
represents
the
maximum
allowable
exposure
through
drinking
water
after
considering
the
food
and
residential
exposures.
If
the
water
estimated
environmental
concentrations
(
EECs)
are
less
than
the
DWLOCs,
EPA
does
not
have
concern
for
aggregate
exposure.
As
noted
above,
DWLOCs
were
not
calculated
for
the
chronic
aggregate
assessment
because,
as
per
recent
policy,
drinking
water
exposure
to
2,4­
D
is
included
directly
in
the
overall
dietary
risk
using
the
DEEM
and
Lifeline
software
to
generate
a
quantitative
aggregate
assessment.

Aggregate
risk
assessments
for
2,4­
D
were
conducted
as
follows:
acute
and
chronic
aggregate
assessments
were
conducted
based
on
food
and
water
exposures
and
one­
day,
shortterm
and
intermediate­
term
aggregate
assessments
were
conducted
based
on
food,
water,
and
residential
exposures.
No
long­
term
aggregate
risk
assessment
was
conducted
because
no
longterm
exposure
scenarios
are
expected
from
residential
uses
of
2,4­
D.

Acute
Aggregate
To
estimate
aggregate
acute
risks,
DWLOCs
were
calculated.
Table
2
summarizes
the
acute
DWLOCs
calculated
for
the
various
population
subgroups
indicated.

°
The
lowest
acute
DWLOC
is
450
ppb
for
children
1­
2
years
old
which
is
higher
than
the
EDWC
of
70
ppb,
118
ppb,
or
280
ppb
applicable
to
surface
water
as
well
Page
9
of
18
as
the
groundwater
EDWC
of
15
ppb,
and
therefore,
does
not
exceed
EPA's
level
of
concern.
If
it
is
determined
that
the
70­
ppb
label
restriction
is
practical,
enforceable,
and
uniformly­
applied,
acute
aggregate
risk
estimates
associated
with
exposure
to
2,4­
D
residues
in
food
and
drinking
water
would
not
exceed
HED's
level
of
concern.
°
However,
if
the
opposite
determination
is
made,
and
a
1500
ft
set
back
restriction
was
added
to
the
label,
the
modeled
peak
concentration
of
811
ppb
is
above
the
DWLOCs
of
450­
540
ppb
calculated
for
infants,
children,
and
females
13­
49
years
old,
thus
creating
at
least
an
apparent
risk
that
exceeds
the
Agency's
level
of
concern.

Table
2.
Acute
DWLOC
Calculations.

Population
Subgroup
aPAD
(
mg/
kg/
day)
Food
Exp
(
mg/
kg/
day)
Max
Water
Exp
(
mg/
kg/
daya)
Ground
Water
EEC
(
µ
g/
L)
Surface
Water
EEC
(
µ
g/
L)
DWLOC
(

g/
L)
b
General
U.
S.
Population
0.067
0.011710
0.055290
15
70
(
aquatic)
or
118
(
terrestrial
or
240
(
calculated
from
MCL)
1900
All
Infants
(<
1
year
old)
0.012766
0.054234
540
Children
1­
2
years
old
0.022134
0.044866
450
Children
3­
5
years
old
0.020610
0.046390
460
Children
6­
12
years
old
0.014632
0.052368
520
Youth
13­
19
years
old
0.009140
0.057860
1700
Adults
20­
49
years
old
0.008645
0.058355
2000
Adults
50+
years
old
0.006563
0.060437
2100
Females
13­
49
years
old
0.025
0.007675
0.017325
520
a
Maximum
water
exposure
(
mg/
kg/
day)
=
[(
acute
PAD
(
mg/
kg/
day)
­
food
exposure
(
mg/
kg/
day)]
b
DWLOC
(

g/
L)
=
[
maximum
water
exposure
(
mg/
kg/
day)
x
body
weight
(
kg)]
÷
[
water
consumption
(
L)
x
10­
3
mg/

g].
Consumption
=
1
L/
day
for
populations
<
13
years
old
and
2
L/
day
for
populations

13
years
old.
Default
body
weights
=
70
kg
for
adults
>
20
years
old
and
general
U.
S.
population,
60
kg
for
females

13
years
old
and
youth
13­
19
years
old,
and
10
kg
for
all
others.
Values
are
rounded
to
2
significant
figures.

