Document ID: EPA-HQ-OPP-2004-0220-0012
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2004-08-12T04:00Z

Overview
of
2,4­
DB
Risk
Assessment
Introduction
This
document
summarizes
EPA's
human
health,
environmental
fate
and
transport,
and
ecological
risk
findings
for
the
pesticide
2,4­
DB,
as
presented
fully
in
the
documents:

"
2,4­
DB
and
2,4­
DB­
DMAS
 
Report
of
the
Hazard
Identification
Assessment
Review
Committee,"
dated
June
13,
2003

"
2,4­
DB
and
2,4­
DMA
Toxicology
Chapter
for
RED,"
dated
July
20,
2004

"
Environmental
Fate
and
Effects
Division
Preliminary
Risk
Assessment
for
2,4­
DB
and
2,4­
DB­
DMAS
Reregistration
Eligibility
Document,"
dated
July
20,
2004

"
2,4­
DB
and
2,4­
DB
Dimethylamine
Salt:
Revised
Product
Chemistry
and
Residue
Chemistry
Summary
Documents
for
the
RED,"
dated
July
19,
2004

"
2,4­
DB
Acute
and
Chronic
Dietary
Exposure
Assessments
for
the
Reregistration
Eligibility
Decision,"
dated
July
13,
2004

"
2,4­
DB:
Revised
Occupational
and
Residential
Exposure
and
Risk
Assessments
for
the
RED
Document,"
dated
July
19,
2004

"
2,4­
DB
and
2,4­
DB­
DMAS
Human
Health
Risk
Assessment,"
dated
July
19,
2004.

The
purpose
of
this
overview
is
to
help
the
reader
understand
the
conclusions
reached
in
the
risk
assessments
by
identifying
the
key
features
and
findings
of
the
assessments.
References
to
relevant
sections
in
the
complete
documents
are
provided
to
allow
the
reader
to
find
the
place
in
these
assessments
where
a
more
detailed
explanation
is
provided.

Risks
summarized
in
this
document
are
those
that
result
only
from
the
use
of
2,4­
DB.
The
Food
Quality
Protection
Act
(
FQPA)
requires
that
the
Agency
consider
available
information
concerning
the
cumulative
effects
of
a
particular
pesticide's
residues
and
other
substances
that
have
a
common
mechanism
of
toxicity.
The
reason
for
consideration
of
other
substances
is
due
to
the
possibility
that
low­
level
exposures
to
multiple
chemical
substances
that
cause
a
common
toxic
effect
by
a
common
toxic
mechanism
could
lead
to
the
same
adverse
health
effect
that
would
occur
at
a
higher
level
of
exposure
to
any
of
the
substances
individually.
Unlike
other
pesticides
for
which
EPA
has
followed
a
cumulative
risk
approach
based
on
a
common
mechanism
of
toxicity,
EPA
has
not
made
a
common
mechanism
of
toxicity
finding
for
2,4­
DB
and
any
other
substances
and
2,4­
DB
does
not
appear
to
produce
a
toxic
metabolite
produced
by
2
other
substances.
For
the
purposes
of
this
action,
therefore,
EPA
has
assumed
that
2,4­
DB
does
not
have
a
common
mechanism
of
toxicity
with
other
substances.
For
information
regarding
EPA's
efforts
to
determine
which
chemicals
have
a
common
mechanism
of
toxicity
and
to
evaluate
the
cumulative
effects
of
such
chemicals,
see
the
policy
statements
released
by
EPA's
Office
of
Pesticide
Programs
concerning
common
mechanism
determinations
and
procedures
for
cumulating
effects
from
substances
found
to
have
a
common
mechanism
on
EPA's
website
at
http://
www.
epa.
gov/
pesticides/
cumulative.

These
2,4­
DB
risk
assessments
and
additional
supporting
documents,
are
posted
on
EPA's
Internet
website
http://
docket.
epa.
gov/
edkpub/
index.
jsp
and
are
available
in
the
Pesticide
Docket
for
public
viewing.
The
Agency
has
determined
2,4­
DB
will
go
through
a
modified
4­
phase
public
participation
process
because
of
the
availability
of
highly
refined
risk
assessments.
Meetings
with
stakeholders
(
i.
e.,
growers,
extension
officials,
commodity
group
representatives
and
other
government
officials)
will
be
held
to
discuss
the
risk
assessments,
the
identified
risks
and
to
solicit
input
on
risk
mitigation
strategies,
if
needed.
This
feedback
will
be
used
to
complete
the
Reregistration
Eligibility
Decision
(
RED)
document,
which
will
include
the
resulting
risk
management
decisions.
The
Agency
plans
to
conduct
a
close­
out
conference
call
with
interested
stakeholders
to
describe
the
regulatory
decisions
presented
in
the
RED.

Use
Profile
°
Herbicide
(
systemic):
Registered
for
use
on
alfalfa,
clover,
soybean,
peanuts,
peppermint,
spearmint,
and
trefoil.
2,4­
DB
and
2,4­
DB­
DMAS
are
chlorophenoxy
herbicides
which
function
by
mimicking
the
action
of
auxins,
plant
growth
hormones.

°
Formulations:
2,4­
DB
is
manufactured
as
an
acid
and
the
dimethylamine
salt,
2,4­
DBDMAS
End­
use
products
are
formulated
either
as
soluble,
emulsifiable,
or
flowable
concentrates.

°
Methods
of
Application:
2,4­
DB
and
its
dimethylamine
salt
(
2,4­
DB­
DMAS)
can
be
applied
either
as
a
broadcast
application
early
season,
or
a
directed
spray
late
season.
Ground
or
aerial
applications
may
be
made.

°
Use
Rates:
Maximum
label
application
rates
for
food/
feed
crops
range
from
0.25
lb
ae
(
acid
equivalents)/
Acre
to
1.5
lb
ae/
Acre.

°
Annual
Poundage:
Total
annual
domestic
usage
is
approximately
375,000
pounds
active
ingredient.

°
Tolerances
in
Use
Profile:
Currently
there
are
7
listed
tolerances,
4
of
which
are
to
be
revoked.
The
Agency
is
proposing
that
a
total
of
14
tolerances
need
to
be
completed
for
3
the
risk
assessment.
(
A
table
of
tolerances
is
located
on
page
40
of
the
Product
Chemistry
Summary
Document)

°
Technical
Registrants:
Aceto
Agricultural
Chemicals
Corporation,
A.
H.
Marks
&
Company,
Limited,
Atanor
S.
A.,
Drexel
Chemical
Company,
Makhteshim­
Agan
of
North
America,
Inc.

