Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
1
of
70
UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
Date:
September
13,
2005
MEMORANDUM
SUBJECT:
Dicamba:
HED
Chapter
of
the
Reregistration
Eligibility
Decision
Document
(
RED)
­
Phase
I.
PC
Code:
029801;
DP
Barcode:
D317720.

Regulatory
Action:
Phase
1
Reregistration
Action
Risk
Assessment
Type:
Single
Chemical
Aggregate
FROM:
Christine
Olinger,
Risk
Assessor
Reregistration
Branch
I
Health
Effects
Division
(
7509C)

AND
Yung
Yang,
Ph.
D.,
Toxicologist
Timothy
Dole,
Industrial
Hygienist
Monica
Hawkins,
M.
P.
H.,
Environmental
Health
Scientist
Health
Effects
Division
(
7509C)

THROUGH:
Whang
Phang,
Ph.
D.,
Branch
Senior
Scientist
Reregistration
Branch
I
Health
Effects
Division
(
7509C)

TO:
Kendra
Tyler
Branch
Special
Review
and
Reregistration
Division
(
7508C)
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
2
of
70
Table
of
Contents
1.0
Executive
Summary
.
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4
2.0
Ingredient
Profile
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6
2.1
Summary
of
Registered/
Proposed
Uses
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6
2.2
Structure
and
Nomenclature
.
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6
2.3
Physical
and
Chemical
Properties
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8
3.0
Hazard
Characterization/
Assessment
.
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11
3.1
Hazard
and
Dose­
Response
Characterization
.
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.
11
3.2
Absorption,
Distribution,
Metabolism,
Excretion
(
ADME)
.
.
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12
3.3
FQPA
Considerations
.
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15
3.3.1
Adequacy
of
the
Toxicity
Data
Base
.
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15
3.3.2
Evidence
of
Neurotoxicity
.
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15
3.3.3
Developmental
Toxicity
Studies
.
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16
3.3.4
Reproductive
Toxicity
Study
.
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16
3.3.5
Additional
Information
from
Literature
Sources
.
.
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.
17
3.3.6
Pre­
and/
or
Postnatal
Toxicity
.
.
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.
17
3.3.6.1
Determination
of
Susceptibility
.
.
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.
17
3.3.6.2
Degree
of
Concern
Analysis
and
Residual
Uncertainties
.
17
3.3.7
Recommendation
for
a
Developmental
Neurotoxicity
Study
.
.
.
.
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.
.
18
3.4
Safety
Factor
for
Infants
and
Children
.
.
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18
3.4.1
Adequacy
of
the
Exposure
Data
Base
.
.
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18
3.4.2
Conclusion
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18
3.5
Hazard
Identification
and
Toxicity
Endpoint
Selection
.
.
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.
18
3.5.1
Acute
Reference
Dose
(
aRfD)
­
Females
age
13­
49
.
.
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18
3.5.2
Acute
Reference
Dose
(
aRfD)
­
General
Population
.
.
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19
3.5.3
Chronic
Reference
Dose
(
cRfD)
.
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19
3.5.4
Incidental
Oral
Exposure
(
Short
and
Intermediate
Term)
.
.
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19
3.5.5
Dermal
Absorption
.
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19
3.5.6
Dermal
Exposure
.
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20
3.5.7
Inhalation
Exposure
.
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20
3.5.8
Level
of
Concern
for
Margin
of
Exposure
.
.
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20
3.5.9
Recommendation
for
Aggregate
Exposure
Risk
Assessments
.
.
.
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.
21
3.5.10
Classification
of
Carcinogenic
Potential
.
.
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21
3.6
Endocrine
disruption
.
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23
4.0
Public
Health
and
Pesticide
Epidemiology
Data
.
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23
4.1
Incident
Reports
.
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23
4.2
Other
Pesticide
Epidemiology
Published
Literature
.
.
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24
5.0
Dietary
Exposure/
Risk
Characterization
.
.
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24
5.1
Pesticide
Metabolism
and
Environmental
Degradation
.
.
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24
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
3
of
70
5.1.1
Metabolism
in
Primary
Crops
.
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24
5.1.2
Metabolism
in
Rotational
Crops
.
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25
5.1.3
Metabolism
in
Livestock
.
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25
5.1.4
Analytical
Methodology
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26
5.1.5
Environmental
Degradation
.
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26
5.1.6
Comparative
Metabolic
Profile
.
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27
5.1.7
Pesticide
Metabolites
and
Degradates
of
Concern
.
.
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27
5.1.8
Drinking
Water
Residue
Profile
.
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28
5.1.9
Food
Residue
Profile
.
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29
5.1.10
International
Residue
Limits
.
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29
5.2
Dietary
Exposure
and
Risk
.
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30
6.0
Residential
(
Non­
Occupational)
Exposure/
Risk
Characterization
.
.
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31
6.1
Residential
Handler
Exposure
.
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32
6.2.
Residential
Postapplication
Exposure
.
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33
6.3
Other
(
Spray
Drift,
etc.)
.
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37
7.0
Aggregate
Risk
Assessments
and
Risk
Characterization
.
.
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38
7.1
Acute
Aggregate
Risk
.
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38
7.2
Short­
Term
Aggregate
Risk
.
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39
7.3
Intermediate­
Term
Aggregate
Risk
.
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39
7.4
Long­
Term
Aggregate
Risk
.
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39
7.5
Cancer
Risk
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40
8.0
Cumulative
Risk
Characterization/
Assessment
.
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40
9.0
Occupational
Exposure/
Risk
Pathway
.
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41
9.1
Short/
Intermediate/
Long­
Term/
Cancer
(
if
needed)
Handler
Risk
.
.
.
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41
9.2
Short/
Intermediate/
Long­
Term/
Cancer
(
if
needed)
Postapplication
Risk
.
.
.
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43
10.0
Data
Needs
and
Label
Requirements
.
.
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46
10.1
Toxicology
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.
.
.
.
.
.
.
.
.
.
.
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.
.
.
.
.
.
46
10.2
Residue
Chemistry
.
.
.
.
.
.
.
.
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.
.
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.
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.
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.
.
.
.
46
10.3
Occupational
and
Residential
Exposure
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
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.
47
References:
.
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.
.
.
.
.
.
.
47
Appendix
A:
Toxicology
Assessment
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
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.
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.
.
.
.
.
.
48
Appendix
B:
Use
Profile
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
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.
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.
.
.
.
.
56
Appendix
C:
Tolerance
Reassessment
Summary
and
Table
.
.
.
.
.
.
.
.
.
.
.
.
.
.
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.
59
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
4
of
70
1.0
Executive
Summary
Dicamba
(
2­
methoxy­
3,6­
dichlorobenzoic
acid)
is
a
selective
benzoic
acid
herbicide
registered
for
the
control
of
certain
broadleaf
weeds
and
woody
plants
before
their
emergence.
It
is
an
auxin
agonist
that
is
readily
translocated
symplastically
and
apoplastically
with
accumulation
in
meristemic
regions
of
the
plant.
Sensitive
plants
exhibit
rapid
uncontrolled
growth
characterized
by
twisting
and
curling
of
stems
and
petioles,
stem
elongation
and
swelling
and
leaf
cupping.
Weed
control
is
generally
achieved
in
5
to
7
days.

Different
forms
of
dicamba
(
acid
and
salt)
have
registered
uses
on
rights
of
way
areas,
asparagus,
barley,
corn
(
field
and
pop),
grasses
grown
in
pasture
and
rangeland,
oats,
proso
millet,
rye,
sorghum,
soybeans,
sugarcane,
and
wheat.
Application
rates
range
from
0.5
to
2.8
lb
ae/
A.
Residential
uses
include
broadcast
and
spot
treatment
on
golf
courses
and
lawns.

Dicamba
has
a
low
acute
toxicity
via
oral,
dermal
or
inhalation
route.
It
is
an
eye
and
dermal
irritant
but
it
is
not
a
skin
sensitizer.
Following
oral
administration,
dicamba
is
rapidly
absorbed
and
excreted
in
urine
and
feces.
Consistent
neurotoxic
signs
(
e.
g.,
ataxia,
decreased
motor
activity,
impaired
righting
reflex
and
gait)
were
observed
in
many
studies
in
rats
and
rabbits
at
high
doses.
There
was
an
increased
incidence
of
abortion
in
the
rabbit
developmental
toxicity
study
at
doses
that
also
showed
maternal
toxicity.
In
a
two­
generation
reproduction
study,
offspring
toxicity
was
manifested
as
decreased
pup
body
weight
gain
in
all
generations
at
a
dose
lower
than
the
parental
systemic
toxicity
NOAEL.
Developmental
studies
in
rats
and
rabbits
showed
no
evidence
(
qualitative
or
quantitative)
for
increased
susceptibility
following
in
utero
and/
or
pre­/
post­
natal
exposure
of
dicamba.
Dicamba
is
classified
as
"
Not
Likely
to
be
Carcinogenic
to
Humans"
by
the
oral
route.
Mutagenicity
studies
did
not
demonstrate
evidence
of
mutagenic
potential
for
dicamba
although
some
positive
results
were
reported
in
published
literature.

An
acute
neurotoxicity
study
in
rats
was
selected
for
the
general
population,
including
infants
and
children,
for
an
endpoint
of
concern
for
a
single
oral
exposure
risk
assessment.
For
the
short­
and
intermediate­
term
incidental
oral
exposure
and
the
chronic
RfD,
a
multi­
generation
reproduction
study
in
rats
was
selected
based
on
impaired
pup
growth
(
decreased
pup
weights).

The
dermal
exposure
limits
for
all
durations
were
based
on
a
multi­
generation
reproduction
study
in
rats.
The
rat
28­
day
dermal
toxicity
study
was
not
selected
because
the
offspring
effect
in
the
reproductive
study
was
not
measured
in
this
study.
In
addition,
the
NOAEL
(
1000
mg/
kg/
day)
in
the
28­
day
dermal
toxicity
study
would
not
be
protective
of
the
reproductive­
offspring
effects
in
the
rat
multi­
generation
reproduction
study
with
a
NOAEL
of
45
mg/
kg/
day
using
a
dermal
absorption
factor
of
15%.
The
multi­
generation
reproduction
study
with
a
longer
duration
and
a
NOAEL
of
45
mg/
kg/
day
will
be
protective
and
appropriate
for
short­,
intermediate­
and
longterm
dermal
risk
assessments.
Since
an
oral
NOAEL
was
selected,
a
15%
dermal
absorption
factor
was
used
for
route­
to­
route
extrapolation
for
assessing
dermal
risk.

The
inhalation
endpoints
selected
paralleled
the
determinations
made
for
the
dermal
exposure
assessments
above
and
assumed
a
100%
default
assumption
in
the
absence
of
a
repeated
exposure
inhalation
toxicity
study.
Dicamba
Human
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Assessment
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of
70
The
uncertainty
factors
used
in
determining
the
acute
and
chronic
RfD
exposure
limit
were
100x
(
10x
for
intraspecies
variation
and
10x
for
interspecies
extrapolation).
An
additional
3x
was
applied
to
acute
dietary
risk
assessment
for
general
population
for
using
a
LOAEL
in
establishing
the
acute
reference
dose.

Several
plant
metabolism
studies
have
been
submitted
for
dicamba.
Generally
there
are
two
major
plant
metabolites
3,6­
dichloro­
5­
hydroxybenzoic
acid
(
5­
OH
dicamba)
and
3,6­
dichlorosalicylic
acid
(
DCSA),
which
are
structurally
similar
to
the
parent
compound
and
are
included
in
the
dietary
risk
assessment.
The
dietary
exposure
estimates
were
conducted
assuming
100%
crop
treated
and
tolerance­
level
residues
in
all
crops.
For
the
acute
and
chronic
assessments
the
most
highly
exposed
subgroup
was
children,
ages
1­
2.
The
exposure
estimates
were
well
below
the
levels
of
concern,
with
the
acute
exposure
at
5.4%
of
the
acute
population
adjusted
dose
(
aPAD)
and
the
chronic
exposure
at
6.5%
of
the
chronic
population
adjusted
dose
(
cPAD).
The
actual
exposures
are
likely
to
be
much
lower
than
those
estimated
in
this
assessment
because
of
the
percent
crop
treated
and
residue
levels
used
in
this
evaluation.

Dicamba
could
potentially
be
found
in
drinking
water.
Environmental
fate
studies
show
that
the
major
environmental
degradate
would
be
DCSA.
Sufficient
drinking
water
monitoring
data
from
surface
water
sources
were
not
available
so
estimated
drinking
water
concentrations
(
EDWCs)
were
determined
for
surface
water
resources
using
PRZM­
EXAMS.
Ground
water
monitoring
data
were
used
for
a
scoping
assessment
when
ground
water
could
be
a
source
of
drinking
water.
When
food
and
water
exposures
are
aggregated
the
total
dietary
exposure
for
acute
and
chronic
scenarios
are
well
below
the
level
of
concern
for
all
population
groups.

Exposure
to
dicamba
may
occur
in
residential
settings
from
treatment
of
turf
around
the
home
and
at
golf
courses.
Residential
handler
assessments
were
conducted
for
homeowners
applying
dicamba
to
lawns
using
various
types
of
application
equipment.
Residential
post­
application
assessments
were
conducted
for
adults
doing
yardwork
after
application
or
playing
golf
on
treated
turf,
and
were
conducted
for
children
playing
on
a
treated
lawn
or
consuming
dirt
or
pesticide
granules
while
playing.
Even
when
exposures
occur
on
the
day
of
treatment,
all
of
the
residential
exposures
are
considerably
below
the
level
of
concern.

The
Food
Quality
Protection
Act
(
FQPA)
requires
EPA
to
aggregate
or
add
exposures
from
food,
water,
and
residential
settings.
When
residential
handler
or
post­
application
exposures
are
added
to
food
and
water
exposures
for
any
exposure
duration,
the
risk
estimates
are
all
well
below
the
levels
of
concern.
For
example,
the
scenario
with
the
highest
exposure
estimate,
a
child
playing
on
a
treated
lawn
and
consuming
treated
food)
produced
a
margin
of
exposure
(
MOE)
of
1030;
any
exposure
with
an
MOE
exceeding
100
is
considered
to
be
not
of
concern.

The
risks
for
occupational
exposures
were
estimated
for
pesticide
applicators
as
well
as
people
who
may
enter
treated
fields
after
application.
The
MOEs
were
calculated
for
short/
intermediate
term
dermal
and
inhalation
exposures
using
standard
assumptions
and
unit
exposure
data
for
a
wide
range
of
application
methods
and
equipment.
The
unit
exposure
data
were
taken
from
the
Pesticide
Handlers
Exposure
Database
(
PHED)
and
the
Outdoor
Residential
Exposure
Task
Force
(
ORETF)
studies
for
professional
lawn
care
operators.
All
of
the
mixer/
loader
MOEs
exceed
the
target
of
100
with
the
single
layer
personal
protective
equipment
(
PPE)
and
are
not
of
Dicamba
Human
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6
of
70
Cl
Cl
O
OH
OCH
3
concern.
The
MOEs
for
applicators
are
above
100
with
baseline
or
single
layer
PPE
.
The
MOEs
for
the
mixer/
loader/
applicators
are
acceptable
with
single
layer
PPE
and
the
MOEs
for
the
flaggers
are
acceptable
with
baseline
PPE.
The
labels
typically
require
baseline
clothing
with
water
proof
gloves.
There
are
no
residual
concerns
regarding
occupational
exposure
to
dicamba.

2.0
Ingredient
Profile
2.1
Summary
of
Registered/
Proposed
Uses
Dicamba
(
2­
methoxy­
3,6­
dichlorobenzoic
acid)
is
a
selective
benzoic
acid
herbicide
registered
for
the
control
of
certain
broadleaf
weeds
and
woody
plants
before
their
emergence.
It
is
an
auxin
agonist
that
is
readily
translocated
symplastically
and
apoplastically
with
accumulation
in
meristemic
regions
of
the
plant.
Sensitive
plants
exhibit
rapid
uncontrolled
growth
characterized
by
twisting
and
curling
of
stems
and
petioles,
stem
elongation
and
swelling
and
leaf
cupping.
Weed
control
is
generally
achieved
in
5
to
7
days.

Different
forms
of
dicamba
(
acid
and
salt)
have
registered
uses
on
rights
of
way
areas,
asparagus,
barley,
corn
(
field
and
pop),
grasses
grown
in
pasture
and
rangeland,
oats,
proso
millet,
rye,
sorghum,
soybeans,
sugarcane,
and
wheat.
Application
rates
range
from
0.5
to
2.8
lb
ae/
A.
Residential
uses
include
broadcast
and
spot
treatment
on
golf
courses
and
lawns.

The
registrants
intend
to
support
all
currently
registered
uses
described
in
the
Use
Profile,
which
is
provided
in
Appendix
B
of
this
document.
The
different
forms
of
dicamba
acid
and
salts
that
will
be
supported
for
reregistration,
include:
the
dicamba
acid
(
PC
Code
029801),
dimethylamine
(
DMA)
salt
(
PC
Code
029802),
sodium
(
Na)
salt
(
PC
Code
029806),
isopropylamine
(
IPA)
salt
(
PC
Code
128944),
diglycolamine
(
DGA)
salt
(
PC
Code
128931),
and
potassium
(
K)
salt
(
PC
Code
129043).

There
were
approximately
434
active
products
of
Dicamba
formulated
from
6
different
forms.
The
acid,
dimethylamine
and
sodium
salt
ester
forms
of
Dicamba
have
the
most
products.
The
products
are
formulated
as
liquids,
standard
granules
and
water
dispersible
granules.
The
residential
products
are
typically
formulated
as
granular
weed
and
feed
formulations
or
as
liquids
in
concentrates
or
ready
to
use
sprays.

2.2
Structure
and
Nomenclature
TABLE
2.1.
Dicamba
and
its
Salts
Nomenclature
PC
Code
029801
Chemical
structure
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
TABLE
2.1.
Dicamba
and
its
Salts
Nomenclature
Page
7
of
70
Cl
Cl
O
O
­[
NH
2
(
CH
3
)
2
]+

OCH
3
Cl
Cl
O
O
­
Na
+

OCH
3
Cl
Cl
O
O
­[
NH
3
CH
2
CH
2
OCH
2
CH
2
OH]+

OCH
3
Common
name
Dicamba
acid
Molecular
Formula
C8H6Cl2O3
Molecular
Weight
221.04
IUPAC
name
3,6­
dichloro­
o­
anisic
acid
CAS
name
3,6­
dichloro­
2­
methoxybenzoic
acid
or
2­
methoxy­
3,6­
dichlorobenzoic
acid
CAS
#
1918­
00­
9
PC
Code
029802
Chemical
structure
Common
name
Dicamba
dimethylamine
salt
(
DMA
salt)

Molecular
Formula
C10H13Cl2NO3
Molecular
Weight
266.1
CAS
#
2300­
66­
5
PC
Code
029806
Chemical
structure
Common
name
Dicamba
sodium
salt
(
Na
salt)

Molecular
Formula
C8H5Cl2NaO3
Molecular
Weight
243.0
CAS
#
1982­
69­
0
PC
Code
128931
Chemical
structure
Common
name
Dicamba
diglycolamine
salt
(
DGA
salt)

Molecular
Formula
C12H17Cl2NO5
Molecular
Weight
326.18
CAS
#
104040­
79­
1
Dicamba
Human
Health
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I
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TABLE
2.1.
Dicamba
and
its
Salts
Nomenclature
Page
8
of
70
Cl
Cl
O
OCH
3
O
­[
NH
3
CH(
CH
3
)
2
]+

Cl
Cl
O
OCH
3
O
­
K
+
PC
Code
128944
Chemical
structure
Common
name
Dicamba
isopropylamine
salt
(
IPA
salt)

Molecular
Formula
C11H15Cl2NO3
Molecular
Weight
280.15
CAS
#
55871­
02­
8
PC
Code
129043
Chemical
structure
Common
name
Dicamba
potassium
salt
(
K
salt)

Molecular
Formula
C8H5Cl2KO3
Molecular
Weight
259.1
CAS
#
10007­
85­
9
2.3
Physical
and
Chemical
Properties
TABLE
2.2.
Physicochemical
Properties
of
Dicamba
and
its
Salts
Parameter
Value
Reference
Dicamba
acid
(
PC
Code
029801)

Melting
point
114­
116
°
C
(
PAI)
90­
100
°
C
(
87%
TGAI)
SRR
Reregistration
Standard,
6/
30/
89
pH
2.5­
3.0
(
87%
TGAI)

Density,
bulk
density,
or
specific
gravity
1.57
g/
mL
at
25
°
C
(
87%
TGAI)

Water
solubility
0.5
g/
100
mL
at
25
°
C
(
PAI)
Dicamba
Human
Health
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Assessment
­
Phase
I
Barcode:
D317720
TABLE
2.2.
Physicochemical
Properties
of
Dicamba
and
its
Salts
Parameter
Value
Reference
Page
9
of
70
Solvent
solubility
g/
100
mL
at
25
°
C
(
PAI)
dioxane
118.0
ethanol
92.2
isopropyl
alcohol
76.0
methylene
chloride
26.0
acetone
17.0
toluene
13.0
xylene
7.8
heavy
aromatic
naphthalene
5.2
Vapor
pressure
3.4
x
10­
5
mm
Hg
at
25
°
C
(
PAI)

Dissociation
constant,
pKa
1.97
(
PAI)

Octanol/
water
partition
coefficient
0.1
(
PAI)

UV/
visible
absorption
spectrum
neutral:
511
(
275
nm)
acidic
(
pH
0­
1):
1053
(
281
nm)
basic
(
pH
13­
14):
469
(
274
nm)
RD
D266167,
6/
26/
00,
B.
Kitchens
Dicamba
DMA
salt
(
PC
Code
029802)

Melting
point
101.0­
114.5
°
C
D213276,
D216855,
D216859,
D216853,
D216857,
D216862,
D217061,
D218789,
D218792,
D218784,
D218787,
and
D218786,
11/
21/
95,
L.
Cheng
pH
3.89
at
25
°
C
(
1%
solution)

Density,
bulk
density,
or
specific
gravity
0.77
g/
mL
at
25
°
C
(
tap
density)

Water
solubility
94.5
g/
100
mL
at
25
°
C
Solvent
solubility
N/
A;
data
for
the
free
acid
are
representative
of
the
dicamba
salts
D198000,
5/
5/
94,
P.
Deschamp
Vapor
pressure
Dissociation
constant,
pKa
Octanol/
water
partition
coefficient
KOW
=
0.078
D213276,
D216855,
D216859,
D216853,
D216857,
D216862,
D217061,
D218789,
D218792,
D218784,
D218787,
and
D218786,
11/
21/
95,
L.
Cheng
UV/
visible
absorption
spectrum
Not
available
Dicamba
Na
salt
(
PC
Code
029806)

Melting
point
320­
325
°
C
RD
Memorandum,
9/
26/
94,
T.
Alston
pH
7.16
Density,
bulk
density,
or
specific
gravity
1.03
g/
mL
at
25
°
C
Water
solubility
N/
A;
data
for
the
organic
salts
(
DMA,
DGA,
and
IPA)
are
representative
of
the
Na
salt
D198000,
5/
5/
94,
P.
Deschamp
Solvent
solubility
N/
A;
data
for
the
free
acid
are
representative
of
the
dicamba
salts
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
TABLE
2.2.
Physicochemical
Properties
of
Dicamba
and
its
Salts
Parameter
Value
Reference
Page
10
of
70
Vapor
pressure
Dissociation
constant,
pKa
Octanol/
water
partition
coefficient
N/
A;
data
for
the
organic
salts
(
DMA,
DGA,
and
IPA)
are
representative
of
the
Na
salt
UV/
visible
absorption
spectrum
Not
available
Dicamba
DGA
salt
(
PC
Code
128931)

Melting
point
52.0­
85.0
°
C
D213276,
D216855,
D216859,
D216853,
D216857,
D216862,
D217061,
D218789,
D218792,
D218784,
D218787,
and
D218786,
11/
21/
95,
L.
Cheng
pH
7.60
at
25
°
C
(
1%
solution)

Density,
bulk
density,
or
specific
gravity
0.69
g/
mL
at
25
°
C
(
tap
density)

Water
solubility
107
g/
100
mL
at
25
°
C
Solvent
solubility
N/
A;
data
for
the
free
acid
are
representative
of
the
dicamba
salts
D198000,
5/
5/
94,
P.
Deschamp
Vapor
pressure
Dissociation
constant,
pKa
Octanol/
water
partition
coefficient
KOW
=
0.061
D213276,
D216855,
D216859,
D216853,
D216857,
D216862,
D217061,
D218789,
D218792,
D218784,
D218787,
and
D218786,
11/
21/
95,
L.
Cheng
UV/
visible
absorption
spectrum
Not
available
Dicamba
IPA
salt
(
PC
Code
128944)

Melting
point
93.5­
127.5
°
C
D213276,
D216855,
D216859,
D216853,
D216857,
D216862,
D217061,
D218789,
D218792,
D218784,
D218787,
and
D218786,
11/
21/
95,
L.
Cheng
pH
4.68
at
25
°
C
(
1%
solution)

Density,
bulk
density,
or
specific
gravity
0.63
g/
mL
at
25
°
C
(
tap
density)

Water
solubility
59.6
g/
100
mL
at
25
°
C
Solvent
solubility
N/
A;
data
for
the
free
acid
are
representative
of
the
dicamba
salts
D198000,
5/
5/
94,
P.
Deschamp
Vapor
pressure
Dissociation
constant,
pKa
Octanol/
water
partition
coefficient
KOW
=
0.070
D213276,
D216855,
D216859,
D216853,
D216857,
D216862,
D217061,
D218789,
D218792,
D218784,
D218787,
and
D218786,
11/
21/
95,
L.
Cheng
UV/
visible
absorption
spectrum
Not
available
Dicamba
K
salt
(
PC
Code
129043)
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
TABLE
2.2.
Physicochemical
Properties
of
Dicamba
and
its
Salts
Parameter
Value
Reference
Page
11
of
70
Melting
point
Decomposes
at
213.5
°
C
D213276,
D216855,
D216859,
D216853,
D216857,
D216862,
D217061,
D218789,
D218792,
D218784,
D218787,
and
D218786,
11/
21/
95,
L.
Cheng
pH
8.12
at
25
°
C
(
1%
solution)

Density,
bulk
density,
or
specific
gravity
0.88
g/
mL
at
25
°
C
(
tap
density)

Water
solubility
N/
A;
data
for
the
organic
salts
(
DMA,
DGA,
and
IPA)
are
representative
of
the
K
salt
D198000,
5/
5/
94,
P.
Deschamp
Solvent
solubility
N/
A;
data
for
the
free
acid
are
representative
of
the
dicamba
salts
Vapor
pressure
Dissociation
constant,
pKa
Octanol/
water
partition
coefficient
N/
A;
data
for
the
organic
salts
(
DMA,
DGA,
and
IPA)
are
representative
of
the
K
salt
UV/
visible
absorption
spectrum
Not
available
3.0
Hazard
Characterization/
Assessment
3.1
Hazard
and
Dose­
Response
Characterization
Dicamba
has
a
low
acute
toxicity
via
oral,
dermal
or
inhalation
route.
It
is
an
eye
and
dermal
irritant
but
it
is
not
a
skin
sensitizer.
Following
oral
administration,
dicamba
is
rapidly
absorbed
and
excreted
in
urine
and
feces
without
significant
metabolism.
Dogs
are
generally
considered
to
be
toxicologically
more
sensitive
when
exposed
to
dicamba.
However,
a
submitted
toxicity
study
in
dogs
showed
that
no
effect
was
seen
at
the
highest
dose
tested
(
52
mg/
kg/
day)
which
indicated
that
the
animals
in
the
study
were
not
tested
at
high
enough
doses.
Consistent
neurotoxic
signs
(
e.
g.,
ataxia,
decreased
motor
activity,
impaired
righting
reflex
and
gait)
were
observed
in
many
studies
in
rats
and
rabbits
at
high
doses.
There
is
an
increased
incidence
of
abortion
in
the
rabbit
developmental
toxicity
study
at
doses
that
also
showed
maternal
toxicity.
In
a
two­
generation
reproduction
study,
offspring
toxicity
was
manifested
as
decreases
in
pup
weight
in
all
generations
at
a
dose
lower
than
the
parental
systemic
toxicity
NOAEL.
Developmental
studies
in
rats
and
rabbits
showed
no
evidence
(
qualitative
or
quantitative)
for
increased
susceptibility
following
in
utero
and/
or
pre­/
post­
natal
exposure
of
dicamba.
Dicamba
is
classified
as
"
Not
Likely
to
be
Carcinogenic
to
Humans"
by
the
oral
route.
Mutagenicity
studies
did
not
demonstrate
evidence
of
mutagenic
potential
for
dicamba
although
some
positive
results
were
reported
in
published
literature.