Chronic
Aggregate
If
both
the
1500­
ft
setback
and
the
70­
ppb
maximum
limit
on
the
Task
Force
II
Master
Label
are
present
on
all
aquatic
use
labels
and
if
both
of
these
restrictions
are
determined
to
be
practical,
enforceable,
and
universally­
applied,
then
chronic
dietary
exposure
to
2,4­
D
(
food
plus
water
sources)
leads
to
risks
that
are
less
than
the
Agency's
level
of
concern
(
100%
of
the
cPAD)
for
all
population
subgroups
reflecting
food
plus
drinking
water
residues.

One­
day/
Short­
term
Aggregate
One­
day
and
short­
term
risk
estimates
associated
with
exposure
to
2,4­
D
residues
on
Page
10
of
18
lawns
and
via
recreational
activities
(
swimming
or
golfing)
exactly
meet
or
exceed
HED's
level
of
concern
(
MOE's
<
1000)
for
the
following
scenarios:
°
toddlers
exposed
postapplication
to
2,4­
D­
treated
lawns
(
MOE
=
1,000
for
one
scenario);
°
adults
swimming
in
2,4­
D
BEE­
treated
water
(
MOE
=
310);
°
22­
kg
child
swimming
in
2,4­
D
acid­
and
2,4­
D
DMA­
treated
water
(
MOE
=
920);
and
°
22­
kg
child
swimming
in
2,4­
D
BEE­
treated
water
(
MOE
=
220).
°
All
of
these
one­
day
and
short­
term
residential
or
recreational
risks
alone
are
either
of
Agency
concern
(
i.
e.,
MOEs
are
less
than
the
target
of
1000)
or
they
just
meet
the
target
MOE
of
1000
and
would
be
of
Agency
concern
if
additional
2,4­
D
exposure
due
to
consumption
of
food
or
drinking
water
were
aggregated.

Occupational
Risk
(
For
a
compete
discussion,
see
section
7.0
of
the
Human
Health
Risk
Assessment)

Workers
can
be
exposed
to
a
pesticide
through
mixing,
loading,
or
applying
the
pesticide,
and
reentering
a
treated
site.
Worker
risk
is
measured
by
a
Margin
of
Exposure
(
MOE)
which
determines
how
close
the
occupational
exposure
comes
to
the
NOAEL
taken
from
animal
studies.
Generally,
MOEs
that
are
greater
than
100
do
not
exceed
the
Agency's
level
of
concern.

The
following
assumptions
and
factors
were
used
in
order
to
complete
the
exposure
and
risk
assessments
for
occupational
handlers/
applicators:

$
The
average
work
day
was
8
hours.

$
A
listing
of
application
methods
and
amounts
of
acreage
treated
per
8
hour
day
is
included
in
Table
17.


The
application
rate
for
submerged
aquatic
weeds
is
based
upon
the
master
label
rate
of
10.8
lbs
a.
i.
per
acre
foot
times
an
average
lake
depth
of
5
feet.


Maximum
application
rates
and
daily
acreage
were
used
to
evaluate
short
term
exposures.


Average
application
rates
were
used
to
evaluate
intermediate
term
exposures.


A
body
weight
of
60
kg
was
assumed
for
short­
term
exposures
because
the
shortterm
endpoint
relates
to
females
13­
50
years
of
age.


A
body
weight
of
70
kg
was
assumed
for
intermediate­
term
exposures
because
the
intermediate­
term
endpoint
is
not
gender­
specific.


The
dermal
absorption
rate
is
5.8%.


The
inhalation
absorption
rate
is
100%.


Baseline
PPE
includes
long
sleeve
shirts,
long
pants
and
no
gloves
or
respirator.


Single
Layer
PPE
includes
baseline
PPE
with
gloves.


Double
Layer
PPE
includes
coveralls
over
single
layer
PPE

Double
Layer
PPE
PF5
includes
above
with
a
PF5
respirator
(
i.
e.
a
dustmask)


Double
Layer
PPE
PF10
includes
above
with
a
PF10
cartridge
respirator
Page
11
of
18

Only
closed
cockpit
airplanes
are
used
for
aerial
application.


There
are
very
few
exposure
data
to
evaluate
the
exposure
in
rotary­
winged
aircraft;
therefore,
the
exposure
data
for
fixed­
wing
aircraft
are
used
as
a
surrogate.


Airplane
and
helicopter
pilots
do
not
wear
chemical
resistant
gloves.

Based
on
currently
registered
use
sites,
formulations,
and
types
of
equipment
commonly
used
for
mixing,
loading,
and
application,
EPA
has
identified
18
major
occupational
handler
scenarios.