Hazard
Characterization
(
For
a
complete
discussion,
see
section
1.0
of
the
2,4­
DB
Toxicology
Chapter
and
section
3.0
of
the
2,4­
DB
Human
Health
Risk
Assessment)

Data
show
that
2,4­
DB­
DMAS
dissociates
to
2,4­
DB
in
rats,
after
which
they
share
the
same
metabolic
pathway.
The
toxicity
and
LOAELs
of
2,4­
DB
and
2,4­
DB­
DMAS
were
similar
in
the
studies
which
were
conducted
with
both
chemicals.
For
the
above
reasons,
the
same
endpoints
were
selected
for
both
2,4­
DB
and
2,4­
DB­
DMAS
from
an
adequate
toxicity
database.
These
endpoints
are
listed
below
in
Tables
1
and
2.

Similarities
in
the
toxicity
of
2,4­
DB
and
2,4­
DMAS
include:

Forms
of
both
liver
and
kidney
toxicity
were
noted
in
subchronic
and
chronic
toxicity
studies
submitted
to
the
Agency.

Other
forms
of
toxicity
included
decreased
hematological
parameters
in
studies
conducted
with
rats
and
dogs,
and
both
developmental
and
offspring
toxicity
in
studies
with
rats.

Although
neurotoxicity
has
been
noted
in
other
phenoxy
herbicides,
clinical
signs
suggestive
of
neurotoxicity
with
2,4­
DB
and
2,4­
DB­
DMAS
only
occurred
at
lethal
doses.

EPA
is
required
under
the
Federal
Food
Drug
and
Cosmetic
Act
(
FFDCA),
as
amended
by
FQPA,
to
develop
a
screening
program
to
determine
whether
certain
substances
(
including
all
pesticide
active
and
other
ingredients)
"
may
have
an
effect
in
humans
that
is
similar
to
an
effect
produced
by
a
naturally
occurring
estrogen,
or
other
such
endocrine
effects
as
the
Administrator
may
designate.
2,4­
DB
has
properties
that
could
indicate
Endocrine
Disrupting
Chemical
(
EDC)
properties.
These
include
decreased
body
weights
and
altered
liver
function
in
mice
exposed
to
this
herbicide.
When
the
appropriate
screening
and/
or
testing
protocols
being
considered
under
the
Agency's
Endocrine
Disrupting
Screening
Program
(
EDSP)
have
been
developed,
2,4­
DB
may
be
subjected
to
additional
screening
and/
or
4
testing
to
better
characterize
effects
related
to
endocrine
disruption.

Toxicity
endpoints
and
doses
were
selected
from
rat
studies,
rather
than
dog
studies,
because
of
differences
in
the
elimination
of
phenoxyacetic
compounds
in
dogs
compared
to
other
mammalian
species.
The
dog
is
more
sensitive
to
toxicity
from
2,4­
DB
than
is
the
rat
or
human,
as
is
the
case
for
2,4­
DB.
Although
absorption
and
distribution
of
chlorophenoxy
herbicides
and
other
organic
acids
is
similar
across
all
species
evaluated,
the
half­
life
of
elimination
for
dogs
is
significantly
longer
than
for
all
other
species
considered.
Consequently,
effects
are
seen
at
lower
dose
levels
in
dog
than
in
rat.
In
the
case
of
2,4­
DB,
the
Agency
believes
it
is
appropriate
to
use
endpoints
from
the
rat
studies
to
determine
the
effects
on
humans
to
prevent
an
overemphasis
of
risk.

Differences
in
toxicity
were,
however
noted
and
include:

2,4­
DB­
DMAS
was
more
irritating
than
2,4­
DB.

Table
1.
Toxicological
Endpoints
for
2,4­
DB
(
Dietary)

Exposure
Scenario
Dose
for
Risk
Assessment
and
Uncertainty
Factor
Special
FQPA
Safety
Factor
and
Level
of
Concern
Study
and
Toxicological
Effects
Acute
Dietary
(
Females
13­
50
years
of
age)
NOAEL
=
62.5
mg/
kg/
day
UF
=
100
Acute
RfD
=
0.6
mg/
kg/
day
FQPA
SF
=
1X
aPAD
=
acute
RfD
FQPA
SF
=
0.6
mg/
kg/
day
Rat
developmental
toxicity.
LOAEL
=
125
mg/
kg/
day
based
on
skeletal
variations/
malformations,
microphthalmia,
post­
implantation
loss
Acute
Dietary
(
General
population
including
infants
and
children)
None
N/
A
No
appropriate
endpoint
attributable
to
a
single
dose
from
oral
toxicity
studies
was
identified.

Chronic
Dietary
(
All
populations)
NOAEL=
3
mg/
kg/
day
UF
=
100
Chronic
RfD
=
0.03
mg/
kg/
day
FQPA
SF
=
1X
cPAD
=
chronic
RfD
FQPA
SF
=
0.03
mg/
kg/
day
Chronic/
carcinogenicity
study
in
rats.
LOAEL
=
30
mg/
kg/
day
based
on
decreased
body
weight
gain
and
food
consumption
in
females.

UF
=
uncertainty
factor,
FQPA
SF
=
Special
FQPA
safety
factor,
NOAEL
=
no
observed
adverse
effect
level,
LOAEL
=
lowest
observed
adverse
effect
level,
PAD
=
population
adjusted
dose,
(
a
=
acute,
c
=
chronic)
RfD
=
reference
dose,
NA
=
Not
Applicable
Table
2.
Toxicological
Endpoints
for
2,4­
DB
(
Non­
dietary)
5
Exposure
Scenario
Dose
for
Risk
Assessment
and
Uncertainty
Factor
Special
FQPA
Safety
Factor
and
Level
of
Concern
Study
and
Toxicological
Effects
Short­
Term
Dermal
(
1
to
30
days)
None
N/
A
Quantization
not
required.
No
systemic
toxicity
via
the
dermal
route
and
there
are
no
developmental
concerns.