An
acute
neurotoxicity
study
in
rats
was
selected
for
the
general
population,
including
infants
and
children,
for
an
endpoint
of
concern
for
a
single
oral
exposure
risk
assessment.
For
the
short­
and
intermediate­
term
incidental
oral
exposure
and
the
chronic
RfD,
a
multi­
generation
reproduction
study
in
rats
was
selected
based
on
impaired
pup
growth
(
decreased
pup
weights).
Dicamba
Human
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Risk
Assessment
­
Phase
I
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Page
12
of
70
The
dermal
exposure
limits
for
all
durations
were
based
on
a
multi­
generation
reproduction
study
in
rats.
The
rat
28­
day
dermal
toxicity
study
was
not
selected
because
the
offspring
effect
in
the
reproductive
study
was
not
measured
in
this
study.
In
addition,
the
NOAEL
(
1000
mg/
kg/
day)
in
the
28­
day
dermal
toxicity
study
would
not
be
protective
of
the
reproductive­
offspring
effects
in
the
rat
multi­
generation
reproduction
study
with
a
NOAEL
of
45
mg/
kg/
day
using
a
dermal
absorption
factor
of
15%.
The
multi­
generation
reproduction
study
with
a
longer
duration
and
a
NOAEL
of
45
mg/
kg/
day
will
be
protective
and
appropriate
for
short­,
intermediate­
and
longterm
dermal
risk
assessments.
Since
an
oral
NOAEL
was
selected,
a
15%
dermal
absorption
factor
was
used
for
route­
to­
route
extrapolation.

The
inhalation
endpoints
selected
paralleled
the
determinations
made
for
the
dermal
exposure
assessments
above
and
assumed
a
100%
default
relative
inhalation
to
oral
absorption
assumption
in
the
absence
of
a
repeated
exposure
inhalation
toxicity
study.

The
uncertainty
factors
used
in
determining
the
acute
and
chronic
RfD
exposure
limit
were
100x
(
10x
for
intraspecies
variation
and
10x
for
interspecies
extrapolation).
An
additional
3x
was
applied
to
acute
dietary
risk
assessment
for
general
population
for
using
a
LOAEL
because
most
of
the
clinical
signs
of
neurotoxicity
were
seen
at
repeated
doses
of
150
mg/
kg/
day
or
above
(
TXR
No.
0050280).

Note
that
a
profile
of
the
acute
toxicity
studies
may
be
found
in
Table
3.1
and
other
studies
may
be
found
in
Table
3.2.

3.2
Absorption,
Distribution,
Metabolism,
Excretion
(
ADME)

Multiple
studies
describing
the
metabolism
or
the
pharmacokinetic
of
dicamba
in
rats
have
been
submitted
to
the
Agency.
The
metabolism
study
in
rats
showed
that
following
oral
administration,
dicamba
is
rapidly
absorbed
and
excreted.
Over
95%
is
excreted
in
the
urine
and
the
compound
is
not
metabolized
or
accumulated
by
the
tissues.

The
plasma
pharmacokinetic
studies
in
rats
showed
that
absorption
of
the
radiolabeled
dicamba
was
rapid,
with
peak
plasma
concentrations
found
within
2
hours
of
treatment.
Absorption
was
not
saturated,
even
at
the
highest
dose,
as
indicated
by
increasing
plasma
concentrations
with
doses.
However,
the
increase
in
plasma
concentration
was
non­
linear
and
disproportionate
from
one
dose
to
the
next
doses,
which
is
consistent
with
saturation
of
excretion.
No
significant
treatment­
related
differences
between
the
sexes
or
time
of
radiolabel
administration
were
found.
Another
plasma
pharmacokinetic
study
suggested
that
dicamba
acts
as
an
inhibitor
of
renal
anion
transport.

Table
3.1.
Acute
Toxicity
Profile
on
Dicamba
OPPTS
Guideline
Study
Type
MRID
Results
Toxicity
Category
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
3.1.
Acute
Toxicity
Profile
on
Dicamba
Page
13
of
70
870.1100
Acute
oral
toxicity
/
rat
00078444
LD50
=>
2740
mg/
kg
III
870.1200
Acute
dermal
toxicity
/
rat
00241584
LD50
=>
2000
mg/
kg
III
870.1300
Acute
inhalation
toxicity
/
rat
00263861
LC50
=>
5.3
mg/
L
IV
870.2400
Primary
eye
irritation
/
rabbit
00241584
Irritant
II
870.2500
Primary
dermal
irritation
/
rabbit
00237955
Irritant
II
870.2600
Dermal
sensitization
/
guinea
pig
00263861
Non­
Sensitizer
­­

Table
3.2.
Subchronic,
Chronic
and
Other
Toxicity
Profile
for
Dicamba
Guideline
No./
Study
Type/
MRID
Nos.
Doses/
Classification
Results
870.3100
Subchronic
Oral
­
Rat
44623101
(
1997)
(
0,
500,
3000,
6000,
12000
ppm)
M:
0,40.1,238.7,479.4,1000
mg/
kg/
day
F:
0,43.2,266.4,535.6,1065.3
mg/
kg/
day
Acceptable/
Guideline
NOAEL=
479.4/
535.6
mg/
kg/
day(
M/
F).
LOAEL=
1000/
1065.3
mg/
kg/
day
(
M/
F)
based
on
clinical
signs,
decr.
body
weight
gains,
incr.
liver
wt
and
incr.
centrolobular
hepatocyte
hypertrophy
and
hepatocellular
pigmentation.

870.3200
28­
Day
dermal
toxicity
­
Rat
45814501
(
2002)
0,30,300,1000
mg/
kg/
day
(
M/
F)
Acceptable/
Guideline
NOAEL=
1000
mg/
kg/
day
(
HDT)
LOAEL=
not
determined.

870.3700a
Prenatal
developmental
­
Rat
00084024
(
1981)
0,64,160,400
mg/
kg/
day
(
GD
6­
19)
Acceptable/
Guideline
Maternal:
NOAEL=
160
mg/
kg/
day;
LOAEL=
400
mg/
kg/
day
based
on
Incr.
mortality,
clinical
signs,
decr.
body
weight
gains,
decr.
food
consumption.
Developmental:
NOAEL=
400
mg/
kg/
day
(
HDT),
LOAEL
not
established.

870.3700b
Prenatal
developmental
­
NZW
Rabbit
42429401
(
1992)
0,30,150,300
mg/
kg/
day
(
GD
6­
18)
Range­
finding:
0,62.5,125,250,500
mg/
kg/
day
(
GD
6­
18)
Acceptable/
Guideline
Maternal:
NOAEL=
62.5
mg/
kg/
day,
LOAEL=
150
mg/
kg/
day
based
on
incr.
abortion,
clinical
signs
(
decr.
motor
activity,
ataxia).
Developmental:
NOAEL=
62.5
mg/
kg/
day,
LOAEL=
150
mg/
kg/
day
based
on
incr.
abortion.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
3.2.
Subchronic,
Chronic
and
Other
Toxicity
Profile
for
Dicamba
Guideline
No./
Study
Type/
MRID
Nos.
Doses/
Classification
Results
Page
14
of
70
870.3800
Reproduction
and
fertility
effects
­
Rat
43137101
(
1993)
(
0,500,1500,5000
ppm)
M:
0,40,122,419
mg/
kg/
day
F:
0,45,
136,
450
mg/
kg/
day
Acceptable/
Guideline
Parental/
Systemic:
NOAEL=
122/
136
mg/
kg/
day
(
M/
F);
LOAEL=
419/
450
mg/
kg/
day
(
M/
F)
based
on
clinical
signs
(
slow
righting
reflex).
Reproductive:
NOAEL=
122
mg/
kg/
day;
LOAEL=
419
mg/
kg/
day
based
on
delayed
sexual
maturation
in
F1
males.
Offspring:
NOAEL=
45
mg/
kg/
day;
LOAEL=
136
mg/
kg/
day
based
on
impaired
pup
growth
(
decr.
pup
weights)
in
all
generations
during
lactation
period.

870.4200a
Chronic
Toxicity/
Carcinogenicity
­
Rat
00146150
(
1985)
(
0,50,250,2500
ppm)
M:
0,2,11,107
mg/
kg/
day
F:
0,3,13,127
mg/
kg/
day
Acceptable/
Guideline
NOAEL=
107/
127
mg/
kg/
day
(
M/
F),
LOAEL
was
not
established.
Not
carcinogenic.
The
study
is
considered
adequate
for
evaluating
the
carcinogenic
potential.

870.4100b
Chronic
toxicity
­
dog
40321102
(
1986)
(
0,100,500,2500
ppm)
0,2,11,52
mg/
kg/
day
Acceptable/
Guideline
NOAEL=
52
mg/
kg/
day
(
HDT).

870.4200b
Carcinogenicity
­
mouse
40872401
(
1988)
(
0,50,150,1000,3000
ppm)
M:
0,5.5,17.2,108,358
mg/
kg/
day
F:
0,5.8,18.8,121,354
mg/
kg/
day
Acceptable/
Guideline
NOAEL=
358/
354
mg/
kg/
day
(
M/
F),
LOAEL
was
not
established.
Not
carcinogenic.
The
study
is
considered
adequate
for
evaluating
the
carcinogenic
potential.

870.5100
Gene
Mutation
Salmonella
typhimurium
00143001(
1979)
Acceptable/
Guideline
Not
mutagenic.

870.5395
Chromosome
aberration
(
CHO)
40321101
(
1986)
Acceptable/
Guideline
Chromosome
aberrations
were
not
induced
in
a
cultured
CHO
cells
at
concentrations
of
2330,
1170,
590,
and
300
µ
g/
mL
either
with
or
without
S­
9
activation.

870.5550
Unscheduled
DNA
synthesis
(
UDS)
00143001
(
1979)
Acceptable/
Guideline
No
evidence
of
UDS
at
levels
0.1
to
3000
µ
g/
mL.

870.6200
Acute
Neurotoxicity
­
Rat
42774104
(
1993)
0,300,600,1200
mg/
kg
Acceptable/
Guideline
NOAEL
was
not
established,
LOAEL=
300
mg/
kg
based
on
severe
neurologic
signs
(
impaired
respiration,
rigidity
upon
handling,
prodding,
or
dropping,
impaired
gait
and
righting
reflex
in
both
sexes.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
3.2.
Subchronic,
Chronic
and
Other
Toxicity
Profile
for
Dicamba
Guideline
No./
Study
Type/
MRID
Nos.
Doses/
Classification
Results
Page
15
of
70
870.6200
Subchronic
neurotoxicity
­
Rat
43245210
(
1994)
(
0,3000,6000,12000
ppm)
M:
0,197.1,401.4,767.9
mg/
kg/
day
F:
0,253.4,472.0,1028.9
mg/
kg/
day
Acceptable/
Guideline
NOAEL=
401.4/
472.0
mg/
kg/
day
(
M/
F);
LOAEL=
767.9/
1028.9
mg/
kg/
day
(
M/
F)
based
on
rigidity
body
tone,
slightly
impaired
righting
reflex
and
gait.

870.6300
Developmental
Neurotoxicity
­
Rat
Data
Gap
Not
available.

870.7485
Metabolism
00028261(
1967)
Acceptable/
guideline
Rapidly
absorbed
and
excreted
in
urine
and
feces.
Dicamba
is
not
metabolized
or
bioaccumulation.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
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Page
16
of
70
3.3
FQPA
Considerations
The
database
is
adequate
in
terms
of
endpoint
studies
and
dose
response
information
to
select
appropriate
endpoints
for
prenatal
or
postnatal
risk
for
infants
and
children.
There
is
no
evidence
(
qualitative
or
quantitative)
of
increased
susceptibility
following
in
utero
and/
or
pre­
natal
exposure
in
the
developmental
toxicity
studies
in
rats
and
rabbits.
There
was
evidence
of
increased
sensitivity
to
the
offspring
following
pre­
and/
or
postnatal
exposure
in
the
two­
generation
reproduction
study
in
rats.
In
that
study,
offspring
toxicity
was
manifested
as
decreased
pup
body
weight
in
all
generations
at
a
dose
lower
than
the
parental
systemic
toxicity
NOAEL.
However,
the
degree
of
concern
is
low
for
the
quantitative
susceptibility
because
the
risk
assessment
was
based
on
the
very
same
effect
seen
in
the
pups
with
a
definitive
NOAEL.
There
are
no
concern
or
residual
uncertainties
for
pre­
and
postnatal
toxicity.

After
considering
the
available
toxicity
data,
the
risk
assessment
team
determined
that
a
developmental
neurotoxicity
study
(
DNT)
is
not
required
based
on
the
following
reasons:
(
1)
although
clinical
signs
of
neurotoxicity
were
seen
in
pregnant
animals,
no
evidence
of
developmental
anomalies
of
the
fetal
nervous
system
were
observed
in
the
prenatal
developmental
toxicity
studies,
in
either
rats
or
rabbits,
at
maternally
toxic
doses
up
to
300
or
400
mg/
kg/
day,
respectively;
(
2)
there
were
no
evidence
of
behavioral
or
neurological
effects
on
the
offspring
in
the
two­
generation
reproduction
study
in
rats;
(
3)
the
ventricular
dilation
of
the
brain
in
the
chronic
toxicity
study
was
only
observed
in
females
at
the
high
dose
after
two
years
exposure.
The
significance
of
this
observation
is
questionable
since
no
similar
histopathological
finding
was
seen
in
the
subchronic
neurotoxicity
study.
In
addition,
the
dicamba
risk
assessment
team
evaluated
the
quality
of
the
exposure
data;
and,
based
on
these
data,
recommended
that
the
special
FQPA
SF
be
reduced
to
1x.

3.3.1
Adequacy
of
the
Toxicity
Data
Base
The
following
studies
are
available
in
the
toxicity
database:
­
Developmental
toxicity
studies
in
rats
and
rabbits
(
acceptable).
­
Two
generation
reproduction
study
in
rats
(
acceptable).
­
Acute
and
subchronic
neurotoxicity
studies
in
rats
(
acceptable).

3.3.2
Evidence
of
Neurotoxicity
There
is
evidence
of
neurotoxicity
resulting
from
exposure
to
dicamba.
The
velevant
findings
are
summarized
below
and
the
executive
summaries
of
studies
are
presented
in
Appendix
A.

In
the
acute
neurotoxicity
study,
at
300
mg/
kg
bw
or
above,
clinical
signes
of
neurotoxicity
consisted
of
impaired
gait
and
righting
reflex,
decreased
arousal
and
rears/
minutes,
and
rigidity
upon
handling
were
found.
At
higher
dose
levels,
the
effects
were
more
pronounced
with
additional
effects.
The
subchronic
neurotoxicity
study
in
rats
showed
rigid
body
tone,
impaired
righting
reflex
and
gait
at
768
mg/
kg.

In
the
developmental
toxicity
studies
in
rats
ataxia,
stiffening
of
the
body
when
touched,
and
decreased
motor
activity
were
seen
at
400
mg/
kg
in
the
dams.
The
developmental
toxicity
study
in
rabbits
showed
that
at
150
mg/
kg
the
dams
presented
signs
of
ataxia,
rales
and
decreased
motor
Dicamba
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Health
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­
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Barcode:
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of
70
activity.

A
two
generation
reproduction
study
demonstrated
tense/
stiff
body
tone
and
slow
righting
reflex
in
the
dams
from
both
generations
at
approximately
450
mg/
kg.
It
should
be
noted
that
the
signs
of
neurotoxicity
were
consistent
across
several
studies.

3.3.3
Developmental
Toxicity
Studies
In
a
developmental
toxicity
study
(
MRID
No.
00084024),
pregnant
(
CD
Charles
River)
rats
(
25/
dose
group)
received
gavage
administration
of
dicamba
(
85.3%)
in
corn
oil
at
dose
levels
of
0,
64,
160,
or
400
mg/
kg/
day
during
gestation
days
6
through
19.
Maternal
toxicity
limited
to
the
high
dose
(
400
mg/
kg/
day)
was
characterized
by
mortality
in
three
gravid
and
one
non­
gravid
dams
that
exhibited
neurotoxic
signs
prior
to
death;
clinical
signs
of
nervous
system
toxicity
that
included
ataxia,
salivation,
stiffening
of
the
body
when
held,
and
decreased
motor
activity;
statistically
significant
(
p<
0.05)
decreases
in
body
weight
gain
during
the
dosing
period;
and
concomitant
decreases
in
food
consumption.
Dicamba
had
no
effect
on
any
of
the
cesarean
parameters.
For
maternal
toxicity,
the
NOAEL
was
160
mg/
kg/
day
and
the
LOAEL
was
400
mg/
kg/
day
based
on
mortality,
clinical
signs,
body
weight
changes
and
decreases
in
food
consumption.
No
Treatment­
related
fetal
gross
external,
skeletal
or
visceral
anomalies
(
malformations
or
variations)
were
seen
at
any
dose
level.
For
developmental
toxicity,
the
NOAEL
was
>
400
mg/
kg/
day;
a
LOAEL
was
not
established.
This
study
is
classified
acceptable/
guideline
(
OPPTS
870.3700a)
and
satisfies
the
requirements
for
a
developmental
toxicity
study
in
the
rat.

In
a
developmental
toxicity
study
(
MRID
No.
42429401),
inseminated
New
Zealand
White
rabbit
(
19­
20/
dose)
were
given
oral
capsules
containing
dicamba
(
90.5%)
at
dose
levels
of
0,
30,
150,
or
300
mg/
kg/
day
from
days
6
through
18
of
gestation.
No
maternal
or
developmental
toxicity
was
observed
at
30
mg/
kg/
day.
At
150
mg/
kg/
day,
maternal
toxicity
was
characterized
by
abortion
(
5%)
and
clinical
signs
such
as
ataxia,
rales,
decreased
motor
activity.
At
300
mg/
kg/
day
maternal
toxicity
was
manifested
by
abortions
(
20%),
clinical
signs,
decreased
body
weight
and
body
weight
gain
and
food
consumption.
Developmental
toxicity
at
300
mg/
kg/
day
was
manifested
by
irregular
ossification
of
the
nasal
bones
of
the
skull.
At
150
mg/
kg/
day,
increased
incidence
of
abortion
was
observed
and
was
considered
developmental
toxicity.
In
a
range­
finding
study,
NZW
rabbits
were
dosed
at
0,
62.5,
125,
250,
or
500
mg/
kg/
day
from
days
6
through
18
of
gestation.
No
maternal
or
developmental
toxicity
was
observed
at
62.5
mg/
kg/
day.
Treatment­
related
maternal
toxicity
was
manifested
by
mortality,
increased
resorptions
and
reduction
in
the
litter
size
at
500
mg/
kg/
day.
Clinical
signs
occurred
at
125,
250,
and
500
mg/
kg/
day.
Cesarean
sections
revealed
no
treatment­
related
differences
between
treated
and
control
groups,
and
no
external
malformation
or
variations
were
seen
in
any
of
the
fetuses
of
the
treated
does.
Based
on
the
results
of
these
studies,
the
NOAEL
for
maternal
toxicity
was
62.5
mg/
kg/
day
and
the
LOAEL
was
150
mg/
kg/
day
based
on
increased
incidences
of
abortion
and
clinical
signs
(
i.
e.,
decreased
motor
activity,
ataxia).
For
developmental
toxicity,
the
NOAEL
was
62.5
mg/
kg/
day
and
the
LOAEL
was
150
mg/
kg/
day
based
on
increased
incidence
of
abortion.
This
study
is
classified
acceptable/
guideline
(
OPPTS
870.3700b;
OECD
414)
and
satisfies
the
requirements
for
a
developmental
toxicity
study
in
the
rabbit.

3.3.4
Reproductive
Toxicity
Study
Dicamba
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­
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In
a
two­
generation
reproduction
study
(
MRID
43137101),
Sprague­
Dawley
rats
(
32
or
28/
group)
received
dicamba
technical
(
86.5%)
in
the
diet
at
dose
levels
of
0,
500,
1500,
or
5000
ppm
(
0,
40,
122,
or
419
mg/
kg/
day
for
males
and
0,
45,
136
or
450
mg/
kg/
day
for
females,
respectively)
for
two
generations.
Systemic
toxicity
was
observed
at
5000
ppm,
manifested
as
clinical
signs
in
dams
from
both
generations
during
lactation
(
tense/
stiff
body
tone
and
slow
righting
reflex)
and
significantly
increased
relative
liver
to
body
weights
(
112%
of
control)
in
both
generations
and
sexes,
adults
as
well
as
weanlings.
The
increase
(
107%)
in
relative
kidney
weights
observed
at
1500
and/
or
5000
ppm
were
not
considered
to
be
toxicologically
significant
due
to
lack
of
corroborative
gross
or
histopathological
lesions
in
the
kidneys.
Sexual
maturation
among
male
pups
in
the
F1
generation
was
significantly
delayed
at
5000
ppm.
Similar
effects
were
not
seen
in
females.
Significantly
decreased
pup
body
weights
were
observed
in
all
generations
and
matings
at
1500
ppm
(
86
­
90%
of
control)
and
at
5000
ppm
(
74
­
94%
of
control)
throughout
lactation.
For
parental
systemic
toxicity,
the
NOAEL
was
122
and
136
mg/
kg/
day
for
males
and
females,
respectively,
and
the
LOAEL
was
419
and
450
mg/
kg/
day
in
males
and
females
based
on
clinical
signs
of
neurotoxicity.
For
reproductive
toxicity,
the
NOAEL
was
122
mg/
kg/
day
and
the
LOAEL
was
419
mg/
kg/
day
based
on
delayed
sexual
maturation
in
F
1
males.
For
offspring
toxicity,
the
NOAEL
was
45
mg/
kg/
day
and
the
LOAEL
was
136
mg/
kg/
day
based
on
decreased
pup
body
weight.
This
study
is
classified
as
acceptable/
guideline
and
satisfies
the
guideline
requirements
(
OPPTS
870.3800;
OECD
416)
for
a
two­
generation
reproduction
study
in
the
rat.

3.3.5
Additional
Information
from
Literature
Sources
No
additional
relevant
toxicity
studies
from
published
literature
were
identified.