With
the
exception
of
mixing/
loading
wettable
powder,
the
short­
term
and
intermediate­
term
MOEs
are
greater
than
the
target
of
100
with
baseline
or
single
layer
PPE
and
are
not
of
concern.
The
MOEs
for
handling
wettable
powder
are
greater
than
100
with
engineering
controls
(
i.
e.
water­
soluble
bags).


The
labels
typically
require
single­
layer
PPE
for
applicators
and
handlers
and
that
a
mechanical
system
(
probe
and
pump
or
spigot)
be
used
for
containers
of
5
gallons
or
more.
The
mechanical
system
is
not
required
for
1
to
5
gallon
containers;
however,
additional
PPE
(
coveralls
or
a
chemical
resistant
apron)
are
required
if
the
mechanical
system
is
not
used.


Most
of
the
wettable
powder
products
are
packaged
in
water­
soluble
bags.

Occupational
Postapplication
Exposures
and
Risk
To
provide
weed
control
without
damaging
crops,
2,4­
D
applications
are
made
during
the
dormant
season
or
prior
to
planting,
sprays
are
directed
to
the
row
middles
or
orchard
floors,
and
drop
booms
and/
or
shields
are
used
to
prevent
crop
foliar
contact.
These
techniques
also
reduce
postapplication
exposures
because
they
minimize
the
amount
of
residue
on
the
crop
foliar
surfaces.
However,
broadcast
applications
may
be
made
to
grass
crops
such
cereal
grains,
rice
and
sugarcane
which
are
tolerant
of
2,4­
D.


Given
the
above
characteristics
of
2,4­
D,
it
is
anticipated
that
postapplication
exposures
would
primarily
occur
following
broadcast
treatment
of
grass
crops.
Because
2,4­
D
is
typically
applied
only
a
few
times
per
season
and
because
the
agricultural
scenarios
occur
for
only
a
few
months
per
year,
it
is
anticipated
that
2,4­
D
exposures
would
primarily
be
short­
term
and
secondarily
intermediate­
term.


Potential
inhalation
exposures
are
not
anticipated
for
the
postapplication
worker
scenarios
because
of
the
low
vapor
pressure
of
2,4­
D
(
2.0e­
07
torr
at
20o
C).


For
postapplication
occupational
exposures,
all
of
the
short­
term
MOEs
are
above
100
on
day
zero
which
indicates
that
the
risks
are
not
of
Agency
concern.
The
intermediate­
term
MOEs
are
also
all
above
100
on
day
zero
and
are
not
of
Agency
concern.

In
the
Worker
Protection
Standard
(
WPS),
a
restricted
entry
interval
(
REI)
is
defined
as
the
duration
of
time
which
must
elapse
before
residues
decline
to
a
level
such
that
entry
into
a
Page
12
of
18
previously
treated
area
and
performance
of
a
specific
task
or
activity
would
not
result
in
exposures
that
are
of
concern.


The
WPS
REI
for
2,4­
D,
based
on
acute
toxicity,
is
12
hours
for
the
ester
and
sodium
salt
forms
and
is
48
hours
for
the
acid
and
amine
salt
forms.

Ecological
Risk
To
estimate
potential
ecological
risk,
EPA
integrates
the
results
of
exposure
and
ecotoxity
using
the
risk
quotient
method.
Risk
quotients
(
RQs)
are
calculated
by
dividing
exposure
estimates
by
ecotoxity
values,
both
acute
and
chronic,
for
various
wildlife
species.
RQs
are
then
compared
to
levels
of
concern
(
LOCs)
to
assess
the
potential
for
adverse
ecological
effects.
Exceedance
of
an
LOC
indicates
potential
risk
to
nontarget
organisms
and
the
need
for
the
Agency
to
consider
mitigation
measures.
Risk
characterization
provides
further
information
on
the
likelihood
of
adverse
effects
occurring
by
considering
the
fate
of
the
chemical
in
the
environment,
communities
and
species
potentially
at
risk,
their
spatial
and
temporal
distributions,
and
the
nature
of
the
effects
observed
in
studies.
Generally,
the
higher
the
RQ
the
greater
the
potential
risk.
Reported
incidents
to
nontarget
organisms,
such
as
fish
and
birds,
involving
the
use
of
a
pesticide
can
provide
meaningful
information
to
confirm
the
results
of
risk
assessments
and
to
help
characterize
ecological
risks.