Intermediate­
Term
Dermal
(
1
to
6
months)
Oral
NOAEL
=
15.8
mg/
kg/
day
(
dermal
absorption
=
23%)
Residential
LOC
for
MOE
=
100
Occupational
=
100
Subchronic
rat
toxicity
(
2,4­
DB
study)
LOAEL
=
50
mg/
kg/
day
based
on
decreased
body
weight
gain,
increased
relative
liver/
kidney
weight,
and
microscopic
changes
Long­
Term
Dermal
(>
6
months)
Oral
NOAEL
=
3
mg/
kg/
day
(
dermal
absorption
=
23%)
Residential
LOC
for
MOE
=
100
Occupational
LOC
for
MOE
=
100
Chronic/
carcinogenicity
study
in
rats.
LOAEL
=
30
mg/
kg/
day
based
on
decreased
body
weight
gain
and
food
consumption
in
females.

Short­
Term
Inhalation
(
1
to
30
days)
Oral
NOAEL
=
31
mg/
kg/
day
(
inhalation
absorption
=
100%)
Residential
LOC
for
MOE
=
100
Occupational
LOC
for
MOE
=
100
Rat
developmental
toxicity.
LOAEL
=
62.5
mg/
kg/
day
based
on
decreased
maternal
body
weight,
body
weight
gain,
and
food
consumption,
and
clinical
signs
(
emaciation,
few
feces)

Intermediate­
Term
Inhalation
(
1
to
6
months)
Oral
NOAEL
=
15.8
mg/
kg/
day
(
inhalation
absorption
=
100%)
Residential
LOC
for
MOE
=
100
Occupational
LOC
for
MOE
=
100
Subchronic
rat
toxicity
(
2,4­
DB
study).
LOAEL
=
50
mg/
kg/
day
based
on
decreased
body
weight
gain,
increased
relative
liver/
kidney
weight,
and
microscopic
changes
Long­
Term
Inhalation
(>
6
months)
Oral
NOAEL
=
3
mg/
kg/
day
(
inhalation
absorption
=
100%)
Residential
LOC
for
MOE
=
100
Occupational
LOC
for
MOE
=
100
Chronic/
carcinogenicity
study
in
rats.
LOAEL
=
30
mg/
kg/
day
based
on
decreased
body
weight
gain
and
food
consumption
in
females.

Cancer
None
N/
A
Classified
"
not
likely
to
be
a
human
carcinogen".

UF
=
uncertainty
factor,
FQPA
SF
=
Special
FQPA
safety
factor,
NOAEL
=
no
observed
adverse
effect
level,
LOAEL
=
lowest
observed
adverse
effect
level,
PAD
=
population
adjusted
dose,
(
a
=
acute,
c
=
chronic)
RfD
=
reference
dose,
MOE
=
margin
of
exposure,
LOC
=
level
of
concern,
NA
=
Not
Applicable
6
Human
Health
Risk
Assessment
Dietary
Risk
(
Food)

(
For
a
complete
discussion,
see
the
Acute
and
Chronic
Dietary
Exposure
Assessment
for
2,4­
DB)

Dietary
risk
assessment
incorporates
both
exposure
to
and
toxicity
of
a
given
pesticide.
The
risk
is
expressed
as
a
percentage
of
a
maximum
acceptable
dose
(
i.
e.,
the
dose
which
will
result
in
no
unreasonable
adverse
health
effects).
This
dose
is
referred
to
as
the
population
adjusted
dose
(
PAD).
The
PAD
is
equivalent
to
the
Reference
Dose
(
RfD)
divided
by
the
special
FQPA
Safety
Factor.
EPA
is
concerned
when
estimated
dietary
risk
exceeds
100%
of
the
PAD.

The
magnitude
of
the
residue
data
for
processed
commodities
of
food/
feed
crops
that
are
from
presently
registered
use
sites
have
been
evaluated
and
deemed
adequate
by
the
Agency.
Based
on
the
submitted
studies,
a
processing
factor
of
0.72x
was
used
for
peanut
oil
in
the
dietary
assessment
and
1x
processing
factor
was
used
for
mint
oil
and
soybean
oil.

2,4­
DB
acute
and
chronic
dietary
exposure
assessments
were
conducted
using
the
Dietary
Exposure
Evaluation
Model
software
with
the
Food
Commodity
Intake
Database
(
DEEMFCIDTM
Version
1.30),
which
incorporates
consumption
data
from
USDA's
Continuing
Surveys
of
Food
Intakes
by
Individuals
(
CSFII),
1994­
1996
and
1998.

Acute
and
chronic
dietary
exposure
estimates
were
also
conducted
using
the
LifelineTM
model
(
Version
2.0).
These
LifelineTM
assessments
were
conducted
using
the
same
consumption
data
as
the
DEEM­
FCIDTM.

For
acute
exposure
estimates,
individual
one­
day
food
consumption
data
are
used
on
an
individual­
by­
individual
basis.
The
reported
consumption
amounts
of
each
food
item
can
be
multiplied
by
a
residue
point
estimate
and
summed
to
obtain
a
total
daily
pesticide
exposure
for
a
deterministic
exposure
assessment.
The
resulting
distribution
of
exposures
is
expressed
as
risk
as
a
percentage
of
the
acute
PAD
(
aPAD).

For
chronic
dietary
exposure
assessment,
an
estimate
of
the
residue
level
in
each
food
or
food­
form
on
the
food
commodity
residue
list
is
multiplied
by
the
average
daily
consumption
estimate
for
that
food/
food
form.
The
resulting
residue
consumption
estimate
is
summed
with
the
residue
consumption
estimates
for
all
other
food/
food
forms
on
the
commodity
residue
list
to
arrive
at
the
total
average
estimated
exposure.
Exposure
is
expressed
in
mg/
kg
body
weight/
day
and
risk
is
expressed
as
a
percent
of
the
chronic
PAD
(
cPAD).

An
unrefined
dietary
risk
assessment
(
which
assumed
tolerance
level
residues
and
100%
crop
treated)
was
conducted
for
all
supported
2,4­
DB
food
uses
for
both
acute
and
chronic
dietary
risk
as
a
screen
to
determine
if
more
refined
analyses
were
needed.
7
Acute
Dietary
Risk
(
Food)

Acute
dietary
risk
estimates
are
provided
for
females
13­
49
years
old,
the
only
population
subgroup
of
concern.
The
results
using
the
DEEM­
FCID
and
Lifeline
models
based
on
conservative
residue
estimates
which
showed
risk
estimates
at
the
95th
percentile
of
exposure
to
be
<
1%
of
the
aPAD
regardless
of
the
model
used
and
were
therefore
not
of
concern.
Based
on
the
results
of
the
assessment,
further
refinements
are
not
warranted.