3.3.6
Pre­
and/
or
Postnatal
Toxicity
3.3.6.1
Determination
of
Susceptibility
There
is
no
evidence
of
increased
qualitative
or
quantitative
susceptibility
following
in
utero
and/
or
pre­
natal
exposure
in
the
developmental
toxicities
in
rats
and
rabbits.
There
was
evidence
of
increased
quantitative
susceptibility
to
the
offspring
following
pre­
and/
or
postnatal
exposure
in
the
two­
generation
reproduction
study
in
rats.
In
that
study,
offspring
toxicity
was
manifested
as
decreased
pup
body
weight
gain
in
all
generations
at
a
dose
lower
than
the
parental
systemic
toxicity
NOAEL.
However,
the
NOAEL
of
45
mg/
kg/
day
identified
in
this
study
was
chosen
for
risk
assessments
for
all
routes
and
exposure
durations
other
than
acute
oral
exposures.
Since
this
NOAEL
is
the
lowest
(
most
sensitive
endpoint)
in
the
dicamba
toxicity
data
base,
and
the
doseresponse
observed
in
the
study
is
well
defined
assuring
that
this
dose
is
a
clear
NOAEL,
use
of
the
NOAEL
and
endpoint
for
risk
assessment
is
protective
for
all
observed
toxic
effects
of
the
chemical.
Therefore,
there
is
low
concern
for
the
increased
susceptibility
observed
in
the
reproduction
study
since
all
appropriate
risk
assessments
utilize
this
endpoint.
Additionally,
there
is
no
increased
susceptibility
observed
in
the
developmental
toxicity
studies.
Since
the
most
sensitive
observed
developmental
endpoint
(
increased
incidence
of
abortion)
and
the
associated
NOAEL
was
used
for
acute
dietary
risk
assessment
for
females
of
child­
bearing
age,
the
risk
assessment
is
protective
for
potential
acute
toxicity
to
developing
fetuses.
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3.3.6.2
Degree
of
Concern
Analysis
and
Residual
Uncertainties
The
degree
of
concern
is
low
for
the
quantitative
susceptibility
because
the
risk
assessment
was
based
on
the
most
sensitive
endpoint
with
a
definitive
NOAEL.
There
are
no
concern
or
residual
uncertainties
for
pre­
and
postnatal
toxicity.

3.3.7
Recommendation
for
a
Developmental
Neurotoxicity
Study
After
considering
the
available
toxicity
data,
the
risk
assessment
team
determined
that
a
developmental
neurotoxicity
study
(
DNT)
is
not
required
based
on
the
following
reasons:
(
1)
although
clinical
signs
of
neurotoxicity
were
seen
in
pregnant
animals,
no
evidence
of
developmental
anomalies
of
the
fetal
nervous
system
were
observed
in
the
prenatal
developmental
toxicity
studies,
in
either
rats
or
rabbits,
at
maternally
toxic
doses
up
to
300
or
400
mg/
kg/
day,
respectively;
(
2)
there
were
no
evidence
of
behavioral
or
neurological
effects
on
the
offspring
in
the
two­
generation
reproduction
study
in
rats;
(
3)
the
ventricular
dilation
of
the
brain
in
the
chronic
toxicity
study
was
only
observed
in
females
at
the
high
dose
after
two
years
exposure.
The
significance
of
this
observation
is
questionable
since
no
similar
histopathological
finding
was
seen
in
the
subchronic
neurotoxicity
study.

3.4
Safety
Factor
for
Infants
and
Children
3.4.1
Adequacy
of
the
Exposure
Data
Base
The
dietary
exposure
assessment
is
based
on
the
exaggerated
exposure
assumptions,
that
all
crops
consumed
in
the
U.
S.
are
treated,
and
that
the
commodities
bear
tolerance
level
residues.
The
residential
exposure
assessment
assumes
maximum
label
use
rate
as
well
as
other
conservative
assumptions.
Therefore,
the
Agency
does
not
believe
that
exposure
to
dicamba
will
be
underestimated.

3.4.2
Conclusion
Based
on
the
hazard
data,
there
are
no
concerns
and
no
residual
uncertainties
with
regard
to
preand
or
postnatal
toxicity.
In
addition,
the
dicamba
risk
assessment
team
evaluated
the
quality
of
the
exposure
data
and
has
no
residual
uncertainties.
Therefore,
the
team
has
recommended
that
the
special
FQPA
Safety
Factor
be
reduced
to
1x.

3.5
Hazard
Identification
and
Toxicity
Endpoint
Selection
A
summary
of
the
endpoints
and
doses
selected
for
risk
assessment
may
be
found
in
Table
3.4
at
the
end
of
this
section.

3.5.1
Acute
Reference
Dose
(
aRfD)
­
Females
age
13­
49
No
study
was
identified
that
demonstrated
effects
to
the
developing
fetus
as
a
result
of
a
single
exposure
via
the
oral
route.
Therefore,
this
risk
assessment
is
not
required.
Dicamba
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Health
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­
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I
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3.5.2
Acute
Reference
Dose
(
aRfD)
­
General
Population
The
results
of
the
Acute
Neurotoxicity
Study
(
ACN)
in
Rats
(
MRID
No.:
42774104)
were
considered
for
this
endpoint.
A
summary
may
be
found
in
Appendix
A.
The
effects
observed
in
this
study
can
be
attributed
to
a
single
dose
and
is
appropriate
for
all
populations.
Neurotoxicity
was
seen
in
both
sexes
at
the
lowest
dose
tested,
300
mg/
kg/
day.
With
the
exception
of
the
decrease
in
forelimb
grip
strength,
which
persisted
until
day
7,
the
other
neurologic
signs
such
as
impaired
gaits
and
righting
reflex
were
seen
on
the
day
of
dosing.
A
comparison
with
the
rat
developmental
toxicity
study
that
had
similar
clinical
signs
with
a
NOAEL
of
160
mg/
kg/
day
after
10
days
of
treatment
indicates
that
the
NOAEL
for
the
acute
neurotoxicity
study
is
unlikely
to
be
more
than
3­
fold
lower
than
the
LOAEL
(
ACN
LOAEL/
3
=
100
mg/
kg;
rat
developmental
study
NOAEL
=
160
mg/
kg).
Therefore,
it
was
determined
that
an
uncertainty
factor
of
3
for
extrapolation
of
LOAEL
to
NOAEL
was
adequate.
The
total
uncertainty
factor
is
300x,
10x
for
interspecies
extrapolation,
10x
for
intraspecies
variations,
and
3x
for
using
a
LOAEL.
The
acute
population
adjusted
dose
for
the
general
population
is
equal
to
the
acute
reference
dose
and
is
1.0
mg/
kg/
day.

3.5.3
Chronic
Reference
Dose
(
cRfD)

The
Multi­
generation
Reproduction
Study
in
Rats
(
MRID
No.:
43137101)
was
used
for
establishing
the
chronic
reference
dose.
The
selected
dose
and
endpoints
are
appropriate
for
the
route
and
duration
of
exposure
and
is
protective
of
the
general
population.
A
summary
of
this
study
may
found
in
Section
3.3.4.
The
NOAEL
for
offspring
toxicity
was
45
mg/
kg/
day
based
upon
the
impaired
pup
growth
(
decreased
pup
weights)
at
136
mg/
kg/
day
(
LOAEL).
An
uncertainty
factor
of
100x
is
to
be
applied
including
10x
for
interspecies
extrapolation
and
10x
for
intraspecies
variations.
The
chronic
population
adjusted
dose
(
cPAD)
is
equal
to
the
chronic
reference
dose
and
is
0.45
mg/
kg/
day.

3.5.4
Incidental
Oral
Exposure
(
Short
and
Intermediate
Term)

The
Multi­
generation
Reproduction
Study
in
Rats
(
MRID
No.:
43137101)
was
selected
for
this
risk
assessment.
This
study
is
of
the
appropriate
route
and
duration
of
exposure,
since
effects
in
the
pups
were
seen
on
lactation
day
21
in
both
F
2
litters
and
is
protective
of
the
population
of
concern
(
infants
and
children).
A
summary
of
this
study
may
found
in
Section
3.3.4.
The
NOAEL
for
offspring
toxicity
was
45
mg/
kg/
day
based
upon
the
impaired
pup
growth
(
decreased
pup
weights)
at
136
mg/
kg/
day
(
LOAEL).
An
uncertainty
factor
of
100x
is
to
be
applied
including
10x
for
interspecies
extrapolation
and
10x
for
intraspecies
variations.
The
chronic
population
adjusted
dose
(
cPAD)
is
equal
to
the
chronic
reference
dose
and
is
0.45
mg/
kg/
day.

3.5.5
Dermal
Absorption
A
dermal
absorption
study
is
not
available.
An
upper­
bound
estimate
of
dermal
absorption
was
estimated
using
the
NOAEL
of
1000
mg/
kg/
day
in
the
21­
day
dermal
toxicity
rabbit
study
and
the
LOAEL
of
150
mg/
kg/
day
in
the
rabbit
oral
developmental
study.

150
x
100
=
15
%
dermal
absorption
factor
1000
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3.5.6
Dermal
Exposure
The
Multi­
generation
Reproduction
Study
in
Rats
(
MRID
No.:
43137101)
was
selected
for
this
endpoint.
A
summary
of
this
study
may
found
in
Section
3.3.4.
Although
a
rat
28­
day
dermal
toxicity
study
was
available
which
showing
no
systemic
toxicity
at
the
highest
dose
tested
of
1000
mg/
kg/
day,
this
dermal
study
did
not
assess
reproductive
and
offspring
effects.
Offspring
toxicity
in
the
rat
oral
multi­
generation
reproduction
study
was
noted
below
dosages
where
parental
toxicity
was
evident.
In
order
to
be
protective
of
these
effects
in
the
absence
of
any
route­
specific
data,
the
reproduction
study
was
chosen
for
all
time
periods
of
exposure,
including
short­
term,
since
effects
in
the
pups
were
seen
on
lactation
day
21
in
both
F
2
litters.
Since
an
oral
NOAEL
was
selected,
15%
dermal
absorption
factor
should
be
used
for
route­
to­
route
extrapolation.
The
NOAEL
for
offspring
toxicity
was
45
mg/
kg/
day
based
upon
the
impaired
pup
growth
(
decreased
pup
weights)
at
136
mg/
kg/
day
(
LOAEL).

3.5.7
Inhalation
Exposure
The
Multi­
generation
Reproduction
Study
in
Rats
(
MRID
No.:
43137101)
was
used
for
selecting
this
endpoint.
A
summary
of
this
study
may
found
in
Section
3.3.4.
In
the
absence
of
a
repeated
exposure
inhalation
study,
an
oral
study
is
employed.
Inhalation
absorption
is
assumed
to
be
equivalent
to
oral
(
i.
e.,
100%).
The
NOAEL
for
offspring
toxicity
was
45
mg/
kg/
day
based
upon
the
impaired
pup
growth
(
decreased
pup
weights)
at
136
mg/
kg/
day
(
LOAEL).

3.5.8
Level
of
Concern
for
Margin
of
Exposure
The
levels
of
concern
for
occupational
and
residential
exposures
are
summarized
in
Table
3.3.
For
Occupational
Exposure
a
margin
of
exposure
(
MOE)
MOE
of
100
is
required
for
short­,
intermediate­,
and
long­
term
occupational
risk
assessments
for
both
dermal
and
inhalation
routes
of
exposure.
The
MOEs
for
dermal
and
inhalation
exposures
may
be
combined
for
occupational
exposure
risk
assessment
because
the
toxicity
endpoints
for
these
routes
of
exposure
are
the
same.
For
Residential
Exposure
a
margin
of
exposure
(
MOE)
of
100
is
required
for
short­,
intermediate­,
and
long­
term
residential
risk
assessments
for
both
dermal
and
inhalation
routes
of
exposure,
and
an
MOE
of
300
is
required
for
acute
exposures.
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Table
3.3.
Summary
of
Target
Margins
of
Exposure
(
MOEs)
for
Risk
Assessment
Route
Duration
Acute
(
1
day)
Short­
Term
(
1­
30
Days)
Intermediate­
Term
(
1
­
6
Months)
Long­
Term
(>
6
Months)

Occupational
(
Worker)
Exposure
Dermal
NA
100
100
100
Inhalation
NA
100
100
100
Residential
(
Non­
Dietary)
Exposure
Oral
300
100
100
N/
A
Dermal
300
100
100
100
Inhalation
300
100
100
100
N/
A
=
Not
Applicable
3.5.9
Recommendation
for
Aggregate
Exposure
Risk
Assessments
A
common
toxicological
endpoint
(
decreased
pup
growth)
of
concern
was
identified
for
the
short­,
intermediate­
and
long­
term
durations
via
the
oral,
dermal
(
oral
equivalent)
and
inhalation
(
oral
equivalent)
routes.
Therefore,
the
aggregate
exposure
risk
assessment
should
include
oral,
dermal
and
inhalation
routes
appropriate
to
the
population
of
concern.

3.5.10
Classification
of
Carcinogenic
Potential
In
accordance
with
the
EPA
Final
Guidelines
for
Carcinogen
Risk
Assessment
(
March
29,
2005),
dicamba
is
classified
as
"
Not
Likely
to
be
Carcinogenic
to
Humans".
This
was
based
on
negative
cancer
studies
in
rats
and
mice
which
were
tested
at
adequate
dose
levels
to
assess
the
carcinogenicity
of
dicamba
(
TXR
No.
0053647).
A
detailed
discussion
of
the
carcinogenicity
studies
may
be
found
in
Appendix
A
of
this
document.
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Table
3.4
Summary
of
Toxicology
Endpoint
Selection
for
Dicamba
Exposure
Scenario
Dose
Used
in
Risk
Assessment,
UF
Special
FQPA
SF*
and
Level
of
Concern
for
Risk
Assessment
Study
and
Toxicological
Effects
Acute
Dietary
(
General
population
including
infants
and
children
LOAEL
=
300
mg/
kg/
day
UF
=
300
Acute
RfD
=
1
mg/
kg/
day
FQPA
SF
=
1X
aPAD
=
acute
RfD
FQPA
SF
=
1.0
mg/
kg/
day
Acute
Neurotoxicity
Study
in
Rats
LOAEL
=
300
mg/
kg/
day
(
LDT)
based
on
clinical
signs
of
neurotoxicity.

Chronic
Dietary
(
All
populations)
NOAEL=
45
mg/
kg/
day
UF
=
100
Chronic
RfD
=
0.45
mg/
kg/
day
FQPA
SF
=
1X
cPAD
=
chronic
RfD
FQPA
SF
=
0.45
mg/
kg/
day
Multi­
generation
Reproduction
Study
in
Rats
LOAEL=
136
mg/
kg/
day
based
on
impaired
pup
growth
(
decreased
pup
weights).

Short­
Term
Incidental
Oral
(
1
­
30
Days)
Oral
NOAEL=
45
mg/
kg/
day
Residential
LOC
for
MOE
=
100
Multi­
generation
Reproduction
Study
in
Rats
See
above
section
Intermediate­
Term
Incidental
Oral
(
1
­
6
Months)
Oral
NOAEL=
45
mg/
kg/
day
Residential
LOC
for
MOE
=
100
Multi­
generation
Reproduction
Study
in
Rats
See
above
section
Short­
Term
Dermal
(
1
­
30
days)
Oral
NOAEL=
45
mg/
kg/
day
(
Dermal
absorption
rate
=
15%)
Residential
LOC
for
MOE
=
100
Occupational
LOC
for
MOE
=
100
Multi­
generation
Reproduction
Study
in
Rats
See
above
section
Intermediate­
Term
Dermal
(
1
­
6
Months)
Oral
NOAEL=
45
mg/
kg/
day
(
Dermal
absorption
rate
=
15%)
Residential
LOC
for
MOE
=
100
Occupational
LOC
for
MOE
=
100
Multi­
generation
Reproduction
Study
in
Rats
See
above
section
Long­
Term
Dermal
(>
6
Months)
Oral
NOAEL=
45
mg/
kg/
day
(
Dermal
absorption
rate=
15%)
Residential
LOC
for
MOE
=
100
Occupational
LOC
for
MOE
=
100
Multi­
generation
Reproduction
Study
in
Rats
See
above
section
Short­
Term
Inhalation
(
1
­
30
days)
Oral
NOAEL=
45
mg/
kg/
day
(
Inhalation
absorption
rate=
100%)
Residential
LOC
for
MOE
=
100
Occupational
LOC
for
MOE
=
100
Multi­
generation
Reproduction
Study
in
Rats
See
above
section
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3.4
Summary
of
Toxicology
Endpoint
Selection
for
Dicamba
Exposure
Scenario
Dose
Used
in
Risk
Assessment,
UF
Special
FQPA
SF*
and
Level
of
Concern
for
Risk
Assessment
Study
and
Toxicological
Effects
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24
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Intermediate­
Term
Inhalation
(
1
­
6
Months)
Oral
NOAEL=
45
mg/
kg/
day
(
Inhalation
absorption
rate=
100%)
Residential
LOC
for
MOE
=
100
Occupational
LOC
for
MOE
=
100
Multi­
generation
Reproduction
Study
in
Rats
See
above
section
Long­
Term
Inhalation
(>
6
Months)
Oral
NOAEL=
45
mg/
kg/
day
(
Inhalation
absorption
rate=
100%)
Residential
LOC
for
MOE
=
100
Occupational
LOC
for
MOE
=
100
Multi­
generation
Reproduction
Study
in
Rats
See
above
section
Cancer
(
Oral,
dermal,
inhalation)
Not
Likely
to
be
Carcinogenic
to
human.

3.6
Endocrine
disruption
EPA
is
required
under
the
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."
Following
recommendations
of
its
Endocrine
Disruptor
and
Testing
Advisory
Committee
(
EDSTAC),
EPA
determined
that
there
was
a
scientific
basis
for
including,
as
part
of
the
program,
the
androgen
and
thyroid
hormone
systems,
in
addition
to
the
estrogen
hormone
system.
EPA
also
adopted
EDSTAC's
recommendation
that
the
Program
include
evaluations
of
potential
effects
in
wildlife.
For
pesticide
chemicals,
EPA
will
use
FIFRA
and,
to
the
extent
that
effects
in
wildlife
may
help
determine
whether
a
substance
may
have
an
effect
in
humans,
FFDCA
authority
to
require
the
wildlife
evaluations.
As
the
science
develops
and
resources
allow,
screening
of
additional
hormone
systems
may
be
added
to
the
Endocrine
Disruptor
Screening
Program
(
EDSP).
While
delayed
sexual
maturation
in
females
was
observed
in
the
rat
reproduction
study,
no
effects
clearly
related
to
endocrine
disruption
were
seen
in
the
toxicity
data
base.

When
additional
appropriate
screening
and/
or
testing
protocols
being
considered
under
the
Agency's
EDSP
have
been
developed,
dicamba
may
be
subjected
to
further
screening
and/
or
testing
to
better
characterize
effects
related
to
endocrine
disruption.

4.0
Public
Health
and
Pesticide
Epidemiology
Data
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4.1
Incident
Reports
The
OPP
Incident
Data
System
(
IDS),
California
Department
of
Pesticide
Regulation,
National
Pesticide
Information
Center
(
NPIC),
National
Institute
of
Occupational
Safety
and
Health's
Sentinel
Event
Notification
System
for
Occupational
Risks
(
NIOSH
SENSOR),
and
Poison
Control
Centers
were
reviewed
for
adverse
incidents
as
a
result
of
dicamba
exposure.
Dicamba
is
rarely
used
as
a
herbicide
by
itself.
Most
often
it
is
mixed
with
other
ingredients,
particularly
other
chlorophenoxy
herbicides,
such
as
2,4­
D.
Consequently,
most
incidents
involving
dicamba
exposure
also
involved
exposure
to
other
pesticides
as
well.
There
were
too
few
reports
of
ill
effects
from
exposure
to
Dicamba
in
the
available
data
bases
to
draw
conclusions
about
likely
effects.
Reigart
and
Roberts
(
1999)
state
that
dicamba
can
be
moderately
irritating
to
skin
and
respiratory
tract.
This
is
consistent
with
reported
symptoms
from
Poison
Control
Centers.

4.2
Other
Pesticide
Epidemiology
Published
Literature
Two
epidemiology
studies
evaluated
pesticides
and
non­
Hodgkin's
lymphoma
(
NHL).
One
study
examined
residential
use
and
concluded
there
was
"
no
detectable
excess
associated
with
residential
exposures"
which,
for
dicamba,
were
more
prevalent
in
controls
than
cases.
The
second
study
was
a
multicenter
population­
based
incidence
study.
In
the
multivariate
model
which
included
exposure
to
other
major
pesticides,
history
of
cancer
in
the
case
or
relatives
to
the
case
subject,
there
was
a
twofold
risk
for
dicamba
mixtures
(
odds
ratio
=
1.96;
95%
confidence
interval
1.40­
2.75)
and
similar
risks
were
seen
for
mecoprop
and
aldrin.
The
authors
concluded
that
"
In
our
final
models,
NHL
was
associated
with
a
personal
history
of
cancer;
a
history
of
cancer
in
first­
degree
relatives;
and
exposure
to
dicamba­
containing
herbicides,
to
mecoprop,
and
to
aldrin."
The
Health
Effects
Division
concludes
that
this
study
suggests
that
dicamba
may
be
associated
with
NHL,
but
that
the
evidence
for
this
association
is
not
strong
enough
to
identify
dicamba
as
a
likely
or
probable
cause
of
NHL.
The
Agricultural
Health
Study
is
planning
to
assess
NHL
in
the
next
year;
further
assessment
that
will
permit
a
more
definitive
conclusion
concerning
dicamba
will
be
available
at
that
time.

5.0
Dietary
Exposure/
Risk
Characterization
5.1
Pesticide
Metabolism
and
Environmental
Degradation
5.1.1
Metabolism
in
Primary
Crops
The
nature
of
the
residue
in
plants
is
adequately
understood
based
on
the
aggregate
of
metabolism
studies
conducted
on
several
crops.
The
results
of
these
studies
indicate
that
dicamba
is
rapidly
absorbed
and
translocated
by
grasses,
grapes,
black
valentine
beans,
wheat,
bluegrass,
and
soybeans.
It
is
also
rapidly
absorbed
by
sugarcane
following
foliar
application
but
it
is
very
slowly
translocated
from
the
leaves
to
the
roots.
The
metabolism
of
dicamba
in
plants
proceeds
mainly
by
demethylation
and
hydroxylation.
Major
metabolites
found
include
3,6­
dichloro­
5­
hydroxybenzoic
acid
(
5­
OH
dicamba)
metabolite
and
3,6­
dichloro­
2­
hydroxybenzoic
acid
metabolite,
also
referred
to
as
3,6­
dichlorosalicylic
acid
(
DCSA).
The
chemical
names
and
structures
of
dicamba
and
its
regulated
metabolites
are
depicted
below
in
Table
5.1.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
26
of
70
Cl
Cl
OCH
3
OH
O
Cl
Cl
OCH
3
O
OH
O
H
Cl
Cl
O
OH
OH
Table
5.1.
Chemical
names
and
structures
of
dicamba
and
its
metabolites.

Dicamba
(
3,6­
dichloro­
o­
anisic
acid)
5­
hydroxy
dicamba
(
3,6­
dichloro­
5­
hydroxy­
o­
anisic
acid)
DCSA
(
3,6­
dichloro­
2­
hydroxybenzoic
acid
or
3,6­
dichlorosalicylic
acid)

The
8/
12/
83
Residue
Chemistry
Chapter
of
the
Dicamba
Registration
Standard
and
the
6/
30/
89
Residue
Chemistry
Chapter
of
the
Dicamba
(
SRR)
Registration
Standard
concluded
that
the
major
residues
found
in
barley,
corn,
cotton,
grasses,
oat,
proso
millet,
sorghum,
sugarcane,
and
wheat
are
dicamba
and
its
3,6­
dichloro­
5­
hydroxybenzoic
acid
(
5­
OH
dicamba)
metabolite.
It
also
concluded
that
in
asparagus,
the
residues
of
concern
are
dicamba
and
DCSA
and
in
aspirated
grain
fractions
and
soybeans
the
residues
of
concern
are
dicamba,
5­
OH
dicamba,
and
DCSA.

No
new
data
are
available
or
required.
HED
concludes
that
these
residues
are
appropriate
for
the
tolerance
expression
and
risk
assessment.

5.1.2
Metabolism
in
Rotational
Crops
The
nature
of
the
residue
in
rotational
crops
is
understood.
The
results
of
an
acceptable
confined
rotational
crop
study
showed
that
at
a
plantback
interval
of
120
days,
the
total
radioactive
residues
were
<
0.01
ppm
in/
on
samples
of
collard
greens
(
a
representative
of
leafy
vegetables)
and
carrots
(
a
representative
of
root
crops)
but
were
>
0.01
ppm
in
the
matrices
of
barley
(
a
representative
of
small
grains).
Residue
characterization
of
barley
matrices
from
the
120­
day
rotation
showed
that
a
relatively
high
percentage
of
TRR
was
associated
with
natural
plant
constituents
(
lignin
and
cellulose).
Therefore,
tolerances
are
not
required
for
rotational
crops.

5.1.3
Metabolism
in
Livestock
The
nature
of
the
residue
in
animals
is
adequately
understood
based
on
acceptable
metabolism
studies
conducted
on
ruminants
and
poultry.
The
compounds
identified
in
these
studies
include
dicamba,
3,6­
dichlorosalicylic
acid
(
DCSA)
and
2­
amino­
3,6­
dichlorophenol.

In
a
ruminant
metabolism
study,
dicamba
per
se,
accounting
for
63.28­
92.82%
of
the
TRR,
was
detected
in
kidney,
liver,
and
fat.
The
metabolite
DCSA
was
a
major
metabolite
in
kidney
(
10.55%
TRR;
0.0057
ppm)
and
liver
(
11.77%
TRR;
0.0017
ppm)
and
only
a
minor
component
in
fat
(
1.23%
TRR;
0.0001
ppm).
An
unknown,
accounting
for
<
10%
of
the
TRR
was
detected
in
liver.
A
trace
(
0.006%
TRR)
of
5­
OH
dicamba
(
a
plant
dicamba
metabolite)
was
detected
in
urine.
Dicamba
metabolism
in
ruminants
is
proposed
by
the
registrant
to
proceed
via
formation
of
DCSA
or
5­
OH
dicamba.
Dicamba
Human
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­
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I
Barcode:
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27
of
70
In
a
poultry
metabolism
study
conducted
at
twice
the
maximum
theoretical
dietary
burden
dicamba
per
se
accounted
for
61.16%
and
95.25%
of
the
TRR
in
liver
and
eggs,
respectively.
The
metabolite
2­
amino­
3,6­
dichlorophenol
(
2A36DCP)
was
detected
in
liver
(
35.76%
TRR;,
0.001
ppm)
but
not
in
eggs.
The
metabolites
DCSA
and
5­
OH
dicamba
were
not
detected
in
liver
or
eggs
but
were
detected
in
excreta
and
together
accounted
for
<
3%
of
the
TRR.
Dicamba
metabolism
in
poultry
is
proposed
by
the
registrant
to
proceed
via
formation
of
DCSA
subsequently
followed
by
formation
of
2A36DCP.