Environmental
Fate
and
Transport
(
For
a
complete
discussion,
see
the
Environmental
Fate
and
Ecological
Risk
Assessment.)

2,4­
D
acid
is
non­
persistent
to
moderately
persistent
in
aerobic,
aquatic,
and
terrestrial
environments
under
laboratory
and
field
conditions,
is
persistent
in
anaerobic
aquatic
environments,
and
is
mobile
in
soil
and
aquatic
environments.

The
Agency
proposed
an
environmental
fate
bridging
strategy
in
the
1988
Registration
Standard
for
the
amine
salts
and
esters
of
phenoxy
herbicides,
and
also
proposed
that
studies
conducted
with
the
acid
provide
"
surrogate
data"
for
2,4­
D
amine
salts
and
esters.
The
Agency
required
submission
of
data
providing
information
on
the
dissociation
time
of
2,4­
D
amine
salts
and
rate
of
hydrolysis
of
2,4­
D
esters
as
confirmatory
data
for
this
strategy.
Currently
the
Agency
has
received
bridging
data
for
2,4­
D
DMAS,
2,4­
D
IPA,
2,4­
D
TIPA,
2,4­
D
EHE,
2,4­
D
BEE,
2,4­
D
DEA,
2,4­
D
IPE
and
2,4­
D
sodium
salt.
The
bridging
data
indicate
esters
of
2,4­
D
are
rapidly
hydrolyzed
in
alkaline
aquatic
environments,
soil/
water
slurries,
and
moist
soils.
The
2,4­
D
amine
salts
have
been
shown
to
dissociate
rapidly
in
water.
However,
2,4­
D
esters
may
persist
under
extremely
dry
soil
conditions
and
sterile
acidic
aquatic
conditions.

The
weight
of
evidence
from
open­
literature
and
registrant­
sponsored
data,
reviewed
Page
13
of
18
subsequent
to
establishment
of
the
bridging
strategy,
indicates
that
2,4­
D
amine
salts
and
2,4­
D
esters
are
not
persistent
under
most
environmental
conditions
including
those
associated
with
most
sustainable
agricultural
conditions.
2,4­
D
amine
salt
dissociation
is
expected
to
be
instantaneous
(<
3
minutes)
under
most
environmental
conditions.
Although
the
available
data
on
de­
esterification
of
2,4­
D
ester
may
not
support
instantaneous
conversion
from
the
2,4­
D
ester
to
2,4­
D
acid,
it
does
show
2,4­
D
esters
in
normal
agriculture
soil
and
natural
water
conditions
are
short
lived
compounds
with
a
median
half
life
of
2.9
days.
Under
these
conditions,
the
environmental
exposure
from
2,4­
D
esters
and
2,4­
D
amine
salts
is
expected
to
be
minimal
in
both
terrestrial
and
aquatic
environments.
Further
analysis
is
required
on
reason(
s)
for
2,4­
D
BEE
persistence
in
sediments
from
aquatic
field
studies.
Additionally,
the
persistence
of
2,4­
D
EHE
on
foliage
and
in
leaf
litter
in
registrant
submitted
forest
field
dissipation
studies
requires
additional
investigation.
No
field
dissipation
data
(
terrestrial,
forest,
or
aquatic)
have
been
submitted
for
the
amine
salts,
2,4­
D
IPA,
2,4­
D
TIPA,
and
2,4­
D
DEA,
or
for
the
esters
2,4­
D
BEE
(
aquatic
field
dissipation
data
is
available
for
this
chemical
form)
and
2,4­
D
IPE
to
determine
their
persistence
under
field
conditions.

Nontarget
Terrestrial
Species
Risk
Birds

No
definitive
endpoint
was
available
from
avian
acute
dietary
studies,
so
that
risk
was
not
evaluated
using
an
acute
dietary
endpoint.
However
comparison
with
the
lowest
dietary
LC
50
of
>
5620
mg
ae/
kg­
diet
would
result
in
no
acute
level
of
concern
(
LOC)
exceedances.


For
most
small
birds
and
some
medium
birds,
when
data
from
oral
gavage
studies
were
compared
to
predicted
maximum
exposures,
there
are
exceedances
of
acute
LOCs
for
all
use
sites
except
potatoes
and
citrus

There
are
also
exceedances
of
acute
restricted
use
and
endangered
species
LOCs
for
medium
and
large
birds
feeding
on
short
grass,
tall
grass,
and
broadleaf
forage/
small
insects
at
all
use
sites
except
potatoes
and
citrus.