Table
3.
Acute
Dietary
Exposure
and
Risk
Population
Subgroup
Acute
Dietary
(
95th
Percentile)

DEEM­
FCID
Lifeline
Dietary
Exposure
(
mg/
kg/
day)
%
aPAD
Dietary
Exposure
(
mg/
kg/
day)
%
aPAD
Females
13­
49
years
old
0.000467
0.08
0.000614
0.102
Chronic
Dietary
Risk
(
Food)

The
chronic
risk
estimates
presented
in
Table
4
are
below
the
Agency's
level
of
concern
for
the
general
U.
S.
population
(<
1%
of
the
cPAD)
and
all
the
population
subgroups
(

2.2%
cPAD).
The
most
highly
exposed
population
subgroup
was
all
infants
(<
1
years
old).

This
assessment
was
based
on
conservative
residue
estimates.
Based
on
the
results
of
the
assessment,
further
refinements
are
not
warranted.
8
Table
4.
Chronic
Dietary
Exposure
and
Risk
Population
Subgroup*
Chronic
Dietary
DEEM­
FCID
Lifeline
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD
General
U.
S.
Population
0.000242
0.8
0.000232
0.8
All
Infants
(<
1
year
old)
0.000661
2.2
0.000554
1.8
Children
1­
2
years
old
0.000548
1.8
0.000539
1.8
Children
3­
5
years
old
0.000535
1.8
0.000505
1.7
Children
6­
12
years
old
0.000373
1.2
0.000346
1.2
Youth
13­
19
years
old
0.000238
0.8
0.000224
0.7
Adults
20­
49
years
old
0.000197
0.7
0.000198
0.7
Adults
50+
years
old
0.000153
0.5
0.000191
0.6
Females
13­
49
years
old
0.000185
0.6
0.000228
0.8
*
*
The
values
for
the
highest
exposed
population
for
each
type
of
risk
assessment
are
bolded.

Drinking
Water
Dietary
Risk
(
For
a
complete
discussion,
see
section
4.3
of
the
2,4­
DB
Human
Health
Risk
Assessment)

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
of
treated
water
allowed
in
the
diet,
EPA
first
looks
at
how
much
of
the
overall
allowable
risk
is
contributed
by
food,
then
calculates
a
"
drinking
water
level
of
comparison"
(
DWLOC)
to
determine
whether
modeled
or
monitoring
levels
exceed
this
level.

The
Agency
uses
a
DWLOC
as
a
surrogate
to
capture
risk
associated
with
exposure
from
pesticides
in
drinking
water.
The
DWLOCs
represent
the
maximum
contribution
to
the
human
diet
(
in
ppb
or
µ
g/
L)
that
may
be
attributed
to
residues
of
a
pesticide
in
drinking
water
after
food
9
exposure
is
subtracted
from
the
aPAD
or
cPAD.
Risks
from
drinking
water
are
assessed
by
comparing
the
DWLOCs
to
the
estimated
environmental
concentrations
(
EECs)
in
surface
water
and
groundwater.
Drinking
water
modeling
provides
high­
end
to
bounding
estimates
of
pesticide
concentrations
in
groundwater
and
surface
water
used
as
drinking
water
prior
to
treatment.

The
mobility
of
2,4­
DB
in
mineral
soils
was
classified
as
very
mobile
to
moderately
mobile.
The
half­
life
of
2,4­
DB
in
terrestrial
field
dissipation
studies
was
2
to
6.7
days.
The
primary
route
of
dissipation
was
by
transformation,
major
transformation
products
being
2,4­
dichlorophenoxyacetic
acid
(
2,4­
D
acid,
5.0­
15%
of
the
applied)
and
2,4­
D
Phenol
(
5.0­
27.3%
of
the
applied).
2,4­
D
acid
was
identified
as
the
major
degradate
degradate
in
the
aerobic
and
anaerobic
soil
metabolism
studies.

There
were
monitoring
data
for
2,4­
DB
from
the
United
States
Geological
Survey
(
USGS)
and
the
USEPA.
Frequency
of
detections
were
not
sufficient
to
calculate
time
weighted
means.

Modeling
of
surface
water
concentrations
of
2,4­
DB
was
performed
using
the
PRZM/
EXAMS
model,
using
alfalfa,
peanuts,
and
soybean
applications.
Estimated
concentrations
of
2,4­
DB
in
surface
drinking
water
were
the
highest
from
the
Texas
alfalfa
scenario
as
follows:
318.68

g
ae/
L
for
the
1
in
10
year
peak
(
acute)
72.40

g
ae/
L
for
the
1
in
10
year
annual
daily
average
concentration
(
chronicnon
cancer)
39.85

g
ae/
L
for
the
36­
year
annual
daily
average
concentration
(
chronic­
cancer)

No
degradation
products
of
2,4­
DB
were
included
in
this
assessment.
The
major
degradate
of
2,4­
DB
is
2,4­
D.
According
to
data
from
the
US
Geographical
Survey
reported
in
the
EFED
water
memo,
2,4­
D
is
used
in
virtually
the
entire
country,
whereas
2,4­
DB
use
is
in
discrete
areas
of
the
country,
which
overlap
areas
of
2,4­
D
use.
Since
2,4­
DB
accounts
for
a
small
percentage
of
2,4­
D
water
exposure,
both
in
terms
of
usage
and
environmental
transformation,
water
exposure
to
2,4­
D
will
be
addressed
in
the
2,4­
D
RED.

The
SCI­
GROW
model
estimated
the
concentration
of
2,4­
DB
in
drinking
water
from
shallow
ground
water
sources
to
be
0.51

g
ae/
L.
This
concentration
can
be
used
for
both
acute
and
chronic
exposure
Residential
Risk
There
are
no
residential
uses
for
2,4­
DB.
10
Aggregate
Risk
(
For
a
complete
discussion,
see
section
4.5
of
the
Human
Health
Risk
Assessment)

Aggregate
exposure
to
a
pesticide
combines
exposure
from
food,
drinking
water,
and
residential
sources
of
exposure.
Since
there
are
no
residential
uses
for
2,4­
DB,
aggregate
assessments
included
exposure
via
food
and
drinking
water.

Drinking
water
levels
of
comparison
(
DWLOCs)
were
calculated
for
acute
and
chronic
exposures.
The
DWLOC
is
the
maximum
potential
concentration
that
may
be
present
in
drinking
water
without
exceeding
the
level
of
concern
when
exposure
from
food
and
water
were
considered
together.