HED
does
not
anticipate
the
occurrence
of
quantifiable
residues
of
dicamba
or
DCSA
in
poultry
eggs
and
meat
as
a
result
of
treating
crops
which
are
poultry
feed
items
with
use
patterns
likely
to
result
in
the
highest
residues.
Therefore,
HED
concludes
that
tolerances
are
not
needed
in
poultry
eggs
and
meat
at
this
time
but
may
be
required
if
additional
uses
are
registered
in
the
future.

5.1.4
Analytical
Methodology
There
are
adequate
plant
enforcement
methods.
The
Pesticide
Analytical
Manual
(
PAM)
Vol.
II
lists
Method
I
(
AM
0268A),
a
GC
method
with
electron
capture
detection
(
GC/
ECD)
for
the
enforcement
of
dicamba
plant
tolerances.
The
sensitivity
of
the
method
is
listed
at
0.05
ppm
and
can
determine
residues
of
dicamba,
5­
hydroxy­
dicamba,
and
DCSA.
For
the
enforcement
of
animal
commodity
tolerances,
PAM
Vol.
II
lists
Method
II,
a
GC/
ECD
method
which
is
identical
to
Method
I.
The
sensitivity
of
the
method
is
listed
at
0.01
ppm.
Based
on
the
results
of
animal
metabolism
study,
which
showed
that
acid
hydrolysis
can
additionally
extract
up
to
30%
of
TRR
in
goat
liver,
HED
is
requiring
the
registrants
to
revise/
improve
Method
II
to
include
an
acid
hydrolysis
step
and
submit
additional
validation
data.
Method
II
should
also
be
re­
written
specifically
for
the
analysis
of
the
parent
dicamba
and
its
metabolite
3,6­
dichloro­
2­
hydroxybenzoic
acid
metabolite
in
animal
matrices.

According
to
FDA's
PAM
Volume
I,
Appendix
II,
dicamba
is
completely
recovered
using
Section
402
E2
of
Protocol
B
but
is
only
partially
recovered
using
Section
402
E1
of
Protocol
B.
There
are
no
multiresidue
methods
recovery
data
for
the
dicamba
metabolites
of
concern
(
5­
OH
dicamba
and
DCSA),
and
these
data
are
required.

5.1.5
Environmental
Degradation
Aerobic
soil
metabolism
is
the
main
degradative
process
for
dicamba.
A
single
observed
half­
life
for
dicamba
was
six
days,
with
formation
of
the
intermediate
non­
persistent
degradate
DCSA.
DCSA
degraded
at
roughly
the
same
rate
as
dicamba;
the
final
metabolites
were
carbon
dioxide
and
microbial
biomass.
Dicamba
is
stable
to
abiotic
hydrolysis
at
all
pH's
and
photodegrades
slowly
in
water
and
on
soil.
Dicamba
is
more
persistent
under
anaerobic
soil:
water
systems
in
the
laboratory,
with
a
half­
life
of
141
days.
The
major
degradate
under
anaerobic
conditions
was
DCSA,
which
was
persistent,
comprising
>
60%
of
the
applied
after
365
days
of
anaerobic
incubation.
No
other
anaerobic
degradates
were
present
at
>
10%
during
the
incubation.
There
are
no
acceptable
data
for
the
aerobic
aquatic
metabolism
of
dicamba;
supplemental
information
indicates
that
dicamba
degrades
more
rapidly
in
aquatic
systems
when
sediment
is
present.

Dicamba
is
very
soluble
in
water
and
very
mobile,
based
on
laboratory
studies.
Because
dicamba
is
not
persistent
under
aerobic
conditions,
very
little
dicamba
could
be
expected
to
leach
to
Dicamba
Human
Health
Risk
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­
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Barcode:
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of
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groundwater.
If
any
dicamba
did
reach
anaerobic
ground
water,
it
would
be
somewhat
persistent
(
due
to
its
anaerobic
half­
life
of
141
days);
any
DCSA
that
reached
ground
water
would
be
expected
to
persist.
Results
from
two
acceptable
field
dissipation
studies
conducted
with
dimethylamine
salt
of
dicamba,
indicated
that
dicamba
dissipated
with
a
half­
life
range
of
4.4
to
19.8
days.
The
DCSA
was
the
major
degradate
in
both
studies.
Both,
dicamba
and
its
degradate
(
DCSA)
were
found
in
soil
segments
deeper
than
10
cm.

5.1.6
Comparative
Metabolic
Profile
Metabolism
in
rats
appears
to
be
less
extensive
than
that
observed
in
the
plant
and
livestock
metabolism
studies.
In
the
rats
study
rapid
absorption
of
dicamba
was
observed,
but
minimal
metabolism
was
observed
as
more
than
95%
of
the
dosing
material
was
recovered
as
dicamba.
Dicamba
metabolism
in
ruminants
is
proposed
by
the
registrant
to
proceed
via
formation
of
DCSA
or
5­
OH
dicamba.
Dicamba
metabolism
in
poultry
is
proposed
by
the
registrant
to
proceed
via
formation
of
DCSA
subsequently
followed
by
formation
of
2A36DCP.
DCSA
and
5­
OH­
dicamba
were
major
plant
metabolites,
and
DCSA
was
the
only
significant
environmental
degradate
that
could
potentially
be
found
in
drinking
water.

5.1.7
Pesticide
Metabolites
and
Degradates
of
Concern
A
summary
of
dicamba
metabolites
and
environmental
degradates
to
be
included
in
the
dietary
risk
assessment
and
tolerance
expression
may
be
found
in
Table
5.2.
DCSA
and
5­
OH­
dicamba
are
major
metabolites,
and
in
the
case
of
DCSA,
a
major
degradate
that
could
potentially
be
found
in
drinking
water.
Specific
toxicity
data
are
not
available
for
either
of
these
compounds.
Based
on
their
structural
similarity
to
the
parent,
the
risk
assessment
team
has
concluded
that
they
may
have
similar
toxicity
as
the
parent,
and
should
be
included
in
the
dietary
risk
assessment.

Table
5.2
Summary
of
Dicamba
Metabolites
and
Degradates
to
be
included
in
the
Risk
Assessment
and
Tolerance
Expression
1
Matrix
Residues
included
in
Risk
Assessment
Residues
included
in
Tolerance
Expression
Plants
Primary
Crop
­
Most
grains
Dicamba
and
5­
OH
Dicamba
Dicamba
and
5­
OH
Dicamba
Primary
Crop
­
Asparagus
Dicamba
and
DCSA
Dicamba
and
DCSA
Primary
Crop
­
Soybean
and
Aspirated
Grain
Fractions
Dicamba,
DCSA,
and
5­
OH
Dicamba
Dicamba,
DCSA,
and
5­
OH
Dicamba
Rotational
Crop
Not
Required
2
Not
Required
2
Livestock
Ruminant
Dicamba
and
DCSA
Dicamba
and
DCSA
Poultry
Not
Required
Not
Required
Dicamba
Human
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­
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Table
5.2
Summary
of
Dicamba
Metabolites
and
Degradates
to
be
included
in
the
Risk
Assessment
and
Tolerance
Expression
1
Matrix
Residues
included
in
Risk
Assessment
Residues
included
in
Tolerance
Expression
Page
29
of
70
Drinking
Water
Dicamba
and
DCSA
Not
Applicable
1
Nomenclature
of
metabolites/
degradates:
3,6­
dichloro­
5­
hydroxybenzoic
acid
=
5­
OH;
3,6­
dichloro­
2­
hydroxybenzoic
acid
=
3,6­
dichlorosalicylic
acid
=
DCSA;
2
Tolerances
and
dietary
risk
assessment
are
not
required
provided
the
registrants
specify
a
120­
day
plantback
interval.

5.1.8
Drinking
Water
Residue
Profile
5.1.8.1
Surface
Water
PRZM­
EXAMS
simulations
were
conducted
for
Dicamba
acid
and
its
degradate
DCSA
use
on
sugarcane
to
evaluate
the
cumulative
probability
distribution
for
peak
and
annual
mean
Estimated
Drinking
Water
Concentrations
(
EDWCs).
A
summary
of
the
EDWCs
may
be
found
in
Table
5.3.

Table
5.3.
Estimated
Drinking
Water
Concentrations
to
Be
Used
for
Exposure
to
Dicamba
Acid,
and
its
Degradate
Dichlorosalicylic
Acid
(
DCSA)
in
Drinking
Water
Crop
Model
EDWCs
(:
g/
L)

Dicamba
DCSA
Acute
One­
in­
10­
year
annual
mean
36
year
overall
mean
Acute
One­
in­
10­
year
annual
mean
36
year
overall
mean
Surface
Water
FL­
Sugarcane
(
Ground)
357
13
5.23
10.1
0.75
0.4
FL­
Sugarcane
(
Aerial)
346
12.9
5.38
10.9
0.813
0.47
LA­
Sugarcane
(
Ground)
233
9.74
3.13
8.79
0.66
0.32
LA­
Sugarcane
(
Aerial)
230
9.74
3.44
9.74
0.73
0.39
Note
that
these
estimates
assume
one
application
@
2.8
lb
ai/
A
(
parent);
and
0.446
lb
ai/
A
(
DCSA)
and
a
crop
area
factor
of
0.87.
Dicamba
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5.1.8.2
Ground
Water
SCIGROW
(
Screening
Concentration
in
Ground
Water)
provides
a
groundwater
screening
exposure
value
to
be
used
in
determining
the
potential
risk
to
human
health
from
drinking
water
contaminated
with
the
pesticide.
Since
the
SCIGROW
concentrations
are
likely
to
be
approached
in
only
a
very
small
percentage
of
drinking
water
sources,
i.
e.,
highly
vulnerable
aquifers,
it
is
not
appropriate
to
use
SCIGROW
for
national
or
regional
exposure
estimates.

SCIGROW
estimates
likely
groundwater
concentrations
if
the
pesticide
is
used
at
the
maximum
allowable
rate
in
areas
where
groundwater
is
exceptionally
vulnerable
to
contamination.
In
most
cases,
a
large
majority
of
the
use
area
will
have
groundwater
that
is
less
vulnerable
to
contamination
than
the
areas
used
to
derive
the
SCIGROW
estimate.
The
EDWC
for
dicamba
is
0.016
:
g/
L
and
for
DCSA
is
0.008
:
g/
L.

Monitoring
data
are
available
in
the
Pesticides
in
Ground
Water
Database
[
Hoheisel
et
al.
1991]
for
dicamba
(
3,172
wells
sampled)
and
5­
hydroxy
dicamba
(
87
wells
sampled).
Out
of
the
wells
sampled,
there
were
no
reports
of
residues
greater
than
the
stated
MCL
(
200
µ
g/
L
lifetime).
Detections
were
ranging
from
traces
to
44
ppb.
The
highest
detection
was
for
water
samples
in
IN.
However,
the
detection
limits
are
unknown,
and
it
is
not
known
if
wells
were
sampled
in
areas
where
dicamba
was
used.
The
US
Geological
Survey
National
Water
Quality
Assessment
program
(
NAWQA)
has
analyzed
for
dicamba
in
their
samples
for
surface
and
groundwater.
A
total
of
6614
surface
water
samples
were
collected
between
1993
and
2003
with
201
detections
ranging
from
0.009
to
1.76
ppb.
The
highest
detection
was
for
water
samples
in
FL.
A
total
of
6571
ground
water
samples
were
collected
between
1993
and
2004,
with
149
detections
ranging
from
0.008
to
2.50
ppb.
The
highest
detection
was
for
water
samples
in
GA.
The
major
degradate
for
dicamba,
DCSA
was
not
analyzed
for
by
the
NAWQA.

The
highest
value
found
in
the
Pesticides
in
Ground
Water
Database
is
higher
than
the
modeled
value.
Therefore,
a
scoping
assessment
using
the
highest
monitoring
value
was
conducted.

5.1.9
Food
Residue
Profile
Tolerance­
level
residues
and
100%
crop
treated
were
assumed
for
all
crops
in
this
assessment.
If
sufficient
data
were
available
to
reassess
tolerances,
then
the
reassessed
values
were
used.
The
established
values
were
used
for
most
commodities
with
the
exception
of
the
livestock
commodities
and
sorghum.
All
processing
factors
were
assumed
to
be
1,
though
the
available
processing
data
suggest
that
residue
concentrations
are
reduced
upon
processing.
The
tolerance
reassessment
summary
may
found
in
Appendix
C
of
this
document.

5.1.10
International
Residue
Limits
No
Codex
MRLs
have
been
established
for
dicamba;
therefore,
issues
of
compatibility
between
Codex
MRLs
and
U.
S.
tolerances
do
not
exist.
Compatibility
cannot
be
achieved
with
the
Canadian
negligible
residue
limits
or
with
Mexican
MRLs
because
these
levels
are
expressed
in
terms
of
parent
compound
only.
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5.2
Dietary
Exposure
and
Risk
Acute
and
chronic
dietary
risk
assessments
were
conducted
using
the
Dietary
Exposure
Evaluation
Model
(
DEEM­
FCID
 
,
Version
2.03),
which
uses
food
consumption
data
from
the
USDA's
Continuing
Surveys
of
Food
Intakes
by
Individuals
(
CSFII)
from
1994­
1996
and
1998.
The
analyses
were
performed
to
support
the
reregistration
eligibility
decision
­
Phase
I.
Results
of
the
analyses
for
food
alone
may
be
found
in
Table
5.4
and
for
food
and
drinking
water
from
surface
water
sources
may
be
found
in
Table
5.5.
The
latter
table
also
includes
a
scoping
assessment
for
chronic
dietary
exposures
using
the
highest
value
found
in
the
Pesticides
in
Ground
Water
database.

Table
5.4.
Summary
of
Dietary
Exposure
and
Risk
for
Dicamba
­
Food
Only
Population
Subgroup*
Acute
Dietary
(
95th
Percentile)
Chronic
Dietary
Dietary
Exposure
(
mg/
kg/
day)
%
aPAD*
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD*

General
U.
S.
Population
0.0297
3.0
0.0115
2.6
All
Infants
(<
1
year
old)
0.0516
5.2
0.0189
4.2
Children
1­
2
years
old
0.0536
5.4
0.0292
6.5
Children
3­
5
years
old
0.0483
4.8
0.0266
5.9
Children
6­
12
years
old
0.0354
3.5
0.0182
4.1
Youth
13­
19
years
old
0.0233
2.3
0.0111
2.5
Adults
20­
49
years
old
0.0214
2.1
0.00946
2.1
Adults
50+
years
old
0.0150
1.5
0.00721
1.6
Females
13­
49
years
old
0.0180
2.9
0.00843
1.9
*
The
population
subgroup
that
has
the
most
exposure
is
bolded.

Table
5.5.
Summary
of
Dietary
Exposure
and
Risk
for
Dicamba
­
Food
and
Water
Population
Subgroup*
Acute
Dietary
(
95th
Percentile)
Chronic
Dietary
­
Surface
Water
Chronic
Dietary
­
Ground
Water
Dietary
Exposure
(
mg/
kg/
day)
%
aPAD*
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD*
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD*

General
U.
S.
Population
0.0435
4.4
0.0118
2.6
0.0124
2.7
All
Infants
(<
1
year
old)
0.108
11
0.0199
4.4
0.0217
4.8
Children
1­
2
years
old
0.0756
7.6
0.0297
6.6
0.030
6.8
Children
3­
5
years
old
0.0675
6.8
0.0270
6.0
0.0278
6.2
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Table
5.5.
Summary
of
Dietary
Exposure
and
Risk
for
Dicamba
­
Food
and
Water
Population
Subgroup*
Acute
Dietary
(
95th
Percentile)
Chronic
Dietary
­
Surface
Water
Chronic
Dietary
­
Ground
Water
Dietary
Exposure
(
mg/
kg/
day)
%
aPAD*
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD*
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD*

Page
32
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Children
6­
12
years
old
0.0476
4.8
0.0185
4.1
0.019
4.2
Youth
13­
19
years
old
0.0318
3.2
0.0113
2.5
0.0117
2.6
Adults
20­
49
years
old
0.0341
3.4
0.00973
2.2
0.0102
2.3
Adults
50+
years
old
0.0267
2.7
0.00750
1.7
0.00804
1.8
Females
13­
49
years
old
0.0312
3.1
0.00870
1.9
0.00922
2.0
*
The
population
subgroup
that
has
the
most
exposure
is
bolded.

Estimated
exposure
to
dicamba
and
its
residues
of
concern
for
all
population
sub­
groups
are
all
well
below
the
level
of
concern.
The
most
highly
exposed
subgroup
for
both
acute
and
chronic
exposure
is
children,
aged
1­
2.
Acute
exposures
are
at
5.4
and
7.6%
of
the
acute
Population
Adjusted
Dose
(
aPAD)
for
food
and
food
plus
water,
respectively.
Chronic
exposures
are
at
6.5,
6.6
and
6.8%
of
the
chronic
Population
Adjusted
Dose
(
cPAD)
for
food,
food
plus
drinking
water
(
from
surface
water
sources),
and
food
plus
drinking
water
(
from
ground
water
sources)
respectively.
When
considering
acute
exposure
in
food
and
water
combined,
the
most
highly
exposed
subgroup
is
infants
with
11%
of
the
aPAD
consumed.

Actual
exposure
is
likely
to
be
considerably
lower.
These
assessments
assume
all
commodities
have
tolerance
level
residues,
but
residues
in
most
field
trials
are
lower.
The
assessments
also
assume
all
crops
are
treated,
but
a
screening
level
usage
analysis
(
M.
Kaul,
9/
20/
04)
indicate
that
the
percent
crop
treated
for
most
commodities
is
less
than
20
%.
Only
drinking
water
from
surface
water
sources
were
considered,
but
the
model
estimates
for
ground
water
are
much
lower
than
surface
water
estimates.

6.0
Residential
(
Non­
Occupational)
Exposure/
Risk
Characterization
According
to
the
EPA
Pesticide
Sales
and
Usage
Report
for
2000/
2001,
dicamba
is
ranked
number
seven
among
the
ten
most
commonly
used
conventional
pesticide
active
ingredients
in
the
home
and
garden
market
sector.

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
herbicides
such
as
2,4­
D
and
MCPP­
p.
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
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spot
treatments
because
the
labels
recommend
repeat
applications
in
two
to
three
weeks
for
hard
to
kill
weeds.

6.1
Residential
Handler
Exposure
and
Risk
Estimates
6.1.1
Residential
Handler
Exposure
Assessment
Scenarios
The
following
scenarios
were
assessed:
1.
Hand
Application
of
Granules
2.
Belly
Grinder
Application
3.
Load/
Apply
Granules
with
a
Broadcast
Spreader
4.
Mix/
Load/
Apply
with
a
Hose­
end
Sprayer
(
Mix
your
own)
5.
Mix/
Load/
Apply
with
a
Hose­
end
Sprayer
(
Ready
to
Use)
6.
Mix/
Load/
Apply
with
Hand
Held
Pump
Sprayer
7.
Mix/
Load/
Apply
with
Ready
to
Use
Sprayer
Data
Sources
The
handler
exposure
data
were
taken
from
the
Pesticide
Handler
Exposure
Database
(
PHED)
and
the
Outdoor
Residential
Exposure
Task
Force
(
ORETF).
Exposure
data
for
scenarios
#
1
and
#
2
were
taken
from
PHED.
Exposure
data
for
scenarios
#
3,
#
4
and
#
5
were
taken
from
the
residential
portion
of
the
ORETF
Handler
Study.
Exposure
data
for
scenarios
#
6
and
#
7
were
taken
from
MRID
444598­
01,
which
has
recently
been
purchased
by
the
ORETF.
This
study
involved
low
pressure
handwand
and
RTU
trigger
sprayer
application
of
carbaryl
to
home
vegetable
plants.

Assumptions
Regarding
Residential
Applicators
C
Clothing
would
consist
of
a
short­
sleeved
shirt,
short
pants
and
no
gloves.

C
Broadcast
spreaders
and
hose
end
sprayers
would
be
used
for
broadcast
treatments
and
the
other
application
methods
would
be
used
for
spot
treatments
only.

C
An
area
of
0.023
acre
(
1000
square
feet)
would
be
treated
per
application
during
spot
treatments
and
an
area
of
0.5
acre
would
be
treated
during
broadcast
applications.

C
The
application
rate
is
1.0
lb
ae/
acre
as
listed
in
the
Dicamba
Use
Closure
Memo.

6.1.2
Residential
Handler
Risk
Estimates
A
summary
of
the
margin
of
exposure
(
MOE)
estimates
is
included
in
Table
6.1.
All
of
the
MOEs
exceed
the
target
MOE
of
100
and
the
risks
are
not
of
concern.
The
residential
handler
risks
were
calculated
using
standard
assumptions,
the
highest
quality
unit
exposure
data
available,
and
the
maximum
label
application
rates.
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Table
6.1
Dicamba
Short
Term
MOEs
for
Homeowner
Applications
to
Lawns
(
Application
Rate
=
1.0
lb
ai/
acre)

Scenario
Treated
Area
(
acres/
day)
Combined
Dose
(
mg/
kg/
day)
Combined
MOEA
1
Hand
Application
of
Granules
0.023
0.0058
7800
2
Belly
Grinder
Application
0.023
0.0054
8300
3.
Load/
Apply
Granules
with
a
Broadcast
Spreader
0.5
0.00073
62000
4.
Mix/
Load/
Apply
with
a
Hose­
end
Sprayer
(
Mix
your
own)
0.5
0.012
3800
5.
Mix/
Load/
Apply
with
a
Hose­
end
Sprayer
(
Ready
to
Use)
0.5
0.0029
16000
6.
Mix/
Load/
Apply
with
Hand
Held
Pump
Sprayer
0.023
0.0019
24000
7.
Mix/
Load/
Apply
with
Ready
to
Use
Sprayer
0.023
0.0027
17000
A.
The
target
MOE
is
100.

6.2.
Residential
Postapplication
Exposure
and
Risk
Estimates
6.2.1
Residential
Postapplication
Exposure
Assessment
Scenarios
The
following
exposure
scenarios
are
assessed
for
residential
post
application
risks
C
Acute
and
Short
Term
Exposures
of
Toddlers
Playing
on
Treated
Turf
C
Acute
and
Short
Term
Exposures
of
Adults
Performing
Yardwork
on
Treated
Turf
C
Acute
and
Short
Term
Exposures
of
Adults
Playing
Golf
on
Treated
Turf
C
Acute
Exposures
of
Toddlers
from
Incidental
Oral
Ingestion
of
Granules
Data
Sources
There
are
three
turf
transferable
residue
studies
(
MRID
446557­
02,
450331­
01
and
446557­
03
that
were
submitted
by
the
Broadleaf
Turf
Herbicide
TFR
Task
Force.
The
field
portion
of
the
studies
were
conducted
by
Grayson
Research
LLC
of
Creedmoor,
North
Carolina,
AGSTAT
of
Verona,
Wisconsin,
and
Research
for
Hire
of
Porterville,
California.
The
laboratory
analysis
for
all
three
studies
was
conducted
by
Covance
Laboratories
of
Madison,
Wisconsin.
These
studies
measured
the
dissipation
of
several
phenoxy
herbicides,
including
Dicamba,
using
the
ORETF
roller
technique
(
which
is
also
called
the
modified
California
Roller).

There
was
an
additional
study
(
MRID
449590­
01)
that
was
submitted
by
Novartis
Crop
Protection.
The
field
portion
of
this
study
was
conducted
by
Research
Options,
Inc
of
Winter
Garden,
Florida,
ABC
Laboratories
California
of
Madera,
California
and
Crop
Management
Strategies
of
Germansville,
PA.
The
laboratory
analysis
for
all
three
sites
was
conducted
by
ABC
Laboratories
of
Columbia,
Missouri.
This
study
also
used
the
ORETF
roller
technique.
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All
of
the
studies
were
reviewed
by
HED
and
were
found
to
meet
all
of
the
series
875
guidelines
for
postapplication
exposure
monitoring.

Application
of
the
TTR
Data
A
summary
of
the
data
used
for
exposure
assessment
is
included
in
Table
9.2
Table
6.2
­
Summary
of
TTR
Data
Used
for
Post
Application
Exposure
Assessment
MRID
449590­
01
450331­
01
Location
Florida
California
Precipitation
No
Rain
No
Rain
Application
Rate
(
lb
ae/
acre)
1.0
0.21
Maximum
TTR
(
ug/
cm2)
0.29
0.033
Maximum
TTR
(
percent
of
application
rate)
2.6
­
Note
1
1.3
Day
0
Average
TTR
(
ug/
cm2)
0.10
0.033
Day
0
Average
TTR
(
percent
of
application
rate)
0.90
1.3
­
Note
2
Semi­
log
Slope
Factor
N/
A
­
0.38
­
Note
2
7
day
Average
TTR
(
ug/
cm2)
N/
A
0.013
7
day
Average
TTR
(
percent
of
application
rate)
N/
A
0.55
­
Note
2
Note
1
­
This
value
was
used
to
derive
the
TTR
for
1day
acute
exposures.
Note
2
­
These
values
were
used
to
derived
the
TTR
for
seven
day
average
short
term
exposures.

General
Assumptions
The
following
general
assumptions
are
taken
from
the
Standard
Operating
Procedure
(
SOPs)
of
December
18,
1997
and
ExpoSAC
Policy
#
12
"
Recommended
Revisions
to
the
Standard
Operating
Procedures
for
Residential
Exposure
Assessments
of
February
22,
2001.

C
The
TTR
values
were
used
for
calculating
dermal
exposures
on
turf
because
they
were
greater
than
1.0%
of
the
application
rate.
These
values
were
adjusted
for
application
rates
as
needed
C
An
assumed
initial
TTR
value
of
5.0%
of
the
application
rate
is
used
for
assessing
hand
to
mouth
exposures.