In
general,
when
oral
gavage
data
is
compared
with
predicted
mean
exposures,
RQs
will
be
lower,
but
will
still
result
in
multiple
restricted
use
and
endangered
species
LOC
exceedances,
and
a
few
acute
LOC
exceedances
at
the
higher
use
rate
sites
such
as
non­
cropland
and
asparagus.


For
chronic
exposure
of
birds
to
non­
granular
spray,
exceedances
of
chronic
LOCs
occurred
for
forage
on
shortgrass
for
use
of
2,4­
D
on
asparagus,
cranberries,
forestry,
and
non­
cropland.


Consideration
of
the
non­
granular
spray
average
application
rates
results
in
reduction
of
chronic
risk,
but
not
to
below
LOCs.

Mammals

Acute
LOCs
for
mammals
feeding
on
plants
and
insects
were
exceeded
for
use
of
Page
14
of
18
non­
granular
formulations
for
all
uses
assessed
for
small
and
medium
size
mammals
except
in
potatoes
and
citrus.
There
were
no
exceedances
for
granivores.


Banded
applications
result
in
exceedances
of
acute
LOCs
at
all
use
sites.


Mammalian
chronic
RQs
range
from
0.05
to
200
and
chronic
LOCs
were
exceeded
in
all
cases
with
the
exception
of
potatoes
and
citrus
(
large
insects,
seeds).


Consideration
of
average
application
rates
results
in
EECs
below
the
LOCs
for
non­
granular,
granular,
or
banded
applications.
However,
consideration
of
average
application
rates
for
non­
granular,
granular
and
banded
applications
did
not
result
in
exposure
below
the
chronic
LOC.

Plants

For
nontarget
terrestrial
plants,
the
RQs
resulting
from
granular
broadcast
applications
range
from
2.2
(
single
application)
to
266
(
multiple
applications)
for
the
acid
and
amine
salts
and
from
2.0
to
1702
for
the
esters.


According
to
the
2,4­
D
Master
Label
the
only
use
sites
which
allow
applications
of
granular
formulations
are
the
non­
crop
land
sites,
turf,
and
cranberries.


Acute
LOCs
for
both
non
endangered
and
endangered
terrestrial
plants
were
exceeded
for
non­
granular
and
granular
uses
at
many
use
sites.
Consideration
of
average
application
rates
did
not
result
in
exposure
below
LOCs.

Nontarget
Aquatic
Species
Risk
Terrestrial
applications

There
were
no
acute
or
chronic
LOC
exceedances
for
aquatic
organisms
through
use
of
2,4­
D
acid
and
amine
salts
due
to
runoff/
drift
from
use
on
terrestrial
sites.


There
were
no
acute
LOC
exceedances
for
aquatic
organisms
due
to
drift­
only
of
2,4­
D
esters
to
water
bodies
from
use
on
terrestrial
sites.


There
were
no
acute
LOC
exceedances
for
aquatic
organisms
due
to
the
runoff/
drift
of
2,4­
D
esters
to
water
bodies
from
use
on
terrestrial
sites.


For
non­
target,
aquatic
plants,
the
runoff/
drift
of
2,4­
D
acid
and
amine
salts
from
use
on
terrestrial
crops
results
in
an
exceedance
of
the
aquatic
vascular
plant
endangered
species
LOCs
for
use
of
2,4­
D
acid
and
amine
salts
on
pasture
and
apples.


Consideration
of
average
application
rates
results
in
EECs
below
the
endangered
species
LOC.


For
non­
target
aquatic
plants,
there
are
no
LOC
exceedances
for
either
the
scenario
incorporating
exposure
resulting
from
the
drift
of
the
ester
forms
to
aquatic
water
bodies
or
from
the
runoff
of
the
ester
forms
to
water
bodies
from
use
on
terrestrial
sites.
Page
15
of
18
Aquatic
weed
applications

Use
of
2,4­
D
acid
and
amine
salts
in
aquatic
weed
control
through
direct
subsurface
application
to
water
bodies
results
in
an
exceedance
of
the
restricted
use
and
endangered
species
LOCs
for
freshwater
invertebrates.
There
are
no
chronic
LOC
exceedances
for
this
use.