An
acute
DWLOC
was
calculated
only
for
females
13­
49
years
of
age
because
this
was
the
only
population
subgroup
for
which
an
endpoint
was
selected.
The
concentration
of
2,4­
DB
estimated
in
water
was
less
than
the
DWLOC;
and
therefore
EPA
has
no
concern
for
acute
aggregate
exposure.

Table
5.
DWLOCs
for
Acute
Exposure
to
2,4­
DB
Population
Subgroup
Acute
PAD
mg/
kg/
day
Food
Exposure
mg/
kg/
day
Target
Max
Water
Exposure
mg/
kg/
day
Ground
Water
EEC

g/
L
Surface
Water
EEC

g/
L
DWLOC

g/
L
Females
13­
49
years
0.6
mg/
kg
0.000467
0.600
0.51
318.68
18,000

For
chronic
aggregate
risk,
most
highly
exposed
population
subgroup
was
all
infants
<
1
year
old.
The
concentration
of
2,4­
DB
estimated
in
water
was
less
than
the
DWLOC;
and
therefore
EPA
has
no
concern
for
chronic
aggregate
exposure.

Table
6.
DWLOCs
for
Chronic
Exposure
Population
Subgroup
Chronic
PAD
mg/
kg/
day
Food
Exposure
mg/
kg/
day
Target
Max
Water
Exposure
mg/
kg/
day
Ground
Water
EEC

g/
L
Surface
Water
EEC

g/
L
DWLOC

g/
L
U.
S.
Population
(
total)
0.03
0.000242
0.030
0.51
72.40
1050
All
infants
(<
1
year)
0.03
0.000661
0.029
0.51
72.40
290
11
Occupational
Risk
(
For
a
complete
discussion,
see
section
4.6
of
the
2,4­
DB
Human
Health
Risk
Assessment)

People
can
be
exposed
to
a
pesticide
while
working
through
handling,
mixing,
loading,
or
applying
a
pesticide,
and
reentering
a
treated
site.
Handler
and
worker
risks
are
measured
by
a
Margin
of
Exposure
(
MOE)
which
determines
how
close
the
occupational
exposure
comes
to
a
No
Observed
Adverse
Effect
Level
(
NOAEL)
taken
from
animal
studies.
Generally,
MOEs
greater
than
100
do
not
exceed
the
Agency's
level
of
concern.
For
workers
entering
a
treated
site,
Restricted
Entry
Intervals
(
REIs)
are
calculated
to
determine
the
minimum
length
of
time
required
until
MOEs
exceed
100
and
workers
can
safely
re­
enter.

Occupational
Handler
Summary

Exposure
analyses
were
performed
using
the
Pesticide
Handlers
Exposure
Database
(
PHED).

The
target
Margin
of
Exposure
(
MOE)
for
occupational
populations
is
100,
which
includes
the
standard
safety
factors
of
10X
for
intraspecies
variability
(
i.
e.
differences
among
humans)
and
10X
for
interspecies
variability
(
differences
between
humans
and
animals)

The
MOEs
for
occupational
exposures
were
calculated
for
short­
term
inhalation
exposure
and
for
intermediate­
term
combined
dermal
and
inhalation
exposures
and
are
summarized
in
Tables
7
and
8.
All
of
the
short­
term
inhalation
MOEs
exceed
100
at
baseline
and
respiratory
protection
is
not
needed.
All
of
the
intermediate­
term
mixer/
loader
combined
MOEs
exceed
100
if
single
layer
PPE
(
i.
e.
baseline
clothing
and
chemical
resistant
gloves)
is
worn.
The
intermediate­
term
MOEs
for
applicators
exceed
100
with
baseline
PPE.
12
Table
7.
2,4­
DB
Short­
Term
MOEs
for
Handlers
Exposure
Scenario
Crop
Label
Application
Rate
(
lb
ae/
acre)
Acres/
Day
Baseline
Inhalation
MOE
Mix/
Load
Liquids
for
Aerial
Alfalfa,
Clover
Mint
Peanuts
(
SW),
Soybeans
Peanuts
(
SE)
1.5
0.75
0.4
0.25
1200
1200
1200
1200
1,000
2,000
3,800
6,000
Mix/
Load
Liquids
for
Groundboom
Alfalfa,
Clover,
CRPA
Mint
Peanuts
(
SW),
Soybeans
Peanuts
(
SE)
1.5
0.75
0.4
0.25
200
200
200
200
6,000
12,000
23,000
36,000
Aerial
Application
Alfalfa,
Clover
Mint
Peanuts
(
SW),
Soybeans
Peanuts
(
SE)
1.5
0.75
0.4
0.25
1200
1200
1200
1200
18,000
35,000
66,000
110,000
Groundboom
Application
Alfalfa,
Clover,
CRPA
Mint
Peanuts
(
SW),
Soybeans
Peanuts
(
SE)
1.5
0.75
0.4
0.25
200
200
200
200
9,800
20,000
37,000
59,000
Flag
Aerial
Application
Alfalfa,
Clover
Mint
Peanuts
(
SW),
Soybeans
Peanuts
(
SE)
1.5
0.75
0.4
0.25
1200
1200
1200
1200
3,400
6,900
13,000
21,000
13
Table
8.
2,4­
DB
Intermediate­
Term
MOEs
for
Handlers
Exposure
Scenario
Crop
Average
Application
Rate
(
lb
ae/
acre)
Acres/
Day
Baseline
Combined
Dermal/
Inhal
ation
MOE
Single
Layer
Combined
MOE
Mix/
Load
Liquids
for
Aerial
Alfalfa,
Clover
Mint
Peanuts
Soybeans
0.55
0.75
0.24
0.13
1200
1200
1200
1200
2.5
1.8
5.7
11
260
190
590
1100
Mix/
Load
Liquids
for
Groundboom
Alfalfa,
Clover
Mint
Peanuts
Soybeans
0.55
0.75
0.24
0.13
200
200
200
200
15
11
34
64
1500
1100
3600
6600
Aerial
Application
Alfalfa,
Clover
Mint
Peanuts
Soybeans
0.55
0.75
0.24
0.13
1200
1200
1200
1200
1400
1000
3200
5800
NA
NA
NA
NA
Groundboom
Application
Alfalfa,
Clover
Mint
Peanuts
Soybeans
0.55
0.75
0.24
0.13
200
200
200
200
2500
1900
5800
11000
2500
1900
5800
11000
Flag
Aerial
Application
Alfalfa,
Clover
Mint
Peanuts
Soybeans
0.55
0.75
0.24
0.13
1200
1200
1200
1200
580
430
1300
2500
540
400
1200
2300

Intermediate­
term
handler
exposures
are
less
likely
to
occur
because
2,4­
DB
is
applied
only
once
or
twice
per
season.
Metabolism
studies
in
rats
also
indicated
that
most
of
the
2,4­
DB
dose
is
excreted
within
24
hours
through
the
urine
and
feces.