C
An
assumed
initial
TTR
value
of
20%
of
the
application
is
used
for
assessing
object
to
mouth
exposures.

C
Soil
residues
are
contained
in
the
top
centimeter
and
soil
density
is
0.67
mL/
gram.

C
Three
year
old
toddlers
are
expected
to
weigh
15
kg.

C
Hand­
to­
mouth
exposures
are
based
on
a
frequency
of
20
events/
hour
and
a
surface
area
per
event
of
20
cm2
representing
the
palmar
surfaces
of
three
fingers.

C
Saliva
extraction
efficiency
is
50
percent
meaning
that
every
time
the
hand
goes
in
the
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70
mouth
approximately
½
of
the
residues
on
the
hand
are
removed.

C
Adults
are
assessed
using
a
transfer
coefficient
of
14,500
cm2/
hour.

C
Toddlers
are
assessed
using
a
transfer
coefficient
of
5200
cm2/
hour.

C
Golfers
are
assessed
using
a
transfer
coefficient
of
500
cm2/
hour.

C
An
exposure
duration
of
2
hours
per
day
is
assumed
for
toddlers
playing
on
turf
or
adults
performing
heavy
yardwork.

C
An
exposure
duration
of
4
hours
is
assumed
for
playing
golf.

C
The
assumed
ingestion
rate
is
0.3
gram/
day.
This
is
based
on
the
assumption
that
if
150
lbs
of
product
were
applied
to
a
½
acre
lawn,
the
amount
of
product
per
square
foot
would
be
3
g/
ft2
and
a
child
would
consume
one­
tenth
of
the
product
available
in
a
square
foot.

C
The
percent
ai
in
granular
formulations
used
in
residential
settings
was
assumed
to
be
in
the
range
of
0.1
to
1.0
percent
based
upon
the
product
labels
listed
in
OPPIN.

Assumptions
Specific
to
Dicamba
The
following
assumptions
that
are
specific
to
Dicamba
are
used
for
assessing
residential
post
application
exposures.

C
The
application
rate
of
1.0
lbs
ae/
acre
as
stated
in
the
Use
Closure
Memo
was
used.

Calculation
Methods
The
above
factors
were
used
in
the
standard
SOP
formulas
to
calculate
the
exposures.
MOEs
were
calculated
for
acute
dermal
and
incidental
oral
exposures
using
the
maximum
TTR
value
along
with
the
acute
dietary
LOAEL
of
300
mg/
kg/
day
for
children
and
NOAEL
of
62.5
mg/
kg/
day
for
females,
aged
13­
49.
MOEs
for
short
term
exposures
were
calculated
using
the
seven
day
average
TTR
value,
because
the
short
term
dermal
NOAEL
of
45
mg/
kg/
day
was
based
upon
decreased
pup
body
weight
gain
which
did
not
occur
until
after
several
days
of
exposure.

6.2.2
Residential
Postapplication
Risk
Estimates
The
MOEs
for
acute
exposures
are
summarized
in
Table
6.3.
All
of
the
acute
MOEs
for
both
adult
and
toddler
exposures
exceed
the
respective
target
MOEs
of
100
and
300,
so
the
risks
for
adults
and
toddler
exposures
are
not
of
concern.
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Table
6.3
­
Acute
Dicamba
MOEs
for
Turf
Exposures
(
Application
Rate
=
1.0
lb
ae/
acre)

Scenario
TTR
(
ug/
cm2)
TC
(
cm2/
hr)
Dermal
MOE
Hand­
to
Mouth
MOE
Object
to
Mouth
MOE
Soil
Ingestion
MOE
Total
MOEB
Toddlers
(
BW
=
15
kg)

Playing
0.29A
5,200
9,900
20,000
80,000
5,900,000
6,100
Adults
(
BW
=
70
kg)

Yardwork
Golfing
0.29A
14,500
500
17,000
240,000
N/
A
A.
This
value
was
derived
from
the
maximum
TTR
of
2.6
percent
from
MRID
449590­
01.
B.
Total
MOE
=
1/((
1/
Dermal
MOE)
+
(
1/
Hand­
to­
Mouth
MOE)+
(
1/
Object­
to­
Mouth
MOE)+(
1/
Soil
Ingestion
MOE)).

The
target
MOE
is
300
for
adult
and
toddler
exposures.

The
MOEs
for
short
term
exposures
are
summarized
in
Table
6.4.
All
of
the
short
term
MOEs
for
both
adult
and
toddler
exposures
exceed
the
target
MOE
of
100.

Table
6.4.
Short
Term
Dicamba
MOEs
for
Turf
Exposures
(
Application
Rate
=
1.0
lb
ae/
acre)

Scenario
TTR
(
ug/
cm2)
TC
(
cm2/
hr)
Dermal
MOE
Hand­
to
Mouth
MOE
Object
to
Mouth
MOE
Soil
Ingestion
MOE
Total
MOEB
Toddler
Exposures
(
BW
=
15
kg)

Playing
0.060A
5200
7,200
7,200
29,000
2,100,000
3,200
Adult
Exposures
(
BW
=
70
kg)

Yardwork
0.060A
14500
12,000
N/
A
Golfing
0.060A
500
170,000
A.
Seven
day
average
TTR
derived
from
the
California
TTR
Study
MRID
450331­
01.
B.
Total
MOE
=
1/((
1/
Dermal
MOE)
+
(
1/
Hand­
to­
Mouth
MOE)+
(
1/
Object­
to­
Mouth
MOE)+(
1/
Soil
Ingestion
MOE))

The
target
MOE
for
adult
and
toddler
exposures
is
100.

The
acute
margins
of
exposures
from
toddlers
ingesting
granules
are
summarized
in
Table
6.5.
All
of
the
MOEs
exceed
300,
and
are
not
of
concern.
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Table
6.5
Granule
Ingestion
Risks
for
Dicamba
Percent
ai
Potential
Dose
Rate1
(
mg/
day)
Absorbed
Dose2
(
mg/
kg/
day)
Acute
MOE3
0.1
0.3
0.02
15000
0.5
1.5
0.1
3000
1.0
3.0
0.2
1500
1.
Potential
Dose
Rate
(
PDR)
=
0.3
gram/
day
*
Percent
ai*
1000
mg/
gram
2.
Absorbed
Dose
=
PDR/
BW
3.
MOE
=
NOAEL/
Dose
where
the
NOAEL
=
300
mg/
kg/
day
The
calculation
of
acute
MOEs
using
a
maximum
TTR
value
for
toddler
turf
post
application
exposure
represents
a
policy
change,
because
the
maximum
TTR
values
were
previously
only
used
to
calculate
short
term
MOEs.
The
dicamba
risk
assessment
team
decided
that
the
previous
approach
would
greatly
overestimate
the
short
term
risks,
because
the
short
term
incidental
oral
and
dermal
endpoints
were
based
upon
effects
that
would
only
occur
after
several
days
of
exposure.
The
team
also
decided
that
the
single
day
exposures
as
represented
by
the
maximum
TTR
values
would
be
more
appropriately
assessed
using
the
acute
dietary
endpoints.
The
short
term
exposures
were
assessed
using
the
seven
day
average
TTR
values
because
the
endpoints
occurred
after
several
days
of
exposure
and
because
the
TTR
data
were
collected
during
a
seven
day
time
period.

The
actual
use
rates
of
dicamba
are
typically
less
than
the
maximum
label
rates
because
dicamba
is
usually
mixed
with
other
herbicides
such
as
2,4­
D
and
MCPP­
p.

6.3
Other
(
Spray
Drift,
etc.)

Spray
drift
is
always
a
potential
source
of
exposure
to
residents
nearby
to
spraying
operations.
This
is
particularly
the
case
with
aerial
application,
but,
to
a
lesser
extent,
could
also
be
a
potential
source
of
exposure
from
the
ground
application
method
employed
for
the
dicamba.
The
Agency
has
been
working
with
the
Spray
Drift
Task
Force,
EPA
Regional
Offices
and
State
Lead
Agencies
for
pesticide
regulation
and
other
parties
to
develop
the
best
spray
drift
management
practices.
On
a
chemical
by
chemical
basis,
the
Agency
is
now
requiring
interim
mitigation
measures
for
aerial
applications
that
must
be
placed
on
product
labels/
labeling.
The
Agency
has
completed
its
evaluation
of
the
new
data
base
submitted
by
the
Spray
Drift
Task
Force,
a
membership
of
U.
S.
pesticide
registrants,
and
is
developing
a
policy
on
how
to
appropriately
apply
the
data
and
the
AgDRIFT
computer
model
to
its
risk
assessments
for
pesticides
applied
by
air,
orchard
airblast
and
ground
hydraulic
methods.
After
the
policy
is
in
place,
the
Agency
may
impose
further
refinements
in
spray
drift
management
practices
to
reduce
off­
target
drift
with
specific
products
with
significant
risks
associated
with
drift.
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7.0
Aggregate
Risk
Assessments
and
Risk
Characterization
In
accordance
with
the
FQPA,
HED
must
consider
and
aggregate
(
add)
pesticide
exposures
and
risks
from
three
major
sources:
food,
drinking
water,
and
residential
exposures.
In
an
aggregate
assessment,
exposures
from
relevant
sources
are
added
together
and
compared
to
quantitative
estimates
of
hazard
(
e.
g.,
a
NOAEL
or
PAD),
or
the
risks
themselves
can
be
aggregated.
When
aggregating
exposures
and
risks
from
various
sources,
HED
considers
both
the
route
and
duration
of
exposure.

7.1
Acute
Aggregate
Risk
Acute,
or
less
than
one
day,
exposures
may
result
from
consuming
treated
food,
drinking
water,
or
residential
exposures
such
as
yard
work
for
adults,
playing
golf
on
treated
turf,
or
playing
in
treated
turf
for
children.
Typically
HED
does
not
aggregate
acute
food
exposures
with
acute
residential
exposures.
The
acute
food
exposure
estimates
consider
higher
food
consumption
with
maximum
residue
values
and
the
estimated
drinking
water
estimates
are
high­
end
values
as
well.
It
is
very
unlikely
that
high
end
food
and
water
exposures
will
occur
on
the
same
day
as
the
maximum
residential
exposures.

The
aggregate
food
and
water
assessment
results
are
presented
in
Table
7.1.
The
most
highly
exposed
subgroup
is
infants
(<
1
year
old)
at
11%
of
the
aPAD,
which
is
well
below
the
level
of
concern.
As
stated
previously,
actual
exposures
are
likely
to
be
much
lower
because
the
food
assessment
assumes
100%
crop
treated
and
tolerance
level
residues.

Table
7.1.
Aggregate
Acute
Assessment
for
Dicamba
­
Food
and
Water
Population
Subgroup*
Acute
Dietary
(
95th
Percentile)

Dietary
Exposure
(
mg/
kg/
day)
%
aPAD
General
U.
S.
Population
0.0435
4.4
All
Infants
(<
1
year
old)
0.108
11
Children
1­
2
years
old
0.0756
7.6
Children
3­
5
years
old
0.0675
6.8
Children
6­
12
years
old
0.0476
4.8
Youth
13­
19
years
old
0.0318
3.2
Adults
20­
49
years
old
0.0341
3.4
Adults
50+
years
old
0.0267
2.7
Females
13­
49
years
old
0.0312
5.0
Drinking
water
exposures
are
from
surface
water
sources.
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7.2
Short­
Term
Aggregate
Risk
The
short
term
aggregate
assessment
considered
exposures
from
food,
water,
residential
handles,
and
residential
post­
application
activities.
Average
food
and
water
exposure
estimates
were
used
in
the
assessment.
The
residential
handler
scenario
that
resulted
in
the
highest
exposures,
mix/
load/
apply
with
a
(
mix
your
own)
hose­
end
sprayer,
was
used
in
the
handler
assessment.
The
exposures
from
the
yardwork
post­
application
scenario
was
used
for
the
adult
assessment,
and
the
exposures
from
the
toddler
playing
in
turf
scenario
was
used
in
the
child
assessment.
The
other
scenario
considered
was
the
same
adult
applying
dicamba
with
the
hose­
end
sprayer
and
then
doing
yardwork
in
the
treated
area.

The
results
of
all
of
the
short­
term
aggregate
assessments
are
presented
in
Table
7.2.
HED
is
generally
not
concerned
if
the
margins
of
exposure
(
MOEs)
exceed
the
target,
which
for
this
assessment
is
100.
The
MOEs
for
all
scenarios
are
greater
than
100
so
are
not
of
concern.
As
stated
in
the
previous
section,
these
are
likely
to
be
overestimates
and
the
actual
exposures
are
probably
much
lower.

Table
7.2.
Short­
Term
Aggregate
Risk
Calculations
For
Dicamba
Population
Food
+
Water
Exposure
mg/
kg/
day
Incidental
Oral
Exposure,
mg/
day
Dermal
Dose,
mg/
kg/
day
Combined
Exposure,
mg/
kg/
day
MOE
Food
+
Water+
Incidental
Oral
+
Dermal
Adult
Male
­
Handler
0.012822
0
0.0102
0.023
1950
Adult
Male
­
Post
­
App
0.012822
0
0.0037
0.01652
2720
Child
­
Post
­
App
0.029662
0.0078
0.0062
0.04366
1030
Note:
HED
is
generally
not
concerned
if
the
MOE
exceeds
the
target
of
100.
The
adult
handler
assessment
is
from
the
scenario
that
had
the
highest
exposure,
Mix/
Load/
Apply
with
a
Hose­
end
Sprayer
(
Mix
your
own).
The
adult
post­
application
assessment
is
from
the
yard
work
scenario.
The
exposures
for
the
child
post­
application
scenario
are
from
a
toddler
playing
on
treated
turf.
Average
food
and
water
exposures
were
used
in
this
assessment.
Adult
Male
food
consumption
was
used
for
the
food
and
water
values
because
they
have
greater
exposure.

7.3
Intermediate­
Term
Aggregate
Risk
There
are
no
residential
scenarios
that
would
result
in
intermediate­
term
(
1
month
to
6
month)
residential
exposures.
Additionally,
the
same
toxicity
study
was
used
as
the
endpoint
for
all
short­
,
intermediate­,
and
long­
term
assessments,
so
the
short­
term
assessment
is
protective
of
all
of
these
exposures.
An
intermediate­
term
assessment
is
not
required.

7.4
Long­
Term
Aggregate
Risk
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There
are
no
residential
scenarios
that
would
result
in
long
term
(
greater
than
six
month)
exposures,
so
only
food
and
water
need
be
aggregated
for
this
assessment.
Results
of
the
chronic
assessment
are
presented
in
Table
7.3.

The
most
highly
exposed
subgroup
is
children,
aged
1­
2
years
old,
at
6.6%
of
the
cPAD.
Again,
this
is
an
exaggerated
assessment
as
it
assumes
100
percent
crop
treated
and
tolerance­
level
residues.
Actual
exposure
is
likely
to
be
much
lower.

Table
7.3.
Summary
of
Dietary
Exposure
and
Risk
for
Dicamba
­
Food
and
Water
Population
Subgroup*
Chronic
Dietary
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD*

General
U.
S.
Population
0.0118
2.6
All
Infants
(<
1
year
old)
0.0199
4.4
Children
1­
2
years
old
0.0297
6.6
Children
3­
5
years
old
0.0270
6.0
Children
6­
12
years
old
0.0185
4.1
Youth
13­
19
years
old
0.0113
2.5
Adults
20­
49
years
old
0.00973
2.2
Adults
50+
years
old
0.00750
1.7
Females
13­
49
years
old
0.00870
1.9
7.5
Cancer
Risk
In
accordance
with
the
EPA
Final
Guidelines
for
Carcinogen
Risk
Assessment
(
March
29,
2005),
dicamba
is
classified
as
"
Not
Likely
to
be
Carcinogenic
to
Humans".
This
was
based
on
negative
cancer
studies
in
rats
and
mice
which
were
tested
at
adequate
dose
levels
to
assess
the
carcinogenicity
of
dicamba
Therefore,
this
risk
assessment
is
not
required.

8.0
Cumulative
Risk
Characterization/
Assessment
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
as
to
dicamba
and
any
other
substances,
and
dicamba
does
not
appear
to
produce
a
toxic
metabolite
produced
by
other
substances.
For
the
purposes
of
this
tolerance
action,
therefore,
EPA
has
not
assumed
that
dicamba
has
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
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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/.
9.0
Occupational
Exposure/
Risk
Pathway
9.1
Short/
Intermediate
Handler
Risk
9.1.1
Exposure
9.1.1.1
Exposure
Scenarios
Based
upon
the
application
methods
for
occupational
uses
of
dicamba,
the
following
exposure
scenarios
were
assessed.

Mix/
Load
Wettable
Powder
Mix/
Load
Water
Dispersible
Granules
Mix/
Load
Liquid
Formulations
Load
Granules
Aerial
Application
Groundboom
Application
Turfgun
Application
Backpack
application
Right
of
Way
Application
Broadcast
Spreader
Application
Mix/
Load/
Apply
Liquids
with
a
Backpack
Sprayer
Mix/
Load/
Apply
Wettable
Powder
with
a
Turfgun
Mix/
Load/
Apply
Wettable
Powder
with
a
Water
Dispersible
Granules
Mix/
Load/
Apply
Liquids
with
a
Turfgun
Load/
Apply
Granules
with
a
Push
Cyclone
Flag
Aerial
Application
9.1.1.2
Occupational
Handler
Exposure
Assumptions
and
Data
Sources
Exposure
Assumptions
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.
°
The
daily
acreages
treated
were
taken
from
EPA
Science
Advisory
Council
for
Exposure
Standard
Operating
Procedure
#
9
"
Standard
Values
for
Daily
Acres
Treated
in
Agriculture,"
Revised
July
5,
2000.
These
values
are
listed
in
Table
6.

C
The
application
rates
are
the
maximum
rates
as
listed
in
the
Dicamba
Use
Closure
Memo.

C
A
body
weight
of
70
kg
was
assumed
because
the
endpoint
is
not
gender
specific.

C
The
inhalation
absorption
rate
is
100%.

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

C
Single
Layer
PPE
includes
baseline
PPE
with
chemical
resistant
gloves.

C
Double
Layer
PPE
includes
coveralls
over
single
layer
PPE.

C
PF5
indicates
a
filtering
facepiece
respirator
(
i.
e.
a
dustmask)
with
a
protection
Dicamba
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Health
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Phase
I
Barcode:
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43
of
70
factor
of
5
when
properly
fitted.

C
PF10
indicates
a
half
mask
elastomeric
facepiece
respirator
with
a
protection
factor
of
10
when
properly
fitted
and
used
with
appropriate
cartridges.

C
Only
closed
cockpit
airplanes
are
used
for
aerial
application.

C
Airplane
pilots
do
not
wear
chemical
resistant
gloves.

Handler
Exposure
Data
Sources
The
handler
exposure
data
were
taken
from
the
Pesticide
Handler
Exposure
Database
(
PHED),
the
Outdoor
Residential
Exposure
Task
Force
(
ORETF)
and
the
California
Department
of
Pesticide
Regulation
(
CA
DPR).
The
PHED
data
were
used
primarily
for
the
large
scale
agricultural
and
forestry
scenarios
and
the
ORETF
data
were
used
for
lawn
care
scenarios.
The
CA
DPR
data
were
used
for
the
backpack
applicator
forest
site
preparation
scenario
where
multiple
applicators
are
supplied
by
a
nurse
tank.

9.1.2
Occupational
Handler
Risk
Estimates
and
Characterization
A
summary
of
the
risk
estimates
for
occupational
handlers
is
presented
in
Table
9.1.
The
margins
of
exposure
for
some
of
the
baseline
exposure
scenarios
are
below
the
target
of
100.
However,
if
a
single
layer
of
protection
or
engineering
controls
are
added
to
these
scenarios,
then
all
of
the
occupational
exposure
estimates
have
margins
of
exposure
exceeding
100,
so
none
of
are
of
risk
concern.

The
actual
use
rates
of
dicamba
are
typically
less
than
the
maximum
label
rates
because
dicamba
is
usually
mixed
with
other
herbicides
such
as
2,4­
D
to
increase
the
spectrum
of
weeds
controlled.

Only
a
few
dicamba
products
are
formulated
as
wettable
powders
and
most
of
these
products
are
packaged
in
water
soluble
bags
that
are
used
on
turf.

Many
of
the
labels
require
waterproof
gloves
instead
of
chemical
resistant
gloves.
It
is
not
known
if
these
gloves
provide
adequate
protection.

Table
9.1
Dicamba
Handler
Combined
MOEs
Exposure
Scenario
Crop
or
Site
Application
Rate
(
lb
ae/
acre)
Acres/
Day
Margins
of
Exposure
Baseline
Single
Layer
Engineering
Control
Mixer/
Loader
(
M/
L)

M/
L
WP
for
Groundboom
M/
L
WP
for
Turfgun
Application
Golf
Courses
turf
1
1
40
5
130
>
1000
>
1000
>
1000
>
1000
>
1000
M/
L
WDG
for
Aerial
M/
L
WDG
for
Aerial
M/
L
WDG
for
Groundboom
M/
L
WDG
for
Groundboom
M/
L
WDG
for
Groundboom
M/
L
WDG
for
Turf
Gun
Fallow
Land
Corn
Fallow
Land
Corn
Golf
Courses
Turf
2
0.5
2
0.5
1
1
1200
1200
200
200
40
100
120
490
740
>
1000
>
1000
>
1000
120
490
740
>
1000
>
1000
>
1000
NA
NA
NA
NA
NA
NA
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Table
9.1
Dicamba
Handler
Combined
MOEs
Exposure
Scenario
Crop
or
Site
Application
Rate
(
lb
ae/
acre)
Acres/
Day
Margins
of
Exposure
Baseline
Single
Layer
Engineering
Control
Page
44
of
70
M/
L
Liquids
for
Aerial
M/
L
Liquids
for
Aerial
M/
L
Liquids
for
Aerial
M/
L
Liquids
for
Groundboom
M/
L
Liquids
for
Groundboom
M/
L
Liquids
for
Groundboom
M/
L
Liquids
for
Groundboom
M/
L
Liquids
for
Groundboom
M/
L
Liquids
for
ROW
Sprayer
M/
L
Liquids
for
Turf
Gun
M/
L
Liquids
for
Backpack
Application
Sugar
Cane
Soybeans,
RPF
Small
Grains,
Corn
Sugar
Cane
Soybean,
RPF
Small
Grains,
Corn
Sod
Farms
Golf
Courses
Right
of
Way
Areas
Turf
Forest
Site
Prep
2.8
2
0.5
2.8
2
0.5
1
1
2
1
2
1200
1200
1200
200
200
200
80
40
50
100
40
23
12
13
18
72
90
180
72
72
90
200
280
>
1000
>
1000
>
1000
>
1000
>
1000
>
1000
>
1000
>
1000
>
1000
680
960
>
1000
>
1000
>
1000
>
1000
>
1000
>
1000
>
1000
>
1000
>
1000
Load
Granulars
for
Broadcast
Spreader
Golf
Courses
1.5
40
>
1000
>
1000
>
1000
Applicator
(
APP)

Aerial
Application
Groundboom
Application
ROW
Application
Back
Pack
Application
Turfgun
Application
Broadcast
Spreader
Application
All
crops
above
All
crops
above
ROW
Forest
Site
Prep
Turf
Golf
Courses
0.5
to
2.8
0.5
to
2.8
2
1.0
1.5
1.5
1200
40
to
200
50
4
5
40
ND
>
1000
160
ND
ND
>
1100
ND
>
1000
500
410
>
1000
>
1000
>
1000
>
1000
ND
ND
ND
>
1000
Mixer/
Loader/
Applicator
(
M/
L/
A)

M/
L/
A
Wettable
Powder
with
Turfgun
M/
L/
A
WDG
with
Turfgun
M/
L/
A
Liquid
Flowables
with
Turfgun
M/
L/
A
Liquids
with
Backpack
Sprayer
Load/
Apply
Granules
with
a
Push
Cyclone
turf
turf
turf
ROW,
RPF
turf
1
1
1
2
1
5
5
5
4
5
ND
ND
ND
ND
ND
>
1000
>
1000
>
1000
970
>
1000
>
1000
ND
ND
ND
ND
Flagger
Flag
Aerial
Application
All
crops
above
0.5
to
2.8
1200
>
470
>
440
>
1000
Notes:
Risk
estimates
are
the
combined
dermal
and
inhalation
exposures.

RPF
=
Rangeland,
Pastures
and
Fallow
Land
ROW
=
Rights
of
Way
ND
=
No
Data
Available
MOEs
that
are
less
than
100
indicate
risks
of
concern
and
are
highlighted
in
bold
font.

9.2
Short/
Intermediate/
Long­
Term
Postapplication
Risk
Post
application
Dicamba
exposures
can
occur
in
the
agricultural
environment
when
workers
enter
fields
recently
treated
with
Dicamba
to
conduct
tasks
such
as
scouting
and
irrigation.

9.2.1
Occupational
Post
Application
Exposure
9.2.1.1
Occupational
Post
Application
Exposure
Scenarios
Broadcast
applications
can
be
made
to
grass
crops,
such
as
cereal
grains,
which
are
tolerant
of
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of
70
dicamba.
Because
dicamba
is
typically
applied
once
per
season
and
the
relevant
agricultural
scenarios
occur
for
only
a
few
weeks
per
year,
it
is
anticipated
that
dicamba
exposures
would
be
primarily
short
term
and,
more
rarely,
intermediate
term.

Potential
inhalation
exposures
are
not
anticipated
for
the
post­
application
worker
scenarios
because
of
the
low
vapor
pressure
of
dicamba
(
3.4
x
10
­
5
mm
at
25
C),
and
the
Agency
currently
has
no
policy/
method
for
evaluating
non­
dietary
ingestion
by
workers
due
to
poor
hygiene
practices
or
smoking.
As
a
result,
only
dermal
exposures
were
evaluated
in
the
post­
application
worker
assessment.