Use
of
2,4­
D
BEE
in
weed
control
through
direct
subsurface
application
to
water
bodies
results
in
exceedances
of
the
acute
risk
LOC
for
freshwater
fish
and
invertebrates
and
chronic
risk
LOC
for
freshwater
and
estuarine
fish
and
freshwater
invertebrates
when
compared
on
an
acid
equivalent
basis.


Additional
characterization
of
the
potential
risk
associated
with
the
direct
application
of
2,4­
D
for
aquatic
weed
control
was
completed
by
back­
calculating
the
target
concentration
needed
to
reduce
EECs
below
LOCs.
This
indicates
that
for
all
2,4­
D
chemical
forms
target
concentration
reduction
of
up
to
10­
fold
still
exceed
all
LOCs
for
aquatic
organisms.


The
scenario
of
direct
application
to
water
for
aquatic
weed
control
for
2,4­
D
acid
and
amine
salts
indicates
an
acute
and
endangered
species
LOC
exceedances
for
aquatic
vascular
and
acute
LOC
exceedances
for
non­
vascular
plants.


Use
of
2,4­
D
BEE
(
the
only
ester
registered
for
aquatic
weed
control)
for
direct
application
to
water
for
weed
control
results
in
exceedances
of
all
LOCs
for
vascular
and
an
acute
LOC
exceedance
for
non­
vascular
plants.


For
all
2,4­
D
chemical
forms,
target
concentration
reduction
of
up
to
100­
fold
still
exceed
all
LOCs
for
aquatic
plants.

Rice
paddy
application

Use
of
2,4­
D
acid
and
amine
salts
in
rice
paddies
results
in
exceedances
of
the
acute
endangered
species
LOCs
for
freshwater
invertebrates.


The
rice
model
used
to
predict
these
EECs
is
a
screening
level
model
which
predicts
concentration
in
tailwater
at
the
point
of
release
from
the
paddy.
It
is
anticipated
that
once
released,
the
concentration
will
be
reduced
and
subsequently
is
expected
to
decrease
away
from
the
point
of
release.


Consideration
of
average
application
rates
results
in
EECs
below
the
endangered
species
LOC.


Use
of
2,4­
D
acid
and
amine
salts
in
rice
paddies
result
in
exceedances
of
the
acute
and
endangered
species
LOCs
for
aquatic
vascular
plants.
Consideration
of
average
application
rates
results
in
EECs
below
the
endangered
species
LOCs.

Endangered
Species

Overall,
RQs
exceed
the
Agency's
levels
of
concern
for
endangered
and
threatened
Page
16
of
18
freshwater
fish
and
invertebrates,
estuarine
invertebrates,
birds,
mammals,
aquatic
vascular
plants,
and
terrestrial
non­
target
plants
at
many
sites.
There
are
currently
no
listed
endangered
estuarine
invertebrates
or
non­
vascular
aquatic
plants.

Summary
of
Pending
Data
The
following
data
will
be
required
as
confirmatory
information
in
the
reregistration
eligibility
decision
for
2,4­
D:

Toxicology
Data
Needs
°
Developmental
neurotoxicity
study,
a
subchronic
inhalation
toxicity
study,
and
a
repeat
2­
generation
reproduction
study
[
using
the
new
protocol]
addressing
concerns
for
endocrine
disruption
[
thyroid
and
immunotoxicity
measures]
are
recommended
to
be
conducted
on
2,4­
D.

Product
and
Residue
Chemistry
Data
Needs
°
Grape
processing,
wheat
hay
field
trials,
and
limited
irrigated
crop
studies
(
sugar
beet
roots
and
tops
and
strawberries)
are
recommended
to
support
tolerance
establishment/
reassessment
associated
with
the
use
patterns
currently
supported
by
Task
Force
II.

Environmental
Fate
Data
Needs
The
environmental
fate
database
is
essentially
complete.
However
several
studies
have
been
classified
as
supplemental.
The
following
studies
will
assist
in
fully
evaluating
the
potential
risks
associated
with
2,4­
D:

°
Additional
data
on
the
behavior
of
2,4­
D
BEE
under
acidic
to
neutral
aquatic
conditions
in
a
water/
sediment
system
will
aid
in
fully
evaluating
the
aquatic
use
of
2,4­
D
BEE.
°
A
laboratory
volatility
study
for
2,4­
D
IPE
is
necessary
to
assess
the
volatility
of
this
ester.
°
Terrestrial
field
dissipation
studies
(
164­
1)
were
required
in
1995
for
2,4­
D
IPA,
2,4­
D
TIPA,
and
2,4­
D
DEA
but
have
not
been
submitted.
These
studies
will
aid
in
fully
assessing
the
behavior
of
these
chemical
forms
under
actual
use
conditions.
°
EFED
believes
a
terrestrial
field
dissipation
study
for
2,4­
D
BEE
will
aid
in
fully
assessing
the
behavior
of
this
chemical
form
under
actual
use
conditions.
Page
17
of
18
°
2,4­
D
IPE
is
currently
registered
only
as
a
growth
inhibitor
and
therefore
EFED
does
not
believe
a
terrestrial
field
dissipation
study
is
needed
for
this
chemical
form.
°
Aquatic
field
dissipation
studies
(
164­
2)
in
a
rice
use
scenario
for
2,4­
D
IPA,
2,4­
D
TIPA,
and
2,4­
D
DEA
will
aid
in
fully
assessing
the
behavior
of
these
chemical
forms
under
actual
use
conditions.
°
Aquatic
field
dissipation
studies
(
164­
2)
in
an
aquatic
weed
control
scenario
were
required
in
1995
for
2,4­
D
IPA,
2,4­
D
TIPA,
and
2,4­
D
DEA
but
have
not
been
submitted
These
studies
will
aid
in
fully
assessing
the
behavior
of
these
chemical
forms
under
actual
use
conditions.
°
Forest
field
dissipation
studies
(
164­
3)
were
required
in
1995
for
2,4­
D
IPA,
2,4­
D
TIPA,
and
2,4­
D
DEA
but
have
not
been
submitted.
These
studies
will
aid
in
fully
assessing
the
behavior
of
these
chemical
forms
under
actual
use
conditions.
°
EFED
believes
a
forest
field
dissipation
study
for
2,4­
D
BEE
will
aid
in
fully
assessing
the
behavior
of
this
chemical
form
under
actual
use
conditions.
°
2,4­
D
IPE
is
not
used
in
forestry
applications
and
therefore
a
forest
field
dissipation
study
is
not
needed
at
this
time.

Ecological
Effects
Data
Needs
The
ecological
toxicity
data
base
is
fairly
complete
with
the
exception
of
the
terrestrial
plant
testing
on
the
typical
end­
use
product
(
TEP).
In
addition
to
plant
testing
with
TEP
the
following
studies
will
assist
in
fully
evaluating
the
potential
risks
associated
with
2,4­
D:

°
Estuarine
Fish
­
Since
environmental
fate
data
suggest
that
2,4­
D
esters
may
persist
under
certain
conditions
and
RQs
associated
with
freshwater
fish
indicate
potential
risk
to
fish
for
2,4­
D
BEE,
further
acute
testing
with
2,4­
D
BEE
will
aid
in
fully
assessing
the
toxicity
of
this
ester.
°
Estuarine/
marine
invertebrates,
acute
­
Since
environmental
fate
data
indicate
that
2,4­
D
esters
may
persist
under
certain
conditions
and
RQs
associated
with
freshwater
invertebrates
indicate
potential
risk
to
aquatic
invertebrates
for
2,4­
D
BEE,
further
acute
testing
with
2,4­
D
BEE
will
aid
in
fully
assessing
the
toxicity
of
this
ester.
°
Estuarine
and
Marine
Invertebrate,
Chronic
­
Since
freshwater
chronic
risk
quotients
are
exceeded
for
2,4­
D
BEE
(
13.05),
a
chronic
study
will
aid
in
fully
assessing
the
risks
associated
with
2,4­
D
BEE
for
marine
invertebrates.
°
Sediment
toxicity
testing
­
Due
to
the
persistence
and
high
toxicity
of
the
2,4­
D
BEE
granular
formulation
when
used
in
a
direct
application
to
water
a
sediment
toxicity
test
following
EPA
guidelines
is
requested
on
the
granular
formulation.
°
Non­
Target
Terrestrial
Plants
­
Currently,
no
studies
following
the
EPA
protocols
are
available
for
the
2,4­
D
sodium
salt,
and
some
data
is
missing
or
unavailable
for
Page
18
of
18
some
of
the
other
active
ingredients.
Current
EFED
policy
requires
testing
of
the
TEP
because
these
products
sometimes
include
surfactants
or
adjuvants
to
increase
the
absorption
to
the
foliage
and
may
increase
the
toxicity
of
the
product.