The
amine
salt
form
of
2,4­
DB
is
a
severe
eye
irritant
and
eye
protection
is
recommended.

Post­
Application
Occupational
Risk
Post­
application
2,4­
DB
exposures
can
occur
in
the
agricultural
environment
when
workers
enter
fields
recently
treated
with
2,4­
DB
to
conduct
tasks
such
as
scouting
and
irrigation.
Post­
application
exposure
to
re­
entry
workers
is
possible
because
2,4­
DB
can
be
broadcast
applied.

Because
2,4­
DB
is
typically
applied
once
or
twice
per
season
it
is
anticipated
that
2,4­
Db
exposure
will
be
primarily
short­
term.
Because
there
is
no
endpoint
for
short­
term
dermal
exposures,
short­
term
post­
application
risks
were
not
assessed.
14

There
were
no
chemical
specific
worker
exposure
data
submitted
for
2,4­
DB,
therefore,
standard
values
and
assumptions
were
used
as
discussed
below.
The
following
assumptions
were
made
regarding
occupational
post­
application:

The
average
application
rates
were
used
because
it
is
highly
unlikely
workers
would
be
exposed
to
residues
shortly
after
application
for
more
that
thirty
consecutive
days.

The
risks
for
alfalfa,
peanuts
and
soybeans
were
assessed
using
average
rates
as
reported
in
the
QUA
report.
The
risks
for
mint
were
assessed
at
the
maximum
label
rate
of
0.75
lb
ai/
acre
which
is
slightly
less
than
the
rate
of
0.8
lb
ai/
acre
reported
in
the
QUA
report.

The
initial
percent
of
application
rate
as
Dislodgeable
Foliar
Residue
(
DFR)
was
assumed
to
be
20%
for
all
crops.

The
post
application
risk
estimates
are
highly
conservative
because
they
are
based
upon
an
intermediate­
term
endpoint.
Intermediate­
term
exposures
are
unlikely
to
occur
because
2,4­
DB
is
applied
only
once
or
twice
per
season.
Turf
Transferable
residue
data
for
the
other
phenoxy
herbicides
such
as
2,4­
D
and
MCPA
have
indicated
that
the
dissipation
is
fairly
rapid.

Table
9.
2,4­
DB
Post­
Application
Worker
Risks
Crop
Transfer
Coefficient
Group
Application
Rate
(
lb
a.
i./
acre)
Intermediate­
term
MOE
on
Day
0
Low
Exposure
Scenarios*
Medium
Exposure
Scenarios*
High
Exposure
Scenarios*

Alfalfa
Field/
row
crop,
low/
medium
0.55
4900
325
NA
Mint
Field/
row
crop,
low/
medium
0.75
3600
240
NA
Peanuts
Field/
row
crop,
low/
medium
0.24
11000
740
NA
Soybeans
Field/
row
crop,
low/
medium
0.13
22000
1500
NA
*
Task
descriptions
for
each
crop
and
exposure
scenario
are
included
in
Table
10
of
the
Occupational
and
Residential
Risk
Assessment
15
Ecological
Risk
Environmental
Fate
and
Transport
Although
this
action
is
for
reregistration
of
the
active
ingredients
2,4­
DB
and
2,4­
DBDMAS
risks
were
assessed
only
for
2,4­
DB
since
2,4­
DB­
DMAS
is
highly
unstable
in
moist
soils
and
aquatic
environments.
Consequently,
application
rates
are
expressed
in
pounds
of
acid
equivalents
(
ae)
rather
than
pounds
of
active
ingredients
(
ai)
per
acre.
Bridging
data
were
submitted
by
the
registrant
demonstrating
that
2,4­
DB­
DMAS,
a
salt,
rapidly
dissociates
when
exposed
to
moisture
to
form
2,4­
DB
and
dimethylamine.
It
is
very
important
to
note,
however,
that
2,4­
DB­
DMAS
could
persist
under
dry
soil
conditions.

The
dissipation
of
2,4­
DB
in
soil
environments
appears
to
be
dependent
on
leaching
and
on
oxidative
microbial­
mediated
degradation.
Photodegradation
appears
to
be
the
main
path
of
dissipation
of
2,4­
DB
in
aquatic
environments.
The
mobility
of
2,4­
DB
was
classified
as
very
mobile
to
moderately
mobile.

The
major
degradate
of
2,4­
DB,
2,4­
D,
has
been
shown
to
be
non­
persistent
and
mobile
in
aerobic
terrestrial
and
aquatic
environments.
Under
anaerobic
conditions,
however,
2,4­
D
is
more
persistent.
The
dissipation
of
2,4­
D
appears
to
be
dependent
on
oxidative
microbial­
mediated
mineralization,
photodegradation
in
water,
and
leaching.

To
estimate
potential
ecological
risk,
EPA
integrates
the
results
of
exposure
and
ecotoxicity
studies
using
the
quotient
method.
Risk
quotients
(
RQs)
are
calculated
by
dividing
exposure
estimates
by
ecotoxicity
values,
both
acute
and
chronic,
for
various
wildlife
species.
RQs
are
then
compared
to
levels
of
concern
(
LOCs).
Generally,
the
higher
the
RQ,
the
greater
the
potential
risk.
Risk
characterization
provides
further
information
on
the
likelihood
of
adverse
effect
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.

Terrestrial
Organism
Risk

The
greatest
potential
for
risks
is
to
terrestrial
non­
targeted
plants
from
2,4­
DB
spray
drift
and
runoff
to
areas
adjacent
to
or
near
treated
fields.
Spray
drift
may
potentially
damage
plants
through
direct
contact
or
through
soil
deposition
during
seedling
emergence.
Potential
effects
on
non­
target
terrestrial
plants
are
most
likely
to
occur
as
a
result
of
spray
drift
from
aerial
and
ground
applications
of
the
liquid
formulation.