9.2.1.2
­
Exposure
Data
Sources
and
Assumptions
There
are
three
turf
transferable
residue
(
TTR)
studies
that
were
submitted
by
the
Broadleaf
Turf
Herbicide
TFR
Task
Force.
A
summary
of
the
turf
transfer
coefficients
along
with
characterization
of
the
post­
application
scenarios
as
low,
medium,
or
high
exposures
may
be
found
in
Table
9.2
The
following
assumptions
were
made
regarding
occupational
post
application:

C
Risks
were
assessed
using
the
maximum
rates
from
the
Dicamba
Use
Closure
Memo.

C
The
transfer
coefficients
are
from
an
interim
transfer
coefficient
policy
developed
by
HED's
Science
Advisory
Council
for
Exposure
using
proprietary
data
from
the
Agricultural
Reentry
Task
Force
(
ARTF)
database
(
US
EPA,
August
7,
2001).
This
policy
will
be
periodically
updated
to
incorporate
additional
information
about
agricultural
practices
in
crops
and
new
data
on
transfer
coefficients.
Much
of
this
information
will
originate
from
exposure
studies
currently
being
conducted
by
the
ARTF,
from
further
analysis
of
studies
already
submitted
to
the
Agency,
and
from
studies
in
the
published
scientific
literature.

C
The
transfer
coefficients
for
turf
harvesting
and
maintenance
are
based
upon
recently
conducted
ARTF
studies
that
are
being
reviewed
by
HED.

C
The
initial
percent
of
application
rate
as
Dislodgeable
Foliar
Residue
(
DFR)
was
assumed
to
be
20%
for
all
crops
except
turf.
These
are
the
standard
values
used
in
the
absence
of
chemical
specific
data.

C
The
Maximum
TTR
value
(
2.6
percent
of
the
application
rate)
from
the
DMA
Treatment
at
the
Florida
site
in
the
Vanquish
Study
was
used
to
assess
risks
of
working
on
turf.
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Table
9.2
Post
Application
Exposure
Scenarios
and
Transfer
Coefficients
for
Dicamba
Crop
Label
Directions
Post
Application
Exposure
Scenarios
Transfer
Coefficient
(
cm2/
hr)

Asparagus
Apply
immediately
after
cutting.
If
spray
contacts
emerged
spears,
crooking
may
result.
Pre
Harvest
Interval
(
PHI)
=
24
hours
None1,2
Small
Grains
Barley,
Oats,
proso
millet,
triticale,
wheat
Apply
to
fall
seeded
barley
prior
to
the
jointing
stage.
Apply
to
spring
seed
barley
before
it
exceeds
the
4
leaf
stage.
Apply
to
fall
seeded
oats
prior
to
the
jointing
stage.
Apply
to
spring
seeded
oats
before
the
5
leaf
stage
is
exceeded.
Apply
to
proso
millet
at
the
2
to
5
leaf
stage.
Apply
to
fall
seeded
triticale
or
wheat
prior
to
the
jointing
stage.
Apply
to
spring
seeded
triticale
or
wheat
before
the
6
leaf
stage.

Low
Exposure
Scenarios
­
Irrigation,
scouting,
immature
plants
Medium
Exposure
Scenarios
­
Same
as
above
on
mature
plants
100
1500
Corn
Early
Post
Emergence
­
Apply
from
corn
emergence
through
5
leaf
stage
or
8
inches
tall,
whichever
comes
first.

Late
Post
Emergence
­
Apply
from
8
to
36
inch
corn
or
to
15
days
before
tassel
emergence,
whichever
comes
first.

Low
Exposure
Scenarios
­
Scouting,
weeding
immature
plants
Medium
Exposure
Scenarios
­
Scouting,
weeding
more
mature
plants
High
Exposure
Scenarios
­
Scouting,
weeding,
irrigation
mature
plants
Very
High
Exposure
Scenarios
­
Detasseling
100
400
NA
NA
Cotton
N/
A
­
Applied
as
a
preplant
treatment.
NA
Pasture,
Rangeland,
Grassland
PHI
=
7
days
None1
Sorghum
Post
Emergence
­
Apply
when
sorghum
is
in
the
3
to
5
leaf
stage,
but
before
it
is
15"
tall.
If
sorghum
is
taller
than
8"
use
drop
nozzles
and
keep
spray
off
the
foliage.

Pre­
harvest
application
(
TX
and
OK
only)
­
apply
anytime
after
soft
dough
stage
(
PHI
=
30
days)

Low
Exposure
Scenarios
­
Scouting
immature
plants
High
Exposure
Scenarios
­
Irrigation
and
scouting
mature
plants
100
1000
Soybeans
Apply
after
pods
have
reached
mature
brown
color
and
at
least
75%
leaf
drop
has
occurred
(
PHI
=
14
days)
None1
Sugarcane
Apply
before
canes
appear
for
control
of
emerged
weeds.
Apply
after
canes
emerge
and
through
canopy
closure.
When
possible
direct
sprays
beneath
the
canopy
to
minimize
the
likelihood
of
crop
damage.

Medium
Exposure
Scenarios
­
scouting
immature
plants
High
Exposure
Scenarios
­
scouting
mature
plants
1000
2000
Turf,
Sod
Farm
and
Golf
Course
Treat
when
weeds
are
young
and
actively
growing.
Do
not
apply
more
than
1.0
lb
per
season.

Low
Exposure
Scenarios
­
Mowing
High
Exposure
Scenarios
­
Transplanting,
hand
weeding
3400
6800
1.
Post
application
exposures
are
expected
to
be
minimal
due
to
application
timing
or
method.
2.
Asparagus
plants
do
not
have
foliage
(
i.
e.
ferns)
when
the
spears
are
harvested.

9.2.2
Occupational
Post
Application
Risk
Estimates
A
summary
of
the
worker
risks
for
short/
intermediate
term
post
application
exposures
is
given
in
Table
9.3.
All
of
the
short/
intermediate
term
MOEs
are
above
100
on
Day
0
which
indicates
that
the
risks
are
not
of
concern.
The
Worker
Protection
Standard
(
WPS)
Restricted
Entry
Interval
Dicamba
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Health
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­
Phase
I
Barcode:
D317720
Page
47
of
70
(
REI)
for
dicamba
is
24
hours
for
the
amine
and
sodium
salt
forms.

Table
9.3
­
Dicamba
Postapplication
Worker
Risks
Crop
Transfer
Coefficient
Group
Application
Rate
(
lb
ae/
acre)
Short/
Intermediate
Term
MOE
on
Day
0
Low
Exposure
Scenarios*
Medium
Exposure
Scenarios*
High
Exposure
Scenarios*

Small
Grains
(
i.
e.
wheat)
Field/
row
crop,
low/
medium
0.50
23000
1600
NA
Corn
(
Early
Post
Emergence)
Field/
row
crop,
low/
medium
0.50
23000
N/
A
NA
Corn
(
Late
Post
Emergence)
Field/
row
crop,
low/
medium
0.25
N/
A
12000
N/
A
Sorghum
Field/
row
crop,
low/
medium
0.25
47000
12000
4700
Sugarcane
Sugarcane
2.8
N/
A
420
210
Turf
Turf
1.0
2600
N/
A
1300
10.0
Data
Needs
and
Label
Requirements
10.1
Toxicology
No
studies
are
required.

10.2
Residue
Chemistry
C
Additional
method
validation
data
using
Method
AM­
0691B­
0297­
4;
recovery
data
are
needed
for
barley
grain
and
straw
at
fortification
levels
of
6
and
15
ppm,
respectively,
and
for
wheat
straw
at
30
ppm.
Additional
method
validation
data
using
Method
AM­
0941­
1094­
0
are
also
needed
for
soybean
seeds
at
a
spike
level
of
10
ppm.

C
Revise/
improve
Method
II
of
PAM
Vol.
II
to
include
an
acid
hydrolysis
step
and
submit
additional
validation
data.
Method
II
should
also
be
re­
written
specifically
for
the
analysis
of
the
parent
dicamba
and
its
metabolite
3,6­
dichloro­
2­
hydroxybenzoic
acid
metabolite
in
animal
matrices.

C
Multiresidue
methods
recovery
data
for
the
dicamba
metabolites
of
concern
(
5­
OH
dicamba
and
DCSA).

C
Storage
stability
data
for
sugarcane
molasses
and
animal
commodities.

C
Residue
data
and
tolerances
for
soybean
forage
and
hay
if
no
feeding
restrictions
appear
on
the
label.

C
Magnitude
of
the
residue
data
for
sugarcane.
In
lieu
of
submitting
additional
data
the
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
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Page
48
of
70
registrants
have
the
option
of
relying
on
the
available/
submitted
data
provided
they
revise
their
product
labels
for
consistency
with
the
reviewed
data.

10.3
Occupational
and
Residential
Exposure
No
Data
Required
References
Abdel­
Saheb,
I.,
Drinking
water
assessment
for
Dicamba
on
sugarcane;
PC
Code
029801;
DP
Barcode:
317705;
May
31,
2005.

Dole,
T.
Dicamba:
Occupational
and
Residential
Exposure
and
Risk
Assessment
for
the
Reregistration
Eligibility
Decision
(
RED)
Document
;
PC
Code
029801,
DP
Barcode
D317701;
August
2005.

Hartge
P,
Colt
JS,
Severson
RK,
et
al.
2005.
Residential
herbicide
use
and
risk
of
non­
Hodgkin's
lymphoma.
Cancer
Epidemiology,
Biomarkers
and
Prevention
14:
934­
7.

Hawkins,
M.;
Review
of
Dicamba
Incident
Reports;
Chemical
#
029801;
DP
Barcode
D316974;
July
28,
2005.

Kaul,
M.;
Screening
Level
Usage
Analysis
for
Dicamba,
9/
20/
04.

Kidwell,
J.;
DICAMBA:
Report
of
the
Dose
Adequacy
Review
Team.
PC
Code:
029801.
DP
Barcode:
DP
317700;
8/
16/
2005.

McDuffie
HH,
Pahwa
P,
McLaughlin
JR.
2001.
Non­
Hodgkin's
lymphoma
and
specific
pesticide
exposures
in
men:
cross­
Canada
study
of
pesticides
and
health.
Cancer
Epidemiology,
Biomarkers
and
Prevention
10:
1155­
63.

Olinger,
C.,
Dicamba:
Acute
and
Chronic
Dietary
Exposure
Assessments
for
the
Reregistration
Eligibility
­
Phase
1;
PC
Code:
029801;
DP
Barcode:
D317702;
August
2005.

Olinger,
C.,
Dicamba:
Residue
Chemistry
Considerations
for
the
Reregistration
Eligibility
Decision
(
RED)
Document;
PC
Code:
029801;
DP
Barcode:
D317703;
August
2005.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
49
of
70
Appendix
A:
Toxicology
Assessment
Table
A3.
Data
requirements
(
CFR
158.340)
for
Dicamba
Study
Technical
Required
Satisfied
870.1100
Acute
Oral
Toxicity
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.1200
Acute
Dermal
Toxicity
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.1300
Acute
Inhalation
Toxicity
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.2400
Primary
Eye
Irritation
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.2500
Primary
Dermal
Irritation
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.2600
Dermal
Sensitization
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
870.3100
Oral
Subchronic
(
rodent)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.3150
Oral
Subchronic
(
nonrodent)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.3200
21­
Day
Dermal
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.3250
90­
Day
Dermal
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.3465
90­
Day
Inhalation
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
yes
yes
yes
no
no
yes1
yes1
yes
NA
NA
870.3700a
Developmental
Toxicity
(
rodent)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.3700b
Developmental
Toxicity
(
nonrodent)
.
.
.
.
.
.
.
.
.
.
.
.
870.3800
Reproduction
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
yes
yes
yes
yes
yes
yes
870.4100a
Chronic
Toxicity
(
rodent)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.4100b
Chronic
Toxicity
(
nonrodent)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.4200a
Oncogenicity
(
rat)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.4200b
Oncogenicity
(
mouse)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.4300
Chronic/
Oncogenicity
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
870.5100
Mutagenicity 
Gene
Mutation
­
bacterial
.
.
.
.
.
.
.
.
870.5300
Mutagenicity 
Gene
Mutation
­
mammalian
.
.
.
.
.
.
870.5375
Mutagenicity 
Structural
Chromosomal
Aberrations
870.5xxx
Mutagenicity 
Other
Genotoxic
Effects
.
.
.
.
.
.
.
.
.
.
yes
yes
yes
yes
yes
yes
yes
yes
870.6100a
Acute
Delayed
Neurotox.
(
hen)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.6100b
90­
Day
Neurotoxicity
(
hen)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.6200a
Acute
Neurotox.
Screening
Battery
(
rat)
.
.
.
.
.
.
.
.
.
870.6200b
90
Day
Neuro.
Screening
Battery
(
rat)
.
.
.
.
.
.
.
.
.
.
.
870.6300
Develop.
Neuro
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
no
no
yes
yes
yes
no
no
yes
yes
yes
870.7485
General
Metabolism
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
870.7600
Dermal
Penetration
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
yes
yes
yes
yes
Special
Studies
for
Ocular
Effects
Acute
Oral
(
rat)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Subchronic
Oral
(
rat)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Six­
month
Oral
(
dog)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
no
no
no
no
no
no
1.
Requirements
are
satisfied
by
chronic
oral
toxicity
studies.

Summaries
of
Carcinogenicity
and
Mutagenicity
Studies
Carcinogenicity
Study
in
Rats
Executive
Summary:
In
a
combined
chronic
toxicity/
carcinogenicity
study
(
MRID
00146150),
groups
of
60
male
and
60
female
CD
rats
were
fed
diets
containing
dicamba
(
86.8%
a.
i.;
Lot
no.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
50
of
70
52625110)
at
0,
50,
250
ro
2500
ppm
for
115
(
males)
or
117
(
females)
weeks.
These
doses
correspond
to
0,
2,
11
or
107
mg/
kg
bw/
day
for
males
and
0,
3,
13
or
127
mg/
kg
bw/
day
for
females.
Treatment
had
no
adverse
effect
on
survival,
body
weight,
body
weight
gain,
food
consumption,
hematology,
clinical
chemistry,
urinalysis,
organ
weights
or
gross
pathology.
Histopathology
revealed
increases
in
malignant
lymphomas
in
males
(
0/
60,
0/
60,
4/
60
and
4/
60
at
0,
50,
250
and
2500
ppm,
respectively)
and
thyroid
parafollicular
cell
carcinomas
in
males
(
1/
60,
0/
60,
2/
60
and
5/
60
at
0,
50,
250
and
2500
ppm,
respectively).
The
Cochran­
Armitage
trend
test
showed
a
statistically
significant
(
p<
0.05)
tendency
for
the
proportion
of
animals
with
tumors
to
increase
steadily
with
increase
in
dose.
Pairwise
comparison
(
Fisher's
Exact
test)
showed
no
statistical
significance.
Therefore,
these
tumors
were
not
considered
to
be
toxicologically
significant.

Under
the
conditions
of
this
study,
dicamba
was
not
carcinogenic
in
male
or
female
rats
at
the
doses
tested.
The
lack
of
systemic
toxicity
indicate
that
the
animals
may
have
tolerated
higher
doses
(
i.
e.,
an
MTD
was
not
achieved).
However,
the
doses
employed
in
this
study
were
approved
by
the
Agency
(
Memo:
S.
April
to
R.
Taylor,
RD,
dated
09/
26/
86).

Discussion
of
Tumor
Data:
The
administration
of
dicamba
to
rats
up
to
2500
ppm
(
107
mg/
kg/
day
for
males,
127
mg/
kg/
day
for
females)
in
the
diet
revealed
increases
in
malignant
lymphomas
in
males
(
0/
60,
0/
60,
4/
60
and
4/
60
at
0,
50,
250
and
2500
ppm,
respectively)
and
thyroid
parafollicular
cell
carcinomas
in
males
(
1/
60,
0/
60,
2/
60
and
5/
60
at
0,
50,
250
and
2500
ppm,
respectively).
The
Cochran­
Armitage
trend
test
showed
a
statistically
significant
(
p<
0.05)
tendency
for
the
proportion
of
animals
with
tumors
to
increase
steadily
with
increase
in
dose.
Pairwise
comparison
(
Fisher's
Exact
test)
showed
no
statistical
significance.
Therefore,
these
tumors
were
not
considered
to
be
toxicologically
significant.

Adequacy
of
the
Dose
Levels
Tested:

The
Dose
Adequacy
Review
Team
(
DART)
reviewed
the
dosages
of
the
study
and
concluded
that
the
dose
levels
in
the
chronic
toxicity/
carcinogenicity
study
in
rats
could
have
been
higher
based
on
kinetics
data
which
indicated
that
saturation
of
excretion
occurred
at
a
dose
ranging
from
>
200
to
400
mg/
kg/
day.
However,
retesting
at
a
dose
greater
than
300
mg/
kg/
day,
for
example,
would
not
be
recommended
based
on
the
saturation
data,
which
showed
evidence
of
saturation
of
excretion
at
>
200
mg/
kg/
day.
Retesting
at
a
dose
of
300
mg/
kg/
day
would
not
be
expected
to
alter
the
conclusion
that
there
was
no
carcinogenic
effect.
Since
the
doses
in
the
rat
carcinogenicity
study
(
107/
127
mg/
kg/
day)
were
within
a
factor
of
around
two
fold
of
the
saturation
point
(>
200­
400
mg/
kg/
day),
the
doses
were
considered
to
be
adequate
for
assessment
of
carcinogenicity.
Therefore,
the
DART
concluded
that
a
new
chronic
toxicity/
carcinogenicity
study
in
the
rat
was
not
required
(
TXR
No.
0053647).

Carcinogenicity
Study
in
Mice
Executive
Summary:
In
a
carcinogenicity
study
(
MRID
40872401),
groups
of
52
male
and
52
female
CD­
1
mice
were
fed
diets
containing
dicamba
(
86.8%
a.
i.;
Lot
no.
52625110)
at
0,
50,
150,
1000
or
3000
ppm
for
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
51
of
70
89
(
males)
or
104
(
females)
weeks.
These
doses
correspond
to
0,
5.5,
17.2,
108
or
358
mg/
kg
bw/
day
for
males
and
0,
5.8,
18.8,
121
or
354
mg/
kg
bw/
day
for
females.
Mortality
was
significantly
increased
in
males
at
150
ppm
and
at
3000
ppm;
the
cause
of
mortality
was
amyloidosis.
The
incidence
of
this
lesion
was
higher
than
any
other
single
factor
among
males
that
died
in
all
groups
especially
the
high
dose.
Except
for
a
significant
decrease
at
150
ppm,
survival
among
treated
females
was
comparable
to
that
of
the
controls.
Body
weight
gain
was
higher
in
treated
males
than
control
males
while
there
was
a
17%
decrease
in
body
weight
gain
in
females
at
3000
ppm.
No
treatement­
related
effects
were
seen
in
food
consumption,
hematology,
organ
weights
or
gross
pathology.
Histopathology
revealed
a
statistically
significant
(
p
<
0.05)
increase
in
lymphosarcomas
in
females
at
150
ppm
only
(
8/
52,
15%)
compared
to
controls
(
2/
52,
4%).
The
increase
was
not
considered
to
be
treatment­
related
due
to
lack
of
a
dose­
response
and
the
incidences
were
within
the
historical
control
range
(
6­
33%).
Additionally,
the
incidence
in
the
concurrent
control
(
4%)
was
below
the
historical
range.

Under
the
conditions
of
this
study,
dicamba
was
not
carcinogenic
in
male
or
female
mice
at
the
doses
tested.
The
lack
of
systemic
toxicity
indicate
that
the
animals
may
have
tolerated
higher
doses
(
i.
e.
and
MTD
was
not
achieved).
However,
the
doses
employed
in
this
study
were
approved
by
the
Agency
(
Memo:
S.
April
to
R.
Taylor,
RD,
dated
11/
15/
84).

Discussion
of
Tumor
Data:
The
administration
of
dicamba
to
mice
up
to
3000
ppm
(
358
mg/
kg/
day
for
males,
354
mg/
kg/
day
for
females)
in
the
diet
revealed
a
statistically
significant
(
p
<
0.05)
increase
in
lymphosarcomas
in
females
at
150
ppm
only
(
8/
52,
15%)
compared
to
controls
(
2/
52,
4%).
The
increase
was
not
considered
to
be
treatment­
related
due
to
lack
of
a
dose­
response
and
the
incidences
were
within
the
historical
control
range
(
6­
33%).
Additionally,
the
incidence
in
the
concurrent
control
(
4%)
was
below
the
historical
range.

Adequacy
of
the
Dose
Levels
Tested:

The
DART
revisited
the
1995
decision
by
the
RfD/
Peer
Review
Committee
that
the
mouse
carcinogenicity
study
was
not
tested
at
a
high
enough
doses
to
evaluate
carcinogenicity
in
the
mouse.
The
DART
concluded
that
3000
ppm
is
an
adequate
dose
in
the
mouse
cancer
study
and
decided
that
a
new
mouse
carcinogenicity
study
was
not
needed
(
TXR
No.
0053647).

Mutagenicity
The
RfD/
Peer
Review
Committee
reviewed
the
toxicology
database
of
dicamba
and
determined
that
mutagenicity
studies
satisfied
the
minimum
mutagenicity
testing
as
per
the
pre­
1991
guidelines
(
TXR
No.
0012037,
7/
29/
96).
Results
are
summarized
as
follow:
negative
for
Ames
(
Salmonella),
negative
for
WPU
(
E.
Coli
WP2),
negative
for
SRL
(
sex­
linked
recessive
lethal
in
Drosophila),
negative
for
YE3
(
S.
cerevisiae
mitotic
recombination
in
strain
D3),
negative
for
UDH
(
UDS
with
WI­
38
human
lung
fibroblasts),
negative
for
SAR
(
differential
toxicity
with
S.
typhimurium),
negative
for
chromosome
aberration
in
the
CHO
cells;
positive
for
REP
(
differential
toxicity
with
E.
Coli
polA),
positive
for
REW
(
differential
toxicity
with
B.
subtilis).
Other
published
studies
included
positive
UDS
in
cultured
human
lymphocytes
w/
S9,
slight
increase
of
SCE
in
cultured
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
52
of
70
human
lymphocytes
with
plus
­
minus
activity;
positive
in
an
in
vivo
assay
for
unwinding
of
liver
DNA
in
i.
p.
injected
rats
(
Environ
Milec
Mutagen
15:
131­
135,
1990);
negative
for
Salmonella
and
E.
Coli
WP2
(
Mut.
Res
116:
185­
216,
1983);
Negative
for
aberrations
in
rat
bone
marrow
(
Mut.
Res
321:
219­
228,
1994).

Structure
Activity
Relationship
Analysis
for
Carcinogenicity
The
Structure
Activity
Relationship
(
SAR)
showed
that
the
concern
level
for
carcinogenic
potential
is
low.
According
to
the
OncoLogic
Cancer
Expert
System,
there
is
a
Low­
Moderate
concern
for
para­
dichlorobenzene
but
the
substituents
of
dicamba
lower
the
concern
to
Low.
A
structurally
similar
chemical,
2,4­
D,
is
negative
for
carcinogenicity
with
a
negative
Ames
test
but
positive
chromosomal
aberration
and
CHO
tests.
Other
structurally
similar
chemicals,
5­
chlorosalicylic
acid,
dichlorobenzoic
acid,
and
chlorobenzoic
acid
have
negative
Ames
tests,
but
no
carcinogenicity
data
are
available.

OTHER
TOXICOLOGY
STUDIES
Executive
summaries
for
studies
not
described
in
the
main
body
of
the
document
are
provided
in
the
following
pages.

In
an
acute
neurotoxicity
study
(
MRID
42774104)
groups
of
Crl:
CD
BR
rats
(
10/
sex/
dose)
received
a
single
oral
(
gavage)
administration
of
dicamba
(
86.9%)
in
corn
oil
at
doses
of
0,
300,
600,
or
1200
mg/
kg.
Vehicle
controls
received
corn
oil
only.
Positive
controls
received
acrylamide
at
50
mg/
kg/
day
by
intraperitoneal
injection
on
seven
consecutive
days.
At
300
mg/
kg,
transiently
impaired
respiration;
rigidity
upon
handling,
prodding
or
dropping;
freezing
of
movement
when
touched;
decreased
arousal
and
fewer
rears/
minute
compared
to
controls;
impairment
of
gait
and
righting
reflex
were
observed
in
both
sexes.
In
addition,
males
showed
decreased
forelimb
grip
strength.
With
the
exception
of
the
decrease
in
forelimb
grip
strength,
which
persisted
until
day
seven,
these
effects
were
observed
only
on
the
day
of
dosing.
In
addition,
at
600
mg/
kg,
both
sexes
showed
decreases
in
locomotor
activity
and
males
showed
significant
decreases
in
tail
flick
reflex
and
a
raised
posture
when
placed
in
an
open
field.
These
effects
were
also
observed
only
on
the
day
of
dosing.
At
the
highest
dose
level
tested
(
1200
mg/
kg),
both
males
and
females
showed
an
impaired
startle
response
to
an
auditory
stimulus.
The
effect
was
significant
in
males
on
day
seven
and
in
females
on
the
day
of
dosing.
In
addition,
males
showed
decreases
in
body
weight
(
5
­
9%),
body
weight
gain
(
24%)
and
food
consumption
(
13%
between
days
0
and
7).
The
LOAEL
was
300
mg/
kg
based
on
the
several
neurologic
signs
listed
above;
a
NOAEL
was
not
established.
The
submitted
study
is
classified
as
acceptable/
guideline
and
satisfies
the
Guideline
requirements
for
an
acute
neurotoxicity
screening
battery
in
rats.

Subchronic
Neurotoxicity
Study
in
the
Rat
In
a
subchronic
neurotoxicity
study
(
MRID
No.
43245210),
Sprague­
Dawley
rats
(
10/
sex/
dose)
were
fed
diets
containing
dicamba
(
86.9%)
at
0,
3000,
6000,
or
12000
ppm
(
0,
197.1,
401.4,
767.9
mg/
kg/
day
for
males
and
0,
253.4,
472.0
or
1028.9
mg/
kg/
day
for
females,
respectively)
for
13
weeks.
Neurobehavioral
evaluations,
consisting
of
FOB,
locomotor
activity,
and
auditory
Dicamba
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Barcode:
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of
70
startle
response,
were
conducted
at
prestudy
and
during
Weeks
4,
8
and
13.
No
toxicologically
significant
differences
were
noted
in
either
the
mean
body
weights
or
food
consumption
of
the
treated
animals.
Neurobehavioral
evaluations
at
the
4­,
8­,
and
13­
week
evaluations
revealed
abnormal
FOB
observations
consisting
of
rigid
body
tone,
slightly
impaired
righting
reflex
and
impaired
gait.
At
Week
13
the
incidences
of
these
findings
were
decreased.
Rigid
body
tone
was
also
noted
during
evaluation
of
the
righting
reflex
and
landing
foot
splay.
The
NOAEL
was
401
mg/
kg/
day
and
the
LOAEL
was
768
mg/
kg/
day
based
on
rigid
body
tone,
slightly
impaired
righting
reflex
and
impaired
gait.
The
study
is
classified
as
acceptable/
guideline
and
satisfies
the
guideline
requirements
(
870.6200b)
for
a
subchronic
neurotoxicity
study
in
the
rat.

21/
28­
Day
Dermal
Toxicity
 
Rat
(
870.3200)

In
a
28­
day
dermal
toxicity
study
(
MRID
45814501),
Dicamba
(
91.0%
a.
i.,
batch
#
B2826511)
was
applied
to
the
shaved
skin
of
10
male
and
10
female
Alpk:
AP
f
SD
rats
/
sex/
dose
at
dose
levels
of
0,
30,
300
or
1000
mg/
kg
bw/
day,
6
hours/
day
for
5
days/
week
during
a
28­
day
period.

Clinical
observations,
body
weights
and
food
consumption
were
measured
throughout
the
study.
Urine
samples
were
taken
for
clinical
pathology
during
week
4
of
the
study.
A
functional
observational
battery
of
all
animals
consisting
of:
detailed
clinical
observations,
including
quantitative
assessments
of
landing
foot
splay,
sensory
perception
and
muscle
weakness,
and
assessment
of
motor
activity
was
performed
on
day
22.
At
the
end
of
the
scheduled
period,
the
animals
were
killed
and
subjected
to
a
post
mortem
examination.
Blood
samples
were
taken
for
clinical
pathology,
selected
organs
and
specified
tissues
were
taken
for
subsequent
histopathological
examination.

There
were
no
changes
indicative
of
systemic
toxicity
in
either
sex.
There
were
no
compound
related
effects
in
mortality,
clinical
signs,
body
weight,
food
consumption,
hematology,
clinical
chemistry,
organ
weights,
or
gross
and
histologic
pathology.
Histopathological
changes
indicative
of
irritation
were
seen
in
skin
from
the
application
site
in
both
sexes
given
1000
or
300
mg/
kg/
day
and
in
some
males
given
30
mg/
kg/
day.
A
LOAEL
for
systemic
toxicity
was
not
established.
The
NOAEL
is
1000
mg/
kg/
day
the
highest
dose
tested.

This
28­
day
dermal
toxicity
study
in
the
rat
is
acceptable/
guideline,
and
satisfies
the
guideline
requirement
for
a
28­
day
dermal
toxicity
study
(
OPPTS
870.3200
;
OECD
410)
in
the
rat.

21/
28­
Day
Dermal
Toxicity
 
Rabbit
(
870.3200)

In
a
21­
day
dermal
study
(
MRID
40547901),
New
Zealand
white
rabbits
(
5/
sex/
group)
received
15
repeated
dermal
applications
of
Dicamba
in
deionized
water
at
dose
levels
of
0,
40,
200,
or
1000
mg/
kg/
day
,
6
hours/
day,
5
days/
week
over
a
three
week
period.
No
systemic
toxicity
was
observed
at
any
dose
level.
Dose­
related
dermal
irritation
was
observed
at
the
application
sites.
Desquamation
was
seen
predominantly
in
the
1000
mg/
kg/
day
group
while
moderate
erythema,
moderate
edema
and
atonia
were
observed
exclusively
in
the
1000
mg/
kg/
day
group.
A
doserelated
incidence
of
fissuring
was
noted
in
the
200
and
1000
mg/
kg/
day
groups.
The
severity
of
acanthosis
and
the
incidence
of
hyperkeratosis
was
increased
at
these
sites
in
rabbits
at
200
and
1000
mg/
kg.
For
systemic
toxicity,
the
NOEL
was
1000
mg/
kg/
day
(
HDT);
a
systemic
LOEL
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was
not
be
established.

This
28­
day
dermal
toxicity
study
in
the
rat
is
acceptable/
guideline,
and
satisfies
the
guideline
requirement
for
a
21­
day
dermal
toxicity
study
(
OPPTS
870.3200
;
OECD
410)
in
the
rabbit.

Subchronic
Oral
Toxicity­
Rat
(
870.3100)
In
a
13­
week
subchronic
toxicity
study
(
MRID
44623101),
dicamba
technical
(
89.4%
a.
i.)
was
administered
to
HanIbm:
WIST
(
Wistar)
rats
(
10
or
20
rats/
sex/
dose)
by
feeding
at
dose
levels
of
0,
500,
3000,
6000,
or
12,000
ppm
(
equivalent
to
0/
0,
40.1/
43.2,
238.7/
266.4,
479.4/
535.6,
or
1000.0/
1065.3
mg/
kg/
day
[
M/
F])
for
13
weeks.
Following
13
weeks
of
treatment,
10
rats/
sex/
dose
were
sacrificed.
Rats
(
10/
sex)
in
the
control
and
12,000
ppm
groups
were
maintained
for
a
4­
week
recovery
period
to
determine
the
reversibility
of
effects.

No
treatment­
related
deaths
were
observed
in
any
treatment
group.
The
liver
was
the
target
organ,
as
evidenced
by
microscopic
liver
changes
associated
with
clinical
serum
chemistry
changes
and
increased
relative
(
to
body)
liver
weights
(
820­
23%)
in
both
sexes
at
the
high
dose.
The
livers
of
the
12,000
ppm
females
exhibited
slight
centrolobular
hepatocyte
hypertrophy
(
4/
10)
and
an
increased
incidence
of
minimal
to
moderate
hepatocellular
pigmentation
(
5/
10).
Both
sexes
exhibited
increased
alkaline
phosphatase
(
862­
76%),
serum
alanine
aminotransferase
(
859­
66%),
and
serum
aspartate
aminotransferase
(
829%)
activities
compared
to
the
controls.
Females
exhibited
an
increase
in
mean
gamma
glutamyl
transferase
activity
(
8136%)
while
males
showed
a
decrease
activity
(
950%)
compared
to
the
controls.

Other
effects
observed
in
the
12,000
ppm
rats
were
transient
hypothermia
(
weeks
1­
4),
reduced
activity,
slower
movements,
decreased
food
consumption,
and
less
efficient
food
utilization
than
the
controls
throughout
the
treatment
period.
Lower
mean
final
body
weights
(
918­
20%),
body
weight
gains
(
928­
40%)
and
adipose
tissue
content
were
observed
compared
to
the
controls.
Decreases
in
protein
(
910­
15%)
and
globulin
(
916­
26%)
levels
were
observed
in
both
sexes.
In
females,
decreased
mean
hemoglobin
concentration
(
94%)
and
red
blood
cell
counts
(
94%),
and
decreased
mean
corpuscular
hemoglobin
concentration
(
93%)
were
observed.
Significant
(
p<
0.05
or
p<
0.01)
increases
of
white
blood
cell
count
(
813%)
and
lymphocyte
count
(
833%)
were
observed
in
12000
ppm
females
compared
to
the
controls.
Males
had
a
lower
mean
platelet
count
(
97%)
and
shorter
partial
thromboplastin
time
(
911%)
compared
to
the
controls.
Urinalysis
showed
that
males
excreted
more
triple
phosphate
crystals
in
the
12000
ppm
group,
whereas
females
excreted
more
uric
acid
crystals
in
the
12000
and
6000
ppm
groups
at
week
12.
Following
a
4­
week
recovery
period,
all
observed
effects
were
recovered.

The
LOAEL
for
this
study
is
12,000
ppm
(
1000
mg/
kg/
day),
based
on
clinical
signs,
reduced
body
weight
gains,
hematological
and
clinical
serum
chemistry
changes
in
both
sexes,
centrolobular
hepatocyte
hypertrophy
and
hepatocellular
pigmentation
in
females,
and
increased
relative
(
to
body)
liver
weights
for
both
sexes.
The
NOAEL
is
6000
ppm
(
479
mg/
kg/
day).
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This
13­
week
subchronic
toxicity
study
is
classified
acceptable/
guideline
(
870.3100)
and
satisfies
the
guideline
requirement
for
a
subchronic
toxicity
study
in
rodents.

Chronic
Toxicity
­
Dog
(
870.4100b)

In
a
chronic
oral
toxicity
study
(
MRID
40321102),
dicamba
(
86.8,
a.
i.,
lot
#
52625110)
was
administered
to
beagle
dogs
(
4/
sex/
group)
in
diet
at
dose
levels
of
0,
100,
500,
or
2500
ppm
(
0,
2,
11,
or
52
mg/
kg/
day,
respectively)
for
one
year.

The
investiagated
parameters
in
this
study,
which
included
behavior,
mortality,
body
weight,
food
consumption,
hematology,
serum
chemistry,
urinalysis
as
well
as
macroscopic
and
histologic
examination
of
tissues,
did
not
reveal
any
apparent
adverse
effect
from
the
test
compound.
Therefore,
the
NOAEL
for
dicamba
was
2500
ppm
in
the
diet
(
about
52
mg/
kg/
day),
the
highest
dosage
administered
in
this
test;
the
absence
of
any
adverse
effects
among
treated
animals
indicated
that
the
MTD
was
not
attained.

This
one­
year
dog
study
is
classified
Acceptable/
Guideline
and
satisfies
the
guideline
requirement
for
a
chronic
toxicity
study
in
dogs.

Metabolism
­
Rat
(
870.7485)

In
a
plasma
kinetics
study,
(
MRID
44609801),
[
phenyl­
U­­
14C]­
dicamba
(
[
14C]­
dicamba;
86.0%
a.
i.
radiochemical
purity),
was
administered
as
a
dietary
admix
to
4
male
and
4
female
Wistar
and
Sprague­
Dawley
at
900,
1500,
3000,
4500,
and
12000
ppm
(
Wistar
rats)
and
900,
1500,
3000,
6000
and
9000
ppm
(
Sprague­
Dawley
rats)
for
fourteen
days,
followed
by
a
radioactive
dose
of
90,
150,
300,
450
mg/
kg
bw
(
Wistar
rats)
and
75,
125,
250,
500
and
800
mg/
kg
bw
by
a
single
gavage
dose
(
in
10
ml/
kg
body
weight
0.5%
Tylose
CB
30.000
in
aqua
bidest).
Plasma
levels
were
measured
at
various
time
intervals
following
radioactive
dose.

A
preliminary
study
in
Wistar
rats
suggests
excessive
toxicity
following
repeated
gavage
doses.
Therefore,
the
main
study
in
both
strains
of
rats
was
conducted
as
a
dietary
ad
mix
followed
by
a
gavage
dose
of
radiolabeled
dicamba.
In
both
strains
of
rats,
the
plasma
levels
reached
a
maximum
level
after
0.5­
1
hour
following
the
gavage
dose
and
declined
thereafter.
The
AUC
0­
4
values
were
calculated
from
the
plasma
concentrations
versus
time
curves
at
the
respective
dose
levels
indicated
linear
relationship
with
increase
in
dose
up
to
a
certain
dose
levels
in
both
strains
of
rats
indicating
saturation
of
excretion.
Initial
plasma
half­
life
was
increased
with
increasing
dose,
but
terminal
half­
life
remains
more
or
less
constant
in
both
strains
of
rats
indicating
saturation
of
excretion.
Plasma
half­
life
was
increased
with
increasing
dose
giving
no
indication
of
saturation
of
oral
absorption.

In
Wistar
rats,
the
increase
in
plasma
AUC
was
linear
with
dose
up
to
a
level
of
150
mg/
kg
bw
in
males
and
300
mg/
kg
bw
in
females.
Above
these
dose
levels,
plasma
AUC­
values
increased
more
than
dose.
Sprague­
Dawley
rats
showed
similar
results,
with
the
increase
in
AUC
being
linear
with
dose
up
to
a
level
of
125
and
250
mg/
kg
bw
in
males
and
females,
respectively.
Above
these
dose
Dicamba
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of
70
levels,
plasma
AUC­
values
increased
more
than
dose.
Considering
that
oral
absorption
was
not
saturated
and
that
initial
plasma
levels
went
up
with
dose,
the
disproportionate
increase
in
plasma
AUC
is
clearly
due
to
saturation
of
renal
excretion
of
dicamba
resulting
in
a
longer
plasma
half­
life.
This
is
supported
by
half­
life
data
in
both
species
which
showed
an
increase
in
plasma
half­
life
with
dose.

This
plasma
kinetics
study
in
the
rats
is
classified
Acceptable/
Nonguideline
(
§
85­
1).

Metabolism
­
Rat
(
870.7485)

In
a
plasma
pharmacokinetic
study
(
MRID
46022302),
five
groups
of
4
male
and
4
female
Wistar
rats
received
diets
containing
the
equivalent
of
50,
100,
200,
400,
or
800
mg/
kg
dicamba/
day
for
90
days
(
Lot
No.
52103810,
87.2%
a.
i.)
.
On
study
days
29,
63,
and
91,
dietary
supplementation
of
dicamba
was
stopped
and
rats
in
each
group
received
an
equivalent
gavage
dose
of
14C­
dicamba
(
Lot
No.
787­
0102,
>
99%
a.
i.,
universally
labeled
in
the
phenyl
group).
Blood
samples
were
drawn
0.5,
1,
2,
4,
6,
8,
12,
24,
and
48
hours
after
treatment
and
the
plasma
radioactivity
determined.

Absorption
of
the
radiolabeled
test
material
was
rapid,
with
peak
plasma
concentrations
found
within
2
hours
of
treatment.
Absorption
was
not
saturated,
even
at
the
highest
dose,
as
indicated
by
increasing
plasma
concentrations
with
dose.
However,
the
increase
in
plasma
concentration
was
disproportionate
from
dose
as
shown
by
the
$
2­
fold
increase
in
AUC
from
one
dose
group
to
the
next
at
doses
>
100
mg/
kg.
Elimination
of
radiolabel
from
the
plasma
was
tri­
phasic,
with
the
terminal­
phase
consistent
between
doses.
However,
the
initial
elimination
phase
increased
with
dose,
particularly
in
the
400
and
800
mg/
kg
dose
groups
and
is
consistent
with
excretion
saturation.
No
significant
treatment­
related
differences
between
the
sexes
or
time
of
radiolabel
administration
were
found.

This
plasma
pharmacokinetic
study
in
the
rat
is
classified
Acceptable/
Nonguideline
and
satisfies
its
intent.

Metabolism
­
Rat
(
870.7485)

In
a
pharmacokinetic
study
(
MRID
46022303),
two
groups
of
3
male
Wistar
rats
were
given
a
single
200
mg/
kg
gavage
dose
of
14C­
dicamba
(
Lot
No.
787­
0102,
>
99%
a.
i.,
universally
labeled
in
the
phenyl
group).
One
group
of
rats
was
pretreated
with
a
150
mg/
kg
IP
dose
of
probenecid
,
a
known
competitive
inhibitor
of
renal
anion
transport,
30
minutes
prior
to
dicamba
dosing.
Blood
samples
were
drawn
0.5,
1,
2,
4,
6,
8,
12,
24,
and
48
hours
after
gavage
treatment
and
the
plasma
radioactivity
determined.

The
time
to
peak
plasma
concentration
in
rats
treated
with
14C­
dicamba
occurred
within
0.5
hours
while
peak
plasma
concentration
was
reached
at
1.0
hour
in
the
probenecid/
dicamba
rats.
However
pretreatment
with
probenecid
increased
plasma
AUC
by
a
factor
of
1.54.
Although
the
terminal
phase
of
elimination
remained
relatively
the
same,
the
initial
and
intermediate
elimination
phases
were
increased
by
a
factor
of
two.
These
data
suggest
that
both
dicamba
and
probenecid,
act
as
inhibitors
of
renal
anion
transport.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
57
of
70
This
pharmacokinetic
study
in
the
rat
(
MRID
46022303)
is
classified
Acceptable/
Nonguideline
and
satisfies
its
intent.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
58
of
70
Appendix
B:
Use
Profile
Table
B.
1
Dicamba
Use
Profile
(
8/
2/
2005)

Use
Sites
Forms1
Max
Application
Rate
(
Unit/
Area)
Max
Application
Rate
(
year)

Non­
Food/
Non­
Feed
Uses
Agricultural
Fallow/
Idleland
(
Non­
crop)
Dimethylamine
Salt
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Agricultural
rights­
ofway
fencerows/
hedgerows
(
Non­
crop)
2
Dimethylamine
Salt,
Sodium
Salt
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)

7.7
(
lbs
a.
e./
A)
7.7
(
lbs
a.
e./
A)

Agricultural
Uncultivated
Areas
(
Non­
crop)
Dimethylamine
Salt
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Agricultural/
Farm
Structures/
Buildings
and
Equipment
(
Non­
crop)
Dimethylamine
Salt
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Airports/
Landing
Fields
(
Non­
crop)
Dimethylamine
Salt
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Commercial/
Industrial
Lawns
(
Non­
crop)
Dimethylamine
Salt
1.0
(
lbs
a.
i./
A)
1.0
(
lbs
a.
i./
A)
year
Commercial/
Institutional/
Industrial
Premises/
Equipment
(
Noncrop
Dimethylamine
Salt
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Drainage
Systems
(
Noncrop
Dimethylamine
Salt,
DGA
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Fencerows/
Hedgerows
(
Noncrop
Dimethylamine
Salt
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Forest
Plantings
(
reforestation
programs)(
tree
farms,
tree
plantations,
etc)
(
Non­
crop)
Dimethylamine
Salt
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Forest
Trees
(
Non­
crop)
Dimethylamine
Salt,
DGA
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Golf
Course
Turf
Dimethylamine
Salt,
DGA
1.0
(
lbs
a.
i./
A)
1.0
(
lbs
a.
e./
A)
year
Household
Domestic
Dwellings
(
Non­
crop)
Dimethylamine
Salt
1.0
(
lbs
a.
i./
A)
1.0
(
lbs
a.
i./
A)
year
Industrial
Areas
(
Outdoor)
(
Non­
crop)
Dimethylamine
Salt,
DGA
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
B.
1
Dicamba
Use
Profile
(
8/
2/
2005)

Use
Sites
Forms1
Max
Application
Rate
(
Unit/
Area)
Max
Application
Rate
(
year)

Page
59
of
70
Nonagricultural
Outdoor
Buildings/
Structures
(
Noncrop
Dimethylamine
Salt
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Nonagricultural
Rights­
ofway
Fencerows/
Hedgerows
(
Non­
crop)
Dimethylamine
Salt,
Sodium
Salt,
DGA
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Nonagricultural
Uncultivated
Area/
Soils
(
Non­
crop)
Dimethylamine
Salt,
DGA
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Ornamental
Lawns
and
Turf
Dimethylamine
Salt,
Sodium
Salt,
DGA
1.0
(
lbs
a.
i./
A)
1.0
(
lbs
a.
i../
A)
year
Ornamental
Sod
Farm
Dimethylamine
Salt,
DGA
1.0
(
lbs
a.
e./
A)
1.0
(
lbs
a.
e./
A)
year
Paths/
Patios
(
Non­
crop)
Dimethylamine
Salt
2.0
(
lbs
a.
e/
A)
2.0
(
lbs
a.
e./
A)
year
Paved
Areas
(
Private
Roads/
Sidewalks
(
Non­
crop)
Dimethylamine
Salt
2.0
(
lbs
a.
e/
A)
2.0
(
lbs
a.
e./
A)
year
Recreation
Area
Lawns
Dimethylamine
Salt,
DGA
1.0
(
lbs
a.
i./
A)
1.0
(
lbs
a.
i./
A)
year
Recreational
Areas
Dimethylamine
Salt,
DGA
1.0
(
lbs
a.
i./
A)
1.0
(
lbs
a.
i./
A)
year
Residential
Lawns
Dimethylamine
Salt
1.0
(
lbs
a.
i./
A)
1.0
(
lbs
a.
i./
A)
year
Urban
Areas
(
Non­
crop)
Dimethylamine
Salt
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Food/
Feed
Uses
Agricultural
Crops/
Soils
Dimethylamine
Salt,
Sodium
Salt
2.0
(
lbs
a.
e/
A)
2.0
(
lbs
a.
e./
A)
year
Agricultural
Fallow/
Idleland
All
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Agricultural/
Farm
Premises
Dimethylamine
Salt,
DGA
1.0
(
lbs
a.
e./
A)
1.0
(
lbs
a.
e./
A)
year
Agricultural/
Farm
Structures/
Buildings
and
Equipment
Dimethylamine
Salt
1.0
(
lbs
a.
e./
A)
1.0
(
lbs
a.
e./
A)
year
Asparagus
Dimethylamine
Salt,
Sodium
Salt,
DGA
0.5
(
lbs
a.
e./
A)
0.5
(
lbs
a.
e./
A)
year
Barley
Dimethylamine
Salt,
Sodium
Salt,
DGA,
IPA
0.25
(
lbs
a.
e./
A)
0.38
(
lbs
a.
e./
A)
year
Corn
(
field,
pop,
seed,
silage)
Dimethylamine
Salt,
Sodium
Salt,
DGA,
Potassium
Salt
0.5
(
lbs
a.
e./
A)
0.75
(
lbs
a.
e./
A)
year
Cotton
Dimethylamine
Salt,
DGA
0.25
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
B.
1
Dicamba
Use
Profile
(
8/
2/
2005)

Use
Sites
Forms1
Max
Application
Rate
(
Unit/
Area)
Max
Application
Rate
(
year)

Page
60
of
70
1.
There
are
5
forms
of
dicamba
used
in
this
Master
Label:
Dimethylamine
Salt
(
PC
Code
29802),
Sodium
Salt
(
PC
Code
29806),
Diglycoamine
[
DGA]
(
PC
Code
128931),
Isopropylamine
Salt
[
IPA]
(
PC
Code
128944),
and
Potassium
Salt
(
PC
Code
129043)

2.
Label
100­
884
list
7.7
lbs
a.
e./
A
as
the
maximum
rate
for
spot
treatment
for
Agricultural
right­
of­
way
uses.
The
2.0
lbs
a.
e./
A
is
what
the
registrant
stated
at
the
SMART
Meeting
as
the
rate
they
intended
to
support.

3.
Based
on
label
51036­
289
and
7969­
131
4.
Label
100­
884
list
7.7
lbs
a.
e./
A
as
the
maximum
rate
for
spot
treatment
for
pasture
uses.
The
2.0
lbs
a.
e./
A
is
what
the
registrant
stated
at
the
SMART
Meeting
as
the
rate
they
intended
to
support.

5.
Label
100­
884
list
7.7
lbs
a.
e./
A
as
the
maximum
rate
for
spot
treatment
for
rangeland
uses.
The
2.0
lbs
a.
e./
A
is
what
the
registrant
stated
at
the
SMART
Meeting
as
the
rate
they
intended
to
support.
Hay
Dimethylamine
Salt,
Sodium
Salt,
DGA
2.03
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
Millet
(
Proso)
Dimethylamine
Salt
0.125
(
lbs
a.
e/
A)
0.125
(
lbs
a.
e./
A)
year
Oats
Dimethylamine
Salt,
Sodium
Salt,
DGA
0.125
(
lbs
a.
e./
A)
1.0
(
lbs
a.
e/
A)
year
Pastures4
Dimethylamine
Salt,
Sodium
Salt,
DGA
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
7.7
(
lbs
a.
e/
A)
7.7
(
lbs
a.
e/
A)
year
Rangeland5
Dimethylamine
Salt,
Sodium
Salt,
DGA
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e./
A)
year
7.7
(
lbs
a.
e./
A
7.7
(
lbs
a.
e/
A)
year
Rye
Dimethylamine
Salt
0.5
(
lbs
a.
e./
A)
1.0
(
lbs
a.
e./
A)
year
Sorghum
All
.2748
(
lbs
a.
e./
A)
0.5
(
lbs
a.
e./
A)
year
Soybean
Sodium
Salt,
DGA
2.0
(
lbs
a.
e./
A)
2.0
(
lbs
a.
e/
A)
year
Sudangrass
Dimethylamine
Salt
0.5
(
lbs
a.
e./
A)
As
listed
for
Hay.
1.0
(
lbs
a.
e./
A)
year
Sugarcane
Dimethylamine
Salt,
Sodium
Salt,
DGA
2.8
(
lbs
a.
e./
A)
2.8
(
lbs
a.
e./
A)
year
Wheat
Dimethylamine
Salt,
Sodium
Salt,
DGA,
IPA
0.5
(
lbs
a.
e./
A)
1.0
(
lbs
a.
e./
A
)
year
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
61
of
70
Appendix
C:
TOLERANCE
REASSESSMENT
SUMMARY
The
established
tolerances
for
dicamba
are
listed
in
40
CFR
§
180.227.
There
are
three
dicamba
tolerance
expressions.
Under
40
CFR
§
180.227
(
a)(
1),
the
tolerances
are
expressed
in
terms
of
the
combined
residues
of
the
herbicide
dicamba
(
3,6­
dichloro­
o­
anisic
acid)
and
its
metabolite
3,6­
dichloro­
5­
hydroxy­
o­
anisic
acid.
The
tolerances
listed
in
40
CFR
§
180.227
(
a)(
2)
are
expressed
in
terms
of
the
combined
residues
of
dicamba
and
its
metabolite
3,6­
dichloro­
2­
hydroxybenzoic
acid.
Finally,
the
tolerances
listed
in
40
CFR
§
180.227
(
a)(
3)
are
expressed
in
terms
of
the
combined
residues
of
dicamba
and
its
metabolites
3,6­
dichloro­
5­
hydroxy­
o­
anisic
acid
and
3,6­
dichloro­
2­
hydroxybenzoic
acid.