The
non­
targeted
terrestrial
plant
LOCs
for
acute
risks
and
endangered
species
have
been
exceeded
using
the
highest
application
rate
for
alfalfa
(
for
aerially/
ground
applied
at
a
rate
of
1.7
lbs
ae/
A,
2
times
per
year
with
a
30
day
interval).
The
LOCs
for
acute
endangered
and
non­
endangered
terrestrial
plants
were
exceeded
in
the
following
categories:
16
Table
10.
Summarized
Terrestrial
Plant
Risk
Quotients
for
Technical
2,4­
DB
based
on
seedling
emergence
for
dicots
(
carrots)
at
an
application
rate
of
1.7lbs
ae/
acre
to
alfalfa
Scenario
Acute­
Endangered
RQs
Acute
Non­
endangered
RQs
adjacent
to
treated
sites
semi­
aquatic
areas
adjacent
to
treated
sites
semi­
aquatic
areas
Ground
application
Dicot
113.33
793.33
8.64
60.51
Aerial
application
Dicot
234.22
642.22
17.86
48.98
Table
11.
Summarized
Terrestrial
Plant
Risk
Quotients
for
Technical
2,4­
DB
based
on
vegetative
vigor
for
monocots
(
onions)
for
an
application
rate
of
1.7lbs
ae/
acre
to
alfalfa
Scenario
Acute­
Endangered
RQs
Acute
Non­
endangered
RQs
Ground
application
Monocot
1.42
0.21
Aerial
application
Monocot
7.08
1.05

Acute
terrestrial
plant
LOCs
are
exceeded
for
the
following
categories
when
average
application
rates
are
used
for
alfalfa,
exceedances
for
all
other
crop
uses
were
lower:

Table
12.
Summarized
Terrestrial
Plant
Risk
Quotients
for
Technical
2,4­
DB
based
on
seedling
emergence
for
dicots
(
carrots)
at
an
application
rate
of
0.55
lbs
ae/
acre
to
alfalfa
Scenario
Acute­
Endangered
RQs
Acute
Non­
endangered
RQs
adjacent
to
treated
sites
semi­
aquatic
areas
adjacent
to
treated
sites
semi­
aquatic
areas
Ground
application
Dicot
36.67
256.67
2.80
19.58
Aerial
application
Dicot
75.78
207.78
5.78
5.85
Table
13.
Summarized
Terrestrial
Plant
Risk
Quotients
for
Technical
2,4­
DB
based
on
vegetative
vigor
for
17
monocots
(
onions)
for
an
application
rate
of
0.55lbs
ae/
acre
to
alfalfa
Scenario
Acute­
Endangered
RQs
Acute
Non­
endangered
RQs
Ground
application
Monocot
0.46
0.07
Aerial
application
Monocot
2.29
0.34

Acute
avian
LOCs
were
exceeded
for
small
birds
feeding
exclusively
on
short
grass
and
endangered
species
LOCs
were
exceeded
for
small
and
medium
birds
feeding
on
short
grass,
tall
grass,
and
broadleaf
plants/
insects.
Based
on
the
acute
toxicity
studies
submitted
for
birds,
there
is
a
large
differential
between
the
acute
toxicity
studies
administered
as
a
single
gavage
dose
or
when
mixed
in
the
feed.
This
disparity
in
mortality
between
the
two
types
of
studies
suggests
that
the
dietary
matrix
may
have
a
lowering
effect
of
the
toxicity
of
2,4­
DB.

Quantitative
chronic
risks
to
birds
were
not
assessed
due
to
a
lack
of
avian
reproduction
data.

Predicted
residues
from
the
application
of
2,4­
DB
from
all
uses
do
not
result
in
exceedances
of
the
acute
LOC
for
mammals.
Exceedances
of
the
restricted
use
and
endangered
species
LOCs
for
small
and
medium
size
mammals
do
occur
for
certain
food
items
when
using
the
alfalfa
application
scenario.
When
using
the
soybean
and
peanut
application
scenario,
endangered
species
LOCs
are
exceeded
for
small
mammals
feeding
exclusively
on
short
grass.
Complete
tables
listing
LOC
exceedances
are
located
in
Appendix
D,
Tables
5
to
16
of
the
Environmental
Fate
and
Effects
Division
Preliminary
Risk
Assessment.

Chronic
mammalian
LOCs
are
exceeded
for
the
maximum
residues
and
two
applications
for
small
mammals
feeding
on
short
grass,
tall
grass
and
broadleaf
plants
and
insects,
and
medium­
size
mammals
feeding
on
short
grass.
For
a
single
application
at
the
same
rate
and
the
maximum
residues,
the
chronic
LOC
for
small
mammals
feeding
on
short
grass
is
exceeded.
At
one
or
two
applications
and
using
the
mean
residue
values,
acute
endangered
species
LOCs
are
exceeded
for
two
applications
of
2,4­
DB
to
alfalfa
for
small
and
medium
size
mammals
feeding
on
short
grass.

When
assessing
the
potential
chronic
risks
from
the
average
application
rates
of
2,4­
DB,
no
mammalian
chronic
levels
of
concern
are
expected
to
be
exceeded
for
any
of
the
crop
scenarios
modeled
in
this
risk
assessment
based
on
linear
extrapolation.

The
screening­
level
risk
assessment
relies
on
labeled
maximum
application
rates
to
calculate
wildlife
dietary
exposures.
When
using
average
labeled
application
rates
aerially
18
applied
at
one
and
two
applications
(
from
BEAD's
Quantitative
Analysis
Report)
to
any
of
the
crop
scenarios
modeled,
acute
levels
of
concern
would
not
likely
be
exceeded
for
mammals.
When
assessing
the
potential
chronic
risks
from
average
application
rates
of
2,4­
DB,
no
mammalian
chronic
levels
of
concern
are
expected
to
be
exceeded
for
any
of
the
crop
scenarios
modeled
in
the
risk
assessment.

Since
2,4­
DB
was
practically
non­
toxic
to
honey
bees,
the
potential
for
2,4­
DB
to
have
adverse
effects
on
pollinators
and
other
beneficial
insects
is
low.