The
results
of
plant
and
animal
metabolism
studies
suggest
that
the
various
tolerance
expressions
for
dicamba
are
appropriate.
The
results
of
a
confined
rotational
crop
study
indicate
that
tolerances
need
not
be
established
for
rotational
crops
pending
label
revisions
to
specify
appropriate
rotational
crop
restrictions.

A
summary
of
the
tolerance
reassessment
and
recommended
modifications
in
commodity
definitions
for
dicamba
is
presented
in
Table
C1.

Tolerances
Established
Under
CFR
§
180.227
(
a)(
1)

Pending
label
revisions
and/
or
adjustment
of
tolerances,
there
are
adequate
residue
data
to
reassess
the
tolerances
for:
barley,
grain,
hay,
and
straw;
corn,
field,
grain,
forage,
and
stover;
grass
forage
and
hay;
wheat
grain,
straw,
forage
and
hay;
and
sorghum
grain,
forage,
and
stover.

The
submitted
data
for
many
commodities
do
not
support
the
established
tolerances
because
they
do
not
reflect
the
maximum
use
rates
listed
in
Dicamba
Master
Use
Profile.
To
fulfill
reregistration
requirements,
the
registrant
are
required
to
submit
additional
data
for
sugarcane.
In
lieu
of
submitting
additional
data,
the
registrants
are
given
the
option
to
rely
on
the
available
data
provided
they
revise
their
product
labels
for
consistency
with
the
reviewed
data.

HED
will
allow
the
translation
of
available/
requested
data
from
some
crop
commodities
to
agronomically
related
commodities
with
identical
uses.
Where
this
situation
exists,
any
HED
recommendations
with
regards
to
label
revision
and
tolerance
reassessment
should
apply
to
both
crop
commodities.
The
following
translations
have
been
made
in
this
Residue
Chemistry
Chapter:
(
i)
data
from
field
corn
grain
and
stover
may
be
translated
to
pop
corn
grain
and
stover;
(
ii)
data
from
wheat
grain
may
be
translated
to
proso
millet
grain
and
rye
grain;
(
iii)
data
from
wheat
forage,
hay,
and
straw
may
be
translated
to
oat
forage,
hay,
and
straw;
and
(
iv)
data
from
wheat
straw
may
be
translated
to
proso
millet
straw
Pending
submission
of
supporting
storage
stability
data,
an
acceptable
sugarcane
processing
study
is
available
to
reassess
the
established
tolerance
for
sugarcane
molasses.
When
the
maximum
HAFT
combined
residue
level
(
0.183
ppm)
of
the
RAC
is
multiplied
by
the
observed
concentration
factor
for
sugarcane
molasses
(
24.4x),
the
resulting
level
is
4.465
ppm
which
is
higher
than
the
current
tolerance
of
2.0
ppm.
Based
on
these
data,
HED
recommends
that
the
tolerance
for
sugarcane
molasses
be
increased
from
2.0
ppm
to
5.0
ppm,
toxicological
considerations
permitting.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
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Page
62
of
70
The
Agency
no
longer
considers
sugarcane
forage
and
fodder
to
be
significant
livestock
feed
items,
and
these
items
have
been
deleted
from
Table
1
of
OPPTS
860.1000.
Therefore,
the
respective
tolerances
should
be
revoked.

The
generic
"
corn,
forage"
tolerance
should
be
revoked
since
a
separate
tolerance
for
field
corn
forage
is
established.
The
generic
"
corn,
stover"
tolerance
should
be
revoked
since
separate
tolerances
are
established
for
field
corn
stover
and
pop
corn
stover.
The
generic
"
corn,
grain"
tolerance
should
be
split
into:
"
corn,
field,
grain"
and
"
corn,
pop,
grain".

Tolerances
Needed
Under
CFR
§
180.227
(
a)(
1)

Tolerances
are
needed
for
proso
millet
forage
and
hay.
The
available/
requested
data
for
wheat
forage
and
hay
may
be
translated
to
proso
millet
forage
and
hay.

Tolerances
are
needed
for
rye
grain,
forage,
and
straw.
The
available/
requested
data
for
wheat
grain,
forage,
and
straw
may
be
translated
to
rye
grain,
forage,
and
straw.

Tolerances
Established
Under
CFR
§
180.227
(
a)(
2)

Pending
label
revisions
and/
or
adjustment
of
tolerance,
there
are
adequate
data
to
reassess
the
established
tolerance
for
asparagus.

A
ruminant
feeding
study
conducted
at
a
dosing
level
of
1000
ppm
is
under
review.
Assuming
this
study
is
adequate
sufficient
data
are
available
to
reassess
the
established
ruminant
tolerances.

Tolerances
Established
Under
CFR
§
180.227
(
a)(
3)

There
are
adequate
data
to
reassess
the
tolerances
for
soybean
seed
and
soybean
hulls.

An
acceptable
soybean
processing
study
is
available
to
reassess
the
established
tolerance
for
soybean
hulls.
When
the
HAFT
combined
residue
level
(
7.44
ppm)
for
the
RAC
is
multiplied
by
the
observed
concentration
factor
for
soybean
hulls
(
3.8x),
the
resulting
level
is
28.272
ppm
which
suggests
that
the
existing
tolerance
of
13.0
ppm
needs
an
upward
adjustment.
Based
on
these
data,
HED
recommends
that
the
tolerance
for
soybean
hulls
be
increased
from
13.0
ppm
to
30.0
ppm.

There
are
adequate
residue
data
on
the
aspirated
grain
fractions
of
sorghum,
soybean,
and
wheat
and
may
be
translated
to
corn.

Tolerances
That
May
Be
Needed
Under
CFR
§
180.227
(
a)(
3)

It
is
the
current
Agency
policy
to
allow
label
restrictions
on
the
feeding/
grazing
of
livestock
animals
on
soybean
forage
and
hay,
thus,
precluding
the
need
for
residue
data
and
tolerances
for
these
soybean
commodities.
HED
defers
to
RD
for
verifying
whether
such
restrictions
exist
on
product
labels.
If
such
restrictions
appear
on
the
labels,
then
residue
data
and
tolerances
for
soybean
forage
and
hay
are
not
necessary.
If
no
such
restrictions
appear
on
the
labels,
then
the
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Page
63
of
70
registrants
are
required
to
propose
tolerances
for
soybean
forage
and
hay;
based
on
the
available
data,
a
tolerance
level
of
0.1
ppm
would
be
appropriate
for
each
soybean
commodity.
Concomitant
with
these
tolerance
proposals,
the
registrants
are
required
to
propose
a
maximum
seasonal
rate
of
0.5
lb
ae/
A
for
preplant
application
on
soybean
grown
for
forage
and
hay
only.

Pending
Tolerance
Petition:

PP#
6E06209:
Interregional
Research
Project
No.
4
(
IR­
4)
has
submitted
a
petition,
on
behalf
of
the
Agricultural
Experiment
Stations
of
MN,
ND
and
WI,
proposing
the
following
permanent
tolerances
for
the
combined
residues
of
the
herbicide
dicamba
and
its
5­
hydroxy
(
5­
OH)
metabolite
(
3,6­
dichloro 
5­
hydroxy­
o­
anisic
acid)
in/
on:
sweet
corn
forage
at
1.0
ppm,
fresh
sweet
corn
at
0.1
ppm,
and
sweet
corn
stover
at
1.0
ppm.
HED's
evaluation
of
residue
data
and
analytical
methods
(
DP
Barcode
D275611,
7/
26/
2001,
G.
Kramer)
concluded
that
additional
field
residue
trials
need
to
be
conducted
and
a
revised
Section
F
must
be
submitted
before
a
favorable
recommendation
can
be
made.

Codex/
International
Harmonization
No
Codex
MRLs
have
been
established
for
dicamba;
therefore,
issues
of
compatibility
between
Codex
MRLs
and
U.
S.
tolerances
do
not
exist.
Compatibility
cannot
be
achieved
with
the
Canadian
negligible
residue
limits
or
with
Mexican
MRLs
because
these
levels
are
expressed
in
terms
of
parent
compound
only.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
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Page
64
of
70
Table
9.
Tolerance
Reassessment
Summary
for
Dicamba.

Commodity
Current
Tolerance
(
ppm)
Reassessed
Tolerance
(
ppm)
Comments/

Correct
commodity
definition
Dicamba
Tolerances
Listed
Under
40
CFR
§
180.227
(
a)(
1)

[
Expressed
in
terms
of
the
combined
residues
of
dicamba
and
its
metabolite
3,6­
dichloro­
5­
hydroxy­
o­
anisic
acid]

Barley,
grain
6.0
6.0
Barley,
hay
2.0
2.0
Barley,
straw
15.0
15.0
Corn,
field,
forage
3.0
3.0
The
combined
residues
ranged
from
<
0.01
to
2.27
ppm
in/
on
field
corn
forage
harvested
39­
71
days
following
the
last
of
three
sequential
treatments
for
a
total
of
2.75
lb
ae/
A.
The
combined
residues
ranged
from
<
0.01
to
2.45
ppm
in/
on
field
corn
fodder
harvested
66­
123
days
following
same
sequential
treatments.

Corn,
field,
stover
3.0
3.0
Corn,
forage
0.5
Revoke
The
generic
"
corn,
forage"
tolerance
should
be
revoked
since
a
separate
tolerance
for
field
corn
forage
is
established.

Corn,
grain
0.5
0.1
The
combined
residues
ranged
from
<
0.01
to
0.015
ppm
in/
on
field
corn
grain
samples
harvested
69­
123
days
following
the
last
of
three
sequential
treatments
for
a
total
of
2.75
lb
ae/
A.
The
generic
"
corn,
grain"
tolerance
should
be
split
into:
"
corn,
field,
grain";
and
"
corn,
pop,
grain".

Corn,
pop,
stover,
3.0
3.0
HED
will
allow
the
translation
of
available
data
for
field
corn
stover
to
pop
corn
stover.
Any
label
revision
for
field
corn
should
also
be
made
for
pop
corn.

Concurrently,
any
adjustment
to
the
field
corn
stover
tolerance
should
also
be
applied
as
necessary
to
the
pop
corn
stover
tolerance.

Corn,
stover
0.5
Revoke
The
generic
"
corn,
stover"
tolerance
should
be
revoked
since
separate
tolerances
are
established
for
field
corn
stover
and
pop
corn
stover.

Cotton,
undelinted
seed
5.0
TBD
Cotton,
meal
5.0
TBD
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
9.
Tolerance
Reassessment
Summary
for
Dicamba.

Commodity
Current
Tolerance
(
ppm)
Reassessed
Tolerance
(
ppm)
Comments/

Correct
commodity
definition
Page
65
of
70
Crop
Group
17
(
grass
forage,
fodder,
and
hay)
The
combined
residues
ranged
66­
358
ppm
in/
on
grass
forage
samples
harvested
immediately
(
0­
day)
following
a
single
application
at
2.0
lb
ae/
A
(
1x).
The
combined
residues
ranged
25­
201
ppm
in/
on
grass
hay
samples
harvested
7
days
following
a
single
application
1x.
Based
on
these
data,
HED
is
reassessing
the
grass
forage
tolerance
at
400
ppm
and
the
grass
hay
tolerance
at
250
ppm.

Concomitant
with
the
reassessment
of
these
tolerances,
HED
is
requesting
RD
to
verify
that
all
dicamba
labels
specify
a
0­
day
PHI/
PGI
for
grass
forage
and
a
7­

day
PHI
for
grass
hay
when
applied
at
a
maximum
of
2.0
lb
ae/
A.

­
Grass
forage
125.0
400
­
Grass
hay
200.0
250
Millet,
proso,
grain
0.5
2.0
HED
will
allow
the
translation
of
available/
requested
data
for
wheat
grain
and
straw
to
proso
millet
grain
and
straw
since
the
Dicamba
Master
Use
Profile
indicates
that
the
application
rate
of
the
two
crops
is
identical.
Any
label
revision
for
wheat
should
also
be
made
for
proso
millet.
Concurrently,
any
adjustment
to
the
wheat
grain
and
straw
tolerances
should
also
be
applied
as
necessary
to
the
proso
millet
grain
and
straw
tolerances.

Millet,
proso,
straw
0.5
TBD
Oat,
grain
0.5
2.0
HED
will
allow
the
translation
of
available/
requested
data
for
wheat
grain
to
oat
grain
since
the
Dicamba
Master
Use
Profile
indicates
that
the
application
rate
of
the
two
crops
is
identical.

Oat,
forage
80.0
2.0
HED
will
allow
the
translation
of
available/
requested
data
for
wheat
forage,
hay,

and
straw
to
oat
forage,
hay,
and
straw
since
the
Dicamba
Master
Use
Profile
indicates
that
the
application
rate
of
the
two
crops
is
identical.

Oat,
hay
20.0
TBD
Oat,
straw
0.5
30
Sorghum,
grain
3.0
4.0
The
maximum
combined
residues
were
2.73
ppm
(
MRID
43245203)
and
3.164
ppm
(
MRID
44089306)
in/
on
sorghum
grain
harvested
30­
42
days
following
sequential
treatments
for
a
total
rate
of
0.5
lb
ae/
A
(
1x
the
maximum
rate
listed
in
the
Dicamba
Master
Use
Profile).
These
data
suggest
that
the
established
tolerance
for
sorghum
grain
may
be
too
low.
Based
on
the
reviewed
data,
HED
is
recommending
a
tolerance
level
of
4.0
ppm
for
sorghum
grain
concomitant
with
label
revision
to
specify
a
30­
day
PHI.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
9.
Tolerance
Reassessment
Summary
for
Dicamba.

Commodity
Current
Tolerance
(
ppm)
Reassessed
Tolerance
(
ppm)
Comments/

Correct
commodity
definition
Page
66
of
70
Sorghum,
forage
3.0
0.5
The
maximum
combined
residues
were
0.46
ppm
(
MRID
43245203)
and
0.350
ppm
(
MRID
44089306)
in/
on
sorghum
forage
samples
harvested
20­
72
days
following
a
single
postemergence
application
at
0.25
lb
ae/
A
(
0.5x
the
seasonal
rate
listed
in
the
Dicamba
Master
Use
Profile).
The
maximum
combined
residues
were
8.22
ppm
(
MRID
43245203)
and
4.29
ppm
(
MRID
44089306)
in/
on
sorghum
fodder
(
stover)
samples
collected
at
PHIs
of
30­
42
days
following
the
last
of
two
applications
for
a
total
rate
of
0.5
lb
ae/
A
(
1x).
These
data
suggest
that
the
established
tolerance
for
sorghum
forage
may
be
too
high
and
the
tolerance
for
fodder
too
low.
Based
on
these
data,
HED
is
recommending
tolerance
levels
of
0.5
ppm
for
sorghum
forage
and
10.0
ppm
for
sorghum
stover
concomitant
with
the
following
recommended
label
revisions:
(
i)
a
20­
day
PHI
and
a
maximum
single/
seasonal
rate
of
0.25
lb
ae/
A
for
sorghum
forage;
and
(
ii)

a
30­
day
PHI
for
sorghum
fodder
(
stover)
at
a
maximum
seasonal
rate
of
0.5
lb
ae/
A.

Sorghum,
grain,
stover
3.0
10
Sugarcane,
cane
0.1
TBD
1
The
available
data
do
not
support
the
maximum
seasonal
single/
yearly
rate
of
2.8
lb
ae/
A
that
is
listed
in
the
Dicamba
Master
Use
Profile
because
the
sugarcane
trials
were
conducted
at
an
application
rate
of
2.0
lb
ae/
A.
The
maximum
combined
residues
were
0.202
ppm
in/
on
sugarcane
harvested
87­
173
days
following
a
single
layby
application
at
2.0
lb
ae/
A.

The
registrants
are
required
to
submit
additional
data
on
sugarcane
reflecting
a
maximum
single/
yearly
rate
of
2.8
lb
ae/
A.
Alternatively,
the
registrants
may
rely
on
the
available
data
provided
they
are
willing
to
revise
their
product
labels
for
consistency
with
the
reviewed
data.
If
the
registrants
elect
to
choose
the
latter
option,
then
they
will
be
required
to
revise
product
labels
to
specify
a
maximum
seasonal
rate
of
2.0
lb
ae/
A
and
an
87­
day
PHI
for
sugarcane.
Based
on
the
reviewed
data,
the
existing
tolerance
of
0.1
ppm
for
sugarcane
is
too
low,
and
HED
is
recommending
that
it
be
reassessed
at
0.3
ppm
if
the
registrants
elect
to
revise
product
labels
as
detailed
above.

Sugarcane,
fodder
0.1
Revoke
These
items
are
no
longer
regulated
and
have
been
removed
from
Table
1
of
OPPTS
860.1000.

Sugarcane,
forage
0.1
Revoke
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
9.
Tolerance
Reassessment
Summary
for
Dicamba.

Commodity
Current
Tolerance
(
ppm)
Reassessed
Tolerance
(
ppm)
Comments/

Correct
commodity
definition
Page
67
of
70
Sugarcane,
molasses
2.0
5.0
When
the
maximum
HAFT
combined
residue
level
(
0.183
ppm)
of
the
RAC
is
multiplied
by
the
observed
concentration
factor
for
sugarcane
molasses
(
24.4x),

the
resulting
level
is
4.465
ppm
which
is
higher
than
the
current
tolerance
of
2.0
ppm.
Based
on
these
data,
HED
recommends
that
the
tolerance
for
sugarcane
molasses
be
increased
from
2.0
ppm
to
5.0
ppm,
pending
submission
of
supporting
storage
stability
data.

Wheat,
forage
80.0
TBD
Additional
data
are
currently
under
review.

Wheat,
grain
2.0
2.0
The
combined
residues
were
<
0.01
to
0.15
ppm
in/
on
samples
of
wheat
grain
harvested
63­
125
days
following
one
spring
broadcast
application
at
0.25
lb
ae/
A.

The
combined
residues
were
0.039
to
1.4
ppm
in/
on
grain
samples
harvested
6­
12
days
following
the
last
of
two
treatments
for
a
total
of
0.5
lb
ae/
A.

Wheat,
hay
20.0
TBD
Additional
data
are
currently
under
review.

Wheat,
straw
30.0
30.0
The
combined
residues
were
0.011
to
0.97
ppm
in/
on
samples
of
wheat
straw
harvested
63­
125
days
following
one
spring
broadcast
application
at
0.25
lb
ae/
A.

The
combined
residues
were
0.13
to
26
ppm
in/
on
straw
samples
harvested
6­
12
days
following
the
last
of
two
treatments
for
a
total
of
0.5
lb
ae/
A.

Dicamba
Tolerances
Needed
Under
40
CFR
§
180.227(
a)(
1)

Millet,
proso,
forage
None
TBD
HED
will
allow
the
translation
of
available/
requested
data
for
wheat
forage
and
hay
to
proso
millet
forage
and
hay
since
the
Dicamba
Master
Use
Profile
indicates
that
the
application
rate
for
wheat
is
slightly
higher
than
millet.

Millet,
proso,
hay
None
TBD
Rye,
grain
None
2.0
HED
will
allow
the
translation
of
available/
requested
data
for
wheat
grain,

forage,
and
straw
to
rye
grain,
forage,
and
straw
since
the
Dicamba
Master
Use
Profile
indicates
that
the
yearly
application
rate
of
the
two
crops
is
identical.

Rye,
forage
None
TBD
Rye,
straw
None
30.0
Dicamba
Tolerances
Listed
in
40
CFR
§
180.227
(
a)(
2)

[
Expressed
in
terms
of
the
combined
residues
of
dicamba
and
its
metabolite
3,6­
dichloro­
2­
hydroxybenzoic
acid]

Asparagus
4.0
4.0
Th
combined
residues
ranged
0.28­
3.29
ppm
in/
on
asparagus
samples
harvested
24
hours
following
a
single
application
at
1x
the
maximum
rate
listed
in
the
Dicamba
Master
Use
Profile.
These
data
support
the
currently
established
tolerance
of
4.0
ppm
on
asparagus
pending
verification
by
RD
that
the
label
PHI
for
asparagus
is
24
hours
or
1
day.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
9.
Tolerance
Reassessment
Summary
for
Dicamba.

Commodity
Current
Tolerance
(
ppm)
Reassessed
Tolerance
(
ppm)
Comments/

Correct
commodity
definition
Page
68
of
70
Cattle,
fat
0.2
0.3
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Cattle,
kidney
1.5
25
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Cattle,
liver
1.5
Revoke
Residues
in
liver
will
be
covered
by
redefined
meat
by­
products
tolerance.

Cattle,
meat
byproducts
0.2
3.0
Cattle,
meat
by­
products,
except
kidney.
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Cattle,
meat
0.2
0.25
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Goat,
fat
0.2
0.3
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Goat,
kidney
1.5
25
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Goat,
liver
1.5
Revoke
Residues
in
liver
will
be
covered
by
redefined
meat
by­
products
tolerance.

Goat,
meat
byproducts
0.2
3.0
Goat,
meat
by­
products,
except
kidney
Goat,
meat
0.2
0.25
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Hog,
fat
0.2
0.3
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Hog,
kidney
1.5
25
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Hog,
liver
1.5
Revoke
Residues
in
liver
will
be
covered
by
redefined
meat
by­
products
tolerance.

Hog,
meat
byproducts
0.2
3.0
Hog,
meat
by­
products,
except
kidney
Hog,
meat
0.2
0.25
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Horse,
fat
0.2
0.3
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
9.
Tolerance
Reassessment
Summary
for
Dicamba.

Commodity
Current
Tolerance
(
ppm)
Reassessed
Tolerance
(
ppm)
Comments/

Correct
commodity
definition
Page
69
of
70
Horse,
kidney
1.5
25
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Horse,
liver
1.5
Revoke
Residues
in
liver
will
be
covered
by
redefined
meat
by­
products
tolerance.

Horse,
meat
byproducts
0.2
3.0
Horse,
meat
by­
products,
except
kidney
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Horse,
meat
0.2
0.25
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Milk
0.3
0.2
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Sheep,
fat
0.2
0.3
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Sheep,
kidney
1.5
25
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Sheep,
liver
1.5
Revoke
Residues
in
liver
will
be
covered
by
redefined
meat
by­
products
tolerance.

Sheep,
meat
byproducts
0.2
3.0
Sheep,
meat
by­
products,
except
kidney
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Sheep,
meat
0.2
0.25
Reassessed
values
are
based
on
a
new
ruminant
feeding
study
currently
under
review.

Dicamba
Tolerances
Under
40
CFR
§
180.227(
a)(
3)

[
Expressed
in
terms
of
the
combined
residues
of
dicamba
and
its
metabolites
3,6­
dichloro­
5­
hydroxy­
o­
anisic
acid
and
3,6­
dichloro­
2­
hydroxybenzoic
acid]

Grain,
aspirated
grain
fractions
5100
1000
There
are
adequate
residue
data
on
the
aspirated
grain
fractions
of
sorghum,

soybean,
and
wheat,
and
can
be
translated
to
corn.

Soybean,
hulls
13.0
30.0
When
the
maximum
HAFT
combined
residue
level
(
7.44
ppm)
of
the
RAC
is
multiplied
by
the
observed
concentration
factor
for
soybean
hulls
(
3.8x),
the
resulting
level
is
28.272
ppm
which
suggests
that
the
existing
tolerance
of
13.0
ppm
is
too
low.
HED
recommends
that
the
tolerance
for
soybean
hulls
be
increased
from
13.0
ppm
to
30.0
ppm.
Dicamba
Human
Health
Risk
Assessment
­
Phase
I
Barcode:
D317720
Table
9.
Tolerance
Reassessment
Summary
for
Dicamba.

Commodity
Current
Tolerance
(
ppm)
Reassessed
Tolerance
(
ppm)
Comments/

Correct
commodity
definition
Page
70
of
70
Soybean,
seed
10.0
10.0
The
highest
total
residues
were
8.13
ppm
in/
on
samples
of
soybean
seed
harvested
6­
8
days
following
treatments
at
1.25x
the
maximum
rate
listed
in
the
Dicamba
Master
Use
Profile.

Dicamba
Tolerances
That
May
Be
Needed
Under
40
CFR
§
180.227(
a)(
3)

Soybean,
forage
None
TBD
It
is
the
current
Agency
policy
to
allow
label
restrictions
on
the
feeding/
grazing
of
livestock
animals
on
soybean
forage
and
hay,
thus,
precluding
the
need
for
residue
data
and
tolerances.
HED
defers
to
RD
for
verifying
whether
such
restrictions
exist
on
product
labels.
If
such
restrictions
appear
on
the
labels,
then
residue
data
and
tolerances
for
soybean
forage
and
hay
are
not
necessary.
If
no
such
restrictions
appear
on
the
labels,
then
the
registrants
are
required
to
propose
tolerances
for
soybean
forage
and
hay;
based
on
the
available
data,
a
tolerance
level
of
0.1
ppm
would
be
appropriate
for
each
soybean
commodity.

Concomitant
with
these
tolerance
proposals,
the
registrants
are
required
to
propose
a
maximum
seasonal
rate
of
0.5
lb
ae/
A
for
preplant
application
on
soybean
grown
for
forage
and
hay.

Soybean,
hay
None
TBD
1
TBD
=
To
be
determined.
Additional
data/
information
are
required
for
tolerance
reassessment.