Aquatic
Organism
Risk

Although
2,4­
DB
is
classified
as
practically
non­
toxic
to
slightly
toxic
to
freshwater
fish,
simulations
of
alfalfa
scenarios
indicate
an
exceedances
of
the
acute
endangered
freshwater
fish
species
LOC
based
on
the
1
in
10
year
peak
estimated
by
modeling.
This
exceedance
is
likely
caused
by
the
high
runoff
vulnerability
of
the
alfalfa
scenario
coupled
with
the
highest
use
rate.
Factors
contributing
to
runoff
vulnerability
can
be
attributed
to
the
pesticide
fate
properties,
soil
type,
site
location,
and
rainfall
patterns
and
amounts
relative
to
pesticide
application.

Freshwater
invertebrates
are
not
expected
to
be
at
risk
for
application
scenarios
examined
in
the
risk
assessment.

2,4­
DB
rapidly
degrades
to
2,4­
D
in
aquatic
environments,
and
is
characterized
as
slightly
toxic
to
freshwater
fish.
The
potential
for
risks
from
2,4­
DB's
degradation
to
2,4­
D
in
the
environment
is
summarized
and
addressed
in
2,4­
D's
Registration
Eligibility
Decision
Science
Chapter:
Endangered
Species
Assessment.

Risk
to
Endangered
Species
The
preliminary
risk
assessment
for
endangered
species
indicates
that
2,4­
DB
exceeds
the
endangered
species
LOCs
for
the
following
scenarios:

(
For
a
complete
discussion
of
LOC
exceedances
refer
to
the
Environmental
Fate
and
Effects
Division
revised
risk
assessment)

Freshwater
fish
Levels
of
Concern
using
the
Texas
Alfalfa
scenario
were
exceeded
in
aquatic
environments
through
drift
and
runoff.

Small
mammals
feeding
on
short
grass,
tall
grass,
and
broadleaf
plants/
insects
when
single
or
multiple
aerial
applications
are
made
to
alfalfa.

Medium­
size
mammals
feeding
on
short
grass,
tall
grass
and
broadleaf
plants/
insects
when
multiple
aerial
applications
are
made
to
alfalfa
and
short
grass
and
broadleaf
plants/
insects
when
a
single
application
is
made
to
alfalfa.
19

Small
and
medium
size
birds
feeding
on
short
grass,
tall
grass,
and
broadleaf
plants/
insects
when
multiple
aerial
applications
are
made
to
alfalfa.

Non­
target
terrestrial
plants
at
the
highest
application
rate.

There
are
a
number
of
areas
of
uncertainty
in
the
terrestrial
and
aquatic
organism
risk
assessments
that
could
potentially
lead
to
an
over
or
under
estimate
of
risk.
For
a
complete
discussion
refer
to
Section
V
of
the
Environmental
Fate
and
Effects
Division
Preliminary
Risk
Assessment.

Data
Requirements
Toxicology
Data
Gap:
A
28­
day
inhalation
study
is
required
because
the
use
pattern
indicates
potential
repeated
exposure
via
this
route.
This
study
should
be
conducted
with
2,4­
DB­
DMAS
because
of
the
irritancy
from
this
compound.

Residue
Chemistry
Deficiencies:
Labels
that
only
prohibit
the
grazing
of
forage
or
feeding
of
hay
within
60
days
of
the
application
of
a
tank
mix
with
Lorax
50W
application
should
be
against
feeding/
grazing
soybean
forage
and
harvesting
hay
for
60
days
following
any
2,4­
DB
application.

The
submitted
plant
analytical
methods
are
adequate
for
data
collection
but
must
be
adequately
validated
for
each
study
for
which
it
was
used.
If
any
of
the
submitted
analytical
methods
for
plant
commodities
are
proposed
as
a
2,4­
DB
tolerance
enforcement
method
then
the
method
should
be
modified
determination
of
free
and
conjugated
2,4­
DB.
An
ILV
should
be
performed.

The
submitted
methods
for
livestock
commodities
are
adequate
for
data
collection.
If
the
submitted
method
is
proposed
as
the
enforcement
method
for
determining
2,4­
DB
in
livestock
commodities
then
an
ILV
of
the
method
should
be
performed.

Additional
field
trials
on
clover
forage
and
hay
are
required
at
the
maximum
label
rate
(
1.3
lb
ae/
A)
with
a
60­
day
PHI
to
reassess
the
2,4­
DB
tolerances.
Ten
additional
trials
are
recommended
in
the
following
regions:
1
(
Region
1),
1
(
Region
2),
1
(
Region
4),
3
(
Region
5),
1
(
Region
6),
1
(
Region
7),
1
(
Region
8),
1
(
Region
9).

Analytical
reference
standards
must
be
supplied
as
requested
by
the
EPA
National
Pesticide
Standards
Repository
for
2,4­
DB.

Product
Chemistry
Deficiencies:
There
are
a
number
of
product
chemistry
deficiencies
for
various
registrants.
Registrants
should
also
submit
required
data
for
dibenzo­
p­
dioxins
and
dibenzofurans,
and
either
certify
that
the
suppliers
of
beginning
materials
and
the
manufacturing
process
for
the
2,4­
DB
products
have
not
20
changed
since
the
last
comprehensive
product
chemistry
review
or
submit
a
complete
updated
product
chemistry
data
package.

Environmental
Fate
Data:

Bioconcentration
in
Fish
Study

Laboratory
Volatility
Study

Droplet
Size
Spectrum
Study

Drift
Field
Evaluation
Ecological
Effects:

The
ecotoxicity
database
does
not
contain
all
the
studies
needed
to
perform
a
complete
risk
assessment.
The
following
studies
are
requested:

Seedling
Emergence:
EFED
is
requesting
the
entire
seedling
emergence
and
vegetative
vigor
toxicity
studies
be
conducted
using
the
TEP,
in
accordance
with
current
policy.
Toxicity
tests
conducted
with
the
TEP
would
allow
for
the
development
of
a
more
appropriate
description
of
the
actual
risk
to
non­
target
terrestrial
plants.

Aquatic
Plant
Toxicity
Test
using
2,4­
DB­
DMAS/
2,4­
DB
(
preferably
using
the
Lemna
gibba).

Chronic
Reproductive
Toxicity
Study
for
birds
using
2,4­
DB
or
2,4­
DB­
DMAS.

Estuarine/
marine
Fish
Acute
Toxicity
test
using
2,4­
DB
or
2,4­
DB­
DMAS.

Acute
Estuarine/
marine
Invertebrate
test
using
2,4­
DB
or
2,4­
DB­
DMAS.